JP6938357B2 - Water discoloration indicator - Google Patents

Description

The present invention relates to a water discoloration indicator. More specifically, the present invention relates to a discoloration indicator capable of visually recognizing an appearance different from that in a dry state due to the adhesion of a medium containing water.

Conventionally, a discolorable laminate in which a porous layer containing a low refractive index pigment is formed on the surface of a support, water is absorbed by the porous layer to make it transparent, and the color of the base is revealed has been disclosed. (See, for example, Patent Document 1).
Further, a discolorable adhesive label in which an adhesive layer is provided on the back surface of a transparent substrate and a porous layer containing a low refractive index pigment and a colored layer are provided on the surface of the transparent substrate is disclosed (for example, a patent). Reference 2).
Although the discolorable laminate and the discolorable adhesive label can be used as an indicator for detecting the adhesion of water, it can only confirm the state in which water is attached, and it returns to the original state by drying, so that water has been used in the past. It was not possible to determine if there was any adhesion.
Further, as another attempt, a water-wetting-sensing printed matter in which an ink containing a water-soluble dye is printed on a paper that does not easily repel water is disclosed (see, for example, Patent Document 3).
In the water-sensitive printed matter, the water-soluble dye elutes from the printed portion and exudes to the non-printed portion due to the adhesion of water, so that it is possible to determine whether or not water has adhered in the past, but the water-soluble dye At the moment, it did not have a function to determine whether or not water was attached.

Japanese Unexamined Patent Publication No. 11-1982271 JP-A-2007-322594 Japanese Unexamined Patent Publication No. 10-2893

The present invention is intended to provide a water discoloration indicator having a function of determining whether or not water has adhered in the past and at present whether or not water has adhered.

The present invention comprises a porous layer in which a low refractive index pigment is fixed to a binder resin in a dispersed state on a support, which is opaque in a non-liquid absorbing state and becomes transparent in a liquid absorbing state, and the porous layer. A part of the porous layer is provided with a water-soluble resin layer in a coexisting state, and the porous layer of the portion provided with the water-soluble resin layer in the non-liquid absorbing state is porous of the portion not provided with the water-soluble resin layer. It requires a water discoloration indicator characterized by being more translucent than the layer.
Further, the water-soluble resin layer contains a transparent resin, the water-soluble resin layer is a resin in a solid state at 25 ° C., and the support is a water-permeable support. The requirements are that a waterproof layer is provided on the upper layer, a non-discoloring colored layer is provided on the support, and an adhesive layer is provided on the lowermost layer.

INDUSTRIAL APPLICABILITY The present invention can provide a highly convenient water discoloration indicator having a function of determining whether or not water has adhered in the past and at present whether or not water has adhered.

It is a vertical sectional view of one Example of the water discoloration indicator of this invention. It is a vertical sectional view of another Example of the water discoloration indicator of this invention. It is a vertical sectional view of another Example of the water discoloration indicator of this invention. It is a vertical sectional view of another Example of the water discoloration indicator of this invention.

The present invention comprises a porous layer in which a low refractive index pigment is fixed to a binder resin in a dispersed state on a support, which is opaque in a non-liquid absorbing state and becomes transparent in a liquid absorbing state, and the porous layer. It is a water discoloration indicator that is inherent in a part and is provided with a water-soluble resin layer in a coexisting state.
The water discoloration indicator is water-soluble because the porous layer in the portion provided with the water-soluble resin layer in the non-liquid absorbing state has higher translucency than the porous layer in the portion not provided with the water-soluble resin layer. Since the lower layer is visually recognized from the portion where the resin layer is provided, various images can be visually recognized.

The support is not particularly limited, and for example, cloth such as paper, synthetic paper, woven fabric, knitted fabric, braid, non-woven fabric, natural or synthetic leather, plastic, glass, ceramics, metal, wood, stone and the like are used. Cloth, synthetic paper, and plastic are preferably used. Further, the shape may be a planar shape or a three-dimensional shape.
The support itself may be colored, or may be provided with a non-discoloring colored layer on the support.
Examples of the coloring agent for coloring the support or the coloring agent contained in the non-discoloring coloring layer include general dyes, fluorescent dyes, and coloring pigments, and among them, the coloring pigments include general pigments and fluorescent pigments. In addition to metal powder, a transparent metallic bright pigment (pearl pigment) in which a core material such as mica, alumina, or glass is coated with titanium oxide can be exemplified.
The water discoloration indicator is formed of a transparent support, for example, a transparent film, so that a low refractive index pigment is fixed to a binder resin in a dispersed state on the back surface of the support in a non-liquid absorbing state. It is also possible to provide a porous layer that is opaque and becomes transparent in a liquid absorbing state, and a water-soluble resin layer that is inherent in a part of the porous layer and coexists.

