Cosmetic coated titanium dioxide particle and preparation thereof

Abstract

The present invention relates to a method for producing a cosmetic titanium dioxide pigment particle comprising the steps of: a) providing an uncoated titanium dioxide pigment particle, and b) coating the uncoated titanium dioxide pigment particle with a bio-based oil to produce a cosmetic titanium dioxide pigment particle, and to a cosmetic titanium dioxide pigment particle comprising a titanium dioxide pigment particle coated with a bio-based oil, wherein the cosmetic titanium dioxide pigment particle comprises a titanium dioxide pigment particle coated with 0.01 wt.% to 0.5 wt of a bio-based oil based on the total weight of the cosmetic titanium dioxide pigment particle.

Description

FIELD OF THE INVENTION The present invention relates to a method for producing a cosmetic titanium dioxide pigment particle, a cosmetic titanium dioxide pigment particle obtainable by the inventive method and a cosmetic titanium dioxide pigment particle. The present invention also relates to a method for manufacturing a cosmetic formulation, a cosmetic formulation obtainable by this method, and the use of the inventive cosmetic titanium dioxide pigment particle or the use of the inventive cosmetic formulation for cosmetic applications. TECHNOLOGICAL BACKGROUND OF THE INVENTION Titanium dioxide, also known as titania, is a white pigment for high-end applications. As a pigment, titanium dioxide pigment particles have various applications such as cosmetics. TiO? pigment particles are sometimes coated with organic coatings when used in products such as cosmetics. Typically, these coated pigment particles are formed by simply mixing the TiO? particles with the organic coating and the final end product. Those coated pigment particles regularly have a rather thick coating or are not homogeneously coated if a reduced amount of organic compound is used for coating. In case of thick coatings those particles have a rather high carbon content which is not desirable. Besides, the before mentioned method can cause undesirable agglomeration of the pigment particles, which can reduce the optical quality of the final product. Furthermore, obtained pigment particles have inferior dispersing properties leading to a lower brightness of the final cosmetic product. Therefore, it would be desirable to have a method for producing a cosmetic titanium dioxide pigment particle having improved dispersing properties, having a low carbon content and / or improves brightness of the final product. Besides, in applications such as cosmetic applications a color-neutral appearance is preferred. OBJECT AND SUMMARY OF THE INVENTION It is the technical object of the invention to provide a method and a cosmetic titanium dioxide particle as well as cosmetic formulations overcoming above problems. This object is achieved by a a method for producing a cosmetic titanium dioxide particle being coated with a bio-based oil. The object is moreover achieved by a cosmetic titanium dioxide pigment particle comprising a titanium dioxide pigment particle coated with a biobased oil according to the invention as well as a cosmetic formulation according to the inventiob n. The inventors have surprisingly found a cosmetic titanium dioxide pigment particle being coated with a bio-based oil applied on a titanium dioxide particle having a satisfactory b* value and concomitantly improving the brightness of cosmetic formulations. Besides, the carbon content as well as the Loss on Drying and Loss on Ignition are favorable. In a first aspect the present invention relates to a method for producing a cosmetic titanium dioxide pigment particle comprising, preferably consisting of, the steps of: a) providing an uncoated titanium dioxide pigment particle, and b) coating the uncoated titanium dioxide pigment particle with a bio-based oil to produce a cosmetic titanium dioxide pigment particle. A bio-based oil according to the invention refers to a type of oil that is derived from renewable biological sources, such as plants, algae, animals or other organic materials. Unlike traditional petroleum-based oils, which are derived from fossil fuels, bio-based oils are produced from biomass through processes like extraction, fermentation, or other bioconversion methods. Those bio-based oils are regularly environmental sustainability and minimize the carbon footprint associated with their production. Thus, bio-based oils are oils obtained from sustainable sources. The bio-based oils comprise refined bio-based oils. Those oils can have a positive effect in particular when used for cosmetic purposes as they can help to reduce e.g. skin irritation or other disadvantageous reactions. For example can the use of polydimethylsiloxane (PDMS) be reduced or completely avoided. Uncoated titanium dioxide pigment particle is to be understood as neither organically nor inorganically coated titanium dioxide pigment particle. In a second aspect the invention relates to a cosmetic titanium dioxide pigment particle obtainable by the inventive method for producing a cosmetic titanium dioxide pigment particle. In a third aspect the invention relates to a cosmetic titanium dioxide pigment particle comprising, preferably consisting of, a titanium dioxide pigment particle coated with 0.01 wt.