Wet indicator composition and wet indicator

Abstract

A wet indicator composition having excellent color change properties is provided. A wet indicator composition comprising an oily gel and a moisture-sensitive colorant composition is disclosed.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority under Article 4 of the Paris Convention based on Japanese Patent Application No. 2020-129591 filed in Japan on July 30, 2020, which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to a wet indicator, which is a means that notifies the presence of moisture by color change. BACKGROUND

[0004] Examples of articles that exhibit a function by contact with moisture include a moisture exchanger (HEM), a humidity detector, an autoclave (sterilization) tape, a packaging article, and an absorbent article. As a device that shows that these articles are in a wet state and exhibit a function, a wet indicator is known. Wetness refers to a state in which a liquid containing water (such as a body fluid, that is, moisture) is contacted. An indicator refers to a display tool and a marking tool.

[0005] Generally, a wet indicator changes its color to indicate whether an article is dry or wetted by moisture. For example, when an article is wet, a wet indicator is colored or color-changed, thereby showing the state of the wet state of the article.

[0006] Patent Documents 1 to 3 describe wet indicator compositions used in combination with absorbent articles such as diapers.

[0007] Patent Document 1 describes a wet indicator composition that changes color in response to a change in pH. The wet indicator composition contains a water-insoluble thermoplastic polymer composition, a superabsorbent polymer, a wet indicator, and a surfactant ([Abstract], [Claim 1], [Claim 2]).

[0008] Patent Document 2 describes a hot melt humidity indicator composition that can be applied using a conventional hot melt applicator device. The hot melt humidity indicator composition contains components such as a water-insoluble thermoplastic polymer, an anionic surfactant, and a leuco dye ([Abstract], [Claim 1],

[0006] ).

[0009] Patent Document 3 describes a humidity / fluid indicator composition that is colorless in its initial state and can provide various final wet state color choices in the presence of water. The humidity / fluid indicator composition includes a leuco dye and a color developer in a hot melt adhesive matrix ([Abstract],

[0001] ,

[0008] ).

[0010] Prior Art Documents

[0011] Patent Literature

[0012] Patent Literature 1: JP 2009-511673 A

[0013] Patent Literature 2: JP 2018-515165 A

[0014] Patent Literature 3: JP 2018-517894 A SUMMARY

[0015] PROBLEMS TO BE SOLVED BY THE INVENTION

[0016] However, in the conventional wet-state indicator composition, the matrix (i.e., the main continuous phase) is composed of a thermoplastic resin, and the moisture permeability is not sufficiently excellent. Such conventional wet-state indicator composition has a weak degree of color change upon contact with moisture, and the timing of color change is delayed, and thus there is still room for improvement in terms of color change performance. In addition, the conventional wet-state indicator has an odor that causes an unpleasant feeling to the user, and there is also a problem of odor transfer to the absorbent article.

[0017] The present invention solves such problems, and the object is to provide a wet-state indicator composition that is excellent in color change performance and has odor suppressed.

[0018] MEANS FOR SOLVING THE PROBLEMS

[0019] The present invention provides a wet-state indicator composition comprising an oily gel and a moisture-sensitive colorant composition.

[0020] In one embodiment, the oily gel is a solid having an oily substance that is a liquid at room temperature and at least one gelling agent selected from a saturated fatty acid having 16 or more carbon atoms and a derivative of the saturated fatty acid.

[0021] In one embodiment, the oily substance that is a liquid at room temperature is at least one selected from paraffin oil, naphthenic oil, and aromatic oil.

[0022] In one embodiment, the moisture-sensitive colorant composition is a composition comprising a leuco dye or a pH indicator and an anionic surfactant or a nonionic surfactant.

[0023] Further, the present invention also provides a wet-state indicator comprising any one of the wet-state indicator compositions.

[0024] Further, the present invention also provides an absorbent article comprising the wet-state indicator.

[0025] EFFECTS OF THE INVENTION

[0026] According to the present application, there is provided a wetness indicator composition which is excellent in color change properties and in which odor is suppressed. DETAILED DESCRIPTION

[0027] <Oil Gel>

[0028] The wetness indicator composition of the present application contains an oil gel. The oil gel refers to a solid having a structure of a three-dimensionally crosslinked gelling agent and a liquid oily substance contained in the structure. When the wetness indicator composition of the present application contains an oil gel, the wetness indicator composition has an intermediate hardness softer than the hardness of a hot melt type wetness indicator composition, and moisture easily penetrates into the composition, so that the composition strongly and rapidly changes color. Thus, with the wetness indicator of the present application, the state of the wetness of an article can be accurately shown. Furthermore, since the oil gel can contain a colorant or a body fluid which causes odor, the odor of the absorbent article of the present application can be reduced.

[0029] The liquid oily substance refers to a lipophilic substance which is liquid at room temperature, incompatible with water, and compatible with a non-polar solvent. For example, a wax is an oily substance, but is solid at room temperature, and thus does not conform to the liquid oily substance. Since the solid oily substance is poor in water permeability, when used in the matrix of the wetness indicator composition, the solid oily substance can adversely affect the color change properties of the wetness indicator. Examples of the liquid oily substance typically include hydrocarbon oils and liquid polymers.

