JP7310186B2 - Thin film and transfer sheet - Google Patents

Description

The present invention relates to thin films and transfer sheets comprising thin films.

A thin film layer having a thickness of several nanometers to several micrometers is adhesive to the surfaces of living organs, and thus attempts have been made to apply such thin film layers to organs, skin, and the like.
For example, Non-Patent Document 1 reports that the thin film layer can be used as a dressing for wounds. It has also been proposed to apply the thin film layer to the skin to aid skin care and make-up. For example, Patent Literature 1 proposes a cosmetic method in which a thin film layer is attached to the skin and then a cosmetic is applied over the thin film layer. Further, Patent Literature 2 describes a thin film including a thin film layer and a coloring portion formed by applying ink to the thin film layer. For example, by attaching a thin film having a flesh-colored coloring portion to the skin, it is possible to conceal scars on the skin and make spots and freckles less noticeable.

WO2014/058066 JP 2015-193604 A

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

However, when ink is supplied to a thin film layer by a printing method or the like to form a coloring portion, it is difficult to precisely form a coloring portion of a desired color in a desired range because the ink spreads by wetting. rice field. For example, when it is attempted to form a coloring portion in a predetermined pattern, blurring occurs at the outer edge of the coloring portion, creating a gap between the designed pattern and the actually formed pattern.

An object of the present invention is to provide a thin film capable of enhancing the accuracy of forming a coloring portion, and a transfer sheet provided with the thin film.

A thin film that solves the above problems is a thin film comprising a thin film layer having an average mass of 0.1 g/m ² or more and 4 g/m ² or less, wherein the thin film layer has a coloring part that is a cured product of ink. A target surface is formed, and the arithmetic mean roughness Ra of the target surface is 0.1 μm or more and 5 μm or less.

According to the above configuration, the spread of the ink is suppressed due to the increase in the surface area of the thin film layer in contact with the ink supplied to the target surface. As a result, the formation accuracy of the coloring portion is enhanced.
The said structure WHEREIN: A thin film may equip the said object surface with the said coloring part.
According to the above configuration, a thin film having a coloring portion with high forming accuracy is realized.

In the above configuration, the thin film may include a hydrophobic resin layer covering the coloring portion.
According to the above configuration, the exposure of the coloring portion to the outside air and the direct contact of the coloring portion with the transfer-receiving body can be suppressed.

In the above configuration, the thin film layer may be a biocompatible polymer film, and the thin film layer may have a density of 1 g/cm ³ or more and 3 g/cm ³ or less.
According to the above configuration, a thin film layer suitable for attachment to a living body is realized. In addition, in such a thin film having affinity for living tissue, the accuracy of formation of the coloring portion can be enhanced.

In the above configuration, the thin film has a surface opposite to the target surface of the thin film layer as the outermost surface, and the outermost surface or the outermost surface of the thin film opposite to the outermost surface is It may be attached to the skin.

According to the above configuration, since the thin film having the coloring portion with high formation accuracy can be attached to the skin, the function of the thin film, such as assisting makeup, is enhanced. In addition, the thin film can be made thinner as compared with a mode in which both surfaces of the thin film layer are the target surfaces and the coloring portions are formed on both surfaces. Therefore, while the functions required of the thin film such as assisting makeup are sufficiently realized, the skin followability of the thin film is enhanced, and the discomfort felt by the user can be reduced.

A thin film that solves the above problems includes the thin film and a supporting substrate that supports the thin film.
According to the above configuration, deformation of the thin film is suppressed when the transfer sheet is stored or moved. In addition, being supported by the supporting substrate facilitates handling of the thin film.

According to the present invention, it is possible to improve the accuracy of forming the coloring portion with respect to the thin film layer.

The figure which shows the cross-sectional structure of the thin film of a 1st form about one Embodiment of a thin film. (a) is a diagram showing a formation process of a coloring portion in a conventional thin film layer, and (b) is a diagram showing a formation process of a coloring portion in a thin film layer according to an embodiment. The figure which shows the cross-sectional structure of the thin film of a 2nd form about one Embodiment of a thin film. The figure which shows the cross-sectional structure of the other example in the thin film of 2nd form about one Embodiment of a thin film. The figure which shows the cross-sectional structure of the thin film of a 3rd form about one Embodiment of a thin film. The figure which shows the cross-sectional structure of the modification of a thin film about one Embodiment of a thin film. The figure which shows the cross-sectional structure of a transfer sheet about one Embodiment of a transfer sheet.

An embodiment of a thin film and a transfer sheet will be described with reference to the drawings. The transfer sheet is used to transfer the thin film included in the transfer sheet to the object to be transferred. The object to be transferred is not particularly limited, but is, for example, the skin of a living body.

[Structure of thin film]
As the thin film 10 of this embodiment, three forms will be described in order.
As shown in FIG. 1, the thin film 10A of the first embodiment is composed of thin film layers 20. As shown in FIG. The thin film layer 20 has a target surface 20S on which a colored portion, which is a cured product of ink, is formed. The thin film 10A is adhered to the transfer-receiving body after forming the coloring portion on the target surface 20S.

