NZ716868B2 - Method for producing emulsion polymerisates - Google Patents

Abstract

The invention relates to a method for producing emulsion polymer particles with a core-shell structure, wherein the weight ratio of the shells lies within special limits. The invention also relates to the use of said particles in paints, paper coatings, foams, and cosmetic agents.

Description

METHOD FOR PRODUCING EMULSION POLYMERISATES Description The present ion relates to a process for producing emulsion polymer particles having a core-shell structure, wherein the weight ratio of swell-seed (ii) to seed polymer (i) is in the range from 10:1 to 150:1, the weight ratio of the core stage r to first shell (iii) is in the range from 2:1 to 1:5, and the weight ratio of third shell (vii) to second shell (iv) is in the range from 1:2 to 1:10, and also to their use in paints, paper coatings, foams, crop protection agents, liquid inks and cosmetic itions.

Hollow organic particles are a special kind of core-shell particles which, in dried form, consist of an air-filled void surrounded by a hard sheath. Owing to this construction, they have the special ty of scattering light, explaining their use as white pigment in paints, paper coatings and ic compositions, for example ams. When used therein they replace part of the inorganic white pigment titanium e and also boost the effect of the ing TlOz.

C. J. McDonald and M. J. Devon, in Advances in Colloid and Interface Science 2002, 99, 181- 213, describe various ways of forming these hollow particles such as inter alia swelling with organic solvents or propellants, encapsulation of hydrocarbons or approaches based on W/O/W emulsions. However, the method which is preferred for ical as well as economic reasons is that of osmotically swelling specific core-shell particles.

EP 1 904 544 describes this process in fundamental terms, gh the weight ratios of the sheiis differ from the process of the present invention. rs obtained by the process of the present invention exhibit a ctly improved scattering efficiency. This is because, compared with the process disclosed in EP 1 904 544, more voidage is generated by the process of the present invention, based on the polymer solids. The magnitude of total voidage in the polymers due to the hell particles can be determined by means of an NMR method which is se described in the application, via the measured internal water content of the polymers.

Polymers obtained by the process of the present invention have an internal water content of % or more, based on the entire water content of the dispersion. This leads to a distinctly higher whiteness.

EP 1 904 544 already demonstrated the advantage of swelling without stopping the free—radical flux versus EP 0 915 108, in which the free—radical flux is stopped by waiting until the added free-radical initiator has fully reacted, cooling the reaction solution or adding rization inhibitors and/or reducing agents. The process described according to the present invention likewise ensures that at the time of swelling there is a free-radical flux as well as a monomer 40 tration which is sufficient for swelling.

US 8,013,081 se describes a process for producing hollow organic particles. However, the process described according to the present invention again differs in having fundamentally PF 75483 different weight ratios between the shells. Polymers ed by the process of the present invention exhibit a distinctly improved scattering efficiency. This is because, ed with the process disclosed in US 8,013,081, more voidage is generated by the s of the present invention. The magnitude of total voidage in the polymers due to the core-shell particles can be determined by means of an NMR method which is likewise bed in the ation, via the measured internal water t of the polymers.

EP 2 511 312 describes a process which eschews the use of polymerization inhibitor and of reducing agent and utilizes small amounts of free—radical initiators at the start of the first shell (similar to shell iii described in the process of the present invention) to enable swelling through cization with a monomer—solvent system sing from 5 to 50 wt% of a r of the shell monomer system of the second shell (similar to shell iv described in the process of the present invention). The polymers obtained by the process of the present invention accordingly differ fundamentally in that during the swelling, described by steps v) and vi), no second shell iv) r is used for plasticization, but a plasticizer r having a ceiling temperature below 181°C, ably below 95°C.

The m addressed by the t invention — that of developing a production process for emulsion polymer particles, in particular for hollow organic particles having an improved whiteness compared with the prior art — was solved according to the present invention as follows: A process for producing emulsion polymer particles by producing a multistaged on polymer by i) polymerizing in a sequential polymerization a seed, ii) then reacting with a swell—seed comprising 55 to 99.9 wt% of one or more than one nonionic ethylenically unsaturated monomer and 0.1 to 45 wt% of one or more than one ethylenically unsaturated hydrophilic monomer, all based on the overall weight of the core stage polymer comprising both seed and swell—seed, 3O iii) then polymerizing a first shell comprising 85 to 99.9 wt% of one or more than one nonionic ethylenically unsaturated monomer and 0.1 to 15 wt% of one or more than one hydrophilic ethylenically unsaturated monomer, iv) then polymerizing a second shell comprising 85 to 99.9 wt% of one or more than one nonionic ethylenically unsaturated monomer and 0.1 to 15 wt% of one or more than one hydrophilic ethylenically unsaturated monomer, v) then adding at least one plasticizer monomer having a ceiling temperature below 181°C, preferably below 95°C, vi) neutralizing, to a pH of not less than 7.5, the resultant particles with a base, vii) then polymerizing a third shell comprising 90 to 99.9 wt% of one or more than one 40 ic ethylenically unsaturated monomer and 0.1 to 1 0 wt% of one or more than one hydrophilic ethylenically unsaturated monomer, PF 75483 viii) and also ally polymerizing one or more further shells comprising one or more than one nonionic ethylenically unsaturated monomer and one or more than one hydrophilic ethylenically unsaturated monomer, wherein the weight ratio of said seed (ii) to said seed polymer (i) is in the range from 10:1 to 150:1, the weight ratio of the core stage r to said first shell (iii) is in the range from 2:1 to 1:5, and the weight ratio of said third shell (vii) to said second shell (iv) is in the range from 1:2 to 1:10.

The present invention further provides for the use of the emulsion polymers obtainable 1O according to the present invention in paints, paper coatings, foams, crop protection agents, liquid inks or cosmetic compositions, and also paints, paper, foams, crop protection agents, liquid inks or cosmetic compositions sing the emulsion polymers obtained ing to the present invention.

One advantage of the invention is that the described change in the weight ratios between swell- seed (ii) and seed polymer (i), between the core stage polymer and the first shell (iii) and also in particular between the third shell (vii) and the second shell (iv) has the effect in relation to the prior art of the total e of the rs being increased, which leads to a distinct improvement in whiteness, and thus overcomes this disadvantage of the prior art.

Polymers obtained by the process of the present invention have an internal water content of % to 40% or more, based on the entire water content of the dispersion. This leads to a distinctly higher whiteness.

The ion described is a multistaged sequential emulsion polymerization. Sequential relates to the implementation of the individual stages in that each individual stage may also be constructed of two or more sequential steps.

The term “seed” refers to an aqueous polymeric dispersion which is used at the start of the multistaged polymerization and is the t of an emulsion polymerization, or to an aqueous polymeric dispersion present at the end of one of the polymerization stages for producing the hollow particle dispersion, except the last stage.

The seed used at the start of polymerizing the first stage may also be formed in situ and preferably comprises as monomer tuents styrene, acrylic acid, methacrylic acid, esters of acrylic acid and methacrylic acid or mixtures thereof.

The average particle size of the seed polymer in the unswolien state is in the range from 20 to 100 nm.

PF 75483 The swell-seed comprises 55 to 99.9 wt%, preferably 60 to 80 wt%, of a nonionic ethylenically unsaturated r and 0.1 to 45 wt%, preferably 20 to 40 wt%, of an ethylenically unsaturated hydrophilic monomer.

The weight ratio of swell-seed (ii) to seed r (i) is in the range from 10:1 to 150:1.

The average particle size in the unswollen state of the core stage polymer consisting of seed (i) and swell—seed (ii) is in the range from 50 to 300 nm, preferably in the range from 50 to 200 nm.

The glass transition temperature ined by the Fox equation (John Wiley & Sons Ltd., 1O Baffins Lane, Chichester, England, 1997) of the core stage polymer in the protonated state is between —20°C and 150°C.

Nonionic ethylenically rated monomers are for example styrene, vinyltoluene, ethylene, butadiene, vinyl e, vinyl chloride, vinylidene chloride, acrylonitrile, acrylamide, rylamide, (Ci-Cgo)alkyl or (Cs-C20)alkenyl esters of c or methacrylic acid, methacrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2—ethylhexyl acrylate, 2-ethylhexyl methacrylate, benzyl acrylate, benzyl methacrylate, lauryl acrylate, lauryl methacrylate, oleyl acrylate, oleyl methacrylate, palmityl acrylate, palmityl methacrylate, i acrylate, stearyl methacrylate, hydroxyI—containing monomers, in particular C1-Cio hydroxyalkyl (meth)acrylates, such as hydroxyethyl (meth)acrylate, hydroxypropyl acrylate, glycidyl (meth)acrylate, ably methyl methacrylate.

Ethylenically unsaturated hydrophilic monomers are for example acrylic acid, methacrylic acid, acryioyloxypropionic acid, ryloyloxypropionic acid, acryloyioxyacetic acid, methacryloyloxyacetic acid, crotonic acid, aconitic acid, itaconic acid, monomethyl maleate, maleic acid, monomethyl itaccnate, maleic anhydride, fumaric acid, monomethyl fumarate, itaconic anhydride, and also linseed oil fatty acids, such as oleic acid, linoleic acid and linolenic acid and also further fatty acids, such as ricinoleic acid, oleic acid, c acid, vaccenic acid, icosenic acid, cetoleic acid, erucic acid, nervonic acid, arachidonic acid, timnodonic acid, clupanodonic acid, preferably acrylic acid and methacrylic acid.

The first shell (iii) comprises 85 to 99.9 wt% of one or more than one nonionic ethylenically unsaturated monomer, preferably 90 to 99.9 wt%, and also 0.1 to 15 wt%, preferably 0.1 to 10 wt% of one or more than one hydrophilic ethylenically unsaturated monomer.

Nonionic ethylenically unsaturated monomers are for example styrene, oluene, ethylene, butadiene, vinyl acetate, vinyl de, vinylidene chloride, acrylonitrile, acrylamide, methacrylamide, (C1'CZO)aIkyl or (Ca-Czo)alkenyl esters of acrylic or methacrylic acid, 40 methacrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl rylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, benzyl acrylate, benzyl methacrylate, lauryl acrylate, lauryl rylate, oleyl acrylate, oleyl methacrylate, palmityl PF 75483 acrylate, palmityl methacrylate, stearyl acrylate, l methacrylate, hydroxyl—containing monomers, in particular 01—010 hydroxyalkyl (meth)acrylates, such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, glycidyl (meth)acrylate, ably styrene, acrylonitrile, methacrylamide, methacrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2—ethylhexyl acrylate, 2-ethylhexyl methacrylate.

