Particle-containing hydrogel

Abstract

The present invention addresses the problem of providing a hydrogel in which a large amount of volatile components can be stably dispersed and which has excellent slow release properties of the volatile components. Provided is a hydrogel containing porous resin particles and a volatile component, the porous resin particles having a pore diameter of 5-30 nm and an oil absorption of 50-700 ml / 100 g, and the mass ratio of the volatile component (A) to the porous resin particles (B) contained in the hydrogel being (A): (B) 1: 1-1: 4.

Description

Technical Field

[0001] The present invention relates to hydrogels. Background Art

[0002] Hydrogels are formed by swelling a polymer with high affinity for water in an aqueous solvent. Hydrogels have various properties, such as water absorption, swelling, moisture retention, adhesion, and conductivity, depending on their use. Using these properties, hydrogels can be used in a wide range of fields, such as civil engineering, agriculture and gardening, food, medicine, cosmetics, and electricity.

[0003] For example, Patent Document 1 discloses a hydrogel which contains a polymer matrix and water and has a specific network structure.

[0004] In addition, flavoring agents are sometimes used as additives in hydrogels, but if menthol is used, it is difficult to dissolve in the mixing solution for preparing the hydrogel because menthol is crystalline at room temperature. If a large amount of menthol is added, the mixing solution and the hydrogel prepared from the mixing solution become cloudy. Patent Document 2 discloses a hydrogel containing 0.001 to 1% by mass of l-menthol, but if more than 1% by mass of l-menthol is added, the hydrogel becomes cloudy, making it difficult to prepare a hydrogel with a high l-menthol content.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2018-150458

[0008] Patent Document 2: Japanese Patent Application Publication No. 2021-147543 Summary of the invention

[0009] Problem that the invention aims to solve

[0010] An object of the present invention is to provide a hydrogel which can stably disperse a large amount of volatile components and has excellent sustained release properties of the volatile components.

[0011] Solutions for solving problems

[0012] The inventors have conducted intensive studies to solve the above problems and have found that by encapsulating volatile components in porous resin particles and dispersing them in hydrogel, a large amount of volatile components can be stably dispersed in the hydrogel and the sustained release of the volatile components is excellent.

[0013] The present invention has been made based on these findings, and includes inventions in the broad aspects shown below.

[0014] [Item 1]

[0015] A hydrogel comprising: porous resin particles and a volatile component,

[0016] The porous resin particles have a pore size of 5 to 30 nm and an oil absorption of 50 to 700 ml / 100 g.

[0017] The mass ratio of (A) the volatile component to (B) the porous resin particles contained in the hydrogel is (A):(B)=1:1 to 1:4.

[0018] [Item 2]

[0019] The hydrogel according to item 1, wherein the porous resin particles contain a monofunctional (meth)acrylate and a cross-linking monomer.

[0020] [Item 3]

[0021] The hydrogel according to item 1 or 2, wherein the content of the volatile component is 0.5 to 5% by mass relative to 100% by mass of the hydrogel.

[0022] [Item 4]

[0023] The hydrogel according to any one of items 1 to 3, wherein the volatile component is at least one selected from the group consisting of flavors, spices, and essential oils.

[0024] [Item 5]

[0025] The hydrogel according to any one of items 1 to 4, comprising a polymer matrix, water and a wetting agent.

[0026] [Item 6]

[0027] The hydrogel according to item 5, wherein the polymer matrix comprises a copolymer of a cross-linking monomer and a monofunctional monomer having one ethylenically unsaturated group.

[0028] [Item 7]

[0029] The hydrogel according to item 6, wherein the content of the structural unit derived from the monofunctional monomer is 10 to 40% by mass based on 100% by mass of the hydrogel.

[0030] [Item 8]

[0031] The hydrogel according to item 6 or 7, wherein the monofunctional monomer is at least one selected from the group consisting of (meth)acrylamide, (meth)acrylic acid, N,N-dimethyl(meth)acrylamide, diacetone(meth)acrylamide and tert-butylacrylamidesulfonic acid.

[0032] [Item 9]

[0033] The hydrogel according to any one of items 5 to 8, wherein the content of the wetting agent is 20 to 70% by mass relative to 100% by mass of the hydrogel.

[0034] [Item 10]

[0035] The hydrogel according to any one of items 1 to 9, which is used as a living body electrode in a monitoring device or a device for performing treatment by electrical stimulation, a counter electrode plate for an electrosurgical device, an adhesive tape, or a wound covering material.

[0036] Effects of the Invention

[0037] According to the present invention, it is possible to provide a hydrogel in which a large amount of volatile components can be stably dispersed and which has excellent sustained release properties of the volatile components. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A is a schematic top view of an embodiment of a gel sheet.

[0039] Figure 1 B is Figure 1 A schematic cross-sectional view of the gel sheet of A along line 1B-1B. DETAILED DESCRIPTION

[0040] In this specification, singular forms (a, an, the, etc.) include the singular and the plural, unless otherwise explicitly stated in this specification or when the context clearly contradicts.

[0041] In this specification, “comprises” is a concept including “consists essentially of” and “consists only of”.

[0042] In the numerical ranges 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 ranges recorded in this specification, the upper limit or lower limit of the numerical range can be replaced by the values ​​shown in the embodiments or the values ​​derived from the embodiments without doubt. Furthermore, in this specification, the numerical values ​​connected with "~" refer to the numerical ranges containing the numerical values ​​before and after "~" as the lower limit and the upper limit.

