JP2022091201A - Foam rubber and cosmetic applicator - Google Patents

Abstract

To provide a foam rubber that ensures soft, good skin contact, and makes it possible to obtain a smooth feel.SOLUTION: A foam rubber is a porous rubber containing a rubber-based polymer, fat including a fatty acid ingredient, and a silicone oil. The foam rubber contains not less than 1 pt.mass and less than 20 pts.mass of the silicone oil relative to 100 pts.mass of the rubber-based polymer.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to foam rubber and cosmetic application tools.

In the application tools such as puffs used when applying foundation to the skin, there is a tendency that puffs and the like that are soft on the skin and have a smooth feel are preferred.
As the foam rubber used for puffs and the like, for example, the following foam rubbers are known (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2005-225984

In Patent Document 1, the latex, the softener, and the bubble stabilizer are mixed at a maximum shear rate set in the range of 10 to 10,000 min ^-1 , so that phase separation is unlikely to occur even if the softener is mixed. Foam rubber is disclosed.
However, although this foam rubber gives a soft feel, it does not give a slippery feel to the skin.
The present disclosure has been made in view of the above circumstances, and an object of the present invention is to provide a foam rubber that is soft, feels good on the skin, and has a smooth feel. It is also an object of the present disclosure to provide a cosmetic application tool that is soft, feels good on the skin, and has a smooth feel.
The present disclosure can be realized in the following forms.

[1] A foam rubber containing a rubber-based polymer, an oil / fat containing a fatty acid component, and a silicone oil.
A foam rubber containing 100 parts by mass of the silicone oil in an amount of more than 1 part by mass and less than 20 parts by mass with respect to 100 parts by mass of the rubber-based polymer.

The foam rubber of the present disclosure is soft, feels good on the skin, and has a smooth feel.

It is a perspective view which shows an example of the application tool of cosmetics.

Here are desirable examples of the present disclosure.
[2] The foam rubber according to [1], wherein the silicone oil contains at least a polyether-modified silicone oil.

[3] The foam rubber according to [1] or [2], wherein the dynamic friction coefficient (μd) is 1.5 or less.

[4] The foam rubber according to any one of [1] to [3], wherein the 50% compression load is 5 gf / cm ² or more and 15 gf / cm ² or less.

[5] The foam rubber according to any one of [1] to [4], wherein the surface roughness Rz is 5 μm or more and 40 μm or less.

[6] A cosmetic application tool comprising the foam rubber according to any one of [1] to [5].

Hereinafter, the present disclosure will be described in detail. In the present specification, the description using "-" for the numerical range includes the lower limit value and the upper limit value unless otherwise specified. For example, in the description of "10 to 20", both the lower limit value "10" and the upper limit value "20" are included. That is, "10 to 20" has the same meaning as "10 or more and 20 or less".

1. 1. Foam rubber Foam rubber is a porous rubber containing a rubber-based polymer, fats and oils containing a fatty acid component, and silicone oil. The foam rubber contains more than 1 part by mass and less than 20 parts by mass of silicone oil with respect to 100 parts by mass of the rubber-based polymer.
By combining oil and silicone oil, slipperiness is maintained for a long time even if the foam rubber is washed with water. This mechanism is not clear, but it is presumed as follows. However, this disclosure is not limited to this estimation mechanism. Only oils and fats will flow out of the foam rubber when washed with water. Silicone oil is insoluble in water, and it is presumed that by combining fats and oils and silicone oil, components that contribute to slipperiness remain even after washing with water, and slipperiness is maintained for a long period of time.
In addition, the following effects can be expected when applying foundation to the skin using this foam rubber. Foundations often contain silicone oil. Since this foam rubber also contains silicone oil, the affinity between the foam rubber and the foundation is high, and the foundation becomes more familiar with this foam rubber. Therefore, when making up with a foundation using this foam rubber, the makeup effect of the foundation can be enhanced.
The foam rubber may also be referred to as latex foam.

(1) Rubber-based polymer The rubber-based polymer is not particularly limited. Examples of the rubber-based polymer include acrylonitrile-butadiene rubber (NBR), isoprene rubber (IR), styrene-butadiene rubber (SBR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), and butadiene rubber (BR). One or more selected from the group consisting of butyl rubber (isobutyene / isoprene rubber (IIR)) and natural rubber (NR) can be used. Acrylonitrile-butadiene rubber (NBR), which is excellent in weather resistance, oil resistance, abrasion resistance, hygiene (preventing the generation of microorganisms) and the like, is preferably used.