% to 0.5 wt.%, preferably 0.1 wt.% to 0.45 wt.% and more preferably 0.15 - 0.4 wt.% of a bio-based oil based on the total weight of the cosmetic titanium dioxide pigment particle. The inventive cosmetic titanium dioxide pigment particles have advantageous properties when dispersed in a cosmetic formulation. They increase the brightness. This allows the reduction of titanium particles in a cosmetic formulation. Furthermore, it is an indication of an improved tinting strength. In addition to that, the carbon content of the cosmetic TiO? pigment particles can be kept at a low level leading to advantageous Loss on Dryingn and Loss on Ignition properties. In a fourth aspect the invention relates to a method for manufacturing a cosmetic formulation comprising, preferably consisting of, the steps of: a) providing an uncoated titanium dioxide pigment particle; b) coating the titanium dioxide pigment particle with a bio-based oil to manufacture a cosmetic titanium dioxide pigment particle; and c) mixing the coated cosmetic titanium dioxide pigment particle with ingredients of the cosmetic formulation, preferably the ingredients are selected from the group consisting of water, oils, emulsifiers silicones, solvents, color pigments, rheological modifiers such as thickener, stabilizers, antioxidants, preservatives, pH adjusters, fillers, wetting agents and / or combinations thereof. By the method according to this aspect cosmetic compositions with advantageous properties such as increased brightness can be produced. Besides, the amount of potential irritants and / or non-sustainable compounds in the manufactured cosemetic formulation can be reduced. In a fifth aspect the invention relates to a cosmetic formulation obtainable by the method according to the fourth aspect. In a sixth aspect the invention relates to a cosmetic formulation comprising the inventive cosmetic titanium dioxide pigment particle. In a seventh aspect the invention relates to the use of the inventive cosmetic titanium dioxide pigment particle or the use of the inventive cosmetic formulation for cosmetic applications, preferably decorative cosmetics. DESCRIPTION OF THE INVENTION These and other aspects, features and advantages of the invention become obvious to the skilled person from the study of the following detailed description and claims. Each feature from one aspect of the invention can be employed in any other aspect of the invention. Numerical ranges stated in the format "from x to y" include the mentioned values and the values that are within the respective measuring accuracy as known to the skilled person. If several preferred numerical ranges are stated in this format, it is a matter of course that all ranges formed by the combination of the various end points are also included. The pigment particle according to the present invention is comprised of a titanium dioxide pigment and a coating with a bio-based oil. “Titanium dioxide pigments” or “titanium based pigment particles”, as used herein, refers to titanium dioxide pigments obtained by the sulphate or chloride process which are optionally milled. Further, said pigment may be present in the crystal structures of rutile, anatase or brookite, usually in the crystal structures of rutile or anatase. Rutile is particularly suitable as compared to anatase because of its lower photocatalytic activity and higher refractive index. Preferably, said titanium dioxide pigment consists of at least 98 wt.%, preferably of at least 99 wt.% rutile referred to the total weight of said particles. Within the scope of the invention, the titanium dioxide pigment particle has a primary size such that it scatters the visible light, ideally to a high rate. The particle size is the mass-related median d50 (hereinafter: d50) of from 200 nm to 400 nm determined by disc centrifuge. The inventive titanium oxide particles have preferably a spheroidal shape with aspect ratios between 1.1 and 1.6, preferably those particles have an average aspect ratio of 1.2 to 1.4. The particles have preferably a convex form. It is preferred that the inventive titanium dioxide particles are not flake like structures. In the first aspect the invention relates to the method for producing a cosmetic titanium dioxide pigment particle as mentioned above. In a preferred embodiment in step b) 0.1 wt.% to 2.0 wt.%, preferably 0.1 wt.% to 1.0 wt.%, more preferably 0.2 wt.% to 0.5 wt.% and even more preferably 0.3 wt.