Patent Description:
Pigments are of great importance in the cosmetic field, where altering skin and hair color for aesthetic purposes can be desirable.

However, some pigments used in cosmetics have problems in that when applied to cosmetics requiring various environments, they are already discolored during a formulation process due to unstable properties of the dye itself, or have weak stability against light. Thus, in order to solve such problems, various methods such as emulsification, encapsulation and the like have been developed.

Meanwhile, the capsule applied to cosmetics should be easily cracked or broken under pressure when a user applies to a skin according to its use, so that the pigment contained in the capsule can be easily expressed.

That is, there is a need for a capsule which can effectively isolate a pigment from external environment and thus exhibits excellent storage durability, color hiding power, etc., and which can be easily cracked or broken by pressing, rubbing, wiping or scrubbing with a hand or a tool (cotton cloth, sponge, paper, brush, etc.), thereby allowing the pigment included therein to develop color sufficiently.

<CIT> relates to microcapsules for a cosmetic composition which allow the separation of the encapsulated material from the composition. This document namely discloses microcapsules that comprise a core of mannitol, said core being coated with a titanium dioxide particle layer, itself being coated with a silica charged layer and further with an outer polymethacrylate layer.

In order to solve the above-mentioned problems, the present inventors have developed a spherical capsule structure in which silica and a pigment are mixed by using a polymer as a binder, in order that the capsule is stable at a high temperature and does not easily crack or break during the formulation process and thereby stably maintains the pigment, but when the formulation is applied to the skin, the capsule breaks and thereby causes color development.

Therefore, it is one object of the present invention to provide a capsule structure including a pigment, capable of causing color development of the pigment only when applied to the skin, while protecting the pigment from the external environment and ensuring the stability of the pigment.

In order to achieve the object above, one aspect of the present disclosure provides a pigment capsule including a pigment, said piment capsule consisting of an interior and a barrier membrane,.

The present invention also relates to a method for producing the same.

The capsule of the present invention can solve the problem related to instability of the other pigment against the environment by completely isolating this pigment from the external environment, and also, the capsule is stable during the formulation process, but when applied to the skin, it is easily cracked or broken by force applied while rubbing or scrubbing with a hand or a tool, thereby causing color development easily.

Further, the color development of the other pigment is blocked and thus the color due to this pigment does not appear in the product, but the color development occurs after the capsule is applied to the skin, which may arouse users' interests when using the product.

The present invention provides a pigment capsule including a pigment and consisting of an interior and a barrier membrane wherein silica, a titanium dioxide pigment and another pigment are dispersed in an interior of the capsule and wherein the barrier membrane is formed by a polymer binder having a glass transition temperature of <NUM> or higher and being an acrylate copolymer, and a method for producing the same.

In particular, the pigment capsule of the present invention is characterized by having physical properties of maintaining its stability during formulation or storage of the formulated products, but being easily cracked or broken by the pressure at the moment of application to the skin.

The pigment capsule of the present invention has an average diameter of <NUM> to <NUM>, preferably <NUM> to <NUM>, and the pigment capsule according to the present invention may be easily cracked or broken, ruptured, dissolved or disintegrated by a small pressure, that is, the pressure generally applied when pressed, rubbed, wiped or scrubbed with a hand or a tool (cotton cloth, sponge, brush, etc.).

In the present invention, in particular, fumed silica (silica dimethyl silylate) is used as the silica.

In addition, in order to increase the hardness of the capsule for the purpose of completely isolating the other pigment from the external environment and securing physical stability thereof, the present invention provides a capsule in which the titanium dioxide pigment, the other pigment and silica are dispersed inside thereof, and a barrier membrane from the exterior is formed by the polymer binder.

In many cases, a makeup cosmetic composition is subjected to a high temperature during the formulation process, and in particular, a composition for lip makeup such as lipstick is mainly formulated at a high temperature (for example, <NUM> or higher) due to the nature of the mixing process of raw materials, and thus it is very important to secure thermal stability of the capsule. Therefore, the polymer binder in the present invention has a glass transition temperature (Tg) of <NUM> or higher and is an acrylate copolymer.

In addition, the purpose of the pigment capsule in the present invention is that discoloration of the other pigment in the capsule does not occur until the product is applied by a user, and thus, the discoloration of the other pigment should not occur due to the polymer used.

Therefore, the polymer binder used in the present invention is chosen among those that do not cause discoloration of the other pigment, while having a high glass transition temperature (<NUM> or higher). In order to satisfy such a condition, an acrylate copolymer, in particular, a polymethacrylate-based copolymer, is used in the present invention, preferably acrylic acid and acrylate copolymer, more preferably acrylic acid and methacrylate copolymer, and in particular, methacrylic acid and methacrylate copolymer are used.

