JP2007154063A - Moisture indicator and method for indicating amount of moisture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a moisture indicator obtained by utilizing a stimulation-responsive polymer gel, which is high in reliability and visibility, and by which the followings can be checked: dipping time, exposure time and conditions of water (pH, temperature, salt-concentration, etc.). <P>SOLUTION: The moisture indicator is exemplified by arranging in parallel a region 11A comprising a polymer gel 11 having 20 μm volume average particle diameter at swelling, a region 12A comprising a polymer gel 12 having 60 μm volume average particle diameter at swelling and a region 13A comprising a polymer gel 13 having 100 μm volume average particle diameter at swelling, onto a substrate 10 from the right to left in the figure. Where the regions 11A-13A are covered like being surrounded with a water-permeable base material 14. The indicator is, as exemplified, arranged with a plurality of stimulation-responsible polymer gels having different particle diameters so that they must be differed physical properties each other. The indicator may also be arranged with, for example, a plurality of stimulation-responsive polymer gels having different types of stimulation responsibility so as to have different physical properties each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a moisture indicator and a moisture content display method using a stimulus-responsive polymer gel that changes in volume by application of an external stimulus. These moisture indicators and moisture content display methods include, for example, determination of urine of disposable diapers, determination of when to eat such as cup noodles, determination of thawing history of frozen foods, determination of dried state of absorbent material and drying history, etc. It can be used for quantity display.

  Conventionally, various humidity indicators that change color according to ambient humidity have been provided. A well-known type of humidity indicator is one in which cobalt chloride, calcium chloride or the like is added to a paint, and a sensor material that changes color according to the humidity is applied or impregnated on fabric or paper ( For example, see Japanese Utility Model Publication No. 64-28934).

For the purpose of providing a moisture indicator having excellent storage stability, which develops color by adhering to water or water, and does not exhibit environmental preservation resistance, i.e., coloration due to atmospheric humidity, An ink composition for a reversible moisture indicator comprising a composition comprising an electron-accepting colored organic compound, an organic base, a water-absorbing powder, and a polymer binder, which is colored by the involvement of water, dissolved or dispersed in a non-aqueous solvent. And a moisture indicator recording medium obtained by coating the ink composition on a support (see, for example, JP-A-6-3345: reversible moisture indicator ink composition and recording medium using the same), the above-decolorizable moisture indicator ink for the organic acid is a sulfonic acid derivative or an aromatic sulfonic acid amide represented by the general formula R-SO ₂ -NR ₁ R ₂ Narubutsu (e.g., JP-A-8-92511 See for moisture indicator ink composition and a recording medium using the same) is proposed.

  In addition, for the purpose of providing an ink composition for a moisture indicator in which an ink film is dissolved by moisture and the pattern is lost, polyvinyl pyrrolidone contains 1 to 80% by weight of an alkyl group having 2 to 22 carbon atoms based on the entire resin. An olefin oxide, a glycidyl ether having an alkyl group having 2 to 22 carbon atoms on one side of the OH group at the end of the hydrophilic group of hydroxyethyl cellulose and / or hydroxypropyl cellulose; Moisture indicator ink composition (for example, specially characterized by comprising a resin obtained by graft polymerization of at least one selected from the group consisting of glycidyl ester or glycidic acid ester and a pigment as a colorant) See Kai 2003-183546: For moisture indicator Dissolve in one or more water for the purpose of improving visibility by changing the color under the detection of moisture, and also preventing the deterioration of designability while leaving the shape of the pattern after moisture detection. A composition comprising a resin having different properties and two or more colorants having different solubility or dispersibility in water, wherein a part of the composition is eluted together with the color former with water, and also contains another color former. As a pigment used in a moisture indicator ink composition (for example, JP-A-2004-285191: indicator ink composition that changes color due to moisture) having a mechanism in which the ink film changes color due to the residue of the product, Moisture indicator ink composition for highly moisture permeable film, characterized by using a pigment having an average particle size of 0.2 to 10 μm (for example, JP, 2005-15664, A: Moisture indicator ink composition for highly moisture permeable films) has been proposed.

Japanese Utility Model Publication No. 64-28934 JP-A-6-3345 JP-A-8-92511 JP 2003-183546 A JP 2004-285191 A JP 2005-15664 A

  However, the proposed moisture indicator ink 1) cannot retain moisture itself, 2) the ink diffuses and elutes, 3) the color change is not clear due to low contrast, and 4) the immersion or exposure time is confirmed. 4) There are various problems, such as the inability to confirm the state of water (pH, temperature, salt concentration, etc.) and other multipurpose confirmations.

  For this reason, there has been a demand for a moisture indicator that has high reliability and visibility and can check the immersion time, exposure time, and water state (pH, temperature, salt concentration, etc.).

  Therefore, the present invention is a moisture indicator using a stimulus-responsive polymer gel, which has high reliability and visibility, and confirms immersion time, exposure time, water condition (pH, temperature, salt concentration, etc.), etc. An object is to provide a possible moisture indicator. In addition, the present invention is a moisture content display method using a stimulus-responsive polymer gel, which has high reliability and visibility, soaking time, exposure time, water state (pH, temperature, salt concentration, etc.) It is another object of the present invention to provide a moisture content display method that can confirm the above.

The above problem is solved by the following means. That is,
The moisture indicator of the present invention is characterized in that a plurality of stimulus-responsive polymer gels having different physical property values are arranged.

  In the moisture indicator of the present invention, the plurality of stimulus-responsive polymer gels may have different particle sizes or different stimulus-responsive species. The plurality of stimulus-responsive polymer gels preferably include at least one selected from pH-responsive polymer gels and heat-responsive polymer gels.

  In the moisture indicator of the present invention, the plurality of stimulus-responsive polymer gels may be disposed on a support. In this case, it is preferable that the support has a chromatic color.

  In the moisture indicator of the present invention, the plurality of stimulus-responsive polymer gels may be arranged in a predetermined region for each stimulus-responsive polymer gel having the same physical property value. In this case, the arrangement may be a stacked arrangement or a parallel arrangement.

  The plurality of stimulus-responsive polymer gels may each contain a color material, and the color of the color material may be different for each stimulus-responsive polymer gel disposed in the predetermined region. Furthermore, the stimulus-responsive species may be different for each stimulus-responsive polymer gel arranged in the predetermined region.

  On the other hand, in the moisture content display method of the present invention, a plurality of stimulus-responsive polymer gels having different physical property values are arranged in a contracted state, the moisture is held in the plurality of stimulus-responsive polymer gels, and the volume is changed. The plurality of stimuli-responsive polymer gels are displayed by optical change corresponding to the difference in water content held by different physical property values.

  In the moisture content display method of the present invention, the plurality of stimulus-responsive polymer gels may have different particle sizes or different stimulus-responsive species. The plurality of stimulus-responsive polymer gels preferably include at least one selected from pH-responsive polymer gels and heat-responsive polymer gels.

  According to the present invention, it is a moisture indicator using a stimulus-responsive polymer gel, which has high reliability and visibility, and confirms immersion time, exposure time, water condition (pH, temperature, salt concentration, etc.), etc. A possible moisture indicator can be provided. In addition, according to the present invention, it is a moisture content display method using a stimulus-responsive polymer gel, which has high reliability and visibility, soaking time, exposure time, water state (pH, temperature, salt concentration). Etc.) can also be provided.