% to 0.4 wt.% of biobased oil based on the total weight of the uncoated titanium dioxide pigment particle are employed. Using this amount of bio-based oil is advantageous as it allows for the production of coated titanium particles having a low carbon content. A low carbon content is favorable with respect to the properties of the coated TiO? pigment particle in particular with respect to Loss on Drying and Loss on Ignition which are important properties with respect to cosmetic applications. Through this rather low amount of bio-based oil it is still possible to obtain TiO? particles dispersing well in cosmetic formulations leading to improved brightness, that is, L* values in CIELAB measurements. Furthermore, this amount of bio-based oil still provides a homogeneous coating of the TiO? pigment particle with the bio-based oil. It is preferred that other compounds, such as water, are only present in an amount of less then 2.0 wt.%, preferably less than 1.0 wt.%, and more preferably less than 0.9 wt.% based on the combined weight of uncoated titanium dioxide pigment particle and bio-based oil present over the course of the coating step. This is also important with respect to the Loss on Drying and Loss on Ignition of the final coated TiO? pigment particle. It is further preferred that the coated cosmetic titanium dioxide pigment particle has a mean particle size (D50) in the range of from 100 nm to 500 nm, preferably 200 nm to 400 nm. Furthermore, it is preferred that the titanium dioxide pigment particle does not comprise a metal oxide and / or metalloid oxide layer. This means no further layers comprising aluminium oxide, zirconium oxide, silicone dioxide, tin oxide, cerium oxide or mixtures thereof are present. In an embodiment the titanium dioxide pigment particle is present in the crystal structure anatase or in the crystal structure rutile, preferably in the crystal structure rutile. The b*-value for the bio-based oil was measured with a spectrometer Perkin Elmer Lambda 950 applying „Messprinzip CIE Normalbeobachter von 1931 (2°), Normlicht C“ (Measuring principle CIE standard observer from 1931 (2°), standard light C). In a preferred embodiment the bio-based oil has a b*-value, measured according to measuring principle CIE standard observer from 1931 (2°), of lower than 10, preferably lower than 8. In another preferred embodiment the bio-based oil is a plant-based oil, preferably a plantbased oil with a b*-value, measured according to measuring principle CIE standard observer from 1931 (2°), of lower than 10, preferably lower than 8. According to a preferred embodiment the plant-based oil is selected from the group consisting of soybean oil, sesame oil, rice germ oil, avocado oil, moringa oil, sunflower oil, rapeseed oil, grape seed oil or mixtures thereof, preferably sesame oil, rice germ oil, moringa oil, sunflower oil, rapeseed oil, grape seed oil or mixtures thereof, and more preferably rice germ oil. The application of those oils leads to advantageous brightness of the obtained titanium dioxide pigment particles. It is further preferred that step b) is conducted by homogenizing the titanium dioxide pigment particle with the bio-based oil at 1,000 rpm to 3,000 rpm, preferably at 2,000 rpm. It is further preferred that the homogenizing is performed for 1 second to 600 seconds, preferably for 20 to 420 seconds, and more preferably for 30 seconds to 300 seconds. In addition to that an optional sieving step using a sieve, preferably with a mesh size of 400 to 1000 pm, and preferably 600 to 900 pm, may be performed. Homogenizing the TiO? pigment particles support the homogeneous coating of TiO2 pigment particles even if rather low amounts of bio-based oil are used It should be understood that any feature and / or aspect discussed below in connection with the inventive cosmetic titanium dioxide particles according to the invention apply by analogy to the method described hereinbefore. In the second aspect the invention relates to a cosmetic titanium dioxide pigment particle obtainable by the inventive method described before. It should be understood that any feature and / or aspect discussed above in connection with the method described above and the cosmetic titanium dioxide pigment particle described below in particular under the third aspect apply by analogy to the second aspect. In a third aspect the invention relates to a cosmetic titanium dioxide pigment particle comprising a titanium dioxide pigment particle coated with 0.01 wt.% to 0.5 wt.%, preferably 0.1 wt.% to 0.45 wt.% and more preferably 0.15 to 0.4 wt.