[0043] In this specification, "(meth)acrylic acid" means acrylic acid, methacrylic acid or both thereof. Therefore, (meth)acrylamide and / or N,N-dimethyl(meth)acrylamide means (1) acrylamide, methacrylamide or both thereof, (2) N,N-dimethylacrylamide, N,N-dimethylmethacrylamide or both thereof, or (3) both of (1) and (2).

[0044] <Hydrogel>

[0045] The hydrogel of the present invention comprises: porous resin particles and volatile components, the pore size of the porous resin particles is 5 to 30 nm, the oil absorption is 50 to 700 ml / 100 g, and the mass ratio of (A) volatile components to (B) porous resin particles contained in the hydrogel is (A): (B) = 1:1 to 1:4.

[0046] In the hydrogel of the present invention, the porous resin particles and the volatile component are preferably contained in the hydrogel as volatile component-containing particles in which the volatile component is supported on the porous resin particles.

[0047] (Porous resin particles)

[0048] The porous resin particles are not particularly limited as long as they have a porous structure, and are preferably water-insoluble. The water-insoluble property of the resin particles refers not only to the property that the resin particles themselves are water-insoluble, but also to the property that a water-soluble acrylic resin, alginic acid resin or amide resin becomes water-insoluble after cross-linking. Here, "water-insoluble" means that after being added to water, it becomes suspended and / or dispersed at the visual level without dissolving.

[0049] Examples of the porous resin particles include acrylic resins, alginic acid resins, and amide resins. Among them, porous resin particles containing acrylic resins are preferred.

[0050] Examples of porous resin particles containing an acrylic resin include porous resin particles containing a polymer of a monomer mixture containing a monofunctional (meth)acrylate and a crosslinking monomer as monomers.

[0051] Examples of the monofunctional (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, glycidyl (meth)acrylate, methoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, methoxydiethylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, Methoxyethylene glycol (meth)acrylate, butoxytriethylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxytetraethylene glycol (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, N-vinyl-2-pyrrolidone (meth)acrylate, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, etc. These monofunctional (meth)acrylates can be used alone or in combination of two or more. As the monofunctional (meth)acrylate used in the present invention, C1 to C4 (carbon number 1 to 4) alkyl esters of (meth)acrylate are preferred, and methyl methacrylate is particularly preferred.

[0052] The content of the monofunctional (meth)acrylate in the monomer mixture is in the range of 1 to 50% by mass, preferably in the range of 10 to 50% by mass. If the content of the monofunctional (meth)acrylate in the monomer mixture is in the range of 1 to 50% by mass, the crosslinking monomer can be sufficiently contained in the monomer mixture, thereby providing sufficient porosity to the porous resin particles, increasing the specific surface area, and reducing the bulk density of the porous resin particles.

[0053] As the crosslinkable monomer, a known crosslinkable monomer having two or more ethylenically unsaturated groups can be used.

[0054] As the aforementioned crosslinking monomer, for example, (meth)acrylic crosslinking monomers such as ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, allyl (meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, etc.; divinylbenzene, divinylnaphthalene, diallyl phthalate, and vinyl crosslinking monomers as their derivatives, etc. can be cited. Among these, (meth)acrylic crosslinking monomers are preferred, and ethylene glycol di(meth)acrylate is more preferred. These crosslinking monomers can be used alone or in combination of two or more.

[0055] In addition, the content of the cross-linkable monomer in the monomer mixture is in the range of 50 to 99% by mass, more preferably in the range of 50 to 90% by mass. If the content of the cross-linkable monomer in the monomer mixture is in the range of 50 to 99% by mass, sufficient porosity can be imparted to the porous resin particles, the specific surface area can be increased, and the bulk specific gravity of the porous resin particles can be reduced.

[0056] The monomer mixture may contain other monomers in addition to the monofunctional (meth)acrylate and the crosslinking monomer as long as the specific surface area of ​​the porous resin particles of the present invention is not affected.

[0057] The pore size of the porous resin particles is 5 to 30 nm, preferably 10 to 20 nm. If the average pore size is less than 5 nm, there is a concern that the volatile components may be hindered from penetrating into the porous resin particles. In addition, if the pore size exceeds 30 nm, the release rate of the volatile components from the porous resin particles becomes faster, and there is a concern that the sustained release of the volatile components in the hydrogel may be reduced. It should be noted that the pore size refers to the average pore size obtained from the nitrogen desorption isotherm based on the BJH method. As a measurement method based on the BJH method, for example, for the resin particles to be measured, the nitrogen desorption isotherm is measured using a specific surface area / pore distribution measurement device (TristarII3020, manufactured by Shimadzu Corporation), and the pore size (average pore size) can be calculated based on the BJH method (Barrett, EP; Joyner, LG; Halenda, PP, J.Am.Chem.Soc.73, 373 (1951)).

[0058] The oil absorption of the porous resin particles is 50 to 700 ml / 100 g, preferably 100 to 700 ml / 100 g. If the oil absorption is 50 ml / 100 g or more, a large amount of volatile components can be loaded on the porous resin particles, which is preferred. If the oil absorption exceeds 700 ml / 100 g, the number of pores inside the porous resin particles increases, and there is a concern that sufficient particle strength cannot be ensured. It should be noted that the oil absorption can be measured based on the measurement method of JIS K 5101-13-2.