Ethylenically unsaturated hydrophilic monomers are for example acrylic acid, methacrylic acid, acryloyloxypropionic acid, ryloyloxypropionic acid, acryloyloxyacetic acid, 1O methacryloyloxyacetic acid, crotonic acid, aconitic acid, itaconic acid, monomethyl maleate, maleic acid, monomethyl itaconate, maleic anhydride, fumaric acid, thyl fumarate, and also linseed oil fatty acids, such as oleic acid, linoleic acid and linolenic acid and also r fatty acids, such as leic acid, palmitoleic acid, elaidic acid, vaccenic acid, ic acid, cetoleic acid, erucic acid, nervonic acid, arachidonic acid, timnodonic acid, clupanodonic acid, preferably acrylic acid, methacrylic acid, itaconic acid, itaconic anhydride, monomethyl itaconate.

The first shell (iii) encloses the core stage polymer. The weight ratio of the core stage polymer to the first shell (iii) is in the range from 2:1 to 1:5 preferably 2:1 to 1:3, and the shell polymer in the protonated state has a glass transition temperature determined by the Fox equation n -60°C to 120°C.

The particle size of this stage consisting of core stage polymer and first shell (iii) in the unswollen state is from 60 nm to 500 nm, preferably from 60 to 300 nm.

The second shell (iv) comprises 85 to 99.9, preferably 90 to 99.9 wt% of one or more than one nonionic ethylenically unsaturated monomer and 0.1 to 15 wt%, preferably 0.1 to 10 wt% of one or more than one hydrophilic ethylenically unsaturated monomer.

Nonionic ethylenically unsaturated monomers are for example styrene, p—methylstyrene, t-butylstyrene, vinyltoluene, ne, butadiene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile, acrylamide, methacrylamide, (Ci—C20)alkyl or (Cg~Czo)alkenyl esters of acrylic or methacrylic acid, methacrylate, methyl methacrylate, ethyl te, ethyl methacrylate, butyl acrylate, butyl methacrylate, lhexyl acrylate, 2—ethylhexyl methacrylate, benzyl acrylate, benzyl methacrylate, lauryl te, lauryl methacrylate, oleyl acrylate, oleyl methacrylate, palmityl acrylate, palmityl methacrylate, stearyl acrylate, l methacrylate, hydroxyI-containing monomers, in particular 01-qu hydroxyalkyl (meth)acrylates, such as hydroxyethyl (meth)acrylate, hydroxypropyl acrylate, yl (meth)acrylate, ably styrene, acrylonitrile, methacrylamide, methacrylate, methyl methacrylate, ethyl 40 acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, lhexyl acrylate, 2—ethyihexyl methacrylate, PF 75483 Ethylenically unsaturated hydrophilic monomers are for example acrylic acid, methacrylic acid, acryloyloxypropionic acid, methacryloyloxypropionic acid, acryloyloxyacetic acid, methacryloyloxyacetic acid, crotonic acid, aconitic acid, itaccnic acid, monomethyl maleate, maleic acid, monomethyl itaconate, maleic anhydride, fumaric acid, monomethyl te, and also linseed oil fatty acids, such as oleic acid, linoleic acid and linolenic acid and also further fatty acids, such as ricinoleic acid, palmitoleic acid, elaidic acid, vaccenic acid, icosenic acid, ic acid, erucic acid, nervonic acid, arachidonic acid, onic acid, odonic acid, preferably acrylic acid, methacrylic acid, itaccnic acid, itaccnic anhydride, monomethyl itaconate and linseed oil fatty acids.

The first shell is enveloped by the second shell and the weight ratio of the first shell (iii) to the second shell (iv) is in the range from 1:1 to 1:30, and the shell polymer in the protonated state has a Fox glass transition temperature of 50 to 120°C.

The average particle size of this stage, consisting of core stage polymer, first shell (iii) and second shell (iv), in the unswollen state is in the range from 70 to 1000 nm.

The cizer monomer recited under (v) is for example d~methylstyrene, esters of 2-phenyl- acrylic acid/atropic acid (e.g., methyl, ethyl, n—propyl, n-butyl), 2—methyl-2—butene, 2,3—dimethyl- 2-butene, 1,1~diphenylethene or methyl 2-tert—butylacrylate, and also further monomers recited in J. Brandrup, E.H. lmmergut, Polymer Handbook 3rd Edition, ll/316ff. ylstyrene is ably used as plasticizer monomer.

When the polymerization is d out in s solution or dilution, the monomers may be wholly or partly neutralized with bases before or during the polymerization. Useful bases include for example alkali metal or alkaline earth metal compounds such as sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium oxide, sodium carbonate; ammonia; primary, secondary and tertiary amines, such as ethylamine, propylamine, monoisopropylamine, monobutylamine, hexylamine, ethanolamine, dimethylamine, diethylamine, di—n-propylamine, tributylamine, triethanolamine, dimethoxyethylamine, 2-ethoxyethylamine, 3-ethoxypropylamine, dimethylethanolamine, diisopropanolamine, morpholine, ethylenediamine, 2-diethylamino— mine, 2,3-diamlnopropane, 1,2-propylenediamine, dimethylaminopropylamine, neopentanediamine, hexamethylenediamine, oxadodecane-1,12-diamine, polyethylene- lmine, polyvinylamine or mixtures thereof.

The ethylenically unsaturated hydrophilic monomers used in (i) — (v) are preferably not neutralized before or during the polymerization.

The neutralization recited under (vi) is effected with one or more of the ratively d 40 bases for swelling the core and hence leads to the formation of the hollow c le after drying.

PF 75483 it is preferable to use sodium hydroxide, ammonia, triethanolamine and diethanolamine for the lization recited under (vi).

The ethylenically unsaturated hydrophilic monomers used after (vi) are preferably neutralized during the polymerization.

The third shell (vii) comprises 90 to 99.9, preferably 95 to 99.9 wt% of one or more than one nonionic ethylenically unsaturated monomer and 0.1 to 10, preferably 0.1 to 5 wt% of one or more than one hydrophilic ethylenically unsaturated monomer.

The nonionic ethylenically unsaturated monomers are for example styrene, ethylvinylbenzene, vinyltoluene, ne, butadiene, vinyl acetate, vinyl chloride, dene chloride, acrylonitrile, acrylamide, methacrylamide, (C1~Czo)alkyl or o)alkenyl esters of acrylic or methacrylic acid, methacrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2—ethylhexyl acrylate, 2—ethylhexyl methacrylate, benzyl acrylate, benzyl methacrylate, lauryl acrylate, lauryl methacrylate, oleyl acrylate, oleyl methacrylate, palmityl acrylate, palmityl methacrylate, stearyl acrylate, stearyl rylate, hydroxyI-containing rs, in ular 01-010 hydroxyalkyl (meth)acrylates, such as yethyl (meth)acrylate, hydroxypropyl (meth)acrylate, glycidyl (meth)acrylate, preferably styrene, acrylonitrile, methacrylamide, methacrylate, methyl methacrylate, ethyl te, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate.

The nically unsaturated hydrophilic monomers are for example acrylic acid, methacrylic acid, acryloyloxypropionic acid, methacryloyloxypropionic acid, acryloyloxyacetic acid, methacryloyloxyacetic acid, crotonic acid, aconitic acid, ic acid, monomethyl maleate, ' maleic acid, monomethyl ate, maleic ide, fumaric acid, monomethyl fumarate, and also linseed oil fatty acids, such as oleic acid, linoleic acid and linolenic acid and also further fatty acids, such as ricinoleic acid, palmitoleic acid, elaidic acid, vaccenic acid, icosenic acid, cetoleic acid, erucic acid, nervonic acid, arachidonic acid, timnodonic acid, odonic acid, 3O preferably acrylic acid, methacrylic acid, itaconic acid, itaconic anhydride, monomethyl itaconate and linseed oil fatty acids.

The weight ratio of third to second shell is in the range from 1:2 to 1:10, and the shell polymer has a Fox glass transition temperature of 50 to 120°C.

When the polymers obtainable according to the present invention are used for painting, the average final particle size should be in the range from 100 to 600 nm, while it should be in the range from 200 to 2500 nm for use in paper and in cosmetics and in the range from 300 to 800 nm for foams.

In a paint, the pigments employed, specifically TiOz, can be wholly or partly ed by the polymeric dispersion described herein. Paints of this type typically comprise infer a/ia water, PF 75483 thickening agent, aqueous sodium hydroxide solution, t disperser, associative thickener, defoamer, biocide, binder and also film—forming assistant.

The hollow particle dispersion can also be used for similar applications in other coatings consisting of resinous sation products, such as phenoiates and aminoplasts based on urea—formaldehyde and ne-formaldehyde. Use is similarly possible in further coatings based on water—dispersible alkyds, polyurethanes, polyesters, ethyl-vinyl acetates and also styrene-butadiene.

Using the organic pigments obtainable by the process of the present ion in paper coatings leads to an increase in paper gloss. This is attributable to the sheath which, unlike with inorganic pigments, is deformable under pressure. Paper print quality is also enhanced.

Substituting the organic pigments described herein for inorganic pigments leads to a lower density for the coating and thus to paper of lighter .

In cosmetics, the organic pigments obtainable by the process of the present invention can be used for example in suncreams to boost the level of rotection. The extraordinary light- scattering properties serve to increase the probability of UV radiation being absorbed by UV- active substances in the suncream.

The organic pigments obtainable by the process of the present ion are further useful in foams, crop protection agents, thermoplastic g compounds and liquid inks.

