Gel sheet

Abstract

The invention relates to a gel sheet. [Problem] To provide a gel sheet having moderate elasticity and adhesiveness, and excellent workability and cooling effect. [Solution] A gel sheet which is characterized in that the value of R0 is 0.80 to 1.6 mm and the value of R2 is 0.30 to 1.0 in a viscoelasticity measurement method using a Cutometer of the Courage + Khazaka Supply System.

Description

Technical Field

[0001] The present invention relates to a gel sheet. Background Art

[0002] Gel sheets are made by molding a hydrogel obtained by swelling a polymer with high affinity for water in an aqueous solvent into a sheet shape. Gel sheets have various properties such as water absorption, swelling, moisture retention, adhesion, and conductivity, and these properties are effectively utilized in a wide range of fields such as medicine, cosmetics, electronics, and food.

[0003] For example, Patent Document 1 describes an adhesive material having a support and at least one adhesive layer disposed on the support, wherein the at least one adhesive layer contains a mesh structure formed by partially bonding fibers to each other. The adhesive material has a mesh structure by thermally fusing the fibers to each other in the adhesive layer, thereby having the characteristics of effectively hindering the flow of the adhesive composition and inhibiting the paste from seeping out.

[0004] In addition, Patent Document 2 describes a cooling sheet comprising a support layer, an adhesive layer and a cushioning layer for protecting the adhesive layer, wherein the adhesive layer contains: 65 to 85% by mass of water relative to the total mass of the adhesive layer, 0.12 to 0.7% by mass of monooleic acid polyalkylene glycol ester as a surfactant relative to the total mass of the adhesive layer, 3 to 10% by mass of polyvinyl alcohol as a first water-soluble polymer relative to the total mass of the adhesive layer, 0.5 to 5% by mass of polyacrylic acid as a second water-soluble polymer relative to the total mass of the adhesive layer, and 0.01 to 1% by mass of paraben as a preservative relative to the total mass of the adhesive layer, and the mass ratio of the content of polyvinyl alcohol to the content of polyacrylic acid (content of polyvinyl alcohol: content of polyacrylic acid) is in the range of 1.2:1 to 5:1. This sheet has the following characteristics: even when the water content and thus the mass of the adhesive layer are increased, the occurrence of liner displacement and bleeding can be sufficiently suppressed, and the adhesive strength becomes sufficiently high, thereby being able to fully prevent the generation of bacteria and mold in the adhesive layer for a long time.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-204377

[0008] Patent document 2: WO2020 / 170978 Summary of the invention

[0009] Problem that the invention aims to solve

[0010] When applied to the skin, the gel sheet is required to adhere to the skin and follow the skin, and therefore, it is desirable that the gel sheet has appropriate elasticity and adhesiveness.

[0011] On the other hand, the two main surfaces of the gel sheet are protected by films during production and distribution, and the films are peeled off and attached to the skin during use. Therefore, it is desired that the films can be easily peeled off and the gel surfaces do not stick to each other excessively after the film is peeled off, that is, the handleability is excellent.

[0012] In addition, in applications requiring a cooling effect, it is desirable that the gel sheet be able to retain a large amount of water.

[0013] However, the conventional gel sheet of Patent Document 1 forms a network structure by fusing fibers together by applying heat, does not contain a large amount of water, and has a weak cooling effect using the heat of vaporization of water.

[0014] Although the cooling sheet or other poultice disclosed in Patent Document 2 has adhesive properties, there are problems such as gels easily sticking to each other and being difficult to handle.

[0015] An object of the present invention is to provide a gel sheet having appropriate elasticity and adhesiveness and excellent handling properties.

[0016] Solutions for solving problems

[0017] The present invention includes the following embodiments.

[0018] [1] A gel sheet characterized in that, in a viscoelasticity measurement method using a Cutometer manufactured by Courage + Khazaka Co., Ltd., the R0 value is 0.80 to 1.6 mm and the R2 value is 0.30 to 1.0.

[0019] [2] The gel sheet according to [1], comprising a synthetic polymer having a network structure, fibers, a moisturizing agent, and water.

[0020] [3] The gel sheet according to [2], wherein the fiber contains dietary fiber.

[0021] [4] The gel sheet according to [2], wherein the fibers contain cellulose.

[0022] [5] The gel sheet according to [2], wherein the content of the fibers is 0.10 to 1.5 parts by mass based on 100 parts by mass of the gel sheet.

