JP2006117807A - Color-changing pressure-sensitive adhesive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prepare a color-changing pressure-sensitive adhesive sheet enabling visual recognition of the change of aspect caused by the efficient absorption of a liquid leaked from an object to a porous layer in a state bonded to the object to give unexpected appearance and decorative property and having usefulness and convenience as a detection means such as an indicator because the absorbed liquid is held in the layer for a relatively long period. <P>SOLUTION: A porous layer containing a pigment having low refractive index and fixed in a binder resin in dispersed state, exhibiting opaque nature in a non-water absorbed state and turning transparent in a water-absorbed state is applied to the back face of a transparent sheet and a liquid-permeable adhesive layer is applied to the porous layer to prepare the color-changing pressure-sensitive adhesive sheet. As an alternative, a porous layer containing a pigment having low refractive index and fixed in a binder resin in dispersed state, and exhibiting opaque nature in a non-water absorbed state and turning transparent in a water-absorbed state is applied to the back face of a transparent sheet and an adhesive layer is partly applied to the porous layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a discolorable pressure-sensitive adhesive sheet. More specifically, the present invention relates to a discolorable pressure-sensitive adhesive sheet that can visually recognize an aspect different from a dry state by adhering a liquid such as water.

Conventionally, a porous layer containing a low refractive index pigment is laminated on the surface of a sheet material provided with an adhesive layer on the back surface, and a liquid such as water is absorbed into the porous layer to make it transparent, so that the color tone of the base is exhibited. A water discolorable pressure-sensitive adhesive sheet is disclosed (for example, see Patent Document 1).
JP 2002-129117 A

The sheet described above is a water-color-changeable adhesive sheet in which a sheet having an arbitrary shape and size is attached to an appropriate part of an object, and a change in appearance can be visually recognized when a liquid adheres, and the unexpectedness and decoration are enhanced.
However, the sheet has a configuration in which the liquid adheres from the seal surface and returns to the original state when the adhering liquid evaporates. Therefore, it has been difficult to maintain the changed state for a relatively long time.
In addition, when the sheet is used as an indicator, when liquid such as water leaks from the object itself to which the sheet is attached, in the configuration in which the porous layer provided on the sheet surface is provided, the liquid is present in the porous layer. It was difficult to adhere, and even if the liquid leaked temporarily and adhered, it was difficult to confirm whether or not the liquid leaked due to evaporation of the liquid, and the practicality as a detection means was poor.

The present invention provides, on the back surface of the transparent sheet material, a low refractive index pigment fixed to a binder resin in a dispersed state, provided with a porous layer that is opaque in a non-liquid absorbing state and transparent in a liquid absorbing state, A color-changing pressure-sensitive adhesive sheet in which a liquid-permeable pressure-sensitive adhesive layer is provided on a porous layer is a requirement.
Furthermore, a liquid-permeable colored layer is provided between the porous layer and the adhesive layer, a colorant is contained in the adhesive layer, and a colorant is contained in the porous layer. This is a requirement.
Further, on the back surface of the transparent sheet material, there is provided a porous layer in which a low refractive index pigment is fixed in a binder resin in a dispersed state, which is opaque in a non-liquid-absorbing state and transparent in the liquid-absorbing state. A discolorable pressure-sensitive adhesive sheet obtained by partially providing a pressure-sensitive adhesive layer on the layer is a requirement.
Furthermore, a liquid-permeable colored layer is provided between the porous layer and the adhesive layer, an adhesive layer and a colored layer are provided on the porous layer, and a colorant is provided in the adhesive layer. Comprising a colorant in the porous layer, the colorant being a pigment, the transparent sheet material being a liquid-impermeable or poorly-permeable sheet material, It is inherent in a part of the porous layer and is provided with a hydrophobic resin layer in a coexisting state, a release layer is provided on the adhesive layer, and the discolorable adhesive sheet is superimposed on the surface of the core. A tape-type discolorable pressure-sensitive adhesive sheet is required.

  In the present invention, since the liquid leaking from the object is efficiently absorbed into the porous layer and can be visually recognized in the state of being adhered to the object, the present invention can provide unexpectedness and decorativeness, and can absorb the liquid. Since the liquefied liquid is held for a relatively long time, it is possible to provide a discolorable pressure-sensitive adhesive sheet having practicality and convenience suitable as detection means such as an indicator.

Any material can be used as the transparent sheet material as long as it has transparency, but a transparent plastic sheet is preferably used.
Specific examples of the material for the transparent sheet material include plastic sheets such as polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polymethyl methacrylate, polyacrylate, polystyrene, polycarbonate, cellulose triacetate, cellulose diacetate, polyvinyl alcohol, and polyamide. A glass plate can be exemplified, but plastic sheets such as polyethylene, polypropylene, polyethylene terephthalate, and polyvinyl chloride, which are rich in flexibility and excellent in safety, are preferably used.
The transparency may be colorless and transparent, colored transparent, translucent, and colored translucent.
The transparent sheet material prevents the liquid from being absorbed into the porous layer through the sheet material due to condensation in a state of being adhered to the object, and the liquid leaking from the object is applied to the porous layer. In order to maintain the absorbed state for a relatively long time, it is preferably a liquid impermeable or hardly permeable sheet material.

