NEW COLOURED AND COLOURLESS THIN FILLERPIGMENT AND THE METHOD FOR PREPARATION THEREOF

Abstract: The application concerns a flaky color pigment and a pro­ cess for it's production. the pigment comprising a fine flaky powder as base material, and zinc oxide and an inorganic color pigment attached to the surface thereof.

Description: This invention relates to novel, flaky color pigment and to processes for producing the same. More particularly, it relates to novel, flaky color pigment comprising fine flaky powder with a particle size range of 1 to 200 µm, and zinc oxide and an inorganic color pigment attached to the surface thereof, whereby the inorganic color pigment is adhered to the inner or outer surface of zinc oxide. Flaky pigments are often used in the production of cosmetics. It is known that the properties of these pigments could be improved with respect to adhesion, extension on the skin and also with respect to gloss and transparency by different processes for producing. These pigments always consist of a base material and several coatings. Transparent colored pigments are based on platelet-shaped transparent substrates such as mica, talc or glass which are coated with a colored metal oxide or metal hydroxide. In DE-A-1 467468 the precipitation and deposition procedure of flaky substrates with a layer of zinc oxide which can contain a colored metal oxide is discussed, however an adhesion of a finely divided inorganic color pigment is not mentioned. A completely different pigment with high transparency, dispersibility and gloss is described in EP-A-0077959. These transparent color pigments are based on transparent base substrates which are coated with a metal oxide or metal hydroxide layer characterized that the metal oxide or metal hydroxide layer contains traces of an alkaline earth compound. The flaky base substrate is coated with a continuous layer of colored metal oxide which is formed by precipitation and deposition in the suspension of the flaky substrate. Zinc oxide like other colorless metal oxides can be used as a codeposit within the colored metal oxide layer and not as a separate coating. In EP-A-142695 the coating with barium sulfate is discussed followed by a further coating with a colorless or colored metal oxide. This additional layer is also formed by precipitation and deposition in the suspension of the flaky substrate. Coating with zinc oxide and a further adhesion of a finely divided unorganic color pigment is not mentioned. Accordingly it is object of this invention to markedly improve the prior art pigments in view of unique color tone, necessary adhesion, gloss and transparency. We have succeeded in producting novel, flaky color pigment comprising fine flaky powder, and zinc oxide and an inorganic color pigment attached to the surface thereof. The flaky color pigment of this invention shows unique color tone not to be expected with conventional zinc oxide pigment or calamine, exhibits pearlescent gloss, is free from color segregation when used in, for example, lotions, and has fine particles of zinc oxide capable of absorbing ultraviolet rays attached to the surface thereof. With these outstanding characteristics, the flaky pigment of this invention is suitable as an ingredient of cosmetics, such as lotion and cream; particularly when used in place of calamine in conventional calamine lotions, it exhibits unusual effects (unique color tone with no trouble of color segregation). The flaky color pigment of this invention is a type of pigment using fine flaky powder as base material. Typical examples of this base material include muscovite, phlogopite, sericite, talc, kaolin and barium sulfate. Besides these, fine flaky particles with an inorganic color pigment attached thereto, for example, mica-titanium oxide and micairon oxide complexes, may also be used as the base material. The particles size of this base material is 1 to 200 µm, preferably 3 to 70 µm. The flaky color pigment of this invention may be produced from this base material in various ways. Typical methods provided by this invention are as described below. (A) A process which comprises suspending fine flaky powder in water; treating the suspension with (a) an aqueous solution of zinc salt of an organic or inorganic acid and (b) an aqueous solution of an alkali metal or ammonium hydroxide, carbonate or bicarbonate, or urea, so as to deposit zinc hydroxide or basic zinc carbonate on the surface of said fine flaky powder; further treating the powder with fine particles of an inorganic pigment so as to deposit it on the surface of said fine flaky powder; and collecting the resulting solid by filtration, followed by washing with water, drying and calcination. (B) A process which comprises suspending fine flaky