Patent Description:
Film-forming agents which are water resistant and oil resistant so as to impart good properties to cosmetic films and which prevent makeup from coming off have been developed in the field of makeup cosmetics, including lipstick, eye makeup such as mascara, and skin care products. Silicone oils and silicone resins having water repellency are commonly used as such film-forming agents, the important qualities of which are to keep makeup from wearing off and give it excellent longevity. Examples of water-repelling silicone oils and silicone resins used in cosmetic preparations include crosslinked silicones obtained by the addition polymerization of a silicone resin or an organohydrogenpolysiloxane with a vinyl group-containing organopolysiloxane, and acrylic-silicone graft copolymers. Of these, acrylic-silicone graft copolymers are widely used because they are soft films and have excellent water repellency (Patent Document <NUM>: <CIT>).

In recent years, owing to concerns over environmental impact and irritation of the skin, not only acrylic-silicone graft copolymer-containing water-in-oil cosmetic preparations, but also acrylic-silicone graft copolymer-containing oil-in-water emulsion cosmetic preparations, are commonly used in makeup cosmetics (Patent Document <NUM>: <CIT>; Patent Document <NUM>: <CIT>; Patent Document <NUM>: <CIT>). In order to include an acrylic-silicone graft copolymer in an oil-in-water cosmetic, it is necessary to emulsify the acrylic-silicone graft copolymer in the oil-in-water system. However, oil-in-water emulsion compositions of acrylic-silicone graft copolymers have a poor shelf stability and may give rise to concentration separation over time. Also, due to the influence of surfactants, there is a possibility of a decrease in water resistance, a decrease in film formability, and of irritation of the skin and bitterness.

Although investigations of oil-in-water emulsion compositions of acrylic-silicone graft copolymers have hitherto been carried out, in most oil-in-water emulsion compositions of acrylic-silicone graft copolymers that form a film having water resistance, acrylic polymerization is carried out in water. In such a production method, acrylic monomer remains within the composition, making it unsuitable for cosmetic preparations (Patent Document <NUM>: <CIT>).

Patent Document <NUM> discloses a method for producing a cosmetic composition of oil-in-water emulsion comprising an acrylic-silicone graft copolymer and a volatile oil, but it is silent about its particle size and a high shear pressure treatment step.

Hence, although there exists a desire for oil-in-water emulsion compositions of acrylic-silicone graft copolymers which can be used in cosmetic preparations, form a soft, water-resistant film, are mild to the skin, and have minimal bitterness and a good shelf stability, there have hitherto been no reports on methods for producing such oil-in-water emulsion compositions.

In the light of the above circumstances, the object of this invention is to provide an acrylic-silicone graft copolymer-containing oil-in-water emulsion composition which can be used in cosmetic preparations, has good coating properties and film formability, forms a film having water resistance and the softness characteristic of acrylic-silicone graft copolymers, is mild to the skin, and has minimal bitterness and a good shelf stability.

The inventor has conducted extensive investigations in order to achieve this object and discovered as a result that the above problems can be resolved by agitating and thereby emulsifying a composition containing specific amounts of (A) an acrylic-silicone graft copolymer, (B) a volatile oil, (C) a polyoxyethylene sorbitan fatty acid ester having an average number of added moles of ethylene oxide (EO) of at least <NUM> and a hydrophilic-lipophilic balance (HLB) of at least <NUM> and (D) water, and subsequently treating the emulsified composition under a high shear pressure of from <NUM> to <NUM> MPa. This discovery ultimately led to the present invention. Treatment under a high shear pressure results in an even better shelf stability and good coating properties. When an acrylic-silicone graft copolymer-containing oil-in-water emulsion composition obtained by the production method of the invention is used in a cosmetic preparation, a film forms that has water resistance and the softness characteristic of acrylic-silicone graft copolymers. Also, because the bitterness is minimal, the oil-in-water emulsion composition obtained by the inventive production method is gentle on the body and suitable for skin care applications, especially lipstick applications.

Accordingly, the invention provides a method for producing oil-in-water emulsion compositions and a cosmetic preparation as defined in the claims.

The production method of the invention makes it possible to provide acrylic-silicone graft copolymer-containing oil-in-water emulsion compositions which can be used in cosmetic preparations, have good coating properties and film formability, form a film having water-resistance and the softness characteristic of acrylic-silicone graft copolymers, is mild to the skin, and has minimal bitterness and a good shelf stability.

The invention is described in detail below.

Component (A) is an acrylic-silicone graft copolymer which contains constituent units (<NUM>) and (<NUM>) of the general formulae shown below and has a molecular weight of from <NUM>,<NUM> to <NUM>,<NUM>. More specifically, it is a copolymer obtained by grafting polysiloxane chains to an acrylic polymer chain. Component (A) may be of one type used alone or of two or more types used in suitable combination. <CHM>
In these formulae, each R<NUM> is a group independently selected from monovalent hydrocarbon groups, R<NUM> is an alkyleneoxycarbonyl group of <NUM> to <NUM> carbon atoms with the alkenylene group being limited to a structure that bonds with a silicon atom, R<NUM> and R<NUM> are each independently a hydrogen atom or a methyl group, R<NUM> is an alkyl group of <NUM> to <NUM> carbon atoms or a hydrogen atom, and m is an integer from <NUM> to <NUM>. The molar ratio of the constituent units having general formulae (<NUM>) and (<NUM>), expressed as (<NUM>)/(<NUM>), is from <NUM> to <NUM>.

In the above formulae, each R<NUM> is a group independently selected from monovalent hydrocarbon groups. These are exemplified by linear or branched, substituted or unsubstituted alkyl groups of <NUM> to <NUM> carbon atoms, aryl groups of <NUM> to <NUM> carbon atoms and aralkyl groups of <NUM> to <NUM> carbon atoms. Specific examples of linear or branched, substituted or unsubstituted alkyl groups of <NUM> to <NUM> carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, octyl, nonyl, decyl, undecyl, dodecyl and tridecyl groups; and halogen-substituted alkyl groups or fluorine-substituted alkyl groups such as chloromethyl, chloropropyl, bromoethyl and trifluoropropyl groups.

