DE102004029303A1 - Preparation of nanoscale titanium dioxide-dispersion, useful in e.g. lacquers, comprises acid-catalyst hydrolysis of nano-titanium dioxide in presence of polar aprotic solvent and reaction of the dispersion with alkyltrialkoxysilane - Google Patents

Abstract

Preparation of high concentrated, transparent and long term stable nanoscale titanium dioxide-dispersion (I) comprises: (a) preparing a dispersion of nano-titanium dioxide-dispersion (II) by acid catalyst hydrolysis of titanium alcoholate in presence of emulsifying agent and complex active polar aprotic solvent at room temperature; and (b) reacting (II) with alkyltrialkoxysilane for stabilization to form transparent long term stable (II). Preparation of high concentrated, transparent and long term stable nanoscale titanium dioxide-dispersion (I) with a particle size distribution (2-50 nm) comprises: (a) preparing a dispersion of nano-titanium dioxide (TiO 2)-dispersion (II) in a polar aprotic solvent by a acid catalyst hydrolysis of titanium alcoholate of formula (Ti(OR) 4) in presence of emulsifying agent and a complex active polar aprotic solvent with a E-T-N-value (0.2 (preferably greater than 0.3)) at room temperature; and (b) reacting (II) with alkyltrialkoxysilane for stabilization to form transparent long term stable (II) with a content of up to 25 (preferably 10-20) wt.% of nano-TiO 2. R : 2-4C alkyl. Independent claims are also included for: (1) a method for the processing of (I) comprising removing the solvent and isolating nano-TiO 2 powders stabilized with alkyltrialkoxysilane in the form of crystalline anatase; (2) (I) obtained by the method; (3) a shaped part comprising at least a material of at least a polymer material (preferably polyamide, polyester, copolyester, polyacrylate, polycarbonate, polyethylene, copolymer based on ethylene, polypropylene, copolymers based on polypropylene, polyvinyl chloride, polyacetate, polyketone and polyurethane) comprising nanoscale-TiO 2 or at least a material comprising a material mixture of plastics containing nanoscale-TiO 2; and (4) a foil comprising at least a layer of at least a material of plastics (preferably polyamide, polyester and copolyester, polyacrylate, polycarbonate, polyethylene, copolymer based on ethylene, polypropylene, copolymers based on polypropylene, polyvinyl chloride, polyacetate, polyketone and polyurethane) containing nanoscale-TiO 2 or a material mixture of plastics comprising nanoscale-TiO 2.

Description

The The present invention relates to those specified in the claims Object.

The invention relates in particular to highly concentrated, transparent and long-term stable nanoscale titanium dioxide dispersions, a process for preparing the nanoscale titanium dioxide dispersions, nano-TiO ₂ isolated from the dispersions as a crystalline anatase powder, and its use.

In the context of the present invention, nanoscale titanium dioxide (nano-TiO ₂ ) is titanium dioxide as anatase having a particle size of from 2 to 50 nm, preferably from 2 to 30 nm, in particular having particle sizes in the range from 2 to 15 nm or dispersion of titanium dioxide understood with the aforementioned particle size. The particle size is determined according to the invention by means of electron microscopy (TEM) and quantitative image processing.

Nano-titanium dioxide particles have been developing into valuable fillers for some time in various systems. For example, nano titanium dioxide is highly effective UV protection in sun creams and in packaging films, as high-index Component in optical plastic glasses and as a catalyst of many photochemical reactions.

The However, application of these nano-titanium dioxide particles is currently underway still restricted by that so far no fast, uncomplicated method is known the nano-titanium dioxide in the specified particle size and at room temperature highly concentrated, transparent long-term stable Dispersions available can be made. The most important methods for the synthesis of nanoparticles can be summarized under the generic term sol-gel method.

Under the sol-gel process in the narrower sense is understood as the alkoxide method, d. H. the carefully controlled, often base or acid catalyzed Hydrolysis of metal alkoxides and similar molecular precursors in Mixtures of water and one or more organic solvents. As a rule, the solvent is the same Alcohol used, which is based on the alkoxide. Disadvantage of this Procedure is that a complicated process technology required is.

