Moisture indicator composition

Abstract

A wet-state indicator composition is provided, which is excellent in color change performance and in which odor is suppressed. Disclosed is a wet-state indicator composition comprising: a hydrocarbon oil (A); at least one selected from saturated fatty acids having 16 or more carbon atoms and derivatives of the saturated fatty acids (B); and a moisture-sensitive colorant composition (C), wherein component (B) is contained in an amount of 2 to 85 parts by mass based on 100 parts by mass of the total amount of components (A) to (C).

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. 2020-129592, filed in Japan on July 30, 2020 (which is incorporated herein by reference in its entirety). Technical Field

[0003] This invention relates to a wet indicator, which is a component that indicates the presence of moisture by changing color. Background Technology

[0004] Examples of articles that function through contact with moisture include moisture exchangers (HEMs), humidity detectors, autoclave (sterilization) belts, packaged articles, and absorbent articles. Moisture indicators are known as devices that indicate these articles are wet and function. Wetting refers to the state in which the article comes into contact with a liquid containing water (such as bodily fluids, i.e., moisture). Indicators are tools for displaying and marking information.

[0005] Typically, wetness indicators change color to indicate whether an article is dry or wetted. For example, when an article is wet, the wetness indicator is colored or changes color to show the wetness of the article.

[0006] Patent documents 1 to 3 describe compositions for use as wetness indicators in combination with absorbent articles (such as diapers).

[0007] Patent Document 1 describes a wet indicator composition that changes color in response to pH changes. This 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. This hot melt humidity indicator composition contains components such as a water-insoluble thermoplastic polymer, anionic surfactant, and leuco dye ([Abstract], [Claim 1],

[0006] ).

[0009] Patent document 3 describes a humidity / fluid indicator composition that is colorless in its initial state but can provide a variety of final wet color options in the presence of water. This humidity / fluid indicator composition contains a leuco dye and a color developer in a hot melt adhesive matrix ([Abstract],

[0001] ,

[0008] ).

[0010] Existing technical documents

[0011] Patent documents

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

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

[0014] Patent Document 3: JP 2018-517894 A Summary of the Invention

[0015] The problem to be solved by the present invention

[0016] However, in conventional wet indicator compositions, the matrix (i.e., the main continuous phase) is composed of thermoplastic resin, and its moisture permeability is not sufficiently good. Such conventional wet indicator compositions exhibit weak color change upon contact with moisture, and the timing of the color change is delayed, thus leaving room for improvement in color-changing performance. Furthermore, conventional wet indicators have an unpleasant odor that causes discomfort to users, and there is also the problem of odor transfer to absorbent articles.

[0017] The present invention solves such problems, and its object is to provide a composition for a wet indicator that has excellent color-changing properties and suppressed odor.

[0018] means for solving problems

[0019] The present invention provides a composition for a wet indicator comprising: a hydrocarbon oil (A); at least one selected from saturated fatty acids having 16 or more carbon atoms and derivatives thereof (B); and a moisture-sensitive colorant composition (C), wherein component (B) is included in an amount of 2 to 85 parts by mass based on a total amount of 100 parts by mass of components (A) to (C).

[0020] In the embodiments, component (B) contains at least one selected from 12-hydroxystearic acid and a metal salt of 12-hydroxystearic acid.

[0021] In the embodiments, component (C) is a composition comprising a leuco dye or a pH indicator and an anionic surfactant or a nonionic surfactant.

[0022] In the implementation scheme, the anionic surfactant contains a linear alkylbenzene sulfonate.

[0023] In addition, the present invention provides a wetness indicator having a composition for a wetness indicator according to any one of the above.

[0024] In addition, the present invention provides an absorbent article having the above-mentioned wetness indicator.

[0025] Effects of the present invention

[0026] According to the present invention, a composition for a wet indicator is provided, which has excellent color-changing properties and suppressed odor. Detailed Implementation

[0027] <(A) Hydrocarbon Oil>

[0028] The hydrocarbon oil contained in the wet indicator composition of the present invention refers to a lipophilic hydrocarbon compound that is liquid at room temperature. For example, wax is a hydrocarbon compound, but it is solid at room temperature, and therefore does not meet the criteria for hydrocarbon oil. Since solid hydrocarbons have poor water permeability, they may adversely affect the color-changing properties of the wet indicator composition when used in the matrix of the wet indicator composition.

[0029] From the perspective of improving compatibility with colorants, the hydrocarbon oil preferably contains at least one selected from paraffin oil, naphthenic oil, and aromatic oil. More preferably, the hydrocarbon oil contains at least one selected from paraffin oil and naphthenic oil, and even more preferably, it contains paraffin oil. From the perspective of improving water permeability, the weight-average molecular weight of the hydrocarbon oil is preferably between 200 and 2000.

