Water-colored body, Water-colored body set

Abstract

To provide a water discoloration body and a water discoloration body set which can easily extend maintenance time of a water discoloration image by covering the water discoloration image with a cover member immediately after forming the water discoloration image, and can maintain the formed water discoloration image in a clear state.SOLUTION: A water discoloration body 1 and a water discoloration body set include a water discoloration sheet 2 having a porous layer obtained by fixing a low refractive index pigment to a binder resin in a dispersion state on an upper layer of a coloring layer, and a transparent cover member 6 that covers a water discoloration image formed by attaching water to the surface of the porous layer, suppresses dryness of the water, and delays disappearance of the water discoloration image, in which the surface of the water discoloration sheet and the transparent cover member are held in a non-contact state on the lower surface of the transparent cover member, and projections 8 contacting the surface of the water discoloration sheet are non-linearly arranged in at least three or more parts.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a water-discoloring body and a water-discoloring body set. More specifically, the present invention relates to a water-discoloring body and a water-discoloring body set that include a water-discoloring sheet and a cover member that delays the disappearance of a water-discoloring image formed on the water-discoloring sheet. [Background technology]

[0002] Conventionally, a water-discoloring body has been disclosed in which a porous layer in which a low refractive index pigment, which is opaque in a non-water-absorbing state and becomes transparent in a water-absorbing state, is dispersed and fixed in a binder resin is disposed on a colored layer. A water-discoloring material set has also been disclosed in which the water-discoloring image is formed by applying water with a writing or stamping tool or a finger, and then immediately after the water-discoloring image is formed, the water-discoloring image is covered with a cover member, thereby extending the maintenance time of the water-discoloring image (see, for example, Patent Document 1). The water-color changing material set can prolong the time for which the water-color changing image is maintained, and can satisfy the practicality of toys and educational tools. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-254547 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention aims to provide a hydrochromic material and a hydrochromic material set that can extend the duration of the hydrochromic image formed on this type of hydrochromic material and that can clearly maintain the hydrochromic image. [Means for solving the problem]

[0005] The present invention provides a water-discoloring sheet comprising a porous layer, on top of a colored layer, in which a low refractive index pigment is dispersed and fixed in a binder resin, and a transparent cover member that covers the water-discoloring image formed on the surface of the porous layer by the adhesion of water, inhibits the water from drying, and delays the disappearance of the water-discoloring image. The underside of the transparent cover member is in contact with the water-discoloring sheet surface, keeping the water-discoloring sheet surface and the transparent cover member out of contact. Dotted The convex parts must be arranged in a non-linear pattern in at least three places. The convex portions have a height of 0.4 mm to 12.0 mm, and the surface area (s) of the convex portions visible from the top surface of the transparent cover member and the height (h) of the convex portions satisfy the following formula (1), and the area occupied by the convex portions visible from the top surface of the transparent cover member is 10% or less of the surface area of ​​the top surface of the transparent cover member: The requirement is that the material be a hydrochromic material. 1.0≦s / h≦400 (1) Furthermore, The dot-like protrusions are arranged in a grid pattern. The convex portion is transparent, the convex portion is white, the tip of the convex portion is curved, the transparent cover member is flexible, and the convex portion is 100 cm 2 The requirements are that there are three or more per porous layer, the surface of the transparent cover member is non-glossy, one end of the transparent cover member is attached to the water-discoloring sheet and the other end is free, and the transparent cover member is attached to the water-discoloring sheet so that it can be opened and closed freely, the transparent cover member is made up of a plurality of the water-discoloring sheets and a plurality of the transparent cover members, and a letter frame or model letter is provided on the porous layer of the water-discoloring sheet. Furthermore, the present invention requires a water-discoloring body set including the water-discoloring body and a water-attaching tool for forming a water-discoloring image. [Effects of the Invention]

[0006] The present invention provides a water-discoloring object and a water-discoloring object set that are both marketable and practical as a toy or teaching tool, by covering the water-discoloring image with a cover member immediately after forming the water-discoloring image by applying water to the image using a writing or stamping implement or a finger, etc., and thereby easily extending the duration of the water-discoloring image and allowing the formed water-discoloring image to remain clear. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a top view showing a water-chromatic body according to an embodiment of the present invention; [Figure 2] FIG. 2 is a longitudinal sectional view of the water-chromatic body of FIG. 1. [Figure 3] FIG. 10 is a top view showing a water-chromatic body according to another embodiment of the present invention. [Figure 4] 1 is a top view of a water-changing body set according to an embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] The water-discoloring sheet has a porous layer formed on the colored layer, in which a low refractive index pigment is fixed in a dispersed state in a binder resin. The support itself may also serve as the colored layer, but it is preferable to provide a colored layer (including an image of any shape) on the surface of the support. The support may be made of paper, synthetic paper, fabric such as woven fabric, knitted fabric, braided fabric, or nonwoven fabric, natural or synthetic leather, plastic, glass, ceramics, metal, wood, stone, etc. The support is preferably flat, but may also be uneven. The colored layer provided on the surface of the support is formed from a binder resin containing a colorant. Examples of the colorant include general dyes, general pigments, fluorescent dyes, fluorescent pigments, and metallic luster pigments. The colorant is contained in a vehicle containing a binder resin as a binder, and the ink or paint is applied to a support, and then the volatile components are dried to form a colored layer. Examples of the binder resin include urethane resins, nylon resins, vinyl acetate resins, acrylic ester resins, acrylic ester copolymer resins, acrylic polyol resins, vinyl chloride-vinyl acetate copolymer resins, maleic acid resins, polyester resins, styrene resins, styrene copolymer resins, polyethylene resins, polycarbonate resins, epoxy resins, styrene-butadiene copolymer resins, acrylonitrile-butadiene copolymer resins, methyl methacrylate-butadiene copolymer resins, butadiene resins, chloroprene resins, melamine resins, and emulsions of each of the above resins, casein, starch, cellulose derivatives, polyvinyl alcohol, urea resins, and phenolic resins. The colored layer is formed on the support by a printing means such as process printing, screen printing, offset printing, gravure printing, coater, pad printing, inkjet printing, or transfer printing, or by a brush coating, spray coating, electrostatic coating, electrodeposition coating, flow coating, roller coating, or dip coating. Alternatively, a transfer layer can be formed by first applying an ink or paint contained in a vehicle containing a colorant and a binder resin as a binder onto another substrate, and then transferring the transfer layer onto the support to form a colored layer. Furthermore, when the support has transparency, a colored layer can be provided on the back surface of the support (the surface on which the porous layer is not provided).

