Antimicrobial sponge for cosmetics

Abstract

To provide an antimicrobial sponge for cosmetics which has excellent antimicrobial properties even without use of organic synthetic antimicrobial agents and also has excellent antimicrobial sustainability and washability, and an antimicrobial applicator for cosmetics which comprises the antimicrobial sponge for cosmetics and which can be suitably used to, for example, apply cosmetics, such as liquid foundations and powder cosmetics, to the skin.SOLUTION: There are provided an antimicrobial sponge for cosmetics which contains a vegetable essential oil as an essential oil component, and an antimicrobial applicator for cosmetics which comprises the antimicrobial sponge for cosmetics.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an antibacterial cosmetic sponge. More specifically, the present invention relates to an antibacterial cosmetic sponge that is excellent in antibacterial properties, antibacterial retention, and washability, and to an antibacterial cosmetic applicator that has the antibacterial cosmetic sponge and can be suitably used for applying cosmetics such as liquid foundations and powder cosmetics to the skin. [Background technology]

[0002] When a cosmetic preparation is applied to the skin with a cosmetic tool, sebum from the skin, peeled skin, etc. adhere to the cosmetic tool. If the cosmetic tool with sebum from the skin, peeled skin, etc. adhered thereto is left as is, germs may grow on the cosmetic tool, causing a foul odor. In order to prevent germs from growing on the cosmetic tool, the cosmetic tool contains an organic synthetic antibacterial agent, such as a pyrithione metal salt antibacterial agent such as zinc pyrithione, or a thiabenzole antibacterial agent such as thiabendazole (see, for example, claim 1 of Patent Document 1 and paragraph

[0059] of Patent Document 2).

[0003] However, in recent years, there has been a trend toward restricting the use of synthetic organic antibacterial agents from the standpoint of human safety and environmental protection, and therefore there is a demand for the development of cosmetic tools that have antibacterial properties without using synthetic organic antibacterial agents.

[0004] Furthermore, when cosmetics adhere to an antibacterial cosmetic applicator, the antibacterial cosmetic applicator is generally washed to keep the antibacterial cosmetic applicator hygienic. However, when an antibacterial cosmetic applicator that uses an organic synthetic antibacterial agent is washed, the organic synthetic antibacterial agent is removed from the antibacterial cosmetic applicator together with the adhered cosmetics, which not only makes it impossible to maintain the antibacterial properties of the antibacterial cosmetic applicator, but also raises concerns about the impact on the natural environment as the organic synthetic antibacterial agent removed from the antibacterial cosmetic applicator is discharged into the water. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-85034 [Patent Document 2] JP 2017-123907 A Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above-mentioned conventional technology, and an object of the present invention is to provide an antibacterial cosmetic sponge that has excellent antibacterial properties even without the use of an organic synthetic antibacterial agent and also has excellent antibacterial retention and washability, and an antibacterial cosmetic applicator that has the antibacterial cosmetic sponge and can be suitably used when applying cosmetics such as liquid foundations and powder cosmetics to the skin. [Means for solving the problem]

[0007] The present invention relates to (1) An antibacterial cosmetic sponge, which is a cosmetic sponge and contains a vegetable essential oil as an essential oil component; (2) The antibacterial cosmetic sponge according to (1) above, wherein the vegetable essential oil is at least one vegetable essential oil selected from the group consisting of peppermint oil, lavender oil, tea tree oil, eucalyptus oil, lemon oil, hinokitiol oil and neem oil. (3) The antibacterial cosmetic sponge according to (1) above, wherein the vegetable essential oil is contained in the polymer constituting the sponge. (4) The antibacterial cosmetic sponge according to (3) above, wherein the amount of the plant essential oil is 0.0002 to 0.9 parts by mass per 100 parts by mass of the non-volatile content of the polymer constituting the sponge. (5) The antibacterial cosmetic sponge according to (3) above, wherein the polymer constituting the sponge is at least one polymer selected from the group consisting of acrylonitrile-butadiene rubber, styrene-butadiene rubber, natural rubber, isoprene rubber, urethane rubber, cellulose, polyvinyl alcohol, thermoplastic polyester, polyolefin, and soft polyurethane. (6) An antibacterial cosmetic sponge according to any one of (1) to (5) above, which has an antibacterial activity value of 2.0 or more based on the standard of JIS L-1902 (2015) and no halo width based on the standard of JIS L-1902 (2015) is detected; and (7) An antibacterial cosmetic applicator having the antibacterial cosmetic sponge according to any one of (1) to (5) above. Regarding. Effect of the Invention

