DE19961964A1 - Aqueous dispersion of a polymer and fine particulate inorganic particles, useful as an adhesive, is prepared by a radical aquoeus emulsion polymerization in the presence of the dispersed particles. - Google Patents

Abstract

An aqueous dispersion (I) of a polymer and fine particulate inorganic particles is prepared by a radical aquoeus emulsion polymerization of an ethylenically unsaturated monomer dispersed in an aqueous medium using a radical initiator in the presence of a dispersed fine particle inorganic solid and a dispersing agent. A process for the preparation of an aqueous dispersion of a polymer and fine particulate inorganic particles comprises radical aquoeus emulsion polymerization of an ethylenically unsaturated monomer dispersed in an aqueous medium using a radical initiator in the presence of a dispersed fine particle inorganic solid and a dispersing agent. The process is characterized by (A) a stable aqueous dispersion containing inorganic material having an initial solids content of at least 1 wt.%, which, one hour after its preparation, retains more than 90 wt.% of the dispersed solids in dispersed form having an average diameter of less than or equal to 100 nm. (B) the dispersion comprising inorganic particles in a standard aqueous alkali chloride solution has a different electrophoretic mobility to the null point at a pH corresponding to the initial pH of the aqueous reaction medium (C) the radical producing component has a electrical charge that is opposite in sign to the electrophoretic mobility of the dispersed particles in a standard aqueous alkali chloride solution at a pH corresponding to the initial pH of the reaction medium. Independent claims are included for (i) an aqueous dispersion (I) of composite particles prepared by the process and (ii) a composite particle powder prepared by drying the dispersion (I).

Description

The present invention relates to a process for the preparation an aqueous dispersion of polymer and finely divided Inorganic solid particles (composite particles), wherein at least one ethylenically unsaturated monomer in aqueous medium disperse distributed and by means of at least one radical polymerization initiator in the presence at least a dispersed, finely divided inorganic solid and at least one dispersing agent according to the method of free-radically aqueous emulsion polymerization is polymerized.

Furthermore, the invention relates to aqueous dispersions of composite particles and their use as well as composite particle powder.

Aqueous dispersions of composite particles are generally be known. These are fluid systems that act as a disperse phase in aqueous dispersion medium of several into each other entangled polymer chains existing polymer ball, the so-called polymer matrix, and finely divided inorganic Solid particles are in disperse distribution contain. The diameter of the composite particles is often in the Range from 50 nm to 5000 nm.

As well as polymer solutions on evaporation of the solvent and aqueous polymer dispersions on evaporation of the aqueous dispersion medium, have aqueous dispersions of Composite particles have the potential to form modified, finely divided inorganic solid-containing polymer film on, which is why they especially as a modified bandage medium, z. For paints or for coating of leather, paper or plastic films of interest. The from aqueous dispersions of composite particles in principle In addition, composite particulate powders are also known as Additives for plastics, components for toner formulations or additives in electrophotographic applications of Interest.

In the preparation of aqueous dispersions of composite particles is to be assumed from the following state of the art.  

A process for the preparation of polymers encased anorga niche particles by aqueous emulsion polymerization is disclosed in US-A 3,544,500. In this process, the inorganic particles before the actual aqueous emulsions Polymerization coated with water-insoluble polymers. The Dispersion of the treated so in a complex process on organic particles in aqueous medium by means of special stabilizers.

EP-A 104 498 relates to a process for the preparation of Polymer-coated solids, Characteristic of the process is that finely divided solids, which is a minimum Ober Have surface charge, by means of a non-ionic protection colloid dispersed in aqueous polymerization medium and the added ethylenically unsaturated monomers by not ionic polymerization initiators are polymerized.

US-A 4,421,660 discloses a process for the preparation of aqueous dispersions whose dispersively present particles anor ganic particles which completely migrate from a polymer shell are present. The preparation of the aqueous dispersions takes place by free-radically initiated aqueous emulsion polymers hydrophobic, ethylenically unsaturated monomers in Presence of dispersed inorganic particles.

A process for the polymerization of ethylenically unsaturated Monomers in the presence of charge-free inorganic solid fabric particles which are mixed with nonionic dispersants in aqueous reaction medium is stabilized in the US-A 4,608,401.

The free-radically initiated aqueous emulsion polymerization of Styrene in the presence of modified silica particles is described by Furusawa et al. in the Journal of Colloid and Interface Science 1986, 109, pages 69-76. The modification the spherical silica particles having a middle one Particle diameter of 190 nm is carried out by means of hydroxypropyl cellulose.

Hergeth et al. (see Polymer, 1989, 30, pages 254 to 258) be describe the free-radically initiated aqueous emulsion polymer sation of methyl methacrylate or vinyl acetate in the presence of aggregated finely divided quartz powder. The particle sizes of the used aggregated quartz powder are between 1 micron and 35 μm.  

GB-A 2 227 739 relates to a special emulsion polymer tion method in which ethylenically unsaturated monomers in Presence of dispersed inorganic powders which cat have ionic charges, using ultrasound be polymerized waves. The cationic charges of the disper Giert solid particles are by treatment of the particles produced with cationic agents, with aluminum salts being preferred are. The font, however, contains no information regarding part chengrößen and stability of the aqueous solid dispersions.

In EP-A 505 230, the free-radically aqueous emulsion poly merization of ethylenically unsaturated monomers in the presence of surface-modified silica particles. Their functionalization is carried out by means of special silanol group-containing acrylic acid ester.

US Pat. No. 4,981,882 relates to the production of composite particles by means of a special emulsion polymerization process. Ver essential for driving are finely divided inorganic particles which by means of basic dispersants in aqueous medium disper g., treating these inorganic particles with ethylenically unsaturated carboxylic acids and adding at least an amphiphilic component for stabilizing the solid dis persion during the emulsion polymerization. The finely divided Organic particles preferably have a particle size between 100 and 700 nm.

Haga et al. (see The Applied Macromolecular Chemistry 1991, 189, pages 23 to 34) describe the influence of species and Concentration of monomers, type and concentration of poly merisationsinitiators and the influence of the pH on the Polymer formation on titanium dispersed in aqueous medium dioxidteilchen. High yields in the encapsulation of titanium Dioxide particles are obtained when the polymer chains and the Titanium dioxide particles have opposite charges (see. o. g. Publication, Chapter 3.1 Polymerization behavior on encapsu lation and Chapter 4 Conclusion). The publication, however, contains No information regarding the particle size and the stability of the Titanium dioxide dispersions.

Long et al. describe in Tianjin Daxue Xuebao 1991, 4, Pages 10 to 15 the dispersant-free polymerization of Methyl methacrylate in the presence of finely divided silica or aluminum particles. Good yields in the encapsulation of Inorganic particles are obtained when the end groups of the  Polymer chains and the inorganic particles opposite La have.

EP-A 572 128 relates to a method of manufacturing Kompositpar particles, in which the inorganic particles in aqueous medium at a certain pH with an organic polyacid or their salt is treated and then carried through introduced radically initiated aqueous emulsion polymerization of ethylenically unsaturated monomers at a pH ≦ 9 er follows.

Bourgeat-Lami et al. (See The Applied Macromolecular Chemistry 1996, 242, pages 105 to 122) describe by radical aqueous emulsion polymerization of ethyl acrylate in the presence functionalized and non-functionalized silica particle accessible reaction products. In the polymerization Experiments were generally anionically charged silica particle, the nonionic nonylphenol ethoxylate NP30 and the ionic sodium dodecyl sulfate (SDS) as emulsifiers and potassium peroxodisulfate as a radical polymerization initiator used. The authors describe the incurred reaction pro as aggregates containing more than one silica particle hold or as a polymer cluster, focusing on the silica form surface.

Paulke et al. (see Synthesis Studies of Paramagnetic Poly styrene latex particles in Scientific and Clinical Applications of Magnetic Carriers, pages 69 to 76, Plenum Press, New York, 1997) describe three principal synthetic routes to Her position of aqueous iron oxide-containing polymer dispersions. Due to insufficient stability of the aqueous solid Dispersion is the use of fresh for all synthetic routes precipitated iron (II / III) oxide hydrate indispensable requirement. In the presence of this freshly precipitated iron (II / III) oxide hydrate takes place in the first synthesis route the radically initiated aqueous emulsion polymerization of styrene with SDS as emulsifier and potassium peroxodisulfate as a polymerization initiator. In the of The authors favored the second synthesis route is styrene and Methacrylic acid in the presence of freshly precipitated iron (II / III) - oxide hydrate, the emulsifier N-cetyl-N-trimethylammonium bromide (CTAB) and special surface-active polymerization initiators (PEGA 600) in methanolic / aqueous medium polymerized. In the third synthesis route are ethanol and Methoxyethanol as a polymerization medium, hydroxypropyl cellulose as an emulsifier, benzoyl peroxide as a polymerization initiator and  a special iron (II / III) oxide / styrene mixture for Her position of iron oxide-containing polymer dispersions used.

In Japanese Patent Application JP 11-209 622 is a Process for producing core / shell particles disclosed which comprises a core of a silica particle and a poly merschale have. The preparation of the core / shell particles he follows such that the colloidally present in aqueous medium silica particles with a cationic vinyl mono or pretreated a cationic radical initiator who and then a radically initiated aqueous Emulsion polymerization with ethylenically unsaturated monomers he follows.

Armes et al. (see Advanced Materials 1999, 11, No. 5, Pages 408 to 410) describe the preparation of silicon di oxide composite particles, which in an emulsifier-free, radika lisch initiated aqueous emulsion polymerization with special olefinically unsaturated monomers in the presence of disper gured silica particles are accessible. As a prerequisite for the formation of silicon dioxide-containing polymer particles will form a strong acid / base interaction between the structure polymers and the acidic silica particles used postulated. Silica-containing polymer particles were with Poly-4-vinylpyridine and copolymers of styrene and methylmeth obtained acrylate with 4-vinylpyridine.

Object of the present invention was, in view of the vorste prior art, another method of manufacture an aqueous dispersion of composite particles by the method the radically initiated aqueous emulsion polymerization for To provide, which the disadvantages of the known Verfah not or only to a lesser extent.

