JP2009529613A - Titanium dioxide pigment coated with hollow body and method for producing the same - Google Patents

Abstract

The present invention relates to coated titanium dioxide pigments having good opacity as well as good yield for use in decorative paper, as well as a process for the production thereof. This pigment is characterized by a surface coating comprising a hollow body combined with aluminum oxide phosphate. This production method is characterized by first adding an aluminum component and a phosphorus component to the TiO ₂ suspension while not reducing the pH value below 10. The hollow body is subsequently added, followed by the addition of at least one acidic component, which reduces the pH value of the suspension to the range of 4-9. In an alternative method implementation, the suspension has a pH value of less than 4 upon addition of the aluminum component and the phosphorus component.

Description

The present invention relates to a pigment of titanium dioxide having a high opacity, a process for its production, and its use in decorative paper or decorative film.

TECHNICAL BACKGROUND OF THE INVENTION Decorative paper, or decorative film, is a component of a decorative thermosetting coating material that is preferably used in furniture surface improvement, laminate flooring, and interior finishing. Laminate means, for example, a plurality of impregnated papers laminated together, or a layered press material in which paper and hard fiberboard or wood particleboard are pressed together. By using a special synthetic resin, the very high scratch strength, impact strength, chemical resistance and heat resistance of the laminate can be obtained.

  The use of decorative paper (hereinafter decorative paper should always be understood as decorative film) allows the production of decorative surfaces, in which case the decorative paper is a coating for an unattractive wood material surface, for example. It serves not only as a paper but also as a carrier for synthetic resin.

  Among the demands placed on decorative paper are opacity (hiding power), light fastness (Vergraungsstabitalet), color fastness, wet strength, impregnability and printability.

  The economics of the decorative paper manufacturing method are determined, among other things, by the opacity of the pigments in the paper. In order to achieve the required decorative paper opacity, titanium dioxide-based pigments are in principle very suitable. In the production of paper, a titanium dioxide pigment or a suspension of titanium dioxide pigment is usually mixed with a suspension of pulp. In addition to the pigments and pulp that are the raw materials used, auxiliaries such as wet strength agents and in some cases further additives are also generally used. The interaction of each component (pulp, pigment, auxiliaries and additives, water) contributes to the formation of the paper and determines the pigment yield. Yield is understood as the ability to hold all inorganic substances in the paper during manufacture.

  It is known that improved opacity can be achieved by special surface treatments in titanium dioxide pigments.

  In US 5,942,281A and US 5,665,466 A, a first layer of aluminum oxide phosphate is applied at an acidic pH value of 4-6 and a second layer of aluminum oxide is 3-10. A surface treatment is described that precipitates in the pH range, preferably about pH 7. Since the improvement in yield is achieved by a third layer consisting of magnesium oxide, the pigments produced are characterized by mutually continuous layers of aluminum oxide phosphate, aluminum oxide and magnesium oxide.

US 6,962,622 describes a pigment having a high gray resistance (pigment type A), a pigment having an enhanced SiO ₂ content and an Al ₂ O ₃ content in a flake-like precipitate (pigment type). Disclosed is a titanium dioxide-pigment mixture composed of B).

  US Pat. No. 6,143,064A describes coating of pigment particles with precipitated calcium carbonate, wherein the calcium carbonate particles are 30-100 nm in size. Titanium dioxide coated with calcium carbonate achieves higher opacity in paper. Since the calcium particles are responsible for the spacer function in this case, the pigment particles have a better dispersion in the paper. The minimum distance between the pigment particles substantially corresponds to the pigment particle size.

US 5,886,069A and US 5,650,002 describe TiO ₂ pigment particles which also have a coating consisting of inorganic individual particles (Einzelpartikel) having a diameter of 5 to 100 nm as well as a continuous inorganic coating. ing. The order of surface coating is arbitrary, as is the morphology of the individual particles. This production is carried out by mixing a colloidal suspension of individual particles with a slurry of TiO ₂ .