  Hereinafter, the present invention will be described in detail.

  The moisture indicator of the present invention is characterized in that a plurality of stimulus-responsive polymer gels having different physical property values (hereinafter sometimes simply referred to as “polymer gels”) are arranged.

  The moisture indicator of the present invention utilizes the fact that the polymer gel as the moisture indicator ink is swollen from contact with moisture or water vapor from the dry state and dried and shrinks from the swollen state, and has reliability and visibility. Becomes a high moisture indicator. This is because the polymer gel itself retains moisture and does not diffuse and elute, and is highly reliable, and since the polymer gel can retain the color material therein, the color material does not diffuse and elute, Since the display is based on a change in volume, a display with high contrast is possible, and thus visibility is excellent.

  Here, the physical property values are different from each other, for example, having different particle diameters, containing different colorants having different stimulus responsiveness, unilateral or reversible volume change. It shows that. A plurality of polymer gels having different physical property values means that, for example, the physical property values of a group of polymer gel particles are different for each group.

  For example, polymer gels with different particle sizes have different absorption speeds (time until the polymer gel in a dry state comes into contact with water to reach equilibrium swelling) and have multiple stimulus responsiveness with different particle sizes. By disposing the polymer gel, the amount of water retained (volume change magnitude) differs for each polymer gel having a predetermined particle diameter, so that the amount of water can be displayed according to the amount retained. In other words, since the time required to reach equilibrium swelling of the polymer gel differs depending on the particle size, adjusting the particle size and arranging them regularly on the substrate, for example, the immersion time in water and the high humidity exposure time are as follows. It can be confirmed by volume change (for example, color change). Here, the equilibrium swelling indicates a state in which the amount of liquid absorption has reached equilibrium and an increase in volume change is no longer confirmed.

  The polymer gels having different particle diameters mean that the particle size distribution of the group of polymer gel particles has one peak, and the peak value of the particle size distribution is different for each group. As a result, a difference in water retention amount for each group of polymer gel particles can be clearly obtained, and a moisture indicator having higher contrast and excellent visibility can be obtained. In addition, that a particle diameter differs shows that the particle diameter at the time of expansion | swelling order of a polymer gel differs.

In the present invention, the particle diameter means a volume average particle diameter. The volume average particle size and the particle size distribution can be easily measured by a dynamic light scattering particle size distribution analyzer (LA-300 (manufactured by Horiba)) or the like. In the present invention, polymer gels having different particle diameters are polymer gel particle groups having one peak value of particle size distribution, and the particle size distribution obtained by the following formula: GSD Index is 1.6. It means the following, more preferably 1.45 or less.
Formula: GSD Index = (D84v / D16v) ^1/2

  The particle size distribution measured by a dynamic light scattering method particle size distribution analyzer (LA-300 (manufactured by Horiba)) etc. is smaller than the divided particle size range (channel). Then, a cumulative distribution is drawn, and the particle diameter that is 16% cumulative in volume is defined as volume average particle diameter D16v, and the cumulative number particle diameter that is cumulative 16% in number is defined as D16p. Similarly, a particle diameter that is 50% cumulative in volume is defined as a volume average particle diameter D50v, and a particle diameter that is cumulative 50% in number is defined as a number average particle diameter D50p. Similarly, a particle diameter that is 84% cumulative is defined as a volume average particle diameter D84v, and a cumulative number particle diameter that is 84% cumulative is defined as D84p. The volume average particle size is D50v.

  In addition, for example, by using polymer gels having different stimulus responsiveness, the moisture or water vapor of the polymer gel itself can be swollen by contact with moisture or water vapor from the dry state and dried and contracted from the swollen state. In addition to displaying the amount of water due to swelling due to contact with the water, and swelling / shrinking due to a stimulus response, for example, a plurality of water states such as pH, temperature, and salt concentration can be confirmed. In other words, the amount of change in the volume of the polymer gel varies depending on the pH, temperature, salt concentration, contained substance, etc. of the water. Can be confirmed by volume change (eg color change)

  Thus, in the moisture indicator of the present invention, for example, a plurality of stimulus-responsive polymer gels having different physical property values are arranged in a contracted state, and the plurality of stimulus-responsive polymer gels retain moisture and change in volume. It is possible to display the optical change according to the difference in the amount of water held by the different physical property values of the plurality of stimulus-responsive polymer gels. This is the water content display method of the present invention.

  In the moisture indicator of the present invention, polymer gels having different physical property values are arranged in a predetermined region for each polymer gel having the same physical property value. Thereby, it becomes a moisture indicator with high visibility.

  The polymer gel is generally arranged on a support. However, in the present invention, polymer gels having different physical property values are arranged in a predetermined region for each polymer gel having the same physical property value. It is good. The arrangement in the predetermined region can be appropriately performed according to the purpose, whether it is a stacked arrangement or a parallel arrangement. In any case, at least, the polymer gel needs to be embedded and fixed inside the fibrous base material or covered with a water-permeable base material so that the polymer gel comes into contact with moisture or water vapor outside the moisture indicator.

  In the case of a laminated arrangement, it is preferable to laminate each predetermined region while separating polymer gels having different physical property values from each other with a water-permeable substrate. Thereby, water | moisture content or water vapor | steam reaches | attains the thickness direction (stacking direction) of a moisture indicator, and it can function as a moisture indicator. In this case, the thickness direction

  On the other hand, in the case of parallel arrangement, for example, polymer gels having different physical property values may be arranged in a predetermined region, and the predetermined region may be arranged in parallel. By arranging the predetermined area in a drawing shape such as a memory shape, a concentric circle shape, or a character shape, the visibility of the moisture indicator is dramatically improved.

  Here, as the support, synthetic resin sheets such as polyethylene, polypropylene, polyester, nylon, polystyrene, and ethylene-vinyl acetate copolymer, synthetic resin porous sheets, synthetic resin films, synthetic resin porous films, the sheets, and the like Examples thereof include a sheet and film obtained by laminating a metal on a film, a sheet-like metal thin plate, and glass. When the support has a chromatic color, when the polymer gel is in a dry state, that is, in a contracted state, the chromatic color of the support is displayed, and the dry state can be easily confirmed. Improves.

  In addition, as the fibrous base material, nylon fiber, acrylic fiber, polyester fiber, polypropylene fiber, polyvinyl chloride fiber, polyamide fiber, polyurethane fiber, wood pulp, cotton, wool, viscose rayon, Examples include acetate, cupra, carbon fiber, titanium fiber, and glass fiber.

  Examples of the water permeable substrate include polyester resin, polyvinyl pyrrolidone resin, polyurethane resin, polystyrene resin, acrylic resin, vinyl chloride resin, vinyl chloride copolymer resin, polyvinyl butyral resin, and maleic anhydride copolymer resin. Synthetic polymers; Cellulose derivatives such as methylcellulose, ethylcellulose, hydroxyethylcellulose, carboxymethylcellulose; polysaccharides such as starch; porous films such as natural polymers such as gelatin and sodium alginate; porous sheets and highly hydrophilic polyvinylpyrrolidone resins , Polyvinyl butyral resin, cellulose derivatives, natural polymers and the like films and sheets of 50 μm or less.