[0059] The pore volume of the porous resin particles is preferably 0.30 to 0.90 ml / g, more preferably 0.40 to 0.70 ml / g. If the pore volume is 0.30 ml / g or more, a large amount of volatile components can be loaded into the porous resin particles, which is preferred. In addition, if the pore volume is 0.90 ml / g or less, the particle strength of the porous resin particles does not decrease, so it is preferred. It should be noted that in this specification, the pore volume refers to the pore volume per unit mass, and in the present invention, it refers to the pore volume obtained by the nitrogen desorption isotherm using the BJH method. As a measurement method based on the BJH method, for example, for the resin particles to be measured, a specific surface area / pore distribution measuring apparatus (TristarII3020, manufactured by Shimadzu Corporation) is used to measure the nitrogen desorption isotherm, and the pore volume (cumulative pore volume) can be calculated based on the BJH method (Barrett, EP; Joyner, LG; Halenda, PP, J.Am.Chem.Soc.73, 373 (1951)).

[0060] The specific surface area of ​​the porous resin particles is preferably 50 to 300 m 2 / g, more preferably 80 to 200 m 2 / g. If the specific surface area is 50m 2 / g or more, it is preferred that the porous resin particles can absorb a large amount of volatile components. 2 / g or less, the particle strength of the porous resin particles does not decrease, so it is preferred. It should be noted that in this specification, the specific surface area refers to the surface area per unit mass, and in the present invention, it refers to the specific surface area obtained according to the BET method (N2). The determination of the specific surface area based on the BET method (N2) can be carried out according to the BET method (nitrogen adsorption method) described in ISO 9277 1st edition JIS Z 8830:2001. For example, for the resin particles to be measured, a specific surface area / pore distribution measuring device (TristarII3020, manufactured by Shimadzu Corporation) is used to measure the BET nitrogen adsorption isotherm, and the specific surface area can be calculated from the nitrogen adsorption amount using the BET multi-point method.

[0061] The bulk specific gravity of the porous resin particles is preferably 0.20 to 0.70 g / ml, more preferably 0.30 to 0.60 g / ml. If the bulk specific gravity is 0.20 g / ml or more, the particle strength of the porous resin particles will not decrease, so it is preferred. If the bulk specific gravity is 0.70 g / ml or less, a large amount of volatile components can be loaded into the porous resin particles, which is preferred. It should be noted that in this specification, the bulk specific gravity refers to the solid apparent specific gravity measured using the PowderTester PT-E model manufactured by Hosokawa Micron Corporation.

[0062] The volume average particle size of the porous resin particles is preferably in the range of 0.50 to 100 μm, more preferably in the range of 1.0 to 50 μm, and particularly preferably in the range of 2.0 to 30 μm. When it is within the aforementioned range, the penetration of volatile components into the porous resin particles can be effectively reflected. It should be noted that the volume average particle size is measured using a particle size distribution measuring device Multisizer 4e (manufactured by Beckman Coulter, Inc.), 0.1 g of resin particles are dispersed in 10 ml of a 0.1% by mass nonionic surfactant aqueous solution, and the dispersion is used for measurement. The volume average particle size is calculated based on the average value in the volume-based particle size distribution of 100,000 particles.

[0063] The porous resin particles can be produced by subjecting a monomer mixture containing a monofunctional (meth)acrylate and a crosslinking monomer to suspension polymerization in an aqueous medium in the presence of an organic solvent and then removing the organic solvent.

[0064] The content of the porous resin particles in the hydrogel is preferably 0.50 to 10% by mass, more preferably 1.0 to 6.0% by mass, relative to 100% by mass of the hydrogel. When the content of the porous resin particles is within the above range, a large amount of volatile components can be added to the hydrogel without impairing the mechanical strength and flexibility of the hydrogel.

[0065] (Volatile components)

[0066] Examples of the volatile components include flavors, spices, and essential oils, and these may be used alone or in combination of two or more.

[0067] As flavors and spices, for example, citrus essential oils such as l-menthol, orange oil, lemon oil, grapefruit oil, lime oil, tangerine oil, lavender oil, orange oil, and bergamot oil can be cited; flavor oils such as sage, rosemary, perilla, basil, ginger, and mustard; oleoresins obtained by solvent extraction of these; aromatic plant oils such as coffee oil, roasted nut oils, and sesame oil; natural or synthetic flavor compounds such as vanillin, maltol, linalool, geraniol, citral, and limonene, etc. From the viewpoint of effect, l-menthol is preferred. As the l-menthol, in addition to natural menthol and synthetic menthol, menthol-containing essential oils such as peppermint oil, peppermint oil, and spearmint oil can be used alone or in combination of multiple types.

[0068] Examples of the essential oil include white cedar essential oil, Japanese cypress essential oil, Japanese cedar essential oil, and pine essential oil.

[0069] The content of the volatile component in the hydrogel is preferably 0.50 to 5.0% by mass, more preferably 1.0 to 3.0% by mass, relative to 100% by mass of the hydrogel. If the content of the volatile component is 0.50% by mass or more, a hydrogel having excellent sustained release of the volatile component is obtained, which is preferred. If the content of the volatile component is 5.0% by mass or less, there is less concern that the volatile component will precipitate in the hydrogel, which is preferred.

[0070] In addition, the volatile component can be used as a solvent solution optionally diluted with a solvent. As the solvent, there is no particular limitation as long as it is uniformly mixed with the volatile component, and ester oil, silicone oil, hydrocarbon oil, wax, etc. are preferred. In addition, as commercially available products, NEOLIGHT 100P (manufactured by Kokyu Alcohol Kogyo Co., Ltd.) and KAK HL (manufactured by Kokyu Alcohol Kogyo Co., Ltd.) are preferred.

