KR20070018920A - Particle-stabilised emulsions - Google Patents

Abstract

The present invention relates to an oil phase (phase A) containing at least one substantially water insoluble component; Water phase (component B) which may optionally further contain other water soluble components such as salts or organic compounds such as alcohols, carboxylic acids or other compounds,

Arranged at the oil-water interface and partially silylated so that the content of unsilylated surface silanol groups on the silica surface is 95-5% by weight of the starting silica (corresponding to 1.7-0.1 SiOH groups per 1 nm ^{2 of} silica surface), Pyrogenic silica having a surface energy gamma-sD of the dispersion portion of 30 to 80 mJ / m ² and a BET specific surface area of 30 to 500 m ² / g, and

-Additional substances such as pigments or preservatives

It relates to water-in-oil (W / 0) or oil-in-water emulsion (O / W) containing. The average particle size of the dispersed phase of the emulsion of the present invention, that is, the average droplet diameter is 0.5 to 500 m, and the emulsion of the present invention has a low viscosity.

Description

Particle-stabilized emulsions {PARTICLE-STABILISED EMULSIONS}

The present invention relates to water-in-oil (W / O) type or oil-in-water (O / W) type emulsions and their preparation.

Emulsions as water-in-oil (W / O) or oil-in-water (O / W) dispersions, for example in application forms for coatings such as water-based paints and finishes, for example as adhesives and encapsulants such as aqueous epoxy or polyurethane-based, as cosmetic compositions, It is widely used in the food industry as a cleaning or disinfectant for surface modification of solid or liquid substrates or as a reaction medium in emulsion polymerization.

In general, dispersion and stabilization of the dispersed phase is achieved with the aid of emulsifiers. Cationic, anionic, zwitterionic and nonionic emulsifiers are used. Emulsifiers are typically surface-active materials. In other words, the emulsifier is preferably accumulated at an interface such as a liquid-liquid, liquid-solid or liquid-based interface to reduce the interface / surface energy. However, in emulsion application, the emulsion can also cover the surface of the substrate to be treated to significantly change the wetting properties of the surface. This may adversely affect, for example, the adhesive properties of the coating or the adhesive properties of the adhesive bonds or encapsulants. Organic molecular emulsifiers are also potentially harmful substances when used in pharmaceutical or cosmetic compositions or foods.

In 1907, Pickering initiated the preparation of emulsions that were stabilized simply by adding various solids such as basic copper sulfate, basic iron sulfate or other metal salts. This type of emulsion is also called a "pickering emulsion". Basic research has shown that pickling emulsions are characterized by particles arranged at the interface between two liquid phases, thereby forming a barrier to dispersed phase coalescence.

 However, such solid-stabilized emulsions, such as, for example, those disclosed in EP 987008, have a high viscosity and / or a tendency to separate, so that the dispersed phase often settles or creaming occurs.

It is an object of the present invention to overcome the disadvantages of the prior art, in particular to provide a low-viscosity and sediment-stable emulsion with a small particle diameter of the dispersed phase.

This object is achieved by the present invention.

The present invention

An oil phase (phase A) containing a substantially water insoluble component or optionally a plurality of substantially water insoluble components,

Aqueous phase (phase B) which may optionally further contain water-soluble components such as salts or organic compounds such as alcohols, carboxylic acids or other compounds,

Arranged at the oil-water interface and partially silylated so that the content of unsilylated surface silanol groups on the silica surface is 95-5% of the starting silica (corresponding to 1.7-0.1 SiOH groups per 1 nm ^{2 of} silica surface) and dispersion Pyrogenic silica having a surface energy gamma-sD of 30 to 80 mJ / m ² and a BET specific surface area of 30 to 500 m ² / g, and

-Additional substances such as pigments or preservatives

A low viscosity water-in-oil (W / O) type or oil-in-water (O / W) type emulsion having an average particle size of the dispersed phase measured by laser diffraction, that is, an average droplet diameter of 0.5 to 500 µm, Low viscosity means that the relative viscosity (η _r ) of the emulsion is 1-10 ⁶ , and relative viscosity means that the measured viscosity (η) of the emulsion measured at 25 ° C. and shear rate of D = 10 s ⁻¹ is the viscosity of the pure homogeneous phase ( η ₀ ) divided by (η _rel = η / η ₀ ), and the relative viscosity of the emulsion (η _rel ) is defined by the formula η _rel = (1-φ / 0.74) ^{-([η] · 0.74)} (wherein , φ is the phase volume of the dispersed phase and [η] is the form factor of 2.5-100 for the emulsion of the invention).

It was surprising and unexpected to those skilled in the art that the use of sintered-aggregated pyrogenic silica as fine emulsifiers yielded low-viscosity and settling-stable emulsions with small particle diameters in the dispersed phase. This is surprising in that sinter-aggregated pyrogenic silica is commonly used as a rheological additive to increase the viscosity of the liquid medium.

However, the sintered aggregate is a secondary structure according to DIN 53206, which is permanent at shear conditions, as usually occurs on disperse fillers in liquid media such as solvent-containing or solvent-free adhesives or coatings. That is, it cannot be separated into primary particles. This can be demonstrated, for example, from TEM images of cured silica-binder dispersions with only aggregate structures and no discrete primary particles.

Particles based made of a sintered formations also, the hydraulic equivalent diameter is obtained from the measured particle size by quasi-elastic light scattering equation _{a = 6 / A BET · d} ( wherein, A _BET is and BET specific surface area as measured by nitrogen absorption according to DIN 66131 , d is the density of the primary particles), characterized in that more than two factors larger than the diameter of the primary particles obtainable by the computer.

The sintered aggregation system is also characterized by the fact that the fractal dimension df of the mass is less than 2.7, where the fractal dimension df is defined such that the mass is proportional to the radius R relative to the power df. The fractal dimension of the mass can be measured, for example, by incineration X-rays or neutron scattering.

The emulsions of the invention are preferably substantially free of pure organic surface-active materials which are not particulates at atmospheric pressure and room temperature, such as conventional liquids and solids, nonionic, cationic and anionic emulsifiers.

Here, nonparticulate emulsifiers do not mean particles and colloids, but molecules and polymers, and definitions of molecules, polymers, colloids and particles are described in "Dispersionen und Emulsionen [Dispersions and emulsions]", G. Lagaly, O. Schulz, R. Zindel, Steinkopff, Darmstadt 1997, ISBN 3-7985-1087-3, page 14. In general, these organic emulsifiers are less than 1 nm in size, have a molar mass of 10,000 g / mol, a carbon content that can be measured by elemental analysis of more than 50% by weight and a Mohs strength of less than 1.

At the same time, the emulsifiers of the present invention are preferably substantially free and generally have a solubility in water of more than 1% by weight at 20 ° C. at a pressure of normal pressure (ie 900-1100 hPa) and are homogeneous or micelles. The emulsions of the present invention may contain such surface-active materials in water at maximum concentrations of less than 0.1 times, preferably less than 0.01 times, particularly preferably less than 0.001 times, especially less than 0.0001 times, the critical micelle concentration of the surface-active substances. This corresponds to a concentration of the surface-active substance of less than 10% by weight, preferably less than 2% by weight, particularly preferably less than 1% by weight, in particular 0% by weight, based on the total weight of the emulsion of the invention. .