Hereinafter, the polymer gel as the moisture indicator ink will be described in detail.
First, the polymer gel will be described. As the polymer gel, in addition to the function of swelling and drying and shrinking from the swollen state by contact with moisture or water vapor from the dry state, for example, pH change, ion concentration change, adsorption / desorption of chemical substances, solvent composition change, Or, by applying an external stimulus such as heat, the liquid (water or water vapor) is absorbed and released to change the volume (swell or shrink). The state of water can be confirmed according to these stimulus responsiveness. In particular, the pH responsiveness (pH change) and the thermal responsiveness are preferable because they are frequently used as water. For this reason, it is preferable to apply at least one of a pH-responsive polymer gel and a thermo-responsive polymer gel as the polymer gel.

  The volume change of the polymer gel may be unilateral or reversible, but is preferably reversible. The specific example of a polymer gel is shown below.

  As the polymer gel that stimulates and responds to changes in pH, an electrolyte polymer gel is preferable, and examples thereof include a cross-linked product of poly (meth) acrylic acid and its salt, (meth) acrylic acid and (meth) acrylamide, and hydroxy. Cross-linked products and salts of copolymers with ethyl (meth) acrylate, (meth) acrylic acid alkyl ester, cross-linked products and salts of polymaleic acid, maleic acid and (meth) acrylamide, hydroxyethyl (meth) acrylate, Cross-linked products and salts of copolymers with (meth) acrylic acid alkyl esters, etc., cross-linked products of polyvinyl sulfonic acid, vinyl sulfonic acid and (meth) acrylamide, hydroxyethyl (meth) acrylate, (meth) acrylic acid alkyl ester Cross-linked product of copolymer with etc., cross-linked product of polyvinylbenzene sulfonic acid Salts of vinylbenzene sulfonic acid and copolymers of (meth) acrylamide, hydroxyethyl (meth) acrylate, alkyl (meth) acrylate, etc., and salts thereof, cross-linked polyacrylamide alkyl sulfonic acid and Cross-linked products of salts, copolymers of acrylamide alkyl sulfonic acid and (meth) acrylamide, hydroxyethyl (meth) acrylate, alkyl (meth) acrylic acid, etc., and cross-linked products of polydimethylaminopropyl (meth) acrylamide And its hydrochloride, cross-linked products of copolymers of dimethylaminopropyl (meth) acrylamide and (meth) acrylic acid, (meth) acrylamide, hydroxyethyl (meth) acrylate, (meth) acrylic acid alkyl ester, etc. 4 Grades, salts, polydimethyl A cross-linked product of a complex of ruaminopropyl (meth) acrylamide and polyvinyl alcohol, a quaternized product or a salt thereof, a cross-linked product of a composite of polyvinyl alcohol and poly (meth) acrylic acid or a salt thereof, a carboxyalkyl cellulose salt Examples thereof include a cross-linked product, a partial hydrolyzate of a cross-linked product of poly (meth) acrylonitrile, and a salt thereof.

  Among these, poly (meth) acrylic acid polymer materials are preferably used. The pH of water can be confirmed by a polymer gel that responds to a stimulus by this pH change.

  As the polymer gel that responds to a stimulus by changing the ion concentration, an ionic polymer material similar to the above-described stimulus-responsive polymer gel caused by a change in pH can be used. The state of water such as the addition of salt or the use of an ion exchange resin can be confirmed by the polymer gel that stimulates and responds to this change in ion concentration.

  As the polymer gel that stimulates and responds by adsorption and desorption of chemical substances, strong ionic polymer gels are preferable. Examples thereof include crosslinked products of polyvinyl sulfonic acid, vinyl sulfonic acid and (meth) acrylamide, and hydroxyethyl (meth) acrylate. , (Meth) acrylic acid alkyl ester cross-linked copolymer, polyvinyl benzene sulfonic acid cross-linked product and vinyl benzene sulfonic acid and (meth) acrylamide, hydroxyethyl (meth) acrylate, (meth) acrylic acid alkyl ester Cross-linked products of copolymers with, cross-linked products of poly (meth) acrylamide alkyl sulfonic acid, (meth) acrylamide alkyl sulfonic acid and (meth) acrylamide, hydroxyethyl (meth) acrylate, (meth) acrylic acid alkyl ester, etc. Copolymer with Such as cross-linked product, and the like.

  In particular, polyacrylamide alkyl sulfonic acid polymers are preferably used. By using the polymer gel that stimulates and responds by adsorption and desorption of this chemical substance, as a chemical substance, a surfactant, for example, alkylpyridine salt such as n-dodecylpyridinium chloride, alkylammonium salt, phenylammonium salt, tetraphenylphosphonium chloride It is possible to confirm the state of water whether or not a cationic surfactant such as a phosphonium salt is included.

  In general, most polymer gels that respond to stimuli by changing the solvent composition include most polymer gels, and swelling and shrinkage can be caused by using good and poor solvents in the polymer gel. . The state of the water whether or not other water is contained in the water can be confirmed by the polymer gel that responds to the stimulus by the change in the solvent composition.

  Polymer gels that respond to stimuli by applying heat include crosslinked polymers having LCST (lower critical eutectic temperature) and UCST (upper critical eutectic temperature), and two-component polymer gels that are hydrogen bonded to each other. An IPN (interpenetrating network structure) body or the like is preferable. A polymer crosslinked body having LCST contracts at a high temperature, and a polymer crosslinked body or IPN body having a UCST has a characteristic of swelling at a high temperature.

  Specific examples of polymer cross-linked compounds having LCST include cross-linked products of [N-alkyl-substituted (meth) acrylamide] such as poly-N-isopropylacrylamide and N-alkyl-substituted (meth) acrylamide and (meth). Cross-linked copolymer of two or more components such as acrylic acid and salts thereof, (meth) acrylamide, or (meth) acrylic acid alkyl ester, cross-linked product of polyvinyl methyl ether, alkyl such as methyl cellulose, ethyl cellulose, hydroxypropyl cellulose Examples include crosslinked products of substituted cellulose derivatives. Among these, poly N-isopropyl (meth) acrylamide is particularly preferable.

  Specific examples of the polymer cross-linked product having UCST include zwitterions having both anion and cation components in the molecule such as poly [3-dimethyl (methacryloyloxyethyl) ammoniumpropanesulfonate]. Examples thereof include crosslinked polymers.

  On the other hand, specific examples of the IPN body of the two-component polymer gel that hydrogen bonds with each other include an IPN body composed of a crosslinked poly (meth) acrylamide and a crosslinked poly (meth) acrylic acid, and a portion thereof. Japanese body (partially chlorinated acrylic acid unit), cross-linked copolymer of poly (meth) acrylamide as a main component, and IPN body composed of cross-linked poly (meth) acrylic acid and its partial neutralization Examples include the body. More preferably, a cross-linked product of poly [N-alkyl-substituted alkylamide, an IPN product of a cross-linked product of poly (meth) acrylamide and a cross-linked product of poly (meth) acrylic acid, a partially neutralized product thereof, and the like.