Accordingly, a process for the preparation of an aqueous dispersion of polymer particles and finely divided inorganic solid composite material is provided, in which at least one ethylenically unsaturated monomer is dispersed in an aqueous medium and distributed by at least one radicalic polymerization initiator in the presence of at least one dispersed, finely divided inorganic solid and at least one dispersant is polymerized by the method of radically aqueous emulsion polymerization, characterized in that

• a) a stable aqueous dispersion of the at least one anorga nical solid is used, which characterize characterized is that they are at an initial solids concentration from ≧ 1 wt .-%, based on the aqueous dispersion of the at least one solid, one hour after her position more than 90 wt .-% of the originally dispersed Contains solid in dispersed form and their disper solid particles have a weight-average diameter ≦ 100 nm,
• b) the dispersed solid particles of the at least one organic solid in a standard aqueous potassium chloride solution at a pH that matches the pH of the aqueous reaction medium at the beginning of the emulsion corresponds to a nonzero electro show phoretic mobility

and

• a) the radical-generating component of the at least one radika metallic polymerization initiator and / or the dispersing acting component of the at least one dispersant have at least one electrical charge whose Vorzei opposite to the sign of the electrophoretic Mobility of the dispersed solid particles of at least a solid is this in an aqueous standard potassium chloride solution at a pH which is equal to the pH Value of the aqueous reaction medium at the beginning of the emulsion corresponds to polymerization.

For the method according to the invention, all those are fine suitable inorganic solids, which are stable form aqueous dispersions which are at an initial solids concentration of ≧ 1 wt .-%, based on the aqueous dispersion of at least one solid, one hour after her position more than 90 wt .-% of the originally dispersed solid contained in dispersed form and their dispersed Solid particles have a weight-average diameter ≦ 100 nm and, moreover, at a pH equal to the pH the aqueous reaction medium at the beginning of the emulsion sation, a non-zero electrophoretic Show mobility.

As inventively usable finely divided inorganic solids are metals, metal compounds such as metal oxides and metal salts but also semi-metal and non-metal compounds ge is suitable. As finely divided metal powder noble metal colloids, such as palladium, silver, ruthenium, platinum, gold and rhodium and alloys containing them can be used. Examples of finely divided metal oxides which may be mentioned are titanium dioxide (for example commercially available as Hombitec® grades from Sachtleben Chemie GmbH), zirconium (IV) oxide, tin (II) oxide, tin (IV) oxide (for example commercially available as Nyacol® SN grades from Akzo-Nobel), alumina (for example, commercially available as Nyacol® AL grades from Akzo-Nobel), barium oxide, magnesium oxide, various iron oxides, such as iron (II) oxide (wuestite), iron (III) oxide (hematite) and iron (II / III) oxide (magnetite), chromium (III) oxide, anti-mon (III) oxide, bismuth ( III) oxide, zinc oxide (for example commercially available as Sachtotec® brands from Sachtleben Chemie GmbH), nickel (II) oxide, nickel (III) oxide, cobalt (II) oxide, cobalt ( III) oxide, copper (II) oxide, yttrium (III) oxide (for example, commercially available as Nyacol® YTTRIA brands from Akzo-Nobel), cerium (IV) oxide (for example, commercially available as Nyacol® CEO2 brands from Akzo-Nobel ) amorphous and / or in their different crystal modifications and their hydroxy oxides, such as hydroxytitanium (IV) oxide, hydroxyzirconium (IV) oxide, hydroxyaluminum oxide (for example, commercially available as Disperal® brands Fa. Condea-Chemie GmbH) and hydroxyiron (III) oxide amorphous and / or in their different crystal modifications. The following amorphous and / or metal salts present in their different crystal structures can be used in principle in the process according to the invention: sulfides, such as iron (II) sulfide, iron (III) sulfide, iron (II) disulfide (pyrite), tin (II) sulfide, tin (IV) sulfide, mercury (II) sulfide, cadmium (II) sulfide, zinc sulfide, copper (II) sulfide, silver sulfide, nickel (II) sulfide, Cobalt (II) sulfide, cobalt (III) sulfide, manganese (II) sulfide, chromium (III) sulfide, titanium (II) sulfide, titanium (III) sulfide, titanium (IV) sulfide, zirconium (IV) sulfide, antimony (III) sulfide, bismuth (III) sulfide, hydroxides such as stannous hydroxide, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, Zinc hydroxide, iron (II) hydroxide, iron (III) hydroxide, sulfates, such as calcium sulfate, strontium sulfate, barium sulfate, lead (IV) sulfate, carbonates, such as lithium carbonate, magnesium carbonate, calcium carbonate, zinc carbonate, zirconium ( IV) carbonate, iron (II) carbonate, iron (III) carbonate, Ortho phosphate e, such as lithium orthophosphate, calcium orthophosphate, zinc orthophosphate, magnesium orthophosphate, aluminum orthophosphate, tin (III) orthophosphate, iron (II) orthophosphate, iron (III) orthophosphate, metaphosphates, such as lithium metaphosphate, calcium metaphosphate, aluminum metaphosphate, pyrophosphates, such as magnesium pyrophosphate, calcium pyrophosphate, zinc pyrophosphate, iron (III) pyrophosphate, stannous pyrophosphate, ammonium phosphates such as magnesium ammonium phosphate, zinc ammonium phosphate, hydroxyapatite [Ca ₅ {(PO ₄ ) ₃ OH}], orthosilicates such as lithium orthosilicate , Calcium / magnesium orthosilicate, aluminum orthosilicate, iron orthosilicates, magnesium orthosilicate, zinc orthosilicate, zirconium orthosilicates, metasilicates such as lithium metasilicate, calcium / magnesium metasilicate, calcium metasilicate, magnesium meta silicate, zinc metasilicate, phyllosilicates such as sodium aluminum silicate and sodium magnesium silicate especially in spontaneously dela minierender form such as Optigel ® SH (brand of S üd chemie AG), Saponit® SKS-20 and Hektorit® SKS 21 (trademarks of Hoechst AG) and Laponite® RD and Laponite® GS (trademarks of Laporte Industries Ltd.), aluminates such as lithium aluminate, calcium aluminate, zinc aluminate, borates such as Magnesium metaborate, magnesium orthoborate, oxalates such as calcium oxalate, zirconium (IV) oxalate, magnesium oxalate, zinc oxalate, aluminum oxalate, tartrates such as calcium acetate, acetylacetonates such as aluminum acetyl acetonate, iron (III) acetylacetonate, salicylates such as aluminum salicylate, citrates, such as calcium citrate, iron (II) citrate, zinc citrate, palmitates such as aluminum palmitate, calcium palmitate, magnesium palmitate, stearates such as aluminum stearate, calcium stearate, magnesium stearate, zinc stearate, laurates such as calcium laurate, linoleates such as calcium linoleate, oleates such as calcium oleate , Iron (II) oleate or zinc oleate.

As essential inventively usable semimetal compound be amorphous and / or in different crystal structures called the present silica. According to the invention suitable Silicon dioxide is commercially available and may be, for example as Aerosil® (trademark of Degussa AG), Levasil® (trademark of Bayer AG), Ludox® (trademark of DuPont), Nyacol® and Bindzil® (trademarks of Akzo-Nobel) and Snowtex® (trademark of Nissan Chemical Industries, Ltd.). Fiction suitable non-metal compounds are, for example colloidal graphite or diamond.

Leave as at least one finely divided inorganic solid Furthermore, use all the above compounds whose upper surfaces with polymeric compounds or inorganic materials were modified.

As finely divided inorganic solids such are particularly ge its solubility in water at 20 ° C and 1 bar (absolute) ≦ 1 g / l, preferably ≦ 0.1 g / l and in particular ≦ 0.01 g / l. Particular preference is given to compounds selected from the group comprising silica, alumina, stannic oxide, Yttrium (III) oxide, cerium (IV) oxide, hydroxyaluminum oxide, calcium carbonate, magnesium carbonate, calcium orthophosphate, magnesium ore  thophosphate, calcium metaphosphate, magnesium metaphosphate, calcium pyrophosphate, magnesium pyrophosphate, iron (II) oxide, iron (III) oxide, iron (II / III) oxide, titanium dioxide, hydroxyapatite, Zinc oxide and zinc sulfide.

Advantageously, the commercially available compounds the Aerosil®, Levasil®, Ludox®, Nyacol® and Bindzil® grades (Silica), Disperal® grades (hydroxyaluminum oxide), Nyacol® AL grades (aluminum oxide), Hömbitec® grades (Titanium Nyacol® SN grades (tin (IV) oxide), Nyacol® YTTRIA Trademarks (yttrium (III) oxide), Nyacol® CEO2 grades (cerium (IV) oxide) and Sachtotec® grades (zinc oxide) in the process of the invention be used.

The usable in the process according to the invention finely Organic solids are such that the in the aqueous Reaction medium dispersed solid particles a weight having average particle diameter of ≦ 100 nm. Successfully such finely divided inorganic solids are used, their dispersed particles have a weight-average particle diameter <0 nm but ≦ 90 nm, ≦ 80 nm, ≦ 70 nm, ≦ 60 nm, ≦ 50 nm, ≦ 40 nm, ≦ 30 nm, ≦ 20 nm or ≦ 10 nm and all values in between. The determination of the weight-average Particle diameter can be determined, for example, by the method of Ana lytic ultracentrifuge (see, for example, S. E. 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 Cel1-AUC Multiplexer: High Resolution Particle Size Distribution and Density Gradient Techniques, W. Mächtle, pages 147 to 175).

The accessibility of finely divided solids is known to those skilled in the art in principle known and takes place for example by precipitation reaction or chemical reactions in the gas phase (cf. E. Matijevic, Chem. Mater. 1993, 5, pages 412 to 426; Ullmann's Encyclopedia of Industrial Chemistry, Vol. A 23, pages 583 to 660, Verlag Chemie, Weinheim, 1992; D.F. Evans, H. Wennerström in The Colloidal Domain, pages 363 to 405, Verlag Chemie, Weinheim, 1994 and R. J. Hunter in Foundations of Colloid Science, Vol. I, pages 10 to 17, Clarendon Press, Oxford, 1991).

