Transparent skin patch having a double-layer structure and method for manufacturing the same

Abstract

The present invention provides a transparent skin patch that can maintain adhesion and transparency even when worn for extended periods, and a method for manufacturing the same. [Solution] A transparent skin patch having a double-layer structure is disclosed. The transparent skin patch comprises a surface layer comprising a hydrogel mixture and a skin contact layer comprising the hydrogel mixture and in contact with one surface of the surface layer, wherein the surface layer may comprise a water-soluble ultraviolet blocking mixture that provides ultraviolet blocking functionality.

Description

Technical Field

[0001] The present invention relates to a transparent patch attached to the skin, and more specifically, to a transparent patch containing an ultraviolet blocking component and a hydrogel mixture for improving skin conditions, and a method for manufacturing the same.

Background Art

[0002] In the fields of skin care and medicine, skin attachment patches are regarded as important tools for improving and protecting skin conditions. Such skin attachment patches are developed for various applications such as drug delivery systems, beauty management, wound protection and treatment, and operate in a manner of directly attaching to the skin and transmitting components. In particular, they are widely used for skin beauty purposes such as ultraviolet blocking, wrinkle improvement, moisturizing, and acne treatment. Also, in the medical field, they play a role in assisting wound recovery or transmitting specific drugs to the skin for a long time.

[0003] Another important function of skin attachment patches is to protect the skin from ultraviolet rays. Since ultraviolet rays (UV) can induce problems such as skin aging, spots, and skin cancer, blocking ultraviolet rays is essential. However, although existing skin attachment patches have the function of transmitting ultraviolet blocking components to the skin, there is a problem that their performance and application functions are often unsatisfactory. For example, some products such as golf patches are conspicuous in flesh color and have aesthetic problems, and there is a risk of peeling easily in a wet environment or a situation with a lot of movement due to the limit of adhesion. As a result, consumers have come to prefer patches that are more transparent and have good adhesion.

[0004] On the other hand, skin attachment patches having transparency have problems such as wrinkle generation and the absence of a cooling effect while providing transparency. Skin attachment patches having transparency may impose a burden on the skin due to adhesion, may cause irritation to the skin during long-term wearing, and lack the function of lowering the skin temperature or preventing skin troubles during use, so they cannot provide sufficient satisfaction to consumers.

[0005] Furthermore, existing skin-adhering patches have problems such as the UV-blocking components not being evenly distributed on the skin, or the blocking effect decreasing over time. Also, the adhesion of the patch decreases due to the curves and movement of the skin, reducing the UV-blocking effect, and the patch may peel off easily due to environmental factors such as sweat and water. As a result of these problems, the UV-blocking function may not be fully realized.

[0006] Additionally, for UV-blocking patches, transparency that makes them inconspicuous from the outside is a crucial factor. Consumers who prioritize aesthetics, in particular, want patches that are not noticeable when applied to the skin. However, existing patches struggle to meet this requirement, and there is a need for technology that can effectively incorporate UV-blocking components while maintaining a transparent structure. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Republic of Korea Patent Publication No. 10-2014-0081055 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The problem that this invention aims to solve is to provide a transparent skin patch that can maintain adhesion and transparency even when worn for a long period of time, in order to solve the above-mentioned problems.

[0009] The problems that this invention aims to solve are not limited to those mentioned above, and other problems not mentioned should be clearly understood by an ordinary person from the description below. [Means for solving the problem]

[0010] A transparent skin patch having a double-layer structure according to various embodiments of the present invention is disclosed to solve the above-mentioned problems. The transparent skin patch comprises a hydrogel mixture and includes a surface layer that forms a surface and a skin contact layer that contacts one surface of the surface layer and comprises the hydrogel mixture, wherein the surface layer may comprise a water-soluble ultraviolet blocking mixture that provides ultraviolet blocking functionality.

[0011] In alternative embodiments, the hydrogel mixture comprises distilled water, acrylamide, a hydrophilic polymer, methylenebisacrylamide (MBA), and ammonium persulfate (APS), wherein the hydrophilic polymer may include at least one of the following as a hydrophilic polymeric substances that absorb water: agarose, chitin, chitosan, gelatin, hyaluronic acid, carboxymethylcellulose (CMC), and polyvinyl alcohol (PVA).

[0012] In an alternative embodiment, the distilled water is provided in an amount of 50 to 55 parts by weight per 100 parts by weight of the hydrogel mixture, the acrylamide is provided in an amount of 40 to 45 parts by weight per 100 parts by weight of the hydrogel mixture, the hydrophilic polymer is provided in an amount of 5 to 10 parts by weight per 100 parts by weight of the hydrogel mixture, the methylenebisacrylamide is provided in an amount of 0.025 to 0.030 parts by weight per 100 parts by weight of the hydrogel mixture, and the ammonium persulfate is provided in an amount of 0.125 to 0.130 parts by weight per 100 parts by weight of the hydrogel mixture.

[0013] In an alternative embodiment, the water-soluble ultraviolet-blocking mixture may be characterized by comprising ecamsule and disodium phenyl dibenzimidazole tetrasulfonate (DPDT).

[0014] In an alternative embodiment, the water-soluble ultraviolet-blocking mixture may further comprise zinc oxide (ZnO).

[0015] In an alternative embodiment, the zinc oxide is dispersed in the form of particles in the size range of 15 nm to 35 nm, and the particles may be in the form of at least one of spherical, plate-like, rod-like, and irregular shapes.

[0016] In an alternative embodiment, the surface layer may be composed of a mixture of the water-soluble ultraviolet-blocking mixture and the hydrogel mixture in a ratio ranging from 20 parts by weight:80 parts by weight to 30 parts by weight:70 parts by weight, respectively.

[0017] A method for producing a transparent skin patch having a double-layer structure according to another embodiment of the present invention is disclosed. The method comprises the steps of generating a skin contact layer and generating a surface layer on one surface of the skin contact layer, wherein the skin contact layer and the surface layer are composed of a hydrogel mixture, and the surface layer may comprise a water-soluble ultraviolet-blocking component.

[0018] In an alternative embodiment, the steps for generating the surface layer may include: generating a water-soluble ultraviolet-blocking mixture; generating an initial mixture by adding acrylamide and a hydrophilic polymer to distilled water; adding methylenebisacrylamide to the initial mixture and performing mixing; a mixing mixture step in which the water-soluble ultraviolet-blocking mixture is added to the initial mixture containing methylenebisacrylamide and performing mixing; adding ammonium persulfate to the mixing mixture and performing a mixing step; and performing a film formation step based on the final mixture after mixing to generate a surface layer in film form and perform curing.

[0019] In an alternative embodiment, the step of producing the water-soluble ultraviolet-blocking mixture may include the steps of adding and dissolving ecamsul, phenyldibenzimidazole tetrasulfonate disodium, and zinc oxide to distilled water to produce an initial mixture, adjusting the pH of the initial mixture using citric acid or sodium hydroxide, and adding a humectant and a stabilizer to the pH-adjusted initial mixture to produce the water-soluble ultraviolet-blocking mixture.

[0020] Other specific details of the present invention are included in the detailed description and drawings. [Effects of the Invention]

[0021] According to various embodiments of the present invention, all layers constituting the patch contain hydrogel components, which improves moisture retention, allowing the patch to adhere to the skin for extended periods and maintaining adhesion even with skin curves and movements. Furthermore, the transparent properties of the hydrogel improve the transparency of the patch, providing aesthetic satisfaction, and it can maintain moisture even with prolonged use, minimizing skin irritation.

[0022] In addition, the transparent patch for skin of the present invention has a double-layer structure, which simplifies the manufacturing process compared to the process of separately providing an ultraviolet blocking layer, reduces the thickness of the patch, and greatly improves the wearing feeling. Such a structure strengthens the skin adhesion and further improves the transparency of the patch by eliminating the fat-soluble ultraviolet blocking components.

[0023] In addition, the transparent patch of the present invention causes less irritation even during long-term use, and can continuously maintain the ultraviolet blocking effect while minimizing skin problems, so it can satisfy the convenience and safety of users at the same time.

[0024] The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned should be clearly understood by those skilled in the art from the following description.