Only one of the two surfaces of the thin film layer 20 may be the target surface 20S, or both of the two surfaces may be the target surface 20S. In other words, the coloring portion may be formed only on one side of the thin film layer 20 or may be formed on both sides of the thin film layer 20 . FIG. 1 illustrates a configuration in which only one side of the thin film layer 20 is the target surface 20S.

The target surface 20S has unevenness, and the arithmetic mean roughness Ra of the target surface 20S is 0.1 μm or more and 5 μm or less. Arithmetic mean roughness Ra is measured according to JISB 0601-1994. The unevenness of the target surface 20</b>S may be unevenness formed by shaping the surface of the thin film layer 20 or may be unevenness following the shape of particles dispersed in the thin film layer 20 . Further, the unevenness of the target surface 20S may be composed of a plurality of protrusions protruding from the target surface 20S, or may be composed of a plurality of recesses recessed from the target surface 20S. It may be configured by mixing with recesses. The sizes of the protrusions and recesses may be constant or may not be constant. Moreover, the convex portions and the concave portions may be arranged regularly or may be arranged irregularly.

Since the target surface 20S has the above surface roughness, the formation accuracy of the coloring portion is enhanced. This principle will be explained with reference to FIG. FIG. 2(a) schematically shows a case where ink is applied to a flat surface, and FIG. 2(b) schematically shows a case where ink is applied to an uneven surface.

When ink is supplied to a region having a predetermined area in a plan view viewed from the direction facing the target surface 20S, the surface area of the thin film layer 20 in contact with the ink in the target surface 20S is larger when the target surface 20S has unevenness. increase. For example, as shown in FIG. 2, when the ink In is supplied to the region Ro having the width Wo in plan view, the surface area of the thin film layer 20 in contact with the ink In in the region Ro is such that the target surface 20S has unevenness. case becomes larger.

The liquid contained in the ink permeates the thin film layer 20 in the thickness direction and spreads along the target surface 20S. This causes wetting and spreading of the ink. When the ink spreads along the target surface 20S, the size of the region in which the ink spreads in plan view is smaller when the target surface 20S has unevenness than when the target surface 20S is flat. Become. For example, as shown in FIG. 2, when the surface area L is the surface area over which a predetermined amount of ink In supplied to the region Ro is spread, the plane of the region R1 having the surface area L when the target surface 20S is flat When the target surface 20S has unevenness, the width W2 of the region R2 having the surface area L in plan view is smaller than the width W1 in view.

Therefore, since the target surface 20S has unevenness, the area where the ink spreads is reduced in plan view, and the formation of the coloring layer over the area to which the ink is supplied is suppressed.

Further, when the target surface 20S has unevenness, as described above, the surface area of the thin film layer 20 in contact with the ink in the region where the ink is supplied increases, so that the ink permeates in the thickness direction of the thin film layer 20. That is, penetration of the liquid medium contained in the ink is promoted. As a result, the fixing of the coloring material such as the pigment contained in the ink to the target surface 20S is promoted, and the spreading of the ink along the target surface 20S is suppressed. This also prevents the coloring layer from being formed to extend beyond the area to which the ink is supplied.

If the arithmetic mean roughness Ra of the target surface 20S is 0.1 μm or more, the effect of suppressing the formation of the coloring layer to spread beyond the ink-supplied area as described above can be sufficiently obtained. Further, when the arithmetic mean roughness Ra of the target surface 20S is larger than 5 μm, the thickness of the thin film layer 20 may be locally thinned, and the strength of the thin film layer 20 tends to be low. Therefore, when the arithmetic mean roughness Ra of the target surface 20S is 5 μm or less, the thin film layer 20 is prevented from being easily broken. In order to increase the strength of the thin film layer 20, the arithmetic mean roughness Ra of the target surface 20S is more preferably 4 μm or less.

The thin film layer 20 may be a single layer or may be composed of multiple layers. The thin film layer 20 has such a thickness that it exhibits adhesiveness to the transferred body. Expressing these characteristics in terms of the mass of the thin film layer 20, the average mass per unit area of the thin film layer 20 is 0.1 g/m ² or more and 4 g/m ² or less. The density of the thin film layer 20 at this time is, for example, 1 g/cm ³ or more and 3 g/cm ³ or less.

The above-mentioned average mass is obtained by cutting each of the three arbitrary locations in the thin film layer 20 into square-shaped film pieces with one side of 100 mm in plan view, and measuring the average value of the mass of the three film pieces with a precision balance. Calculated by multiplying.