The polymers are obtainable via customary methods of emulsion polymerization. It is preferable to operate in the absence of oxygen, more preferably in a stream of nitrogen. Customary apparatus is employed for the polymerization procedure, examples being stirred tanks, stirred— tank cascades, autoclaves, r reactors and kneaders. The polymerization can be carried out in solvent or diluent media, e.g., toluene, o-xylene, p—xylene, cumene, chlorobenzene, ethylbenzene, technical-grade mixtures of alkylaromatics, cyclohexane, technical—grade 3O aliphatics mixtures, acetone, cyclohexanone, tetrahydrofuran, dioxane, glycols and glycol derivatives, polyalkylene glycols and derivatives f, diethyl ether, tert-butyl methyl ether, methyl acetate, isopropanol, ethanol, water or es such as, for example, isopropanol—water mixtures.

The polymerization can be carried out at temperatures of 20 to 300, preferably of 50 to 200°C.

The polymerization is preferably carried out in the presence of compounds that form free ls. These compounds are needed in a tion of up to 30, preferably 0.05 to 15, more preferably 0.2 to 8 wt%, based on the monomers used in the polymerization. in the case of 40 omponent initiator systems (e.g., redox initiator s), the ing weight particulars are based on total components.

PF 75483 Useful polymerization initiators include, for example, peroxides, eroxides, peroxodisulfates, percarbonates, peroxyesters, hydrogen peroxide and azo compounds.

Examples of initiators, which can be water soluble or else water insoluble, are hydrogen peroxide, dibenzoyl peroxide, dicyclohexyl dicarbonate, dilauroyl peroxide, methyl ethyl ketone peroxide, di-tert-butyl de, acetylacetone de, tert-butyl eroxide, cumene hydroperoxide, tert-butyl perneodecanoate, tert—amyl perpivalate, tert—butyl perpivalate, tert-butyl perneohexanoate, tert-butyl per-Z-ethylhexanoate, tert-butyl zoate, lithium peroxodisulfate, sodium peroxodisulfate, potassium peroxodisulfate, um peroxodisulfate, azobisisobutyronitrile, 2,2’—azobis(2-amidinopropane) dihydrochloride, 2—(carbamoyiazo)isobutyronitrile and 4,4-azobis(4—cyanovaleric acid).

The initiators may be used alone or mixed with each or one another, for example mixtures of hydrogen peroxide and sodium peroxodisulfate. Polymerization in an aqueous medium ably utilizes water-soluble initiators.

The familiar redox initiator systems can also be used as polymerization tors. Redox initiator systems of this type comprise one or more than one peroxide-containing compound combined with a redox co—initiator, e.g., sulfur compounds having a ng effect, examples being bisulfites, sulfites, sulfinates, thiosulfates, dithionites and tetrathionates of alkali metals and ammonium compounds and their adducts such as sodium hydroxymethylsulfinates and acetone bisulfites and also ascorbic acid, isoascorbic acid and sodium erythrobate. Combinations of peroxodisulfates with alkali metal or ammonium hydrogensulfites can accordingly be used, an example being ammonium peroxodisulfate combined with ammonium disulfite. The ratio of peroxide-containing compound to redox co-initiator is in the range from 30:1 to 0.05:1.

Transition metal catalysts may additionally be used in combination with the initiators and/or the redox initiator systems, examples being salts of iron, , nickel, copper, um and manganese. Useful salts e, for example, iron(ll) sulfate, cobalt(ll) chloride, nickel(ll) sulfate, (l) chloride or else water—soluble iron-chelate xes such as K[Fe-lll-EDTA] or Na[Fe—lll-EDTA][DK1]. Based on monomers, the reducing transition metal salt is used in a concentration of 0.1 ppm to 1000 ppm. Combinations of hydrogen peroxide with iron(ll) salts can accordingly be used, an example being 0.5 to 30% of hydrogen peroxide being combined with 0.1 to 500 ppm of Mohr’s salt.

Similarly, polymerization in organic solvents may combine the abovementioned tors with redox co-initiators and/or transition metal catalysts, examples being benzoin, dimethylaniline, ascorbic acid and also organosoluble complexes of heavy metals, such as copper, cobalt, iron, manganese, nickel and chromium. The customarily used amounts of redox co—initiators and/or tion metal sts are here customarily about 0.1 to 1000 ppm, based on the amounts of 40 monomers used.

PF 75483 When the reaction mixture is ently polymerized at the lower limit of the temperature range for the polymerization and then fully polymerized at a higher temperature, it is advantageous to use two or more different initiators that decompose at different temperatures, so an adequate tration of free radicals is available within every temperature interval, or to use a redox initiator system wherein the peroxide-containing component is initially activated by a co-initiator at a low temperature and thermally decomposes at a higher temperature without a continued need for co—initiator.

The initiator can also be added in stages, and/or the rate of initiator addition varied over time.

To obtain polymers of low average lar weight, it is often advantageous to conduct the copolymerization in the presence of chain transfer agents. The chain transfer agents used for this may be customary chain transfer agents, for example organic SH—containing compounds, such as 2-mercaptoethanol, 2—mercaptopropanol, mercaptoacetic acid, utyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan and tert-dodecyl mercaptan, C1-C4 aldehydes, such as formaldehyde, dehyde, propionaldehyde, hydroxylammonium salts such as hydroxyl— um sulfate, formic acid, sodium bisulfite, hypophosphorous acid and/or salts thereof, or isopropanol. Chain transfer agents are lly used in amounts of 0.1 to 20 wt%, based on the monomers. The choice of a suitable solvent is another way to control the average molecular weight. Thus, rization in the presence of diluents having ic hydrogen atoms, or in the presence of secondary alcohols such as, for example, panol, leads to a reduction in the average lar weight through chain transfer.

Polymers of low or comparatively low molecular weight are also ed through: varying the temperature and/or the tor concentration and/or the monomer feed rate.

To obtain comparatively high molecular weight copoiymers, it is often advantageous to m the rization in the presence of crosslinkers. These crosslinkers are compounds having two or more ethylenically unsaturated groups, for example diacrylates or dimethacrylates of at least dihydric saturated alcohols, e.g., ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,2—propylene glycol diacrylate, 1,2—propylene glycol dimethacrylate, 1,4—butanediol diacrylate, 1,4—butanediol dimethacrylate, hexanediol diacrylate, hexanediol dimethacrylate, neopentylglycol diacrylate, neopentylglycol dimethacrylate, 3—methylpentanediol late and 3—methylpentanediol dimethacrylate. The acrylic and methacrylic esters of alcohols having more than 2 OH groups can also be used as crosslinkers, examples being trimethylolpropane triacrylate or trimethylolpropane trimethacrylate. A further class of crosslinkers ses diacrylates or dimethacrylates of hylene glycols or opylene glycols having molecular weights of 200 to 9000 in each case. Polyethylene and/or polypropylene glycols used for preparing the diacrylates or dimethacrylates preferably have a molecular weight of 400 to 2000 40 each. Not only the homopolymers of ethylene oxide and/or propylene oxide can be used, but also block copoiymers of ethylene oxide and propylene oxide, or random copoiymers of ethylene oxide and propylene oxide, which comprise a random distribution of the ethylene oxide PF 75483 and propylene oxide units. Similarly, the oligomers of ethylene oxide and/or propylene oxide are useful for preparing the crosslinkers, examples being diethylene glycol diacrylate, diethylene glycol dimethacrylate, ylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate and/or tetraethylene glycol dimethacrylate.

Useful crosslinkers r include vinyl acrylate, vinyl methacrylate, vinyl itaconate, divinyl adipate, butanediol divinyl ether, trimethylolpropane trivinyl ether, allyl acrylate, allyl methacrylate, methylallyl methacrylate, diallyl phthalate, triallyl isocyanurate, pentaerythritol triallyl ether, triallylsucrose, pentaallylsaccharose, pentaallylsucrose, methylenebis(meth)- acrylamide, divinylethylene urea, divinylpropylene urea, lbenzene, divinyldioxane, triallyl cyanurate, tetraallylsilane, tetravinylsilane and bis- or polyacryloylsiloxanes (e.g., Tegomers® from Evonik ries AG).

Crosslinkers are preferably used in amounts of 0.1 to 70 wt%, based on the monomers to be polymerized in any one stage. Crosslinkers may be added in every stage. it may further be advantageous to stabilize the monomer droplets and/or polymer particles with interface-active auxiliary materials. fiers or protective colloids are typically used for this purpose. Anionic, nonionic, cationic and amphoteric emulsifiers can be used. Anionic emulsifiers include, for e, alkylbenzenesulfonic acids, alkaline earth metal enzenesulfonates, sulfonated fatty acids, ated olefins, ated diphenyl ethers, sulfosuccinates, fatty alcohol sulfates, alkylphenol sulfates, alkyl polyglycol ether sulfates, fatty alcohol ether sulfates, fatty alcohol ates, alkylphenol phosphates, alkyl polyglycol ether phosphates, alkyl polyalkylene oxide phosphates, and fatty alcohol ether phosphates. Useful nonionic fiers include, for example, alkylphenol ethoxylates, polysiioxane poiyalkyiene oxide copolymers, primary alcohol ethoxylates, fatty acid ethoxylates, alkanolamide ethoxylates, fatty amine ethoxylates, EO-PO block copolymers and alkylpolyglucosides. Useful cationic and/or amphoteric emulsifiers include for example: quaternized aminoalkoxylates, alkylbetaines, alkylamidobetaines and sulfobetaines.

Typical protective colloids include, for example, cellulose derivatives, polyethylene glycol, polypropylene glycol, copolymers of ethylene glycol and propylene glycol, polyvinyl e, polyvinyl alcohol, polyvinyl ether, starch and starch tives, dextran, nylpyrrolidone, polyvinylpyridine, polyethyleneimine, polyvinylimidazole, polyvinylsuccinimide, polyvinyl methylsuccinimide, polyvinyl—1,3-oxazolid-2—one, polyvinyl-Z—methylimidazoline and maleic acid and/or maleic anhydride copolymers as described for example in DE 2 501 123.

Preference is given to using alkaline earth metal alkylbenzenesulfonates, alkyl polyglycol ether sulfates and loxane-polyalkylene oxide copolymers.

Based on the weight of the core stage r, fiers or protective colloids are customarily used in concentrations of 0.05 to 20 wt%, preferably in concentrations of 0.1 to 5 wt%, In the PF 75483 r shells, emulsifiers or protective colloids are customarily used in concentrations of 0.05 to wt%, preferably in concentrations of 0.1 to 5 wt%, based on the monomers to be rized in this stage.