[0008] According to the present invention, there are provided an antibacterial cosmetic sponge which has excellent antibacterial properties even without the use of an organic synthetic antibacterial agent and which also has excellent antibacterial retention and washability, and an antibacterial cosmetic applicator which has the antibacterial cosmetic sponge and can be suitably used, for example, when applying cosmetics such as liquid foundations and powder cosmetics to the skin. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] As described above, the antibacterial cosmetic sponge of the present invention is characterized by containing a vegetable essential oil as an essential oil component. Since the antibacterial cosmetic sponge of the present invention contains vegetable essential oil, it has excellent antibacterial properties without using conventional organic synthetic antibacterial agents, and the antibacterial properties are maintained even after washing, so it also has excellent antibacterial maintenance properties and washing resistance.

[0010] In the present invention, antibacterial retention means that the plant essential oil is unlikely to bleed out of the antibacterial cosmetic sponge, and the plant essential oil is retained in the antibacterial cosmetic sponge, thereby maintaining the antibacterial properties. In the present invention, washing resistance means that the antibacterial properties are maintained even after the antibacterial cosmetic sponge is washed.

[0011] The vegetable essential oils used in the cosmetic antibacterial sponge of the present invention are naturally derived, and therefore are distinguished from commonly used organic synthetic antibacterial agents. Examples of vegetable essential oils include peppermint oil, lavender oil, tea tree oil, eucalyptus oil, lemon oil, hinokitiol oil and neem oil. These vegetable essential oils may be used alone or in combination of two or more. The vegetable essential oils used in the cosmetic antibacterial sponge of the present invention may include essential oils other than the above-mentioned vegetable essential oils within the scope that does not impede the purpose of the present invention.

[0012] A vegetable essential oil is usually a mixture of a plurality of components. Peppermint oil contains menthol, menthone and 1,8-cineole as main components, and other components such as methyl acetate, menthofuran, isomenthone, limonene, and pinene as minor components. The content of each component contained in peppermint oil cannot be determined in general because it varies depending on the conditions when peppermint stems and leaves are distilled with steam, but an example of the content is peppermint oil containing about 40 to 60 mass% of menthol, about 15 to 25 mass% of menthone, and about 5 to 10 mass% of 1,8-cineole as main components. Peppermint oil has excellent affinity with the sponge made of the soft foamed resin described above, and can prevent the elution of vegetable essential oils and improve washing resistance, so it can be suitably used in the present invention. Lavender oil contains 30-40% by mass of linalyl acetate as the main component, and also contains limonene, linalool, geraniol, nerol, cineole, d-borneol, etc. Tea tree oil contains terpineol, cineole, etc. Eucalyptus oil contains citronellal, cineole, camphene, pinene, etc. Lemon oil contains d-limonene, citral, etc. Hinokitiol oil contains hinokitiol, etc. Neem oil contains azadirachtin, etc.

[0013] Among the vegetable essential oils, peppermint oil is preferred because it has excellent affinity with sponges made of rubbers such as acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), and urethane rubber, and soft foamed resins such as soft polyurethane foam, and can prevent the elution of vegetable essential oils and improve washing resistance.

[0014] The plant essential oil is preferably contained in the polymer constituting the sponge. The plant essential oil is contained in the polymer constituting the sponge, including the plant essential oil being contained in the polymer of the sponge's raw material beforehand, the plant essential oil being absorbed in the polymer constituting the sponge after the sponge is made, and the plant essential oil being adsorbed in the polymer constituting the sponge after the sponge is made. From the viewpoint of improving the antibacterial maintenance and washing resistance of the cosmetic antibacterial sponge, the plant essential oil is preferably contained in the polymer of the sponge's raw material beforehand.