% of a bio-based oil based on the total weight of the cosmetic titanium dioxide pigment particle. It should be understood that any feature and / or aspect discussed above in connection with the method according to the invention apply by analogy to the cosmetic titanium dioxide particle described. The amount of bio-based oil makes those particles particular suitable for cosmetic applications. Besides, the carbon content is low leading i.a. to advantageous properties with respect to Loss on Drying and Loss on Ignition. In a preferred embodiment the cosmetic titanium dioxide pigment particle according to the second aspect and the third aspect has a brightness L*, when used in a cosmetic formulation as described in the example section, of at least 50, preferably at least 60, more preferably at least 64. This advantageous brightness, L*, demonstrates the good dispersability of the inventive particles in cosmetic formulations. Due to that it would be possible to lower the amount of cosmetic TiO? pigment particle in a respective cosmetic formulation in order to have the same brightness as cosmetic formulation not applying the pigment particles according to the invention. It is further preferred that the cosmetic titanium dioxide pigment particle comprises at most 2.0 wt.%, preferably at most 1.0 wt.%, and more preferably 0.9 wt.% compounds, other than the titanium dioxide pigment particle and the bio-based oil. The b*-value for the bio-based oil was measured with a spectrometer Perkin Elmer Lambda 950 applying „Messprinzip CIE Normalbeobachter von 1931 (2°), Normlicht C“ (Measuring principle CIE standard observer from 1931 (2°), standard light C). In a preferred embodiment the bio-based oil has a b*-value, measured according to measuring principle CIE standard observer from 1931 (2°), standard light C, of lower than 10, preferably lower than 8. In another preferred embodiment the bio-based oil is a plant-based oil, preferably a plantbased oil with a b*-value, measured according to measuring principle CIE standard observer from 1931 (2°), standard light C, of lower than 10, preferably lower than 8. In another preferred embodiment the bio-based oil is a natural oil, preferably a natural oil with a b*-value, measured according to measuring principle CIE standard observer from 1931 (2°), standard light C, of lower than 10, preferably lower than 8. It is further preferred that the cosmetic titanium dioxide pigment particle has b*-value, measured according to the CIELAB powder method according to the description, of lower than 10, preferably lower than 7, more preferably lower than 4, and even more preferably lower than 2. According to a preferred embodiment the plant-based oil is selected from the group consisting of soybean oil, sesame oil, rice germ oil, avocado oil, moringa oil, sunflower oil, rapeseed oil, grape seed oil or mixtures thereof, preferably sesame oil, rice germ oil, moringa oil, sunflower oil, rapeseed oil, grape seed oil or mixtures thereof, and more preferably rice germ oil. In another embodiment the titanium dioxide pigment particle does not comprise a metal oxide and / or metalloid oxide layer. It is preferred that the cosmetic titanium dioxide pigment particle has a Loss on Drying of less than 0.5 wt.%, preferably less than 0.3 wt.%, and more preferably in the range of from 0.01 to 0.3 wt.%; and / or that the cosmetic titanium dioxide pigment particle has a Loss on Ignition of less than 0.5 wt.%, preferably less than 0.4 wt.%, and more preferably in the range of from 0.01 to 0.4 wt.%; and / or that the cosmetic titanium dioxide pigment particle as a Carbon content of less of less than 0.5 wt.%, preferably less than 0.4 wt.%, and more preferably in the range of from 0.01 to 0.4 wt.%. In a preferred embodiment the coating with the bio-based oil is a homogeneous coating. In a fourth aspect the invention relates to a method for manufacturing a cosmetic formulation comprising, preferably consisting of, the steps of: a) providing an uncoated titanium dioxide pigment particle; b) coating the titanium dioxide pigment particle with a bio-based oil to manufacture a cosmetic titanium dioxide pigment particle; and c) mixing the coated cosmetic titanium dioxide pigment particle with ingredients of the cosmetic formulation, preferably the ingredients are selected from the group consisting of water, oils, emulsifiers silicones, solvents, color pigments, rheological modifiers such as thickener, stabilizers, antioxidants, preservatives, pH adjusters, fillers, wetting agents and / or combinations thereof. It should be understood that any feature and / or aspect discussed above in connection with the other aspects according to the invention apply by analogy to this aspect as well. In an embodiment the rheological modifier is a thickener. It is preferred that the filler is mica, talc or a combination thereof. In a fifth aspect the present invention relates to a cosmetic formulation obtainable by the method for manufacturing a cosmetic formulation. It should be understood that any feature and / or aspect discussed above in connection with the other aspects according to the invention apply by analogy to this aspect as well. In