JP7828833B2 - Film-forming composition - Google Patents

Description

This invention relates to a film-forming composition, a film-producing method, and a film-forming kit.

A method for forming a coating by electrostatic spraying is known. For example, Patent Document 1 describes forming a coating with good adhesion to the skin and transparency by directly electrostatically spraying a composition containing a volatile substance, a water-insoluble polymer, and an adhesive polymer onto the skin.

Japanese Patent Publication No. 2018-177802

In areas where a film is formed, such as the skin, a film that adheres well to the skin is desired.
While using water-soluble polymer compounds in the film-forming composition improves adhesion to the skin, the film can sometimes absorb moisture and dissolve. Furthermore, this dissolution of the film tends to occur particularly under high temperature or high humidity conditions, indicating room for improvement in film-forming compositions for electrostatic spraying.

The object of this invention is a coating-forming composition, a coating manufacturing method, and a coating-forming kit for forming a coating that adheres well even under conditions such as high temperature or high humidity.

A coating-forming composition according to one embodiment of the present invention is for forming a coating consisting of a deposit containing fibers by electrostatic spraying directly or indirectly onto a target area for coating.
The above-mentioned film-forming composition comprises a first polymer and a second polymer.
The first polymer described above has a moisture absorption of 1% or less under high temperature and high humidity conditions (left standing for 24 hours at 40°C and 90% RH).
The second polymer described above has a moisture absorption of 5% to 29% under high temperature and high humidity conditions (left standing for 24 hours at 40°C and 90% RH).

A coating manufacturing method according to one embodiment of the present invention is a method for forming a coating on a target area.
The above-described method for manufacturing a coating comprises a coating formation step.
In the above coating formation process, a coating composition is electrostatically sprayed directly or indirectly onto the area to be coated to form a coating consisting of a deposit containing fibers.
The above-mentioned film-forming composition comprises a first polymer and a second polymer.
The first polymer described above has a moisture absorption of 1% or less under high temperature and high humidity conditions (left standing for 24 hours at 40°C and 90% RH).
The second polymer described above has a moisture absorption of 5% to 29% under high temperature and high humidity conditions (left standing for 24 hours at 40°C and 90% RH).

A coating-forming kit according to one embodiment of the present invention comprises the above-mentioned coating-forming composition and a formulation.
The above-mentioned formulation is applied to the skin before or after film formation using the above-mentioned film-forming composition.

According to the film-forming composition, film-producing method, and film-forming kit of the present invention, a well-adhering film can be obtained even under conditions of high temperature or high humidity.

This is a schematic diagram showing the configuration of an electrostatic spray device preferably used in the present invention. This is a schematic diagram showing how a film is formed on the skin by electrostatic spraying using the electrostatic spraying device described above. This is a schematic diagram of a coating-forming kit according to one embodiment of the present invention. This graph shows the relationship between the proportion of the second polymer in the film-forming composition and the overall average usability score of the film after storage at high temperature and humidity.

This invention relates to improving the adhesion of a coating formed on a target area by electrostatic spraying.
The present invention will be described below based on its preferred embodiments.

In this invention, a coating is formed by directly or indirectly applying a coating-forming composition containing predetermined components to the target area via electrostatic spraying.
In this invention, by configuring the film-forming composition to contain predetermined components, the adhesion of the film to the target area for film formation can be improved.
By using the electrostatic spraying method, it is possible to form a coating of deposited fibers (so-called nanofibers) with a fiber diameter on the order of nanometers.
The target site for film formation is typically human skin, but it may also be human teeth, gums, skin, teeth, gums of non-human mammals, or plant surfaces such as branches and leaves. The following explanation will use an example of film formation on human skin.
Furthermore, while the following explanation describes an example of directly forming a film on human skin by electrostatic spraying, it is also possible to form a film on the skin by first forming a film on an applicator, which is an intermediate film-forming object, by electrostatic spraying, and then transferring the film to the skin. This method of forming a film on an intermediate film-forming object and then transferring the film to the film-forming area is referred to as "indirectly forming a film on the film-forming area by electrostatic spraying."
In this specification, the area on which a coating is ultimately formed is referred to as the "coating target area." Therefore, when a coating is formed on an applicator and then transferred to the skin, the coating target area is the skin.
Furthermore, in this specification, "user" means the person whose skin is to which the film is applied. And "assistant" means the person who performs at least part of the application of the formulation and the formation of the film on behalf of the user.

The film formed using the film-forming composition of the present invention can be suitably used for wounds and abnormal conditions from the skin surface to the basal layer of the epidermis. Specifically, it can be suitably used for improving skin conditions and wound healing, with the aim of promoting tissue regeneration, promoting basement membrane regeneration, activating epidermal cell proliferation, epidermal cell epithelialization (promoting keratinization), improving barrier function, improving moisture content, improving scaling, suppressing scab formation, suppressing inflammation, and suppressing post-inflammatory pigmentation. The film is formed on wound healing target sites such as human skin with symptoms such as scaling and inflammation, or damaged skin after laser treatment, and protects the skin. By forming a film on the skin, the skin can be protected from external stimuli and foreign substances by the film, and it is also possible to efficiently heal symptoms such as scaling and inflammation, and damage after laser treatment.
The film-forming composition of the present invention is typically used in conjunction with a formulation (described later). By using it in combination with a formulation, the capillary force of the film's fibers can be utilized to hold the formulation between the fibers. This creates a situation in which the formulation acts efficiently and effectively on the skin while protecting it.
The formulation can be applied to the skin before or after film formation by electrostatic spraying. The following description provides an example of applying the formulation before film formation.
Furthermore, the coating may be used alone, without being used in combination with the formulation. By forming a coating on the skin, the skin can be protected from external stimuli and foreign substances.
The details are explained below.

<Film-forming composition>
The inventors focused on the moisture absorption of polymers used in film-forming compositions under high-temperature and high-humidity environments. They discovered that by combining a first polymer with relatively low moisture absorption under high-temperature and high-humidity environments and a second polymer with relatively high moisture absorption under high-temperature and high-humidity environments to form a film-forming composition, it is possible to form a film that is less affected by the usage environment and adheres well using this film-forming composition.
The details are explained below.

Here, "good adhesion" refers to a state where the user feels that the formed film adheres firmly to the skin (the area where the film is formed), and when they touch the skin with the film formed on it using their fingertips or palm, they feel a uniform, almost adhesive adhesion across the entire body part (fingertips or palm) being touched.

The film-forming composition of the present invention comprises a first polymer having a moisture absorption of 1% or less in a high-temperature, high-humidity environment, a second polymer having a moisture absorption of more than 1% and 40% or less in a high-temperature, high-humidity environment, and a solvent. The solvent evaporates during the film-forming process, and the film is composed of the first polymer and the second polymer. Although the film-forming composition consists of the first polymer, the second polymer, and the solvent, it may also contain other components.
The first polymer is the core of the coating.
The second polymer contributes to modifying the surface of the fibers that make up the coating.

