JP2007161600A - Polymer emulsion for cosmetic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polymer emulsion for cosmetics capable of forming a film having excellent shrinkability, softness and water resistance, a method for producing the emulsion and an eyelash cosmetic. <P>SOLUTION: The polymer emulsion contains core-shell type polymer particles. The polymer of the shell part is an amphiphilic polymer containing a constitution unit derived from methacrylic acid and/or its salt and a constitution unit derived from a hydrophobic vinyl monomer and having a glass transition temperature of ≥100°C, and the polymer of the core part is a hydrophobic polymer containing a constitution unit derived from a hydrophobic vinyl monomer and having a glass transition temperature of ≤10°C. The invention further provides a method for producing the polymer emulsion and an eyelash cosmetic product compounded with the emulsion. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cosmetic polymer emulsion, and more particularly to a cosmetic polymer emulsion capable of forming a film excellent in shrinkage, flexibility and water resistance, a method for producing the same, and a cosmetic for eyelashes.

Cosmetics for eyelashes typified by mascara have a makeup effect that makes the eyelash shape and gives a sense of volume, making it appear darker and longer beautifully. The makeup effect of the eyelashes is improved by curling the tip of the upper eyelash upward. For this reason, it is often performed to apply a cosmetic for eyelashes after curling the tip of the upper eyelash upward using a buller (eyelash corrector). This is because the eyelashes appear dark and long when viewed from the front by curling the eyelashes upward.
A polymer emulsion having a film-forming property is used as one component of this eyelash cosmetic.

For example, Patent Document 1 discloses a cosmetic for eyelashes obtained by blending a polymer emulsion with water-dispersible or water-soluble sucrose fatty acid ester or fatty acid soap. However, this cosmetic for eyelashes has a problem that the curl-up effect is not sufficient.
Patent Document 2 discloses a mascara composition that gives a curl-up effect to eyelashes by a combination of a polymer that can adhere to a keratinous substance and other polymer particles, wax, or the like. Patent Document 3 discloses a mascara composition that provides a curl-up effect and an effect of thickening eyelashes by a combination of a polymer capable of forming a film causing shrinkage exceeding 1% of the stratum corneum and a high-hardness wax. ing.
However, the mascara compositions disclosed in Patent Documents 2 and 3 have a problem that curled eyelashes are easily washed away by tears or rain.
Therefore, there is a need for a polymer emulsion for cosmetics that can be incorporated into eyelash cosmetics and can provide a sufficient curl-up effect to the eyelash cosmetics without using a buller, and can also provide makeup persistence. It was.

JP 2000-119140 A JP 2003-55136 A JP-A-11-255619

  An object of the present invention is to provide a polymer emulsion for cosmetics capable of forming a film excellent in shrinkage, flexibility and water resistance, a method for producing the same, and a cosmetic for eyelashes.

The present inventors have found that a polymer emulsion containing core-shell type polymer particles composed of a specific amphiphilic polymer and a hydrophobic polymer can achieve the above-mentioned problem.
That is, the present invention
(1) A polymer emulsion containing core-shell type polymer particles, wherein the polymer of the shell part is a structural unit derived from methacrylic acid and / or a salt thereof (a-1) and a hydrophobic vinyl monomer (a-2) A structural unit derived from an amphiphilic polymer (A) having a glass transition temperature of 100 ° C. or higher, and a polymer in a core portion comprising a structural unit derived from a hydrophobic vinyl monomer (b), and having a glass transition temperature A polymer emulsion for cosmetics, which is a hydrophobic polymer (B) having a temperature of 10 ° C. or lower,
(2) The method for producing a polymer emulsion for cosmetics according to (1) above, wherein the hydrophobic vinyl monomer (b) and the polymerization initiator are dispersed in an aqueous phase and polymerized using the amphiphilic polymer (A) as a dispersant. And (3) a cosmetic for eyelashes comprising the cosmetic polymer emulsion of (1) above,
I will provide a.

  The polymer emulsion for cosmetics and the cosmetics for eyelashes of the present invention are excellent in the curl-up effect due to high shrinkage, and can form a cosmetic film maintaining flexibility and water resistance at a high level. Moreover, according to the manufacturing method of this invention, the polymer emulsion for cosmetics can be manufactured efficiently.

