U.S. patent application number 09/892577 was filed with the patent office on 2002-03-21 for skin cosmetic composition.
This patent application is currently assigned to Kao Corporation. Invention is credited to Kiba, Atsuyuki, Kubo, Hideaki, Sakai, Shigefumi, Shigeno, Chitoshi.
Application Number | 20020034525 09/892577 |
Document ID | / |
Family ID | 27481406 |
Filed Date | 2002-03-21 |
United States Patent
Application |
20020034525 |
Kind Code |
A1 |
Sakai, Shigefumi ; et
al. |
March 21, 2002 |
Skin cosmetic composition
Abstract
A skin cosmetic composition comprising: a hydrogel particle
comprising a non-crosslinked hydrogel containing an oil component
therein dispersed in an aqueous medium; a hydrogel particle
comprising a non-crosslinked hydrogel containing an oil component
therein; and a process for preparing a hydrogel particle comprising
the steps of discharging an oil component-emulsified or dispersed
solution prepared by dissolving a non-crosslinked hydrogel in an
aqueous solution, with vibration from an orifice to form droplets;
and cooling the droplets to solidify.
Inventors: |
Sakai, Shigefumi;
(Sumida-ku, JP) ; Kiba, Atsuyuki; (Sumida-ku,
JP) ; Shigeno, Chitoshi; (Wakayama-shi, JP) ;
Kubo, Hideaki; (Wakayama-shi, JP) |
Correspondence
Address: |
OBLON SPIVAK MCCLELLAND MAIER & NEUSTADT PC
FOURTH FLOOR
1755 JEFFERSON DAVIS HIGHWAY
ARLINGTON
VA
22202
US
|
Assignee: |
Kao Corporation
Chuo-ku
JP
|
Family ID: |
27481406 |
Appl. No.: |
09/892577 |
Filed: |
June 28, 2001 |
Current U.S.
Class: |
424/401 ;
514/54 |
Current CPC
Class: |
A61P 17/00 20180101;
B01J 13/0065 20130101; A61K 8/0204 20130101; A61K 8/73 20130101;
A61K 8/042 20130101; A61Q 19/00 20130101; A61K 8/0283 20130101;
A61K 8/65 20130101; A61K 8/68 20130101; B01J 13/0056 20130101 |
Class at
Publication: |
424/401 ;
514/54 |
International
Class: |
A61K 007/00; A61K
031/715 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 30, 2000 |
JP |
2000-198543 |
Jun 30, 2000 |
JP |
2000-199401 |
Aug 14, 2000 |
JP |
2000-245708 |
Aug 14, 2000 |
JP |
2000-245709 |
Claims
What is claimed is:
1. A skin cosmetic composition comprising: (B) a hydrogel particle
comprising a non-crosslinked hydrogel containing an oil component
therein dispersed in (B) an aqueous medium.
2. The skin cosmetic composition according to claim 1, wherein the
hydrogel particle (A) further comprises an emulsifying agent or
dispersing agent.
3. The skin cosmetic composition according to claim 1, wherein the
hydrogel is made of agar or gelatin.
4. A hydrogel particle comprising a non-crosslinked hydrogel
containing an oil component therein.
5. The hydrogel particle according to claim 4, wherein the oil
component is emulsified or dispersed with an emulsifying agent or
dispersing agent.
6. The hydrogel particle according to claim 5, wherein the
emulsifying agent or dispersing agent comprises a macromolecular
emulsifying or dispersing agent.
7. The hydrogel particle according to claim 4, wherein the oil
component comprises a solid fat, and the melting point of the oil
component is not less than 35.degree. C.
8. The hydrogel particle according to claim 4, wherein the oil
component comprises a solid ceramide or an analog thereof.
9. The hydrogel particle according to claim 4, wherein not less
than 80% by weight of the hydrogel particle is composed of a
hydrogel particle having a ratio of a longest diameter to a
shortest diameter (longest diameter/shortest diameter) of not more
than 1.7.
10. The hydrogel particle according to claim 4, wherein the
hydrogel particle has a breaking intensity of 2 to 40 kPa and a
Young's modulus of 10 to 150 kPa.
11. The hydrogel particle according to claim 4, wherein the
non-crosslinked hydrogel is made of agar or gelatin.
12. The hydrogel particle according to claim 4, wherein the
non-crosslinked hydrogel is made of agar having a gel strength of
not more than 68.6 kPa.
13. A process for preparing a hydrogel particle comprising the
steps of: discharging an oil component-emulsified or dispersed
solution prepared by dissolving a non-crosslinked hydrogel in an
aqueous solution, with vibration from an orifice to form droplets;
and cooling the droplets to solidify.
14. The process according to claim 13, wherein the oil component is
emulsified or dispersed in the aqueous component solution with at
least one of an emulsifying agent and a dispersing agent.
15. The process according to claim 13, wherein the non-crosslinked
hydrogel is made of agar or gelatin.
16. The process according to claim 13, wherein the non-crosslinked
hydrogel is made of agar having a gel strength of not more than
68.6 kPa.
17. A skin cosmetic composition comprising visibly recognizable
particles having an average particle diameter of 0.1 to 5 mm and an
aqueous medium having a viscosity of 300 to 5000 mPa.multidot.s at
25.degree. C. and a specific gravity of 0.7 to 2.0, said visibly
recognizable particles being dispersed in the aqueous medium.
18. The skin cosmetic composition according to claim 17, wherein
the particle comprises a conditioning component.
19. The skin cosmetic composition according to claim 17, wherein
the skin cosmetic composition is a lotion.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a skin cosmetic composition
having excellent utility, which gives sufficient moisturizing
effects while being free from tackiness and having refreshing
feeling. More specifically, the present invention relates to a skin
cosmetic composition which can be used as lotion and the like.
[0003] The present invention also relates to a hydrogel particle
and a process for preparing the same. More specifically, the
present invention relates to a hydrogel particle in which an oil
component is dispersed and which can be applied to cosmetics,
pharmaceuticals, quasi-drug, foods and the like.
[0004] 2. Discussion of the Related Art
[0005] Conventionally, as an aqueous cosmetic composition
containing an oil component for the purposes of giving moisturizing
effect, there have been known aqueous cosmetic compositions having
an emulsion form, a solubilized form or a double-layer form.
[0006] The aqueous cosmetic composition having an emulsion form
(milky lotion) can supplement an oily component to skin. However,
the emulsion sometimes becomes unstable when a component which
affects emulsion stability, such as an electrolyte is added to the
composition. As a result, there are some defects such that
moisturizing effects are impaired.
[0007] The aqueous cosmetic composition having a solubilized form
(lotion) imparts moisturizing effects to skin to some extent.
However, there are some defects in the composition such that the
amount of an oil to be used in the composition should be relatively
reduced, so that sufficient moisturizing effects are not
maintained.
[0008] Also, the aqueous cosmetic composition having a double-layer
form comprising an aqueous phase and an oil phase separated from
each other is excellent in moisturizing effects, and their effects
can be maintained. However, there are some defects in the
composition such that the selection of their components used in the
oil phase and the aqueous phase and the control of their
compositional ratio would be difficult for giving a homogeneous
dispersion only by shaking the composition upon use, and for
recovering the original double layer by allowing it to stand.
Especially, since a liquid oil is used in the composition in a
large amount as a component for the oil phase, there are some
defects in the composition such that the user's feel is unpleasant,
and that the composition is applied inhomogeneously upon use, so
that the composition is not good in fitness for the skin.
[0009] Under the above circumstances, there have been proposed
various capsule-containing cosmetic compositions having both
moisturizing effects and its maintaining effects, while exhibiting
the characteristics of the aqueous cosmetic composition having a
solubilized form (lotion).
[0010] For instance, there have been proposed a cosmetic
composition containing an oil-in-water type (hereinafter referred
to as O/W type) emulsion-incorporating capsule, wherein the capsule
has a shell containing calcium alginate, the content of which is
0.1 to 1.0% by weight based on the entire amount of the capsule
(Japanese Patent Laid-Open No. Hei 2-117610); an alginate
capsule-containing cosmetic composition in which a part of the
alginates is existing in the form of a polyvalent metal salt
containing a barium salt as an essential component, wherein the
capsules exist in the outer phase comprising an aqueous solution of
carboxyvinyl polymer, the pH of which is adjusted (Japanese Patent
Laid-Open No. Hei 11-29433); and a water-containing cosmetic
composition comprising soft capsules or spheres, the substrate of
which is agar (Japanese Patent Laid-Open No. Hei 1-193216).
[0011] The alginate-based capsule is prepared by reacting a
water-soluble alginate with a water-soluble calcium salt to form a
water-insoluble calcium alginate. Therefore, the incorporation of a
surfactant, a water-soluble polymer, or an inorganic salt, those
containing a di- or more valent metal ion, into the capsule is
restricted. The stability of the alginate capsule depends upon pH,
and the capsule is stable in a specified acidic region. However,
the capsule is dissolved and broken in an alkaline region. In
addition, if the washing of the polyvalent metal ions used in the
curing reaction is insufficient after the preparation of the
capsule, in the case where the outer phase comprises an aqueous
medium containing a thickener not having enough tolerance against a
salt, the viscosity of the aqueous medium is reduced by the
remaining polyvalent metal ions, so that the dispersion of the
capsule becomes inhomogeneous, thereby making it unfavorable in
properties and appearance. Therefore, the aqueous medium is limited
to those containing a thickener such as a polysaccharide which
would not affect the aqueous medium, so that refreshing user's feel
free from tackiness is difficult to be obtained.
[0012] The soft capsule, the substrate of which is agar
necessitates agar in a high concentration in order to form a shell.