Examples of aryl groups of <NUM> to <NUM> carbon atoms include phenyl, tolyl, xylyl and naphthyl groups. Examples of aralkyl groups of <NUM> to <NUM> carbon atoms include benzyl, phenylethyl and phenylpropyl groups. These may be substituted. Of the above, alkyl groups of <NUM> to <NUM> carbon atoms and aryl groups are preferred. From the standpoint of versatility, methyl groups are more preferred.

R<NUM> is an alkyleneoxycarbonyl group of <NUM> to <NUM> carbon atoms (the alkylene group being limited to a structure that bonds with a silicon atom). An alkyleneoxycarbonyl group of <NUM> or <NUM> carbon atoms is preferred.

R<NUM> and R<NUM> are each independently a hydrogen atom or a methyl group. R<NUM> is an alkyl group of <NUM> to <NUM> carbon atoms or a hydrogen atom, and is exemplified by linear or branched, substituted or unsubstituted alkyl groups. Specific examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, octyl, nonyl, decyl, undecyl and dodecyl groups; and halogen-substituted alkyl groups such as chloromethyl, chloropropyl, bromoethyl and trifluoropropyl groups. Of these, an alkyl group of <NUM> to <NUM> carbon atoms or a hydrogen atom is preferred. An alkyl group of <NUM> to <NUM> carbon atoms or a hydrogen atom is more preferred.

The subscript "m" is an integer from <NUM> to <NUM>, and preferably from <NUM> to <NUM>. When m is less than <NUM>, the water resistance of the formed film is inadequate; when it exceeds <NUM>, the glass transition point of the resulting acrylic-silicone graft copolymer is too low, as a result of which a film of a sufficient strength cannot be formed.

The molar ratio of the constituent units of general formulae (<NUM>) and (<NUM>), expressed as (<NUM>)/(<NUM>), is from <NUM> to <NUM>, preferably from <NUM> to <NUM>, and more preferably from <NUM> to <NUM>. When this molar ratio (<NUM>)/(<NUM>) is less than <NUM>, the water resistance of the film may decrease; on the other hand, when it is larger than <NUM>, the film becomes viscous and a film of sufficient strength cannot be formed.

The sum of constituent units (<NUM>) and (<NUM>) may be <NUM> mol%, although optional constituent units may be included within a range that does not detract from the advantageous effects of the invention. For example, radical polymerizable silane compound of general formula (<NUM>) may be included as such constituent units. When such constituent units are included, the amount thereof may be set to from <NUM> to <NUM> mol% of all the constituent units. <CHM>
In the formula, R<NUM> is a hydrogen atom or a methyl group, each R<NUM> is independently an alkyleneoxycarbonyl group of <NUM> to <NUM> carbon atoms, and X is a hydrolyzable silyl group of general formula (<NUM>) below. <CHM>
wherein R<NUM> is a monovalent hydrocarbon group and n is an integer from <NUM> to <NUM>, with the proviso that when n is <NUM> or <NUM>, the R<NUM> groups may mutually differ.

R<NUM> is exemplified in the same way as R<NUM> above, with an alkyl group of <NUM> to <NUM> carbon atoms being preferred.

Component (A) has a weight-average molecular weight of from <NUM>,<NUM> to <NUM>,<NUM>, preferably from <NUM>,<NUM> to <NUM>,<NUM>, and more preferably from <NUM>,<NUM> to <NUM>,<NUM>. The glass transition point is preferably from -<NUM> to +<NUM>. At a molecular weight below <NUM>,<NUM>, the film durability decreases; on the other hand, at a molecular weight above <NUM>,<NUM>, the feel upon use when the composition is included in a cosmetic preparation worsens. The weight-average molecular weight, which is determined by gel permeation chromatography (GPC), is obtained by dissolving component (A) in toluene and calculation as a polystyrene-equivalent value.

Examples of component (A) include, but are not limited to, those shown below. Copolymerization of constituent units (<NUM>) and (<NUM>) may be random, block or graft polymerization. <CHM>
<CHM>
<CHM>
wherein p1, p2 and p3 are integers from <NUM> to <NUM>, with the sum p1+p2+p3 being from <NUM> to <NUM>; and m is an integer from <NUM> to <NUM>. <CHM>
<CHM>
<CHM>
<CHM>
wherein, p1, p2 and p3 are integers from <NUM> to <NUM>, with the sum p1+p2+p3 being from <NUM> to <NUM>.

The acrylic-silicone graft copolymer of component (A) can be obtained by, for example, reacting a radical polymerizable group-containing organopolysiloxane compound with an acrylic monomer. From the standpoint of the ease of production and molecular design, it is preferable to use the so-called macromonomer method which copolymerizes a radical polymerizable group-containing organopolysiloxane compound of general formula (<NUM>) and an acrylic monomer of general formula (<NUM>) in the presence of a radical polymerization initiator. <CHM>
wherein R<NUM> and m are the same as above, and A is a radical-polymerizable group of general formula (<NUM>) below. <CHM>
wherein R<NUM> and R<NUM> are the same as above. <CHM>
wherein R<NUM> and R<NUM> are the same as above.

As for the method of preparing the compound of general formula (<NUM>), this compound can be obtained by, for example, carrying out a dehydrochlorination or dechlorination reaction in accordance with the customary method on an acryloxy or methacryloxy group-substituted chlorosilane compound of general formula (<NUM>) below and a mono-terminally reactive diorganopolysiloxane of general formula (<NUM>) below. <CHM>
wherein R<NUM> is the same as above and R<NUM>, which is the alkylene residue of R<NUM>, is a saturated divalent hydrocarbon group of <NUM> to <NUM> carbon atoms that has a linear or branched carbon chain. <CHM>
wherein R<NUM> and m are the same as above.

The acrylic monomer of general formula (<NUM>) which is composed primarily of acrylate and/or methacrylate is a compound having one radical polymerizable unsaturated bond on the molecule. Illustrative examples include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, cyclohexyl (meth)acrylate, <NUM>-ethylhexyl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate and behenyl (meth)acrylate. These may be used singly or two or more may be suitably combined and used. The use in combination of methyl (meth)acrylate and, of the above monomers, a monomer that gives a homopolymer having a high glass transition temperature (Tg) and a monomer that gives a homopolymer having a low Tg is preferred.