  The cosmetic polymer emulsion of the present invention is a polymer emulsion containing water as a continuous phase and containing core-shell type polymer particles, wherein the polymer in the shell part is derived from methacrylic acid and / or a salt thereof (a-1). And an amphiphilic polymer (A) having a glass transition temperature (hereinafter referred to as “Tg”) of 100 ° C. or higher, and a structural unit derived from the hydrophobic vinyl monomer (a-2). The polymer is a hydrophobic polymer (B) containing a structural unit derived from the hydrophobic vinyl monomer (b) and having a Tg of 10 ° C. or lower. Hereinafter, each component will be described.

[Amphiphilic polymer (A)]
The amphiphilic polymer (A) is a polymer that forms the shell part of the core-shell type polymer particle of the present invention, and a structural unit derived from methacrylic acid and / or a salt thereof (a-1) and a hydrophobic vinyl monomer ( The structural unit is derived from a-2), and Tg is 100 ° C. or higher.
This amphiphilic polymer (A) is a polymer having a firm film-forming property after drying, and also has a high shrinkage. Therefore, when the emulsion is dried, the curling property is reduced when the film is formed. It has the property to express. Here, “film forming property” means that when a polymer emulsion is spread on a Teflon petri dish and allowed to stand at 25 ° C. for one day to dry to produce a film having a thickness of 0.2 mm, a continuous film of 0.2 mm ² or more. The property of forming a transparent or semi-transparent solid film. However, cracks may occur with drying, and it is not necessary to obtain a single film.

One of the structural units of the amphiphilic polymer (A) is methacrylic acid and / or a salt thereof (a-1). Examples of the methacrylic acid salt include ammonium methacrylate.
Another structural unit of the amphiphilic polymer (A) is a hydrophobic vinyl monomer (a-2). The hydrophobic vinyl monomer means a vinyl monomer having a dissolution amount of 2 g or less, preferably 1.8 g or less when the vinyl monomer is dissolved in 100 g of water at 20 ° C. The lower the solubility of the hydrophobic vinyl monomer (a-2), the better when the amphiphilic polymer (A) is blended in the cosmetic because the moisture resistance of the cosmetic is improved.
In addition, the hydrophobic vinyl monomer (a-2) is preferably one having a Tg of 80 ° C. or higher, more preferably 100 ° C. or higher, when the monomer is polymerized into a homopolymer from the viewpoint of shrinkage. preferable.
Preferable examples of the hydrophobic vinyl monomer (a-2) include alkyl (meth) acrylate, styrene, alkyl acrylamide, and alkyl methacrylamide. Examples of the alkyl group contained in these monomers include a linear or branched hydrocarbon having 1 to 12 carbon atoms, a hydrocarbon group having a monocyclic or polycyclic aliphatic ring or aromatic ring having 5 to 25 carbon atoms. And a hydrocarbon group having a linear or branched alkyl group having 1 to 8 carbon atoms as a substituent in the ring.
Among these, from the viewpoint of shrinkability, methyl (meth) acrylate, butyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, styrene, butylacrylamide, and butylmethacrylamide are particularly preferable. Methacrylate and tert-butylacrylamide are preferred.
A hydrophobic vinyl monomer (a-2) can be used individually or in mixture of 2 or more types.

The Tg of the amphiphilic polymer (A) is 100 ° C. or higher, preferably Tg 105 ° C. or higher, more preferably Tg 110 ° C. or higher, and particularly preferably Tg 120 ° C. or higher from the viewpoint of shrinkage. Moreover, although it is preferable from a viewpoint of an eyelash curl improvement so that Tg is high, Tg250 degrees C or less is preferable from the restrictions on manufacture, and Tg230 degrees C or less is more preferable.
The glass transition temperature is a value measured by a differential scanning calorimeter. Specifically, when measurement is performed under the conditions of the following continuous temperature programs 1 to 4, the value measured by the temperature program 3 is defined as Tg.
Temperature program:
1.30 to 250 ° C .: Temperature rising rate 30 ° C./min, holding time 1 min
2.250 to -100 ° C: cooling rate 200 ° C / min, holding time 10 min
3. −100 to 250 ° C .: Temperature rising rate 10 ° C./min, holding time 1 min
4.250 to 30 ° C .: cooling rate 30 ° C./min, holding time 2 min
Tg is measured after neutralization of the carboxyl group contained in the amphiphilic polymer (A) as described later.