Originally developed on silicon compounds, the sol-gel process is increasingly being used for the synthesis of nano-titanium dioxide according to the equation Ti (OR) ₄ + 2 H ₂ O → TiO ₂ + 4 ROH used (see, for example, literature (24) to (26)).

By appropriate choice of reaction conditions often succeeds the Synthesis of monodisperse particles, d. H. such with a very narrow particle size distribution, the diameter of the particles ranging from microns to down to a few nanometers. An example of this special reaction is working in microemulsions, which manages to limit the particle size (see z. Literature (27)).

The Working in microemulsion has the disadvantage that the space-time yield as a result of frequent low concentrations of the reactants is low and that size Amounts of water / solvent / surfactant mixtures incurred, which must be disposed of.

Out EP 0 774 443 B1 (23) is now a method for producing nanodispersed titanium dioxide is known, which is added to an alkaline liquid at elevated temperature, a sulfuric acid titanyl sulfate until the resulting mixture acidic, ie sulfuric acid in excess or an alkaline liquid and a sulfuric acid Titanyl sulphate solution at elevated temperature simultaneously with good mixing in a container such that the mixture obtained is acidic, ie sulfuric acid is present in excess, the mixture thus obtained is cooled, then a monobasic acid is added to the resulting mixture, the formed nano titanium dioxide Flake particles, these filtered off and washed.

TiO ₂ occurs in nature as rutile and anatase (rarely also brookite), and also artificial TiO ₂ is produced in these modifications.

In high-temperature pyrolysis (see, for example, references (1) to (3)) using TiCl ₄ or orthoester TiOR ₄ , rutile is stable in the low-temperature processes of the sol-gel process, usually with the alkyl orthotitanates TiOR ₄ , however, almost always disturbed nano-anatase is produced, often in poorer crystal quality.

Dispersions of nano-rutile are usually prepared by redispersion of pyrolysis-TiO ₂ powder in the ultrasound, resulting in naturally broad diameter distributions. Sometimes the direct sol-gel synthesis of nano-rutile is described (see, for example, literature (4) and (5)), but only in very dilute aqueous dispersion (≦ 1.5% by weight). Rutile was also obtained from inverse emulsion, but with aggregated, non-round particles almost in the micrometer range (see, eg, Literature (6)).

Dispersions of nano-anatase have so far been predominantly orthotitanates TiOR ₄ with sol-gel method (see, for example, literature (7) to (12)) in alcohol / water mixtures (see, for example, literature (12) to (15)) with hydrochloric, acetic or nitric acid. The most important reaction is always the acid-catalyzed hydrolysis of the titanate TiOR ₄ to the ortho acid TiOH ₄ , which proceeds rapidly. This joins the slower condensation to TiO ₂ . The TiO ₂ concentration in the dispersions is always low in the previous methods (usually <2 wt .-%).

In The nineties were often monodisperse anatase particles synthesized with diameters of 1 μm rather than micro-anatase than nano-anatase must be called (See, for example, Literature (5), (16) to (18)). Then the procedures became aligned on nano-anatase with smaller particles (diameter> 100 nm).

The anatase is the usual sol-gel processes with highly disturbed crystal structure, so that should rather be spoken of amorphous TiO ₂ . Only after hours of annealing the dispersions in an autoclave (hydrothermal process), the crystalline anatase or rutile develops (see, for example, literature (19) and (20)). The crystallization increases the refractive index, but is unfortunately associated with aggregation.

Also in anhydrous organic media can be formed by solvolysis TiO ₂ (solvothermal method), but only in lengthy reactions in an autoclave (see, for example, literature (21)).

In addition to the sol-gel process, a gel-sol process has been developed with which nano-TiO ₂ in aqueous dispersion can be prepared not only in more or less spherical form but also in spindle form (see, for example, Literatur (20 )). Disadvantages are the low TiO ₂ concentration (≤ 4 wt .-%) and long tempering steps of a few days.

