JP2023070534A - Thin film bondable onto oil solution, transfer sheet for thin film, method for using thin film and method for producing thin film - Google Patents

Abstract

To provide a thin film that retains its followability regardless of moisture, oil-based cosmetics or agents applied on an adherend, a transfer sheet for a thin film, a method for using a thin film and a method for producing a thin film.SOLUTION: A thin film has a unit area mass of 0.1 g/m2 or more and 5.0 g/m2 or less. The thin film has a face to be in contact with an adherend, the face having a plurality of cavities with a diameter of 1 μm or more and 900 μm or less. The distance between adjacent cavities is 20 μm or more and 2000 μm or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a thin film, a transfer sheet, a method of using the thin film, and a method of manufacturing the thin film.

A thin film having a thickness of several μm or less has high conformability to the surface shape of an adherend such as the skin of a living body, and thus adheres to the adherend without using an adhesive or pressure-sensitive adhesive. Therefore, various uses of such thin films have been proposed. For example, Patent Literature 1 and Non-Patent Literature 1 describe the use of thin films for cosmetic applications such as skin care and makeup, and medical applications such as wound healing.

JP 2017-19116 A

T. Fujie et al. , Adv. Funct. Mater. , 2009, Vol. 19, pp. 2560-2568

The followability of the thin film is lost when there is an interposition between the adherend and the thin film. For example, when an adherend is coated with a substance that is difficult to be absorbed by the adherend or a substance that is difficult to evaporate into the atmosphere, the thin film cannot follow the adherend.

Assuming that the adherend is human skin, after applying cosmetics, a thin film is attached for the purpose of moisturizing and blocking. At that time, by applying an oily agent that is difficult to be absorbed by the skin and is difficult to evaporate into the atmosphere, the followability of the thin film is reduced. There is a demand for a thin film that can be applied without being affected by the type of drug that is applied to human skin, that maintains followability even on oils and fats, and that can be applied.

Therefore, the present invention provides a thin film, a transfer sheet of the thin film, a method for using the thin film, which retains followability without being affected by moisture, oil cosmetics, and chemicals applied to the adherend, and , an object of the present invention is to provide a method for manufacturing a thin film.

One aspect of the present invention for solving the above problems is a thin film having a mass per unit area of 0.1 g/m ² or more and 5.0 g/m ² or less, which is brought into contact with an adherend of the thin film. It is characterized by having a plurality of voids with a diameter of 1 μm or more and 900 μm or less on the surface and a distance between adjacent voids of 20 μm or more and 2000 μm or less. .

Another aspect of the present invention is a transfer sheet comprising a thin film and a supporting substrate that supports the thin film.

Another aspect of the present invention is a method of using a thin film, which includes a step of attaching the thin film to an adherend that is a living body.

Another aspect of the present invention is a step of applying a coating liquid to a substrate to form a thin film constituting a first surface;
A step of applying the coating liquid on the first surface, spraying water with a sprayer before drying, and then drying the coating film to form a thin film constituting the second surface in which voids are formed; A method for producing a thin film, comprising:

Another aspect of the present invention is a method for producing a thin film, comprising the step of applying a coating liquid containing a pore structure additive to a substrate to form a thin film constituting the first surface.

Another aspect of the present invention includes a step of applying a coating liquid to a base material to form a thin film constituting a first surface, applying a coating liquid containing a fibrous additive on the first surface, and a step of forming a thin film forming a surface.

According to the present invention, a thin film, a transfer sheet of the thin film, a method for using the thin film, which retains followability without being affected by moisture, oily cosmetics, and chemicals applied to the adherend, and , can provide a thin film manufacturing method.

The figure which shows the cross-section of the thin film with a hole of one Embodiment. The figure which shows the cross-sectional structure of the thin film containing a fibrous additive of one Embodiment. The figure which shows the cross-section of the thin film containing the additive which has a porous structure of one Embodiment. The figure which shows the container of a thin film A diagram for explaining a method of attaching a thin film to an adherend.

An embodiment of a thin film, a transfer sheet, and a method of using the thin film will be described with reference to the drawings. FIG. 1 is a view showing a cross-sectional structure of a thin film with holes according to one embodiment, FIG. 2 is a view showing a cross-sectional structure of a thin film containing fibrous additives according to one embodiment, and FIG. FIG. 2 is a diagram showing a cross-sectional structure of an additive-containing thin film having a morphological porous structure; An adherend to which the thin film of the present embodiment is attached is a biological tissue such as skin or an organ. In particular, the thin film of the present embodiment is suitably used when the skin of a living body is used as an adherend.