The polymer binder used in the present invention could be used up to <NUM>% by weight based on the total weight of the capsule. However, when the polymer binder is used in an excessive amount, the contents of silica, titanium dioxide pigment, and the other pigment become relatively small, so that the shape of the capsule may not be spherical and become distorted, and it may not crack or break when rubbed by a hand. Therefore, in consideration of these factors, the content of the polymer binder is <NUM> to <NUM>% by weight, preferably <NUM> to <NUM>% by weight based on the total weight of the capsule.

The other pigment used in the present invention is not particularly limited by its type, such as water-soluble dyes and oil-soluble dyes. For example, the following other pigments may be used.

As specific examples of organic dyes, those having the following trade names may be mentioned:.

In particular, as the pigment capsule according to the present invention, the other pigment such as oil-soluble dye Red <NUM>, which exhibits a difference in color expression under humidity changes and alkaline conditions, thus having poor stability, may also be used.

In the pigment capsule of the present invention, the other pigment could be used up to <NUM>% by weight based on the total weight of the capsule. However, when the other pigment is used in an excessive amount, the contents of the polymer binder forming the capsule exterior become relatively small, and thus, the other pigment cannot be completely protected from the external environment, thereby causing a problem in stability of the other pigment. Therefore, in consideration of these factors, the content of the other pigment is <NUM> to <NUM>% by weight based on the total weight of the capsule.

Further, the pigment capsule of the present invention contains a C<NUM>-C<NUM> trivalent carboxylic acid, said C<NUM>-C<NUM> trivalent carboxylic acid being selected from the group consisting of citric acid, iso-citric acid, aconitic acid, tricarballylic acid, and trimesic acid inside thereof. By containing such a C<NUM>-C<NUM> trivalent carboxylic acid, the pH of the capsule interior can be maintained under an acidic condition, thereby preventing discoloration of the other pigment due to contact with an alkali oil. The content of the C<NUM>-C<NUM> trivalent carboxylic acid could not be particularly limited as long as it prevents discoloration of the other pigment and thereby does not alter the exterior color of the capsule, and in particular, when formulated into a cosmetic composition for lip makeup, as long as it is suitable for the pH standard of the composition. In the present invention, the C<NUM>-C<NUM> trivalent carboxylic acid is added in an amount of <NUM> to <NUM>% by weight, preferably <NUM> to <NUM>% by weight based on the total weight of the capsule. When the amount is less than <NUM>% by weight, it may be insufficient to prevent the discoloration of the other pigment, and when the amount is more than <NUM>% by weight, the difference in the effects due to an increase in the content is insignificant.

The present invention provides a method for producing the pigment capsule including a pigment, this pigment capsule being as disclosed above, the method including the steps of:.

In the method of the present invention, the step of dissolving the polymer binder and the other pigment is characterized by dissolving each of the polymer binder and the other pigment in different solvents so that the both can be sufficiently, completely dissolved, preferably to the extent of <NUM>%, and then mixing and using them, while preventing color development of the other pigment.

As the polymer binder and the other pigment used in the present invention, those described above can be used.

As the solvent for dissolving the polymer binder, an organic solvent, preferably, at least one organic solvent selected from the group consisting of a C<NUM>-C<NUM> lower alcohol (for example, methanol, ethanol, isopropanol, butanol, etc.), acetone, and a mixture thereof, or a mixture of the organic solvent and water, for example, methanol, methanol/water (<NUM>:<NUM>), ethanol, ethanol/water (<NUM>:<NUM>), isopropanol, isopropanol/water (<NUM>:<NUM>), isopropanol/water (<NUM>:<NUM>), N-butanol, acetone, acetone/water (<NUM>:<NUM>), acetone/water (<NUM>:<NUM>), acetone/isopropanol (<NUM>:<NUM>) may be used, more preferably, ethanol or acetone may be used.

Further, as the solvent for dissolving the other pigment, a chlorine-containing hydrocarbon-based organic solvent, preferably chloroform, dichloromethane (DCM), and more preferably dichloromethane (DCM) may be used.

In the method of the present invention, the ratio of the solvent for dissolving the polymer binder to the solvent for dissolving the other pigment is about <NUM>:<NUM>. When the ratio of the solvent is less than about <NUM>:<NUM> (for example, <NUM>:<NUM>, <NUM>:<NUM>, etc.), the polymer binder may be precipitated, and when the ratio of the solvent is greater than about <NUM>:<NUM>, (for example, <NUM>:<NUM>, <NUM>:<NUM>, <NUM>:<NUM>, etc.), discoloration of the other pigment may occur, which is not preferred.