[0023] [6] The gel sheet according to [2], wherein the synthetic polymer having a network structure comprises a crosslinked product of a crosslinking agent and one or both of a polymer of a polymerizable unsaturated monomer having an anionic functional group and a salt of the polymer.

[0024] [7] The gel sheet according to [6], wherein the polymer of the polymerizable unsaturated monomer having anionic functional groups comprises one or both of polyacrylic acid and acrylic acid-methacrylic acid copolymer, and the salt of the polymer of the polymerizable unsaturated monomer having anionic functional groups comprises one or both of sodium polyacrylate and sodium polyacrylate grafted starch.

[0025] [8] The gel sheet according to any one of [1] to [7], wherein both main surfaces are gel layers.

[0026] [9] The gel sheet according to [8], further comprising an intermediate substrate.

[0027]

[10] A method for producing a gel sheet, which is the method for producing a gel sheet described in [1], comprising: mixing a polymer of a polymerizable unsaturated monomer having anionic functional groups and one or both of a salt of the polymer, fibers, a moisturizing agent, a cross-linking agent and water to form a gel-like composition having a network structure.

[0028] Effects of the Invention

[0029] According to the present invention, a gel sheet having moderate elasticity and adhesiveness and excellent handling properties can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 An example of changes in the measured values ​​in the viscoelasticity measurement using a Cutometer from the start of the initial suction to the end of the initial relaxation is shown.

[0031] Figure 2 The following are the measurement results of viscoelasticity R0 and R2 of the surface of the gel sheet measured by Cutometer in Examples and Comparative Examples. DETAILED DESCRIPTION

[0032] In the present specification, the singular forms (a, an, the) include the singular and the plural, unless otherwise explicitly stated in the present specification or there is an obvious contradiction in the context.

[0033] In the present specification, the term “comprise” is a concept that also includes “consist essentially of” and “consist of”.

[0034] In the numerical range recorded in stages in this specification, the upper limit or lower limit of the numerical range of a certain stage can be arbitrarily combined with the upper limit or lower limit of the numerical range of other stages. In addition, in the numerical range recorded in this specification, the upper limit or lower limit of the numerical range can also be replaced by the value shown in the embodiment or the value derived from the embodiment without doubt. Furthermore, in this specification, the numerical value connected by "~" refers to the numerical range containing the numerical value before and after "~" as the lower limit and the upper limit.

[0035] According to one embodiment of the present invention, there is provided a gel sheet characterized in that, in a viscoelasticity measurement method using a Cutometer manufactured by Courage + Khazaka Co., Ltd., the value of R0 is 0.80 to 1.6 mm and the value of R2 is 0.30 to 1.0.

[0036] The viscoelasticity measurement method using a Cutometer manufactured by Courage + Khazaka Corporation will be described.

[0037] Cutometer is a device that is known to quantitatively evaluate the "tension" of the skin by treating the skin as an elastic body and measuring the viscoelasticity of the skin.

[0038] The inventors have conducted intensive studies and found that a gel sheet having appropriate elasticity and adhesiveness and excellent handling properties can be manufactured based on specific measurement values ​​obtained when the measurement object of the Cutometer is the surface of a gel sheet instead of skin.

[0039] Using a Cutometer, the probe opening is placed under negative pressure to suck the surface of the gel sheet ( Figure 1 During the suction phase, the penetration depth (mm) of the gel sheet surface sucked into the opening is measured using a prism inside the probe, and then the negative pressure is released to relax ( Figure 1 The penetration depth (mm) of the gel sheet surface at the end of relaxation can be measured in the same manner. The Cutometer can repeat the above-mentioned suction-relaxation process for many times, but in the present invention, the first suction is called the primary suction, and the first relaxation that follows is called the primary relaxation.

[0040] In the viscoelasticity measurement method using a cutometer, R0 is the value of the penetration depth (mm) of the gel sheet surface into the probe opening at the end of the initial suction. R1 is the value of the penetration depth (mm) of the gel sheet surface into the probe opening at the end of the initial relaxation. R2 is the value obtained by dividing the difference between R0 and R1 by R0 [R2 = (R0-R1) / R0].