[0015] The amount of vegetable essential oil per 100 parts by mass of the non-volatile content of the polymer constituting the sponge cannot be determined in general because it varies depending on the type of the vegetable essential oil, but from the viewpoint of imparting sufficient antibacterial properties to the sponge, it is preferably 0.0002 parts by mass or more, more preferably 0.0015 parts by mass or more, even more preferably 0.0075 parts by mass or more, and even more preferably 0.015 parts by mass or more, and from the viewpoint of reducing the stickiness imparted to the sponge by the vegetable essential oil and suppressing the odor of the vegetable essential oil, it is preferably 0.9 parts by mass or less, more preferably 0.6 parts by mass or less, even more preferably 0.3 parts by mass or less, even more preferably 0.15 parts by mass or less, and particularly preferably 0.145 parts by mass or less. The non-volatile content of the polymer means a polymer from which volatile components such as the solvent contained in the polymer have been removed.

[0016] Examples of the polymer constituting the sponge include rubbers such as acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), natural rubber (NR), isoprene rubber (IR), and urethane rubber; celluloses such as carboxymethyl cellulose; polyvinyl alcohol; thermoplastic polyesters; polyolefins; and thermoplastic resins such as soft polyurethane, but the present invention is not limited to these examples. These polymers may be used alone or in combination of two or more kinds.

[0017] Examples of the thermoplastic polyester include polyethylene terephthalate and polybutylene terephthalate, but the present invention is not limited to these examples. Examples of the polyolefin include polyethylene, polypropylene, and ethylene-propylene copolymer, but the present invention is not limited to these examples.

[0018] Among the polymers constituting the sponge, acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), natural rubber, isoprene rubber, urethane rubber and soft polyurethane are preferred because of their excellent affinity with plant essential oils, and from the viewpoint of improving the retention of the antibacterial properties of the sponge, acrylonitrile-butadiene rubber (NBR) and styrene-butadiene rubber (SBR) are more preferred, with acrylonitrile-butadiene rubber (NBR) being even more preferred.

[0019] In the present invention, the combination of acrylonitrile-butadiene rubber (NBR) and peppermint oil is preferable from the viewpoints of having excellent affinity between the NBR and peppermint oil, preventing the elution of essential oils, improving washing resistance, and improving the maintenance of the antibacterial properties of the sponge.

[0020] When rubber is used as the polymer, the rubber can be used as a latex. Polymers such as thermoplastic resins and cellulose can be used in a form suitable for the polymer, such as a solution, emulsion, or suspension. When polyolefin is used as the polymer, the polyolefin melted by heating and the plant essential oil can be kneaded to obtain a uniform composition. When soft polyurethane is used as the polymer, a foam of the soft polyurethane (soft polyurethane foam) can be used as the sponge.

[0021] The antibacterial cosmetic sponge of the present invention can be produced, for example, by mixing a vegetable essential oil with a polymer, dispersing the vegetable essential oil in the polymer to prepare a polymer containing the vegetable essential oil, mixing a gas such as air, nitrogen gas, or carbon dioxide gas into the polymer so that the sponge has a predetermined expansion ratio to disperse the gas bubbles in the polymer, filling a mold with the polymer in which the bubbles are dispersed, and then heating it to a predetermined temperature to produce an antibacterial cosmetic sponge (hereinafter referred to as Production Method A); mixing a polymer, a vegetable essential oil, and a chemical foaming agent such as carbonate or bicarbonate, heating the resulting mixture to decompose the chemical foaming agent and foam the polymer to produce an antibacterial cosmetic sponge (hereinafter referred to as Production Method B); and impregnating a sponge with vegetable essential oil, and then washing the sponge with a solvent such as water as necessary to remove the vegetable essential oil free in the sponge to produce an antibacterial cosmetic sponge (hereinafter referred to as Production Method C). However, the present invention is not limited to only these methods. Among these methods, from the viewpoint of improving the durability of the antibacterial property and the washability of the antibacterial cosmetic sponge, the manufacturing method A and the manufacturing method B are preferred, and the manufacturing method A is more preferred. When the manufacturing method A and the manufacturing method B are adopted, the plant essential oil is dispersed in the polymer, but may be present on the surface of the polymer.