[Structure of thin film]
As shown in FIGS. 1 to 3, the thin film 10 has a first surface 11F and a second surface 11R opposite to the first surface 11F. When the thin film 10 is attached to the adherend, the first surface 11F is in contact with the adherend, and the second surface 11R is the outermost surface located on the opposite side of the adherend. A plurality of gaps are formed in the first surface 11F of the thin film 10 according to the embodiment. As will be explained below, the voids are generated by voids generated in the thin film itself, voids generated between additives such as fibers, and additives having voids such as diatoms.

The perforated thin film described in FIG. 1 may be laminated and has perforations on the first surface 11F side.

The fibrous additive-containing thin film described in FIG. 2 may be laminated and has the fibrous additive on the first surface 11F side.

The thin film with porous structure additive, described in FIG. 3, may be laminated and has the porous structure additive on the first surface 11F side.

It is preferable that the diameter of the void is 1 μm or more and 900 μm or less, and the distance between the voids is 20 μm or more and 2000 μm or less. By satisfying the conditions, when an oil-based cosmetic or drug is applied to an adherend and the thin film 10 is attached thereon, the oil-based cosmetic or drug may cause voids due to pressure or capillary action during application. transferred to and absorbed by the body. As a result, it is possible to suppress slippage caused by oil-based cosmetics and medicines remaining between the adherend and the film, thereby improving the adhesion between the adherend and the thin film 10 . In addition, although the space|gap may penetrate, it is preferable not to penetrate. The depth of the voids is preferably 5% or more and 80% or less of the thickness of the thin film.

The thin film 10 is so thin that the thin film 10 alone exhibits adhesiveness to an adherend. In other words, the mass per unit area of the thin film 10 is small enough to exhibit the adhesiveness. Specifically, the mass per unit area of the thin film 10 is 5.0 g/m ² or less. If the mass per unit area is 5.0 g/m ² or less, the thin film 10 can follow the surface shape of the adherend well, and the adhesion between the thin film 10 and the adherend is improved. Increased. In addition, since the thin film 10 has improved conformability to the surface shape of the adherend, even if the adherend has a curved surface or elasticity like the skin, The thin film 10 follows the fine shape of the surface of the adherend. As a result, only the thin film 10 is prevented from moving on the adherend, so failure in attaching the thin film 10 to the adherend is less likely to occur.

Also, the mass per unit area of the thin film 10 is 0.1 g/m ² or more. If the mass per unit area is 0.1 g/m ² or more, the strength of the thin film 10 can be satisfactorily obtained, and defects such as tearing of the thin film 10 are less likely to occur. Also, if the mass per unit area is 0.1 g/m ² or more, it is easy to form the thin film 10 in a continuous film shape.

The mass per unit area is the mass of the thin film 10 converted per part having an area of 1 m ² in plan view. The mass per unit area is obtained, for example, by converting from the average value of masses measured in a plurality of measurement regions, or by multiplying the average thickness of the thin film 10 by the density of the thin film 10 . The density of the thin film 10 is, for example, 1 g/cm ³ or more and 3 g/cm ³ or less.

A polymer material is preferably used as the material of the thin film 10 . The polymer material used for the thin film 10 may be any material that can form the thin film 10 so that the weight per unit area falls within the range described above. When the adherend is skin, the polymeric material is preferably a biocompatible material with low toxicity, skin irritation, and skin sensitization.

A known material is used as the biocompatible polymeric material. Polymer materials include, for example, polyesters, polyolefins, polyamides, polyimides, polyvinyl alcohols, polyurethanes, polyvinyl acetates, polyvinyl chlorides, polyvinylidene chlorides, polycarbonates, acrylic resins, polysiloxanes, cellulose, and polysaccharides such as chitin and chitosan. , various proteins such as casein, rubbers, derivatives, modified products, copolymers and mixtures of these polymer compounds.

The thin film 10 may contain only one type of the polymer materials described above, or may contain a plurality of types. In addition, there is no particular limitation on the molecular weight of the polymer material contained in the thin film 10, and the thin film 10 may contain one type of polymer material having a predetermined weight average molecular weight, or may contain different weight average molecular weights. It may contain a plurality of types of polymer materials having.

The thin film 10 may contain various additives other than the above fibrous additives and porous structure additives. Additives include, for example, high refractive index materials, low refractive index materials, light absorbers, and dyes for adjusting the optical properties of the thin film 10, modifiers for adjusting the wettability of the thin film 10, They are a conductive material, a cosmetic, a beauty ingredient, a medicinal ingredient, a perfume capable of imparting fragrance to the thin film 10, and an antibacterial agent capable of imparting an antibacterial effect to the thin film 10. The additive contained in the thin film 10 may be selected according to the function desired to be exhibited in the thin film 10 .