[0030] The hydrocarbon oil includes paraffin oil, naphthenic oil, and aromatic oil. From the viewpoint of improving water permeability, the weight average molecular weight of the hydrocarbon oil is preferably 200 to 2000. From the viewpoint of improving compatibility with the wetness-sensitive colorant composition, the hydrocarbon oil preferably contains at least one selected from paraffin oil and naphthenic oil, more preferably contains paraffin oil.

[0031] A commercially available product can be used as the hydrocarbon oil. Examples of the commercially available hydrocarbon oil include White Oil Broom 350 (trade name) manufactured by Kukdong Oil & Chemicals Co. Ltd.; Diana Fresia PW32 (trade name), Diana Process Oil PW-90 (trade name), and Daphne Oil KP-68 (trade name) manufactured by Idemitsu Kosan Co., Ltd.; Nyflex 222B (trade name) manufactured by Nynas AB; SUNPURE N90 manufactured by JAPAN SUN OIL COMPANY, LTD.; KN4010 (trade name) manufactured by PetroChina Company Limited; Enerper M1930 (trade name) manufactured by BP Chemicals Ltd.; Kaydol (trade name) manufactured by Crompton Corporation; and Primol 352 (trade name) manufactured by Esso Standard Oil.

[0032] The liquid polymer refers to a polymer that exhibits a liquid state at room temperature. The type of the polymer is not particularly limited, but is typically at least one polymer selected from the group consisting of polybutene, polybutadiene, polyisobutylene, and polyisoprene. From the viewpoint of improving water permeability, the weight average molecular weight of the liquid polymer is preferably from 2000 to 100000, more preferably from 2000 to 80000. From the viewpoint of improving compatibility with the moisture-sensitive colorant composition, the liquid polymer preferably contains polybutene.

[0033] A commercially available product can be used as the liquid polymer. Examples of the liquid polymer as a commercially available product include Nisseki Polybutene HV-300 (trade name) and Nisseki Polybutene HV-1900 (trade name) manufactured by ENEOS Corporation, B-1000 (trade name) and BI-2000 (trade name) manufactured by Nippon Soda Co., Ltd., Tetrax (trade name) and Himol (trade name) manufactured by JX Energy Corporation, LIR-15 (trade name) and LIR-50 (trade name) manufactured by KURARAY CO., LTD., and Nipol IR2200 (trade name) manufactured by Zeon Corporation.

[0034] The liquid oily substance is contained in the oil gel by being held by the three-dimensionally crosslinked gelling agent. The three-dimensionally crosslinked gelling agent in the presence of the liquid oily substance can be a known substance. From the viewpoint of improving water permeability, the gelling agent is preferably a saturated fatty acid having 16 or more carbon atoms and a derivative of the saturated fatty acid.

[0035] The liquid oily substance is contained in the oil gel by being held by the three-dimensionally crosslinked gelling agent. The three-dimensionally crosslinked gelling agent in the presence of the liquid oily substance can be a known substance. From the viewpoint of improving water permeability, the gelling agent is preferably a saturated fatty acid having 16 or more carbon atoms and a derivative of the saturated fatty acid.

[0036] The saturated fatty acid refers to a fatty acid having no double bond or triple bond in a carbon chain. The fatty acid is an aliphatic carboxylic acid having at least one carboxyl group. The saturated fatty acid having a hydroxyl group is preferred because it is easily crosslinked to exhibit good performance of the indicator composition fully gelled. The saturated fatty acid is preferably in a chain form. Furthermore, the chain saturated fatty acid is preferably a straight-chain saturated fatty acid.

[0037] The saturated fatty acid more preferably has 16 to 36 carbon atoms, and further preferably has 18 to 20 carbon atoms. Specific examples of the saturated fatty acid having 16 or more carbon atoms include arachidic acid having 20 carbon atoms, stearic acid having 18 carbon atoms, 12-hydroxystearic acid having 18 carbon atoms, heptadecanoic acid having 17 carbon atoms, palmitic acid having 16 carbon atoms, and 16-hydroxyhexadecanoic acid having 16 carbon atoms. Among them, 12-hydroxystearic acid is particularly preferred.

[0038] The saturated fatty acid derivative refers to a compound in which a part of the saturated fatty acid is substituted with a coexisting group. The saturated fatty acid derivative can have 16 or more carbon atoms, preferably 16 to 36 carbon atoms, more preferably 18 to 20 carbon atoms. For example, a fatty acid amide, a fatty acid alkyl ester, a fatty acid metal salt, a monoglyceride, a diglyceride, a sorbitan fatty acid ester, or a diglycerol fatty acid ester having 16 or more carbon atoms can be used as the saturated fatty acid derivative. The preferred saturated fatty acid derivative includes a saturated fatty acid metal salt.

[0039] The saturated fatty acid derivative particularly preferably has a chemical structure derived from stearic acid. The "chemical structure derived from stearic acid" refers to a unit represented by the following formula

[0040] CH3(CH2) 16 COOH (1)

[0041] The saturated fatty acid derivative also includes a chemical structure in which a part of Formula (1) is substituted with another coexisting group (e.g., hydroxyl group, alkyl group, alkali metal, or alkaline earth metal), and an oligomer or polymer having a unit represented by Formula (1).

