Skincare cooling product, method of making, and method of using the same

Abstract

This invention provides a skincare product, an encapsulation containing such a skincare product, a method for manufacturing the skincare product and the encapsulation, and a method for using the skincare product. Such a skincare product is configured to provide skincare and cooling and includes a hydrogel layer. The hydrogel layer comprises at least 50% by weight of a liquid portion and a solid gel portion. The solid gel portion comprises: acrylamide as a monomer, diacrylamide as a crosslinking agent, a humectant, and an antimicrobial agent. The liquid portion comprises water and is water, a toner, or an essence. The liquid portion is embedded and distributed within the solid gel portion. The hydrogel layer has a covalently crosslinked structure of a single type.

Description

Skin care cooling product, method of making same and method of using same The present invention generally relates to skin care products. More particularly, the disclosed subject matter relates to skin care products, such as masks, pads, or patches, that are configured to contact and cleanse or treat the skin of an individual in need thereof, such as a human, and also provide a cooling effect. A cosmetic facial mask prepared by impregnating a cosmetic liquid (such as skin lotion) into a non-woven fabric has been used. The facial mask can be easily used, has a high beautifying effect, and gives the user a high sense of psychological satisfaction. Some of the purposes of using cosmetic masks may include moisturizing, conditioning skin texture, treating tightness and sagging, treating wrinkles and folds, improving makeup lasting, tightening pores, and firming the skin. Therefore, cosmetic masks are used not only as a moisturizing tool, but also as a functional cosmetic material for treating tightness and sagging, wrinkles and folds, and firming the skin. For example, ice can be used to cool the skin or injured area of ​​an individual in need. Cooling the skin can sometimes provide a soothing effect. Cooling the injured area after an injury plays an important role in reducing swelling and inflammation around the injury site and accelerating recovery. After the acute phase has passed, occasional application of heat often aids recovery. Athletes have also learned the importance of using cooling after training to aid recovery. Cooling reduces pain, minimizes tissue damage, and has also been shown to have a positive effect on performance. Active cooling uses electricity to power a coolant (whether water or air) to remove heat from a surface. Alginate-acrylamide hydrogels have a double-network structure that can have both covalent and ionic crosslinks. See, for example, A. Pragya et al., “Dynamic cross-linking of an alginate-acrylamide tough hydrogel system: time-resolved in situ mapping of gel self-assembly.” RSC Adv. 2021, 11, 10710. Composite materials including alginate-acrylamide-based double-network hydrogels have also been studied for cooling applications. See P. Gogoi et al., “Ductile cooling phase change material,” Nanoscale Adv., 2020, 2, 3900; International application WO 2021 / 178601. The present invention provides a skin care product, a method of making a skin care product, and a method of using a skin care product. Such skin care products may take the form of, but are not limited to, a mask, a pad, a patch, a film, or any combination thereof. The skin care product also provides a cooling effect on the skin. In some embodiments, the skin care product (such as a facial mask and a neck patch or pad) has a single-layer structure and is configured to contact and treat the skin of an individual (such as a human) while also providing a cooling effect. In one aspect, the present invention provides a skin care product configured to provide both skin care and cooling. Such a skin care product comprises a hydrogel layer comprising a liquid portion that is at least 50% by weight of the total weight of the hydrogel layer, and a solid gel portion. The solid gel portion comprises the following: acrylamide as a monomer, bisacrylamide as a crosslinker, a hygroscopic agent, and an antimicrobial agent. The liquid portion comprises water. The liquid portion can be water, toner, serum, or a combination thereof. The liquid portion is embedded in and distributed within the solid gel portion. The hydrogel layer has covalent crosslinks as the sole type of crosslinking structure. In some embodiments, the hydrogel layer lacks ionic crosslinks. In some embodiments, the hydrogel layer has a single-layer structure, and the skin care product is in a form selected from the group consisting of a mask (such as a facial mask), a pad, a patch, and any combination thereof. Examples of suitable hygroscopic agents (or desiccants) include, but are not limited to, calcium sulfate, calcium chloride, potassium chloride, any hydrates thereof, and any combination thereof. Examples of suitable antimicrobial agents include, but are not limited to, zinc oxide, titanium oxide, and any