Since the thin film 10 is attached to the adherend without an adhesive layer, the thin film 10 is intended to act on the adherend like a component for whitening, anti-blemish and anti-wrinkle. When components are contained, the action of such components tends to reach the adherend. Therefore, the components contained in the thin film 10 can function more effectively.

The thin film 10 may be a single film or a laminate of multiple films. When thin film 10 is a laminate of a plurality of films, the composition of each film may be the same or different. Furthermore, some of the multiple films may contain the additive, or each of the multiple films may contain the additive.

[Structure of transfer sheet]
The transfer sheet is used when attaching the thin film 10 to an adherend. As shown in FIGS. 1 to 3, the transfer sheet 20 includes a thin film 10 and a support substrate 21 that supports the thin film 10. As shown in FIGS. The second surface 11</b>R of the thin film 10 is in contact with the support base material 21 .

The support base material 21 has a function of suppressing deformation of the thin film 10 when the thin film 10 is stored or when the thin film 10 is moved onto an adherend when the thin film 10 is used. Being supported by the support base material 21 makes it easier to handle the thin film 10 .

The material of the support base material 21 is not particularly limited. The support substrate 21 is preferably any one of polymer film, woven fabric, knitted fabric, non-woven fabric, and paper, for example.

Materials of the polymer film used for the supporting base material 21 include, for example, polyester, polyolefin, polyamide, polyimide, polyvinyl alcohol, polyurethane, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, polycarbonate, acrylic resin, polysiloxanes, Various proteins such as cellulose and casein, rubbers, derivatives, modified products, copolymers and mixtures of these high molecular compounds. The polymer film used as the support base material 21 may be a film that has undergone processing such as embossing, punching, and making porous by foaming.

The woven fabric, knitted fabric, and non-woven fabric used for the support base material 21 are composed of natural fibers or chemical fibers. As natural fibers, cotton, hemp, pulp, wool, silk, and the like can be used. As chemical fibers, fibers made of polyester, polyolefin, cupra, rayon, lyocell, acetate, diacetate, nylon, aramid, acrylic, etc. can be used. Further, the support base material 21 may be made of a fibrous material in which natural fibers and chemical fibers are mixed. The support base material 21 made of such a fiber material may be subjected to processing such as embossing, punching, and making the fibers porous by foaming.

When the supporting substrate 21 is made of a fiber material, the basis weight of the supporting substrate 21 is preferably 3 g/m ² or more and 200 g/m ² or less, more preferably 10 g/m ² or more and 100 g/m ² or less. preferable. If the basis weight of the supporting base material 21 is at least the above lower limit, the thin film 10 becomes easy to handle because the supporting base material 21 has rigidity to the extent that deformation such as twisting due to static electricity or air currents is difficult to occur. . In addition, if the basis weight of the supporting base material 21 is equal to or less than the above upper limit value, the supporting base material 21 is not excessively clogged with fibers. In addition, the liquid absorption of the supporting base material 21 proceeds smoothly. Therefore, the support base material 21 can be easily peeled off, and the thin film 10 can be suitably transferred from the support base material 21 to the adherend.

When the support base material 21 is made of a fiber material, the manufacturing method of the fiber material is not particularly limited. For example, a wet or dry web produced by a spunbond method, a meltblown method, an airlaid method, a flash spinning method, or the like is manufactured by using a spunlace method, a thermal bond method, a chemical bond method, or the like. A fiber material can be appropriately selected and used.

Moreover, the transfer sheet 20 may include a protective layer that covers the first surface 11F of the thin film 10 . By providing the protective layer, the thin film 10 is protected during storage of the thin film 10 . As the protective layer, the above-described various substrates exemplified as the support substrate 21 can be used. The materials of the protective layer and the supporting substrate 21 may be the same or different.

The outer shape of the thin film 10 and the transfer sheet 20 in plan view is not particularly limited. The outer shape of the thin film 10 and the transfer sheet 20 is, for example, a polygonal shape such as a rectangle, a circular shape, an elliptical shape, or a shape surrounded by straight lines or curved lines. In plan view, the thin film 10 and the support base 21 may have the same shape, or the support base 21 may be larger than the thin film 10 .

[Structure of Thin Film Container]
FIG. 4 shows a container containing the thin film 10 . The thin film container 30 includes a transfer sheet 20 having a protective layer and a packaging body 31 containing the transfer sheet 20 . The package 31 is preferably configured to be sealable.

The packaging body 31 has, for example, a bag shape formed from a polymer film. As the polymer film, for example, a film composed of a single layer or a plurality of layers made of polyolefin, polyester, polyacrylonitrile, nylon, or the like is used. Furthermore, in the package 31, a gas barrier layer made of at least one of an organic substance and an inorganic substance may be laminated on the polymer film. By providing the gas barrier layer, the thin film 10 is prevented from being affected by moisture in the outside air, and thus deterioration of the thin film 10 is suppressed.