[Method for measuring the moisture absorption of polymers in high-temperature and high-humidity environments]
In this specification, the moisture absorption of polymers under high-temperature and high-humidity conditions is measured using the measurement method described below.
One g of the polymer to be measured is placed in an incubator at 40°C and 90% RH (high temperature and high humidity environment) for 24 hours, thereby subjecting the polymer to a high temperature and high humidity load.
The initial weight of the polymer to be measured is determined by first leaving it standing for 1 minute at 25°C and 50% RH before applying the high temperature and humidity load. The weight of the polymer to be measured after the high temperature and humidity load is determined by first leaving it standing for 1 minute at 25°C and 50% RH immediately after removing it from the incubator. The moisture absorption of the polymer to be measured is then calculated using the following formula (1).
Moisture absorption = (Weight after high temperature and humidity load - Initial weight) / Initial weight × 100 (%) ... (1)
In this specification, unless otherwise specified, "humidity absorption" means "humidity absorption under high temperature and high humidity conditions."

[First Polymer]
From the viewpoint of creating a coating that is less affected by the usage environment and can easily maintain good quality, the first polymer has a moisture absorption of 1% or less, more preferably 0.9% or less. Also, from the same viewpoint, it is preferable that the moisture absorption is 0.1% or more, more preferably 0.6% or more.

In addition to the aforementioned hygroscopic properties, the properties of the first polymer can also be explained from the perspective of water insolubility. Specifically, it is preferable that the first polymer is a polymer that, when 1 g of polymer is weighed and immersed in 10 g of deionized water under conditions of 1 atmosphere and 23°C, more than 0.5 g of the immersed polymer remains undissolved after 24 hours.

More specifically, from the viewpoint of creating a coating that easily maintains good quality, it is more preferable to use one or more polymers selected from polyvinyl butyral resin, polyurethane resin, and polylactic acid as the first polymer, and even more preferable to use polyvinyl butyral resin.

[Second Polymer]
The second polymer has good compatibility and, from the viewpoint of reducing wrinkles and air bubbles in the film formed on the skin, a moisture absorption of more than 5%, preferably 6.5% or more, and from the same viewpoint and from the viewpoint of suppressing nozzle clogging during electrostatic spraying, 29% or less, preferably 28.4% or less. The moisture absorption of the second polymer is more than 5% and 29% or less, preferably 6.5% or more and 28.4% or less.

As the second polymer, it can contain one or more polymers selected from polyvinylpyrrolidone, a copolymer of polyvinylpyrrolidone, polyalkylene glycol, and a silicone structure-containing copolymer. From the viewpoint of improving the compatibility of the film formed on the skin, it is preferable to use a polymer that contains one or more polymers selected from polyvinylpyrrolidone copolymer and polyalkylene glycol.
Furthermore, the content ratio of one or more polymers selected from polyvinylpyrrolidone, polyvinylpyrrolidone copolymers, polyalkylene glycols, and silicone structure-containing copolymers relative to the total amount of the second polymer is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 95% by mass or more, from the viewpoint of improving the adherence of the film formed on the skin.

Examples of polyvinylpyrrolidone copolymers include vinyl acetate/vinylpyrrolidone copolymer, vinylpyrrolidone/dimethylaminoethyl methacrylate copolymer with diethyl sulfate, and vinylcaprolactam/vinylpyrrolidone/dimethylaminopropylmethacrylamide/methacryloylaminopropyllauryldimonium chloride copolymer. From the viewpoint of improving the adhesion of the film formed on the skin, vinyl acetate/vinylpyrrolidone copolymer is preferred.

The vinyl acetate/vinylpyrrolidone copolymer is a copolymer obtained by the polymerization of vinyl acetate and vinylpyrrolidone, and has structures based on vinyl acetate and vinylpyrrolidone within the polymer. Here, if the structure based on vinyl acetate is denoted as VP and the structure based on vinylpyrrolidone as VA, the ratio of VP to VA (VP:VA) in the vinyl acetate/vinylpyrrolidone copolymer in this invention is preferably in the range of VP:VA = 20:80 to 80:20, and more preferably in the range of VP:VA = 25:75 to 65:35, from the viewpoint of improving the adhesion of the film formed on the skin. Note that the ratio in this section refers to the molar ratio, and the amount of residual monomer relative to the initial monomer composition can be calculated by gas chromatography.

As a more specific example, the following commercially available products can be used as polyvinylpyrrolidone and its copolymers.
Product Name: PVA/VA E735 (Ashland Japan Co., Ltd.)
Product Name: PLASDONE® S630 (Ashland Japan Co., Ltd.)
Product Name: PVA/VA E535 (Ashland Japan Co., Ltd.)
Product Name: PVA/VA E335 (Ashland Japan Co., Ltd.)
Product name: Gafquat® 734 (Ashland Japan Co., Ltd.)
Product name: Aquastyle 300N (Ashland Japan Co., Ltd.)

Examples of polyalkylene glycols include polyethylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, and polyoxyethylene polyoxypropylene glycol. From the viewpoint of ensuring good adhesion of the film formed on the skin, polyoxyethylene polyoxypropylene glycol is preferred.

The average number of moles of ethylene oxide added to polyoxyethylene polyoxypropylene glycol is preferably 5 to 200, more preferably 10 to 30, from the viewpoint of good compatibility and reduction of wrinkles and air bubbles in the film formed on the skin. Similarly, the average number of moles of propylene oxide added is preferably 5 to 100, more preferably 10 to 30, from the same viewpoint. The average number of moles of ethylene oxide added can be calculated, for example, by the method described in "JIS K 0070-1992 7.1 Neutralization titration method," and the average number of moles of propylene oxide added can be determined using ^1H -NMR.

As a more specific example, the following commercially available products can be used as polyethylene glycol adducts.
Product name: Pronon (registered trademark) 124P (NOF Co., Ltd.)

As a more specific example, the following commercially available products can be used as silicone structure-containing copolymers.
Product name: Silicone KF-6011 (Shin-Etsu Chemical Co., Ltd.)

[solvent]
The solvent contains one or more selected from monohydric alcohols and ketones. Monohydric alcohols and ketones are volatile substances. From the viewpoint of ensuring good adhesion of the formed film, the solvent preferably contains one or more selected from ethanol, isopropyl alcohol, and butyl alcohol as monohydric alcohols, and more preferably contains ethanol. From a similar viewpoint, the solvent preferably contains acetone as a ketone. The type of solvent used can be appropriately determined depending on the type of first polymer, and a solubilizer for the first polymer can be used as the solvent. For example, when polyvinyl butyral resin or polyurethane resin is used as the first polymer, ethanol can be used as the solvent. When polylactic acid is used as the first polymer, acetone can be used as the solvent.

When ethanol is used as the solvent, the ethanol content in the solvent is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, relative to the total amount of the solvent, from the viewpoint of high volatility and compatibility with the formed film. Furthermore, it is preferably 100% by mass or less, and more preferably 95% by mass. In addition, the ethanol content in the solvent is preferably 50% by mass or more and 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, and even more preferably 80% by mass or more and 95% by mass or less, relative to the total amount of the solvent.