The porous layer is a layer in which a low refractive index pigment is fixed together with a binder resin in a dispersed state, and has different transparency in a dry state and a liquid absorbing state.
The refractive index of the low refractive index pigment is in the range of 1.4 to 1.8, and exhibits good transparency when it absorbs water.
Examples of the low refractive index pigment include silicic acid and salts thereof, barite powder, barium sulfate, barium carbonate, calcium carbonate, gypsum, clay, talc, alumina, alumina white, magnesium carbonate and the like, and silicic acid and salts thereof are preferable. Used.
Examples of the salt of silicate include aluminum silicate, potassium aluminum silicate, sodium aluminum silicate, aluminum calcium silicate, potassium silicate, calcium silicate, sodium calcium silicate, sodium silicate, magnesium silicate, potassium magnesium silicate and the like.
Further, two or more kinds of the low refractive index pigments can be used in combination.
The particle size of the low refractive index pigment is not particularly limited, but those having a particle size of 0.03 to 10.0 μm are preferably used.
Silicic acid is mentioned as a preferably used low refractive index pigment.
The silicic acid may be a silicic acid produced by a dry method, but a silicic acid produced by a wet method (hereinafter referred to as a wet method silicic acid) is particularly effective. Explaining this point, the silicic acid is amorphous. It is produced as a quality amorphous silicic acid, and depending on the production method, a dry method using a vapor phase reaction such as thermal decomposition of silicon halide such as silicon tetrachloride (hereinafter referred to as dry silicic acid) and sodium silicate are used. The dry method silicic acid and the wet method silicic acid have different structures, and the dry method silicic acid has a three-dimensional structure in which silicic acid is tightly bonded. On the other hand, the wet method silicic acid has a so-called two-dimensional structural portion in which silicic acid is condensed to form a long molecular arrangement.
Therefore, since the molecular structure is coarser than that of the dry silicic acid, when the wet silicic acid is applied to the porous layer, the diffuse reflection of light in the dry state is excellent as compared with the system using the dry silicic acid. Therefore, it is presumed that the concealment property under normal conditions will increase.
Further, since the porous layer absorbs water, the wet method silicic acid has more hydroxyl groups existing as silanol groups on the particle surface than the dry method silicic acid, and the degree of hydrophilicity is large. It is preferably used.
In addition, in order to adjust the hiding property of the porous layer in a normal state and the transparency in a liquid absorbing state, another general-purpose low refractive index pigment can be used in combination with the wet method silicic acid.

The low refractive index pigment in the porous layer depends on properties such as particle size, specific surface area, and oil absorption, but in order to satisfy both the hiding property in the normal state and the transparency in the liquid absorbing state, it is necessary to satisfy both. preferably the coating amount is 1 to 30 g / ^{m 2,} more preferably 5 to 20 g / ^{m 2.} If it is less than 1 g / m ² , it is difficult to obtain sufficient concealment under normal conditions, and if it ^{exceeds 30 g / m 2} , it is difficult to obtain sufficient transparency at the time of liquid absorption.
The low refractive index pigment is dispersed in a vehicle containing a binder resin as a binder, applied to a support, and then dried to form a porous layer.
Examples of the binder resin include urethane resin, nylon resin, vinyl acetate resin, acrylic acid ester resin, acrylic acid ester copolymer resin, acrylic polyol resin, vinyl chloride-vinyl acetate copolymer resin, maleic acid resin, polyester resin, and styrene. Resin, styrene copolymer resin, polyethylene resin, polycarbonate resin, epoxy resin, styrene-butadiene copolymer resin, acrylonitrile-butadiene copolymer resin, methyl methacrylate-butadiene copolymer resin, butadiene resin, chloroprene resin, melamine resin, and the above. Examples thereof include each resin emulsion, casein, starch, cellulose derivative, polyvinyl alcohol, urea resin, phenol resin and the like.
The mixing ratio of the low refractive index pigment and these binder resins depends on the type and properties of the low refractive index pigment, but preferably, the binder resin solid content is 0.5 to 1 part by mass of the low refractive index pigment. It is 2 parts by mass, more preferably 0.8 to 1.5 parts by mass. When the solid content of the binder resin is less than 0.5 parts by mass with respect to 1 part by mass of the low refractive index pigment, it is difficult to obtain a practical film strength of the porous image, and when it exceeds 2 parts by mass. In addition, the permeability of water into the porous layer is deteriorated.
Since the mixing ratio of the binder resin to the colorant is small in the porous layer as compared with a general coating film, it is difficult to obtain sufficient film strength. Therefore, it is effective to use a nylon resin or a urethane-based resin among the above-mentioned binder resins in order to increase the scratch resistance.
Examples of the urethane-based resin include polyester-based urethane resin, polycarbonate-based urethane resin, and polyether-based urethane resin, and two or more of them can be used in combination. Further, a colloid in which the resin is emulsified and dispersed in water or self-emulsified by the ionic group of the ionic urethane resin (urethane ionomer) itself without the need for an emulsifier and dissolved or dispersed in water. A dispersed type (ionomer type) urethane resin can also be used.
Either an aqueous urethane resin or an oil urethane resin can be used as the urethane resin, but in the present invention, an aqueous urethane resin, particularly a urethane emulsion resin or a colloidal dispersion type urethane resin is preferable. Used for.
The urethane-based resin can be used alone, but other binder resins can also be used in combination depending on the type of support and the performance required for the film. When a binder resin other than the urethane resin is used in combination, it is preferable that the urethane resin is contained in the binder resin of the porous layer in a solid content mass ratio of 30% or more in order to obtain a practical film strength.
Among the binder resins, those having a crosslinkable property can be further improved in film strength by adding an arbitrary cross-linking agent and cross-linking.
The binder resin has different affinities with water, and by combining these, the permeation time into the porous layer, the degree of permeation, and the slow speed of drying after permeation can be adjusted. Further, the adjustment can be controlled by appropriately adding a dispersant or a surfactant.