Brief Description of the Drawings

[0025] Various aspects are described with reference to the drawings, where like reference numerals are used generically to refer to like components. In the following examples, for purposes of explanation, numerous specific details are presented to provide a thorough understanding of one or more aspects. However, it will be apparent that such aspects may be practiced without these specific details. [Figure 1] FIG. 1 is an exemplary diagram for explaining the peeling phenomenon due to the mechanical properties between the film and the adhesion site. [Figure 2] FIG. 2 is an exemplary diagram for explaining the adhesion force between the film composed of a hydrogel mixture related to an embodiment of the present invention and the skin. [Figure 3] FIG. 3 is an exemplary diagram showing the actual attachment state of the transparent patch for skin related to an embodiment of the present invention. [Figure 4] FIG. 4 is an exemplary diagram exemplarily showing the cross-section of the transparent patch for skin having a double-layer structure related to an embodiment of the present invention. [Figure 5] FIG. 5 is an exemplary diagram for explaining that the surface layer related to an embodiment of the present invention contains nanoparticles. [Figure 6] Figure 6 is an exemplary flowchart of a method for manufacturing a transparent skin patch having a double-layer structure related to one embodiment of the present invention. [Figure 7] Figure 7 is an illustrative diagram illustrating the adhesiveness test process and results related to one embodiment of the present invention. [Figure 8] Figure 8 is an illustrative diagram illustrating the biocompatibility test process and results related to one embodiment of the present invention. [Figure 9] Figure 9 is an illustrative diagram illustrating experimental examples related to the suitability of water-soluble UV-blocking mixtures. [Figure 10] Figure 10 is an illustrative diagram illustrating experimental examples related to the suitability of water-soluble UV-blocking mixtures. [Figure 11] Figure 11 is an illustrative diagram illustrating experimental examples related to the suitability of water-soluble UV-blocking mixtures. [Figure 12] Figure 12 is an illustrative diagram illustrating experimental examples related to the suitability of water-soluble UV-blocking mixtures. [Modes for carrying out the invention]

[0026] A variety of embodiments and / or aspects are disclosed with reference to the drawings. The following description discloses numerous specific details for illustrative purposes to aid in the general understanding of one or more aspects. However, it is also perceptible to those ordinary skill in the art of the invention that these aspects may be implemented without these specific details. The following description and accompanying drawings describe in detail specific exemplary aspects of one or more aspects. However, such aspects are illustrative, and some of the various methods in the principles of the various aspects may be utilized, and the description is intended to include all such aspects and their equivalents. Specifically, the terms “embodiments,” “examples,” “aspects,” “exemplifications,” etc., as used herein, do not necessarily imply that any described aspect or design is better or more advantageous than other aspects or designs. Hereafter, identical or similar components, regardless of their reference numerals in the drawings, will be assigned the same reference numeral, and redundant descriptions thereof will be omitted. Furthermore, in describing the embodiments disclosed herein, if a specific description of the relevant prior art is deemed to obscure the gist of the embodiments disclosed herein, such detailed description will be omitted. In addition, the accompanying drawings are merely for the purpose of facilitating the understanding of the embodiments disclosed herein, and the accompanying drawings do not limit the technical ideas disclosed in the specification.

[0027] Although terms such as "first," "second," etc., are used to describe a variety of elements and components, it goes without saying that these elements and components are not limited by these terms. These terms are simply used to distinguish one element or component from another. Therefore, it goes without saying that the first element or component mentioned below may be the second element or component within the technical concept of the present invention. Unless otherwise defined, all terms used herein (including technical and scientific terms) are intended to be understood in a way that is commonly understood by a person of ordinary skill in the art to which the present invention pertains. Furthermore, terms defined in commonly used dictionaries shall not be interpreted ideally or excessively unless explicitly and specifically defined otherwise. Furthermore, the term "or" is intended to mean an implicational "or," not an exclusive "or." That is, unless otherwise specified or clear from the context, "X uses A or B" is intended to mean one of the natural implicational substitutions. That is, if X uses A, or X uses B, or X uses both A and B, "X uses A or B" can apply to any of these cases. Also, the terms "and / or" as used herein should be understood to refer to and include all possible combinations of one or more of the listed related items.

[0028] Furthermore, the terms “comprise” and / or “comprising” should be understood to mean that the features and / or components in question are present, but not to exclude the presence or addition of one or more other features, components and / or groups thereof. Also, where not otherwise specified or clearly indicated in the context as referring to the singular, the singular in this specification and claims should be interpreted as generally meaning “one or more.” When it is mentioned that one component is “connected” or “linked” to another component, it must be understood that it is directly connected to or may be linked to the other component, but that other components may exist in between. Conversely, when it is mentioned that one component is “directly connected” or “directly linked” to another component, it must be understood that there are no other components in between. When an element or layer is referred to as "on" another element or layer, it includes not only cases where it is directly above another element or layer, but also cases where another layer or element is interposed in between. On the other hand, when an element is referred to as "directly on," it indicates that there is no other element or layer interposed in between. Spatially relative terms such as "below," "beneath," "lower," "above," and "upper" can be used to easily describe the correlation between one component and other components, as illustrated in the drawings. Spatially relative terms should be understood as terms that include not only the directions illustrated in the drawings, but also the different directions of the components during use or operation. The objectives and effects of the present invention, and the technical configurations for achieving them, will become clear when you refer to the embodiments described in detail below, along with the accompanying drawings. In describing the present invention, if a specific explanation of a known function or configuration is deemed to unnecessarily obscure the gist of the invention, such detailed explanation will be omitted. Furthermore, the terms described below are defined in consideration of the functions of the present invention, and these may differ depending on the intent or conventions of the user or operator. However, the present invention is not limited to the embodiments disclosed below and can be embodied in a variety of different forms. These embodiments are provided solely to complete the invention and to fully inform those skilled in the art of which the invention pertains of the disclosure, and the invention is defined only by the claims. Accordingly, the definition should be based on the overall content of this specification. The transparent skin patch 1000 having a double-layer structure of the present invention can be used as a cosmetic and protective patch that adheres directly to the user's skin and performs functions such as UV protection, moisturizing, and skin protection. The transparent skin patch 1000 having a double-layer structure provides both transparency and excellent adhesion, making it easy to use in daily life, and is effective in preventing skin damage caused by ultraviolet rays and improving skin condition.

[0029] According to one embodiment of the present invention, a transparent skin patch 1000 having a double-layer structure is composed of a hydrogel component having mechanical properties similar to those of skin, thereby achieving improved adhesion and reduced peeling. Generally, when there is a large difference in mechanical properties between the film (or patch) and the adhesive site (e.g., skin), uneven stress is generated at the adhesive site, reducing the adhesive strength and making delamination more likely, as shown in Figure 1(a). Figure 1 is an illustrative diagram illustrating the delamination phenomenon caused by the mechanical properties between the film and the adhesive site. More specifically, Figure 1(a) shows a situation where delamination occurs due to stress concentration between the film and the skin when there is a large difference in physical properties. The harder the film and the greater the difference in physical properties between it and the skin, the more stress concentrates at the adhesive site, causing the patch to peel off easily.

[0030] On the other hand, as shown in Figure 1(b), when the mechanical properties are similar, the stress distribution at the adhesive site becomes uniform, and the adhesion between the film and the skin is stably maintained. Such mechanical properties can be achieved by using a skin-like material such as hydrogel, which is one of the important technical features of the transparent skin patch 1000 having a double-layer structure of the present invention.

[0031] When the hydrogel mixture of the present invention is formed in the form of a film (or patch), i.e., a hydrogel film 10, the hydrogel film 10 adheres strongly to the user's skin and flexibly adheres along the curves of the skin, as shown in Figure 2. Figure 2 is an illustrative diagram illustrating the adhesive force between a film containing the hydrogel mixture and the skin in relation to one embodiment of the present invention. Due to the high water content and flexibility inherent to hydrogels, the hydrogel film 10 can provide a comfortable fit while adhering closely to the skin and can maintain a stable contact area with the skin for a long period of time. Hydrogels commonly used inevitably experience rapid water loss at room temperature, which may somewhat reduce their mechanical properties and adhesive properties. In the case of the hydrogel mixture of the present invention, by utilizing a solvent with high boiling and freezing points that has a negative charge opposite to the positively charged hydrogen of water, each solvent molecule can maintain water for a long time through hydrogen bonding and further provide an antifreeze function.

[0032] Furthermore, the hydrogel film of the present invention can embody mechanical properties similar to those of the human body, particularly facial skin, through the optimization of functional materials. To achieve this, high mechanical properties are provided by adjusting the composition ratio of the hydrogel material to form a double network structure through the interaction and entanglement of polymer chains. Such a double network hydrogel mimics the elasticity and flexibility of skin, and can maintain stable adhesion without putting strain on the skin even when worn for extended periods. In other words, the present invention provides a hydrogel patch having physical properties similar to skin through an optimized composition ratio and reaction mechanism of the material, thereby enabling stable adhesion to the user's skin for extended periods and minimizing the reduction in adhesive strength and peeling phenomena.

[0033] Furthermore, referring to Figure 3, the transparent skin patch 1000 having the double-layer structure of the present invention provides outstanding transparency and remains virtually invisible from the outside even when attached to the skin. Figure 3 is an illustrative diagram showing the actual attachment state of a transparent skin patch associated with one embodiment of the present invention. As shown in Figure 3, the transparent skin patch 1000 having the double-layer structure of the present invention appears to be integrated with the skin, which is achieved by the high transparency of the hydrogel mixture component of the present invention. Conventional patch products are easily noticeable when applied to the skin, which can be an aesthetic burden for the user. However, the transparent skin patch 1000 of the present invention, having a double-layer structure, solves this problem by using a highly transparent hydrogel mixture that maintains its transparency even after being applied to the skin while performing UV blocking and skin protection functions.