The pressure-sensitive adhesive layer is formed on the back surface of the transparent sheet material by coating a pressure-sensitive adhesive mainly composed of general-purpose acrylic resin, urethane resin, styrene-butadiene copolymer, vinyl ether copolymer, natural rubber and the like. .
The adhesive layer is preferably provided with a release layer such as release paper on the adhesive layer for the convenience of use.
The pressure-sensitive adhesive may be used in combination with a tackifier.

The porous layer formed on the transparent sheet material is a layer in which a low refractive index pigment is fixed in a dispersed state together with a binder resin.
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 white, magnesium carbonate, and the like. It is in the range of 1.8, and when the liquid composition is absorbed, good transparency is exhibited.
Examples of the silicic acid salt include aluminum silicate, aluminum potassium silicate, sodium aluminum silicate, aluminum calcium silicate, potassium silicate, calcium silicate, sodium calcium silicate, sodium silicate, magnesium silicate, and potassium magnesium silicate.
The particle size of the low refractive index pigment is not particularly limited, but 0.03 to 10.0 μm is preferably used.
Two or more of the low refractive index pigments can be used in combination.
In addition, silicic acid is mentioned as a low refractive index pigment used suitably.
The silicic acid may be silicic acid produced by a dry process, but silicic acid produced by a wet process (hereinafter referred to as wet process silicic acid) is particularly effective and satisfies practicality.
This point will be described below.
Silicic acid is produced as amorphous amorphous silicic acid, and according to its production method, a dry process using a gas phase reaction such as thermal decomposition of silicon halide such as silicon tetrachloride (hereinafter referred to as dry process silicic acid) In general, the wet process silicic acid is most suitable for the purpose of functioning as the porous layer intended by the present invention. .
This is because the dry process silicic acid and the wet process silicic acid have different structures, and the dry process silicic acid forms a three-dimensional structure in which the silicic acid is closely bound, whereas the wet process silicic acid is a long molecule formed by condensation of silicic acid. It has a so-called two-dimensional structure part that forms an array.
Therefore, since the molecular structure becomes rough compared to the dry method silicic acid, when wet method silicic acid is applied to the porous layer, it is excellent in the diffused reflection of light in the dry state compared to the system using the dry method silicic acid, Therefore, it is guessed that the concealment property in a normal state becomes large.
Moreover, in the porous layer of the present invention, since liquid such as water is absorbed, wet process silicic acid has more hydroxyl groups present as silanol groups on the particle surface than dry process silicic acid, and is hydrophilic. The degree is large and it is preferably used.
In addition, in order to adjust the concealability in the normal state of the porous layer and the transparency in the liquid absorption state, other general-purpose low-refractive-index pigments can be used in combination with the wet method silicic acid.

The wet process silicic acid in the porous layer depends on properties such as particle size, specific surface area, oil absorption, etc., but in order to satisfy both the concealing property in the normal state and the transparency in the liquid absorbing state, it is applied. preferably the amount is ^{1g / m 2 ~30g / m 2} , more preferably ^{5g / m 2 ~20g / m 2} .
If it is less than 1 g / m ² , it is difficult to obtain sufficient concealability in a normal state, and if it exceeds 30 g / m ² , it is difficult to obtain sufficient transparency upon liquid absorption.
The particle size of the silicic acid is not particularly limited, but 0.03 to 10.0 μm is preferably used.
The silicic acid is dispersed in a vehicle containing a binder resin as a binder, applied to a base material, and then the volatile matter is dried to form a porous layer.
Examples of the binder resin include urethane resin, nylon resin, vinyl acetate resin, acrylic ester resin, acrylic ester copolymer resin, acrylic polyol resin, vinyl chloride-vinyl acetate copolymer resin, maleic resin, polyester resin, 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 Each resin emulsion, casein, starch, cellulose derivative, polyvinyl alcohol, urea resin, phenol resin and the like can be mentioned.
The mixing ratio of the silicic acid and these binder resins depends on the type and properties of silicic acid, but is preferably 0.5 to 2 parts by weight of binder resin solids, more preferably 1 part by weight of silicic acid. 0.8 to 1.5 parts by weight. When the binder resin solid content is less than 0.5 parts by weight with respect to 1 part by weight of silicic acid, it is difficult to obtain a practical film strength of the porous layer, and when it exceeds 2 parts by weight, The permeability of water into the porous layer is deteriorated.
Since the porous layer has a small mixing ratio of the binder resin to the colorant as compared with a conventionally known general coating film, it is difficult to obtain sufficient film strength. Therefore, in order to increase the scratch resistance, it is effective to use a nylon resin or a urethane resin among the binder resins.
Examples of the urethane resin include a polyester urethane resin, a polycarbonate urethane resin, and a polyether urethane resin, and two or more of them can be used in combination. In addition, a urethane emulsion resin in which the resin is emulsified and dispersed in water, or a colloid in which the resin is self-emulsified without the need for an emulsifier by an ionic group of the ionic urethane resin (urethane ionomer) itself and dissolved or dispersed in water A dispersion type (ionomer type) urethane resin can also be used.
The urethane-based resin may be either an aqueous urethane-based resin or an oil-based urethane-based resin, but in the present invention, an aqueous urethane-based resin, in particular, a urethane-based emulsion resin or a colloidally dispersed urethane-based resin is suitable. Used for.
The urethane resin can be used alone, but other binder resins can be used in combination depending on the type of support and the performance required for the coating. When a binder resin other than the urethane resin is used in combination, in order to obtain a practical film strength, it is preferable to contain 30% or more of the urethane resin in a solid content weight ratio in the binder resin of the porous layer. In the binder resin, the crosslinkable resin can be further improved in film strength by adding an arbitrary crosslinking agent and crosslinking.
The binder resin has a large or small affinity with water. By combining these, the penetration time into the porous layer, the degree of penetration, and the slow speed of drying after the penetration can be adjusted. Furthermore, the said adjustment can be controlled by adding a dispersing agent suitably.