[Method for producing thin film and transfer sheet]
As a method for forming voids in the perforated thin film shown in FIG. 1, before drying the coating film constituting the thin film 10, water is sprayed on the first surface 11F with a mist spray, and then the coating film is dried. etc.

The method for forming voids in the thin film containing fibrous additives shown in FIG. The added fibers are fine fibers that can be contained inside the thin film 10, such as cellulose nanofibers.

A method for forming voids in the thin film containing the porous structure additive described in FIG. The pores of the added additive become voids in the thin film 10 . Void additives added to thin films are diatoms and the like.

The thin film 10 is formed by a known thin film forming method. For example, a solution casting method in which a coating liquid containing the material of the thin film 10 is applied to a substrate in a thin film and then the solvent is evaporated, or a melt extrusion method in which a molten material is extruded to form a thin film can be used. Among these methods, the solution casting method is preferably used.

In the solution casting method, a coating liquid is generated by dissolving or dispersing the material of the thin film 10 in a solvent. A coating film is formed by applying the coating liquid to the surface of the film-forming substrate, and the thin film 10 is formed by drying the coating film. For example, a resin film is used as the film-forming substrate. When the thin film 10 has a plurality of layers, the thin film 10 is formed by forming a coating liquid for each layer and repeating the formation and drying of the coating film.

The solvent for the coating liquid may be selected according to the properties of the material of the thin film 10 . Solvents are, for example, water, ethanol, isopropyl alcohol, acetic acid, ethyl acetate, butyl acetate, propyl acetate, ethyl methyl ketone, acetone, dimethylsulfoxide, benzene, hexane, and the like.

The method of applying the coating liquid is not particularly limited as long as it is a method capable of forming a coating film with a desired thickness. Various coating methods such as direct gravure, reverse gravure, small-diameter reverse gravure, Meyer coat, die, curtain, spray, spin coat, screen printing, comma, knife, gravure offset, roll coat, etc. can be used as coating methods. is.

The transfer sheet 20 is formed, for example, by transferring the thin film 10 formed on the film-forming substrate onto the support substrate 21 . As a method of transferring the thin film 10 from the film-forming base material to the support base material 21, a known transfer method such as a method using peeling by suction or a method using a sacrificial film may be used. Alternatively, a film-forming base material may be used as the support base material 21 . That is, the transfer sheet 20 may be formed by depositing the thin film 10 on the supporting substrate 21 as a substrate for film formation. When the protective layer is provided, the protective layer is superimposed on the surface of the thin film 10 placed on the support substrate 21 .

[How to use the thin film]
A method for using the thin film 10 will be described. Below, the case where the thin film 10 is used in the final stage of daily skin care will be described. FIG. 5 is a diagram illustrating a method of attaching a thin film to an adherend.

First, an application step of applying the milky lotion Ml onto the adherend Sk, which is the skin of a living body, is performed. The milky lotion Ml is assumed to contain oil and active ingredients. The active ingredient may be a medicinal ingredient or a cosmetic ingredient. A medicinal component is, for example, a component such as a steroid that has an anti-inflammatory effect. Cosmetic ingredients include, for example, ingredients for whitening, ingredients that improve blemishes and wrinkles, moisturizers, and penetration enhancers. The milky lotion Ml may be liquid or semi-solid such as cream or ointment as long as it can be applied onto the adherend Sk. It should be noted that what is applied onto the adherend Sk is not limited to the milky lotion, and may be moisture, oily cosmetics, and medicines.

Subsequently, a step of attaching the thin film 10 is performed. In the sticking step, the transfer sheet 20 is placed on the adherend Sk so that the first surface 11F of the thin film 10 is in contact with the application area of the latex Ml and the surface of the adherend Sk around it. As a result, the application area of the latex Ml is covered with the thin film 10 .

Next, the support base material 21 is peeled off from the thin film 10 . As a result, the thin film 10 is transferred from the supporting substrate 21 to the adherend Sk, and the attaching step is completed. A liquid such as water or lotion may be supplied to the support base material 21 before the support base material 21 is peeled off. In this case, the separation between the thin film 10 and the supporting substrate 21 is promoted by the liquid permeating the supporting substrate 21 and changing the volume and fiber diameter of the supporting substrate 21 .

After that, the emulsion Ml is fixed on the adherend Sk for a long time. A state in which the thin film 10 is attached to the adherend Sk is maintained for a predetermined period of time. As a result, the milky lotion Ml absorbed by the thin film 10 penetrates into the adherend Sk, and the penetration promoting effect can be preferably obtained. The predetermined period may be set according to the amount of emulsion Ml to be applied and the type of active ingredient.

