METHOD OF PRETREATMENT FOR NAIL COATING, METHOD OF DECORATING NAIL AND PLASMA IRRADIATION DEVICE

Abstract

The present invention provides a method of pretreatment for nail coating, the method including irradiating plasma to a nail, before the step of applying a nail coating liquid to the nail, wherein the gas used for generating the plasma is one or more gases selected from the group consisting of nitrogen gas, oxygen gas and carbon dioxide gas.

Claims

1. A method of pretreatment for nail coating, the method comprising irradiating plasma to a nail or a nail coating liquid applied to the nail, before or during the step of applying the nail coating liquid to the nail, wherein the gas used for generating the plasma is one or more gases selected from the group consisting of nitrogen gas, oxygen gas and carbon dioxide gas.

2. The method of pretreatment for nail coating according to claim 1, wherein the plasma is atmospheric pressure plasma.

3. A method of decorating a nail, the method comprising: irradiating plasma to the nail; applying a curable nail coating liquid to the nail; and curing the curable nail coating liquid, wherein the gas used for generating the plasma is one or more gases selected from the group consisting of nitrogen gas, oxygen gas, and carbon dioxide gas.

4. The method of decorating a nail according to claim 3, wherein the method does not comprise a step of polishing the nail.

5. A method of decorating a nail, the method comprising: irradiating plasma to a stone; applying a curable nail coating liquid to the nail; placing the stone irradiated with the plasma on the curable nail coating liquid applied on the nail; and curing the curable nail coating liquid, wherein the gas used for generating the plasma is one or more gases selected from the group consisting of nitrogen gas, oxygen gas and carbon dioxide gas.

6. The method of decorating a nail according to claim 3, further comprising irradiating plasma to the curable nail coating liquid which is applied to the nail, and is before or after curing.

7. A plasma irradiation device, comprising: a plasma generation section; and a gas supply section, wherein the plasma generation section has a porous structure with holes, and the plasma is emitted from each hole.

8. The plasma irradiation device according to claim 7, wherein the holes have a diameter of from 0.3 to 3.0 mm.

9. The plasma irradiation device according to claim 7, wherein the gas supply section supplies one or more gases selected from the group consisting of nitrogen gas, oxygen gas and carbon dioxide gas.

10. The plasma irradiation device according to claim 7, wherein the plasma irradiation device is for irradiating plasma to at least one selected from the group consisting of a nail, a stone and a coating liquid.

11. The method of decorating a nail according to claim 5, further comprising the step of irradiating plasma to the curable nail coating liquid which is applied to the nail, and is before or after curing.

12. The plasma irradiation device according to claim 8, wherein the gas supply section supplies one or more gases selected from the group consisting of nitrogen gas, oxygen gas and carbon dioxide gas.

13. The plasma irradiation device according to claim 8, wherein the plasma irradiation device is for irradiating plasma to at least one selected from the group consisting of a nail, a stone and a coating liquid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1 is a configuration diagram of a plasma irradiation device according to the present embodiment.

[0027] FIG. 2A and FIG. 2B are schematic diagrams of the plasma generation section of the plasma irradiation device shown in FIG. 1. FIG. 2A is a front view, and FIG. 2B is a view taken along the line b-b in FIG. 2A.

[0028] FIG. 3 is a graph showing the results of the tensile test in relation to the gas type.

[0029] FIG. 4 is a graph showing the results of the tensile test in relation to the plasma irradiation time.

[0030] FIG. 5 is a graph showing the relationship between the plasma gas type and the water contact angle.

[0031] FIG. 6 is a graph showing the results of the tensile test in relation to the gas type.

[0032] FIG. 7 is a graph showing the results of the tensile test in relation to the gas type.

MODE FOR CARRYING OUT THE INVENTION

[0033] Embodiments of the method of pretreatment for nail coating, the method of decorating a nail and the plasma irradiation device will be described below more specifically.

[Method of Pretreatment for Nail Coating]

[0034] The method of pretreatment for nail coating according to the present embodiment is a method of pretreatment for nail coating, the method including irradiating plasma to a nail or a nail coating liquid applied to the nail, before or during the step of applying the nail coating liquid to the nail, wherein the gas used for generating the plasma is one or more gases selected from the group consisting of nitrogen gas, oxygen gas and carbon dioxide gas.

[0035] The plasma irradiation is performed as a pretreatment for the application of the nail coating liquid. The nail coating liquid as used herein refers to a liquid to be applied to a fingernail of a human hand or a toenail of a human foot. Specifically, the definition of the nail coating liquid includes a liquid for a base coat, a lacquer liquid referred to as nail polish and a liquid for a top coat. The definition of the nail coating liquid also includes liquids for the protection and reinforcement of nails, such as those for sports, and those for the elderly and musical instrument players, in addition to those for decoration. Materials to be used for nail coating are not particularly limited, and examples thereof include resins such as acrylic resins, urethane resins, and nitrocellulose resins. Further, known curing methods such as curing by drying and curing by an energy ray such as UV can also be used for nail coating.

[0036] The plasma is irradiated to a nail before the application of a liquid for a base coat, by a plasma irradiation device. Further, the plasma can be irradiated to a base coat formed by drying a base coating liquid applied to the nail. In addition, the plasma can be irradiated to a nail polish formed by drying a lacquer liquid applied to the nail. It is preferred to use an irradiation device based on the principle of non-thermal equilibrium plasma, referred to as low-temperature plasma or atmospheric pressure plasma, as the plasma irradiation device. In such a plasma irradiation device, plasma is generated by applying a voltage to the gas continuously supplied to the device.

[0037] One type of gas selected from the group consisting of nitrogen gas, oxygen gas and carbon dioxide gas is used, as the gas to be supplied to the plasma irradiation device to generate plasma. These gases may be used singly, or as a mixture of a plurality of gases. For example, it is possible to use a simulated air gas containing about 78% nitrogen gas and about 21% oxygen gas, with the balance being carbon dioxide gas and/or an impurity gas(es). It is also possible to use air. Further, it is possible to use a gas containing: one gas selected from the group consisting of nitrogen gas, oxygen gas and carbon dioxide gas; and water vapor.

[0038] The effects to be described below, such as an adhesive force to a nail coating, can be expected, by the plasma irradiation using one gas selected from the group consisting of nitrogen gas, oxygen gas, and carbon dioxide gas.