  US 2003 0024437 A1 discloses a pigment mixture having pigment particles on the surface on which particles in spherical form, for example calcium carbonate, silicon oxide, aluminum oxide, zircon oxide or titanium oxide, are deposited in situ.

Problem setting and overview of the present invention The object of the present invention is to provide an alternative titanium dioxide pigment having good opacity for use in decorative paper, as well as good yield. A further object of the present invention is to provide a method for producing such a titanium dioxide pigment.

  This problem is solved by a pigment of titanium dioxide containing titanium dioxide particles in which a layer comprising aluminum phosphate, aluminum oxide and hollow bodies is present on the particle surface.

This challenge is further
a) Preparation of an aqueous suspension of uncoated titanium dioxide particles b) Addition of aluminum component and phosphorus component c) Addition of hollow body d) pH value of suspension to a value in the range of about 4-9 It is solved by a method for producing a coated titanium dioxide pigment, which comprises the step of conditioning.

  Further advantageous variants of the invention are described in the dependent claims.

DESCRIPTION OF THE INVENTION Here and hereinafter, “oxide” is to be understood as the corresponding hydrous oxide or hydrate. It is understood that all subsequent disclosures relating to pH values, temperatures, concentrations in mass% or volume%, etc. include all values within the respective measurement accuracy ranges known to those skilled in the art. It should be. In the scope of the present application, the expression “significant amount” or “significant proportion” means the smallest amount of a component that affects the properties of the mixture within the range of measurement accuracy.

  The titanium dioxide pigments according to the invention are characterized by the use of hollow bodies. The hollow body includes a hollow sphere, a micro hollow body, and a micro hollow sphere. The hollow body is used in the post-treatment according to the present invention. The hollow body is deposited on the particle surface and acts as a spacer between the individual pigment particles. The hollow body may be inorganic and organic in nature. The hollow body preferably has an average diameter of 5 to 1000 nm. Hollow bodies are characterized by air uptake, where air uptake may only be present after drying of the pigment.

Organic hollow bodies are used, for example, as fillers in paints. The hollow body acts as a spacer between the pigment particles and takes advantage of the favorable refractive index difference between the pigment and air due to its air uptake, leading to a higher hiding power (“Qualitatsverbesserung RopaqueTM Polymer zur Qualitaetsverbersserundck” Farben "Phaenomen Farbe 2/98, 1/99). For the production of organic hollow bodies, the publication “Hollow Latex particles: synthesis and applications” (McDonald et al., Advances in Colloid and Interface Science 99 (2002) 181 to 213) is outlined. The production of inorganic hollow spheres is typically described in “Nanoengineering of Inorganic and Hybrid Hollow Spheres by Colloidal Templating” (Caruso et al., Science 1998, 282, 1111). WO 02/074431 A1 discloses the production of inorganic hollow bodies and their application in catalysis or photonics.

In the process according to the invention, a layer of an aluminum-phosphorus compound is deposited on the surface of the TiO ₂ particles in a mixture with a hollow body and optionally in a mixture with aluminum oxide. The composition depends on the amount of aluminum and phosphorus components used. Hereinafter, this layer is simply referred to as an aluminum oxide phosphate-hollow sphere layer.

The post-treatment method that forms the basis of the present invention starts from a suspension of aqueous and preferably wet-ground TiO ₂ (step a). Wet grinding is optionally carried out in the presence of a dispersant. TiO ₂ is an uncoated particle of TiO ₂ , that is, a particle of a TiO ₂ base (Grundkoper) produced according to the sulfuric acid method (SP) or the chlorine method (CP). In the CP method, the addition of aluminum in an amount of 0.3 to ₃ % by weight, calculated as Al ₂ O ₃ , and the oxygen excess of 2% to 15% in the gas phase in the oxidation of titanium tetrachloride to titanium dioxide. The base body is usually stabilized by the addition of and in the SP method, for example by doping with Al, Sb, Nb or Zn.