Next, a method for preparing the acrylic-silicone graft copolymer of general formula (<NUM>) is described. An exemplary method is that of copolymerizing a radical polymerizable group-containing organopolysiloxane compound of general formula (<NUM>) with an acrylic monomer of general formula (<NUM>) in the presence of a radical polymerization initiator. This is carried out in the presence of, as the radical polymerization initiator, an ordinary radical polymerization initiator such as a peroxide (e.g. benzoyl peroxide, dicumyl peroxide, t-butylperoxy-<NUM>-ethylhexyl hexanoate) or an azo compound (e.g. azobisisobutyronitrile). The amount of radical polymerization initiator used may be an ordinary amount and is preferably from <NUM> to <NUM> wt% of the total amount of monomer that takes part in copolymerization. This amount is suitably selected according to the specified reaction rate, the degree of polymerization of the target copolymer and the type of radical polymerization initiator. Use may be made of solution polymerization, emulsion polymerization, suspension polymerization or bulk polymerization as the method of copolymerization in this invention. Of these, solution polymerization is especially preferred because it is easy to adjust the molecular weight of the resulting copolymer within an optimal range.

Solvents that may be used in this copolymerization reaction include alcohols such as isopropyl alcohol and butanol; aromatic hydrocarbons such as benzene, toluene and xylene; ketones such as methyl ethyl ketone and methyl isobutyl ketone; and esters such as ethyl acetate and isobutyl acetate. These may be used singly or two or more may be suitably combined and used together. The reaction is preferably carried out at a temperature of between <NUM> and <NUM>, and especially between <NUM> and <NUM>. Under these temperature conditions, the reaction can be brought to substantial completion in from about <NUM> to about <NUM> hours. Because acrylic monomer is present in the copolymer solution following the reaction, this may be driven off by heating under reduced pressure. In cases where the acrylic monomer cannot be completely driven off in this way, distillation and removal is possible by adding a solvent and again heating under reduced pressure.

The volatile oil is one that can be used in cosmetic products. Use can be made of a volatile oil that is suitably selected from among those having a boiling point at normal pressure/<NUM> of <NUM> or less. Exemplary volatile oils include silicone oils, hydrocarbon oils and ester oils. These may be used singly or two or more may be suitably combined and used together. Of these, from the standpoint of versatility, silicone oils and hydrocarbon oils are preferred.

The silicone oil used is one having a viscosity at <NUM> of <NUM><NUM>/s or less. This viscosity, which is the kinematic viscosity, is a value measured at <NUM> with an Ostwald viscometer (the same applies below). At a viscosity greater than <NUM><NUM>/s, silicone oil does not readily volatize at <NUM> and remains in the film, giving rise to a sticky sensation when included in cosmetic preparations. Examples of silicone oils include those of the following general formulae. <CHM>
<CHM>
<CHM>
wherein the subscript "a" is an integer from <NUM> to <NUM>, and each R<NUM> is independently selected from among monovalent hydrocarbon groups and exemplified in the same way as R<NUM> above.

Hydrocarbon oils are exemplified by volatile hydrocarbon oils that are linear or branched. Specific examples include isododecane, α-olefin oligomers, light isoparaffin, light liquid isoparaffin, liquid paraffin and liquid isoparaffin. These should be suitably selected according to, for example, the required feeling upon use. However, from the standpoint of versatility, isododecane and isoparaffin are preferred.

Examples of ester oils include ethyl acetate, butyl acetate and isopropyl acetate.

The polyoxyethylene sorbitan fatty acid ester having an average number of moles of added ethylene oxide (EO) of at least <NUM> and a hydrophilic-lipophilic balance (HLB) of at least <NUM> may be used singly, or two or more may be suitably combined and used together. By using such sorbitan fatty acid ester, an oil-in-water emulsion composition that has little bitterness, is mild, and has good coating properties, film formability and shelf stability can be achieved.

Illustrative examples of the polyoxyethylene sorbitan fatty acid ester include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan isostearate, polyoxyethylene sorbitan triooleate and polyoxyethylene sorbitan tristearate. Of these, from the standpoint of emulsifiability, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate and polyoxyethylene sorbitan monopalmitate are preferred. From the standpoint of bitterness and the like, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate and polyoxyethylene sorbitan monopalmitate are more preferred. Polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate and polyoxyethylene sorbitan monooleate are recognized also as food additives.

The number of moles of ethylene oxide added is at least <NUM>, preferably from <NUM> to <NUM>, and more preferably from <NUM> to <NUM>. When the number of moles of ethylene oxide added is less than <NUM>, the polyoxyethylene fatty acid ester dissolves the acrylic-silicone copolymer and remains in the acrylic-silicone copolymer film; hence, there is a risk of decreased film formability and of stickiness. At more than <NUM>, it becomes solid at room temperature and is difficult to handle.

The HLB is at least <NUM>, preferably from <NUM> to <NUM>, and more preferably from <NUM> to <NUM>. The HLB is determined by Griffin's formula. When a liquid surfactant having an HLB of less than <NUM> is included, the surfactant dissolves the acrylic-silicone copolymer and remains in the acrylic-silicone copolymer film; hence, there is a risk of decreased film formability and of stickiness.

In general, surfactants which have a low molecular weight or which have functional groups such as amino groups or include much salt are known to give rise to irritation of the skin and bitterness. Therefore, to further reduce the bitterness of an oil-in-water emulsion composition obtained by the production method of the invention, it is desirable to select a polyoxyethylene sorbitan fatty acid ester for which the content of salt and low-molecular-weight compounds is even lower. For example, it is possible to reduce the bitterness of the emulsion composition by using Nonion ST-<NUM> or Nonion OT-<NUM> from NOF Corporation.

Purified water or the like may be suitably selected and used as the water.