In order to control the rapid hydrolysis of the orthotitanates TiOR ₄ , a carefully metered addition of water and complexing ligands (such as acetylacetone) were used (see, for example, references (12) and (22)).

The processes described hitherto in the literature for the preparation of nano-TiO ₂ have one or more of the following disadvantages: complicated production methods, long reaction times at often high temperatures in sometimes unpleasant reagents and dispersants (for example acetic or nitric acid), nonuniform nano- TiO ₂ particles in often low concentrations and gelling of the dispersion.

Therefore, it has been desired to produce concentrated, long-term stable nano-TiO ₂ sols with low cost, good quality processes. Furthermore, the object of the present invention comprises the isolation of redispersible, non-aggregated to the sol nano-TiO ₂ particles in powder form. The nano-TiO ₂ particles should be so small that they do not diminish transparency when dispersed in a polymeric matrix.

This object is achieved according to the invention by the process according to claim 1, according to which the preparation of highly concentrated, transparent and long-term stable nanoscale titanium dioxide dispersions having a particle size distribution of between 2 and 50 nm and a content of up to 25 wt .-% of nano Titanium dioxide (a) an acid-catalyzed hydrolysis of titanium alkoxide Ti (OR) ₄ , whose alkyl radicals R contain 2 to 4 carbon atoms, at room temperature in the presence of an emulsifier and a complexing polar aprotic solvent having an E _T ^N value greater than 0.2, preferably greater than 0.25 and particularly preferably greater than 0.3 is carried out, so that a dispersion of nano-TiO ₂ particles is formed in the polar aprotic solvent and (b) the TiO ₂ dispersion is stabilized with alkyltrialkoxysilanes, so that a Transparent long-term stable nano-TiO ₂ dispersion containing up to 25 wt .-% nano-TiO ₂ is created. Preference is given to nano-TiO ₂ dispersion having a content of 5 to 25 wt .-% and particularly preferably with a content of 10 to 20 wt .-% nano-TiO ₂ prepared.

The invention therefore relates to a fast, uncomplicated process which leads to concentrated, transparent and long-term stable dispersions of nanoparticles of TiO ₂ having diameters <50 nm both at low temperatures (room temperature) and at 70 ° C. (see 1 ). The dispersant used is preferably dimethylacetamide (DMAc), which can be loaded with up to 25% by weight of nano-TiO ₂ . The dispersing agent, in particular DMAc, complexes both the Ti species which are intermediately formed during the precipitation process and the TiO ₂ particles which form. In order to be able to produce in particular stable, highly concentrated nano-TiO ₂ sols, the water concentration must be kept low. It may only be insignificantly above the stoichiometric amount (2 moles of water per mole of Ti ⁴⁺ ). The nano-TiO ₂ particles are protected according to the invention with alkyltrialkoxysilanes, which is why the dispersions at room temperature for months, ie at least remain transparent for up to 6 months.

The nano-TiO _{2 is} isolated from the DMAc dispersions as a white anatase powder which can be redispersed in lower alcohols, such as, for example, ethanol or isopropanol, again giving transparent nano-TiO ₂ dispersions which are almost unchanged from the original TiO ₂ particles exist. Particle enlargement of the nano-TiO ₂ particles caused by the processes isolation and redispersion occurs only to a minor extent.

If the nano-TiO ₂ dispersions are mixed with thermoplastics, for example polyamides, polyesters, polycarbonates or polyacrylates, and dried, transparent nano-TiO ₂ -containing thermoplastics with an increased refractive index are formed, in which the nano-TiO ₂ particles are homogeneously distributed present (see 2 ). The refractive index of the nano-TiO ₂ filled thermoplastics corresponds to the expected volume average of the component indices.