[0042] The fatty acid metal salt is preferably a metal salt having a chemical structure derived from stearic acid, and specific examples thereof include sodium stearate having 18 carbon atoms and lithium 12-hydroxystearate, and magnesium stearate having 36 carbon atoms. Among them, lithium 12-hydroxystearate is particularly preferred.

[0043] When the wet-state indicator composition of the present application contains 12-hydroxystearic acid and lithium 12-hydroxystearate as the gelling agent, an oily substance is easily solidified to prepare an oily gel having an appropriate hardness. When the oily gel is formed to have an appropriate hardness, moisture easily penetrates into the gel. Since the moisture easily penetrates, the moisture and the surfactant easily coexist, the generation of protons is promoted, and the discoloration of the colorant is promoted.

[0044] The gelling agent is blended with the oily substance to form a continuous porous body similar to a tissue, and a structure in which the oily substance is confined in the voids of the continuous porous body is formed. By blending the liquid oily substance with the gelling agent, an oily gel having an appropriate hardness is obtained, and the oily gel has a fine continuous porous body. In the wet-state indicator composition of the present application, since the oily gel has a fine continuous porous structure, for example, moisture such as urine and body fluid can easily penetrate therein.

[0045] The gelling agent is contained in the wet-state indicator composition in an amount of 2 to 80 mass%, preferably 5 to 70 mass%, more preferably 10 to 50 mass%, based on the total amount of the oily gel and the moisture-sensitive colorant composition. By adjusting the content of the gelling agent in the wet-state indicator composition within the above range, the compatibility between the liquid oily substance and the colorant is improved, and the generation of protons is easily promoted, and the wet-state indicator composition of the present application can exhibit a clear and rapid coloration.

[0046] <Moisture-sensitive colorant composition>

[0047] The wet-state indicator composition of the present application contains a moisture-sensitive colorant composition. The moisture-sensitive colorant composition refers to a composition containing a colorant that substantially discolors upon receiving protons and a surfactant that releases protons in the presence of water. As the colorant and the surfactant used in the moisture-sensitive colorant composition, known colorants and surfactants can be used in combination.

[0048] Coloring agents include dyes, indicators, and pigments. Specific examples of coloring agents that can be used include oxazolidine-based dyes, azo-based dyes, methine-based dyes, anthraquinone-based dyes, and leuco dyes. From the viewpoint of obtaining a rapid and clear color change, the coloring agent preferably contains a leuco dye and a pH indicator. Since the leuco dye or the pH indicator has strong proton sensitivity, the use of the leuco dye or the pH indicator improves the color change performance of the wet-state indicator composition.

[0049] A leuco dye is a dye that can change between two chemical species, one of which is colorless. The reversible transformation is induced by heat, light, or pH; thus, examples of thermochromism, photochromism, and halochromism are produced, respectively. Typical irreversible transformation is induced by reduction or oxidation. The colorless form is sometimes referred to as the leuco form.

[0050] The leuco dye is not limited as long as it sufficiently colors, and a known or commercially available leuco dye can be used. For example, the following compounds, such as leuco dyes that can be halochromic, can be appropriately used. These can be used alone, or in the form of two or more thereof.

[0051] (a) Fluorans: 2'-[(2-chlorophenyl)amino]-6'-(dibutylamino)-spiro[isobenzofuran-1(3H),9'-(9H)xanthene]-3-one, 3-diethylamino-6-methyl-7-chlorofluorane, 3-dimethylaminobenzo(a)-fluorane, 3-amino-5-methylfluorane, 2-methyl-3-amino-6,7-dimethylfluorane, 2-bromo-6-cyclohexylaminofluorane, 6'-ethyl(4-methylphenyl)amino-2'-(N-methylphenylamino)-spiro(isobenzofuran 1(3H),9'-(9H)xanthene)-3-one, 3,6-diphenylaminofluorane, 9-ethyl(3-methylbutyl)amino-spiro[12H-benzo(a)xanthene-12,1'(3'H)isobenzofuran]-3'-one, and 2'-[bis(phenylmethyl)amino]-6'-(diethylamino)-spiro-[isobenzofuran-1(3H),9'-(9H)xanthene]-3-one;

[0052] (b) Fluorens: 3,6-bis(diethylamino)fluorene spiro(9,3')-4'-azaphthalide and 3,6-bis(diethylamino)fluorene spiro(9,3')-4',7'-diazaphthalide;

[0053] (c) Diphenylmethane phthalides: 3,3-bis-(p-ethoxy-4-dimethylaminophenyl)phthalide;

[0054] (d) diphenylmethane azaphthalides: 3,3-bis-(l-ethoxy-4-diethylaminophenyl)-4- azaphthalide and 3,3-bis(4-diethylamino-2-ethoxyphenyl)-4-azaphthalide;

[0055] (e) indolylphthalides: 3,3-bis(n-butyl-2-methylindol-3-yl)phthalide and 3,3-bis(l- ethyl-2-methylindol-3-yl)phthalide;