The emulsion of the invention contains an oil phase (phase A). Phase A contains one substantially water insoluble component, optionally a plurality of substantially water insoluble components. Substantially water insoluble herein means that the solubility of the components in water alone or in mixtures is less than 10 g, preferably less than 1 g, per 100 g of water as measured at atmospheric pressure (ie, 900-1100 hPa) and at 20 ° C. Particularly preferably less than 0.1 g.

In the case of the emulsion of the present invention, the viscosity of phase A measured at a shear gradient of 25 ° C. and 10 s ⁻¹ is 0.1 to 1,000,000 mPa · s, preferably 0.1 to 500,000 mPa · s, particularly preferably 0.2 to 100,000 mPa · s.

In the case of the emulsion of the invention, phase A may preferably contain a plurality of components. Each component may be a material that is liquid and solid at 20 ° C., and the entire mixture of each component has the viscosity described above. Preferably, but not necessarily, multicomponent phase A is a true solution, ie a homogeneous phase in which no further phase interface occurs.

Examples of substantially water-insoluble components formed by or inherent in Phase A of the emulsion of the present invention include aliphatic and aromatic hydrocarbons, alcohols, aldehydes, ketones, ethers, esters, amines, carboxylic acids and derivatives thereof, Polycondensates of 1,2-propanediol with phthalic acid dissolved in reactive diluents such as mercaptans, thioethers, oligomers and polymeric compounds such as polyolefins such as polystyrene, polypropylene or polyethylene, saturated or unsaturated polyesters such as styrene Or polycondensates of phthalic acid, 1,2-propanediol and maleic acid, polyethers, polyepoxides or monomers or oligomer precursors thereof, such as

Alkylene bisglycidyl ethers such as

(Wherein n is preferably 0 to 10, particularly preferably 0 to 5)

Bisphenol A diglycidyl ether such as

Epoxy novolac resin such as

Difunctional epoxy compounds such as

Trifunctional epoxy compounds such as

Tetrafunctional epoxy compounds, such as

Polyurethanes or monomers or oligomer precursors thereof such as polyetherpolyols, polyacrylatepolyols, polyesterpolyols, polyfunctional isocyanates such as hexane diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate or isocyanates provided with blocking protecting groups Hydroxylamine or malonic ester derivatives, organic complexes such as synthetic or natural pharmaceutical or cosmetic active substances, dyes, organo-element compounds such as organosilicon compounds such as organic (poly) silanes, organic (poly) siloxanes, organic ( Poly) silazanes and organic (poly) silcarbanes or transition metal compounds. Optionally phase A may contain oil-wettable particles such as pigments, fillers or rheological additives.

The emulsion of the invention also contains an aqueous phase (phase B). In addition to water, phase B is a further component, preferably an acid, a base, a salt, a water-soluble organic compound such as alcohols, carboxylic acids and derivatives thereof, amines or other organic compounds, polymers or oligomer compounds such as polyols or polyamines. Or polyamidoamines, water soluble organic complexes such as synthetic or natural pharmaceutical or cosmetic active substances, dyes, organo-element compounds such as water soluble organosilicon compounds or water soluble transition metal compounds. Optionally, phase B may contain water-wettable particles such as pigments, fillers or rheological additives.

The emulsion of the invention contains a sintered aggregate of suitable pyrogenic silica, which is arranged at the oil-water interface. The sintered aggregates used according to the invention are partly wetted with water, i.e. not completely wetted with water and are not completely water-invasive.

The sintered aggregates used according to the invention are sintered aggregates which are solid at a pressure of normal pressure (ie 900 to 1100 hPa) and at room temperature.

The solubility in water of the sintered aggregates used according to the invention is preferably less than 0.1 g / l, particularly preferred at pH 7.33 and 0.11 mole of electrolyte background and at a pressure of normal pressure (ie 900-1100 hPa) and at a temperature of 37 ° C. Preferably less than 0.05 g / l.

The average hydraulic equivalent diameter D _h of the sintered aggregates used according to the invention is preferably greater than 1 nm, preferably 1 to 5000 nm, preferably 10 to 1000 nm, particularly preferably measured by dynamic light scattering. Is 100-600 nm, very particularly preferably 200-500 nm, especially 210-450 nm.

This implies that the impact radius R _c of the sintered aggregate suitable for the formation of the particle layer at the oil-water interface is greater than 0.8 nm, preferably 0.8 to 4000 nm, preferably 8 to 850 nm, particularly preferably 80 to 500 nm. Very particularly preferably from 170 to 375 nm. The impact radius is the radius of the smallest sphere that contains all the components of the aggregate, and the impact radius R _c is described in R. de Rooij, AA Potanin, D. Van den Ende, J. Mellema, J. Chem. Phys. 1993, 99, 9213] is obtained from the equation R _c = [R _h ² /0.76 + 2.63.R _h ² / d _f ] ^0.5 and the hydraulic equivalent radius (R _h ) corresponds to the hydraulic equivalent diameters of 2 and 1.8. Obtained by dividing the fractal dimension with the value of.

The sintered aggregates used according to the invention are also preferably used in the particle size measurement using quasi-elastic light scattering, where the equivalent hydraulic diameter is in each case based on a specific surface area of 100 m ² / g, where a = 6 / A _BET , A _BET is the BET specific surface measured by nitrogen absorption in accordance with DIN 66131, and d is the density of the primary particles), at least 2 factors, preferably 5 to 50 factors, than the primary particle diameter obtainable by the computer. , Particularly preferably 7 to 25 factors, very particularly preferably 7.5 to 16.5 factors, large (the factor increases or decreases in a corresponding linear fashion if the surface area is smaller or larger).

The molar mass of the sintered aggregates used according to the invention is in each case preferably greater than 10,000 g / mol, preferably 50,000 to 50,000,000 g / mol, especially 100,000 to 10,000,000 g / mol, as measured by static light scattering.

The BET specific surface area of the sintered aggregates used according to the invention is preferably 30 to 500 m ² / g, particularly preferably 80 to 300 m ² / g. The BET surface area is measured according to known methods, preferably according to the German industry standards DIN 66131 and DIN 66132.

The carbon content of the sintered aggregates used according to the invention is preferably less than 50% by weight.

The Mohs strength of the sintered aggregates used according to the invention is preferably greater than 1, particularly preferably greater than 4.

The surface gamma energy of the sintered aggregate is 30-72.5 mJ / m ² at a pressure of normal pressure (ie 900-1100 hPa) and a temperature of 25 ° C.