Depending on the nature of the polymers, the isolated nano-titanium dioxide particles or the nano-TiO ₂ dispersions can be introduced into the polymeric matrix by extrusion, in situ polymerization or by cast film technique. Since no further aggregation of the nano-particles occurs, transparent polymers are still transparent even with a high proportion (> 50% by weight) of nano-titanium dioxide particles.

The nano-TiO ₂ dispersions or nano-TiO ₂ (as white anatase powder) produced can be used in plastics, coatings and paints to influence the refractive index (n D 20) by up to 0.2 units and the Abbe number be used. The plastics can be selected from the group of thermosetting plastics and thermoplastics. According to the invention, the thermoplastics may be selected from the group of polyamides, polyesters and copolyesters, polyacrylates, polycarbonates, polyethylenes, ethylene-based copolymers, polypropylene, polypropylene-based copolymers, polyvinyl chloride, polyacetates, polyketones and polyurethanes be selected.

Out the plastics or from the material mixtures of the aforementioned Plastics that contain the nanoscale titanium dioxide can also form parts and films comprising at least one layer of a material the aforementioned group of plastics or mixtures of materials made from the aforementioned plastics.

The invention therefore relates to a process for the preparation of highly concentrated, transparent and long-term stable nanoscale titanium dioxide dispersions having a particle size distribution of between 2 and 50 nm, with a content of up to 25 wt .-% of nano-titanium dioxide, wherein (a) a acid-catalyzed hydrolysis of titanium alkoxide Ti (OR) ₄ , whose alkyl radicals R contain 2 to 4 carbon atoms, at least at room temperature or else at elevated temperature and in the presence of an emulsifier and a complexing polar aprotic solvent having an E _T ^N value greater than 0, 2, preferably greater than 0.25 and particularly preferably greater than 0.3, so that a dispersion of nano-TiO ₂ particles is formed in the polar aprotic solvent and (b) the TiO ₂ dispersion with alkyltrialkoxysilanes for stabilizing the TiO ₂ - Particles so that a transparent long-term stable nano-TiO ₂ dispersion with a content of up to 25 Wt .-% nano-TiO _{2 is} obtained.

In step (a), the procedure is to initially add the emulsifier, preferably a cationic emulsifier dissolved in a solvent such as dimethylacetamide, with hydrochloric acid, dilute with water and mix. However, according to the invention it is also possible to use anionic emulsifiers or nonionic emulsifiers. However, preferred is a cationic emulsifier such as dodecyltrimethylammonium bromide. After cooling this solution, the titanium alkoxide Ti (OR) ₄ , in particular tetrapropyl orthotitanate, dispersed in an aprotic polar solvent, is then added as rapidly as possible. If the orthotitanate dispersion is not added quickly but slowly added dropwise, larger nano-particles with a diameter of up to 50 nm are formed. At an addition time significantly longer than 30 minutes there is a risk of further aggregation, whereby particles larger than 50 nm can be formed.

In particular, according to the invention Dimethylacetamide used as aprotic polar solvent. The Orthotitanate swells in dimethylacetamide but does not dissolve immediately completely on, so that a dispersion arises. After stirring this completely clarified and then consists of nano-titanium dioxide particles. By adding Alkyltrialkoxysilanes, in particular of 3-methacryloyltrimethylsiloxane then the titanium dioxide is stabilized. This dispersion is over months stable. Surprisingly could according to the invention a dispersion be prepared with up to 25 wt .-% nanoscale titanium dioxide, the thin, colorless and over remained stable for several months.

According to the invention, the polar aprotic solvent used is one having an E _T ^N value of greater than 0.2, preferably greater than 0.25 and particularly preferably greater than 0.3.

For the definition of E _T ^N values, reference is made to Ch. Reichert, Solvents and Solvent Effects in Organic Chemistry, page 363, f.

With the dispersion media otherwise customary in the prior art, such as acetic acid, nitric acid or alcohol / water mixtures, only dilute nano-TiO ₂ dispersions can be prepared (<4% by weight of TiO ₂ ).