(2) Fats and oils containing fatty acid components (fatty acid softeners)
The fats and oils containing a fatty acid component are not particularly limited.
The fatty acid components include cabric acid, cabric acid, lauric acid, myristic acid, palmitic acid, palmitreic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid, eicosenoic acid, behenic acid (behenic acid), and erucic acid. One or more selected from the group consisting of (erucic acid) and lignoseric acid is preferable.
As oils and fats containing fatty acid components, from the viewpoint of further enhancing safety to the human body, castor oil, red flower oil, rice white squeezed oil, peanut oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, palm oil, olive oil, Examples thereof include vegetable oils such as corn oil and animal oils, and vegetable oils containing a large amount of oleic acid, for example, fallen raw oil, olive oil and rapeseed oil are preferable.
The fats and oils containing a fatty acid component are biogenic fatty acid ester oils such as fatty acid ester oils obtained by dehydrating or hydrogenating the fats and oils exemplified above, for example, fats and oils such as dehydrated sebacic acid, dibutyl phthalate, dioctyl phthalate, and the like. Di- (2-ethylhexyl) phthalate, di-tetrahydrophthalate (2-ethylhexyl), di-n-octyl adipate, di-di (2-ethylhexyl) adipate, diisodecyl adipate, tricresyl phosphate, alkylallyl phosphate, Fats and oils such as butylphthalylbutylglycolate, di-n-butyl sebacate, di (2-ethylhexyl) sebacate, triethylene glycol di (2-ethyl hexoate), acetyltri-n-butyl citrate, etc. (Plastic agent), di-n-butyl sebacate, di (2-ethylhexyl) sebacate, triethylene glycol di (2-ethyl hexoate), acetyl tri-n-butyl acid, etc. There may be.
The fats and oils containing the fatty acid component may be used alone or in combination of two or more.

The content of fats and oils is preferably 0.5 parts by mass or more, more preferably 0.7 parts by mass or more, with respect to 100 parts by mass of the rubber-based polymer, from the viewpoint of smoothing the feel of the foam rubber on the skin. More than 0.0 parts by mass is more preferable. On the other hand, from the viewpoint of suppressing oil and fat from bleeding from the foam rubber and contaminating the surroundings, 30.0 parts by mass or less is preferable, and 20.0 parts by mass or less is more preferable with respect to 100 parts by mass of the rubber-based polymer. It is more preferably 10.0 parts by mass or less. From these viewpoints, the content of fats and oils is preferably 0.5 parts by mass or more and 30.0 parts by mass or less, and more preferably 0.7 parts by mass or more and 20.0 parts by mass or less with respect to 100 parts by mass of the rubber-based polymer. , 1.0 part by mass or more and 10.0 parts by mass or less is more preferable.

(3) Silicone oil Silicone oil is not particularly limited. As the silicone oil, for example, straight silicone oil, modified silicone oil and the like can be used. As the straight silicone oil, dimethyl silicone oil, methyl phenyl silicone oil, methyl hydrogen silicone oil and the like can be used. As the modified silicone oil, a polyether-modified silicone oil, a methylstyryl-modified silicone oil, an alkyl-modified silicone oil, a higher fatty acid ester-modified silicone oil, a higher fatty acid-modified silicone oil, or the like can be used.
One type of silicone oil may be used alone, or two or more types may be used in combination.
Silicone oil is one selected from the group consisting of dimethyl silicone oil and polyether-modified silicone oil from the viewpoint of having good emulsifying property, being able to be finely dispersed in the latex composition, and increasing the slipperiness of the foam rubber. It is preferable to include at least the above.
In particular, polyether-modified silicone oil is preferable from the following viewpoints. Since the polyether-modified silicone oil has hygroscopicity, its use increases the slipperiness of the foam rubber. Polyether-modified silicone oil is water-insoluble and durable. The polyether-modified silicone oil bleeds on the surface of the foam rubber to impart slipperiness.
When the oil and fat and the modified silicone oil are mixed with the latex of the rubber-based polymer, they are compatible with each other to make the emulsified particles finer, so that a smooth foam can be formed with less cell roughness.
The viscosity of the silicone oil is not particularly limited. The kinematic viscosity of the silicone oil is more preferably 20 mm ² / s or more and 300 mm ² / s or less, more preferably 40 mm, from the viewpoint of optimizing the time until the silicone oil bleeds on the surface of the foam rubber and bleeds so as to impart slipperiness. It is more preferably ² / s or more and 150 mm ² / s or less, and further preferably 50 mm ² / s or more and 100 mm ² / s or less.

The content of the silicone oil is more than 1 part by mass and 20 parts by mass with respect to 100 parts by mass of the rubber-based polymer from the viewpoint of improving the appearance of the surface of the foam rubber and improving the tactile sensation when it touches the skin and maintaining them. It is less than parts by mass, preferably 3 parts by mass or more and 15 parts by mass or less, and more preferably 5 parts by mass or more and 10 parts by mass or less.