The surface energy gamma-sD of the dispersion portion of the silica sintered aggregate used according to the invention is 30 to 80 mJ / m ² , preferably 35 to 70 at a pressure of normal pressure (ie 900 to 1100 hPa) and a temperature of 25 ° C. mJ / m ² , particularly preferably 40 to 70 mJ / m ² . The surface energy gamma-sD of the dispersion portion is described, for example, in "Inverse Gas Chromatography"-"Characterisation of Polymers and other Materials", 391 ACS Symposium , DR Lloyd, Th C Ward, HP Schreiber, Chapter 18, pages 248-261. ACS, Washington DC, 1989, ISBN 0-8412-1610-X].

Preferred starting silicas from which the silica used in the partially water-wetting emulsions according to the invention can be prepared are, for example, halogen-silicon compounds (eg silicon trichloride) or halogen-organosilicon compounds (eg methylchlorosilane, e.g. methyltrichloro Silanes or hydrogenchlorosilanes such as hydrogentrichlorosilane, or other hydrogenmethylchlorosilanes such as hydrogenmethyldichlorosilane, or alkylchlorosilane) or any predetermined atomizable of the above-mentioned organosilicon compounds and hydrocarbons, preferably Can be prepared by any desired method known per se, such as in flame reactions from volatile mixtures (the flame can be a hydrogen-oxygen flame or a carbon monoxide-oxygen flame). The preparation of the silica can be carried out, for example, with or without further water in the purification step, preferably with no water.

Preferably, partially calcined, particularly preferably partially silylated, silica sintered aggregates are used as silica sintered aggregates in the preparation of the emulsions of the invention.

Here, partially silylated means that the entire silica surface is neither silylated nor unsilylated.

The coating degree (τ) of the silica sintered aggregate surface by the silylating agent radical is preferably 5 to 95%, particularly preferably 10 to 90%, especially 15 to 75%, based on the total particle surface.

The coating with the silylating agent can be measured, for example, by elemental analysis by means of the residual content of the reactive surface silanol groups of the silica sintered aggregate or via the carbon content.

Partial silylation also means that the content of unsilylated surface silanol groups on the silica surface is 95 to 5%, particularly preferably 90 to 10% and especially 85 to 25% of the silanol groups of the starting silica.

This means that the density of the surface silanol groups (SiOH) is preferably 0.1 to 1.7 SiOH, preferably 0.2 to 1.6 SiOH, particularly preferably 0.45 to 1.55 SiOH per particle surface (nm ² ).

For starting silicas with a specific surface area of 200 m ² / g that can be used for silylation, this preferably means 0.03 to 0.57 mmol, preferably 0.06 to 0.54 mmol, particularly preferably 0.15 to 0.51 mmol per g of SiOH. In the case of silica having a smaller or larger surface area, this means more or less surface silanol groups (SiOH) in linear proportion.

The carbon content of the silica used according to the invention is 0.1 to 20% by weight, preferably 0.1 to 15% by weight, particularly preferably 0.1 to 10% by weight.

Processes for partial plasticization or partial silylation of solid particles are already known.

Preferably, the specific surface area of the starting silica is 25-500 m ² / g. The starting silica preferably has sintered aggregates (defined according to DIN 53206) in the range 200-1000 nm in diameter, consists of sintered aggregates and granulates 1-500 μm depending on the external shear rod (e.g. measurement conditions). Phosphorus aggregates (defined according to DIN 53206).

The surface fractal dimension of the starting silica is preferably 2.3 or less and the surface fractal dimension (D _s ) is defined herein as follows: The particle surface (A) is proportional to the particle radius (R) for the power of D _s . . The density of the accessible, ie chemically reactive surface silanol groups (SiOH) of the starting silica is from 1.5 to 2.5 SiOH, particularly preferably from 1.6 to 2.0 SiOH, per 1 nm ² of specific surface area.

In the production of silica sintered aggregates used according to the invention, silica prepared at high temperatures (above 1000 ° C.) can be used as starting silica, with pyrogenic silica being particularly preferred. Newly prepared hydrophilic silicas obtained directly from the burners or temporarily stored or already packaged may be used.

Undensified silica with a packing and packing density of less than 60 g / l, densified silica with a packing and packing density of more than 60 g / l can be used as starting silica.

Mixtures of different silicas, such as silica mixtures of different BET surface areas, can be used as starting silica.

In silylation of silica, organosilicon compounds such as (i) or (ii) or mixtures of (i) and (ii) can be preferably used, for example:

(i) organosilanes or organosilazanes of formula (I) and / or partial hydrolysis products thereof

R ¹ _d SiY _4-d

In the above formula,

R ¹ is a C _1-24 aromatic hydrocarbon radical which may be the same or different and may be interrupted by a monovalent optionally substituted optionally monounsaturated or polyunsaturated optionally oxygen atom,

d is 1, 2 or 3,

Y may be the same or different and a halogen atom, a monovalent Si—N-bonded nitrogen radical to which additional silyl radicals may be bonded, —OR ² or —OC (O) OR ² , wherein R ² is hydrogen Is a hydrocarbon radical which may be interrupted by an atom or a monovalent optionally substituted optionally monounsaturated or polyunsaturated oxygen atom.

(ii) linear, branched or cyclic organosiloxanes comprising units of the formula

R ³ _e (OR ⁴ ) _f SiO _{(4-ef) / 2}

In the above formula,

R ³ may be the same or different and is one of those disclosed for R ¹ ,

R ⁴ may be the same or different and has the meanings disclosed for R ³ ,

e is 0, 1, 2 or 3,

f is 0, 1, 2 or 3, except that the sum of e + f is 3 or less.

The organosilicon compounds that can be used for silylation of silica can be, for example, silazanes of formula (I) or mixtures of silanes, preferably comprising methylchlorosilanes or alkoxysilanes and optionally disilazane.

Examples of R ¹ in formula (I) are preferably methyl, octyl, phenyl and vinyl radicals, particularly preferably methyl radicals.

Examples of R ² are preferably methyl, ethyl, propyl and octyl radicals, with methyl and ethyl radicals being preferred.

Examples of organosilanes of formula I include alkylchlorosilanes such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, octylmethyldichlorosilane, octyltrichlorosilane, octadecylmethyldichlorosilane and octadecyltrichlorosilane, methylmeth Methoxysilanes such as methyltrimethoxysilane, dimethyldimethoxysilane and trimethylmethoxysilane, methylethoxysilanes such as methyltriethoxysilane, dimethyldiethoxysilane and trimethylethoxysilane, methylacetoxysilane such as methyl Triacetoxysilane, dimethyldiacetoxysilane and trimethylacetoxysilane, phenylsilanes such as phenyltrichlorosilane, phenylmethyldichlorosilane, phenyldimethylchlorosilane, phenyltrimethoxysilane, phenylmethyldimethoxysilane, phenyldimethylmeth Methoxysilane, phenyltriethoxysilane, phenylmethyldiethoxysilane and phenyldimethylethoxysilane, vinylsilane, eg For example, vinyltrichlorosilane, vinylmethyldichlorosilane, vinyldimethylchlorosilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane and vinyldimethylethoxy Silanes, disilazanes such as hexamethyldisilazane, divinyltetramethyldisilazane and bis (3,3-trifluoropropyl) tetramethyldisilazane, cyclosilazane such as octamethylcyclotetrasilazane and Silanols such as trimethylsilanol.