[0022] In the manufacturing methods A to C, the plant essential oil may be used as it is, or may be used as an organic solvent solution. The type of organic solvent is preferably appropriately selected according to the type of plant essential oil. A suitable organic solvent is, for example, ethanol, but the present invention is not limited to only such an example. The concentration of the plant essential oil in the organic solvent solution of the plant essential oil is not particularly limited, and it is preferable to adjust the concentration of the plant essential oil to suit each manufacturing method. In the manufacturing method C, it is preferable to use an organic solvent solution of the plant essential oil, and it is more preferable to use an organic solvent solution of the plant essential oil having a concentration of about 10 to 5000 ppm.

[0023] In the antibacterial cosmetic sponge of the present invention, it is preferable that gas bubbles are dispersed in the polymer containing plant essential oil, in order to improve the durability of the antibacterial properties and washing resistance of the antibacterial cosmetic sponge.

[0024] The sponge may have either closed cells or open cells, but from the viewpoint of enhancing the retention of plant essential oil within the sponge, it is preferable for the sponge to have open cells.

[0025] The expansion ratio of the antibacterial cosmetic sponge is not particularly limited, but is preferably about 3 to 10 times from the viewpoint of improving the usability when the antibacterial cosmetic sponge is used as an antibacterial cosmetic applicator such as a puff. The expansion ratio is a value obtained by dividing the volume of the sponge by the volume of the polymer that is the raw material of the sponge. The diameter of the air bubbles contained in the sponge is not particularly limited, but is usually preferably about 0.01 to 50 μm.

[0026] The cosmetic antibacterial sponge of the present invention may contain additives such as vegetable oils such as olive oil, colorants, and fragrances, as long as the object of the present invention is not hindered. The additives may be contained in the polymer constituting the sponge, or may be contained in the air bubbles constituting the sponge. When vegetable oils such as olive oil are contained in the cosmetic antibacterial sponge of the present invention, the flexibility of the cosmetic antibacterial sponge can be increased.

[0027] The antibacterial cosmetic sponge of the present invention can be obtained in the manner described above. The antibacterial cosmetic sponge of the present invention has antibacterial properties without the use of conventional organic synthetic antibacterial agents, and has excellent washability because it can maintain its antibacterial properties even after the antibacterial cosmetic sponge is washed after cosmetics such as liquid foundation or powder cosmetics are attached thereto, making it suitable for use as an antibacterial cosmetic applicator.

[0028] Among the antibacterial cosmetic sponges of the present invention, a sponge in which acrylonitrile-butadiene rubber (NBR) and peppermint oil are used in combination, from the viewpoints of having excellent affinity between the acrylonitrile-butadiene rubber (NBR) and peppermint oil, preventing the elution of plant essential oils, improving washing resistance, and improving the maintenance of the antibacterial properties of the sponge, and in which air bubbles are dispersed in the acrylonitrile-butadiene rubber (NBR) containing peppermint oil is preferred.

[0029] The types and contents of the components such as plant essential oils and organic synthetic antibacterial agents in the cosmetic antibacterial sponge can be identified using analytical equipment such as liquid chromatography, gas chromatography, etc. More specifically, the types and contents of the components such as plant essential oils and organic synthetic antibacterial agents in the cosmetic antibacterial sponge can be determined, for example, by preparing an extract by extracting the components contained in the cosmetic antibacterial sponge with an extraction solvent, and examining the retention time of the extract and the peak size of each component using gas chromatography to perform qualitative and quantitative analysis of each component.