[0030] Commercially available products can be used as hydrocarbon oils. Examples of commercially available hydrocarbon oils 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 SUNOIL 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.

[0031] Based on a total amount of 100 parts by weight of hydrocarbon oil, saturated fatty acid, and wet-sensitive colorant composition (i.e., components (A) to (C)), the hydrocarbon oil is included in the wet indicator composition in an amount of 5 to 90 parts by weight, preferably 20 to 75 parts by weight, and more preferably 30 to 65 parts by weight. By adjusting the content of hydrocarbon oil in the wet indicator composition within the above range, the compatibility between the hydrocarbon oil and the colorant is improved, and protons are readily generated. Furthermore, the wet indicator composition of the present invention can exhibit obvious and rapid coloring.

[0032] <(B) Saturated fatty acids>

[0033] Saturated fatty acids are fatty acids that do not have double or triple bonds in their carbon chains. Fatty acids are aliphatic carboxylic acids that have at least one carboxyl group.

[0034] The saturated fatty acids contained in the indicator compositions of the present invention have the property of gelling the entire composition through cross-linking. Saturated fatty acids having hydroxyl groups are preferred because they readily cross-link. Saturated fatty acids are preferably in chain form. Furthermore, chain saturated fatty acids are preferably straight-chain saturated fatty acids. The saturated fatty acids are cross-linked in the presence of hydrocarbon oils, whereby the hydrocarbon oils are included in the cross-linked saturated fatty acids. The saturated fatty acids used can be known substances. From the perspective of improving water permeability, such saturated fatty acids are preferably saturated fatty acids having 16 or more carbon atoms and derivatives of said saturated fatty acids.

[0035] The wet indicator composition of the present invention comprises an oily gel formed by hydrocarbon oil being contained in three-dimensionally cross-linked saturated fatty acids. The wet indicator composition containing the oily gel has a moderate hardness, softer than that of a hot-melt wet indicator composition, and moisture readily penetrates the composition, causing a strong and rapid color change. Therefore, using the wet indicator of the present invention, the wet state of an article can be accurately displayed. Furthermore, since the oily gel can contain colorants or bodily fluids that cause odor, the odor of the absorbent article of the present invention can be reduced.

[0036] Saturated fatty acids more preferably have 16 to 36 carbon atoms, and even more preferably have 18 to 20 carbon atoms. Specific examples of saturated fatty acids having 16 or more carbon atoms include arachidic acid with 20 carbon atoms, stearic acid with 18 carbon atoms, 12-hydroxystearic acid with 18 carbon atoms, heptadecanoic acid with 17 carbon atoms, palmitic acid with 16 carbon atoms, and 16-hydroxyhexadecanoic acid with 16 carbon atoms. Among these, 12-hydroxystearic acid is particularly preferred.

[0037] Saturated fatty acid derivatives are compounds in which a portion of a saturated fatty acid is substituted by a coexisting group. Saturated fatty acid derivatives may have 16 or more carbon atoms, preferably 16 to 36 carbon atoms, and more preferably 18 to 20 carbon atoms. For example, fatty acid amides, fatty acid alkyl esters, fatty acid metal salts, monoglycerides, diglycerides, sorbitol fatty acid esters, or diglycerides having 16 or more carbon atoms can be used as saturated fatty acid derivatives. Preferred saturated fatty acid derivatives include saturated fatty acid metal salts.

[0038] Saturated fatty acid derivatives are particularly preferably those having a chemical structure derived from stearic acid. "Chemical structure derived from stearic acid" refers to a unit represented by the following formula.

[0039] CH3(CH2) 16 COOH (1)

[0040] Saturated fatty acid derivatives also include chemical structures in which a portion of formula (1) is replaced by other coexisting groups (e.g., hydroxyl, alkyl, alkali metal or alkaline earth metal) and oligomers or polymers having units represented by formula (1).

[0041] The fatty acid metal salt is preferably a metal salt having a chemical structure derived from stearic acid, and specific examples include sodium stearate and lithium 12-hydroxystearate having 18 carbon atoms, and magnesium stearate having 36 carbon atoms. Among them, lithium 12-hydroxystearate is particularly preferred.

[0042] When the wet indicator composition of the present invention contains 12-hydroxystearic acid and lithium 12-hydroxystearate, it readily undergoes three-dimensional cross-linking and readily contains hydrocarbon oils, making it easy to prepare an oily gel with appropriate hardness. When the oily gel is formed to have appropriate hardness, moisture easily permeates into the gel. Due to the ease of moisture permeation, moisture and surfactants readily coexist, promoting proton generation and promoting color change of the colorant.