 Preference is given to methyltrichlorosilane, dimethyldichlorosilane and trimethylchlorosilane or hexamethyldisilazane.

Examples of organosiloxanes of formula (II) are linear or cyclic dialkylsiloxanes having an average number of dialkylsilyloxy units greater than three. Dialkylsiloxanes are preferably dimethylsiloxanes. Trimethylsilyloxy, dimethylhydroxysilyloxy, dimethylchlorosilyloxy, methyldichlorosilyloxy, dimethylmethoxysilyloxy, methyldimethoxysilyloxy, dimethylethoxysilyloxy, methyldiethoxysilyloxy, dimethylacetoxysilyloxy, Particular preference is given to linear polydimethylsiloxanes having end groups such as methyldiacetoxysilyloxy and dimethylhydroxysilyloxy groups, in particular trimethylsilyloxy or dimethylhydroxysilyloxy end groups.

The viscosity at 25 degrees C of the said polydimethylsiloxane is 2-100 mPa * s.

Further examples of organosiloxanes are silicone resins, especially those containing methyl groups as alkyl groups, particularly preferably those containing R ³ ₃ SiO _1/2 and SiO _4/2 units or R ³ SiO _3/2 and optionally R ³ _It contains ₂ SiO _2/2 units (wherein R ³ is one of the above meanings).

The viscosity at 25 ° C. of the silicone resin comprising units of formula (II) is preferably 500 to 5000 mm ² / s.

Preferred silicone resins having a viscosity above 1000 mm ² / s at 25 ° C. are solvents which are technically easily handled, such as preferably at a pressure of atmospheric pressure and a mixture viscosity of 1000 mm ² / s at a temperature of 25 ° C. 10% by weight or more in alcohols such as methanol, ethanol, isopropanol, ethers such as diethyl ether, siloxanes such as tetrahydrofuran, hexamethyldisiloxane, alkanes such as cyclohexane or n-octane, aromatics such as toluene or xylene It can be dissolved at a temperature.

It is preferred to dissolve in solid organosiloxanes (as defined above) in solvents which are technically easily handled at a pressure of atmospheric pressure and a mixture viscosity of 1000 mm ² / s and a concentration of more than 10% by weight at a temperature of 25 ° C. Do.

Firing and silylation, which are preferably carried out during the preparation of the silica sintered aggregates used according to the invention, can be carried out in a batch reaction, ie by a batch process or in a continuous reaction, with continuous reaction being preferred.

Plasticization and silylation can be carried out in one step or in two or three successive steps. This means that the loading (physical adsorption of the silylating agent) can be carried out upstream of the reaction and the purification step can preferably be carried out downstream of the reaction. Three successive steps of (1) loading-(2) reaction-(3) purification are preferred.

The loading temperature is preferably -30 to 350 ° C, preferably 20 to 120 ° C.

The reaction temperature is preferably 0 to 400 ° C, particularly preferably 20 to 330 ° C.

The reaction time is preferably 1 minute to 24 hours, preferably 30 minutes to 4 hours.

The reaction pressure is preferably in the atmospheric pressure range, i.e. 900 to 1100 hPa. Purification temperature becomes like this. Preferably it is 80 degreeC-400 degreeC.

Effective migration and thorough mixing of the silica and silylating agents is necessary during (1) loading step, (2) reaction step and (3) purification step. This is preferably done mechanically or by gas fluidization. Gas fluidization can be carried out with any inert gas that does not induce secondary reactions, decomposition reactions, oxidation processes and sparks and explosions. Here, the apparent gas velocity is 0.05 to 5 cm / s, particularly preferably 0.05 to 1 cm / s. Mechanical fluidization can be effected with paddle stirrers, anchor high stages, and other suitable stirring means.

In a particularly preferred embodiment, only a sufficient amount of gas is maintained to maintain an atmosphere having a low oxygen content, preferably less than 5% by volume, followed by only fluidization mechanically.

The reaction is preferably carried out in an atmosphere that does not induce oxidation of the silylated silica, ie preferably in less than 10% by volume of oxygen, particularly preferably in less than 2.5% by volume of oxygen, and in less than 1% by volume of oxygen. Best results are obtained.

The silylating agent is effectively introduced into the silica. If the silylating agent is a liquid compound at the application temperature, an effective spraying technique is preferably used. 1 nozzle spraying under pressure (5-20 bar), 2 nozzle spraying under pressure (gas and liquid, 2-20 bar), microdispensing using a grinder, and the like.

The silylating agent is added as a very finely divided aerosol, the sedimentation rate of the aerosol is preferably 0.1-20 cm / s and the droplet size having an aerodynamic equivalent diameter is 5-25 μm.

Alternatively, protic solvents such as liquid or volatile alcohols or water can be added, with the usual alcohols being isopropanol, ethanol and methanol. Mixtures of the protic solvents described above may also be added. It is preferable not to add a protic solvent.

Alternatively, acidic or basic catalysts can be preferably added. These catalysts can be basic in the sense of Lewis bases or Bronsted bases, such as ammonia, or acidic in the sense of Lewis acids or Bronsted acids, such as hydrogen chloride. If a catalyst is used, it is preferred that it is less than 1000 ppm. Particular preference is given to not adding a catalyst.

The purification step is characterized by migration, slow migration and slight mixing is preferred.

The purification step is also characterized by an increase in gas introduction corresponding to an apparent gas velocity of 0.001 to 10 cm / s.

The purification step may also include mixing by mechanical stirring means. The stirring means is preferably adjusted and operated so that mixing and flow takes place but no complete vortex occurs.

Mechanical densification methods such as, for example, press rolls, ball mills, edge mills, screw compactors and breakers can be used during the silylation step.

In addition, before the silylation step, during the silylation step or after the silylation step, by a deagglomeration method of silica, such as a pin-disk mill or mill fractionation apparatus and / or a mechanical densification method of silica, such as a press roll or a suitable vacuum method. Densification or other mechanical densification methods by sucking air or gas may be used, such as press rolls, ball mills, edge mills, screw compactors and breakers.

The preparation of the silica sintered aggregates according to the invention can also be carried out in situ in the preparation of the emulsions of the invention.

The emulsion of the present invention contains silica sintered aggregates in an amount of preferably 0.1 to 50 parts by weight, particularly preferably 1 to 15 parts by weight, in particular 2 to 10 parts by weight, based on 100 parts by weight of the total emulsion.

In the case of the emulsions of the invention, the volume fraction (Φ ₀ ) of oil phase, defined as Φ ₀ = volume of oil phase / (volume of oil phase + volume of water phase), is preferably 0.1 to 0.9, preferably 0.2 to 0.8, particularly preferred. Preferably from 0.3 to 0.7, in particular from 0.4 to 0.6.