[0056] (f) phenylindolylphthalides: 3-(l-diethylaminophenyl)-3-(l-ethyl-2-methylindol-3- yl)phthalide;

[0057] (g) phenylindolylazaphthalides: 3-(2-ethoxy-4-diethylaminophenyl)-3-(l-ethyl-2- methylindol-3-yl)-4-azaphthalide and 3-[2-ethoxy-4-(N-ethyl-anilinyl)phenyl]-3-(l- ethyl-2-methylindol-3-yl)-4-azaphthalide;

[0058] (h) styrylquinolines: 2-(3-methoxy-4-dodecyloxyphenylstyryl)quinoline;

[0059] (i) diazaronhodamine lactones: 2-(dimethylamino)-8-(dimethylamino)-4-methyl- spiro[5H-(l)benzopyrano(2,3-d)pyrimidine-5,l'(3'H)-isobenzofuran];

[0060] (j) pyridines: 2,6-diphenyl-4-(6-dimethylaminophenyl)pyridine and 2,6-diethoxy-4- (4-diethylaminophenyl)pyridine;

[0061] (k) quinazolines: 2-(4-N-methyl-anilinylphenyl)-l-phenoxyquinazoline and 2-(4- dimethylaminophenyl)-4-(l-methoxyphenoxy)quinazoline;

[0062] (l) bisquinazolines: 4,4'-(ethylenedioxy)-bis[2-(l-diethylaminophenyl)quinazoline] and 4,4'-(ethylenedioxy)-bis[2-(l-di-n-butylaminophenyl)quinazoline];

[0063] (m) ethylenophthalides: 3,3-bis[l,l-bis-(p-dimethylaminophenyl)ethylidene-3]phthalide;

[0064] (n) ethylene azaphthalides: 3,3-bis[l,l-bis-(p-dimethylaminophenyl)ethylidene-2]-4- azaphthalide and 3,3-bis[l,l-bis-(p-dimethylaminophenyl)ethylidene-2]-4,7- diazaphthalide; and

[0065] (o) aminophthalides: 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (crystal violet lactone).

[0066] Further, at least one of an aminophthalide and a fluoran is used as a colorant. As a fluoran, in particular, 2'-[bis(phenylmethyl)amino]-6'-(diethylamino)-spiro-[isobenzo- furan-l(3H),9'-(9H)xanthene]-3-one, 2'-[(2-chlorophenyl)amino]-6'-(dibutylamino)- spiro[isobenzofuran-l(3H),9'-(9H)xanthene]-3-one, and 3,6-diphenylaminofluoran are more preferable. As an aminophthalide, crystal violet lactone is particularly preferable.

[0067] When the wet-state indicator composition of the present application contains a leuco dye as a colorant, the leuco dye is easily ring-opened by protons generated in the presence of a surfactant and urine (moisture), and the wet-state indicator composition is colored quickly, which is preferable. The content of the leuco dye can be appropriately determined depending on the type of the leuco dye and the desired color tone.

[0068] A pH indicator refers to a chemical added to a reaction liquid in order to know an equivalent point by a directly visible change such as a color change or a precipitate formation in titration. An acid-base indicator is used as a pH indicator. Specific examples of the pH indicator include phenothalin, methyl orange, potassium chromate, bromocresol green, and bromophenol blue.

[0069] The colorant is contained in the wet-state indicator composition in an amount of 0.01 to 7 mass%, preferably 0.05 to 5 mass%, more preferably 0.1 to 4 mass%, based on the total amount of the oily gel and the moisture-sensitive colorant composition. By adjusting the content of the colorant in the wet-state indicator composition within the above range, the color difference between the dry state and the wet state of the wet-state indicator composition increases, and the color change can be easily perceived.

[0070] The colorant is used in combination with a surfactant to become a moisture-sensitive colorant composition. The surfactant improves the compatibility of the colorant with other components, and the colorant is easily contained in the oily gel.

[0071] The surfactant is a substance that exhibits a function of causing the colorant to change color in the presence of moisture. For example, an anionic surfactant and a nonionic surfactant are preferable because they are easily wetted with water to generate protons, and many colorants change color by receiving protons.

[0072] Examples of anionic surfactants include:

[0073] Alkali metal alkyl sulfates such as sodium dodecyl sulfate and potassium dodecyl sulfate;

[0074] Sodium dodecyl polyethylene glycol ether sulfate;

[0075] Ammonium alkyl sulfates such as ammonium dodecyl sulfate;

[0076] Sodium sulfosinoate;

[0077] Alkyl sulfonates such as alkali metal salts of sulfonated paraffins and ammonium salts of sulfonated paraffins;

[0078] Fatty acid salts such as sodium laurate, triethanolamine oleate, and triethanolamine abietate;

[0079] Alkyl aryl sulfonates such as sodium dodecylbenzenesulfonate and alkali metal sulfates of alkali phenol hydroxyethylene;

[0080] High alkyl naphthalene sulfonates;

[0081] Naphthalene sulfonic acid formalin condensates;

[0082] Dialkyl sulfosuccinates;

[0083] Polyoxyethylene alkyl sulfates; and

[0084] Polyoxyethylene alkyl aryl sulfates.