  The porous layer is a conventionally known means, for example, printing means such as screen printing, offset printing, gravure printing, coater, tampo printing, transfer, brush coating, spray coating, electrostatic coating, electrodeposition coating, flow coating. It can be formed by roller coating, dip coating or the like.

Next, a specific configuration of the discolorable pressure-sensitive adhesive sheet of the present invention will be described in detail.
As described above, a transparent sheet material is used for the discolorable pressure-sensitive adhesive sheet. This is because the porous layer is provided in the lower layer, so that the porous layer is opaque in the non-liquid-absorbing state and transparent in the liquid-absorbing state, and the state of the lower layer can be seen through from the surface of the transparent sheet material. It is for doing so.
On the back surface of the transparent sheet material, a porous layer which is opaque in a non-liquid-absorbing state and transparent in a liquid-absorbing state is provided, and an adhesive layer is further provided on the upper surface.
Therefore, in the dry state with the pressure-sensitive adhesive sheet attached to the object, the color tone due to the low refractive index pigment, which is the color material contained in the porous layer, is visually recognized.
When liquid is absorbed into the porous layer, the porous layer becomes transparent and the color tone of the lower layer is visually recognized, but the color tone of the lower layer is visually recognized when the colored layer is not provided. It will be.
Therefore, the color tone of the porous layer in the dry state and the color tone of the object need to be different.
In addition, if it is configured to provide a colored layer and visually recognize the color tone of the colored layer in a state where the porous layer is transparent, it can be put into practical use without considering the color tone of the above-mentioned object. There is no loss of sex.
In addition to interposing the colored layer between the porous layer and the pressure-sensitive adhesive layer, the same effect and effect can be obtained by adding a colorant in the pressure-sensitive adhesive layer or by adding a colorant in the porous layer. it can.
As the colorant, general-purpose dyes and pigments are used, and pigments excellent in water resistance are preferably used.
In the present invention, when an adhesive layer is provided on the entire surface of the porous layer, the adhesive layer needs to have a function of allowing the liquid to pass through in order to adhere the liquid to the porous layer in a state where the adhesive sheet is attached to the object. There is.
Furthermore, when the colored layer is interposed between the porous layer and the adhesive layer, when the colored layer is provided on the entire surface of the porous layer, the liquid adheres to the porous layer with the adhesive sheet attached to the object. In order to achieve this, the colored layer must also have a function of transmitting liquid.
Moreover, when providing an adhesion layer partially on a porous layer, the said adhesion layer does not need to be provided with the function to permeate | transmit a liquid. In this case, an adhesive layer and a colored layer can be provided on the porous layer.
Further, a hydrophobic resin layer can be provided in a part of the porous layer and coexisting, and the porous layer in the coexisting position of the water repellent resin layer is not formed in a water absorbing state due to a water repellent effect. The opaque aspect of the porous layer itself can be maintained. Therefore, the water-repellent resin layer, which is difficult to distinguish in the normal state (non-liquid-absorbing state), is visually recognized by water absorption to the porous layer not provided with the water-repellent resin layer.

  The porous layer, the water-repellent resin layer, and the colored layer described above are not limited to solid prints, and may be images of characters, symbols, alphanumeric characters, lines, designs, and the like.

The discolorable pressure-sensitive adhesive sheet can be applied to the object as it is in a flat shape, or cut into a desired size and shape and attached to the object, or the surface of the core formed of paper or the like can be discolored. It is also possible to use the adhesive sheet practically in the form of a tape by weighting it.
By adopting the tape form, it is easy to carry and can save resources because there is no need to provide a release layer, and can be cut to a suitable size according to the length of the object and attached. , Applicable to objects of various shapes and sizes.

The object to which the discolorable pressure-sensitive adhesive sheet obtained as described above is attached is not limited to a planar shape, and includes various forms such as a linear shape, an uneven shape, and a three-dimensional shape.
Specific examples include toys, dolls, costumes for dolls, models imitating cars and ships, learning tools, books with waterproofing, entertainment tools such as puzzles and games, and the like.
It can also be used as various indicators, for example, detection of liquid leaks from pipes, pipes, water tanks, tanks, detection of liquid leaks at pipes and connections between pipes, and parts connected to pipes and pipes (faucets, etc.) Examples include detection of leakage at connecting parts, detection of water leakage from walls of houses, transportation of water-inhibiting chemicals, detection of leakage of storage containers, detection of urine in disposable diapers, and the like.

