Gel sheet

Abstract

To provide a gel sheet having appropriate elasticity and adhesiveness, and having excellent handleability and cooling effect.SOLUTION: The gel sheet characterized by the use of a viscoelastic measurement method with a Custometer manufactured by Courage + Khazaka, where the value of R0 ranges from 0.80 to 1.6 mm and the value of R2 ranges from 0.30 to 1.0.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Gel sheets are made by molding hydrogels, which are polymers with high affinity for water that swell in aqueous solvents, into sheets. Gel sheets have various properties, such as water absorption, swelling, moisture retention, adhesiveness, and electrical conductivity, and are used in a wide range of fields, including medicine, cosmetics, electricity, and food, taking advantage of these properties.

[0003] For example, Patent Document 1 describes an adhesive material having a support and at least one adhesive layer provided on the support, the at least one adhesive layer containing a mesh structure formed by partially bonding fibers to each other. This adhesive material has the property of efficiently inhibiting the flow of the adhesive composition and suppressing glue overflow by forming a mesh structure by thermally fusing fibers to each other in the adhesive layer.

[0004] Patent Document 2 describes a cooling sheet including a support layer, an adhesive layer, and a liner layer for protecting the adhesive layer, in which 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 polyalkylene glycol monooleate 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 a paraoxybenzoic acid ester as a preservative relative to the total mass of the adhesive layer, and the mass ratio of the polyvinyl alcohol content to the polyacrylic acid content (polyvinyl alcohol content:polyacrylic acid content) is within the range of 1.2:1 to 5:1. This sheet has the properties that even when the water content is increased and the mass of the adhesive layer is further increased, the occurrence of liner slippage and seepage is sufficiently suppressed, the adhesive strength is sufficiently high, and the growth of bacteria and mold in the adhesive layer is sufficiently prevented for a long period of time. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2006-204377 [Patent Document 2] WO2020 / 170978 Summary of the Invention [Problem to be solved by the invention]

[0006] When applied to the skin, the gel sheet is required to adhere to and conform to the skin, and therefore it is desirable for the gel sheet to have appropriate elasticity and adhesiveness.

[0007] On the other hand, since both main surfaces of a gel sheet are protected with a film during production and distribution, and the film is peeled off when the sheet is used to apply the sheet to the skin, it is desirable that the film be easily peelable and that the gel surfaces do not stick too much to each other even after the film is peeled off, i.e., that the gel sheet has excellent handleability.

[0008] In addition, in applications where a cooling effect is required, it is desirable for the gel sheet to be able to retain a large amount of water.

[0009] However, conventional gel sheets form a mesh structure by applying heat to fuse the fibers, and do not contain much water, meaning that the cooling effect due to the latent heat of vaporization of water is weak (Reference 1).

[0010] Regarding poultices such as cooling sheets, although they are sticky, the gel particles tend to stick together, making them difficult to handle (Reference 2).

[0011] An object of the present invention is to provide a gel sheet that has appropriate elasticity and adhesiveness, and also has excellent handling properties. [Means for solving the problem]

[0012] The present invention encompasses the embodiments described below. [1] A gel sheet characterized in that the R0 value is 0.80 to 1.6 mm and the R2 value is 0.30 to 1.0, as measured by a viscoelasticity measurement method using a Cutometer manufactured by Courage+Khazaka. [2] The gel sheet according to [1], which contains a synthetic polymer having a network structure, fibers, a moisturizer and water. [3] The gel sheet according to [2], wherein the fiber includes dietary fiber. [4] The gel sheet according to [2], wherein the fibers contain cellulose. [5] The gel sheet according to [2], wherein the content of the fibers per 100 parts by mass of the gel sheet is 0.10 to 1.5 parts by mass. [6] The synthetic polymer having a network structure, The gel sheet according to [2], comprising a crosslinked product of a crosslinker and either or both of a polymer of a polymerizable unsaturated monomer having an anionic functional group and a salt of the polymer. [7] The polymer of the polymerizable unsaturated monomer having an anionic functional group includes one or both of polyacrylic acid and an acrylic acid methacrylic acid copolymer; The gel sheet according to [6], wherein the salt of a polymer of a polymerizable unsaturated monomer having an anionic functional group contains one or both of sodium polyacrylate and sodium acrylate-grafted starch. [8] The gel sheet according to any one of [1] to [7], wherein both main surfaces are gel layers. [9] Item 10. The gel sheet according to item 8, further comprising an intermediate substrate.