Furthermore, the solvent may contain water.
In the examples described later, we give an example in which 99-degree synthetic alcohol (Nippon Synthetic Alcohol Co., Ltd.), which is an anhydrous alcohol with an ethanol content of 99.5% by volume or more, is used as the solvent. However, since ethanol easily absorbs moisture from the air, the ethanol content will not be 100% by volume. Therefore, when using the above-mentioned 99-degree synthetic alcohol as a solvent, the solvent will contain moisture.
Furthermore, in the description of the ethanol content in the solvent mentioned above, ethanol refers to the anhydrous alcohol, 99% synthetic alcohol (Nippon Synthetic Alcohol Co., Ltd.).

The water content in the solvent is preferably 0.2% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.4% by mass or more, relative to the total amount of the solvent, from the viewpoint of compatibility with the formed film. Furthermore, it is preferably 10% by mass or less, and even more preferably 5% by mass or less. The water content in the solvent is preferably 0.2% by mass or more and 10% by mass or less, more preferably 0.3% by mass or more and 10% by mass or less, and even more preferably 0.4% by mass or more and 5% by mass or less, relative to the total amount of the solvent.

When forming a nanofiber coating using electrostatic spraying, the solvent is evaporated to form the nanofibers, so it is preferable that the main component of the solvent be a volatile substance.
The volatile substance preferably has a vapor pressure of 0.01 kPa or more and 106.66 kPa or less at 20°C, more preferably 0.13 kPa or more and 66.66 kPa or less, even more preferably 0.67 kPa or more and 40.00 kPa or less, and even more preferably 1.33 kPa or more and 40.00 kPa or less.

In a film formed using the film-forming composition of the present invention, the content of the first polymer is preferably 40% by mass or more, more preferably 48% by mass or more, even more preferably 54% by mass or more, even more preferably 60% by mass or more, and even more preferably 64% by mass or more, from the viewpoint of good compatibility and reduction of wrinkles and air bubbles in the film formed on the skin. Similarly, from the same viewpoint, it is preferably 98% by mass or less, more preferably 89% by mass or less, even more preferably 85% by mass or less, even more preferably 82% by mass or less, and even more preferably 79% by mass or less. Furthermore, the content of the first polymer is preferably 40% by mass or more and 98% by mass or less, more preferably 48% by mass or more and 89% by mass or less, even more preferably 54% by mass or more and 85% by mass or less, even more preferably 60% by mass or more and 82% by mass or less, and even more preferably 64% by mass or more and 79% by mass or less.

In a film formed using the film-forming composition of the present invention, the content of the second polymer is preferably 2% by mass or more, more preferably 12% by mass or more, even more preferably 15% by mass or more, even more preferably 18% by mass or more, and even more preferably 21% by mass or more, from the viewpoint of good compatibility and reduction of wrinkles and air bubbles in the film formed on the skin. Similarly, from the same viewpoint, it is preferably 60% by mass or less, more preferably 52% by mass or less, even more preferably 46% by mass or less, even more preferably 40% by mass or less, and even more preferably 34% by mass or less. Furthermore, the content of the second polymer is preferably 2% by mass or more and 60% by mass or less, more preferably 12% by mass or more and 52% by mass or less, even more preferably 15% by mass or more and 46% by mass or less, even more preferably 18% by mass or more and 40% by mass or less, and even more preferably 21% by mass or more and 34% by mass or less.

[Mass ratio (blending ratio) of the first polymer and the second polymer in the film-forming composition]
From the viewpoint of forming a coating that is less affected by the usage environment and blends well, it is preferable to define the blending ratio of the first polymer, which has relatively low moisture absorption in high-temperature and high-humidity environments, and the second polymer, which has relatively high moisture absorption, as follows.
In the film-forming composition, the proportion of the second polymer to the total polymer of the first polymer and the second polymer combined (hereinafter sometimes simply referred to as "the proportion of the second polymer") is preferably 0.05 or more, more preferably 0.11 or more, even more preferably 0.15 or more, even more preferably 0.18 or more, even more preferably 0.21 or more, and from the viewpoint of good compatibility and reducing wrinkles and air bubbles in the film formed on the skin, it is also preferably 0.60 or less, more preferably 0.52 or less, even more preferably 0.46 or less, even more preferably 0.40 or less, even more preferably 0.38 or less, and even more preferably 0.34 or less. Furthermore, the proportion of the second polymer to the total polymer when the first polymer and the second polymer are combined is preferably 0.05 to 0.60, more preferably 0.11 to 0.52, even more preferably 0.15 to 0.46, even more preferably 0.18 to 0.40, even more preferably 0.21 to 0.38, and even more preferably 0.21 to 0.34.
The proportion of the second polymer can be determined by the following formula (2), where M1 is the mass (content) of the first polymer in the film-forming composition and M2 is the mass (content) of the second polymer.
The proportion of the second polymer = M2 / (M1 + M2) ... (2)

In this embodiment, the film-forming composition is composed of a mixture of a first polymer, a second polymer, and a solvent. The solvent evaporates during the film-forming process, and the film is composed of the first and second polymers.

The film-forming composition of the present invention is composed of a first polymer with relatively low moisture absorption and a second polymer with relatively high moisture absorption in the above-mentioned proportions. This improves the moisture resistance of the film formed using the film-forming composition. For example, even in high-temperature and high-humidity usage environments such as bathrooms and changing rooms, the film formed on the skin is less likely to absorb moisture, dissolve, and become wrinkled, resulting in a film with a stable shape and maintained quality.
Furthermore, when the area to be covered is a wound on the skin, the cover is in a state where it easily absorbs exudate, and the humidity at the area where the cover is formed is high. However, by improving the moisture resistance of the cover, the phenomenon of the cover dissolving due to exudate is less likely to occur, and the quality of the cover can be stably maintained.
Furthermore, when the target area for film formation is the oral cavity, such as teeth and gums, which are high-humidity environments, the film is in a state where it easily absorbs saliva. However, by improving the moisture resistance of the film, the phenomenon of the film dissolving due to saliva is less likely to occur, and the quality of the film can be stably maintained.
Thus, the film formed using the film-forming composition of the present invention maintains its quality and stable film shape even in high-temperature or high-humidity environments.

In addition, by including a second polymer, the adhesion of the coating to the skin can be improved, resulting in a coating that maintains good adhesion even in high-temperature or high-humidity environments, and can maintain good compatibility with the skin over time, making it less susceptible to environmental influences.
Furthermore, because it adheres well to the skin, it is less likely for the film to wrinkle or for air bubbles to be trapped, resulting in a natural appearance where the boundary between skin with and without the film is indistinguishable, making the presence of the film almost imperceptible.
Furthermore, the coating formed using the coating-forming composition of the present invention adheres firmly to the skin, even on uneven skin surfaces such as wounds, by conforming to the irregularities of the skin, thus reducing the likelihood of sensory discomfort on the skin.

Furthermore, the inclusion of the second polymer improves the compatibility between the coating and the formulation, ensuring that the formulation is present throughout the entire coating formed on the skin. This allows for good contact between the formulation, held between the fibers, and the skin for extended periods during use. As a result, the penetration of the formulation into the skin is further promoted, improving the effectiveness of the formulation on the skin.
Furthermore, the formed coating exhibits excellent moisture resistance even under conditions of high temperature or high humidity, making it less susceptible to environmental influences and allowing the film shape to be easily maintained stably. Therefore, the formulation can be stably retained between the fibers for extended periods, further enhancing the efficacy of the formulation on the skin.