[0043] Saturated fatty acids are blended with hydrocarbon oils to form a continuous porous body resembling a tissue, and a structure is formed in which the hydrocarbon oil is confined within the pores of the continuous porous body. By blending hydrocarbon oils with saturated fatty acids, an oily gel with suitable hardness is obtained, and this oily gel has a fine, continuous porous body. In the composition for wet indicators of the present invention, because the oily gel has a fine, continuous porous structure, moisture, such as urine and bodily fluids, can easily penetrate into it.

[0044] Based on the total amount of 100 parts by weight of hydrocarbon oil, saturated fatty acid, and moisture-sensitive colorant composition (i.e., components (A) to (C)), the saturated fatty acid is included in the wet indicator composition in an amount of 2 to 85 parts by weight, preferably 10 to 70 parts by weight, and more preferably 20 to 60 parts by weight. By adjusting the content of saturated fatty acid in the wet indicator composition within the above range, the compatibility between the hydrocarbon oil and the colorant is improved, and protons are readily generated. Furthermore, the wet indicator composition of the present invention can exhibit obvious and rapid coloring.

[0045] <(C) Moisture-sensitive colorant composition>

[0046] The wet indicator composition of the present invention comprises a moisture-sensitive colorant composition. A moisture-sensitive colorant composition refers to a composition comprising: a colorant that substantially changes color upon accepting a proton and a surfactant that releases a proton in the presence of water. Known colorants and surfactants can be used in combination as the colorant and surfactant used in the moisture-sensitive colorant composition.

[0047] Colorants include dyes, indicators, and pigments. Specific examples of colorants that can be used include oxazolidine-based dyes, azo-based dyes, methylene-based dyes, anthraquinone-based dyes, and leuco dyes. From the perspective of obtaining rapid and obvious color change, the colorant preferably contains a leuco dye and a pH indicator. Because leuco dyes or pH indicators have strong proton sensitivity, the use of leuco dyes or pH indicators improves the color-changing properties of compositions for wet indicators.

[0048] Leuco dyes are dyes that can change between two chemical substances, one of which is colorless. Reversible changes are caused by heat, light, or pH; resulting in examples of thermochromism, photochromism, and acid-induced color development, respectively. Typical irreversible changes are caused by reduction or oxidation. The colorless form is sometimes referred to as the leuco form.

[0049] There are no restrictions on the leuco dyes used, as long as they provide sufficient coloring, and known or commercially available leuco dyes can be used. For example, compounds that can be developed by acid can be appropriately used. These can be used alone or in two or more forms.

[0050] (a) Fluorans: 2'-[(2-chlorophenyl)amino]-6'-(dibutylamino)-spiro[isobenzofuran-1(3H),9'-(9H)xanthone]-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)xanthan)-3-one, 3,6-diphenylaminofluorane, 9-ethyl(3-methylbutyl)amino-spiro[12H-benzo(a)xanthan-12,1'(3'H)isobenzofuran]-3'-one and 2'-[bis(phenylmethyl)amino]-6'-(diethylamino)-spiro-[isobenzofuran-1(3H),9'-(9H)xanthan]-3-one;

[0051] (b) Fluorens: 3,6-bis(diethylamino)fluorenspiro(9,3')-4'-azaphthalide and 3,6-bis(diethylamino)fluorenspiro(9,3')-4',7'-diazaphthalide;

[0052] (c) Diphenylmethane phthalides: 3,3-bis-(p-ethoxy-4-dimethylaminophenyl)phthalide;

[0053] (d) Diphenylmethane azirphthalides: 3,3-bis-(1-ethoxy-4-diethylaminophenyl)-4-azirphthalide and 3,3-bis(4-diethylamino-2-ethoxyphenyl)-4-azirphthalide;

[0054] (e) Indolephthalides: 3,3-bis(n-butyl-2-methylindole-3-yl)phthalide and 3,3-bis(1-ethyl-2-methylindole-3-yl)phthalide;

[0055] (f) Phenylindolylphthalides: 3-(1-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)phthalide;

[0056] (g) Phenylindole azirphthalides: 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindole-3-yl)-4-azirphthalide and 3-[2-ethoxy-4-(N-ethylphenylamino)phenyl]-3-(1-ethyl-2-methylindole-3-yl)-4-azirphthalide;

[0057] (h) Styrenicoquinolines: 2-(3-methoxy-4-dodecyloxystyrenico)quinoline;

[0058] (i) Diazazanordamine lactones: 2-(dimethylamino)-8-(dimethylamino)-4-methyl-spiro[5H-(1)benzopyrano(2,3-d)pyrimidine-5,1'(3'H)-isobenzofuran];