According to the invention suitable polar aprotic solvents are N, N-disubstituted amides, nitroalkanes, nitriles, sulfoxides, sulfones. They have E _T ^N values in the range of 0.3 to 0.5. The most important polar aprotic solvents used according to the invention are acetone, acetonitrile, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, hexamethylphosphoric triamide. Very particular preference is given to using dimethylacetamide according to the invention.

The acid used in sol preparation, for example, concentrated hydrochloric acid, stabilizes the Ti (OH) _x species during formation of the nanoscale titanium dioxide particles. Due to the influence of the acid concentration on the solubility of the various Ti species and the particle size of the titanium dioxide formed according to the invention at a pH of 4 or less, preferably from 2 or less, and more preferably in a pH range from 1.5 to 2 worked.

Of Another is according to the invention to make sure that the total water concentration in sol production only a little over the stoichiometric amount (in relation to titanium) may lie. According to the invention with an amount of water worked, which is the 1.0 to a maximum of 1.5 times the stoichiometric amount equivalent.

Finally, in the process according to the invention, the resulting nano-TiO _{2 is} stabilized by means of alkantrialkoxysilane. Such silanes have the following general formula (I) or derivatives thereof: (R ₁ ) _m -Si (OR ₂ ) _n (I), wherein R _{1 represents} a substituted or unsubstituted alkyl or aryl group, R _{2 represents} identical or different, substituted or unsubstituted alkyl or acyl groups, m is zero or an integer from 1 to 3 and n is an integer from 1 to 4, with the proviso that the sum of m and n is 4.

Especially preferred compounds of the formula (I) contain an acryloyl or a methacryloyl group and are especially 3-acryloxypropyltrimethylsiloxane and / or 3-methacryloxypropyltrimethoxysilane.

The Amount of alkantrialkoxysilane used is such that approximately a monomolecular coverage of the nano-titanium dioxide particle surface takes place.

• – eine hohe nano-TiO₂-Konzentration im Sol,
• – aggregatfreie nano-TiO₂-Partikel, die optisch „unsichtbar" sind,
• – nano-TiO₂-Pulver, welches in den erfindungsgemässen, polar aprotischen Lösungsmitteln mit einem E_T ^N-Wert von grösser 0,2 sowie in Alkoholen redispergierbar ist und unter 100°C auch in Polymere einextrudiert werden kann.
• – Das erfindungsgemäße TiO₂-Pulver besteht aus nano-Anatas mit Gitterstörungen, nicht aber aus amorphem TiO₂.

Advantages of the invention are:

• A high nano-TiO ₂ concentration in the sol,
• - aggregate-free nano-TiO ₂ particles that are optically "invisible",
• Nano-TiO ₂ powder which is redispersible in the polar aprotic solvents according to the invention with an E _T ^N value of greater than 0.2 and in alcohols and which can also be extruded into polymers at 100 ° C.
• The TiO ₂ powder according to the invention consists of nano-anatase with lattice defects, but not of amorphous TiO ₂ .

The Invention will now be apparent from the following examples and the figures explained in more detail, without but to limit these to it.

1 shows a transmission electron micrograph of nano-TiO ₂ particles according to the invention, deposited from dimethylacetamide dispersion; the white spots show nano-TiO ₂ particles shot by the electron beam;

2 shows a transmission electron micrograph of a polyamide film of an amorphous polyamide: Trogamid-T poly (trimethylhexamethylene terephthalamide) (TMDT)), the company Degussa AG, Germany;

example 1

Preparation of a 15 wt .-% TiO ₂ dispersion in dimethylacetamide (according to the invention).

0.5 g of the cationic emulsifier dodecyltrimethylammonium bromide dissolved in 30 g of dimethylacetamide (DMAc) are mixed with 9 g of concentrated hydrochloric acid (HCl, 37% by weight) diluted with 9 g of water with stirring. After cooling this solution, a dispersion of 110 g of tetrapropyl orthotitanate (TPOT, molecular weight 284 g / mol) in 50 g of DMAc is added over 2 minutes. The orthotitanate swells in DMAc, but does not dissolve completely, creating a turbid dispersion. It clears completely after 45 minutes of stirring and then consists of nano-TiO ₂ particles with diameters of 4 to 13 nm (predominantly 5 to 11 nm, see 1 ). Particle size determination was done by electron microscopy (TEM) and quantitative image processing.