(Improvement in Adhesion)

[0039] Performing the pretreatment of irradiating plasma to a nail using the above-described gas improves the adhesion of the nail coating liquid to be applied to the nail after the plasma irradiation. This eliminates the need for polishing the nail before the application of the nail coating liquid, which has been conventionally performed for the purpose of improving the adhesion. Therefore, it is possible to avoid a decrease in the thickness of the nail due to polishing, making it possible to prevent the whitened appearance and a decrease in the strength of the nail. Nail thickness affects the moisture content of nails, and a lower nail thickness makes the nails more susceptible to cracking and the like. However, the present embodiment requires no polishing before the application of the nail coating liquid, and thus it is possible to prevent nail cracking and the like, and helps to maintain healthy nails. Since the moisture content of nails tends to decrease in the elderly, in particular, the fact that polishing can be avoided as much as possible has a large effect particularly for the elderly.

[0040] Moreover, the improvement in the adhesion of the nail coating liquid enables the number of reapplications to be reduced.

[0041] The reason why the plasma irradiation improves adhesion is thought to be because adhesive functional groups are generated on the nail surface irradiated with the plasma.

[0042] Further, during the step of applying any of the coating liquids in general, including a base coat, a nail polish and a top coat, the adhesion of the nail polish to the base coat applied to a nail is expected to improve, by irradiating plasma to the base coat. In addition, the adhesion of the top coat to the nail polish is expected to improve, by irradiating plasma to the nail polish applied to the nail.

(Prevention of Nail Cracking)

[0043] As described above, performing the pretreatment of irradiating plasma to a nail using the above-described gas eliminates the need for polishing the nail before the application of the nail coating liquid, and accordingly, the thickness of the nail does not decrease, making it possible to prevent nail cracking. Further, the occurrence of nail cracking can be prevented, because any of the nail coating liquids for the protection and reinforcement of nails, such as those for sports, and those for the elderly and musical instrument players, can be applied thinly without uneven spots per a single application. In addition, by irradiating plasma to the surface of the underlying layer when such a nail coating liquid is applied in layers, the adhesion between coating liquid layers can be expected to improve, making it possible to easily reinforce the nail, and to prevent the nail from cracking and scratching.

(Degreasing Treatment is not Required)

[0044] Performing the pretreatment of irradiating plasma to a nail using the above-described gas makes it possible to clean the surface of the nail by a dry-cleaning effect. This eliminates the need for a degreasing treatment of wiping the nail surface with a nail polish remover or an organic solvent such as acetone, which has been conventionally performed for the purpose of improving the adhesion. Therefore, it is possible to reduce the percutaneous absorption of the organic solvent, and to prevent the discoloration of the nail.

(Improvement in Wettability)

[0045] Performing the pretreatment of irradiating plasma to a nail using the above-described gas makes it possible to improve the wettability of the surface of the nail. This allows for reducing the uneven spots in the nail coating liquid to be applied. A beauty serum may be applied to the nail surface before the application of the nail coating liquid thereto. Uneven spots in the beauty serum can be reduced by pretreatment of plasma irradiation using the above-described gas. Therefore, it is possible to evenly apply the beauty serum and the nail coating liquid. Therefore, it is possible to reduce the treatment time for performing nail coating, such as nail art.

[0046] The reason why the wettability is improved by the plasma irradiation is thought to be because the surface free energy of the nail surface irradiated with the plasma increases.

(Sterilization and Cleaning)

[0047] Performing the pretreatment of irradiating plasma to a nail using the above-described gas makes it possible to eliminate bacteria attached to the surface of the nail. Performing the pretreatment of irradiating plasma makes it possible to decompose and remove dirt such as bacteria or oils and fats on the nail and the fingertip. Therefore, it can be expected to prevent bacterial infection and to prevent the occurrence of green nail and the like. Further, the treatment of nail coating can be performed under good hygiene. Furthermore, due to dry cleaning without using any surfactant or organic solvent, a physical burden is allowed to be smaller than that in the case of using a surfactant or an organic solvent.

(Penetration of Beauty Serum)

[0048] There are cases where a beauty serum is applied to the nail surface before the application of the nail coating liquid thereto or after the removal of the nail coating liquid therefrom. Performing the pretreatment of irradiating plasma to a nail using the above-described gas before the application of the beauty serum makes it possible to promote the penetration of the beauty serum into the nail plate, lateral nail folds, nail grooves and the like. The moisture content of nails and skin is improved, by promoting the penetration of the beauty serum by the plasma irradiation. In other words, the moisture retention effect of the beauty serum is improved. A decrease in the moisture content of nails and skin may be one of the causes for the occurrence of cracks and fissures in the nails and the skin around the nails. That is, it can be expected to alleviate or to prevent the occurrence of cracks and fissures in the nails and the skin around the nails, and the like, by the plasma irradiation. The improvement in the moisture retention effect of the beauty serum can be expected to promote the action of the nail matrix which is a source of the healthy nail.

[0049] In both the cases of applying the nail coating liquid after application of the beauty serum and of applying the nail coating liquid without applying the beauty serum, performing the pretreatment of irradiating plasma using the above-described gas in advance makes it possible to enhance the effects of the beauty serum and the nail coating liquid to support nail care.

[0050] The effects described above work synergistically, making it possible to reduce the treatment time for performing nail coating, and to perform the application of the nail coating liquid that serves to maintain healthy nails and achieves a high adhesion, under good hygiene.

[0051] Furthermore, the healthy nail can be grown due to the above-described effects such as the improvement in adhesion, the prevention of nail cracking, the elimination of requirement of degreasing treatment, the improvement in wettability, the sterilization, and the penetration of the beauty serum. This offers a useful value to a person needing nail care. For example, in a sport athlete, a pitcher in baseball as a specific example, nail cracking affects play, and the defective nail leads to an injury. Therefore, the healthy nail can be grown for the purpose of reducing injuries affecting play, such as nail cracking.

[Method of Decorating Nail]

[0052] Next, an embodiment of the method of decorating a nail will be described specifically.

[0053] The method of decorating a nail according to the present embodiment is a method of decorating a nail, the method including: [0054] the step of irradiating plasma to the nail; [0055] the step of applying a curable nail coating liquid to the nail; and [0056] the step of curing the curable nail coating liquid, [0057] wherein the gas used for generating the plasma is one or more gases selected from the group consisting of nitrogen gas, oxygen gas, and carbon dioxide gas.

[0058] The curable nail coating liquid as used herein refers to a coating liquid which is cured by performing a curing treatment after the application, or by a polymerization reaction, among the liquids to be applied to a fingernail of a human hand or a toenail of a human foot. Such a curable nail coating liquid may be, for example, an energy ray-curable resin which is cured by the irradiation of an energy ray, such as a photocurable resin, particularly, an ultraviolet-curable (UV-curable) resin, and is referred to as gel nail polish. Further, the definition of the curable nail coating liquid includes an acrylic resin, a urethane resin, nitrocellulose and the like, which are used for attaching false nails and for nail sculpturing.