Therefore, there are some defects such that some residue of agar
remains on skin when the soft capsule is applied to the skin,
causing unpleasant feeling. In addition, as a process for preparing
a soft capsule, there has been known a process disclosed in
Japanese Patent Laid-Open No. Hei 1-193216 mentioned above.
However, it is difficult to obtain particles having high
monodispersibility efficiently.
[0013] An object of the present invention is to provide a skin
cosmetic composition in which particles are dispersed or suspended
in a liquid medium showing good appearance, being excellent in
storage stability without allowing the particles to float or
precipitate in the liquid medium with the passage of time, being
smooth on skin when applied thereto, and having no residue of
particles on the skin, thereby favorably exhibiting effects based
on the ingredients.
[0014] Another object of the present invention is to provide a skin
cosmetic composition in which specified particles are dispersed or
suspended in a flowable substrate having a relatively low
viscosity, and the visible particles give pretty impression, and
the ingredients can be uniformly spread over the skin when the
cosmetic composition is applied thereto, thereby realizing
refreshing feel without tackiness.
[0015] A still another object of the present invention is to
provide a hydrogel particle and a process for efficiently preparing
the same, whereby the hydrogel particle having high sphericity and
excellent monodispersibility, having an oil component therein
stably dispersed in high content, being applied to cosmetics,
pharmaceuticals, quasi-drug, and foods.
[0016] These and other objects of the present invention will be
apparent from the following description.
SUMMARY OF THE INVENTION
[0017] According to the present invention, there are provided:
[0018] (1) a skin cosmetic composition comprising:
[0019] (A) a hydrogel particle comprising a non-crosslinked
hydrogel containing an oil component therein dispersed in
[0020] (B) an aqueous medium;
[0021] (2) a hydrogel particle comprising a non-crosslinked
hydrogel containing an oil component therein;
[0022] (3) a process for preparing a hydrogel particle comprising
the steps of:
[0023] discharging an oil component-emulsified or dispersed
solution prepared by dissolving a non-crosslinked hydrogel in an
aqueous solution, with vibration from an orifice to form droplets;
and
[0024] cooling the droplets to solidify; and
[0025] (4) a skin cosmetic composition comprising visibly
recognizable particles having an average particle diameter of 0.1
to 5 mm and an aqueous medium having a viscosity of 300 to 500
mPa.multidot.s at 25.degree. C. as determined by Brookfield
viscometer and a specific gravity of 0.7 to 2.0, the visibly
recognizable particles being dispersed in the aqueous medium.
DETAILED DESCRIPTION OF THE INVENTION
[0026] The term "non-crosslinked hydrogel" as referred to herein
means a gel comprising water as a dispersion medium, in which the
formation of the gel is based upon not a crosslinking reaction via
potassium ions or calcium ions but a heat-reversible sol-gel
transformation. The polymer material which forms the above gel
includes, for instance, agar, gelatin and the like, and these
materials can be used alone or in admixture.
[0027] The dissolution temperature of the agar in water is
generally not less than 75.degree. C., principally 75.degree. to
90.degree. C. The gelatin temperature of an agar aqueous solution
upon cooling is 30.degree. to 45.degree. C.
[0028] Examples of the non-crosslinked hydrogel include agar and
gelatin. These non-crosslinked hydrogels can be used alone or in
admixture thereof. Among them, agar is preferable. The gel strength
of the agar is preferably not more than 68.6 kPa (700 g/cm.sup.2),
more preferably 19.6 kPa (200 g/cm.sup.2) to 63.7 kPa (650
g/cm.sup.2), from the viewpoint of texture upon use.
[0029] The gel strength is determined by NIKKAN-SUI-SIKI Method.
According to the NIK AN-SUI-SIKI Method, the gel strength is
determined by applying a load to a gel, being prepared by allowing
a 1.5% by weight agar aqueous solution to stand at 20.degree. C.
for 15 hours to harden, with a NIKKAN-SUI-SIKI gel strength
measuring device commercially available from KIYA SEISAKUSHO Co.,
Ltd. to obtain the maximum weight (g) per 1 cm.sup.2 surface area
of the gel when the gel endures the load for 20 seconds at
20.degree. C.
[0030] The term "hydrogel particle" as referred to herein means an
approximately spherical particle made of a hydrogel, and does not
include a so-called capsule composed of a shell and a core
material. One of the great features of the hydrogel particle of the
present invention resides in that the non-crosslinked hydrogel
forms a continuous phase, and an oil component is contained therein
as a dispersion phase.
[0031] The non-crosslinked hydrogel particle (A) is a particle
having a spherical shape, prepared by incorporating an oil
component usually used in cosmetics into a sol prepared by
dissolving a polymer for forming a non-crosslinked hydrogel in
water, and subjecting the gel to a heat-reversible sol-gel
transformation.
[0032] The content of the continuous phase in the hydrogel particle
is preferably 40 to 99% by weight, more preferably 40 to 92.5% by
weight, still more preferably from 60 to 90% by weight, especially
preferably 60 to 80% by weight, from the viewpoint of preventing
the breaking during washing of the hydrogel particle and
formulating it into cosmetics.
[0033] The content of the polymer for forming the non-crosslinked
hydrogel in the continuous phase is preferably 0.25 to 5.1% by
weight, more preferably 0.75 to 2.0% by weight, from the viewpoints
of giving excellent texture upon use and preventing the breaking
during washing of the hydrogel particle and formulating it into
cosmetics.
[0034] Accordingly, the content of the non-crosslinked
hydrogel-forming substance in the hydrogel particles is preferably
0.1 to 5.0% by weight, more preferably 0.3 to 2.0% by weight.
[0035] On the other hand, as the oil component, various fats and
oils such as solid fats and liquid oils can be used. In a skin
cosmetic composition, the oil component is added for the purpose of
skin care. The skin care can be carried out by giving skin
moisturizing properties, and softening and smoothening the skin,
thereby improving the texture of the skin.
[0036] The oil component includes, for instance, liquid oils such
as hydrocarbon oils, ester oils and plant oils; solid to semisolid
oils such as hardening oils, solid paraffins, Vaseline, and
ceramides and analogs thereof, such as natural ceramides of Types I
to VI, ceramide derivatives having sugar moiety, and aliphatic
amide derivatives of ceramide analogs such as N-(2-hydroxy-3
-hexadecyloxypropyl)-N-2-hydroxyethylhexadecanamid- e and
N-(2-hydroxy-3 -hexadecyloxypropyl)-N-2-hydroxyethyldecanamide,
higher alcohols (14 to 22 carbon atoms), higher fatty acids (12 to
22 carbon atoms), glyceride, ethylene glycol di-fatty acid esters
(number of carbon atoms of the fatty acid moiety being 12 to 36),
and dialkyl ethers (total number of carbon atoms: 12 to 36);
oil-soluble vitamins; and liquid, semisolid or solid silicones. The
oil-soluble vitamins include vitamin A, vitamin E, vitamin D and
derivatives thereof, such as fatty acid esters of vitamin A
(palmitate, acetate and the like), fatty acid esters of vitamin E
(acetate, linoleate and the like) and the like. The silicones
include, for instance, silicone oils such as dimethyl polysiloxane,
methylphenyl polysiloxane, octamethyl cyclotetrasiloxane,
decamethyl cyclopentasiloxane and methyl hydrogenpolysiloxane;
dimethyl polysiloxanes having a high polymerization degree;
silicone resins; silicone rubbers; silicone beads; amino-modified
silicones; alkyl-modified silicones; and the like.
[0037] The term "solid fat" as referred to herein means an oil
component having a melting point of not less than 35.degree. C. The
term "liquid fat" as referred to herein means an oil component
having a melting point of less than 35.degree. C. The melting point
of the oil component is a value as determined by differential
scanning calorimetry (hereinafter referred to as DSC).
[0038] It is preferable that the oil component contains a solid
fat, or a solid fat and a liquid oil, from the viewpoint of
preventing leakage of the oil component from the hydrogel particle
during the high-temperature storage.
[0039] The melting point of the oil component is preferably not
less than 35.degree. C., more preferably 40.degree. to 90.degree.
C., still more preferably 50.degree. to 90.degree. C., especially
preferably 60.degree. to 80.degree. C.
[0040] Among them, the melting point of the solid fat being
determined by DSC is preferably 40.degree. to 120.degree. C., more
preferably 50.degree. to 100.degree. C., especially preferably
50.degree. to 90.degree. C.
[0041] The content of the solid fat in the oil component is
preferably 1 to 80% by weight, more preferably 6 to 80% by weight,
still more preferably 10 to 70% by weight, most preferably 19 to
70% by weight, from the viewpoint of suppressing the leakage of the
oil component from the hydrogel particle and from the viewpoint of
giving skin smoothness.
[0042] The content of the liquid oil in the oil component is
preferably 20 to 99% by weight, more preferably 20 to 94% by
weight, still more preferably 30 to 90% by weight, most preferably
30 to 81% by weight, from the viewpoint of suppressing the leakage
of the oil component from the hydrogel particle and from the
viewpoint of giving skin smoothness.
[0043] In addition, there can be properly added to a continuous
phase or dispersed phase of the hydrogel particle sugars,
polyhydric alcohols, surfactants, polymers, ultraviolet shielding
agents, UV radiation absorbing substances, perfumes, colorants,
preservatives, powders and the like, as occasion demands. The
polymers include, for instance, acrylic, styrenic, ether-based,
ester-based, or silicone-based polymer emulsions or
suspensions.