combination thereof. In some embodiments, the solid gel portion comprises, by dry weight, 50% to 80% of an acrylamide portion, 0.1% to 1% of a bisacrylamide portion, 0.1% to 20% of a hygroscopic agent, and 0.1% to 25% of an antimicrobial agent, based on the total weight of the solid gel portion. In some embodiments, the solid gel portion further comprises, based on the total weight of the solid gel portion on a dry weight basis, a portion selected from the group consisting of: 1% to 8% of an initiator and 0.1% to 1% of an accelerator. For example, in some embodiments, the initiator is ammonium persulfate (APS) and the accelerator is N,N'-methylenebis(acrylamide) (MBAA). In some embodiments, the hydrogel layer comprises 80% to 95% by weight, such as 80% to 86% by weight liquid fraction. According to some embodiments, a skin care product configured to provide both skin care and cooling comprises a hydrogel layer. Based on the total weight of the hydrogel layer, the hydrogel comprises 50% to 95% of a liquid portion and a solid gel portion. The solid gel portion consists essentially of the following components: acrylamide as a monomer, bisacrylamide as a crosslinking agent, an initiator, an accelerator, a hygroscopic agent, and an antimicrobial agent. Each component is described herein. In some embodiments, the hydrogel layer comprises 80% to 95% by weight, such as 80% to 86% by weight, of the liquid portion. The liquid portion comprises water and is selected from the group consisting of water, toner, serum, or a combination thereof. The liquid portion is embedded in and distributed within the solid gel portion. The hydrogel layer has covalent crosslinks as a single type of crosslinking structure. The hydrogel layer has a single-layer structure, and the skin care product does not have any other layers besides the hydrogel layer. The hydrogel layer is configured to be applied directly to the skin of a subject, such as a human (e.g., a female). In some embodiments, the hygroscopic agent is selected from the group consisting of calcium sulfate, calcium chloride, potassium chloride, any hydrates thereof, and any combination thereof. The antimicrobial agent is selected from the group consisting of zinc oxide, titanium oxide, and any combination thereof. In some embodiments, the initiator is ammonium persulfate (APS) and the accelerator is N,N'-methylenebis(acrylamide) (MBAA). The base polymer in the hydrogel layer is polyacrylamide (PAM). Other base components used in double-network hydrogels, such as alginates (e.g., calcium alginate or sodium alginate), are not used. In some embodiments, the hydrogel does not include poly(N-isopropylacrylamide) (PNIPAM), polyvinyl alcohol (PVA), or other base polymers used to form the double network, in addition to one type of polyacrylamide. Poly(N-isopropylacrylamide) (PNIPAM) can be used alone. In some embodiments, the solid gel portion comprises, by dry weight, 50% to 80% acrylamide, 0.1% to 1% bisacrylamide, 1% to 8% initiator, 0.1% to 1% accelerator, 0.1% to 20% hygroscopic agent, and 0.1% to 25% antimicrobial agent, based on the total weight of the corresponding portion and the solid gel portion. The hydrogel layer has any suitable thickness, such as in the range of 0.5 mm to 1 cm (eg, 1 mm to 10 mm). In another aspect, the present invention provides a package or container (or packaged product) comprising an outer shell and a skin care product enclosed therein. The skin care product described herein is placed within the outer shell. The outer shell may be a plastic bag, a plastic-coated paper bag, a plastic film, a plastic box, a glass box, or any combination thereof. Such skin care product may be in the form of, but not limited to, a cover film, a gasket, a patch, a film, or any combination thereof. The skin care product is reusable. In another aspect, the present invention provides a method for making a skin care product as described herein. The method comprises the steps of preparing the components and combining them together to form the skin care product. Such a method comprises mixing at least two parts of a sol as described herein. The present invention also provides a method for making a packaged product as described herein. The present invention also provides a method for using the skin care product as described herein. Priority claims and cross-references This application claims priority to U.S. Provisional Application No. 63 / 482,604, filed on February 1, 2023, which is expressly incorporated herein by reference in its entirety. This description of the exemplary embodiments is intended to be read in conjunction with the accompanying drawings, which are to be considered a part of the complete written description. In this specification, relative terms such as "lower," "upper," "horizontal," "vertical," "above," "below," "upward," "downward," "top," and "bottom," and derivatives thereof (e.g., "horizontally," "downward," "upward," etc.), are to be interpreted as referring to the orientation being described or shown in the drawing in question. Such relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Unless expressly stated otherwise, terms referring to attachment, coupling, and the like (such as "connect") refer to a relationship of structures that are fastened or attached to one another, directly or indirectly through intervening structures, as well as both removable and rigid attachments or relationships. For the purpose of the following description, it should be understood that the embodiments described below may adopt alternative variations and embodiments. It should also be understood that the specific articles, compositions and / or processes described herein are illustrative and should not be considered as limiting. In this disclosure, unless the context clearly dictates otherwise, the singular forms "a," "an," and "the" include plural references, and a reference to a specific value includes at least that specific value. Thus, for example, a reference to a "nanostructure" refers to one or more such structures and equivalents thereof known to those skilled in the art, and so forth. When a value is expressed as an approximation by the use of "about," it should be understood that the specific value forms another embodiment. As used herein, "about X" (where X factors in the value) preferably refers to ±10% of the recited value, inclusive. For example, the phrase "about 8" preferably refers to a value between 7.2 and 8.8, inclusive; as another example, the phrase "about 8%" preferably, but not always, refers to a value between 7.2% and 8.8%, inclusive. All ranges, where present, are inclusive and combinable. For example, when reciting a range of "1 to 5," the recited range should be interpreted to include ranges of "1 to 4," "1 to 3," "1 to 2," "1 to 2 and 4 to 5," "1 to 3 and 5," "2 to 5," and the like. In addition, when a list of alternatives is affirmatively provided, such a list can be interpreted to mean that any alternatives can be excluded, for example, by a negative limitation in the claims. For example, when reciting a range of "1 to 5," the recited range can be interpreted to include the negative exclusion of any of 1, 2, 3, 4, or 5; thus, the recitation of "1 to 5" can be interpreted as "1 and 3 to 5, but not including 2" or simply as "where 2 is not included." It is intended that any component, element, attribute, or step affirmatively recited herein may be expressly excluded from the claims, regardless of whether such component, element, attribute, or step is listed as an alternative or whether or not it is recited separately. As used herein, the term "hydrogel" refers to a gel comprising a water-insoluble, three-dimensional network of polymer chains capable of absorbing large amounts of water. One or more polymers in the hydrogel may include ionically crosslinked structures, covalently crosslinked structures, or both. Compounds containing ions and / or curing agents as crosslinking agents can be used to form crosslinks in one or more, typically hydrophilic, polymers. Hydrogels are highly absorbent and also possess good mechanical properties. As used herein, the term "double-network hydrogel" refers to a hydrogel having two types of crosslinks (eg, covalent crosslinks and ionic crosslinks). Such double-network hydrogels have an interpenetrating network (IPN) structure. As used herein, the term "single-network hydrogel," "single-network hydrogel," or "single-network hydrogel" refers to a hydrogel having only a single type of crosslink, such as only covalent crosslinks without ionic crosslinks. The hydrogel disclosed in the present invention is a single-network hydrogel. The present invention provides a skin care product, a packaged product containing the skin care product, a method of making the skin care product, a method of making the packaged product, and a method of using the skin care product. Such skin care products may take the form of, but are not limited to, a cover film, a pad, a patch, a film, or any combination thereof. The skin care product also provides a cooling effect on the skin. The skin care product, such as a facial mask and a neck patch or pad, has a single-layer structure and is configured to contact and treat the skin of an individual (such as a human) while also providing a cooling effect. According to some embodiments, the skin care products provided herein are configured to provide both skin care and cooling. Such skin care products comprise a hydrogel layer. Such a hydrogel layer comprises a liquid portion that is at least 50% by weight of the total weight of the hydrogel layer, and a solid gel portion. The solid gel portion comprises the following: acrylamide as a monomer, bisacrylamide as a crosslinking agent, a hygroscopic agent, and an antimicrobial agent. The liquid portion comprises water and is selected from the group consisting of water, toner, serum, or any combination thereof. The liquid portion is embedded in and distributed within the solid gel portion. The hydrogel layer has covalent crosslinks as the sole type of crosslinking structure. In some embodiments, the hydrogel layer does not contain ionic