a sixth aspect the present invention relates to a cosmetic formulation comprising the inventive cosmetic titanium dioxide pigment particle. It should be understood that any feature and / or aspect discussed above in connection with the other aspects according to the invention apply by analogy to this aspect as well. The inventive cosmetic formulation has advantageous brightness, L*. It is preferred that the cosmetic formulation is a water-in-oil emulsion (W / 0), an oil-in-water emulsion (0 / W), or in a powderous form. In a seventh aspect the present invention relates to the use of the inventive cosmetic titanium dioxide pigment particle, or the use of the inventive cosmetic formulation for cosmetic applications, preferably decorative cosmetics. It should be understood that any feature and / or aspect discussed above in connection with the other aspects according to the invention apply by analogy to this aspect as well. It is preferred that the inventive pigment particle or the inventive cosmetic formulation are used for make up, cosmetic foundations, bb cream, blush, nail varnish, hair color, skin brightner, concealer, pressed powder, stage make-up, personal care products, creams, lotion, mascara, soap and / or eye shadow. Experimental Section Examples An uncoated rutile titanium dioxide pigment particle (300 g, K2071 commercially available von Kronos Titan GmbH) was mixed with 0.3 wt.% of a bio-based oil (applied oils are metioned in Table 2). In a first step, the mixture was pre-homogenized by stirring with a spatula. Then, the mixture was further homogenized in a speedmixer (SpeedMixer DAC 600.2 VAC-by Hausschild) at 2,000 rpm for 30 seconds. The so obtained mixture was sieved with a sieve having a mesh size of 800 pm. The sieved mixture was finally mixed at 1,000 rpm to 2,000 rpm for 1 minute in a mixer (Nobilta-Mischer NOB 130 by Hosokawa Alpine) to obtain a cosmetic titanium dioxide pigment particle. The cosmetic titanium dioxide pigment particle was formulated into a standard cosmetic foundation (ALL DAY LONG - Long lasting foundation - obtained from Brenntag), whereby the TiO? K1171 (Kronos) was replaced by TiO2 pigments as described herein, and analyzed. Comparative Examples Comparative Example 1 is K2071 commercially available von Kronos Titan GmbH without any coating. Comparative Example 2 was produced by providing all components of the standard cosmetic foundation (ALL DAY LONG - Long lasting foundation - obtained from Brenntag without the TiO? K1171 (Kronos)) as well as K2071 and 0.3 wt.% based on the amount of TiO2 pigment of soybean oil and homogenizing the components at 2,000 rpm for 1 minute. CIELAB Determination For Foundation: The L*, a* and b* values were determined as follows: The foundations were applied with a layer thickness of 400pm wet (doctor blade (Rakel) from company Erichsen) on black leneta card (Leneta black plastic chart P121-14. After 48 hours of drying the color L*, a* and b*of the foundation was measured by a spectro-guide sphere gloss from Byk-Gardner. Measurement results are shown in Tables 1 & 2. For Powder: The L*, a* and b* values were determined as follows: Measurements were performed according to DIN EN ISO 11664-4:201 1-07 and DIN EN ISO 787-25:2007. For pigment powder measurements the powder was pressed in a form of powder pellet with a matte surface. The X-Rite VS450 colorimeter was used for reflectance data determination. Measurement results are shown in Table 3. Table 1: L*, a* and b* values of cosmetic formulations according to CE1 & 2 and Example 1 Example Sample L* a* b* Comparative Example 1 K 2071 without coating 63.5 9.7 15.2 Example 1 K 2071 coated with 0.3 wt.% soybean oil according to the invention 66.1 8.2 12.9 Comparative Example 2 K 2071 + 0.3 wt.% soybean oil added during cosmetic production 62.4 10.4 14.8 The measurements showed that a cosmetic formulation comprising TiO? coated with soybean oil showed a higher L* value, that is, brightness of the cosmetic formulation was improved. From this can be derived that the TiO? coated according to Example 1 has better dispersing properties in the cosmetic foundation compared to CE1 and CE2. It can be seen that the cosmetic formulation according to Example 1 possesses a higher brightness (L*-value) compared to the uncoated titanium dioxide pigment particle (CE1) and the foundation obtained by the state of the art method (CE2). Further CIELAB measurements were performed applying uncoated TiO? (K2071) and further bio-based oils according to Examples 1 to 5. The results obtained in this measurement series were referenced to Example 1 (Brightness (%)), that is, the TiO? coated with 0.3 wt.% of soybean oil. The results of those measurements are shown in Table 2. Table 2: Brightness in % (based on L*) of CE1 & Examples 2 to 5 relative to Example 1 Example Sample Brightness (%) Comparative Example 1 K2071 uncoated 90.2 Example 1 K 2071 coated with 0.3 wt.