Examples of the present invention will be described below. In addition, the part in an Example shows a weight part.
Example 1 (see FIG. 1)
As the transparent sheet material 2, 15 parts of wet process fine particle silica [trade name: NIPSEAL E-220, manufactured by Nippon Silica Kogyo Co., Ltd.] on the back of a transparent polyethylene terephthalate film (thickness 16 μm), urethane emulsion [trade name: Hydran] AP-10, manufactured by Dainippon Ink & Chemicals, Inc., solid content 30%] 45 parts, water 40 parts, silicone-based antifoaming agent 0.5 part, aqueous ink thickener 3 parts, ethylene glycol 1 part, Using a white screen printing ink obtained by uniformly mixing and stirring 3 parts of an isocyanate-based crosslinking agent, the entire surface is solid-printed on a 100-mesh screen plate and dried and cured at 60 ° C. for 30 minutes to form a porous layer 3 did.
Further, an acrylic resin-based adhesive containing a porous pigment was applied on the entire surface of the porous layer 3 to provide an adhesive layer 4 having liquid permeability.
Next, the side of the release paper coated with silicon was bonded to the pressure-sensitive adhesive layer 4 to provide a release layer 5 to obtain a color-changing pressure-sensitive adhesive sheet 1.
In the normal state (non-water-absorbing state), the discolorable pressure-sensitive adhesive sheet is visually recognized as white by the porous layer, and when the release layer is peeled off and water is attached to the pressure-sensitive adhesive layer, the porous layer becomes transparent due to liquid absorption.
Although it was transparent in the liquid-absorbed state, it returned to its original white state by drying, and the above-mentioned change in appearance could be reproduced repeatedly.

The discolorable pressure-sensitive adhesive sheet obtained as described above was cut into a circle by Thomson, and the release layer was peeled off and adhered to the vicinity of the joint of a black hard polyvinyl chloride water pipe.
The discolorable pressure-sensitive adhesive sheet was white in a state where there was no water leakage from the joint, but when the water leaked from the joint and reached the discolorable pressure-sensitive adhesive sheet, the porous layer penetrates from the adhesive layer to the porous layer. Becomes transparent by absorbing liquid, and therefore, the color-changing pressure-sensitive adhesive sheet changes its color from white to black by a pipe when viewed from the transparent sheet side.
In addition, the sheet | seat which exhibits black in the state which leaked the water returns to original white by repairing a joint part and eliminating water leak, and functions as a reversible water leak indicator.

Example 2 (see FIG. 2)
Using the same white screen printing ink as in Example 1 on the back of a transparent soft vinyl chloride film (thickness: 100 μm) as the transparent sheet material 2, the entire surface was solid-printed on a 100 mesh screen plate at 50 ° C. The porous layer 3 was formed by drying and curing for 30 minutes.
Next, using a screen printing ink containing a fluorescent pink pigment on the porous layer 3, the entire surface is solid-printed on a 180 mesh screen plate, dried and cured at 50 ° C. for 30 minutes, and has liquid permeability. A colored layer 6 was formed.
Further, a vinyl ether copolymer resin adhesive containing a porous pigment is applied onto the colored layer 6 to provide a liquid-permeable adhesive layer 4, which is layered on the surface of the core and slit into a 20 mm width tape. The form of the discolorable pressure-sensitive adhesive sheet 1 was obtained.
In the normal state (non-water-absorbing state), the color-changeable pressure-sensitive adhesive sheet is visually recognized as white due to the porous layer, and when water is attached to the pressure-sensitive adhesive layer, the porous layer becomes transparent due to liquid absorption and the pink color due to the colored layer is visually recognized. .
Although it was pink in the liquid-absorbed state, it returned to its original white state upon drying, and the above-mentioned change in appearance could be reproduced repeatedly.

The discolorable pressure-sensitive adhesive sheet obtained as described above was cut into a length of 3 cm and adhered to a joint portion of a metal water pipe.
The color-changing pressure-sensitive adhesive sheet was white in a state where there was no water leakage from the joint, but when the water leaked from the joint and reached the color-changing pressure-sensitive adhesive sheet, it penetrates into the porous layer through the pressure-sensitive adhesive layer and the colored layer. The porous layer is made transparent by liquid absorption, so that the discolorable pressure-sensitive adhesive sheet changes color from white to pink when viewed from the transparent sheet material side.
The pink sheet in the state of water leakage returns to the original white color by repairing the joint portion to eliminate water leakage, and functions as a reversible water leakage indicator.