(4) Other softeners Both fats and oils containing fatty acid components and silicone oils function as softeners. In addition to these compounds, other softeners may be added to the composition of the rubber latex during the production of the foam rubber. The other softener is a component that imparts appropriate flexibility to the foam rubber. Other softeners are not particularly limited. Examples of other softeners include hydrocarbon-based process oils such as paraffin-based process oils, naphthen-based process oils, and aromatic process oils, spindle oils, and petrolatum. The paraffin-based process oil is a process oil containing 50% by mass or more of carbon in the paraffin-based hydrocarbon with respect to 100% by mass of the total carbon content. The naphthenic process oil is a process oil containing 30% by mass to 45% by mass of carbon in the naphthenic hydrocarbon with respect to 100% by mass of the total carbon content. The aromatic process oil is a process oil containing 35% by weight or more of carbon in the aromatic hydrocarbon with respect to 100% by mass of the total carbon content.
Paraffin-based process oils are preferable from the viewpoint of suppressing yellowing of foam rubber and further enhancing safety to the human body, and paraffin-based hydrocarbons having a high content with respect to the total carbon content, for example, 100 mass of total carbon content. A paraffin-based process oil containing 70% by mass or more of paraffin-based hydrocarbon and 30% by mass or less of naphthen-based hydrocarbon as a residue is more preferable, and liquid paraffin is further preferable.

The content of the other softener is preferably 0.5 parts by mass or more, and 0.7 parts by mass or more with respect to 100 parts by mass of the rubber-based polymer, from the viewpoint of giving the foam rubber appropriate flexibility and excellent elongation. Is more preferable, and 1.0 part by mass or more is further preferable. On the other hand, from the viewpoint of preventing other softeners from bleeding from the foam rubber and contaminating the surroundings, 30.0 parts by mass or less is preferable and 20.0 parts by mass or less is preferable with respect to 100 parts by mass of the rubber-based polymer. More preferably, 10.0 parts by mass or less is further preferable. From these viewpoints, the content of fats and oils is preferably 0.5 parts by mass or more and 30.0 parts by mass or less, and more preferably 0.7 parts by mass or more and 20.0 parts by mass or less with respect to 100 parts by mass of the rubber-based polymer. , 1.0 part by mass or more and 10.0 parts by mass or less is more preferable.

(5) Foaming agent A foaming agent may be added to the composition of the rubber latex at the time of manufacturing the foam rubber. The foaming agent is not particularly limited. Foaming agents include fatty acid salts such as potassium oleate, sodium laurate, sodium myristate, sodium stearate, ammonium stearate, sodium oleate, potassium castor oil soap, potassium palm oil soap; sodium lauroyl sarcosin, myristol sarcosin. Sarcosine salts such as sodium, oleyl sarcosin sodium, cocoyl sarcosin sodium; sulfates such as palm oil alcohol sodium sulfate, polyoxyethylene lauryl ether sodium sulfate; sodium dioctyl sulfosuccinate, sodium lauryl sulfosuccinate, sodium dodecylbenzene sulfonate, α -Sulfonates such as sodium olefin sulfonate; cationic surfactants such as stearyldimethylammonium chloride and benzalconium chloride are exemplified. The content of the foaming agent in the latex composition is preferably 1.0 part by mass or more and 10.0 parts by mass or less, and 2.0 parts by mass or more and 8.0 parts by mass or less with respect to 100 parts by mass of the rubber-based polymer. Is more preferable.

(6) Foaming Stabilizer A foaming stabilizer may be added to the mixture of rubber latex in the production of foam rubber. The foaming stabilizer is not particularly limited. Examples of the foaming stabilizer include an alkyl chloride / formaldehyde / ammonia reaction product, an alkyl quaternary ammonium chloride, an alkylaryl sulfonate, and a higher fatty acid ammonium.
The alkyl chloride-formaldehyde-ammonia reaction product is obtained, for example, by reacting an alkyl chloride with formaldehyde and ammonia. The number of carbon atoms of the alkyl chloride is not particularly limited. The number of carbon atoms of the alkyl chloride is preferably an integer of 1 or more and 4 or less. As the alkyl chloride / formaldehyde / ammonia reaction product, for example, ethyl chloride / formaldehyde / ammonia reaction product is preferably exemplified.
The number of carbon atoms of the alkyl of the alkyl quaternary ammonium chloride is not particularly limited. The number of carbon atoms of the alkyl quaternary ammonium chloride is preferably an integer of 1 or more and 4 or less.
The number of carbon atoms of the alkyl of the alkylaryl sulfonate is not particularly limited. The alkyl carbon number of the alkylaryl sulfonate is preferably an integer of 1 or more and 4 or less.
The carbon number of the higher fatty acid of the higher fatty acid ammonium is not particularly limited. The carbon number of the higher fatty acid is preferably an integer of 1 or more and 20 or less.
The foaming stabilizer may be used alone or in combination of two or more.
As the foaming stabilizer, an alkyl chloride / formaldehyde / ammonia reaction product is preferable because a softening agent (one or more of fats and oils containing a fatty acid component, silicone oil, and other softening agents) is uniformly dispersed. Alkyl chloride-formaldehyde-ammonia reaction products having 1 or more and 4 or less carbon atoms are more preferable, and ethyl chloride-formaldehyde-ammonia reaction products are particularly preferable.
The amount of the foaming stabilizer to be blended is not particularly limited. The amount of the foaming stabilizer to be blended is preferably 2.0 parts by mass or more, preferably 3.0 parts by mass or more, based on 100 parts by mass of the rubber-based polymer in the rubber latex mixture from the viewpoint of uniformly dispersing the softening agent. Is more preferable, and 3.5 parts by mass or more is further preferable. On the other hand, from the viewpoint of suppressing the cost of the foaming stabilizer and shortening the gelation time, 8.0 parts by mass or less is preferable, and 7.0 parts by mass or less is more preferable with respect to 100 parts by mass of the rubber-based polymer. More preferably, it is 5.0 parts by mass or less. From these viewpoints, the blending amount of the foaming stabilizer is preferably 2.0 parts by mass or more and 8.0 parts by mass or less, and 3.0 parts by mass or more and 7.0 parts by mass or less with respect to 100 parts by mass of the rubber-based polymer. Is more preferable, and 3.5 parts by mass or more and 5.0 parts by mass or less are further preferable.