[0030] The antibacterial cosmetic sponge of the present invention has an antibacterial activity value of 2.0 or more as measured in accordance with the provisions of JIS L-1902 (2015), more specifically, the measurement method described in the Examples below, and no halo width is detected, demonstrating excellent antibacterial retention.

[0031] The antibacterial cosmetic applicator of the present invention has the antibacterial cosmetic sponge. Examples of the antibacterial cosmetic applicator include a cosmetic sponge puff, a facial cleansing sponge, and a cosmetic tip, but the present invention is not limited to these examples. The cosmetic sponge puff is a sponge puff used when applying a cosmetic to human skin by taking the cosmetic on the sponge puff. The facial cleansing sponge is a sponge used when applying a facial cleanser to human facial skin by taking the facial cleanser on the sponge.

[0032] The antibacterial cosmetic applicator of the present invention can be produced, for example, by using the production methods A to C of the antibacterial cosmetic sponge.

[0033] For example, when manufacturing an antibacterial cosmetic applicator using manufacturing method A for an antibacterial cosmetic sponge, a plant essential oil is mixed with a polymer and the plant essential oil is dispersed in the polymer to prepare a polymer containing the plant essential oil, a gas such as air is mixed into the polymer so that the sponge has a predetermined expansion ratio to disperse the gas bubbles in the polymer, the polymer with the dispersed gas bubbles is filled into a mold having an inner shape corresponding to the predetermined shape of an antibacterial cosmetic applicator, the mold is heated to a temperature of about 80 to 130°C to form an antibacterial cosmetic sponge, and the obtained antibacterial cosmetic sponge is removed from the mold and cut to a predetermined thickness as necessary, thereby producing an antibacterial cosmetic applicator.

[0034] For example, when manufacturing an antibacterial cosmetic applicator using manufacturing method B for an antibacterial cosmetic sponge, a polymer, a vegetable essential oil, and a chemical foaming agent are mixed, the mixture is filled into a mold having an inner surface shape corresponding to a predetermined shape of an antibacterial cosmetic applicator, and the mold is heated to a temperature of about 80 to 130°C to decompose the chemical foaming agent and foam the polymer, forming an antibacterial cosmetic sponge containing the vegetable essential oil in the polymer, and the obtained antibacterial cosmetic sponge is removed from the mold and cut to a predetermined thickness as necessary, thereby producing an antibacterial cosmetic applicator.

[0035] For example, when producing an antibacterial cosmetic applicator using manufacturing method C for an antibacterial cosmetic sponge, the sponge is impregnated with vegetable essential oil to produce an antibacterial cosmetic sponge, and then, if necessary, the antibacterial cosmetic sponge is washed with a solvent such as water to remove any free and attached vegetable essential oil within the sponge, and the antibacterial cosmetic sponge is cut to a predetermined thickness as necessary, thereby producing an antibacterial cosmetic applicator.

[0036] The antibacterial cosmetic applicator of the present invention uses the antibacterial cosmetic sponge of the present invention, and therefore has excellent antibacterial properties without the use of organic synthetic antibacterial agents, and also has excellent antibacterial retention and washing resistance, and can be preferably used, for example, when applying cosmetics such as liquid foundations and powder cosmetics to the skin. EXAMPLES

[0037] Next, the antibacterial cosmetic sponge of the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

[0038] Examples 1 to 8 A latex composition was prepared by mixing 100 parts by mass of NBR latex (manufactured by Zeon Corporation, trade name: NIPOL LX531B, resin solid content: 60% by mass) as a polymer constituting the sponge, 1.3 parts by mass of sulfur (manufactured by Hosoi Chemical Co., Ltd.) as a vulcanizing agent, 1.5 parts by mass of a vulcanization accelerator (manufactured by Kawaguchi Chemical Co., Ltd., trade name: Accel MZ) as a vulcanization aid (manufactured by Uniroyal Corporation, trade name: Trimenbase), 1.5 parts by mass of an antioxidant (manufactured by Kawaguchi Chemical Co., Ltd., trade name: Antage BHT) and 3.0 parts by mass of sodium silicofluoride (manufactured by Mitsui Toatsu Chemical Co., Ltd.) to a uniform composition.