% soybean oil 100.0 Example 2 K 2071 coated with 0.3 wt.% sesame oil 99.0 Example 3 K 2071 coated with 0.3 wt.% Moringa oil 98.1 Example 4 K 2071 coated with 0.3 wt.% Avocado oil 98.1 Example 5 K 2071 coated with 0.3 wt.% Rice germ oil 100.2 It can be seen that the cosmetic formulations according to Examples 1 to 5 possess a higher brightness compared to the uncoated titanium dioxide pigment particle (CE 1). In Table 3 the L*, a* and b* values of the pigment powders, which are applied in Examples 1 - 5 and CE 1 are shown. Table 3 also shows the difference in b* values between a coated and an uncoated pigment particle. Table 3: b* values of coated TiO? pigment powders according to Examples 1 to 5 Example Sample b*coated - b* uncoated L* a* b* Test series 1 Comparative Example 1 K2071 uncoated — 98.6 -0.13 0.94 Example 2 K2071 coated with 0.3 wt.% soybean oil 0.05 98.3 -0.19 0.99 Example 5 K2071 coated with 0.3 wt.% Rice germ oil 0.02 98.2 -0.17 0.96 Test Series 2 Comparative Example 1 K2071 uncoated — 98.5 -0.08 0.58 Example 1 K2071 coated with 0.3 wt.% soybean oil 0.09 98.5 -0.09 0.67 Example 2 K2071 coated with 0.3 wt.% sesame oil 0.16 98.5 -0.1 0.74 Example 3 K2071 coated with 0.3 wt.% Moringa oil 0.13 98.5 -0.12 0.71 Example 4 K2071 coated with 0.3 wt.% Avocado oil 0.12 98.5 -0.11 0.7 Particle size determination The size of the titanium dioxide particles was determined by using a CPS Disc centrifuge, Model DC 20000 available from CPS Instrument, Inc. located in Florida, United States of America. The sample was prepared by obtaining a first premix by mixing 2 g of a dry pigment particles with 80 g sodium hexametaphosphate solution (0.06 mass % in water) to obtain a first premix. The sodium hexametaphosphate is commercially available from BK Giulini GmbH in Ladenburg, Germany, under the name Calgon N until the first premix was homogenized. Subsequently, 2 g of this first premix were added to a sodium hexametaphosphate solution (0.06 mass % in water), and again sufficiently homogenized by mixing to obtain a second premix. 100 pl of this second premix were used as the sample for determining the particle size. The centrifuge was operated at 3,000 rpm. The calibration standard parameters were as follows: • Particle density: 1.385 g / mL • Peak diameter: 1.27 pL • Half height peak width: 0.08 pL The fluid parameters were as follows: • Fluid density: 1.045 g / mL • Fluid refraction index: 1.344 • Fluid viscosity: 1.2 cps Determination of Carbon Content Equipment: LECO CS774 Carbon I Sulfur analyzer by means of Combustion Infrared Detection Technique; analytical balance A pre-weighed sample of 0.5 gram is combusted in a stream of oxygen using RF induction to heat the sample.Carbon and sulfur present in the sample are oxidized to carbon dioxide (CO2) and sulfur dioxide (SO2), swept by the oxygen carrier through a drying reagent and then through a non-dispersive infrared (NDIR) cell, where sulfur is detected as SO2. The gas flow continues past a heated catalyst, where carbon monoxide (CO) is converted to CO2 and SO2 to sulfur trioxide (SO3), which is subsequently removed by a filter. Carbon is then detected as CO2 by another NDIR cell. Sulfur is not calibrated, therefore is no method available. Non dispersive infrared cells are based on the principle that CO2 and SO2 absorb infrared (IR) energy at unique wavelengths within the IR spectrum. Determination Loss on Drying (LOP) and Loss on Ignition (LOI) Approximately 10 g (+ / -1 g ) of the material to be tested is weighed into a previously annealed and balanced crucible. First, the material is dried for two hours at 105°C in a drying oven. After this, the crucibles are left to cool in a desiccator for 45 minutes. The proportion of volatile substances is then determined by weighing (LOD). The dried sample is then annealed for half an hour at 800°C in the muffle furnace. The crucibles are then cooled again in the desiccator. This time, cooling takes approx. 1-1.5 hours for eight crucibles. By determining the weight loss, the proportion of loss on ignition is obtained in relation to the dried sample (LOI). In Table 4 the results on the measurements of the pigment particles according to Examples 1 - 5 are shown. The carbon content, the Loss on Drying and the Loss on Ignition were determined. Table 4: Results of carbon content, Loss on Drying and Loss on Ignition measurements of TiO2 pigment particles coated with different bio-based oils. Carbon content [wt.%] Loss on drying [wt.%] Loss on ignition [wt.%] Example 1 0.32 0.1 0.33 Example 2 0.24 0.12 0.3 Example 3 0.42 0.12 0.34 Example 4 0.3 0.11 0.32 Example 5 0.24 0.1 0.27 From Table 4 can be derived that all inventive cosmetic titanium dioxide particles with a coating of a bio-based oil have advantageous properties with respect to carbon content, Loss on Drying as well as Loss on Ignition.