[0034] In the embodiment, the transparent skin patch 1000 having the double-layer structure of the present invention appears almost identical to the hue of the skin, minimizing light scattering and making it difficult to recognize the presence of the patch from the outside. As a result, the patch can be used in daily life without aesthetic burden, and maintains transparency even when worn for a long time, enhancing the comfort and aesthetic satisfaction of the user. The following will provide a more detailed explanation of the composition of each layer in the transparent skin patch having a double-layer structure according to the present invention, its effects, and its manufacturing method, with reference to Figures 4 to 6.

[0035] Figure 4 is an illustrative diagram showing a cross-section of a transparent skin patch having a double-layer structure related to one embodiment of the present invention. As shown in Figure 4, the transparent skin patch 1000 having a double-layer structure may include a surface layer 100 and a skin contact layer 200. The transparent skin patch 1000 having a double-layer structure is characterized by having a double-layer structure. The double-layer structure consists of a skin contact layer 200 containing a hydrogel and a surface layer 100 containing an ultraviolet blocking component. The surface layer 100 contains the ultraviolet blocking component of the present invention in a water-soluble form and is stably maintained so as not to be adsorbed to the skin or seep out from the surface, and can continuously provide an ultraviolet blocking effect. In addition, the skin contact layer 200 containing the hydrogel maintains the existing moisture retention capacity and skin adhesion, minimizing skin irritation and maintaining the adhesion effect for a long time. Thus, because the transparent skin patch 1000 having a double-layer structure contains only two layers, the process is simplified, production efficiency is improved, and the thickness is reduced, significantly improving the wearing comfort. The thin and light structure adheres more naturally to the skin, and stable adhesion can be maintained without discomfort even when worn for a long time. Furthermore, because the surface layer 100 contains water-soluble components instead of oil-soluble UV-blocking components, there is no phenomenon of UV-blocking components seeping out, ensuring greater transparency and providing superior effects for cosmetic purposes. As a result, when the user applies the patch, it is hardly noticeable on the skin surface, maximizing UV-blocking performance while simultaneously satisfying aesthetic effects.

[0036] More specifically, a transparent skin patch 1000 having a double-layer structure may be composed of a hydrogel mixture and may include a surface layer 100 that forms the surface. The surface layer 100 maintains transparency while being highly durable, allowing it to protect the patch from external irritants and contamination of the skin. This extends the overall lifespan of the patch and provides moisture evaporation prevention and UV protection even with prolonged use.

[0037] In one embodiment, the surface layer 100 is based on the unique hydrogel mixture of the present invention, thus maintaining a high moisture content and a transparent appearance, and providing a natural adherence to the skin for a comfortable wearing experience. Specifically, the hydrogel mixture of the present invention is manufactured through specific components and a carefully adjusted composition ratio to maximize moisture evaporation suppression and UV blocking functions. Such an optimized composition ratio simultaneously improves the flexibility and durability of the hydrogel, enabling the patch to provide comfortable and stable adhesion even when worn on the skin for extended periods. For example, monomers for the moisture-retaining polymer, along with components such as crosslinking agents and curing agents, can be mixed in appropriate proportions to ensure the structural stability of the hydrogel. As a result, the transparent skin patch of the present invention provides both excellent performance and durability, maintaining effective UV protection and moisture protection even after prolonged use.

[0038] The hydrogel mixture of the present invention may comprise distilled water, acrylamide, a hydrophilic polymer, methylenebisacrylamide (MBA), and ammonium persulfate (APS). In the examples, distilled water acts as the main solvent for the hydrogel, dissolving the polymer components and promoting uniform mixing. The distilled water forms the basis for maintaining the water content of the hydrogel, and together with the added water evaporation inhibitor, it ensures that the hydrogel maintains its flexibility and adhesion.

[0039] Acrylamide is the main monomer of hydrogels and can form the structural basis of them. Acrylamide forms polymer chains through polymerization, a process that determines the mechanical strength and flexibility of the hydrogel. For example, the physical properties of a hydrogel can change depending on its acrylamide content. Hydrophilic polymers may be polymeric substances that have hydrophilic properties and absorb moisture. Hydrophilic polymers play a role in improving moisture absorption and retention capabilities. For example, hydrophilic polymers may include at least one of the following: agarose, chitin, chitosan, gelatin, hyaluronic acid, carboxymethylcellulose (CMC), and polyvinyl alcohol (PVA). Hydrophilic polymers contribute to hydrogels maintaining moisture for extended periods and minimizing skin irritation.

[0040] Methylenebisacrylamide acts as a cross-linker, forming bonds between polymer chains within the hydrogel. These cross-links maintain the structural stability of the hydrogel and increase its mechanical strength, providing robust resistance to external impacts and deformation. In one example, increasing the amount of cross-linker increased the hardness of the hydrogel, but excessive amounts may reduce the flexibility of the hydrogel. Therefore, it is crucial to adjust the amount of cross-linker to an appropriate level.

[0041] Ammonium persulfate acts as a radical initiator, initiating the polymerization of acrylamide. It accelerates the chemical reaction, helping the hydrogel to form rapidly and stably. Furthermore, ammonium persulfate plays a crucial role in the curing process of the hydrogel, contributing to the stable maintenance of its morphology and structure. The hydrogel mixture of the present invention is designed with an optimized and original recipe, which maximizes various properties such as skin adhesion, flexibility, moisture retention, and transparency.

[0042] In the examples, distilled water is provided in an amount of 50 to 55 parts by weight per 100 parts by weight of the hydrogel mixture, acting as the main solvent for the hydrogel and forming an important basis for maintaining moisture content along with uniform mixing of the components. The optimized ratio of distilled water helps the film adhere to the skin for a long time while maintaining the moisture content of the hydrogel. Acrylamide is present in an amount of 40 to 45 parts by weight per 100 parts by weight of the hydrogel mixture, and contributes as a monomer to form the structural base of the hydrogel. The proportion of acrylamide provides a good balance of strength and flexibility in the hydrogel, resulting in a comfortable fit when attached to the skin and durability that can withstand external impacts.

[0043] Hydrophilic polymers are present in an amount of 5 to 10 parts by weight per 100 parts by weight of the hydrogel mixture. They maximize the water absorption capacity of the hydrogel, minimizing skin irritation and preventing skin dryness even during prolonged use. Among these hydrophilic polymers, agarose, chitin, chitosan, and gelatin maximize compatibility with the skin while maintaining moisture, thereby improving the skin-protective effect of the hydrogel. Methylenebisacrylamide is present in an amount of 0.025 to 0.030 parts by weight per 100 parts by weight of the hydrogel mixture and acts as a crosslinking agent to form bonds between the polymer chains of the hydrogel. Such a ratio may be optimized to maintain the structural stability of the hydrogel without losing flexibility. Excessive use of crosslinking agents can reduce flexibility, but in this invention, flexibility and strength are simultaneously ensured through careful adjustment.

[0044] Ammonium persulfate is provided in an amount of 0.125 to 0.130 parts by weight per 100 parts by weight of the hydrogel mixture, and acts as a radical initiator to promote the polymerization reaction of the hydrogel. Such a ratio ensures that the hydrogel hardens rapidly and stably, and that it functions stably even when adhered to the skin while maintaining its form.

[0045] The optimized component ratio of the hydrogel mixture described above ensures that the hydrogel of the present invention has properties that differentiate it from existing products, providing performance as an innovative skin patch that maximizes moisture retention and skin affinity while maintaining transparency and adhesion. In the examples, the surface layer 100 may be provided on one surface of the skin contact layer 200 and may contain a water-soluble ultraviolet blocking mixture that provides ultraviolet blocking functionality. The surface layer 100 can be formed by mixing a water-soluble UV-blocking mixture that provides UV-blocking functionality with a hydrogel mixture. More specifically, the surface layer 100 can contain the hydrogel mixture of the present invention as is, while being uniformly mixed with a water-soluble UV-blocking mixture containing a water-soluble UV-blocking component to provide UV-blocking performance along with skin adhesion and moisture retention.

[0046] The surface layer 100 of the present invention may be constructed by uniformly mixing a water-soluble UV-blocking mixture with a hydrogel mixture. Through such a structure, the UV-blocking components contained in the surface layer are maintained on the skin for a long period of time, providing a sustained protective effect against UV-A and UV-B. In specific examples, the surface layer 100 may contain a water-soluble UV-blocking mixture containing UV-blocking components such as ecamsule and disodium phenyl dibenzimidazole tetrasulfonate (DPDT), which is uniformly mixed with the hydrogel mixture to maximize UV-blocking performance. Each UV-blocking component is blended in an optimal proportion within the mixture to maximize the UV-blocking effect, which can simultaneously provide high transparency and protection without irritating the skin.

