FLAKY COLOURED PIGMENT

Abstract: Flaky coloured pigments are obtained by uniformly adher­ ing a finely divided colour pigment onto a flaky substrate by the use of an organic high molecular compound as a binder.

Description: The invention relates to flaky coloured pigments whereby the surface of a flaky substrate is covered with a finely divided colour pigment. It is known that a colour pigment during the course of its production consists of extremely fine particles which are called primary particles. These particles possess a very high surface energy, thus representing an unstable state and tend to cohere to coarser pigment particles. When a pigment of this nature is to be used, therefore the cohering coarse pigment particles are mechanically crushed into primary particles for the purpose of enhancing the colour generating property and the crushed pigment particles have their surface chemically treated for the purpose of enabling the individual particles of the pigment to be kept in a stably dispersed state. The pigment so rendered to be easily wetted and dispersed is put to use. When the pigment treated as described above is left standing for a long time in a vehicle, however, the pigment particles in the vehicle are suffered to cohere again possibly to the extent of adversely effecting the colour generating property of the pigment. The US-A-3647492 describes pigments on the basis of a pearlescent substrate to the surface of which particles of a "finely divided" pigment are bound via an adhesive binder. A fusion of the dried modified pigments to each other is accepted and any agglomerates present in the dried modified pigment are readily broken by crushing or milling. It has now been found, however, that the primary particles of a colour pigment can be deposited to adhere fast in a state free from cohesion on the surface of a flaky substrate, thus producing flaky pigments which exhibit satisfactory spreading property and adhering property to the skin and enjoy high colouring property, especially a very good colour saturation and which possess transparency resistance to weather conditions, heat and solvents. The invention therefore concerns flaky coloured pigments comprising a flaky substrate with a width and length of about 1 - 30 µm and a thickness of about 0.1 - 1 µm, the surface of which is covered by a finely divided colour pigment, which is optionally comminuted with the aid of a sand mill, a ball mill or a roll, the finally divided colour pigment, adhering uniformly to the flaky substrate by the use of an organic high molecular compound as a binder. The invention also concerns a process for the production of flaky coloured pigments characterized in that a flaky substrate is suspended in a dispersion or a solution of a finely divided colour pigment, which is optionally treated with a sand mill, a ball mill or a roll, that the resulting suspension is mixed with a solution of an organic high molecular compound and that the organic high molecular compound and the colour pigment are caused to precipitate onto the flaky substrate. The invention further concerns the use of these flaky coloured pigments in cosmetics. According to the present invention as well organic as inorganic colour pigments can be deposited onto flaky substrates. As concrete examples of flaky substrates to be used in this invention there may be cited talc, Kaolin and bismuth oxychloride as well as various species of mica such as common mica and sericite which have been used to date as raw materials for face powder and other similar cosmetic articles. Synthetic pearl pigments obtained by coating mica with iron oxide or titanium dioxide can also be used. As a rule these substrates are used as particles with a width and length of about 1-30, especially of about 4-25 µm, and having a thickness of about 0.1-1 µm. Examples of the organic high molecular compounds to be used for causing adhesion of the colour pigment to the flaky substrate include polyethylene glycols, polypropylene glycols, polyvinyl pyrrolidons, polyvinyl alcohols, polyacrylates, polyethylene, celluloses and derivatives thereof which are generally acceptable for use as raw materials for cosmetic compositions. As a rule, compounds having molecular weights of about 500 to about 160,000 can be used, those having molecular weights of about 3,000 to about 50,000 being preferred. These binders are used generally in an amount of from about 0.1 to about 10 % by weight, especially in an amount of from about 1 to about 7 % by weight regarding the final flaky coloured pigment. As a rule, the process for coating the colour pigment onto the flaky substrate includes the following steps: (1) The colour pigment is either dispersed in a finely divided state with the aid of, for instance, a sand mill, ball mill or a roll in a solution of an organic high molecular compound in hot water and/or an alcohol or is dissolved in a suitable solvent and admixed with a solution of an organic high molecular compound in water and/or an alcohol. (2) The flaky substrate is suspended in a solution of an organic high molecular compound in water or an alcohol. (3) The suspension or solution of (1) is admixed with the