In the portion where the adherend Sk and the thin film 10 are in direct contact, the thin film 10 follows the fine surface shape of the adherend Sk derived from texture, which is the unevenness of the skin surface. High adhesion between the body Sk and the thin film 10 can be obtained. Since the emulsion Ml is not absorbed by the adherend Sk and does not evaporate into the atmosphere, it is difficult to apply a normal film. The sticking of the thin film is maintained while Ml is maintained.

In the thin film 10, since transmission of the latex Ml is suppressed, it is suppressed that the latex Ml seeps out to the second surface 11R of the thin film 10 and makes the sticking portion of the thin film 10 sticky. Furthermore, since the thin film 10 is extremely thin, it is possible to reduce discomfort in the appearance and feel of the area where the thin film 10 is attached. Therefore, even when the thin film 10 is attached to the adherend Sk, which is the user's skin, for a long time, the user can be prevented from feeling discomfort or discomfort.

Conventionally, when a film made of polyethylene, polyvinylidene chloride, or the like is used, it is difficult to peel off from the base material on the emulsion Ml, and the oil of the emulsion Ml affects the adherend Sk and the conventional film. Slippage occurred due to remaining in between. Therefore, it is difficult to apply the film to the adherend Sk, and even if the film can be applied to the adherend Sk, the film tends to peel off. On the other hand, in the thin film 10 of the present embodiment, the pore structure in the thin film, the fibrous additive, and the pore structure additive control the thin film surface, so that the effect of the latex Ml can be obtained. At the same time, it is possible to provide the thin film 10 with a moisturizing effect and a permeation promoting effect.

In addition, since the thin film 10 is attached to the adherend Sk without using an adhesive layer, it is easier to separate from the adherend Sk than a film attached using an adhesive layer. Therefore, damage to the adherend Sk when the thin film 10 is peeled off can be reduced, and roughening of the adherend Sk caused by components contained in the adhesive layer can be suppressed. Therefore, even if the thin film 10 is applied to the area where the skin is weakened when used as the final stage of usual skin care, it is possible to suppress the burden on the skin due to the application or peeling of the thin film 10.例文帳に追加

Further, the thin film 10 may be used for moisturizing the adherend Sk. In this case, the latex Ml may not be applied to the adherend Sk before the thin film 10 is attached. Even when the milky lotion Ml is not applied, the application of the thin film 10 suppresses the diffusion of moisture pre-existing in the vicinity of the surface of the adherend Sk, thereby moisturizing the adherend Sk. Also, before the thin film 10 is attached, instead of the milky lotion Ml, a liquid such as water containing no active ingredient may be applied to the adherend Sk.

A good amount of water evaporation can be obtained at the location where the thin film 10 is attached. Good water loss means an amount equivalent to the water loss in the inner forearm, which is healthy and less likely to have rough skin. If the moisture transpiration rate is good, it is possible to avoid stuffiness due to excessive moisturizing. By properly maintaining the amount of water transpiration, the amount of water in the skin, such as the amount of water in the stratum corneum, is properly maintained. As a result, the skin's barrier function and the like tend to function normally, and skin homeostasis tends to be maintained normally. In addition, since the thin film 10 is in the form of a film, when it is applied to a conventional cream or liquid moisturizing product, stickiness of the product and adherence of ingredients to clothes can be suppressed. Also, if a cream or liquid moisturizing product is used as a chemical agent, a high moisturizing effect can be obtained while suppressing stickiness.

Further, the thin film 10 may be used for both the penetration and moisturizing purposes of cosmetics applied to the adherend Sk. One example is the improvement of wrinkles caused by age-related deformation. There are two types of wrinkles: shallow wrinkles formed on the epidermis and deep wrinkles formed by deformation of the dermis. The cause of shallow wrinkles is dryness, and shallow wrinkles are improved by moisturizing and turning over the skin. Deep wrinkles are caused by the reduction of collagen fibers and elastic fibers existing in the dermis due to aging and photoaging. Decreased fibers can be restored by penetration of active ingredients into the dermis. By using the thin film 10 of the present embodiment, it is possible to make deep wrinkles inconspicuous by permeation of active ingredients contained in cosmetics, and to improve shallow wrinkles by moisturizing.

The application of the thin film 10 is not limited to moisturizing or promoting permeation, as long as it holds at least one of moisture and a chemical agent between the adherend and the thin film 10 . For example, the thin film 10 may be used in wet therapy where moistening improves the wound healing environment. By using the thin film 10, a wet environment can be preferably formed on the surface of the adherend. The adherend in wet therapy is not limited to the skin, and may be an organ.