The content of the structural unit derived from methacrylic acid and / or its salt (a-1) contained in the amphiphilic polymer (A) is preferably 15% by mass, more preferably 15 to 98% by mass, from the viewpoint of shrinkage. Preferably, 20 to 90 mass% is more preferable, and 40 to 80 mass% is particularly preferable.
Further, the content of the structural unit derived from the hydrophobic vinyl monomer (a-2) contained in the amphiphilic polymer (A) is preferably 2 to 80% by mass in order to obtain the stability of the emulsion. 80 mass% is more preferable, and 20-60 mass% is still more preferable.

The mass average molecular weight of the amphiphilic polymer (A) is a value measured by gel permeation chromatography (GPC) using polystyrene as a standard substance, preferably 5,000 to 1,000,000, and 8,000. More preferred is ˜500,000. If the mass average molecular weight is 5,000 or more, good shrinkage effect can be obtained, and if it is 1,000,000 or less, moderate ease of application can be maintained.
The carboxyl group contained in the amphiphilic polymer (A) is preferably neutralized from the viewpoint of use as a cosmetic. In the neutralization treatment, the degree of neutralization is preferably in the range of 0.01 to 0.6 equivalents, and in the range of 0.02 to 0.3 equivalents in terms of the number of equivalents of neutralizing agent with respect to 1 equivalent of acid. More preferred. Further, the pH value after the neutralization treatment is preferably 4.8 to 7.8, and more preferably 5.0 to 7.5.
As the neutralizing agent, one or more kinds selected from L-arginine, potassium hydroxide, sodium hydroxide, ammonia, 2-aminomethyl-1-propanol, 2-aminomethyl-propanediol and tris (hydroxymethyl) aminomethane It is preferable to use a basic compound.

[Hydrophobic polymer (B)]
The hydrophobic polymer (B) is a polymer that forms the core of the core-shell type polymer particle of the present invention, includes a structural unit derived from the hydrophobic vinyl monomer (b), and has a Tg of 10 ° C. or less, preferably 5 It is a polymer at a temperature of 0 ° C. The lower the Tg, the better the softness can be felt when forming a film. The Tg of the hydrophobic polymer (B) is measured in the same manner as the Tg of the amphiphilic polymer (A).
The hydrophobic polymer (B) is preferably not crosslinked from the viewpoint of the water resistance of the film.

The hydrophobic vinyl monomer (b) is synonymous with the hydrophobic vinyl monomer (a-2) in a broad sense. That is, when the vinyl monomer is dissolved in 100 g of water at 20 ° C., the vinyl monomer has a dissolution amount of 2 g or less, preferably 1.8 g or less.
The hydrophobic vinyl monomer (b) is preferably one having a Tg of 20 ° C. or less when the monomer is polymerized to form a homopolymer from the viewpoint of softness when used for cosmetics. Those are more preferred.

The hydrophobic vinyl monomer (b) preferably has a hydrocarbon chain having 2 to 45 carbon atoms, more preferably 4 to 25 carbon atoms, and still more preferably 8 to 20 carbon atoms. The hydrocarbon chain may be either linear or branched. Moreover, you may contain the hydrocarbon group which has a monocyclic or polycyclic aliphatic ring or an aromatic ring. Further, the ring may further contain a hydrocarbon group having a linear or branched alkyl group as a substituent. Alkyl (meth) acrylate is preferably used. For example, ethyl (meth) acrylate, 3-methoxyethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) ) Acrylate, tert-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, 2-phenylethyl (meth) acrylate, benzyl (meth) Examples include acrylate, tetradecyl (meth) methacrylate, diethylaminoethyl (meth) acrylate, diisopropylaminoethyl (meth) acrylate, and the like.
Among these, ethyl (meth) acrylate, isobutyl (meth) acrylate, and n-lauryl (meth) acrylate are particularly preferable.
In addition, a hydrophobic vinyl monomer (b) can be used individually or in mixture of 2 or more types. Moreover, as long as Tg of hydrophobic polymer (B) is 10 degrees C or less, monomers other than said monomer can also be copolymerized.