[0041] That is, Figure 1 As shown,

[0042] t: Elapsed time from the first suction (seconds)

[0043] e(t): penetration depth into the probe opening t seconds after the start of initial suction (mm)

[0044] a: Attraction time (seconds)

[0045] b: relaxation time (seconds)

[0046] In this case, R0, R1 and R2 are defined by the following formulae.

[0047] R0=e(a)=Uf

[0048] R1=e(a+b)=Uf-Ua

[0049] R2=[e(a)-e(a+b)] / e(a)=Ua / Uf

[0050] In the gel sheet of the present invention (hereinafter referred to as gel sheet), the Cutometer value R0 of the gel sheet surface is 0.80 to 1.6 (mm), and R2 is 0.30 to 1.0. When the Cutometer value R0 of the gel sheet surface is 0.80 to 1.6 (mm) and R2 is 0.30 to 1.0, the gel sheet has appropriate elasticity and adhesiveness, the gels are not easy to adhere to each other, and the handling is good. More preferably, R0 is 0.90 to 1.3 (mm) and R2 is 0.60 to 0.80.

[0051] When R0 is less than 0.80, the surface tension of the gel is strong and the adhesion becomes weak, which is not preferred. When R0 exceeds 1.6, the gel is too soft and the gels tend to adhere to each other, which is not preferred from the viewpoint of operability. If R2 is less than 0.30, the elasticity of the gel is small, which is not preferred.

[0052] The cutometer used in the viscoelasticity measurement of the gel sheet is not particularly limited as long as it is a cutometer manufactured by Courage + Khazaka, and preferably the cutometer DUAL MPA 580 can be used. The type of the probe used in the viscoelasticity measurement of the gel sheet is not particularly limited as long as it can be connected to the cutometer body, and preferably the cutometer CT 580 (manufactured by Courage + Khazaka) can be used.

[0053] The diameter of the probe opening of the Cutometer is not particularly limited, but the larger the diameter, the stronger the influence of the deep part of the gel. Therefore, from the perspective of measuring the elasticity of the gel surface, it is preferably 2.0 to 4.0 mm, and particularly preferably 2.0 mm. The suction pressure during suction of the gel sheet surface is not particularly limited, but in order to stably suck the gel surface and measure it, it is preferably 30 to 50 kPa, more preferably 35 to 50 kPa, and particularly preferably 40 kPa. The suction time is not particularly limited, but in order to stably measure the elongation of the gel surface during suction, it is preferably 1.0 to 6.0 seconds, more preferably 1.5 to 5.0 seconds, and particularly preferably 2 seconds. The relaxation time is not particularly limited, but in order to stably detect the recovery of the gel surface, it is preferably 1.0 to 6.0 seconds, more preferably 1.5 to 5.0 seconds, and particularly preferably 2.0 seconds. The most preferred diameter of the probe opening is 2.0 mm, the suction pressure is 40 kPa, the suction time is 2.0 seconds, and the relaxation time is 2.0 seconds.

[0054] The gel sheet may include a synthetic polymer having a network structure, fibers, a moisturizer, and water. With such a structure, a more excellent cooling effect can be exerted.

[0055] The synthetic polymer having a network structure is not particularly limited as long as it can contain water and form a gel.

[0056] The content of the synthetic polymer having a network structure in the gel sheet is not particularly limited, but is preferably 2.0 to 20 parts by mass, more preferably 4.0 to 16 parts by mass, and even more preferably 7.0 to 12 parts by mass relative to 100 parts by mass of the gel sheet from the viewpoint of appropriate elasticity, adhesiveness, and handleability.

[0057] The content of the synthetic polymer having a network structure in the gel sheet can be appropriately prepared so as to satisfy the numerical ranges of R0 and R2 described above.

[0058] The fiber plays a role in relieving the adhesion between gels and improving the handling properties. The fiber is not particularly limited as long as it is a thread-like material, and for example, dietary fiber and synthetic fiber can be used.

[0059] In one embodiment, the fiber includes dietary fiber. Dietary fiber is preferred because it is easily blended into the gel and is gentle on the skin. As the dietary fiber, cellulose and wheat fiber can be preferably used.

[0060] In one embodiment, the fiber includes cellulose. Cellulose is preferred because it can be easily blended into a gel and is mild to the skin.

[0061] As cellulose, microfibrillated cellulose and cellulose nanofibers can be preferably used, and microfibrillated cellulose can be more preferably used. As microfibrillated cellulose, EXILVA (manufactured by Borregaard) is preferably used. As cellulose nanofibers, RHEOCRYSTA (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and nanoforest (manufactured by Chuetsu Pulp Industry Co., Ltd.) are preferably used.