[0047] In particular, ekamsul has a high absorption rate mainly in the UVA region of 320-360 nm, and DPDT exhibits excellent blocking performance in the UVB region of 280-320 nm. Therefore, the two components work in complementary wavelength bands to achieve a wide range of UV blocking. The complementary combination of ekamsul and DPDT can stably provide UV protection across the entire range, which is difficult to achieve with a single component alone.

[0048] The water-soluble UV-blocking mixture containing the aforementioned UV-blocking components forms a surface layer together with the hydrogel mixture of the present invention, maximizing UV-blocking performance while maintaining skin adhesion and moisture retention. UV-A can penetrate deep into the skin and induce wrinkles and skin aging, while UV-B is the main cause of sunburn on the skin surface. The patch of the present invention effectively prevents skin damage by blocking both UV-A and UV-B. More specifically, ekamusul may be included in an amount of about 20 to 25 parts by weight per 100 parts by weight of the water-soluble UV-blocking mixture and is effective in blocking UV-A. Ekamusul plays a role in preventing skin aging and wrinkle formation by blocking UV-A that penetrates deep into the skin. Phenyldibenzimidazole tetrasulfonate disodium may be included in an amount of about 10 to 15 parts by weight per 100 parts by weight of the water-soluble UV-blocking mixture and acts as an ingredient that can effectively block both UV-A and UV-B. The ratio of these UV-blocking components is precisely adjusted to maximize UV ​​protection performance. Each component is uniformly mixed with the hydrogel mixture to form a surface layer, ensuring even distribution on the skin surface. This provides sustained UV protection while simultaneously maximizing moisture retention and skin adhesion. When a water-soluble UV-blocking mixture containing such UV-blocking components is mixed with the original hydrogel mixture of the present invention, the surface layer 100 performs a dual function of maximizing UV-blocking function while simultaneously providing skin adhesion and moisture retention. The hydrogel mixture helps to ensure that the UV-blocking components are stably delivered to the skin, while also providing a comfortable fit even when the patch is in contact with the skin for extended periods. Therefore, the surface layer 100 combines an optimized ratio of UV-blocking components with the flexibility and moisture-retaining properties of the hydrogel, allowing the patch to effectively perform its UV-blocking function for a long period of time while also adhering naturally to the skin and retaining moisture.

[0049] According to one embodiment of the present invention, the surface layer 100 may be characterized by being composed of a mixture of a water-soluble UV-blocking mixture and a hydrogel mixture in a ratio range of 20 parts by weight:80 parts by weight to 30 parts by weight:70 parts by weight, respectively. For example, if the water-soluble UV-blocking mixture and the hydrogel mixture are not mixed in an appropriate ratio according to one embodiment of the present invention, the balance between UV-blocking performance and moisture retention may be disrupted. For example, if the ratio of the UV-blocking component is excessively high, the flexibility and adhesion of the hydrogel may decrease, which may increase the likelihood that the patch will not adhere stably to the skin and will easily peel off. Conversely, if the ratio of the hydrogel mixture is excessively high, the UV-blocking component may not be sufficiently distributed to the skin, and the UV-blocking performance may decrease. Since such an imbalance in ratios can reduce the performance of the patch, it is important to maintain an appropriate ratio between the water-soluble UV-blocking mixture and the hydrogel mixture. This combination of ratios optimizes the balance between the UV-blocking components and the hydrogel mixture, maximizing both UV-blocking performance and skin adhesion simultaneously. Specifically, the water-soluble UV-blocking mixture provides UV protection through its water-soluble UV-blocking components, while the hydrogel mixture minimizes irritation by adhering to the skin for extended periods through its moisture retention and flexibility. The ratio range of these two mixtures is designed to ensure that the UV-blocking components are effectively delivered to the skin while the high water content of the hydrogel reduces skin irritation and maintains moisturizing effects. Furthermore, this ratio setting ensures that the patch adheres stably to the skin even when used for extended periods, and that the UV-blocking components are uniformly dispersed within the hydrogel layer without leaching out, providing sustained protection from ultraviolet rays.

[0050] According to embodiments of the present invention, the surface layer 100 may further comprise zinc oxide (ZnO). Specifically, zinc oxide may be additionally included in a water-soluble ultraviolet-blocking mixture composed of ecamsul and disodium phenyldibenzimidazole tetrasulfonate. In the examples, zinc oxide is dispersed in nanoparticle form to maximize its ultraviolet blocking performance, which allows it to effectively absorb and reflect ultraviolet light. Figure 5 is an illustrative diagram illustrating the inclusion of nanoparticle-form zinc oxide in a surface layer associated with one embodiment of the present invention. As shown in Figure 5, zinc oxide 110 is dispersed in nanoparticle form having nanoscale, performing a role in blocking ultraviolet light (UV-A and UV-B) over a wide range.

[0051] Zinc oxide can cover the entire ultraviolet region from 280 nm to 400 nm, and exhibits particularly excellent blocking performance in the high-wavelength UVA region around 380 nm, where the absorption of organic UV blockers decreases sharply.

[0052] In the case of water-soluble organic UV-blocking components such as ecamsul and DPDT, they generally exhibit high absorption rates up to around 360 nm, but there is a limit where the blocking rate drops sharply in the wavelength range above 380 nm, which may limit their blocking effect against high-wavelength UVA.

[0053] On the other hand, zinc oxide can maintain stable and sustained blocking performance even against ultraviolet light above 380 nm through physical reflection and scattering mechanisms, thus effectively compensating for the limitations of such organic filters. Furthermore, nano-sized zinc oxide particles possess excellent UV reactivity due to their high surface area, acting as a core component that fills in blind spots in the UV blocking range while maintaining the transparency of the patch. Nano-sized zinc oxide particles physically reflect or scatter ultraviolet light, increasing the length through which it passes through the layer. This effect enhances UV absorption by UV-blocking agents, effectively reducing the amount of UV light reaching the skin. The small nanometer-level particles have a high surface area, further improving UV blocking performance and maximizing UV protection while maintaining the transparency of the patch.

[0054] In one embodiment, zinc oxide nanoparticles having a size of 15 nm to 35 nm can be used. However, the smaller the size of the zinc oxide nanoparticles used, the more times light is reflected and scattered within the contained layer, and as a result, the length of UV light transmission is increased, thereby increasing the UV blocking capacity per unit concentration. The size of the zinc oxide nanoparticles plays an important role in maximizing UV blocking performance while maintaining the transparency of the patch. In particular, a small particle size of 15 nm enhances UV blocking performance, effectively blocking not only UV-B but also UV-A, while maintaining the transparency of the patch and providing aesthetic satisfaction during use. For example, if the size of the zinc oxide nanoparticles is large, the UV blocking performance of the layer may decrease or the transparency of the patch may decrease, so the size of the zinc oxide nanoparticles used can play an important role in providing optimal UV blocking performance and transparency.

[0055] In the examples, the particles may be comprised of at least one of the following shapes: spherical, plate-like, rod-like, and irregular, each of which shape affects the UV-blocking performance of zinc oxide. For example, spherical particles have the property of scattering light uniformly, while rod-like particles scatter light in specific directions, enabling more efficient UV blocking. Such combinations of nanoparticle shapes allow the patch to adhere naturally to the skin and maintain a transparent appearance while blocking ultraviolet rays. Furthermore, the embodiment may include a skin contact layer 200 that contacts one surface of the surface layer 100 and is composed of a hydrogel mixture. The skin contact layer 200 contacts one surface of the surface layer 100 and may be composed of the hydrogel mixture of the present invention. Due to the flexibility and moisture retention capacity of the hydrogel, the skin contact layer provides a comfortable wearing experience while adhering closely to the skin for extended periods, minimizing skin irritation.

[0056] Furthermore, the skin contact layer may contain drug delivery components, thereby providing not only skin protection but also skin health improvement functions. For example, the skin contact layer 200 may contain components such as collagen, panthenol, hyaluronic acid, and vitamin C, which can provide increased skin elasticity, moisturizing, wrinkle improvement, and whitening effects. For example, collagen increases skin elasticity, panthenol promotes skin regeneration and hydration, hyaluronic acid maintains skin moisture, and vitamin C contributes to skin whitening and wrinkle improvement through its antioxidant effects.

