EP1618254A2

EP1618254A2 - Method for the treatment of paper surfaces

Info

Publication number: EP1618254A2
Application number: EP04727277A
Authority: EP
Inventors: Harm Wiese; Hubertus KRÖNER
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2003-04-17
Filing date: 2004-04-14
Publication date: 2006-01-25
Also published as: DE10318066A1; CN1791722A; WO2004092481A2; JP2006523783A; US20060191653A1; AU2004231028A1; BRPI0409416A; CA2522620A1; AU2004231028B2; WO2004092481A3

Abstract

The invention relates to a method for the treatment of paper surfaces.

Description

Process for treating paper surfaces

description

The present invention relates to a method for treating paper surfaces, which is characterized in that the surface of the paper is coated with particles (composite particles) which are composed of polymer and finely divided inorganic solid, the weight-average particle size of the finely divided inorganic solid Is <100 nm.

The present invention also relates to a process for the treatment of paper surfaces, which is characterized in that the surface of the paper is coated with an aqueous dispersion, which by mixing an aqueous polymer dispersion with at least one dispersed, finely divided inorganic solid, which has a weight-average particle diameter <100 nm, is available, is treated.

Papers are used in many ways. Depending on their intended use, the papers must be easily writable or printable (e.g. writing paper, newsprint, paper for journals, catalogs, books etc.), absorbent (e.g. paper handkerchiefs, serviettes, kitchen paper and hygienic paper) or also very hard-wearing , such as banknote paper, thin printing paper, kraft paper, capacitor paper or photo paper.

Particularly in the case of the writable and printable papers and the very stressed papers, the paper surfaces are often subjected to additional treatment steps in order to achieve the required properties. In particular, the paper surfaces are coated with paper coating slips or treated with paper sizing agents.

Paper coating slips essentially consist of a polymeric binder, one or more pigments and various other auxiliaries. Coating with paper coating slips gives base papers a hard-wearing, smooth white surface with improved printability.

The binders used in paper coating slips are usually acrylate or styrene / butadiene copolymers. Corresponding paper coating slips are described, for example, in WO 97/00776, EP-A 1101425 and in EP-A 1132521. The paper sizes are generally non-pigmented binders, such as starches, proteins, resin glues, and aqueous polymer dispersions, and in particular starch-containing aqueous polymer dispersions, which are described, for example, in documents EP-A 307816, EP-A 735065, DE- A 3627494 and DE-A 10039388 are described. The gluing in particular strengthens the fiber structure and thus improves the water resistance and the writability and printability. The pigments and fillers are also better fixed.

The object of the present invention was to provide a new method for surface modification of paper.

Accordingly, the methods defined at the outset were found.

In the context of this document, paper is to be understood as a flat material according to DIN 6730 (August 1985), consisting essentially of fibers of predominantly vegetable origin, which is formed on a sieve by dewatering a fiber suspension containing various auxiliaries, the fiber felt thus obtained is then compressed and dried. As auxiliaries, for example fillers, dyes, pigments, binders, optical brighteners, retention aids, wetting agents, defoamers, preservatives, slime control agents, plasticizers, antiblocking agents, antistatic agents, water repellents, etc., are used. Depending on the basis weight of the sheet material obtained, one also speaks of raw paper (basis weight <225 g / m ² ) or of raw cardboard (basis weight> 225 g / m ² ). In addition, the term "cardboard" is also used, which with a basis weight of approx. 150 to 600 g / m ²

Types of base paper as well as types of raw cardboard include. For the sake of simplicity, the term "base paper" is intended to include both base paper, base paperboard and cardboard.

Often, the base paper is refined by the so-called coating, or converted into the finished use form. Coating of paper is understood to mean coating the paper on one or both sides with an aqueous coating slip consisting essentially of pigments and binders. Depending on the type of coating color, the layer thickness to be achieved or the type of paper to be produced, different coating methods are used for this purpose, for example the roller, doctor blade, air brush or cast coating methods known to the person skilled in the art, each of which is followed by a drying step. The papers treated in this way are referred to as "coated papers". Another method of treating paper is to treat the paper surfaces with sizing agents. The papers treated in this way are referred to as "sized papers".

It is essential that the methods according to the invention are suitable both for base papers and for coated and sized papers.

In one embodiment, the composite particles are applied to the paper surface in the form of an aqueous composite particle dispersion (method 1).

Aqueous dispersions of composite particles are generally known. These are fluid systems which contain, as a disperse phase in an aqueous dispersion medium, polymer balls consisting of a plurality of intertwined polymer chains, the so-called polymer matrix and finely divided inorganic solid particles in dispersed distribution. The diameter of the composite particles is often in the range from 30 nm to 5000 nm.

Composite particles and processes for their preparation in the form of aqueous composite particle dispersions are known to the person skilled in the art and are described, for example, in the documents US-A 3,544,500, US-A 4,421, 660, US-A 4,608,401, US-A 4,981, 882, EP-A 104498, EP -A 505 230, EP-A 572 128, GB-A 2227 739, WO 0118081, WO 0129106 and in Long et al., Tianjin Daxue Xuebao 1991, 4, pages 10 to 15, Bourgeat-Lami et al., Die Angewandte Macromolecular Chemistry 1996, 242, pages 105 to 122, Paulke et al., Synthesis Studies of Paramagnetic Polystyrene Latex Particles in Scientific and Clinical Applications of Magnetic Carriers, pages 69 to 76, Plenum Press, New York, 1997, Armes et al., Advanced Materials 1999, 11, No. 5, pages 408 to 410.

Also suitable according to the invention are, for example, aqueous composite particle dispersions which have been prepared in accordance with the procedure disclosed in WO 03000760. This process is characterized in that at least one ethylenically unsaturated monomer is dispersed in an 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 anionic, cationic and nonionic dispersant using the free radical method - Is polymerized aqueous emulsion polymerization, wherein

a) a stable aqueous dispersion of the at least one inorganic solid is used, which is characterized in that, at an initial solid concentration of> 1% by weight, based on the aqueous dispersion of the at least one inorganic solid, it is still one hour after its preparation. contains more than 90% by weight of the originally dispersed solid in dispersed form and whose dispersed solid particles have a diameter of <100 nm,

b) the dispersed solid particles of the at least one inorganic solid in an aqueous standard potassium chloride solution have a non-zero electrophoretic mobility at a pH which corresponds to the pH of the aqueous reaction medium before the start of the addition of the dispersants,

c) at least one anionic, cationic and nonionic dispersant is added to the aqueous solid particle dispersion before the addition of the at least one ethylenically unsaturated monomer is started,

d) then 0.01 to 30% by weight of the total amount of the at least one monomer is added to the aqueous solid particle dispersion and polymerized until a conversion of at least 90%

and

e) the remaining amount of the at least one monomer is then added continuously under polymerisation conditions in accordance with the consumption.

All those finely divided inorganic solids are suitable for this process which form stable aqueous dispersions which, at an initial solids concentration of> 1% by weight, based on the aqueous dispersion of the at least one inorganic solid, continue for one hour after their preparation without stirring or shaking contain more than 90% by weight of the originally dispersed solid in dispersed form and whose dispersed solid particles have a diameter of <100 nm and moreover at a pH which corresponds to the pH of the aqueous reaction medium before the addition of the dispersants, show non-zero electrophoretic mobility.

The quantitative determination of the initial solids concentration and the solids concentration after one hour and the determination of the particle diameter is carried out using the analytical ultracentrifuge method (cf. 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, pages 147 to 175). The values given for the particle diameter correspond to the so-called d ₅₀ values.