[0062] As the wheat fiber, for example, oat fiber and wheat fiber can be used, and oat fiber can be preferably used. As the oat fiber, VITACEL (manufactured by Leitemeyer) is preferably used.

[0063] As the synthetic fiber, polyester fiber, nylon fiber, rayon fiber, polyethylene fiber, polypropylene fiber, polyurethane fiber, etc. can be used.

[0064] The above fibers can be used alone or in combination of two or more.

[0065] The fiber content in the gel sheet is not particularly limited. From the perspective of appropriate elasticity, adhesion and operability, it is preferably 0.10 to 1.5 parts by mass, more preferably 0.10 to 1.0 parts by mass, further preferably 0.10 to 0.50 parts by mass, and particularly preferably 0.30 to 0.50 parts by mass, relative to 100 parts by mass of the gel sheet. The average fiber length of the fiber is not particularly limited, but is preferably 0.010 to 500 μm, more preferably 0.10 to 300 μm. The method for determining the average fiber length of dietary fiber is not particularly limited. For example, the fiber length of any 10 points or more can be measured by morphological observation using a scanning electron microscope, and the fiber length can be calculated by averaging the number of points.

[0066] The type of fibers in the gel sheet, the content of fibers in the gel sheet, and the average fiber length can be appropriately prepared so as to satisfy the numerical ranges of R0 and R2 described above.

[0067] The moisturizer is added to impart moistness to the gel sheet.

[0068] There are no particular limitations on the moisturizing agent, and examples thereof include glycols such as propylene glycol, dipropylene glycol (DPG), 1,3-butylene glycol (1,3-BG), ethylene glycol, triethylene glycol, 1,6-hexanediol, 1,9-nonanediol, and butanediol; trivalent or higher polyols such as glycerol, diglycerol, pentaerythritol, and sorbitol; polyol condensates such as polyethylene glycol, polypropylene glycol, and polyglycerol; and polyol modified substances such as polyoxyethylene glycerol. From the viewpoint of appropriate elasticity and water retention, the moisturizing agent preferably includes one or both of propylene glycol and glycerol, and more preferably includes both of propylene glycol and glycerol. The above moisturizing agents may be added alone or in combination of two or more.

[0069] The content of the moisturizer in the gel sheet is not particularly limited, but is preferably 5 to 40 parts by mass, more preferably 10 to 35 parts by mass, and even more preferably 15 to 30 parts by mass based on 100 parts by mass of the gel sheet from the viewpoint of appropriate elasticity and water retention.

[0070] The type of moisturizer and the content of the moisturizer in the gel sheet can be appropriately prepared so as to satisfy the numerical ranges of R0 and R2.

[0071] The water content is not particularly limited, but is preferably 40 to 85 parts by mass, more preferably 50 to 80 parts by mass, and even more preferably 60 to 75 parts by mass based on 100 parts by mass of the gel sheet from the viewpoint of appropriate elasticity and cooling effect.

[0072] The water content in the gel sheet can be appropriately prepared so as to satisfy the numerical ranges of R0 and R2 described above.

[0073] As the synthetic polymer having a network structure, a crosslinked product of a crosslinking agent and one or both of a polymer of a polymerizable unsaturated monomer having an anionic functional group and a salt of the polymer can be used.

[0074] As the polymer of the polymerizable unsaturated monomer having anionic functional groups, from the viewpoint of moderate adhesiveness, preferably polyacrylic acid as a polymer of acrylic acid, starch-acrylic acid graft polymer as a graft polymer of starch and acrylic acid, polymethacrylic acid as a polymer of methacrylic acid, acrylic acid-methacrylic acid copolymer as a copolymer of acrylic acid and methacrylic acid can be used, more preferably polyacrylic acid and acrylic acid-methacrylic acid copolymer can be used, and further preferably polyacrylic acid can be used. The gel sheet has moderate adhesiveness, can be continuously adhered to the object, and can achieve continuous cooling of the object.

[0075] The content of the polymer of the polymerizable unsaturated monomer having anionic functional groups in the gel sheet is not particularly limited, but is preferably 1.0 to 10 parts by mass, more preferably 2.0 to 8.0 parts by mass, and even more preferably 3.0 to 7.0 parts by mass relative to 100 parts by mass of the gel sheet from the viewpoint of appropriate elasticity, adhesiveness, and handleability.