Thus, by using the film-forming composition of the present invention, it is possible to form a film with stable quality that is less affected by the usage environment and can stably maintain a good film shape and good adhesion over a long period of time.

<About electrostatic spray>
A coating is formed by electrostatically spraying a film-forming composition and depositing fibers onto the skin.
The electrostatic spraying method involves applying a positive or negative high voltage to a film-forming composition to charge it, and then spraying the charged composition toward an object. The sprayed film-forming composition spreads through the air, repeatedly becoming finer due to Coulomb repulsion, and during this process, or after adhering to the area to be coated, the volatile solvent evaporates, forming a film on the surface of the area to be coated.

[Electrostatic spray device]
Figure 1 is a schematic diagram showing the configuration of an electrostatic spray device preferably used in the present invention.
As shown in Figure 1, the electrostatic spray device 10 comprises a low-voltage power supply 11, a high-voltage power supply 12, an auxiliary electrical circuit 13, a microgear pump 14 as a liquid supply pump, a container 15, a nozzle 16, a conduit 17, a flexible conduit 18, and a current limiting resistor 19. Note that the liquid supply pump can be replaced with a piston pump instead of a gear pump, and the nozzle and pump may be replaceable.

The low-voltage power supply 11 generates a voltage of several volts to over ten volts. To enhance the portability of the electrostatic spray device 10, the low-voltage power supply 11 preferably consists of one or more batteries. Furthermore, using batteries as the low-voltage power supply 11 has the advantage of allowing for easy replacement as needed. Alternatively, an AC adapter or the like can be used as the low-voltage power supply 11 instead of batteries.

The high-voltage power supply 12 is connected to the low-voltage power supply 11 and includes an electrical circuit (not shown) that boosts the voltage generated by the low-voltage power supply 11 to a high voltage. The boosting electrical circuit generally consists of a transformer, capacitor, and semiconductor elements.

The auxiliary electrical circuit 13 is interposed between the low-voltage power supply 11 and the high-voltage power supply 12, and has the function of adjusting (amplifying) the voltage of the low-voltage power supply 11 to ensure stable operation of the high-voltage power supply 12.
Furthermore, the auxiliary electrical circuit 13 has the function of controlling the rotational speed of the motor provided in the microgear pump 14. By controlling the rotational speed of the motor, the amount of film-forming composition supplied from the container 15 to the microgear pump 14 is controlled.
A switch SW is installed between the auxiliary electric field 13 and the low-voltage power supply 11. The electrostatic spray device 10 can be operated/stopped by switching the SW on and off.

The nozzle 16 is made of various conductive materials, including metal, and its outer circumference is covered with a non-conductive material such as plastic, rubber, or ceramic.
The nozzle 16 is shaped to allow the film-forming composition to be discharged from its tip. A minute space through which the film-forming composition flows is formed inside the nozzle 16 along its longitudinal direction. The cross-sectional size of this minute space is preferably 100 μm or more and 1000 μm or less in diameter.
The nozzle 16 is connected to the microgear pump 14 via a conduit 17. The conduit 17 may be made of a conductive or non-conductive material.
The nozzle 16 is electrically connected to the high-voltage power supply 12, making it possible to apply a high voltage to the nozzle 16. In this case, in order to prevent an undesirable current from flowing if a human body directly touches the nozzle 16, the nozzle 16 and the high-voltage power supply 12 are electrically connected via a current-limiting resistor 19.

The container 15 contains the coating-forming composition. Preferably, the container 15 is a replaceable cartridge type. The container 15 is connected to the microgear pump 14 via a flexible conduit 18.
The microgear pump 14 functions as a supply device that supplies the film-forming composition contained in the container 15 to the nozzle 16.
The microgear pump 14 operates by receiving power from the low-voltage power supply 11.
The microgear pump 14, under the control of the auxiliary electrical circuit 13, supplies a predetermined amount of the coating composition to the nozzle 16.

Figure 2 shows an example of the use of the electrostatic spray device 10 described above.
In the example shown in Figure 2, the electrostatic spray device 10 is a handy type with dimensions that allow it to be held in one hand. The electrostatic spray device 10 has a cylindrical housing 20, and all of the components shown in Figure 1 are housed within the housing 20. Note that the shape of the housing 20 is not limited to a cylindrical shape, and can typically be shaped and sized to be easily held in one hand.
A nozzle (not shown) is positioned at one end 10a in the longitudinal direction of the housing 20. The nozzle is positioned so as to be convex toward the skin side, with the direction of discharge of the film-forming composition 1 aligned with the longitudinal direction of the housing 20. This makes it difficult for the film-forming composition to adhere to the housing 20, allowing for stable film formation.

<Method for manufacturing coatings using electrostatic spraying>
A preferred method for producing a coating according to the present invention comprises a formulation application step and a coating formation step. The formulation application step may be performed before or after the coating formation step.

[Formulation Application Process]
The formulation application process involves applying the formulation to the skin. The formulation is applied by the user or assistant, primarily to the area where film formation is to occur. The formulation has a different composition from the film-forming composition, preferably does not contain the first polymer of the present invention, and preferably is applied to the skin by a method other than electrostatic spraying.
Preferably, the formulation has functions such as moisturizing, anti-inflammatory, antiseptic, and topical hemorrhoid treatment. The formulation may be selected as appropriate depending on the skin symptoms. Examples of formulations will be described later.
The formulation can be applied to the skin in liquid, cream, foam, or mist form for ease of application. Typically, the formulation is applied to the skin before film formation to improve adhesion between the film and the skin.
Applying the formulation before the film-forming process makes the sprayed film-forming composition adhere more strongly due to electrostatic force, and also improves the transparency of the sprayed film-forming composition. Improved transparency makes the presence of the film less visually apparent, resulting in a natural, skin-like appearance without any unnatural feeling.
On the other hand, if the formulation application process is performed after the film formation process, the film formed by electrostatic spraying becomes more easily absorbed by the formulation, resulting in increased adhesion to the skin and further improved transparency.

Here, applying a formulation to the skin refers to a state in which the formulation adheres to, is applied to, carries, or is fixed to a target area on the skin.
The means by which the formulation is applied to the skin are not particularly limited. For example, it may be spread using fingers, a brush or other tools, or it may be sprayed using a sprayer or the like.

[Film formation process]
The film formation process involves using the electrostatic spraying device 10 to electrostatically spray a film-forming composition directly onto the skin to form a film consisting of deposits containing fibers.
By using the formulation and coating together, the capillary force of the fibers forming the coating prevents the formulation from being unevenly distributed and allows it to spread, while also retaining the formulation between the fibers and/or on the fiber surface.