When the average mass is 0.1 g/m ² or more, the strength of the thin film layer 20 is sufficiently ensured, so that the thin film layer 20 is prevented from tearing when it is attached to a transferred body. When the average mass is 4 g/m ² or less, the adhesion of the thin film layer 20 to the transferred body, especially to the skin, is sufficiently obtained. In addition, when the thin film layer 20 is applied to the skin, wrinkles in the thin film layer 20 and uncomfortable feeling for the user can be suppressed.

The average mass increases when the thin film layer 20 contains, as additives, components such as oils that function as plasticizers, various resin components, particles, and the like. When the additive is not contained, the average mass per unit area of the thin film layer 20 is preferably 0.1 g/m ² or more and 2.0 g/m ^{2 or} less.

A second form of thin film will be described with reference to FIG. As shown in FIG. 3, the thin film 10B of the second embodiment includes a coloring portion 21 in addition to the thin film layer 20 described above. The coloring portion 21 is positioned on the target surface 20S. In the drawings below, the surface of the coloring portion 21 opposite to the target surface 20S is shown flat, but the coloring portion 21 may have a shape that follows the unevenness of the target surface 20S.

The coloring portion 21 is a cured product of ink containing a coloring material. The coloring portion 21 presents an arbitrary visible color under a light source in a predetermined wavelength range. For example, the coloring portion 21 may be visually recognized as colored under light in the visible region, or may be visually recognized as colored under light in the ultraviolet region.

The coloring portion 21 may be monochromatic, or may have a plurality of regions exhibiting different colors. Further, the coloring portion 21 may be positioned in a partial area of the target surface 20S, or may be positioned over the entire target surface 20S. For example, the coloring portion 21 may form a pattern such as a design, a picture, or a character, or may be formed in a gradation form in which the color density gradually changes.

The function of the thin film 10B realized by the coloring portion 21 is not particularly limited. The thin film 10B may be provided with a function of concealing defects such as scars, spots, and freckles on the skin by the coloring portion 21, or a function of decorating the skin like a tattoo sticker may be provided with the thin film 10B. Further, the coloring portion 21 may form a pattern having information such as identification information, and such information may be read from the thin film 10B attached to the transfer-receiving body and used. In this case, the coloring section 21 may be configured so as not to be visually recognized under light in the visible range. For example, when both surfaces of the thin film layer 20 are the target surfaces 20S, one target surface 20S is formed with a coloring portion 21 having a color that is visible under light in the visible region, and the other target surface 20S is: A coloring portion 21 having the above information and not visible under light in the visible region may be formed.

Since the target surface 20S has the above-described surface roughness, the accuracy of the formation range of the coloring portion 21 is enhanced. Therefore, when the coloring portion 21 is to be formed in a desired pattern, bleeding of the pattern is suppressed, and the accuracy of forming the pattern with respect to the design is enhanced. In addition, when regions exhibiting different colors are adjacent to each other in the coloring portion 21, the accuracy of designing the color switching position is enhanced. Even when the coloring portion 21 is configured in a gradation pattern, the accuracy of the positions of changes in color density is enhanced, so that the gradient of the gradation can be accurately formed according to the design.

Incidentally, as shown in FIG. 3, the coloring portion 21 may be positioned on the target surface 20S, and as shown in FIG. It may soak into the inside. When the coloring material contained in the ink for forming the coloring portion 21 permeates into the thin film layer 20 together with the medium, the coloring portion 21 partially soaked inside the thin film layer 20 is formed.

A third embodiment of the thin film will be described with reference to FIG. As shown in FIG. 5, the thin film 10C of the third embodiment includes a hydrophobic resin layer 22 in addition to the thin film layer 20 and the coloring portion 21 described above. The hydrophobic resin layer 22 covers the coloring portion 21 on the target surface 20S. The hydrophobic resin layer 22 spreads over the thin film layer 20, for example.

The coloring portion 21 is protected by the provision of the hydrophobic resin layer 22 . In the thin film 10C, when the surface of the thin film 10C on which the coloring portion 21 is located faces the outside of the transferred body and is exposed to the outside air, the surface of the hydrophobic resin layer 22 is the outermost surface. exposed to the outside air. Therefore, compared to a form in which the hydrophobic resin layer 22 is not provided and the coloring portion 21 is exposed to the outside air, the coloring portion 21 is prevented from being detached from the target surface 20S due to rubbing or the like. Further, in the thin film 10C, a hydrophobic resin layer 22 is provided in the case where the surface of the thin film 10C on which the coloring portion 21 is located is attached to the skin as an object to be transferred. As a result, the coloring portion 21 is prevented from coming into direct contact with the skin, so that the stimulation of the skin by the coloring material is suppressed.

When the thin film 10C is attached to the skin, the thin film 10C is likely to come into contact with moisture such as sweat. Since the hydrophobic resin layer 22 is mainly composed of a hydrophobic resin, even when the thin film 10C comes into contact with moisture, the state in which the hydrophobic resin layer 22 covers the coloring portion 21 is preferably maintained. can.