[0059] (j) Pyridines: 2,6-diphenyl-4-(6-dimethylaminophenyl)pyridine and 2,6-diethoxy-4-(4-diethylaminophenyl)pyridine;

[0060] (k) Quinazoline class: 2-(4-N-methylphenylaminophenyl)-1-phenoxyquinazoline and 2-(4-dimethylaminophenyl)-4-(1-methoxyphenoxy)quinazoline;

[0061] (l) Biquinazoline class: 4,4'-(ethylenedioxy)-bis[2-(1-diethylaminophenyl)quinazoline] and 4,4'-(ethylenedioxy)-bis[2-(1-di-n-butylaminophenyl)quinazoline];

[0062] (m) Ethylenophthalides: 3,3-bis[1,1-bis-(p-dimethylaminophenyl)ethylidene-3]phthalide;

[0063] (n) Ethylene azirphthalides: 3,3-bis[1,1-bis-(p-dimethylaminophenyl)ethylene-2]-4-azirphthalide and 3,3-bis[1,1-bis-(p-dimethylaminophenyl)ethylene-2]-4,7-diazaphthalide;

[0064] (o) Aminophthalides: 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (crystal violet lactone).

[0065] Furthermore, at least one of aminophthalides and fluoranes can be used as a coloring agent. As fluoranes, 2'-[bis(phenylmethyl)amino]-6'-(diethylamino)-spiro-[isobenzofuran-1(3H),9'-(9H)xanthon]-3-one, 2'-[(2-chlorophenyl)amino]-6'-(dibutylamino)-spiro-[isobenzofuran-1(3H),9'-(9H)xanthon]-3-one, and 3,6-diphenylaminofluorane are particularly preferred. As an aminophthalide, crystal violet lactone is especially preferred.

[0066] When the wet indicator composition of the present invention contains a leuco dye as a coloring agent, the leuco dye is readily ring-opened by protons generated in the presence of surfactants and urine (moisture), and the wet indicator composition is rapidly colored, which is preferred. The content of the leuco dye can be appropriately determined according to the type of leuco dye and the desired hue.

[0067] pH indicators are chemicals added to a reaction liquid to indicate the equivalence point through directly visible changes (such as color changes or precipitation formation during titration). Acid-base indicators are used as pH indicators. Specific examples of pH indicators include phenolphthalein, methyl orange, potassium chromate, bromocresol green, and bromophenol blue.

[0068] Based on the total amount of 100 parts by weight of hydrocarbon oil, saturated fatty acid, and moisture-sensitive colorant composition (i.e., components (A) to (C)), the colorant is included in the wet indicator composition in an amount of 0.05 to 5 parts by weight, preferably 0.1 to 3 parts by weight, and more preferably 0.5 to 2 parts by weight. By adjusting the content of the colorant in the wet indicator composition within the above range, the color difference between the dry and wet states of the wet indicator composition increases, and the color change can be easily perceived.

[0069] Colorants are used in combination with surfactants to form moisture-sensitive colorant compositions. Surfactants improve the compatibility of colorants with other components, and colorants are easily contained in oily gels.

[0070] Surfactants are substances that exhibit the function of changing the color of a colorant in the presence of water. For example, anionic and nonionic surfactants are preferred because they are easily wetted by water to generate protons, and many colorants change color by accepting protons.

[0071] Examples of anionic surfactants include:

[0072] Alkali metal alkyl sulfates, such as sodium dodecyl sulfate and potassium dodecyl sulfate;

[0073] Sodium dodecyl polyethylene glycol ether sulfate;

[0074] Alkyl ammonium sulfate, such as dodecyl ammonium sulfate;

[0075] Sodium sulfosinoate;

[0076] Alkyl sulfonates, such as alkali metal salts and ammonium salts of sulfonated paraffins;

[0077] Fatty acid salts, such as sodium lauryl oleate, triethanolamine oleate, and triethanolamine rosinate;

[0078] Alkyl aryl sulfonates, such as sodium dodecylbenzene sulfonate and alkali metal sulfates of basic phenol hydroxyethylene;

[0079] High alkyl naphthalene sulfonates;

[0080] Naphthalenesulfonic acid formalin condensate;

[0081] Dialkyl sulfosuccinate;

[0082] Polyoxyethylene alkyl sulfates; and

[0083] Polyoxyethylene alkyl aryl sulfate.