It is preferable to include (E) a water-soluble polymer compound in the oil-in-water emulsion composition of the invention in order to keep down film stickiness, increase film strength and increase emulsifiability, or in order to thicken the oil-in-water emulsion composition and increase shelf stability. "Water-soluble polymeric compound" refers to a polymer compound which has polar groups on the molecule and is dispersible in water. The water-soluble polymer compound may be a natural polymer, a semi-synthetic product or a synthetic product. Specific examples include starch, mannan, galactan from seaweeds, alginates, gum arabic, dextran, gelatin, casein, collagen, polyvinyl alcohol, methylcellulose, carboxymethylcellulose hydroxymethylcellulose, polyvinyl pyrrolidone, xanthan gum and acrylic acid polymers.

The contents of the various ingredients in the oil-in-water emulsion composition are described below.

The component (A) content is from <NUM> to <NUM> wt%, preferably from <NUM> to <NUM> wt%, and more preferably from <NUM> to <NUM> wt%. At a content lower than <NUM> wt%, properties such as water repellency are difficult to obtain when component (A) is included in a cosmetic preparation. On the other hand, at a content greater than <NUM> wt%, it is difficult to achieve a small particle size and the stability of oil-in-water emulsion compositions produced according to this invention worsens, resulting in separation over time.

The component (B) content is from <NUM> to <NUM> wt%, and preferably from <NUM> to <NUM> wt%. Because component (A) is a solid and is difficult to emulsify, preliminary dissolution in component (B) followed by emulsification is preferred. At a content lower than <NUM> wt%, there is a risk that component (A) will not dissolve, making emulsification impossible. On the other hand, at a content greater than <NUM> wt%, the volatile oil used as component (B) remains present, and so film properties when the emulsion composition is included in a cosmetic preparation cannot be obtained.

The weight ratio in which components (A) and (B) are included, expressed as (A)/(B), is preferably from <NUM>/<NUM> to <NUM>/<NUM>, and more preferably from <NUM>/<NUM> to <NUM>/<NUM>. Setting (A)/(B) to <NUM>/<NUM> or more enables properties such as water repellency to be achieved when the emulsion composition is included in a cosmetic preparation; setting (A)/(B) to <NUM>/<NUM> or less enables the size of the emulsion particles to be made finer, further enhancing stability over time. In addition, the viscosity (at <NUM>) of the mixed solution of components (A) and (B) is preferably not more than <NUM><NUM>/s, more preferably not more than <NUM><NUM>/s, and even more preferably not more than <NUM><NUM>/s. The lower limit, although not particularly defined, may be set to <NUM><NUM>/s or more. By setting this viscosity to not more than <NUM><NUM>/s, the size of the emulsion particles can be made finer, further enhancing the stability over time.

The component (C) content is from <NUM> to <NUM> wt%, and preferably from <NUM> to <NUM> wt%. At a content below <NUM> wt%, the emulsifiability decreases and component (A) cannot be emulsified. On the other hand, at more than <NUM> wt%, the water repellency of the film decreases.

The component (D) content is from <NUM> to <NUM> wt%, preferably from <NUM> to <NUM> wt%, and more preferably from <NUM> to <NUM> wt%. At less than <NUM> wt%, the viscosity of the oil-in-water emulsion composition obtained by the production method of the invention rises, making the composition difficult to handle. On the other hand, at more than <NUM> wt%, the deionized water serving as component (D) tends to remain, making the film properties difficult to achieve.

Component (E) is an optional ingredient. When included, the amount thereof is preferably from <NUM> to <NUM> wt%, and more preferably from <NUM> to <NUM> wt%, relative to the combined amount of components (A) and (B). By setting the content of component (E) relative to the combined amount of components (A) and (B) to at least <NUM> wt%, the advantageous effects of including component (E) can be obtained. When the amount is set to more than <NUM> wt%, the film may become too hard and a film having the softness characteristic of acrylic-silicone graft copolymers may not be attainable.

Antimicrobial agents and preservatives such as surfactants, oxazoline compounds and aromatic carboxylates, flavors, antioxidizing agents, rust inhibitors, dyes, fillers, curing catalysts, organic powders, inorganic powders and the like may be included in the oil-in-water emulsion compositions produced by the method of the invention. These may be used singly or two or more may be suitably combined and included in a suitable amount.

The production method of this invention includes agitating and thereby emulsifying a composition containing above components (A), (B), (C) and (D) (Step (I)), and subsequently treating the emulsified composition under a high shear pressure of from <NUM> to <NUM> MPa (Step (II)). More preferred examples are described in detail below.

Because component (A) is a solid and thus difficult to emulsify, it is preferable to first dissolve it in component (B) and then carry out emulsification. Some or all of component (C) and some or all of component (D) are added to the resulting mixed solution, and emulsification is carried out with an agitator such as a homogenizing mixer or a homogenizing disperser. Where necessary, the remaining amounts of components (C) and (D) are then added and diluted with an agitator such as a homogenizing mixer or a homogenizing disperser, thereby giving an emulsion composition (I).

The emulsification temperature is not particularly limited, although it is desirable to set it or below the flash point of the oil-in-water emulsion composition obtained by the production method of the invention. The emulsification temperature is preferably from <NUM> to <NUM>, and more preferably from <NUM> to <NUM>. By setting it to from <NUM> to <NUM>, emulsification is easy and the emulsion composition becomes more stable. The stirring speed is preferably from <NUM> to <NUM>,<NUM> rpm, and more preferably from <NUM> to <NUM>,<NUM> rpm. The emulsification time is not particularly limited, although it is preferably from <NUM> to <NUM> minutes when production is carried out with a batch-type emulsifier, and is preferably <NUM> minute or less when production is carried out with a continuous emulsifier. The pressure during emulsification is not limited to normal pressure; that is, emulsification may also be carried out under reduced pressure or applied pressure. In cases where agitation is carried out under reduced pressure or applied pressure, bubble incorporation is sometimes discouraged, enabling more effective emulsification. When the system is set to a reduced pressure, this pressure is made higher than the vapor pressure of the starting materials so as to prevent volatilization of the starting materials.