[0071] When a solvent solution containing a volatile component is formed, it is preferably prepared so that the concentration of the volatile component in the solvent solution becomes 20 mass % or more.

[0072] The content of the solvent in the hydrogel is preferably 0 to 5.0% by mass relative to 100% by mass of the hydrogel. The content of the solvent within the above range is preferred because a large amount of volatile components can be supported on the porous resin particles, and a hydrogel having excellent sustained release of the volatile components can be obtained.

[0073] (Method for producing porous resin particles carrying volatile components (particles containing volatile components))

[0074] The porous resin particles carrying a volatile component (particles containing a volatile component) can be obtained by mixing a volatile component or a solvent solution containing a volatile component with porous resin particles and stirring the mixture. The stirring time is not particularly limited but is about 0.50 to 12 hours.

[0075] In the present invention, the mass ratio of (A) volatile component to (B) porous resin particles in the volatile component-containing particles contained in the hydrogel ((A):(B)) is 1:1 to 1:4, preferably 1:2 to 1:2.5. Within the above range, the volatile component can be loaded on the porous particles, and a hydrogel with excellent sustained release of the volatile component can be obtained.

[0076] Furthermore, the hydrogel of the present invention preferably comprises a polymer matrix, water and a wetting agent.

[0077] (Polymer Matrix)

[0078] The polymer matrix preferably contains 10 to 40% by mass, more preferably 15 to 30% by mass, in 100% by mass of the hydrogel. If the content is 10% by mass or more, the hydrogel has sufficient shape retention and is not prone to excessive softness and easy breakage. In addition, if the content is 40% by mass or less, it is not easy to worry about the softness of the hydrogel being impaired.

[0079] The polymer matrix is ​​not particularly limited as long as it can form a network structure and contain at least water to form a gel, and can be formed, for example, from a copolymer of a monofunctional monomer having one ethylenically unsaturated group and a crosslinking monomer.

[0080] (1) Monofunctional monomers

[0081] As the above-mentioned monofunctional monomer, there is no particular limitation as long as it has one ethylenically unsaturated group, and water-soluble monomers are preferred. For example, as the monofunctional monomer, there can be mentioned dialkyl (meth) acrylamides such as (meth) acrylamide, N,N-dimethyl (meth) acrylamide, and N,N-diethyl (meth) acrylamide; alkyl (meth) acrylamides such as N-isopropyl (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, and N-propyl (meth) acrylamide; hydroxyalkyl (meth) acrylamides such as N-hydroxyethyl (meth) acrylamide and N-hydroxymethyl (meth) acrylamide; N-ethoxymethyl (meth) acrylamide, N-propoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-isobutoxymethyl (meth) acrylamide; Alkoxyalkyl (meth)acrylamide, such as acrylamide, N-pentyloxymethyl (meth)acrylamide, N-hexyloxymethyl (meth)acrylamide, N-heptyloxymethyl (meth)acrylamide, N-octyloxymethyl (meth)acrylamide, N-ethoxyethyl (meth)acrylamide, N-propoxyethyl (meth)acrylamide, and N-butoxyethyl (meth)acrylamide; cationic acrylamide compounds containing amino groups such as N,N-dimethylaminopropyl (meth)acrylamide; anionic monofunctional monomers containing sulfonic acid groups such as 4-acryloylmorpholine and tert-butylacrylamide sulfonic acid or their salts; diacetone (meth)acrylamide; (meth)acrylic acid or its salts; and derivatives thereof. Among them, it is preferred to use at least one selected from the group consisting of (meth)acrylamide, N,N-dimethyl (meth)acrylamide, diacetone (meth)acrylamide, tert-butylacrylamide sulfonic acid and its salts, and (meth)acrylic acid and its salts, but it is not limited thereto. These monofunctional monomers may be used alone or in combination of two or more.

[0082] In addition, as the monofunctional monomer, in addition to the above, vinyl amide monofunctional monomers such as N-vinyl pyrrolidone, N-vinylacetamide, and N-vinyl formamide; nonionic monofunctional monomers such as allyl alcohol, styrene monomers, etc. can be optionally used. These monofunctional monomers can be used alone or in combination of two or more.

[0083] The content of the structural unit derived from the monofunctional monomer in the hydrogel is preferably in the range of 10 to 40% by mass, and more preferably 15 to 35% by mass, relative to 100% by mass of the hydrogel. If the content of the structural unit derived from the monofunctional monomer is within the above range, it is preferred from the viewpoint of the shape, adhesion, operability and flexibility of the hydrogel. If the content is 10% by mass or more, it is not easy to worry about the reduced shape stability caused by the small amount of monofunctional monomers, and a hydrogel with moderate adhesion and no reduction in cohesion and the retention of the hydrogel itself can be obtained. In addition, if the content is 40% by mass or less, a hydrogel with moderate adhesion is obtained, and it is not easy to worry about the softness of the hydrogel being impaired.