[0084] Examples of nonionic surfactants include:

[0085] Polyoxyethylene alkyl ethers;

[0086] Polyoxyethylene alkyl aryl ethers;

[0087] Dehydrated sorbitol fatty acid esters;

[0088] Polyoxyethylene dehydrated sorbitol fatty acid ester;

[0089] Fatty acid monoglycerides, such as glycerol monolaurate;

[0090] Polyoxyethylene oxypropylene copolymer; and

[0091] Condensation products of ethylene oxide with aliphatic amines, amides, or acids.

[0092] The surfactant is preferably anionic, more preferably a linear alkylbenzene sulfonate, and even more preferably sodium dodecylbenzene sulfonate. When sodium dodecylbenzene sulfonate is used as the surfactant, the colorant readily dissolves in the hydrocarbon oil, and the hydrocarbon oil readily comes into contact with water, thereby readily generating protons. Because it readily donates protons to the colorant, the color change of the wet indicator composition occurs rapidly.

[0093] Based on the total amount of 100 parts by weight of hydrocarbon oil, saturated fatty acid, and moisture-sensitive colorant composition (i.e., components (A) to (C)), a surfactant is included in the composition for wet indicators in an amount of 1 to 40 parts by weight, preferably 3 to 30 parts by weight, and more preferably 4 to 22 parts by weight. By adjusting the surfactant content in the composition for wet indicators within the above range, the sensitivity of the composition for wet indicators to moisture is improved, and the wet state is accurately indicated.

[0094] Pigments

[0095] In the wet indicator composition of the present invention, pigments may be used as needed. Pigments include inorganic pigments and organic pigments. Inorganic pigments include colored inorganic pigments and extender pigments.

[0096] Examples of colored inorganic pigments include white titanium dioxide, lead white (basic lead carbonate), zinc white (zinc oxide), and zinc barium white (barium sulfate / zinc sulfide);

[0097] Red iron oxide (III), red lead oxide, silver vermilion (mercury sulfide), molybdenum red;

[0098] Pale yellow chrome yellow (lead chromate), cadmium yellow (cadmium sulfide), zinc chromate, lead yellow (lead monoxide);

[0099] Bluish ultramarine blue, Prussian blue, cobalt blue (cobalt aluminate); and

[0100] Black pigments include iron oxide black (iron(II,III)) and carbon black.

[0101] Examples of extender pigments include barite (barium sulfate), gypsum (hydrated calcium sulfate), kaolin (diatomaceous earth), silica (silicon dioxide), precipitated silica, talc, barium carbonate, and calcium carbonate.

[0102] Examples of organic pigments include lakes and colored organic pigments. There are two types of lakes, one of which is dyed lakes, which are pigments obtained by staining extender pigments with dyes. The other type of lake is where the dye becomes insoluble through a reaction with a divalent or higher valence metal salt, and examples include azo lakes formed from azo dyes.

[0103] Examples of colored organic pigments include insoluble azo pigments, metallic phthalocyanine pigments, anthraquinone pigments, and vat pigments. In azo dyes, anthraquinone dyes, and indigo dyes, which are representative types of dyes based on chemical structure, water-insoluble substances are used as pigments. Furthermore, metallic phthalocyanine pigments have hues ranging from blue to green and exhibit excellent lightfastness.

[0104] <Tackifying Resins>

[0105] In the wet indicator composition of the present invention, a tackifier resin may be used as needed. Examples of tackifier resins include natural rosin, modified rosin, hydrogenated rosin, glycerol esters of natural rosin, glycerol esters of modified rosin, pentaerythritol esters of natural rosin, pentaerythritol esters of modified rosin, pentaerythritol esters of hydrogenated rosin, copolymers of natural terpenes, three-dimensional polymers of natural terpenes, hydrogenated derivatives of copolymers of hydrogenated terpenes, polyterpene resins, hydrogenated derivatives of phenol-based modified terpene resins, aliphatic petroleum hydrocarbon resins, hydrogenated derivatives of aliphatic petroleum hydrocarbon resins, aromatic petroleum hydrocarbon resins, hydrogenated derivatives of aromatic petroleum hydrocarbon resins, cyclic aliphatic petroleum hydrocarbon resins, and hydrogenated derivatives of cyclic aliphatic petroleum hydrocarbon resins.

[0106] Commercially available products can be used as tackifier resins. Examples of such commercially available products include KE-604 (trade name), ARKON P100 (trade name), and ARKON M100 (trade name) manufactured by Arakawa Chemical Industries, Ltd.; RHR-101HK 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.

[0107] Considering the compatibility between surfactants and hydrocarbon oils, RHR-101HK and Foral AX-E (which are rosin-based tackifier resins) are particularly preferred as tackifier resins.