suspension of (2) thereby causing the organic high molecular compound and the colour pigment to be precipitated onto the flaky substrate, and separating the precipitated solid from the suspension and drying the solid. Suitable solvents for the organic high molecular compound include water and alcohols, especially ethanol, and mixtures thereof. If water is used at the solvent, preferably polyethylene glycol with a molcular weight of from about 1,000 to about 10,000, polypropylene glycol with a molecular weight of about 1,000 to about 6,000, polyvinyl alcohol with a molecular weight of about 10,000 to about 100,000 or polyvinyl pyrrolidone with a molecular weight of about 10,000 to about 40,000 is used as the organic high molecular compound. In the case of inorganic pigments which are to be coated onto the flaky substrate and which can be exemplified, for instance, as including iron blue, ultramarine blue, iron oxide type pigments, titanium dioxide, zinc oxide, chromium oxide, cobalt blue and cobalt green, step (1) above always refers to the formation of a suspension of the colour pigment in the solution of the organic high molecular compound. Organic pigments, however, in general are basic compounds containing azo type and hydrazone type groups as colouring groups in the molecular structure thereof and therefore are capable of forming salts with an acidic substance. For example, copper phthalocyanine reacts with sulfuric acid and consequently forms a salt. This sulfate is soluble in sulfuric acid of a high concentration. When the concentration of sulfuric acid is in the order of only 80-65 %, however, the sulfate is not dissolved but is kept in the form of a slurry in the sulfuric acid. The phthalocyanine pigment in the aforementioned form of an acid paste produces finely divided pigment particles when it is poured into a large volume of water. Other possibilities of obtaining a solution of organic pigments includes dissolving the pigment in a solvent containing a Lewis acid or in a polar organic solvent. Examples of solvents to be used for dissolving an organic colour pigment or dispersing it in the form of a slurry include concentrated sulfuric acid, Lewis acids such as solutions of aluminum chloride and iron chloride in alcoholes, and polar organic solvents such as dimethylformamide, dimethylsulfoxide and tetrahydrofurane. Examples of organic pigments which can be used effectively in this invention include organic pigments of the quinacridone type, condensed azo type, dioxazine type, isoindolinone type, vat type and phthalocyanine type. For use in cosmetic articles the following pigments prove desirable: Red colour: No. 3, No. 104, No. 106, No. 202, No. 204 No. 207, No. 213, No. 223, No. 226 and No. 401 Yellow colour: No. 4, No. 5, No. 203, No. 205 and No. 403 Blue colour: No. 202, No. 203, No. 1 and No. 404 Green colour: No. 3 and No. 201 Orange colour: No. 301, No. 203 and No. 205 Purple colour: No. 401 By the process according to the invention practically any desired amount of colour pigment can be adhered to the flaky substrate one being thus able to produce flaky pigments with widely differing colour effects. As a rule, amounts of about 0.5 to about 30 % by weight and especially of about 1 to about 20 % by weight, referring to the total pigment weight, are used. The resulting pigments are especially useful in cosmetics. The flaky pigments possess a bright colour tone, exhibit satisfactory adhering property and spreading property to the skin and prevent the organic or inorganic colour pigment from directly contacting the skin. Thus, it serves to decrease possible differential sensation which the colour pigment may cause on the skin. It has also been found that such compounds as iron blue and ultramarine blue which have poor resistance to heat can be caused to adhere fast to a flaky substrate at a temperature not exceeding 200 °C. Example 1: In 143 g of water, 7.2 g of polyethylene glycol having a molecular weight of about 6,000 was dissolved by heating. In the produced solution, 14 ml of ethanol and 71.5 g of ultramarine blue added thereto were finely divided and dispersed with the aid of a sand mill. The suspension so obtained was added to a solution of 28 ml of ethanol in 576 g of water. Separately, 500 g of mica 1 to 15 µm in grain size was suspended in a solution produced by adding a solution of 5.7 g of polyethylene glycol in 140 g of water to 2,500 g of water. To this suspension which was kept stirred, the aforementioned suspension of pigment was added at a rate of 3 ml/min. The solid which was educed in the resultant mixture was separated by filtration and was dried at a temperature of 110° to 140 °C. Consequently, there was obtained a blue flaky pigment. Example 2: In 200 g of water, 1 g of polyvinyl alcohol was dissolved by heating. In the produced solution, 50 g of ultramarine blue was finely divided and dispersed with the aid of a sand mill. To the resultant suspension which was kept stirred, a solution of 1.0 g of polyethylene glycol with a molecular weight of about 8,500 in 100 g of water was added. Separately, a suspension was prepared by adding 400 g of mica 1 to 15 µm in grain size to a solution