  The state of water can be confirmed by the polymer gel that responds to stimulation by the application of heat.

  The volume change amount of the polymer gel is not particularly limited, but it is preferably as high as possible, and the volume ratio during swelling and shrinking (when swelling / shrinking) is preferably 5 or more, particularly preferably 10 or more. In the present invention, the volume change of the polymer gel may be unilateral or reversible, but is preferably reversible.

  In addition, the form of the polymer gel is not particularly limited, but in consideration of the stimulus response characteristic, the form of particles is particularly preferable. When using a stimulus-responsive polymer gel that is in the form of particles, the shape of each polymer gel is not particularly limited, but spheres, ellipsoids, polyhedra, porous bodies, fibers, stars, needles, A hollow shape or the like can be used.

  The polymer gel is preferably particles having a volume average particle diameter of 0.5 μm or more, particularly 1 μm or more in a swollen state. When the volume average particle diameter is less than 0.5 μm, optical characteristics cannot be obtained, aggregation and the like are liable to occur, and handling thereof becomes difficult when used. On the other hand, the upper limit of the volume average particle diameter is not limited, but is selected according to the purpose of use, the shape of the indicator, and the design.

  When a fast response speed such as pH change or temperature change is required, the response speed may be slow when the volume average particle diameter exceeds 1 mm. For this reason, when a high response speed is required, the particle diameter is preferably controlled in the range of 1 μm to 500 μm.

  The polymer gel particles may be obtained by a method in which the polymer gel is made into particles by a physical pulverization method, etc., a method in which a polymer before cross-linking is made into particles by a chemical pulverization method and then cross-linked to obtain polymer gel particles, or It can be produced by a general particle formation method such as a particle polymerization method such as an emulsion polymerization method, a suspension polymerization method, or a dispersion polymerization method. Alternatively, polymer gel particles may be produced by extruding a polymer before cross-linking with a nozzle cap or the like to form a fiber, and then pulverizing the resulting polymer, or a method of pulverizing the fiber to form a particle and then cross-linking. Is possible.

  In order to improve the visibility of the moisture indicator, the polymer gel preferably contains a color material such as a pigment or a dye as a light adjusting material. In this case, it is preferable that the polymer gels having different physical property values, that is, the color of the coloring material be different for each stimulus-responsive polymer gel arranged in a predetermined region. Thereby, the color displayed for every predetermined area changes, and the visibility of a moisture indicator improves dramatically.

  Depending on the purpose of the moisture indicator, in addition to color materials, light scattering materials, materials that absorb or scatter light other than visible light, that is, infrared absorbing dyes, infrared absorbing or scattering pigments, ultraviolet absorbing dyes, ultraviolet absorbing or Light control materials such as scattering pigments can also be applied.

  As the addition amount of such a light-modulating material, it is preferable to add an amount that is equal to or higher than the saturated absorption concentration or the saturated scattering concentration when the polymer gel is dried or contracted. Here, “saturated absorption (or scattering) concentration or higher” means a region where the relationship between the light control material concentration and the light absorption amount under a specific optical path length deviates significantly from the linear relationship. By adding a light control material having such a concentration to the polymer gel, the optical density or scattering can be changed by swelling / shrinking of the polymer gel. The concentration of the light control material that is equal to or higher than the saturated absorption concentration or the saturated scattering concentration is generally 3% by mass or more, and it is preferable to add the range of 5% by mass to 95% by mass to the polymer gel, more preferably 5%. The range is from mass% to 80 mass%. If the amount is less than 3% by mass, the effect of adding the light adjusting material cannot be sufficiently obtained. If the amount exceeds 95% by mass, the properties of the polymer gel may be deteriorated.

  Examples of the color material as the light adjusting material include various dyes and pigments, and inorganic pigments, organic pigments, basic dyes, acid dyes, disperse dyes, reactive dyes, and the like are preferable. In particular, a pigment is preferable because its addition has a relatively small influence on the stimulus response of the polymer gel.

  Specific examples of suitable general dyes include black nigrosine dyes, azo dyes such as red, green, blue, cyan, magenta and yellow dyes, anthraquinone dyes, indigo dyes, and phthalocyanine dyes. Examples thereof include dyes, carbonium dyes, quinoneimine dyes, methine dyes, quinoline dyes, nitro dyes, benzoquinone dyes, naphthoquinone dyes, naphthalimide dyes, and verinone dyes, and those having a high light absorption coefficient are particularly desirable.

  Specific examples of common pigments include various carbon blacks (channel black, furnace black, etc.) that are black pigments, titanium black, metal oxides such as titanium oxide that are white pigments, and color pigments. Examples of color pigments include benzidine yellow pigments, rhodamine magenta pigments, phthalocyanine cyan pigments, or other anthraquinone, azo, azo metal complexes, phthalocyanine, quinacridone, perylene, indigo. And various color pigments such as isoindolinone, quinacridone, and allylamide.

  More specific examples of pigments include zinc oxide, basic lead carbonate, basic lead sulfate, lead sulfate, lithobon, muscovite, zinc sulfide, titanium oxide, anmotimone, lead white, zirconium oxide, alumina, micanite, White pigments such as inorganic oxides such as micalex, quartz, calcium carbonate, gypsum, clay, silica, silicic acid, silicon earth, talc, basic magnesium carbonate, alumina white, gloss white, satin white, zinc, alumel, Antimony, aluminum, aluminum alloy, iridium, indium, osmium, chromium, chromel, cobalt, zirconium, stainless steel, gold, silver, foreign silver, copper, bronze, tin, tungsten, tungsten steel, iron, lead, nickel, nickel alloy, Nickelin, platinum, platinum rhodium, tantalum, duralumin, nicro , Titanium, Krupp Austenitic Steel, Constantan, Brass, Platinum Iridium, Palladium, Palladium Alloy, Molybdenum, Molybdenum Steel, Manganese, Manganese Alloy, Rhodium, Rhodium Gold, etc., Phenolic Resin, Furan Resin, Xylene / Formaldehyde Resin , Urea resin, melamine resin, aniline resin, alkyd resin, unsaturated polyester, epoxy resin, polyethylene, polypropylene, polystyrene, poly-p-xylylene, polyvinyl acetate, acrylic resin, methacrylic resin, polyvinyl chloride, polyvinylidene chloride, Fluorine plastics, polyacrylonitrile, polyvinyl ether, polyvinyl ketone, polyether, polycarbonate, thermoplastic polyester, polyamide, diene plastic, polyurethane Tan-based plastic, polyphenylene, polyphenylene oxide, polysulfone, an aromatic heterocyclic polymer, silicone, natural rubber-based plastic, pigments and the like made of a polymeric material such as cellulose plastics.

  As more specific examples of yellow pigments that are color pigments, compounds typified by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds are used. More specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, 168, etc. are preferably used.

  More specific examples of magenta pigments include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. More specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48; 2, 48; 3, 48; 4, 57; 1, 81; 1, 144, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, 254 are particularly preferred.

  More specific examples of cyan pigments include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like. Specifically, as the pigment, for example, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15; 3, 15: 4, 60, 62, 66 and the like can be used particularly preferably.