The polymerization may be carried out in a batch or continuous manner in any one of a multiplicity of versions. Customarily, some of the monomer is initially charged, optionally in a suitable diluent or solvent and optionally in the presence of an emulsifier, of a protective colloid or of further auxiliary materials, inertized and heated to the desired polymerization temperature.

However, the initial charge may also merely comprise a suitable diluent. The free-radical initiator, further monomer and other auxiliary materials, e.g., chain transfer agents or inkers are each optionally added in a diluent within a d period of time. Feed times may be chosen to differ in length. For instance, a longer feed time may be chosen for the initiator feed than for the monomer feed.

When the polymer is produced in a steam—volatile solvent or solvent e, the solvent may be removed by introduction of steam in order that an aqueous solution or dispersion may be obtained in this way. The polymer may also be separated from the organic diluent via a drying operation.

The process of the present invention delivers a distinctly higher scattering efficiency in paints and hence a distinct improvement in whiteness and also particles having a distinctly larger voidage (internal . The whiteness of the core-shell particles ed according to the process of the present invention is .2 78. The proportion of internal water is in a range between % and 40%.

The present ion further es for the use of the polymer dispersions obtainable according to the present invention in , paper coatings, foams, crop protection agents, liquid inks, thermoplastic molding compounds and cosmetic compositions, preferably in paints.

The present invention r provides a paint in the form of an aqueous composition comprising - at least one on polymer particle ing to the present invention, as defined above, - at least one filming polymer, - ally (in)organic filler and/or optionally further (in)organic pigments, - optionally at least one customary auxiliary, and - water.

Optionally useful filming polymers include aqueous emulsion polymers based on purely te polymers and/or styrene-acrylate polymers, and also any further filming polymers for coatings 40 ting of resinous condensation products comprising phenolates and aminoplasts and also comprising urea—formaldehyde and melamine-formaldehyde. It is similarly possible to use PF 75483 further polymers based on dispersible alkyds, ethanes, ters, ethyl-vinyl acetates and also styrene~butadiene.

The emulsion polymer particles of the present invention are preferably employed in aqueous paints. Suitable fillers in ciearcoat systems include, for example, matting agents to thus substantially reduce gloss in a desired manner. Matting agents are generally transparent and may be not only c but also inorganic. inorganic fillers based on silica are most suitable and are widely available commercially. Examples are the ® brands of W.R. Grace & Company and the Acematt® brands of Evonik industries AG. Organic g agents are for example available from BYK—Chemie GmbH under the Cerafiour® and the Ceramat® brands, from Deuteron GmbH under the Deuteron MK® brand. Suitable fillers for emulsion paints further include aluminosiiicates, such as feidspars, silicates, such as kaolin, talc, mica, magnesite, alkaline earth metal carbonates, such as calcium ate, for example in the form of calcite or chalk, magnesium carbonate, te, alkaline earth metal sulfates, such as calcium sulfate, silicon e, etc. The ence in the paints is naturally for finely divided fillers. The fillers can be used as individual components. in practice, however, filler mixtures have been found to be particularly advantageous, examples being calcium carbonate/kaolin and calcium carbonate/talc. Gloss paints generally include only minimal amounts of very finely divided fillers or contain no fillers at all.

Finely divided fillers can also be used to enhance the hiding power and/or to economize on white-pigments. Blends of fillers and color pigments are preferably used to control the hiding power of the hue and of the depth of shade.

Suitable pigments include, for e, inorganic white pigments such as um dioxide, preferably in the rutiie form, barium sulfate, zinc oxide, zinc sulfide, basic lead ate, antimony trioxide, lithopone (zinc sulfide + barium sulfate) or colored pigments, for example iron oxides, carbon black, graphite, zinc yellow, zinc green, ultramarine, manganese black, antimony black, manganese violet, an blue or Parisian green. In addition to inorganic pigments, the emulsion paints of the present invention may also comprise organic color pigments, for example sepia, gamboge, Cassel brown, toluidine red, parared, Hansa yellow, indigo, azo dyes, quinonoid and indigoid dyes and also dioxazine, quinacridone, phthaiocyanine, isoindoiinone and complex pigments. Also useful are the Luconyi® brands from BASF SE, e.g., l® yellow, Luconyi® brown and Luconyi® red, especially the transparent versions.

The coating composition (aqueous paint) of the present invention, in addition to the polymer dispersion, may ally comprise additional filming polymers, pigment and further auxiliaries. 40 Customary auxiliaries include wetting or dispersing agents, such as sodium polyphosphate, potassium polyphosphate, ammonium poiyphosphate, alkali metal and um salts of acrylic acid copolymers or of maleic anhydride copolymers, polyphosphonates, such as sodium PF 75483 1-hydroxyethane-1,1-diphosphonate and also naphthalenesulfonic acid salts, in particular their sodium salts. , More ance attaches to the film-forming assistants, the thickeners and defoamers. Suitable film-forming assistants include, for example, Texanol® from n Chemicals and the glycol ethers and esters as are commercially ble for example from BASF SE, under the names Solvenon® and Lusolvan®, and from Dow Chemicals under the tradename Dowano|®. The amount is preferably < 10 wt% and more preferably < 5 wt%, based on overall formulation. it is also le to formulate entirely without ts.

Suitable auxiliaries further include flow control agents, defoamers, biocides and thickeners.

Useful thickeners include, for example, associative thickeners, such as polyurethane thickeners.

The amount of thickener is preferably less than 2.5 wt%, more preferably less than 1.5 wt% of thickener, based on paint solids content. Further directions regarding the ation of wood paints are described at length in “water-based acrylates for tive coatings” by the authors M. Schwartz and R. Baumstark, lSBN 3—878706.

The paints of the present invention are obtained in known manner by blending the components in customary mixers. A tried and tested procedure is to first prepare an s paste or sion from the pigments, water and optionally the auxiliaries and only then to mix the polymeric , i.e., generally the aqueous dispersion of the polymer, with the pigment paste or, respectively, dispersion.

The paint of the present invention can be applied to substrates in a conventional manner, e.g., by brushing, spraying, g, rolling or knifecoating.

The paints of the present invention are notable for ease of handling and good processing teristics, and also for a high level of whiteness. The paints have a low noxiant content.

They have good performance characteristics, for example good fastness to water, good adherence in the wet state, and good block resistance, good recoatability, and they exhibit good flow on application. The equipment used is easily cleaned with water.

The examples which follow are offered by way of elucidation, not limitation of the present invention.

Experimental methods Determination of glass transition temperature Glass transition temperatures were determined by theoretical computation as per the Fox equation (John Wiley & Sons Ltd., Baffins Lane, Chichester, England, 1997), where the value 40 for the protonated state of the acid is assumed for the glass transition temperature of monomers having a ylic acid function.

PF 75483 1fl'g = Wa/Tga + Wb/Tgb, where Tgal and Tgb = glass transition temperature of polymers "a" and "b" Wa and Wb = weight fraction of polymers "a" and "b" Measurement of particle size Particle sizes were ined by hydrodynamic fractionation using a Polymer Labs particle size distribution analyzer . The Cartridge PL0850-1020 column used was operated with a flow rate of 2 'l. The samples were diluted with eluent solution down to an tion of 0.03 AU-ul'l.

The sample is eluted by the size ion principle according to the hydrodynamic er.

The eluent comprises 0.2 wt% of dodecylpoly(ethylene glycol ether)23, 0.05 wt% of sodium dodecylsulfonate, 0.02 wt% of sodium dihydrogen phosphate and 0.02 wt% of sodium azide in zed water. The pH is 5.8. The elution time is calibrated with polystyrene calibration lattices. The measurement range extends from 20 nm to 1200 nm. Detection is by UV detector at wavelength 254 nm.

Particle size can further be determined using a Coulter M4+ Particle Analyzer or by photon correlation spectroscopy also known as quasi elastic light scattering or dynamic light ring (DlN ISO 2004-10) using a Malvern high performance particle sizer (HPPS).

Procedure for whiteness measurement A 6 9 quantity of the hereinbelow described color paste and 0.312 g based on solids of the hollow particle dispersion are weighed out into a vessel, the mixture is homogenized without stirring air thereinto. A 200 um knife coater is used to draw down a film of this mixture on a black polymeric foil (matte , article No. 13.41 EG 870934001, Bernd Schwegmann GmbH & Co. KG, D) at a speed of 0.9 cm/sec. The samples are dried at 23°C and a relative humidity of 40—50% for 24 h. Subsequently, a Minolta CM—508i spectrophotometer is used to measure 3O the whiteness (L value from L a b color space to l\l@ 11664-42012—06) at three different places. The places where the measurements were d out are marked in order that a micrometer ‘screw may subsequently be used to determine the corresponding thicknesses of the colored-film layer by differential measurement relative to the uncoated polymeric foil. After computing an average film thickness and also an average whiteness from the three individual measurements, the whiteness level obtained is y standardized to a dry film thickness of 50 pm by linear extrapolation. The calibration needed for this was done by measuring the whiteness of a standard hollow particle dispersion in a dry film thickness range of about -60 pm.

PF 75483 Preparation of color paste A vessel is initially charged with 185 g of water and subsequently with the following ingredients, added in the stated order under a dissolver at about 1000 rpm and stirred homogeneous for altogether about 15 minutes: 2 g of 20 wt% aqueous sodium hydroxide solution, 12 g of Pigmentverteiler® MD 20 pigment disperser (copolymer of maleic acid and diisobutylene from BASF SE), 6 g of ® E 255 (siloxane er from Miinzing Chemie GmbH), 725 g of Acronal® A 684 (binder, 50 wt% dispersion from BASF SE), 40 g of Texanol® (film—forming assistant from Eastman Chemical Company), 4 g of Agitan® E 255 (siloxane defoamer from 1O MUnzing Chemie GmbH), 25 g of DSX 3000 (30 wt%, associative thickener: hydrophobic modified polyether (HMPE)) and 2 g of DSX 3801 (45 wt%, associative thickener: hydrophobic modified ethoxylated urethane (HEUR)).