[0009] A water-discoloring sheet can be obtained by laminating a porous layer on the colored layer, in which a low refractive index pigment is fixed in a dispersed state by a binder resin. 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 is a layer whose transparency differs between a dry state and a liquid-absorbing state. Examples of the low refractive index pigment include silicic acid and its salts, barytic powder, barium sulfate, barium carbonate, calcium carbonate, gypsum, clay, talc, alumina white, and magnesium carbonate, which have a refractive index in the range of 1.4 to 1.8 and exhibit good transparency when absorbing water. Examples of the salt of silicic acid include aluminum silicate, potassium aluminum silicate, sodium aluminum silicate, calcium aluminum silicate, potassium silicate, calcium silicate, sodium calcium silicate, sodium silicate, magnesium silicate, and potassium magnesium silicate. A preferred example of a low refractive index pigment is silica. Two or more of the low refractive index pigments can also be used in combination. The particle size of the low refractive index pigment is not particularly limited, but is preferably 0.03 to 10.0 μm. The silicic acid may be silicic acid produced by a dry method, but silicic acid produced by a wet method (hereinafter referred to as wet-method silicic acid) is particularly effective. In this regard, silicic acid is produced as amorphous silicic acid, and depending on the production method, it can be broadly divided into dry-method silicic acid (hereinafter referred to as dry-method silicic acid) which uses a gas phase reaction such as thermal decomposition of silicon halide such as silicon tetrachloride, and wet-method silicic acid which uses a liquid phase reaction such as decomposition with an acid such as sodium silicate. Dry-method silicic acid and wet-method silicic acid have different structures; the dry-method silicic acid forms a three-dimensional structure in which silicic acid is tightly bonded, while wet-method silicic acid has a so-called two-dimensional structure in which silicic acid is condensed to form a long molecular arrangement. Therefore, since the molecular structure is coarser than that of the dry process silica, when wet process silica is applied to a porous layer, it is presumed that the system will have better diffused reflection of light in a dry state and greater hiding power in the normal state than a system using dry process silica. Furthermore, since the porous layer is capable of absorbing water, wet-process silica has more hydroxyl groups present as silanol groups on the particle surface than dry-process silica, and is therefore more hydrophilic, and is therefore preferably used. In order to adjust the hiding power of the porous layer in a normal state and the transparency in a liquid-absorbed state, other low refractive index pigments may be used in combination with the wet-process silica.

[0010] 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 hiding power in a normal state and transparency in a liquid-absorbed state, the coating amount is set to 1 to 50 g / m 2 It is preferable that the density is 5 to 50 g / m. 2 1g / m 2 If the density is less than 50 g / m, it is difficult to obtain sufficient hiding power under normal conditions. 2 If the thickness exceeds this value, it is difficult to obtain sufficient transparency when absorbing liquid. The low refractive index pigment is dispersed in a vehicle containing a binder resin as a binding agent, and after coating on a support, the volatile components are dried to form a porous layer. Examples of the binder resin include urethane resins, nylon resins, vinyl acetate resins, acrylic ester resins, acrylic ester copolymer resins, acrylic polyol resins, vinyl chloride-vinyl acetate copolymer resins, maleic acid resins, polyester resins, styrene resins, styrene copolymer resins, polyethylene resins, polycarbonate resins, epoxy resins, styrene-butadiene copolymer resins, acrylonitrile-butadiene copolymer resins, methyl methacrylate-butadiene copolymer resins, butadiene resins, chloroprene resins, melamine resins, and emulsions of each of the above resins, casein, starch, cellulose derivatives, polyvinyl alcohol, urea resins, and phenolic resins. The mixing ratio of the low refractive index pigment to the binder resin depends on the type and properties of the low refractive index pigment, but is preferably 0.5 to 2 parts by mass, more preferably 0.8 to 1.5 parts by mass, of binder resin solids per part by mass of the low refractive index pigment. If the binder resin solids per part by mass of the low refractive index pigment is less than 0.5 parts by mass, it is difficult to obtain a practical coating strength for the porous layer, and if it exceeds 2 parts by mass, water permeability into the porous layer is easily impaired. The porous layer has a smaller binder resin to colorant ratio than a general coating film, making it difficult to obtain sufficient film strength. Therefore, in order to improve abrasion resistance, it is effective to use a nylon resin or a urethane-based resin among the binder resins. The urethane resin may be a polyester urethane resin, a polycarbonate urethane resin, a polyether urethane resin, etc., and two or more of these may be used in combination. Alternatively, a urethane emulsion resin in which the resin is emulsified and dispersed in water, or a colloidal dispersion type (ionomer type) urethane resin in which the ionic urethane resin (urethane ionomer) itself emulsifies without the need for an emulsifier due to the ionic groups of the urethane resin itself, and is dissolved or dispersed in water, may also be used. The urethane resin may be either an aqueous urethane resin or an oil-based urethane resin, but an aqueous urethane resin, particularly an urethane emulsion resin or a colloidal dispersion type urethane resin, is preferably used. The urethane resin can be used alone, or can be used in combination with other binder resins depending on the performance required for the film. When a binder resin other than a urethane resin is used in combination, in order to obtain practical film strength, it is preferable that the urethane resin be contained in the binder resin of the porous layer in an amount of 30% or more by solid mass ratio. Among the binder resins, if the binder resin is crosslinkable, the strength of the film can be further improved by adding an optional crosslinking agent to crosslink the binder resin. The binder resins have different affinities with water, and by combining these, it is possible to adjust the time and degree of penetration into the porous layer and the rate of drying after penetration. Furthermore, the adjustment can be controlled by adding a dispersant or surfactant as appropriate.

[0011] The porous layer can be formed on the colored layer by printing means such as screen printing, offset printing, gravure printing, coater, pad printing, or transfer printing, brush coating, spray coating, electrostatic coating, electrodeposition coating, flow coating, roller coating, or dip coating.

[0012] Furthermore, a colorant may be added to the porous layer to color the porous layer in a dry state. Examples of the colorant include general dyes, general pigments, fluorescent dyes, fluorescent pigments, metallic luster pigments, reversible thermochromic compositions, reversible thermochromic microcapsule pigments encapsulating a reversible thermochromic composition, photochromic compositions, and photochromic microcapsule pigments encapsulating a photochromic composition. When fluorescent colorants such as fluorescent dyes and fluorescent pigments are used, the clarity of the color change is excellent. When photochromic colorants such as thermochromic colorants such as reversible thermochromic compositions and reversible thermochromic microcapsule pigments encapsulating a reversible thermochromic composition are used, a variety of changes can be imparted. The reversible thermochromic composition preferably contains three components: an electron-donating organic color-forming compound, an electron-accepting compound, and an organic compound medium that reversibly induces a color-forming reaction. As the photochromic composition, photochromic compounds such as spirooxazine compounds, spiropyran compounds, diarylethene compounds, etc. are preferably used.