[0076] As the salt of the polymer of the polymerizable unsaturated monomer having anionic functional groups, from the viewpoint of appropriate elasticity and adhesiveness, sodium salts, potassium salts, and triethanolamine salts of polyacrylic acid, starch-acrylic acid graft polymer, polymethacrylic acid, and acrylic acid-methacrylic acid copolymer can be preferably used, and sodium polyacrylate and sodium polyacrylate graft starch can be more preferably used. Sodium polyacrylate can be used more preferably.

[0077] The content of the salt of the polymer of the polymerizable unsaturated monomer having anionic functional groups in the gel sheet is not particularly limited, but is preferably 1.0 to 10 parts by mass, more preferably 1.5 to 6.0 parts by mass, and even more preferably 2.0 to 4.0 parts by mass relative to 100 parts by mass of the gel sheet from the viewpoint of appropriate elasticity, adhesiveness, and handleability.

[0078] In addition, in consideration of handling properties during production, the weight average molecular weight of the polymerizable unsaturated monomer having an anionic functional group or a salt thereof before crosslinking with a crosslinking agent is preferably in the range of 10,000 to 5,000,000.

[0079] Examples of the crosslinking agent include magnesium aluminosilicate metasilicate, aluminum hydroxide, potassium alum, aluminum sulfate, aluminum glycinate, aluminum acetate, aluminum oxide, aluminum metasilicate, magnesium chloride, calcium hydroxide, calcium carbonate, polyethyleneimine, polyethylene glycol diglycidyl ether, glycerol triglycidyl ether, and triglycidyl isocyanurate. Preferably, magnesium aluminosilicate metasilicate can be used.

[0080] The content of the crosslinking agent in the gel sheet is not particularly limited, but is preferably 0.10 to 5.0 parts by mass, more preferably 0.20 to 2.0 parts by mass, and even more preferably 0.30 to 1.0 parts by mass based on 100 parts by mass of the gel sheet from the viewpoint of appropriate elasticity and handling properties.

[0081] In a specific embodiment, the polymer of the polymerizable unsaturated monomer having an anionic functional group includes one or both of polyacrylic acid and acrylic acid-methacrylic acid copolymer, and the salt of the polymer of the polymerizable unsaturated monomer having an anionic functional group includes one or both of sodium polyacrylate and sodium polyacrylate grafted starch. Such a structure imparts elasticity and adhesiveness, handleability, and ease of manufacture to the gel sheet.

[0082] The gel sheet may contain a preservative. As the preservative, for example, phenoxyethanol, methylparaben, propylparaben, etc. can be used, and phenoxyethanol can be used preferably. The above preservatives can be used alone or in combination of two or more.

[0083] The type of preservative and the content of the preservative in the gel sheet can be appropriately prepared so as to satisfy the numerical ranges of R0 and R2 described above.

[0084] The content of the preservative in the gel sheet is not particularly limited, but is preferably 0.10 to 1.0 part by mass, more preferably 0.20 to 0.80 part by mass, and even more preferably 0.40 to 0.60 part by mass, based on 100 parts by mass of the gel sheet.

[0085] The gel sheet may further contain ingredients other than the above ingredients. As such ingredients, for example, pH adjusters, antioxidants, antibacterial agents, medicinal ingredients, metal chelating agents, fragrances, and coloring agents may be listed. These ingredients may be added within the range that does not impair the effects of the present invention.

[0086] The gel sheet may have both major surfaces serving as gel layers.

[0087] The state where both main surfaces are gel layers refers to the state where the gel raw material is located on both main surfaces of the gel sheet and the surface of the gel raw material is exposed to the outside air. When both main surfaces are gel layers, the gel surface is exposed to the outside air, and moisture is easily vaporized, so the cooling effect based on vaporization heat is improved.

[0088] In the gel sheet, an intermediate base material formed of a woven fabric or a nonwoven fabric may be embedded along the surface direction of the gel sheet. The inclusion of the intermediate base material can enhance the gel sheet and improve the shape retention during cutting.

[0089] As the intermediate substrate, for example, nonwoven fabric or woven fabric can be used. The material of the nonwoven fabric and woven fabric can use natural fibers such as cellulose, silk, hemp, polyester, nylon, rayon, polyethylene, polypropylene, polyurethane and other synthetic fibers, or their blends, and adhesives can also be used as needed.