[0084] (2) Cross-linking monomer

[0085] As the above-mentioned crosslinking monomer, it is preferred to use a monomer having two or more polymerizable double bonds in the molecule. As such a crosslinking monomer, for example, N,N'-methylenebis(meth)acrylamide, N,N'-ethylenebis(meth)acrylamide, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, (poly)glycerol di(meth)acrylate, (poly)glycerol tri(meth)acrylate and other multifunctional (meth)acrylamide or (meth)acrylate, tetraallyloxyethane, diallyl ammonium chloride, etc., which can be used in one or in combination of two or more. It should be noted that as the crosslinking monomer having two or more polymerizable double bonds in the above-mentioned molecule, a polyglycerol derivative as a multifunctional compound having two or more (meth)acryloyl groups or vinyl groups and a molecular weight of 400 or more, which is recorded in Japanese Patent Gazette No. 2803886, can also be used.

[0086] The content of the structural unit derived from the cross-linking monomer in the hydrogel is preferably in the range of 0.010 mass % to 0.50 mass %, more preferably 0.010 mass % to 0.10 mass % relative to 100 mass % of the hydrogel. If the content of the structural unit derived from the cross-linking monomer is within the above range, it is preferred from the viewpoint of the shape, adhesion, operability and flexibility of the hydrogel. If the content is 0.010 mass % or more, it is not easy to generate concerns about reduced shape stability caused by low cross-linking density, and in addition, a hydrogel with moderate adhesion and no reduction in cohesion and the retention of the hydrogel itself can be obtained. In addition, it is not easy to generate concerns about the deterioration of the operability of the gel sheet such as a part of the gel material remaining on the adherend during peeling. When the content is less than 0.50 mass %, a hydrogel with moderate adhesion is obtained, and in addition, it is not easy to generate concerns about the softness of the hydrogel being impaired.

[0087] (water)

[0088] The water content in the hydrogel is not particularly limited, and is preferably 10 to 60% by mass, more preferably 15 to 30% by mass, relative to 100% by mass of the hydrogel. If the water content is 10% by mass or more, the water content of the hydrogel relative to the equilibrium water content will not become too low, and it is not easy to worry about deterioration (such as swelling, etc.) caused by the hygroscopicity of the hydrogel. In addition, if the water content is 60% by mass or less, the water content of the hydrogel relative to the equilibrium water content will not become too much, and it is not easy to worry about deterioration (such as shrinkage, etc.) caused by drying of the hydrogel.

[0089] (Wetting agent)

[0090] There are no particular limitations on the wetting agent, and examples thereof include glycols such as ethylene glycol, triethylene glycol, 1,6-hexanediol, 1,9-nonanediol, propylene glycol, and butylene glycol; trivalent or higher polyols such as glycerol, pentaerythritol, and sorbitol; polyol condensates such as polyethylene glycol, polypropylene glycol, and polyglycerol; polyol modified bodies such as polyoxyethylene glycerol; polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene isostearyl ether, and polyoxyethylene methyl glucoside; polyoxyalkylene alkyl ethers such as polyoxypropylene lauryl ether, polyoxypropylene stearyl ether, polyoxypropylene isostearyl ether, and polyoxypropylene methyl glucoside; monosaccharides such as xylose, arabinose, glucose, galactose, and mannose; disaccharides such as sucrose, maltose, cellobiose, and lactose; oligosaccharides such as maltotriose, and polysaccharides such as xylan, starch, cellulose, chitin, and chitosan; Amino sugars of these sugars and N-acetylated forms thereof may also be used. Both the D-form and the L-form may be used in combination of two or more.

[0091] Among the wetting agents, polyols that are liquid in the use temperature range of the hydrogel (for example, about 20° C. when used indoors) are preferably used. Specifically, ethylene glycol, triethylene glycol, propylene glycol, polypropylene glycol, polyethylene glycol, polyglycerol, and glycerol are suitable.

[0092] The content of the wetting agent in the hydrogel is not particularly limited, but is preferably in the range of 20 to 70% by mass, more preferably in the range of 30 to 60% by mass, relative to 100% by mass of the hydrogel. If the content of the wetting agent is 20% by mass or more, the obtained hydrogel has a moisturizing power, and the evaporation of water is also suppressed, so the stability of the hydrogel over time is improved, which is preferred. In addition, if the content of the wetting agent is 70% by mass or less, the wetting agent does not seep out from the surface of the hydrogel, and the reduction in adhesiveness caused by the seepage is suppressed, which is preferred.

[0093] (Electrolytes)

[0094] Furthermore, the hydrogel may optionally contain an electrolyte, thereby imparting conductivity to the hydrogel.

[0095] When imparting conductivity to the hydrogel, the content of the above-mentioned electrolyte in the hydrogel is preferably 0.050 to 10% by mass, more preferably 0.10 to 6.0% by mass, relative to 100% by mass of the hydrogel. If the content of the electrolyte is 0.050% by mass or more, the impedance of the hydrogel sheet is reduced, and the conductivity becomes good, so it is preferred. On the other hand, if the content of the above-mentioned electrolyte in the above-mentioned hydrogel is too much, the dissolution of the electrolyte in the hydrogel becomes difficult, and there is a concern that crystals will be precipitated inside the gel, or that the dissolution of other components will be hindered. In addition, the conductivity reaches the upper limit, and from the viewpoint of imparting conductivity, it cannot be said that the addition of the above amount is beneficial.