[0085] Examples of nonionic surfactants include:

[0086] Polyoxyethylene alkyl ethers;

[0087] Polyoxyethylene alkyl aryl ethers;

[0088] Sorbitan fatty acid esters;

[0089] Polyoxyethylene sorbitan fatty acid esters;

[0090] Fatty acid monoglycerides such as glycerol monolaurate;

[0091] Polyoxyethylene oxypropylene copolymers; and

[0092] Condensation products of ethylene oxide with fatty amines, amides or acids.

[0093] The surfactant is preferably an anionic surfactant, more preferably a linear alkylbenzene sulfonate, further preferably sodium dodecylbenzene sulfonate. When sodium dodecylbenzene sulfonate is used as the surfactant, the colorant is easily dissolved in the oily substance, and the oily substance is easily brought into contact with water, thereby easily generating protons. Since protons are easily provided to the colorant, the discoloration of the wet-state indicator composition proceeds rapidly.

[0094] The surfactant is contained in the wet-state indicator composition in an amount of 1 to 30 mass%, preferably 3 to 20 mass%, more preferably 5 to 15 mass%, based on the total amount of the oily gel and the moisture-sensitive colorant composition. By adjusting the content of the surfactant in the wet-state indicator composition within the above range, the sensitivity of the wet-state indicator composition to moisture is improved, and the wet state is accurately shown.

[0095] <pigment>

[0096] In the wet-state indicator composition of the present application, a pigment can be used as needed. The pigment includes inorganic pigments and organic pigments. The inorganic pigments include colored inorganic pigments and extender pigments.

[0097] Examples of the colored inorganic pigments include white titanium dioxide, white lead (basic lead carbonate), zinc white (zinc oxide), zinc-battery white (barium sulfate / zinc sulfide);

[0098] red iron (III) oxide, red lead (lead oxide), silver vermilion (mercury sulfide), molybdenum-red;

[0099] light yellow chrome yellow (lead chromate), cadmium yellow (cadmium sulfide), zinc chromate, lissajous (lead monoxide);

[0100] bluish ultramarine blue, Prussian blue, cobalt blue (cobalt aluminate); and

[0101] Black pigments include iron black (iron (II, III)) and carbon black.

[0102] Examples of the extender pigments include barite (barium sulfate), gypsum (hydrated calcium sulfate), kaolin (white clay), silica (silicon dioxide), white carbon (precipitated silica), talc, barium carbonate, and calcium carbonate.

[0103] Examples of the organic pigment include lakes and colored organic pigments. There are two types of lakes, one of which is a dyed lake, which is a pigment obtained by dyeing a body pigment with a dye. The other lake is a lake in which a dye becomes insoluble by reacting with a divalent or higher valent metal salt, and examples thereof include azo lakes formed from azo dyes.

[0104] Examples of the colored organic pigment include insoluble azo pigments, metal phthalocyanine pigments, anthraquinone pigments, and vat pigments. Among azo dyes, anthraquinone dyes, and indigo dyes, which are representative types of dyes based on chemical structures, a substance that is insoluble in water is used as a pigment. Furthermore, metal phthalocyanine pigments have a color tone from blue to green, and have excellent light resistance.

[0105] <Viscosity-increasing agent resin>

[0106] In the wet-state indicator composition of the present application, a viscosity-increasing agent resin can be used as needed. Examples of the viscosity-increasing agent resin include natural rosin, modified rosin, hydrogenated rosin, glycerol ester of natural rosin, glycerol ester of modified rosin, pentaerythritol ester of natural rosin, pentaerythritol ester of modified rosin, pentaerythritol ester of hydrogenated rosin, copolymer of natural terpene, three-dimensional polymer of natural terpene, hydrogenated derivative of copolymer of hydrogenated terpene, polyterpene resin, hydrogenated derivative of phenol-based modified terpene resin, aliphatic petroleum hydrocarbon-based resin, hydrogenated derivative of aliphatic petroleum hydrocarbon-based resin, aromatic petroleum hydrocarbon-based resin, hydrogenated derivative of aromatic petroleum hydrocarbon-based resin, cyclic aliphatic petroleum hydrocarbon-based resin, and hydrogenated derivative of cyclic aliphatic petroleum hydrocarbon-based resin.

[0107] As the tackifier resin, commercially available products can be used. Examples of such commercially available products include KE-604 (trade name) manufactured by Arakawa Chemical Industries, Ltd., ARKON P100 (trade name) and ARKON M100 (trade name) manufactured by Wuzhou Sun Shine Forestry & Chemicals Co., Ltd., Foral AX-E (trade name) manufactured by Eastman Chemical Company, FTR6100 manufactured by Mitsui Chemicals, Inc., CLEARON M105 (trade name) manufactured by YASUHARA CHEMICAL CO., LTD., ECR5600 (trade name) and ECR179EX (trade name) manufactured by Exxon Mobil Corporation, and Quinton DX390 (trade name) manufactured by Zeon Corporation. These commercially available tackifier resins can be used alone or in combination.

[0108] RHR-101HK and Foral AX-E, which are rosin-based tackifier resins, are particularly preferable as the tackifier resin in view of the compatibility between the surfactant and the liquid oily substance.