[0039] The plant essential oils shown in Table 1 were added to the latex composition in the amounts shown in Table 1 per 100 parts by mass of non-volatile content of NBR latex contained in the latex composition obtained above, and mixed to obtain a uniform composition to prepare a mixture.

[0040] The mixture obtained above was expanded to 5 times its volume by mixing air into it (expansion ratio: 5 times), and then the mixture was poured into an aluminum cylinder with an inner diameter of 55 mm. The cylinder was then heated at 120°C for 25 minutes to obtain a cylindrical sponge. The sponge obtained above was removed from the cylinder, washed with water, dried, and then cut to a thickness of 8 mm. The edges were polished to produce an antibacterial cosmetic sponge. All of the obtained antibacterial cosmetic sponges had open cells.

[0041] [Antibacterial] The antibacterial activity value was examined to evaluate the antibacterial properties based on the provisions of JIS L-1902 (2015). 0.4g pieces of sponge were taken from three different locations of the antibacterial cosmetic sponge and used as test pieces.

[0042] Staphylococcus aureus (initial number of bacteria: 1.5 x 10 5 The test piece was placed on an agar medium containing A (CFU / mL) and the bacteria were cultured for 18 hours in a thermostatic chamber at 37°C. The test piece was then washed with water to remove the bacteria, and the survival cell count A (CFU / mL) was measured. CFU (colony forming unit) refers to colony forming units.

[0043] As a control, the test piece was not placed on the agar medium, and the bacteria were cultured in a constant temperature room at 37°C for 18 hours in the same manner as above. The test piece was then washed with water to remove the bacteria, and the viable bacterial count B (CFU / mL) was measured.

[0044] Next, the formula: [Antibacterial activity value] = log (number of surviving bacteria B / number of surviving bacteria A) The antibacterial activity value was calculated based on the above, and the antibacterial property was evaluated based on the following evaluation criteria. (Evaluation Criteria) ◎: Antibacterial activity value is 5.5 or more (pass). ○: Antibacterial activity value is 2.0 or more and less than 5.5 (pass). ×: Antibacterial activity value is less than 2.0 (failure).

[0045] [Antibacterial maintenance] Based on the provisions of JIS L-1902 (2015), the halo width was examined to evaluate the antibacterial durability. 0.4g pieces of sponge were taken from three different places of the antibacterial cosmetic sponge and used as test pieces.

[0046] Staphylococcus aureus bacteria solution 1mL (initial number of bacteria: 1.5 x 10 5 CFU / mL) and 15 mL of agar medium adjusted to about 45°C were mixed in a petri dish, and the agar medium was cooled to room temperature and solidified. Excess water was removed by tilting the petri dish.

[0047] Next, the test piece was placed on the surface of the agar medium in the petri dish and the bacteria were cultured in a constant temperature room at 37°C for 24 hours. The width of the halo formed around the test piece was then measured and calculated using the formula: [Halo width (mm)] = [[Halo diameter (mm)] - [Test piece length (mm)]] / 2 The halo width was calculated based on the above, and the antibacterial maintenance was evaluated based on the following evaluation criteria. Note that the smaller the halo width, the better the antibacterial maintenance.

[0048] (Evaluation Criteria) ◎: No halo width detected (passed). ×: Halo width was detected and was less than 1 mm (failed). ××: The halo width is 1 mm or more (failed).

[0049] [Washing resistance] Based on the provisions of JIS L-1042 (2015), the test pieces were immersed in an aqueous solution containing 0.1% by mass of neutral detergent at a water temperature of 40°C for 30 minutes, and then washed by rubbing with hands 100 times. The antibacterial properties and antibacterial retention of the test pieces were evaluated in the same manner as described above.

[0050] [Feeling of use] Before the washing test, the test pieces were examined for odor and stickiness, and the feel when used was evaluated based on the following evaluation criteria.