The average mass per unit area of the hydrophobic resin layer 22 is preferably 3.9 g/m ² or less. The density of the hydrophobic resin layer 22 at this time is, for example, 1 g/cm ³ or more and 3 g/cm ³ or less. The average mass is measured by the same method as for the average mass of the thin film layer 20 .

In any of the first to third embodiments, the thickness of the thin film layer 20 is necessarily thicker at convex portions on the target surface 20S and thinner at concave portions on the target surface 20S. No need. The thin film layer 20 may include a portion that is a convex portion on one target surface 20S and a concave portion on the surface opposite to the target surface 20S, in other words, a portion that has a wavy cross-sectional shape. FIG. 6 shows, by way of example, a second form of thin film 10B comprising such a thin film layer 20 . When the thin film layer 20 has a wavy cross-sectional shape, the ink medium is particularly thick at the convex portions of the target surface 20S, compared to the case where the thin film layer 20 is thicker at the convex portions of the target surface 20S. It easily penetrates the thin film layer 20 . Therefore, the fixing of the coloring material to the target surface 20S is promoted, and the spreading of the ink along the target surface 20S is suppressed.

[Thin film material]
A material constituting the thin film layer 20 is not particularly limited. When the object to be transferred is a living body, the thin film layer 20 is preferably a biocompatible polymer film having affinity for living tissue. In this case, the material of the thin film layer 20 is, for example, polymeric materials such as polylactic acid, hyaluronic acid, polyglycolic acid, fibroin, polycaprolactone, chitosan, copolymers of these polymeric materials, and acrylic urethane copolymers. one or more materials selected from the group consisting of coalescing; There is no particular limitation on the molecular weight of the material of the thin film layer 20, and the thin film layer 20 may be composed of one type of material having a predetermined average molecular weight, or may be composed of a plurality of types of materials having mutually different average molecular weights. may

Moreover, when the thin film 10 is attached to the skin as a transfer target, the thin film layer 20 may contain a functional substance, which is a substance that exhibits a predetermined function on the skin. Functional substances are, for example, cosmetics used for skin care such as moisturizing creams and serums, cosmetic ingredients, pigments, drugs, proteins, enzymes, and the like. The thin film layer 20 may contain only one kind of functional substance, or may contain two or more kinds. Moreover, the thin film layer 20 may contain various additives such as a plasticizer.

When the unevenness of the target surface 20S is generated by containing particles, for example, an inorganic filler or an organic filler is used as the particles. Examples of inorganic filler materials include talc, silica, mica, alumina, zinc oxide, titanium oxide, barium sulfate, calcium carbonate, magnesium carbonate, barium silicate, calcium silicate, metallic soap, and silicone. Materials for the organic filler include, for example, polyamide, polyethylene, polypropylene, acrylic resin, polyurethane, polytetrafluoroethylene, and cellulose. The volume average particle diameter of the particles contained in the thin film layer 20 measured by a laser diffraction scattering method is preferably 0.5 μm or more from the viewpoint of suppressing aggregation of particles in the process of forming the thin film layer 20. It is preferably 20.0 μm or less from the viewpoint of suppressing sedimentation.

The ink for forming the coloring portion 21 includes a liquid medium and a coloring material such as a pigment or a dye. The medium may be a dispersion medium or a solvent, that is, the color forming material may be dispersed or dissolved in the ink. Additionally, the ink may include dispersed color-forming material and dissolved color-forming material.

Water and various organic solvents can be used as the ink medium. The ink medium may be composed of a mixture of a plurality of materials. As the pigment, known organic pigments and inorganic pigments can be used. An example of a black inorganic pigment is carbon black. As the dye, for example, known synthetic food coloring and natural food coloring can be used. The ink may contain a plurality of types of materials as coloring materials, and may be adjusted to a desired color by mixing a plurality of pigments and dyes. When the thin film 10 is attached to the skin, it is preferable that the ink material, particularly the coloring material, is a material that has little effect on the skin. Moreover, the ink may contain additives such as a dispersant.

The hydrophobic resin forming the hydrophobic resin layer 22 is not particularly limited. Hydrophobic resins include, for example, polymeric materials such as polylactic acid, polycaprolactone, acrylic resins and polycarbonate, copolymers of these polymeric materials, acrylic urethane copolymers, and the like. There is no particular limitation on the molecular weight of the material of the hydrophobic resin layer 22, and the hydrophobic resin layer 22 may be composed of one type of material having a predetermined average molecular weight, or a plurality of types of materials having different average molecular weights. It may be constructed from any material.

Moreover, when the thin film 10 is attached to the skin, the hydrophobic resin layer 22 may contain a functional substance, which is a substance that exhibits a predetermined function on the skin. Functional substances are, for example, cosmetics used for skin care such as moisturizing creams and serums, cosmetic ingredients, pigments, drugs, proteins, enzymes, and the like. The hydrophobic resin layer 22 may contain only one kind of functional substance, or may contain two or more kinds. Moreover, the hydrophobic resin layer 22 may contain various additives such as a plasticizer.