[0044] The colorants include water-insoluble pigments, oil-soluble
dyes, vat dyes, lake dyes and the like. The pigments include, for
instance, inorganic pigments such as carbon black, talc, kaolin,
mica, mica titanium, red oxide, bismuth oxychloride, magnesium
silicate, titanium oxide and iron oxide; and organic pigments such
as Red 202, Red 204, Red 205, Red 206, Red 219, Red 228, Red 404,
Yellow 205, Yellow 401, Orange 401 and Blue 404. The oil-soluble
dyes include, for instance, Red 505, Red 501, Red 225, Yellow 404,
Yellow 405, Yellow 204, Orange 403, Blue 403, Green 202, Violet 201
and the like. The vat dyes include, for instance, Red 226, Blue
204, Blue 201 and the like. The lake dyes include, for instance,
those prepared by laking various acidic dyes with aluminum or
barium. These colorants can be used alone or in admixture
thereof.
[0045] The content of the oil component in the hydrogel particle
(A) is preferably 1 to 60% by weight, more preferably 10 to 60% by
weight, still more preferably 20 to 40% by weight, from the
viewpoints of the texture of the particle upon use and effects such
as moisturizing.
[0046] The average particle diameter of the hydrogel particle (A)
is preferably 0.005 to 10 mm, more preferably 0.1 to 10 mm, still
more preferably 0.5 to 5 mm, especially preferably 1.15 to 5 mm,
from the viewpoints of easiness in the preparation and
productivity. The average particle diameter of the hydrogel
particle (A) means a weight-average particle diameter determined by
classifying the hydrogel particles using screens having various
sieve-openings and calculating the weight-average particle diameter
in accordance with a screening method. Specifically, 100 g of the
hydrogel particles (A) are subjected to wet classification in water
by stacking screens with sieve-openings of 3.35 mm, 2.80 mm, 2.36
mm, 2.00 mm, 1.70 mm, 1.40 mm, and 1.00 mm. The weight-average
particle diameter is determined from a sieve-opening of each screen
(mm) and each weight percentage by weighing the particles remaining
on each screen and the particles passing through 1.00 mm sieve.
[0047] In the hydrogel particles (A), the weight ratio of the water
contained therein to the polymer constituting the hydrogel
[water/polymer] is preferably 25 to 1000, more preferably 50 to
500, from the viewpoints of making the particles unbreakable by
mechanical forces such as stirring and washing during the
preparation of the hydrogel particles and the addition to a
cosmetic composition, and giving excellent texture upon use and an
appropriate disintegration properties.
[0048] The shape of the hydrogel particle is not limited to
specified ones, and it is preferable that the hydrogel particle has
a shape corresponding to the rotation symmetry. The term "shape
corresponding to the rotation symmetry" means a shape produced by
rotating a figure formed by a continuous curve on its virtual axis,
and does not include a shape having a plane surface such as a
trigonal pyramid or a cylinder. It is more preferable that the
shape of the hydrogel particle is spherical, from the viewpoint of
appearance.
[0049] It is desired that the ratio of the longest diameter to the
shortest diameter (longest diameter/shortest diameter) of the
particle is not more than 1.7, preferably not more than 1.5, more
preferably not more than 1.2, from the viewpoint of appearance.
[0050] In addition, it is desired that hydrogel particles having a
ratio of the (longest diameter to the shortest diameter (longest
diameter/shortest diameter) of not more than 1.7 are contained in
the hydrogel particles in the content of not less than 80% by
weight, preferably not less than 90% by weight, from the viewpoint
of appearance. The longest diameter and the shortest diameter are
determined by the method for determining sphericity described in
Examples given below.
[0051] In addition, it is desired that the breaking intensity of
the hydrogel particle is 2 to 40 kPa, preferably 5 to 25 kPa, from
the viewpoint of improving texture upon use, and that the Young's
modulus of the hydrogel particle is 10 to 150 kPa, preferably 30 to
100 kPa.
[0052] When the breaking intensity is not less than 2 kPa, the
hydrogel particle is less breakable during washing of the hydrogel
particle and formulating the hydrogel particle into a cosmetic.
When the breaking intensity is not more than 40 kPa, the hydrogel
particle is extensible on skin and suited for the skin.
[0053] When the Young's modulus is not less than 10 kPa, the
hydrogel particle is less breakable during washing of the hydrogel
particle and formulating the hydrogel particle into a cosmetic, and
the oil component dispersed in the particles is less likely to leak
out from the hydrogel particle during washing. Also, when the
Young's modulus is not more than 150 kPa, the hydrogel particle is
extensible on skin.
[0054] The breaking intensity and the Young's modulus are
determined in accordance with the determination methods described
in Examples given below.
[0055] For instance, the hydrogel particle (A) containing an oil
component can be prepared as follows.
[0056] First, a water-soluble polymer for forming a non-crosslinked
hydrogel such as agar or gelatin is dispersed in ion-exchanged
water, and the mixture is sufficiently stirred and dissolved at a
temperature of not less than the dissolving temperature, to give a
sol. Thereafter, an oil component is mixed with the sol at a
temperature of not less than the gelation temperature, to give an
O/W type dispersion.
[0057] It is preferable that the average particle diameter of the
oil component is smaller than the particle diameter of the hydrogel
Also, it is more preferable that the average particle diameter is
not more than 10% of the particle diameter of the hydrogel.
However, it is desired that the average particle diameter of the
oil component is preferably not more than 500 .mu.m, more
preferably not more than 100 .mu.m, still more preferably not more
than 50 .mu.m, especially preferably not more than 20 .mu.m, from
the viewpoint that the hydrogel particles can be smoothly extended
on the skin. In addition, the average particle diameter of the oil
component is preferably not less than 0.5 .mu.m, more preferably
not less than 4 .mu.m, still more preferably not less than 5 .mu.m,
especially preferably not less than 10 .mu.m, from the viewpoint of
fitting of the oil component to the skin. In considerations of
these viewpoints, the average particle diameter of the oil
component is preferably from 0.5 to 500 .mu.m, more preferably from
4 to 100 .mu.m, still more preferably from 5 to 50 .mu.m,
especially preferably from 10 to 20 .mu.m.
[0058] The average particle diameter of the oil component is
intended to mean a volume-average particle diameter obtained by
measuring each particle diameter of the oil components contained in
the dispersion before the preparation of the hydrogel particle with
a laser diffraction/scattering type particle size analyzer
(commercially available from Horiba, LTD. under the Model No.
LA-910), and obtaining an average from the particle diameters as
shown in Examples given below.
[0059] It is preferable that the oil component contains an
emulsifying agent or a dispersing agent, so that the oil component
can stably exist in an emulsion or dispersion during the
preparation of the O/W dispersion.
[0060] The emulsifying agent and the dispersing agent include at
least one compound selected from the group consisting of polymer
emulsifying-dispersing agents, nonionic surfactants, anionic
surfactants, cationic surfactants and amphoteric surfactants. It is
desired that the concentration of the emulsifying agent and/or the
dispersing agent in the dispersion is usually 0.001 to 20% by
weight, preferably 0.005 to 10% by weight, more preferably 0. 1 to
5% by weight.
[0061] Among the emulsifying agents and the dispersing agents, a
combined use of at least one surfactant selected from the group
consisting of nonionic surfactants, anionic surfactants, cationic
surfactants and amphoteric surfactants, with the polymer
emulsifying-dispersing agent is preferable, more preferably a
combined use of the nonionic surfactant and the polymer
emulsifying-dispersing agent, still more preferably a single use of
the polymer emulsifying-dispersing agent, from the viewpoint of
spreadability on skin and handling during washing and formulating
into a cosmetic. When the polymer emulsifying-dispersing agent is
used, the tackiness caused by the surfactant can be reduced when
the particles are applied to skin, since the amount of the
surfactant can be reduced or omitted.
[0062] The polymer emulsifying-dispersing agent includes, for
instance, a copolymer of acrylic acid and alkyl methacrylate
(commercially available from B.F. Goodrich under the trade name of
PEMULEN, and the like); a composite prepared from an amphoteric
polymer and a higher fatty acid as disclosed in Japanese Patent
Laid-Open No. Hei 7-100356; water-soluble amphipathic polymer
electrolytes as disclosed in Japanese Patent Laid-Open Nos. Hei
8-252447 and Hei 9-141079; water-soluble crosslinked amphipathic
polymer electrolytes as disclosed in Japanese Patent Laid-Open Nos.
Hei 9-141080 and Hei 9-141081; synthetic polymers such as acrylic
acid-based copolymers, polyvinyl pyrrolidones, polyvinyl alcohols
and derivatives thereof, polyacrylamides and ethylene oxide adducts
of alkylphenol formaldehyde condensates as disclosed in Japanese
Patent Laid-Open No. Hei 10-53625; and natural polymers such as
guar gum, karaya gum, tragacanth gum, gum arabic, arabinogalactan
and casein. Among them, the copolymer of acrylic acid and alkyl
methacrylate, the acrylic acid-based copolymers (Carbopol) and the
polyvinyl alcohols are preferable, from the viewpoint of reduced
tackiness.
[0063] As the nonionic surfactants, the anionic surfactants, the
cationic surfactants and the amphoteric surfactants, those usually
used for cosmetics can be used alone or in admixture thereof.
[0064] The particle can be prepared from the dispersion thus
obtained by a general dropping method or stirring method.
[0065] The dropping method is a process for preparing a particle,
utilizing the technique such that a liquid obtained by discharging
a dispersion from an orifice is formed into a droplet by its
surface or interfacial tension. The droplet formed by the dropping
method is cooled to solidify in the atmosphere or in liquid, to
give a particle.
[0066] In the dropping method, a droplet can be formed in the
atmosphere, or in liquid. When the droplet is formed in the liquid,
the droplet can be formed in a stand-still liquid. It is preferable
that the droplet is formed in the liquid stream having a downward
flow, an upward flow or a cocurrent flow with a pipe for forming a
droplet. The end surface of the pipe can exist either in the
atmosphere or in the liquid. When the droplet is formed in the
liquid, it is preferable that the end surface exists in the
liquid.