Preferably, TiO ₂ particles produced according to the chlorine method are used. This process is carried out at a temperature below 80 ° C., preferably at 55 ° C. to 65 ° C.

  The suspension can be adjusted in step a) to be either alkaline or acidic and preferably has a pH value of more than 9 or a pH value of less than 4.

In step b), an aluminum component and a phosphorus component are added. Suitable aluminum components for the surface treatment method according to the present invention are alkaline or acidic reactive water-soluble salts such as sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum chloride, aluminum acetate and the like. This choice should not be understood as a limitation. Aluminum components, calculated as Al ₂ O _3, and in an amount of 1.0 to 5.0 wt% with respect to TiO ₂ particles, preferably 1.5 to 4.5 wt%, especially 2.0 It is desirable to add by mass%.

Suitable phosphorus components are inorganic compounds such as alkali phosphates, ammonium phosphates, polyphosphates, phosphoric acid and the like. This choice should not be understood as a limitation. Particularly suitable is disodium hydrogen phosphate or phosphoric acid. The phosphorus component is calculated as P ₂ O _{5 and} is 1.0 to 5.0% by mass, preferably 1.5 to 4.0% by mass, particularly 2.0 to 3.0% by mass with respect to the TiO ₂ particles. Add in concentration.

  The Al component and the P component can be added to the suspension individually in any order, either sequentially or simultaneously.

  In the subsequent step c), an organic or inorganic hollow body having an average diameter of 5 to 1000 nm, preferably 400 to 600 nm, is added.

  As the organic hollow sphere, for example, a product of Rohm & Haas, Ropaque (registered trademark) is considered. Ropaque (R) is a styrene / acrylic copolymer hollow sphere. Other latex hollow spheres or polymeric hollow spheres are also suitable. However, this listing should not be understood as a limitation of the invention. Rather, in principle, all organic hollow bodies having a required particle diameter in the range of 5 to 1000 nm and stable at the generated pH value are considered.

As inorganic hollow bodies, glass hollow spheres and ceramic hollow spheres are generally described in the prior art, and individually described are TiO ₂ hollow spheres. Here too, all kinds of inorganic hollow bodies can basically be used within the scope of the present invention as long as they have the required average particle diameter of 5 to 1000 nm and are stable at the pH value generated. is there. One skilled in the art can select an appropriate hollow body for reasons of application conditions such as processability and cost.

The hollow body is added in an amount of 1 to 15% by weight with respect to the uncoated TiO ₂ particles.

  In a further subsequent step d), the pH value of the suspension is adjusted to a value in the range of 4-9 by the addition of a component for adjusting the pH value. The component that adjusts the pH value used may be an acid or alkaline solution. As acid, for example, sulfuric acid, hydrochloric acid, phosphoric acid, or other suitable acids can be used. Furthermore, instead of acids, the corresponding acidic reactive salts, such as aluminum sulfate, can be used. Furthermore, it is also possible to use acidic metal salt solutions, for example cerium, titanium or zircon acid metal salt solutions, so that the deposition takes place together with a layer of aluminum oxide phosphate hollow spheres. As the alkaline solution, a sodium hydroxide solution is preferably used. Alkaline reactive salts are also suitable. Those skilled in the art know compounds that adjust the appropriate pH value. This choice should therefore not be understood as a limitation of the present invention.

In a subsequent subsequent step e), a layer of aluminum oxide on the aluminum oxide phosphate-hollow sphere layer is obtained by parallel addition of an alkaline aluminum component and an acidic aluminum component (eg sodium aluminate / aluminum sulfate). Or by adding an alkaline aluminum component, such as sodium aluminate and an acid, such as sulfuric acid or hydrochloric acid, or by adding an alkaline solution, such as NaOH, together with an acidic aluminum component, such as aluminum sulfate, to maintain the pH value in the range of 4-9. Application has proven advantageous. In this case, these components can be added so that the pH value always remains in the range of 4 to 9. Alternatively, these components are added in combination such that the pH value changes within the pH value range 4-9 during the addition. This method is known to those skilled in the art. For adjusting the pH value, for example, alkaline solutions or acids (for example (NaOH / H ₂ SO ₄ ), or alkaline or acidic reactive salt solutions (for example sodium aluminate / aluminum sulfate) are suitable, step d). It has proved particularly advantageous to carry out the treatment at a pH value adjusted in.