[0096] The electrolyte is not particularly limited, and examples thereof include alkali metal halides such as sodium halides (e.g., sodium chloride), lithium halides, and potassium halides; alkaline earth metal halides such as magnesium halides and calcium halides; and other metal halides. In addition, various metal hypochlorites, chlorites, chlorates, perchlorates, sulfates, carbonates, nitrates, and phosphates are also suitable as the electrolyte. In addition, inorganic salts such as ammonium salts and various complex salts; salts of monobasic organic carboxylic acids such as acetic acid, benzoic acid, and lactic acid; salts of polybasic organic carboxylic acids such as tartaric acid; monovalent or divalent or higher salts of polybasic carboxylic acids such as phthalic acid, succinic acid, adipic acid, and citric acid; metal salts of organic acids such as sulfonic acid and amino acids; and organic ammonium salts are also suitable as the electrolyte.

[0097] In addition, a base such as sodium hydroxide may be appropriately added to the hydrogel for the purpose of adjusting the pH.

[0098] (additive)

[0099] Furthermore, the hydrogel may optionally contain other additives. Examples of other additives include rust inhibitors, mildew inhibitors, antioxidants, dispersants, defoamers, stabilizers, surfactants, colorants, and the like.

[0100] (Intermediate substrate)

[0101] The hydrogel of the present invention may further include an intermediate substrate embedded in the in-plane direction. Here, the in-plane direction of the hydrogel refers to any direction in a plane orthogonal to the thickness direction of the hydrogel. By including the intermediate substrate, it is helpful to strengthen the hydrogel, improve the shape retention during cutting, etc. It should be noted that the hydrogel in which the intermediate substrate is embedded in the in-plane direction can also be interchangeably represented as a composite material comprising a hydrogel and an intermediate substrate embedded in the in-plane direction of the hydrogel.

[0102] The intermediate substrate is not particularly limited, and nonwoven fabrics, woven fabrics, paper, films, etc. can be cited. The material of the intermediate substrate can be natural fibers such as cellulose, silk, and hemp, synthetic fibers such as polyester, nylon, rayon, polyethylene, polypropylene, and polyurethane, or blends thereof, and a binder can be optionally used, and further, coloring can be optionally performed.

[0103] 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 corresponding to weight per unit area, material etc., without uneven weight per unit area.For woven fabric, also can suitably select and be not particularly limited to plain weave, tricot warp knitted fabric (tricot), raschel warp knitted fabric (raschel) etc.

[0104] The weight per unit area of ​​the nonwoven fabric or woven fabric is not particularly limited as long as it is a weight per unit area that can obtain the desired physical properties as the intermediate substrate, and is preferably 10 to 100 g / m 2 If the unit area weight of the nonwoven fabric or woven fabric is 10g / m 2 If the weight per unit area is 100 g / m 2 Below this value, the intermediate base material will not become too hard, and the followability and conductivity of the hydrogel to the skin will not be damaged.

[0105] If the thickness of the intermediate substrate is too thick, the liquid permeability will be poor. On the contrary, if it is too thin, it is possible that the gel sheet cannot be reinforced, as in the case where the weight per unit area is too small. Therefore, the thickness is appropriately set in consideration of these factors. It is preferably within the range of 0.050 mm to 2.0 mm. In addition, it is more preferably 0.050 mm to 0.50 mm, and particularly preferably 0.080 mm to 0.30 mm.

[0106] It should be noted that the thickness of the hydrogel of the present invention is appropriately selected according to the application, and is, for example, in the range of 0.20 mm to 2.0 mm. In a preferred embodiment, the thickness of the hydrogel of the present invention is 0.30 mm to 1.2 mm.

[0107] <Applications of hydrogel>

[0108] The hydrogel of the present invention can stably disperse a large amount of volatile components, and the volatile components have excellent sustained release properties.

[0109] The hydrogel of the present invention is also excellent in softness and water retention, and therefore can be used in a wide range of fields including medicine, cosmetics, food, chemistry, civil engineering, agriculture, bioengineering, sports, etc. For example, it can be used as a biological electrode hydrogel, a cooling gel, a cosmetic facial mask, a cell culture medium, etc. The hydrogel of the present invention can preferably be used as a biological electrode in a monitoring device or a device for treatment with electrical stimulation, a counter electrode plate for an electrosurgical device, an adhesive tape, or a wound covering material.

[0110] <Method for producing hydrogel>

[0111] The hydrogel of the embodiment of the present invention is not particularly limited, and can be composed of a gelled product obtained by uniformly dispersing the above-mentioned materials other than water and a polymerization initiator in water, and heating or irradiating the obtained mixed solution with ultraviolet rays, etc., thereby polymerizing and crosslinking. The polymerization initiator can be a thermal polymerization initiator or a photopolymerization initiator, and a known thermal polymerization initiator or photopolymerization initiator for polymerizing acrylic monomers can be used. In addition, the content of the polymerization initiator is not particularly limited, and is preferably 0.010% by mass or more, and preferably 1.0% by mass or less, relative to the total amount of the obtained hydrogel (the total amount of the above-mentioned mixed solution) of 100% by mass. Furthermore, when polymerization is performed by ultraviolet irradiation, the cumulative exposure amount of ultraviolet rays also varies depending on the content of the polymerization initiator, etc., and is preferably 800 to 10000 mJ / cm 2 The range of 2000 to 10000 mJ / cm is more preferred. 2 In the present invention, the reaction rate of the non-crosslinking monomer and the crosslinking monomer can be appropriately adjusted by appropriately setting the amount of the polymerization initiator and the ultraviolet irradiation amount.