[0067] The dispersion prepared in the above method is heated to a
temperature of not less than the gelation temperature, and the
dispersion is discharged from the orifice into the atmosphere such
as air or liquid in the form of a droplet or a liquid column.
During discharging, the liquid column is formed into a droplet by
its surface tension, and further cooled to solidify. In this case,
when the discharging rate is fast, the liquid column is cooled to
solidify in some cases before the formation of a droplet.
Therefore, it is preferable that the discharging rate is not so
fast. However, when a vibration is applied to the dispersion, the
formation of the liquid column into a droplet is accelerated, so
that the production efficiency is improved. In addition, when a
vibration is applied, since the size of the formed droplet becomes
even, the monodispersibility of the particles is improved.
Therefore, in order to improve the production efficiency and the
monodispersibility of the particles, it is preferable that the
vibration is applied to the dispersion. The method of applying
vibration is not limited. Examples of the method include a method
of applying vibration to an orifice, thereby applying vibration to
a liquid column; a method of applying vibration to a dispersion to
be discharged from an orifice before discharging; a method of
applying vibration to a liquid column discharged from an orifice by
pulsating flow of a cooling liquid; a method of applying vibration
to a liquid column discharged from an orifice by a vibrating ring
set around the liquid column; and the like.
[0068] Among the above methods, in order to efficiently carry out
the formation of particles of the dispersion, the method of
applying vibration to a dispersion to be discharged from an orifice
before discharging is preferable.
[0069] The frequency of the vibration can be properly selected
depending upon the discharging rate, i.e. linear velocity and the
liquid viscosity. The frequency applied is not limited, and the
frequency is preferably 1 to 2000 Hz, more preferably 5 to 200
Hz.
[0070] When the droplet is formed in the liquid, the droplet can be
formed in a stand-still liquid. It is preferable that the droplet
is formed in the liquid stream having downward flow, an upward flow
or a cocurrent flow with a pipe for forming a droplet. The flow
rate of the liquid in the liquid stream is preferably 0.8 to 5
times that of the dispersion. It is more preferable that the flow
rate is 0.8 to 2 times that of the dispersion, from the viewpoint
of making the size of the formed droplets even. In addition, the
end surface of the pipe can be positioned in either the atmosphere
or the liquid. When the droplet is formed in the liquid, it is
preferable that the end surface exists in the liquid.
[0071] The orifice diameter is not limited to specified ones. It is
desired that the orifice diameter is usually 0.1 to 5 mm. The
temperature of the dispersion discharged from the orifice is not
limited to specified ones as long as the temperature of the
dispersion is not less than the gelation temperature. It is desired
that the temperature of the dispersion is usually 40.degree. to
100.degree. C.
[0072] It is desired that the temperature of the gas or liquid for
solidifying the dispersion is not more than the gelation
temperature, preferably not more than 40.degree. C., more
preferably not more than 20.degree. C.
[0073] The stirring method is a process for preparing a particle,
using a technique such that a dispersion is added to a liquid being
substantially immiscible with the dispersion and
temperature-controlled to not less than the gelation temperature of
the non-crosslinked hydrogel, the dispersion is formed into fine
particles by shearing force with stirring, and the fine particles
are formed into a droplet by its surface tension. The droplet
formed by the stirring method is cooled to solidify in a liquid
substantially immiscible with the dispersion, to give a solid
particle.
[0074] The temperature of the dispersion as discharged of the
dispersion is not limited to specified ones. It is preferable that
the temperature of the dispersion is not less than the gelation
temperature of the non-crosslinked hydrogel and not more than
100.degree. C. It is desired that the temperature of the dispersion
is higher than the gelation temperature by not less than 10.degree.
C., preferably higher than the gelation temperature by not less
than 20.degree. C., from the viewpoint of easiness in preparing a
spherical particle having excellent appearance. It is desired that
the upper limit of the temperature is 100.degree. C., that is, a
boiling point of water.
[0075] The viscosity of the dispersion can be determined by a
Brookfield viscometer. The viscosity of the dispersion is not
limited to specified ones. It is desired that the viscosity of the
dispersion at discharging of the dispersion is usually 0.1 to 1000
mPa.multidot.s, preferably 1 to 800 mpa.multidot.s at the
temperature of discharging of the dispersion.
[0076] In the skin cosmetic composition of the present invention,
the hydrogel particle. (A) is dispersed in an aqueous medium (B) as
a substrate for a cosmetic composition.
[0077] It is desired that the content of the hydrogel particle (A)
in the skin cosmetic composition is 1 to 40% by weight, preferably
5 to 30% by weight, from the viewpoints of appearance and physical
properties.
[0078] In the present invention, the aqueous medium (B) is not
limited to specified ones, as long as the hydrogel particle (A) can
be stably and homogeneously dispersed therein, without
precipitating or floating. The aqueous medium can be used in any
forms such as transparent or semitransparent aqueous solutions, O/W
type emulsion or gel, and the like. The hydrogel particle
(A)-dispersed skin cosmetic composition can be designed in the
forms of lotion, milky lotion, cream, gelated cosmetic and the
like.
[0079] In order to impart desired liquid properties to the aqueous
medium (B), a water-soluble thickener can be contained in the
aqueous medium (B). As the water-soluble thickener, there can be
used, for instance, a water-soluble polymer, clay, and the like.
The amount of the water-soluble thickener can be selected, so that
the viscosity (Brookfield viscometer at 25.degree. C.) of the
aqueous medium (B) becomes appropriate for the viscosity and
specific gravity of the skin cosmetic composition.
[0080] The viscosity of the aqueous medium is 300 to 5000
mPa.multidot.s at 25.degree. C., preferably 500 to 3000
mPa.multidot.s, from the viewpoints of homogenous dispersibility of
the particles, appearance and users' feel, especially impression
and users' feel as a lotion.
[0081] The specific gravity of the aqueous medium is 0.7 to 2.0,
preferably 0.8 to 1.5, from the viewpoints of the
monodispersibility of the particles and the users' feel as
cosmetics.
[0082] In the present invention, the aqueous medium is preferably a
transparent or semitransparent flowable liquid having a viscosity
of 300 to 5000 mPa.multidot.s at 25.degree. C. and a specific
gravity of 0.7 to 2.0, from the viewpoints of giving the cosmetic
composition flowability especially useful as lotion, and
transparency in appearance. Further, since the particles to be
dispersed in the aqueous medium are stably dispersed and suspended
in the aqueous medium, the dispersion is excellent in appearance,
and also gives refreshing feel.
[0083] The phrase "the aqueous medium is transparent or
semitransparent" as used herein means that the light transmittance
is not less than 30%.
[0084] The aqueous polymers include, for instance, plant-based
polymers such as gum arabic, tragacanth gum, galactan, carob gum,
guar gum, karaya gum, carrageenan, pectin, agar, quince seed gum
(marmelo), starches (rice, Indian corn, white potato, wheat), and
algae colloids (brown algae extract); microorganism-based polymers
such as dextran, succinoglucan and pullulan; animal-based polymers
such as collagen, casein, albumin and gelatin; modified starches
such as carboxymethyl starch and methylhydroxypropyl starch;
modified celluloses such as methyl cellulose, ethyl cellulose,
methylhydroxypropyl cellulose, hydroxyethyl cellulose, sodium
cellulose sulfate, hydroxypropyl cellulose and sodium carboxymethyl
cellulose; alginates such as sodium alginate and propylene glycol
alginate; vinyl polymers such as polyvinyl methyl ether, and
carboxymethyl polymer (commercially available from BF Goodrich
under the trade name of CARBOPOL941, and the like); polyoxyethylene
polymers; polyoxyethylene-polyoxypropylene copolymer; acrylic
polymers such as sodium polyacrylate, polyethyl acrylate and
polyacrylamide; polyethyleneimine; cationic polymers; inorganic
compounds such as bentonite, aluminum magnesium silicate, hectorite
and silicic acid anhydride; cationic crosslinked copolymers
disclosed in Japanese Patent Laid-Open No. Hei 11-71435;
water-soluble polysaccharides disclosed in Japanese Patent
Laid-Open Nos. 9-235301 and 10-25301; and the like.
[0085] The cationic crosslinked copolymers disclosed in Japanese
Patent Laid-Open No. Hei 11-71435 are copolymers having a cationic
group and a crosslinked structure in its molecule. The cationic
crosslinked copolymers include, for instance, a cationic
crosslinked copolymer prepared by copolymerizing at least one
cationic group-containing vinyl monomer [hereinafter referred to as
monomer (a.sub.1)], at least one amide-group containing vinyl
monomer [hereinafter referred to as monomer (a.sub.2)], and at
least one crosslinkable vinyl monomer having not less than two
vinyl groups in its molecule [hereinafter referred to as monomer
(a.sub.3)] [hereinafter referred to as copolymer (A)], which give
the aqueous medium (B) favorable thixotropy.
[0086] Preferable concrete examples of the monomer (a.sub.1)
include acid-neutralized compounds of monomers having amino group
such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl
(meth)acrylate, dimethylaminopropyl (meth)acrylamide, and
diethylaminopropyl (meth)acrylamide, or quaternary ammonium salts
of these monomers prepared by quaternarizing the monomers with a
quaternalizing agent; dimethyldiallylammonium chloride; and the
like.
[0087] Preferable concrete examples of the monomer (a.sub.2)
include N,N-di-substituted (meth)acrylamide such as N,N-dimethyl
(meth)acrylamide and N,N-diethyl (meth)acrylamide; N-methyl
(meth)acrylamide, N-n-propyl (meth)acrylamide, N-t-butyl
(meth)acrylamide, N-(meth)acryloylmorpholine, N-vinylpiperidone,
N-vinylpyirolidone and the like. Among them, from the viewpoint of
improving the user's feel, N,N-di-substituted (meth)acrylamide is
preferable, and N,N-dimethyl (meth)acrylamide and N,N-diethyl
(meth)acrylamide are more preferable.