As described above, the thin film 10 according to the present embodiment is a thin film having a mass per unit area of 0.1 g/m ² or more and 5.0 g/m ² or less. It is characterized by having voids with a diameter of 1 μm or more and 900 μm or less, and an interval between voids of 20 μm or more and 2000 μm or less. As a result, it is possible to provide a thin film that retains followability without being affected by moisture, oily cosmetics, and chemicals applied on an adherend. In addition, at the place where the thin film is attached, the diffusion of moisture and chemicals can be suppressed, and the deterioration of the followability of the thin film to the adherend due to the oil agent can be prevented. It is possible to achieve both effects of moisturizing and promoting penetration of the agent. In addition, stickiness on the application area of the medicine is also suppressed, so high practicality can be obtained.

Further, the thin film 10 according to this embodiment may be used on a daily basis. Thin films that have been conventionally used for cosmetics cannot be applied on oily agents, and therefore the application sites and application targets are limited. On the other hand, since the thin film 10 according to the present embodiment is compatible with any adherend at the time of application, it can be applied in any daily state, and the simplicity of application can be improved.

In addition, the thin film 10 according to the present embodiment maintains followability without being affected by moisture, oily cosmetics, and medicines applied to the adherend, so that the texture, which is unevenness of the surface of the skin, is maintained. It can be attached regardless of the state of the adherend derived from the above.

In addition, the thin film can be attached regardless of the state of the adherend, and the active ingredient on the adherend can be retained by the thin film regardless of moisture or oil, so that the effect of the active ingredient can be suitably obtained for a long time. be able to. As a result, the convenience of attaching the thin film is improved.

[Example]
The thin film described above will be described using specific examples and comparative examples. Table 1 shows the manufacturing conditions.

(Example 1)
Poly-DL-lactic acid (manufactured by Musashino Chemical Laboratory) was dissolved in butyl acetate to prepare a coating liquid for forming a thin film. The weight average molecular weight of poly-DL-lactic acid is 100,000. The mass ratio of the solute component in the coating liquid was 10%. After that, the above coating liquid was applied to a PET sheet as a base material for film formation using a wire bar to form a coating film. The coating film is applied so that the mass per unit area of the film after drying is 0.3 g/m ² , and the coating film is dried in a circulation oven at 80°C to form the first surface. A thin film was formed. Next, the same coating liquid as the coating liquid used for forming the thin film constituting the first surface was applied onto the first surface so that the mass per unit area was 0.6 g m ² . A thin film consisting of two surfaces was formed. After that, the thin film forming the second surface was sprayed with water by a mist sprayer to form a pore structure and create voids. The coating solution was dried in a circulation oven at 80°C.

Subsequently, a non-woven fabric (manufactured by Futamura Chemical Co., Ltd.) is laminated as a supporting substrate on the thin film on the film-forming substrate, the film-forming substrate is peeled off, and the thin film is removed from the film-forming substrate. Transferred to a supporting substrate. The main component of the nonwoven fabric used as the support base material is cellulose made from pulp, and the basis weight of the nonwoven fabric is 20 g/m ² . As a result, a transfer sheet of Example 1 comprising the supporting substrate and the thin film was obtained.

(Example 2)
In Example 2, a transfer sheet was produced using the same material as in Example 1, except that diatom was added as a pore structure additive to the coating liquid for forming the first surface so that the solid content ratio was 10%. bottom. A PET sheet serving as a substrate for film formation was coated with the above coating solution using a wire bar to form a coating film. The coating film was applied so that the mass per unit area of the film after drying was 0.6 g/m ² , and the coating film was dried in a circulation oven at 80°C to obtain the transfer sheet of Example 2. got

(Example 3)
In Example 3, poly-DL-lactic acid (manufactured by Musashino Chemical Laboratory) was dissolved in butyl acetate to prepare a coating liquid for forming a thin film. The weight average molecular weight of poly-DL-lactic acid is 100,000. The mass ratio of the solute component in the coating liquid was 10%. After that, the above coating liquid was applied to a PET sheet as a base material for film formation using a wire bar to form a coating film. The coating film is applied so that the mass per unit area of the film after drying is 0.6 g/m ² , and the coating film is dried in a circulation oven at 80°C to form the first surface. A thin film was formed. Next, polyvinyl alcohol (Nippon Synthetic Chemical Industry) and cellulose nanofibers were dissolved and dispersed in distilled water to prepare a coating liquid for forming a thin film. The weight average molecular weight of polyvinyl alcohol is 400,000. The weight ratio of the solute component in the coating liquid was 1.25% for polyvinyl alcohol and 1.25% for cellulose nanofiber. After that, the above-described coating solution was applied onto the thin film constituting the first surface using a wire bar to form a coating film. The coating film is applied so that the mass per unit area of the film after drying is 0.3 g/m ² , and the coating film is dried in a circulation oven at 80 ° C. to form a second layer thin film. formed.