The method for determining electrophoretic mobility is known to the person skilled in the art (see, for example, RJ 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 solid particles dispersed in the aqueous reaction medium is determined using a commercially available electrophoresis device, such as the Zetasizer 3000 from Malvern Instruments Ltd., at 20 ° C. and 1 bar (absolute). For this purpose, the aqueous solid particle dispersion is diluted with a pH-neutral 10 millimolar (mM) aqueous potassium chloride solution (standard potassium chloride solution) to such an extent that the solid particle concentration is approximately 50 to 100 mg / l. The pH of the measurement sample, which the aqueous reaction medium has before the addition of the dispersants, is adjusted by means of the common inorganic acids, such as, for example, dilute hydrochloric acid or nitric acid, or bases, such as, for example, dilute sodium hydroxide solution or potassium hydroxide solution. The migration of the dispersed solid particles in the electric field is detected by means of so-called electrophoretic light scattering (see e.g. B.R. Ware and W.H. Flygare, Chem. Phys. Lett.

1971, 12, pages 81 to 85). The sign of the electrophoretic mobility is defined by the direction of migration of the dispersed solid particles, i.e. If the dispersed solid particles migrate to the cathode, their electrophoretic mobility is positive, but if they migrate to the anode, they are negative.

A suitable parameter in order to influence or adjust the electrophoretic mobility of dispersed solid particles to a certain extent is the pH of the aqueous reaction medium. Protonation or deprotonation of the dispersed solid particles changes the electrophoretic mobility in the acidic pH range (pH <7) in the positive direction and in the alkaline range (pH> 7) in the negative direction. A suitable pH range for the process disclosed in WO 03000760 is the one within which a free-radically initiated aqueous emulsion polymerization can be carried out. This pH range is usually pH 1 to 12, often pH 1.5 to 11 and often pH 2 to 10.

The pH of the aqueous reaction medium can be adjusted using commercially available acids, such as, for example, dilute hydrochloric, nitric or sulfuric acid, or bases, such as, for example, dilute sodium or potassium hydroxide solution. It is often beneficial if some or all of the amount used to adjust the pH Amount of acid or base is added to the aqueous reaction medium before the at least one finely divided inorganic solid.

It is essential for the method disclosed according to WO 033000760 that when the dispersed solid particles under the aforementioned pH conditions

have an electrophoretic mobility with a negative sign, per 100 parts by weight of the at least one ethylenically unsaturated monomer, 0.01 to 10 parts by weight, preferably 0.05 to 5 parts by weight and particularly preferably 0.1 to 3 parts by weight Parts of at least one cationic dispersant, 0.01 to

100 parts by weight, preferably 0.05 to 50 parts by weight and particularly preferably 0.1 to 20 parts by weight of at least one nonionic dispersant and at least one anionic dispersant are used, the amount of which is such that the equivalent Ratio of anionic to cationic dispersant is greater than 1, or

have an electrophoretic mobility with a positive sign, per 100 parts by weight of the at least one ethylenically unsaturated monomer, 0.01 to 10 parts by weight, preferably 0.05 to 5 parts by weight and particularly preferably 0.1 to 3 parts by weight Parts of at least one anionic dispersant, 0.01 to 100

Parts by weight, preferably 0.05 to 50 parts by weight and particularly preferably 0.1 to 20 parts by weight, of at least one nonionic dispersant and at least one cationic dispersant are used, the amount of which is such that the equivalent ratio from cationic to anionic dispersant is greater than 1.

Under the equivalent ratio of anionic to cationic dispersant, the ratio of the number of moles of anionic dispersant used is multiplied by the number of anionic groups contained per mole of anionic dispersant, divided by the number of moles of cationic dispersant used, multiplied by the number of cationic dispersants per mole of cationic dispersant Understood groups. The same applies to the equivalent ratio of cationic to anionic dispersant.

The total amount of the at least one anionic, cationic and nonionic dispersant used in accordance with WO 03000760 can be introduced into the aqueous solid dispersion. However, it is also possible to put only a subset of the dispersants mentioned in the aqueous solid dispersion and to add the remaining amounts continuously or discontinuously during the radical emulsion polymerization. However, what is essential to the procedure is that the aforementioned equivalent ratio of anionic and cationic dispersant is maintained depending on the electrophoretic sign of the finely divided solid before and during the free radical initiated emulsion polymerization. If inorganic solid particles are therefore used which have an electrophoretic mobility with a negative sign under the aforementioned pH conditions, the equivalent ratio of anionic to cationic dispersant must be greater than 1 during the entire emulsion polymerization. Correspondingly, in the case of inorganic solid particles with an electrophoretic mobility with a positive sign, the equivalent ratio of cationic to anionic dispersant must be greater than 1 during the entire emulsion polymerization. It is expedient if the equivalent ratios are>2,> 3, ≥ 4,>5,>6,> 7, or> 10, the equivalent ratios in the range between 2 and 5 being particularly favorable.

Another method for treating paper surfaces is characterized in that the surface of the paper is treated with an aqueous dispersion, which by mixing an aqueous polymer dispersion with at least one dispersed, finely divided organic solid, which has a weight-average particle diameter <100 nm ( Procedure 2).

Aqueous polymer dispersions are generally known. These are fluid systems which, as a disperse phase in an aqueous dispersion medium, contain polymer balls consisting of a plurality of intertwined polymer chains, the so-called polymer matrix or polymer particles, in disperse distribution. The diameter of the polymer particles is often in the range from 10 to 5000 nm.

An aqueous polymer dispersion is prepared, for example, by means of free-radically initiated aqueous emulsion polymerization. The implementation of a radically initiated aqueous emulsion polymerization of ethylenically unsaturated monomers has been described many times and is therefore sufficiently known to the person skilled in the art [cf. e.g. Encyclopedia of Polymer Science and Engineering, Vol. 8, pages 659 to 677, John Wiley & Sons, Inc., 1987; DC Blackley, Emulsion Polymerization, pages 155 to 465, Applied Science Publishers, Ltd., Essex, 1975; . DC Blackley, polymer latices, 2 ^πd Edition, Vol 1, pages 33 to 415, Chapman & Hall, 1997; H. Warson, The Applications of Synthetic Resin Emulsions, pages 49 to 244, Ernest Benn, Ltd., London, 1972; D. Diederich, Chemistry in our time 1990, 24, pages 135 to 142, Verlag Chemie, Weinheim; J. Piirma, Emulsion Polymerization, Ropes 1 to 287, Academic Press, 1982; F. Hölscher, dispersions of synthetic high polymers, pages 1 to 160, Springer-Verlag, Berlin, 1969 and the patent specification DE-A 40 03422]. It usually takes Usually in such a way that the ethylenically unsaturated monomers are dispersed in an aqueous medium, with the use of dispersants, and polymerized by means of at least one radical polymerization initiator. The method disclosed in WO 03000760 differs from this procedure only in the additional presence of at least one finely divided inorganic solid which has a non-zero electrophoretic mobility and the use of a special dispersant combination during the polymerization.