Example 3
On the back of a transparent polypropyne film (thickness 50 μm) having a corona-treated surface as a transparent sheet material, 15 parts of wet method fine particle silica [trade name: NIPSEAL E-1011, manufactured by Nippon Silica Kogyo Co., Ltd.], urethane emulsion [ Product name: Hydran AP-10, manufactured by Dainippon Ink & Chemicals, Inc., solid content 30%], 45 parts, water 40 parts, silicone antifoam 0.5 parts, aqueous ink thickener 3 parts, ethylene Using a white screen printing ink obtained by uniformly mixing and stirring 1 part of glycol and 3 parts of an isocyanate-based crosslinking agent, the entire surface is solid-printed on a 100-mesh screen plate and dried and cured at 60 ° C. for 30 minutes to be porous. A layer was formed.
Furthermore, a urethane colored adhesive containing a porous pigment and a blue pigment was applied on the entire surface of the porous layer to provide a blue colored adhesive layer having liquid permeability.
Next, the side of the release paper coated with silicon was bonded to the adhesive layer to provide a release layer to obtain a discolorable adhesive sheet.
In the normal state (non-water-absorbing state), the discolorable pressure-sensitive adhesive sheet is visually recognized as white due to the porous layer. When the release layer is peeled off and water is attached to the adhesive layer, the porous layer is cleared by liquid absorption and colored adhesive. The blue color due to the layer is visible.
Although blue was exhibited in the liquid-absorbed state, it returned to the original white state by drying, and the above-mentioned change in appearance could be repeatedly reproduced.

The discolorable pressure-sensitive adhesive sheet obtained as described above was cut into a rectangle and stuck so as to close the hole provided in the water storage part of the water gun.
The discolorable pressure-sensitive adhesive sheet was white in a state where the water storage portion of the water gun was not filled with water, but when the water was filled, water penetrated into the porous layer from the pores through the adhesive layer. The quality layer is made transparent by liquid absorption, so that the color-changing pressure-sensitive adhesive sheet changes color from white to blue when viewed from the transparent sheet material side.
In addition, the sheet | seat which exhibits blue in the state to which the said water adhered has become white when the water of a water storage part is lost, and can also provide the playability as a toy, and also functions as a reversible moisture indicator.

Example 4
On the back of a transparent polyethylene film (100 μm thick) with a corona-treated surface as a transparent sheet material, 15 parts of wet method fine particle silica [trade name: NIPSEAL E-220, manufactured by Nippon Silica Kogyo Co., Ltd.], urethane emulsion [commodity Name: Hydran AP-10, manufactured by Dainippon Ink & Chemicals, Inc., solid content 30%] 45 parts, pink pigment 0.5 part, water 40 parts, silicone-based antifoaming agent 0.5 part, for water-based ink Using a pink screen printing ink obtained by uniformly mixing and stirring 3 parts of a thickener, 1 part of ethylene glycol, and 3 parts of an isocyanate-based crosslinking agent, the entire surface was solid-printed on a 100 mesh screen plate at 60 ° C. It was dried and cured for 30 minutes to form a colored porous layer.
Further, a urethane resin adhesive containing a porous pigment was applied on the entire surface of the colored porous layer to provide an adhesive layer having liquid permeability.
Next, the side of the release paper coated with silicon was bonded to the adhesive layer to provide a release layer to obtain a discolorable adhesive sheet.
In the normal state (non-water-absorbing state), the discolorable pressure-sensitive adhesive sheet has a pastel pink color due to the porous layer, and when the release layer is peeled off and water is attached to the pressure-sensitive adhesive layer, the colored porous layer becomes transparent due to liquid absorption. Vivid pink color is visible.
In the liquid-absorbed state, it showed a bright pink color, but returned to the original pastel pink color state upon drying, and the above-mentioned change in appearance could be reproduced repeatedly.

The discolorable pressure-sensitive adhesive sheet obtained as described above was cut into a circle by Thomson, and the release layer was peeled off and adhered to the vicinity of the joint of a blue hard polyvinyl chloride water pipe.
The discolorable pressure-sensitive adhesive sheet had a pastel pink color when there was no water leak from the joint, but when the water leaks from the joint and reaches the discolorable pressure-sensitive adhesive sheet, it penetrates the colored porous layer through the adhesive layer. The colored porous layer is colored and transparent by liquid absorption, and therefore, when viewed from the transparent sheet material side, the discolorable pressure-sensitive adhesive sheet changes from pastel pink to purple, which is a mixture of transparent pink and blue of the pipe. .
The purple sheet in the state of water leakage returns to the original pastel pink color by repairing the joint portion to eliminate water leakage, and functions as a reversible water leakage indicator.

Example 5 (see FIG. 3)
As transparent sheet material 2, on the back of a pink transparent polyethylene terephthalate film (thickness: 16 μm), 15 parts of wet method fine particle silica [trade name: NIPSEAL E-220, manufactured by Nippon Silica Kogyo Co., Ltd.], urethane emulsion [trade name] : Hydran AP-10, manufactured by Dainippon Ink & Chemicals, Inc., solid content 30%] 45 parts, water 40 parts, silicone antifoam 0.5 parts, aqueous ink thickener 3 parts, ethylene glycol 1 Using a white screen printing ink obtained by uniformly mixing and stirring 3 parts of an isocyanate-based crosslinking agent, the entire surface was solid-printed on a 100-mesh screen plate, dried and cured at 60 ° C. for 30 minutes, and porous layer 3 Formed.
Further, a hydrophobic acrylic resin adhesive was partially applied in the form of dots on the porous layer 3 to provide an adhesive layer 4.
Next, the side of the release paper coated with silicon was bonded to the adhesive layer to provide the release layer 5, and the discolorable adhesive sheet 1 was obtained.
In the normal state (non-water-absorbing state), the discolorable pressure-sensitive adhesive sheet is visually recognized as white due to the porous layer and opaque pink color due to the pink transparent polyethylene terephthalate film located on the upper surface thereof. When water is attached, the porous layer is transparentized by absorbing liquid, and a transparent pink color is visible.
In the liquid-absorbed state, it had a transparent pink color, but returned to its original opaque pink color by drying, and the above-mentioned change in appearance could be reproduced repeatedly.