[0109] <Other Components>

[0110] The wet-state indicator composition of the present application can contain at least one of the following additives as a component other than the above components: thickening agents (styrene-based polymers, olefin-based polymers), antioxidants (phenol-based, phosphorus-based, and sulfur-based), ultraviolet absorbers, optical brighteners, non-fading dyes, fragrances, disinfectants, antibacterial agents, repellents, skin care components, non-fading pigments, lubricants, and fillers.

[0111] <Method for Producing the Wet-State Indicator Composition>

[0112] The wet-state indicator composition of the present application is prepared by mixing the above components while heating as necessary. When the components are mixed until they become uniform and cooled to room temperature, the wet-state indicator composition is gelled and becomes hard.

[0113] For example, all the components contained in the wet-state indicator composition are put into a container, and the components are dissolved or uniformly dispersed, heated and stirred until a uniform state is obtained. The heating temperature is suitably adjusted generally in the range of 50 to 250°C, preferably 70 to 200°C, more preferably 80 to 160°C. The heating time is determined in consideration of the heating temperature, but is adjusted generally between 5 minutes and 1 hour, preferably between 10 minutes and 40 minutes.

[0114] The uniform composition can be prepared by putting each component into a container in turn and mixing the components sequentially.

[0115] < Wet-state indicator >

[0116] The wet-state indicator composition is molded into a suitable shape, and is used as a wet-state indicator, optionally in combination with components, substances or materials that do not impair the function of the wet-state indicator. The wet-state indicator composition can be used as a single material, for example, by being applied onto a substrate such as a film or paper, or can be used in combination with a water-absorbing substance. The wet-state indicator of the present application can be used for various articles in which detection of a wet state is required, but is particularly preferably used for absorbent articles.

[0117] When the wet-state indicator composition and the water-absorbing substance are combined, examples of embodiments thereof are as follows. That is,

[0118] The wet-state indicator composition and the water-absorbing substance are positioned adjacent to each other;

[0119] The wet-state indicator composition is mixed with the water-absorbing substance; and

[0120] The wet-state indicator composition and the water-absorbing substance are heated to be compatible with each other.

[0121] The water-absorbing substance can be a known resin having water-absorbing properties such as polyvinyl alcohol or an acrylic resin, or a known substance having water-absorbing properties such as wood, paper or cloth, and the shape of the water-absorbing substance can be any shape such as a sheet shape, a block shape, a granular shape or a fibrous shape.

[0122] < Absorbent article >

[0123] The absorbent article of the present application includes a water-absorbing substance and the wet-state indicator composition of the present application. Specifically, the absorbent article is a so-called sanitary material such as a sanitary napkin, an incontinence pad, a maternity panty, a breast pad, an underarm sweat pad, a paper diaper, a pet sheet, a hospital gown and a white surgical gown.

[0124] The absorbent article is composed of at least one member selected from the group consisting of a woven fabric, a nonwoven fabric, a rubber, a resin, paper, and a polyolefin film, and the wet state indicator according to the present application. For reasons such as durability and cost, the polyolefin film is preferably a polyethylene film.

[0125] When the wet state indicator of the present application is used for a paper diaper, the wet state indicator is preferably attached to the surface of a powder or a particle of a water-absorbing resin stored in the disposable diaper. In addition to the paper diaper, by applying the wet state indicator of the present application to the surface of various substrates such as resin particles, a woven fabric, a nonwoven fabric, a resin sheet, paper, a resin molded article, metal, and wood in any manner, a moisture wet state indicator action can be provided on the surface of the various substrates.

[0126] Examples

[0127] Hereinafter, the present application will be described using examples for the purpose of describing the present application in more detail and specifically, but these examples do not limit the present application at all.

[0128] In the examples and comparative examples, the components to be blended in the composition for a wet state indicator are shown below.

[0129] The liquid oily substance constituting the oily gel is as follows.

[0130] < Liquid Oily Substance >

[0131] Paraffin oil (Liquid Paraffin (trade name) manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0132] Paraffin oil (Daphne Oil KP-68 (trade name) manufactured by Idemitsu Kosan Co., Ltd.)

[0133] Paraffin oil (Diana Fresia PW-32 (trade name) manufactured by Idemitsu Kosan Co., Ltd.)

[0134] Naphthenic oil (KNH4010 (trade name) manufactured by PetroChina Company Limited)

[0135] Liquid polybutene (Nisseki Polybutene HV-100 (trade name) manufactured by JXTG Nippon Oil & Energy Corporation)

[0136] < Wax >

[0137] Fischer-Tropsch wax (Sasol H1 (trade name) manufactured by Sasol Limited)

[0138] The colorant constituting the moisture-sensitive colorant composition is as follows.

[0139] <colorant>

[0140] pH indicator (Bromocresol green (trade name) manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0141] Leuco dye (Crystal violet lactone (trade name) manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0142] Leuco dye (Blue 1 (trade name) manufactured by Yamada Chemical Co., Ltd.)

[0143] Leuco dye (Blue 203 (trade name) manufactured by Yamada Chemical Co., Ltd.)