[Polymer emulsion for cosmetics]
The mass ratio of the amphiphilic polymer (A) to the hydrophobic polymer (B) in the core-shell type polymer particles is selected from the viewpoint of achieving both shrinkability and water resistance formed from the polymer emulsion [(A) / (B )] Is preferably 1/1 to 1/10, more preferably 1/1 to 1/7, and particularly preferably 1/1 to 1/5.
The particle size of the polymer particles in the polymer emulsion is preferably from 0.05 to 20 μm, more preferably from 0.08 to 15 μm, from the viewpoint of emulsion stability and the like. The particle size of the polymer particles can be measured using a laser diffraction particle size distribution measuring device.

[Method for producing polymer emulsion for cosmetics]
In the method for producing a cosmetic polymer emulsion of the present invention, an amphiphilic polymer (A) and a hydrophobic polymer (B) are contacted in an aqueous phase to form a polymer emulsion containing core-shell type polymer particles. If it is a method which can be performed, it will not specifically limit. For example, after the hydrophobic polymer (B) is polymerized by a known method, the obtained hydrophobic polymer (B) is pulverized and the amphiphilic polymer (A) is dispersed in the aqueous phase as a dispersant. be able to.
However, in order to efficiently produce the cosmetic polymer emulsion of the present invention, the amphiphilic polymer (A) is used as a dispersant, and the hydrophobic vinyl monomer (b) and the polymerization initiator are dispersed in an aqueous phase. It is preferable to employ a polymerization method.
Examples of the emulsifier used for dispersion include an ultrasonic homogenizer, a homomixer, a milder, an attritor, a (ultra) high pressure homogenizer, a nanomizer system, and a membrane emulsifier.

As the polymerization method, solution polymerization, bulk polymerization, precipitation polymerization, non-emulsification polymerization and the like can be used. The polymerization initiator is not particularly limited. For example, hydroperoxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, paramentane hydroperoxide, peroxides such as benzoyl peroxide, lauroyl peroxide, and azobisiso Examples thereof include organic polymerization initiators such as azo compounds such as butyronitrile, and inorganic polymerization initiators such as persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate. In addition, a so-called redox polymerization initiator in which a reducing agent such as sodium bisulfite, ascorbic acid or a salt thereof is used in combination with the polymerization initiator can also be used.
According to the production method of the present invention, the polymerization proceeds in a state where the amphiphilic polymer (A) is present around the droplets of the hydrophobic vinyl monomer (b) dispersed in water. Polymer particles having a structure are formed.

[Eyelash cosmetics]
Since the polymer emulsion for cosmetics of the present invention has a tensile effect due to the shrinkage of the formed film, it can be suitably blended in packs, lotions, eyelash cosmetics, etc. that can have a tensile function. it can. In particular, when the cosmetic for eyelashes blended with the polymer emulsion for cosmetics of the present invention is applied to the upper surface of the eyelashes, the curling property is exhibited by drying of the polymer emulsion, and the cosmetic durability is also improved.
The cosmetics for eyelashes of the present invention are applied not only to makeup cosmetics called mascara containing color pigments, but also to so-called eyelash base agents and makeup cosmetics called top coats. The fee is also included. Especially, the cosmetics for eyelashes of this invention can be utilized suitably as a compounding component of a mascara composition.

[Mascara composition]
The mascara composition preferably contains a wax in addition to the cosmetic polymer emulsion of the present invention. As the wax, a wax having a penetration of 8 or more is more preferable from the viewpoint of obtaining a particularly high curl-up effect. Here, the penetration is a value measured according to JIS K-2235-5.4. That is, a wax sample kept at 25 ° ± 0.1 ° C. was placed on a specified needle (needle mass 2.5 ± 0.02 g, needle holder mass 47.5 ± 0.02 g, weight mass 50 ± 0.05 g) measures the length of penetration for 5 seconds, and the value obtained by multiplying the penetration distance (mm) by 10 is defined as the penetration.
The wax can be appropriately selected from animal waxes, plant waxes, mineral waxes, synthetic waxes and the like. Specific examples include carnauba wax, beeswax, extremely hydrogenated jojoba oil, lanolin wax, microcrystalline wax, paraffin wax, glycerides solid at room temperature (25 ° C.), silicone wax, and the like. Of these, beeswax and microcrystalline wax are preferred. Said wax can be used individually or in mixture of 2 or more types.
The blending amount of the wax is preferably 0.1 to 20% by mass in the mascara composition. By blending 0.1% by mass or more, a sufficient curl-up effect of eyelashes can be obtained, and when it is 20% by mass or less, a good finish can be expected.