(7) Gelling agent A gelling agent may be added to the latex composition at the time of producing foam rubber. The gelling agent has a role of aggregating and gelling the rubber-based polymer particles dispersed in the latex. At this time, the latex composition gels while maintaining the dispersed state of the foam generated by the gas mixed in the rubber latex mixture. Therefore, the gelled latex composition is heated and vulcanized. A foam rubber having a substantially uniform cell structure can be obtained.
The action of the gelling agent will be described. The latex composition has a surface-active function on the alkaline side due to the influence of the dispersant and the foaming agent. When a gelling agent is added to such a latex composition, acid is generated due to the decomposition of the gelling agent, and the pH drops sharply. When the latex composition shifts to the acidic side due to this decrease in pH, the surface active function of the dispersant is inactivated, so that the dispersed rubber-based polymer particles are aggregated and gelled.
As the gelling agent, for example, a liquid material in which hexafluorosilicate is in an aqueous solution state is preferably used. Examples of the hexafluorosilicate include sodium silicate (SSF), potassium silicate, and calcium silicate.
The gelling agent may be used alone or in combination of two or more.
As the gelling agent, sodium silicate is particularly preferably used from the viewpoint of facilitating reaction control such as gelation start time.
The blending amount of the gelling agent is not particularly limited. The blending amount of the gelling agent is preferably 0.1 part by mass or more and 10.0 parts by mass or less as the solid content with respect to 100 parts by mass of the solid content (rubber-based polymer) in the rubber latex.

(8) Dispersant A dispersant may be blended in the latex composition at the time of manufacturing the foam rubber. The dispersant has a role of improving the dispersibility of the rubber-based polymer particles and various additives in the latex composition. By adding a dispersant, the latex composition can be made uniform. Further, the dispersant can uniformly disperse the gas to be mixed in the latex composition.
The dispersant is not particularly limited. Examples of the dispersant include anionic surfactants and nonionic surfactants.
Examples of the anionic surfactant include fatty acid alkali metal salts, alkyl sulfonic acid alkali metal salts, and alkylbenzene sulfonic acid alkali metal salts.
Examples of the nonionic surfactant include sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene hydrogenated castor oil, polyoxyethylene alkyl ether and the like.
The dispersant may be used alone or in combination of two or more.
The content of the dispersant in the latex composition is preferably 0.5 parts by mass or more and 10.0 parts by mass or less, and 1.0 part by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the rubber-based polymer. More preferred.

(9) Anti-aging agent An anti-aging agent may be added to the latex composition at the time of manufacturing the foam rubber. The anti-aging agent is not particularly limited. Examples of the antiaging agent include diphenylamine-based compounds, condensates of aromatic amines and aliphatic ketones, imidazole-based compounds, mono-phenol-based compounds, bis-phenol-based compounds, trisphenol-based compounds, polyphenol-based compounds and the like. Be done.
Examples of the diphenylamine compound include N-phenyl-N'-(p-toluenesulfonyl) -p-phenylenediamine and the like.
Examples of the imidazole compound include 2-mercaptobenzimidazole and a zinc salt thereof.
Examples of the mono-phenolic compound include 2,6-di-t-butyl-4-methylphenol and the like.
The anti-aging agent may be used alone or in combination of two or more.
The amount of the anti-aging agent to be blended in the latex composition is preferably 1.0 part by mass or more and 10.0 parts by mass or less, and 2.0 parts by mass or more and 6 by mass with respect to 100 parts by mass of the rubber-based polymer from the viewpoint of preventing aging. More preferably, it is 0.0 parts by mass or less.