[10] A method for producing the gel sheet according to [1], A method for producing a gel sheet, comprising 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-like composition having a network structure. Effect of the Invention

[0013] According to the present invention, it is possible to provide a gel sheet having appropriate elasticity and adhesiveness, as well as excellent handling properties. [Brief description of the drawings]

[0014] [Figure 1] 1 shows an example of the change in viscoelasticity measured using a Cutometer from the start of the first suction to the end of the first relaxation. [Diagram 2] 1 shows the results of measurement of viscoelasticity R0 and R2 of the gel sheet surface measured with a Cutometer in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] As used herein, the singular forms (a, an, the) are intended to include both the singular and the plural, unless otherwise expressly stated in the specification or clearly contradictory in context.

[0016] In this specification, the term "comprise" is a concept that encompasses "consist essentially of" and "consist only of."

[0017] In the numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. In addition, in the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in an example or a value that can be unambiguously derived from an example. Furthermore, in this specification, a numerical value connected with "~" means a numerical range that includes the numerical values ​​before and after "~" as the lower and upper limits.

[0018] According to one aspect of the present invention, there is provided a gel sheet, characterized in that the R0 value is 0.80 to 1.6 mm and the R2 value is 0.30 to 1.0, as measured by a viscoelasticity measurement method using a Cutometer manufactured by Courage+Khazaka.

[0019] Viscoelasticity measurements using a Courage+Khazaka Cutometer.

[0020] The Cutometer is generally known as a device that can quantitatively evaluate the "tightness" of the skin by treating the skin as an elastic body and measuring the viscoelasticity of the skin.

[0021] After careful study, the inventors discovered that, based on specific measurement values ​​obtained when the measurement target of the Cutometer is the surface of a gel sheet instead of skin, it is possible to produce a gel sheet that has suitable elasticity and adhesion, as well as excellent handleability.

[0022] According to the Cutometer, the probe opening under negative pressure sucks the gel sheet surface (suction phase in FIG. 1), the penetration depth (mm) of the gel sheet surface drawn into the opening is measured using a prism provided inside the probe, and then the negative pressure is released to allow relaxation (relaxation phase in FIG. 1), and 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 suction-relaxation process multiple times in succession, but in the present invention, the first suction is referred to as the initial suction, and the first relaxation performed after this is referred to as the initial relaxation.

[0023] In the viscoelasticity measurement method using a Cutometer, R0 is the penetration depth (mm) of the gel sheet surface into the probe opening at the end of the first suction. R1 is the penetration depth (mm) of the gel sheet surface into the probe opening at the end of the first relaxation. R2 is the difference between R0 and R1 divided by R0 [R2=(R0-R1) / R0]. That is, as shown in FIG. t: Time elapsed from the start of the first suction (seconds) e(t): Penetration depth into the probe opening t seconds after the start of the first suction (mm) a: Suction time (seconds) b: Relaxation time (seconds) In this case, R0, R1, and R2 are defined by the following formulas. R0 = e(a) = Uf R1=e(a+b)=Uf-Ua R2 = [e(a)-e(a+b)] / e(a) = Ua / Uf

[0024] The gel sheet of the present invention (hereinafter simply referred to as gel sheet) has a Cutometer value R0 of 0.80 to 1.6 (mm) and R2 of 0.30 to 1.0 on the surface of the gel sheet. When the Cutometer value R0 of the surface of the gel sheet 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 less likely to stick to each other, and the handling is good. It is more preferable that R0 is 0.90 to 1.3 (mm) and R2 is 0.60 to 0.80.

[0025] If R0 is less than 0.80, the gel surface will be too taut and the adhesion will be weak, which is not preferred. If R0 exceeds 1.6, the gel will be too soft and will tend to stick to itself, which is not preferred from the standpoint of handleability. If R2 is less than 0.30, the gel will have low elasticity, which is not preferred.

[0026] The cutter used to measure the viscoelasticity of the gel sheet is not particularly limited as long as it is manufactured by Courage+Khazaka, but preferably, the Cutometer DUAL MPA580 can be used. The type of probe used to measure the viscoelasticity of the gel sheet is not particularly limited as long as it can be connected to the Cutometer main body and used, but the Cutometer CT580 (manufactured by Courage+Khazaka) is preferred.

[0027] The diameter of the probe opening of the Cutometer is not particularly limited, but since the larger the diameter, the stronger the influence of the deeper part of the gel, from the viewpoint 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 since the gel surface can be stably sucked and measured, 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 extension 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 return 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. It is most preferable that the 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.