The porous layer can be coated by screen printing, offset printing, gravure printing, coater, tampo printing, transfer or other printing means, brush coating, spray coating, electrostatic coating, electrodeposition coating, sink coating, roller coating, dip coating, etc. It can be formed on a support.
The porous layer may be an image of a circle, an ellipse, a square, a rectangle, or the like, but in addition to various characters, symbols, figures, and patterns, people, animals, plants, fruits, foodstuffs, vehicles, and buildings. , An image of a celestial body or the like.

A water-soluble resin layer that is inherent in a part of the porous layer and is provided in a coexisting state will be described.
Examples of the water-soluble resin contained in the water-soluble resin layer include polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, polyethylene glycol, water-soluble acrylic resin, water-soluble nylon resin, sodium alginate, propylene glycol alginate, gum arabic, casein, and casein. Examples thereof include cell rolls and cellulose derivatives such as sodium, guar gum, gelatin, dextrin, starch, processed starch, reduced candy, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose, and carboxymethyl ethyl cellulose, and salts thereof.

In the water-soluble resin layer, the water-soluble resin elutes to the surroundings due to the adhesion of water. Due to the elution of the sex resin, the translucency becomes low, the effect of visually recognizing the lower layer from the portion where the water-soluble resin layer is provided decreases, and that state is maintained even if it becomes a non-liquid absorbing state again, so in the past It is possible to determine whether or not there is water adhesion.
In addition, the porous layer in the portion where the water-soluble resin layer is not provided conceals the lower layer in the non-liquid absorbing state, and is transparent in the liquid absorbing state to have a repeating function of visually recognizing the lower layer, so that water adheres to it. It is possible to distinguish between a state in which water is present and a state in which water is not attached.
The water-soluble resin layer is excellent in storage stability in the initial state by using a resin in a solid state at 25 ° C., preferably in a solid state at 30 ° C., and more preferably in a solid state at 35 ° C.
As the resin used for the water-soluble resin layer, it is preferable to use a transparent resin because it does not contaminate the surroundings or adhere to the resin to contaminate it.
By using the water-soluble resin, the elution property and diffusibility at the time of water adhesion are excellent, but by using the water-soluble resin and the water-insoluble resin together, the storage stability in the initial state at high humidity can be improved. Can be improved.
When the water-soluble resin and the water-insoluble resin are used in combination, it is preferable to use the water-soluble resin and the water-insoluble resin in a mass ratio of 95: 5 to 10:90, and more preferably 95: 10 to 20:80. Therefore, if the mass ratio of the water-soluble resin is low, it becomes difficult to visually recognize the state change before and after water adhesion, and the function as an indicator tends to deteriorate.

The water-soluble resin layer prepares a liquid composition and is formed by the same means as the porous layer.
As the solvent of the liquid composition, water, water and a water-soluble organic solvent, or a solvent can be used.
The solvents used are aromatic hydrocarbons of benzene, toluene and xylene, hexane, cyclohexane, saturated hydrocarbons of octane, acetone, methyl ethyl ketone, ketones of cyclohexanone, chloroform, halogenated hydrocarbons of trichloroethane, mineral spirit and petroleum ether. Petroleum-based solvent can be mentioned.
If necessary, the liquid composition may contain a thickener, a dispersant, a pH adjuster, a preservative, an antifungal agent, an antioxidant and the like.

Examples of the water-soluble resin layer include various characters, symbols, figures, patterns, and shapes such as people, animals, plants, fruits, foodstuffs, vehicles, buildings, and celestial bodies. The pattern may be an independent discontinuous pattern such as a polka dot pattern, or may be a partially connected continuous pattern such as a checkered pattern.
The area ratio between the portion where the water-soluble resin layer is formed and the portion where the water-soluble resin layer is not formed is not particularly limited, but is preferably 0.1: 99.9 to 30:70 per ^{cm 2.} When is 1:99 to 20:80, an image of a visible size is appropriately provided over the entire surface of the porous layer, and the texture of the water discoloration indicator in a dry state can be enhanced. , A clear change between the non-absorbent state and the liquid-absorbent state can be visually recognized.