(10) Vulcanizing agent A vulcanizing agent may be blended in the latex composition at the time of manufacturing the foam rubber. The vulcanizing agent has a function of vulcanizing (crosslinking) the rubber in order to secure the elastic modulus of the foam rubber. The vulcanizing agent is not particularly limited. Examples of the vulcanizing agent include sulfur, sulfur compounds, organic peroxides, phenol compounds and the like. As the sulfur, for example, colloidal sulfur, fine powdered sulfur and the like can be used. As the sulfur compound, for example, sulfur dichloride, dipentamethylene thiuram tetrasulfide and the like can be used.
The vulcanizing agent may be used alone or in combination of two or more.
The blending amount of the vulcanizing agent varies depending on the type of the rubber-based polymer, the vulcanization mechanism, and the cross-linking agent, but in the composition of the rubber latex, 0.02 parts by mass or more and 20 parts by mass with respect to 100 parts by mass of the rubber-based polymer. It is preferably 0.0 parts by mass or less, and more preferably 0.1 parts by mass or more and 10.0 parts by mass or less.

(11) Vulcanization Auxiliary Agent A vulcanization aid may be added to the latex composition at the time of producing foam rubber. The vulcanization aid promotes the action of the vulcanizing agent. The vulcanization aid is not particularly limited. As the vulcanization aid, for example, an inorganic compound such as zinc oxide or magnesium oxide, an organic substance such as stearic acid or amines, or the like can be used. The vulcanization aid may be used alone or in combination of two or more.
The blending amount of the vulcanization aid is preferably 0.5 parts by mass or more and 10.0 parts by mass or less, and 1.0 part by mass or more and 5.0 by mass or less, based on 100 parts by mass of the rubber-based polymer in the rubber latex composition. More preferably, it is by mass or less.

(12) Vulcanization Accelerator A vulcanization accelerator may be added to the latex composition at the time of producing foam rubber. The vulcanization accelerator is used for the purpose of shortening the vulcanization time and the like.
The vulcanization accelerator is not particularly limited. Examples of the vulcanization accelerator include zinc dithiocarbamate, thiuram, sulfenamides, benzothiazoles and the like.
The vulcanization accelerator may be used alone or in combination of two or more.
Examples of zinc dithiocarbamate include zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc di-n-butyldithiocarbamate, zinc dibenzyldithiocarbamate, zinc ethylphenyldithiocarbamate, zinc N-pentamethylenedithiocarbamate and the like. Be done.
Examples of thiurams include tetramethylthium monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, N, N'-dimethyl-N, N'-diphenyluram disulfide, dipentamethylene thiuram tetrasulfide and the like. Can be mentioned.
Examples of sulfenamides include N, N-diisopropyl-2-benzothiallyl sulfenamide, Nt-butyl-2-benzothialyl sulfenamide, and N-cyclohexyl-2-benzothiazyl sulfenamide. Examples thereof include amide, N, N-dicyclohexyl-2-zinzothiazylsulfenamide, N-oxydiethylene-2-benzothiadylsulfenamide and the like.
Examples of benzothiazoles include 2-mercaptobenzothiazole and its salts (sodium salt, zinc salt, cyclohexylamine salt, dicyclohexylamine salt, etc.), 2- (4'-morpholinodithio) benzothiazole, 4-morphornyloo. Examples thereof include 2-benzothiazyl disulfide and 2- (N, N-diethylthiocarbamoylthio) benzothiazole.
The blending amount of the vulcanization accelerator is preferably 0.02 parts by mass or more and 20 parts by mass or less, and more preferably 0.1 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the rubber-based polymer in the latex composition. ..

(13) Other Additives In the foam rubber of the present disclosure, as an additive to be added to the rubber latex, an antibacterial agent, a filler, a colorant, a fragrance, a thickener, and a fungicide are used as long as the effects of the present disclosure are not impaired. A mold agent, a cooling agent, or the like may be used.

(14) Apparent density The apparent density of the foam rubber is not particularly limited. The apparent density of the foam rubber is preferably 0.05 g / cm ³ or more and 0.30 g / cm ³ or less, and 0.10 g / cm ³ or more and 0.20 g / cm ³ or less, from the viewpoint of softening the skin. It is preferable, 0.13 g / cm ³ or more and 0.18 g / cm ³ or less is more preferable.
The apparent density of the foam rubber is measured by a measuring method described later.

(15) 50% compression load The 50% compression load of the foam rubber is not particularly limited. The 50% compression load of the foam rubber is preferably 5 gf / cm ² or more and 15 gf / cm ² or less, more preferably 7 gf / cm ² or more and 13 gf / cm ² or less, and 8 gf / cm from the viewpoint of skin contact feeling and foundation scraping property. More preferably, it is cm ² or more and 12 gf / cm ² or less.
The 50% compressive load of the foam rubber is measured by the measuring method described later.