The preparation of the stable solid dispersion is carried out by Dispersing the finely divided inorganic solid in the aqueous medium. Depending on the production route of the solids succeed this either directly, for example when precipitated or pyroge  nem silica, alumina, etc. or by addition appro priate ter auxiliaries, such as dispersants.

In general, in the context of the method according to the invention Used dispersing agent, both the finely divided anor ganic solid particles as well as the monomer droplets and the composite particles formed in the aqueous phase disperses keep it distributed and so the stability of the produced aqueous Ensuring composite particle dispersion. As a dispersant Both come to carry out radical aqueous Emulsion polymerizations commonly used protection colloids and emulsifiers into consideration.

Suitable protective colloids are, for example, polyvinyl alcohols, Polyalkylene glycols, alkali metal salts of polyacrylic acids and Polymethacrylic acids, cellulose, starch and gelatin derivatives or acrylic acid, methacrylic acid, maleic anhydride, 2-acrylic amido-2-methylpropanesulfonic acid and / or styrenesulfonic ent but also holding copolymers and their alkali metal salts N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylcarbazole, 1-vinyl imidazole, 2-vinylimidazole, 2-vinylpyridine, 4-vinylpyridine, acrylic amide, methacrylamide, amine group-bearing acrylates, methacrylates, Acrylamides and / or methacrylamides containing homo- and copoly merisate and their nitrogen protonated and / or alky derivatives. Examples of these are N-dimethylaminoethyl acrylate, N-diethylaminoethyl acrylate, N-dimethylaminoethyl meth acrylate, N- (3-dimethylaminopropyl) methacrylamide, tert-butyl aminoethyl methacrylate, 2-N-Benzyldimethylammoniumethylmethacryl acid ester chloride, 2-N-trimethylammoniumethylmethacrylic acid ester chloride, 2-N-Benzyldimethylammoniumethylacrylsäureesterchlo and 1-hydroxyethyl-imidazolin-2-one methacrylate. A detailed The description of other suitable protective colloids can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Ma Kromolekulare Stoffe, Georg Thieme Verlag, Stuttgart, 1961, Sei 411 to 420. Particularly suitable according to the invention are anionic protective colloids, d. H. Protective colloids whose dispersing acting component at least one negative electric charge such as alkali metal salts of polyacrylic acids and polyme thacrylic acids, acrylic acid, methacrylic acid, 2-acrylamido-2-methyl propanesulfonic acid, styrenesulfonic acid and / or maleic anhydride containing copolymers and their alkali metal salts and Alkali metal salts of sulfonic acids of high molecular weight compounds, such as polystyrene and cationic protective colloids, d. H. Protective colloids whose dispersing component we has at least one positive electric charge, such as for example, the nitrogen protonated and / or alkylated th derivatives of N-vinylpyrrolidone, N-vinylcaprolactam, N-vinyl  carbazole, 1-vinylimidazole, 2-vinylimidazole, 2-vinylpyridine, 4-vinylpyridine, acrylamide, methacrylamide, amine group-bearing. Acrylates, methacrylates, acrylamides and / or methacrylamides ent holding homopolymers and copolymers.

Of course, mixtures of emulsifiers and / or Protective colloids are used. Frequently used as a dispersant used exclusively emulsifiers whose relative Molecular weights, in contrast to the protective colloids more usual way below 1500 lie. They can be both anionic, cat ionic or nonionic nature. Of course must be more active in the case of the use of mixtures Substances the individual components are compatible with each other, which can be checked in case of doubt on the basis of fewer preliminary tests can. In general, anionic emulsifiers are among themselves and compatible with nonionic emulsifiers. The same applies also for cationic emulsifiers, while anionic and cat ionic emulsifiers are usually incompatible with each other. An overview of suitable emulsifiers can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular Fabrics, Georg Thieme Verlag, Stuttgart, 1961, pages 192 to 208.

Common nonionic emulsifiers are z. B. ethoxylated mono-, di- and tri-alkylphenols (EO degree: 3 to 50, alkyl radical: C ₄ to C ₁₂ ) and ethoxylated fatty alcohols (EO degree: 3 to 50, alkyl radical: C ₈ to C ₃₆ ).

Usual anionic emulsifiers, ie emulsifiers whose disper gierend acting component has at least one negative electric charge, z. B. Alkali metal and ammonium salts of alkyl sulfates (alkyl: C ₈ to C ₁₂ ), of sulfuric monoesters of ethoxylated alkanols (EO degree: 4 to 30, alkyl: C ₁₂ to C ₁₈ ) and ethoxylated alkylphenols (EO degree: 3 to 50 , Alkyl radical: C ₄ to C ₁₂ ), of alkylsulfonic acids (alkyl radical: C ₁₂ to C ₁₈ ) and of alkylarylsulfonic acids (alkyl radical: C ₉ to C ₁₈ ).

Further surface-active substances whose dispersing component has at least one negative electrical charge are also compounds of the general formula I

wherein R ¹ and R ^{2 are} H atoms or C ₄ - to C ₂₄ alkyl and are not simultaneously H atoms, and A and B may be alkali metal ions and / or ammonium ions proved. In the general formula I, R ¹ and R ^{2 are} preferably linear or branched alkyl radicals having 6 to 18 C atoms, in particular having 6, 12 and 16 C atoms or -H, wherein R ¹ and R ^{2 are} not both simultaneously H atoms are. A and B are preferably sodium, potassium or ammonium, with sodium being particularly preferred. Particularly advantageous are compounds I in which A and B are sodium, R ^{1 is} a branched alkyl radical having 12 C atoms and R ^{2 is} an H atom or R ¹ . Techni cal mixtures are often used which have a proportion of 50 to 90 wt .-% of the monoalkylated product, for example Dowfax® 2A1 (trademark of the Dow Chemical Company). The compounds I are well known, for. Example, from US-A 4,269,749, and commercially available Lich.

Suitable cationic emulsifiers, ie emulsifiers whose dispersing component has at least one positive electric charge, are usually a C ₆ to C ₁₈ alkyl, aralkyl or heterocyclyl radical containing primary, secondary, tertiary or quaternary ammonium salts, alkanolammonium salts , Pyridinium salts, imidazolinium salts, oxazolinium salts, morpholinium salts, thiazolinium salts and salts of amine oxides, quinolinium salts, isoquinolinium salts, tropylium salts, sulfonium salts and phosphonium salts. In addition, polyglycol ether derivatives may also carry at least one positive electrical charge in an acidic environment due to the formation of an oxonium structure. Examples include dodecylammonium acetate or the corresponding hydrochloride, the various Paraffinsäuretri methylammoniumethylester, N-cetylpyridinium chloride, N-lauryl pyridiniumsulfat and N-cetyl-trimethylammonium bromide, N-dodecyl-trimethylammonium bromide, N-octyl-trimethylammonium bromide, N-distearyl-dimethyl-ammonium chloride and Gemini surfactant N, N '- (lauryldimethyl) ethylenediamine dibromide. Numerous other examples can be found in H. Stache, Tensid-Taschenbuch, Carl-Hanser-Verlag, Munich, Vienna, 1981, and in McCutcheon's, Emulsifiers & Detergents, MC Publishing Company, Glen Rock, 1989.

In general, 0.05 to 20 wt .-%, often 0.1 to 5 wt .-%, often 0.2 to 3 wt .-% of dispersant, each based on the Total weight of at least one finely divided inorganic Solid and used for the polymerization at least a monomer used. It can be a partial or Total amount of at least one used in the process Dispersant presented in the aqueous solid dispersion and any remaining amount in the course of radika aqueous initiated emulsion polymerization continuous  be added Lich or discontinuously. It is, however possible, possibly only a subset of the at least a dispersant, in the aqueous solid dispersion to submit and the total or ver remaining amount of the at least one dispersant during the radical emulsion polymerization continuously or to add discontinuously.

Of course, the aforementioned dispersants are suitable very generally for carrying out the method according to the invention. However, the process according to the invention also comprises the preparation aqueous composite particle dispersions, which self-emulsifying Polymers in which monomers which have ionic groups due to a repulsion of charges of the same sign the Stabilization effect included. In these cases needs in usually no additional dispersant can be used. In addition, the inorganic solid particles can also be used due to their uniform charge stabilizing on the aqueous Kompositpartikeldispersion act.

According to the invention, however, only those solids are suitable whose aqueous solid dispersion at an initial solids concentration tion of ≧ 1 wt .-%, based on the aqueous dispersion of Solid, more than one hour after its preparation 90 wt .-% of the originally dispersed solid in disper contains giert form and their dispersed solid particles have a weight-average diameter ≦ 100 nm. Common are initial solids concentrations ≦ 60 wt .-%. Advantageous However, initial solids concentrations ≦ 55 wt .-%, ≦ 50 wt .-%, ≦ 45 wt .-%, ≦ 40 wt .-%, ≦ 35 wt .-%, ≦ 30 wt .-%, ≦ 25 wt .-%, ≦ 20 wt .-%, ≦ 15 wt .-%, ≦ 10 wt .-% and ≧ 1 wt .-%, ≧ 3 wt .-% or ≧ 5 wt .-%, each based on the aqueous dispersion of the solid and all values in between be set.

It is essential to the invention that the dispersed solid particles in a standard aqueous potassium chloride solution at a pH Value, the pH of the aqueous reaction medium at the beginning the emulsion corresponds to a different from zero show anecrophoretic mobility. Under aqueous Reakti Onsmedium at the beginning of the emulsion polymerization is in this Font understood the aqueous reaction medium, the immediate before the addition of the at least one free-radical polymerization initiators. The pH is determined at 20 ° C and 1 bar (absolute) with commercially available pH meters. Depending on Therefore, the pH measurement is carried out on a aqueous dispersion, which only the at least one anor  ganic solid or additionally the at least one Dispersant and / or additionally to the emulsion sation used monomers and optionally further auxiliary contains substances.