[0013] The surface of the porous layer of the water-discoloring sheet is provided with a transparent cover member that covers the water-discoloring image formed by the adhesion of water to the surface of the porous layer, inhibits the water from drying, and delays the disappearance of the water-discoloring image. The transparent substrate forming the transparent cover member only needs to have a transparency sufficient to allow the water discoloration image to be seen through, and may be made of a plastic sheet material, a plastic molded body, or glass. A transparent, colored substrate may also be used. The surface of the transparent cover member has minute irregularities and is non-glossy, so that it is possible to prevent light from being reflected on the surface of the cover member and impairing the visibility of the water-discolored image. In addition, it is possible to write on the transparent cover member using an erasable writing instrument such as a whiteboard marker containing wipeable ink or a writing instrument containing ink that fades with water, to trace the water-discolored image, or to write other letters or marks. The underside of the transparent cover member (transparent base material) has at least three or more convex portions that contact the surface of the water-color changing sheet and are arranged in a non-linear pattern, keeping the surface of the water-color changing sheet and the transparent cover member in a non-contact state. The convex portions form a space between the porous layer and the transparent cover member, and also prevent the contours of the water-discolored image from becoming blurred and unclear, which would occur if the transparent cover member came into contact with the porous image and water in the image diffused to areas where no image was formed. By arranging the protrusions in a non-linear pattern at at least three locations, contact between the transparent cover member and the porous layer can be prevented. Furthermore, by having the convex portions have a height of 0.4 mm to 12.0 mm, preferably 0.5 mm to 10.0 mm, the space between the porous layer and the transparent cover member can inhibit the drying of water, thereby improving the function of delaying the disappearance of the water-discolored image. If the height of the convex portions is less than 0.4 mm, the water-discoloring image formed on the water-discoloring sheet is likely to come into contact with the transparent cover member, resulting in significant bleeding of the water-discoloring image and deformation of the image.If the height of the convex portions is more than 12.0 mm, the effect of suppressing water drying is difficult to exhibit, and it is difficult to extend the duration of the water-discoloring image. Furthermore, when the height was changed from 0.4 mm to 12.0 mm, 0.4 mm was the longest possible length of time the water discoloration image was maintained, so the length of time the water discoloration image was maintained could be adjusted by setting the height of the convex part. Furthermore, when the surface area (s) of the convex portions visible from the top surface of the transparent cover member and the height (h) of the convex portions satisfy the following formula (1), the visibility of the water-discolored image visible through the transparent cover member is not hindered by the convex portions, and the function of delaying the disappearance of the water-discolored image can be achieved. 1.0≦s / h≦ 4 00 (1) If s / h is less than 1.0, the shape of the convex portion will be sharp, which will easily damage the porous layer and require careful handling. 4 If it exceeds 00, the surface area of ​​the convex portions visible from the top surface of the transparent cover member becomes large, which tends to hinder the visibility of the water discoloration image. Furthermore, the area occupied by the convex portion visible from the upper surface of the cover member relative to the surface area of ​​the upper surface of the cover member is 1 By keeping the content at 0.0% or less, it is possible to prevent the projections from interfering with the visibility of the water discoloration image. The convex portions are preferably transparent, and when the porous layer is white, they preferably exhibit a white color, so that the convex portions can be prevented from interfering with the visibility of the water-discolored image. The curved tip of the convex portion makes it difficult for the porous layer to be damaged, prevents the porous layer from peeling off, and makes it easy for even small children to handle. Furthermore, since the transparent cover member has flexibility, the transparent cover member can be easily covered and peeled off, and the protrusion can be made to be 100 cm 2 By providing three or more, preferably four or more, per unit area, contact with the water-discolored image can be suitably avoided during use. Furthermore, by attaching one end of the transparent cover body to the water-discoloring sheet and leaving the other end as a free end so that it can be opened and closed freely on the water-discoloring sheet, convenience can be improved by allowing the water-discoloring image to be covered quickly and easily after it is formed. Furthermore, by making the water-discoloring body consist of a plurality of water-discoloring sheets and a plurality of transparent cover members, a water-discoloring image can be formed on another water-discoloring sheet before the water-discoloring image dries, so that the desired image can be formed quickly. The number of the water-coloring sheets and the number of the transparent cover members may be the same, or the number of the transparent cover members may be fewer. Furthermore, a water-color changing body consisting of a plurality of water-color changing sheets and a single transparent cover member can also produce the same effect. In a water-discoloring body consisting of a plurality of water-discoloring sheets and a plurality of transparent cover members, a letter frame or model letters can be provided on the porous layer of the water-discoloring sheet, thereby obtaining a water-discoloring body excellent for teaching purposes. By providing a water-discoloring sheet on which a character frame is formed by printing or other means on the porous layer, it is possible to visually confirm whether the water-discoloring image has been properly formed within the character frame, and to confirm whether the water-discoloring image has been formed in a balanced manner. The size, shape, color, line width, and line type of the character box are not particularly limited. By providing a water-discoloring sheet on which a model of characters or the like is provided by means of printing or the like on the porous layer, it is possible to visually confirm whether the water-discoloring image is formed according to the model, and to confirm whether the water-discoloring image is formed in a well-balanced manner. The size, shape, color, line width, and line type of the example are not particularly limited, and it may be a contour image or an image formed by a plurality of dots.

[0014] As a means for applying water to the water-discoloring sheet, a hand or finger may be wetted with water and brought into contact with the sheet, or a water application tool may be used. Examples of the water application tool include water guns, sprayers, writing or application tools with a brush tip or fiber pen body at the tip, writing or application tools that store water in a container and have a fiber body or brush that discharges the water from the container, stamping tools, etc. A writing implement or applicator using a plastic porous body or processed fiber body having continuous pores as a pen tip member as the water adhesion implement can easily form a written image and has improved practicality. In addition, a water-color changing object set can be constructed by combining the water-adhering tool and the water-color changing object, and can be used as a teaching tool set or a drawing toy set. Examples of the water-adhering device include writing implements and stamping implements. The writing implements can be a writing brush, a continuous-pore plastic body, felt, a resin-processed or fused fiber body, a plastic body with capillary gaps in the internal axial direction, or other such components that can be used alone, but a more practical writing implement is one in which the component is attached to the barrel as a pen tip and is configured to be able to extract water stored in the barrel. The stamping tool may be a stamping material made of a plastic porous body, a plastic molded body with a roughened stamping surface that is water-wettable, or a rotary stamp in which the above-mentioned component is attached to the outer periphery of a wheel-shaped rotating body. [Example]