  The particle diameter of the pigment to be used is preferably 0.001 μm to 1 μm, particularly preferably 0.01 μm to 0.5 μm, in terms of the volume average particle diameter of the primary particles. This is because if the particle size is less than 0.001 μm, the polymer gel tends to flow out, and if it exceeds 1 μm, the coloring property and light scattering property may be deteriorated.

  Specific examples of suitable inorganic materials for the light-scattering material include zinc oxide, basic lead carbonate, basic lead sulfate, lead sulfate, lithobon, muscovite, zinc sulfide, titanium oxide, ammothymon oxide, lead white, zirconium oxide, and alumina. , Micanite, micalex, quartz, calcium carbonate, gypsum, clay, silica, silicic acid, silicon earth, talc, basic magnesium carbonate, alumina white, gloss white, satin white and other inorganic oxides, zinc, alumel, Antimony, aluminum, aluminum alloy, iridium, indium, osmium, chromium, chromel, cobalt, zirconium, stainless steel, gold, silver, foreign silver, copper, bronze, tin, tungsten, tungsten steel, iron, lead, nickel, nickel alloy, Nickelin, platinum, platinum rhodium, tantalum, duralumin, nik Metal, such as molybdenum, titanium, Krupp austenitic steel, constantan, brass, platinum iridium, palladium, palladium alloy, molybdenum, molybdenum steel, manganese, manganese alloy, rhodium, rhodium gold, ITO (indium tin oxide), etc. Examples include inorganic conductive materials.

  Specific examples of suitable organic materials for light scattering materials include phenol resin, furan resin, xylene / formaldehyde resin, urea resin, melamine resin, aniline resin, alkyd resin, unsaturated polyester, epoxy resin, polyethylene, polypropylene, polystyrene , Poly-p-xylylene, polyvinyl acetate, acrylic resin, methacrylic resin, polyvinyl chloride, polyvinylidene chloride, fluoroplastic, polyacrylonitrile, polyvinyl ether, polyvinyl ketone, polyether, polycarbonate, thermoplastic polyester, polyamide, diene Plastic, polyurethane plastic, polyphenylene, polyphenylene oxide, polysulfone, aromatic heterocyclic polymer, silicone, natural rubber plastic, cellulose Polymeric materials such as plastic or the like and a mixed material of two kinds or more of polymeric materials (polymer blends) and the like.

  These light control materials include light control materials having addition-reactive groups and polymerizable groups for covalent bonding to polymer gels, and light control materials having groups that interact with polymer gels such as ionic bonds. It is also preferable to use various chemically modified light control materials such as materials.

  In addition, it is preferable that the upper light control material is present inside the polymer gel (or the liquid swelling body) and does not move to the outside of the polymer gel due to swelling / shrinkage. For this purpose, as described above, the dimming material is added by the method of covalently bonding the dimming material to the polymer gel, the method of ionic bonding, the method of physically holding it within the network of the polymer gel, etc. It is preferable to do. In particular, when a pigment is used as the light control material, the pigment can be stably held by appropriately selecting the cross-linking density of the polymer gel and forming a network smaller than the particle diameter of the pigment.

  The polymer gel containing such a light-modulating material is obtained by uniformly dispersing and mixing the light-modulating material in the polymer before cross-linking and then crosslinking the polymer precursor monomer composition during polymerization. It can be manufactured by a method of polymerizing by adding a light control material or a light control material having a polymerizable group. The light modulating material is preferably uniformly dispersed in the polymer gel, and in particular, when dispersed in the polymer gel, in the polymer gel production stage, using a mechanical kneading method, a stirring method, or It is desirable to uniformly disperse using a dispersing agent such as a surfactant or an amphiphilic polymer. The particles of the polymer gel containing the light control material can be produced by the same method as the above-described particle forming method.

  Hereinafter, an example of the moisture indicator of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing an example of a moisture indicator of the present invention, FIG. 1 (A) is a plan view, and FIG. 1 (B) is a sectional view taken along the line 1-1 in FIG. 1 (A). The moisture indicator shown in FIG. 1 includes a region 11A including a nonionic hydrophilic polymer gel 11 having a volume average particle diameter of 20 μm when swollen on a substrate 10 and a nonionic hydrophilic polymer having a volume average particle diameter of 60 μm when swollen. A region 12A including the gel 12 and a region 13A including the nonionic hydrophilic polymer gel 13 having a volume average particle diameter of 100 μm when swollen are arranged in parallel from right to left in the figure. And it covers so that the area | regions 11A-13A may be enclosed with the water-permeable base material 14. FIG.

  2 is a schematic configuration diagram showing another example of the moisture indicator of the present invention, FIG. 2 (A) is a plan view, and FIG. 2 (B) is a sectional view taken along the line 2-2 in FIG. 2 (A). is there. The moisture indicator shown in FIG. 2 includes a substrate 20, a region 21 A containing a thermoresponsive polymer gel 21 having a volume average particle diameter of 30 μm at the time of swelling on the substrate 20, and a pH response having a volume average particle diameter of 30 μm at the time of swelling. A region 22A including the conductive polymer gel 22 and a region 23A including the nonionic hydrophilic polymer gel 23 having a volume average particle diameter of 20 μm at the time of swelling are arranged in parallel. The area 21A is circular, the area 22A is arranged in a donut shape around the area 21A, and the area 23A is arranged in parallel in other areas. And it covers so that the area | regions 21A-23A may be enclosed with the water-permeable base material 24. FIG.

  FIG. 3 is a schematic cross section showing another example of the moisture indicator of the present invention. The moisture indicator shown in FIG. 3 includes a nonionic hydrophilic polymer gel 31 having a volume average particle diameter of 20 μm when swollen and a nonionic hydrophilic polymer gel having a volume average particle diameter of 100 μm when swollen. 32 is inserted and fixed. The polymer gels 31 and 32 are made to enter the fibrous base material 30 by suction or the like, respectively, and are divided into a region 31A including the polymer gel 31 and a region 32A including the polymer gel 32 and fixed. ing.

  FIG. 4 is a schematic cross section showing another example of the moisture indicator of the present invention. The moisture indicator shown in FIG. 4 includes a region containing a nonionic hydrophilic polymer gel 41 having a volume average particle diameter of 20 μm at the time of swelling on the first main surface of the substrate 40 through the transparent substrate 40 on which the colored film 40A is attached. A region 42A including a nonionic hydrophilic polymer gel 42 having a volume average particle diameter of 100 μm when swollen is laminated on the second main surface of 41A and the substrate 40. And it covers so that the area | region 41A-42A may be enclosed with the water-permeable base material 44. FIG.

  FIG. 5 is a schematic cross section showing another example of the moisture indicator of the present invention. The water indicator shown in FIG. 5 includes a region 51A including a nonionic hydrophilic polymer gel 51 having a volume average particle diameter of 20 μm when swollen on a transparent substrate 50, a nonionic hydrophilic high molecular weight having a volume average particle diameter of 100 μm when swollen. The regions 52A including the molecular gel 52 are sequentially stacked. And it covers so that the area | region 51A-52A may be enclosed with the water-permeable base material 54. FIG.