Fine-particle inorganic solids which can be used for both processes according to the invention are suitable for metals, metal compounds, such as metal oxides and metal salts, but also for semi-metal and non-metal compounds. Fine metal colloids, such as, for example, palladium, silver, ruthenium, platinum, gold and rhodium, and alloys containing these can be used as finely divided metal powders. Examples of finely divided metal oxides are titanium dioxide (for example commercially available as Hombitec ^® brands from Sachtleben Chemie GmbH), zirconium (IV) oxide, tin (II) oxide, tin (IV) oxide ( for example commercially available as Nyacol ^® SN brands from Akzo-Nobel), aluminum oxide (for example commercially available as Nyacol ^® AL brands 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, antimony (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 grades from. Akzo-Nobel), cerium (IV) oxide (for example, commercially available as Nyacol ^® CE02 grades from. Akzo-Nobel) amorphous and / or in their different crystal modifications as well as their hydroxyoxides such as Hydroxyti - tan (IV) oxide, Hydroxyzirkonium- (IV) oxide, hydroxyaluminum (for example commercially available as Disperal ^® brands from Condea-Chemie GmbH.) and hydroxyiron (III) oxide, amorphous / or in its various and crystal modifications. The following amorphous metal salts and / or their different crystal structures can in principle be used in the process according to the invention: sulfides such as iron (II) sulfide, iron (III) sulfide, iron (II) disulfide (pyrite), tin (ll) sulfide, tin (IV) sulfide, mercury (ll) sulfide, cadmium (ll) sulfide, zinc sulfide, copper (II) sulfide, silver sulfide, nickel (ll) - 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 tin (II) 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, orthophosphates 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 melaphosphate, calcium metaphosphate, aluminum metaphosphate, pyrophosphates, such as magnesium pyrophosphate, calcium pyrophosphate, zinc pyrophosphate, iron (III) pyrophosphate, tin (II) pyrophosphate, ammonium phosphates, such as magnesium ammonium phosphate, zinc ammonium phosphate, hydroxylapalite [Ca ₅ {(Pθ ₄ ) ₃ OH}], orthosilicates, such as lithium orthosilicate, calcium / magnesium orthosilicate, aluminum orthosilicate, iron (II) orthosilicate, iron (III ) orthosilicate, magnesium orthosilicate, zinc orthosilicate, zirconium (III) orthosilicate, zirconium (IV) orthosilicate, metasilicals, such as lithium metasilicate, calcium / magnesium metasilicate, calcium metasilicate, magnesium melasilicate, zinc metasilicate, layered silicates, such as sodium aluminum silicate and sodium magnesium silicate, especially in spontaneously delaminating form, such as, for example, Optigel ^® SH (brand of Südchemie AG), Saponit ^® SKS-20 and Hektorit ^® SKS 21 (brands of Hoechst AG) as well as 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, tatrates such as calcium tatate, acetylacetonate , such as aluminum acetylacetonate, 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.

Amorphous silicon dioxide and / or silicon dioxide present in different crystal structures may be mentioned as the essential semimetal compound which can be used according to the invention. According to the invention suitable silica is commercially available and can examples example as Aerosil ^® (trademark of. Degussa AG), Levasil® ^® (trademark of. Bayer AG), Ludox ^® (trademark of. DuPont), Nyacol ^® and Bindzil ^® ( Brands from Akzo-Nobel) and Snowtex ^® (brand from Nissan Chemical Industries, Ltd.). Non-metal compounds suitable according to the invention are, for example, colloidal graphite or diamond.

Particularly suitable as finely divided inorganic solids are those whose solubility in water at 20 ° C. and 1 bar (absolute) is <1 g / l, preferably <0.1 g / l and in particular <0.01 g / l. Compounds are particularly preferably selected from the group comprising silicon dioxide, aluminum oxide, tin (IV) oxide, yttrium (III) oxide, cerium (IV) oxide, hydroxyaluminium oxide, calcium carbonate, magnesium carbonate, calcium orthophosphate, magnesium orthophosphate, 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. Silicon dioxide sols which have an electrophoretic mobility with a negative sign are particularly preferred.

The commercially available compounds of the Aerosil ^® , Levasil ^® , Ludox ^® , Nyacol ^® and Bindzil ^® brands (silicon dioxide), Disperal ^® brands (hydroxyaluminium oxide), Nyacol ^® AL brands (aluminum oxide), Hombitec can also be used advantageously ^® brands (titanium dioxide), Nyacol ^® SN brands (tin (IV) oxide), Nyacol ^® YTTRIA brands (yttrium (III) oxide), Nyacol ^® CE02 brands (cerium (IV) oxide) and Sachtotec ^® brands (zinc oxide) can be used in the process according to the invention.

The finely divided inorganic solids which can be used in the processes according to the invention are such that the solid particles dispersed in the aqueous reaction medium have a particle diameter of <100 nm. Such finely divided inorganic solids are successfully used, the dispersed particles of which have a 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. It is advantageous to use finely divided inorganic solids which have a particle diameter of <50 nm. The particle diameter is determined using the analytical ultracentrifuge method.

The accessibility of finely divided solids is known in principle to the person skilled in the art and is carried out, for example, by precipitation reactions 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; DF Evans, H. Wennerström in The Colloidal Domain, pages 363 to 405, Verlag Chemie, Weinheim, 1994 and RJ Hunter in Foundations of Colloid Science, Vol. I , Pages 10 to 17, Clarendon Press, Oxford, 1991).

The stable solid dispersion is often produced directly in the synthesis of the finely divided inorganic solids in an aqueous medium or alternatively by dispersing the finely divided inorganic solid in the aqueous medium. Depending on the way in which the finely divided inorganic solids are produced, this can be done either directly, for example in the case of precipitated or pyrogenic silicon dioxide, aluminum oxide, etc., or with the aid of suitable auxiliary units, such as, for example, dispersants or ultrasonic sonotrodes. According to the invention, however, only those fine-particle inorganic solids are suitable whose aqueous solid dispersion at an initial solid concentration of> 1% by weight, based on the aqueous dispersion of the fine-particle inorganic solid, is still one hour after their preparation or by stirring or shaking the sedimented solids, contains more than 90% by weight of the originally dispersed solid in dispersed form without further stirring or shaking and the dispersed solid particles have a diameter of <100 nm. Initial solids concentrations of <60% by weight are common. However, initial solids concentrations of <55% by weight, <50% by weight, <45% by weight, <40% by weight, <35% by weight, <30% by weight, <25% by weight can also be advantageous .-%, <20 wt.%, <15 wt.%, <10 wt.% And> 2 wt.%,> 3 wt.%,> 4 wt.% Or> 5 wt. -% and all values in between, based in each case on the aqueous dispersion of the finely divided inorganic solid. Based on 100 parts by weight of the at least one ethylenically unsaturated monomer in the preparation of aqueous composite particle dispersions (process 1) or 100 parts by weight of dispersion polymer (process 2), according to the invention, 1 to 1000 parts by weight, generally 5 up to 300 parts by weight and often 10 to 200 parts by weight of the at least one finely divided inorganic solid.

Both in the production of the aqueous composite particle dispersion and in the production of the aqueous polymer dispersion and in the mixing thereof with the finely divided inorganic solid, dispersants are used, which include both the finely divided inorganic solid particles and the monomer droplets and the composite particles formed or the mixture of the polymer particles and the like keep finely divided inorganic solids dispersed in the aqueous phase and thus ensure the stability of the aqueous dispersions produced. Suitable dispersants are both the protective colloids usually used to carry out free-radical aqueous emulsion polymerizations and emulsifiers.

A detailed description of suitable protective colloids can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular Substances, Georg-Thieme-Verlag, Stuttgart, 1961, pages 411 to 420.

Suitable neutral protective colloids are, for example, polyvinyl alcohols, polyalkylene glycols, cellulose, starch and gelatin derivatives.