[0015] Examples are shown below, but the present invention is not limited to these examples. In the examples, "parts" refers to parts by mass. Example 1 (see Figures 1 and 2) Preparation of hydrochromic bodies A colored layer 4 was formed on a support 3 made of white synthetic paper by screen printing using a 180-mesh screen stencil, using a screen printing ink prepared by uniformly mixing and stirring 5 parts of blue pigment, 50 parts of acrylic ester emulsion (solid content 50% by weight), 0.2 parts of silicone-based antifoaming agent, 3 parts of thickener, 2 parts of wetting agent, 1 part of leveling agent, 10 parts of water, and 2.5 parts of epoxy-based crosslinking agent. Next, on the colored layer, 15 parts of finely divided silica produced by a wet process (trade name: Nipsil E-200A, manufactured by Nippon Silica Kogyo Co., Ltd.), 50 parts of an aqueous urethane resin as a binder resin (trade name: Hydran AP-10, polyester-based urethane resin, solid content 30% by weight, manufactured by Dainippon Ink and Chemicals, Inc.), 30 parts of water, 0.5 parts of a silicone-based antifoaming agent, 3 parts of an aqueous ink thickener, 1 part of ethylene glycol, and 2 parts of an epoxy-based crosslinking agent were uniformly mixed and stirred to form a white screen printing ink, which was then solid-printed over the entire surface to form a porous layer 5, and a water-discolorable sheet 2 measuring 220 mm x 320 mm was obtained. Next, a transparent cover member 6 was obtained by providing three convex portions 8 made of transparent ABS resin, each having a diameter of 10 mm and a height of 1.0 mm and a conical shape with a curved tip, on the underside of a plate-shaped molded product made of transparent hard ABS resin and measuring 200 mm x 300 mm and 1.0 mm thick as the transparent substrate 7, at positions corresponding to the vertices of an isosceles triangle. The surface area (s) of the convex portion visible from the top surface of the transparent cover member is 78.5 mm 2 The height (h) of the convex portion was 1.0 mm, and the surface area (s) of the convex portion / height (h) of the convex portion was 78.5. The surface area of ​​the upper surface of the transparent cover member is 600 cm 2 The area of ​​the protrusions visible from the top surface of the transparent cover member is 2.36 cm 2 The ratio of the area occupied by the convex portions visible from the upper surface of the transparent cover member to the surface area of ​​the upper surface of the transparent cover member was 0.39%. A water-coloring body 1 comprising the water-coloring sheet 2 and the transparent cover member 6 was obtained.

[0016] The water-discoloring sheet was normally white, but when a writing tool containing water was used to write on the porous layer, a blue water-discoloring image was formed. The water-discolored image was maintained for 5 minutes in an environment of 25°C and 65% RH, but gradually disappeared as the water evaporated, and after 10 minutes the sheet returned to its white state. This phenomenon could be repeated many times. Next, a water-discolored image was formed on the water-discolored sheet by writing with a writing pen containing water, and the transparent cover member was placed on the water-discolored sheet on which the water-discolored image had been formed so that the tips of the convex portions were in contact with the surface of the water-discolored sheet. The water-discolored image was clearly visible through the transparent cover member, and the convex portions prevented the transparent cover member from coming into contact with the water-discolored image, thereby enabling the water-discolored image to be maintained clearly. Furthermore, the water discoloration image maintained the same shape as the water discoloration image immediately after writing, even after being left for 30 minutes in an environment of 25° C. and 65% RH. Next, when the transparent cover was removed from the water-discoloring sheet, the water-discoloring image gradually disappeared as the water evaporated, and after 10 minutes the image was completely decolorized and returned to its original state. This phenomenon could be repeated many times.

[0017] Example 2 (see Figure 3) Preparation of hydrochromic bodies A colored layer was formed on a support consisting of white synthetic paper with polyester nonwoven fabric provided on it. The support was made by uniformly mixing and stirring 5 parts of black pigment, 50 parts of acrylic ester emulsion (solid content 50% by weight), 0.2 parts of silicone antifoaming agent, 3 parts of thickener, 2 parts of wetting agent, 1 part of leveling agent, 10 parts of water, and 2.5 parts of epoxy crosslinking agent. The resulting ink was then screen printed using a 180-mesh screen. Next, a porous layer was formed on the colored layer by solid printing using a white screen printing ink made by uniformly mixing and stirring 15 parts of finely divided silica produced by a wet process (trade name: Nipsil E-200A, manufactured by Nippon Silica Kogyo Co., Ltd.), 50 parts of an aqueous urethane resin as a binder resin (trade name: Hydran AP-10, polyester-based urethane resin, solids content 30% by weight, manufactured by Dainippon Ink and Chemicals, Inc.), 30 parts of water, 0.5 parts of a silicone-based antifoaming agent, 3 parts of an aqueous ink thickener, 1 part of ethylene glycol, and 2 parts of an epoxy-based crosslinking agent. This was then used to obtain a water-discolorable sheet 2 measuring 280 mm x 380 mm. Next, 48 convex portions 8 made of white polyurethane resin, each 3 mm in diameter and 1.2 mm in height and with a curved hemispherical tip, were arranged in a checkerboard pattern at equal intervals of 47 mm on the underside of a flexible polyester transparent sheet 50 μm thick and 253 mm x 353 mm in size as a transparent substrate, to obtain a transparent cover member 6. The surface area (s) of the convex portion visible from the top surface of the transparent cover member is 7.07 mm 2 The height (h) of the convex portion was 1.2 mm, and the surface area (s) of the convex portion / height (h) of the convex portion was 5.89. The surface area of ​​the upper surface of the transparent cover member is 893.09 cm 2 The area of ​​the protrusions visible from the top surface of the transparent cover member is 3.39 cm 2 The ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 0.38%, and the ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 100 cm 2 The number of hit protrusions was 5.37. A water-coloring body 1 comprising the water-coloring sheet 2 and the transparent cover member 6 was obtained.

[0018] The water-discolored sheet was normally white, but when the porous layer was written on with a brush whose tip was impregnated with water, a black water-discolored image was formed. The water-discolored image was maintained for 5 minutes in an environment of 25°C and 65% RH, but gradually disappeared as the water evaporated, and after 10 minutes the sheet returned to its white state. This phenomenon could be repeated many times. Next, a water-discoloring image was formed on the water-discoloring sheet by writing with a brush whose tip was dipped in water, and the transparent cover member was placed on the water-discoloring sheet on which the water-discoloring image had been formed so that the tip of the convex portion was in contact with the surface of the water-discoloring sheet. The water-discolored image was clearly visible through the transparent cover member, and the convex portions prevented the transparent cover member from coming into contact with the water-discolored image, thereby enabling the water-discolored image to be maintained clearly. Furthermore, the water discoloration image maintained the same shape as the water discoloration image immediately after writing, even after being left for 30 minutes in an environment of 25° C. and 65% RH. Next, when the transparent cover was removed from the water-discoloring sheet, the water-discoloring image gradually disappeared as the water evaporated, and after 10 minutes the image was completely decolorized, returning to a completely white water-discoloring sheet. This phenomenon could be repeated many times. Furthermore, since the transparent cover member is flexible, the water-color changing body can be rolled up and carried around, and therefore has excellent portability.