[0088] Preferable concrete examples of the monomer (a.sub.3)
include (meth)acrylates of polyhydric alcohols or unsaturated
alcohols; bis(meth)acrylamide, divinyl compounds, polyallyl
compounds; and the like. Among them, ethylene glycol
di(meth)acrylate, polyethylene glycol di(meth)acrylate,
pentaerythritol tetra(meth)acrylate, allyl ethers of
pentaerythritol, vinyl (meth)acrylate and allyl (meth)acrylate are
especially preferable.
[0089] As the cationic crosslinked copolymers, copolymers made of
preferably exemplified monomers (a.sub.1) to (a.sub.3) are
preferable. Especially, the combination of dimethylaminoethyl
(meth)acrylate/N,N-dime- thyl (meth)acrylamide/polyethylene glycol
di(meth)acrylate is preferable, from the viewpoint of thixotropy of
the aqueous medium (B).
[0090] The content of the monomer (a.sub.3) in the total monomers
is preferably 0.002 to 5% by mol, especially 0.002 to 3% by mol,
more especially 0.002 to 1% by mol. When the content of the monomer
(a.sub.3) is within the above range, the viscosity of the aqueous
medium (B) containing the copolymer (A) is suitable, thereby giving
soft texture and smoothness.
[0091] It is preferable that the pH of the aqueous medium (B) is 4
to 11, especially 4 to 6, from the viewpoint of being less irritant
to skin.
[0092] The method of dispersing and suspending the particles in the
aqueous medium (B) is not limited to specified ones, as long as the
particles can be stably and homogeneously dispersed without
precipitating the particles or allowing the particles to float.
Examples of the method include a method comprising adding an
aqueous dispersion of particles to the previously prepared aqueous
medium (B), and stirring the mixture to homogeneously disperse the
particles in the aqueous medium; and the like.
[0093] To the aqueous medium (B), there can be added those
components usually used in cosmetic compositions, such as
ultraviolet shielding agents, UV radiation absorbing substances,
moisturizing agents, alcohols, vitamins, hydroxycarboxylic acids
and salts thereof, preservatives, water-soluble polymers, coloring
matters, perfumes, antioxidants and the like in proper amounts. The
water-soluble vitamins include niacin, vitamin B.sub.2, vitamin
B.sub.6, vitamin C and biotin. The hydroxycarboxylic acids are
exemplified by glycolic acid, lactic acid, salicylic acid and the
like.
[0094] As described above, since the non-crosslinked hydrogel is
used in the hydrogel particle of the present invention, the
compositional restriction is eliminated, and at the same time the
hardness of the ingredients in the particle becomes uniform, so
that the hardness of the surface is not greater than that in the
inner part of the particle, as in the case of crosslinked hydrogel
particles. Therefore, the particle can be smoothly broken with
fingers when applied to the skin. Furthermore, since there is no
shell portion as in the case of a core-shell capsule, the hydrogel
particle is easily broken and spread over the skin, and no residue
of particles exists on the skin.
[0095] Another embodiment of the present invention, that is, a skin
cosmetic composition comprising visibly recognizable particles
having an average particle diameter of 0.1 to 5 mm and a specified
aqueous medium, the visibly recognizable particles being dispersed
in the aqueous medium is explained. The term "visibly recognizable"
as referred to herein means that non-transparent or colored
particles exist in the transparent or semitransparent aqueous
substrate, so that the presence of the particles can be visibly
recognized. In the present invention, since the above particles are
employed, the particles can be visibly recognized with naked eyes,
and the number of the particles can be counted, even when the
particles are dispersed in a transparent or semitransparent aqueous
substrate.
[0096] The visibly recognizable particles may be any of inorganic
particles and organic particles. Also, the visibly recognizable
particles may be granulated ones of such particles.
[0097] Examples of the inorganic particles and organic particles
include inorganic powders such as talc, mica, kaolin, muscovite,
synthetic mica, phlogopite, biotite, Lithia mica, vermiculite,
magnesium carbonate, calcium carbonate, diatomaceous earth,
magnesium silicate, calcium silicate, aluminum silicate, barium
silicate, strontium silicate, metal salts of tungstic acid,
hydroxyapatite, hydrated silicic acid, magnesium oxide, bentonite,
zeolite, ceramic powder and aluminum hydroxide; organic powders
such as nylon powder, polyethylene powder, polymethyl
benzoguanamine powder, polymethyl methacrylate powder,
polytetrafluoroethylene powder, fine crystalline cellulose, rice
starch and lauroyllysine; powders of metal salts of surfactants
such as calcium stearate, zinc stearate, magnesium stearate,
magnesium myristate, calcium cetyl phosphate and sodium zinc cetyl
phosphate; colored inorganic powders such as titanium oxide, zinc
oxide, zirconium oxide, iron oxide (red oxide), iron titanate, iron
hydroxide, loess, black iron oxide, carbon black, manganese violet,
cobalt violet, chromium oxide, chromium hydroxide, cobalt titanium,
ultramarine and Prussian blue; pearly pigments such as titanium
oxide-coated mica, titanium oxide-coated bismuth oxychloride,
bismuth oxychloride, titanium oxide-coated talc, scale foil and
tinted titanium oxide-coated mica; metal powders such as aluminum
powder, stainless steel powder and copper powder; powders generally
well used in cosmetics; powders prepared by treating the above
powders with silicone or a fluorine compound; and the like. In
addition, the hydrogel particle formed from agar, gelatin and the
like can be preferably used.
[0098] The form of the visibly recognizable particles includes
granules of powders, and non-encapsulated particles such as gel
particles. It is preferable that the shape is spherical, from the
viewpoints of appearance and easiness in preparation. Among the
particles, those which are breakable with fingers upon applying to
the skin are preferable. On the other hand, those particles which
are hardly breakable during its preparation, addition to cosmetics,
or storage in, for instance, a container are preferable.
[0099] In addition, it is preferable that an oily or aqueous
conditioning component is contained in the particle. For instance,
when the oil component which is separated from the aqueous
substrate, or which makes the aqueous substrate white turbid is
contained in the particles, the particles can be visibly recognized
from the outside, without impairing transparency or
semitransparency of the aqueous substrate.
[0100] The oily conditioning component is added to the particles
because the oily conditioning component gives moisture, and softens
or smoothens the skin. As the oily conditioning component, various
volatile and non-volatile conditioning components can be used.
[0101] The oily conditioning component includes, liquid oils such
as hydrocarbon oils, ester oils and plant oils; solid to semisolid
oil agents such as solid paraffms, Vaseline, ceramides, and analogs
thereof, such as natural ceramides of Types I to VI, and aliphatic
amide derivatives of ceramide analogs such as
N-(2-hydroxy-3-hexadecyloxypropyl- )-N-2-hydroxyethylhexadecanamide
and N-(2-hydroxy-3 -hexadecyloxypropyl)-N-2-hydroxyethyldecanamide,
higher alcohols (14 to 22 carbon atoms), glyceride, ethylene glycol
di-fatty acid esters (number of carbon atoms of the fatty acid
moiety being 12 to 36), and dialkyl ethers (total number of carbon
atoms: 12 to 36); and liquid, semisolid or solid silicones. The
silicones include, for instance, silicone oils such as dimethyl
polysiloxane, methylphenyl polysiloxane, octamethyl
cyclotetrasiloxane, decamethyl cyclopentasiloxane and methyl
hydrogenpolysiloxane; dimethyl polysiloxanes having a high
polymerization degree; silicone resins; silicone rubbers; silicone
beads; amino-modified silicones; alkyl-modified silicones; and the
like.
[0102] The aqueous conditioning component includes polyhydric
alcohols such as glycerol, 1,3-butanediol, propylene glycol,
polyethylene glycol and sorbitol.
[0103] It is desired that the content of the conditioning component
in the particles is 10 to 60% by weight, preferably 20 to 40% by
weight, from the viewpoint of improving texture upon use and
moisturizing effects.
EXAMPLES
[0104]
1 Preparation Example I-1 [Preparation of Hydrogel Particles 1] (%
by (Components) weight) (1) N-(2-Hydroxy-3-hexadecyloxypropyl)-N-
10.0 2-hydroxyethylhexadecanamide (2) Fatty acid ester of
dipentaerythritol (commercially available 2.5 from THE NISSHIN OIL
MILLS, Ltd. under the trade name of COSMOL 168AR) (3) Polyglyceryl
diisostearate (commercially available from 5.0 THE NISSHIN OIL
MILLS, Ltd. under the trade name of COSMOL 42) (4) Methyl
polysiloxane (10 mm.sup.2/s) 5.0 (5) Sodium polyoxyethylene lauryl
ether phosphate 0.05 (6) Copolymer of acrylic acid and alkyl
methacrylate 0.01 (commercially available from B. F. Goodrich under
the trade name of PEMULEN TR-1) (7) Methyl paraoxybenzoate 0.3 (8)
Agar (commercially available from Ina Shokuhin Kogyo 1.0 K.K. under
the trade name of UP-16) (9) Purified water Bal.
Preparation Method
[0105] The above components (5) to (9) for aqueous phase were mixed
and dissolved with heating at 90.degree. C. Next, the components
were cooled to 80.degree. C., and a mixture of the above components
(1) to (4) for oil phase dissolved beforehand with heating at
80.degree. C. was added thereto, and the mixture was
emulsified.
[0106] Next, the resulting emulsion was discharged into an oil
[methyl polysiloxane (20 mm.sup.2/s)] cooled to 10.degree. C. from
an orifice having an orifice diameter of 1.5 mm, to give hydrogel
particles 1. The resulting hydrogel particles 1 (average particle
diameter: 2.0 mm) were separated by filtration, washed and
thereafter stored in water.