In this state, the dispersion turns into a yellowish gel after days. Therefore, the finished TiO ₂ dispersion is immediately mixed with 7 g of 3-methacryloyltrimethoxysilane (MPS), which is fixed after stirring for 30 min at room temperature and 30 min at 70 ° C on the TiO ₂ surface. The thus stabilized dispersion is stable for months, it remains thin and colorless. Even when heated to 80 ° C this condition is maintained over several hours.

Example 2

Preparation of crystalline nano-TiO ₂ powder (anatase) (according to the invention).

The TiO ₂ dispersion prepared in Example 1 is placed in a rotary evaporator at 75 ° C (under gradually reduced pressure (400 to 15 mbar)), the solvent is removed and nano-TiO ₂ is isolated as a white powder (crystalline anatase).

The nanodisperse TiO ₂ has a particle size distribution of between 1 and 30 nm (determined by electron microscopy (TEM) and quantitative image processing) and a transparency of at least 99% (measured in a 5 wt .-% aqueous hydrochloric acid solution between 400 and 700 nm at 180 ° / d geometry in a layer thickness of 10 microns).

Example 3

Production of a polyamide film containing nano-TiO ₂ powder (according to the invention).

150 g of nano-TiO ₂ powder are dispersed in 500 ml of methanol or alternatively ethanol or alternatively isopropanol in an ultrasonic bath for 15 min. The result is a transparent, thin, almost colorless dispersion that is stable for weeks.

The abovementioned TiO ₂ dispersion can be mixed with thermoplastics such as, for example, amorphous polyamide, for example a polyamide 6I / 6T (70:30) (Grivory G21 from EMS-Chemie AG, Domat / Ems, CH) or a polyamide TMDT (trogamide Degussa AG, Dusseldorf), dried and a film are produced (see 2 ).

The refractive index of the nano-TiO ₂ filled thermoplastics corresponds to the expected volume average of the component indices. At a filling level of about 50 wt .-%, a refractive index of 1.70 is achieved.

Example 4

Producing a PMMA film containing nano-TiO ₂ particles.

Depending 4g, 3g, 2g or 1g of polymethyl methacrylate (PMMA) (Plexiglas ^® 7N of Messrs. Rohm, Darmstadt) dissolved in 15 ml THF, are ₂ to a dispersion of 1 g TiO in 10 ml DMAc poured. After casting and drying, a transparent film is obtained which contains 20% by weight, 25% by weight, 33% by weight and 50% by weight of nano-TiO ₂ particles without aggregation.

Comparative experiment 1

Similar to Example 1, a TiO ₂ dispersion should be obtained, but instead of the dispersant, dimethylacetamide used ethanol. The tetrapropyl orthotitanate reacted immediately to nano-TiO ₂ , which precipitates after the addition as a white precipitate and gives no stable dispersion. Also, no high concentrations of nano-TiO ₂ in the solution (<5 wt .-%) can be stably maintained for a long time.

literature

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Claims (14)