[0028] The gel sheet may contain a synthetic polymer having a network structure, fibers, a moisturizing agent, and water, which provides a more excellent cooling effect.

[0029] The synthetic polymer having a network structure is not particularly limited as long as it can absorb water and form a gel.

[0030] The content of the synthetic polymer having a network structure in the gel sheet is not particularly limited, but from the viewpoints of appropriate elasticity, adhesiveness, and handleability, the content 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.

[0031] The content of the synthetic polymer having a network structure in the gel sheet can be appropriately adjusted so as to satisfy the above numerical ranges of R0 and R2.

[0032] The fiber acts to reduce adhesion between gels and improve handling. There are no particular limitations on the fiber as long as it is a thread-like material, and for example, dietary fiber or synthetic fiber can be used.

[0033] In one embodiment, the fiber includes dietary fiber. Dietary fiber is preferred because it is easy to incorporate into the gel and is gentle on the skin. As the dietary fiber, cellulose or wheat fiber can be preferably used.

[0034] In one embodiment, the fibers comprise cellulose, which is preferred because it is easy to incorporate into a gel and is gentle on the skin. As the cellulose, preferably, microfibrillated cellulose or cellulose nanofiber can be used, and more preferably, microfibrillated cellulose can be used. As the microfibrillated cellulose, it is preferable to use EXILVA (manufactured by Borregaard). As the cellulose nanofiber, it is preferable to use Rheocrysta (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) or nanoforest (manufactured by Chuetsu Pulp Industry Co., Ltd.).

[0035] As the barley fiber, for example, oat fiber or wheat fiber can be used, and preferably oat fiber can be used. As the oat fiber, it is preferable to use VITACEL (manufactured by Rettenmeyer).

[0036] As the synthetic fibers, polyester fibers, nylon fibers, rayon fibers, polyethylene fibers, polypropylene fibers, polyurethane fibers, etc. can be used.

[0037] The above fibers can be used alone or in combination of two or more kinds.

[0038] The content of fibers in the gel sheet is not particularly limited, but from the viewpoint of appropriate elasticity, adhesion, and handling, it is preferably 0.10 to 1.5 parts by mass, more preferably 0.10 to 1.0 parts by mass, even more 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 fibers is not particularly limited, but is preferably 0.010 to 500 μm, more preferably 0.10 to 300 μm. The method for measuring the average fiber length of dietary fibers is not particularly limited, but for example, morphological observation is performed using a scanning electron microscope, fiber lengths are measured at any 10 or more points, and the number average is calculated.

[0039] The type of fiber in the gel sheet, the content of the fibers in the gel sheet, and the average fiber length can be appropriately adjusted so as to satisfy the above numerical ranges of R0 and R2.

[0040] The moisturizer is added to impart moisturizing properties to the gel sheet.

[0041] The moisturizing agent is not particularly limited, and examples thereof include diols 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 polyhydric alcohols such as glycerin, diglycerin, pentaerythritol, and sorbitol; polyhydric alcohol condensates such as polyethylene glycol, polypropylene glycol, and polyglycerin; and polyhydric alcohol denaturants such as polyoxyethylene glycerin. From the viewpoint of appropriate elasticity and water retention, the moisturizing agent preferably contains one or both of propylene glycol and glycerin, and more preferably contains both of propylene glycol and glycerin. The above moisturizing agents can be added alone or in a mixture of two or more.

[0042] The content of the moisturizer in the gel sheet is not particularly limited, but from the viewpoint of appropriate elasticity and water retention, the content 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, per 100 parts by mass of the gel sheet.

[0043] The type of moisturizer and the content of the moisturizer in the gel sheet can be appropriately adjusted so as to satisfy the above numerical ranges of R0 and R2.

[0044] The water content is not particularly limited, but from the viewpoint of appropriate elasticity and cooling effect, it 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, per 100 parts by mass of the gel sheet.

[0045] The water content in the gel sheet can be appropriately adjusted so as to satisfy the above numerical ranges of R0 and R2.

[0046] As the synthetic polymer having a network structure, a crosslinked product of a crosslinking agent and either or both of a polymer of a polymerizable unsaturated monomer having an anionic functional group and a salt of the polymer can be used.

[0047] As the polymer of the polymerizable unsaturated monomer having an anionic functional group, from the viewpoint of appropriate adhesion, preferably, polyacrylic acid, which is a polymer of acrylic acid, starch-acrylic acid graft polymer, which is a graft polymer of starch and acrylic acid, polymethacrylic acid, which is a polymer of methacrylic acid, and acrylic acid-methacrylic acid copolymer, which is 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 even more preferably, polyacrylic acid can be used. The gel sheet having appropriate adhesion allows it to adhere to the object continuously, thereby enabling the object to be continuously cooled.