The coating manufacturing method using the electrostatic spray device 10 is as follows.
As shown in Figure 2, the user U, that is, the person who will be forming a coating on their skin using electrostatic spraying, holds the electrostatic spraying device 10 in their hand and points one end 10a of the electrostatic spraying device 10, where the nozzle (not shown) is located, towards the area to be coated with electrostatic spraying. Figure 2 shows the state in which one end 10a of the electrostatic spraying device 10 is pointed towards the inside of the user U's forearm. In this state, the switch of the electrostatic spraying device 10 is turned on and electrostatic spraying is performed.
When the electrostatic spray device 10 is powered on, an electric field is generated between the nozzle and the skin. In the embodiment shown in Figure 2, a positive high voltage is applied to the nozzle, and the skin becomes the negative electrode. When an electric field is generated between the nozzle and the skin, the film-forming composition at the tip of the nozzle is polarized by electrostatic induction, and its tip becomes cone-shaped. From the tip of the cone, charged droplets of the film-forming composition are discharged into the air along the electric field toward the skin. As the solvent evaporates from the charged film-forming composition discharged into the air, the charge density on the surface of the film-forming composition becomes excessive, and it spreads into the air while repeatedly becoming finer due to Coulomb repulsion, eventually reaching the skin. While being discharged into the air, the volatile solvent is volatilized from the film-forming composition, and the film-forming polymer (first polymer and second polymer), which is the solute, is solidified while being stretched and deformed by the potential difference to form fibers. These fibers are then deposited on the surface of the skin to form a film.
Once the electrostatic spraying is complete, the power to the electrostatic spraying device 10 is turned off. This eliminates the electric field between the nozzle and the skin.

During the electrostatic spraying process, a high potential difference is generated between the nozzle and the skin. However, because the impedance is very high, the current flowing through the human body is extremely small. For example, the inventors have confirmed that the current flowing through the human body during the electrostatic spraying process is several orders of magnitude smaller than the current flowing through the human body due to static electricity generated in normal daily life.

When forming a fiber deposit by electrostatic spraying, the thickness of the fibers, expressed as a circular diameter, is preferably 10 nm or more, more preferably 50 nm or more. It is also preferably 3000 nm or less, and more preferably 1000 nm or less. In this way, by forming a coating using electrostatic spraying, it is possible to form a coating consisting of nanometer-order fibers.
The thickness of a fiber can be measured, for example, by observing it under a scanning electron microscope (SEM) at a magnification of 10,000 times, removing defects (fiber clumps, fiber intersections, droplets) from the two-dimensional image, selecting 10 fibers at random, drawing lines perpendicular to the longitudinal direction of the fibers, and directly reading the fiber diameter.

[Examples of formulations]
The formulation preferably contains one or more selected from water, polyols, and oils that are liquid at 20°C.

Water-containing formulations include, for example, water, aqueous solutions, and aqueous dispersions. Examples of water-containing formulations include lotions, emulsions such as O/W emulsions and W/O emulsions, compositions having a lamellar structure, cosmetic creams, and aqueous solutions thickened with thickeners. From the viewpoint of moisturizing properties and ensuring good adhesion of the film to the skin, compositions having a lamellar structure are preferred.

When a formulation contains a polyol, examples of such polyols include alkylene glycols such as ethylene glycol, propylene glycol, 1,3-propanediol, and 1,3-butanediol; polyalkylene glycols such as diethylene glycol, dipropylene glycol, polyethylene glycol, and polypropylene glycol; and glycerin derivatives such as glycerin, diglycerin, and triglycerin. From the viewpoint of ensuring good adhesion of the film to the skin, a polyol that is liquid at 20°C is preferred.

When a formulation contains a polyol, the polyol content in the formulation is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, from the viewpoint of ensuring good adhesion of the film to the skin. Similarly, from the same viewpoint, it is 40% by mass or less, preferably 30% by mass or less, and even more preferably 20% by mass or less. Furthermore, the polyol content in the formulation is preferably 3% by mass or more and 40% by mass or less, more preferably 5% by mass or more and 30% by mass or less, and even more preferably 10% by mass or more and 20% by mass or less.

When a formulation contains an oil that is liquid at 20°C (hereinafter, this oil is also referred to as "liquid oil"), examples of oils that are liquid at 20°C include linear or branched hydrocarbon oils, ester oils, higher alcohols of branched or unsaturated fatty acids, and silicone oils.

Examples of the above-mentioned hydrocarbon oils include liquid paraffin, squalane, squalene, n-octane, n-heptane, cyclohexane, light isoparaffin, and liquid isoparaffin. From the viewpoint of usability, liquid paraffin and squalane are preferred.

Furthermore, polar oils that are liquid at 20°C can also be preferably used as the above-mentioned liquid oil. Examples include ester oils, higher alcohols of branched or unsaturated fatty acids, and silicone oils. These liquid oils can be used individually or in combination of two or more.

Examples of the above-mentioned ester oils include esters consisting of a linear or branched fatty acid and a linear or branched alcohol or polyhydric alcohol. Specifically, these include isopropyl myristate, cetyl octanoate, octyldodecyl myristate, isopropyl palmitate, butyl stearate, hexyl laurate, myristyl myristate, decyl oleate, hexyldecyl dimethyloctanoate, cetyl lactate, myristyl lactate, lanolin acetate, isocetyl stearate, isocetyl isostearate, cholesteryl 12-hydroxystearylate, ethylene glycol di-2-ethylhexanoate, dipentaerythritol fatty acid ester, and N monoisostearate. - Alkyl glycol, neopentyl glycol dicaprate, diisostearyl malate, glyceryl di-heptylundecanoate, trimethylolpropane tri-2-ethylhexanoate, trimethylolpropane triisostearate, pentaerythritol tetra-2-ethylhexanoate, glyceryl tri-2-ethylhexanoate, trimethylolpropane triisostearate, cetyl 2-ethylhexanoate, 2-ethylhexyl palmitate, diethylhexyl naphthalenedicarboxylate, benzoic acid (carbon 12- 15) Alkyl, Cetearyl Isononanoate, Tri(Caprylic/Capric Acid) Glycerin, (Dicaprylic/Capric Acid) Butylene Glycol, Glyceryl Trilaurate, Glyceryl Trimyristate, Glyceryl Tripalmitate, Glyceryl Triisostearate, Glyceryl Tri-2-Heptyl Undecanoate, Glyceryl Tribehenate, Glyceryl Tri-2-Heptyl Undecanoate, Glyceryl Triisostearate, Glyceryl Coconut Oil Fatty Acid, Methyl Castor Oil Fatty Acid, Oleyl Oleate, Palmitate Examples include 2-heptyl undecyl mitate, diisobutyl adipate, 2-octyldodecyl N-lauroyl-L-glutamic acid, di-2-heptyl undecyl adipate, ethyl laurate, di-2-ethylhexyl sebacate, 2-hexyldecyl myristate, 2-hexyldecyl palmitate, 2-hexyldecyl adipate, diisopropyl sebacate, di-2-ethylhexyl succinate, triethyl citrate, 2-ethylhexyl paramethoxycinnamate, and tripropylene glycol dipivalate.
Furthermore, the liquid oil may include vegetable oils or animal oils containing ester oils. Examples of liquid oils containing ester oils include vegetable oils such as jojoba oil, olive oil, macadamia nut oil, meadowfoam oil, castor oil, safflower oil, sunflower oil, avocado oil, canola oil, apricot kernel oil, rice germ oil, and rice bran oil, as well as animal oils such as liquid lanolin.