[0059] The step of irradiating plasma to the nail is performed, before the step of applying a curable nail coating liquid to the nail. It is also possible to irradiate plasma to the curable nail coating liquid which is applied to the nail and is before or after curing. It is preferred to use an irradiation device based on the principle of non-thermal equilibrium plasma, referred to as low-temperature plasma or atmospheric pressure plasma, as the plasma irradiation device for irradiating plasma. In such a plasma irradiation device, plasma is generated by applying a voltage to the gas continuously supplied to the device.

[0060] One type of gas selected from the group consisting of nitrogen gas, oxygen gas and carbon dioxide gas is used, as the gas to be supplied to the plasma irradiation device to generate plasma. These gases may be used singly, or as a mixture of a plurality of gases. For example, it is possible to use a simulated air gas containing about 78% nitrogen gas and about 21% oxygen gas, with the balance being carbon dioxide gas and/or an impurity gas(es). It is also possible to use air.

[0061] The effects to be described below can be obtained, by the plasma irradiation using one gas selected from the group consisting of nitrogen gas, oxygen gas and carbon dioxide gas.

(Improvement in Adhesion)

[0062] Performing the plasma irradiation treatment on a nail using the above-described gas improves the adhesion of the curable nail coating liquid to be applied to the nail after the plasma irradiation. This eliminates the need for polishing the nail before the application of the curable nail coating liquid, which has been conventionally performed for the purpose of improving the adhesion. Therefore, it is possible to avoid a decrease in the thickness of the nail due to polishing, making it possible to prevent the whitened appearance and a decrease in the strength of the nail. The nail thickness affects the moisture content of nails, and a lower nail thickness makes the nails more susceptible to cracking and the like. However, the present embodiment requires no polishing before the application of the curable nail coating liquid, and thus it is possible to prevent nail cracking and the like, and helps to maintain healthy nails. Since the moisture content of nails tends to decrease in the elderly, in particular, the fact that polishing can be avoided has a large effect particularly for the elderly.

[0063] Moreover, the improvement in the adhesion of the nail coating liquid enables the number of reapplications to be reduced. The reason why the plasma irradiation improves adhesion is thought to be because adhesive functional groups are generated on the nail surface irradiated with the plasma.

[0064] In cases where the application and the curing of the curable nail coating liquid are performed repeatedly to decorate a nail, the adhesion of the curable nail coating liquid applied as the top coat to the curable nail coating liquid applied as the base coat is expected to improve, by irradiating plasma to the curable nail coating liquid which is applied to the nail and is before or after curing.

(Degreasing Treatment is not Required)

[0065] Performing the plasma irradiation treatment on a nail using the above-described gas makes it possible to clean the surface of the nail by a dry-cleaning effect. This eliminates the need for a degreasing treatment of wiping the nail surface with a nail polish remover or an organic solvent such as acetone, which has been conventionally performed for the purpose of improving the adhesion. Therefore, it is possible to reduce the percutaneous absorption of the organic solvent, and to prevent the discoloration of the nail.

(Improvement in Wettability)

[0066] Performing the plasma irradiation treatment on a nail using the above-described gas makes it possible to improve the wettability of the surface of the nail. This allows for reducing the uneven spots in the curable nail coating liquid to be applied. A beauty serum may be applied to the nail surface before the application of the nail coating liquid thereto. Uneven spots in the beauty serum can be reduced by performing the plasma irradiation treatment using the above-described gas. Therefore, it is possible to evenly apply the beauty serum and the nail coating liquid. Therefore, it is possible to reduce the treatment time for performing nail coating.

[0067] The reason why the wettability is improved by the plasma irradiation is thought to be because the surface free energy of the nail surface irradiated with the plasma increases.

(Prevention of Nail Cracking)

[0068] As described above, performing the plasma irradiation treatment to a nail using the above-described gas eliminates the need for polishing the nail before the application of the nail coating liquid, and accordingly, the thickness of the nail does not decrease, making it possible to prevent nail cracking. Further, the occurrence of nail cracking can be prevented, because the nail coating liquid can be applied thinly without uneven spots per a single application. In addition, by irradiating plasma to the surface of the underlying layer when the nail coating liquid is applied in layers, a good adhesion between coating liquid layers can be expected, making it possible to reinforce the nail, and to prevent the nail from cracking and scratching.

(Sterilization and Cleaning)

[0069] Performing the plasma irradiation treatment to a nail using the above-described gas makes it possible to eliminate bacteria attached to the surface of the nail. Performing the plasma irradiation makes it possible to decompose and remove dirt such as bacteria or oils and fats on the nail and the fingertip. Therefore, it can be expected to prevent bacterial infection and to prevent the occurrence of green nail and the like. Further, the treatment of nail coating can be performed under good hygiene. Furthermore, due to dry cleaning without using any surfactant or organic solvent, a physical burden is allowed to be smaller than that in the case of using a surfactant or an organic solvent.

(Penetration of Beauty Serum)

[0070] There are cases where a beauty serum is applied to the nail surface before the application of the nail coating liquid thereto or after the removal of the nail coating liquid therefrom. Performing the plasma irradiation treatment to a nail using the above-described gas before the application of the beauty serum makes it possible to promote the penetration of the beauty serum into the nail plate, lateral nail folds, nail grooves and the like. The moisture content of nails and skin is improved, by promoting the penetration of the beauty serum by the plasma irradiation. In other words, the moisture retention effect of the beauty serum is improved. A decrease in the moisture content of nails and skin may be one of the causes for the occurrence of cracks and fissures in the nails and the skin around the nails. That is, it can be expected to alleviate or to prevent the occurrence of cracks and fissures in the nails and the skin around the nails, and the like, by the plasma irradiation. The improvement in the moisture retention effect of the beauty serum can be expected to promote the action of the nail matrix which is a source of the healthy nail.

[0071] In both the cases of applying the nail coating liquid after application of the beauty serum and of applying the nail coating liquid without applying the beauty serum, performing the plasma irradiation treatment using the above-described gas in advance makes it possible to enhance the effects of the beauty serum and the nail coating liquid to support nail care.

[0072] The effects described above work synergistically, making it possible to reduce the treatment time for performing nail coating, and to perform the application of the curable nail coating liquid that serves to maintain healthy nails and achieves a high adhesion, under good hygiene.

[0073] Furthermore, the healthy nail can be grown due to the above-described effects such as the improvement in adhesion, the prevention of nail cracking, the elimination of requirement of degreasing treatment, the improvement in wettability, the sterilization, and the penetration of the beauty serum. This offers a useful value to a person needing nail care. For example, in a sport athlete, a pitcher in baseball as a specific example, nail cracking affects play, and the defective nail leads to an injury. Therefore, the healthy nail can be grown for the purpose of reducing injuries affecting play, such as nail cracking.