The method for determining electrophoretic mobility is known to the person skilled in the art (cf., for example, R. J. Hunter, Introduction to modern Colloid Science, chapter 8.4, pages 241 to 248, Oxford University Press, Oxford, 1993, and K. Oka and K. Furusawa, in Electrical Phenomena at Interfaces, Surfactant Science Series, Vol. 76, chapter 8, pages 151 to 232, Marcel Dekker, New York, 1998). The electrophoretic mobility of the in aqueous Reakti Onsmedium dispersed solid particles is by means of a commercially available electrophoresis apparatus, for example Ze tasizer 3000 from Malvern Instruments Ltd., at 20 ° C. and 1 bar (absolutely) determined. For this purpose, the aqueous solid particles Dispersion with a pH-neutral 10 millimolar (mM) potassium chloride solution (standard potassium chloride solution) diluted as far as that the solid particle concentration about 50 to 100 mg / l be wearing. The setting of the sample to the pH value, the aqueous reaction medium at the beginning of the emulsion polymerization has carried out by means of common inorganic acids, such as for example, dilute hydrochloric acid or nitric acid or bases, such as dilute sodium hydroxide solution or potassium hydroxide solution. The Migration of the dispersed solid particles in the electrical Field is using the so-called electrophoretic light scattering detected (see, for example, B.R. Ware and W.H. Flygare, Chem. Phys. Lett. 1971, 12, pages 81 to 85). This is the Vor sign of electrophoretic mobility due to migration defined direction of the dispersed solid particles, d. H. migrate the dispersed solid particles to the cathode is their electrophoretic mobility positive, they migrate against it to the anode, it is negative.

Be surface-modified solid particles, as they for example, described in the prior art, used, Thus, the determination of electrophoretic mobility with the sen surface-modified particles. Is against a finely divided inorganic solid only with the help of Dispersants dispersible, the determination of the elec trophoretical mobility with suitable nonionic Dispergiermitteln take place, regardless of whether in inventive method actually cationic or anioni cal dispersants are used. This is why he is because the ionic dispersants affect the  adsorbed particulate dispersed and so their electro alter or reverse phoretic mobility.

A suitable parameter for the electrophoretic mobility of to a certain extent to be dispersed particulate Influence or adjust is the pH of the aqueous reaction tion medium. By protonation or deprotonation of the disper gelled solid particles becomes electrophoretic mobility in the acidic pH range (pH <7) in positive and in the alkaline changed range (pH <7) in the negative direction. On pH range suitable for the process according to the invention is within which is a radically initiated aqueous emuls Perform polymerization. This pH range is in usually at pH 1 to 12, often at pH 1.5 to 11 and often at pH 2 to 10.

Carrying out a free-radically initiated aqueous emulsion anionic polymerization of ethylenically unsaturated monomers many previously described and the skilled person therefore be sufficiently be knows [cf. z. B. Encyclopedia of Polymer Science and Engineering, Vol. 8, page 659 ff., 1987; D. C. Blackley, in High Polymer Latices, Vol. 1, page 35 et seq., 1966; H. Warson, The Applications of Synthetic Resin Emulsions, Chapter 5, page 246 et seq., 1972; D. Diederich, Chemistry in our time 1990, 24, pages 135 to 142; Emulsion Polymerization, Interscience Publishers, New York, 1965; DE-A 40 03 422 and dispersions of synthetic high polymer, F. Hölscher, Springer-Verlag, Berlin, 1969]. He he usually follows so that the at least one ethylenic unsaturated monomers, often with the concomitant use of dispersant average, dispersed in aqueous medium and by means of little at least one radical polymerization initiator polymeri Siert. He differs from this procedure inventive method only by an additional presence of at least one finely divided inorganic solid, wel There is a non-zero electrophoretic mobility and a resulting special dispersant medium and / or polymerization initiator combination.

As at least one ethylenically unsaturated group-containing monomers for the inventive method, in particular in a simple manner radically polymerizable monomers into consideration, such as ethylene, vinyl aromatic monomers such as styrene, α-methylstyrene, o-chlorostyrene or vinyltoluenes, esters of vinyl alcohol and 1 to 18 carbon atoms having monocarboxylic acids, such as vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl laurate and vinyl stearate, esters of preference, 3 to 6 carbon atoms having α, β-monoethylenically unge saturated mono- and dicarboxylic acids, in particular acrylic acid , Methacrylic acid, maleic acid, fumaric acid and itaconic acid, with alkanols generally having 1 to 12, preferably 1 to 8 and in particular 1 to 4, carbon atoms, such as, in particular, methyl and ethyl acrylate, methyl, n-butyl, isobutyl and 2-ethylhexyl ester, dimethyl maleate or di-n-butyl maleate, nitriles α, β-monoethylenic and the like saturated carboxylic acids such as acrylonitrile and C _4-8 conjugated dienes such as 1,3-butadiene and isoprene. The monomers mentioned usually form the main monomers which, based on the total amount of monomers to be polymerized by the process according to the invention, usually have a proportion of more than 50% by weight. In general, these monomers have only a moderate to low solubility in water under normal conditions (20 ° C, 1 bar (absolute)).

Monomers which increased under the above conditions Water solubility, for example, α, β-mono ethylenically unsaturated mono- and dicarboxylic acids and their Amides, such as As acrylic acid, methacrylic acid, maleic acid, fumar acid, itaconic acid, acrylamide and methacrylamide, also vinyl sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, styrene sulfonic acid and its water-soluble salts and N-vinylpyrroli Don.

In the normal case, the abovementioned monomers are merely used as modifying monomers in amounts based on the total amount the monomers to be polymerized, of less than 50 wt .-%, in usually 0.5 to 20 wt .-%, preferably 1 to 10 wt .-% a polymerized.

Monomers, which usually increase the internal strength of the polymer matrix films, usually have at least one epoxy, hydroxy, N-methylol or carbonyl group, or at least two non-conjugated ethylenically unsaturated double bonds. Examples of these are N-alkylolamides of 3 to 10 carbon atoms having α, β-monoethylenically unsaturated carboxylic acids, among which N-methylolacrylamide and N-Me methylolmethacrylamid are very particularly preferred and their esters with 1 to 4 carbon atoms having alkanols , In addition, two vinyl radicals containing monomers, two vinylidene radicals having monomers and two alkenyl radicals having monomers into consideration. Particularly advantageous are the di-esters of two-valent alcohols with α, β-monoethylenically unsaturated monocarboxylic acids, among which acrylic and methacrylic acid are preferred. Examples of such two non-conjugated ethylenically unsaturated double bonds monomers are alkylene glycol diacrylates and dimethacrylates such as ethylene glycol diacrylate, 1,2-propylene glycol diacrylate, 1,3-propylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-Butylenglykoldi acrylate and ethylene glycol dimethacrylate, 1, 2-Propylenglykoldi methacrylate, 1,3-propylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-Butylenglykoldimethacrylate and divinyl benzene, vinyl methacrylate, vinyl acrylate, allyl methacrylate, allyl acrylate, diallyl maleate, diallyl fumarate, methylenebisacrylamide, cyclopentadienyl acrylate, triallyl cyanurate or triallyl iso cyanurate. Of particular importance in this context are the C ₁ -C ₈ hydroxyalkyl methacrylates and acrylates, such as n-hydroxyethyl, n-hydroxypropyl or n-hydroxybutyl acrylate and methacrylate, and also compounds such as diacetone acrylamide and acetylacetoxyethyl acrylate or methacrylate. According to the who the above monomers, based on the total amount of monomers to be polymerized, often in amounts of 0.5 to 10 wt .-% copolymerized.

In the method according to the invention, the weight fraction of at least one ethylenically unsaturated monomer, based on the total weight of the at least one finely divided inorganic Solid and used for the polymerization at least an ethylenically unsaturated monomer, usually between 10 and 99 wt .-%, often between 25 and 90 wt .-% and often between 40 and 80 wt .-%. According to the invention, a partial or Total amount of at least one monomer together with the we at least one finely divided inorganic solid in the reaction medium submitted and any remaining amount according to the consumption during the free radical emulsion polymerization continuously or discontinuously added become. But it is also possible, if necessary, only one Part of the at least one monomer in the aqueous solid submit substance dispersion and then during the radical Emulsion polymerization the total amount or optionally Remaining residual amount according to consumption continuously or discontinuously.

As at least one radical polymerization initiator come for the free-radical aqueous emulsion polymer according to the invention Anyone who is able to do so would consider it free radical aqueous emulsion polymerization in the presence of trigger at least one finely divided inorganic solid sen. In principle, it can be both peroxides and to act azo compounds. Of course, also redox come initiator systems into consideration. As peroxides can in principle organic peroxides, such as hydrogen peroxide or peroxodisulfates, such as the mono- or di-alkali metal or ammonium salts of per  Oxodischwefelsäure, for example, the mono- and di-sodium, Potassium or ammonium salts or organic peroxides such as alkyl hydroperoxides, for example tert-butyl, p-menthyl or cumyl hydroperoxide, as well as dialkyl or diaryl peroxides, such as di-tert. Butyl or di-cumyl peroxide can be used. As azo compound find essentially 2,2'-azobis (isobutyronitrile), 2,2'-azo bis (2,4-dimethylvaleronitrile) and 2,2'-azobis (amidinopropyl) - dihydrochloride (AIBA, corresponds to the sales product V-50 of Wako Chemicals) use. As oxidizing agent for redox Initiator systems essentially come from the abovementioned Per oxide into consideration. As appropriate reducing agents can Low oxidation state sulfur compounds such as alkali sulfites, for example potassium and / or sodium sulfite, Alkalihy drug sulfites, for example potassium and / or sodium hydrogen sulfite, alkali metal bisulfites, for example, potassium and / or Sodium metabisulfite, formaldehyde sulfoxylates, for example Potassium and / or sodium formaldehyde sulfoxylate, alkali salts, spe potassium and / or sodium salts aliphatic sulfinic acids and Alkalimetallhydrogensulfide such as potassium and / or Sodium hydrogen sulphide, salts of polyvalent metals, such as egg sen (II) sulfate, iron (II) - / ammonium sulfate, iron (II) phosphate, Endiols such as dihydroxymaleic acid, benzoin and / or ascorbic acid and reducing saccharides such as sorbose, glucose, fructose and / or dihydroxyacetone. Usually amounts to the amount of radical polymerization used initiators, based on the total amount of polymerizable Monomers, 0.1 to 3 wt .-%.