Examples of higher alcohols include liquid higher alcohols with 12 to 20 carbon atoms, specifically isostearyl alcohol and oleyl alcohol.

Examples of silicone oils include dimethylpolysiloxane, dimethylcyclopolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, and higher alcohol-modified organopolysiloxanes.

When the formulation contains liquid oil, the liquid oil content in the formulation is preferably 1% by mass or more, more preferably 1.5% by mass or more, and even more preferably 2% by mass, from the viewpoint of ensuring good adhesion of the film to the skin. Similarly, from the same viewpoint, it is 10% by mass or less, preferably 6% by mass or less, and even more preferably 4% by mass or less. Furthermore, the liquid oil content in the formulation is preferably 1% by mass or more and 10% by mass or less, more preferably 1.5% by mass or more and 6% by mass or less, and even more preferably 2% by mass or more and 4% by mass or less.

Furthermore, the formulation may also contain solid lipids, and from the viewpoint of improving the compatibility of the film attached to the skin, it is preferable to include pseudo-ceramides. In this invention, pseudo-ceramides include those also called natural (animal) ceramides, human-type ceramides, and synthetic ceramides. For example, the cosmetic ingredient name is cetyl PG hydroxyethyl palmitamide, and the quasi-drug ingredient name is N-(hexadecyloxyhydroxypropyl)-N-hydroxyethylhexadecanamide, or hexadecyloxy PG hydroxyethyl hexadecanamide (abbreviated name).

<Coating Formation Kit>
As shown in Figure 3, the coating-forming kit 2 of the present invention comprises a container 15 filled with the above-mentioned coating-forming composition and a container 3 filled with the formulation.
The container 15 is, for example, a replaceable cartridge type. The user or caregiver can set the container 15 in the electrostatic spray device 10 and use it.

<Other Components>

[Moisture absorption of the coating]
The moisture absorption of the film formed using the film-forming composition is preferably 1% to 10%, more preferably 2% to 9%, and even more preferably 3% to 7%, from the viewpoint of improving the moisture resistance and adhesion of the film. The moisture absorption of the films in each of the examples described later is shown in Tables 1 to 4.
The moisture absorption of the coating is calculated using a weighted average as shown in equation (3) below.
In formula (3), M1 is the mass (content) of the first polymer in the coating, M2 is the mass (content) of the second polymer in the coating, A1 is the moisture absorption of the first polymer, and A2 is the moisture absorption of the second polymer. The moisture absorption is calculated using formula (1) above. The mass ratio of the first polymer to the second polymer in the coating is the same as the mass ratio of the first polymer to the second polymer in the coating composition.
Moisture absorption of the coating = (A1 × M1 + A2 × M2) / (M1 + M2) ... (3)

[Relationship between the moisture absorption of the first polymer and the second polymer]
From the viewpoint of improving the moisture resistance and compatibility of the film formed using the film-forming composition, it is preferable that the difference in moisture absorption between the first polymer and the second polymer be 5% to 30%, more preferably 7% to 16%.

Although the present invention has been described above based on its preferred embodiments, the present invention is not limited to the above embodiments.

<Examples>
The present invention will be further described below with reference to examples. However, the scope of the present invention is not limited to these examples.

<<Test Example 1: Examination of the blending ratio of the first polymer and the second polymer>>
In Examples 1 to 12, coatings were formed using coating compositions with varying mass ratios (blending ratios) of the first polymer and the second polymer, and the usability of the coatings before and after high temperature and humidity conditions was evaluated.
Furthermore, the moisture resistance of cast films (also called polymer coatings) formed using the first and second polymers blended in the mass ratios specified in each example was evaluated. It should be noted that although the fibers of the cast films evaluated for moisture resistance were not nanofibers, it was confirmed that equivalent moisture resistance evaluation results could be obtained as if nanofibers were used.

[Preparation of coating-forming compositions]
As the coating compositions for Examples 1 to 12, mixtures of the following first polymer, second polymer, and solvent were prepared.
(First polymer)
Polyvinyl butyral resin (product name: S-Rec® BH-3, Sekisui Chemical Co., Ltd.) was used as the first polymer. The moisture absorption of the polyvinyl butyral resin calculated by the above formula (1) was 0.9%.
(Second polymer)
As the second polymer, a vinyl acetate/vinylpyrrolidone copolymer (product name: PLASDONE® S630, Ashland Japan Co., Ltd.) was used. The moisture absorption of this polymer, calculated using the above formula (1), was 16.8%.
(solvent)
As the solvent, 99% synthetic alcohol (Nippon Synthetic Alcohol Co., Ltd.), which is an anhydrous alcohol with an ethanol content of 99.5% by volume or more, was used. In the following description of the examples, this anhydrous alcohol will be referred to as "ethanol." As mentioned above, since ethanol readily absorbs moisture from the air, strictly speaking, the solvent contains water.
Ethanol was mixed into the film-forming composition at a ratio of 93% by mass.

In each of Examples 1 to 12, the mass ratio of the first polymer to the second polymer in the film-forming composition (first polymer: second polymer) is as follows.
(Example 1) 71.4:28.6
(Example 2) 95.2:4.8
(Example 3) 90.9:9.1
(Example 4) 87.0:13.0
(Example 5) 83.3:16.7
(Example 6) 76.9:23.1
(Example 7) 66.7:33.3
(Example 8) 62.5:37.5
(Example 9) 55.6:44.4
(Example 10) 50.0:50.0
(Example 11) 45.5:54.5
(Example 12) 41.7:58.3

[Evaluation of usability]
Five expert panelists evaluated the usability of the coatings formed using the coating-forming compositions of each example, both before and after storage at high temperature and humidity.
In evaluating the film-forming composition before storage at high temperature and humidity, expert panelists electrostatically sprayed the film-forming composition onto the inside of their forearms using the electrostatic spray device 10 under the following film-forming conditions to form a film, and then evaluated the film according to the evaluation method described below.
To evaluate the film-forming composition after high-temperature and high-humidity storage, a fiber sheet was first prepared by electrostatically spraying the film-forming composition onto a base layer using the electrostatic spraying device 10 to form a film. This fiber sheet was then packaged in a breathable packaging material and left to stand for 24 hours in an incubator at 40°C and 90% RH (high-temperature and high-humidity environment). The expert panelists removed the fiber sheet after high-temperature and high-humidity storage from the breathable packaging material, positioned the fiber sheet so that the film was in direct contact with the inside of their forearm, and transferred the film by removing the base layer, thereby forming a film on the skin. Rayon nonwoven fabric (product name: Omi Kenshi 45, Omi Kenshi Co., Ltd.) was used as the base layer.

The conditions for film formation by electrostatic spraying are as follows:
Applied voltage: 30kV
Distance between nozzle and skin: 130 mm
Discharge rate of film-forming composition: 4 mL/h
Environment: 25℃, 30%RH

[Evaluation items and evaluation methods]
The evaluation criteria for usability were three: familiarity, appearance, and wrinkles/air bubbles.
The expert panelists evaluated the skin's affinity for the film formed on the skin, the film's appearance, and the presence of wrinkles or air bubbles in the film. The evaluation was conducted without applying the formulation before or after film formation.
Five expert panelists evaluated each evaluation item on a five-point scale from 1 to 5 according to the following evaluation criteria. Based on the overall average score, the usability of the coating was evaluated on a four-point scale from A to D according to the usability evaluation criteria below.
Table 1 shows the overall average score of the usability of the coatings formed using the coating-forming compositions of each example, both before and after high-temperature and high-humidity storage, as well as the evaluation results based on that score, and the average score for each evaluation item.