[0074] Next, another embodiment of the method of decorating a nail will be described specifically.

[0075] The method of decorating a nail according to the present embodiment is a method of decorating a nail, the method including: [0076] the step of irradiating plasma to a stone; [0077] the step of applying a curable nail coating liquid to the nail; [0078] the step of placing the metal portion of the stone irradiated with the plasma on the curable nail coating liquid applied on the nail; and [0079] the step of curing the curable nail coating liquid, [0080] wherein the gas used for generating the plasma is one or more gases selected from the group consisting of nitrogen gas, oxygen gas and carbon dioxide gas.

[0081] The curable nail coating liquid as used herein refers to a coating liquid which is cured by performing a curing treatment after the application, or by a polymerization reaction, among the liquids to be applied to a fingernail of a human hand or a toenail of a human foot. Such a curable nail coating liquid may be, for example, an energy ray-curable resin which is cured by the irradiation of an energy ray, such as a photocurable resin, particularly, an ultraviolet-curable (UV-curable) resin, and is referred to as gel nail polish. Further, the definition of the curable nail coating liquid includes an acrylic resin, a urethane resin, nitrocellulose and the like, which are used for attaching false nails and for nail sculpturing.

[0082] The step of irradiating plasma to a stone is performed, before the step of applying a curable nail coating liquid to the nail. In the previously described embodiment, plasma is irradiated to the nail to which the curable nail coating liquid is to be applied. In the present embodiment, in contrast, plasma is irradiated to the stone to be adhered to the curable nail coating liquid. The nail and the stone are the same in that they are both the objects to be adhered to the curable nail coating liquid.

[0083] The stone is preferably a rhinestone on which a metal is vapor-deposited, but may be a rhinestone on which a metal is not vapor-deposited. The definition of the stone includes decorative chips and beads similar to the stone. Plasma is irradiated to the portion of the stone to be adhered to the curable nail coating liquid. In cases where the stone is a rhinestone, for example, plasma is irradiated to the metal portion vapor-deposited to the rhinestone. It is also possible to irradiate plasma to the curable nail coating liquid which is applied to the nail and is before or after curing.

[0084] It is preferred to use an irradiation device based on the principle of non-thermal equilibrium plasma, referred to as low-temperature plasma or atmospheric pressure plasma, as the plasma irradiation device for irradiating plasma. In such a plasma irradiation device, plasma is generated by applying a voltage to the gas continuously supplied to the device.

[0085] One type of gas selected from the group consisting of nitrogen gas, oxygen gas and carbon dioxide gas is used, as the gas to be supplied to the plasma irradiation device to generate plasma. These gases may be used singly, or as a mixture of a plurality of gases. For example, it is possible to use a simulated air gas containing about 78% nitrogen gas and about 21% oxygen gas, with the balance being carbon dioxide gas and/or an impurity gas(es). It is also possible to use an air gas.

[0086] Performing the plasma irradiation treatment on a stone using the above-described gas results in the formation of adhesive functional groups, such as hydroxyl and carboxyl groups, on the surface of the stone, thereby improving the adhesion of the stone. Further, performing the plasma irradiation treatment makes it possible to clean the surface of the stone by a dry-cleaning effect. This eliminates the need for a degreasing treatment of wiping the stone with an organic solvent such as acetone, which has been conventionally performed for the purpose of improving the adhesion, making the treatment procedure of nail coating easier.

[0087] By irradiating plasma to the curable nail coating liquid which is applied to the nail and is before or after curing, an improvement in the adhesion of the stone to the curable nail coating liquid can be expected. In addition, in cases where the application and the curing of the curable nail coating liquid are performed repeatedly to decorate a nail, the adhesion of the curable nail coating liquid applied as the top coat to the curable nail coating liquid applied as the base coat is expected to improve.

[Plasma Irradiation Device]

[0088] The plasma irradiation device according to the present embodiment is a device for irradiating plasma to a nail or a stone, suitable for the method of pretreatment for nail coating, or the method of decorating a nail, which has been described above. The plasma irradiation device includes: a plasma generation section; and a gas supply section, wherein the plasma generation section has a porous structure, and the plasma is emitted from each hole. In particular, the plasma irradiation device is preferably a device capable of irradiating plasma to a human fingernail locally, or a device capable of irradiating plasma to the respective fingernails or toenails of one hand or one foot, all at once.

[0089] FIG. 1 shows a configuration diagram of the plasma irradiation device according to the present embodiment. The plasma irradiation device 1 shown in FIG. 1 is an irradiation device based on the principle of non-thermal equilibrium plasma, referred to as low-temperature plasma or atmospheric pressure plasma. The plasma irradiation device 1 includes a plasma generation section 2, and plasma is irradiated from the plasma generation section 2. The plasma generation section 2 has, for example, the shape of a nozzle, and plasma is irradiated locally from one end of the nozzle. Further, the plasma irradiation device 1 includes a gas cylinder(s) 3 for one or more gas types, as a gas supply section(s) for supplying a gas(es) to the plasma generation section 2. Each gas cylinder 3 is connected to the plasma generation section 2 through a gas flow path, and a gas flow meter 4 is provided in the gas flow path. The gas flow meter 4 measures the gas flow rate, and appropriately adjusts the gas flow rate, manually or by automatic control. The gas flow meter 4 shown in the figure includes such a means for controlling the gas flow rate.

[0090] It is preferred to use one gas selected from the group consisting of nitrogen gas, oxygen gas and carbon dioxide gas, as the gas to be supplied to the plasma irradiation device [0091] to generate plasma. These gases may be used singly, or as a mixture of a plurality of gases. For example, it is possible to use a simulated air gas containing about 78% nitrogen gas and about 21% oxygen gas, with the balance being carbon dioxide gas and/or an impurity gas(es). It is also possible to use an air gas.

[0092] To generate plasma, electrodes are provided in the interior of the plasma generation section 2, and atmospheric pressure plasma is generated by supplying an appropriate power to the gas introduced into the plasma generation section 2. A known structure can be used as the structure for generating atmospheric pressure plasma. The plasma irradiation device 1 includes a plasma generation power supply 5, which is connected to the electrodes in the plasma generation section 2 and supplies power. In order to generate plasma appropriately, a control unit 6 is connected to the plasma generation power supply 5. The control unit 6 controls the power requirements of the plasma generation power supply 5. The control unit 6 shown in FIG. 1 is a unit that controls the power requirements. However, as another embodiment, the control unit 6 may be configured to control the gas flow rate in addition to controlling the power requirements, and the control unit 6 may be connected to the gas flow meter 4 in addition to being connected to the plasma generation power supply 5, thereby controlling the gas flow rate.