[0090] The manufacture method of nonwoven fabric is not particularly limited, and can enumerate dry process, wet process, spunbond process, meltblown process, air-laid process, chemical bonding process, thermal bonding process, needle punching process, water flow interweaving process.In order to control the position of intermediate substrate, more preferably adopt the method for making corresponding to weight per unit area, material, and do not have uneven weight per unit area.For woven fabric, also not particularly limited, can suitably select plain weave, tricot warp knitted fabric, raschel warp knitted fabric etc.

[0091] The weight per unit area of ​​the woven fabric or nonwoven fabric is not particularly limited, but is preferably 10 to 40 g / m 2 , more preferably 10 to 28 g / m 2 .

[0092] The thickness of the intermediate substrate is not particularly limited, but is, for example, preferably 0.050 mm to 2.00 mm, more preferably 0.050 mm to 0.50 mm, and further preferably 0.080 mm to 0.30 mm.

[0093] In another aspect of the present invention, a method for producing a gel sheet is provided.

[0094] The method comprises the step of mixing one or both of a polymer of a polymerizable unsaturated monomer having an anionic functional group and a salt of the polymer, fibers, a moisturizing agent, a crosslinking agent and water to form a gel composition having a network structure.

[0095] First, a polymer of a polymerizable unsaturated monomer having anionic functional groups and a salt of the polymer, one or both of the polymer, fiber, a moisturizer, a crosslinking agent and water are mixed. The mixed solution may contain a preservative, a pH adjuster, an antioxidant, an antibacterial agent, a medicinal ingredient, a metal chelating agent, a fragrance and a colorant.

[0096] These materials are as described above as components of the gel sheet.

[0097] When mixing one or both of the polymer of the polymerizable unsaturated monomer having an anionic functional group and the salt of the polymer, the fiber, the moisturizing agent, the crosslinking agent and water, these components may be mixed at once or separately.

[0098] Next, the mixed solution can be poured into a container of a desired shape and gelled to form a gel sheet.

[0099] The shape of the gel sheet can be any shape depending on the purpose, and examples thereof include a substantially rectangular shape and a substantially circular shape, but are not limited to these.

[0100] When the gel sheet has an intermediate substrate, the method for manufacturing the gel sheet can be changed according to the composition of the hydrogel, the material and thickness of the intermediate substrate, etc., and is not particularly limited. For example, the following methods can be appropriately used: a method in which the intermediate substrate is held in the air while a certain tension is applied to the intermediate substrate, a gel composition mixed with various components is flowed on the upper and lower sides of the intermediate substrate, and the gel is made into a sheet; a method in which two gel sheets with smooth surfaces are prepared, and the intermediate substrate held under a certain tension is sandwiched between the gel sheets to form a composite; or a method in which a gel sheet with smooth surfaces is prepared, an intermediate substrate is placed on the gel sheet under a certain tension, a gel composition mixed with various components is flowed on the intermediate substrate, and the gel is made; etc.

[0101] According to the above method, a gel sheet can be produced, wherein the value of R0 is 0.80 to 1.6 mm and the value of R2 is 0.30 to 1.0 in the viscoelasticity measurement method using a Cutometer manufactured by Courage + Khazaka Co., Ltd.

[0102] The gel sheet of the present invention has moderate elasticity and adhesiveness and excellent operability, and can therefore be used in various fields such as medicine, cosmetics, food, chemistry, bioengineering, and sports. For example, it can be used as a medical electrode hydrogel, a cooling gel, a cosmetic mask, a cell culture medium, etc. It can preferably be used as a medical electrode hydrogel that is disposed between an electrode made of a conductive material and the skin surface.

[0103] The present invention may also adopt the following configurations.

[0104] Item 1. A gel sheet characterized in that, in a viscoelasticity measurement method using a Cutometer manufactured by Courage + Khazaka Co., Ltd., the value of R0 is 0.80 to 1.6 mm and the value of R2 is 0.30 to 1.0.

[0105] Item 2. The gel sheet according to Item 1, comprising a synthetic polymer having a network structure, fibers, a moisturizer, and water.

[0106] Item 3. The gel sheet according to Item 2, wherein the fiber contains dietary fiber.