2 Preparation Example I-2 [Preparation of Hydrogel Particles 2] (%
by (Components) weight) (1) N-(2-Hydroxy-3-hexadecyloxypropyl)-N-
10.0 2-hydroxyethylhexadecanamide (2) Fatty acid ester of
dipentaerythritol (commercially available 2.5 from THE NISSHIN OIL
MILLS, Ltd. under the trade name of COSMOL 168AR) (3) Polyglyceryl
diisostearate (commercially available from 5.0 THE NISSHIN OIL
MILLS, Ltd. under the trade name of COSMOL 42) (4) Methyl
polysiloxane (10 mm.sup.2/s) 5.0 (5) Sodium polyoxyethylene lauryl
ether phosphate 0.05 (6) Copolymer of acrylic acid and alkyl
methacrylate 0.01 (commercially available from B. F. Goodrich under
the trade name of PEMULEN TR-1) (7) Methyl paraoxybenzoate 0.3 (8)
Sodium alginate 1.0 (9) Purified water Bal.
Preparation Method
[0107] The above components (5) to (9) for aqueous phase were mixed
and dissolved with heating to 90.degree. C. Next, the components
were cooled to 80.degree. C., and a mixture of the above components
(1) to (4) for oil phase dissolved beforehand with heating at
80.degree. C. was added thereto, and the mixture was
emulsified.
[0108] Next, the resulting emulsion was added dropwise into a 1%
aqueous calcium chloride from an orifice having an orifice diameter
of 0.5 mm, to give hydrogel particles 2. The resulting hydrogel
particles 2 (average particle diameter: 2.0 mm) were separated by
filtration, washed and thereafter stored in water.
Examples I-1 to I-3 and Comparative Examples I-1 to I-6
[0109] The constituents of the cosmetic compositions listed in
Table 1 other than the hydrogel particles were homogeneously mixed.
Thereafter, to the mixture was added the hydrogel particles 1 or
the hydrogel particles 2, and the resulting mixture was mixed, to
give a cosmetic composition. The resulting cosmetic composition was
evaluated for smoothness on skin, residue of particles on skin,
sphericity and storage stability by the following methods. The
results are shown in Table 1.
[0110] (1) Moisturizing Effect
[0111] Twenty panel testers conducted sensory evaluation for
texture when each cosmetic composition was applied to skin. Its
evaluation criteria are as follows:
3 [Evaluation Criteria] 5: moist 4: slightly moist 3: moderately
moist 2: slightly not moist 1: not moist
[0112] Next, an average score of the test scores was obtained. When
the average score is not less than 4, the texture was evaluated as
".largecircle.;" when the average score is not less than 2.5 and
less than 4, the texture was evaluated as ".DELTA.;" and when the
average score is less than 2.5, the texture was evaluated as
".times.".
[0113] (2) Smoothness on Skin
[0114] Twenty panel testers conducted sensory evaluation for
texture when each cosmetic was applied to skin. Its evaluation
criteria are as follows:
4 [Evaluation Criteria] 5: easily smoothened 4: slightly smoothened
3: moderately smoothened 2: slightly less easily smoothened 1: less
easily smoothened
[0115] Next, an average score of the test scores was obtained. When
the average score is not less than 4, the texture was evaluated as
".largecircle.;" when the average score is not less than 2.5 and
less than 4, the texture was evaluated as ".DELTA.;" and when the
average score is less than 2.5, the texture was evaluated as
"x."
[0116] (3) Residue of Particles on Skin
[0117] Twenty panel testers conducted sensory evaluation for
texture when each cosmetic was applied to skin. Its evaluation
criteria are as follows:
5 [Evaluation Criteria] 5: no residue of particles 4: not so much
residue of particles 3: normal 2: slight residue of particles 1: a
lot of residue of particles
[0118] Next, an average score of the test scores was obtained. When
the average score is not less than 4, the texture was evaluated as
".largecircle.;" when the average score is not less than 2.5 and
less than 4, the texture was evaluated as ".DELTA.;" and when the
average score is less than 2.5, the texture was evaluated as "x
."
[0119] (4) Sphericity
[0120] The hydrogel particles used in each example or each
comparative example were visually observed to evaluate sphericity.
Its evaluation criteria are as follows:
6 [Evaluation Criteria] .smallcircle.: not so much variation in
shapes being found .DELTA.: slight variation in shapes being found
x: variation in shapes being found
[0121] (5) Storage Stability
[0122] The cosmetic composition obtained in each example or each
comparative example was stored in an atmosphere of 5.degree. C.,
room temperature or 50.degree. C. for one month. Thereafter, the
condition of the cosmetic was visually observed to evaluate storage
stability. Its evaluation criteria are as follows:
[0123] [Evaluation Criteria]
[0124] .largecircle.: no changes
[0125] .DELTA.: external aqueous medium being clouded and particles
being slightly deformed
[0126] x: external aqueous medium being turbid and particles being
deformed
7TABLE 1 Comp. Comp. Comp. Comp. Comp. Comp. Ex. No. and Comp. Ex.
No. Ex. I-1 Ex. I-2 Ex. I-3 Ex. I-1 Ex. I-2 Ex. I-3 Ex. I-4 Ex. I-5
Ex. I-6 Constituent of Cosmetic Composition (parts by weight)
Carboxyvinyl polymer 0.20 -- -- 0.20 -- -- 0.20 -- -- Xanthane gum
-- 0.20 -- -- 0.20 -- -- 0.20 -- Copolymer A -- -- 0.20 -- -- 0.20
-- -- 0.20 Potassium hydroxide 0.10 -- -- 0.10 -- -- 0.10 -- --
Succinic acid -- -- 0.04 -- -- 0.04 -- -- 0.04 Disodium
hydrogenphosphate -- -- 0.10 -- -- 0.10 -- -- 0.10 Methyl
paraoxybenzoate 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20
Perfume 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 Purified water
Bal. Bal. Bal. Bal. Bal. Bal. Bal. Bal. Bal. Hydrogel Particle 1
10.00 10.00 10.00 -- -- -- -- -- -- Hydrogel Particle 2 -- -- --
10.00 10.00 10.00 -- -- -- Physical Properties Moisturizing Effect
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. X X X Smoothness on Skin .largecircle.
.largecircle. .largecircle. .DELTA. .DELTA. .DELTA. .largecircle.
.largecircle. .largecircle. Residue of Particles on Skin
.largecircle. .largecircle. .largecircle. X X X -- -- -- Sphericity
.largecircle. .largecircle. .largecircle. X X X -- -- -- Storage
Stability at 5.degree. C. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. -- -- -- at room
temperature .largecircle. .largecircle. .largecircle. .DELTA.
.largecircle. .largecircle. -- -- -- at 50.degree. C. .largecircle.
.largecircle. .largecircle. X .largecircle. .largecircle. -- -- --
(Note) Copolymer A: N,N-dimethylaminoethyl methacrylate
diethylsulfate/N,N-dimet- hylacrylamide/polyethylene glycol
dimethacrylic acid terpolymer (molar ratio: 30/70/0.04)
[0127] It can be seen from the results shown in Table 1 that the
cosmetic compositions obtained in Examples I-1 to I-3 are excellent
in moisturizing effect and smoothness on skin, have no residue of
particles on skin, and are excellent in storage stability since the
hydrogel particles 1 are used.
Examples II-1 to II-10
[0128] The oil components were dissolved with heating at 80.degree.
C. in a compositional ratio shown in Table 2, to give an oil
component solution. In addition, the aqueous components were
dissolved with heating at 90.degree. C. in a compositional ratio
shown in Table 2, and cooled to 80.degree. C. Thereafter, the oil
component solution was added to the aqueous components, and the
mixture was stirred with an anchor-type stirrer, to give a liquid
mixture. The total amount of the oil components and the aqueous
components before dissolving with heating was 500 g. Further, this
liquid mixture was dispersed with an emulsifier commercially
available from TOKUSHU KIKA KOGYO Co., Ltd. under the trade name of
T.K. HOMO MIXER MARK, Model II 2.5 at 8000 r/min for one minute, to
give a dispersion. This dispersion was discharged with heating at
80.degree. C. into an oil [methyl polysiloxane: commercially
available from Shin-Etsu Chemical Co., Ltd. under the trade name of
KF-96A (20 CS)] cooled to 10.degree. C. from an orifice having an
orifice diameter of 1.2 mm at a flow rate of 10 mL/min. After the
oil dispersion was allowed to separate into solid and liquid
phases, the oil on the particle surface was removed, to give
hydrogel particles.
Examples I-11 and II-12
[0129] The total amount of 500 g of the oil components and the
aqueous components having a compositional ratio shown in Table 3
were dissolved with each other with heating in the same manner as
in Example II-1, and the resulting mixture was discharged from the
orifice in the same manner as in Example II-1, without dispersing
the liquid mixture with an emulsifier, to give hydrogel
particles.
Comparative Examples II-1 and II-2
[0130] The total amount of 500 g of the oil components and the
aqueous components having a compositional ratio shown in Table 3
were dissolved with each other with heating in the same manner as
in Example II-1, and the mixture was stirred with an anchor-type
stirrer, to give a liquid mixture. Further, this liquid mixture was
dispersed with an emulsifier commercially available from TOKUSHU
KIKA KOGYO Co., Ltd. under the trade name of T.K. HOMO MIXER MARK
II 2.5 at 8000 r/min for one minute, to give a dispersion. This
dispersion was discharged into a 1% by weight aqueous calcium
chloride solution at 20.degree. C. from an orifice having an
orifice diameter of 1.2 mm at a flow rate of 10 mL/min. After the
oil dispersion was allowed to separate into solid and liquid
phases, the 1% by weight aqueous calcium chloride solution on the
particle surface was removed, to give hydrogel particles.