[0112] The hydrogel of the above embodiment of the present invention can be formed into a desired shape such as a sheet by injecting a compounding liquid into a container of a desired shape such as a bottomed container with a roughly rectangular cross section, and polymerizing it by heating or ultraviolet irradiation. The shape of the hydrogel formed into a sheet can be formed into any shape according to the purpose, for example, a roughly rectangular shape, a roughly circular shape, etc. can be mentioned, but it is not limited to these. Hereinafter, the sheet-shaped hydrogel is referred to as a "hydrogel sheet" or simply a "gel sheet".

[0113] The manufacturing process of the hydrogel sheet with an intermediate substrate varies slightly according to the composition of the hydrogel, the material of the intermediate substrate, the thickness, etc., and is not particularly limited. For example, the following methods can be appropriately used: a method in which the deformation of the intermediate substrate in the vertical direction is minimized, the intermediate substrate is held in the air under a certain tension, a compounding liquid is injected into the upper and lower sides of the intermediate substrate, and a sheet is formed by polymerization by light irradiation or the like; a method in which two sheets of hydrogels with smooth surfaces are prepared, and the intermediate substrate held under a certain tension is sandwiched and composited with these hydrogels; or a method in which a sheet of hydrogel with smooth surfaces is prepared, an intermediate substrate is placed on the hydrogel under a certain tension, a monomer compounding liquid is injected into the intermediate substrate, and a further polymerization is carried out by light irradiation or the like; etc. In the case where the above-mentioned manufacturing process is a continuous process, the intermediate substrate and / or the hydrogel are rolled up, taken out, and appropriately cut into sheets.

[0114] <Embodiments of Hydrogel Sheet>

[0115] Figure 1 A shows a schematic top view of one embodiment of a gel sheet, Figure 1 B is shown Figure 1 A cross-sectional view of the gel sheet of A on line 1B-1B. The gel sheet 1 comprises the hydrogel 2 of the present invention, and an intermediate substrate 3 is embedded in the in-plane direction of the hydrogel 2, and the intermediate substrate 3 is a nonwoven fabric or a woven fabric. In this embodiment, a base film 4 is provided on one side of the gel sheet 1, and a top film 5 is provided on the back side of the side provided with the base film 4, but the base film 4 and the top film 5 may be omitted.

[0116] As the base film 4, for example, a resin film made of a resin such as polyester, polyolefin, polystyrene, or polyurethane, paper, or paper laminated with the resin film can be used.

[0117] The surface of the base film 4 that contacts the gel sheet 1 is preferably subjected to a release treatment. Examples of the release treatment method include silicone coating, and a baking-type silicone coating that undergoes crosslinking and curing reaction by heat or ultraviolet rays is particularly preferred. As the film subjected to the release treatment, a biaxially stretched PET (polyethylene terephthalate) film, an OPP (oriented polypropylene) film, and the like are particularly preferred.

[0118] As the top film 5, a film made of basically the same material as the base film can also be used. However, when polymerization is performed by ultraviolet irradiation from above with the top film in place, it is preferable to select a film made of a material that does not block light in order not to hinder photopolymerization.

[0119] Example

[0120] The present invention will be described in more detail using Production Examples and Examples, but the present invention is not limited to these Examples.

[0121] (Example 1)

[0122] 1. Preparation of particles containing volatile components

[0123] Using a stirring / mixing container, 1 mass % of l-menthol as a volatile component was dissolved in 1 mass % of NEOLIGHT 100P (manufactured by Kokyu Alcohol Kogyo Co., Ltd.) as a solvent as shown in Table 1 to obtain a solvent solution of the volatile component. 2 mass % of NEOLIGHT 100P (manufactured by Kokyu Alcohol Kogyo Co., Ltd.) prepared with reference to Japanese Patent No. 5812374 of our company and having an average pore diameter of 18 nm, an oil absorption of 150 ml / 100 g, a pore volume of 0.40 ml / g, and a specific surface area of ​​80 m 2 The solvent solution was added little by little to particles A having parameters of 0.40 g / g, bulk density of 0.40 g / ml, and volume average particle size of 8 μm, and the mixture was stirred to obtain particles containing volatile components.

[0124] 2. Preparation of compounding liquid

[0125] Using a stirring / mixing container, as shown in Table 1, 20% by mass of acrylamide (AAM) as a monofunctional monomer, 0.040% by mass of N,N'-methylenebisacrylamide (MBAA) as a crosslinking monomer, 54.8% by mass of glycerol as a wetting agent, 18% by mass of ion exchange water, and 3.16% by mass of other additives such as electrolytes and surfactants, dispersants, pH adjusters, preservatives, initiators, binders, and chelating agents were added, and stirred until completely dissolved to obtain a monomer solution. Then, the volatile component-containing particles prepared in 1. were added to the monomer solution and uniformly dispersed using a homomixer to obtain a compounding liquid.

[0126] 3. Fabrication of Hydrogel

[0127] Next, the obtained mixed solution was dripped onto a 100 μm thick PET film (base film) coated with silicone, and a nylon woven fabric and a 38 μm thick PET film (top film) coated with silicone were covered on the dripped mixed solution, and the mixed solution was evenly spread and fixed in a manner of 0.90 mm. A metal halide lamp was used with an energy of 3000 mJ / cm 2 The mixed liquid was irradiated with ultraviolet rays, thereby obtaining a hydrogel sheet having a thickness of 0.90 mm of Example 1.

[0128] (Examples 2 to 10)

[0129] The hydrogels of Examples 2 to 10 were produced in the same manner as in Example 1 except that the mass % of each component was changed as shown in Table 1.