[0093] FIG. 2A and FIG. 2B show the schematic diagrams of the plasma generation section 2. As shown in FIG. 2A, the plasma generation section 2 has the shape of a nozzle which is approximately cylindrical, and has a gas connector 21 through which the supply of the gas is received, on one end of the cylinder in the axial direction. Irradiation holes 22 for emitting the plasma therethrough are formed on the other end of the cylinder. Further, terminals 23 for receiving the power from the plasma generation power supply 5 are provided between the gas connector 21 and the irradiation holes 22. FIG. 2B shows a view seen from the direction of the line b-b in FIG. 2A. As can be seen from FIG. 2B, the plasma generation section 2 has a porous structure in which a plurality of the irradiation holes 22 are formed on one end surface of the nozzle, and the plasma is emitted from each hole. In the example shown in the figure, the irradiation holes 22 are arranged radially in the direction of the radius, from the center of the circular end surface. However, the arrangement is not limited thereto, and the irradiation holes 22 may be arranged concentrically. The hole diameter of the irradiation holes 22 is preferably from about 0.3 to 3.0 mm, and more preferably from about 0.5 to 1.5 mm, although it varies depending on the number of the irradiation holes 22 formed on the end surface. The irradiation effect is small when the hole diameter is smaller than about 0.3 mm. Even if the hole dimeter is increased to more than about 3.0 mm, on the other hand, it leads not only to a small improvement in the plasma irradiation effect, but also to an increased waste in the amount of gas consumption and in the amount of power consumption.

Examples

[0094] The effects of the present invention will be shown by the following experiments.

(Experiment 1)

[0095] The comparison of the adhesive strength with or without plasma irradiation was carried out as follows, in accordance with the peel strength test (JIS K6854-3). A plurality of L-shaped test pieces made of an acrylic resin plate were prepared. Each test specimen had a length of the longer straight-line portion of the letter L of 60 mm, a length of the shorter straight-line portion thereof of 10 mm, and a thickness of 1 mm. Two test pieces were selected, and plasma was irradiated to the shorter straight-line portion (area: 10 mm.sup.2) of each test piece. A jet-type plasma device manufactured by Plasma Concept Tokyo Inc. was used as the plasma irradiation device. The plasma irradiation was performed under the conditions of a distance from the nozzle to each test piece of 3 mm, a treatment time of from 10 to 60 sec, and a gas flow rate of about 7 L/min. A UV-curable urethane resin <brand name: PREGEL Peelable Base> was applied (adhesive area: 10 mm.sup.2) to the shorter straight-line portions of the two test pieces, and the shorter straight-line portions of the respective test pieces were abutted with each other. Thereafter, ultraviolet light irradiation was carried out using a 165 W DC ultra-high pressure mercury lamp (wavelength: 365 nm), at an irradiation distance of about 30 mm. The irradiation was performed under the conditions of 950 mW/cm.sup.2 and an irradiation time of 4 min.

[0096] The peel strength test was performed after the ultraviolet light irradiation to measure the force required until the UV-curable urethane resin was peeled off, and the measured value was defined as the adhesive strength. The measurement was performed using ORIENTEC RTE-1210 manufactured by Orientec Co., Ltd., under the condition of a test speed of 300 mm/min.

[0097] Such an experiment was carried out for each case in which the type of the gas to be used for the plasma generation is nitrogen, carbon dioxide, air or oxygen. For comparison, an example in which the UV-curable urethane resin was applied and cured without performing the plasma irradiation, was prepared.

[0098] The results of the peel strength test are shown in FIG. 3, as a graph showing the relationship with the gas type.

[0099] In cases where the plasma irradiation was not performed, namely, in the case of the blank test (B in FIG. 3), the adhesive strength was 0.503 kgf. In contrast, the adhesive strength was 0.904 kgf, in the case of performing the plasma irradiation for 30 seconds using nitrogen gas. Accordingly, the adhesive strength was improved by 44% as compared to the blank test. In the case of performing the plasma irradiation for 60 seconds using carbon dioxide gas, the adhesive strength was 0.888 kgf. Accordingly, the adhesive strength was improved by 43% as compared to the blank test. In the case of performing the plasma irradiation for 10 seconds using air, the adhesive strength was 0.631 kgf. Accordingly, the adhesive strength was improved by 20% as compared to the blank test. In the case of performing the plasma irradiation for 10 seconds using oxygen gas, the adhesive strength was 0.611 kgf. Accordingly, the adhesive strength was improved by 18% as compared to the blank test.

[0100] It can be inferred from the relationship of the adhesive strength between the acrylic resin plate and the gel nail polish, that the relationship of the adhesive strength between a nail and the gel nail polish also improves by the plasma irradiation, in the same manner.

(Experiment 2)

[0101] The plasma treatment was performed on the nail plates of subjects, and the retention period from the application to the peeling of a gel nail polish was examined.

[0102] The results thereof are shown in Table 1 and Table 2.

TABLE-US-00001 TABLE 1 CO.sub.2 Gas Subject Gas Flow Treatment Retention No. Hand type rate Time Period 1 Left hand CO.sub.2 6.5 30 s 30 days Right hand CO.sub.2 6.5 60 s 30 days 2 Left hand CO.sub.2 6.5 30 s 90 days Right hand CO.sub.2 6.5 60 s 90 days 3 Left hand CO.sub.2 6.5 60 s 64 days Right hand CO.sub.2 6.5 30 s 65 days

TABLE-US-00002 TABLE 2 N.sub.2 Gas Subject Gas Flow Treatment Retention No. Hand type rate Time Period 1 Right hand N.sub.2 6.5 60 s 21 days 2 Right hand N.sub.2 6.5 60 s 21 days

[0103] In the conventional case in which the plasma treatment is not performed, the retention period from the application to the peeling of the gel nail polish was about two weeks. The present Experiment showed that the retention period was extended by 30 to 90 days by performing the plasma irradiation treatment using carbon dioxide gas, and that the retention period was extended also in the case of using nitrogen gas.

(Experiment 3)

[0104] The comparison of the surface cleaning effect with or without plasma irradiation was performed, by attaching a simulated dirt.