(Comparative example 1)
In Comparative Example 1, poly-DL-lactic acid (manufactured by Musashino Chemical Laboratory) was dissolved in butyl acetate to prepare a coating liquid for forming a thin film. The weight average molecular weight of poly-DL-lactic acid is 100,000. The mass ratio of the solute component in the coating liquid was 10%. After that, the above coating liquid was applied to a PET sheet as a base material for film formation using a wire bar to form a coating film. The coating film was applied so that the mass per unit area of the film after drying was 0.6 g/m ² , and the coating film was dried in a circulation oven at 80°C to prepare a thin film without voids. .

(Comparative example 2)
A transfer sheet of Comparative Example 2 was obtained using the same material and process as in Example 2, except that the amount of the pore structure additive was added so that the solid content ratio was 30%. The pore structure additive used in Comparative Example 2 was added so that the solid content ratio was 30%.

(Applying time)
The application time was measured for the films of Examples 1-3 and Comparative Examples 1-2. The sticking time of the thin film is a parameter indicating the time until the sticking of the thin film 10 to the adherend to which the emulsion is applied is completed. Shorter time indicates easier completion of application.

The sticking time was measured by the following method.
(1) 0.1 g of an emulsion (manufactured by Ryohin Keikaku Co., Ltd.) as a cosmetic product containing an oil agent was applied to an artificial leather of □5 cm×5 cm, and spread over the entire surface of the artificial leather using a spatula.

(2) A thin film cut into a diameter of 30 mm was prepared, and the thin film side (first surface) of the thin film was brought into contact with artificial leather to start measurement. Also, the first surface of the thin film was brought into contact with the artificial leather, and the substrate was immediately peeled off with fingers. The time until the substrate was completely peeled off with a finger was measured. This time was defined as the sticking time (sec) of the thin film.

(Attachment rate)
The adhesion rate was measured for the films of Examples 1-3 and Comparative Examples 1-2. The sticking rate was measured by the following method.
(1) After measuring the sticking time of the thin film, the sticking area of the thin film stuck on the artificial leather is compared with φ30 mm before sticking, and what percentage is pasted is calculated by image processing or visually. bottom.

(Remaining rate of wiping off)
The wiping residual rate was measured for the films of Examples 1-3 and Comparative Examples 1-2. The wiping residual rate is the ratio of the applied area of the thin film after wiping to the applied area of the thin film before wiping, and was measured by the following method.
(1) For the thin film-attached artificial leather after the attachment rate measurement, fold the nonwoven fabric (manufactured by Asahi Kasei Co., Ltd.) into four so that it is easy to hold with one hand, and place the thin film-attached artificial leather on the electronic balance. , Adjust so that the nonwoven fabric is pressed with a load of 100 g, rub 10 times in one direction from the top side to the bottom side of the artificial leather, and image analysis or visual observation of the percentage of the thin film remaining on the artificial leather. Calculated.

The adhesion strength of the thin film 10 to the adherend affects the adhesion time, adhesion rate, and wiping residual rate. The adhesion strength between the thin film and the adherend on an oil such as milky lotion and cream can be adjusted by the pore structure of the thin film, the amount of the fibrous additive, and the amount of the pore-like structure additive. For example, the larger the pore structure area per unit area and the amount of the additive, the higher the adhesive strength, the shorter the application time, the higher the application rate, and the higher the wiping residual rate.

Here, when a drug containing an oil such as milky lotion or cream is applied to an adherend and the drug is covered with a thin film, the thin film 10 is attached to the adherend for several hours. often more. Therefore, even after several hours have passed since the thin film 10 was attached to the adherend, it is preferable that the effect of accelerating the penetration of moisture and drugs and the effect of suppressing abnormalities of the adherend such as inflammation continue. .

(result)
Table 2 shows the results of the above measurements in Examples 1-3 and Comparative Examples 1-2.

Table 3 shows the application time, application rate, wiping remaining rate, and overall evaluation for each example and each comparative example.

Regarding the evaluation results of the application time, the time required to complete the application was rated as "O" when it was within 60 seconds, and was rated as "X" when it took longer than 60 seconds. If the application time is 60 seconds or more, the person applying the thin film tends to feel that the application is difficult, and the time to touch the thin film is longer, so the thin film is damaged by the peeling of the base material, and the thin film may be torn. It may occur.

Regarding the adhesion rate, the case of 100% was evaluated as "∘", the case where the application was possible even if there was a chipped portion was evaluated as "Δ", and the case where the application was not possible was evaluated as "x".