When the polymer binder is dissolved in a solvent, the C<NUM>-C<NUM> trivalent carboxylic acid, preferably, citric acid, or tricarballylic acid may be added thereto. By containing the C<NUM>-C<NUM> trivalent carboxylic acid, the pH of the capsule interior can be maintained under an acidic condition, thereby preventing discoloration of the other pigment due to contact with an alkali oil. At this time, the content of the C<NUM>-C<NUM> trivalent carboxylic acid, which prevents discoloration of the other pigment and thereby does not alter the exterior color of the capsule, is contained in an amount of <NUM> to <NUM>% by weight based on the total weight of the capsule. When the amount is less than <NUM>% by weight, it may be insufficient to prevent the discoloration of the other pigment, and when the amount of more than <NUM>% by weight, the difference in the effects due to an increase in the content is insignificant.

Spray drying may be carried out under the following conditions: Feed rate - amount of air fed to twin-fluid nozzle: <NUM>/min, amount of dispersion fed: <NUM>/min; Environmental conditions - temperature of dispersion (reaction solution): <NUM>, spray dryer inlet temperature: <NUM>, spray dryer outlet temperature: <NUM>. At this time, spray drying may be performed while stirring the mixed polymer solution continuously through a stirrer.

The pigment capsule prepared according to the present invention isolates the other pigment from the external environment and does not cause color development of the other pigment before application of the final product, for example, cosmetics, to the skin, and also, it contains titanium dioxide pigment in the pigment capsule to mask the inherent color of the other pigment, thereby rendering the color of the formulation itself to become close to colorless. That is, it causes color development when the product which is close to colorless, is applied to the skin, and thus, it is also possible to increase interest and attention during make-up.

Hereinafter, the constitutions and effects of the present invention will be described in detail by way of Examples and Test Examples shown below. However, these Examples and Test Examples are given for illustrative purposes only to help understanding of the present invention, and the scope of the invention is not intended to be limited to or by these Examples and Test Examples.

Red <NUM> Lake (<NUM>, <NUM>%) was dispersed in dichloromethane (DCM, <NUM>). Citric acid (<NUM>, <NUM>%) was dissolved in ethanol (<NUM>) heated to <NUM>, and then an acrylate copolymer as a polymer binder (Eudragit® L <NUM>, manufactured by Evonik Degussa; <NUM>, <NUM>%) was dissolved therein. At this time, the volume ratio of ethanol used for dissolving the polymer binder (excluding the volume of ethanol used for dissolving citric acid) and dichloromethane used for dissolving the other pigment was <NUM>:<NUM>. The mixed dispersion solution of citric acid and acrylate copolymer was cooled to <NUM> or less and mixed with the Red <NUM> Lake solution. Then, silica (AEROSIL® R972, manufactured by Evonik Degussa; <NUM>, <NUM>%) and TiO<NUM> (Purolan® E 171A, manufactured by LANXESS; <NUM>, <NUM>%) were added to the mixed dispersion solution, and dispersed as follows: a dispersion vessel was introduced into an ultrasonic dispersion bath and the solution was dispersed for <NUM> minutes using a disperser. Then, the resultant was dried using a spray dryer (DJE-FCNM 020R, manufactured by DONGJIN TECHNOLOGY INSTITTUTE, capacity: <NUM>/hr (H<NUM>O basis)) and encapsulated.

A pigment capsule was prepared in the same manner as in Example <NUM>, except that <NUM> (<NUM>%) of acrylate copolymer was used.

A pigment capsule was prepared in the same manner as in Example <NUM>, except that <NUM> (<NUM>%) of acrylate copolymer was used, and <NUM> (<NUM>%) of Red <NUM> Lake was used.

Red <NUM> Lake (<NUM>, <NUM>%) was dispersed in dichloromethane (DCM, <NUM>). Citric acid (<NUM>, <NUM>%) was dissolved in ethanol (<NUM>) heated to <NUM>, and then an acrylate copolymer as a polymer binder (Eudragit® L <NUM>, manufactured by Evonik Degussa; <NUM>, <NUM>%) was dissolved therein. At this time, the volume ratio of ethanol used for dissolving the polymer binder (excluding the volume of ethanol used for dissolving citric acid) and dichloromethane used for dissolving the other pigment was <NUM>:<NUM>. The mixed dispersion solution of citric acid and acrylate copolymer was cooled to <NUM> or below and mixed with the Red <NUM> Lake solution. Then, silica (AEROSIL® R972, manufactured by Evonik Degussa; <NUM>, <NUM>%) and TiO<NUM> (Purolan® E 171A, manufactured by LANXESS; <NUM>, <NUM>%) were added to the mixed dispersion solution, and dispersed as follows: a dispersion vessel was introduced into an ultrasonic dispersion bath and the solution was dispersed for <NUM> minutes using a disperser. Then, the resultant was dried using a spray dryer (DJE-FCNM 020R, manufactured by DONGJIN TECHNOLOGY INSTITTUTE, capacity: <NUM>/hr (H<NUM>O basis)) and encapsulated.