As at least one radical polymerization initiator whose radical generating component at least one negative electrical Charge, are exemplary peroxodisulfates, such as Mono- or di-alkali metal or ammonium salts of peroxides sulfuric acid, for example the mono- and di-sodium, potassium or ammonium salts and hydrogen peroxide in alkaline medium called.

As at least one radical polymerization initiator whose radical-generating component at least one positive electrical Charge is exemplified AIBA.

According to the invention, a partial or total amount of the little at least one radical polymerization initiator together with the at least one finely divided inorganic solid in the Submitted reaction medium and the remaining if necessary Remaining quantity according to the consumption during the radical Emulsion polymerization continuously or discontinuously too are given. But it is also possible, if necessary unmarried  Lich a subset of at least one radical Polymerization initiator in the aqueous solid dispersion to submit and then during the inventive radical Emulsion polymerization the total amount or optionally Remaining residual amount according to consumption continuously or discontinuously.

As the reaction temperature for the inventive radical aqueous emulsion polymerization in the presence of the at least one finely divided inorganic solid comes the entire area from 0 to 170 ° C into consideration. In this case, temperature is usually from 50 to 120 ° C, often 60 to 110 ° C and often ≧ 70 to 100 ° C. applied. The novel free-radical aqueous emulsions Polymerization can be smaller, equal or greater at one pressure 1 bar (absolute) are carried out so that the polymerization temperature can exceed 100 ° C and can be up to 170 ° C. Preferably, volatile monomers such as ethylene, Butadiene or vinyl chloride polymerized under elevated pressure. The pressure can be 1,2, 1,5, 2, 5, 10, 15 bar or even higher Take values. Are emulsion polymerizations in negative pressure carried out, pressures of 950 mbar, often 900 mbar and often set to 850 mbar (absolute). Advantageously, the Free-radical aqueous emulsion polymerization according to the invention at 1 bar (absolute) under inert gas atmosphere, such as carried out under nitrogen or argon.

The aqueous reaction medium can in principle also be water-soluble organic solvents such as methanol, ethanol, Isopropanol, butanols, pentanols, etc. include. It is preferred the inventive method, however, in the absence of such Solvent carried out.

It is essential to the invention that the dispersed solid particles of the at least one inorganic solid among the above prescribed conditions a non-zero electrophores mobility, the opposite of which at least one electric charge of the radical generator Component of the at least one radical polymerization initiator and / or the dispersing component of the at least one dispersant. Is therefore at least a finely divided inorganic solid whose dispersed Solid particles have an electrophoretic mobility with negative Have sign, so the inventive radi aqueous aqueous emulsion polymerization with at least one Dispersant whose dispersing component little at least one positive charge and / or at least one radical polymerization initiator, its radical-generating  Component carries a positive electrical charge. Is against it in the process according to the invention at least one finely divided anor ganic solid, whose dispersed solid particles an electrophoretic mobility with a positive sign show, then the inventive radical aqueous Emulsion polymerization with at least one dispersant, its dispersing component at least one negative Carries charge and / or with at least one radical poly merisationsinitiator whose radical-generating component a having negative electric charge.

The process according to the invention can be carried out for example in this way be that a stable aqueous dispersion of at least a finely divided inorganic solid containing either a partial or total amount of water needed, be forced at least one dispersant, the at least one Polymerization initiator and / or the at least one ethylenically unsaturated monomers and the optionally white tere customary auxiliaries and additives in a reaction vessel and the contents of the reaction vessel on Reaktionstempe temperature heats up. At this temperature, the ge if necessary remaining amounts of water, at least a dispersant, the at least one polymerization initiator and / or the at least one ethylenically unge saturated monomers and optionally further customary Auxiliaries and additives continuous or discontinuous added and then optionally further on Reaction temperature maintained.

However, the method according to the invention can also be carried out in this way be that a stable aqueous dispersion of at least a finely divided inorganic solid containing either a partial or total amount of water needed, the at least one dispersing agent and / or optionally other customary auxiliaries and additives and optionally one Part of the at least one ethylenically unsaturated monome and the at least one polymerization initiator in one Reaction vessel presents and the contents of the reaction vessel heats up to reaction temperature. At this temperature will be while stirring, the total or the remaining if necessary Residual amount of the at least one ethylenically unsaturated mono and at least one polymerization initiator and any remaining amounts of water, the at least one dispersing agent and / or optionally other customary auxiliaries and additives continuously or  added discontinuously and then optionally kept at reaction temperature.

The composite particles obtainable according to the invention have in the Usually particle diameter of ≦ 5000 nm, often ≦ 1000 nm and often ≦ 400 nm. The determination of the particle diameter is carried out usually by transmission electron microscopic sub investigations (see, for example, L. Reimer, Transmission Electron Microscopy, Springer-Verlag, Berlin, Heidelberg, 1989; D.C. Joy, The Basic Principles of EELS in Principles of Analytical Electron Micro Skopy, edited by D.C. Joy, A.D. Romig, Jr. and J.I. Gold Stein, Plenum Press, New York, 1986; L.C. Sawyer and D.T. Polymer Microscopy, Chapman and Hall, London, 1987).

The composite obtainable by the process according to the invention Particles can have different structures. Frequently Composite particles are obtained with raspberry-shaped structure. The Composite particles according to the invention may contain one or more of containing finely divided solid particles. The finely divided festival Particles of the substance can be completely enveloped by the polymer matrix his. But it is also possible that a part of the finely divided Solid particles enveloped by the polymer matrix while a another part is arranged on the surface of the polymer matrix. Of course, it is also possible that much of the finely divided solid particles on the surface of the polymer matrix is bound. Preference is given to Gew 50% by weight or ≧ 60% by weight, frequently ≧ 70 wt% or ≧ 80 wt% and often ≧ 85 wt% or ≧ 90 wt% the finely divided solid particles, each based on the total amount of fine particles contained in the composite particles particulate solids on the surface of the polymer matrix bound. It should be noted that in individual cases, depending on the solids concentration of the dispersed composite particles, may also come to a partial agglomeration of composite particles.

Of course, after completion of Hauptpolymerisa tion reaction in the aqueous dispersion of the composite particles Remaining monomer residual amounts by steam and / or inert gas stripping and / or by chemical deodorization, as they are For example, in DE-A 44 19 518, EP-A 767 180 or DE-A 38 34 734 are described, be removed without the properties of the aqueous Kompositpartikeldispersion after change in part.

Aqueous dispersions of composite particles, which after Be be prepared inventive method, are suitable as raw materials for the production of adhesives, such as For example, pressure-sensitive adhesives, construction adhesives or industry  adhesives, binders, such as for paper painting, emulsion paints or printing inks and printing lacquers for printing on plastic films, for the production of Nonwovens and for the production of protective layers and Water vapor barriers, such as the primer. Furthermore, the process of the invention can be accessed composite particle dispersions also for the modification of Use cement and mortar formulations. The after the invention according to the method accessible composite particles can be in principle also in medical diagnostics as well as in others use medical applications (see, for example, K. Mosbach and L. Andersson, Nature, 1977, 270, pp. 259-261; P. L. Kronick, Science 1978, 200, pp. 1074-1076; US-A 4,157,323). In addition, the composite particles can be left also as catalysts in various aqueous dispersions use systems.

It should also be noted that the inventively available aqueous dispersions of composite particles in a simple manner are dryable to redispersible composite particle powders (eg freeze drying or spray drying). This applies to special if the glass transition temperature of the polymer matrix of the composite particles ≧ 50 ° C obtainable according to the invention, preferably ≧ 60 ° C, more preferably ≧ 70 ° C, very particularly preferably ≧ 80 ° C and more preferably ≧ 90 ° C or ≧ 100 ° C. is. The composite particle powders are suitable u. a. as additives for plastics, components for toner formulations or additive substances in electrophotographic applications.

Examples

For the following examples was used as finely divided inorganic Solid silica, tin (IV) oxide, yttrium (III) oxide and Cerium (IV) oxide used. The com available silicon dioxide sols Levasil® 200 S (15 nm) Bayer AG, Nyacol® 2040 (20 nm) and Nyacol® 830 (10 nm) Akzo-Nobel and Ludox® HS30 (12 nm) from Dupont. Also used were Nyacol® SN15 [stannic oxide] (10 to 15 nm), Nyacol® YTTRIA [yttrium (III) oxide] (10 nm) and Nyacol® CEO2 {ACT} [cerium (IV) oxide] (10 to 20 nm). The in parentheses specified values correspond to the diameters of the respective inorganic solid particles according to manufacturer's instructions.  

example 1

In a 500 ml four-necked flask equipped with a reflux cooler, a thermometer, a mechanical stirrer and a Dosage device, were under nitrogen atmosphere at 20 ° C and 1 bar (absolute) 90 g of deionized and oxygen-free water and 0.08 g CTAB submitted and stirred (250 revolutions per Minute) first 20 g of Nyacol® 2040 (with a silica resistant content of 40 wt .-%) and then added 5 g of styrene and at closing heated to a reaction temperature of 75 ° C. The pH of this aqueous reaction medium, measured at 20 ° C and 1 bar (absolute), was 8.6.

The stirred reaction medium was at reaction temperature 0.1 g of ammonium peroxodisulfate dissolved in 10 g of deionized and oxygen-free water added. The stirred reaction mixture was held at reaction temperature for 3.5 hours and on then cooled to room temperature.

The composite particle dispersion thus obtained had a solid content of 12.2 wt .-%, based on the total weight of aqueous composite particle dispersion, on. transmission electron Nuclear microscopic investigations (see, for example, L. Reimer, Trans mission Electron Microscopy, Springer-Verlag, Berlin, Heidelberg, 1989; D.C. Joy, The Basic Principles of EELS in Principles of Analytical Electron Microscopy, edited by D.C. Joy, A.D. Romig, Jr. and J.I. Goldstein, Plenum Press, New York, 1986; L.C. Sawyer and D.T. Grupp, Polymer Microscopy, Chapman and Hall, London, 1987) had raspberry-shaped composite particles with one Diameter of about 100 nm. Free silica particles were virtually impossible to prove.