In the case of the emulsions of the invention, the volume fraction of water (Φ _w ), defined as φ _w = volume of water phase / (volume of oil phase + volume of water phase), is preferably 0.1 to 0.9, preferably 0.2 to 0.8, in particular Preferably 0.3 to 0.7, in particular 0.4 to 0.6.

In particular, the emulsion of the present invention preferably has an average particle size, i.e., an average droplet diameter of 0.5 to 500 µm, preferably 0.7 to 100 µm, of a dispersed phase measured using laser diffraction on a laser diffraction apparatus of Sympatec, for example, by a cell measurement technique. And particularly preferably 0.7 to 50 µm, very particularly preferably 0.7 to 10 µm.

The sintered aggregate-stabilized emulsions of the present invention are particularly characterized by low viscosity. Here, the low viscosity is characterized by the relative viscosity (η _r ) of the emulsion of the present invention being 1 to 10 ⁶ , preferably 1 to 5 · 10 ⁵ , particularly preferably less than 10 ⁵ . Relative viscosity is the pure homogeneous phase measured at 25 ° C. by measuring the measured viscosity (η) at 25 ° C. using a cone-and-plate system with a shear rate of D = 10 s ⁻¹ and a measuring gap of 105 μm. It is defined as the ratio (η _rel = η / η ₀ ) divided by the viscosity (η ₀ ).

The sintered aggregate-stabilized emulsions of the present invention also have a relative viscosity (η _rel ) of emulsion, where η _rel = (1-φ / 0.74) ^{-([η] .0.74)} , where φ is the phase volume of the dispersed phase. , [η] is a form factor, in the case of the emulsion of the present invention, from 2.5 to 100, preferably from 2.5 to 50, very particularly preferably from 2.5 to 10).

Particle stabilized emulsions are distinguished in particular in that they are substantially stable against separation of the dispersed phase, ie substantially stable against creaming or sedimentation of the dispersed phase. Here, substantially stable to separation means that the volume of the reduced phase in the dispersion is less than 10%, preferably less than 5%, particularly preferably less than 1% of the total volume.

Emulsion stability was investigated using the following stability analyzer.

The invention also relates to a stability analyzer, which comprises a flat scanner having a sample holder for holding the measuring cell perpendicular to the scanner lamp, a beveled mirror reflecting the scanner's light transversely to the measuring cell and received An analysis device for analyzing light is provided.

Round glass cells having an outer diameter of 12.5 mm and a height of 50 mm are arranged in line on a flat scanner (eg, HPScanJet 3300C from Hewlett-Packard). The cell is held with a thermostat sample holder to prevent slipping (FIG. 1).

Figure 1: Thermostat Sample Holder

The sample is placed on the flat scanner parallel to the longitudinal side of the scanner, ie perpendicular to the scanner lamp (FIG. 2).

Figure 2: Design of the stability analyzer

Each sample holder has up to 21 samples, all of which can be irradiated simultaneously with 24 samples per measurement method. The image is formed by a procedure in which the light of the scanner lamp is reflected laterally on the measurement cell by an oblique mirror. At the same time, the emulsion penetrates through the bottom of the cell (thick arrow in FIG. 2). Scattered light generated by the emulsion (dashed arrow in FIG. 2) is reflected back to the sensor of the flat scanner by a mirror. The path of light can be controlled by adjusting the screw (not shown for the sake of brevity). A 2 mm thick plexiglass screen is also provided on the screen window to protect the sample from heat due to the stair lamp and to protect the scanner from contamination.

에 따라 평균을 낸다. I_av(h)는 셀의 바닥으로부터 높이 h에서 그레이 단계에 해당한다. 600 dpi를 갖는 평상 스캐너의 경우, 예컨대 도 2에 도시한 바와 같이 각각 60픽셀의 980열을 포함하는 총 산란광 강도 분포가 얻어진다.The received light is digitized by the scanner and is preferably stored on the computer in the form of a bitmap file having 256 gray levels. In order to measure the gray level, i.e. scattered light intensity, at height h from the bottom of the cell, the light intensity of 60 pixels in a row

Average according to I _av (h) corresponds to the gray level at height h from the bottom of the cell. In the case of a flat scanner having 600 dpi, for example, as shown in Fig. 2, a total scattered light intensity distribution including 980 rows of 60 pixels is obtained.

The measurement and evaluation method for 24 sample cells takes less than 2 minutes per cell, ie less than 5 seconds.

The measured scattered light intensity is now evaluated by plotting as a function of the height measured from the bottom of the cell. Measurements are made at predetermined distances to evaluate the stability of the emulsion. ΔI (z, t) = I (z, t)-I (z, 0), where I (z, t) is the scattered light intensity at height z and time t, and I (z, 0) is height z And Scattered light intensity at time 0] shows the change in scattered light intensity over time. A change in amount means higher particle scattering concentrations, indicating separation of the emulsion; Similarly, the decrease in scattered light sensitivity at a constant volume element as a function of time is the depletion of particles that can scatter at binary elements.

3 and 4 illustrate the effusion of an unstable emulsion.

A further task is a method of preparing an emulsion, in which the first step prepares a highly concentrated finely divided dispersion of the corresponding silica in the liquid forming a homogeneous phase in the emulsion, and in the second step the agent in the liquid forming a homogeneous phase in the emulsion of the invention. Preparing a highly viscous preemulsion comprising a highly concentrated finely divided dispersion of silica prepared in step 1 and a total amount of the dispersed phase (the volume of dispersion used is such that the total amount of sintered aggregated silica is present) Weigh out the remaining homogeneous phase at

The emulsification process throughout the high viscosity state, referred to hereinafter as the "rigid phase", has proven to be important in obtaining the above properties of the emulsion of the invention.

Specifically, the preparation method of the emulsion of the present invention

Preparation of a highly concentrated finely divided dispersion of the corresponding appropriate silica in the liquid forming a homogeneous phase in the emulsion of the invention.

Preparation of a highly viscous preemulsion consisting of a highly concentrated finely divided dispersion of the appropriate silica in the liquid forming a homogeneous phase in the emulsion of the invention (the volume of the dispersion used is such that the total amount of sintered aggregate silica required is present). ,

-Gradually weighing out the remaining homogeneous phase

It includes.

The preparation of highly concentrated finely divided dispersions of the appropriate suitable silica in the liquid forming a homogeneous phase in the emulsion of the invention is in principle highly sheared while stirring such as a high speed stirrer, high speed dissolver, rotor-stator system, supersonic disperser or ball mill or bead mill The means can be used according to known methods for the preparation of silica dispersions.

The concentration of the silica sintered aggregate in the dispersion is 1 to 80% by weight, preferably 10 to 60% by weight, particularly preferably 10 to 40% by weight, very particularly preferably 12 to 30% by weight.

The preparation of highly viscous preemulsions can in principle be carried out according to known emulsion preparation methods, but the methods disclosed below have been found to be particularly suitable for obtaining the emulsions of the invention.