The water discoloration indicator is formed of a water-permeable support, for example, a material such as a cloth or a film having a through hole, paper, or synthetic paper, so that it adheres not only from the water adhering from the front surface but also from the back surface. It can also detect water.
In a system using a water-permeable support, by providing a waterproof layer on the uppermost layer, an indicator for detecting water adhering from the back surface can be obtained.
The waterproof layer is a transparent layer, and is made of polyethylene, polystyrene, polypropylene, polyvinyl chloride, polyvinyl fluoride, cellophane film, silicone resin, polyamide resin, cellulose resin, acrylic resin, epoxy resin. , It is preferable that it consists of at least one selected from synthetic rubber varnishes.

The water discoloration indicator can be easily adhered to an object by providing an adhesive layer at the bottom layer.
The pressure-sensitive adhesive layer is formed of a general-purpose acrylic resin, urethane-based resin, styrene-butadiene copolymer, vinyl ether copolymer, a pressure-sensitive adhesive mainly composed of natural rubber, and the like.
Further, the adhesive layer may be provided with a release layer such as a release paper for convenience at the time of use.

The water discoloration indicator can be attached to an article, cut into a desired size and shape and attached to the article, or a water discoloration indicator can be wound on the surface of a core formed of paper or the like. It can also be put into practical use as a tape form.
By adopting the tape form, it is easy to carry and it is not necessary to provide a release layer, so that resource saving can be promoted, and it can be cut into an appropriate size according to the length of the object and attached. Satisfies applicability to articles of various shapes and sizes.

Examples of the object to which the water discoloration indicator is attached include, for example, water leakage detection of pipes, pipes, water tanks, etc., wetness detection by beverages such as juice, wetness detection of electronic devices, disposable diapers, and urine. Detection is possible.

Examples of the present invention will be described below. In addition, the part in an Example shows a mass part.
Example 1 (see FIG. 1)
Wet method fine particle silica [trade name: Nipseal E-220, manufactured by Nippon Silica Industry Co., Ltd.] 15 parts, urethane emulsion [trade name: Hydran AP-10, Dainippon Ink Chemicals] on the surface of blue polyethylene terephthalate film as support 2. Made by Kogyo Co., Ltd., solid content 30%] 45 parts, water 40 parts, silicone-based defoamer 0.5 parts, water-based ink thickener 3 parts, ethylene glycol 1 part, isocyanate-based cross-linking agent 3 parts mixed The entire surface was solid-printed on a 100-mesh screen plate using the above-mentioned screen printing ink, and dried and cured at 60 ° C. for 30 minutes to form the porous layer 3.
Next, using a screen printing ink containing 50.0 parts of polyvinylpyrrolidone resin [trade name: Socalan K-17, manufactured by BASF] and 50.0 parts of water on the porous layer, a 100-mesh screen plate is used. A dot pattern having a diameter of 2 mm was printed and dried and cured at 50 ° C. for 30 minutes to form a translucent water-soluble resin layer 4 contained in a part of the porous layer to obtain a water discoloration indicator 1.

When the back surface (support side) of the water discoloration indicator was attached to a pipe and put into practical use, in a normal state (non-water absorption state), a white color due to the porous layer and a transparent resin layer partially contained in the porous layer were used. The porous layer becomes transparent and a blue dot pattern is visible, but when water adheres from the surface, the polyvinylpyrrolidone resin of the water-soluble resin layer becomes eluted to the surroundings, and the porous layer absorbs liquid. It becomes transparent and the blue part of the water-adhered part is visually recognized in a solid state.
The indicator in the state where water is attached shows the above-mentioned aspect, but when the porous layer dries, it returns to the original white state, and the water-soluble resin layer in the part where water is attached is a porous layer of polyvinylpyrrolidone resin. Since the dot pattern disappears or becomes lighter due to elution and diffusion, only the white color of the porous layer becomes visible, and the appearance is different from that before the water adhered, so it is necessary to determine that water has adhered in the past. Was made.
When water adhered to the water discoloration indicator again, the porous layer became transparent due to the liquid absorption and the blue color was visually recognized, and the state in which the water adhered could be repeatedly visually recognized.
In addition, even if a large amount of water adhered to the indicator and water flowed out to the surroundings, the water-soluble resin was transparent and did not become dirty.

Example 2
As a support, on the surface of blue 100% cotton broad fabric, wet method fine particle silica [trade name: Nipseal E-220, manufactured by Nippon Silica Industry Co., Ltd.] 15 parts, urethane emulsion [trade name: Hydran AP-10, Dainippon Ink Chemical Industry Co., Ltd., solid content 30%] 45 parts, water 40 parts, silicone-based defoamer 0.5 parts, water-based ink thickener 3 parts, ethylene glycol 1 part, isocyanate-based cross-linking agent 3 parts The entire surface was solid-printed on a 100-mesh screen plate using a screen printing ink obtained by mixing the above, and dried and cured at 130 ° C. for 5 minutes to form a porous layer.
Next, a 100 mesh screen was used on the porous layer using a screen printing ink containing 50.0 parts of polyethylene glycol resin [trade name: PEG4000, manufactured by Sanyo Chemical Industries, Ltd.] and 50.0 parts of water. A dot pattern having a diameter of 2 mm was printed on a plate and dried and cured at 100 ° C. for 5 minutes to form a water-soluble resin layer having translucency to obtain a water discoloration indicator.