Anionic protective colloids, ie protective colloids whose dispersing component has at least one negative electrical charge, include, for example, polyacrylic acids and polymethacrylic acids and their alkali metal salts, Acrylic acid, methacrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, 4-styrene sulfonic acid and / or copolymers containing maleic anhydride and their alkali metal salts and alkali metal salts of sulfonic acids of high molecular weight compounds such as polystyrene, into consideration.

Suitable cationic protective colloids, i.e. Protective colloids whose dispersing component has at least one positive electrical charge are, for example, the derivatives of N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylcarbazole, 1-vinylimidazole, 2-vinylimidazole, 2-vinylimidazole, 2-vinylpyridine, protonated and / or alkylated on the nitrogen -Vinylpyridine, acrylamide, methacrylamide, acrylate-bearing acrylates, methacrylates, acrylamides and / or homo- and copolymers containing methacrylamides.

Mixtures of emulsifiers and / or protective colloids can of course also be used. Often only emulsifiers are used as dispersants, the relative molecular weights of which, in contrast to the protective colloids, are usually below 1500. Of course, if mixtures of surface-active substances are used, the individual components must be compatible with one another, which can be checked in the case of doubt using a few preliminary tests. An overview of suitable emulsifiers can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular Substances, Georg-Thieme-Verlag, Stuttgart, 1961, pages 192 to 208.

Common nonionic emulsifiers are, for example, ethoxylated mono-, di- and tri-alkylphenols (EO grade: 3 to 50, alkyl radical: C ₄ to C ₁₂ ) and ethoxylated fatty alcohols (EO degree: 3 to 80; alkyl radical: C ₈ to C) ₃₆ ). Examples are the Lutensol ^® A grades (Cι ₂ C ₁₄ fatty alcohol ethoxylates, EO units: 3 to 8), Lutensol ^® AO-marks (C ₁₃ C ₁₅ - Oxoalkoholethoxilate, EO units: 3 to 30) Lutensol ^® AT brands (C ₁₆ C ₁₈ - fatty alcohol ethoxylates, EO grade: 11 to 80), Lutensol ^® ON brands (C ₁₀ - oxo alcohol ethoxylates, EO grade: 3 to 11) and the Lutensol ^® TO brands (C ₁₃ - Oxo alcohol ethoxylates, EO grade: 3 to 20) from BASF AG.

Typical anionic emulsifiers are, for example, alkali metal and ammonium salts of alkyl sulfates (alkyl radical: C ₈ to C ₁₂ ), of sulfuric acid semiesters of ethoxylated alkanols (EO degree: 4 to 30, alkyl radical: C ₁₂ to C ₁₈ ) and ethoxylated alkylphenols (EO- Grade: 3 to 50, alkyl radical: C ₄ to C ₁₂ ), of alkyl sulfonic acids (alkyl radical: C ₁₂ to C ₁₈ ) and of alkylarylsulfonic acids (alkyl radical: C ₉ to C ₁₈ ).

Compounds of the general formula I have also proved to be further anionic emulsifiers

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 can be alkali metal ions and / or ammonium ions. In the general formula I, R ¹ and R ^{2 are} preferably linear or branched alkyl radicals having 6 to 18 carbon atoms, in particular having 6, 12 and 16 carbon atoms or -H, where R ¹ and R ^{2 are} not both H atoms at the same time are. A and B are preferably sodium, potassium or ammonium, with sodium being particularly preferred. 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 are particularly advantageous. Industrial mixtures are used which have a share of 50 to 90 wt .-% of the monoalkylated product, for example Dowfax ^® 2A1 (trademark of Dow Chemical Company). The compounds I are generally known, for example from US Pat. No. 4,269,749, and are commercially available.

Suitable cationic emulsifiers are generally a primary, secondary, tertiary or quaternary ammonium salt, alkanolammonium salt, pyridinium salt, imidazolinium salt, oxazolinium salt, morpholinium salt and thiazolinium salt, and a C ₆ -C ₁₈ alkyl, aralkyl or heterocyclic radical Amine oxides, quinolinium salts, isoquinolinium salts, tropylium salts, sulfonium salts and phosphonium salts. Examples include dodecylammonium acetate or the corresponding hydrochloride, the chlorides or acetates of the various 2- (N, N, N-trimethylammonium) ethyl paraffinic acid esters, N-cetylpyridinium chloride, N-lauryl-pyridinium sulfate and N-cetyl-N, N, N-trimethylammonium bromide. N-DodecyI-N, N, N-trimethylammonium bromide, N-octyl-N, N, N, N-trimethlyammonium bromide, N, N-distearyl-N, N-dimethylammonium chloride and the gemini surfactant N, N '- (lauryldimethyl) - ethylenediamine dibromide , Numerous other examples can be found in H. Stächen, Tensid-Taschenbuch, Carl-Hanser-Verlag, Munich, Vienna, 1981 and in McCutcheon's, Emulsifiers & Detergents, MC Publishing Company, Glen Rock, 1989.

The aqueous dispersions which can be used according to methods 1 and 2 according to the invention generally contain between 0.1 to 10% by weight, often 0.5 to 7.0% by weight and often 1.0 to 5.0% by weight. % of dispersant, based in each case on the aqueous dispersion. Emulsifiers are preferably used.

For the production of the composite particles which can be used according to the invention (process 1) and the dispersion polymer used according to the invention (process 2) as an ethylenically unsaturated monomer, inter alia, in particular in a simple manner, radically polymerizable monomers, such as ethylene, vinyl aromatic monomers such as styrene, α-methylstyrene, o-chlorostyrene or vinyl toluenes, esters of vinyl alcohol and monocarboxylic acids having 1 to 18 carbon atoms , such as vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl laurate and vinyl stearate, esters of σ,? -monoethylenically unsaturated mono- and dicarboxylic acids preferably having 3 to 6 carbon atoms, such as 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, acrylic acid and methacrylic acid methyl, ethyl, n-butyl, isobutyl and -2 -ethylhexyl ester, maleic acid dimethyl ester or maleic acid di-n-butyl ester, nitrite σ,? -monoβthylenically unsaturated carboxylic acids, such as acrylonitrile and C. _8- conjugated dienes such as 1, 3-butadiene and isoprene. The monomers mentioned generally form the main monomers which, based on the total amount of the monomers to be polymerized by the process according to the invention, normally have a proportion of> 50% by weight,> 80% by weight or> 90% by weight unite on itself. As a rule, these monomers have only moderate to low solubility in water at normal conditions [20 ° C., 1 bar (absolute)].

Monomers which usually increase the internal strength of the films of the polymer matrix normally have at least one epoxy, hydroxyl, N-methylol or carbonyl group, or at least two non-conjugated ethylenically unsaturated double bonds. Examples of these are two monomers having vinyl residues, two monomers having vinylidene residues and two monomers having alkenyl residues. The di-esters of dihydric alcohols with α, β-mono-ethylenically unsaturated monocarboxylic acids are particularly advantageous, among which acrylic and methacrylic acid are preferred. Examples of such monomers having two non-conjugated ethylenically unsaturated double bonds 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 and ethylene diacrylate, 1, 4-butylene glycol diacrylate, 1 1,2-propylene glycol dimethacrylate, 1,3-propylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate as well as divinylbenzene, vinyl methacrylate, vinyl acrylate, allyl methacrylate, allyl acrylate, triallyl maleate, triallyl malylate, diallyl malylate, diallyl malylate, cyclo Of particular importance in this context are the methacrylic acid and acrylic acid CrCs hydroxyalkyl esters such as n-hydroxyethyl, n-hydroxypropyl or n-hydroxybutyl acrylate and methacrylate, and compounds such as diacetone acrylamide and acetylacetoxyethyl acrylate or methacrylate. According to the invention, the aforementioned monomers, based on the total amount of the monomers to be polymerized, are polymerized in amounts of up to 5% by weight. Monomers containing siloxane groups are also optional, such as vinyltrialkoxysilanes, for example vinyltrimethoxysilane, alkylvinyldialkoxysilanes, acryloxyalkyltrialkoxysilanes, or methacryloxyalkyltrialkoxysilanes, such as, for example, acryloxyethyltrimethoxysilane, methacryloxyethyltrimethoxysilane trimethoxysiloxyliloxysiloxysilane, or These monomers are used in amounts of up to 2% by weight, frequently from 0.01 to 1% by weight and often from 0.05 to 0.5% by weight, in each case based on the total amount of monomers.