[Structure of transfer sheet]
As shown in FIG. 7 , the transfer sheet 30 includes the thin film 10 and a supporting substrate 31 that supports the thin film 10 . FIG. 7 exemplifies the form in which the transfer sheet 30 is provided with the thin film 10C of the third form, but the transfer sheet 30 may be provided with the thin film 10B of the second form.

Among the surfaces of the thin film 10, the surface supported by the supporting substrate 31 is the supporting surface 11F, and the outermost surface opposite to the supporting surface 11F is the non-supporting surface 11N. When only one side of the thin film layer 20 is the target surface 20S, the support surface 11F may be the outermost surface of the thin film 10 facing the same side as the target surface 20S, or may be the outermost surface facing the target surface 20S. It may be the outermost surface. When the support surface 11F has unevenness, the support substrate 31 may or may not fill the unevenness of the support surface 11F.

When the thin film 10 is adhered to the transfer target, the support surface 11F is exposed to the outside air, and the non-support surface 11N is in contact with the transfer target. That is, when the coloring portion 21 is provided only on one side of the thin film 20, the outermost surface of the thin film 10, which is located on the same side as the coloring portion 21 with respect to the thin film layer 20, is attached to the transferred body. Alternatively, the outermost surface of the thin film layer 20 located on the side opposite to the coloring portion 21 may be attached to the transferred body.

In particular, when the transfer sheet 30 is provided with the thin film 10B of the second form, if the outermost surface on the side where the coloring part 21 is located is attached to the transferred body, the coloring part 21 is a thin layer on the transferred body. Since it is covered with 20, detachment of the coloring part 21 is suppressed. On the other hand, if the outermost surface on the side opposite to the coloring portion 21 is adhered to the skin as a transferred body, the coloring portion 21 can be prevented from irritating the skin.

Note that the transfer sheet 30 may include the thin film 10</b>A of the first embodiment as the thin film 10 . In this case, the target surface 20S is the non-supporting surface 11N, and the transfer sheet 30 is used for transfer after the color developing portion 21 is formed on the transfer sheet 30. FIG.

The support base material 31 has a function of suppressing the deformation of the thin film 10 when the transfer sheet 30 is stored or when the thin film 10 is moved onto the object to be transferred when the transfer sheet 30 is used. Being supported by the support base material 31 makes it easier to handle the thin film 10 .

The support base material 31 is preferably a porous base material. A porous substrate is a substrate having a large number of minute gaps inside, and can permeate or permeate a liquid. Porous substrates that can be used as the support substrate 31 include, for example, sheets made of fiber materials such as nonwoven fabrics, paper, knitted fabrics, and woven fabrics, and resin sheets having a structure including gaps such as a mesh. Among these base materials, nonwoven fabrics are preferably used because they can rapidly absorb and diffuse moisture. Fibers constituting the non-woven fabric are, for example, natural fibers such as cotton, hemp, wool and pulp, semi-synthetic fibers such as rayon, and synthetic fibers such as polyvinyl alcohol and polyacrylic acid. Among the above fibers, natural fibers, particularly pulp, are preferably used. The nonwoven fabric may be composed of one type of fiber, or may be composed of two or more types of fiber.

The manufacturing method of the nonwoven fabric used as the support base material 31 is not particularly limited, and for example, any one of the spunlace method, spunbond method, needle punch method, melt blow method, air lay method, flash spinning method, and resin adhesion method. It may be a nonwoven fabric manufactured by The basis weight of the nonwoven fabric used as the support base material 31 is preferably 10 g/m ² or more and 150 g/m ² or less, and is 20 g/m ² or more and 50 g/m ^{2 or} less because it is excellent in use feeling such as touch. is more preferred.
In addition, the supporting base material 31 is not limited to the porous base material, and may be composed of a base material such as a resin sheet or a metal foil that does not have a gap inside.

The transfer sheet 30 may have a protective layer that covers the non-supporting surface 11N of the thin film 10 . The protective layer has a function of protecting the non-supporting surface 11N of the thin film 10 . The protective layer is preferably composed of a porous substrate. As the porous base material constituting the protective layer, each of the above-mentioned materials exemplified as the porous base material constituting the supporting base material 31 can be used. The protective layer and the supporting substrate 31 may be composed of the same type of porous substrate, or may be composed of different types of porous substrates. In addition, the protective layer is not limited to the porous base material, and may be composed of a base material such as a resin sheet or a metal foil having no internal gaps.

[Method for producing thin film and transfer sheet]
An example of a method for manufacturing the thin film 10 and the transfer sheet 30 will be described. Note that the thin film 10 and the transfer sheet 30 may be manufactured by a method different from the manufacturing method described below as long as the thin film 10 and the transfer sheet 30 having the configurations described above can be formed.