When the back surface (support side) of the water discoloration indicator was fixed to the joint portion of the pipe using a binding band and put into practical use, in the normal state (non-water absorption state), the white color due to the porous layer and the inside of the porous layer The porous layer becomes transparent due to the transparent resin layer partially embedded, and the blue dot pattern is visible, but when water adheres to the back surface, water passes through the cotton broad cloth of the support to the porous layer and the water-soluble resin layer. The polyethylene glycol resin of the water-soluble resin layer adheres to the surroundings, and the porous layer becomes transparent by absorbing liquid, and the water-adhered portion is visually recognized as a solid blue color.
The indicator in the state where water is attached shows the above-mentioned aspect, but when the porous layer dries, it returns to the original white state, and the water-soluble resin layer in the part where water is attached is a polyethylene glycol resin porous layer. Since the dot pattern disappeared or lightened due to elution and diffusion, only the white color of the porous layer became visible, and the appearance was different from that before the water adhered, so it should be determined that water had adhered in the past. Was made.
When water adhered to the water discoloration indicator again, the porous layer became transparent due to the liquid absorption and the blue color was visually recognized, and the state in which the water adhered could be repeatedly visually recognized.
In addition, even if a large amount of water adhered to the indicator and water flowed out to the surroundings, the water-soluble resin was transparent and did not become dirty.

Example 3
As a support, on the surface of blue 100% cotton broad fabric, wet method fine particle silica [trade name: Nipseal E-220, manufactured by Nippon Silica Industry Co., Ltd.] 15 parts, urethane emulsion [trade name: Hydran AP-10, Dainippon Ink Chemical Industry Co., Ltd., solid content 30%] 45 parts, water 40 parts, silicone-based defoamer 0.5 parts, water-based ink thickener 3 parts, ethylene glycol 1 part, isocyanate-based cross-linking agent 3 parts The entire surface was solid-printed on a 100-mesh screen plate using a screen printing ink obtained by mixing the above, and dried and cured at 130 ° C. for 5 minutes to form a porous layer.
Next, on the porous layer, 25.0 parts of polyvinylpyrrolidone resin [trade name: Socalan K-17, manufactured by BASF], 55.6 parts of acrylic acid ester resin emulsion [trade name: Movinyl 966A, Nippon Synthetic Chemical Co., Ltd. ), Solid content 45%], using a screen printing ink containing 19.4 parts of water, print a dot pattern with a diameter of 2 mm on a 100 mesh screen plate, dry and cure at 100 ° C for 5 minutes to make it transparent. A water-soluble resin layer having photophilicity was formed to obtain a water discoloration indicator.

When the back surface (support side) of the water discoloration indicator was attached to the seat portion of the chair and put into practical use, in the normal state (non-water absorption state), the white color due to the porous layer and a part of it were contained in the porous layer. The transparent resin layer makes the porous layer transparent and the blue dot pattern is visible, but when water adheres from the surface, the polyvinylpyrrolidone resin of the water-soluble resin layer is in a state of being eluted to the surroundings, and the porous layer becomes It becomes transparent by absorbing liquid, and the blue color of the water-adhered part is visually recognized in a solid state.
The indicator in the state where water is attached shows the above-mentioned aspect, but when the porous layer dries, it returns to the original white state, and the water-soluble resin layer in the part where water is attached is a porous layer of polyvinylpyrrolidone resin. Since the dot pattern disappears or becomes lighter due to elution and diffusion, only the white color of the porous layer becomes visible, and the appearance is different from that before the water adhered, so it is necessary to determine that water has adhered in the past. Was made.
When water adhered to the water discoloration indicator again, the porous layer became transparent due to the liquid absorption, and the blue color due to the support was visually recognized, and the state in which water was adhered could be repeatedly visually recognized.
Even if the water discoloration indicator is left in an environment of 30 ° C. and 85% humidity for 72 hours, the colored layer can retain the dot pattern before wetting, and is excellent in storage stability in the initial state. rice field.
In addition, even if a large amount of water adhered to the indicator and water flowed out to the surroundings, the water-soluble resin was transparent and did not become dirty.