[0019] Example 3 Preparation of hydrochromic bodies A water-discolored sheet was obtained in the same manner as in Example 2. Next, 48 convex portions made of white polyurethane resin, each 3 mm in diameter and 0.6 mm in height and with a curved hemispherical tip, were arranged in a checkerboard pattern at equal intervals of 47 mm on the underside of a flexible polyester transparent sheet 50 μm thick and 253 mm x 353 mm in size as a transparent substrate, to obtain a transparent cover member. The surface area (s) of the convex portion visible from the top surface of the transparent cover member is 7.07 mm 2 The height (h) of the convex portion was 0.5 mm, and the surface area (s) of the convex portion / height (h) of the convex portion was 14.14. The surface area of ​​the upper surface of the transparent cover member is 893.09 cm 2 The area of ​​the protrusions visible from the top surface of the transparent cover member is 3.39 cm 2 The ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 0.38%, and the ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 100 cm 2 The number of hit protrusions was 5.37. A water-coloring body comprising the water-coloring sheet and the transparent cover member was obtained.

[0020] The water-discolored sheet was normally white, but when a writing brush with a tip dipped in water was used to write on the porous layer, a black water-discolored image was formed. The water-discolored image was maintained for 5 minutes in an environment of 25°C and 65% RH, but gradually disappeared as the water evaporated, and after 10 minutes the sheet returned to its white state. This phenomenon could be repeated many times. Next, a water-discoloring image was formed on the water-discoloring sheet by writing with a brush whose tip was dipped in water, and the transparent cover member was placed on the water-discoloring sheet on which the water-discoloring image had been formed so that the tip of the convex portion was in contact with the surface of the water-discoloring sheet. The water-discolored image was clearly visible through the transparent cover member, and the convex portions prevented the transparent cover member from coming into contact with the water-discolored image, thereby enabling the water-discolored image to be maintained clearly. Furthermore, the water discoloration image maintained the same shape as the water discoloration image immediately after writing, even after being left for 30 minutes in an environment of 25° C. and 65% RH. Next, when the transparent cover was removed from the water-discoloring sheet, the water-discoloring image gradually disappeared as the water evaporated, and after 10 minutes the image was completely decolorized and returned to its original state. This phenomenon could be repeated many times. Furthermore, since the transparent cover member is flexible, the water-color changing body can be rolled up and carried around, and therefore has excellent portability.

[0021] Example 4 Preparation of hydrochromic bodies A water-discolored sheet was obtained in the same manner as in Example 2. Next, a transparent polyester sheet having a thickness of 50 μm and dimensions of 262 mm x 362 mm was used as a transparent substrate, and 48 convex portions made of white polyurethane resin with a diameter of 12 mm, a height of 5.0 mm, and a curved hemispherical shape at the tip were arranged in a checkerboard pattern at equal intervals of 38 mm to obtain a transparent cover member. The surface area (s) of the convex portion visible from the top surface of the transparent cover member is 113.04 mm 2 The height (h) of the convex portion was 5.0 mm, and the surface area (s) of the convex portion / height (h) of the convex portion was 22.61. The surface area of ​​the upper surface of the transparent cover member is 948.44 cm 2 The area of ​​the protrusions visible from the top surface of the transparent cover member is 54.26 cm 2 The ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 5.72%, and the ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 100 cm 2 The number of hit protrusions was 5.06. A water-coloring body comprising the water-coloring sheet and the transparent cover member was obtained.

[0022] The water-discolored sheet was normally white, but when a writing brush with a tip dipped in water was used to write on the porous layer, a black water-discolored image was formed. The water-discolored image was maintained for 5 minutes in an environment of 25°C and 65% RH, but gradually disappeared as the water evaporated, and after 10 minutes the sheet returned to its white state. This phenomenon could be repeated many times. Next, a water-discoloring image was formed on the water-discoloring sheet by writing with a brush whose tip was dipped in water, and the transparent cover member was placed on the water-discoloring sheet on which the water-discoloring image had been formed so that the tip of the convex portion was in contact with the surface of the water-discoloring sheet. The water-discolored image was clearly visible through the transparent cover member, and the convex portions prevented the transparent cover member from coming into contact with the water-discolored image, thereby enabling the water-discolored image to be maintained clearly. Furthermore, the water discoloration image maintained the same shape as the water discoloration image immediately after writing, even after being left for 20 minutes in an environment of 25° C. and 65% RH. Next, when the transparent cover was removed from the water-discoloring sheet, the water-discoloring image gradually disappeared as the water evaporated, and after 10 minutes the image was completely decolorized and returned to its original state. This phenomenon could be repeated many times. Furthermore, since the transparent cover member is flexible, the water-color changing body can be rolled up and carried around, and therefore has excellent portability.

[0023] Example 5 Preparation of hydrochromic bodies A water-discolored sheet was obtained in the same manner as in Example 2. Next, a transparent polyester sheet having a thickness of 50 μm and dimensions of 265 mm x 365 mm was used as a transparent substrate, and 48 convex portions made of white polyurethane resin with a diameter of 15 mm, a height of 7.0 mm, and a curved hemispherical shape with a tip were arranged in a checkerboard pattern at equal intervals of 35 mm to obtain a transparent cover member. The surface area (s) of the convex portion visible from the top surface of the transparent cover member is 176.63 mm 2 The height (h) of the convex portion was 7.0 mm, and the surface area (s) of the convex portion / height (h) of the convex portion was 25.23. The surface area of ​​the upper surface of the transparent cover member is 967.25 cm 2 The area of ​​the protrusions visible from the top surface of the transparent cover member is 84.78 cm 2 The ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 8.77%, and the ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 100 cm 2 The number of hit protrusions was 4.96. A water-coloring body comprising the water-coloring sheet and the transparent cover member was obtained.

[0024] The water-discolored sheet was normally white, but when a writing brush with a tip dipped in water was used to write on the porous layer, a black water-discolored image was formed. The water-discolored image was maintained for 5 minutes in an environment of 25°C and 65% RH, but gradually disappeared as the water evaporated, and after 10 minutes the sheet returned to its white state. This phenomenon could be repeated many times. Next, a water-discoloring image was formed on the water-discoloring sheet by writing with a brush whose tip was dipped in water, and the transparent cover member was placed on the water-discoloring sheet on which the water-discoloring image had been formed so that the tip of the convex portion was in contact with the surface of the water-discoloring sheet. The water-discolored image was clearly visible through the transparent cover member, and the convex portions prevented the transparent cover member from coming into contact with the water-discolored image, thereby enabling the water-discolored image to be maintained clearly. Furthermore, the water-discolored image maintained the same shape as the water-discolored image immediately after writing, even after being left for 15 minutes in an environment of 25° C. and 65% RH. Next, when the transparent cover was removed from the water-discoloring sheet, the water-discoloring image gradually disappeared as the water evaporated, and after 10 minutes the image was completely decolorized and returned to its original state. This phenomenon could be repeated many times. Furthermore, since the transparent cover member is flexible, the water-color changing body can be rolled up and carried around, and therefore has excellent portability.