[0057] In addition to the aforementioned ingredients, the product may also contain ingredients that provide soothing and anti-inflammatory effects, such as aloe vera extract and green tea extract, as well as anti-aging ingredients like retinol and niacinamide. Antibacterial and wound-healing ingredients such as tea tree oil and salicylic acid may also be added, and a variety of functional ingredients such as antioxidants, whitening agents, and moisturizers may be included as needed. Therefore, the skin contact layer 200 of the present invention provides skin adhesion and moisture retention based on a hydrogel mixture, while also performing functions such as effective nutrient delivery, elasticity improvement, moisturizing, and soothing as a drug delivery system. As described above, the transparent skin patch 1000 of the present invention, having a double-layer structure, effectively blocks ultraviolet rays as an ultraviolet blocking layer in the surface layer 100, thereby protecting the skin from ultraviolet rays. Furthermore, the double-layer structure minimizes the patch thickness while effectively maintaining both UV protection and skin adhesion. The double-layer structure improves process efficiency, reduces patch thickness for a better wearing experience, and allows for natural adhesion to the skin. Additionally, enhanced adhesion ensures the patch remains stable on the skin for extended periods, and the absence of lipid-soluble UV-blocking components may further improve transparency.

[0058] Furthermore, the transparent skin patch 1000, having a double-layer structure, contains the hydrogel mixture of the present invention in all layers, ensuring moisture retention, excellent adhesion, and high transparency. Due to the properties of the hydrogel, the patch adheres naturally to the skin, retaining moisture even during prolonged use and minimizing skin irritation. As a result, the transparent skin patch 1000, having a double-layer structure, provides a comfortable wearing experience while maintaining stable adhesion over a long period of time.

[0059] Furthermore, the skin contact layer 200 can additionally perform drug delivery functions, allowing functional ingredients such as collagen, panthenol, and hyaluronic acid to be effectively delivered to the skin. Through this, various skin improvement effects such as increased skin elasticity, moisturizing effects, and skin soothing can be expected.

[0060] In other words, the transparent skin patch 1000 having a double-layer structure of the present invention is a highly functional multilayer patch that ensures UV protection, moisture retention, adhesion, and transparency, while also performing skin improvement functions through drug delivery, providing outstanding effects for skin protection and management.

[0061] Figure 6 shows an exemplary flowchart of a method for manufacturing a transparent skin patch having a double-layer structure related to one embodiment of the present invention. The steps shown in Figure 6 may be changed in order as necessary, and at least one or more steps may be omitted or added. That is, the following steps are only one embodiment of the present invention, and the scope of the present invention is not limited thereto. According to one embodiment of the present invention, a method for manufacturing a transparent skin patch having a double-layer structure may include a step (S100) of generating a skin contact layer.

[0062] More specifically, the skin contact layer 200 can be produced using a hydrogel mixture, in which the hydrogel components are uniformly mixed and formed in film form. To produce the skin contact layer 200, first, a hydrogel mixture containing distilled water, acrylamide, a hydrophilic polymer, methylenebisacrylamide, and ammonium persulfate is prepared. The hydrogel mixture allows the hydrogel to adhere to the skin while forming the basic structure of the patch. For uniform formulation of the hydrogel mixture, a heating and mixing process is carried out at an appropriate temperature, during which a cross-linking reaction can occur and optimize the mechanical strength and flexibility of the hydrogel.

[0063] Subsequently, the skin contact layer 200 is cast or molded in film form to form a layer with the desired thickness and structure. At this stage, the film is controlled to maintain its moisture content, and drug delivery components may be added. The drug delivery components, along with the hydrogel, are slowly absorbed into the skin to provide a skin improvement effect. Therefore, the skin contact layer can be manufactured with a hydrogel mixture as the base, possessing a structure that provides skin adhesion, moisture retention, and drug delivery capabilities.

[0064] According to one embodiment of the present invention, a method for manufacturing a transparent skin patch that adheres to the user's skin may include the step (S200) of generating a surface layer 100 on one surface of a skin contact layer 200. According to the examples, the step of generating the surface layer 100 may include the step of generating a water-soluble UV-blocking mixture. Here, the water-soluble UV-blocking mixture can mean a mixture containing UV-blocking components that are responsible for the UV-blocking function in the surface layer. In specific examples, the steps of producing a water-soluble UV-blocking mixture may include: adding ecamsul, disodium phenyldibenzimidazoletetrasulfonate, and zinc oxide to distilled water and dissolving them to produce an initial mixture; adjusting the pH of the initial mixture using an acid and a base such as citric acid or sodium hydroxide; and adding a humectant and a stabilizer to the pH-adjusted initial mixture to produce a water-soluble UV-blocking mixture.

[0065] More specifically, the step of producing a water-soluble UV-blocking mixture involves the following process: First, to produce a water-soluble UV-blocking mixture, ecamsul, disodium phenyldibenzimidazole tetrasulfonate, and zinc oxide are added to distilled water to form an initial mixture. According to the examples, the combination of the three components described above can mutually expand the ultraviolet blocking region, enabling ultraviolet blocking effects over a wide wavelength range (280-400 nm) that would be difficult to achieve with each component alone. Specifically, ekamsul exhibits excellent absorption in the UVA region (320-360 nm), DPDT has specialized blocking performance for UVB (280-320 nm), and zinc oxide provides stable blocking performance through reflection and scattering, especially for high-wavelength UVA regions above 380 nm. Therefore, the combination of these three components is advantageous for creating high-performance UV blocking that eliminates blind spots in UV blocking and maintains a uniform blocking rate across the entire range.

[0066] Furthermore, the aforementioned combination, by simultaneously utilizing the advantages of both water-soluble organic and inorganic filters, can also achieve additional effects such as maintaining skin transparency, reducing irritation, and improving photostability. The initial mixture formation stage is a crucial step in helping the UV-blocking components dissolve and disperse uniformly. Subsequently, an acid and a base, such as citric acid or sodium hydroxide, are used to adjust the pH of the initial mixture to a skin-friendly range. During this process, the pH is set within a range that allows the UV-blocking components to act stably while minimizing skin irritation.

[0067] After pH adjustment is complete, humectants and stabilizers are added to finalize the water-soluble UV-blocking mixture. The humectants help retain moisture for extended periods when the patch is applied to the skin, preventing dryness, while the stabilizers ensure the mixture remains stable for a long time. The resulting water-soluble UV-blocking mixture provides effective UV protection to the skin by ensuring uniform distribution and stable maintenance of the UV-blocking components. Furthermore, in specific embodiments, the steps for generating the surface layer may include: adding acrylamide and a hydrophilic polymer to distilled water to generate an initial mixture; adding methylenebisacrylamide to the initial mixture and performing mixing; adding a water-soluble ultraviolet-blocking mixture to the initial mixture containing methylenebisacrylamide and performing mixing; adding ammonium persulfate to the mixing mixture and performing a mixing process; and using the final mixture after mixing as a base to perform a film formation process to generate a surface layer in film form and perform curing.

[0068] More specifically, the process of generating the surface layer may include the following steps: First, an initial mixture is prepared by adding acrylamide, a hydrophilic polymer (e.g., agarose), and zinc oxide to distilled water, mixing them, and then dissolving them on a 90°C hotplate. At this stage, the polymeric substance that forms the basis of the hydrogel is dissolved, and the zinc oxide acts as a UV-blocking component. At this time, the size of the zinc oxide particles is set to 15 nm to 30 nm, which can improve UV-blocking performance while maintaining the transparency of the patch.

[0069] Subsequently, the mixed solution (i.e., the initial mixture or aqueous phase) is agitated for approximately 10 seconds using a high-frequency processing machine to make the mixture more uniform. Then, methylenebisacrylamide (MBA) is added to the initial mixture and stirred. Methylenebisacrylamide acts as a crosslinking agent, contributing to the formation of the hydrogel's structural strength.

[0070] Next, the water-soluble UV-blocking mixture is added to the initial mixture and mixed in a Thinky mixer for approximately 20 to 40 seconds, after which the mixing process is carried out in a shear mixer. During this process, the two phases are uniformly mixed, and the UV-blocking component is uniformly distributed within the hydrogel.

[0071] Finally, after injecting ammonium persulfate (APS), the mixture is mixed again to create a film-shaped surface layer. For example, a stable and uniform film can be completed through a mixing process to quickly and uniformly mix the APS after injection, a casting process to form the film, and a heat treatment process to cure it. Ammonium persulfate acts as a radical initiator to promote the formation of polymer chains and helps the hydrogel to cure rapidly. The fabricated patch is cured in a 70°C oven for 40 to 1 hour to complete the process. In this process, the content of each component and the processing conditions are important factors that determine the final physical properties of the hydrogel, and through this, a surface layer with optimized transparency, UV blocking performance, adhesion, and moisture retention can be produced.