  FIG. 6 is a schematic cross section showing another example of the moisture indicator of the present invention. The moisture indicator shown in FIG. 6 includes a region 61A containing a nonionic hydrophilic polymer gel 61 having a volume average particle diameter of 20 μm when swollen on a transparent substrate 60, a nonionic hydrophilic high molecular weight having a volume average particle diameter of 100 μm when swollen. The regions 62A including the molecular gel 62 are sequentially stacked. Then, the region 61A and the region 62A are separated from each other by the water-permeable base material 64, and the water-permeable base material 14 covers the regions 61A to 62A.

  The moisture indicator of the present invention described above utilizes the fact that the polymer gel swells due to adhesion of moisture and water vapor, and shrinks by drying (desorption of moisture), so that the moisture retention amount of the polymer gel ( It is possible to display the amount of water corresponding to the volume change). Thereby, it can utilize for the display of moisture content, such as determination of the urine of a disposable diaper, the determination at the time of eating, such as cup noodles, determination of thawing history, such as frozen food, dryness of a liquid absorption substance, and determination of dry history.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the present invention.

(Production of nonionic hydrophilic polymer gel particles A-1)
Polymer gel particles containing a colorant were produced by the following process. 12 g of acrylamide, 48 mg of methylenebisacrylamide as a cross-linking agent, 5.75 g of distilled water, and 34.25 g of a 13.5 wt% aqueous dispersion of blue pigment (Dainippon Ink Co., Ltd., microencapsulated blue pigment) were mixed by stirring. . After removing oxygen by nitrogen substitution, a solution obtained by dissolving 0.04 g of ammonium persulfate as a polymerization initiator in 2 ml of water was added to prepare an aqueous solution. A solution obtained by dissolving 9 g of sorbitol-based surfactant (SO-15R: manufactured by Nikko Chemical Co., Ltd.) in 300 ml of cyclohexane was added to a reaction vessel purged with nitrogen, and the previously prepared aqueous solution was added thereto. The mixture was suspended by stirring at 1200 rpm for 30 minutes using a stirring blade.

  TEMDA was added to the suspension and polymerization was performed for 3 hours. After completion of the polymerization, purification was performed by washing with a large amount of ion-exchanged water in which 0.1 wt% of a surfactant was dissolved to obtain a polyacrylamide gel containing a coloring material that reached equilibrium swelling. The liquid absorption of the gel particles was about 25 g / g.

  Further, when the color tone change during swelling and contraction was confirmed, a large density change was confirmed. The coloring material (pigment) was not eluted or diffused even after repeated swelling and shrinkage.

(Production of nonionic hydrophilic polymer gel particles A-2)
The amount of the methylenebisacrylamide as the cross-linking agent was changed to 24 mg, the colorant was changed to carbon black pigment (manufactured by Taisei Kako Co., Ltd., TBK-BC3), and the polymerization initiator ammonium persulfate was changed to 0.4 g. Polyacrylamide gel particles were obtained in the same manner as A-1. The liquid absorption amount of the polymer gel particles was about 90 g / g.

(Production of pH-responsive polymer gel particles B)
Polymer gel particles containing a colorant were produced by the following process. 12 g of sodium acrylate, 50 mg of methylene bisacrylamide as a cross-linking agent, 5.75 g of distilled water, and 34.25 g of a 13.5 wt% aqueous dispersion of carbon black pigment (manufactured by Taisei Kako Co., Ltd., TBK-BC3) are stirred and mixed. After removing oxygen by nitrogen substitution, an aqueous solution was prepared by adding 0.4 g of ammonium persulfate as a polymerization initiator dissolved in 2 ml of water. A solution obtained by dissolving 9 g of a sorbitol-based surfactant (SO-15R: manufactured by Nikko Chemical Co., Ltd.) in 300 ml of cyclohexane is added to a nitrogen-substituted reaction vessel, and the previously prepared aqueous solution is added thereto, followed by rotary stirring. The mixture was suspended by stirring at 1200 rpm for 30 minutes using a blade.

  TEMDA was added to the suspension and polymerization was performed for 3 hours. After completion of the polymerization, purification was carried out by washing with a large amount of ion-exchanged water in which 0.1 wt% of a surfactant was dissolved to obtain a sodium polyacrylate gel containing a coloring material that reached equilibrium swelling. The liquid absorption amount of the polymer gel particles was about 150 g / g. The polymer gel particles were classified to obtain particles having a volume average particle size of 30 μm and a particle size distribution GSD Index = 1.35.

  Further, when the color tone change during swelling and contraction was confirmed, a large density change was confirmed. Further, this gel was able to confirm the change in color due to a change in the amount of liquid absorbed due to a change in pH. The coloring material (pigment) was not eluted or diffused even after repeated swelling and shrinkage.

(Production of thermoresponsive polymer gel particles C)
Polymer gel particles containing a colorant were produced by the following process. 10 g of N-isopropylacrylamide, 48 mg of methylenebisacrylamide as a cross-linking agent, 5.75 g of distilled water, 34.25 g of a 13.5 wt% aqueous dispersion of carbon black pigment (manufactured by Taisei Kako Co., Ltd., TBK-BC3) are mixed by stirring. After removing oxygen by nitrogen substitution, a solution obtained by dissolving 0.4 g of ammonium persulfate as a polymerization initiator in 2 ml of water was added to prepare an aqueous solution. A solution obtained by dissolving 9 g of a sorbitol-based surfactant (SO-15R: manufactured by Nikko Chemical Co., Ltd.) in 300 ml of cyclohexane is added to a nitrogen-substituted reaction vessel, and the previously prepared aqueous solution is added thereto, followed by rotary stirring. The mixture was suspended by stirring at 1200 rpm for 30 minutes using a blade. The liquid temperature of the suspension was maintained at 10 ° C.

  TEMDA was added to the suspension and polymerization was performed for 3 hours. After completion of the polymerization, purification was performed by washing with a large amount of ion-exchanged water in which 0.1 wt% of a surfactant was dissolved to obtain a poly N-isopropylacrylamide gel containing a coloring material that reached equilibrium swelling. The liquid absorption amount of the polymer gel particles was about 28 g / g. The polymer gel particles were classified to obtain particles having a volume average particle size of 30 μm and a particle size distribution GSD Index = 1.37.

  Further, when the color tone change during swelling and contraction was confirmed, a large density change was confirmed. Further, the polymer gel particles changed in the liquid absorption amount due to the temperature change, and the change was confirmed by the color change. The coloring material (pigment) was not eluted or diffused even after repeated swelling and shrinkage.

[Example 1]
The polymer gel particles A-1 (polyacrylamide gel particles) are classified, and the particles having a volume average particle diameter of 20 μm at the time of swelling and a particle size distribution GSDIndex = 1.3 are classified into polymer gel particles A-2 (polyacrylamide gel particles). ) To obtain particles having a volume average particle diameter of 60 μm at the time of swelling and a particle size distribution GSDIndex = 1.35. When this particle is dried and then transferred to distilled water to measure the time until equilibrium swelling is reached, the polymer gel particle A-1 has a volume average particle diameter of 20 μm when swollen within 30 seconds. It took about 3 to 4 minutes for particles having a volume average particle diameter of 60 μm during swelling of −2.