of 4 g of polyethylene glycol in 2,000 g of water. To this suspension, the aforementioned suspension of ultramarine blue was added at a rate of 4 to 6 ml/min. The resultant mixture was filtered and the solid consequently separated, in a state not washed with water, was dried at a temperature in the range of 110° to 140 °C. Consequently, there was obtained a blue flaky pigment. Example 3: In 50 g of water, 5 g of polyethylene glycol having a molecular weight of about 6,000 was dissolved by heating. In the solution so produced, 10 g of iron blue was finely divided and dispersed with the aid of a sand mill. To the suspension, a solution prepared by dissolving 3 g of polyethylene glycol in 300 g of water by heating was added. Separately, 190 g of mica 1 to 15 µm in grain size was suspended in a solution of 3 g of polyethylene glycol in 1,500 g of water. To the resultant suspension which was kept stirred, the aforementioned suspension of pigment was added at a rate of 3 ml/min. The produced mixture was filtered and the separated solid was dried at a temperature of 100° to 120 °C. Consequently, there was obtained a blue flaky pigment. Example 4: A pigment was prepared by following the procedure of Example 1, except that talc was used as a flaky substrate in the place of mica. Example 5: A pigment was prepared by following the procedure of Example 3, except that talc was used as a flaky substrate in the place of mica. Example 6: A pigment was prepared by following the procedure of Example 1, except that red oxide was used as a pigment in the place of ultramarine blue. Example 7: A pigment was prepared by following the procedure of Example 1, except that yellow iron oxice was used as a pigment in the place of ultramarine blue. Example 8: A pigment was prepared by following the procedure of Example 1, except that chromium oxide was used as a pigment in the place of ultramarine blue. Example 9: A pigment was prepared by following the procedure of Example 1, except that a pearl pigment obtained by depositing titanium dioxide on mica was used as a flaky substrate in the place of mica. Example 10: A pigment was prepared by following the procedure of Example 1, except that polyvinyl pyrrolidone with a molecular weight of about 18,000 was used in the place of polyethylene glycol. Under an electron microscope, each of the pigments obtained in the preceding working examples was found to have fine particles of inorganic pigment deposited fast on a flaky substrate. The flaky pigment covered with an inorganic pigment, when used in cosmetic articles such as cheek rouge and eye shadow, exhibits outstanding spreading property and adhering property to the skin. Example 11: In 52 g of concentrated sulfuric acid, 2.5 g of phthalocyanine blue was dissolved. This solution was gradually added to 500 g of an aqueous 60 wt% sulfuric acid solution to prepare a sulfuric acid slurry of phthalocyanine. In the resultant suspension, 150 g of mica coated with titanium dioxide (about 50 % by weight) was thoroughly mixed. The suspension was intimately mixed with a solution of 10 g of polyethylene glycol with a molecular weight of about 8,500 in 2.5 liters of hot water at 50° to 60 °C and the resultant mixture was kept stirred at the same temperature for 20 minutes. The mixture so produced was left cooling to room temperature, then filtered, and washed with water. The solid so separated was dried at a temperature in the range of 120° to 140 °C. Consequently, there was obtained a pigment possessing a blue luster. Example 12: A dispersion having 0.3 g of phthalocyanine blue dispersed in a solution of 3.0 g of anhydrous aluminium chloride in 30 g of ethanol and a suspension having 15 g of mica coated with titanium dioxide (about 50 % by weight) suspended in a solution of 3 g of polyethylene glycol in 50 g of ethanol were thoroughly mixed. The resultant mixture was dispersed in a solution of 5 g of polyethylene glycol in 500 ml of hot water and stirred therein for five minutes. The resultant dispersion was left cooling to room temperature, filtered, and washed with water. When the resultant solid was dried at a temperature of 120° to 140 °C, there was obtained a pigment possessing a blue luster. When the pigments obtained in Example 11 and Example 12 were independently mixed in a toluene-water two-phase system and then left standing at rest, they passed into the toluene phase (organic layer). This experiment evinces that the pigments are hydrophobic because of the adhesion of organic pigments to the titanium dioxide mica composite. Under an electron microscope, the pigment produced as described above was found to have fine particles of organic pigment deposited on the flaky substrate. Example 13: In 20 g of dimethyl formamide, 0.2 g of Helindon Pink was dissolved by heating. The resultant solution was thoroughly mixed with a suspension of 10 g of mica in 50 g of ethanol. The suspension so obtained was stirred in a solution of 4 g of polyethylene glycol with a molecular weight of about 8,500 in 200 g of hot water. The mixture obtained consequently was filtered. The solid separated was washed with water and dried at a temperature of 110° to 140 °C. Consequently there