[0051] (Evaluation Criteria) ⊚: The test piece had almost no odor or stickiness, and was suitable for practical use (passed). ◯: The test piece had a slight odor or was sticky, but did not interfere with practical use (passed). △: The test piece had an odor or was sticky, but was usable (passed). ×: The test piece had an odor or sticky feeling that interfered with practical use (failed).

[0052] [No use of synthetic organic antibacterial agents] The use of organic synthetic antibacterial agents in the test specimens was used as an indicator, and the use of organic synthetic antibacterial agents was evaluated based on the following evaluation criteria.

[0053] (Evaluation Criteria) ◎: No synthetic organic antibacterial agents were used in the test specimen. ×: An organic synthetic antibacterial agent is used in the test piece.

[0054] [Table 1]

[0055] Examples 37 to 41 A latex composition was prepared by mixing 100 parts by mass of NBR latex (manufactured by Zeon Corporation, trade name: NIPOL LX531B, resin solid content: 60% by mass) as a polymer constituting the sponge, 1.3 parts by mass of sulfur (manufactured by Hosoi Chemical Co., Ltd.) as a vulcanizing agent, 1.5 parts by mass of a vulcanization accelerator (manufactured by Kawaguchi Chemical Co., Ltd., trade name: Accel MZ) as a vulcanization aid (manufactured by Uniroyal Corporation, trade name: Trimenbase), 1.5 parts by mass of an antioxidant (manufactured by Kawaguchi Chemical Co., Ltd., trade name: Antage BHT) and 3.0 parts by mass of sodium silicofluoride (manufactured by Mitsui Toatsu Chemical Co., Ltd.) to a uniform composition.

[0056] The latex composition obtained above was expanded to 5 times its volume by mixing air into it (expansion ratio: 5 times), and then the latex composition was poured into an aluminum cylinder having an inner diameter of 55 mm. The cylinder was then heated at 120°C for 25 minutes to obtain a cylindrical sponge. The sponge obtained above was removed from the cylinder, washed with water, dried, and then cut to a thickness of 8 mm, and the edges were ground to produce a cosmetic sponge.

[0057] Next, the cosmetic sponge obtained above was immersed for 1 hour in an ethanol solution (liquid temperature: 23°C) of peppermint oil having the concentration of peppermint oil shown in Table 2, and then the cosmetic sponge was removed from the ethanol solution and washed with water to remove the peppermint oil free within the cosmetic sponge, and the cosmetic sponge was dried for 3 hours in a dryer with an internal temperature of 80°C to produce an antibacterial cosmetic sponge. All of the obtained antibacterial cosmetic sponges had open cells.

[0058] Next, the physical properties of the antibacterial cosmetic sponge obtained above were evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0059] [Table 2]

[0060] Comparative Examples 1 to 9 An antibacterial cosmetic sponge was prepared in the same manner as in Example 1, except that in place of 0.0002 parts by mass of peppermint oil per 100 parts by mass of non-volatile content of NBR latex, an organic synthetic antibacterial agent shown in Table 3 was used in the amount shown in Table 3.

[0061] Next, the physical properties of the antibacterial cosmetic sponges obtained in each Comparative Example were evaluated in the same manner as in Example 1. The results are shown in Table 3. The numerical value in parentheses for antibacterial retention indicates the detected halo width.

[0062] In Table 3, the abbreviations for the organic synthetic antibacterial agents have the following meanings: ZPT: Zinc pyrithione IPBC: propyl iodide butylcarbamate CCR: Chlorocresol

[0063] [Table 3]

[0064] From the results shown in Table 3, it can be seen that in each comparative example, an organic synthetic antibacterial agent is used in the cosmetic antibacterial sponge, and the organic synthetic antibacterial agent removed from the cosmetic antibacterial sponge is discharged, raising concerns about the impact on the natural environment. In addition, the cosmetic antibacterial sponges obtained in each comparative example are inferior in washability or usability, and the confirmation of halo width indicates that they are inferior in antibacterial maintenance. In addition, the cosmetic antibacterial sponge obtained in comparative example 1 uses an organic synthetic antibacterial agent (zinc pyrithione), and a halo width (bacteria growth inhibition width) is confirmed, and further, a decrease in the halo width is confirmed after the washing test, indicating that the organic synthetic antibacterial agent may bleed out from the test piece and the leached organic synthetic antibacterial agent may come into direct contact with human skin.