crosslinks. The liquid portion comprising water can be present in any amount, but at least 50% is preferred. The hydrogel may have less water and may be soaked in water before use to increase the water content. For example, the liquid portion may be present in an amount ranging from 50% to 95%, 50% to 90%, 60% to 95%, 70% to 95%, or 80% to 95%. In some embodiments, the hydrogel layer comprises 80% to 86% (e.g., 84% to 86%) of the liquid portion, based on the weight of the liquid portion relative to the total weight of the hydrogel. In some embodiments, the hydrogel layer has a single-layer structure, and the skin care product is in a form selected from the group consisting of a mask (such as a facial mask), a pad, a patch, and any combination thereof. In some embodiments, the skin care product is a reusable skin care mask or pad that can be formed into different shapes to cool a body area such as the face or neck. The mask is a single layer of polyacrylamide hydrogel with additives such as calcium sulfate, calcium chloride, or potassium chloride as a desiccant to enhance cooling effectiveness; zinc oxide or titanium dioxide for antimicrobial properties; and a facial toner or serum for skin care benefits. Facial toners or serums can be customized to impart different benefits and may include ingredients including, but not limited to, glycerin, agar, sesame gum, carrageenan, carob gum, cellulose gum, hydrolyzed collagen, hyaluronic acid, potassium sorbate, sucrose, glucose, inositol, disodium EDTA, 1,2-hexanediol, allantoin, polyglyceryl-10 laurate, butylene glycol, dipropylene glycol, and any combination thereof. When applied to the face and neck, the skin care product provided in the present invention reduces skin temperature by up to 8.5°C, and the cooling effect and adhesion last for up to 90 minutes. Examples of suitable hygroscopic agents (or desiccants) include, but are not limited to, calcium sulfate, calcium chloride, potassium chloride, any hydrates thereof, and any combination thereof. Examples of suitable antimicrobial agents include, but are not limited to, zinc oxide, titanium oxide, and any combination thereof. In some embodiments, the solid gel portion comprises, by dry weight, 50% to 80% of an acrylamide portion, 0.1% to 1% of a bisacrylamide portion, 0.1% to 20% of a hygroscopic agent, and 0.1% to 25% of an antimicrobial agent, based on the total weight of the solid gel portion. For example, the content of the hygroscopic agent is in the range of 1% to 18%, such as 9% to 18%, based on the total weight of the solid gel portion on a dry weight basis. The content of the antimicrobial agent can be in the range of 1% to 25%, 1% to 20%, 2% to 25%, 5% to 25%, or any other suitable range based on the total weight of the solid gel portion on a dry weight basis. In some embodiments, the solid gel portion further comprises, based on the total weight of the solid gel portion on a dry weight basis, a portion of an initiator in a range of 1% to 8% (e.g., 3% to 8%) and an accelerator in a range of 0.1% to 1% (e.g., 0.1% to 0.5%). For example, in some embodiments, the initiator is ammonium persulfate (APS) and the accelerator is N,N'-methylenebis(acrylamide) (MBAA). According to some embodiments, a skin care product is configured to provide both skin care and cooling and comprises a hydrogel layer comprising a liquid portion of 50% to 95% (e.g., 80% to 86%), based on the total weight of the hydrogel layer, and a solid gel portion. The solid gel portion consists essentially of acrylamide as a monomer, bisacrylamide as a crosslinker, an initiator, an accelerator, a hygroscopic agent, and an antimicrobial agent. Each of these ingredients is described herein. The liquid portion comprises water and is selected from the group consisting of water, toner, serum, and any combination thereof. The liquid portion is embedded in and distributed within the solid gel portion. The hydrogel layer has covalent crosslinks as the sole type of crosslinking structure. The hydrogel layer has a single-layer structure, and the skin care product has no other layers besides the hydrogel layer. The hydrogel layer is configured for direct application to the skin of an individual, such as a human (e.g., a female). The hydrogel layer provides the desired adhesion to the skin surface and is also removable when necessary. In some embodiments, the hygroscopic agent is selected from the group consisting of calcium sulfate, calcium chloride, potassium chloride, any hydrates thereof, and any combination thereof. The antimicrobial agent is selected from the group consisting of zinc oxide, titanium oxide, and any combination thereof. In some embodiments, the initiator is ammonium persulfate and the accelerator is N,N'-methylenebis(acrylamide) (MBAA). The base polymer in the hydrogel layer is polyacrylamide (PAM). Other base components of the double-network hydrogel, such as alginate, are not used. In some embodiments, the hydrogel does not include poly(N-isopropylacrylamide) (PNIPAM) or polyvinyl alcohol (PVA) used to form the double