(Item evaluation criteria)
5 points...Excellent 4 points...Good 3 points...Average 2 points...Poor 1 point...Very Poor

(Usability evaluation criteria)
A: 4.5 ≤ Overall average score ≤ 5.0
B: 4.0 ≤ Overall average score < 4.5
C: 3.0 ≤ Overall Average Score < 4.0
D: Overall average score < 3.0

[Evaluation of moisture resistance of cast film]
The moisture resistance of the cast film was evaluated as follows:
0.35 g of the polymer to be evaluated (a mixture of the first and second polymers according to the formulation ratios of each example) was dissolved in 4.65 g of ethanol to prepare 5 g of polymer solution. This polymer solution was prepared in a ratio of 7% by mass of polymer and 93% by mass of ethanol. The polymer solution was placed in a 5 cm square plastic scheele and dried at room temperature for 72 hours to evaporate the ethanol and prepare a cast film.
Next, the prepared cast film was left to stand in an incubator at 40°C and 90% RH (high temperature and high humidity environment) for 24 hours. The weight change rate of the cast film before and after standing in the high temperature and high humidity environment was calculated. Based on this weight change rate, the hygroscopicity of the cast film was evaluated on a four-point scale from A to D as follows. The evaluation results are shown in Table 1.
A: 0% ≤ weight change rate ≤ 5%
B: 5% < Weight change rate ≤ 10%
C: 10% < Weight change rate ≤ 15%
D: 15% < Weight change rate

Figure 4 is a graph created based on Table 1, showing the relationship between the proportion of the second polymer (horizontal axis) and the overall average usability score of the coating after high-temperature, high-humidity storage (vertical axis).

As shown in Table 1 and Figure 4, when the proportion of the second polymer in the film-forming composition was 0.05 to 0.60, the film's compatibility evaluation before and after high-temperature, high-humidity storage was 3 or higher, and its usability evaluation was B or higher, indicating good performance.

<<Test Example 2: Investigation of the Second Polymer, Part 1>>
In Examples 1 (the same as Example 1 of Test Example 1), 13, and 14, the mixing ratio of the first polymer and the second polymer was the same, and a film-forming composition was prepared using a material with different moisture absorption properties for the second polymer. The usability of the film formed using this film-forming composition under the same formation conditions as in Test Example 1, both before and after high temperature and high humidity, was evaluated using the same method as in Test Example 1.
Furthermore, the moisture resistance of the cast film formed using the first polymer and the second polymer in the blending ratios of each example in the same manner as in Test Example 1 was evaluated using the same method as in Test Example 1.
Furthermore, as Comparative Example 1, a film-forming composition containing only the first polymer was prepared, and the usability of the film formed using this film-forming composition was evaluated. In addition, the moisture resistance of the cast film formed using only the first polymer was evaluated.
Table 2 shows the overall average score of the usability of the coatings formed by the coating-forming compositions of each example and comparative example before and after high-temperature and high-humidity storage, the evaluation results based on that score, the average score for each evaluation item, and the evaluation results for the cast film.

[Preparation of coating-forming compositions]
For the film-forming compositions of Examples 1, 13, and 14, a mixture of the following first polymer, second polymer, and solvent was prepared. In preparing this mixture, the polymers were blended so that the mass ratio of the first polymer to the second polymer was 71.4:28.6.
Furthermore, a mixture of the following first polymer and solvent was prepared as a film-forming composition for Comparative Example 1. The second polymer was not included in this film-forming composition.
(First polymer)
Polyvinyl butyral resin (product name: S-Rec® BH-3, Sekisui Chemical Co., Ltd.) was used as the first polymer. The moisture absorption of the polyvinyl butyral resin calculated by the above formula (1) was 0.9%.
(Second polymer)
The following were used as the second polymer in each example.
(Example 1) Vinyl acetate/vinylpyrrolidone copolymer (product name: PLASDONE® S630 Ashland Japan Co., Ltd.) The moisture absorption of the polymer calculated by the above formula (1) was 16.8%.
(Example 13) Diethyl sulfate of vinylpyrrolidone dimethylaminoethyl methacrylate copolymer (product name: Gafquat 734, Ashland Japan Co., Ltd.) The moisture absorption of the polymer calculated by the above formula (1) was 28.4%.
(Example 14) Vinylcaprolactam/vinylpyrrolidone/dimethylaminopropylmethacrylamide/methacryloylaminopropyllauryldimonium chloride copolymer (Aquastyle 300N Ashland Japan Co., Ltd.) The moisture absorption of the polymer calculated by the above formula (1) was 19.8%.
(solvent)
Ethanol was used as the solvent. Ethanol was mixed into the film-forming composition at a ratio of 93% by mass.

<<Test Example 3: Investigation of the Second Polymer, Part 2>>
In Examples 1 (the same as Example 1 of Test Example 1) and 15-17, vinyl acetate/vinylpyrrolidone copolymers with different compositional ratios of vinylpyrrolidone (VP) and vinyl acetate (VA) were used as the second polymer, and the blending ratio of the first polymer and the second polymer was the same. The usability of the films formed under the same formation conditions as in Test Example 1, both before and after high temperature and humidity, was evaluated using the same method as in Test Example 1.
Furthermore, the moisture resistance of the cast films formed using the first and second polymers of each example was evaluated using the same method as in Test Example 1.
Table 3 shows the overall average score of the usability of the coatings formed by the coating-forming compositions of each example before and after high-temperature and high-humidity storage, the evaluation results based on that score, the average score for each evaluation item, and the evaluation results for the cast film.

[Preparation of coating-forming compositions]
For the film-forming compositions of Examples 1, 15-17, a mixture of the first polymer, the second polymer, and the solvent shown below was prepared. In preparing this mixture, the polymers were blended so that the mass ratio of the first polymer to the second polymer was 71.4:28.6.
(First polymer)
Polyvinyl butyral resin (product name: S-Rec® BH-3, Sekisui Chemical Co., Ltd.) was used as the first polymer. The moisture absorption of the polyvinyl butyral resin calculated by the above formula (1) was 0.9%.
(Second polymer)
The following were used as the second polymer in each example.
(Example 1)
The moisture absorption of the vinyl acetate/vinylpyrrolidone copolymer (product name: PLASDONE® S630 (composition ratio VP:VA = 60:40), Ashland Japan Co., Ltd.) calculated using the above formula (1) was 16.8%.
(Example 15)
The moisture absorption of the vinyl acetate/vinylpyrrolidone copolymer (product name: PVP/VA E735 (composition ratio VP:VA = 70:30), Ashland Japan Co., Ltd.) calculated using the above formula (1) was 26.2%.
(Example 16)
The moisture absorption of the vinyl acetate/vinylpyrrolidone copolymer (product name: PVP/VA S535 (composition ratio VP:VA = 50:50), Ashland Japan Co., Ltd.) calculated using the above formula (1) was 14.6%.
(Example 17)
The moisture absorption of the vinyl acetate/vinylpyrrolidone copolymer (product name: PVP/VA E335 (composition ratio VP:VA = 30:70), Ashland Japan Co., Ltd.) calculated using the above formula (1) was 12.0%.
(solvent)
Ethanol was used as the solvent. Ethanol was mixed into the film-forming composition at a ratio of 93% by mass.