[0065] In contrast, the cosmetic antibacterial sponges obtained in each Example do not use organic synthetic antibacterial agents, as shown in Tables 1 and 2, and therefore do not release organic synthetic antibacterial agents from the cosmetic sponges, which shows that they have the advantage of being environmentally friendly.

[0066] In addition, the antibacterial cosmetic sponges obtained in each Example were confirmed to have sufficient antibacterial activity values ​​to exhibit antibacterial properties, since lavender oil, tea tree oil, eucalyptus oil, lemon oil, hinokitiol oil, or neem oil was used, and no halo width was detected. In addition, the antibacterial cosmetic sponges obtained in each Example were confirmed to have antibacterial activity values ​​100 times or more higher than those of the antibacterial cosmetic sponges obtained in each Comparative Example.

[0067] Therefore, the antibacterial cosmetic sponges obtained in each Example have excellent antibacterial retention because no halo width is detected, and it is understood that the exudation of the plant essential oil makes it difficult for the plant essential oil to come into contact with human skin. In addition, when the antibacterial cosmetic sponges obtained in each Example are washed, the antibacterial properties are maintained even after washing, and since no halo width is detected, the antibacterial retention is excellent, and therefore it is understood that the washability is also excellent.

[0068] Furthermore, the antibacterial cosmetic sponges obtained in Examples 1 to 7, especially those obtained in Examples 1 to 6, contain acrylonitrile-butadiene rubber (NBR) and peppermint oil in combination, It was found that the product prevented the elution of plant-derived essential oils, improved washing resistance, improved the retention of the antibacterial properties of the sponge, and also provided an excellent feel when used.

[0069] Therefore, the antibacterial cosmetic sponge of the present invention does not use conventional organic synthetic antibacterial agents, so it is environmentally friendly and has excellent antibacterial properties. In addition, the plant essential oils are not prone to seeping out (bleeding), so it has excellent antibacterial retention properties. For example, the antibacterial properties are maintained even when the sponge is washed after cosmetics such as liquid foundation or powder cosmetics are attached to it, so it also has excellent washing resistance, making it ideal for use as an antibacterial cosmetic applicator.

Claims

1. An antibacterial cosmetic sponge comprising a sponge and a plant essential oil and used when applying cosmetics to the skin, characterized in that the sponge is impregnated with the plant essential oil.

2. An antibacterial cosmetic sponge as described in claim 1, wherein the polymer constituting the sponge is a thermoplastic resin.

3. An antibacterial cosmetic sponge as described in claim 2, wherein the thermoplastic resin is at least one selected from the group consisting of rubber, cellulose, polyvinyl alcohol, thermoplastic polyester, polyolefin and soft polyurethane.

4. An antibacterial cosmetic sponge as described in claim 1, wherein the polymer constituting the sponge is acrylonitrile-butadiene rubber.

5. An antibacterial cosmetic sponge as described in claim 1, wherein the vegetable essential oil is at least one vegetable essential oil selected from the group consisting of peppermint oil, lavender oil, tea tree oil, eucalyptus oil, lemon oil, hinokitiol oil and neem oil.

6. An antibacterial cosmetic sponge as described in claim 5, wherein the plant essential oil is peppermint oil.

7. An antibacterial cosmetic applicator comprising the antibacterial cosmetic sponge according to claim 1.

8. A method for producing an antibacterial cosmetic sponge containing a sponge and vegetable essential oil and used when applying cosmetics to the skin, characterized in that after impregnating the sponge with vegetable essential oil, the vegetable essential oil that is free within the cosmetic sponge is removed.