network. Poly(N-isopropylacrylamide) (PNIPAM) itself can be used as the base polymer of the hydrogel. A monomer curing agent such as N,N'-methylenebis(acrylamide) (MBAA) may be used as a crosslinking agent. A crosslinking accelerator and / or a photoinitiator may be used. In some embodiments, the solid gel portion comprises, by dry weight, 50% to 80% acrylamide, 0.1% to 1% bisacrylamide, 1% to 8% initiator, 0.1% to 1% accelerator, 0.1% to 20% hygroscopic agent, and 0.1% to 25% antimicrobial agent, based on the total weight of the corresponding portion and the solid gel portion. In some embodiments, acrylamide and bisacrylamide provide the polymer matrix of the hydrogel in skin care products. The hydrogel is configured to provide directional evaporative cooling. The hydrogel layer has any suitable thickness, such as in the range of 0.5 mm to 1 cm (eg, 1 mm to 10 mm). The present invention provides wearable skincare and cooling solutions that utilize passive cooling, specifically, heat dissipation through evaporation of water from a hydrogel. Hydrogel-based evaporative cooling mimics mammalian perspiration. The hydrogels in the skincare products provided herein also utilize a unique combination of one or more polymers and additives and / or fillers. When not in use, skin care products such as hoods or patches are stored in sealed, insulated bags to prevent dehydration of the hydrogel; refrigeration is not required. To use the patch, it is removed from its packaging and pressed against the body to adhere. Upon contact with the skin (at a temperature of approximately 36°C), water evaporates from the hydrogel and enters the surrounding environment, effectively removing body heat and lowering the skin's temperature. During a period such as the first 30 minutes of use, the patch achieves a maximum temperature drop of Δ (e.g., approximately 8.5°C) in the contacted skin (as depicted in Figure 1). The cooling effect can remain flat and then decrease in magnitude over time, providing graded and safe cooling for a certain total time until the hydrogel dries out. To reuse the patch, the hydrogel is rehydrated by adding a liquid (such as water or a composition of the liquid portion described herein) to the gel surface. Skin care products such as patches or hoods can also absorb moisture from air or a moisture chamber during storage before reuse. The patch can then be placed on the body for another round of cooling. The patch can be used multiple times, for example up to 30 rounds of cooling, before it is discarded due to wear and tear. The skin care products provided herein, such as masks or pads, are thin and conform to the body's contours. The hydrogel layer that contacts the skin is biocompatible. The material's water-based nature and its independence from refrigeration make it particularly suitable for travel. Sometimes, such as CaCl The hygroscopic additives of 2 and KCl are water soluble. Using water vapor solvent / adsorbent, deliquescent salts with high water affinity can be dissolved in the hydrated hydrogel. For example, CaCl 2 releases heat upon dissolution and can absorb heat during endothermic recrystallization as water evaporates from the hydrogel. In some embodiments, the base polymer in the hydrogel layer is polyacrylamide (PAM) without any alginate, such as calcium alginate or sodium alginate. Antimicrobial additives or fillers include zinc oxide. Zinc oxide is a preferred filler due to its thermal and antibacterial properties. The skin care products provided herein have good mechanical properties, such as good toughness, while also having good adhesion. No insulating support layer is required. No adhesive layer is required. The exemplary skin care products can be applied to a surface, such as the skin. The surface can be wet or dry. Prior to use, the skin care products are stored in a sealed package at room temperature. Refrigeration is not required. They can be removed from the packaging and reused multiple times before being discarded. The skin care product can be any shape and any size. For example, the skin care product can be rectangular, square, round, oval, or any other regular or irregular shape. It can also contain one or more holes, cutouts, cavities, or depressions, for example, to fit the face. The present invention also provides a hydrogel layer having a liquid fraction comprising water of less than 50%. Such a hydrogel layer can be soaked in water or exposed to moisture to increase the liquid fraction comprising water to a desired level above 50%, such as 50% to 95% or 80% to 96%. In another aspect, the present invention provides a package (or packaged product) comprising a housing and a skin care product enclosed therein. The skin care product described herein is disposed within the housing. Such a skin care product may take the form of, but is not limited to, a cover film, a gasket, a patch, a film, or any combination thereof. The skin care product is reusable. In another aspect, the present invention provides a method for making a skin care product as described herein. The method comprises