[0072] Through the aforementioned process steps, a transparent skin patch 1000 having a double-layer structure according to the present invention can be manufactured. The manufactured transparent skin patch 1000 can adhere to the skin for a long period of time and provides high moisture retention and excellent transparency. In addition, the UV-blocking component contained in the surface layer of the patch protects the skin from ultraviolet rays for a long time, and the surface layer prevents the UV-blocking component from seeping out to the outside, thereby enhancing the persistence of the UV-blocking effect. Furthermore, the skin contact layer is composed of a skin-friendly hydrogel mixture, minimizing skin irritation, and can also provide skin improvement effects by containing various drug delivery components as needed. Whether the transparent skin patch 1000 having a double-layer structure of the present invention exhibits UV blocking effect, skin adhesion, and moisture retention effect can be confirmed through the following experimental examples.

[0073] <Experimental Example 1: Adhesion Ability Test> This experiment aims to confirm the adhesive ability of patches produced through the hydrogel mixture of the present invention to adhere to skin. Through this, we evaluated how stably a hydrogel material with a Young's modulus similar to that of skin maintains its adhesion on a real skin surface. The materials used in this experiment included a patch to which the hydrogel material of the present invention was applied, and porcine skin having physical properties similar to human skin. The adhesive strength of the hydrogel patch of the present invention was evaluated using porcine skin under conditions similar to those of human skin. Test equipment such as an adhesion tester, strain gauge, and high-resolution microscope were used to measure the adhesive strength. First, after cleaning the surface of the pig's skin, a transparent patch coated with the hydrogel material of the present invention was attached to the pig's skin surface. After applying light pressure to fix the hydrogel patch in place so that it was completely in contact with the skin surface, an adhesion test was performed. To evaluate the adhesive strength of the hydrogel patch, the stress (kPa) due to strain (%) was measured. The results showed that even with a strain close to 200% in the strain test, the hydrogel patch adhered strongly to the pig's skin, and the adhesive strength did not decrease significantly. Strain (%) represents the deformation rate and indicates how much the hydrogel patch can stretch. In other words, it is expressed as a percentage of how much the patch can stretch while attached to the skin. Stress (kPa) indicates the degree to which the hydrogel patch resists pressure or force applied while attached to the skin and is an important indicator for evaluating adhesion strength.

[0074] As shown in the graph in Figure 7, stress increases with increasing strain, but even with strain close to 200%, the adhesive strength (stress) of the hydrogel patch did not decrease significantly. This indicates that the hydrogel patch maintains its adhesive strength stably even when the skin deforms, i.e., when the skin stretches or moves. From this, we can conclude that the hydrogel patch can maintain stable adhesive strength even when used for a long time in close contact with the skin. In other words, it means that the hydrogel patch maintains strong adhesive strength even with skin movement and stretching. Furthermore, adhesive strength tests recorded a shear stress of 36 kPa, indicating that the hydrogel patch maintains strong adhesion to the skin. This strong adhesion is attributed to the hydrogel material's moisture retention and flexibility, which ensured its long-lasting performance. Finally, microscopic observation of the close bond between the pig skin and the hydrogel patch confirmed that a covalent bond was formed between the hydrogel patch and the pig skin, resulting in strong adhesion to the skin surface. This type of bonding structure significantly improves the adhesive performance of the hydrogel. As a result, this experiment demonstrated that the hydrogel patch of the present invention exhibits strong adhesion under conditions similar to those of skin and maintains a stable adhesion even during prolonged use. Furthermore, the high water content and flexibility of the hydrogel material resulted in excellent adhesive performance in strain tests.

[0075] <Experimental Example 2: Biocompatibility Test> The biocompatibility test was an experiment to confirm whether the hydrogel material of the present invention is compatible with the biological environment when it is attached to the skin for an extended period of time, and was performed through in vitro cell experiments. The NIH 3T3 cell line was used in the experiment, and these cells play an important role in skin regeneration and healing as skin fibroblasts. First, in the experimental preparation process, the hydrogel of the present invention was placed as a sample on a culture dish containing NIH 3T3 cells, as shown in Figure 8. The hydrogel was attached to the culture dish so that it could come into direct contact with the cells, and the experiment proceeded in a manner that evaluated the interaction between the cells and the hydrogel. During the experiment, a high-resolution microscope and fluorescence staining were used to confirm cell growth and any deformation. Cell viability and morphological changes were visually confirmed through fluorescence staining, and it was also evaluated whether the hydrogel material induced toxicity in the cells. As shown in Figure 8, the experimental results demonstrated that the hydrogel material of the present invention did not induce cytotoxicity, and NIH 3T3 cells survived and proliferated normally. In particular, the hydrogel material maintained its non-swelling properties and showed almost no structural deformation even when in prolonged contact with cells, demonstrating that it does not excessively absorb moisture or deform even when used in the body environment for extended periods. Furthermore, it was possible to confirm that cells differentiated and grew normally on the hydrogel surface. Through this process, we confirmed that the hydrogel material of the present invention does not cause problems even when it is in contact with the skin for a long period of time and acts harmlessly on the human body.

[0076] <Experiment Example 3: Evaluation of Skin Moisture Retention and Adhesion> This study was conducted to evaluate the moisturizing effect, adhesion, UV protection effect, and other skin-improving effects of the transparent skin patch of the present invention when applied to actual human skin. The experiment involved 20 adult women aged 30 to 60 years (average age 50.05 ± 6.08 years), all of whom met the research participation criteria and were selected for their normal skin condition. The experiment was conducted on the face (around the eyes) and forearm (upper arm), and the subjects applied the transparent skin patch of the present invention once a day. First, in the facial experiment, the patch was applied to the area from the cheekbone to the temple after washing and drying the face, and was left on for 4 hours before being removed. Additionally, to evaluate the skin temperature reduction (cooling) effect, the product was applied to both sides of the face, using the nose as a reference point, and removed after 15 minutes. In the forearm experiment, a 4cm x 4cm patch was applied and left on for 4 hours before being removed. Skin moisturizing ability was evaluated by comparing skin moisture content before and after patch application. Moisturizing duration was checked over 24 hours, and the results showed that the patch of the present invention effectively maintained high skin moisture content for 24 hours after application. The results of the 24-hour moisturizing duration check showed that the patch of the present invention increased skin moisture content by an average of 35%, and maintained a moisture retention capacity that was 28% or more higher even after 24 hours. The UV blocking effect was evaluated by measuring the blocking performance against UV-A and UV-B rays, and the results confirmed that it effectively protects against UV rays that induce skin irritation. The UV blocking effect was evaluated by measuring the blocking performance against UV-A and UV-B rays, and the UV protection factor (SPF) recorded was 50 or higher. It showed an average blocking effect of more than 95% against UV rays that induce skin irritation. Furthermore, the adhesion strength after exercise was evaluated by measuring the patch's adhesion after subjects exercised on a treadmill for 30 minutes. In the experiment, the patch's state before and after adhesion was recorded and analyzed using a strain gauge and a high-resolution camera. The degree to which the patch remained firmly attached was confirmed through the strain generated on the skin where the patch was attached, and the degree to which the patch's adhesion was maintained by sweat after exercise was evaluated. The adhesion maintenance rate was calculated based on the ratio of the area where the patch did not peel off and remained in contact with the skin, and the average adhesion maintenance rate after patch attachment was measured at 98%. This value was calculated considering the ratio of the area where the patch peeled off or the adhesion weakened relative to the skin contact area, demonstrating that the patch of the present invention maintains strong adhesion even with sweat generated during exercise. The improvement in skin tone and the reduction of dark circles (under-eye circles) were assessed through subjective evaluations by research participants and professional skin analysis equipment. Two weeks after patch application, over 80% of users reported a more uniform improvement in skin tone, and over 75% reported a positive reduction in dark circles. User satisfaction was high due to the transparent patch's ease of use in daily life, with over 90% of users citing its transparency and inconspicuousness as its greatest advantages. Furthermore, over 85% of users experienced rapid relief of skin irritation after patch application due to the soothing effect of the patch.

[0077] <Experimental Example 4: UV Blocking Test of DPDT Hydrogel> This experiment was conducted to investigate the effect of hydrogel mixtures containing phenyldibenzimidazole tetrasulfonate disodium (DPDT) on UV blocking performance. In the experiment, hydrogel patches were prepared by varying the DPDT content to 20 mg, 10 mg, and 5 mg, and the UV blocking performance of each sample was evaluated. The hydrogel mixture used in the experiment consisted of 8 g of distilled water (DIW), 5.4 g of acrylamide, 0.72 g of agarose, 0.007 g of methylenebisacrylamide (MBA, 2X concentration), and 0.0035 g of ammonium persulfate (APS, 2X concentration). Each composition was mixed sequentially. First, agarose was added to the distilled water and stirred at approximately 65°C until it was completely dissolved and clear. Then, acrylamide was added, and stirring was continued at the same temperature to ensure homogeneous mixing. Because it contains a UV-blocking agent, DPDT was added separately to the sample at concentrations of 20 mg, 10 mg, and 5 mg, respectively, and stirred for a sufficient amount of time to ensure that the DPDT was uniformly dispersed in the hydrogel solution. Then, MBA and APS, which had been prepared in advance by diluting them in distilled water, were added to the mixture at a ratio of 350 μL each, and gently mixed again to prepare for the reaction. The mixed hydrogel composition was uniformly applied onto a 75 μm PET film using a bar coater. The applied film was then cured on a 65°C hot plate for approximately 10 minutes to complete a hydrogel-type UV-blocking patch. Each completed sample was mounted on an ultraviolet blocking rate measuring device, and the ultraviolet blocking rate was measured in the wavelength range from 240 nm to ~420 nm. Referring to Figure 9, the sample containing 20 mg of DPDT showed an average ultraviolet blocking rate of over 99.9%, the sample containing 10 mg showed approximately 90.6%, and the sample containing 5 mg showed approximately 91.4% blocking performance. According to the measured spectral results, all samples maintained a stable high blocking rate in the wavelength band below 360 nm, but a decrease in absorption rate was observed in some samples in the high-wavelength UVA region above 380 nm. These results suggest that while the overall UV blocking effect tends to improve as the concentration of DPDT increases, the difference is not significant above a certain level.