Example 4 (see FIG. 2)
As support 2, on the surface of blue 100% cotton broad cloth, wet method fine particle silica [trade name: Nipseal E-220, manufactured by Nippon Silica Industry Co., Ltd.] 15 parts, urethane emulsion [trade name: Hydran AP-10, large Nippon Ink Chemical Industry Co., Ltd., solid content 30%] 45 parts, water 40 parts, silicone-based defoamer 0.5 parts, water-based ink thickener 3 parts, ethylene glycol 1 part, isocyanate-based cross-linking agent 3 The entire surface was solid-printed on a 100-mesh screen plate using a screen printing ink obtained by mixing the parts, and dried and cured at 130 ° C. for 5 minutes to form the porous layer 3.
Next, on the porous layer, 50.0 parts of polyethylene glycol resin [trade name: PEG4000, manufactured by Sanyo Kasei Kogyo Co., Ltd.], 11.1 parts of acrylic acid ester resin emulsion [trade name: Movinyl 966A, Nippon Synthetic Chemical Co., Ltd. Made by Co., Ltd., solid content 45%], using a screen printing ink containing 38.9 parts of water, a dot pattern with a diameter of 2 mm is printed on a 100 mesh screen plate, and dried and cured at 100 ° C. for 5 minutes. A water-soluble resin layer 4 having translucency is formed, and a colorless and transparent polyethylene terephthalate film (thickness 25 μm) is further formed on the porous layer and the water-soluble resin layer by using a water-insoluble adhesive made of an acrylic resin. A waterproof layer 5 was formed by sticking it on the entire surface to obtain a water discoloration indicator 1.

When the back surface (support side) of the water discoloration indicator was fixed to the joint portion of the pipe using a binding band and put into practical use, in the normal state (non-water absorption state), the white color due to the porous layer and the inside of the porous layer The porous layer becomes transparent due to the transparent resin layer partially embedded, and the blue dot pattern is visible, but when water adheres from the back surface, water passes through the cotton broad cloth of the support to the porous layer and the water-soluble resin layer. The polyethylene glycol resin of the water-soluble resin layer adheres to the surroundings, and the porous layer becomes transparent by absorbing liquid, and the water-adhered portion is visually recognized as a solid blue color.
The indicator in the state where water is attached shows the above-mentioned aspect, but when the porous layer dries, it returns to the original white state, and the water-soluble resin layer in the part where water is attached is a polyethylene glycol resin porous layer. Since the dot pattern disappeared or lightened due to elution and diffusion, only the white color of the porous layer became visible, and the appearance was different from that before the water adhered, so it should be determined that water had adhered in the past. Was made.
When water adheres to the water discoloration indicator from the back surface again, the porous layer becomes transparent due to liquid absorption and the blue color is visually recognized, and the state in which the water adheres can be repeatedly visually recognized, and the water adhered from the front surface can be detected. Instead, it detects only the water adhering from the back surface, so it was useful as an indicator to detect the presence or absence of water leakage from the joint part.
Even if the water discoloration indicator is left in an environment of 30 ° C. and 85% humidity for 72 hours, the colored layer can retain the dot pattern before wetting, and is excellent in storage stability in the initial state. rice field.
In addition, even if a large amount of water adhered to the indicator and water flowed out to the surroundings, the water-soluble resin was transparent and did not become dirty.

Example 5
On the surface of blue T / C (65/35) broad cloth as a support, wet method fine particle silica [trade name: Nipseal E-220, manufactured by Nippon Silica Industry Co., Ltd.] 15 parts, urethane emulsion [trade name: Hydran AP -10, manufactured by Dainippon Ink Chemical Industry Co., Ltd., solid content 30%] 45 parts, water 40 parts, silicone-based defoamer 0.5 parts, water-based ink thickener 3 parts, ethylene glycol 1 part, isocyanate Using a screen printing ink obtained by mixing three parts of the system cross-linking agent, the entire surface was solid-printed on a 100-mesh screen plate and dried and cured at 130 ° C. for 5 minutes to form a porous layer.
Next, on the porous layer, 25.0 parts of a polyvinylpyrrolidone resin [trade name: Socalan K-17, manufactured by BASF] and 25.0 parts of a polyethylene glycol resin [trade name: PEG4000, manufactured by Sanyo Kasei Kogyo Co., Ltd.] A dot pattern having a diameter of 2 mm is printed on a 100-mesh screen plate using a screen printing ink containing 50.0 parts of water, and dried and cured at 100 ° C. for 5 minutes to obtain a translucent water-soluble resin layer. Further, a colorless and transparent polyethylene terephthalate film (thickness 25 μm) was attached to the entire surface of the porous and water-soluble resin layer using a water-insoluble adhesive made of acrylic resin to form a waterproof layer. ..
Next, a water-insoluble adhesive layer made of a dot-shaped acrylic resin was provided on the back surface of the support to obtain a water discoloration indicator.

When the adhesive layer side of the water discoloration indicator was attached to the joint portion of the pipe and put into practical use, in the normal state (non-water absorption state), the white color due to the porous layer and the transparent resin partially contained in the porous layer. The layer makes the porous layer transparent and a blue dot pattern is visible, but when water adheres from the back surface, water adheres to the porous layer and the water-soluble resin layer through the T / C broad cloth of the support, and is water-soluble. The polyvinylpyrrolidone resin and the polyethylene glycol resin of the sex resin layer are in a state of being eluted to the surroundings, and the porous layer is made transparent by the liquid absorption, and the water-adhered portion is visually recognized in a solid state in blue.
The indicator in the state where water is attached shows the above-mentioned aspect, but when the porous layer dries, it returns to the original white state, and the water-soluble resin layer in the part where water is attached is polyvinylpyrrolidone resin and polyethylene glycol resin. Distilled and diffused into the porous layer, causing the dot pattern to disappear or lighten and only the white color of the porous layer to be visible. Was able to be determined.
When water adheres to the water discoloration indicator from the back surface again, the porous layer becomes transparent due to liquid absorption and the blue color is visually recognized, and the state in which the water adheres can be repeatedly visually recognized, and the water adhered from the front surface can be detected. However, since it detects only the water adhering from the back surface, it was useful as an indicator for detecting the presence or absence of water leakage from the joint portion.
Even if the water discoloration indicator is left in an environment of 30 ° C. and 85% humidity for 72 hours, the colored layer can retain the dot pattern before wetting, and is excellent in storage stability in the initial state. rice field.
In addition, even if a large amount of water adhered to the indicator and water flowed out to the surroundings, the water-soluble resin was transparent and did not become dirty.