was obtained a red flaky pigment. Example 14: In 130 g of water, 3.0 g of polyethylene glycol having a molecular weight of about 6,000 was dissolved by heating. In a sand mill, the solution and 14 ml of ethanol and 25 g of Helindon Pink added thereto were kneaded to effect dispersion of pigment. To the resultant suspension which was kept stirred, a solution of 1.0 g of polyethylene glycol in 189 g of water and 1.5 g of ethanol was added. Separately, a suspension was prepared by adding 500 g of mica 1 to 15 µm in grain size to a solution of 5.5 g of polyethylene glycol in 2,500 g of water and 80 g of ethanol. To this suspension, the aforementioned suspension of organic pigment was added at a rate of 6 to 7 ml/min. Then, the resultant mixture was filtered and the separated solid, in a state not washed with water, was dried at a temperature of 110° to 140 °C. Consequently, there was obtained a red flaky pigment. Example 15: A yellow flaky pigment was obtained by following the procedure of Example 14, except that Hanza Yellow was used in the place of Helindon Pink. Example 16: A blue flaky pigment was obtained by following the procedure of Example 14, except that phthalocyanine blue was used in the place of Helindon Pink. Example 17: A red flaky pigment was obtained by following the procedure of Example 14, except that mica having about 17 % by weight of iron oxide deposited thereon was used in the place of mica. Example 18: A yellow flaky pigment was obtained by following the procedure of Example 15, except that mica having about 11 % by weight of yellow iron oxide deposited thereon was used in the place of mica. Example 19: A red flaky pigment was obtained by following the procedure of Example 14, except that Red No. 202 was used in the place of Helindon Pink. Example 20: In 60 g of water, 3 g of polyethylene glycol having a molecular weight of about 20,000 was dissolved. In a sand mill, the solution and 5 g of Hanza Yellow were mixed to effect dispersion. Separately, in a solution of 3 g of polyethylene glycol in 300 ml of water, 100 g of mica 1 to 15 µm in grain size was suspended. To the suspension which was kept heated at 15° to 50 °C and stirred, the aforementioned suspension of organic pigment was added. The resultant mixture was filtered and the separated solid was dried at 110° to 140 °C. Consequently, there was obtained a yellow flaky pigment. Example 21: A yellow flaky pigment was obtained by following the procedure of Example 20, except that talc not more than 20 µm in grain size was used in the place of mica. Example 22: In 150 g of water, 0.30 g of polyvinyl alcohol (#500 with a molecular weight of about 27,000) and 3.0 g of polyethylene glycol having a molecular weight of 6,000 were dissolved by heating. In a sand mill, the solution and 10 g of Helindon Pink added thereto were mixed to effect dispersion. Separately, a suspension was prepared by adding 200 g of mica 1 to 15 µm in grain size to a solution o 2.5 g of polyethylene glycol in 1,300 g of water. To the suspension which was kept stirred, the aforementioned dispersion of organic pigment was added. The solid which educed in the mixture was separated by filtration and dried at 105° to 140 °C. Consequently, there was obtained a red flaky pigment. Example 23: A red flaky pigment was obtained by following the procedure of Example 22, except that polyvinyl pyrrolidone was used in the place of polyvinyl alcohol. Under an electron microscope, each of the pigments obtained in the preceding examples was found to have fine particles of organic pigment deposited fast on a flaky substrate. The flaky pigment covered with an organic pigment prepared as described above, when used in cosmetic articles such as cheek rouge and eye shadow, exhibits excellent spreading property and adhering property to the skin.

Claims: Flaky coloured pigments comprising a flaky substrate with a width and length of about 1 - 30 µm and a thickness of about 0.1 - 1 µm, the surface of which is covered by a finely divided colour pigment, which is optionally comminuted with the aid of a sand mill, a ball mill or a roll, the finally divided colour pigment, adhering uniformly to the flaky substrate by the use of an organic high molecular compound as a binder. A flaky pigment according to claim 1 characterized in that the flaky pigment contains about 0.5 to about 30 % by weight of the colour pigment and about 0.1 to about 10 % by weight of the binder. Process for the production of flaky coloured pigments characterized in that a flaky substrate is suspended in a dispersion or a solution of a finely divided colour pigment, which is optionally treated with a sand mill, a ball mill or a roll, that the resulting suspension is mixed with a solution of an organic high molecular compound and that the organic high molecular compound and the colour pigment are caused to precipitate onto the flaky substrate. Use of the flaky coloured pigments according to claim 1 in cosmetics.

Inventors: NOGUCHI, TAMIO, WATANABE, TAKAJI
Applicants: MERCK PATENT GESELLSCHAFT MIT BESCHRAENKTER HAFTUNG
Application year: 1986
Main classification: C09B63
IPC codes: A61Q1, C09B67, C09C3, C09C1, A61K8, C08J7, C04B14, C09B63