[0105] A plurality of L-shaped test pieces made of an acrylic resin plate were prepared. Each test specimen had a length of the longer straight-line portion of the letter L of 60 mm, a length of the shorter straight-line portion thereof of 10 mm, and a thickness of 1 mm. Two test pieces were selected, and a liquid paraffin emulsion as the simulated dirt was applied to the shorter straight-line portion (area: 10 mm.sup.2) of each test piece. Plasma was irradiated to the portion of each test piece to which the simulated dirt had been applied. A jet-type plasma device manufactured by Plasma Concept Tokyo Inc. was used as the plasma irradiation device. The plasma irradiation was performed under the conditions of a distance from the nozzle to each test piece of 3 mm, a treatment time of from 5 to 60 sec, different gas types (nitrogen, carbon dioxide, air and oxygen), and a gas flow rate of about 7 L/min. A UV-curable urethane resin <brand name: PREGEL Peelable Base> was applied (adhesive area: 10 mm.sup.2) to the shorter straight-line portions of the two test pieces, in the same manner as Experiment 1, and the shorter straight-line portions of the respective test pieces were abutted with each other. Thereafter, ultraviolet light irradiation was carried out using a 165 W DC ultra-high pressure mercury lamp (wavelength: 365 nm), at an irradiation distance of about 30 mm. The irradiation was performed under the conditions of 950 mW/cm.sup.2 and an irradiation time of 4 min.

[0106] The peel strength test was performed after the ultraviolet light irradiation to measure the force required until the UV-curable urethane resin was peeled off, and the measured value was defined as the adhesive strength. The measurement was performed using ORIENTEC RTE-1210 manufactured by Orientec Co., Ltd., under the condition of a test speed of 300 mm/min.

[0107] Such an experiment was carried out multiple times, varying the plasma irradiation time. For comparison, an example in which the UV-curable urethane resin was applied over the simulated dirt and cured, without performing the plasma irradiation, was prepared.

[0108] The results of the peel strength test are shown in FIG. 4, as a graph showing the relationship with the plasma irradiation time.

[0109] In cases where the plasma irradiation was not performed, the adhesive strength was 0.35 kgf. In contrast, the adhesive strength was 0.63 kgf in the case of performing the plasma irradiation for 30 seconds, and the adhesive strength was 0.74 kgf in the case of performing the plasma irradiation for 60 seconds. Accordingly, in cases where the plasma irradiation was performed, the irradiation surface was dry-cleaned by the plasma irradiation, and as a result, the adhesive strength was drastically improved as compared to the case in which the plasma irradiation was not performed.

[0110] It can be inferred from the results of the surface cleaning effect on the acrylic resin plate that the surface cleaning effect on a nail can also be achieved in the same manner.

(Experiment 4)

[0111] The comparison of the surface water contact angle with or without plasma irradiation was performed, by attaching a simulated dirt.

[0112] After applying a liquid paraffin emulsion as the simulated dirt on the surface of an acrylic resin plate, water droplets (4 L of distilled water) were dropped thereon, and the water contact angle was examined by a portable contact angle meter PG-X+. This was taken as the blank test. Next, after applying the liquid paraffin emulsion as the simulated dirt on the surface of an acrylic resin plate, plasma irradiation was performed using a jet-type plasma device manufactured by Plasma Concept Tokyo Inc. under the conditions of a distance from the nozzle to the test piece of 3 mm, a treatment time of 60 sec, different gas types (nitrogen, carbon dioxide, air and oxygen), and a gas flow rate of about 7 L/min. Thereafter, water droplets (4 L of distilled water) were dropped thereon, and the water contact angle was examined by a portable contact angle meter PG-X+.

[0113] Such an experiment was carried out three times for each case in which the type of the gas to be used for the plasma generation is nitrogen, carbon dioxide, air or oxygen, and the mean value was determined for each gas type.

[0114] The results thereof are shown in FIG. 5, as a graph showing the relationship between the gas type and the water contact angle. It can be seen from FIG. 5 that the water contact angle was 72 in the case of the blank test in which the plasma irradiation was not performed, whereas the water contact angle was 53 when the plasma of nitrogen gas was irradiated, the water contact angle was 1 when the plasma of oxygen gas was irradiated, the water contact angle was 41 when the plasma of air was irradiated, and the water contact angle was 24 when the plasma of carbon dioxide gas was irradiated.

[0115] It can be inferred from the results of the water contact angle of the acrylic resin plate that the water contact angle of a nail also deceases, in the same manner.

(Experiment 5)

[0116] The bactericidal effect on nails with or without plasma irradiation was examined as follows.

[0117] On the surface of one nail, of a plurality of nails of one hand, plasma irradiation was performed using a jet-type plasma device manufactured by Plasma Concept Tokyo Inc. under the conditions of a distance from the nozzle to the nail of 3 mm, a treatment time of 30 sec, a gas type of oxygen, and a gas flow rate of about 7 L/min.

[0118] The plasma-treated nail and a nail without the plasma treatment, of the nails of one hand, were each wiped with a sterile swab, to collect bacteria. Each cotton swab after the collection was dipped in saline (0.9%) and stirred to prepare a suspension. One g of each diluted sample was dropped on an agar culture medium, and evenly spread using a spreader. After culturing (at 35 C. for 48 hours) in a thermostatic chamber, the number of colonies was counted.

[0119] As a result, the number of colonies was 11 for the nail without plasma irradiation, whereas the number of colonies was 1 for the plasma-irradiated nail.

(Experiment 6)

[0120] The penetration effect of a beauty serum into nails with or without plasma irradiation was examined as follows.

[0121] Nails were placed in an airtight container (desiccator) containing silica gel, and the container was left to stand 24 hours. Next, distilled water was dropped using a syringe, on each of a plasma-treated nail and a nail without the plasma treatment, and water on each nail surface was wiped off after one minute. Subsequently, the moisture content was measured using a moisture meter (a trace moisture measuring device, AQ-2200, manufactured by Hiranuma Sangyo Co., Ltd.), with a vaporizer set to a temperature of 100 C.

[0122] As a result, the nail without the plasma treatment had a moisture content of 20.4%, whereas the plasma-treated nail had a moisture content of 23.7%, revealing that the penetration effect of water was higher in the plasma-treated nail. It can be inferred from the penetration effect of distilled water described above, that such a penetration effect can be obtained also in the case of a beauty serum.

(Experiment 7)

[0123] The comparison of the adhesive strength of stones with or without plasma irradiation was carried out as follows, in accordance with the tensile shear adhesive strength test for rigid adherends (JIS K6850, 1999).

[0124] A plurality of test pieces (each having a size of 10 mm60 mm, and a thickness of 1 mm) made of an acrylic resin plate, an aluminum plate and a brass plate were prepared. A combination of an acrylic resin test piece and an aluminum test piece, or a combination of an acrylic resin test piece and a brass test piece, was prepared, and plasma was irradiated to the vicinity of the short side of each test piece. A jet-type plasma device manufactured by Plasma Concept Tokyo Inc. was used as the plasma irradiation device. The plasma irradiation was performed under the conditions of a distance from the nozzle to each test piece of 3 mm, a treatment time of from 10 to 60 sec, and a gas flow rate of about 7 L/min. A UV-curable urethane resin <brand name: PREGEL Peelable Base> was applied to the vicinity of the short sides irradiated with the plasma, of the two test pieces, and then the short sides were layered one on another (adhesive area: 10 mm.sup.2). Thereafter, ultraviolet light irradiation was carried out using a 165 W DC ultra-high pressure mercury lamp (wavelength: 365 nm), at an irradiation distance of about 30 mm. The irradiation was performed under the conditions of 950 mW/cm.sup.2 and an irradiation time of 4 min.