First, the thin film layer 20 is formed on the surface of the film-forming substrate. As the film-forming base material, a base material composed of a thermoplastic resin, a thermosetting resin, a water-soluble resin, a metal oxide, a metal, or the like is used. For example, the film-forming substrate is a substrate made of a resin such as polyethylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, acrylic resin, polycarbonate, cycloolefin, polyamide, epoxy resin, urethane resin, polyvinyl alcohol, etc. Such resin substrates It is a base material that has been stretched, released, or matted. Alternatively, a substrate made of an inorganic material such as glass, quartz, aluminum, or the like, or a substrate made of such an inorganic material subjected to mold release treatment or matte processing may be used as the film-forming substrate. Also, the film-forming substrate may be a substrate having high liquid permeability, such as a porous substrate.

A coating liquid in which the material of the thin film layer 20 is dissolved in a solvent is applied to the surface of the film-forming substrate, and the thin film layer 20 is formed by drying the coating film. Examples of the solvent include ester solvents such as ethyl acetate and butyl acetate, ketone solvents such as acetone and ethyl methyl ketone, nonpolar solvents such as toluene and hexane, and water and alcohol, depending on the characteristics of the material of the thin film layer 20. A polar solvent such as is used.

The method of applying the coating liquid is not particularly limited as long as it is a method capable of precisely controlling the coating amount of the coating liquid. As the coating method, for example, gravure, microgravure, spin coating, spray coating, silk screen, die coating, or curtain coating is preferably used.

The film-forming substrate may be used as the supporting substrate 31, or a substrate different from the supporting substrate 31 may be used as the film-forming substrate, and the thin film layer 20 formed on the film-forming substrate may be used as the supporting substrate. It may be transferred onto the material 31 . As a transfer method, a known transfer method such as a method using peeling by suction or a method using a sacrificial film may be used.

A known method may be used as a method for forming the unevenness on the target surface 20S of the thin film layer 20 . For example, the following four methods are available as methods of forming unevenness by molding the surface of the thin film layer 20 . In the first method, a substrate on which irregularities are formed in advance, that is, a substrate that has been subjected to matte processing is used as the film-forming substrate. By using a film-forming base material having unevenness on the surface, the surface of the thin film layer 20 in contact with the film-forming base material is formed with unevenness. In the second method, when the coating liquid is applied to the film-forming substrate, a printing plate with a random pattern is used to form unevenness on the surface of the coating film, so that the film-forming substrate in the thin film layer 20 Concavities and convexities are formed on the surface opposite to the . In the third method, unevenness is formed on the surface of the thin film layer 20 opposite to the film-forming substrate by contacting the surface of the coating with a plate having an uneven pattern before the coating is dried. In the fourth method, after drying the coating film, a plate having an uneven pattern is heated and pressed against the surface of the film, or the film is heated and pressed against the cooled plate. As a result, unevenness is formed on the surface of the thin film layer 20 opposite to the film-forming substrate. The plate used for forming the unevenness may be made of metal or may be made of resin.

When the thin film layer 20 contains particles, the particles may be dispersed in the coating liquid. It should be noted that unevenness of the target surface 20S may be formed by both shaping the surface of the thin film layer 20 and containing particles.

The coloring portion 21 may be formed on the thin film layer 20 having the target surface 20S as the top surface on the film-forming substrate, or may be formed on the thin film layer 20 having the target surface 20S as the top surface on the support substrate 31. may be formed for According to the method of forming the thin film 10 by forming the coloring portion 21 on the thin film layer 20 on the film forming substrate, and then transferring the thin film 10 to the supporting substrate 31, the coloring portion is formed on the thin film layer 20. A transfer sheet 30 can be formed in which the outermost surface on the same side as 21 serves as the support surface 11F. According to the method of forming the thin film 10 by forming the coloring portion 21 on the thin film layer 20 on the support substrate 31, the outermost surface of the thin film layer 20 opposite to the coloring portion 21 is the supporting surface 11F. A transfer sheet 30 can be formed.

A printing method is preferably used as a method for forming the coloring portion 21, that is, as a method for supplying ink to the target surface 20S. Examples of printing methods include inkjet printing, offset printing, and screen printing. Ink may be supplied to the target surface 20S using a method other than the printing method, such as a method using spraying.

If the base material supporting the thin film layer 20 when forming the coloring portion 21 is a base material with high liquid permeability, the penetration of the ink medium in the thickness direction of the thin film layer 20 is promoted. As a result, the fixing of the coloring material to the target surface 20S is promoted, and the spreading of the ink along the target surface 20S is suppressed. In addition, when the thin film layer 20 contains particles, if the particles have hygroscopicity, this also promotes penetration of the ink medium in the thickness direction of the thin film layer 20 .

The hydrophobic resin layer 22 is formed by applying a coating liquid obtained by dissolving the material of the hydrophobic resin layer 22 in a solvent to the target surface 20S on which the color developing portion 21 is formed, and drying the coating film. . Examples of the solvent include ester solvents such as ethyl acetate and butyl acetate, ketone solvents such as acetone and ethyl methyl ketone, nonpolar solvents such as toluene and hexane, and water, depending on the characteristics of the material of the hydrophobic resin layer 22. and polar solvents such as alcohol are used.