In addition, those ethylenically unsaturated monomers A which either have at least one acid group and / or their corresponding anion or those ethylenically unsaturated monomers B which have at least one amino, amido, ureido or N-heterocyclic group and / or can also be used as monomers which contain ammonium derivatives protonated or alkylated on nitrogen. Based on the total amount of monomers, the amount of monomers A or monomers B is up to 10% by weight, often 0.1 to 7% by weight and often 0.2 to 5% by weight.

As monomers A, ethylenically unsaturated monomers with at least one acid group are used. The acid group can be, for example, a carboxylic acid, sulfonic acid, sulfuric acid, phosphoric acid and / or phosphonic acid group. Examples of monomers A are acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, 4-styrenesulfonic acid, 2-methacryloxyethylsulfonic acid, vinylsulfonic acid and vinylphosphonic acid as well as phosphoric acid monoesters of n-hydroxyalkyl acrylates and n-hydroxyalkyl methacrylates, such as, for example, phosphoric acid, ethyl monoester Hydroxypropyl acrylate, n

Hydroxybutyl acrylate and hydroxyethyl methacrylate, n-hydroxypropyl methacrylate or n-hydroxybutyl methacrylate. According to the invention, however, it is also possible to use the ammonium and alkali metal salts of the aforementioned ethylenically unsaturated monomers, some of which have an acid group. Sodium and potassium are particularly preferred as the alkali metal. Examples include the ammonium, sodium and potassium salts of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, 4-styrenesulfonic acid, 2-methacryloxyethylsulfonic acid, vinylsulfonic acid and vinylphosphonic acid as well as the mono- and di-ammonium, sodium and - Potassium salts of the phosphoric acid monoesters of hydroxyethyl acrylate, n-hydroxypropyl acrylate, n-hydroxybutyl acrylate and hydroxyethyl methacrylate, n-hydroxypropyl methacrylate or n-hydroxybutyl methacrylate.

Acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, 4-styrene sulfonic acid, 2-methacryloxyethyl sulfonic acid, vinyl sulfonic acid and vinyl phosphonic acid are preferably used. As monomers B, ethylenically unsaturated monomers are used which contain at least one amino, amido, ureido or N-heterocyclic group and / or their ammonium derivatives protonated or alkylated on nitrogen.

Examples of monomers B which contain at least one amino group are 2-aminoethyl acrylate, 2-aminoethyl methacrylate, 3-aminopropyl acrylate, 3-aminopropyl methacrylate, 4-amino-n-butyl acrylate, 4-amino-n-butyl methacrylate, 2- (N-methylamino) ethyl acrylate, 2- (N-methylamino) ethyl methacrylate, 2- (N-ethylamino) ethyl acrylate, 2- (N-ethylamino) ethyl methacrylate, 2- (Nn-

Propylamino) ethyl acrylate, 2- (Nn-propylamino) ethyl methacrylate, 2- (N-iso-propylamino) ethyl acrylate, 2- (N-iso-propylamino) ethyl methacrylate, 2- (N-tert-butylamino) ethyl acrylate, 2- ( N-tert-butylamino) ethyl methacrylate (for example commercially available as NORSOCRYL ^® TBAEMA Fa. Elf Atochem), 2- (N, N- dimethylamino) ethyl acrylate (for example commercially available as NORSOCRYL ^® A- DAME Fa. Elf Atochem) 2- (N, N-dimethylamino) ethyl methacrylate (for example commercially available as NORSOCRYL ^® MADAME Fa. Elf Atochem), 2- (N, N-diethylamino) ethyl acrylate, 2- (N, N-diethylamino) ethyl methacrylate, 2- ( N, N-di-n-propylamino) ethyl acrylate, 2- (N, N-di-n-propylamino) ethyl methacrylate, 2- (N, N-di-isopropylamino) ethyl acrylate, 2- (N, N-di -isopropylamino) ethyl methacrylate, 3- (N-methylamino) propyl acrylate, 3- (N-methylamino) propyl methacrylate, 3- (N-ethylamino) propyl acrylate, 3- (N-ethylamino) propyl methacrylate, 3- (Nn-propylamino) propyl acrylate, 3- (Nn-propylamino) propyl methacrylate, 3- (N-iso Propylamino) propyl acrylate, 3- (N-iso-propylamino) propyl methacrylate, 3- (N-tert-butylamino) propyl acrylate, 3- (N-tert-butylamino) propyl methacrylate, 3- (N, N-

Dimethylamino) propyl acrylate, 3- (N, N-dimethylamino) propyl methacrylate, 3- (N, N-diethylamino) propyl acrylate, 3- (N, N-diethylamino) propyl methacrylate, 3- (N, N-di-n-propylamino) propyl acrylate, 3- (N, N-di-n-propylamino) propyl methacrylate, 3- (N, N-di-isopropylamino) propyl acrylate and 3- (N, N-di-iso-propylamino) propyl methacrylate.

Examples of monomers B which contain at least one amido group are acrylamide, methacrylamide, N-methyl acrylamide, N-methyl methacrylamide, N-ethyl acrylamide, N-ethyl methacrylamide, Nn-propylacrylamide, Nn-propyl methacrylamide, N-isopropyl acrylamide and N-isopropyl methacrylamide , N-tert-butyl acrylamide, N-tert-butyl methacrylamide, N, N-dimethylacrylamide, NN-dimethyl methacrylamide, N, N-diethylacrylamide, N, N-diethyl methacrylamide, N, N-di-n-propylacrylamide, N, N -Di-n-propyl methacrylamide, N, N-di-iso-propylacrylamide, N, N-di-iso-propyl methacrylamide, N, N-di-n-butylacrylamide, N, N-di-n-butyl methacrylamide, N- ( 3-N ', N ^' - dimethylaminopropyl) methacrylamide, diacetone acrylamide, N, N'-methylenebisacrylamide, N- (Diphenylmethyl) acrylamide, N-cyclohexylacrylamide, but also N-vinylpyrrolidone and N-vinylcaprolactam.

Examples of monomers B, the ureido group contained at least N, N'-divinylethyleneurea and 2- (1-imidazolin-2-onyi) ethyl methacrylate (for example commercially available as NORSOCRYL ^® 100 from. Elf Atochem).

Examples of monomers B which contain at least one N-heterocyclic group are 2-vinylpyridine, 4-vinylpyridine, 1-vinylimidazole, 2-vinylimidazole and N-vinylcarbazole.