Determination of internal water content The relative internal water content, i.e., the fraction of the water population in the interior of the core shell particles based on the overall water content of the sample, can be bed via a pulsed-field-gradient r—magnetic nce (PFG-NMR) 1H NMR experiment. in a system where the internal and external water populations are subject to diffusive exchange, exact determination is possible by varying the diffusion times according to Kérger (Annalen der Physik, series 7, volume 27, issue 1, 1971, pp. 107-109). A linear approximation to this exchange model is le in the region for which the effective diffusion time A of the PFG-NMR signal attenuation is very much smaller than the exchange time between the reservoirs. In the system bed, this is for example the case with A varying n 7 and 10 ms, for which the actual internal water t can be determined from the extrapolation to 0 ms. One uisite is that sufficiently strong gradient fields are available. In the case of exchange times being similar, a comparison of the internal water content can also be approximated via a comparison of measurements at a single, short diffusion time. In the present case, the comparisons between similar polymers were carried h a diffusion time of A = 7 ms by varying the gradient field strengths g up to 800 G/cm for an effective gradient pulse duration 5 = 1 ms by using a ated gradient echo pulse sequence (Steijskal & Tanner, J.

Chem. Phys., 1965, Vol. 42, pp. 288ff) on a commercially available high field NMR system r Biospin, Rheinstetten/Germany). The water signal was integrated from 5.8 to 3.7 ppm relative to the water signal maximum referenced internally to 4.7 ppm. The relative signal contributions by internal and external water were derived from the tors of a bi—exponential fit to the gradient-dependent PFG—NMR signal drop-off, with the sum total of the two prefactors being standardized. The fitted effective diffusion coefficients in our example were on the order of 2 x 10-9 m2/s for external water and 5 x 10-12 m2/s for al water. The error associated with the determination of the internal water content was about 1% based on 100% overall water 40 content.

PF 75483 Examples Production of core-shell particles: Organic raw materials not in the form of an aqueous solution were all purified by distillation prior to the synthesis.

Example 1: Seed dispersion A1: A pre-emulsion was prepared from 123.85 g of water, 0.88 g of Disponi|® LDBS 20 m dodecylbenzene sulfonate (20% strength», 182 g of n~butyl te, 163.45 9 of methyl rylate and 4.55 g of methacrylic acid. The initial charge, consisting of 1172.5 g of water, 70 g of Disponil® LDBS 20 and also 22.19 g of the pre-emulsion, in a polymerization vessel equipped with an anchor stirrer, a reflux condenser and two feed vessels was heated in a nitrogen atmosphere to a temperature of 80°C and ently polymerized for 15 min by addition of 67.2 g of a 2.5 wt% sodium peroxodisuifate solution. fter, the rest of pre- emulsion was metered in at 80°C over 60 min. This was followed by r polymerization for min and cooling down to 55°C over 20 min. To deplete the residual monomers, 3.5 g of a wt% aqueous felt-butyl hydroperoxide solution and also 2.19 g of a 10 wt% aqueous it® C (sodium hydroxymethylsulfonate) solution were then added to the reaction mixture, which was d for one hour and then cooled down to 30°C, at which point 4.38 g of 25 wt% aqueous ammonia solution were added to adjust the pH of the dispersion.

Solids content: 19.8% Particle size (PSDA, volume median): 34 nm Dispersion B1 (swell-core) The initial charge, consisting of 1958.8 9 of water and 14.54 g of seed dispersion A1, in a polymerization vessel equipped with an anchor stirrer, reflux condenser and two feed vessels was heated in a nitrogen here to a temperature of 82°C. Two s after addition of 26.68 g of a 7 wt% sodium peroxodisuifate solution, a mixture of 0.62 g of allyl methacrylate and 217.34 g of methyl methacrylate and a solution of 9.34 g of Lutensit® A—EP A (alkyl polyalkylene oxide phosphates (20% strength», 9.34 g of Disponil® LDBS 20 and 166 g of methacrylic acid in 562 g of water were added concurrently over 90 min. Ten minutes after completion of the addition, 92.55 g of a 1.5 wt% sodium peroxodisuifate solution, a mixture of 62 g of n-butyl methacrylate and 345.86 9 of methyl methacrylate and also a solution of 2.49 g of Disponil® LDBS 20 and 8.38 g of methacrylic acid in 276.89 g of water were added concurrently over 75 min. Finally, the feed vessel was rinsed with 33 g of water and rization was continued for a r 30 min.

Solids content: 21.8% 40 pH: 3.5 Particle size (PSDA, volume median): 186 nm PF 75483 sion C1 The initial charge, consisting of 261 g of water and 273.21 g of dispersion B1, in a rization vessel equipped with an anchor stirrer, a reflux condenser and two feed vessels was heated in a nitrogen atmosphere to a temperature of 81°C. Addition of 25.2 g of a 1.4 wt% sodium peroxodisulfate solution was followed by the metered addition over 120 min of preemulsion 1, consisting of 132 g of water, 13.6 g of Disponil® LDBS 20, 4.08 g of methacrylic acid, 17.2 g of methyl methacrylate, 10.88 g of acrylonitrile, 3.4 g of allyl methacrylate and 202.84 g of styrene, er with 24.32 g of a 2.5 wt% sodium peroxodisulfate solution. On completion of the additions, 3.36 g of a 2.5 wt% sodium disulfate on were added and the internal temperature was raised to 92°C over 40 min. Then, 23.76 g of a-methylstyrene were added over 10 min and the feed rinsed with 40.5 g of water. After a r 20 min of stirring 32 g of a 10 wt% ammonia solution were metered in over 5 min and stirred in for 5 min.

This was followed by the metered addition within 15 min of pre—emulsion 2, consisting of 98.44 g of water, 7 g of Disponil® LDBS 20, 0.28 g of methacrylic acid and 78 g of lbenzene (65% strength in ethylvinylbenzene). Completion of the addition was followed five minutes later by the on of 5.64 g of a 10 wt% aqueous solution of utyl hydroperoxide and the metering over 20 min of 31 g of a 3 wt% aqueous Rongalit C solution. 30 minutes after completion of the addition a further 9.16 g of a 10 wt% aqueous solution of z‘enibutyl hydroperoxide and 8.52 g of a 5.1 wt% aqueous Rongalit C® solution were added concurrently by metered on over 60 min.

Solids content: 29.7% pH: 9.5 Particle size (PSDA, volume median): 389 nm Whiteness: 79 internal water: 24% Example 2: Dispersion B2 (swell—core) The initial charge, consisting of 526 g of water, in a polymerization vessel equipped with an 3O anchor stirrer, a reflux condenser and two feed vessels was heated in a nitrogen atmosphere to a temperature of 82°C. After admixing a on of 76 g of water, 1.41 g of Disponil® FES 993 (alkyl polyglycol ether sulfates (30% strength» and 10.96 of EFKA® 3031 (polysiloxane polyalkylene oxide copolymers) and waiting for the temperature of the solution to return to 82°C, pre-emulsion 1 (consisting of 15.62 g of water, 0.28 g of Disponil® FES 993, 28.66 g of methyl methacrylate and 0.34 g of methacrylic acid) and 11.43 g of a 10 wt% sodium peroxodisulfate solution were admixed in succession before rizing for 30 min during which the temperature within the polymerization vessel was adjusted to 85°C. fter, pre-emulsion 2 (consisting of 236 g of water, 18.63 g of Disponil® FES 993, 250 g of methyl methacrylate and 144.31 g of methacrylic acid) was metered in at 85°C over 120 min. Finally, the feed vessel was 40 rinsed with 10 g of water and polymerization was continued for a further 15 min.

Solids content: 33.2% pH: 3.6 PF 75483 Particle size (PSDA, volume median): 130 nm Dispersion C2 The initial charge, consisting of 429 g of water and 80.13 g of dispersion 82 in a polymerization vessel equipped with an anchor stirrer, a reflux condenser and two feed vessels was heated in a nitrogen atmosphere to a temperature of 78°C and, following admixture of 18 g of a 2.5 wt% sodium peroxodisulfate solution, incipiently polymerized for 5 min. Then pre—emulsion 1 (consisting of 30 g of water, 3 g of Disponil® LDBS 20, 2.7 g of methacrylic acid, 23.8 g of methyl methacrylate and 34 g of styrene) was added over 60 min together with 36 g of a 1O 2.5 wt% sodium peroxodisulfate solution, starting at 78°C; the internal ature was raised to 80°C during the addition. On completion of the additions, pre-emulsion 2 (consisting of 118 g of water, 7 g of Disponil® LDBS 20, 2 g of linseed oil fatty acids, 0.9 g of allyl methacrylate and 296.1 g of styrene) was added over 75 min together with 9 g of a 2.5 wt% sodium peroxodisulfate solution, starting at 80°C; during the feed the al ature was raised to 82°C. On completion of the feeds the internal temperature was raised to 93°C and the system was stirred for 15 min before 18 g of d-methylstyrene were added. After a r 40 min of stirring, the temperature was lowered to 87°C. On attaining the temperature, the system was stirred for 15 min before 228 g of a 1.7 wt% ammonia solution were added over 30 min. After a renewed 15 min of stirring, pre-emulsion 3 sting of 51 g of water, 1.2 g of il LDBS 20, 0.2 g of methacrylic acid and 41.8 g of divinylbenzene) was added over 30 min. Five s after completion of the addition 6 g of a 10 wt% s solution of tert—butyl hydroperoxide were admixed together with 25 g of water, while 31 g of a 3.3 wt% aqueous Rongalit C® solution were added over 60 min.

Solids content: 28.9% pH: 10.2 Particle size (PSDA, volume median): 387 nm Whiteness: 80 internal water: 25% ative example: Dispersion BV1 (swell-core) The initial charge, consisting of 986 g of water and 28.2 g of Acrona|® A508, in a polymerization vessel equipped with an anchor r, a reflux condenser and two teed vessels was heated in a nitrogen atmosphere to a temperature of 82°C and, following admixture of 20.9 g of a 2.5% sodium peroxodisulfate solution, incipiently polymerized for 5 min. Then pre-emulsion 1 (consisting of 161 g of water, 2.20 g of Disponil® LDBS 20, 13.70 g of Lutensit® A~EP A, 0.07 g of fed-dodecyl tan, 136.3 g of methyl methacrylate, 0.66 g of allyl methacrylate and 68.3 g of methacrylic acid) was added over 70 min at 82°C. On completion of the addition 2.9 g of a 2.5% sodium peroxodisulfate solution were added and the system was stirred for 5 min. 40 fter pre-emulsion 2 (consisting of 167 g of water, 1.76 g of Disponil® LDBS 20, 110 g of methyl methacrylate, 13.5 g of n-butyl acrylate and 1.35 g of methacrylic acid) was added over PF 75483 70 min at 82°C together with 12 g of a'2.5% sodium peroxodisulfate solution. The system was finally postpolymerized for a further 30 min.