Subsequent adjustment of the pH value to 5-8 in step f), if necessary, for example in alkaline solution / acid (eg NaOH / H ₂ SO ₄ or HCL) or alkaline / acid salt solution, eg sodium aluminate / sulfuric acid Perform using aluminum.

Step d), e), the amount of and f) aluminum compounds used in may be calculated as Al ₂ O _3, shall be included already in step b) the amount of Al ₂ O ₃ is used in. The total amount of aluminum compounds used in steps b) to f) is ideally 1.0 to 9.0% by weight, preferably 1.0 to 9.0% by weight, based on uncoated TiO ₂ particles calculated as Al ₂ O ₃ Is 3.5 to 7.5% by mass, especially 5.5% by mass. The amount of the phosphorus component used in step d) and e) optionally likewise calculated as P ₂ O _5, it can be included in the P ₂ O ₅ used in step b). The total amount of phosphorus compounds used in steps b) to e) is calculated as P ₂ O _{5 and} is ideally 1.0 to 5.0% by weight with respect to the uncoated TiO ₂ particles, preferably Is from 1.5 to 3.5% by weight, and in particular from 2.0 to 3.0% by weight.

  Additional metal salt solutions such as Ce, Ti, Si, Zr or Zn metal salt solutions can also be added to the suspension in step b) together with the Al component and the P component, and these metal salt solutions are subsequently added to the step. In d), together with aluminum oxide phosphate-hollow spheres, the sulfate or oxide in the layer is deposited and deposited on the particle surface. Furthermore, it is possible to apply further organic layers before or after step e), which organic layers are known from the prior art (eg Zn-containing compounds, Ti-containing compounds, Si-containing compounds). .

In a preferred embodiment of the process according to the invention, one starts from an alkaline TiO ₂ suspension. For this, in step a) the suspension is first adjusted to a pH value of at least 10 with a suitable alkaline compound, for example NaOH. This is ideally done before grinding if wet grinding is performed.

  Subsequently in step b), the aluminum component and the phosphorus component are each added to the suspension in the form of an aqueous solution. During the addition of the components, the pH value of the suspension is kept at least 10, suitably at least 10.5 and particularly preferably at least 11.

  Particularly suitable as the alkaline aluminum component is sodium aluminate. In the case of an acidic reactive compound, such as aluminum sulfate, which will reduce the pH value to less than 10 upon addition, it is advantageous to compensate for this effect by the addition of a suitable alkaline compound, such as NaOH. Proved. Suitable alkaline compounds for maintaining the pH value of at least 10 and the necessary amounts are well known to those skilled in the art.

  In the case of phosphorus components, if the pH value drops below 10 upon their addition, it has proved equally advantageous to compensate for this effect by the addition of a suitable alkaline compound, for example NaOH. Appropriate alkaline compounds to keep the pH value at least 10 and the required amounts are routine for those skilled in the art.

  The Al component and the P component can be added to the suspension sequentially or simultaneously in any order.

  In the next step c), an organic hollow body or an inorganic hollow body having an average diameter of 5 to 1000 nm, preferably 400 to 600 nm, is added, the pH value of the suspension being less than 10, preferably 10. It does not drop below 5, especially below 11.

  In the next step d), a component for adjusting the pH value is added so that the pH value is adjusted in the range of 4-9.

  In an alternative embodiment of the method according to the invention, the surface treatment according to the invention is started from a range of acidic pH values.