The following compounds are preferably used: 2-vinylpyridine, 4-vinylpyridine, 2-vinylimidazole, 2- (N, N-dimethylamino) ethyl acrylate, 2- (N, N-dimethylamino) ethyl methacrylate, 2- (N, N-diethylamino) ethyl acrylate , 2- (N, N-diethylamino) ethyl methacrylate, 2- (N-tert-butylamino) ethyl methacrylate, N- (3-N ', N'-dimethylaminopropyl) methacrylamide and 2- (1-imidazolin-2-onyl) ethyl methacrylate.

Depending on the pH of the aqueous reaction medium, some or all of the abovementioned nitrogen-containing monomers B can be present in the quaternary ammonium form protonated on nitrogen.

As monomers B, which have a quaternary Alkylammoniumstruktur on the nitrogen, may be mentioned by way of example, 2- (N, N, N-trimethyl ammonium) ethylacrylatchlorid (for example commercially available as NORSOCRYL ^® ADAMQUAT MC 80 from. Elf Atochem), 2- (N , N, N-trimethylammonium) ethyl methacrylate chloride (e.g., commercially available as NORSOCRYL MADQUAT ^® MC 75 from. Elf Atochem), 2- (N-methyl-N, N-diethylammonium) ethylacrylatchlorid, 2- (N-methyl-N, N - diethylammonium) ethyl methacrylate chloride, 2- (N-methyl-N, N-dipropylammonium) ethyl acrylate chloride, 2- (N-methyl-N, N-dipropylammonium) ethyl methacrylate, 2- (N-benzyl-N, N-dimethylammonium) ethyl acrylate chloride ( for example commercially available as NORSOCRYL ^® ADAMQUAT BZ 80 from. Elf Atochem), 2- (N-benzyl-N, N-dimethylammonium) ethyl methacrylate chloride (e.g., commercially available as NORSOCRYL ^® MADQUAT BZ 75 from. Elf Atochem), 2- ( N-benzyl-N, N-diethylammonium) ethyl acrylate chloride, 2- (N-benzyl-N, N-diethylammonium) ethyl methacrylate chloride, 2- (N-benzyl-N, N-dipropylammonium) ethyl acrylate chloride, 2- (N-benzyl-N, N-dipropylammonium) ethyl methacrylate chloride, 3- (N, N, N-trimethylammonium) propyiacrylatch ioride, 3- (N, N, N- trimethylammonium) propyl methacrylate chloride, 3- (N-methyl-N, N- diethylammonium) propyl acrylate chloride, 3- (N-methyl-N, N-diethylammonium) propyl methacrylate chloride, 3- (N-methyl-N, N-dipropylammonium) propyl acrylate chloride, 3- (N-methyl-N, N-dipropylammonium) propyl methacrylate chloride, 3 - (N-Benzyl-N, N-dimethylammonium) propyl acrylate chloride, 3- (N-benzyl-N, N-dimethylammonium) propyl methacrylate chloride, 3- (N-benzyl-N, N-diethylammonium) propylacrylate chloride, 3- (N-benzyl -N, N-diethylammonium) propylmβthacrylate chloride, 3- (N-benzyl-N, N-dipropylammonium) propylacrylate chloride and 3- (N-benzyl-N, N-dipropylammonium) propyl methacrylate chloride. The corresponding bromides and sulfates can of course also be used instead of the chlorides mentioned.

Preferred are 2- (N, N, N-trimethylammonium) ethyl acrylate chloride, 2- (N, N, N-trimethylammonium) ethyl methacrylate chloride, 2- (N-benzyl-N, N-dimethylammonium) ethyl acrylate chloride and 2- (N-benzyl) N, N-dimethylammonium) ethyl methacrylate chloride used.

Mixtures of the aforementioned ethylenically unsaturated monomers can of course also be used.

For the preparation of the aqueous composite particle dispersion and the aqueous polymer dispersion by free-radical polymerization, all those free-radical polymerization initiators which are capable of triggering a free-radical aqueous emulsion polymerization can be used. In principle, these can be both peroxides and azo compounds. Of course, redox initiator systems can also be used. In principle, inorganic peroxides, such as hydrogen peroxide or peroxodisulfates, such as the mono- or di-alkali metal or ammonium salts of peroxodisulfuric acid, such as, for example, their mono- and di-sodium, potassium or ammonium salts, or organic peroxides, such as alkylhydroperoxides, can be used as peroxides , for example tert-butyl, p-mentyl or cumyl hydroperoxide, and dialkyl or diaryl peroxides such as di-tert-butyl or di-cumyl peroxide can be used. As an azo compound essentially of 2,2'-azobis (isobutyronitrile), ^2,2'-azobis (2,4-dimethylvaleronitrile), and ^2,2'-azobis (amidinopropyI) dihydrochloride (AIBA, corresponding to V-50 from Wako Chemicals) Use. The above-mentioned peroxides are essentially suitable as oxidizing agents for redox initiator systems. Sulfur compounds with a low oxidation level, such as alkali sulfites, for example potassium and / or sodium sulfite, alkali hydrogen sulfites, for example potassium and / or sodium hydrogen sulfite, alkali metal sulfites, for example potassium and / or sodium metabisulfite, formaldehyde sulfoxylates, for example potassium and / or sodium formaldehyde, can be used as corresponding reducing agents. Alkali salts, especially potassium and / or Sodium salts aliphatic sulfinic acids and alkali metal hydrogen sulfides, such as, for example, potassium and / or sodium hydrogen sulfide, salts of polyvalent metals, such as iron (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 can be used. As a rule, the amount of the radical polymerization initiator used, based on the total amount of the monomer mixture, is 0.1 to 5% by weight.

The reaction temperature for the radical aqueous polymerization reaction in the presence or absence of the finely divided inorganic solid is the entire range from 0 to 170 ° C. Temperatures of 50 to 120 ° C, often 60 to 110 ° C and often> 70 to 100 ° C are generally used. The radical aqueous emulsion polymerization can be carried out at a pressure of less than, equal to or greater than 1 bar (absolute), the polymerization temperature exceeding 100 ° C. and up to 170 ° C. Volatile monomers such as ethylene, butadiene or vinyl chloride are preferably polymerized under elevated pressure. The pressure can be 1.2, 1.5, 2, 5, 10, 15 bar or even higher. If emulsion polymerizations are carried out under reduced pressure, pressures of 950 mbar, often 900 mbar and often 850 mbar (absolute) are set. The radical aqueous emulsion polymerization is advantageously carried out at 1 bar (absolute) under an inert gas atmosphere, such as, for example, under nitrogen or argon.

In principle, the aqueous reaction medium can also comprise water-soluble organic solvents, such as, for example, methanol, ethanol, isopropanol, butanols, pentanols, but also acetone, etc. However, the polymerization reaction is preferably carried out in the absence of such solvents.