Comparative Examples II-3 and II-4
[0131] The total amount of 500 g of the oil components and the
aqueous components having a compositional ratio shown in Table 3
were dissolved with each other with heating. As a result, the
dispersion was gelated, thereby making it impossible to form
particles.
Comparative Examples II-5 and II-6
[0132] The total amount of 500 g of the oil components and the
aqueous components having a compositional ratio shown in Table 3
were dissolved with each other with heating, and the resulting
mixture was discharged in the same manner as in Comparative Example
II-1. As a result, the droplets were not gelated, thereby making it
impossible to form particles.
8TABLE 2 Composition of Hydrogel Particle (% by weight) Dispersed
Phase (Oil Phase) Ex. No. Liquid Solid Ex. Ex. Ex. Ex. Ex. Ex. Ex.
Ex. Ex. Ex. Ex. Ex. Oil Fat II-1 II-2 II-3 II-4 II-5 II-6 II-7 II-8
II-9 II-10 II-11 II-12 .largecircle. Fatty acid ester of
dipentaerythritol 15.0 15.0 25.0 15.0 2.5 2.5 15.0 25.0 2.5 2.5 5.0
5.0 .largecircle. Polyglyceryl diisostearate 5.0 5.0 -- 5.0 5.0 5.0
5.0 -- 5.0 5.0 10.0 10.0 .largecircle. Methyl polysiloxane
[commercially 5.0 5.0 25.0 5.0 5.0 5.0 5.0 17.5 5.0 5.0 5.0 5.0
available from Shin-Etsu Chemical Co., Ltd. under the trade name of
KF-96A (10 CS)] .largecircle. N-(2-Hydroxy-3-hexadecyloxypropyl)-
-- -- -- 10.0 10.0 10.0 7.5 7.5 -- -- 7.5 7.5
N-2-hydroxyethylhexadecanamide (commercially available from Kao
Corporation under the trade name of Sphingolipid E) .largecircle.
Stearyl alcohol (commercially -- -- -- -- -- -- -- -- 10.0 -- -- --
available from Kao Corporation under the trade name of KALCOL 80)
.largecircle. Solid paraffin (commercially available -- -- -- -- --
-- -- -- -- 10.0 -- -- from Nikko Rika K.K. under the trade name of
CERESIN #810A) -- Sorbitan monostearate (commercially -- -- -- --
-- -- -- -- -- 1.0 1.0 available from Kao Corporation under the
trade name of RHEODOL SUPER SP-S10) Composition of Hydrogel
Particle (% by weight) Continuous Phase (Aqueous Phase) Ex. No. Ex.
Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. II-1 II-2 II-3 II-4
II-5 II-6 II-7 II-8 II-9 II-10 II-11 II-12 Deionized Water Balance
Balance Balance 63.4 76.11 75.94 63.7 48.47 Balance Balance 49.2
Balance Agar UP-16 (Gel Strength: 58.8 kPa) -- 1.0 1.5 1.0 1.0 1.0
1.0 1.0 1.0 1.5 1.0 0.5 Agar T-1 (Gel Strength: 88.2 kPa) 0.5 -- --
-- -- -- -- -- -- -- -- -- Methyl paraoxybenzoate 0.3 0.3 0.3 0.3
0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 86% Glycerol -- -- -- -- -- -- --
-- -- -- 20.0 20.0 Calcium lactate -- -- -- -- -- -- 0.5 -- -- --
-- -- Sodium polyoxyethylene lauryl ether 0.3 0.05 0.1 0.3 -- 0.05
1.0 0.1 -- 0.05 1.0 1.0 phosphate (commercially available from Kao
Corporation under the trade name of SPE104NB) Copolymer of acrylic
acid and alkyl -- 0.03 0.02 -- 0.01 0.03 -- 0.02 0.01 0.03 -- --
methacrylate [commercially available from B. F. Goodrich under the
trade name of PEMULEN (TR-1)] 20% Aqueous polyoxyethylene octyl
decyl -- -- -- -- -- -- 1.0 -- -- -- -- -- ether (commercially
available from Kao Corporation under the trade name of EMULGEN
2025G) 1N Aqueous sodium hydroxide -- 0.18 0.11 -- 0.08 0.18 --
0.11 0.08 0.18 -- -- Viscosity of Dispersion at Discharging 40 45
300 55 50 35 70 255 60 40 120 100 (mPa .multidot. s)
[0133]
9TABLE 3 Comp. Comp. Comp. Comp. Comp. Comp. Comp. Ex. No. Ex. II-1
Ex. II-2 Ex. II-3 Ex. II-4 Ex. II-5 Ex. II-6 Composition of
Hydrogel Particle (% by weight) Dispersed Phase (Oil Phase) Fatty
acid ester of dipentaerythritol 2.5 15.0 15.0 15.0 25.0 25.0
Polyglyceryl diisostearate 5.0 5.0 5.0 5.0 -- -- Methyl
polysiloxane [commercially 5.0 5.0 5.0 5.0 25.0 25.0 available from
Shin-Etsu Chemical Co., Ltd. under the trade name of KF-96A (10
CS)] N-(2-Hydroxy-3-hexadecylo- xypropyl)- 10.0 -- 5.0 7.5 -- --
N-2-hydroxyethylhexadecanamide (commercially available from Kao
Corporation under the trade name of Sphingolipid E) Sorbitan
monostearate -- -- -- -- -- -- Composition of Hydrogel Particle (%
by weight) Continuous Phase (Aqueous Phase) Deionized Water 75.94
Balance 66.2 Balance 48.58 Balance Sodium alginate 1.0 1.0 1.0 1.0
1.0 1.5 Methyl paraoxybenzoate 0.3 0.3 0.3 0.3 0.3 0.3 86% Glycerol
-- -- -- -- -- -- Calcium lactate -- -- 0.5 0.5 -- -- Sodium
polyoxyethylene lauryl ether phosphate 0.05 0.05 1.0 1.0 0.1 0.1
(commercially available from Kao Corporation under the trade name
of SPE104NB) Copolymer of acrylic acid and alkyl methacrylate 0.03
0.03 -- -- 0.02 0.02 [commercially available from B. F. Goodrich
under the trade name of PEMULEN (TR-1)] 20% Aqueous polyoxyethylene
octyl decyl ether -- -- 1.0 1.0 -- -- (commercially available from
Kao Corporation under the trade name of EMULGEN 2025G) 1 N Aqueous
sodium hydroxide 0.18 0.18 -- -- -- -- Viscosity of Dispersion at
Discharging (mPa .multidot. s) 45 50 -- Gelated -- 500
Experiment
[0134] The properties of the dispersion before the formation of
particles and the hydrogel particles obtained in each example and
each comparative example were evaluated by the following methods.
The results are shown in Table 4.
[0135] (1) Average Particle Diameter of Oil Component
[0136] With 50 g of water at 60.degree. C. was diluted 0.5 g of the
dispersion before the formation of particles. The average particle
diameter of the oil component was determined using the diluted
solution with a laser diffraction/scattering type particle size
analyzer commercially available from Horiba, LTD. under the model
number of LA-910.
[0137] (2) Average Particle Diameter of Hydrogel Particles
[0138] 100 g of the particles were subjected to wet classification
in water by using sieves with various mesh screens (opening of
standard sieves prescribed in JIS Z 8801: 1000 to 4000 .mu.m), and
excess water was removed therefrom with filter paper. Thereafter,
the weight-average particle diameter was determined by measuring
the weight of the particles existing on each screen and calculating
by using the average sieve size of the adjoining sieves.
[0139] (3) Breaking Intensity and Young's Modulus
[0140] The breaking intensity and Young's modulus were obtained
from the breaking strength of the hydrogel particles and the slope
of the load curve before break as determined by using a compression
tester commercially available from NIDEC-SHIMPO Corporation under
the trade name of FGX-0.2R; minimum determination load: 2 mN. As
the measurement element, an adaptor having a planar shape was used,
and the lowering speed of the measurement element was 10 mm/min and
the temperature during the measurement was 25.degree. C.
[0141] The breaking intensity and the Young's modulus of the
hydrogel particles were obtained by using the cross-sectional area
of the particles before measurement.
[0142] (4) Smoothness on Skin
[0143] The smoothness was determined in the same manner as
above.
[0144] (5) Residue of Particles on Skin
[0145] The residue of particles on skin was determined in the same
manner as above.
[0146] (6) Tackiness
[0147] Twenty panel testers conducted sensory evaluation for
texture when the hydrogel particles were applied to skin. Its
evaluation criteria are as follows:
10 [Evaluation Criteria] 5: not tacky 4: not much tacky 3: slightly
tacky 2: somewhat tacky 1: markedly tacky
[0148] Next, an average score of the test scores was obtained. When
the average score is not less than 4, the texture was evaluated as
".largecircle.;" when the average score is not less than 2.5 and
less than 4, the texture was evaluated as ".DELTA.;" and when the
average score is less than 2.5, the texture was evaluated as
"x."
[0149] (7) Oil Leakage
[0150] A tightly closed vessel was charged with 100 parts by weight
of the hydrogel particles and 75 parts by weight of a 20% by weight
aqueous ethanol solution, and the mixture was stored at 40.degree.
C. for 24 hours. The oil component floating in the tightly closed
vessel was visually observed, and a degree of difficulty in leakage
of the oil component was evaluated as oil leakage on the basis of
the following evaluation criteria.