[0108] <Other Components>

[0109] The composition for wet indicators of the present invention may contain at least one of the following additives as components other than those described above: thickeners (styrene-based polymers, olefin-based polymers), antioxidants (phenol-based, phosphorus-based, and sulfur-based), ultraviolet absorbers, fluorescent whitening agents, non-color-changing dyes, fragrances, disinfectants, antibacterial agents, repellents, skin care components, non-color-changing pigments, lubricants, and fillers.

[0110] <Production Method of Composition for Wet Indicators>

[0111] The composition for a wet indicator of the present invention is prepared by mixing the above-mentioned components while heating as needed. When the components are mixed until they become homogeneous and cooled to room temperature, the composition for a wet indicator gels and hardens.

[0112] For example, all components contained in the wet indicator composition are placed in a container, and the components are dissolved or uniformly dispersed, heated, and stirred until a homogeneous state is obtained. The heating temperature is typically adjusted appropriately within the range of 50 to 250°C, preferably 70 to 200°C, and more preferably 80 to 160°C. The heating time is determined taking into account the heating temperature, but is typically adjusted between 5 minutes and 1 hour, preferably between 10 minutes and 40 minutes.

[0113] A homogeneous composition can be prepared by sequentially placing each component into a container and mixing the components in sequence.

[0114] <Wetness Indicator>

[0115] The composition of the moisture indicator is molded into a suitable shape and optionally used as a moisture indicator in combination with components, substances, or materials that do not impair the function of the moisture indicator. The composition of the moisture indicator can be used as a single material, for example, by being applied to a substrate (such as a film or paper), or it can be used in combination with an absorbent substance. The moisture indicator of the present invention can be used in various articles in which moisture needs to be detected, but is particularly preferred for absorbent articles.

[0116] Examples of embodiments of a wet indicator when combined with a water-absorbing substance are as follows. That is,

[0117] Position the wet indicator and the absorbent material close to each other;

[0118] The composition of the wet indicator is mixed with an absorbent substance; and

[0119] The wet indicator is heated with the composition and the water-absorbing substance until they are compatible with each other.

[0120] The absorbent material can be a known absorbent resin (such as polyvinyl alcohol or acrylic resin) or a known absorbent material (such as wood, paper or cloth), and the absorbent material can be in any shape (such as sheet shape, block shape, granule shape or fiber shape).

[0121] <Absorbent products>

[0122] The absorbent articles of the present invention include absorbent materials and compositions for moisture indicators of the present invention. Specifically, absorbent articles are so-called sanitary materials (such as sanitary napkins, absorbent pads, postpartum shorts, breastfeeding pads, underarm sweat pads, diapers, pet sheets, hospital gowns, and white surgical gowns).

[0123] The absorbent article comprises at least one component selected from woven fabrics, nonwoven fabrics, rubber, resin, paper, and polyolefin films, and a wetness indicator according to the invention. For reasons such as durability and cost, the polyolefin film is preferably a polyethylene film.

[0124] When the wetness indicator of the present invention is used in disposable diapers, the wetness indicator preferably adheres to the surface of the powder or granules of absorbent resin stored in the disposable diaper. In addition to disposable diapers, the wetness indicator of the present invention can provide a moisture indicator effect on the surface of various substrates (such as resin granules, woven fabrics, nonwoven fabrics, resin sheets, paper, resin molded articles, metals, and wood) by applying the wetness indicator of the present invention to the surface of various substrates in any manner.

[0125] Example

[0126] In the following description, for the purpose of describing the invention in more detail and in a more specific manner, embodiments will be used, but these embodiments are not at all limiting of the invention.

[0127] In the examples and comparative examples, the components to be blended in the composition for wet indicator are as follows.

[0128] <hydrocarbon oil>

[0129] Paraffin oil (liquid paraffin manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0130] Paraffin oil (Daphne Oil KP-68 manufactured by Idemitsu Kosan Co., Ltd.)

[0131] Paraffin oil (Diana Fresia PW-32, manufactured by Idemitsu Kosan Co., Ltd.)

[0132] Naphthenic oil (KNH4010 (trade name) manufactured by PetroChina Company Limited)

[0133] Liquid polybutene (Nisseki Polybutene HV-100 manufactured by JXTG Nippon Oil & Energy Corporation (trade name))

[0134] The colorants constituting the moisture-sensitive colorant composition are as follows.

[0135] <Coloring agent>

[0136] pH indicator (bromocresol green, manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0137] Leuco dye (crystal violet lactone manufactured by FUJIFILM Wako Pure Chemical Corporation (trade name))

[0138] Leuco dye (Blue 1 (trade name) manufactured by Yamada Chemical Co., Ltd.)

[0139] Leuco dye (Blue 203 (trade name) manufactured by Yamada Chemical Co., Ltd.)