In cases where some or all of component (C) and some of component (D) are added and emulsification is carried out with an agitator such as a homogenizing mixer or a homogenizing disperser, following which the remainder of component (D) and, if necessary, the remainder of component (C) are added and dilution is carried out, the stirring speed during dilution is preferably from <NUM> to <NUM>,<NUM> rpm, and more preferably from <NUM> to <NUM>,<NUM> rpm. The dilution time is preferably from <NUM> to <NUM> minutes when using a batch-type apparatus and <NUM> minute or less when using a continuous apparatus.

At a content of initially added component (D) that is low relative to the mixed solution of components (A) and (B), the average particle size of the resulting emulsion composition (I) becomes finer and, even when the shear pressure in the subsequent high shear pressure treatment is low, an oil-in-water emulsion composition of the desired particle size can be obtained. However, when the content of initially added component (D) is too small, the mixed solution of components (A) and (B) cannot be emulsified into an oil-in-water system. In the light of these points, the content of initially added component (D) is preferably from <NUM> to <NUM> wt%, and more preferably from <NUM> to <NUM> wt%, of the mixed solution of components (A) and (B).

Emulsifiers that may be used include, for example, the Homogenizing Mixer (Primix Corporation), the Homogenizing Disper (Primix Corporation), the Agi Homo Mixer (Primix Corporation), the Combi Mix (Primix Corporation)--which is a three-shaft dispersion mixer that combines the Homogenizing Mixer, the Homogenizing Disper and the Anchor Mixer, a colloid mill having an agitating mechanism consisting of a rotor and a stator (such as those available from IKA, PUC, Nissei Corporation and Iwaki Co. ), high-shear mixers (such as those available from Silverson and Primix Corporation) and the Hivis Disper Mix model 3D-<NUM> (Primix Corporation), which is an agitator based on the orbital revolution and own-axis rotation of two blades and the high-speed rotation of a toothed blade.

Emulsion particles in the emulsion composition (I) following completion of the emulsification step (I) have an average particle size that is preferably in the range of <NUM> to <NUM>,<NUM>.

The resulting emulsion composition (I) is then treated at a high shear pressure of from <NUM> to <NUM> MPa in a high-pressure homogenizing disperser, thereby giving oil-in-water emulsion composition (II). The shear pressure is from <NUM> to <NUM> MPa, and preferably from <NUM> to <NUM> MPa. At a shear pressure below <NUM> MPa, it is difficult to achieve an average particle size for the resulting oil-in-water emulsion composition of <NUM> or less. On the other hand, setting the shear pressure to more than <NUM> MPa is unlikely to have the effect of making the average particle size even smaller and moreover places a large strain on the equipment. When high shear pressure treatment does not achieve the target average particle size in a single pass, treatment may be carried out two or more times.

The high-pressure homogenizer may be a slit passage-type apparatus which emulsifies a sample by utilizing the energy of, for example, collisions between particles that form by pressurizing a mixture and ejecting it from a slit, shear forces due to pressure differences, and collisions with an impact ring; or a frontal collision-type apparatus which causes a sample to collide and emulsify by utilizing the fact that applying pressure increases acceleration. Exemplary high-pressure homogenizers include the Starburst and SUGINO HJP-<NUM> from Sugino Machine Ltd. , the LAB <NUM> from SMT Co. , the HPH from IKA and the Econizer Labo-<NUM> from Sanmaru Machinery Co.

Component (E), in cases where other optional ingredients are included, is not particularly limited. When component (E) is included, it may be added in step (I) or may be added after high shear pressure treatment has been carried out in step (II). In cases where component (E) is added following high shear pressure treatment in step (II), mixture is carried out using an agitator such as a homogenizing mixer or a homogenizing disperser.

The properties of oil-in-water emulsion compositions obtained by the production method of the invention are described. The emulsion particles are rendered to a small size by the production method of the invention. Oil-in-water emulsion compositions obtained by the production method of the invention have a good shelf stability, excellent coating properties and also excellent film formability. The film has water resistance and also has the softness characteristic of acrylic-silicone graft copolymers. When an oil-in-water emulsion composition obtained by the production method of the invention is used in a cosmetic product, a film that is mild to the skin, has little bitterness and is soft can be obtained.

The viscosity of the oil-in-water emulsion composition, although not particularly specified, is preferably from <NUM> to <NUM>,<NUM> mPa·s, more preferably from <NUM> to <NUM>,<NUM> mPa·s, and even more preferably from <NUM> to <NUM>,<NUM> mPa·s. At a viscosity of <NUM> mPa·s or more, the coating properties improve further; at a viscosity of <NUM>,<NUM> mPa·s or less, the handleability is better and the particle size becomes finer with high shear pressure treatment. The viscosity is a value measured at <NUM> with a BM-type rotational viscometer.

The emulsion particles in the oil-in-water emulsion composition have an average size of <NUM> or less, and preferably <NUM> or less. When the average particle size is larger than <NUM>, separation may soon arise. Although the average particle size has no particular lower limit, it is generally at least <NUM>, and especially at least <NUM>. The average particle size is measured by a dynamic light scattering method. The instrument used for the dynamic light scattering method is exemplified by the N4 PLUS (BECKMAN COULTER), the DelsaMax CORE (BECKMAN COULTER) and the DelsaMax Pro (BECKMAN COULTER). Measurement is carried out after diluting the oil-in-water emulsion composition with water to the optimal concentration for the particular instrument used. The method of calculating the particle size is based on the scattering intensity.

The oil-in-water emulsion composition obtained by the production method can be included in a cosmetic preparation. The cosmetic preparation is not particularly limited and can be used in, for example, skin care cosmetics and hair care cosmetics. Based on the properties of the invention, inclusion in makeup cosmetics and skin care cosmetics is especially preferred. Examples of makeup cosmetics include foundation (including all solid and liquid foundations), cream, makeup base, skin milk, eyeshadow, lipstick, lip cream, rouge, eyebrow, mascara, eyeliner, cleansing preparations and packs. Of these, lipsticks are preferred. The form of the cosmetic preparation is not particularly limited. For example, various forms such as liquids, emulsions, creams, solids, pastes, gels, multilayer preparations, mousses, sprays, sticks and pencils may be selected. The content of the oil-in-water emulsion composition therein is preferably from <NUM> to <NUM> wt%, and more preferably from <NUM> to <NUM> wt%. The advantageous effects of the invention are readily obtained particularly within this range. When the content is too high, a heavy texture may result.