<<Test Example 4: Investigation of the Second Polymer, Part 3>>
Examples 1 (the same as Example 1 of Test Example 1), 18 and 19, and Comparative Examples 2 and 3 were prepared by using the same blending ratio of the first polymer and the second polymer, but using materials with different hygroscopic properties for the second polymer to create a film-forming composition. The usability of the film formed using this film-forming composition under the same formation conditions as in Test Example 1, both before and after high temperature and high humidity, was evaluated using the same method as in Test Example 1.
Furthermore, the moisture resistance of the cast films formed using the first and second polymers of each example and comparative example in the same manner as in Test Example 1 was evaluated using the same method as in Test Example 1.
Table 4 shows the overall average score of the usability of the coatings formed by the coating-forming compositions of each example and comparative example before and after high-temperature and high-humidity storage, the evaluation results based on that score, the average score for each evaluation item, and the evaluation results for the cast film. In Table 4, a "-" in the usability column indicates that the coating dissolved and the evaluation could not be performed.

[Preparation of coating-forming compositions]
For the film-forming compositions of Examples 1, 18, and 19, and Comparative Examples 2 and 3, a mixture of the first polymer, the second polymer, and the solvent shown below was prepared. In preparing this mixture, the polymers were blended so that the mass ratio of the first polymer to the second polymer was 71.4:28.6.
(First polymer)
Polyvinyl butyral resin (product name: S-Rec® BH-3, Sekisui Chemical Co., Ltd.) was used as the first polymer. The moisture absorption of the polyvinyl butyral resin calculated by the above formula (1) was 0.9%.
(Second polymer)
The following were used as the second polymer in each example and comparative example.
(Example 1)
Vinyl acetate/vinylpyrrolidone copolymer (product name: PLASDONE® S630, Ashland Japan Co., Ltd.) The moisture absorption of the polymer calculated using the above formula (1) was 16.8%.
(Example 18)
Polyoxyethylene (20) polyoxypropylene (20) glycol (product name: Pronon 124P, NOF Corporation) The moisture absorption of the polymer calculated using the above formula (1) was 8.5%.
(Example 19)
PEG-11 methyl ether dimethicone (product name: Silicone KF6011, Shin-Etsu Chemical Co., Ltd.) The moisture absorption of the polymer calculated using the above formula (1) was 6.5%.
((Comparative Example 2))
Polyethylene glycol (product name: PEG400, Wako Pure Chemical Industries, Ltd.) This polyethylene glycol is a polymer with an average molecular weight of 360 to 440. The moisture absorption of this polymer, calculated using the above formula (1), was 45.6%.
((Comparative Example 3))
Polyethylene glycol (product name: PEG1450, Sanyo Chemical Industries, Ltd.) This polyethylene glycol is a polymer with an average molecular weight of 1450. The moisture absorption of this polymer, calculated using the above formula (1), was 42.0%.
(solvent)
Ethanol was used as the solvent. Ethanol was mixed into the film-forming composition at a ratio of 93% by mass.

Furthermore, the following primer solution (formulation) formulation is disclosed as an example of a formulation that can be applied before and after the film formation process.
<Primer Liquid Formula>
Pseudo-ceramide 1% by mass
Glycerin fatty acid ester 0.34% by mass
Cetyl alcohol 0.34% by mass
Dimethylpolysiloxane 2% by mass
Glycerin 10% by mass
1,3-Butanediol 3% by mass
Distearyldimonium chloride 0.4% by mass
Polyoxyethylene sorbitan monostearate (20 E.O.) 0.2% by mass
Succinic acid 0.005% by mass
Methyl parahydroxybenzoate 0.2% by mass
The mixture was balanced with purified water so that the total percentage reached 100% by mass.

1... Film-forming composition

Claims (7)

A coating-forming composition for forming a coating consisting of fiber-containing deposits by electrostatic spraying directly or indirectly onto a target area for coating,
The aforementioned film-forming composition is
A first polymer that absorbs less than 1% of moisture under high temperature and high humidity conditions (left standing for 24 hours at 40°C and 90% RH),
It contains a second polymer whose moisture absorption is 5% to 29% under high temperature and high humidity conditions (left standing for 24 hours at 40°C and 90% RH),
The first polymer comprises one or more polymers selected from polyvinyl butyral resin, polyurethane resin, and polylactic acid.
The second polymer comprises one or more polymers selected from polyvinylpyrrolidone, a copolymer of polyvinylpyrrolidone, a polyalkylene glycol, and a silicone structure-containing copolymer.
When the mass of the first polymer in the film-forming composition is M1 and the mass of the second polymer is M2, the value of M2/(M1+M2) is 0.05 or more and 0.60 or less.
Composition for film formation. The film-forming composition according to claim 1, wherein the second polymer comprises one or more polymers selected from vinyl acetate/vinylpyrrolidone copolymer, vinylpyrrolidone/dimethylaminoethyl methacrylate copolymer diethyl sulfate, vinylcaprolactam/vinylpyrrolidone/dimethylaminopropylmethacrylamide/methacryloylaminopropyl lauryldimonium chloride copolymer, polyoxyethylene polyoxypropylene glycol, and PEG- 11 methyl ether dimethicone. The film-forming composition according to claim 1 or 2, further comprising one or more selected from monohydric alcohols and ketones. The film-forming composition according to claim 1 or 2, wherein the area to be coated is human skin. A method for manufacturing a coating to form a coating on a target area,
The method comprises a coating formation step of directly or indirectly electrostatically spraying a coating-forming composition onto a target area to form a coating, thereby forming a coating consisting of deposits containing fibers.
The aforementioned film-forming composition is
A first polymer that absorbs less than 1% of moisture under high temperature and high humidity conditions (left standing for 24 hours at 40°C and 90% RH),
It contains a second polymer whose moisture absorption is 5% to 29% under high temperature and high humidity conditions (left standing for 24 hours at 40°C and 90% RH),
The first polymer comprises one or more polymers selected from polyvinyl butyral resin, polyurethane resin, and polylactic acid.
The second polymer comprises one or more polymers selected from polyvinylpyrrolidone, a copolymer of polyvinylpyrrolidone, a polyalkylene glycol, and a silicone structure-containing copolymer.
When the mass of the first polymer in the film-forming composition is M1 and the mass of the second polymer is M2, the value of M2/(M1+M2) is 0.05 or more and 0.60 or less.
Coating manufacturing method. The method for producing a coating according to claim 5 , further comprising a formulation application step of applying the formulation to the area to be coated, either before or after the coating formation step. A film-forming composition according to claim 1 or 2,
A film-forming kit comprising a formulation applied to the target site for film formation before or after film formation using the film-forming composition.