[0048] The content of the polymer of the polymerizable unsaturated monomer having an anionic functional group in the gel sheet is not particularly limited, but from the viewpoints of appropriate elasticity, adhesiveness, and handleability, the content 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.

[0049] As the salt of the polymer of the polymerizable unsaturated monomer having an anionic functional group, from the viewpoint of appropriate elasticity and adhesion, preferably, the sodium salt, potassium salt, or triethanolamine salt of polyacrylic acid, starch-acrylic acid graft polymer, polymethacrylic acid, or acrylic acid-methacrylic acid copolymer can be used, more preferably, sodium polyacrylate, or sodium acrylate graft starch can be used, and even more preferably, sodium polyacrylate can be used.

[0050] The content of the salt of the polymer of a polymerizable unsaturated monomer having an anionic functional group in the gel sheet is not particularly limited, but from the viewpoints of appropriate elasticity, adhesiveness, and handleability, the content 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.

[0051] In addition, the polymer of the polymerizable unsaturated monomer having an anionic functional group or a salt thereof before crosslinking with the crosslinking agent preferably has a weight average molecular weight in the range of 10,000 to 5,000,000, taking into consideration the handleability during production.

[0052] Examples of the crosslinking agent include magnesium aluminometasilicate, 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, glycerin triglycidyl ether, triglycidyl isocyanurate, etc. Magnesium aluminometasilicate can be preferably used.

[0053] The content of the crosslinking agent in the gel sheet is not particularly limited, but from the viewpoint of appropriate elasticity and handleability, the content 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 relative to 100 parts by mass of the gel sheet. 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 acrylate grafted starch. Such a configuration imparts elasticity, adhesiveness, and handling properties to the gel sheet, and is easy to manufacture.

[0054] The gel sheet may contain a preservative. Examples of the preservative include phenoxyethanol, methylparaben, and propylparaben, and preferably phenoxyethanol. The above preservatives may be used alone or in combination of two or more kinds.

[0055] The type of preservative and the content of the preservative in the gel sheet can be appropriately adjusted so as to satisfy the above numerical ranges of R0 and R2.

[0056] 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 parts by mass, and even more preferably 0.40 to 0.60 parts by mass, per 100 parts by mass of the gel sheet.

[0057] The gel sheet may further contain ingredients other than the above ingredients. Examples of such ingredients include pH adjusters, antioxidants, antibacterial agents, medicinal ingredients, sequestering agents, fragrances, and colorants. These ingredients can be added within a range that does not impair the effects of the present invention.

[0058] The gel sheet can have gel layers on both main surfaces.

[0059] The state where both main surfaces are gel layers refers to a state where the above-mentioned gel material is located on both main surfaces of the gel sheet and the surfaces of the gel material are exposed to the outside air. When both main surfaces are gel layers, the gel surfaces are exposed to the outside air and moisture is easily evaporated, so the cooling effect due to the heat of vaporization is enhanced.

[0060] The gel sheet may have an intermediate substrate made of a woven or nonwoven fabric embedded in the gel sheet along the surface direction of the gel sheet. The inclusion of the intermediate substrate reinforces the gel sheet and improves its shape retention when cut.

[0061] The intermediate substrate may be, for example, a nonwoven fabric or a woven fabric. The material of the nonwoven fabric or woven fabric may be natural fibers such as cellulose, silk, or hemp, or synthetic fibers such as polyester, nylon, rayon, polyethylene, polypropylene, or polyurethane, or a blend thereof, and a binder may be used as necessary.

[0062] The manufacturing method of the nonwoven fabric is not particularly limited, but includes dry method, wet method, spunbond method, meltblown method, airlaid method, chemical bond method, thermal bond method, needle punch method, and hydroentanglement method. It is more preferable to adopt a manufacturing method according to the basis weight and material, and to have no basis weight unevenness for position control of the intermediate substrate. The woven fabric is also not particularly limited, and can be selected appropriately, such as plain weave, tricot, and raschel.

[0063] The basis weight of the woven or nonwoven fabric is not particularly limited, but is, for example, 10 to 40 g / m 2 It is preferable that the thickness is 10 to 28 g / m 2 It is more preferable that:

[0064] The thickness of the intermediate substrate is not particularly limited, and 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.

[0065] In another aspect of the present invention, a method for producing a gel sheet is provided.