The method of applying the coating liquid is not particularly limited as long as it is a method capable of precisely controlling the coating amount of the coating liquid. As the coating method, for example, gravure, microgravure, spin coating, spray coating, silk screen, die coating, or curtain coating is preferably used.
When forming the transfer sheet 30 having a protective layer, the protective layer is laminated on the non-supporting surface 11N of the thin film 10 .

[Transfer method for thin film]
A method of transferring the thin film 10 using the transfer sheet 30 will be described. A method of transferring the thin film 10 to the skin as a transfer target by using a porous base material as the support base material 31 and moistening the support base material 31 will be described below.

First, a liquid such as water is supplied to a portion of the skin where the thin film 10 is attached. The supply liquid, which is the liquid to be supplied, may be any liquid that can wet the transfer sheet 30, specifically, any liquid containing water or oils such as massage oil. For example, as the supply liquid, water or cosmetics such as lotion can be used.

Subsequently, the transfer sheet 30 is placed on the skin so that the non-supporting surface 11N of the thin film 10 is in contact with the application site. Then, by pressing the transfer sheet 30 with a finger or the like from above the support base material 31 , the supply liquid is permeated into the support base material 31 .

Subsequently, the support base material 31 is peeled off from the thin film 10 . Thereby, the thin film 10 is attached to the skin. When the transfer sheet 30 gets wet, the supporting base material 31, which is a porous base material, expands, and the supply liquid penetrates between the supporting base material 31 and the thin film 10. The base material 31 becomes easier to peel off from the thin film 10 .

In the above transfer method, the method of supplying the supply liquid to the skin before placing the transfer sheet 30 on the skin was exemplified. may be supplied to Alternatively, the support base material 31 may be peeled off from the thin film 10 without wetting the transfer sheet 30 . In this case, the supporting substrate 31 does not have to be a porous substrate.

[Example]
The thin film and transfer sheet described above will be described using specific examples and comparative examples.

(Example 1)
DL-polylactic acid (manufactured by Musashino Chemical Laboratory Co., Ltd.) was dissolved in ethyl acetate to a concentration of 10 wt % to prepare a coating liquid for forming a thin film layer. As a substrate for film formation, a soda plate glass with a thickness of 1 mm whose surface is sandblasted to form unevenness and subjected to mold release treatment is used, and the coating liquid is applied to the surface of the substrate for film formation using a wire bar. to form a coating film. The arithmetic mean roughness Ra of the surface of the film-forming substrate is 0.15 μm. A thin film layer was formed by drying and solidifying the coating film by heating in an oven. The heating temperature during drying was selected from the range of 70°C or higher and 120°C or lower. In the above steps, the thin film layer was formed so as to have an average weight of 0.4 g/m ² after drying.

Subsequently, a non-woven fabric (manufactured by Futamura Chemical Co., Ltd.) as a supporting substrate was laminated on the thin film layer, the film forming substrate was peeled off, and the thin film layer was transferred from the film forming substrate to the supporting substrate. The main component of the nonwoven fabric is cellulose, and the basis weight is 20 g/m ² . The upper surface of the thin film layer on the supporting base material becomes a target surface having irregularities.

Subsequently, an ink was applied to the target surface of the thin film layer on the support base material using an inkjet printing method to form a patterned colored portion. The ink for forming the color-developing portion was prepared using water as a medium and Red No. 102, Yellow No. 4, and carbon black as color-developing materials. Each coloring material was blended so that the color of the ink would be a skin color. The pattern to be formed was a line-and-space type pattern in which belt-like regions with a width of 0.5 mm are arranged in parallel at intervals of 0.5 mm.
Thus, a thin film and a transfer sheet of Example 1 were obtained. The thin film of Example 1 is the thin film of the second embodiment.

(Example 2)
A thin film and a transfer sheet of Example 2 were obtained by the same steps as in Example 1, except that soda lime glass having a different surface roughness from that of Example 1 was used as the film forming substrate. The soda lime glass used in Example 2 has unevenness formed by sandblasting on the surface, and the surface arithmetic mean roughness Ra is 3.5 μm. The pattern for forming the color-developing portion in the second embodiment is the same pattern as in the first embodiment.

(Example 3)
Same as in Example 1, except that soda lime glass having a different surface roughness from that in Example 1 was used as the film-forming substrate, and the thin film layer was formed so that the average mass after drying was 0.7 g/m ² . A thin film and a transfer sheet of Example 3 were obtained by the same process. The soda lime glass used in Example 3 has unevenness formed by sandblasting on the surface, and the surface arithmetic mean roughness Ra is 2.8 μm. The pattern for forming the coloring portion in the third embodiment is the same pattern as in the first embodiment.