[0130] (Comparative Examples 1 to 4)

[0131] Hydrogels of Comparative Examples 1 to 4 were prepared in the same manner as in Example 1 except that the mass % of each component was changed as shown in Table 1. In Comparative Examples 1, 2, and 4, the volatile components could not be stably dispersed and precipitated in the hydrogel, and thus hydrogels could not be prepared.

[0132] In addition, each component used in Examples 1 to 10 and Comparative Examples 1 to 4 is as follows.

[0133] ·AAM: Acrylamide

[0134] AA: Acrylic acid

[0135] DMAA: N,N-dimethylacrylamide

[0136] MBAA: N,N'-Methylenebisacrylamide

[0137] · l-Menthol: Menthol JP COS (manufactured by TAKASAGO INTERNATIONAL CORPORATION)

[0138] Lavender oil: LAVENDER GEL SK F 2263 (manufactured by INOUE PERFUMERY MFG.CO.,LTD.)

[0139] Citrus oil: CITRUS GEL SK F 2264 (manufactured by INOUE PERFUMERY MFG.CO.,LTD.)

[0140] NEOLIGHT 100P: Isodecyl neopentanoate (manufactured by Kokyu Alcohol Kogyo Co., Ltd.)

[0141] Particle A (porous resin particles): average pore size 18 nm, oil absorption 150 ml / 100 g, pore volume 0.40 ml / g, specific surface area 80 m 2 / g, bulk density 0.40g / ml, volume average particle size 8.0μm

[0142] Particle B (porous resin particles): average pore size 13 nm, oil absorption 250 ml / 100 g, pore volume 0.70 ml / g, specific surface area 200 m 2 / g, bulk density 0.30g / ml, volume average particle size 8.0μm

[0143] Particle C (porous resin particles): average pore size 18 nm, oil absorption 100 ml / 100 g, pore volume 0.40 ml / g, specific surface area 100 m 2 / g, bulk density 0.60g / ml, volume average particle size 20μm

[0144] Particle D (non-porous resin particles): volume average particle size 8.0 μm

[0145] SB-700 (porous inorganic particles): porous silica particles, oil absorption 400 to 700 ml / 100 g, average particle size 4.0 to 6.0 μm (manufactured by Miyoshi Kasei, Inc.)

[0146] (Evaluation of odor retention (sustained release))

[0147] After the hydrogel was peeled off from the PET film (base film), five panelists skilled in sensory testing evaluated the odor of the gel surface after exposure to the atmosphere for 10 seconds and obtained a score. After that, the PET film (base film) was covered and the same evaluation was performed 20 times to obtain the corresponding score. The average of the five evaluations in the first, tenth, and twentieth times was calculated. The results are shown in Table 1.

[0148] Rating 1: No odor

[0149] Rating 2: Peel off the protective film and put your nose close to the gel surface to smell a faint odor

[0150] Rating 3: Smell when removing the protective film

[0151] Rating 4: A noticeable odor is detected when the protective film is removed

[0152] (result)

[0153] In the hydrogels of Examples 1 to 10, a large amount of volatile components were stably dispersed, and the sustained release of the volatile components was good.

[0154] In the compositions of Comparative Examples 1, 2, and 4, volatile components precipitated in the hydrogel, and thus hydrogels could not be produced. The hydrogel of Comparative Example 3 had a drastic decrease in the odor of the volatile components and poor sustained release properties.

[0155] [Table 1]

[0156]

[0157] Description of Reference Numerals

[0158] 1…Gel sheet

[0159] 2…Hydrogel

[0160] 3…Intermediate substrate

[0161] 4…Base film

[0162] 5…Top film

Claims

1. A hydrogel comprising: porous resin particles and a volatile component, The porous resin particles have a pore size of 5 to 30 nm and an oil absorption of 50 to 700 ml / 100 g. The mass ratio of (A) the volatile component to (B) the porous resin particles contained in the hydrogel is (A):(B)=1:1 to 1:

4.

2. The hydrogel according to claim 1, wherein The porous resin particles contain a monofunctional (meth)acrylate and a cross-linking monomer.

3. The hydrogel according to claim 1, wherein The content of the volatile component is 0.5 to 5% by mass relative to 100% by mass of the hydrogel.

4. The hydrogel according to claim 1, wherein The volatile component is at least one selected from the group consisting of fragrances, spices and essential oils. The hydrogel according to claim 1 , comprising: a polymer matrix, water and a wetting agent.

6. The hydrogel according to claim 5, wherein The polymer matrix includes a copolymer of a cross-linking monomer and a monofunctional monomer having one ethylenically unsaturated group.

7. The hydrogel according to claim 6, wherein The content of the structural unit derived from the monofunctional monomer is 10 to 40% by mass based on 100% by mass of the hydrogel.

8. The hydrogel according to claim 6, wherein The monofunctional monomer is at least one selected from the group consisting of (meth)acrylamide, (meth)acrylic acid, N,N-dimethyl(meth)acrylamide, diacetone(meth)acrylamide, and tert-butylacrylamidesulfonic acid.

9. The hydrogel according to claim 5, wherein The content of the wetting agent is 20 to 70% by mass relative to 100% by mass of the hydrogel.

10. The hydrogel according to claim 1, which is used as a living body electrode in a monitoring device or a device for treatment using electrical stimulation, a counter electrode plate for an electrosurgical device, an adhesive tape, or a wound covering material.

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