[0107] Item 4. The gel sheet according to Item 2 or 3, wherein the fibers contain cellulose.

[0108] Item 5. The gel sheet according to any one of Items 2 to 4, wherein a content of the fibers is 0.10 to 1.5 parts by mass based on 100 parts by mass of the gel sheet.

[0109] Item 6. The gel sheet according to any one of Items 2 to 5, wherein the synthetic polymer having a network structure comprises a crosslinked product of a crosslinking agent and one or both of a polymer of a polymerizable unsaturated monomer having an anionic functional group and a salt of the polymer.

[0110] Item 7. The gel sheet according to Item 6, wherein the polymer of the polymerizable unsaturated monomer having anionic functional groups comprises one or both of polyacrylic acid and acrylic acid-methacrylic acid copolymer, and the salt of the polymer of the polymerizable unsaturated monomer having anionic functional groups comprises one or both of sodium polyacrylate and sodium polyacrylate grafted starch.

[0111] Item 8. The gel sheet according to any one of Items 1 to 7, wherein both main surfaces are gel layers.

[0112] Item 9. The gel sheet according to Item 8, further comprising an intermediate substrate.

[0113] Item 10. The gel sheet according to any one of Items 2 to 9, further comprising a preservative.

[0114] Item 11. The gel sheet according to any one of Items 2 to 10, further comprising at least one of a pH adjuster, an antioxidant, an antibacterial agent, a medicinal ingredient, a metal chelating agent, a flavor, and a colorant.

[0115] Item 12. A method for producing a gel sheet, which is the method for producing a gel sheet according to any one of Items 1 to 11, comprising: mixing a polymer of a polymerizable unsaturated monomer having anionic functional groups and one or both of a salt of the polymer, fibers, a moisturizer, a cross-linking agent and water to form a gel-like composition having a network structure.

[0116] Example

[0117] The present invention will be described in more detail using Production Examples and Examples, but the present invention is not limited to these Examples.

[0118] 1. Preparation of Gel Sheets

[0119] (Example 1)

[0120] Using a stirring / mixing container, as shown in Table 1, 4.0 parts by mass of sodium polyacrylate as a salt of a polymer of a polymerizable unsaturated monomer having an anionic functional group, 6.0 parts by mass of dipropylene glycol (DPG) as a moisturizer, and 10 parts by mass of glycerol were fully mixed until uniform. 0.10 parts by mass of microfibrillated cellulose as a fiber, 1.0 parts by mass of magnesium aluminosilicate as a crosslinking agent, 0.50 parts by mass of phenoxyethanol as a preservative, and 73.4 parts by mass of water were added to the mixture and fully dispersed to prepare a slurry. 5 parts by mass of polyacrylic acid as a polymer of a polymerizable unsaturated monomer having anionic functional groups were added to the slurry to make a total of 100 parts by mass, and the mixture was fully kneaded and stirred. Next, a half piece of tricot (nylon knitted fabric) as an intermediate substrate was sandwiched between a 38 μm thick PET film (polyethylene terephthalate film) and a 100 μm thick PET film, and an appropriate amount of the above composition was flowed into the central part immediately after the mixing was completed in order to obtain a sheet. The sheet was left as is for 24 hours to obtain a gel sheet with a thickness of 1.0 mm. The gel sheet was cut into a facial shape and a quadrilateral shape as a sample for evaluation.

[0121] (Example 2 to Example 16 and Comparative Example 1 to Comparative Example 13)

[0122] As shown in Tables 1 to 3, gel sheet samples of Examples 2 to 16 and Comparative Examples 1 to 13 were prepared in the same manner as in Example 1 except that the composition for forming the gel sheet was changed.

[0123] [Table 1]

[0124]

[0125] [Table 2]

[0126]

[0127] [Table 3]

[0128]

[0129] 2. Measurement or evaluation methods and evaluation criteria

[0130] (1) Viscoelasticity measurement using Cutometer DUAL MPA580

[0131] Regarding viscoelasticity, the PET film of the gel sheet cut into a square shape of 80 mm × 90 mm was peeled off, and the probe Cutometer CT 580 of Cutomer DUAL MPA 580 manufactured by Courage + Khazaka was pressed, and the gel was sucked (primary suction) from the opening at the front end of the probe by negative pressure, and then the negative pressure was released (primary relaxation), and R0 and R2 (Tables 1 to 3) were obtained from the measurement parameters of the obtained viscoelasticity values. The measurement conditions were as follows: the diameter of the probe opening was 2 mm, the suction pressure was 40 kPa, the suction time was 2 seconds, and the relaxation time was 2 seconds.