The sign determination of electrophoretic mobility followed with the finely divided inorganic solids in general by means of the Zetasizer 3000 from Malvern Instruments Ltd. For this purpose, the finely divided inorganic solid was diluted Dispersion with pH-neutral 10 mM potassium chloride solution (standard potassium chloride solution) to the extent that their Feststoffteilchenkonzen between 50 and 100 mg per liter. Using dilute Hydrochloric acid or dilute sodium hydroxide solution was used to adjust the pH a, the aqueous reaction medium immediately before the addition of the Had polymerization initiator.

With dilute hydrochloric acid was set at 60 mg / l Silica solids diluted Nyacol® 2040 dispersion a pH of 8.6. The electrophoretic mobility of  Silica particles in Nyacol® 2040 had a negative sign get up.

The solids content was generally determined by adding about 1 g of the Composite particle dispersion in an open aluminum crucible with an inner diameter of about 3 cm in a drying oven 2 hours at 150 ° C was dried. To determine the feast In each case, two separate measurements were carried out and the corresponding mean value formed.

Example 2

Under nitrogen atmosphere were at 20 ° C and 1 bar (absolute) 60 g deionized and oxygen-free water and 1.5 g 1 M Hydrochloric acid in a 500 ml four-necked flask and stirred (250 revolutions per minute) 20 g Nyacol® 2040 added. to Finally, the aqueous phase was adjusted with 1.62 g of 1 M salt acid to pH 2.5 and filled with water containing 1 M salt acid to pH 2.5, to 100 g. After that the reaction mixture was heated to a reaction temperature of 75 ° C on. The pH of this aqueous phase, measured at room temperature was 2.5.

Parallel set an aqueous emulsion, consisting of 20 g Styrene, 80 g of deionized and oxygen-free water as well 0.2 g of CTAB (feed 1). An initiator solution was made up of 0.45 g Ammonium peroxodisulfate and 44.55 g deionized and oxygen produced free water (inlet 2).

At the reaction temperature, 5 g of the stirred reaction medium of feed 2 added. After 5 minutes and at the same time Beginning, one dosed the stirred reaction medium at Reakti onstemperatur the feed 1 over 2 hours and the rest of feed 2 over 2.5 hours too. Subsequently, the Reaktionsge was stirred Mix for 1 hour at reaction temperature and then cooled Room temperature off.

The composite particle dispersion thus obtained had a solid content of 10.4 wt .-%, based on the total weight of aqueous composite particle dispersion, on. The presence of him berry-shaped composite particles with a diameter of about 160 to 240 nm was measured by transmission electron micros of copious investigations. Free silica part only traces could be detected.  

The silica particles had an electrophoretic at pH 2.5 mobility with a negative sign.

Example 3

The procedure of Example 2 was repeated with the Off assume that the pH of the aqueous reaction medium is 5 was asked. The template was set in the following way ago: 60 g of deionized and oxygen-free water and 1.5 g 1 M hydrochloric acid were initially charged and stirred (250 revolutions per minute) 20 g Nyacol® 2040 added. Then you put the aqueous phase with 1.01 g of 1 M hydrochloric acid to pH 5 and filled with water, which was adjusted to pH 5 with 1 M hydrochloric acid had been raised to 100 g.

The composite particle dispersion thus obtained had a solid content of 11.6% by weight, based on the total weight of the aq composite particle dispersion. Transmissionselektronenmi microscopic studies confirm the presence of raspberry shaped composite particles having a diameter of about 180 to 240 nm. Free silica particles practically could not be detected.

At a pH of 5, the silica particles had a electrophoretic mobility with a negative sign.

Example 4

The procedure of Example 2 was repeated with the Off assume that the pH of the aqueous reaction medium is 7 was set and as a polymerization initiator instead of 0.45 g of ammonium peroxodisulfate 0.45 g of sodium peroxodisulfate sat. In addition, the reaction temperature of 75 to 85 ° C at lifted. The reaction template was prepared in the following manner provides: 60 g of deionized and oxygen-free water and 1.5 g 1 M hydrochloric acid were introduced and stirred (250 Umdrehun per minute) 20 g Nyacol® 2040 added. Subsequently presented the aqueous phase with 0.5 g of 1 M hydrochloric acid to pH 7 and filled with water, which was adjusted to pH 7 with 1 M hydrochloric acid had been raised to 100 g.

The resulting composite particle dispersion became a solid content of 11.2 wt .-%, based on the total weight of aqueous composite particle dispersion determined. By means of transmis Electron microscopic investigations were conducted by raspberry mige composite particles with a diameter of about 150 to  190 nm detected. Free silica particles could prak can not be proved.

At a pH of 7, the silica particles had a electrophoretic mobility with a negative sign.

Example 5

Example 2 was repeated except that instead of 20 g of styrene, a monomer mixture consisting of 10 g of styrene and 10 g of 2-ethylhexyl acrylate and, instead of 0.2 g of CTAB, 0.4 g of CTAB and as a polymerization initiator instead of 0.45 g of ammonium Peroxodisulfate 0.45 g of sodium peroxodisulfate were used. The reaction temperature was also raised from 75 to 85 ° C.

The resulting composite particle dispersion had a solid content of 11.8 wt .-%, based on the total weight of aqueous composite particle dispersion, on. By means of transmissions Electron microscopic studies were raspberry shaped Nachge composite particles with a diameter of about 300 nm grasslands. Free silica particles were virtually impossible prove.

Example 6

Example 2 was repeated except that instead of 20 g of styrene 20 g of methyl methacrylate (MMA) and as Polymerisati onsinitiator instead of 0.45 g of ammonium peroxodisulfate 0.45 g Sodium peroxodisulfate were used. The reaction temperature was also raised from 75 to 85 ° C.

The resulting composite particle dispersion had a solid content of 11.2% by weight, based on the total weight of the aq composite particle dispersion. Raspberry-shaped composite par particles with a diameter of about 80 to 140 nm could be detected by transmission electron microscopic measurements. Free silica particles could not be detected practically become.

Example 7

Example 2 was repeated except that instead of 20 g of styrene, a monomer mixture consisting of 10 g of MMA and 10 g n-butyl acrylate was used.  

The composite particle dispersion thus obtained had a solid content of 11.6 wt .-%, based on the total weight of aqueous composite particle dispersion, on. About transmissionse Electron microscopic measurements could raspberry-shaped compo Sit particles with a diameter of about 200 to 400 nm nachge be meadows. Free silica particles became practical not established.

Example 8

Under nitrogen atmosphere were at 20 ° C and 1 bar (absolute) 40 g deionized and oxygen-free water and 1.5 g 1 M Hydrochloric acid in a 500 ml four-necked flask and stirred (250 revolutions per minute) 40 g Nyacol® 2040 added. to Finally, the aqueous phase was adjusted with 4 g of 1 M hydrochloric acid to pH 2.5 and filled with water, which was treated with 1 M hydrochloric acid was adjusted to pH 2.5, to 100 g. Then heated the reaction mixture to a reaction temperature of 75 ° C. on.

Parallel set an aqueous emulsion, consisting of 20 g Styrene, 20 g n-butyl acrylate, 60 g deionized and oxygen free water and 0.2 g of CTAB (feed 1). An initiator solution was from 0.45 g of ammonium peroxodisulfate and 45 g of deioni prepared and oxygen-free water (feed 2).

At the reaction temperature, 5 g of the stirred reaction medium of feed 2 added. After 5 minutes and at the same time Beginning, one dosed the stirred reaction medium at Reakti onstemperatur the feed 1 over 2 hours and the rest of feed 2 over 2.5 hours too. Subsequently, the Reaktionsge was stirred Mix for 1 hour at reaction temperature and then cooled Room temperature off.

The resulting composite particle dispersion had a solid content of 22.4 wt .-%, based on the total weight of aqueous composite particle dispersion, on. transmission electron Nuclear microscopy studies showed the presence of raspberry shaped composite particles with a diameter of about 240 nm. Free silica particles could not be detected practically become.

Example 9

Under nitrogen atmosphere were at 20 ° C and 1 bar (absolute) 15 g deionized and oxygen-free water and 1.5 g 1 M Hydrochloric acid in a 500 ml four-necked flask and stirred  (250 revolutions per minute) 73.5 g Nyacol® 2040 added. Subsequently, the aqueous phase was adjusted with 8.24 g of 1 M salt acid to pH 2.5 and filled with water containing 1 M salt acid to pH 2.5, to 100 g. subsequently, ßend the reaction mixture was heated to a reaction temperature from 75 ° C to.

In parallel, an aqueous emulsion consisting of 34.3 g was prepared Styrene, 34.3 g n-butyl acrylate, 31.4 g deionized and acidic fabric-free water and 0.4 g CTAB (feed 1). A Initiator solution was prepared from 1.58 g of ammonium peroxodisulfate and 45 g deionized and oxygen-free water (Zu run 2).

At the reaction temperature, 5 g of the stirred reaction medium of feed 2 added. After 5 minutes and at the same time Beginning, one dosed the stirred reaction medium at Reakti onstemperatur the feed 1 over 2 hours and the rest of feed 2 over 2.5 hours too. Subsequently, the Reaktionsge was stirred Mix for 1 hour at reaction temperature and then cooled Room temperature off.

From the formed composite particle dispersion became a feast content of 40.0 wt .-%, based on the total weight of aqueous composite particle dispersion determined. By means of transmis Electron microscopic measurements were raspberry-shaped Composite particles with a diameter of about 270 nm nachgewie be sen. Free silica particles were practically not detectable.

Example 10

Under nitrogen atmosphere were at 20 ° C and 1 bar (absolute) 50 g deionized and oxygen-free water and 1.5 g 1 M Hydrochloric acid in a 500 ml four-necked flask and stirred (250 revolutions per minute) 26.7 g of Nyacol® 830 (with a Silica solids content of 30% by weight). subsequently, ßend set the aqueous phase with 4.06 g of 1 M hydrochloric acid pH 2.5 and filled with water, which was mixed with 1 M hydrochloric acid pH 2.5, to 100 g. Then heated the reaction mixture to a reaction temperature of 85 ° C. on. The pH of this aqueous phase, measured at room temp ratur, was 2.5.

Parallel set an aqueous emulsion, consisting of 20 g Styrene, 80 g of deionized and oxygen-free water as well 0.2 g of CTAB (feed 1). An initiator solution was made up of 0.45 g  Sodium peroxodisulfate and 45 g of deionized and oxygen produced free water (inlet 2).