(16) Dynamic friction coefficient (μd)
The coefficient of dynamic friction (μd) of the foam rubber is not particularly limited. The dynamic friction coefficient (μd) of the foam rubber is preferably 1.3 or less, and the initial dynamic friction coefficient and the dynamic friction coefficient at the 10th washing with water, which are measured by the measurement method described later, are both preferably 1.5 or less. Is more preferable, and 1.0 or less is further preferable. When the coefficient of dynamic friction is within this range, a smooth feel is obtained on the skin. The lower limit of the dynamic friction coefficient (μd) of the foam rubber is usually 0.1 or more.

(17) Surface roughness Rz
The surface roughness Rz of the foam rubber is not particularly limited. The surface roughness Rz is preferably 5 μm or more and 40 μm or less, more preferably 10 μm or more and 35 μm or less, and further preferably 13 μm or more and 30 μm or less, from the viewpoint of suppressing the feeling of roughness (stickiness) on the skin.
The surface roughness Rz of the foam rubber is measured by a measuring method described later.

2. 2. Method for manufacturing foam rubber The method for manufacturing foam rubber is not particularly limited. For example, the following manufacturing method is preferably adopted.
First, a vulcanized paste is prepared. Specifically, sulfur as a vulcanizing agent and a vulcanization accelerator, zinc oxide, an antiaging agent, and a dispersant are added to ion-exchanged water to prepare a vulcanization paste.
Next, foam rubber (latex foam) is produced. Specifically, a vulcanized paste, a foaming agent, an oil and fat, a surfactant, and a silicone oil are blended with a latex (emulsion) to obtain a latex composition. A foam rubber can be produced by adding a gelling agent and air to this composition, foaming and gelling with a mixer, and then heating.
The gas that foams the latex composition to form a foam is not particularly limited. As the gas, for example, air, nitrogen or the like can be used. A mixer can be used as a method of foaming. As the mixer, for example, a hovered mixer, a pin mixer, an oaks mixer and the like can be preferably used. The vulcanization method is not particularly limited. Examples of the vulcanization method include steam vulcanization, hot air vulcanization, high frequency vulcanization, electron beam vulcanization and the like.

3. 3. Cosmetic application tool The foam rubber of the present disclosure can be suitably used for the cosmetic application tool 1. FIG. 1 schematically shows an example of a cosmetic application tool 1.
The foam rubber of the present disclosure has a good feel on the skin and has excellent commercial value for applications in which it comes into direct contact with the skin. When the foam rubber of the present disclosure is used for the coating tool 1, it is possible to provide a coating tool having a good feel and a high cosmetic effect. The shape and structure of the cosmetic application tool 1 are not particularly limited as long as it is used for the purpose of applying the cosmetic. The foam rubber of the present disclosure may be used for a part of the coating tool 1 or may be used for the whole. Puffs, brushes, and the like for liquid kits, cream powder foundations, and the like are preferably exemplified as the cosmetic application tool 1.

Hereinafter, a more specific description will be given with reference to Examples.

1. 1. Preparation of Foam Rubber Various foam rubbers were prepared at the blending ratios shown in Table 1-2. In Table 1-2, the details of the main raw materials are shown below. In Table 1-2, the mass part of the latex represents the mass part of the rubber-based polymer (solid content) contained in the latex.
(1) Raw material / synthetic latex rubber (denoted as "latex" in the table):
Product name Nipol LX531B (acrylonitrile-butadiene rubber latex) Made by Nippon Zeon Corporation ・ Fats and oils containing fatty acid components 1 (denoted as “fatty acid softener 1” in the table):
Olive oil (manufactured by Kanto Chemical Co., Inc.)
Fats and oils 2 containing fatty acid components (denoted as "fatty acid softener 2" in the table):
Rice white squeezed oil (manufactured by Kanto Chemical Co., Inc.)
Fats and oils containing fatty acid components 3 (denoted as "fatty acid softener 3" in the table):
Peanut oil (manufactured by Kanto Chemical Co., Inc.)
・ Dimethyl silicone oil 1:
Product name KF96-50 Made by Shin-Etsu Chemical Co., Ltd.
・ Dimethyl silicone oil 2:
Product name KF96-100 Made by Shin-Etsu Chemical Co., Ltd. ・ Polyether-modified silicone oil:
Product name KF642 Made by Shin-Etsu Chemical Co., Ltd.
・ Foam stabilizer:
Ethyl chloride / formaldehyde / ammonia reaction product Product name Trimenbase Uniroyal Chemical Company
-Vulcanizer-containing emulsion:
Emulsion made by emulsifying 40% by mass of sulfur and 10% by mass of dispersant casein with 50% by mass of water, manufactured by Karuizawa Seisakusho Co., Ltd.
・ Vulcanizing agent:
Sulfur: manufactured by Hosoi Chemical Industry Co., Ltd. ・ Vulcanization accelerator:
G-n-Butyldithiocarbamate Zinc Brand name Noxeller MZ Ouchi Shinko Kagaku Kogyo Co., Ltd.
・ Foaming agent:
Potassium oleate soap Product name FR14, Kao Corporation
・ Anti-aging agent:
Phenolic Antioxidant Product Name ADEKA STAB AO-60 Made by ADEKA CORPORATION
・ Vulcanization aid:
Zinc Oxide Product Name Zinc Oxide Type 2 Sakai Chemical Industry Co., Ltd.
・ Gelling agent:
Product name Sodium Kay Fluoride manufactured by Mitsui Chemicals, Inc.
・ Surfactant:
Polyoxyethylene alkyl ether Product name Emargen 1135S-70
・ Dispersant:
Naphthalene Sulfonic Acid Formalin Condensate Soda Product Name Demor N, manufactured by Kao Corporation