[0025] Example 6 Preparation of hydrochromic bodies A water-discolored sheet was obtained in the same manner as in Example 2. Next, a transparent polyester sheet having a thickness of 50 μm and dimensions of 265 mm x 365 mm was used as a transparent substrate. On the underside of the sheet, 48 convex portions made of white polyurethane resin, each 15 mm in diameter and 10.0 mm in height and with a curved hemispherical tip, were arranged in a checkerboard pattern at equal intervals of 35 mm to obtain a transparent cover member. The surface area (s) of the convex portion visible from the top surface of the transparent cover member is 176.63 mm 2 The height (h) of the convex portion was 10.0 mm, and the surface area (s) of the convex portion / height (h) of the convex portion was 17.66. The surface area of ​​the upper surface of the transparent cover member is 967.25 cm 2 The area of ​​the protrusions visible from the top surface of the transparent cover member is 84.78 cm 2 The ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 8.77%, and the ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 100 cm 2The number of hit protrusions was 4.96. A water-coloring body comprising the water-coloring sheet and the transparent cover member was obtained.

[0026] The water-discolored sheet was normally white, but when a writing brush with a tip dipped in water was used to write on the porous layer, a black water-discolored image was formed. The water-discolored image was maintained for 5 minutes in an environment of 25°C and 65% RH, but gradually disappeared as the water evaporated, and after 10 minutes the sheet returned to its white state. This phenomenon could be repeated many times. Next, a water-discoloring image was formed on the water-discoloring sheet by writing with a brush whose tip was dipped in water, and the transparent cover member was placed on the water-discoloring sheet on which the water-discoloring image had been formed so that the tip of the convex portion was in contact with the surface of the water-discoloring sheet. The water-discolored image was clearly visible through the transparent cover member, and the convex portions prevented the transparent cover member from coming into contact with the water-discolored image, thereby enabling the water-discolored image to be maintained clearly. Furthermore, the water-discolored image maintained the same shape as the water-discolored image immediately after writing, even after being left for 10 minutes in an environment of 25° C. and 65% RH. Next, when the transparent cover is removed from the water-discoloring sheet, the water-discoloring image gradually disappears as the water evaporates, and after 10 minutes the image is completely decolorized and returns to its original state. This phenomenon can be repeated many times. Furthermore, since the transparent cover member is flexible, the water-color changing body can be rolled up and carried around, and therefore has excellent portability.

[0027] Example 7 Preparation of hydrochromic bodies A water-discolored sheet was obtained in the same manner as in Example 2. Next, a transparent polyester sheet having a thickness of 50 μm and dimensions of 265 mm x 365 mm was used as a transparent substrate. On the underside of the sheet, 48 convex portions made of white polyurethane resin, each 15 mm in diameter and 0.5 mm in height and with a curved hemispherical tip, were arranged in a checkerboard pattern at equal intervals of 35 mm to obtain a transparent cover member. The surface area (s) of the convex portion visible from the top surface of the transparent cover member is 176.63 mm 2 The height (h) of the convex portion was 0.5 mm, and the surface area (s) of the convex portion / height (h) of the convex portion was 353.33. The surface area of ​​the upper surface of the transparent cover member is 967.25 cm 2 The area of ​​the protrusions visible from the top surface of the transparent cover member is 84.78 cm 2 The ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 8.77%, and the ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 100 cm 2 The number of hit protrusions was 4.96. A transparent cover member was attached to one end of the water-discoloring sheet, and the other end was left as a free end to obtain a water-discoloring body.

[0028] The water-discolored sheet was normally white, but when a writing brush with a tip dipped in water was used to write on the porous layer, a black water-discolored image was formed. The water-discolored image was maintained for 5 minutes in an environment of 25°C and 65% RH, but gradually disappeared as the water evaporated, and after 10 minutes the sheet returned to its white state. This phenomenon could be repeated many times. Next, a water-discoloring image was formed on the water-discoloring sheet by writing with a brush whose tip was dipped in water, and the transparent cover member was placed on the water-discoloring sheet on which the water-discoloring image had been formed so that the tip of the convex portion was in contact with the surface of the water-discoloring sheet. The water-discolored image was clearly visible through the transparent cover member, and the convex portions prevented the transparent cover member from coming into contact with the water-discolored image, thereby enabling the water-discolored image to be maintained clearly. Furthermore, the water discoloration image maintained the same shape as the water discoloration image immediately after writing, even after being left for 30 minutes in an environment of 25° C. and 65% RH. Next, when the transparent cover is removed from the water-discoloring sheet, the water-discoloring image gradually disappears as the water evaporates, and after 10 minutes the image is completely decolorized and returns to its original state. This phenomenon can be repeated many times. Furthermore, since the transparent cover member is flexible, the water-color changing body can be rolled up and carried around, and therefore has excellent portability.

[0029] Example 8 Preparation of hydrochromic bodies A water-discolored sheet was obtained in the same manner as in Example 2. Next, 48 convex portions made of white soft SEBS resin with a diameter of 5 mm, a height of 10.0 mm and a curved tip were arranged in a grid pattern at equal intervals of 45 mm on the underside of a flexible polyester transparent sheet having a thickness of 50 μm and dimensions of 255 mm x 355 mm as a transparent substrate, to obtain a transparent cover member. The surface area (s) of the convex portion visible from the top surface of the transparent cover member is 19.63 mm 2 The height (h) of the convex portion was 10.0 mm, and the surface area (s) of the convex portion / height (h) of the convex portion was 1.96. The surface area of ​​the upper surface of the transparent cover member is 905.25 cm 2 The area of ​​the protrusions visible from the top surface of the transparent cover member is 9.42 cm 2 The ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 1.04%, and the ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 1.04%. 2 The number of hit protrusions was 5.30. A transparent cover member was attached to one end of the water-discoloring sheet, and the other end was left as a free end to obtain a water-discoloring body.

[0030] The water-discolored sheet was normally white, but when a writing brush with a tip dipped in water was used to write on the porous layer, a black water-discolored image was formed. The water-discolored image was maintained for 5 minutes in an environment of 25°C and 65% RH, but gradually disappeared as the water evaporated, and after 10 minutes the sheet returned to its white state. This phenomenon could be repeated many times. Next, a water-discoloring image was formed on the water-discoloring sheet by writing with a brush whose tip was dipped in water, and the transparent cover member was placed on the water-discoloring sheet on which the water-discoloring image had been formed so that the tip of the convex portion was in contact with the surface of the water-discoloring sheet. The water-discolored image was clearly visible through the transparent cover member, and the convex portions prevented the transparent cover member from coming into contact with the water-discolored image, thereby enabling the water-discolored image to be maintained clearly. Furthermore, the water-discolored image maintained the same shape as the water-discolored image immediately after writing, even after being left for 10 minutes in an environment of 25° C. and 65% RH. Next, when the transparent cover is removed from the water-discoloring sheet, the water-discoloring image gradually disappears as the water evaporates, and after 10 minutes the image is completely decolorized and returns to its original state. This phenomenon can be repeated many times. Furthermore, since the transparent cover member is flexible, the water-color changing body can be rolled up and carried around, and therefore has excellent portability.