  In this case, in step b), an aluminum component and a phosphorus component are added so that the pH value of the suspension is still less than 4. The person skilled in the art knows whether to reduce the pH value with an appropriate acid already in step a) or to reduce the pH value to less than 4 with the appropriate combination of ingredients in step b), possibly with addition of acid It is up to you. For example, a combination of phosphoric acid / sodium aluminate or disodium hydrogen phosphate / aluminum sulfate is suitable. These components can be added to the suspension sequentially or simultaneously in any order.

  In step c), only hollow bodies that are stable at acidic pH values are used.

  In step d), on the other hand, a component for adjusting the pH value is added, thereby adjusting the pH value to 4-9.

The surface-treated TiO ₂ pigment is separated from the suspension by filtration methods known to those skilled in the art and the resulting filter cake is washed to separate soluble salts. The cleaned filter paste is treated with a compound containing nitrate, such as KNO ₃ , NaNO ₃ , Al (NO ₃ ) ₃ , before or during subsequent drying to improve the light fastness of the pigments in the laminate. It can be mixed in an amount of 0.05-0.5% calculated as NO ₃ . In subsequent milling, for example milling with a wet jet mill (Dampfmuehle), organic pigments such as polyalcohols are used from the group which are usually used in the production of TiO ₂ pigments and are known to those skilled in the art (Trimethylolpropane) can be added.

  As an alternative to the addition of nitrate-containing compounds before or during drying, the addition of such substances can also take place during grinding.

  Pigments made according to this method exhibit improved opacity compared to comparative pigments and are very suitable for use in decorative paper or decorative coatings.

  The surface treatment method according to the present invention is usually carried out in batch operation. It is also possible to carry out the treatment continuously, in which case sufficient mixing must be ensured, for example by means of suitable mixing tools known to those skilled in the art.

EXAMPLES The present invention will now be described by way of example, which is not intended to limit the invention.

EXAMPLE A suspension of TiO ₂ from the chlorine method, ground in a sand mill, having a TiO ₂ concentration of 350 g / l was adjusted to a pH value of 10 at 60 ° C. with NaOH. Under stirring, 2.0% by weight of Al ₂ O ₃ suspension was added as a sodium aluminate solution. After a stirring time of 15 minutes, 2.4% by weight of P ₂ O ₅ was added as a solution of disodium hydrogen phosphate. An additional 15 minutes of stirring time continued. Subsequently, 30% Ropaque Ultra Emulsion (polymer hollow spheres, Rohm & Haas) was added according to the content of styrene / acrylic copolymer of 2% by weight of active substance with respect to TiO _{2 and} stirred for a further 15 minutes. The suspension was adjusted to a pH value of 5 in the next step by addition of an aluminum sulfate solution corresponding to 2.6% by weight Al ₂ O ₃ . Subsequently, 0.7% by weight of Al ₂ O ₃ was mixed in the form of a parallel addition of sodium aluminate solution and aluminum sulfate solution to keep the pH value at 5.

After a stirring time of 30 minutes, the suspension was adjusted to a pH value of about 5.8 using a solution of alkaline sodium aluminate, filtered, and water-soluble salts were removed by washing. The washed filter paste was dried in a spray drier in the form of NaNO ₃ with the addition of 0.25% by weight of NO ₃ and subsequently ground in a wet jet mill.

  A transmission electron micrograph of the example pigment shows the hollow body deposited on the pigment surface in FIG.

Comparative Example A suspension of TiO ₂ from the chlorine method crushed in a sand mill with a TiO ₂ concentration of 350 g / l was adjusted to a pH value of 10 at 60 ° C. with NaOH. Under stirring, 2.0% by weight of Al ₂ O ₃ suspension was added as a sodium aluminate solution. After a stirring time of 15 minutes, 2.4% by weight of P ₂ O ₅ was added as a solution of disodium hydrogen phosphate. An additional 15 minutes of stirring time continued. The suspension was adjusted to a pH value of 5 in the next step by adding an aluminum sulphate solution corresponding to 2.6% by weight Al ₂ O ₃ . Subsequently, 0.8% by weight of Al ₂ O ₃ was mixed in the form of parallel addition of sodium aluminate solution and aluminum sulfate solution, and the pH value was kept at 5.