powder in water; treating the suspension with (a) an aqueous solution of zinc salt of an organic or inorganic acid and (b) an aqueous solution of an alkali metal or ammonium hydroxide, carbonate or bicarbonate, or urea, so as to deposit zinc hydroxide or basic zinc carbonate on the surface of said fine flaky powder; collecting the resulting solid by filtration, followed by washing with water, drying and calcination; suspending the calcined powder thus obtained in water; and treating the suspended powder with fine particles of an inorganic color pigment so as to deposit it on the surface of said fine flaky powder. (C) A process which comprises suspending, in water, flaky pigment composed of fine flaky powder and fine particles of an inorganic pigment deposited on the surface thereof; treating the suspension with (a) an aqueous solution of zinc salt of an organic or inorganic acid and (b) an aqueous solution of an alkali metal or ammonium hydroxide, carbonate or bicarbonate, or urea, so as to deposit zinc hydroxide or basic zinc carbonate on the surface of said fine flaky powder; and collecting the resulting solid by filtration, followed by washing with water, drying and calcination. Each of the processes (A) to (C) is explained below in more detail. (1) In general operation of process (A), the fine flaky powder is suspended in 100 parts of water, the suspension was stirred at 0 to 100°C, preferably at 20 to 80°C, and 5 to 45 wt% aqueous solution of zinc salt of an organic or inorganic acid is added while controlling the pH within the range from 7.0 to 9.5 by using 5 to 45 wt% aqueous solution of an alkali metal or ammonium hydroxide, carbonate or bicarbonate, trhereby depositing zinc hydroxide or basic zinc carbonate on the surface of said fine flaky powder. To the suspension thus obtained, is added with stirring an aqueous suspension of inorganic pigment prepared, for example, by suspending, in about 0.5 to 20 parts of water, 10 parts of the fine flaky powder used above and about 0.05 to 2 parts of an inorganic pigment ( e.g., red iron oxide, cobalt blue and ultramarine blue ) finely pulverized by a sand mill or the like. The resulting solid is collected by filtration, washed with water, dried, and calcined at a temperature higher than 500°C. (2) Process (B) is a method suitable when using an inorganic pigment that is rather poor in thermal resistance, such as Prussian blue and yellow iron oxide. Zinc hydroxide or basic zinc carbonate is deposited on the surface of fine flaky powder in the same way as in process (A). After that, the solid matters are collected by filtration, washed with water, dried and calcined at a temperature higher than 500°C. The pigment thus obtained ( about 10 parts ) is then suspended in water ( 100 parts ). To this suspension is added with stirring an aqueous suspension of inorganic pigment prepared by suspending, in about 0.5 to 20 parts of water, about 0.05 to 2 parts of an inorganic pigment ( e.g., red iron oxide, cobalt blue and ultramarine blue ) finely pulverized by a sand mill or the like. The resulting solid is collected by filtration, washed with water, and dried. (3) In general operation of process (C), about 10 parts of flaky pigment, composed of fine flaky powder as base material and fine, inorganic color pigment deposited on the surface thereof, is suspended in 100 parts water, and this suspension is treated in the same manner as in process (A) to deposit zinc hydroxide or basic zinc carbonate. The resulting solid is collected by filtration, washed with water, dried and calcined at a temperature higher than 500°C. The above-mentioned aqueous solution of zinc salt of an organic or inorganic acid may also contain a titanium salt, such as titanium oxytitanate and titanium tetrachloride. Pigment with brighter gloss can be obtained by addition of such a titanium salt. Typical examples of the zinc salt (a) mentioned above include zinc sulfate, chloride, nitrate, oxalate and tartrate. Sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium carbonate, potassium carbonate and ammonium carbonate may be mentioned as examples of the alkali metal or ammonium hydroxide, carbonate or bicarbonate (b) mentioned above. Use of urea, which undergoes hot hydrolysis to form ammonia and carbon dioxide, gives the same result as when ammonium hydroxide or carbonate is used. Illustrative examples of the inorganic pigment include iron oxide pigment ( e.g., red, yellow and black iron oxides ), cobalt oxide pigment ( e.g., cobalt blue, cobalt green and cobalt violet ), ultramarine blue, Prusssian blue and manganese violet. The following Examples further illustrate the invention but are not intended to limit its scope. Example 1 Muscovite about 1 to 15 microns in diameter ( 300 g ) was