[0125] The tensile shear adhesive strength test was performed after the ultraviolet light irradiation to measure the force required until the two test pieces adhered with the UV-curable urethane resin were broken by tensile shear, and the measured value was defined as the adhesive strength. The measurement was performed using ORIENTEC RTE-1210 manufactured by Orientec Co., Ltd., under the condition of a test speed of 300 mm/min.

[0126] Such an experiment was carried out for each case in which the type of the gas to be used for the plasma generation is nitrogen, carbon dioxide, air or oxygen. For comparison, an example in which the UV-curable urethane resin was applied and cured without performing the plasma irradiation, was prepared.

[0127] The results of the tensile shear adhesive strength test of the test piece which is a combination of the acrylic plate and the aluminum plate are shown in FIG. 6, as a graph showing the relationship with the gas type.

[0128] In cases where the plasma irradiation was not performed, namely, in the case of the blank test, the adhesive strength was 22.77 kgf. In contrast, the adhesive strength was 25.21 kgf in the case of performing the plasma irradiation for 60 seconds using oxygen gas. Accordingly, the adhesive strength was improved by 10% as compared to the blank test. In the case of performing the plasma irradiation for 60 seconds using air, the adhesive strength was 44.41 kgf. Accordingly, the adhesive strength was improved by 49% as compared to the blank test. In the case of performing the plasma irradiation for 60 seconds using nitrogen gas, the adhesive strength was 54.94 kgf. Accordingly, the adhesive strength was improved by 59% as compared to the blank test. In the case of performing the plasma irradiation for 60 seconds using carbon dioxide gas, the adhesive strength was 52.89 kgf. Accordingly, the adhesive strength was improved by 57% as compared to the blank test. In the case of performing the plasma irradiation for 30 seconds using oxygen gas, the adhesive strength was 46.87 kgf. Accordingly, the adhesive strength was improved by 51% as compared to the blank test. In the case of performing the plasma irradiation for 30 seconds using air, the adhesive strength was 47.59 kgf. Accordingly, the adhesive strength was improved by 52% as compared to the blank test. In the case of performing the plasma irradiation for 30 seconds using nitrogen gas, the adhesive strength was 48.37 kgf. Accordingly, the adhesive strength was improved by 53% as compared to the blank test. In the case of performing the plasma irradiation for 30 seconds using carbon dioxide gas, the adhesive strength was 39.79 kgf. Accordingly, the adhesive strength was improved by 43% as compared to the blank test.

[0129] The results of the tensile shear adhesive strength test of the test piece which is a combination of the acrylic plate and the brass plate are shown in FIG. 7, as a graph showing the relationship with the gas type.

[0130] In cases where the plasma irradiation was not performed, namely, in the case of the blank test, the adhesive strength was 40.75 kgf. In contrast, the adhesive strength was 53.77 kgf in the case of performing the plasma irradiation for 60 seconds using oxygen gas. Accordingly, the adhesive strength was improved by 24% as compared to the blank test. In the case of performing the plasma irradiation for 60 seconds using nitrogen gas, the adhesive strength was 53.77 kgf. Accordingly, the adhesive strength was improved by 24% as compared to the blank test. In the case of performing the plasma irradiation for 60 seconds using carbon dioxide gas, the adhesive strength was 54.33 kgf. Accordingly, the adhesive strength was improved by 25% as compared to the blank test. In the case of performing the plasma irradiation for 30 seconds using oxygen gas, the adhesive strength was 45.79 kgf. Accordingly, the adhesive strength was improved by 11% as compared to the blank test. In the case of performing the plasma irradiation for 30 seconds using air, the adhesive strength was 51.94 kgf. Accordingly, the adhesive strength was improved by 22% as compared to the blank test. In the case of performing the plasma irradiation for 30 seconds using nitrogen gas, the adhesive strength was 51.66 kgf. Accordingly, the adhesive strength was improved by 21% as compared to the blank test. In the case of performing the plasma irradiation for 30 seconds using carbon dioxide gas, the adhesive strength was 50.33 kgf. Accordingly, the adhesive strength was improved by 19% as compared to the blank test.

[0131] Both aluminum and brass are respectively a metal and an alloy each used as the metal portion of a rhinestone, and it can be seen from the test results described above that the adhesive strength between the gel nail polish and the rhinestone was improved by the plasma irradiation treatment.

(Experiment 8)

[0132] The comparisons of the water contact angle, the surface free energy and the hydrogen bond energy with or without plasma irradiation were carried out, using a goat skin as a simulated skin substituting a human skin.

[0133] A goat skin having a thickness after tanning of 0.3 mm was cut into rectangles with a size of 1 cm10 cm, to prepare a plurality of samples. Plasma was irradiated on one surface of each sample. The plasma irradiation device used for the plasma irradiation was a jet-type plasma device manufactured by Plasma Concept Tokyo Inc. The plasma irradiation was performed under the conditions of a distance from the nozzle to each sample of 3 mm, a treatment time of 10 seconds, a gas type of carbon dioxide, and a gas flow rate of about 8 L/min.

[0134] Each of water, diiodomethane and bromonaphthalene was dropped on the surface of the plasma-irradiated sample and on the sample not irradiated with the plasma, as a control experiment, in an amount of 1.5 L, and the contact angle in the case of water, the contact angle in the case of diiodomethane and the contact angle in the case of bromonaphthalene were examined by a portable contact angle meter DropMaster DM-500. Each contact angle was measured for one second. Based on these contact angles, the surface free energy and the hydrogen bond energy of the plasma-irradiated sample, and of the sample not irradiated with the plasma, as a control experiment, were calculated. The method of calculating the surface free energy and the hydrogen bond energy was a theoretical formula for the surface free energy (Kitazaki-Hata theory).

[0135] The measured water contact angle of the sample not irradiated with the plasma, as a control experiment, was 38.4, whereas that of the plasma-irradiated sample was 0.1, which was about a 99% decrease.

[0136] Further, the surface free energy of the sample not irradiated with the plasma, as a control experiment was 63.6 mJ/m, whereas that of the plasma-irradiated sample was 76.8 mJ/m. The hydrogen bond energy of the sample not irradiated with the plasma, as a control experiment was 18.2 mJ/m, whereas that of the plasma-irradiated sample was 28.9 mJ/m.