[0144] The surfactant constituting the moisture-sensitive colorant composition is as follows.

[0145] <surfactant>

[0146] Anionic surfactant (Sodium dodecylbenzenesulfonate (reagent name) manufactured by KANTO CHEMICAL CO., INC.)

[0147] Anionic surfactant (Aerosol QT-100 (trade name) manufactured by SOLVAY)

[0148] Nonionic surfactant (SURFLIC-AQ250 (trade name) manufactured by Itoh Oil Chemicals Co., Ltd.)

[0149] The gelling agent constituting the oily gel is as follows.

[0150] <gelatinizing agent (saturated fatty acid having 16 or more carbon atoms or derivative thereof)>

[0151] Saturated fatty acid having 18 carbon atoms (Stearic acid (reagent name) manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0152] Saturated fatty acid having 16 carbon atoms (16-hydroxyhexadecanoic acid (reagent name) manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0153] Saturated fatty acid having 18 carbon atoms (12-hydroxystearic acid (reagent name) manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0154] Saturated fatty acid derivative having 18 carbon atoms (sodium stearate (reagent name) manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0155] Saturated fatty acid derivative having 36 carbon atoms (magnesium stearate (reagent name) manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0156] <Non-gelling agent (hydrocarbon not meeting "gelling agent")>

[0157] Aliphatic alkane having 17 carbon atoms (n-heptadecane (reagent name) manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0158] Aliphatic alkane having 20 carbon atoms (eicosane (reagent name) manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0159] Aliphatic alcohol having 18 carbon atoms (1-octadecanol (reagent name) manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0160] Unsaturated fatty acid having 18 carbon atoms (oleic acid (reagent name) manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0161] Saturated fatty acid having 10 carbon atoms (decanoic acid (reagent name) manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0162] Saturated fatty acid having 14 carbon atoms (3-hydroxytetradecanoic acid (reagent name) manufactured by Combi-Blocks Inc.)

[0163] <Viscosity-increasing agent resin>

[0164] Hydrogenated rosin-based tackifier resin (RHR-101HK (trade name) manufactured by Wuzhou Sun Shine Forestry & Chemicals Co., Ltd.)

[0165] Hydrogenated rosin-based tackifier resin (Foral AX-E (trade name) manufactured by Eastman Chemical Japan Ltd.)

[0166] Hydrogenated hydrocarbon-based tackifier resin (HD-1100 (trade name) manufactured by Tiajin Luhua Chemical Co., Ltd.)

[0167] Hydrogenated hydrocarbon-based tackifier resin (ARKON P100 (trade name) manufactured by Arakawa Chemical Industries, Ltd.)

[0168] Hydrogenated hydrocarbon-based tackifier resin (ECR5400 (trade name) manufactured by Exxon Mobil Corporation)

[0169] Hydrogenated hydrocarbon-based tackifier resin (FTR-6100 (trade name) manufactured by Mitsui Chemicals, Inc.)

[0170] The above components were blended in the ratios shown in Tables 1 to 4, and stirred and mixed to prepare the wet indicator composition. Specifically, the components were placed in a 70 ml container, and heated to 130°C with a glass column heater, and the compound of the components was stirred for 20 minutes using a stirrer at a stirring speed of 300 to 500 rpm. All the numerical values (composition) shown in Tables 1 to 4 related to the wet indicator composition are parts by mass (solid content).

[0171] For the wet indicator composition of the examples and comparative examples, it was confirmed whether an oily gel was formed in appearance, and phase separation, odor, discoloration time, and bleeding were evaluated. The evaluation details are shown below.

[0172] <Appearance>

[0173] The wet indicator composition of the examples and comparative examples was allowed to stand at room temperature for 1 day, and the appearance of each composition was visually observed to confirm whether an oily gel was produced.

[0174] Whether the wet indicator composition was a gel was evaluated by the flowability of the composition and bleeding of oily substances.

[0175] The composition was placed in a container, the composition was not flowable even when the container was tilted, and a commercially available oil blotter was pressed against the composition, and when oil seepage was visually recognized, the composition was determined to be a gel. The evaluation results are shown in Tables 1 to 4.

[0176] The hardness of the wet-state indicator composition was evaluated according to the following criteria.

[0177] In an environment of 23°C, a cylindrical SUS probe was pressed against the wet-state indicator composition of each example and comparative example to apply a load of 1 kg, and after 8 seconds, the degree of penetration of the SUS probe into the composition was confirmed to evaluate the hardness of the composition. The evaluation criteria were as follows.

[0178] Penetration of a 16 mm diameter probe of 4 mm or more: very soft

[0179] Penetration of a 16 mm diameter probe of less than 4 mm: soft

[0180] Penetration of a 5 mm diameter probe of less than 4 mm: hard

[0181] Penetration of a 3 mm diameter probe of less than 4 mm: very hard

[0182] <Phase separation>

[0183] Using 30 g of the wet-state indicator composition of each example and comparative example as an evaluation sample, 30 g of each sample was placed in a 70 ml glass container, and allowed to stand in a heating oven at 100°C. After aging the sample for 24 hours, the presence or absence of phase separation was visually confirmed to evaluate whether the composition was uniform or non-uniform.