the steps of preparing the components and combining them together to form the skin care product. Such a method comprises mixing at least two parts of a sol as described herein. In some embodiments, a method of making a skin care product as described herein comprises mixing at least two parts of a sol, wherein a first part of the sol comprises acrylamide and a second part of the sol comprises bisacrylamide. Each sol comprises water. The method may further comprise mixing a third part of the sol comprising an antimicrobial agent. The present invention also provides a method of manufacturing a packaged product as described herein. In another aspect, the present invention provides a method of using a skin care product as described herein. For example, such a method comprises at least one step of applying the skin care product to a surface, such as the skin or body part, of a subject. Such a subject is a human, such as any person, athlete, or patient in need of skin care. The mechanism of action is directional evaporative cooling, which simulates and enhances sweating. When in contact with human skin (or another warm surface), water evaporates from the hydrogel matrix into the surrounding environment, thereby lowering the temperature of the skin in contact. The cooling effect ends when the hydrogel matrix dries out. The material can be rehydrated with water or a composition of the liquid portion for the next round of cooling. The hydrogel material can withstand multiple cycles of cooling, such as 30 cycles, before being discarded. It can be stored at ambient temperature and atmosphere or in a humid chamber or in a sealed insulated bag or airtight container. The skin care products provided in the present invention can be used by healthy people, such as women. The toner or essence water in the skin care products provides skin care benefits while also providing a cooling effect. Examples The following samples were prepared using the following procedure: Solution A (or Sol A) and Solution B (or Sol B) were mixed in a 4:1 volume ratio, and the desired volume of Solution C (or Sol C) containing an additive (such as zinc oxide) was added. The solution was poured directly into a closed mold having the desired shape of a skin care product, such as a blister. Gelation occurred within 12 hours at room temperature in the mold. The skin care product, such as a blister, could then be removed from the mold for use. The thickness of the skin care product, such as a blister, ranged from 1 mm to 3 mm. Sol A contains acrylamide, ranging from 12.95 to 17.45 wt% of Sol A (equivalent to 9 to 14.0 wt% of the total gel); and a liquid fraction comprising water, ranging from 82.5 to 87 wt% of Sol A. The water fraction is divided into facial toner or serum (0 to 28 wt% of the total gel) and deionized water (the remaining water content in Sol A). In the formulations presented in Tables 1 to 12, "water" refers to the liquid fraction comprising water, which includes deionized water plus facial toner or serum. Sol A further contains TEMED, comprising 0.05 wt% of Sol A (equivalent to 0.03 to 0.04 wt% of the total gel). Sol B comprises 0.109 wt % N,N'-methylenebis(acrylamide) solution, which ranges from 22.5 to 31.4 wt % of Sol B (equivalent to 0.005 to 0.007 wt % of the total gel); 1.09 wt % ammonium persulfate solution, which ranges from 37.5 to 60 wt % of Sol B (equivalent to 0.08 to 0.11 wt % of the total gel); and 6.06 wt % CaSO 4 1 / 2H 2O solution, ranging from 13.7 to 40 wt% of Sol B (equivalent to 0.15 to 0.48 wt% of the total gel). Sol C includes zinc oxide in an amount ranging from 0 to 5 wt % of the total mass of the skin care product as a mask. In the samples described herein, the total water content in the total gel ranged from 84.3 to 89.1 wt%. The instructions for use of the skincare product include the following: Store the skincare product, such as the mask, in a sealed container at room temperature. Before use, apply a small amount of facial toner, skincare serum, or plain water to the mask surface for moisturizing purposes. Then apply the mask to the desired area on your face or neck. After use, rinse the mask with water to clean it and return it to its container for storage. The mask can be rehydrated (by applying more water, toner, or serum) and then reused for another cooling cycle. The mask lasts for 30 cooling cycles and can be stored for one month, and can be used daily for one month before being discarded. Test Method: Test conditions included a controlled temperature chamber set at 37°C and 30-60% relative humidity. Sample thickness was 2.5 mm. The sample was placed on a temperature probe with a data logger on an acrylic plate (an acrylic model with thermal resistance similar to human skin). As shown in Figure 1, the temperature drop (∆) is the temperature drop after sample placement, minus the temperature at t = 0 (acrylic plate only). The flat line region represents the flat portion of the S-shaped temperature curve after the initial temperature drop, during which the cooling efficiency of the sample remains relatively constant. The formulations and experimental data are shown in Tables 1 to 12. 