The capsules prepared in Examples and Comparative Examples were observed under a scanning electron microscope (SEM) (<FIG>).

<FIG> is an image showing the pigment-supported capsules. By applying the spray drying method, it was possible to support the pigment on the silica and to carry out encapsulation in such a manner that the polymer encapsulates the exterior thereof. Further, it was confirmed through the SEM image shown in <FIG> that the capsules were formed as porous polymer.

Furthermore, it was confirmed through <FIG>, which showed the state of capsules when the capsules of Example <NUM> were rubbed with fingers several times, that the pigment was developed as the capsule broke.

In addition, it was confirmed in <FIG> that Si, Ti, O, and Br elements contained in the polymer capsules were evenly distributed through EDX mapping, thereby confirming whether or not the pigment was impregnated.

<NUM> of ethylcellulose, polyvinylpyrrolidone (PVP), polycaprolactone (PCL), polylactic acid (PLA) or poly (methyl methacrylate) as a polymer was dissolved in <NUM> of DCM solution. Then, <NUM> of Red <NUM> dye was dissolved in in <NUM> of DCM. The two solutions were separately prepared and then mixed to observe the color change. The observation results are shown in <FIG>.

<FIG> (<NUM>) to (<NUM>) show that <NUM> cps, <NUM> cps, and <NUM> cps of ethyl cellulose were used, respectively. As the molecular weight increased, the color became darker.

Meanwhile, <FIG>) and (<FIG>) show that polyvinylpyrrolidone having molecular weights of <NUM>,<NUM> and <NUM>,<NUM> was used, respectively. As the molecular weight of the polyvinylpyrrolidone increased, the color became lighter.

Therefore, although there was a slight difference in color, it was ultimately observed that discoloration occurred regardless of the molecular weight of the polymer.

When PCL, PLA or crosslinked PMMA, which is a different type of polymer binder, was used, there was no discoloration of Red <NUM> Lake, but the glass transition temperature (Tg) was found to be <NUM> or less. Thus, the stability is not ensured at <NUM> or higher, which is the production temperature for common makeup cosmetics, in particular, cosmetics for lip makeup, and is therefore not suitable for application to the pigment capsules of the present invention (see, <FIG> (<NUM>) to (<NUM>)).

In general, makeup cosmetics, in particular, lip makeup cosmetics, are manufactured at high temperatures, thus, it was confirmed whether the capsules maintain stability at high temperatures.

Specifically, the capsules of Examples <NUM> to <NUM> having different contents of polymer and other pigment (polymer content of <NUM>% + other pigment content of <NUM>%, polymer content of <NUM>% + other pigment content of <NUM>%, polymer content of <NUM>% + other pigment content of <NUM>%, respectively) were heat-treated in an oven at <NUM> for <NUM> hour or <NUM> hours, and then the capsule state was observed under a scanning electron microscope (SEM). Observation results are shown in Table <NUM>, <FIG> (<NUM>-hour heat treatment) and <FIG> (<NUM>-hour heat treatment).

As shown in Table <NUM>, it can be confirmed that all pigment capsules prepared according to the present invention maintained the stability when the polymer was heat-treated at <NUM>, which is a high temperature, for <NUM> hour or <NUM> hours.

The hardness (cracking or breaking) of the pigment capsules according to the present invention was confirmed by the following method.

Specifically, the capsules of Examples <NUM> to <NUM> having different contents of polymer and other pigment (polymer content of <NUM>% + other pigment content of <NUM>%, polymer content of <NUM>% + other pigment content of <NUM>%, polymer content of <NUM>% + other pigment content of <NUM>%, respectively) were rubbed with a hand once, <NUM> times or <NUM> times, then, it was confirmed whether or not the capsules crack or broke. The cracking or breakage of the capsules was confirmed through SEM.

The evaluation results are shown in Table <NUM> and <FIG>.

As seen from the results of Table <NUM> and <FIG>, the higher the content of the polymer binder, the higher the hardness, and thus the capsules did not easily crack or break, and when rubbed by hand <NUM> times, the capsules are all broken and the color development occurred, confirming allowing color development to easily occur on the skin when a user makes up without a specific tool or device.