[0078] <Experimental Example 5: UV Blocking Test of Ekamusul and Zinc Oxide (ZnO) Based Hydrogels> This experiment aimed to confirm the UV blocking performance of hydrogel films containing ecamsule and zinc oxide (ZnO), and quantitatively evaluated how the UV blocking effect changes depending on the concentration of each component and whether or not they are combined. The hydrogel composition consisted of 8 g of distilled water, 5.4 g of acrylamide, 0.72 g of agarose, 0.007 g of methylenebisacrylamide (MBA), and 0.0035 g of ammonium persulfate (APS). First, agarose was added to the distilled water and completely dissolved at 65°C, then acrylamide was added and the mixture was stirred to maintain transparency. Subsequently, Ekamsul was added to the samples in concentrations of 2 mg, 5 mg, 10 mg, and 20 mg, and samples with 0.11 g of zinc oxide (ZnO, average particle size 30 nm) added under separate conditions were also prepared. 350 μL of MBA and APS, pre-diluted in distilled water, were added to each composition, and the mixture was gently stirred to ensure uniform dispersion. The completed mixture was evenly applied to a 75 μm thick transparent PET film using a bar coater in a 4 cm x 4 cm area, and cured on a 65°C hot plate for approximately 10 minutes to form an ultraviolet-blocking hydrogel film. The UV blocking performance was measured via a UV / VIS spectrophotometer in the wavelength range of 240 nm to 420 nm, and the UV blocking rate (%) and absorbance of each sample were analyzed. Referring to Figure 10, the measurement results showed that when ekamsul was contained in 20 mg, a high blocking rate of over 90% was maintained for UV light below 360 nm, but above 380 nm, the absorbance decreased sharply, and the blocking performance fell to below 40%. On the other hand, the sample containing zinc oxide maintained a stable blocking performance of over 80% on average over a wide UV range from 280 nm to 400 nm. These results confirmed that while ekamsul exhibits a strong blocking effect in the 320-360 nm UVA region, its performance rapidly decreases at higher wavelengths of UVA (especially above 380 nm), indicating a limit to its effectiveness. In contrast, zinc oxide demonstrated that it can effectively complement the blind spots in ekamsul's UV blocking capabilities by exhibiting sustained blocking ability even in the higher wavelength UVA region through physical reflection and scattering. In conclusion, the combination of ecumsul and zinc oxide can extend the UV blocking range to 260-400 nm, and in particular, it can maintain blocking performance up to high wavelengths. This combination of the two components provides a highly advantageous configuration for maximizing the effectiveness of skin hydrogel UV blocking films.

[0079] <Experiment Example 6: Comparative Experiment on the UV / VIS Spectroscopy Board's UV Blocking Performance> This experiment was conducted to determine how the UV absorption and transmission properties of a hydrogel patch change depending on the type and concentration of UV-blocking components. To this end, hydrogel films containing each component were fabricated, and their optical properties in the UV region (200-400 nm) were quantitatively analyzed using a UV / VIS spectrophotometer. The sample used in the experiment consisted of a total of five items, as follows: - Hydrogel 1: Contains 0.11g of ZnO (30nm) - Hydrogel 2: Contains 20mg of Ecamsule - Contains Hydrogel 3:Ecamsule 10mg - Contains Hydrogel 4:Ecamsule 5mg - Contains Hydrogel 5:Ecamsule 2mg Each sample was prepared using the same hydrogel composition (distilled water, acrylamide, agarose, MBA, APS), differing only in the UV-blocking component. These samples were then coated onto a PET film under identical conditions and cured at 65°C for 10 minutes to produce a film. Subsequently, UV / VIS spectroscopy measurements were performed targeting the ultraviolet wavelength range. UV / VIS spectroscopy primarily involved analysis in the 200-400 nm range, comparing absorbance and transmittance, and the results are shown in Figure 11.

[0080] Absorbance analysis results - 200~280nm (UVC region): High absorbance values ​​were observed in all samples containing Ecamsule or ZnO, which means that ultraviolet light can be effectively absorbed and blocked in this wavelength range. - 280~400nm (UVB / UVA region): Only Hydrogel 1, which contains ZnO, and Hydrogel 2, which has a high ecamsul content, maintained stable absorbance. For Hydrogels 3-5, which have low ecamsul concentrations, the absorbance values ​​tended to decrease sharply. This indicates insufficient UV blocking performance in the high-wavelength ultraviolet region, and in particular, the absorption limit in the 360-400 nm region was clearly observed. Transmittance analysis results - Below 280nm: The transmittance was close to 0% for all samples, meaning no light passed through, indicating that ultraviolet light was strongly absorbed at this wavelength. - Above 280 nm: Transmittance gradually increased in most samples, and particularly high transmittances of over 50% were observed in samples with low concentrations of ecumsul. This suggests a significant decrease in the UV blocking effect at this wavelength. On the other hand, Hydrogel 1 containing ZnO maintained low transmittance across the entire 280-400 nm range, demonstrating stable UV blocking performance. conclusion Hydrogels containing ecamsule were confirmed to effectively block ultraviolet light in the UVC region of 200–280 nm. However, in the higher wavelength region of 280–400 nm, absorbance and transmittance analysis clearly showed a decrease in blocking performance. This trend was particularly pronounced at lower ecamsule concentrations. In contrast, the hydrogel containing ZnO (30 nm) maintained high absorbance and low transmittance even in the 280-400 nm region, and analysis showed that it could stably ensure UV blocking performance of 80% or more in that range. Therefore, to maximize the UV blocking effect, a hydrogel composition is required that either includes an inorganic UV blocking agent such as ZnO, or ensures a sufficient concentration of an organic filter such as ecumsul. In particular, this experiment demonstrates that the combined use of ZnO is essential to block UVA wavelengths (380 nm and above).

[0081] <Experimental Example 7: Evaluation of UV blocking performance of hydrogel films on Ecamsule and DPDT substrates> This experiment involved preparing hydrogel films containing the water-soluble UV-blocking agents ecamsule and phenyldibenzimidazole tetrasulfonate disodium (DPDT), and then comparing and analyzing their UV absorption performance using a UV / VIS spectrophotometer (200-500 nm range). Through this experiment, the aim was to quantitatively understand the wavelength-specific absorption characteristics of each UV-blocking component and to clearly evaluate the UV-blocking range of the hydrogel films. The sample used in the experiment consisted of the following six items. - Sample 1: Contains DPDT 20mg - Sample 2: Contains DPDT 10mg - Sample 3: Contains 5mg of DPDT - Sample 4: Contains 20mg of Ecamsule - Sample 5: Contains 10mg of Ecamsule - Sample 6: Contains Ecamsule 5mg Each sample was prepared as a hydrogel film for UV / VIS analysis by adding the above-mentioned UV-blocking agent to the same hydrogel composition (distilled water, acrylamide, agarose, MBA, APS) at different concentrations, mixing the mixture, coating it onto a 75 μm PET film, and curing it at 65°C for 10 minutes. As shown in Figure 12, all samples exhibited absorbance peaks in the approximately 280-400 nm range, but differences in absorbance characteristics were observed depending on the component and concentration. DPDT-containing samples (Samples 1-3) Sample 1 (DPDT 20mg, black line) Absorbance increased sharply in the 280-320 nm range, reaching a peak of 0.8, and was maintained in the 320-360 nm range. Absorbance increased somewhat more gradually around 340-360 nm, and then decreased sharply above 380 nm, falling to below 0.1. This indicates that DPDT can absorb a considerable amount not only in the UVB (280-320 nm) range but also in the mid-wavelength UVA (320-360 nm) range. Sample 2 (DPDT 10mg, red line) The peak absorbance was slightly lower than that of Sample 1, recording approximately 0.6-0.7. Absorbance increased sharply in the 280-320 nm range, was maintained gradually from 320-360 nm, but decreased rapidly after 360 nm, and almost no absorbance was observed above 380 nm. This suggests that the UVB / UVA absorption capacity relatively decreases with decreasing DPDT concentration. Sample 3 (DPDT 5mg, blue line) The maximum absorbance was approximately 0.5, which was about 60% lower than that of Sample 1. An absorption peak appears in the 280-320 nm range, but it decreases sharply after 320 nm, and the absorbance was also somewhat low in the 340-360 nm range. Samples containing ecamsule (Samples 4-6) Sample 4 (Ecamsule 20mg, pink line) Absorbance increased sharply in the 320-360 nm range, showing a very high peak exceeding 3.0. Absorbance was also above 0.5 in the 280-320 nm (UVB) range, indicating significantly superior overall absorption capacity compared to the DPDT sample. However, absorption was maintained gradually between 360 and 380 nm, and then rapidly decreased to below 0.1 after 380 nm. This clearly demonstrates that Ecamsule is an organic UV shielding agent primarily optimized for the UVA (320-360 nm) region. Sample 5 (Ecamsule 10mg, green line) Compared to Sample 4, the absorbance peak appeared approximately 1.5 to 1.6 lower, recording a level of 0.4 in the 280-320 nm range. Absorbance increased in the 320-360 nm region, but decreased to less than half the level compared to Sample 4. When the ecamsule concentration was halved, the absorbance capacity weakened compared to the high concentration, making the high-wavelength ultraviolet blocking limit even clearer. Sample 6 (Ecamsule 5mg, orange line) The maximum absorbance was approximately 1.5, which is almost the same as Sample 5, but it was recorded even lower at approximately 0.3 or less in the 280-320 nm range. The absorbance peak in the 320-360 nm range was also slightly reduced compared to Sample 5. As the ecamsule concentration decreases further, the absorption capacity decreases significantly, especially in the UVB (280-320 nm) range, and even in the UVA (360-380 nm) range, absorption drops to below 0.2, clearly indicating the limit of the blocking performance.