At the reaction temperature, 5 g of the stirred reaction medium of feed 2 added. After 5 minutes and at the same time Beginning, one dosed the stirred reaction medium at Re reaction temperature, the feed 1 over 2 hours and the rest of Feed 2 over 2.5 hours too. Then they stirred the Re action mixture for 1 hour at reaction temperature and cooled then to room temperature.

The resulting composite particle dispersion had a solid content of 11.5 wt .-%, based on the total weight of aqueous composite particle dispersion, on. Through transmissions Electron microscopic measurements could raspberry-shaped Kompo Site particles with a diameter of about 160 nm demonstrated become. Free silica particles were virtually impossible prove.

The silica particles of Nyacol® 830 exhibited at a pH Value of 2.5 an electrophoretic mobility with negative fore sign up.

Example 11

Under nitrogen atmosphere were at 20 ° C and 1 bar (absolute) 50 g deionized and oxygen-free water and 1.5 g 1 M Hydrochloric acid in a 500 ml four-necked flask and stirred (250 revolutions per minute) 26.7 g Ludox® HS30 (with a Silica solids content of 30% by weight). subsequently, ßend set the aqueous phase with 1.88 g of 1 M hydrochloric acid pH 2.5 and filled with water, which was mixed with 1 M hydrochloric acid pH 2.5, to 100 g. Then you heated the reaction mixture to a reaction temperature of 85 ° C. The pH of this aqueous phase, measured at room temperature, was 2.5.

In parallel, an aqueous emulsion consisting of 10 g was prepared Styrene, 10 g n-butyl acrylate, 80 g deionized and oxygen free water and 0.2 g of CTAB (feed 1). An initiator solution was prepared from 0.45 g of sodium peroxodisulfate and 45 g of deioni prepared and oxygen-free water (feed 2).

At the reaction temperature, 5 g of the stirred reaction medium of feed 2 added. After 5 minutes and at the same time Beginning, one dosed the stirred reaction medium at Reakti onstemperatur the feed 1 over 2 hours and the rest of feed  2 over 2.5 hours too. Subsequently, the Reaktionsge was stirred Mix for 1 hour at reaction temperature and then cooled Room temperature off.

The thus accessible composite particle dispersion had a feast content of 11.2 wt .-%, based on the total weight of aqueous composite particle dispersion, on. transmission electron Nuclear microscopic measurements confirm the presence of raspberry composite particles with a diameter of about 260 nm. Free silica particles were virtually undetectable.

The silicon dioxide particles of Ludox® HS30 were found in a pH of 2.5 an electrophoretic mobility with negative Sign on.

Example 12

Under nitrogen atmosphere were at 20 ° C and 1 bar (absolute) 60 g deionized and oxygen-free water and 1.5 g 1 M Hydrochloric acid in a 500 ml four-necked flask and stirred (250 revolutions per minute) 20 g Nyacol® 2040 added. to Finally, the aqueous phase was adjusted with 1.62 g of 1 M salt acid to pH 2.5 and filled with water containing 1 M salt acid to pH 2.5, to 100 g. subsequently, ßend the reaction mixture was heated to a reaction temperature from 85 ° C to.

An aqueous emulsion consisting of 20 g of styrene, 78 g of deionized and oxygen-free water and 2 g of a 20% strength by weight aqueous solution of the nonionic emulsifier Lutensol® AT18 (trademark of BASF AG, C ₁₆ C ₁₈ fatty alcohol ethoxylate) was placed in parallel with 18 ethylene oxide units) ago (feed 1). An initiator solution was prepared from 0.45 g of AIBA and 45 g of deionized and oxygen-free water (feed 2).

At the reaction temperature, 5 g of the stirred reaction medium of feed 2 added. After 5 minutes and at the same time Beginning, one dosed the stirred reaction medium at Reakti onstemperatur the feed 1 over 2 hours and the rest of feed 2 over 2.5 hours too. Subsequently, the Reaktionsge was stirred Mix for 1 hour at reaction temperature and then cooled Room temperature off.

The resulting composite particle dispersion had a solid content of 11.3% by weight, based on the total weight of the aq composite particle dispersion. By transmission electro Nuclear microscopic measurements showed the presence of raspberry  composite particles with a diameter of about 200 nm be sets. Free silica particles were virtually nonexistent weisbar.

Example 13

Under nitrogen atmosphere were at 20 ° C and 1 bar (absolute) 46.7 g of deionized and oxygen-free water as well about 0.02 g of 1 M sodium hydroxide solution in a 500 ml four-necked flask and while stirring (250 revolutions per minute) 53.3 g of Nyacol® SN15 (with a Zinndioxideststoffgehalt of 15 wt .-%) zugege ben. Subsequently, the reaction mixture was heated to a reac tion temperature of 85 ° C on. The pH of this aqueous phase, measured at room temperature, was 10.

Parallel set an aqueous emulsion, consisting of 20 g Styrene, 1.5 g 1 M hydrochloric acid, 78.5 g deionized and acidic substance-free water and 0.2 CTAB (feed 1). An initiator solution was made up of 0.45 g of AIBA and 45 g of deionized and acidic fabric-free water (feed 2).

At the reaction temperature, 5 g of the stirred reaction medium of feed 2 added. After 5 minutes and at the same time Beginning, one dosed the stirred reaction medium at Reakti onstemperatur the feed 1 over 2 hours and the rest of feed 2 over 2.5 hours too. Subsequently, the Reaktionsge was stirred Mix for 1 hour at reaction temperature and then cooled Room temperature off.

The resulting composite particle dispersion had a solid content of 10.4% by weight, based on the total weight of the aq composite particle dispersion. By transmission electro Nuclear microscopic measurements showed raspberry-shaped composite particles kel with a diameter of about 50 to 230 nm demonstrated become. Free Zinndioxidteilchen were virtually impossible prove.

The tin dioxide particles of Nyacol® SN15 were at a pH of 10 electrophoretic mobility with negative sign on.

Example 14

Example 13 was repeated except that instead of 0.2 g CTAB 0.4 g CTAB and 0.45 g AIBA 0.45 g Sodium peroxodisulfate were used.  

The thus accessible composite particle dispersion had a feast content of 11.5 wt .-%, based on the total weight of aqueous composite particle dispersion, on. transmission electron NEM-microscopic measurements confirm the presence of raspberry shaped composite particles with a diameter of about 130 nm. Free Zinndioxidteilchen were virtually undetectable.

Example 15

Under nitrogen atmosphere were at 20 ° C and 1 bar (absolute) 73.3 g of deionized and oxygen-free water and 0.01 g 1 M hydrochloric acid in a 500 ml four-necked flask and placed under Stirring (250 revolutions per minute) 26.7 g Levasil® 200 S (with a silica solids content of 30% by weight). to Finally, the reaction mixture was heated to a reaction temperature temperature of 85 ° C. The pH of this aqueous phase, measured at room temperature, was 3.8.

Parallel set an aqueous emulsion, consisting of 20 g Styrene, 80 g of deionized and oxygen-free water as well 2.0 g of a 20 wt .-% aqueous solution of nonionic Emulsifier Lutensol® AT18 (feed 1). An initiator solution was made up of 0.45 g of sodium peroxodisulfate and 45 g of deionized and oxygen-free water (feed 2).

At the reaction temperature, 5 g of the stirred reaction medium of feed 2 added. After 5 minutes and at the same time Beginning, one dosed the stirred reaction medium at Reakti onstemperatur the feed 1 over 2 hours and the rest of feed 2 over 2.5 hours too. Subsequently, the Reaktionsge was stirred Mix for 1 hour at reaction temperature and then cooled Room temperature off.

The resulting composite particle dispersion had a solid content of 11.0 wt .-%, based on the total weight of aqueous composite particle dispersion, on. transmission electron Nuclear microscopic measurements confirm the presence of raspberry composite particles with a diameter of about 300 to 600 nm. Free silica particles were virtually nonexistent weisbar.

At a pH of 3.8, the silica particles of Levasil® 200 S has a positive electrophoretic mobility Sign on.  

Example 16

Under nitrogen atmosphere were at 20 ° C and 1 bar (absolute) 60 g deionized and oxygen-free water and 0.01 g 1 M Hydrochloric acid in a 500 ml four-necked flask and stirred (250 revolutions per minute) 40 g Nyacol® CEO2 {ACT} (with a cerium dioxide solids content of 20% by weight). to closing heated to a reaction temperature of 85 ° C. The pH of this aqueous phase, measured at room temperature, was 3.

Parallel set an aqueous emulsion, consisting of 20 g Styrene, 80 g of deionized and oxygen-free water as well 0.44 g of a 45 wt .-% aqueous solution of the anionic Dowfax® 2A1 (inlet 1). An initiator solution was made up of 0.45 g AIBA and 45 g of deionized and oxygen-free water (feed 2).

At the reaction temperature, 5 g of the stirred reaction medium of feed 2 added. After 5 minutes and at the same time Beginning, one dosed the stirred reaction medium at Reakti onstemperatur the feed 1 over 2 hours and the rest of feed 2 over 2.5 hours too. Subsequently, the Reaktionsge was stirred Mix for 1 hour at reaction temperature and then cooled Room temperature off.

A solids content of 11.4 wt .-%, based on the Gesamtge weight of the aqueous composite particle dispersion, the so zug ized composite particle dispersion. By transmissionselek Tronenmikroskopische measurements were raspberry-shaped Kompositpar detected with a diameter of about 130 nm. Free Ceria particles could not be detected practically.

The ceria particles of Nyacol® CEO2 {ACT} had a pH of Value of 3.0 an electrophoretic mobility with positive fore sign up.

Example 17

Under nitrogen atmosphere were at 20 ° C and 1 bar (absolute) 42.9 g of deionized and oxygen-free water in a 500 ml Four-necked flask and placed under stirring (250 revolutions per Minute) 57.1 g of Nyacol® YTTRIA (with an yttrium (III) oxide solid substance content of 14 wt .-%) was added. Then you heated that Reaction mixture to a reaction temperature of 85 ° C. The  pH of this aqueous phase, measured at room temperature, be contributed 7.2.