The discolorable pressure-sensitive adhesive sheet obtained as described above was cut into a circle by Thomson, and the release layer was peeled off and adhered to the vicinity of the joint of a blue hard polyvinyl chloride water pipe.
The color-changing pressure-sensitive adhesive sheet was pink in the state where there was no water leakage from the joint, but when water leaked from the joint and reached the color-changing pressure-sensitive adhesive sheet, it penetrated the porous layer and became transparent, and thus transparent. When viewed from the sheet material side, the color-changing adhesive sheet changes from pink to purple, which is a mixture of pink and blue of the pipe.
The purple sheet in the leaked state returns to the original pink color by repairing the joint portion to eliminate the water leak, and functions as a reversible water leak indicator.

Example 6 (see FIG. 4)
On the back surface of a transparent soft polyvinyl chloride film (thickness: 100 μm) as the transparent sheet material 2, using the same white screen printing ink as in Example 1, the entire surface was printed with a 100 mesh screen plate, and 50 The porous layer 3 was formed by drying and curing at 30 ° C. for 30 minutes.
Next, using a screen printing ink containing a green pigment on the porous layer 3, the entire surface is solid-printed on a 180 mesh screen plate, dried and cured at 50 ° C. for 30 minutes, and the liquid permeability is increased. A green colored layer 6 was formed.
Further, a hydrophobic vinyl ether copolymer resin-based adhesive is partially applied in the form of dots on the colored layer 6 to provide an adhesive layer 4 which is layered on the surface of the core and slit into a width of 20 mm. A discolorable pressure-sensitive adhesive sheet 1 was obtained.
In the normal state (non-water-absorbing state), the color-changing pressure-sensitive adhesive sheet is visually recognized as white due to the porous layer, and when water is attached from the back surface, the porous layer is transparentized due to liquid absorption and green due to the colored layer is observed.
Although green was exhibited in the liquid-absorbed state, it returned to the original white color by drying, and the change in appearance could be reproduced repeatedly.

The discolorable pressure-sensitive adhesive sheet obtained as described above was cut to a length of 3 cm and adhered to a joint of a water pipe made of hard vinyl chloride.
The color-changing pressure-sensitive adhesive sheet was white in the state where there was no water leakage from the joint, but when water leaked from the joint and reached the color-changing pressure-sensitive adhesive sheet, it penetrated the porous layer through the colored layer and became transparent, Therefore, when viewed from the transparent sheet material side, the discolorable pressure-sensitive adhesive sheet changes color from white to green.
The green sheet in the state of water leakage returns to the original white color by repairing the joint portion to eliminate water leakage, and functions as a reversible water leakage indicator.

Example 7 (see FIG. 5)
On the back surface of a transparent soft polyvinyl chloride film (thickness: 100 μm) as the transparent sheet material 2, using the same white screen printing ink as in Example 1, the entire surface was printed with a 100 mesh screen plate, and 50 The porous layer 3 was formed by drying and curing at 30 ° C. for 30 minutes.
Next, using a screen printing ink containing a red pigment on the porous layer 3, the letters “water leakage” is printed on a 180-mesh screen plate and dried and cured at 50 ° C. for 30 minutes. Thus, a red colored image 61 having liquid permeability was formed.
Further, a hydrophobic vinyl ether copolymer resin-based adhesive is applied to the periphery of the colored image 61 to provide an adhesive layer 4, which is placed on the surface of the core and slit into a width of 20 mm to change the tape-like discolorable adhesive sheet. 1 was obtained.
In the normal state (non-water-absorbing state), the color-changing pressure-sensitive adhesive sheet is visually recognized as white due to the porous layer, and when water is attached from the back side, the porous layer becomes transparent due to liquid absorption and the characters “water leakage” due to a colored image Is visible.
In the liquid-absorbed state, the characters “occurrence of water leak” were visually recognized. However, when the liquid was dried, the original white state was restored, and the change in the appearance could be reproduced repeatedly.

The discolorable pressure-sensitive adhesive sheet obtained as described above was cut into a length of 5 cm and adhered to a joint of a water pipe made of hard vinyl chloride.
The color-changing pressure-sensitive adhesive sheet was white in the state where there was no water leakage from the joint, but when water leaked from the joint and reached the color-changing pressure-sensitive adhesive sheet, the porous layer penetrated and became transparent, and thus the transparency sheet. When viewed from the material side, the color-changing adhesive sheet changes from a white state on the entire surface to a state where red “water leakage” appears.
In addition, the sheet in which the characters “occurrence of water leakage” appear in the state of water leakage returns to the original white color by repairing the joint portion to eliminate water leakage, and functions as a reversible water leakage indicator.