[0066] Such a method includes 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 humectant, a crosslinker and water to form a gel-like composition having a network structure.

[0067] First, 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 are mixed. The mixture may contain a preservative, a pH adjuster, an antioxidant, an antibacterial agent, a medicinal ingredient, a metal sequestering agent, a fragrance, a coloring agent, etc.

[0068] These materials are as described above as components of the gel sheet.

[0069] When mixing one or both of the polymer of a polymerizable unsaturated monomer having an anionic functional group and the salt of the polymer, the fiber, the moisturizing agent, the crosslinking agent, and the water, these components may be mixed at once or may be mixed separately.

[0070] Next, the mixture can be poured into a container of a desired shape and gelled to form a gel sheet.

[0071] The gel sheet may have any shape depending on the purpose, and examples thereof include, but are not limited to, a substantially rectangular shape, a substantially circular shape, and the like.

[0072] When the gel sheet includes an intermediate substrate, the manufacturing method of the gel sheet can be changed according to the composition of the hydrogel, the material of the intermediate substrate, the thickness, etc., and is not particularly limited. For example, a method of holding the intermediate substrate in the air while applying a certain tension to the intermediate substrate, pouring a gel composition containing the various components onto the upper and lower sides of the intermediate substrate, and gelling the intermediate substrate to form a sheet; a method of preparing two gel sheets with a smooth surface, and then sandwiching the intermediate substrate, which is being held while applying a certain tension, between these gel sheets to form a composite; or a method of preparing a gel sheet with a smooth surface, placing the intermediate substrate on the gel sheet while applying a certain tension, and pouring a gel composition containing the various components onto the intermediate substrate to gel it; and the like can be appropriately adopted.

[0073] According to the above method, a gel sheet can be produced which is characterized in that the R0 value is 0.80 to 1.6 mm and the R2 value is 0.30 to 1.0, as measured by a viscoelasticity measurement method using a Cutometer manufactured by Courage+Khazaka.

[0074] The gel sheet of the present invention has appropriate elasticity and adhesiveness, and has excellent handling properties, and can be used in a wide range of 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 face mask, a cell culture medium, etc. Preferably, it can be used as a medical electrode hydrogel that is placed between an electrode made of a conductive material and the skin surface.

[0075] The present invention can also have the following configuration.

[0076] Item 1. A gel sheet characterized in that the R0 value is 0.80 to 1.6 mm and the R2 value is 0.30 to 1.0 in a viscoelasticity measurement method using a Cutometer manufactured by Courage+Khazaka. Item 2. The gel sheet according to Item 1, comprising a synthetic polymer having a network structure, fibers, a moisturizing agent, and water. Item 3. The gel sheet according to Item 2, wherein the fiber includes dietary fiber. Item 4. The gel sheet according to item 2 or 3, wherein the fibers contain cellulose. Item 5. The gel sheet according to any one of Items 2 to 4, wherein the content of the fibers per 100 parts by mass of the gel sheet is 0.10 to 1.5 parts by mass. Item 6. The synthetic polymer having a network structure, Item 6. The gel sheet according to any one of items 2 to 5, comprising 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. Item 7. The polymer of the polymerizable unsaturated monomer having an anionic functional group includes one or both of polyacrylic acid and an acrylic acid methacrylic acid copolymer; Item 7. The gel sheet according to item 6, wherein the salt of the polymer of the polymerizable unsaturated monomer having an anionic functional group includes one or both of sodium polyacrylate and sodium acrylate-grafted starch. Item 8. The gel sheet according to any one of items 1 to 7, wherein both main surfaces are gel layers. Item 9. The gel sheet according to item 8, further comprising an intermediate substrate. Item 10. The gel sheet according to any one of Items 2 to 9, further comprising a preservative. 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 sequestering agent, a fragrance, and a colorant. Item 12. A method for producing the gel sheet according to any one of items 1 to 11, A method for producing a gel sheet, comprising 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-like composition having a network structure. EXAMPLES

[0077] The present invention will be described in more detail with reference to Production Examples and Examples, but the present invention is not limited to these Examples.