Method 1:

First, the high concentration of silica dispersion disclosed above is introduced, the volume initially introduced containing the total amount of silica sintered aggregate required.

The total volume of the dispersed phase is slowly metered in, for example using a high speed stirrer, high speed dissolver or rotor-stator system, while homogenizing continuously.

The desired residual volume of the pure homogenous phase is then slowly metered in, optionally continuously homogenizing, for example using a high speed stirrer, high speed dissolver or rotor-stator system.

Method 2:

First, the total volume of the dispersion phase is introduced.

The above-described high concentration silica dispersion is slowly metered in, for example using a high speed stirrer, high speed dissolver or rotor-stator system, while the volume of the weighing volume contains the total amount of silica sintered aggregate required.

The desired residual volume of the pure homogenous phase is then slowly metered in, optionally continuously homogenizing, for example using a high speed stirrer, high speed dissolver or rotor-stator system.

The method can be carried out continuously or batchwise. Continuous is preferred.

The temperature of the liquid phase during the emulsification process is 0 to 80 ° C, preferably 10 to 50 ° C, particularly preferably 20 to 40 ° C.

The emulsification step can be carried out at atmospheric pressure, i.e. 900 to 1100 hPa, elevated pressure or vacuum. Atmospheric pressure is preferred.

The emulsions according to the invention can be used for all purposes for which emulsions have already been used. These are in particular organosilicon compounds such as organo (poly) silicone, organo (poly) siloxane, organo (poly) silazane and organo (poly) silcarbene; Polyolefins such as polyisobutylene terminated with silyl (such as obtainable under the trade name Epion from Kaneka Corp., Japan); Polycondensates of phthalic acid with 1,2-propanediol or polycondensates of phthalic acid, 1,2-propanediol and maleic acid, optionally dissolved in reactive diluents such as styrene; Polypropylene glycols terminated with polyurethanes, polyols such as hydroxy-containing polyesters, hydroxy-containing polyethers, methyldimethoxysilylpropyl (for example, obtainable as "MS Polymers" from Kaneka Corp., Japan) Hydroxy-containing polyacrylates; Polyisocyanates such as aliphatic and aromatic polyisocyanates, polyurethane prepolymers terminated with isocyanates (produced by excess reaction of polyols and polyisocyanates) and silyl terminated derivatives thereof (e.g. under the tradename DESMOSEAL from Bayer AG, Germany) has exist); Polyurethanes or precursors thereof such as polyetherpolyols, polyacrylatepolyols, polyesterpolyols, polyfunctional isocyanates such as hexane diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate or isocyanates provided with blocking protecting groups such as hydroxylamine or Malonic ester derivatives; (Poly) epoxy compounds such as bisphenol A based epoxides, monomers with glycidyloxy functional groups, oligomers and polymer compounds such as diglycidyl ether based bisphenol A, epoxy novolac raw materials and resins, epoxy alkyd resins, epoxy Alkylates, aliphatic epoxides such as linear alkylene bisglycidyl ethers and alicyclic glycidyl ethers such as 3,4-epoxycyclohexyl 3,4-epoxycyclohexanecarboxylate and aromatic epoxides such as p- Triglycidyl ether of aminophenol and triglycidyl ether of methylenedianiline; (Poly) amines such as cyclic and linear amines such as hexamethylenediamine, aromatic amines such as 4,4'methylenebis (2,6-diethylaniline), bis (2-aminoalkyl) polyalkylene oxide, Bis (2-aminopropyl) polypropylene glycol and zephamine, (poly) amidoamine, (poly) mercaptans, (poly) carboxylic acids, (poly) carboxylic acid anhydrides; Acrylates and esters thereof such as glycidyl acrylate, alkyl acrylates and esters thereof, methacrylates and esters thereof, polysulfide-forming polymers and polysulfides such as thioplasts (eg, Toray Thiokol Co. Waterborne coatings, adhesives and encapsulants.

Examples of epoxy compounds

Alkylene bisglycidyl ethers such as

(Wherein n is preferably 0 to 10, particularly preferably 0 to 5)

Such as bisphenol A diglycidyl ether.

Examples of epoxy novolac resins include

Of,

Difunctional epoxy compounds, such as

Trifunctional epoxy compounds, such as

Tetrafunctional epoxy compounds such as;

The emulsions of the invention can also be used for cosmetic and pharmaceutical applications, for washing and cleaning agents or for applications for changing the interfacial properties of solid and liquid substrates such as water repellents, adhesion promoters, release agents, paper coatings or foam control agents. The emulsions of the invention can also be used, for example, in the preparation of w / o / w or o / w / o multiphase emulsions or for the separation of reactive substances as controlled release systems.

Effects of the Invention

The emulsions of the invention have the advantage that they are substantially stable against separation, ie substantially stable against creaming or sedimentation of the dispersed phase.

The emulsion of the invention also has the advantage that it can be easily applied because it has a low shear viscosity.

Example 1:

Preparation of Solid Particles

100 g of pyrogenic silica having a BET specific surface area of 200 m ² / g according to DIN 66131 and DIN 66132 are fluidized with stirring and then treated and blanketed with nitrogen gas for 15 minutes and the nitrogen stream feed is stopped. 2 g of dimethyldichlorosilane are then sprayed using a 2-nozzle as an aerosol in silica fluidized at an atmospheric pressure of about 1013 hPa and a temperature of about 25 ° C. After stirring for an additional 30 minutes, the so treated silica is heated at 300 ° C. for 2 hours in an oven having a capacity of 100 l under a moderate nitrogen stream of 100 l / h.

White powdery silica is obtained having the following properties:

Silica is not fully wetted with water, but is limitedly wetted, which is the starting silica (HDK® N20), which uses Ultraturrax to incorporate only 16% by weight of silica into water to create a stable flowable material for one day but completely wetted with water. ) Is evident from the fact that 24% by weight can be incorporated under the same conditions and viscosity.

Further properties of the silica are summarized in Table 1.

characteristic Silica B1 according to Example 1 BET surface area 184 m ² / g Residual content of unsilylated silica silanol groups 80% Carbon content (% C) 0.5 wt% Methanol water 0 Contact angle for water and air (THETA) method 1 84 ° Contact angle for water and air (THETA) method 2 80 ° Surface Energy GAMMA 69 mJ / m ² Surface energy of the dispersion part GAMMA-s-D 65 mJ / m ²

-BET specific surface area is measured according to DIN 66131 and DIN 66132.

The residual content of unsilylated silica silanol groups is obtained as the ratio of the amount of silica silanol groups of the silica prepared as described above divided by the amount of silica silanol groups of the untreated starting silica; The amount of silica silanol groups is determined by acid-base titration. Method: acid-base titration of silica suspended in 50:50 water / methanol; Titration above the pH range of isoelectric point or below the dissolution pH range of silica; 100% SiOH (silica surface silanol group): Untreated silica contains SiOH-phil = 1.8 SiOH / nm ² ; Silylated silica: SiOH-silyl; Residual content of unsilyl silica silanol group; % SiOH = SiOH-silyl / SiOH-phil.100%.