In addition to the above-mentioned components, radical chain-transferring compounds can optionally also be used in the processes for producing the aqueous composite particle dispersion or the aqueous polymer dispersion, in order to reduce or control the molecular weight of the polymers accessible by the polymerization. Essentially aliphatic and / or araliphatic halogen compounds, such as, for example, n-butyl chloride, n-butyl bromide, n-butyl iodide, methylene chloride, ethylene dichloride, chloroform, bromoform, bromotrichloromethane, dibromodichloromethane, carbon tetrachloride, tetrabromide carbonate, primary compounds such as benzyl chloride, benzomide, benzyl chloride, come , secondary or tertiary aliphatic thiols, such as ethanethiol, n-propanethiol, 2-propanethiol, n-butanethiol, 2-butanethiol, 2-methyl-2-propanethiol, n-pentanethiol, 2-pentanethiol, 3-pentanethiol, 2-methyl -2-butanethiol, 3-methyl-2-butanethiol, n-hexanethiol, 2-hexanethiol, 3-hexanethiol, 2-methyl-2-pentanethiol, 3-methyl-2-pentanethiol, 4-methyl-2-pentanethiol, 2-methyl-3-pentanethiol, 3-methyl-3-pentanethiol, 2-ethylbutanethiol, 2-ethyl-2-butanethiol, n-heptanethiol and its isomeric compounds, n-octanethiol and its isomeric compounds, n-nonanthiol and its isomers Compounds, n-decanethiol and its isomeric compounds, n-undecanethiol and its isomeric compounds, n-dodecanethiol and its isomeric compounds, n-tridecanethiol and its isomeric compounds, substituted thiols, such as 2-hydroxyβthanethiol, aromatic thiols, such as benzene thiol, ortho -, meta-, or para-MethylbenzoIthiol, as well as all other in polymer Handbook 3 ^rd edtition, 1989, J. Brandrup and EH Immergut, John Weley & Sons, section II, pages 133 to 141, sulfur compounds described, as well as aliphatic and / or aromatic aldehydes, such as acetaldehyde, propionaldehyde and / or benzaldehyde, unsaturated fatty acids, such as oleic acid, dienes with non-conjugated double bonds, such as divinylmethane or vinylcyclohexane or hydrocarbon fe with easily abstractable hydrogen atoms, such as toluene. However, it is also possible to use mixtures of non-interfering radical chain-transferring compounds mentioned above. The optionally used total amount of the radical chain transferring compounds, based on the total amount of the monomers to be polymerized, is generally <5% by weight, often <3% by weight and often <1% by weight.

The aqueous composite particle dispersions used according to the invention and the aqueous dispersions composed of aqueous polymer dispersion and finely divided inorganic solid usually have a total solids content of 1 to 70% by weight, often 5 to 65% by weight and often 10 to 60% by weight.

The composite particles or dispersion polymers used according to the invention generally have particle diameters of> 0 and <1000 nm, frequently <500 nm and often <250 nm. The determination of these particle diameters is also carried out by the analytical ultracentrifuge method. The indicated values correspond to the so-called d ₅ o values.

The composite particles that can be used according to the invention can have different structures. The composite particles can contain one or more of the finely divided solid particles. The finely divided solid particles can be completely enveloped by the polymer matrix. However, it is also possible for part of the finely divided solid particles to be enveloped by the polymer matrix, while another part is arranged on the surface of the polymer matrix. Of course, it is also possible for a large part of the finely divided solid particles to be bound on the surface of the polymer matrix. It should also be noted that the aqueous composite particle dispersions can be dried in a simple manner to redispersible composite particle powders (for example freeze drying or spray drying). This applies in particular if the glass transition temperature of the polymer matrix of the composite particles accessible according to the invention is> 50 ° C, preferably> 60 ° C, particularly preferably> 70 ° C, very particularly preferably> 80 ° C and particularly preferably> 90 ° C or Is> 100 ° C. The composite particle powders are also suitable for the treatment of paper surfaces according to the invention.

The mixtures of aqueous polymer dispersion and finely divided inorganic solid are obtained, for example, by adding the corresponding amount of the finely divided inorganic solid to an aqueous polymer dispersion stirred at 20 to 25 ° C. (room temperature), either in the form of powder or likewise in the form of an aqueous solid dispersion stirred in and mixed homogeneously.

In the treatment of the paper surface according to the invention, the composite particles or the mixture of dispersion polymer and finely divided inorganic solid in an amount of 0.1 to 100 g / m ² , often 0.2 to 20 g / m ² and often 0.5 to 10 g / m ² paper applied to the paper surface. Larger quantities are also conceivable, but are generally not economically viable. If the composite particles or the mixture of dispersion polymer and finely divided inorganic solid are applied to the paper surface in the form of aqueous polymer dispersions, the abovementioned amounts are based on the amounts of composite particles or mixture of dispersion polymer and finely divided inorganic solid contained in the aqueous dispersions , Following the application of the aqueous dispersions, there is generally a drying step familiar to the person skilled in the art.

Composite particles or dispersion polymers whose polymers can be filmed and whose minimum film-forming temperature is <150 ° C., preferably <100 ° C. and particularly preferably <50 ° C., are used in particular for the process according to the invention. Since the minimum film formation temperature can no longer be measured below 0 ° C, the lower limit of the minimum film formation temperature can only be specified by the glass transition temperature. The glass transition temperatures should not fall below -60 ° C, preferably -30 ° C. The minimum film-forming temperature is determined in accordance with DIN 53 787 and ISO 2115 and the glass transition temperature is determined in accordance with DIN 53 765 (differential scanning calorimetry, 20 K / min, mid-point measurement).

It can be advantageous if the paper coated with composite particles, in particular if the coating takes place in the form of such aqueous dispersions is exposed to the coating process, such pressures and / or temperatures that the polymer contained in the composite particles (process 1) films. The same also applies if the paper surfaces are coated according to method 2 with an aqueous dispersion, a mixture of polymer and finely divided inorganic solid. It is irrelevant whether, for example when using aqueous dispersions, the drying conditions (temperature / pressure) are selected so that the polymer films, or whether the filming takes place in a subsequent separate step. If the corresponding aqueous dispersions are used, the filming step is often carried out during drying.

The coated papers accessible by the process according to the invention can be used in many ways, for example as writing paper, newsprint, paper for journals, catalogs, books, as banknote paper, thin printing paper, kraft paper, capacitor paper or photo paper.

The papers according to the invention can advantageously be labeled and printed, for example, by means of offset, flexographic and gravure printing processes. In particular, the printed papers according to the invention which are accessible by the offset printing process have advantages with regard to their resistance to dry, wet picking and impact as well as their good "mottle" properties.

Examples

I. Preparation of an aqueous composite particle dispersion

In a 2 l four-necked flask equipped with a reflux condenser, a thermometer, a mechanical stirrer and a metering device, 416.6 were at 20 to 25 ° C (room temperature) and 1 bar (absolute) under a nitrogen atmosphere and stirring (200 revolutions per minute) g Nyacol ^® 2040 and then a mixture of 2.5 g of methacrylic acid and 12 g of a 10 wt .-% aqueous solution of sodium hydroxide was added within 5 minutes. Thereafter, the stirred reaction mixture added over 15 minutes a mixture of 10.4 g of a 20 wt .-% aqueous solution of the nonionic surfactant Lutensol ^® AT 18 (Trademark of BASF AG, C ₁₆ C ₁₈ -Fettalkoholethoxilat with an average of 18 ethylene oxide units ) and 61.4 g of deionized water. Thereafter, 0.83 g of N-cetyl-N, N, N-trimethylammonium bromide (CTAB), dissolved in 200 g of deionized water, was metered into the reaction mixture over 60 minutes. The reaction mixture was then heated to a reaction temperature of 80.degree. At the same time, a monomer mixture consisting of 117.5 g of methyl methacrylate, 130 g of n-butyl acrylate and 0.5 g of methacryloxypropyltrimethoxysilane was introduced as feed 1, and an initiator solution consisting of 2.5 g of sodium peroxodisulfate, 11.5 g of a 10 wt .-% solution of sodium hydroxide and 100 g of deionized water.