Solids content: 19.7% pH: 4.3 Particle size (PSDA, volume median): 213 nm Dispersion CV1 The initial charge, consisting of 458 g of water and 154.5 g of dispersion BV1, in a rization vessel equipped with an anchor stirrer, reflux condenser and two feed vessels 1O was heated in a nitrogen atmosphere to a temperature of 82°C and, ing admixture of 12.8 g of a 2.5% sodium peroxodisulfate solution, incipiently polymerized for 5 min. Then pre- emulsion 1 (consisting of 159 g of water, 6.7 g of Disponil® LDBS 20, 9.8 g of methacrylic acid and 156 g of e) was added over 90 min at 82°C together with 16.8 g of a 2.5% sodium peroxodisulfate solution. On completion of the two ons the internal temperature was raised to 92°C over 30 min and then pre-emulsion 2 (consisting of 14 g of water, 0.5 g of arylsulfonate (15% strength) and 13.6 g of o-methylstyrene) was added and stirred for 5 min before the admixture of 26 g of 10% strength ammonia—water; the reaction mixture was stirred at 92°C for a further 15 min. Thereafter 3.6 g of a 2.5% sodium peroxodisulfate solution were added over 3 min. ulsion 3 (consisting of 157 g of water, 5.9 g of Disponil® LDBS 20, 0.2 g of methacrylic acid, 20 g of lbenzene and 198 g of styrene) was added over 100 min at 92°C together with 23.7 g of a 2.5% sodium peroxodisulfate solution. The system was finally postpolymerized for a further 30 min. To reduce residual monomers, a chemical deodorization was onally carried out as a final step. To this end, 12.0 g of a 10% strength tert-butyl eroxide solution and also 12.0 g of a 10% strength ascorbic acid solution were added concurrently to the reaction mixture over 60 min at 92°C.

Solids t: 29.3% pH: 8.6 Particle size (PSDA, volume median): 480 nm Whiteness: 76 3O Internal water: 14% Example 3 Seed sion A2: A pre-emulsion was prepared from 123.85 g of water, 0.35 g of Disponil® FES 993, 182 g of n- butyl acrylate, 163.45 g of methyl methacrylate and 4.55 g of methacrylic acid. The initial charge, consisting of 1190.9 g of water, 24.97 g of Disponil® FES 993 and also 22.19 g of the pre—emulsion, in a polymerization vessel equipped with an anchor stirrer, a reflux condenser and two feed vessels was heated in a nitrogen atmosphere to a temperature of 80°C and ently polymerized for 15 min by addition of 67.2 g of a 2.5 wt% sodium peroxodisulfate 40 solution. Thereafter, the rest of the pre-emulsion was metered in at 80°C over 60 min. This was followed by further polymerization for 15 min and g down to 55°C over 20 min. To deplete the residual monomers, 3.5 g of a 10 wt% aqueous z‘erI-butyl hydroperoxide solution and also PF 75483 2.19 g of a 10 wt% s Rongalit C® solution were then added to the reaction mixture, which was stirred for one hour and then cooled down to 30°C, at which point 4.38 g of 25 wt% aqueous ammonia solution were added to adjust the pH of the dispersion.

Solids content: 19.9% Particle size (PSDA, volume median): 50 nm Dispersion BS (swell-core) The initial charge, consisting of 1822.6 g of water and 169 g of seed dispersion A2, in a polymerization vessel ed with an anchor stirrer, reflux condenser and two feed vessels was heated in a nitrogen atmosphere to a temperature of 82°C. Two s after on of 26.68 g of a 7 wt% sodium peroxodisulfate solution, a mixture of 0.62 g of allyl methacrylate and 217.34 g of methyl methacrylate and a solution of 9.34 g of Lutensit® A-EP A, 9.34 g of Disponil® LDBS 20 and 166 g of methacrylic acid in 562 g of water were added concurrently over 90 min. Ten minutes after completion of the on, 92.55 g of a 1.5 wt% sodium disulfate solution, a mixture of 62 g of n—butyl methacrylate and 345.86 g of methyl methacrylate and also a solution of 2.49 g of Disponil® LDBS 20 and 8.38 g of rylic acid in 276.89 g of water were added concurrently over 75 min. Finally, the feed vessel was rinsed with 33 g of water and polymerization was continued for a further 30 min.

Solids content: 21.9% pH: 3.5 Particle size (PSDA, volume ): 190 nm Dispersion C2 The initial charge, ting of 261 g of water and 27321 g of dispersion B3, in a polymerization vessel equipped with an anchor stirrer, a reflux condenser and two feed vessels was heated in a nitrogen atmosphere to a temperature of 81°C. Addition of 25.2 g of a 1.4 wt% sodium peroxodisulfate solution was followed by the metered addition over 120 min of pre— emulsion 1, consisting of 132 g of water, 13.6 g of Disponil® LDBS 20, 4.08 g of methacrylic acid, 17.2 g of methyl methacrylate, 10.88 g of acrylonitrile, 3.4 g of allyl methacrylate and 202.84 9 of e, together with 24.32 g of a 2.5 wt% sodium peroxodisulfate solution. On completion of the additions, 3.36 g of a 2.5 wt% sodium peroxodisulfate solution were added and the internal temperature was raised to 92°C over 40 min. Then, 23.76 g of q-methylstyrene were added over 10 min and the feed rinsed with 40.5 g of water. After a further 20 min of stirring 32 g of a 10 wt% ammonia solution were metered in over 5 min and stirred in for 5 min.

This was followed by the metered addition within 15 min of pre-emulsion 2, ting of 98.44 g of water, 7 g of Disponil® LDBS 20, 0.28 g of methacrylic acid and 78 g of divinylbenzene.

Completion of the addition was followed five minutes later by the addition of 5.64 g of a 10 wt% aqueous solution of utyl hydroperoxide and the metering over 20 min of 31 g of a 3 wt% aqueous Rongalit C® solution. 30 minutes after completion of the addition a further 9.16 g of a 40 10 wt% aqueous on of tert—butyl hydroperoxide and 8.52 g of a 5.1 wt% aqueous Rongalit C® solution were added concurrently by metered addition over 60 min.

Solids content: 29.7% PF 75483 pH: 9.5 Particle size (PSDA, volume median): 394 nm Whiteness: 80 al water: 25% Example 4: Seed dispersion: Similar to Example 3 Dispersion (swell-core) Similar to Example 3 Dispersion C4 The initial charge, consisting of 261 g of water and 273.21 g of dispersion B3, in a polymerization vessel equipped with an anchor stirrer, a reflux condenser and two feed vessels was heated in a nitrogen atmosphere to a temperature of 81°C. Addition of 25.2 g of a 1.4 wt% sodium peroxodisulfate solution was followed by the metered addition over 120 min of pre- emuision 1, consisting of 132 g of water, 13.6 g of il® LDBS 20, 4.08 g of rylic acid, 17.2 g of methyl methacrylate, 3.4 g of allyl methacrylate and 213.72 g of styrene, together with 24.32 g of a 2.5 wt% sodium peroxodisulfate solution. On completion of the additions, 3.36 g of a 2.5 wt% sodium peroxodisulfate solution were added and the al temperature was raised to 92°C over 40 min. Then, 23.76 g of d—methylstyrene were added over 1 0 min and the feed rinsed with 40.5 g of water. After a further 20 min of stirring 32 g of a 10 wt% ammonia solution were metered in over 5 min and stirred in for 5 min. This was followed by the metered addition within 15 min of pre-emulsion 2, consisting of 98.44 g of water, 7 g of Disponil® LDBS 20, 0.28 g of methacrylic acid and 78 g of lbenzene. Completion of the addition was followed five minutes later by the addition of 5.64 g of a 10 wt% aqueous solution of fart—butyl hydroperoxide and the metering over 20 min of 31 g of a 3 wt% aqueous Rongalit C® solution. minutes after completion of the on a r 9.16 g of a 10 wt% aqueous solution of fan‘- butyl hydroperoxide and 8.52 g of a 5.1 wt% aqueous Rongalit C® solution were added concurrently by metered on over 60 min. 3O Solids content: 29.7% pH: 9.5 le size (PSDA, volume median): 390 nm Whiteness: 80 al water: 25% Example 5: Similar to Example 3 Dispersion (swell-core) Similar to Example 3 40 Dispersion CS The initial charge, consisting of 261 g of water and 273.21 g of dispersion B3, in a polymerization vessel equipped with an anchor stirrer, a reflux condenser and two feed vessels PF 75483 ‘ was heated in a nitrogen atmosphere to a temperature of 81°C. on of 25.2 g of a 1.4 wt% sodium peroxodisulfate solution was followed by the metered addition over 120 min of pre- emulsion 1, consisting of 102 g of water, 13.6 g of Disponil® LDBS 20, 2 g of d oil fatty acids, 17.2 g of methyl methacrylate, 3.4 g of allyl methacrylate and 217.8 g of e, together with 24.32 g of a 2.5 wt% sodium peroxodisulfate solution. On completion of the additions, 3.36 g of a 2.5 wt% sodium peroxodisulfate solution were added and the internal temperature was raised to 92°C over 40 min. Then, 23.76 g of q-methylstyrene were added over 10 min.