[0140] The surfactants constituting the moisture-sensitive colorant composition are as follows.

[0141] <surfactants>

[0142] Anionic surfactant (sodium dodecylbenzenesulfonate manufactured by KANTO CHEMICAL CO., INC. (reagent name))

[0143] Anionic surfactant (Aerosol QT-100 manufactured by SOLVAY (trade name))

[0144] Nonionic surfactant (SURFLIC-AQ250, manufactured by Itoh Oil Chemicals Co., Ltd.)

[0145] <Saturated fatty acids having 16 or more carbon atoms or derivatives of said saturated fatty acids>

[0146] A saturated fatty acid with 16 carbon atoms (16-hydroxyhexadecanoic acid (reagent name) manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0147] A saturated fatty acid derivative with 36 carbon atoms (magnesium stearate (reagent name) manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0148] A saturated fatty acid with 18 carbon atoms (12-hydroxystearic acid (reagent name) manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0149] A saturated fatty acid derivative with 18 carbon atoms (sodium stearate (reagent name) manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0150] <Tackifying Resins>

[0151] Tackifier resin based on hydrogenated rosin (RHR-101HK (trade name) manufactured by Wuzhou Sun Shine Forestry & Chemicals Co., Ltd.)

[0152] Tackifier resin based on hydrogenated rosin (Foral AX-E (trade name) manufactured by Eastman Chemical Japan Ltd.)

[0153] Hydrogenated hydrocarbon-based tackifier resin (HD-1100 (trade name) manufactured by Tiajin Luhua Chemical Co., Ltd.)

[0154] Hydrogenated hydrocarbon-based tackifier resin (ARKONP100 (trade name) manufactured by Arakawa Chemical Industries, Ltd.)

[0155] Hydrogenated hydrocarbon-based tackifier resin (ECR5400 (trade name) manufactured by Exxon Mobil Corporation)

[0156] Hydrogenated hydrocarbon-based tackifier resin (FTR-6100 (trade name) manufactured by Mitsui Chemicals, Inc.)

[0157] The above components were blended in the proportions shown in Tables 1 to 4, and stirred and mixed to prepare a composition for a wet indicator. Specifically, the components were placed in a 70 ml container and heated to 130°C using a glass column heater, and the blend was stirred for 20 minutes using a stirrer at a speed of 300 to 500 rpm. All values ​​(compositions) related to the composition for a wet indicator shown in Tables 1 to 4 are parts by weight (solid content).

[0158] For the wet indicator compositions of the examples and comparative examples, the appearance was checked for the formation of an oily gel, and phase separation, odor, discoloration time, and bleeding were evaluated. Evaluation details are shown below.

[0159] <Appearance>

[0160] The wet indicator compositions of the examples and comparative examples were 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 formed.

[0161] Whether a composition for a wet indicator is a gel is evaluated by assessing the composition’s flowability and the exudation of oily substances.

[0162] The composition was placed in a container that remained non-flowing even when the container was tilted, and commercially available blotting paper was pressed onto the composition. When oil seepage was visually identifiable, the composition was identified as a gel. Evaluation results are shown in Tables 1 through 4.

[0163] The hardness of the composition for wet indicators is evaluated according to the following criteria.

[0164] In an environment of 23°C, a cylindrical SUS probe was pressed onto the wet indicator composition of each example and comparative example to apply a load of 1 kg, and after 8 seconds, the extent to which the SUS probe penetrated into the composition was confirmed to evaluate the hardness of the composition. The evaluation criteria are as follows.

[0165] A 16mm diameter probe penetrates to a depth of 4mm or more: very soft.

[0166] The penetration depth of a 16mm diameter probe is less than 4mm: soft

[0167] The penetration depth of a 5mm diameter probe is less than 4mm: hard

[0168] A 3mm diameter probe penetrates less than 4mm: extremely hard.

[0169] Phase separation

[0170] Using 30g of each example and comparative example's wet indicator composition as evaluation samples, 30g of each sample was placed in a 70ml glass container and allowed to stand in a 100°C oven. After aging the samples for 24 hours, the presence or absence of phase separation was visually confirmed to evaluate whether the composition was homogeneous or heterogeneous.

[0171] A: No phase separation was observed, and no turbidity was observed.

[0172] B: No phase separation was observed, and the mixture was homogeneous, but slight turbidity was observed.

[0173] C: A slightly transparent upper layer of clear liquid was observed at the top.

[0174] D: Obvious phase separation was observed.