[0184] A: No phase separation was observed, and no turbidity was observed

[0185] B: No phase separation was observed, and was uniform, but slight turbidity was observed

[0186] C: A slightly transparent supernatant was observed at the top

[0187] D: A clear phase separation was observed

[0188] <Odor>

[0189] Using 30 g of the wet-state indicator composition of each example and comparative example as an evaluation sample, 30 g of each sample was placed in a 70 ml glass container, covered with aluminum foil, and then allowed to stand in a desiccator at 40°C for 1 hour. Thereafter, the container was taken out of the desiccator, the aluminum foil was removed, and the odor was confirmed. The evaluation criteria were as follows.

[0190] A: No odor was felt

[0191] B: Slight odor is felt

[0192] C: Obvious odor is felt, but not unpleasant

[0193] D: Strong and unpleasant odor is felt

[0194] <Discoloration Test>

[0195] The wet-state indicator composition of each example and comparative example was placed in a glass bottle, and the glass bottle was heated in a drier at 100°C until a uniform liquid was obtained. Subsequently, an appropriate amount of each composition was dropped on a coverage test paper (JIS K-5600 manufactured by TP Giken Co., Ltd.), and then a uniform film having a thickness of about 27.5 μm was quickly prepared with a doctor blade coater (No. 12 manufactured by Dai-ichi Rika Co., Ltd.), and the color of the coated film was recorded as the initial state (sample). It should be noted that, for samples in which no discoloration was observed, the symbol "-" is shown in the table.

[0196] The sample was allowed to stand at room temperature for 30 minutes or more, and then placed on a table, and water was sprayed on the sample. Thereafter, the final color, the degree of hue change (color difference), and the time until the color bleeds out and becomes the final color were recorded and described in Tables 1 to 4.

[0197] <Color Difference (Degree of Hue Change)>

[0198] The evaluation criteria for the degree of hue change are as follows.

[0199] A: Very obvious difference in hue is observed before and after spraying

[0200] B: Obvious difference in hue is observed before and after spraying

[0201] C: Slight difference in hue is observed before and after spraying

[0202] D: No difference in hue is observed before and after spraying

[0203] <Bleeding>

[0204] After the color of the sample becomes the final color, the water-applied sample is vertically tilted from the table, and the bleeding associated with the dripping of moisture is recorded. When the color bleeds out due to water, the application pattern of the wet-state indicator applied to the diaper is disrupted, and the visibility deteriorates. Therefore, when the bleeding is less, it is preferred as a wet-state indicator composition. The evaluation criteria are as follows.

[0205] A: No bleeding is observed

[0206] B: slight bleeding was observed, but the shape of the applied portion was retained

[0207] C: bleeding was observed, but the shape of the applied portion was retained

[0208] D: bleeding was observed, and the shape of the applied portion was damaged and not retained

[0209] <Time until it becomes the final color>

[0210] The time from spraying the water until it becomes the final color was measured and described in Tables 1 to 4. It should be noted that for the compositions for which no color difference was observed, the symbol "-" is shown in the table.

[0211] [Table 1]

[0212]

[0213] [Table 2]

[0214]

[0215] [Table 3]

[0216]

[0217] [Table 4]

[0218]

[0219] As shown in Tables 1 and 2, the wet-state indicator composition of the examples had an oily gel, the components were not separated, and no strong odor was generated. Furthermore, in the wet-state indicator composition of the examples, the color change was clear, the time from the initial stage to the final discoloration was short, and the color was not blurred.

[0220] On the other hand, as shown in Tables 3 and 4, since the wet-state indicator compositions of Comparative Examples 1 to 9 did not have an oily gel, phase separation occurred, and the composition was not uniform, an odor was generated, or the discoloration change (color difference) was small.

[0221] The wet-state indicator composition of Comparative Example 10 had an oily gel, but did not contain a surfactant, so that almost no protons were generated, and the color difference could not be clearly shown.

[0222] In the absence of a surfactant, the colorant is almost not compatible with the oily substance and other components, and the colorant is not contained in the gel. The wet-state indicator composition of Comparative Example 10 could not suppress the odor of the colorant.

[0223] Industrial applicability

[0224] The wetness indicator composition of the present invention provides a wetness indicator to be attached to an absorbent article, such as a diaper or a napkin.

Claims

1. A wetness indicator composition comprising as a matrix an oily gel and a moisture- sensitive colorant composition, wherein the oily gel has a fine continuous porous structure and is a solid having a structure of three-dimensionally cross-linked gelling agent and an oily substance which is liquid at room temperature contained in the structure, wherein the gelling agent is selected from saturated fatty acids having 16 to 36 carbon atoms and derivatives of the saturated fatty acids, and wherein the moisture-sensitive colorant composition is a composition comprising a leuco dye or a pH indicator and an anionic or non-ionic surfactant.

2. The wetness indicator composition according to claim 1, wherein the oily substance which is liquid at room temperature is at least one selected from paraffin oil, naphthenic oil and aromatic oil.

3. A wetness indicator comprising the wetness indicator composition according to claim 1 or 2.

4. An absorbent article comprising the wetness indicator according to claim 3.

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