[0137] It can be seen from these experiment results that the surface of the goat skin was hydrophilized by the plasma treatment, and the surface free energy was increased by about 20%, and the hydrogen bond energy was increased by about 59%. Further, it was possible to say that the surface of the goat skin was chemically activated by the plasma treatment, thereby hydrophilizing the surface.

(Experiment 9)

[0138] The comparisons of the water contact angle, the surface free energy and the hydrogen bond energy with or without plasma irradiation were carried out, using the mantle of a Japanese common squid as a simulated nail substituting a human nail.

[0139] The mantle of a Japanese common squid was cut into rectangles with a size of 1 cm10 cm, to prepare a plurality of samples. Plasma was irradiated on one surface of each Sample. The plasma irradiation device used for the plasma irradiation was a jet-type plasma device manufactured by Plasma Concept Tokyo Inc. The plasma irradiation was performed under the conditions of a distance from the nozzle to each sample of 3 mm, a treatment time of 10 seconds, a gas type of carbon dioxide, and a gas flow rate of about 8 L/min.

[0140] Each of water, diiodomethane and bromonaphthalene was dropped on the surface of the plasma-irradiated sample and on the sample not irradiated with the plasma, as a control experiment, in an amount of 1.5 L, and the contact angle in the case of water, the contact angle in the case of diiodomethane and the contact angle in the case of bromonaphthalene were examined by a portable contact angle meter DropMaster DM-500. Each contact angle was measured for one second.

[0141] It was not possible to measure the contact angle of water, because the water penetrated into the interior of the mantle from the surface. The contact angle of diiodomethane on the sample not irradiated with the plasma, as a control experiment, was 92.3, whereas that on the plasma-irradiated sample was 51.2. Further, the contact angle of bromonaphthalene on the sample not irradiated with the plasma, as a control experiment, was 22.7, whereas that on the plasma-irradiated sample was 8.1.

[0142] It can be seen from these experiment results that the contact angle of diiodomethane was decreased by about 45% as compared to the control experiment, and the contact angle of bromonaphthalene was decreased by about 64% as compared to the control experiment, by the plasma treatment, showing that the surface of the mantle of the Japanese common squid was chemically modified by the plasma treatment. Since both diiodomethane and bromonaphthalene are non-polar solvents, it was possible to say that the wettability of a non-polar substance, such as an oil, was improved by the plasma treatment.

(Experiment 10)

[0143] The comparison of the penetration of a moisture oil with or without plasma irradiation was carried out, using a goat skin as a simulated skin substituting a human skin.

[0144] A goat skin having a thickness after tanning of 0.3 mm was cut into squares with a size of 3 cm3 cm, and left to stand in a constant temperature and humidity chamber controlled to 25 C. and 50% RH for 5 hours, to prepare a plurality of samples. Plasma was irradiated on one surface of each Sample. The plasma irradiation device used for the plasma irradiation was a jet-type plasma device manufactured by Plasma Concept Tokyo Inc. The plasma irradiation was performed under the conditions of a distance from the nozzle to each sample of 3 mm, a treatment time of 30 seconds, a gas type of carbon dioxide, and a gas flow rate of about 8 L/min.

[0145] A quantity of 0.02 g of Cuticle Care Oil (including a natural vegetable oil and a horse oil) (GROWN CARE) as a moisture oil was dropped using a syringe, on the surface of the plasma-irradiated sample and on the sample not irradiated with the plasma, as a control experiment, and an image of the region on which the oil had been dropped, of each sample, was captured one minute after the dropping. Each captured image was binarized using image analysis software, to measure the area of the region where the oil had penetrated.

[0146] The measured area of the oil-penetrated region of the sample not irradiated with the plasma, as a control experiment, was 101.1 mm.sup.2, whereas that of the plasma-irradiated sample was 114.7 mm.sup.2, showing about a 13% improvement.

[0147] Further, the moisture oil remained on the surface of the goat skin even one minute after the dropping of the oil, in the sample not irradiated with the plasma, as a control experiment. In the plasma-irradiated sample, in contrast, the moisture oil had penetrated into the skin immediately after the dropping, and no oil remined on the surface of the goat skin.

[0148] Based on the results of these experiment results, it was possible to say that the penetration of the moisture oil into the goat skin was improved by the plasma treatment.

(Experiment 11)

[0149] The comparison of the moisture retention of a beauty serum with or without plasma irradiation was carried out.

[0150] The moisture content of the surfaces of the lateral nail folds of the nail of the index finger of one subject was measured with a multifunctional skin checker (Peipai skin moisture checker PM-907) from Shenzhen Jiatu Co., Ltd.

[0151] The vicinities of the measured lateral nail folds and lateral nail plate edges around the lateral nail folds of the plurality of nails were irradiated with plasma using a jet-type plasma device manufactured by Plasma Concept Tokyo Inc. under the conditions of a distance from the nozzle to each nail of 3 mm, a treatment time of 30 sec, a gas type (carbon dioxide), and a gas flow rate of about 7 L/min. The nails of the hands of the subject also included nails that were not irradiated with plasma.

[0152] DHC Medicinal Mild Lotion from DHC Corporation was dripped as a lotion on the lateral nail folds along the lateral nail plate edges of each of the nails of the subject, irradiated with and without plasma, and left to stand for 30 seconds to allow the lotion to agree with the skin.

[0153] The moisture contents of three points on the surface of the lateral nail folds of the nail of each index finger of the subject after the dripping of the lotion were measured with the multifunctional skin checker (Peipai skin moisture checker PM-907) which was the same skin moisture checker as before the dripping.

[0154] As a result of the measurement, the average value of the moisture contents of the three points on the surface of the lateral nail folds before the plasma irradiation and the dripping of the lotion was 23%. The average value of the moisture contents of the three points on the surface of the lateral nail folds after the dripping of the lotion without the plasma irradiation was 51%. The average value of the moisture contents of the three points on the surface of the lateral nail folds after the plasma irradiation and the dripping of the lotion was 65%. The results revealed that the moisture content in the case of the plasma irradiation and the dripping of the lotion was 1.27 times, as a value obtained by dividing 65 by 51, the moisture content in the case of the dripping of the lotion without the plasma irradiation.

REFERENCE SIGNS LIST

[0155] 1 Plasma irradiation device [0156] 2 Plasma generation section [0157] 3 Gas cylinder [0158] 4 Gas flow meter [0159] 5 Plasma generation power supply [0160] 6 Control unit [0161] 21 Gas connector [0162] 22 Irradiation hole [0163] 23 Terminal