In the mascara composition, a monohydric or polyhydric alcohol can be blended in order to improve adhesion to eyelashes. Examples of monohydric alcohols include ethanol, isopropanol, and butyl alcohol. Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, glycerin, diglycerin, polyglycerin, 1 , 3-butylene glycol and the like. Among these, ethanol, propylene glycol, dipropylene glycol, and 1,3-butylene glycol are preferable from the viewpoint of ease of handling. These monovalent or polyhydric alcohols can be used alone or in admixture of two or more.
1-12 mass% is preferable in a mascara composition, and, as for the compounding quantity of monohydric or polyhydric alcohol, 2-10 mass% is still more preferable. If it is 1 mass% or more, the adhesion to eyelashes is improved, and if it is 12 mass% or less, the curl-up effect can be maintained.

In the mascara composition, within the range not impairing the object of the present invention, a film-forming polymer other than the cosmetic polymer emulsion, liquid oil, thickener, fiber, and other components that are usually added to cosmetics are blended. Can do.
Examples of the film-forming polymer include polyvinyl acetate, polyvinyl alcohol, and a silicone-based polymer. These polymers can be used regardless of cosmetic forms such as solution-based and emulsion-based products.
Liquid oil is used from the viewpoint of obtaining a beautiful finish. Specific examples include hydrocarbon oils such as light isoparaffin, liquid isoparaffin, liquid paraffin and heavy liquid isoparaffin; diisostearyl malate, isotridecyl isononanoate, glyceryl dimyristate, glyceryl diisostearate, myristic acid / isostearic acid Examples include esters and triglycerides such as glyceryl, neopentyl glycol dicaprate, castor oil, macadamian nut oil, and jojoba oil; and silicone oils such as dimethylpolysiloxane and methylphenylpolysiloxane.
0.01-10 mass% is preferable in a mascara composition, and, as for the compounding quantity of liquid oil, 1-8 mass% is still more preferable.

A thickener is a material that can be dissolved in an aqueous component and impart viscosity, and can be added to improve adhesion to eyelashes. The thickener is not particularly limited as long as it can be used in cosmetics. For example, natural thickeners such as guar gum, gum arabic, sodium alginate, carrageenan, xanthan gum, modified corn starch, starch; semi-synthetic thickeners such as methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, cationized hydroxyethylcellulose Synthetic vinyl thickeners such as carboxyvinyl polymer, acrylic polymer such as sodium polyacrylate, polyvinyl alcohol, polyvinyl pyrrolidone, vinyl pyrrolidone / vinyl alcohol copolymer, polymethyl vinyl ether;
The blending amount of the thickener is preferably 0.01 to 20% by mass and more preferably 0.5 to 10% by mass in the mascara composition from the viewpoint of improving adhesion to eyelashes.

Fibers can be included to enhance the long lash effect. Examples of the fibers include natural fibers such as cotton, silk, and linen, recycled fibers such as rayon, and synthetic fibers such as polyamide, polyester, acrylic resin, and polyolefin. Polyamide fibers such as nylon are preferable from the viewpoint of strength. If necessary, for example, fibers subjected to surface treatment such as silica treatment, silicone treatment, fluorine compound treatment, metal soap treatment, oil treatment can be used. The form of the fiber is preferably 0.1 to 20 T in thickness and 0.1 to 5 mm in length from the viewpoint of adhesion to eyelashes.
The blending amount of the fiber is preferably 0.1 to 6% by mass in the mascara composition from the viewpoint of obtaining a sufficient long rush effect.

Examples of other components usually added to cosmetics include pigments, surfactants, UV absorbers, UV scattering agents, moisturizers, antioxidants, fragrances, preservatives, and the like. These may be used alone or in admixture of two or more.
Examples of the pigment include inorganic pigments, organic pigments and extender pigments. Examples of the inorganic pigment include titanium oxide, black titanium oxide, zinc white, bengara, yellow iron oxide, black iron oxide, and the like. Examples of the organic pigment include tar dye.
The pigment may be surface-treated, for example, silica treatment, alumina treatment, silica-alumina treatment, hydrophilic treatment such as polyacrylic acid treatment, silicone treatment, fluorine compound treatment, metal soap treatment, lecithin treatment, fat treatment. Those subjected to an isohydrophobic surface treatment can be used.
Among them, the pigment subjected to the hydrophilized surface treatment has a high affinity with the polymer emulsion, and in particular, the pigment treated with polyacrylic acid is more preferable in terms of the curl-up effect and finish.
0.1-20 mass% is preferable in the cosmetics for eyelashes, and, as for the compounding quantity of a pigment, 1-8 mass% is still more preferable.
Examples of the surfactant include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphiphilic surfactant.