Regarding the wiping residual rate, if the rate of change in the applied area before and after wiping was within 30%, it was rated as "O", and if it was greater than 30%, it was rated as "x". If the wipe-off residual rate is 70% or more, the adhesion strength is sufficient to allow the thin film to remain on the adherend without being peeled off when the thin film is applied for a long period of time.

In the comprehensive evaluation, the case where the above evaluation results consisted only of "○" and "△" was given as "○", and the others were given as "x".

The voids formed in the thin films of Examples 1 and 2 were photographed with a microscope, and the diameters of the additives and the spacing between the additives were recorded as coordinates using ImageJ. After that, the distance (μm) per coordinate was calculated from the coordinates of the scale bar, and the diameter and spacing between the additives were obtained from the recorded coordinates. Table 4 shows the diameters and distances of the voids formed in the thin films of Examples 1 and 2.

As shown in Table 3, in Examples 1 to 3, the application time was shorter than 60 seconds, and it was confirmed that the adhesive quickly adhered to the adherend even on cosmetics containing oil agents.

In Example 1, there were uniformly large gaps compared to other examples, and the application time could be greatly shortened. In addition, since the voids do not penetrate the thin film, it is thought that the film strength was maintained, leading to an improvement in the adhesion rate.

In Example 2, the application time was shortened by adding the porous structure additive having a large amount of voids. In Example 2, the sticking rate was smaller than in Example 1 because the size of the porous additive was greater than the thickness of the thin film. It is thought that this is because the area of the film in contact with the adherend decreased, as in , and the film strength decreased.

In Example 3, the fibrous additive was added to form voids, but since the amount of the fibrous additive added was as small as 1.25%, the amount of voids decreased and the application time was shortened. Smaller than 1 and 2. Moreover, since it is a laminated thin film using water-soluble PVA, water is required for adhesion to the adherend. It is considered that the sticking rate was low because the milky lotion applied to the adherend lacked water.

On the other hand, in Comparative Example 1, since there were no voids for absorbing the latex, the latex remained between the adherend and the thin film, delaying contact of the thin film with the adherend and delaying the application time. is longer. In addition, in Comparative Example 2, since the amount of the pore structure additive was as high as 30%, the thin film became brittle and each measurement was difficult.

When cosmetics containing an oil agent are present between the adherend and the thin film, the adhesion between the adherend and the thin film is weakened, and the amount of the thin film remaining on the adherend after wiping off is reduced. However, in Examples 1 to 3, it was confirmed that the oil agent was adsorbed in the structure or the additive, and peeling due to wiping was less likely to occur.

From these results, Examples 1 to 3 solve the conventional problem of attaching a thin film on cosmetics containing oil agents, and attach a thin film only with cosmetics containing oil agents applied to the adherend. become able to.

Sk... adherend M1... latex 10... thin film 11F... first surface 11R... second surface 20... transfer sheet 21... supporting substrate 30... thin film container 31... package

Claims (10)

A thin film having a mass per unit area of 0.1 g/m ² or more and 5.0 g/m ² or less,
Having a plurality of voids with a diameter of 1 μm or more and 900 μm or less on the surface of the thin film that comes into contact with the adherend,
A thin film, wherein the distance between adjacent gaps is 20 μm or more and 2000 μm or less. 2. The thin film according to claim 1, wherein the voids in the thin film are any one of voids generated in the thin film itself, voids generated between additives in fibers, and voids derived from additives having voids. 3. The thin film of claim 1 or 2, wherein the thin film comprises an additive having fibers or voids. The thin film according to any one of claims 1 to 3, which is used for skin care. A transfer sheet comprising: the thin film according to claim 1; and a supporting substrate supporting the thin film. A method of using a thin film, comprising a step of attaching the thin film according to claim 1 to the adherend, which is a living body. The adherend is the skin of a living body, and a coating step of applying a liquid containing an active ingredient intended for percutaneous absorption to the adherend,
7. The method of using the thin film according to claim 6, wherein in the attaching step, the thin film is attached to the adherend so as to cover the area to which the liquid is applied. A method for producing a thin film according to claim 1,
a step of applying a coating liquid to a substrate to form a thin film constituting a first surface;
A step of applying the coating liquid on the first surface, spraying water with a sprayer before drying, and then drying the coating film to form a thin film constituting the second surface in which voids are formed; A method for producing a thin film, comprising: 2. The method for producing a thin film according to claim 1, comprising the step of applying a coating liquid containing a pore structure additive to a substrate to form a thin film constituting the first surface. a step of applying a coating liquid to a substrate to form a thin film constituting a first surface;
The thin film according to claim 1, comprising the step of applying a coating liquid containing a fibrous additive on the first surface to form a thin film constituting the second surface. Production method.

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