11 [Evaluation Criteria] .smallcircle.: no oil float .DELTA.:
slight oil float x: obvious oil float
[0151] (8) Sphericity
[0152] A 3 g sample of the hydrogel particles was weighed, and the
particles were dispersed in water over a petri dish so that the
particles were not overlaid and photographed with a camera. A
particle having a ratio of the longest diameter to the shortest
diameter of not more than 1.7 was considered as a particle having a
high sphericity. The longest diameter and the shortest diameter
were determined for about 50 photographed particles. When not less
than 80% by weight of the particles have a high sphericity, it was
evaluated as ".largecircle.;" when less than 80% by weight and not
less than 50% of the particles have a high sphericity, it was
evaluated as ".DELTA.;" and when less than 50% by weight of the
particles have a high sphericity, it was evaluated as "x."
[0153] (9) Melting Point of Oil Component
[0154] The peak temperature of a DSC curve as determined by a
differential scanning calorimeter commercially available from
Perkin-Elmer under the trade name of DSC 7 differential scanning
calorimeter at a heating rate of 2.degree. C./min with a sample
amount of 10 to 20 mg was defined as a melting point. The melting
point for the oil component was determined for the oil component
solution prepared in the same manner as in Examples II-1 to
II-10.
12 TABLE 4 Oil Component Physical Properties of Hydrogel Particles
Average Average Particle Melting Particle Breaking Young's Residue
of Diameter Point Diameter Intensity Modulus Smoothness Particles
Oil No. [.mu.m] [.degree. C.] [.mu.m] [kPa] [kPa] on Skin on Skin
Tackiness Leakage Sphericity Ex. II-1 4 less than 3200 14 118
.largecircle. .largecircle. .DELTA. .DELTA. .largecircle. 35 Ex.
II-2 6 less than 3200 13 119 .largecircle. .largecircle.
.largecircle. .DELTA. .largecircle. 35 Ex. II-3 12 less than 3100
35 145 .largecircle. .largecircle. .largecircle. .DELTA.
.largecircle. 35 Ex. II-4 5 69 3200 15 125 .largecircle.
.largecircle. .DELTA. .largecircle. .largecircle. Ex. II-5 25 69
3100 7 43 .largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Ex. II-6 8 69 3200 12 60 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Ex. II-7 7 67 3000 28 95
.largecircle. .largecircle. .DELTA. .largecircle. .largecircle. Ex.
II-8 10 67 3100 20 80 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Ex. II-9 26 58 3100 8 45 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Ex. II-10
14 66 3200 30 95 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Ex. II-11 25 67 3100 21 110
.largecircle. .largecircle. .DELTA. .largecircle. .largecircle. Ex.
II-12 25 67 3100 5 70 .largecircle. .largecircle. .DELTA.
.largecircle. .largecircle. Comp. Ex. II-1 8 69 3100 43 155 .DELTA.
.DELTA. .largecircle. .DELTA. .DELTA. Comp. Ex. II-2 7 less than
3000 39 173 .DELTA. .DELTA. .DELTA. X .DELTA. 35 Comp. Ex. II-3 The
dispersion was gelated before the formation of particles, thereby
making it impossible to form particles. Comp. Ex. II-4 The
dispersion was gelated before the formation of particles, thereby
making it impossible to form particles. Comp. Ex. II-5 The droplets
were not gelated, thereby making it impossible to form particles.
Comp. Ex. II-6 12 The droplets were not gelated, thereby making it
impossible to form particles.
[0155] It can be seen from the comparison of Example II-2 with
Comparative Example II-2 that when a non-crosslinked hydrogel is
used in the hydrogel particles, the hydrogel is excellent in
smoothness and free from residue of particles and tackiness, so
that the particles having improved oil leakage can be obtained. In
addition, it can be seen from the comparison of Example II-7 with
Comparative Examples II-3 and II-4 that there is no compositional
limitation in Example II-7. Further, it can be seen from the
comparison of Examples II-3 and II-8 with Comparative Examples II-5
and II-6 that the particles can be formed even when the content of
the oil component is high.
Examples III-1 and III-2
[0156] The oil components having a compositional ratio shown in
Table 5 were dissolved with heating at 80.degree. C., and the
aqueous components having a compositional ratio shown in Table 5
were dissolved with heating at 90.degree. C., and cooled to
80.degree. C. The oil components were mixed with the aqueous
components, and the mixture was stirred with an anchor-type stirrer
at 80.degree. C., to give a liquid mixture. The total amount of the
oil components and the aqueous components were 500 g. Further, this
liquid mixture was dispersed with an emulsifier commercially
available from TOKUSHU KIKA KOGYO Co., Ltd. under the trade name of
T.K. HOMO MIXER MARK, Model II 2.5 at 8000 r/min for one minute, to
give a dispersion. The dispersion was discharged with heating at
80.degree. C. into an oil [methyl polysiloxane: commercially
available from Shin-Etsu Chemical Co., Ltd. under the trade name of
KF-96A (20 CS)] cooled to 10.degree. C. from an orifice having an
orifice diameter of 1.2 mm at a flow rate of 15 mL/min. During the
preparation, the droplets were formed by vibrating the dispersion
at a frequency of 60 Hz, and cooled to solidify. Thereafter, the
particles were allowed to separate into solid and liquid phases and
washed, to give hydrogel particles having high monodispersibility.
The viscosity of the dispersion at discharging was 55
mPa.multidot.s (55 cP).
Examples III-3 and III-4
[0157] The oil components having a compositional ratio shown in
Table 5 were dissolved with heating at 80.degree. C., and the
aqueous components having a compositional ratio shown in Table 5
were dissolved with heating at 90.degree. C., and cooled to
80.degree. C. The oil components were mixed with the aqueous
components, and the mixture was stirred with an anchor-type stirrer
at 80.degree. C., and talc was further added thereto, to give a
liquid mixture. The total amount of the oil component, the aqueous
component and talc was 500 g. The liquid mixture was treated in the
same manner as in Example III-1, to give hydrogel particles having
high monodispersibility. The viscosity of the dispersion at
discharging was 65 mPa.multidot.s (65 cP).
13TABLE 5 Ex. Ex. Ex. Ex. Ex. No. III-1 III-2 III-3 III-4
Composition of Hydrogel Particle (% by weight) Oil Phase Fatty acid
ester of dipentaerythritol 15.0 5.0 15.0 5.0 Polyglyceryl
diisostearate 5.0 10.0 5.0 10.0 Methyl polysiloxane [commercially
5.0 5.0 5.0 5.0 available from Shin-Etsu Chemical Co., Ltd. under
the trade name of KF-96A] N-(2-Hydroxy-3-hexadecyloxypropyl)- 10.0
10.0 10.0 10.0 N-2-hydroxyethylhexadecanamide (commercially
available from Kao Corporation under the trade name of Sphingolipid
E) Aqueous Phase Deionized Water 63.4 69.14 62.4 68.14 Agar UP-16
(commercially available 1.0 0.5 1.0 0.5 from Ina Shokuhin Kogyo
K.K.) Methyl paraoxybenzoate 0.3 0.3 0.3 0.3 Sodium polyoxyethylene
lauryl ether 0.3 0.05 0.3 0.05 phosphate (commercially available
from Kao Corporation under the trade name of SPE-104NB) Copolymer
of acrylic acid and alkyl -- 0.01 -- 0.01 methacrylate
[commercially available from B. F. Goodrich under the trade name of
PEMULEN (TR-1)] Talc (powder) [commercially available -- -- 1.0 1.0
from K.K. Yamaguchi Ummo Kogyosho]
Evaluation
[0158] Next, the following evaluation was made by using the
hydrogel particles obtained in each of Examples and Comparative
Examples. The results are shown in Table 6.
[0159] (1) Average Particle Diameter of Hydrogel Particles
[0160] The average particle diameter was determined in the same
manner as above.
[0161] (2) Sphericity
[0162] The sphericity was determined in the same manner as
above.
[0163] (3) Monodispersibility
[0164] The monodispersibility was evaluated by obtaining a CV value
from a standard deviation and arithmetic means of the determined
particle diameter. The longest diameter of the particle obtained
when determining the sphericity was defined as the particle
diameter of the particle. Those having a CV value of not more than
5 are evaluated as excellent monodispersibility. The longest
particle diameter and the shortest particle diameter are also shown
in Table 6. The smaller the difference therebetween is, the more
excellent the monodispersibility is.
14 TABLE 6 Physical Properties of Hydrogel Particles
Monodispersibiity Average Shortest Longest Particle Particle
Particle Ex. Diameter Diameter Diameter CV No. [.mu.m] Sphericity
[mm] [mm] Value Evaluation III-1 2.04 .largecircle. 1.95 2.10 1.30
Excellent III-2 2.01 .largecircle. 1.93 2.10 1.28 Excellent III-3
1.98 .largecircle. 1.91 2.08 1.25 Excellent III-4 2.00
.largecircle. 1.90 2.07 1.29 Excellent
[0165] It can be seen from the results shown in Table 6 that the
hydrogel particles obtained in each example have high sphericity
and are excellent in monodispersibility.
[0166] The skin cosmetic composition of the present invention shows
excellent appearance because particles are dispersed and suspended
in a liquid medium. Also, the skin cosmetic composition is
excellent in storage stability and smoothness, and no residue of
particles remains on skin when the skin cosmetic composition is
applied to the skin. Therefore, the skin cosmetic composition
favorably exhibits the effects based on the ingredients. In the
skin cosmetic composition of the present invention, the particles
are easily broken when applied to skin, so that the ingredients are
uniformly smoothened over the skin, thereby realizing a refreshing
feel without being tacky.
[0167] When the hydrogel particles of the present invention are
applied to skin and rubbed with fingers, the particles are smoothly
broken, so that there are exhibited such effects that the hydrogel
particles are easily smoothened, have no residue of particles and
excellent breaking ability. In addition, the hydrogel particles of
the present invention exhibit some effects such that there is no
leakage of the oil component from the particles, without giving
tackiness during application.
* * * * *