  The mascara of the present invention comprises a solution system using a solvent that dissolves the core-shell polymer of the present invention, an oil-in-water emulsion system (O / W) using water, and a water-in-oil emulsion system (W / O). Etc. are provided. Among these, an oil-in-water type emulsion system (O / W) is preferable from the viewpoint of improving the curl-up effect.

Production Example 1 (Amphiphilic polymer (A) solution: production of poly (methacrylic acid / tert-butylacrylamide) sodium salt aqueous solution)
1900 g of ethanol was put in a glass reaction vessel, nitrogen bubbling was performed at room temperature for 30 minutes, and then heated to 63 ° C. in a nitrogen atmosphere. A solution of 6.1 g of azo polymerization initiator 2,2′-avizos (2,4-dimethylvaleronitrile) (Wako Pure Chemical Industries, Ltd., V-65) dissolved in 30 g of ethanol was added, and then methacrylic acid. A mixture consisting of 300 g, tert-butylacrylamide 300 g, and ethanol 490 g was added over 2 hours. After completion of the addition of the mixture, the mixture was stirred at 63 ° C. for 6 hours, then heated to 71 ° C. and stirred for 2 hours to perform polymerization.
The obtained polymer solution was dropped into hexane to perform reprecipitation. The precipitate was collected and dried at 70 ° C. for 12 hours or more under reduced pressure to obtain poly (methacrylic acid / tert-butylacrylamide). The polymer composition measured by NMR was methacrylic acid / tert-butylacrylamide = 56/44 (mass ratio). The mass average molecular weight measured by GPC was 66,000 (polystyrene conversion).
8.34g of 1N sodium hydroxide aqueous solution was dripped at the liquid which melt | dissolved 15g of obtained poly (methacrylic acid / tert- butyl acrylamide) in 70g of ethanol. Furthermore, 70 g of water was added, and ethanol was distilled off with an evaporator to obtain a poly (methacrylic acid / tert-butylacrylamide) sodium salt aqueous solution (degree of neutralization 0.08). It was 213 degreeC as a result of measuring Tg of this polymer with the differential scanning calorimeter (The Seiko Instruments Inc. make, DSC6200. The measurement of Tg is the same below). The Tg of the tert-butylacrylamide homopolymer is 135 ° C.
The obtained polymer solution had a pH of 5.8, and the solid content after concentration by an evaporator was 22%.

Example 1 (Production of polymer emulsion)
The polymer solution obtained in Production Example 1 was diluted with water to a concentration of 12.5% to prepare 250 g of an aqueous phase. On the other hand, 30 g of lauryl methacrylate, 0.4 g of methacrylic acid and 0.4 g of lauroyl peroxide as an initiator were added and mixed to obtain a uniform oil phase. This oil phase was added to the aqueous phase and stirred at 8000 rpm for 12 minutes with a homomixer. Thereafter, polymerization was carried out at 70 ° C. for 4 hours, and after raising the temperature to 80 ° C., the polymerization was continued for 2 hours to obtain a polymer emulsion. This polymer emulsion was an emulsion containing polymer particles having polylauryl methacrylate (PLMA) as a core part and poly (methacrylic acid / tert-butylacrylamide) as a shell part.
The obtained polymer emulsion had a pH of 5.8 and a particle diameter (median diameter) measured by using a laser diffraction particle size distribution analyzer (LA-920, manufactured by Horiba, Ltd.) was 8 μm. Further, after the polymerization, the solid content after concentration by an evaporator was 42%. The Tg of the core polymer was -65 ° C.

Example 2 (Production of polymer emulsion)
The same procedure as in Example 1 was performed except that 30 g of the lauryl methacrylate in the oil phase of Example 1 was changed to 90 g, and polylauryl methacrylate (PLMA) was used as the core part, and poly (methacrylic acid / tert-butylacrylamide) was used as the shell part. An emulsion containing polymer particles was obtained.
Example 3 (Production of polymer emulsion)
The same procedure as in Example 1 was carried out except that 30 g of the lauryl methacrylate in the oil phase of Example 1 was changed to 120 g. Polylauryl methacrylate (PLMA) was used as the core part, and poly (methacrylic acid / tert-butylacrylamide) was used as the shell part. An emulsion containing polymer particles was obtained.