(2) Preparation of foam rubber Each foam rubber was specifically produced as follows.
(2.1) Example 1-8
(Preparation of vulcanized paste)
Vulcanization agent (10 parts by mass), vulcanization accelerator (Noxeller MZ (6 parts by mass)), zinc oxide 2 types (18 parts by weight), antiaging agent (13 parts by mass), dispersant (3) By weight), was added to ion-exchanged water (50 parts by weight) and dispersed in a ball mill for 48 hours to prepare a vulcanized paste.

(Making foam rubber)
NBR latex rubber is used as the synthetic latex rubber that is the main raw material for foam rubber, and 7.6 parts by mass of vulture-based paste is applied to 100 parts by mass of the rubber-based polymer contained in the latex mixture according to the formulation shown in Table 1. , 0.2 parts by mass of foaming agent, oil and fat containing fatty acid component (fatty acid-based softener), 0.1 parts by mass of surfactant, and silicone oil were mixed to obtain a latex composition (latex foam raw material). .. After adding 10 parts by mass of a gelling agent and air to this raw material and foaming, foaming and gelling with an oak mixer, and then heating at 100 ° C. for 30 minutes, a foam rubber was prepared. ..

(2.2) Comparative Example 1
A foam rubber was produced in the same manner as in Examples except that silicone oil was not used.

(2.3) Comparative Example 2
A foam rubber was produced in the same manner as in the examples except that no fat or oil (fatty acid-based softener) containing a fatty acid component was used.

(2.4) Comparative Example 3
A foam rubber was produced in the same manner as in the examples except that the amount of silicone oil was too large.

(2.5) Comparative Example 4
A foam rubber was produced in the same manner as in the examples except that the amount of silicone oil was too small.

(2.6) Comparative Example 5
A foam rubber was produced in the same manner as in Examples except that no silicone oil was used and no fat or oil (fatty acid-based softener) containing a fatty acid component was used.

2. 2. Evaluation method (1) Evaluation method of surface appearance of foam rubber The cell state (cell fineness and uniformity) of the foam rubber was evaluated.
The evaluation of the surface appearance (rough cell) is as follows.
A: The cells are very uniform.
B: The cells are uniform.
C: The fineness of the cell is slightly inferior, and the uniformity of the cell is slightly inferior.
D: The cells are coarse, the cells are continuous, and they are hangnail.

(2) Apparent density The apparent density was measured according to JIS-K 6767.

(3) 50% compression load The compression load of the foam rubber was measured according to JIS-K 6767.
The skin layer of the foam rubber was removed to prepare a test piece having a thickness of 10 mm. Then, using a compression tester, 50% compression was performed at a compression rate of 10 mm / min, and then the compression load after 10 seconds was measured.

(4) Dynamic Friction Coefficient A sample piece was prepared by removing the skin layer of the foam rubber and punching it into a rectangular flat plate (10 mm × 100 mm × 5 mm) having a thickness of 10 mm. The test piece was placed on a support table (test table) of a friction coefficient measuring machine (HEIDON-14D manufactured by Shinto Kagaku). Then, a load of 0.98N is applied, and the weight member constituting the R50 spherical glass is placed on the sample piece (the R50 spherical side is placed), and the weight member is placed in the horizontal direction (longitudinal direction of the sample piece). On the other hand, the coefficient of dynamic friction (μd) was measured by sliding at a speed of 1000 mm / min (sliding while in contact with the sample piece). This was used as the initial coefficient of dynamic friction. Then, the sample piece was submerged in water (tap water), taken out after 5 minutes, the water was wiped off, and then left at room temperature for 3 hours. After repeating this operation 10 times, the coefficient of dynamic friction (μd) was measured in the same manner as in the initial stage. This dynamic friction coefficient (μd) was used as the dynamic friction coefficient for the 10th washing with water.