Process for the preparation of highly concentrated, transparent and long-term stable nanoscale titanium dioxide dispersions having a particle size distribution of between 2 and 50 nm, characterized in that (a) an acid-catalyzed hydrolysis of titanium alkoxide Ti (OR) ₄ , whose alkyl radicals R contain 2 to 4 carbon atoms, at room temperature in the presence of an emulsifier and a complexing acting polar aprotic solvent having an E _T ^N value of greater than 0.2, preferably greater than 0.25 and particularly preferably greater than 0.3, is performed, so that a dispersion of nano -TiO ₂ particles in the polar aprotic solvent is formed, and (b) the TiO ₂ dispersion is stabilized with alkyltrialkoxysilanes, so that a transparent long-term stable nano-TiO ₂ dispersion containing up to 25 wt .-% nano-TiO ₂ , preferably with a content of 5 to 25 wt .-% nano-TiO ₂ , particularly preferably with a content of 10 to 20 wt .-% nano-TiO ₂ , is obtained. Method according to claim 1, characterized in that in step (a) a pH of 4 or smaller, preferably set by 2 or less. Method according to claim 1 or 2, characterized in that in step (a) to a maximum 1.5 times the titanium-related stoichiometric demand for water is used. Method according to one of the preceding claims 1 to 3, characterized in that an emulsifier as emulsifier from the group of cationic emulsifiers, anionic emulsifiers or the nonionic emulsifiers is used, wherein a cationic Emulsifier, more preferably dodecyltrimethylammonium bromide in Step (a) is used. Method according to one of the preceding claims 1 to 4, characterized in that as a polar aprotic solvent Dimethylacetamide is used. Process according to any one of the preceding claims 1 to 5, characterized in that the nano-titania particles are stabilized in step (b) with alkyltrialkoxysilanes represented by the following general formula (I) and derivatives thereof: (R ₁ ) _m -Si (OR ₂ ) _n (I) wherein R _{1 represents} a substituted or unsubstituted alkyl or aryl group, R _{2 represents} identical or different, substituted or unsubstituted alkyl or acyl groups, m is zero or an integer from 1 to 3 and n is an integer from 1 to 4, with the proviso that the sum of m and n is 4. Method according to claim 6, characterized in that the compound according to formula (I) a compound having an acryloyl or methacryloyl group wherein is 3-acryloxypropyltrimethoxysilane and / or 3-methacryloxypropyltrimethoxysilane are preferred. Method according to one of the preceding claims 1 to 7, characterized in that is used as the titanium alkoxide Ti (OR) ₄ tetrapropylorthotitanate. A method for further processing according to the method according to the claims 1 to 8 obtained nanoscale titanium dioxide dispersions, characterized that the solvent removed and nano-titania powder in the form of crystalline anatase, stabilized with alkyltrialkoxysilanes, is isolated. Highly concentrated, transparent and long-term stable nanoscale titanium dioxide dispersion having an average particle size distribution of between 2 and 50 nm, with a nano titanium dioxide content of up to 25% by weight, preferably from 5 to 25% by weight, particularly preferably from 10 to 20% by weight, obtainable by the process according to one or more of claims 1 to 8. Use of the nanoscale titanium dioxide according to claim 9 in plastics, coatings and paints. Use according to claim 11, characterized in that the plastics are selected from the group of thermosetting plastics and the thermoplastic Plastics, in particular from the group of polyamides, the polyester and copolyesters, polyacrylates, polycarbonates, polyethylenes, the ethylene-based copolymers, polypropylene, on polypropylene based copolymers, polyvinyl chlorides, polyacetates, polyketones and the polyurethanes. Molding, which at least partially from at least a material made of a polymeric material, in particular from Group of polyamides, polyesters and copolyesters, polyacrylates, polyethylenes, ethylene-based copolymers, polypropylenes, polypropylene-based copolymers, polyvinyl chlorides, polyacetates, polycarbonates, polyketones, and polyurethanes, containing nanoscale titanium dioxide according to claim 9, or at least from a material containing a material mixture of the aforementioned Plastics containing nanoscale titanium dioxide according to claim 9, contains. Film comprising at least one layer of at least a material from the group of plastics, in particular from the group of polyamides, polyesters and copolyesters, polyacrylates, polyethylenes, ethylene-based copolymers, polypropylenes, polypropylene-based copolymers, polyvinyl chlorides, polyacetates, polycarbonates, polyketones, and polyurethanes, containing nanoscale titanium dioxide according to claim 9, or a material mixture from one of the aforementioned plastics containing nanoscale Titanium dioxide according to claim 9, contains.