[0132] (2) Evaluation of gel elasticity

[0133] The PET film of the gel sheet cut into a square shape of 80 mm×90 mm was peeled off, and the elasticity when pressed with a fingertip was evaluated based on the following criteria.

[0134] A: Very good elasticity, moderate softness

[0135] B: Good elasticity and moderate softness

[0136] C: Lack of elasticity, slightly too soft or slightly too hard

[0137] D: Lack of elasticity, too soft or too hard

[0138] A and B are qualified.

[0139] (3) Evaluation of operability

[0140] The PET film of the gel sheet cut into a square shape of 80 mm×90 mm was peeled off, and the sheet was folded in half. The ease of peeling after the gels were bonded together was evaluated based on the following criteria.

[0141] A: Easy to peel off

[0142] B: Slightly easy to peel off

[0143] C: Difficult to peel off

[0144] D: Very difficult to peel off

[0145] A and B are qualified.

[0146] (4) Evaluation of Adhesion

[0147] The gel sheet cut into the shape of a face was worn on the face of 10 subjects, and the peeling of the gel when the face was shaken 10 times up and down and left and right was evaluated based on the following criteria. The highest evaluation among the evaluation results of the 10 subjects was used as an index of adhesiveness.

[0148] A: No peeling

[0149] B: Only the end is peeled off

[0150] C: There is peeling from the end to the center

[0151] D: Peeling off from the face

[0152] A and B are qualified.

[0153] (5) Evaluation of cooling effect

[0154] The gel sheet cut into the shape of the face was worn on the face of 10 subjects for 30 minutes, and the cooling sensation was evaluated based on the following criteria: The highest evaluation among the judgment results of the 10 subjects was used as an index of cooling sensation.

[0155] A: Feel a strong cooling sensation

[0156] B: Feel a slightly stronger cooling sensation

[0157] C: Feel a slight cooling sensation

[0158] D: A weak cooling sensation or no cooling sensation

[0159] A and B are qualified.

[0160] 3. Results

[0161] The results are shown in Figure 1 and Tables 1 to 3. The above results show that the gel sheet of this example, in which R0 is in the range of 0.80 to 1.6 (mm) and R2 is in the range of 0.30 to 1.0, has appropriate elasticity and adhesiveness, and has excellent handling properties and cooling effects.

Claims

1. A gel sheet, characterized in that: In the viscoelasticity measurement method using a Cutometer manufactured by Courage+Khazaka Co., Ltd., the value of R0 was 0.80 to 1.6 mm, and the value of R2 was 0.30 to 1.

0. 2 . The gel sheet according to claim 1 , comprising a synthetic polymer having a network structure, fibers, a moisturizing agent and water.

3. The gel sheet according to claim 2, wherein: The fiber comprises dietary fiber.

4. The gel sheet according to claim 2, wherein: The fibers comprise cellulose.

5. The gel sheet according to claim 2, wherein: The content of the fibers is 0.10 to 1.5 parts by mass based on 100 parts by mass of the gel sheet.

6. The gel sheet according to claim 2, wherein: The synthetic polymer having a network structure includes a crosslinked product of a crosslinking agent and one or both of a polymer of a polymerizable unsaturated monomer having an anionic functional group and a salt of the polymer.

7. The gel sheet according to claim 6, wherein: The polymer of the polymerizable unsaturated monomer having an anionic functional group comprises one or both of polyacrylic acid and acrylic acid-methacrylic acid copolymer, The salt of the polymer of the polymerizable unsaturated monomer having an anionic functional group includes one or both of sodium polyacrylate and sodium polyacrylate grafted starch.

8. The gel sheet according to any one of claims 1 to 7, wherein The two main surfaces are gel layers. 9 . The gel sheet according to claim 8 , further comprising an intermediate substrate.

10. A method for producing a gel sheet, which is the method for producing a gel sheet according to claim 1, The manufacturing method comprises: A step of mixing one or both of a polymer of a polymerizable unsaturated monomer having an anionic functional group and a salt of the polymer, fibers, a moisturizing agent, a crosslinking agent, and water to form a gel composition having a network structure.

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