After the SiO ₂ vapor-deposited film was treated with γ-aminopropylmethoxysilane, the dispersion was adjusted so that swollen gel particles occupied 80% of the area of the fixed surface on this film, and each was settled and fixed on the film surface. In order to remove excess particles, they were rinsed with distilled water to obtain polymer gel particle fixed films. These two polymer gel particle fixed films are laminated so that the film surfaces (surfaces on which the polymer gel is not fixed) are opposed to each other, and dried to obtain a highly water-permeable substrate (polyvinylpyrrolidone resin porous material). The desired moisture indicator was obtained.

  When the moisture indicator was swollen, it exhibited a dark blue color seen from the polymer gel particle A-1 fixing surface and black when viewed from the polymer gel particle A-2 fixing surface. When this was dried, it had a pale grayish blue color.

  When this moisture indicator was immersed in ion-exchanged water and viewed from the fixed surface side of the polymer gel particle A-2, it changed to dark blue in about 1 minute, and then changed to black after 5 minutes.

[Example 2]
On a non-woven fabric made of acrylic fiber having a thickness of 0.2 mm and a basis weight of 50 g / m ² , which is a fibrous base material composed of fibers having a diameter of about 20 μm, using the dispersion according to swelling particle size used in Example 1 The polymer gel particles A-1 were uniformly applied while suction filtration, and then the polymer gel particles A-2 were uniformly applied while suction filtration. After application, the same fibrous base material was placed and dried to obtain a target moisture indicator in which the polymer gel particles were dispersed and fixed inside the fibrous base material.

  When this moisture indicator was immersed in ion-exchanged water and viewed from the fixed surface side of the polymer gel particle A-2, it changed to a dark blue color as in Example 1 and then changed to black.

[Example 3]
On a non-woven fabric made of acrylic fiber having a thickness of 0.2 mm and a basis weight of 50 g / m ² , which is a fibrous base material composed of fibers having a diameter of about 20 μm, using the dispersion according to swelling particle size used in Example 1 Then, it was uniformly applied while suction filtration, and then dried to obtain a fibrous base material in which polymer gel particles were dispersed and fixed on the fibrous base material. As described above, the target moisture indicator is bonded to the base sheet (polyethylene terephthalate) in parallel with two fibrous base materials in which 1 g of each dry particle is immobilized for each of the polymer gel particles A-1 and A-2. Obtained.

  When 60 ml of ion-exchanged water was brought into contact with this moisture indicator, the fixed part of the polymer gel particle A-1 was changed to dark blue, but the fixed part of the polymer gel particle A-2 was slightly changed to gray. Subsequently, when 60 ml of ion-exchanged water was further contacted, it was confirmed that the fixed portion of the polymer gel particle A-2 was changed to black and colored depending on the amount of water.

[Example 4]
After the silver film (aluminum laminate film) was treated with γ-aminopropylmethoxysilane, the area of the fixed surface was formed on this film using the polymer gel particle A-2 (polyacrylamide gel particle) dispersion used in Example 1. The dispersion was adjusted so that swollen gel particles accounted for 80% of the solution, and each was settled and fixed on the film surface. In order to remove excess particles, they were rinsed with distilled water to obtain polymer gel particle fixed films. This was dried and protected with a highly water-permeable substrate (polyvinylpyrrolidone resin porous film) to obtain a target moisture indicator. When the moisture indicator was swollen, it was black when viewed from the fixed surface. When this was dried, it was silver.

  When this moisture indicator was immersed in ion-exchanged water and viewed from the fixed surface side, it turned black after 5 minutes.

[Example 5]
Polymer gel particles A-1 (polyacrylamide gel particles) are classified, particles having a volume average particle diameter of 100 μm at the time of swelling and a particle size distribution GSDIndex = 1.37, particles having a volume average particle diameter of 60 μm at the time of swelling, and particle size distribution GSDIndex. = 1.3 particles, a volume average particle diameter during swelling of 20 μm, and a particle size distribution GSDIndex = 1.35 were obtained. When the particles were dried and then transferred to distilled water to measure the time required to reach equilibrium swelling, the particle size varied depending on the particle size. It took 9 to 10 minutes for the swollen particle size and 3 to 4 minutes for the 60 μm particle size. 20 μm swelled within 30 seconds.

After the SiO ₂ vapor-deposited film is treated with γ-aminopropylmethoxysilane, the dispersion is adjusted so that the swollen gel particles occupy 80% of the fixed surface area on the film, and the particles are settled according to the swollen particle diameter. The polymer gel of each particle diameter was fixed to the predetermined region. In order to remove excess particles, the film was rinsed with distilled water to obtain a polymer gel particle fixed film. Three polymer gel particles arranged in parallel in this predetermined region. The film in this state had a dark blue color. This was dried and protected with a highly water-permeable substrate (polyvinylpyrrolidone resin porous film) to obtain a target moisture indicator. In this state, it was light blue.

  When this moisture indicator is immersed in ion-exchanged water, the region (part) where the 20 μm polymer gel particles are fixed changes to dark blue within 30 seconds, and after 3-4 minutes, the 60 μm polymer gel particles are removed. After 9 to 10 minutes had passed since the fixed region (portion), the region (portion) to which the 100 μm polymer gel particles had been fixed changed to a dark blue color.

[Example 6]
On a non-woven fabric made of acrylic fiber having a thickness of 0.2 mm and a basis weight of 50 g / m ² , which is a fibrous base material composed of fibers having a diameter of about 20 μm, using the dispersion according to swollen particle size used in Example 5 A fibrous base material in which each polymer gel is uniformly applied to each predetermined region while being suction-filtered according to particle diameter, and then dried and polymer gel particles are dispersed and fixed in parallel inside the fibrous base material. Got. Three kinds of polymer gels were dispersed and fixed in a predetermined region, and a fibrous base material was bonded in parallel to a base sheet (polyethylene terephthalate) to obtain a target moisture indicator. This indicator had a light blue color when dry and a dark blue color when wet.

  When this moisture indicator is immersed in ion-exchanged water, the region (part) where the 20 μm polymer gel particles are fixed changes to dark blue within 30 seconds, and after 3-4 minutes, the 60 μm polymer gel particles are removed. After 9 to 10 minutes had passed since the fixed region (portion), the region (portion) to which the 100 μm polymer gel particles had been fixed changed to a dark blue color.

[Example 7]
Polymer gel particles A-2 (polyacrylamide gel particles), polymer gel particles B (polyacrylic acid sodium gel particles), and polymer gel particles C (poly N-isopropylacrylamide gel particles) are classified and swollen. Particles having a volume average particle size of 30 μm and a particle size distribution GSDIndex = 1.35 were obtained.

After the SiO ² vapor-deposited film is treated with γ-aminopropylmethoxysilane, the dispersion is adjusted so that the swollen gel particles occupy 80% of the area of the fixed surface on the film, and the particles are settled for each type to be on the film surface. Each type of polymer gel was fixed in a predetermined region. In order to remove excess particles, the film was rinsed with distilled water to obtain a polymer gel particle-fixed film in which three types of polymer gel particles were fixed in parallel for each predetermined region. The film in this state was black. This was dried and protected with a highly water-permeable substrate (polyvinylpyrrolidone resin porous film) to obtain a target moisture indicator. In this state, it was light gray.