[0082] Comprehensive Analysis - 280~320nm (UVB region) All DPDT samples (Samples 1-3) showed strong absorbance characteristics in this range, with the absorbance peak increasing proportionally with concentration. On the other hand, the Ecamsule samples (Samples 4-6) showed relatively low absorbance in this range. - 320~360nm (medium wavelength UVA range) Ecamsule 20 mg (Sample 4) showed an absorbance peak of 3.0 or higher, which was even greater than the maximum absorbance of the DPDT sample (approximately 0.8). In other words, Ecamsule demonstrated excellent performance in blocking mid-wavelength UVA, while DPDT's absorbance was limited to a maximum level of approximately 0.7. - 360~380nm (high wavelength UVA range) In the Ecamsule sample, the absorbance decreased sharply in this interval, while in the DPDT 20 mg (Sample 1), the absorbance was maintained at a level of 0.4-0.5. This suggests that DPDT maintains some absorption beyond the mid-wavelength to ensure high-wavelength blocking capability. - 380~400nm In all samples, the absorbance plummeted to below 0.1, confirming that blocking high-wavelength UVA above 380 nm is virtually impossible with a single component alone.

[0083] conclusion Hydrogel films containing Ecamsule and DPDT individually exhibited the following characteristics. Ecamsule demonstrated excellent blocking performance (absorbance of 3.0 or higher) in the mid-wavelength UVA range of 320-360 nm, but its blocking rate decreased sharply in the high-wavelength UVA range of 380 nm and above. DPDT demonstrated excellent blocking performance (absorbance of 0.8 or higher) in the UVB region of 280-320 nm, and it was confirmed that it can block a certain level of light up to the high-wavelength UVA region while partially maintaining absorbance up to 360-380 nm. Therefore, it is expected that using Ecamsule and DPDT together will allow Ecamsule to complement the mid-wavelength UVA region and DPDT to complement the UVB and high-wavelength UVA regions, thereby maintaining high absorbance across the entire range between 280 and 360 nm. However, to ensure stable blocking up to high wavelengths above 380 nm, the addition of a physical blocking agent such as zinc oxide (ZnO) is absolutely necessary. The results of this experiment clearly demonstrate that combining Ecamsule, DPDT, and ZnO in a skin hydrogel film can ensure UV blocking performance across the entire range between 280 and 400 nm. The descriptions of the embodiments presented herein are provided so that any person with ordinary skill in the art of the present invention may utilize or practice the present invention. Various variations of such embodiments are obvious to a person with ordinary skill in the art of the present invention, and the general principles defined herein may be applied to other embodiments without departing from the scope of the present invention. Therefore, the present invention is not limited by the embodiments presented herein, but should be interpreted in the broadest sense consistent with the principles and novel features presented herein. [Explanation of Symbols]

[0084] 1000: Transparent skin patch with a double-layer structure 10: Hydrogel film 100: Surface layer 200: Skin contact layer

Claims

1. A surface layer comprising a hydrogel mixture and forming a surface; and A skin contact layer comprising the hydrogel mixture and in contact with one surface of the surface layer; A transparent skin patch having a double-layer structure, characterized in that the surface layer comprises a water-soluble ultraviolet-blocking mixture that provides ultraviolet-blocking functionality.

2. The hydrogel mixture comprises distilled water, acrylamide, a hydrophilic polymer, methylenebisacrylamide (MBA), and ammonium persulfate (APS). The aforementioned hydrophilic polymer is a polymeric substance having hydrophilicity that absorbs moisture, A transparent skin patch having a double-layer structure according to claim 1, characterized in that it contains at least one of agarose, chitin, chitosan, gelatin, hyaluronic acid, carboxymethylcellulose (CMC), and polyvinyl alcohol (PVA).

3. The distilled water is provided in an amount of 50 to 55 parts by weight per 100 parts by weight of the hydrogel mixture. The acrylamide is present in an amount of 40 to 45 parts by weight per 100 parts by weight of the hydrogel mixture. The aforementioned hydrophilic polymer is The hydrogel mixture is provided in an amount of 5 to 10 parts by weight per 100 parts by weight, The methylenebisacrylamide is provided in an amount of 0.025 to 0.030 parts by weight per 100 parts by weight of the hydrogel mixture, and The transparent skin patch having a double-layer structure according to claim 2, characterized in that the ammonium persulfate is present in an amount of 0.125 to 0.130 parts by weight per 100 parts by weight of the hydrogel mixture.

4. A transparent skin patch having a double-layer structure according to claim 1, characterized in that the water-soluble ultraviolet blocking mixture comprises ecamsule and disodium phenyldibenzimidazole tetrasulfonate (DPDT).

5. The transparent skin patch having a double-layer structure according to claim 4, characterized in that the water-soluble ultraviolet-blocking mixture further comprises zinc oxide (ZnO).

6. The zinc oxide is dispersed in the form of particles ranging in size from 15 nm to 35 nm. The transparent skin patch having a double-layer structure according to claim 5, characterized in that the particles are comprised of at least one shape from spherical, plate-like, rod-like, and irregular.

7. The transparent skin patch having a double-layer structure according to claim 1, characterized in that the surface layer is composed of a mixture of the water-soluble ultraviolet blocking mixture and the hydrogel mixture in a ratio of 20 parts by weight:80 parts by weight to 30 parts by weight:70 parts by weight, respectively.

8. In a method for manufacturing a transparent skin patch that is attached to the user's skin, The step of generating a skin contact layer; and The step of generating a surface layer on one surface of the skin contact layer; The skin contact layer and the surface layer are characterized by comprising a hydrogel mixture. A method for producing a transparent patch for skin, characterized in that the surface layer comprises a water-soluble ultraviolet blocking component.

9. The step of generating the aforementioned surface layer is: A step of producing a water-soluble ultraviolet-blocking mixture; A step in which acrylamide and a hydrophilic polymer are added to distilled water to produce an initial mixture; The step of adding methylenebisacrylamide to the initial mixture and performing mixing; Mixing step: Adding the water-soluble UV-blocking mixture to the initial mixture containing the methylenebisacrylamide and performing mixing; The step of adding ammonium persulfate to the mixing mixture and performing the mixing process; and A method for producing a transparent skin patch having a double-layer structure according to claim 8, comprising the step of performing a film-forming step based on the final mixture after mixing is complete to generate a surface layer in the form of a film and then performing curing;

10. The step of producing the water-soluble ultraviolet blocking mixture is: A step in which ecamsul, phenyldibenzimidazole tetrasulfonate disodium, and zinc oxide are added to distilled water and dissolved to produce an initial mixture; A step of adjusting the pH of the initial mixture using citric acid or sodium hydroxide; and A method for producing a transparent skin patch having a double-layer structure according to claim 9, comprising the step of adding a humectant and a stabilizer to the initial mixture whose pH has been adjusted to produce the water-soluble ultraviolet blocking mixture.

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