[0031] Example 9 Weight is 130g / m 2 A porous layer was formed on a support made of red polyester satin fabric by solid printing using a white screen printing ink prepared by uniformly mixing and stirring 15 parts of particulate silica produced by a wet process (trade name: Nipsil E-200A, manufactured by Nippon Silica Kogyo Co., Ltd.), 50 parts of an aqueous urethane resin as a binder resin (trade name: Hydran AP-10, polyester-based urethane resin, solids content 30 wt%, manufactured by Dainippon Ink and Chemicals, Inc.), 30 parts of water, 0.5 parts of a silicone-based antifoaming agent, 3 parts of an aqueous ink thickener, 1 part of ethylene glycol, and 2 parts of an epoxy-based crosslinking agent, to obtain a water-discoloring sheet measuring 310 mm x 410 mm. Next, a transparent sheet made of flexible soft PVC, 200 μm thick and 310 mm x 410 mm in size, was used as a transparent substrate. 63 convex portions made of transparent soft PVC resin, each 10 mm in diameter and 3.0 mm in height with a curved hemispherical tip, were provided at intervals of 40 mm on the underside of the sheet to obtain a transparent cover member. The surface area (s) of the convex portion visible from the top surface of the transparent cover member is 78.5 mm 2 The height (h) of the convex portion was 3.0 mm, and the surface area (s) of the convex portion / height (h) of the convex portion was 26.17. The surface area of ​​the upper surface of the transparent cover member is 1271 cm2 The area of ​​the protrusions visible from the top surface of the transparent cover member is 49.46 cm 2 The ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 3.9%, and the ratio is 100 cm 2 The number of hit protrusions was 4.95. A transparent cover member was attached to one end of the water-discoloring sheet, and the other end was left as a free end to obtain a water-discoloring body.

[0032] The water-discoloring sheet was normally white, but when writing was done on the porous layer with a writing brush containing water in the tip, a red water-discoloring image was formed. The water-discolored image was maintained for 3 minutes in an environment of 25°C and 65% RH, but gradually disappeared as the water evaporated, and after 10 minutes the sheet returned to its white state. This phenomenon could be repeated many times. Next, a water-discoloring image was formed on the water-discoloring sheet by writing with a writing brush containing water in the tip, and the transparent cover member was placed on the water-discoloring sheet on which the water-discoloring image had been formed so that the tip of the convex portion was in contact with the surface of the water-discoloring sheet. The water-discolored image was clearly visible through the transparent cover member, and the convex portions prevented the transparent cover member from coming into contact with the water-discolored image, thereby enabling the water-discolored image to be maintained clearly. Furthermore, the water discoloration image maintained the same shape as the water discoloration image immediately after writing, even after being left for 20 minutes in an environment of 25° C. and 65% RH. Next, when the transparent cover is removed from the water-discoloring sheet, the water-discoloring image gradually disappears as the water evaporates, and after 10 minutes the image is completely decolorized and returns to its original state. This phenomenon can be repeated many times. Furthermore, since the transparent cover member is flexible, the water-color changing body can be rolled up and carried around, and therefore has excellent portability.

[0033] Example 10 Preparation of hydrochromic bodies A water-discolored sheet was obtained in the same manner as in Example 2. Next, 48 convex portions made of white polyurethane resin, each 3 mm in diameter and 0.4 mm in height and with a curved hemispherical tip, were arranged in a checkerboard pattern at equal intervals of 47 mm on the underside of a flexible polyester transparent sheet 50 μm thick and 253 mm x 353 mm in size as a transparent substrate, to obtain a transparent cover member. The surface area (s) of the convex portion visible from the top surface of the transparent cover member is 7.07 mm 2 The height (h) of the convex portion was 0.4 mm, and the surface area (s) of the convex portion / height (h) of the convex portion was 17.68. The surface area of ​​the upper surface of the transparent cover member is 893.09 cm 2 The area of ​​the protrusions visible from the top surface of the transparent cover member is 3.39 cm 2 The ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 0.38%, and the ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 100 cm 2 The number of hit protrusions was 5.37. A transparent cover member was attached to one end of the water-discoloring sheet, and the other end was left as a free end to obtain a water-discoloring body.

[0034] The water-discolored sheet was normally white, but when a writing brush with a tip dipped in water was used to write on the porous layer, a black water-discolored image was formed. The water-discolored image was maintained for 5 minutes in an environment of 25°C and 65% RH, but gradually disappeared as the water evaporated, and after 10 minutes the sheet returned to its white state. This phenomenon could be repeated many times. Next, a water-discoloring image was formed on the water-discoloring sheet by writing with a brush whose tip was dipped in water, and the transparent cover member was placed on the water-discoloring sheet on which the water-discoloring image had been formed so that the tip of the convex portion was in contact with the surface of the water-discoloring sheet. The water-discolored image was clearly visible through the transparent cover member. Although a portion of the water-discolored image came into contact with the transparent cover member and caused slight bleeding, this did not pose a practical problem and the clear water-discolored image was maintained. Furthermore, the water discoloration image maintained the same shape as the water discoloration image immediately after writing, even after being left for 30 minutes in an environment of 25° C. and 65% RH. Next, when the transparent cover was removed from the water-discoloring sheet, the water-discoloring image gradually disappeared as the water evaporated, and after 10 minutes the image was completely decolorized and returned to its original state. This phenomenon could be repeated many times. Furthermore, since the transparent cover member is flexible, the water-color changing body can be rolled up and carried around, and therefore has excellent portability.

[0035] Example 11 Preparation of hydrochromic bodies A water-discolored sheet was obtained in the same manner as in Example 2. Next, a transparent polyester sheet having a thickness of 50 μm and dimensions of 265 mm x 365 mm was used as a transparent substrate. On the underside of the sheet, 48 conical protrusions made of white polyurethane resin with a diameter of 15 mm and a height of 12.0 mm and a curved tip were arranged in a checkerboard pattern at equal intervals of 35 mm to obtain a transparent cover member. The surface area (s) of the convex portion visible from the top surface of the transparent cover member is 176.63 mm 2 The height (h) of the convex portion was 12.0 mm, and the surface area (s) of the convex portion / height (h) of the convex portion was 14.72. The surface area of ​​the upper surface of the transparent cover member is 967.25 cm 2 The area of ​​the protrusions visible from the top surface of the transparent cover member is 84.78 cm 2 The ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 8.77%, and the ratio of the area occupied by the convex portions visible from the top surface of the transparent cover member to the surface area of ​​the top surface of the transparent cover member is 100 cm 2 The number of hit protrusions was 4.96. A water-coloring body comprising the water-coloring sheet and the transparent cover member was obtained.