(5) Evaluation of Ten-Point Average Surface Roughness Rz A sample of foam rubber was punched into a rectangular flat plate (20 mm × 100 mm × 5 mm) to prepare a sample piece. After wiping off the dirt on the surface of the sample piece with alcohol, the sample piece is subjected to a ten-point averaging method (method based on JIS-B0601) using a surface roughness meter (Surfcoder SE30D manufactured by Kosaka Research Institute). The surface roughness (10-point average roughness: Rz) was measured. As the stylus of the surface roughness meter, a stylus tip radius of 250 μm was used in order to improve the reproducibility of measurement.

(6) Skin tactile sensory evaluation The skin tactile sensory evaluation, that is, the evaluation of the skin feel, was evaluated by the feel when the foam rubber sample was pressed against the cheek.
The evaluation of skin feel and sensuality is as follows.
A: It is smooth, has a very smooth feel, and feels good.
B: Smooth and silky.
C: Smooth but slightly rough.
D: It is not smooth and has a rough and rough feeling.

3. 3. Results The results are also shown in Table 1-2.
In Table 1-2, A, B, C, and D in the comprehensive judgment column mean the following.
A: Very good.
B: Excellent.
C: Slightly inferior.
D: Very inferior.

(1) Satisfaction status of each requirement of Example 1-8 Example 1-8 satisfies all of the following requirements (a)-(d).
-Requirement (a): Includes a rubber-based polymer.
-Requirement (b): Contains fats and oils containing fatty acid components.
-Requirement (c): Contains silicone oil.
-Requirement (d): Silicone oil is contained in an amount of more than 1 part by mass and less than 20 parts by mass with respect to 100 parts by mass of the rubber-based polymer.

(2) Satisfaction status of each requirement of Comparative Example 1-5 On the other hand, Comparative Example 1-4 does not satisfy the following requirements.
In Comparative Example 1, the requirement (c) is not satisfied.
In Comparative Example 2, the requirement (b) is not satisfied.
In Comparative Example 3, the requirement (d) is not satisfied.
In Comparative Example 4, the requirement (d) is not satisfied.
In Comparative Example 5, the requirements (b), (c) and (d) are not satisfied.

(3) Results and Discussion Examples 1-8 had a good surface appearance, a smooth feel on the skin, and a good overall judgment. In Examples 1-8, the skin feels smooth and smooth even after the 10th washing with water.
Further, in Examples 5, 6 and 7 in which the modified silicone oil is more than 1 part by mass and less than 10 parts by mass with respect to 100 parts by mass of the rubber-based polymer, the initial and 10th washing with water are very smooth and smooth. The feel was good and the overall judgment was very good.
On the other hand, in Comparative Example 1 containing no silicone oil, the skin contact after the 10th washing with water was inferior to that of the example, and the comprehensive judgment was also inferior to that of the example.
Comparative Example 2 containing no fat and oil containing a fatty acid component had a poor surface appearance, was inferior to the skin in the initial stage and 10th washing with water, and was inferior to the example in the comprehensive judgment.
In Comparative Example 3 in which the amount of silicone oil was 20 parts by mass or more, the surface appearance was poor, the surface roughness Rz was high, the skin contact was inferior to that of the example, and the comprehensive judgment was also inferior to that of the example.
In Comparative Example 4 in which the amount of silicone oil was 1 part by mass or less, the initial skin contact and the 10th washing with water were inferior to those of the examples, and the comprehensive judgment was also inferior to the examples.
In Comparative Example 5 which did not contain fats and oils containing a fatty acid component and did not contain silicone oil, the initial skin contact and the 10th washing with water were inferior to those of the examples, and the comprehensive judgment was also inferior to the examples.

4. Effect of Examples According to the above examples, it is possible to provide a foam rubber that is soft, feels good on the skin, and has a smooth feel.

The present disclosure is not limited to the embodiments detailed above and can be modified or modified in various ways.

1 ... Makeup application tool

Claims (6)

A foam rubber containing a rubber-based polymer, fats and oils containing a fatty acid component, and silicone oil.
A foam rubber containing 100 parts by mass of the silicone oil in an amount of more than 1 part by mass and less than 20 parts by mass with respect to 100 parts by mass of the rubber-based polymer. The foam rubber according to claim 1, wherein the silicone oil contains at least a polyether-modified silicone oil. The foam rubber according to claim 1 or 2, wherein the dynamic friction coefficient (μd) is 1.5 or less. The foam rubber according to any one of claims 1 to 3, wherein the 50% compression load is 5 gf / cm ² or more and 15 gf / cm ² or less. The foam rubber according to any one of claims 1 to 4, wherein the surface roughness Rz is 5 μm or more and 40 μm or less. A cosmetic application tool comprising the foam rubber according to any one of claims 1 to 5.

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