After 30 minutes of stirring time, the suspension was adjusted to a pH value of about 5.8 using an alkaline sodium aluminate solution, filtered, and water-soluble salts were removed by washing. The washed filter paste was dried in a spray drier in the form of NaNO ₃ with the addition of 0.25% by weight of NO ₃ and subsequently ground in a jet mill.

Test method and test results
In order to evaluate the optical properties of the test-style decorative paper and thus the quality of the titanium dioxide pigment, it is important to compare with decorative paper of the same ash content. A decorative paper having a weight of about 80 g / m ² and an ash content of about 30 g / m ² was produced. This procedure and the auxiliaries used are known to those skilled in the art.

  The titanium dioxide content (ash content) of one piece of paper and the pigment yield were subsequently measured.

a) Ash content For the determination of the titanium dioxide content, a defined mass of the produced paper was ashed at 900 ° C. using a high-speed ashing device (Schnellverascher). The mass ratio of TiO ₂ (ash) was obtained in mass% depending on the amount of residue generated. The calculation of ash content was based on the following formula.
Ash content [g / m ² ] = (ash [mass%] × basis weight [g / m ² ]) / 100 [%]
b) Yield Yield is understood as the retention of all inorganic substances in the paper on the paper machine net. The so-called one-pass retention measured here indicates the percentage proportion that is retained in one paper machine feed process. The percentage ratio of ash to weight parts of pigment used in the total solids of the suspension is the yield.
Yield [%] = Ash content [%] × (Pigment weight [g] + pulp weight [g])
Pigment weighing [g]
b) Optical properties The optical properties of the pigments were measured in the laminate.

For this purpose, the decorative paper was impregnated with a modified melamine impregnated resin and pressed into a laminate. A piece of paper to be resin coated is completely impregnated in the melamine resin solution and then passed between two doctor blades to ensure a constant resin application and then directly at 130 ° C. in a circulating air drying shelf. (Vorkondensieren). Resin application was 120-140% of the mass of a piece of paper. The paper had a residual moisture of about 6% by weight. The compressed paper is integrated into a presscake together with a core paper impregnated with phenolic resin and white / black underlay paper. For the evaluation of the test pigment, the laminate structure was composed of 11 layers. That is, decorative paper, white / black underlay, core paper, core paper, core paper, white underlay, core paper, core paper, core paper, white / black underlay, decorative paper. The molding material is pressed using a Wickert Laminat-Presse type 2742 at a temperature of 140 ° C. and a pressure of 900 N / cm ² for a press time of 300 seconds.

  The optical properties of the laminate were measured using a commercially available photometer.

For the evaluation of the optical properties of the layered press material, the decorative paper color values (CIELAB L ^* , -a ^* , -b ^* ) are measured in white using an ELREPHO® 3000 color meter according to DIN 6174. And for black underlay. Opacity is a measure for the translucency or transparency of paper. The following parameters were selected as criteria for the opacity of the laminate: CIELAB L ^* _schwarz , ie the brightness of the laminate measured on black underlay paper, and the opacity value L [%] = (Y _schwarz / Y _weiss ) × This L is calculated from the Y value (Y _schwarz ) of the decorative paper measured for the black underlay paper and the Y value (Y _weiss ) measured for the white underlay paper.

Test results This table shows the test results for laminates made with the pigments according to the invention (Examples) and laminates made with comparative pigments (Comparative). The pigment according to the invention has an improved opacity compared to the comparative pigment.

It is the transmission electron micrograph of a pigment which shows the hollow body deposited on the pigment surface.