Example 6
Wet method fine particle silica [trade name: Nipseal E-220, manufactured by Nippon Silica Industry Co., Ltd.] 15 parts, urethane emulsion [trade name: Hydran AP-10, Dainippon Ink Chemicals] on the surface of red polyethylene terephthalate film as support 2. Made by Kogyo Co., Ltd., solid content 30%] 45 parts, water 40 parts, silicone-based defoamer 0.5 parts, water-based ink thickener 3 parts, ethylene glycol 1 part, isocyanate-based cross-linking agent 3 parts mixed The entire surface was solid-printed with the screen printing ink, and dried and cured at 80 ° C. for 5 minutes to form a porous layer.
Next, using a screen printing ink containing 30 parts of polyvinyl alcohol resin [trade name: Gosenol KL-03, manufactured by Nippon Synthetic Chemical Co., Ltd.] and 70 parts of water on the porous layer, a screen plate of 100 mesh is used. The lattice pattern was printed at 60 ° C. and dried and cured at 60 ° C. for 30 minutes to form a water-soluble resin layer having translucency, and a water discoloration indicator 1 was obtained.

When the back surface (support side) of the water discoloration indicator was attached to a mobile phone and put into practical use, the white color due to the porous layer and the transparent resin partially contained in the porous layer under normal conditions (non-water absorption state). The layer makes the porous layer transparent and a red lattice pattern is visible, but when water adheres from the surface, the polyvinyl alcohol resin of the water-soluble resin layer is in a state of being eluted to the surroundings, and the porous layer absorbs liquid. The water-adhered part becomes transparent and the red color is visually recognized in a solid state.
The indicator in the state where water is attached shows the above-mentioned aspect, but when the porous layer dries, it returns to the original white state, and the water-soluble resin layer in the portion where water is attached is a porous layer of polyvinyl alcohol resin. Since the lattice pattern disappeared or lightened due to elution and diffusion, only the white color of the porous layer became visible, and the appearance was different from that before the water adhered, so it should be determined that water had adhered in the past. Was made.
When water adhered to the water discoloration indicator again, the porous layer became transparent due to the liquid absorption and red color was visually recognized, and the state in which water was adhered could be repeatedly visually recognized.
In addition, even if a large amount of water adhered to the indicator and water flowed out to the surroundings, the water-soluble resin was transparent and did not become dirty.

Example 7 (see FIG. 3)
As the support 2, a solid blue colored layer 6 is formed on the surface of white synthetic paper with a blue water-resistant screen printing ink, and then a wet method fine particle silica [trade name:] is formed on the colored layer. Nip seal E-220, manufactured by Nippon Silica Industry Co., Ltd.] 15 parts, urethane emulsion [trade name: Hydran AP-10, manufactured by Dainippon Ink and Chemicals Co., Ltd., solid content 30%] 45 parts, water 40 parts, silicone Solid printing is performed on the entire surface with a screen printing ink made by mixing 0.5 parts of a defoaming agent, 3 parts of a thickener for water-based ink, 1 part of ethylene glycol, and 3 parts of an isocyanate-based cross-linking agent, and printing at 80 ° C. for 5 minutes. The porous layer 3 was formed by drying and curing.
Next, 80 meshes were used on the porous layer using a screen printing ink containing 25.0 parts of a hydroxypropyl cellulose resin [trade name: HPC-L, manufactured by Nippon Soda Co., Ltd.] and 75.0 parts of water. A star pattern was printed on the screen plate of No. 1 and dried and cured at 60 ° C. for 30 minutes to form a translucent water-soluble resin layer 4 to obtain a water discoloration indicator 1.