  When this moisture indicator was immersed in room temperature ion-exchanged water, all parts turned black in about 1 minute. When the same indicator was immersed in water having a pH of 3 and a water temperature of 50 ° C., the portion where the polymer gel A-2 was immobilized changed to black, and the other portions had no color change. When the water temperature reached about 25 ° C., the portion where the polymer gel C was immobilized changed to black, but the portion where the polymer gel B was immobilized did not change. When the pH of this water was changed to pH 8, all parts showed black. When this solution was heated to a water temperature of 50 ° C., only the portion where the polymer gel C was immobilized was erased. In addition to moisture, this moisture indicator was able to detect moisture temperature, pH and other conditions.

[Example 8]
A fibrous base material composed of fibers having a diameter of about 20μm by using a dispersion solution used in Example 7, the thickness of 0.2 mm, a predetermined region on the acrylic fiber non-woven fabric of basis weight 50 g / m ^2, Each polymer gel was uniformly applied by suction filtration for each type, and then dried to obtain a fibrous base material in which the polymeric gel particles were dispersed and fixed in parallel inside the fibrous base material. Three kinds of polymer gels were dispersed and fixed in a predetermined region, and a fibrous base material was bonded in parallel to a base sheet (polyethylene terephthalate) to obtain a target moisture indicator. This indicator was light gray in the dry state and black in the wet state. The same evaluation as in Example 7 was performed and similar results were obtained.

[Example 9]
After the SiO ₂ vapor-deposited film is treated with γ-aminopropylmethoxysilane, polymer gel particles A-1 (polyacrylamide gel) in which the dispersion is adjusted so that swollen gel particles occupy 80% of the area of the fixed surface on this film Particles having a swollen particle diameter of 20 μm to 100 μm and a volume average particle diameter of 60 μm and a particle size distribution GSDIndex = 1.75 were settled and fixed on the film surface. In order to remove excess particles, the film was rinsed with distilled water to obtain a polymer gel particle fixed film. The film in this state was black. This was dried to obtain a target moisture indicator. In this state, it was light gray.

  When this moisture indicator was immersed in ion-exchanged water, the whole gradually turned black, but it was difficult to distinguish the passage of time as compared with Examples 1-6.

[Example 10]
After the SiO ₂ vapor-deposited film is treated with γ-aminopropylmethoxysilane, the volume average particle diameter at the time of swelling is 30 μm μm, and the particle size distribution GSDIndex = 1. Preparation of a mixed dispersion of polymer gel particles A (polyacrylamide gel particles), polymer gel particles B (sodium polyacrylate gel particles), and polymer gel particles C (poly N-isopropylacrylamide gel particles) classified into 35 Then, the polymer gel particles were settled and fixed on the film surface. In order to remove excess particles, rinsing with distilled water was performed to obtain a polymer gel particle-immobilized film in which three types of polymer gel particles were mixed and fixed. The film in this state was black. This was dried to obtain a target moisture indicator. In this state, it was light gray.

  This moisture indicator was evaluated in the same manner as in Example 5. However, although a color change occurred, it was difficult to identify the change compared to Examples 7 and 8.

  From the above, it can be seen that this example is a moisture indicator having high reliability and high visibility. It can also be seen that the immersion time, exposure time, water state (pH, temperature, salt concentration, etc.) can be confirmed. Furthermore, it can also be seen that the visibility as a moisture indicator is dramatically improved by arranging polymer gel particles in a predetermined region for each type, such as by particle diameter or by stimulus responsiveness (Examples 1 to 8).

It is a schematic block diagram which shows an example of the moisture indicator of this invention, FIG. 1 (A) is a top view, FIG.1 (B) is 1-1 sectional drawing of FIG. 1 (A). It is a schematic block diagram which shows another example of the moisture indicator of this invention, FIG. 2 (A) is a top view, FIG.2 (B) is 1-1 sectional drawing of FIG. 2 (A). It is a schematic sectional drawing which shows another example of the moisture indicator of this invention. It is a schematic sectional drawing which shows another example of the moisture indicator of this invention. It is a schematic sectional drawing which shows another example of the moisture indicator of this invention. It is a schematic sectional drawing which shows another example of the moisture indicator of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Substrate 11-13 Polymer gel 11A-13A Area | region 14 containing a polymer gel Water-permeable base material 20 Substrate 21-23 Polymer gel 21A-23A Area | region 24 containing a polymer gel Water-permeable base material 30 Fibrous base material 31 -32 Polymer Gel 31A-32A Region 40 Containing Polymer Gel Transparent Substrate 40A Colored Films 41-42 Polymer Gel 41A-42A Region Containing Polymer Gel 44 Water-permeable Substrate 50 Transparent Substrate 51-52 Polymer Gel 51A -52A Region 54 containing polymer gel Water-permeable substrate 60 Transparent substrates 61-62 Polymer gel 61A-62A Region containing polymer gel 64 Water-permeable substrate

Claims (15)

  A moisture indicator in which a plurality of stimulus-responsive polymer gels having different physical property values are arranged.   The moisture indicator according to claim 1, wherein the plurality of stimulus-responsive polymer gels have different particle sizes.   The moisture indicator according to claim 1, wherein the plurality of stimulus-responsive polymer gels have different stimulus-responsive species.   The moisture indicator according to claim 1, wherein the plurality of stimulus-responsive polymer gels include at least one selected from a pH-responsive polymer gel and a thermo-responsive polymer gel.   The moisture indicator according to claim 1, wherein the plurality of stimulus-responsive polymer gels are disposed on a support.   The moisture indicator according to claim 5, wherein the support has a chromatic color.   The moisture indicator according to claim 1, wherein the plurality of stimulus-responsive polymer gels are arranged in a predetermined region for each stimulus-responsive polymer gel having the same physical property value.   The moisture indicator according to claim 7, wherein the arrangement is a stacked arrangement.   The moisture indicator according to claim 7, wherein the arrangement is a parallel arrangement.   The moisture indicator according to claim 7, wherein each of the plurality of stimulus-responsive polymer gels contains a color material, and the color of the color material is different for each of the stimulus-responsive polymer gels arranged in the predetermined region.   The moisture indicator according to claim 7, wherein a stimulus-responsive species is different for each stimulus-responsive polymer gel arranged in the predetermined region.   A plurality of stimulus-responsive polymer gels having different physical property values are arranged in a contracted state, the moisture is retained in the plurality of stimulus-responsive polymer gels, the volume is changed, and the plurality of stimulus-responsive polymer gels are mutually connected. A method for displaying the amount of moisture that is displayed by optical change according to the difference in the amount of moisture to be held due to different physical property values.   The water content display method according to claim 12, wherein the plurality of stimulus-responsive polymer gels have different particle sizes.   The moisture content display method according to claim 12, wherein the plurality of stimulus-responsive polymer gels have different stimulus-responsive species.   The moisture content display method according to claim 12, wherein the plurality of stimulus-responsive polymer gels include at least one selected from a pH-responsive polymer gel and a thermo-responsive polymer gel.

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