(Comparative example)
Same as in Example 1, except that soda lime glass having a different surface roughness from that in Example 1 was used as the film-forming substrate, and the thin film layer was formed so that the average mass after drying was 0.7 g/m ² . A thin film and a transfer sheet of Comparative Examples were obtained by the same process. The soda lime glass used in the comparative example has unevenness formed by sandblasting on the surface, and the surface arithmetic mean roughness Ra is 0.05 μm. The pattern for forming the colored portion in the comparative example is the same pattern as in the first example.

(Evaluation method)
<Measurement of surface roughness>
Arithmetic mean roughness Ra was measured for the target surface of the thin film layer in each of the thin films of Examples and Comparative Examples. For the measurement, a square-shaped test piece with a side of 20 mm was prepared from the thin film layer before the formation of the colored portion in each example and comparative example, and the surface of the smooth substrate was moistened with water. The surface opposite to the target surface was attached to the base material, and the surface roughness was measured after drying the test piece for several hours to about 24 hours. The measurement was performed using a surface roughness profiler (Surfcom 130A, manufactured by Tokyo Seimitsu Co., Ltd.) according to a measuring method conforming to JIS B 0601:1994.

<Evaluation of Formation Accuracy of Colored Portion>
With respect to the pattern of the colored portion of the thin film of each example and comparative example, the width of the belt-like region in plan view from the direction facing the target surface was measured. When the width of the band-shaped region is 0.5 mm, "⊚" is used. , and the case of exceeding 0.65 mm was set as "x".

<Evaluation results>
Table 1 shows the measurement results of the arithmetic mean roughness Ra of the target surface and the evaluation results of the formation accuracy of the colored portion for each example and comparative example.

In the comparative examples in which the arithmetic mean roughness Ra of the target surface was smaller than 0.1 μm, the gaps between the adjacent belt-like regions were difficult to see, and the line-and-space pattern could not be formed. On the other hand, in Examples 1 to 3 in which the target surface had an arithmetic mean roughness Ra of 0.1 μm or more, the gap between the adjacent band-shaped regions was visible, and a line-and-space pattern was formed. In particular, it was confirmed that the greater the arithmetic mean roughness Ra of the target surface, the more the width of the belt-like region is suppressed compared to the pattern to be formed, and the higher the pattern formation accuracy.

As described above in the embodiments and examples, according to the thin film and the transfer sheet, the effects listed below can be obtained.
(1) If the target surface 20S on which the coloring portion 21 is formed has an arithmetic mean roughness Ra of 0.1 μm or more and 5 μm or less, the surface area of the thin film layer 20 in contact with the ink supplied to the target surface 20S increases. spread of the ink is suppressed. As a result, the formation accuracy of the coloring portion 21 is enhanced.

(2) In the form in which the thin film 10 includes the hydrophobic resin layer 22 that covers the coloring portion 21, the coloring portion 21 is prevented from being exposed to the outside air and the coloring portion 21 is prevented from coming into direct contact with the transferred material. .

(3) When the object to be transferred is the skin, the thin film 10 having the coloring portion 21 with high forming accuracy is attached to the skin, so that the function of the thin film 10 such as assisting makeup is enhanced. In addition, in a mode in which only one surface of the thin film layer 20 is the target surface 20S and the surface of the thin film layer 20 opposite to the target surface 20S is the outermost surface of the thin film 10, both surfaces of the thin film layer 20 are the target surface 20S. Therefore, the thin film 10 can be made thinner as compared with the form having the coloring portions 21 on both sides. Therefore, while the functions required of the thin film 10, such as assisting makeup, can be sufficiently achieved, the followability of the thin film 10 to the skin is enhanced, and discomfort felt by the user can be reduced.

10, 10A, 10B, 10C thin film 11F supporting surface 11N non-supporting surface 20 thin film layer 20S target surface 21 coloring portion 22 hydrophobic resin layer 30 transfer sheet 31 …a supporting substrate.

Claims (5)

A thin film comprising a thin film layer having an average mass of 0.1 g/m ² or more and 4 g/m ² or less,
The thin film layer has a target surface on which a colored portion, which is a cured product of ink, is formed,
the thin film layer is a biocompatible polymer film,
The thin film layer has a density of 1 g/cm ³ or more and 3 g/cm ³ or less,
A thin film, wherein the target surface has an arithmetic mean roughness Ra of 0.1 μm or more and 5 μm or less. The thin film according to claim 1, wherein the target surface is provided with the coloring portion. 3. The thin film according to claim 2, further comprising a hydrophobic resin layer covering the coloring portion. The thin film has a surface opposite to the target surface in the thin film layer as an outermost surface, and the outermost surface or the outermost surface of the thin film opposite to the outermost surface is attached to the skin. The thin film according to any one of claims 1 to 3 . A thin film according to any one of claims 1 to 4 ,
a supporting substrate that supports the thin film;
A transfer sheet comprising:

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