Example 4 (Production of polymer emulsion)
The same procedure as in Example 1 was performed except that 30 g of lauryl methacrylate in the oil phase of Example 1 was changed to 30 g of isobutyl acrylate, polyisobutyl acrylate (PiBuAA) was used as the core, and poly (methacrylic acid / tert-butylacrylamide) was the shell. An emulsion containing polymer particles in parts was obtained. The Tg of the core polymer was −24 ° C.
Example 5 (Production of polymer emulsion)
The same procedure as in Example 1 was performed except that 30 g of lauryl methacrylate in the oil phase of Example 1 was changed to 90 g of isobutyl acrylate, polyisobutyl acrylate (PiBuAA) was used as the core, and poly (methacrylic acid / tert-butylacrylamide) was the shell. An emulsion containing polymer particles in parts was obtained.
Example 6 (Production of polymer emulsion)
The same procedure as in Example 1 was performed except that 30 g of lauryl methacrylate in the oil phase of Example 1 was changed to 150 g of isobutyl acrylate. An emulsion containing polymer particles in parts was obtained.

Example 7 (Production of polymer emulsion)
The same procedure as in Example 1 was performed except that 30 g of lauryl methacrylate in the oil phase of Example 1 was changed to 26 g of ethyl acrylate and 4 g of ethyl methacrylate, and a polyethyl acrylate / ethyl methacrylate copolymer (PEA / EMA) was used as the core part. An emulsion containing polymer particles having poly (methacrylic acid / tert-butylacrylamide) as a shell portion was obtained. The Tg of the core polymer was -14 ° C.

Comparative Example 1
In Example 1, it carried out like Example 1 except not having used a core polymer (polylauryl methacrylate (PLMA)).
Comparative Example 2
1050 g of ion-exchanged water and 0.75 g of sodium N-stearoyl-N-methyltaurine (Nikko Chemicals, Nikkor SMT) were added to a glass reaction vessel, and the temperature was raised to 70 ° C. Thereafter, nitrogen was flowed at 130 ml / min for 10 minutes. As a peroxide polymerization initiator, 3 g of ammonium persulfate (manufactured by Sigma Aldrich Japan Co., Ltd.) was dissolved in 30 g of water and added to the reaction vessel. Next, a mixture of 243 g of methyl methacrylate (manufactured by Mitsubishi Gas Chemical Co., Ltd.), 339 g of butyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.), and 22.5 g of acrylic acid (manufactured by Toagosei Co., Ltd., 80% aqueous solution) is taken over 3 hours. And added to the reaction vessel. After completion of the addition, polymerization was performed at 70 ° C. for 1 hour, and then the temperature was raised to 75 ° C. and aging was performed for 3 hours. Then, it cooled to room temperature and 87 g of 1N sodium hydroxide aqueous solution (made by Wako Pure Chemical Industries Ltd.) was added. The resulting polymer emulsion is a single layer film-forming polymer emulsion (degree of neutralization 0.35) consisting of polymethyl methacrylate / butyl acrylate / acrylic acid (mass ratio) = 40.5 / 56.5 / 3. This was concentrated to a concentration of 50%.

(Evaluation of polymer emulsion)
The shrinkage, flexibility, and water resistance of the films formed from the polymer emulsions for cosmetics obtained in Examples 1 to 7 and Comparative Examples 1 and 2 were evaluated by the following methods, and the results are shown in Table 1. .
Evaluation of film shrinkage (hair curl angle)
Take three pieces of hair with a length of 1 to 1.5 cm and fix them horizontally. The polymer emulsion was applied 10 times to this hair at 23 ° C. and a relative humidity of 60%, and the warp angle of the hair from the horizontal plane was measured. The measurement was performed three times, and the average value was evaluated based on the following criteria with the warp angle.
Evaluation of Flexibility of Film The polymer emulsion and mascara liquid were cast on a 75 μm nylon film at a thickness of 200 μm, dried overnight, and then repeatedly bent at 90 degrees to evaluate the number of bendings when the film was broken.
Evaluation of Water Resistance of Film A polymer emulsion was developed on a Teflon petri dish and dried overnight. The time until water was dropped on the dried film and whitened was measured and evaluated.