When the back surface (support side) of the water discoloration indicator was attached to a pipe and put into practical use, in a normal state (non-water absorption state), a white color due to the porous layer and a transparent resin layer partially contained in the porous layer were used. The porous layer becomes transparent and a blue star pattern is visible, but when water adheres from the surface, the hydroxypropyl cellulose resin of the water-soluble resin layer is in a state of being eluted to the surroundings, and the porous layer absorbs liquid. It becomes transparent and the water-adhered part is visually recognized in a solid state in blue.
The indicator in the state where water is attached shows the above-mentioned aspect, but when the porous layer dries, it returns to the original white state, and the water-soluble resin layer in the part where water is attached is made of hydroxypropyl cellulose resin. Since the star pattern disappears or becomes lighter due to elution and diffusion in the layer, only the white color of the porous layer becomes visible, and the appearance is different from that before the water adhered, so it is determined that water has adhered in the past. I was able to.
When water adhered to the water discoloration indicator again, the porous layer became transparent due to the liquid absorption and the blue color was visually recognized, and the state in which the water adhered could be repeatedly visually recognized.
In addition, even if a large amount of water adhered to the indicator and water flowed out to the surroundings, the water-soluble resin was transparent and did not become dirty.

Example 8 (see FIG. 4)
As the support 2, a colored layer 6 having a heart pattern having water resistance and water permeability is provided on the surface of a white polyester non-woven fabric using a blue printing ink, and then a wet method fine particle silica is provided on the colored layer. [Product name: Nipseal E-220, manufactured by Nippon Silica Industry Co., Ltd.] 15 parts, urethane emulsion [Product name: Hydran AP-10, manufactured by Dainippon Ink Chemical Industry Co., Ltd., solid content 30%] 45 parts, water A 100-mesh screen using a screen printing ink made by mixing 40 parts, 0.5 part of silicone-based defoamer, 3 parts of thickener for water-based ink, 1 part of ethylene glycol, and 3 parts of isocyanate-based cross-linking agent. The entire surface was solidly printed on a plate and dried and cured at 130 ° C. for 5 minutes to form the porous layer 3.
Next, from above the porous layer, 25.0 parts of polyvinylpyrrolidone resin [trade name: Socalan K-17, manufactured by BASF], 55.6 parts of acrylic acid ester resin emulsion [trade name: Movinyl 966A, Nippon Synthetic Chemical Co., Ltd. Made of plastic, solid content 45%], using a screen printing ink containing 19.4 parts of water, a star pattern was printed on a 100 mesh screen plate so that it was located above the heart pattern of the colored layer, and the temperature was 110 ° C. The water-soluble resin layer 4 having translucency was formed by drying and curing for 5 minutes to obtain a water discoloration indicator 1.

When the back surface (support side) of the water discoloration indicator was attached to a disposable diaper and put into practical use, the white color due to the porous layer and the transparent resin layer partially contained in the porous layer under normal conditions (non-water absorption state) were obtained. The porous layer becomes transparent and a blue star pattern is visible, but when water adheres from the back surface, it adheres to the porous layer and the water-soluble resin layer through the polyester non-woven fabric and the colored layer of the support, and the water-soluble resin. The polyvinylpyrrolidone resin in the layer is in a state of being eluted to the surroundings, and the porous layer is made transparent by absorbing liquid, and a blue heart pattern is visually recognized in the water-attached portion.
The indicator in the state where water is attached shows the above-mentioned aspect, but when the porous layer dries, it returns to the original white state, and the water-soluble resin layer in the part where water is attached is a polyethylene glycol resin porous layer. Since the star pattern disappears or becomes lighter due to elution and diffusion, only the white color of the porous layer becomes visible, and the appearance is different from that before water adhered, so it is necessary to determine that water has adhered in the past. Was made.
When water adheres to the water discoloration indicator from the back surface again, the porous layer becomes transparent by absorbing liquid and a blue heart pattern is visually recognized, and the state in which water is adhered can be repeatedly visually recognized to check for the presence or absence of urine leakage. It was useful as an indicator to detect.
Even if the water discoloration indicator was left for 72 hours in an environment of 30 ° C. and 85% humidity, the star pattern before getting wet could be retained, and the storage stability in the initial state was also excellent.
In addition, even if a large amount of urine adhered to the indicator and urine flowed out to the surroundings, the water-soluble resin was transparent and did not become dirty.

1 Water discoloration indicator 2 Support 3 Porous layer 4 Water-soluble resin layer 5 Waterproof layer 6 Colored layer

Claims (7)

A porous layer in which a low refractive index pigment is fixed to a binder resin in a dispersed state on a support, which is opaque in a non-liquid absorbing state and becomes transparent in a liquid absorbing state, and a part of the porous layer. However, the water-soluble resin layer is provided in the coexisting state, and the porous layer of the portion provided with the water-soluble resin layer in the non-liquid absorbing state is larger than the porous layer of the portion not provided with the water-soluble resin layer. A discoloration indicator characterized by high translucency. The discoloration indicator according to claim 1, wherein the water-soluble resin layer contains a transparent resin. The discoloration indicator according to claim 1 or 2, wherein the water-soluble resin layer is a resin in a solid state at 25 ° C. The discoloration indicator according to any one of claims 1 to 3, wherein the support is a water-permeable support. The discoloration indicator according to claim 4, wherein a waterproof layer is provided on the uppermost layer. The discoloration indicator according to any one of claims 1 to 5, wherein a non-discoloration coloring layer is provided on the support. The discoloration indicator according to any one of claims 1 to 6, wherein an adhesive layer is provided on the bottom layer.

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