Example 8
On the back of a transparent polyethylene terephthalate film (thickness 16 μm) as a transparent sheet material, 15 parts of wet method fine particle silica [trade name: NIPSEAL E-220, manufactured by Nippon Silica Kogyo Co., Ltd.], urethane emulsion [trade name: Hydran AP -10, manufactured by Dainippon Ink and Chemicals, Inc., solid content 30%] 45 parts, water 40 parts, silicone antifoam 0.5 parts, aqueous ink thickener 3 parts, ethylene glycol 1 part, isocyanate Using a white screen printing ink obtained by uniformly mixing and stirring 3 parts of the system cross-linking agent, the entire surface was solid-printed on a 100-mesh screen plate and dried and cured at 60 ° C. for 30 minutes to form a porous layer.
Further, a colored sticky image was provided by partially printing the letter “water leakage” using an acrylic resin-based pressure-sensitive adhesive containing a blue pigment and a porous pigment on the porous layer.
Next, the side of the release paper coated with silicon was bonded to the colored adhesive image to provide a release layer to obtain a discolorable adhesive sheet.
In the normal state (non-water-absorbing state), the color-changing pressure-sensitive adhesive sheet is visually recognized as white by the porous layer, and when the release layer is peeled off and water is sprayed from the back side, the porous layer becomes transparent due to liquid absorption and a colored pressure-sensitive adhesive image The blue “water leak” letter is visible.
In the liquid-absorbed state, the characters “occurrence of water leak” were visually recognized. However, when the liquid was dried, it returned to the original white color, and the above-mentioned change in appearance could be reproduced repeatedly.

The discolorable pressure-sensitive adhesive sheet obtained as described above was attached to the vicinity of the joint portion of the white hard polyvinyl chloride water pipe after peeling the release layer.
The color-changing pressure-sensitive adhesive sheet was white in the state where there was no water leakage from the joint, but when water leaked from the joint and reached the color-changing pressure-sensitive adhesive sheet, the porous layer penetrated and became transparent, and thus the transparency sheet. When viewed from the side of the material, the color-changing pressure-sensitive adhesive sheet appears white to blue with “water leakage”.
In addition, the sheet in which the characters “occurrence of water leakage” appear in the state of water leakage returns to the original white color by repairing the joint portion to eliminate water leakage, and functions as a reversible water leakage indicator.

Example 9
On the back of a transparent polyethylene film (100 μm thick) with a corona-treated surface as a transparent sheet material, 15 parts of wet method fine particle silica [trade name: NIPSEAL E-220, manufactured by Nippon Silica Kogyo Co., Ltd.], urethane emulsion [commodity Name: Hydran AP-10, manufactured by Dainippon Ink & Chemicals, Inc., solid content 30%] 45 parts, pink pigment 0.5 part, water 40 parts, silicone-based antifoaming agent 0.5 part, for water-based ink Using a pink screen printing ink obtained by uniformly mixing and stirring 3 parts of a thickener, 1 part of ethylene glycol, and 3 parts of an isocyanate-based crosslinking agent, the entire surface was solid-printed on a 100 mesh screen plate at 60 ° C. It was dried and cured for 30 minutes to form a colored porous layer.
Furthermore, a liquid-permeable colored adhesive image was provided on the colored porous layer by printing a letter “water leakage” using a urethane resin adhesive containing a blue pigment and a porous pigment.
Next, the side of the release paper coated with silicon was bonded to the colored adhesive image to provide a release layer to obtain a discolorable adhesive sheet.
In the normal state (non-water-absorbing state), the discolorable pressure-sensitive adhesive sheet has a pastel pink color due to the colored porous layer, and when the release layer is peeled off and water is attached from the back, the colored porous layer is transparent due to liquid absorption. It turns pink, and the pink letters “water leak” are visible on a purple background mixed with the blue color of the colored adhesive image.
In the liquid-absorbed state, the characters “occurrence of water leak” were visually recognized, but when dried, the original pastel pink color was restored, and the change in appearance could be reproduced repeatedly.

The discolorable pressure-sensitive adhesive sheet obtained as described above was cut into a circle by Thomson, and the release layer was peeled off and adhered to the vicinity of the joint of a white hard polyvinyl chloride water pipe.
The discolorable pressure-sensitive adhesive sheet exhibited a pastel pink color when there was no water leak from the joint, but when the water leaked from the joint and reached the discolorable pressure-sensitive adhesive sheet, the colored porous layer penetrated and became a transparent pink color. Therefore, when viewed from the side of the transparent sheet material, the color-changeable pressure-sensitive adhesive sheet appears pink with “water leakage” on a purple background.
In addition, the sheet in which the word “water leak occurred” appears in the state of water leaking above will return to the original pastel pink color by repairing the joint part and eliminating the water leak, functioning as a reversible water leak indicator To do.