The reaction mixture stirred at the reaction temperature was then added over 5 minutes via two separate feed lines 21, 1 g of feed 1 and 57.1 g of feed 2. The reaction mixture was then stirred for one hour at the reaction temperature. Then added to the reaction mixture 0.92 g of a 45 wt .-% aqueous solution of Dowfax ^® 2A1 to. The residues of feed 1 and feed 2 were then continuously metered into the reaction mixture at the same time within 2 hours. The reaction mixture was then stirred for a further hour at the reaction temperature and then cooled to room temperature.

The aqueous composite particle dispersion thus obtained had a solids hardness of 40.1% by weight, based on the total weight of the aqueous composite particle dispersion.

The solids content of the aqueous composite particle dispersion was adjusted to 10% by weight by dilution with deionized water at room temperature with stirring.

I. Application test

Wood-free raw paper (basis weight 70 g / m ² ) from Scheufeien, Germany, with 10 g / m ^{2 of} a coating color (calculated as a solid) consisting of:

70 parts by weight of Hydrocarb ^® 90 (calcium carbonate from Omya AG, Switzerland), 30 parts by weight of Amazon Plus ^® (kaolin from CADAM SA, Brazil), 0.15 parts by weight of Polysalz ^® S (45 % by weight aqueous solution of a polyacrylic acid

Sodium salt from BASF AG, Germany),

10 parts by weight of Styronal ^® PR 8736 (50% by weight aqueous styrene / butadiene

Dispersion from BASF AG, Germany),

0.3 parts by weight of Sterocoll FD ^® (25 wt .-% aqueous ethyl acrylate / acrylic acid / methacrylic acid dispersion from. BASF AG,

Germany) and

34 parts by weight of deionized water, coated with a DT Laboratory Coater from DT Paper Science Oy Ab, Finland) at 30 ° C and atmospheric pressure (Stiffblade, with a thickness of 0.3 mm). The paper web was dried by means of an IR drying unit and air drying (8 IR emitters, each with 650 watts, throughput speed 30 m / min).

Test strips measuring 35 cm × 20 cm were cut from the paper webs and coated uniformly with the dilute aqueous composite particle dispersion. The amount of the diluted aqueous composite particle dispersion was measured so that the amount of composite particles was 1.0 g / m ² paper surface. The test strips were then stored for 15 hours at 23 ° C. and a relative air humidity of 50% (DIN 50014-23 / 50-2). The test strips were then calendered at room temperature using the table laboratory calender K8 / 2 from the company Kleinewefers Anlagen GmbH, Germany. The line pressure between the rollers was 200 kN / cm paper width and the speed was 10 m / min. The process was carried out four times in total.

Comparative example

The comparative example was carried out according to the aforementioned example, with the exception that the surface was not refined with the aqueous composite particle dispersion.

Determination of dry pick resistance with the IGT test printing device (IGT dry)

The test strips were printed with increasing speed in a printing unit (IGT printability tester AC2 / AIC2) with a standard color (printing ink 3808 from Lorilleux-Lefranc). The maximum printing speed was 200 cm / s. The paint was applied at a line pressure of 350 N / cm.

The speed in cm / sec at which 10 tears from the paper coating slip (pick points) occurred after the start of printing is given as a measure of the dry pick resistance. The higher the printing speed at the tenth pick point, the better the result will be evaluated.

wet pick resistance

The test strips were produced and prepared as described for the dry pick resistance test. The printing unit (IGT printability tester AC2 / AIC2) was set up so that the test strips are moistened with water before the printing process.

Printing was carried out at a constant speed of 0.6 cm / s.

Tears from the paper are visible as unprinted areas. To determine the wet pick resistance, the color density in comparison to the full color shade is therefore determined in% using a color densitometer. The higher the specified color density, the better the wet pick resistance.

Pick resistance with multiple printing (offset test)

The printing of the test strips [see test of dry pick resistance] was carried out at a constant speed of 1 m / s and was carried out at a line pressure of 200 N / cm.

Printing was repeated after 30 seconds. The pick resistance is the number of passes until picking occurs. The higher the number of printing processes until the first plucking, the better the result will be evaluated.

Table 1: Compilation of the results

Claims

claims

1. A process for the treatment of paper surfaces, characterized in that the surface of the paper is coated with particles (composite particles) which are composed of polymer and finely divided inorganic solid, the weight-average particle size of the finely divided inorganic solid being <100 nm.

2. The method according to claim 1, characterized in that the composite particles are applied to the paper in the form of an aqueous composite particle dispersion.

3. The method according to claim 2, characterized in that the aqueous composite particle dispersion was prepared by a process in which at least one ethylenically unsaturated monomer was dispersed in an 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 according to the free radical aqueous emulsion polymerization method, wherein

a) a stable aqueous dispersion of the at least one inorganic solid is used, which is characterized in that, at an initial solid concentration of> 1% by weight, based on the aqueous dispersion of the at least one inorganic solid, it is still one hour after its preparation contains as 90% by weight of the originally dispersed solid in dispersed form and the dispersed solid particles thereof have a weight-average diameter <100 nm,

b) the dispersed solid particles of the at least one inorganic

Solid in an aqueous standard potassium chloride solution at a pH which corresponds to the pH of the aqueous dispersing medium before the start of the addition of the dispersing agents, show a non-zero electrophoretic mobility,

c) at least one anionic, cationic and nonionic dispersant is added to the aqueous solid particle dispersion before the addition of the at least one ethylenically unsaturated monomer is started, d) then from the total amount of the at least one monomer 0.01 to 30 wt .-% of the aqueous solid particle dispersion are added and polymerized up to a conversion of at least 90%

and

e) the remaining amount of the at least one monomer is then added continuously under polymerization conditions in accordance with consumption.

4. A process for the treatment of paper surfaces, characterized in that the surface of the paper is treated with an aqueous dispersion which can be obtained by mixing an aqueous polymer dispersion with at least one dispersed, finely divided inorganic solid which has a weight-average particle diameter <100 nm becomes.

5. The method according to any one of claims 1 to 4, characterized in that the amount of composite particles or the mixture of dispersion polymer and finely divided inorganic solid is 0.1 to 100 g / m ² paper.

6. The method according to any one of claims 1 to 5, characterized in that the polymer is filmable.

7. The method according to any one of claims 1 to 6, characterized in that a base paper is used as paper.

8. The method according to any one of claims 1 to 6, characterized in that a coated or sized paper is used as paper.

9. The method according to any one of claims 1 to 8, characterized in that the finely divided inorganic solid is selected from the group comprising silicon dioxide, aluminum oxide, hydroxy aluminum oxide, calcium carbonate, magnesium carbonate, calcium orthophosphate, magnesium orthophosphate, iron (II) oxide, iron ( III) oxide, iron (II / III) oxide, tin dioxide, cerium dioxide, yttrium (III) oxide, titanium dioxide, hydroxylapatite, zinc oxide and zinc sulfide.

10. The method according to any one of claims 1 to 9, characterized in that the treated paper is exposed to pressures and / or temperatures such that the polymer films.

11. Paper obtainable by a process according to one of claims 1 to 10.

12. Use of papers according to claim 11 in the offset, flexographic and gravure printing processes.

13. Printed papers obtainable by use according to claim 12.

14. Use of an aqueous dispersion of particles which are composed of polymer and finely divided inorganic solid, the weight-average particle size of the finely divided inorganic solid being <100 nm, for coating paper.

15. Use of an aqueous dispersion, which by mixing an aqueous polymer dispersion with at least one disperse, finely divided inorganic solid, which has a weight-average particle diameter

<100 nm, is available for coating paper.