1. Impact of Alginate Table 1 shows formulations with and without alginate for forming a double network and the associated test results. Sodium alginate ("alg") was used. Table 2 shows formulations that do not include water (including facial toner and serum). Example 1 ("Ex. 1") can be considered a comparative example. With a reduced alginate content, the gel's toughness decreases and its viscosity increases. Lowering the alginate percentage improves the cooling amplitude and the gel's adhesion to the skin. Therefore, it is preferred that no alginate be used in the skin care products provided herein. Table 1 Table 2 2. Impact of Single Components Table 3 shows formulations with different monomers, such as acrylamide (AAM) and N-isopropylacrylamide (NIPAM). Table 4 shows formulations that do not include water, including facial toners and serums. PNIPAM, a thermoreactive polymer, has a larger initial ΔT than PAM, but its cooling effect does not last as long. Dual networks of PAM and PNIPAM, or PAM and PVA, exhibit smaller cooling amplitudes than PAM alone. Table 3 Table 4 3. Effect of hygroscopic agents Table 5 shows the formulas with different contents of calcium sulfate as a hygroscopic agent. Table 6 shows the formulas without water (including facial toner and essence water). 4. The content of calcium sulfate can increase the cooling range and the adhesion of the gel to the skin at a certain level. However, as the content of calcium sulfate exceeds a certain level, the cooling duration will decrease. Until the content of calcium sulfate is 15% of the dry weight of the gel part, the cooling time will decrease. 4 Concentration, cooling duration increases with CaSO 4 increases with the increase of concentration; when CaSO 4 When the concentration exceeds 15%, the cooling duration increases with the CaSO 4 concentration further increased and decreased. Table 5 Table 6 4. Impact of antimicrobial agents Table 7 shows formulations containing various levels of zinc oxide as an antimicrobial agent. Table 8 shows formulations excluding the water portion (including facial toner and serum). Adding zinc oxide did not compromise cooling performance. Adding ZnO up to 2% by weight of the total gel increased gel stiffness; beyond a certain saturation point, for example, at 5% by weight of the total gel (equivalent to 25% ZnO in the solid gel portion on a dry weight basis), gel integrity decreased. Table 7 Table 8 5. The influence of water Table 9 shows formulations with varying "water" content (i.e., the amount of the liquid portion containing water). Table 10 shows formulations that do not contain water (including facial toners and serums). Increasing the water content up to 86% (in Sol A) increases the cooling amplitude. Above 86%, the cooling amplitude decreases. Increasing the water content reduces gel integrity and increases gel viscosity and adhesion to skin. Table 9 Table 10 6. The impact of toner Table 11 shows the formulations of facial toner water solutions with varying amounts. Table 12 shows formulations excluding water (including facial toner and essence water). Adding facial toner reduced gel toughness. However, no reduction in cooling performance was observed. Table 11 Table 12 FIG2 shows experimental data illustrating the cooling effect of one example of a hydrogel, a single-network PAM hydrogel with an infused toner and having a formulation similar to that of Example 24. A temperature probe was applied to the skin and allowed to calibrate until the reported temperature of the contacting skin surface remained constant. A data logger was then activated to record the skin temperature. Immediately after temperature recording began, a hydrogel sample (2.0 mm thick) was placed over the skin and the temperature probe. As shown in FIG2 , the sample reduced the contacting skin temperature by more than eight degrees (8° C.) and persisted for at least one hour. The skin care products provided herein have numerous advantages. They provide skin care benefits, such as a cosmetic effect, while also providing a cooling effect. They have a single-layer structure and do not require any supporting layers. The hydrogel has good toughness, other mechanical properties, and good adhesion to surfaces such as the skin. They are easy to use and can be reusable. Although the subject matter has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly to encompass other variations and embodiments that may be made by those skilled in the art. The present invention is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features in the drawings are not necessarily to scale. Instead, the dimensions of various features have been arbitrarily expanded or reduced for clarity. Throughout the specification and drawings, like reference numerals represent like features. FIG. 1 illustrates the cooling effect of an exemplary skin care product, such as the patch provided in the present invention. FIG2 shows the cooling effect of the experimental example.