suspended in 3000 ml water, the suspension was heated to 80°C, and a solution of 50 g titanyl sulfate ( TiOSO₄·2H₂O ) and 2 g conc. sulfuric acid in 330 ml water was added to the suspension over a period of 30 minutes, while maintaining the pH within the range from 1.8 to 2.2 by addition of 15 wt% aqueous solution of ammonium carbonate. The pH was raised to 5.0 to 6.0 by adding 15 wt% aqueous solution of ammonium carbonate, 500 g of 28 wt% aqueous solution of zinc nitrate was added over a period of two hours while maintaining the pH within the range from 5.0 to 8.0 by addition of 15 wt% aqueous solution of ammonium carbonate. To the resulting suspension was added with stirring 4 g of red iron oxide finely pulverized by a sand mill, and the precipitate which separated out was collected by filtration, washed with water to remove soluble salts, dried at about 105 to 110°C, and calcined at 650 to 670°C for one hour. The pink pigment thus obtained was found to have titanium oxide, zinc oxide and iron oxide pigment deposited on the surface of muscovite. Example 2 Muscovite about 5 to 20 microns in diameter ( 300 g ) was suspended in 3000 ml of water, the suspension was heated to 80°C, and a solution of 50 g titanyl sulfate ( TiOSO₄·2H₂O ) and 2 g conc. sulfuric acid in 330 ml water was added to the suspension over a period of 30 minutes, while maintaining the pH within the range from 1.8 to 2.2 by addition of 15 wt% aqueous solution of potassium carbonate. The pH was raised to 5.0 to 6.0 by adding 15 wt% aqueous solution of potassium carbonate, and 500 g of 20 wt% aqueous solution of zinc chloride was added over a period of two hours while maintaining the pH within the range from 5.0 to 8.0 by addition of 15 wt% aqueous solution of potassium carbonate. To this suspension was added with stirring 4 g of red iron oxide finely pulverized by a sand mill, and the precipitate which separated out was collected by filtration, washed with water to remove soluble salts, dried at about 105 to 110°C, and calcined at 650 to 670°C for one hour. The pink pigment thus obtained was found to have titanium oxide, zinc oxide and iron oxide pigment deposited on the surface of muscovite. Example 3 Muscovite about 1 to 15 microns in diameter ( 300 g ) was suspended in 3000 ml of water, the suspension was heated to 80°C, and a solution of 50 g titanyl sulfate ( TiOSO₄·2H₂O ) and 2 g conc. sulfuric acid in 330 ml water was added to the suspension over a period of 30 minutes with stirring, while maintaining the pH within the range from 1.8 to 2.2 by addition of a 1:1 mixture of 15 wt% aqueous solution of potassium carbonate and 15 wt% aqueous solution of potassium bicarbonate. The pH was raised to 5.0 to 6.0 by adding the same mixture of alkaline solution as above, and 500 g of 28 wt% aqueous solution of zinc nitrate was added over a period of two hours while maintaining the pH within the range from 5.0 to 6.0 by addition of the same mixture of alkaline solutions as above. To this suspension was added with stirring 4 g of red iron oxide finely pulverized by a sand mill, and the precipitate which separated out was collected by filtration, washed with water to remove soluble salts, dried at about 105 to 110°C, and calcined at 650 to 670°C for one hour. The pink pigment thus obtained was found to have titanium oxide, zinc oxide and iron oxide pigment deposited on the surface of muscovite. Example 4 Muscovite about 1 to 1.5 microns in diameter ( 300 g ) was suspended in 3000 ml water, 300 g of urea and a solution of 100 g zinc nitrate, 30 g titanyl sulfate ( TiOSO₄·2H₂O ) and 2 g conc. sulfuric acid in 300 ml water were added to this suspension over a period of 30 minutes, and the mixture was heated at 90 to 98°C for 4.5 hours with stirring. After the pH was raised to 7.5 to 9.5 by adding 15 wt% aqueous solution of sodium carbonate, 4 g of red iron oxide finely pulverized by a sand mill was added with stirring, and the precipitate which separated out was collected by filtration, washed with water to remove soluble salts, dried at about 105 to 110°C, and calcined at 650 to 670°C for one hour. The pink pigment thus obtained was found to have titanium oxide, zinc oxide and iron oxide pigment deposited on the surface of muscovite. Example 5 Muscovite about 5 to 20 microns in diameter ( 100 g ) was suspended in 1000 ml water, the suspension was heated to 80°C, and 300 g of 25 wt% aqueous solution of zinc nitrate containing 1 g conc. nitric acid was added to this suspension over a period of two hours with stirring, while maintaining the pH within the range from 7.0 to 8.5 by addition of 20 wt% aqueous solution of potassium carbonate. To the resulting suspension was added 10 g of aqueous suspension of 4 g red iron oxide finely pulverized