Parallel set an aqueous emulsion, consisting of 20 g Styrene, 80 g of deionized and oxygen-free water as well 0.44 g of a 45 wt .-% aqueous solution of the anionic Dowfax® 2A1 (inlet 1). An initiator solution was made up of 0.45 g AIBA and 45 g of deionized and oxygen-free water (feed 2).

At the reaction temperature, 5 g of the stirred reaction medium of feed 2 added. After 5 minutes and at the same time Beginning, one dosed the stirred reaction medium at Reakti onstemperatur the feed 1 over 2 hours and the rest of feed 2 over 2.5 hours too. Subsequently, the Reaktionsge was stirred Mix for 1 hour at reaction temperature and then cooled Room temperature off.

The resulting composite particle dispersion had a solid content of 13.8 wt .-%, based on the total weight of aqueous composite particle dispersion, on. By transmissionse Electron microscopic measurements were raspberry-shaped composite detected particles with a diameter of about 60 nm. Free Yttrium (III) oxide particles were virtually undetectable sen.

The yttrium (III) oxide particles of Nyacol® YTTRIA were included a pH of 7.2 with an electrophoretic mobility with positive sign.

Example 18

Example 2 was repeated except that instead of 20 g of styrene, a monomer mixture consisting of 10 g of styrene and 10 g of n-butyl acrylate were used.

The resulting composite particle dispersion had a solid content of 11.3 wt .-%, based on the total weight of aqueous composite particle dispersion, on. By means of transmissions Electron microscopic studies were raspberry shaped Composite particles with a diameter of about 180 to 300 nm demonstrated. Free silica particles became practical do not prove.

Centrifuge the composite particle dispersion (3000 revolutions per minute, duration 20 minutes) led to complete sedimenta tion of the composite particles. The supernatant aqueous reaction mixture  dium was water clear. In this water-clear reaction medium could also by means of transmission electron microscopic Un tests virtually no free silica particles after be pointed. Evaporate the water-clear solution at 150 ° C until to constant weight gave a dry residue of 0.28 wt .-%, based on the total weight of the water-clear Solution. (If the total amount of silica particles in the serum freely available, a dry residue of 3.3% by weight would be expected Accordingly, at least 92 wt .-% of the silica particles bound in composite particles. The actual proportion of gebun However, the silica particles is above this value since was neglected that in serum in addition to the free silicon Dioxide particles still salt from the neutralization of silicon dioxide particles, emulsifier and initiator decomposition products whose quantities can not be calculated exactly).

By means of an analytical ultracentrifuge (see SE Harring 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 Reslution Particle Size Distribution and Density Gradient Techniques, W. Mächtle, pages 147 to 175), a mean density of 1.22 g / cm ^{3 was} determined for the composite particles. In comparison, the density of the pure styrene / n-butyl acrylate copolymer (styrene and n-butyl acrylate in a weight ratio of 1 to 1) is only 1.055 g / cm ³ (E. Penzel, Polyacrylates, in Ullmann's Encyclopedia of Industrial Chemistry, Vol. A 21, page 169).

Comparative Example 1

Example 18 was repeated except that instead of 0.2 g of the cationic emulsifier CTAB 0.44 g of a 45gew .-% Solution of the anionic emulsifier Dowfax® 2A1 were used.

The resulting cloudy reaction mixture was by means of transmissions electron microscopic measurements examined. It could single Lich pure polymer particles and the dispersed silica be found particles. Raspberry-shaped composite particles were not detectable. By centrifuging the cloudy dispersion (3000 revolutions per minute, duration 20 minutes) could not Sedimentation of the dispersed particles can be achieved.  

Comparative Example 2

Example 15 was repeated except that instead of 0.45 g sodium peroxide sulfate 0.45 g AIBA were used.

The resulting cloudy reaction mixture was by means of transmis examined by electron microscopic measurements. It could only pure polymer particles and the dispersed silicon dioxide particles are found. Raspberry-shaped composite particles were undetectable.

Comparative Example 3

Comparative Example 1 was repeated except that add 20 g of deionized and 20 g of Nyacol® 2040 oxygen-free water in the reaction vessel were submitted. This gave a stable, milky white polymer dispersion, which under the above conditions (3000 rev gen per minute, duration 20 minutes) did not sediment.

Comparative Example 4

With stirring, at room temperature within 5 minutes 2.0 g of Nyacol® 2040 in 24.1 g of the stable polymer dispersion stirred from Comparative Example 3, wherein a stable aqueous Dispersion was obtained.

Comparison of the film properties

Exemplary film properties of the aqueous composite Particle dispersion from Example 18 (dispersion A) and the Dispersions from Comparative Example 3 (dispersion B) and Comparative Example 4 (dispersion C) accessible polymer films were compared.

a) Minimum film-forming temperature (MFT) and glass transition temperature temperature (Tg)

The MFT was determined in accordance with ISO 2115 and the Tg Values were determined according to DIN 53765. The values obtained are given in Table 1.  

Table 1

MFT and Tg values of the polymer films from dispersions A to C.

b) Film hardness

Dispersions A to C were coated with a 250 μm wet layer Thickness applied to glass plates and 4 days at 23 ° C and Dried 50% relative humidity. The film hardness was determined by the method of König (DIN 53157). there the higher the attenuation time, the harder the film is. The values given in Table 2 prove that the from the Composite Particle Dispersion A film formed the greatest hardness shows.

Table 2 Hardness of the polymer films from the dispersions A to C.

dispersion King hardness damping time in sec A 77.2 B 34.5 C 59.2

c) water absorption

From the dispersions A to C, polymer films (drying at 23 ° C. and 50% relative humidity for 4 days) having a specific gravity of 100 mg / cm ² were prepared. 2 cm × 5 cm film strips were dipped in deionized water at room temperature. After a defined time, the filmstrips were removed from the water, dried with a dry cotton cloth, and weighed immediately. The so-called water absorption is calculated according to the following formula:

Here, weight _{0 means} the weight of the dry film before immersion in the water and weight _wet the weight of the film which has been immersed in the water for a defined time and then dried with a dry cotton cloth. The water absorption of the polymer films from the dispersions A to C after defined times is given in Table 3. It can be clearly seen that the film formed from the composite particle dispersion A shows the lowest water absorption.

Table 3

Water absorption of the polymer films formed from the dispersions A to C.

Claims (14)

1. A process for the preparation of an aqueous dispersion of particles of polymer and finely divided inorganic solid particles in which at least one ethylenically unge saturated monomer dispersed in aqueous medium and by means of at least one free radical polymerization initiator in the presence of at least one dispersed, finely divided inorganic solid and at least one dispersant is polymerized by the method of free-radically aqueous emulsion polymerization, characterized in that

• a) a stable aqueous dispersion of at least one is used to organic solid, which is characterized in that it at an initial solids concentration of ≧ 1 wt .-%, based on the aqueous dispersion of the at least one solid, one hour after their preparation contains more than 90% by weight of the initially dispersed solid in dispersed form and whose dispersed solid particles have a weight-average diameter of ≦ 100 nm,
• b) the dispersed solid particles of at least one inorganic solid in a standard aqueous potassium chloride solution at a pH which corresponds to the pH of the aqueous reaction medium at the beginning of the Emulsionspoly merization show a non-zero elec trophoretic mobility

and

• a) the radical-generating component of the at least one free-radical polymerization initiator and / or the dis pergierend acting component of the at least one dispersant at least one electrical charge, whose sign opposite to the sign of the electrophoretic mobility of the dispersed solid material particles of the at least one solid, this in a standard aqueous potassium chloride solution at a pH which corresponds to the pH of the aqueous reaction medium at the beginning of the emulsion polymerization have.

2. The method according to claim 1, characterized in that the at least one inorganic solid at least one Ele selected from the group comprising magnesium, calcium, Strontium, barium, boron, titanium, chromium, iron, cobalt, nickel, Copper, zinc, tin, zirconium, cerium, yttrium, aluminum, sili zium, phosphorus, antimony and bismuth. 3. The method according to any one of claims 1 or 2, characterized marked characterized in that the at least one inorganic solid is selected from the group comprising silicon dioxide, Alumina, hydroxyaluminum oxide, calcium carbonate, Magnesium carbonate, calcium orthophosphate, magnesium ortho phosphate, ferric oxide, ferric oxide, ferric (II / III) oxide, tin dioxide, ceria, yttrium (III) oxide, titanium dioxide, hydroxyapatite, zinc oxide and zinc sulfide. 4. The method according to any one of claims 1 to 3, characterized marked characterized in that the at least one inorganic solid in Water at 20 ° C and 1 bar (absolute) solubility ≦ 1 g / l Has water. 5. The method according to any one of claims 1 to 4, characterized marked characterized in that the at least one dispersant anio is nischer emulsifier. 6. The method according to any one of claims 1 to 4, characterized gekenn characterized in that the at least one dispersant is a kat is ionic emulsifier. 7. The method according to any one of claims 1 to 4, characterized marked characterized in that the at least one dispersant is a kat is ionic emulsifier. 8. The method according to any one of claims 1 to 4, characterized marked characterized in that the at least one dispersant is a kat ionic protective colloid is. 9. The method according to any one of claims 1 to 8, characterized marked characterized in that the at least one radical Polymerisati Onsinitiator is selected from the group comprising sodium peroxodisulfate, potassium peroxodisulfate and ammonium peroxo disulfate. 10. The method according to any one of claims 1 to 8, characterized marked characterized in that the at least one radical Polymerisati onsinitiator 2,2'-azobis (amidinopropyl) dihydrochloride.   11. Aqueous dispersion of composite particles, obtainable according to A method according to any one of claims 1 to 10. 12. Aqueous dispersion according to claim 11, characterized that ≧ 50 wt .-% of the finely divided solid particles, based on the total amount of those contained in the composite particles finely divided solid particles, on the surface of Polymer matrix are bonded. 13. Use of an aqueous dispersion of composite particles according to claim 11 or 12, as an adhesive, as a binder, for the preparation of a protective layer, for the modification of Cement and mortar formulations or in the medical Diagnostics. 14. Composite particle powder, obtainable by drying a aqueous dispersion of composite particles according to claim 11 or 12.