Claims

1. A skincare product configured to provide skincare and cooling, wherein the skincare product is in the form of a film, pad, patch, or any combination thereof, and the skincare product has a monolayer structure, the monolayer being a hydrogel layer configured for direct application to the skin surface at room temperature, the hydrogel layer comprising: at least 50% of a liquid portion by weight of the total weight of the hydrogel layer; and a solid gel portion comprising: acrylamide as a monomer, diacrylamide as a crosslinking agent, a humectant, and an antimicrobial agent; wherein the liquid portion comprises water and is selected from the group consisting of water, toner, and essence water, the liquid portion being embedded and distributed within the solid gel portion. The hydrogel layer has covalent cross-linking as the only type of cross-linking structure in the hydrogel layer, and the solid gel portion comprises, by dry weight, 50% to 80% of the acrylamide portion, 0.1% to 1% of the diacrylamide portion, 0.1% to 20% of the hygroscopic agent and 0.1% to 25% of the antimicrobial agent.

2. The skin care product as claimed in item 1, wherein the humectant is selected from the group consisting of: calcium sulfate, calcium chloride, potassium chloride, any hydrate thereof, and any combination thereof.

3. The skin care product as claimed in item 1, wherein the antimicrobial agent is selected from the group consisting of: zinc oxide, titanium oxide and any combination thereof.

4. The skin care product of claim 1, wherein, based on the total weight of the solid gel portion on a dry weight basis, the solid gel portion further comprises an initiator in the range of 1% to 8% and an accelerator in the range of 0.1% to 1%.

5. The skin care product as claimed in item 4, wherein the initiator is ammonium persulfate and the promoter is N,N'-methylenebis(acrylamide) (MBAA).

6. The skin care product of claim 1, wherein the hydrogel layer comprises 80% to 86% of the liquid portion based on the total weight of the hydrogel layer.

7. The skin care product of claim 1, wherein the acrylamide and the diacylamide are provided as polymers only in the matrix of the hydrogel layer.

8. The skin care product of claim 1, wherein the hydrogel layer is configured to provide directional evaporative cooling.

9. A skincare product configured to provide skincare and cooling, wherein the skincare product is in the form of a film, pad, patch, or any combination thereof selected from the group consisting of: a film, a pad, a patch, and any combination thereof, and the skincare product has a monolayer structure, the monolayer being a hydrogel layer configured for direct application to the skin surface at room temperature, the hydrogel layer comprising: a liquid portion comprising, by weight of the total weight of the hydrogel layer, 50% to 95%; and a solid gel portion substantially composed of: acrylamide as a monomer, diacrylamide as a crosslinking agent, an initiator, a promoter, a humectant, and an antimicrobial agent; wherein the liquid portion comprises water and is selected from the group consisting of water, toner, and essence water, the liquid portion being embedded and distributed within the solid gel portion. The hydrogel layer has covalent cross-linking as the only type of cross-linking structure in the hydrogel layer, and wherein, based on the total dry weight of the solid gel portion, the solid gel portion comprises 50% to 80% of the acrylamide portion, 0.1% to 1% of the diacrylamide portion, 0.1% to 20% of the hygroscopic agent and 0.1% to 25% of the antimicrobial agent.

10. The skin care product as claimed in item 9, wherein the humectant is selected from the group consisting of: calcium sulfate, calcium chloride, potassium chloride, any hydrate thereof, and any combination thereof.

11. The skin care product as claimed in item 9, wherein the antimicrobial agent is selected from the group consisting of zinc oxide, titanium oxide and any combination thereof.

12. The skin care product as claimed in item 9, wherein the initiator is ammonium persulfate and the promoter is N,N'-methylenebis(acrylamide) (MBAA).

13. The skin care product of claim 9, wherein the acrylamide and the diacylamide are provided as polymers only in the matrix of the hydrogel layer.

14. The skin care product of claim 9, wherein the hydrogel layer is configured to provide directional evaporative cooling.

15. A method of manufacturing a skin care product as claimed in claim 1, comprising mixing at least two portions of a sol, the at least two portions of the sol comprising a first portion containing the acrylamide and a second portion containing the diacylamide, each sol comprising water.

16. The method of claim 15, further comprising mixing a sol containing a third portion of the antimicrobial agent.

17. An encapsulation comprising a housing and a skincare product as claimed in claim 1 enclosed therein.

18. The skincare product as requested in item 1, wherein the liquid portion is a toner or essence.

19. The skincare product as claimed in item 9, wherein the liquid portion is a toner or essence.

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