by a sand mill. The precipitate which separated out was collected by filtration, washed with water to remove soluble salts, dried at about 105 to 110°C, and calcined at 650 to 670°C for one hour. The pink pigment thus obtained was found to have zinc oxide and iron oxide pigment deposited on the surface of muscovite. Example 6 Pink pigment was produced in the same manner as in Example 5 except that talc about 1 to 20 microns in diameter was used in place of muscovite. Example 7 Muscovite about 5 to 20 microns in diameter ( 300 g ) was suspended in 3000 ml water, the suspension was heated to 80°C, and 330 ml of an aqueous solution containing 50 g titanyl sulfate ( TiOSO₄·2H₂O ) and 2 g conc. sulfuric acid was added to the suspension over a period of 30 minutes with stirring, while maintaining the pH within the range from 1.8 to 2.2 by addition of 15 wt% aqueous solution of potassium carbonate. After the pH was raised to 5.0 to 6.0 by adding 15 wt% aqueous solution of potassium carbonate, 500 g of 28 wt% aqueous solution of zinc nitrate containing 1 g conc. nitric acid was added over a period of two hours while maintaining the pH within the range from 7.0 to 8.5 by addition of 15 wt% aqueous solution of potassium carbonate. To this suspension was added with stirring 5 g of cobalt blue ( CoB ) finely pulverized by a sand mill, and the precipitate which separated out was collected by filtration, washed with water to remove soluble salts, dried at about 105 to 110°C, and calcined at 650 to 670°C for one hour. The whitish-blue pigment thus obtained was found to have zinc oxide and cobalt blue deposited on the surface of mica-titanium oxide base material. Example 8 Mica/titanium oxide complex assuming blue interference color ( 150 g ), prepared by coating muscovite about 10 to 60 microns in diameter with about 50 wt% of titanium oxide, was suspended in 1.5 liters of water, the suspension was heated to 80°C, and 250 g of 42 wt% aqueous solution of zinc nitrate was added to this suspension over a period of 80 minutes with stirring, while maintaining the pH within the range from 8.0 to 9.0 by addition of 30 wt% aqueous solution of potassium carbonate. The solid was collected by filtration, washed with water to remove soluble salts, dried at about 105 to 110°C for 18 hours, and calcined at 650°C for one hour. The pigment assuming blue interference color thus obtained was found to have fine powder of zinc oxide deposited on the surface of muscovite/titanium oxide base material. Example 9 Reddish brown, mica/iron oxide complex ( 50 g ), prepared by coating muscovite about 10 to 60 microns in diameter with about 45 wt% of iron titanium oxide, was suspended in 700 ml of water, the suspension was heated to 80°C, and 80 g of 28 wt% aqueous solution of zinc nitrate was added to this suspension over a period of 80 minutes with stirring, while maintaining the pH within the range from 8.0 to 9.0 by addition of 30 wt% aqueous solution of potassium carbonate. The solid was collected by filtration, washed with water to remove soluble salts, dried at about 105 to 110°C for 18 hours, and calcined at 650°C for one hour. The light reddish-brown pigment thus obtained was found to have fine powder of zinc oxide deposited on the surface of muscovite/iron oxide base material. Example 10 Silver-colored mica/titanium oxide complex ( 300 g ), prepared by coating muscovite about 5 to 20 microns in diameter with about 35 wt% of titanium oxide, was suspended in 3 liters of water, the suspension was heated to 80°C, and 500 g of 42 wt% aqueous solution of zinc nitrate was added to this suspension over a period of 80 minutes with stirring, while maintaining the pH within the range from 8.0 to 9.0 by addition of 30 wt% aqueous solution of potassium carbonate. To the resulting suspension was added with stirring a suspension of 36 g silica-treated ultramarine blue finely pulverized with a sand mill in 150 ml of water, and the solid was collected by filtration, washed with water to remove soluble salts, dried at about 105 to 110°C, and calcined at 650°C for one hour under a nitrogen stream. The light blue, glossy pigment thus obtained was found to have zinc oxide and ultramarine blue deposited on the surface of muscovite/titanium oxide. It was confirmed by electron-microscopic observation that the pigment obtained in the Examples described above consists of fine flaky powder, and fine particles of zinc oxide and inorganic color pigment attached to the surface thereof. It was also ascertained that the novel, flaky color pigment thus prepared, when used in cosmetics ( especially in lotions ), is better than conventional zinc oxide pigment and calamine, particularly in gloss, brightness, as well as in spreadability on, and adhesion to, the skin.