Various ingredients used in conventional cosmetic preparations may be included in cosmetic preparations containing the oil-in-water emulsion composition of the invention, within ranges that do not detract from the advantageous effects of the invention. For example, the following may be included as ingredients: oils, alcoholic hydroxyl group-containing compounds, surfactants, powders, compositions of a crosslinked organopolysiloxane and an oil that is liquid at room temperature, silicone wax, film-forming agents, antiperspirants, antimicrobial agents and other additives. These may be used singly, or two or more may be suitably combined and used together.

The invention is illustrated more fully below by way of Examples and Comparative Examples. In the following Examples, unless noted otherwise, references to "%" in the composition signify percent by weight, and references to "ratios" signify weight ratios. The dynamic viscosity is a measured value obtained at <NUM> with an Ostwald viscometer.

A toluene solution of component (A-<NUM>) an acrylic-silicone copolymer of structural formula (<NUM>) below was obtained by mixing together <NUM> of a monomethacrylate-terminated dimethylpolysiloxane of formula (<NUM>) below, <NUM> of methyl methacrylate, <NUM> of <NUM>-ethylhexyl acrylate and <NUM> of toluene, subsequently adding and dissolving <NUM> of t-butylperoxy-<NUM>-ethylhexyl hexanoate (NOF Corporation, Perbutyl O), and then reacting for <NUM> hours under a nitrogen atmosphere and in a temperature range of between <NUM> and <NUM>. The polystyrene-equivalent weight-average molecular weight determined by GPC (toluene) was about <NUM>,<NUM>. <CHM>
<CHM>
<MAT>.

Four hundred grams of the toluene solution of the copolymer of formula (<NUM>) was heated under reduced pressure at <NUM> and <NUM> mmHg, driving off the toluene and acrylic monomer, following which <NUM> of isododecane was added and heating was carried out under reduced pressure at <NUM> and <NUM> mmHg, driving off the isododecane and the acrylic monomer. Next, <NUM> of (B-<NUM>) isododecane was added and the acrylic-silicone copolymer (A-<NUM>) was dissolved, giving Mixed Solution (i). The ratio expressed as (A-<NUM>)/(B-<NUM>) was about <NUM>/<NUM>, and the viscosity (<NUM>) of Mixed Solution (i) was <NUM><NUM>/s. The methyl methacrylate and <NUM>-ethylhexyl acrylate contents were each less than <NUM> ppm.

Four hundred grams of the toluene solution of acrylic-silicone copolymer (A) obtained in Synthesis Example <NUM> was heated under reduced pressure at <NUM> and <NUM> mmHg, driving off the toluene and the acrylic monomer, following which <NUM> of isododecane was added and heating under reduced pressure was carried out at <NUM> and <NUM> mmHg, driving off the isododecane and the acrylic monomer. Next, <NUM> of (B-<NUM>) isododecane was added and the (A) acrylic-silicone copolymer was dissolved, giving Mixed Solution (ii). The ratio expressed as (A-<NUM>)/(B-<NUM>) was about <NUM>/<NUM>, and the viscosity (<NUM>) of Mixed Solution (ii) was <NUM><NUM>/s. The methyl methacrylate and <NUM>-ethylhexyl acrylate were each less than <NUM> ppm.

Four hundred grams of the toluene solution of acrylic-silicone copolymer (A) obtained in Synthesis Example <NUM> was heated under reduced pressure at <NUM> and <NUM> mmHg, driving off the toluene and the acrylic monomer, following which <NUM> of isododecane was added and heating under reduced pressure was carried out at <NUM> and <NUM> mmHg, driving off the isododecane and the acrylic monomer. Next, <NUM> of the silicone compound of formula (<NUM>) below as component (B-<NUM>) was added and the (A) acrylic-silicone copolymer was dissolved, giving Mixed Solution (iii). The ratio expressed as (A-<NUM>)/(B-<NUM>) was about <NUM>/<NUM>, and the viscosity (<NUM>) of Mixed Solution (iii) was <NUM><NUM>/s. The methyl methacrylate and <NUM>-ethylhexyl acrylate contents were each less than <NUM> ppm.

Fifty grams of (C-<NUM>) Nonion OT-<NUM> (polyoxyethylene (<NUM> EO) sorbitan monooleate; HLB, <NUM>; from NOF Corporation) and <NUM> of (D) deionized water were added to <NUM> of Mixed Solution (i) and emulsification was carried out by stirring for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), following which <NUM> of (D) deionized water was added and stirring was carried out for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), thereby giving Emulsion Composition (I-<NUM>). Emulsion Composition (I-<NUM>) had an average particle size, as measured with the N4 PLUS (BECKMAN COULTER), of <NUM>,<NUM>. Emulsion Composition (I-<NUM>) was then treated twice at <NUM> MPa with the SUGINO HJP-<NUM> (Sugino Machine Ltd. ), giving Oil-in-Water Emulsion Composition (II-<NUM>). Oil-in-Water Emulsion Composition (II-<NUM>) had a viscosity of <NUM> mPa·s and an average particle size, as determined with the N4 PLUS (BECKMAN COULTER), of <NUM>.

Fifty grams of (C-<NUM>) Nonion OT-<NUM> (polyoxyethylene (<NUM> EO) sorbitan monooleate; HLB, <NUM>; from NOF Corporation) and <NUM> of (D) deionized water were added to <NUM> of Mixed Solution (ii) and emulsification was carried out by stirring for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), following which <NUM> of (D) deionized water was added and stirring was carried out for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), thereby giving Emulsion Composition (I-<NUM>). Emulsion Composition (I-<NUM>) had an average particle size, as measured with the N4 PLUS (BECKMAN COULTER), of <NUM>,<NUM>. Emulsion Composition (I-<NUM>) was then treated twice at <NUM> MPa with the SUGINO HJP-<NUM> (Sugino Machine Ltd. ), giving Oil-in-Water Emulsion Composition (II-<NUM>). Oil-in-Water Emulsion Composition (II-<NUM>) had a viscosity of <NUM> mPa·s and an average particle size, as determined with the N4 PLUS (BECKMAN COULTER), of <NUM>.