[0175] <Smell>

[0176] Using 30g of the wet indicator composition for each example and comparative example as evaluation samples, 30g of each sample was placed in a 70ml glass container, covered with aluminum foil, and then allowed to stand in a desiccator at 40°C for 1 hour. Afterward, the container was removed from the desiccator, the aluminum foil was removed, and the odor was confirmed. The evaluation criteria are as follows.

[0177] A: I didn't smell anything.

[0178] B: I detected a slight odor.

[0179] C: I could detect a noticeable odor, but it wasn't unpleasant.

[0180] D: I sensed a strong and unpleasant odor.

[0181] <Color Change Test>

[0182] The wet indicator compositions of each example and comparative example were placed in glass vials, and the vials were heated in a desiccator at 100°C until a homogeneous liquid was obtained. Subsequently, appropriate amounts of each composition were dropped onto opacity test paper (JIS K-5600 manufactured by TP Giken Co., Ltd.), and a uniform film with a thickness of approximately 27.5 μm was rapidly prepared using a doctor blade coater (No. 12 manufactured by Dai-ichi Rika Co., Ltd.), and the color of this coated film was recorded as the initial state (sample). It should be noted that for samples where no coloring was observed, the symbol "-" is shown in the table.

[0183] The samples were allowed to stand at room temperature for 30 minutes or longer, then placed on a stage and water was sprayed onto them. The final color, the degree of hue change (color difference), and the time until the color bleeds out and becomes the final color were then recorded and described in Tables 1 through 4.

[0184] Color difference (the degree of change in hue)

[0185] The evaluation criteria for color tone changes are as follows.

[0186] A: A very noticeable difference in tone was observed before and after spraying.

[0187] B: A noticeable difference in hue was observed before and after spraying.

[0188] C: Slight tonal differences were observed before and after spraying.

[0189] D: No color difference was observed before and after spraying.

[0190] <bleeding>

[0191] After the sample's color reaches its final color, the sample with applied water is tilted vertically off the table, and the amount of color bleeding associated with water dripping is recorded. When color bleeds due to water, the application pattern of the wetness indicator applied to the diaper is disrupted, and visibility deteriorates. Therefore, compositions with minimal color bleeding are preferred as wetness indicators. The evaluation criteria are as follows.

[0192] A: No bleeding was observed.

[0193] B: Slight bleeding was observed, but the shape of the applied area was preserved.

[0194] C: Bleeding was observed, but the shape of the applied area was preserved.

[0195] D: Bleeding was observed, and the shape of the applied area was damaged and not preserved.

[0196] <Until it turns its final color>

[0197] The time from spraying water until it reaches its final color was measured and described in Tables 1 through 4. It should be noted that for compositions for which no color difference was observed, the symbol "-" is shown in the tables.

[0198] [Table 1]

[0199]

[0200] [Table 2]

[0201]

[0202] [Table 3]

[0203]

[0204] [Table 4]

[0205]

[0206] As shown in Tables 1 to 3, in the wet indicator compositions of the examples, the components did not separate and no strong odor was generated. Furthermore, in the wet indicator compositions of the examples, the color change was significant, the time from the initial stage to the final color change was short, and the color was not blurred.

[0207] On the other hand, in the wet indicator compositions of Comparative Examples 1 to 5, there was no change between the initial hue and the hue after wetting with water, therefore they were unsuitable as indicators. In Comparative Examples 1 to 3, odor could not be suppressed.

[0208] Industrial applicability

[0209] The wetness indicator composition of the present invention provides a wetness indicator to be attached to absorbent articles (such as diapers or sanitary napkins).

Claims

1. A composition for a wet indicator, the composition comprising: a hydrocarbon oil (A); at least one selected from saturated fatty acids having 16 or more carbon atoms and derivatives of said saturated fatty acids (B); and a moisture-sensitive colorant composition (C), wherein, Based on a total amount of 100 parts by weight of components (A) to (C), component (A) is contained in an amount of 20 to 90 parts by weight, component (B) is contained in an amount of 2 to 85 parts by weight, wherein component (A) and component (B) form an oily gel having a fine, continuous porous structure, and wherein component (C) is a composition containing a colorant and an anionic surfactant.

2. The composition for a wet indicator according to claim 1, wherein the component (B) contains at least one selected from 12-hydroxystearic acid and a metal salt of 12-hydroxystearic acid.

3. The composition for a wet indicator according to claim 1 or 2, wherein the component (C) is a composition comprising: a leuco dye or a pH indicator; and an anionic surfactant.

4. The composition for a wet indicator according to claim 3, wherein the anionic surfactant comprises a linear alkylbenzene sulfonate.

5. A wet indicator, said wet indicator having a composition for a wet indicator according to any one of claims 1 to 4.

6. An absorbent article having the wetness indicator according to claim 5.

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