Claims: 1. Flaky color pigment comprising fine flaky powder with a particle size range of 1 to 200 µm, and zinc oxide and an inorganic color pigment attached to the surface thereof,whereby the inorganic color pigment is adhered to the inner or outer surface of zinc oxide. 2. Flaky color pigment as defined in claim 1, wherein the amount of said zinc oxide is in the range from 5 to 70% based on the weight of the total flaky color pigment. 3. Process for producing flaky color pigment, which comprises suspending fine flaky powder in water; treating the suspension with (a) an aqueous solution of zinc salt of an organic or inorganic acid and (b) an aqueous solution of an alkali metal or ammonium hydroxide, carbonate or bicarbonate, or urea, so as to deposit zinc hydroxide or basic zinc carbonate on the surface of said fine flaky powder; further treating the powder with fine particles of said inorganic pigment so as to deposit it on the surface of said fine flaky powder; and collecting the resulting solid by filtration, followed by washing with water, drying and calcination. 4. Process for producing flaky color pigment, which comprises suspending fine flaky powder in water; treating the suspension with (a) an aqueous solution of zinc salt of an organic or inorganic acid and (b) an aqueous solution of an alkali metal or ammonium hydroxide, carbonate or bicarbonate, or urea, so as to deposit zinc hydroxide or basic zinc carbonate on the surface of said fine flaky powder; collecting the resulting solid by filtration, followed by washing with water, drying and calcination; suspending the calcined powder thus obtained in water; and treating the suspended powder with fine particles of an inorganic color pigment so as to deposit it on the surface of said fine flaky powder. 5. Process for producing flaky color pigment, which comprises suspending, in water, flaky pigment composed of fine flaky powder and fine particles of an inorganic pigment deposited on the surface thereof; treating the suspension with (a) an aqueous solution of zinc salt of an organic or inorganic acid and (b) an aqueous solution of an alkali metal or ammonium hydroxide, carbonate or bicarbonate, or urea, so as to deposit zinc hydroxide or basic zinc carbonate on the surface of said fine flaky powder; and collecting the resulting solid by filtration, followed by washing with water, drying and calcination. 6. Flaky pigment comprising fine flaky powder with a particle size range of 1 to 200 µm as base material, and zinc oxide attached to the surface thereof. 7. Process for producing a flaky pigment according to claim 6, which comprises suspending fine flaky powder in water; treating the suspension with (a) an aqeous solution of zinc salt of an organic or inorganic acid and (b) an aqeous solution of an alkali metal or ammonium hydroxide, carbonate or bicarbonate, or urea, so as to deposit zinc hydroxide or basic zinc carbonate on the surface of said fine flaky powder; collecting the resulting solid by filtration, followed by washing with water, drying and calcination.

Inventors: NOGUCHI, TAMIO, WATANABE, TAKAJI
Applicants: MERCK PATENT GESELLSCHAFT MIT BESCHRAENKTER HAFTUNG
Application year: 1987
Main classification: C09C1
IPC codes: C09B67, C09C1, C09C3