Fifty grams of (C-<NUM>) Nonion ST-<NUM> (polyoxyethylene (<NUM> EO) sorbitan monostearate; HLB, <NUM>; from NOF Corporation) and <NUM> of (D) deionized water were added to <NUM> of Mixed Solution (i) and emulsification was carried out by stirring for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), following which <NUM> of (D) deionized water was added and stirring was carried out for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), thereby giving Emulsion Composition (I-<NUM>). Emulsion Composition (I-<NUM>) had an average particle size, as measured with the N4 PLUS (BECKMAN COULTER), of <NUM>,<NUM>. Emulsion Composition (I-<NUM>) was then treated twice at <NUM> MPa with the SUGINO HJP-<NUM> (Sugino Machine Ltd. ), giving Oil-in-Water Emulsion Composition (II-<NUM>). Oil-in-Water Emulsion Composition (II-<NUM>) had a viscosity of <NUM> mPa·s and an average particle size, as determined with the N4 PLUS (BECKMAN COULTER), of <NUM>.

Fifty grams of (C-<NUM>) Nonion OT-<NUM> (polyoxyethylene (<NUM> EO) sorbitan monooleate; HLB, <NUM>; from NOF Corporation) and <NUM> of (D) deionized water were added to <NUM> of Mixed Solution (iii) and emulsification was carried out by stirring for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), following which <NUM> of (D) deionized water was added and stirring was carried out for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), thereby giving Emulsion Composition (I-<NUM>). Emulsion Composition (I-<NUM>) had an average particle size, as measured with the N4 PLUS (BECKMAN COULTER), of <NUM>,<NUM>. Emulsion Composition (I-<NUM>) was then treated twice at <NUM> MPa with the SUGINO HJP-<NUM> (Sugino Machine Ltd. ), giving Oil-in-Water Emulsion Composition (II-<NUM>). Oil-in-Water Emulsion Composition (II-<NUM>) had a viscosity of <NUM>,<NUM> mPa·s and an average particle size, as determined with the N4 PLUS (BECKMAN COULTER), of <NUM>.

Fifty grams of (C-<NUM>) Nonion OT-<NUM> (polyoxyethylene (<NUM> EO) sorbitan monooleate; HLB, <NUM>; from NOF Corporation), <NUM> of (E) a <NUM>% aqueous solution (Poval, from Japan Vam & Poval Co. ) of Gohsenol EG-40C (polyvinyl alcohol) and <NUM> of (D) deionized water were added to <NUM> of Mixed Solution (i) and emulsification was carried out by stirring for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), following which <NUM> of (D) deionized water was added and stirring was carried out for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), thereby giving Emulsion Composition (I-<NUM>). Emulsion Composition (I-<NUM>) had an average particle size, as measured with the N4 PLUS (BECKMAN COULTER), of <NUM>,<NUM>. Emulsion Composition (I-<NUM>) was then treated twice at <NUM> MPa with the SUGINO HJP-<NUM> (Sugino Machine Ltd. ), giving Oil-in-Water Emulsion Composition (II-<NUM>). Oil-in-Water Emulsion Composition (II-<NUM>) had a viscosity of <NUM>,<NUM> mPa·s and an average particle size, as determined with the N4 PLUS (BECKMAN COULTER), of <NUM>.

Fifty grams of (C-<NUM>) Nonion ST-<NUM> (polyoxyethylene (<NUM> EO) sorbitan monostearate; HLB, <NUM>; from NOF Corporation) and <NUM> of (D) deionized water were added to <NUM> of Mixed Solution (i) and emulsification was carried out by stirring for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), following which <NUM> of (D) deionized water was added and stirring was carried out for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), thereby giving Emulsion Composition (I-<NUM>). Emulsion Composition (I-<NUM>) had an average particle size, as measured with the N4 PLUS (BECKMAN COULTER), of <NUM>,<NUM>. Emulsion Composition (I-<NUM>) was then treated once at <NUM> MPa with the SUGINO HJP-<NUM> (Sugino Machine Ltd. ), giving Oil-in-Water Emulsion Composition (II-<NUM>). Oil-in-Water Emulsion Composition (II-<NUM>) had a viscosity of <NUM> mPa·s and an average particle size, as determined with the N4 PLUS (BECKMAN COULTER), of <NUM>.

Fifty grams of (C-<NUM>) Nonion OT-<NUM> (polyoxyethylene (<NUM> EO) sorbitan monooleate; HLB, <NUM>; from NOF Corporation) and <NUM> of (D) deionized water were added to <NUM> of Mixed Solution (i) and emulsification was carried out by stirring for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), following which <NUM> of (D) deionized water was added and stirring was carried out for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), thereby giving Emulsion Composition (I-<NUM>). Emulsion Composition (I-<NUM>) had a viscosity of <NUM> mPa·s and an average particle size, as measured with the N4 PLUS (BECKMAN COULTER), of <NUM>,<NUM>.

Fifty grams of (C-<NUM>) Nonion OT-<NUM> (polyoxyethylene (<NUM> EO) sorbitan monooleate; HLB, <NUM>; from NOF Corporation) and <NUM> of (D) deionized water were added to <NUM> of Mixed Solution (i) and emulsification was carried out by stirring for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), following which <NUM> of (D) deionized water was added and stirring was carried out for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), thereby giving Emulsion Composition (I-<NUM>). Emulsion Composition (I-<NUM>) had a viscosity of <NUM> mPa·s and an average particle size, as measured with the N4 PLUS (BECKMAN COULTER), of <NUM>.