[0078] 1. Preparation of Gel Sheets Example 1 Using a stirring / mixing vessel, 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 moisturizing agent, and 10 parts by mass of glycerin were thoroughly mixed until homogeneous, as shown in Table 1. To this mixture, 0.10 parts by mass of microfibrillated cellulose as a fiber, 1.0 parts by mass of magnesium aluminometasilicate as a crosslinking agent, 0.50 parts by mass of phenoxyethanol as a preservative, and 73.4 parts by mass of water were added and dispersed well to form a slurry. 5 parts by mass of polyacrylic acid as a polymer of a polymerizable unsaturated monomer having an anionic functional group was added to this slurry to make a total of 100 parts by mass, and the mixture was thoroughly kneaded and stirred. Next, a tricot half was sandwiched between a 38 μm thick PET film (polyethylene terephthalate film) and a 100 μm thick PET film as an intermediate substrate, and an appropriate amount of the above composition was poured immediately after mixing into the center part so that the thickness was 1.0 mm, and a sheet was made. It was left as it was for 24 hours, and a gel sheet with a thickness of 1.0 mm was obtained. This gel sheet was cut into a face shape and a square shape to be used as a sample for evaluation.

[0079] (Examples 2 to 17 and Comparative Examples 1 to 12) As shown in Tables 1 to 3, gel sheet samples of Examples 2 to 16 and Comparative Examples 1 to 13 were produced in the same manner as in Example 1, except that the compositions for forming the gel sheets were changed.

[0080] [Table 1]

[0081] [Table 2]

[0082] [Table 3]

[0083] 2. Measurement or evaluation methods and evaluation criteria (1) Viscoelasticity measurement using CutometerDUAL MPA580 Viscoelasticity was measured by peeling off the PET film from a gel sheet cut into a square shape of 80 mm x 90 mm, pressing the probe Cutometer CT580 of Courage+Khazaka's CutometerDUAL MPA580 against the gel, aspirating the gel from the opening at the tip of the probe using negative pressure (initial suction), then releasing the negative pressure (initial relaxation), and calculating R0 and R2 from the measurement parameters of the obtained viscoelasticity value (Tables 1 to 3). The measurement conditions were a probe opening with a diameter of 2 mm, suction pressure of 40 kPa, suction time of 2 seconds, and relaxation time of 2 seconds.

[0084] (2) Evaluation of gel elasticity The PET film was peeled off from the gel sheet cut into a square shape of 80 mm x 90 mm, and the elasticity when pressed with a fingertip was evaluated based on the following criteria.

[0085] A: Very good elasticity and moderate softness. B: Good elasticity and moderate softness C: Lacks elasticity, is a little too soft or a little too hard D: Lack of elasticity, too soft or too hard A and B were considered pass marks.

[0086] (3) Evaluation of handling The PET film was peeled off from a gel sheet cut into a square shape of 80 mm x 90 mm, the sheet was folded in half, and the gels were adhered to each other and then peeled off. The ease of peeling was evaluated based on the following criteria.

[0087] A: Easy to peel off B: Somewhat easy to peel off C: Difficult to peel off D: Very difficult to peel off A and B were considered pass marks.

[0088] (4) Evaluation of adhesion Gel sheets cut to the shape of a face were placed on the faces of 10 subjects, and the sheets were shaken up and down and left and right 10 times each. The degree of gel peeling was evaluated according to the following criteria. The most common evaluation among the 10 subjects was used as an index of adhesiveness.

[0089] A: No peeling B: Peeling only at the edge C: Peeling from the edge to the center D: Peeling off from the face A and B were considered pass marks.

[0090] (5) Evaluation of cooling effect The gel sheet was cut to the shape of a face and worn by 10 subjects for 30 minutes, and the cooling sensation was evaluated based on the following criteria. The most common evaluation among the 10 subjects was used as an index of the cooling sensation.

[0091] A: I felt a strong cooling sensation. B: I felt a rather strong cooling sensation. C: I felt a slight cool sensation D: Weak or no cooling sensation felt A and B were considered pass marks.

[0092] 3.Results 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 was in the range of 0.80 to 1.6 (mm) and R2 was in the range of 0.30 to 1.0, had appropriate elasticity and adhesiveness, and also had excellent handling properties and cooling effect.

Claims

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

2. 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. 3. The gel sheet according to claim 2, wherein the content of the fibers per 100 parts by mass of the gel sheet is 0.10 to 1.5 parts by mass.

6. The synthetic polymer having a network structure is 3. The gel sheet according to claim 2, comprising 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 polymer of the polymerizable unsaturated monomer having an anionic functional group comprises one or both of polyacrylic acid and an 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 acrylate-grafted starch. The gel sheet according to claim 6.

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

9. The gel sheet according to claim 8 , further comprising an intermediate substrate.

10. A method for producing the gel sheet according to claim 1, A method for producing a gel sheet, comprising 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-like composition having a network structure.

Images