Carbon content (% C) is determined by elemental carbon analysis; Combustion of the sample above 1000 ° C. in the O ₂ stream, detection and quantification of the generated CO ₂ uses IR; LECO 244 device.

Methanol number is determined as follows: wettability test (volume% of methanol in water) = methanol water (MN): the eastern blood silica is shaken with the eastern blood water-methanol mixture; Starts with 0% methanol; Silica does not float when wetting does not occur; Mixtures having a methanol content of at least 5% by volume should be used; Upon wetting, the silica precipitates; Methanol water (MN) is obtained as% of methanol in water.

Contact angle for water The THETA method 1 is measured as follows: The contact angle of the particles is carefully prepared with silica pellets by conventional methods and then digitally measured for water (in this case attached water droplets containing distilled water in the air). Obtained by measuring the contact angle.

The contact angle θ is defined as the ratio of the surface tension and the surface energy γ of the liquid l and the solid s in the gas space g: cosθ = (γ (sl) − γ (sg)) / γ (lg). Since [J] = [N · m], the surface energy (mJ / m ² ) of the solid is the same dimension as the surface tension (mN / m) of the liquid.

The contact angle for water THETA method 2 is based on the suction to a predetermined mass of a given liquid whose surface tension is known (in this case slightly densified pellets of silica with an open porosity of 0.25 and a pore radius of r) the Lucas-Washburn equation Measured by absorption method using The suction rate (dh / dt) and the height (h) of the suction liquid column are calculated from the absorption mass (m) of the liquid by the particle mass as a function of time (t), and the viscosity (η) and suction of the sucked liquid As the surface tension (γ) of the liquid, if the particle radius (r) is known, the cosine of the θ (cos (θ)) can be calculated. [Washburm, EW, Phys. Rew. 17, 273 (1921) and R. Lucas, Kolloid s. 23, 15 (1918); J. Schoelkopf et al., J. Colloid. Interf. Sci. 227, 119-131 (2000).

0: 100, 5:95, 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, 45:55, 50:50, 55:45, 60: Methanol-water mixtures having a mixing ratio (volume of methanol to volume of water) of 40, 65:35, 70:30, 75:25, 80:20, 85:15, 90:10, 95: 5, 100: 0 Use as liquid with known surface tension.

dh / dt = r γ cos (θ) / (4 η), and

h ² = r γ t t cos (θ) / (2 η)

t = Am ² (Washburn formula)

Where t is time and m is the mass of the aspirated liquid.

[Wherein η is the viscosity of the liquid, ρ is the density of the liquid, γ is the surface tension of the liquid, θ is the contact angle of the liquid-powder, and C is a factor that depends only on the geometry of the sample tube and powder. ]

The measurement method is disclosed in FIG. 5.

Surface energy (GAMMA) is a critical surface using a Zisman plot that plots each contact angle THETA of silica for a given liquid as shown in FIG. 6 as measured above by the absorption method for each contact angle. Can be measured for particles as energy GAMMA-crit.

However, liquids of different surface tension for particles such as pyrogenic silica which consist of primary particles having a material density of d _MD > 1 g / ml but form aggregates with a bulk density of d _SD << 1 g / ml Agitation into it can be used as a method, in which when no wetting occurs, the particle aggregates float, and when wet, the air in the aggregates is replaced and the particle aggregates settle.

Different liquids and different surface tensions can be used to accurately measure the surface tension of the liquid in which the particle aggregates are settled; This obtains the critical surface energy γ _crit as a measure of the surface energy γ of the particles.

This method can also be simplified by adding methanol, ethanol or isopropanol to reduce the surface tension (72.5 mN / m) of water.

Generally, water is first introduced and a certain amount of particle aggregates is floated on the surface of the water and then titrated with stirring to add alcohol. Record the water-to-alcohol ratio upon sedimentation of the particle aggregates and accurately measure the water: alcohol ratio in a separate experiment using standard methods (Wilhelmy method).

More effectively, as described herein, certain mixtures of water and methanol are prepared and then the surface tension of these mixtures is measured. In a separate experiment, these water: methanol mixtures are covered with a predetermined amount of particle aggregates (such as 1: 1 by volume) and shaken under certain conditions (such as gentle shaking by hand or using a rotary mixer for about 1 minute). do.

The water: methanol mixture in which the particle aggregates have settled and the water: methanol mixture having a high methanol content in which the particle aggregates have settled are measured. The critical surface energy γ _crit is obtained as a measure of the surface energy γ of the particles as shown in Table 1 by the surface tension of the latter methanol: water mixture.

-Measure the dispersion fraction of the surface energy (gamma-sD) using alkanes as reverse gas chromatography and probes ["Inverse Gas chromatographie [Inverse gas chromatography]"-"Characterisation of Polymers and other Materials", 391 ACS Symposium Series, DR Lloyd, Th C Ward, HP Schreiber, Chapter 18, pages 248-261, ACS, Washington DC 1989, ISBN 0-8412-1610-X.

The 16 g of partially hydrophobic silica disclosed above is predispersed in 84 g of demineralized water in a 500 ml stainless steel beaker using a dissolver equipped with a serrated disc. The highly viscous but still flowable product is pumped through the ultrasonic cell at an amplitude power of 300 watts at a flow rate of 10 ml per minute. The analytical data of the dispersion thus obtained is summarized in Table 2.

characteristic Aqueous Dispersion from Example 1 Solid content 16.1% pH 5.3 Average diameter 302 nm Sintered aggregate Viscosity 240 mPas

The solids content of the dispersion is measured by the following method: 10 g of the aqueous dispersion are mixed with the same amount of ethanol in a ceramic dish and evaporated at 150 ° C. in a N ₂ -flushed drying oven until the weight is constant. The solids content is obtained with the mass (m _s ) of the dry residue according to "solids content /% = m _s100 / 10 g".

pH is measured using a pH combination electrode.

The average diameter of the sintered aggregates is determined using photocalibration spectroscopy in the following manner: Four samples of the dispersion to be measured having a silica content of 1%, 0.75%, 0.5% and 0.25% by weight using a magnetic stirrer Prepared in demineralized water by stirring in an appropriate amount of starting dispersion. Samples are measured on Coulter's PCS apparatus Coulter N4 Plus at detection angles of 30.1 °, 62.6 ° and 90 °. The average diameter of the sintered aggregate is obtained by extrapolating the resulting angle-dependent measurements to the silica content of 0% dry weight and then averaging over three measurement angles.

The viscosity of the dispersion was measured using a Haake rheometer MCR 600 with a cone-and-plate sensor system at 25 ° C. and a shear rate of D = 10 s ⁻¹ (measurement gap of 105 μm).