Claims

1. A method for producing a cosmetic titanium dioxide pigment particle comprising the steps of:a) providing an uncoated titanium dioxide pigment particle, andb) coating the uncoated titanium dioxide pigment particle with a bio-based oil to produce a cosmetic titanium dioxide pigment particle.

2. The method according to claim 1,wherein other compounds are only present in an amount of less then 2.0 wt.%, preferably less than 1.0 wt.% based on the combined weight of uncoated titanium dioxide pigment particle and bio-based oil present over the course of the coating step.

3. The method according to claim 1 or 2,wherein the titanium dioxide pigment particle has a mean particle size (D50) in the range of from 100 nm to 500 nm, preferably 200 nm to 400 nm; and / orwherein the titanium dioxide pigment particle does not comprise a metal oxide and / or metalloid oxide layer.

4. The method according to any one of the claims 1 to 3,wherein the titanium dioxide pigment particle is present in the crystal structure anatase or in the crystal structure rutile, preferably in the crystal structure rutile.

5. The method according to any one of the claims 1 to 4,wherein the bio-based oil is a plant-based oil, preferably a plant-based oil with a b*-value, measured according to measuring principle CIE standard observer from 1931 (2°), standard light C, of lower than 10, preferably lower than 8; and / orwherein 0.1 wt.% to 1.0 wt.%, preferably 0.2 wt.% to 0.5 wt.% and more preferably0.3 wt.% to 0.4 wt.% bio-based oil based on the total weight of the uncoated titanium dioxide pigment particle are employed in step b).