Example 10
As a transparent sheet material, on the back of a transparent polyethylene terephthalate film (thickness 16 μm), 15 parts of wet method fine particle silica [trade name: NIPSEAL E-220, manufactured by Nippon Silica Kogyo Co., Ltd.], urethane emulsion [trade name: Hydran AP -10, manufactured by Dainippon Ink and Chemicals, Inc., solid content 30%] 45 parts, water 40 parts, silicone antifoaming agent 0.5 parts, aqueous ink thickener 3 parts, ethylene glycol 1 part, isocyanate Using a white screen printing ink obtained by uniformly mixing and stirring 3 parts of the system cross-linking agent, the entire surface was solid-printed on a 100-mesh screen plate and dried and cured at 60 ° C. for 30 minutes to form a porous layer.
Furthermore, a letter “water leak” is printed on a 150-mesh screen plate using a fluorine-based water repellent on the porous layer, dried and cured at 130 ° C. for 3 minutes, and water-repellent in the porous layer. A hydrophobic coexistence layer impregnated with the agent was provided.
Further, an acrylic resin-based adhesive containing a porous pigment was applied to the entire surface to provide a liquid-permeable adhesive layer.
Next, the side of the release paper coated with silicon was bonded to the adhesive layer to provide a release layer to obtain a discolorable adhesive sheet.
In the normal state (non-water-absorbing state), the color-changing pressure-sensitive adhesive sheet is visually recognized as white due to the porous layer, and when the release layer is peeled off and water is attached from the back side, only the porous layer portion where the hydrophobic coexistence layer is not provided It becomes transparent by liquid absorption and the word “water leak occurs” appears.
In the liquid-absorbed state, the characters “occurrence of water leak” were visually recognized. However, the original white state was restored by drying, and the above-described change in the appearance could be repeatedly reproduced.

The discolorable pressure-sensitive adhesive sheet obtained as described above was cut into a circle by Thomson, and the release layer was peeled off and adhered to the vicinity of the joint of a black hard polyvinyl chloride water pipe.
The color-changing pressure-sensitive adhesive sheet was white in a state where there was no water leakage from the joint, but when the water leaked from the joint and reached the color-changing pressure-sensitive adhesive sheet, a portion where a hydrophobic coexistence layer was not formed via the pressure-sensitive adhesive layer The porous layer becomes transparent. Accordingly, when viewed from the transparent sheet material side, the black color of “water leakage” appears on the white background of the discolorable pressure-sensitive adhesive sheet.
In the state where water has leaked, the sheet on which the characters “occurrence of water leak” appear returns to the original white color by repairing the joint portion to eliminate the water leak, and functions as a reversible water leak indicator.

It is a longitudinal cross-sectional explanatory drawing of one Example of the color-change adhesive sheet of this invention. It is a longitudinal cross-sectional explanatory drawing of the other Example of the discolorable adhesive sheet of this invention. It is a longitudinal cross-sectional explanatory drawing of the other Example of the discolorable adhesive sheet of this invention. It is a longitudinal cross-sectional explanatory drawing of the other Example of the discolorable adhesive sheet of this invention. It is a longitudinal cross-sectional explanatory drawing of the other Example of the discolorable adhesive sheet of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Discolorable adhesive sheet 2 Transparent sheet material 3 Porous layer 4 Adhesive layer 5 Release layer 6 Colored layer 61 Colored image

Claims (14)

  On the back side of the transparent sheet material, a low refractive index pigment is fixed in a binder resin in a dispersed state, and a non-liquid-absorbing and opaque porous layer is provided on the porous layer. A discolorable pressure-sensitive adhesive sheet comprising a liquid-permeable pressure-sensitive adhesive layer.   The discolorable pressure-sensitive adhesive sheet according to claim 1, wherein a liquid-permeable colored layer is provided between the porous layer and the pressure-sensitive adhesive layer.   The discolorable pressure-sensitive adhesive sheet according to claim 1, comprising a colorant in the pressure-sensitive adhesive layer.   The discolorable pressure-sensitive adhesive sheet according to claim 1, comprising a colorant in the porous layer.   On the back side of the transparent sheet material, a low refractive index pigment is fixed in a binder resin in a dispersed state, and a non-liquid-absorbing and opaque porous layer is provided on the porous layer. And a discolorable pressure-sensitive adhesive sheet obtained by partially providing a pressure-sensitive adhesive layer.   The discolorable pressure-sensitive adhesive sheet according to claim 5, wherein a liquid-permeable colored layer is provided between the porous layer and the pressure-sensitive adhesive layer.   The discolorable pressure-sensitive adhesive sheet according to claim 5, wherein an adhesive layer and a colored layer are provided on the porous layer.   The discolorable pressure-sensitive adhesive sheet according to claim 5, comprising a colorant in the pressure-sensitive adhesive layer.   The discolorable pressure-sensitive adhesive sheet according to claim 5, comprising a colorant in the porous layer.   The discolorable pressure-sensitive adhesive sheet according to any one of claims 2 to 4 and 6 to 9, wherein the colorant is a pigment.   The discolorable pressure-sensitive adhesive sheet according to any one of claims 1 to 10, wherein the transparent sheet material is a liquid-impermeable or hardly-permeable sheet material.   The discolorable pressure-sensitive adhesive sheet according to any one of claims 1 to 11, wherein the discolorable pressure-sensitive adhesive sheet is provided in a part of the porous layer and has a hydrophobic resin layer in a coexisting state.   The discolorable pressure-sensitive adhesive sheet according to any one of claims 1 to 12, wherein a release layer is provided on the pressure-sensitive adhesive layer.   A color-changing pressure-sensitive adhesive sheet in the form of a tape in which the color-changing pressure-sensitive adhesive sheet according to any one of claims 1 to 12 is placed on the surface of a core.

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