The 78 g of the silica dispersion disclosed above with a solids content of 16% by weight is first introduced into a 500 ml stainless steel beaker. A 150 g viscosity 1000 mPas polydimethylsiloxane (available under the trade name "AK100" from Wacker-Chemie GmbH, Munich, Germany) is weighed slowly over 15 minutes with Ultraturrax at 10000 rpm and cooled with water. The temperature of the mixture should not exceed 60 ° C. 86 g of demineralized water are then slowly added over 100 minutes at 10000 rpm to this highly viscous stable material. The temperature of the mixture should not exceed 60 ° C. Analytical data for low viscosity white O / W emulsions is summarized in Table 3.

Example 2:

78 g of the silica dispersion according to example 1 are first introduced into 500 ml of stainless steel beakers. While stirring at 10000 rpm using Ultraturrax and cooling with water, 150 g of methyl nonaate is slowly metered in over 15 minutes. The temperature of the mixture should not exceed 60 ° C. 86 g of demineralized water are then added slowly over 15 minutes at 10000 rpm as well. The temperature of the mixture should not exceed 60 ° C. Analytical data for low viscosity white O / W emulsions is summarized in Table 3.

Example 3:

A polydimethylsiloxane of viscosity 1000 mPas (available under the trade name "OH 1000" from Wacker-Chemie GmbH, Munich, Germany) terminated with 150 g of OH is first introduced into a 500 ml stainless steel beaker. While stirring at 10000 rpm with Ultraturrax and cooling with water, 78 g of the silica dispersion obtained in Example 1 were slowly metered in over 15 minutes. The temperature of the mixture should not exceed 60 ° C. 86 g of demineralized water are then slowly added over 100 minutes at 10000 rpm to this highly viscous stable material. The temperature of the mixture should not exceed 60 ° C. Analytical data for low viscosity white O / W emulsions is summarized in Table 3.

Example 4:

78 g of the silica dispersion according to example 1 are first introduced into 500 ml of stainless steel beakers. While stirring at 10000 rpm using Ultraturrax and cooling with water, 150 g solution of 125 g epoxy resin Epikote 828 in 25 g xylene is slowly metered in over 15 minutes. The temperature of the mixture should not exceed 60 ° C. 86 g of demineralized water are then slowly added over 100 minutes at 10000 rpm to this highly viscous stable material. The temperature of the mixture should not exceed 60 ° C. Analytical data for low viscosity white O / W emulsions is summarized in Table 3.

Example 5:

5 g of partially hydrophobic silica (available under the trade name "WackerHDK H20" from Wacker-Chemie GmbH, Munich, Germany) with a plasticity of 50% and a carbon content of 1.1% were first prepared by dissolving with a toothed disc. Stir into 85 g of isododecane in a stainless steel beaker and then for 10 minutes at 10000 rpm. While stirring at 10000 rpm using Ultraturrax and cooling with water, 120 g of demineralized water is slowly metered in over 15 minutes to this highly viscous stable material. The temperature of the mixture should not exceed 60 ° C. 95 g of isododecane are then slowly added to the resulting stable material over 15 minutes at 10000 rpm. The temperature of the mixture should not exceed 60 ° C. Analytical data for low viscosity white O / W emulsions is summarized in Table 3.

Example 6:

94 g of the silica dispersion obtained in Example 1 having a solids content of 16% by weight is first introduced into a 500 ml stainless steel beaker. A 180 g viscosity 1000 mPas polydimethylsiloxane (available under the trade name "AK100" from Wacker-Chemie GmbH, Munich, Germany) is weighed slowly over 15 minutes with Ultraturrax at 10000 rpm and cooled with water. The temperature of the mixture should not exceed 60 ° C. 41 g of demineralized water are then slowly added over 15 minutes at 10000 rpm to this highly viscous stable material. The temperature of the mixture should not exceed 60 ° C. Analytical data for low viscosity white O / W emulsions is summarized in Table 3.

Claims (9)

An oil phase (phase A) containing a substantially water insoluble component or optionally a plurality of substantially water insoluble components, Aqueous phase (phase B) which may optionally further contain water-soluble components such as salts or organic compounds such as alcohols, carboxylic acids or other compounds, Arranged at the oil-water interface and partially silylated so that the content of unsilylated surface silanol groups on the silica surface is 95-5% of the starting silica (corresponding to 1.7-0.1 SiOH groups per 1 nm ^{2 of} silica surface) and dispersion Pyrogenic silica having a surface energy gamma-sD of 30 to 80 mJ / m ² and a BET specific surface area of 30 to 500 m ² / g, and -Additional substances such as pigments or preservatives A low viscosity water-in-oil (W / O) type or oil-in-water (O / W) type emulsion having an average particle size of the dispersed phase, that is, an average droplet diameter of 0.5 to 500 µm, wherein the low viscosity is the relative viscosity of the emulsion ( η _r ) is 1 to 10 ⁶ , and the relative viscosity is a value obtained by dividing the measured viscosity (η) of the emulsion measured at a shear rate of 25 ° C. and D = 10 s ⁻¹ by the viscosity (η ₀ ) of the pure homogeneous phase ( η _rel = η / η ₀ ), the relative viscosity of the emulsion (η _rel ) is defined by the formula η _rel = (1-φ / 0.74) ^{-([η] .0.74)} , where φ is the phase volume of the dispersed phase. And [η] is 2.5-100 in the case of the emulsion of the present invention as a form factor), water-in-oil (W / O) type or oil-in-water (O / W) type emulsion. 2. The emulsion of claim 1, wherein the emulsion is stable to separation of the dispersed phase, i.e., to creaming or sedimentation of the dispersed phase, wherein the separation stable phase means that the volume depleted in the dispersion is less than 10% of the total volume. In the first step a highly concentrated finely divided dispersion of the corresponding silica in the liquid forming a homogeneous phase in the emulsion, and in the second step the highly concentrated finely divided of the silica prepared in the first step of the liquid forming a homogeneous phase in the emulsion of the invention A highly viscous preemulsion is prepared comprising the dispersion and the total amount of the dispersed phase (the volume of the dispersion used is such that the total amount of silica required is present) and in the third step the residual homogeneous phase is slowly metered in. The manufacturing method of the emulsion of Claim 1 or Claim 2. As coatings, adhesives and encapsulants, as emulsions for cosmetic and pharmaceutical applications, as washing and cleaning agents or for altering interfacial properties of solid and liquid substrates such as water repellents, adhesion promoters, release agents, paper coatings or foam control agents, Use of the emulsion of claim 1 or 2 for the production of a W / O / W or O / W / O multiphase emulsion or as a controlled release system or for application to sedimentation of inert and reactive materials. A coating material, adhesive or encapsulant containing the emulsion of claim 1. A washing or cleaning agent containing the emulsion of claim 1. A water repellent, an adhesion promoter, a releasing agent, a paper coating or a foam control agent containing the emulsion of claim 1. A W / O / W or O / W / O multiphase emulsion containing the emulsion of claim 1. A flat scanner having a sample holder for holding the measuring cell perpendicular to the scanner lamp, an oblique mirror for deflecting the light of the scanner lamp transversely on the measuring cell and an evaluation device for evaluating the received light Stability analyzer.

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