Claims (22)

  A titanium dioxide pigment comprising titanium dioxide particles, wherein the pigment comprises titanium dioxide particles, wherein a coating comprising aluminum phosphate, aluminum oxide and hollow bodies is present on the particle surface.   The titanium dioxide pigment according to claim 1, wherein the hollow body has an average diameter of 5 to 1000 nm. Characterized in that the aluminum content of the coating is 1.0 to 9.0% by weight, preferably 3.5 to 7.5% by weight, in particular about 5.5% by weight, calculated as Al ₂ O _3. The titanium dioxide pigment according to claim 1 or 2. The phosphorus content of the coating is 1.0 to 5.0% by weight, preferably 1.5 to 3.5% by weight, especially 2.0 to 3.0% by weight, calculated as P ₂ O ₅ The titanium dioxide pigment according to claim 1, wherein the pigment is titanium dioxide. A method for producing coated titanium dioxide pigment particles, comprising:
a) Preparation of an aqueous suspension of uncoated titanium dioxide particles b) Addition of aluminum component and phosphorus component c) Addition of components containing hollow bodies d) pH value of suspension in the range of about 4-9 The manufacturing method of the pigment particle of the coated titanium dioxide including the process of adjusting to the value of this. 6. Process according to claim 5, characterized in that the pH value of the suspension is at least 10 in step a) and the pH value of the suspension is kept at least 10 in step b).   6. Process according to claim 5, characterized in that the pH value of the suspension is adjusted to less than 4 in step b).   The method according to claim 5, wherein the hollow body has an average diameter of 5 to 1000 nm.   9. A method according to any one of claims 5 to 8, characterized in that a further aluminum oxide layer is applied in step e) at a pH value of about 4-9. The total amount of aluminum compound added is calculated to be 1.0 to 9.0% by weight, preferably 3.7 to 7.5% by weight, especially about 5.5% by weight, calculated as Al ₂ O _3. 10. A method according to any one of claims 5 to 9, characterized in that The total amount of phosphorus compound added is 1.0 to 5.0% by mass, preferably 1.5 to 3.5% by mass, especially 2.0 to 3.0% by mass, calculated as P ₂ O _5. 10. A method according to any one of claims 5 to 9, characterized in that it is.   12. A further metal salt solution, for example a metal salt solution of Ce, Ti, Si, Zr or Zn, together with an Al component and a P component in step b) is added to the suspension. The method of any one of these.   12. The process according to claim 11, characterized in that in step f) the final pH value of the suspension is adjusted to about 5-8.   14. Process according to any one of claims 5 to 13, characterized in that an acidic metal salt solution of Ce, Ti or Zr is used for adjusting the pH value in step d).   15. A process according to any one of claims 5 to 14, characterized in that the pigment particles are treated with nitrate in a subsequent step so that the finished pigment contains a maximum of 1.0% by weight of nitrate.   The process according to any one of claims 5 to 15, characterized in that the pigment particles are pulverized together with the organic substance in a subsequent step. A method for producing coated titanium dioxide pigment particles, comprising:
a) Preparation of an aqueous suspension of uncoated titanium dioxide particles, the pH value of the suspension being at least 10 b) Addition of aluminum component and phosphorus component, pH value of the suspension C) addition of components containing hollow bodies d) adjusting the pH value of the suspension to a value in the range of about 4-9 e) of the aluminum oxide at a pH value of about 4-9 A process for producing coated titanium dioxide pigment particles comprising the step of applying a layer.   18. Titanium dioxide pigment particles produced according to the method of any one of claims 5 to 17.   Use of a titanium dioxide pigment according to any one of claims 1, 2, 3, 4, 18 in the manufacture of decorative paper.   A decorative paper comprising the titanium dioxide pigment according to any one of claims 1, 2, 3, 4, and 18.   Use of a decorative paper comprising a pigment of titanium dioxide according to any one of claims 1, 2, 3, 4, 18 for the manufacture of a decorative coating.   A decorative covering comprising the decorative paper according to claim 20.

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