After a further 20 min of stirring 219.28 9 of a 3 wt% sodium hydroxide solution were metered in over 20 min and stirred in for 5 min. This was followed by the metered addition within 15 min of 1O pre—emulsion 2, consisting of 40.44 g of water, 7 g of Disponil® LDBS 20, 0.28 g of methacrylic acid and 78 g of divinylbenzene. Completion of the addition was followed five minutes later by the addition of 5.64 g of a 10 wt% aqueous on of Iefi-butyl hydroperoxide and the metering over 20 min of 31 g of a 3 wt% s Rongalit C solution. 30 minutes after completion of the addition a further 9.16 g of a 10 wt% aqueous on of tert—butyl hydroperoxide and 8.52 g of a 5.1 wt% aqueous Rongalit C® solution were added concurrently by metered addition over 60 min.

Solids content: 30% pH: 8.3 Particle size (PSDA, volume median): 400 nm Whiteness: 79 internal water: 24% Example 6: Seed dispersion: Similar to Example 3 Dispersion (swell-core) Similar to Example 3 Dispersion C6 The initial , consisting of 261 g of water and 273.21 9 of sion 83, in a polymerization vessel equipped with an anchor stirrer, a reflux condenser and two feed vessels was heated in a nitrogen atmosphere to a temperature of 81°C. Addition of 25.2 g of a 1.4 wt% sodium peroxodisulfate solution was followed by the metered addition over 120 min of pre- emulsion 1, consisting of 102 g of water, 13.6 g of Disponil® LDBS 20, 2 g of linseed oil fatty acids, 17.2 g of methyl rylate, 3.4 g of allyl methacrylate and 217.8 g of styrene, together with 24.32 g of a 2.5 wt% sodium disulfate solution. On tion of the additions, 3.36 g of a 2.5 wt% sodium peroxodisulfate solution were added and the internal temperature was raised to 92°C over 40 min. Then, 23.76 g of q-methylstyrene were added over 10 min.

After a further 20 min of stirring 243.64 g of a 6 wt% sodium hydrogen carbonate solution were d in over 20 min and stirred in for 5 min. This was followed by the metered on within 40 15 min of pre-emulsion 2, consisting of 40 g of water, 7 g of Disponil® LDBS 20, 0.28 g of methacrylic acid and 78 g of divinylbenzene. Completion of the addition was ed five minutes later by the addition of 5.64 g of a 10 wt% aqueous solution of fert—butyl hydroperoxide PF 75483 and the metering over 20 min of 31 g of a 3 wt% aqueous Rongalit C® solution. 30 minutes after completion of the addition a further 9.16 g of a 10 wt% aqueous solution of ferf-butyl hydroperoxide and 8.52 g of a 5.1 wt% aqueous Rongalit C® solution were added concurrently by metered addition over 60 min.

Solids content: 30% pH: 7.5 le size (PSDA, volume median): 385 nm Whiteness: 79 al water: 24% Example 7: Seed sion: Similar to Example 3 Dispersion (swell—core) B4 The initial charge, consisting of 1958.8 9 of water and 14.54 g of seed dispersion A2, in a polymerization vessel ed with an anchor r, reflux condenser and two feed vessels was heated in a en here to a temperature of 82°C. Two minutes after addition of 26.68 g of a 7 wt% sodium peroxodisulfate solution, 217.96 9 of methyl methacrylate and a solution of 9.34 g of Lutensit® A—EP A, 9.34 g of Disponil® LDBS 20 and 166 g of methacrylic acid in 562 g of water were added concurrently over 90 min. Ten minutes after completion of the addition, 92.55 g of a 1.5 wt% sodium peroxodisulfate on, a mixture of 62 g of n—butyl methacrylate and 345.86 g of methyl methacrylate and also a solution of 2.49 g of Disponil® LDBS 20 and 8.38 g of methacrylic acid in 276.89 9 of water were added concurrently over 75 min. Finally, the feed vessel was rinsed with 33 g of water and polymerization was continued for a further 30 min.

Solids content: 22% pH: 3.5 Particle size (PSDA, volume median): 185 nm 3O Dispersion C7 The initial charge, ting of 261 g of water and 273.21 9 of dispersion B4, in a polymerization vessel equipped with an anchor stirrer, a reflux condenser and two feed vessels was heated in a nitrogen here to a temperature of 81°C. Addition of 25.2 g of a 1.4 wt% sodium peroxodisulfate solution was followed by the metered addition over 120 min of pre- emulsion 1, consisting of 132 g of water, 13.6 g of Disponil® LDBS 20, 2 g of linseed oil fatty acids, 17.2 g of methyl methacrylate, 3.4 g of allyl methacrylate and 217.8 g of styrene, together with 24.32 g of a 2.5 wt% sodium disulfate solution. On completion of the additions, 3.36 g of a 2.5 wt% sodium peroxodisulfate solution were added and the internal temperature was raised to 92°C over 40 min. Then, 23.76 g of q-methylstyrene were added over 10 min and 40 the feed rinsed with 40.5 g of water. After a further 20 min of stirring 32 g of a 10 wt% ammonia solution were metered in over 5 min and stirred in for 5 min. This was followed by the metered addition within 15 min of pre—emulsion 2, consisting of 98.44 g of water, 7 g of Disponil® PF 75483 LDBS 20, 0.28 g of methacrylic acid and 78 g of divinylbenzene. Completion of the addition was followed five minutes later by the addition of 5.64 g of a 1 0 wt% aqueous solution of fert—butyl hydroperoxide and the metering over 20 min of 31 g of a 3 wt% aqueous Rongalit C® solution. minutes after completion of the addition a further 9.16 g of a 10 wt% aqueous solution of fert- butyl hydroperoxide and 8.52 g of a 5.1 wt% aqueous Rongalit C® solution were added concurrently by metered addition over 60 min.

Solids content: 30% pH: 7.5 Particle size (PSDA, volume median): 385 nm 1O Whiteness: 79 lnternal water: 24% Example 8: Seed dispersion: Similar to Example 1 Dispersion (swell-core) BS The initial charge, consisting of 1958.8 g of water and 14.54 g of seed sion A1, in a polymerization vessel ed with an anchor stirrer, reflux ser and two feed vessels was heated in a en atmosphere to a ature of 82°C. Two minutes after addition of 26.68 g of a 7 wt% sodium peroxodisulfate solution, a mixture of 3.84 g of 2~ethylhexyl thioglycolate and 217.34 g of methyl methacrylate and a solution of 9.34 g of Lutensit® A~EP A, 9.34 g of Disponil® LDBS 20 and 166 g of methacrylic acid in 562 g of water were added concurrently over 90 min. Ten minutes after completion of the addition, 92.55 g of a 1.5 wt% sodium peroxodisulfate solution, a e of 62 g of n-butyl methacrylate and 345.86 9 of methyl methacrylate and also a solution of 2.49 g of Disponil® LDBS 20 and 8.38 g of methacrylic acid in 276.89 9 of water were added concurrently over 75 min. y, the feed vessel was rinsed with 33 g of water and polymerization was continued for a further 30 min.

Solids t: 21.9% pH: 3.7 le size (PSDA, volume median): 187 nm Dispersion C8 The initial Charge, consisting of 261 g of water and 273.21 9 of dispersion B5, in a polymerization vessel equipped with an anchor stirrer, a reflux condenser and two feed vessels was heated in a nitrogen here to a temperature of 81°C. Addition of 25.2 g of a 1.4 wt% sodium peroxodisulfate solution was followed by the metered addition over 120 min of pre- emulsion 1, consisting of 132 g of water, 13.6 g of Disponil® LDBS 20, 2 g of d oil fatty acids, 17.2 g of methyl methacrylate, 3.4 g of allyl methacrylate and 217.8 g of styrene, together with 24.32 g of a 2.5 wt% sodium peroxodisulfate solution. On completion of the additions, 40 3.36 g of a 2.5 wt% sodium peroxodisulfate solution were added and the internal temperature was raised to 92°C over 40 min. Then, 23.76 g of q-methylstyrene were added over 10 min and the feed rinsed with 40.5 g of water. After a further 20 min of stirring 32 g of a 10 wt% ammonia PF 75483 solution were d in over 5 min and stirred in for 5 min. This was followed by the metered addition within 15 min of pre-emulsion 2, ting of 98.44 g of water, 7 g of Disponil® LDBS 20, 0.28 g of methacrylic acid and 78 g of divinylbenzene. Completion of the addition was followed five minutes later by the addition of 5.64 g of a 10 wt% aqueous solution of fed-butyi hydroperoxide and the metering over 20 min of 31 g of a 3 wt% aqueous Rongalit C® solution. minutes after completion of the addition a further 9.16 g of a 10 wt% aqueous solution of fan‘- butyl eroxide and 8.52 g of a 5.1 wt% aqueous Rongalit C® solution were added concurrently by metered addition over 60 min.

Solids content: 30% pH: 7.5 Particle size (PSDA, volume median): 405 nm Whiteness: 80 al water: 26% Example 9: Dispersion (swell—core) B6 ' The initial charge, ting of 521 g of water and 1.64 g of Disponil® FES 993, in a polymerization vessel equipped with an anchor stirrer, a reflux condenser and two feed vessels was heated in a nitrogen atmosphere to a ature of 82°C. Then pre-emulsion 1 consisting of 15.19 g of water, 0.27 g of Disponil® FES 993, 27.88 g of methyl methacrylate and 0.33 g of methacrylic acid and 11.43 g of a 10 wt% sodium peroxodisulfate solution was added before rizing for 30 min during which the temperature within the polymerization vessel was adjusted to 85°C. Thereafter pre-emulsion 2, consisting of 485.67 g of water, 27.22 g of Disponil® FES 993, 334.22 g of methyl methacrylate, 9 g of allyl rylate and 228.82 g of rylic acid was added over 120 min at 85°C. Finally, the feed vessel was rinsed with 10 g of water and the system was postpolymerized for a further 15 min. Subsequently, 133.35 9 of a 1.5 wt% sodium peroxodisulfate solution; a mixture of 89.33 g of n-butyl methacrylate and 489.33 9 of methyl methacrylate; and also a solution of 3.59 g of Disponil® LDBS 20 and 12.07 g of methacrylic acid in 700 g of water; were added concurrently over 75 min. Finally the feed vessel was rinsed with 48 g of water and the system was postpolymerized for a further min.