6. The method according to claim 5,wherein the plant-based oil is selected from the group consisting of soybean oil, sesame oil, rice germ oil, avocado oil, moringa oil, sunflower oil, rapeseed oil, grape seed oil or mixtures thereof, preferably sesame oil, rice germ oil, moringa oil, sunflower oil, rapeseed oil, grape seed oil or mixtures thereof, and more preferably rice germ oil.

7. The method according to any one of the claims 1 to 6,wherein step b) is conducted by- homogenizing the titanium dioxide pigment particle with the bio-based oil at 1,000 rpm to 3,000 rpm, preferably at 2,000 rpm, for 1 second to 600 seconds, preferably for 20 to 420 seconds, and more preferably for 30 seconds to 300 seconds, and- an optional sieving step using a sieve, preferably with a mesh seize of 400 to 1000 pm, and preferably 600 to 900 pm.

8. A cosmetic titanium dioxide pigment particle obtainable by the method according to any one of the claims 1 to 7.

9. A cosmetic titanium dioxide pigment particle comprising a titanium dioxide pigment particle coated with 0.01 wt.% to 0.5 wt.%, preferably 0.1 wt.% to 0.45 wt.% and more preferably 0.15 - 0.4 wt.% of a bio-based oil based on the total weight of the cosmetic titanium dioxide pigment particle.

10. The cosmetic titanium dioxide pigment particle according to claims 8 or 9,wherein the cosmetic titanium dioxide pigment particle comprises at most 2.0 wt.%, preferably at most 1.0 wt.%, and more preferably 0.9 wt.% compounds other than the titanium dioxide pigment particle and the bio-based oil; and / orwherein the the cosmetic titanium dioxide pigment particle has b*-value, measured according to the CIELAB powder method according to the description, of lower than 10, and preferably lower than 4; and / orwherein the titanium dioxide pigment particle does not comprise a metal oxide and / or metalloid oxide layer.

11. The cosmetic titanium dioxide pigment particle according to any one of claims 8 to 10, wherein the cosmetic titanium dioxide pigment particle has a Loss on Drying of less than 0.5 wt.%, preferably less than 0.3 wt.%, and more preferably in the range of from 0.01 to 0.3 wt.%; and / orwherein the cosmetic titanium dioxide pigment particle has a Loss on Ignition of less than 0.5 wt.%, preferably less than 0.4 wt.%, and more preferably in the range of from 0.01 to 0.4 wt.%; and / orwherein the cosmetic titanium dioxide pigment particle has a Carbon content of less of less than 0.5 wt.%, preferably less than 0.4 wt.%, and more preferably in the range of from 0.01 to 0.4 wt.%; and / orwherein the coating with the bio-based oil is a homogeneous coating.

12. A method for manufacturing a cosmetic formulation comprising the steps of:a) providing an uncoated titanium dioxide pigment particle;b) coating the titanium dioxide pigment particle with a bio-based oil to manufacture a cosmetic titanium dioxide pigment particle; andc) mixing the coated cosmetic titanium dioxide pigment particle with ingredients of the cosmetic formulation, preferably the ingredients are selected from the group consisting of water, oils, emulsifiers silicones, solvents, color pigments, rheological modifiers such as thickener, stabilizers, antioxidants, preservatives, pH adjusters, fillers, wetting agents and / or combinations thereof.

13. A cosmetic formulation obtainable by the method of claim 12.

14. A cosmetic formulation comprising the cosmetic titanium dioxide pigment particle according to claims 8 to 11.

15. The cosmetic formulation according to claim 13 or 14,wherein the cosmetic formulation is a water-in-oil emulsion (W / O), an oil-in-water emulsion (O / W), or in a powderous form.

16. Use of the cosmetic titanium dioxide pigment particle according to any one of claims 8 to 11, or use of the cosmetic formulation according to claims 13 or 15 for cosmetic applications, preferably decorative cosmetics.