Thirty grams of (C-<NUM>) Emulgen 104P (polyoxyethylene (<NUM>) lauryl ether; from Kao Corporation), <NUM> of (C-<NUM>) Emulgen 123P (polyoxyethylene (<NUM>) lauryl ether; Kao Corporation) and <NUM> of (D) deionized water were added to <NUM> of Mixed Solution (i) and emulsification was carried out by stirring for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), following which <NUM> of (D) deionized water was added and stirring was carried out for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), thereby giving Emulsion Composition (I-<NUM>). Emulsion Composition (I-<NUM>) had an average particle size, as measured with the N4 PLUS (BECKMAN COULTER), of <NUM>. Emulsion Composition (I-<NUM>) was then treated twice at <NUM> MPa with the SUGINO HJP-<NUM> (Sugino Machine Ltd. ), giving Oil-in-Water Emulsion Composition (II-<NUM>). Oil-in-Water Emulsion Composition (II-<NUM>) had a viscosity of <NUM> mPa s and an average particle size, as determined with the N4 PLUS (BECKMAN COULTER), of <NUM>.

Twenty-eight grams of (C-<NUM>) NIKKOL Decaglyn <NUM>-LV (polyglyceryl monolaurate; from Nikko Chemical Co. ), <NUM> of (C-<NUM>) NIKKOL Decaglyn <NUM>-ISV EX (polyglyceryl monoisostearate; Nikko Chemical Co. ) and <NUM> of (D) deionized water were added to <NUM> of Mixed Solution (i) and stirring was carried out for <NUM> minutes at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), following which <NUM> of (D) deionized water was added and emulsification was carried out by stirring for <NUM> minute at <NUM>,<NUM> rpm with the T. Homogenizing Mixer (Primix Corporation), thereby giving Emulsion Composition (I-<NUM>). Emulsion Composition (I-<NUM>) had an average particle size, as measured with the N4 PLUS (BECKMAN COULTER), of <NUM>,<NUM>. Emulsion Composition (I-<NUM>) was then treated twice at <NUM> MPa with the SUGINO HJP-<NUM> (Sugino Machine Ltd. ), giving Oil-in-Water Emulsion Composition (II-<NUM>). Oil-in-Water Emulsion Composition (II-<NUM>) had a viscosity of <NUM> mPa·s and an average particle size, as determined with the N4 PLUS (BECKMAN COULTER), of <NUM>.

The ingredient makeup, average particle size, viscosity and results of evaluations on shelf stability, presence/absence of bitterness, coatability (coating properties), and film formability of Oil-in-Water Emulsion Compositions II-<NUM> to II-<NUM> and Emulsion Compositions I-<NUM> and I-<NUM> obtained in the above Examples are shown in the tables below. The average particle sizes are measured values obtained with the N4 PLUS (BECKMAN COULTER), and the viscosities of the compositions are values measured at <NUM> with a BM-type rotational viscometer. The compositions in the Examples of the invention formed films having the softness characteristic of acrylic-silicone graft copolymers and were not irritating to the skin.

A <NUM> amount of the emulsion composition was placed in a glass bottle (volume, <NUM>) and left at rest for one month, following which the nonvolatile contents (<NUM>, <NUM> hours) of the top layer and the bottom layer were measured. The result is indicated as the value obtained by dividing the nonvolatile content of the top layer by the nonvolatile content of the bottom layer. The more this value diverges from unity, the greater the degree of separation.

The bitterness was evaluated by five subjects who spread <NUM> of the emulsion composition on the back of their hand, dried the composition at room temperature, and then licked this area and rated the bitterness according to the following criteria. The results, averaged for the five subjects, are indicated as "○" or "×".

The emulsion composition was applied to a weight of <NUM>/m<NUM> onto uncoated paperboard (<NUM> × <NUM>) using a <NUM> film thickness bar coater, and was evaluated for crawling.

Two grams of the emulsion composition was placed in a <NUM> diameter aluminum Petri dish, dried for <NUM> hours at room temperature, and the condition of the film was examined.

Two grams of the emulsion composition was placed in a <NUM> diameter aluminum Petri dish and dried for <NUM> hours at room temperature. A single drop of water was deposited with a pipette on the formed film and the water was lightly wiped off <NUM> seconds later, after which the condition of the film was examined.

A: Component (<NUM>) was mixed into part of component (<NUM>) and dispersed in a roll mill, following which the resulting dispersion was heated and mixed together with components (<NUM>) to (<NUM>). B: Components (<NUM>) to (<NUM>) were heated, added to the mixture obtained in A and emulsification was carried out, followed by cooling. C: Component (<NUM>) was added to the emulsion composition obtained in B, giving a cream lipstick.

Claim 1:
A method for producing an oil-in-water emulsion composition, comprising the steps of:
agitating and thereby emulsifying a composition containing:
(A) from <NUM> to <NUM> wt% of acrylic-silicone graft copolymer which has a weight-average molecular weight of <NUM>,<NUM> to <NUM>,<NUM> and contains constituent units (<NUM>) and (<NUM>) of the following general formulae
<CHM>
wherein each R<NUM> is a group independently selected from monovalent hydrocarbon groups, R<NUM> is an alkyleneoxycarbonyl group of <NUM> to <NUM> carbon atoms with the alkylene group being limited to a structure that bonds with a silicon atom, R<NUM> and R<NUM> are each independently a hydrogen atom or a methyl group, R<NUM> is an alkyl group of <NUM> to <NUM> carbon atoms or a hydrogen atom, m is an integer from <NUM> to <NUM>, and the molar ratio between the constituent units having general formulae (<NUM>) and (<NUM>), expressed as (<NUM>)/(<NUM>), is from <NUM> to <NUM>,
(B) from <NUM> to <NUM> wt% of volatile oil,
(C) from <NUM> to <NUM> wt% of polyoxyethylene sorbitan fatty acid ester having an average number of moles of added ethylene oxide (EO) of at least <NUM> and a hydrophilic-lipophilic balance (HLB) of at least <NUM>, and
(D) from <NUM> to <NUM> wt% of water; and
subsequently treating the emulsified composition under a high shear pressure of from <NUM> to <NUM> MPa, wherein emulsion particles in the oil-in-water emulsion composition have an average particle size of <NUM> or less.