Examples 8 to 9 and Comparative Examples 3 to 4 (production of mascara liquid)
Polymer emulsions obtained in Examples 1 and 7 and Comparative Examples 1 and 2, Carnauba wax (manufactured by Celalica Noda, refined carnauba wax No. 1, penetration 1 or less), beeswax (manufactured by Croda Japan Co., Ltd., BEES) WAX-S, penetration 18), stearic acid (manufactured by Kao Corporation, purified stearic acid 700V), 2-amino-2-methyl-1-propanol), polyoxyethylene monostearate (oxyethylene addition moles: 15) By preparing glycerin and black iron oxide (manufactured by Miyoshi Kasei Co., Ltd., PA-Black BL-100, 3% polyacrylic acid-treated black iron oxide), and uniformly stirring and mixing the components at the ratios shown in Table 2 A mascara composition was prepared. The viscosity of each composition was in the range of 100 to 2000 Pa · s at a temperature of 25 ° C.
The shrinkage, flexibility and water resistance of the film formed from the obtained mascara liquid were evaluated by the following methods, and the results are shown in Table 2.
Evaluation of film shrinkage (film bending test)
At the center of a 2 × 5 cm PET film (Madenex S, manufactured by Teijin DuPont Co., Ltd., film thickness 75 μm) with one end of the short side fixed to a slide glass with tape, 0.04 g of a 4 mm wide strip of mascara is applied. The film is dried under the conditions of 23 ° C. and 60% RH, and the curvature angle of the film after 3 hours is measured. The angle was measured with a protractor, three points were measured per sample, and the average value was taken as the bending angle.
Film Flexibility Evaluation Polymer emulsion and mascara liquid were cast on a 75 μm nylon film at a thickness of 200 μm, dried overnight, and then repeatedly bent at 90 degrees to evaluate the number of times the film was bent.
Evaluation of water resistance of film 10 g of mascara solution was applied to artificial leather in the range of 1.5 cm × 1.5 cm and dried overnight. Water was dropped on the dried film, and it was struck with a finger once a second, and the time until the film oozed or collapsed was measured and evaluated.

  The polymer emulsion for cosmetics of the present invention is excellent in the curl-up effect due to high shrinkage, and can form a cosmetic film maintaining flexibility and water resistance at a high level. For this reason, when it is formulated into makeup cosmetics for eyelashes, especially mascara, it gives the eyelashes an excellent curl-up effect and has excellent flexibility and water resistance, so the curl retention effect lasts for a long time and the finish is beautifully maintained. can do.

Claims (8)

  A polymer emulsion containing core-shell type polymer particles, wherein the polymer in the shell part is derived from a structural unit derived from methacrylic acid and / or a salt thereof (a-1) and a hydrophobic vinyl monomer (a-2) The unit is an amphiphilic polymer (A) having a glass transition temperature of 100 ° C. or higher, the core polymer includes a structural unit derived from the hydrophobic vinyl monomer (b), and the glass transition temperature is 10 ° C. or lower. A polymer emulsion for cosmetics, which is a hydrophobic polymer (B).   The polymer emulsion for cosmetics of Claim 1 whose content rate of the structural unit derived from methacrylic acid and / or its salt (a-1) in an amphiphilic polymer (A) is 15 mass% or more.   The cosmetic polymer emulsion according to claim 1 or 2, wherein the mass ratio of [amphiphilic polymer (A) / hydrophobic polymer (B)] is 1/1 to 1/10.   The polymer emulsion for cosmetics according to any one of claims 1 to 3, wherein the hydrophobic vinyl monomer (a-2) has a glass transition temperature of 80 ° C or higher when the monomer is polymerized to form a homopolymer.   The polymer emulsion for cosmetics according to any one of claims 1 to 4, wherein the hydrophobic vinyl monomer (b) has a hydrocarbon chain having 2 to 45 carbon atoms.   The polymer emulsion for cosmetics according to any one of claims 1 to 5, wherein the hydrophobic vinyl monomer (b) and the polymerization initiator are dispersed in an aqueous phase and polymerized using the amphiphilic polymer (A) as a dispersant. Manufacturing method.   A cosmetic for eyelashes comprising the cosmetic polymer emulsion according to any one of claims 1 to 5.   The cosmetic for eyelashes according to claim 7, wherein the cosmetic for eyelashes is mascara.