When the capsules were prepared into lipstick formulations, it was confirmed that the capsules remained intact after formulation testing without breakage (see, <FIG>).

It was confirmed that the capsules did not crack or break even when rubbed by hand <NUM> times, when ethyl cellulose as a type of polymer was used, or silica supported with iron oxide was used (see, <FIG>).

Lipstick formulations containing the pigment capsules according to the present invention were prepared with the compositions of Table <NUM> below. Formulation (a) contains non-encapsulated Red <NUM>, Formulations (b) to (d) contain encapsulated Red <NUM>. In particular, Formulation (b) contains <NUM>% of Red <NUM> + <NUM>% of polymer, Formulation (c) contains <NUM>% of Red <NUM> + <NUM>% of polymer + <NUM>% of citric acid, and Formulation (d) contains <NUM>% of Red <NUM> + <NUM>% of polymer + <NUM>% of citric acid.

The lipstick formulations prepared with the above compositions were applied to the skin of the back of the hand, and the degree of color development was observed. The results of the expression of exterior color and tinting strength on the skin of the polymer capsules are shown in <FIG>.

Upon comparison of <FIG> showing Formulation (a) containing non-encapsulated pigments and Formulation (b) containing encapsulated pigments, respectively, it can be seen that the expression of exterior color of the lipsticks could be suppressed only by encapsulating the pigments.

In addition, when citric acid was added to adjust the pH of the capsule interior to be acidic, the exterior color could be adjusted close to colorless as shown in <FIG>. In particular, it can be confirmed through <FIG> that using citric acid in an amount of <NUM>% by weight was found to be the optimal condition.

Meanwhile, the result of application of Formulations (a) to (d) to the skin are shown in (<NUM>) to (<NUM>) at the bottom of <FIG>, and it can be confirmed from the results that the tinting strength on the skin was maintained even when the exterior color of the formulations was suppressed.

Lipstick formulations containing the pigment capsules according to the present invention were prepared with the compositions of Table <NUM> below. Formulation (a) contains the capsule of Example <NUM>, Formulation (b) contains the capsule of Example <NUM>, Formulation (c) contains the capsule of Example <NUM>, and Formulation (d) contains the capsule of Example <NUM>.

The exterior of the lipstick formulations prepared with the above compositions was observed, and the degree of exterior color change according to the content of citric acid was observed. The results are shown in <FIG>.

As shown in <FIG>, when the content of Red <NUM> Lake was constant, the exterior color of the formulations did not significantly change even when the content of citric acid was increased.

Based on the results, it can be seen that when the content of citric acid reached a certain concentration level, the role of citric acid in color change was not significant.

Meanwhile, in order to confirm the degree of color change by citric acid in the non-encapsulated pigments, <NUM> of Red <NUM> Lake was dissolved in <NUM> of EtOH, and then <NUM>, <NUM>, <NUM>, <NUM> and <NUM> of citric acid was added (corresponding to <FIG> (<NUM>) to (<NUM>), respectively), and the color change of Red <NUM> Lake was observed. The results are shown in <FIG>.

As shown in <FIG>, it can be confirmed that when <NUM>, <NUM> and <NUM> of citric acid was added, respectively, relative to the equivalent amount of Red <NUM> Lake, the color of Red <NUM> Lake appeared almost the same.

A lipstick formulation containing no pigment (Formulation <NUM>), a lipstick formulation containing the pigment capsule (Red <NUM> Lake) according to the present invention (Formulation <NUM>), and a lipstick formulation containing a non-encapsulated Red <NUM> Lake (Formulation <NUM>) were prepared with the compositions of Table <NUM>.

Claim 1:
A pigment capsule comprising a pigment and consisting of an interior and a barrier membrane,
wherein silica, a titanium dioxide pigment and another pigment are dispersed in the interior, and the barrier membrane is formed by a polymer binder having a glass transition temperature of <NUM> or higher which is an acrylate copolymer,
wherein a C<NUM>-C<NUM> trivalent carboxylic acid is contained in the interior of the capsule,
wherein the other pigment is an oil-soluble dye,
wherein the content of the other pigment is <NUM> to <NUM>% by weight based on the total weight of the capsule,
wherein the content of the polymer binder is <NUM> to <NUM>% by weight based on the total weight of the capsule,
wherein the C<NUM>-C<NUM> trivalent carboxylic acid is selected from the group consisting of citric acid, iso-citric acid, aconitic acid, tricarballylic acid, and trimesic acid, and
wherein the content of the C<NUM>-C<NUM> trivalent carboxylic acid is <NUM> to <NUM>% by weight based on the total weight of the capsule.