Solids content: 33.1% pH: 3.7 le size (PSDA, volume ): 189 nm Dispersion C9 The initial charge, consisting of 354.16 g of water and 179.94 g of dispersion BB, in a polymerization vessel equipped with an anchor stirrer, a reflux condenser and two feed vessels was heated in a nitrogen atmosphere to a temperature of 81°C. Addition of 25.2 g of a 1.4 wt% 40 sodium peroxodisulfate solution was followed by the metered addition over 120 min of preemulsion 1, ting of 132 g of water, 13.6 g of Disponil® LDBS 20, 2 g of linseed oil fatty acids, 10.88 g of acrylonitrile, 17.2 g of methyl methacrylate, 3.4 g of allyl methacrylate and PF 75483 206.9 g of styrene, together with 24.32 g of a 2.5 wt% sodium peroxodisulfate solution. On completion of the ons, 3.36 g of a 2.5 wt% sodium disulfate solution were added and the internal temperature was raised to 92°C over 40 min. Then, 23.76 g of o—methylstyrene were added over 10 min and the feed line rinsed with 40.5 g of water. After a further 20 min of stirring 32 g ofa 10 wt% ammonia solution were metered in over 5 min and stirred in for 5 min. _ This was followed by the metered addition within 15 min of pre-emulsion 2, consisting of 98.44 g of water, 7 g of Disponil® LDBS 20, 0.28 g of methacrylic acid and 78 g of divinylbenzene. Five minutes on completion of the addition were followed by the addition of 5.64 g of a 10 wt% aqueous solution of z‘efi-butyl eroxide and the metering over 20 min of 31 g of a 3 wt% 1O aqueous Rongalit C® solution. 30 minutes after completion of the addition a further 9.16 g of a wt% aqueous solution of feI'I-butyl hydroperoxide and 8.52 g of a 5.1 wt% aqueous Rongalit C® solution were added concurrently by metered on over 60 min.

Solids content: 29.8% pH: 9.5 Particle size (PSDA, volume median): 398 nm Whiteness: 80 internal water: 25% Example 10: sion (swell-core) B7 The l charge, consisting of 478.53 g of water, 1.64 g of Disponil® FES 993 and 13.27 of EFKA® 3031, in a polymerization vessel equipped with an anchor stirrer, a reflux condenser and two feed vessels was heated in a nitrogen atmosphere to a ature of 82°C. Then pre- emulsion 1 consisting of 80.68 g of water, 0.27 g of Disponil® FES 993, 27.88 g of methyl methacrylate and 0.33 g of methacrylic acid and 15.88 g of a 7 wt% sodium peroxodisulfate on was added before polymerizing for 30 min during which the temperature within the polymerization vessel was adjusted to 85°C. Thereafter pre—emulsion 2, ting of 485.67 g of water, 27.22 g of Disponil® FES 993, 334.22 g of methyl methacrylate, 9.00 g of allyl methacrylate and 228.82 g of methacrylic acid was added over 120 min at 85°C. Finally, the feed vessel was rinsed with 450.16 g of water and the system was postpolymerized for a further min. uently, 133.35 9 of a 1.5 wt% sodium peroxodisulfate solution; a mixture of 89.33 g of n-butyl rylate and 489.33 g of methyl methacrylate; and also a solution of 3.59 g of Disponil® LDBS 20 and 12.07 g of methacrylic acid in 700 g of water; were added concurrently over 75 min. Finally the feed vessel was rinsed with 48 g of water and the system was postpolymerized for a further 30 min.

Solids t: 33.1% pH: 2.9 Particle size (PSDA, volume median): 188 nm 40 Dispersion C10 The initial charge, consisting of 354 g of water and 175 g of dispersion B7, in a polymerization vessel equipped with an anchor stirrer, a reflux condenser and two feed vessels was heated in PF 75483 a nitrogen atmosphere to a temperature of 81°C. Addition of 25.2 g of a 1.4 wt% sodium peroxodisulfate solution was followed by the metered addition over 120 min of pre—emulsion 1, consisting of 102 g of water, 13.6 g of Disponil® LDBS 20, 2 g of linseed oil fatty acids, 17.2 g of methyl methacrylate, 3.4 g of allyl methacrylate and 217.8 g of styrene, together with 24.32 g of a 2.5 wt% sodium peroxodisulfate solution. On completion of the metered additions 3.36 g of a 2.5 wt% sodium peroxodisulfate solution was added and the al temperature was raised to 92°C over 40 min. Then 23.76 g of q-methylstyrene were added over 10 min. After a further min of stirring, 243.64 g of a 2.8 wt% sodium hydroxide solution were metered in over 20 min and stirred in for 60 min. This was followed by the metered addition within 15 min of pre— emulsion 2, consisting of 40 g of water, 7 g of Disponil® LDBS 20, 0.28 g of methacrylic acid and 7.8 g of e. Completion of the addition was ed five minutes later by the addition of 5.64 g of a 10 wt% aqueous solution of felt-butyl eroxide and the metering over 20 min of 31 g of a 3 wt% aqueous Rongalit C® on. 30 minutes after completion of the addition a r 9.16 g of a 10 wt% aqueous solution of z‘efi-butyl eroxide and 8.52 g of a 5.1 wt% aqueous Rongalit C® solution were added concurrently by metered addition over 60 min.

Solids content: 29.5% pH: 8.6 Particle size (PSDA, volume median): 398 nm.

Whiteness: 80 Internal water: 25%.

Claims (18)

We claim :-

1. A process for ing emulsion polymer particles by ing a multistaged emulsion polymer by polymerizing in a sequential polymerization i) a seed, and ii) then reacting with a swell-seed comprising 55 to 99.9 wt% of one or more than one nonionic nically unsaturated monomer and 0.1 to 45 wt% of one or more than one ethylenically unsaturated hydrophilic monomer, all based on the 10 overall weight of the core stage r comprising both seed and swell-seed, iii) then polymerizing a first shell comprising 85 to 99.9 wt% of one or more than one nonionic nically unsaturated r and 0.1 to 15 wt% of one or more than one hydrophilic ethylenically unsaturated monomer, iv) then polymerizing a second shell comprising 85 to 99.9 wt% of one or more than 15 one nonionic ethylenically unsaturated monomer and 0.1 to 15 wt% of one or more than one hydrophilic ethylenically rated monomer, v) then adding at least one plasticizer monomer having a ceiling temperature below 181°C, vi) neutralizing, to a pH of not less than 7.5 or greater, the resultant particles with one 20 or more bases, vii) then polymerizing a third shell comprising 90 to 99.9 wt% of one or more than one nonionic ethylenically unsaturated monomer and 0.1 to 10 wt% of one or more than one hydrophilic ethylenically unsaturated monomer, viii) and also optionally rizing one or more further shells comprising one or 25 more than one nonionic ethylenically unsaturated monomer and one or more than one hydrophilic ethylenically unsaturated monomer, wherein the weight ratio of said swell-seed (ii) to said seed polymer (i) is in the range from 10:1 to 150:1, 30 the weight ratio of the core stage polymer to said first shell (iii) is in the range from

2. :1 to 1:5, and weight ratio of said third shell (vii) to said second shell (iv) is in the range from 1:2 to 1:10. 35 2. The process according to claim 1 wherein the average particle size in the len state of the core stage polymer of seed (i) and swell-seed (ii) is in the range from 50 to 300 nm.

3. The process according to either of claims 1 and 2 wherein in the protonated state 40 the glass transition temperature, determined by the Fox equation, of the core stage polymer is between -20°C and 150°C.

4. The process ing to any one of claims 1 to 3 wherein said shell polymer (iii) in the protonated state has a glass tion temperature determined by the Fox equation between -60°C and 120°C.

5. The process according to any one of claims 1 to 4 wherein the particle size of stage (iii) in the unswollen state is from 60 nm to 500 nm. 5

6. The process according to any one of claims 1 to 5 wherein said shell polymer (iv) in the protonated state has a Fox glass transition ature of 50 to 120°C.

7. The process according to any one of claims 1 to 6 wherein the average le size of stage (iv) is in the range from 70 to 1000 nm.

8. The process according to any one of claims 1 to 7 wherein the plasticizer monomer recited under (v) is selected from the group α-methylstyrene, esters of ylacrylic acid/atropic acid (e.g., , ethyl, n-propyl, n-butyl), 2-methyl butene, 2,3-dimethylbutene, 1,1-diphenylethene or methyl 2-tert-butylacrylate.

9. The process according to any one of claims 1 to 8 wherein the bases recited under (vi) are selected from the group of alkali metal or alkaline earth metal compounds such as sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium oxide, sodium carbonate; ammonia; primary, secondary and tertiary amines, such 20 as ethylamine, propylamine, monoisopropylamine, monobutylamine, hexylamine, ethanolamine, dimethylamine, diethylamine, ropylamine, tributylamine, triethanolamine, dimethoxyethylamine, 2-ethoxyethylamine, 3-ethoxypropylamine, dimethylethanolamine, diisopropanolamine, morpholine, ethylenediamine, 2- laminoethylamine, 2,3-diaminopropane, 1,2-propylenediamine, 25 dimethylaminopropylamine, neopentanediamine, hexamethylenediamine, 4,9- dioxadodecane-1,12-diamine, polyethyleneimine, polyvinylamine or es

10. The process according to any one of claims 1 to 9 wherein said shell polymer (vii) 30 in the protonated state has a Fox glass transition ature of 50 to 120°C.

11. The process according to any one of claims 1 to 10 wherein the polymer has an internal water content of 20% to 40%, based on the entire water content of the sion.

12. An emulsion polymer particle ed by a process according to any one of claims 1 to 11.

13. An emulsion r particle obtained by a process according to any one of 40 claims 1 to 11, which has an internal water content of 20% to 40%, based on the entire water content of the dispersion.

14. The emulsion polymer particle obtained by a process according to any one of claims 1 to 11 wherein the whiteness of the polymer particles used is  78.

15. The use of the polymer les obtained according to a process of any one of claims 1 to 11 in paints, paper coatings, cosmetic compositions, crop protection agents, liquid inks, foams or in thermoplastic molding nds.

16. A paint comprising polymer particles obtained according to a process of any one of claims 1 to 11.

17. The paint according to claim 16 wherein the whiteness of the polymer particles 10 used is  78.

18. The process according to claim 1, substantially as herein described with reference to any one of the es thereof.