[0036] The water-discolored sheet was normally white, but when a writing brush with a tip dipped in water was used to write on the porous layer, a black water-discolored image was formed. The water-discolored image was maintained for 5 minutes in an environment of 25°C and 65% RH, but gradually disappeared as the water evaporated, and after 10 minutes the sheet returned to its white state. This phenomenon could be repeated many times. Next, a water-discoloring image was formed on the water-discoloring sheet by writing with a brush whose tip was dipped in water, and the transparent cover member was placed on the water-discoloring sheet on which the water-discoloring image had been formed so that the tip of the convex portion was in contact with the surface of the water-discoloring sheet. The water-discolored image was clearly visible through the transparent cover member, and the convex portions prevented the transparent cover member from coming into contact with the water-discolored image, thereby enabling the water-discolored image to be maintained clearly. Furthermore, the water-discolored image remained for 7 minutes in an environment of 25°C and 65% RH, but gradually disappeared as the water evaporated, and after 15 minutes the entire sheet returned to a white water-discolored sheet. This phenomenon can be repeated many times. Furthermore, since the transparent cover member is flexible, the water-color changing body can be rolled up and carried around, and therefore has excellent portability.

[0037] Example 12 Preparation of the hydrochromic body set (see Figure 4) A water-coloring product set 9 was obtained by combining the water-coloring product 1 of Example 1 with a water-applying tool 8 (a writing element containing water). The water-discoloring body set can form a water-discoloring image on the water-discoloring sheet using a water-adhering tool, and by placing a transparent cover member on it as in Example 1, the water-discoloring image can be clearly seen through the transparent cover member, and the convex portion prevents the transparent cover member from coming into contact with the water-discoloring image, allowing the clear water-discoloring image to be maintained for a long time. Furthermore, each of the water-coloring products of Examples 2 to 11 was combined with a water-adhering tool (a writing tool containing water) to obtain a water-coloring product set. The water-discoloring body set can be used to form a water-discoloring image on the water-discoloring sheet using a water-adhering tool, and by placing a transparent cover member on it as in Examples 2 to 11, the water-discoloring image can be clearly seen through the transparent cover member, and the convex portion prevents the transparent cover member from coming into contact with the water-discoloring image, allowing the clear water-discoloring image to be maintained for a long time.

[0038] Example 13 Preparation of hydrochromic bodies A colored layer was formed on a support made of white synthetic paper by screen printing using a 180-mesh screen stencil, using a screen printing ink prepared by uniformly mixing and stirring 5 parts of blue pigment, 50 parts of acrylic ester emulsion (solids content 50% by weight), 0.2 parts of silicone antifoaming agent, 3 parts of thickener, 2 parts of wetting agent, 1 part of leveling agent, 10 parts of water, and 2.5 parts of epoxy crosslinking agent. Next, on the colored layer, 15 parts of finely divided silica produced by a wet process (trade name: Nipsil E-200A, manufactured by Nippon Silica Kogyo Co., Ltd.), 50 parts of an aqueous urethane resin as a binder resin (trade name: Hydran AP-10, polyester-based urethane resin, solid content 30% by weight, manufactured by Dainippon Ink and Chemicals, Inc.), 30 parts of water, 0.5 parts of a silicone-based antifoaming agent, 3 parts of an aqueous ink thickener, 1 part of ethylene glycol, and 2 parts of an epoxy-based crosslinking agent were uniformly mixed and stirred to form a white screen printing ink, which was then solid-printed over the entire surface to form a porous layer, yielding a water-discoloring sheet measuring 220 mm x 320 mm. Next, a transparent cover member was obtained by providing three convex portions made of transparent acrylonitrile resin, each having a diameter of 10 mm and a height of 1.0 mm, at positions corresponding to the vertices of an isosceles triangle, on the underside of a plate-shaped molded article made of transparent rigid acrylonitrile resin, which had a transparent substrate having a thickness of 1.0 mm, a size of 200 mm x 300 mm, and an upper surface with fine irregularities and non-glossiness. The surface area (s) of the convex portion visible from the top surface of the transparent cover member is 78.5 mm 2 The height (h) of the convex portion was 1.0 mm, and the surface area (s) of the convex portion / height (h) of the convex portion was 78.5. The surface area of ​​the upper surface of the transparent cover member is 600 cm2 The area of ​​the protrusions visible from the top surface of the transparent cover member is 2.36 cm 2 The ratio of the area occupied by the convex portions visible from the upper surface of the transparent cover member to the surface area of ​​the upper surface of the transparent cover member was 0.39%. A water-coloring body comprising the water-coloring sheet and the transparent cover member was obtained.

[0039] The water-discoloring sheet was normally white, but when a writing tool containing water was used to write on the porous layer, a blue water-discoloring image was formed. The water-discolored image was maintained for 5 minutes in an environment of 25°C and 65% RH, but gradually disappeared as the water evaporated, and after 10 minutes the sheet returned to its white state. This phenomenon could be repeated many times. Next, a water-discolored image was formed on the water-discolored sheet by writing with a writing pen containing water, and the transparent cover member was placed on the water-discolored sheet on which the water-discolored image had been formed so that the tips of the convex portions were in contact with the surface of the water-discolored sheet. The water-discolored image could be seen more clearly through the transparent cover member without light being reflected on the surface of the transparent cover member to hinder visibility, and the convex portions prevented the transparent cover member from coming into contact with the water-discolored image, allowing the clear water-discolored image to be maintained. Furthermore, when a photograph was taken indoors with the transparent cover member in place, the lighting fixture was not reflected in the photograph, and a clear image of the discolored water was captured. Furthermore, the water discoloration image maintained the same shape as the water discoloration image immediately after writing, even after being left for 30 minutes in an environment of 25° C. and 65% RH. Next, when the transparent cover was removed from the water-discoloring sheet, the water-discoloring image gradually disappeared as the water evaporated, and after 10 minutes the image was completely decolorized and returned to its original state. This phenomenon could be repeated many times.

[0040] Example 14 Preparation of hydrochromic bodies A colored layer was formed on a support made of white synthetic paper by screen printing using a 180-mesh screen stencil, using a screen printing ink prepared by uniformly mixing and stirring 5 parts of blue pigment, 50 parts of acrylic ester emulsion (solids content 50% by weight), 0.2 parts of silicone antifoaming agent, 3 parts of thickener, 2 parts of wetting agent, 1 part of leveling agent, 10 parts of water, and 2.5 parts of epoxy crosslinking agent. Next, on the colored layer, 15 parts of finely divided silica produced by a wet process (trade name: Nipsil E-200A, manufactured by Nippon Silica Kogyo Co., Ltd.), 50 parts of an aqueous urethane resin as a binder resin (trade name: Hydran AP-10, polyester-based urethane resin, solid content 30% by weight, manufactured by Dainippon Ink and Chemicals, Inc.), 30 parts of water, 0.5 parts of a silicone-based antifoaming agent, 3 parts of an aqueous ink thickener, 1 part of ethylene glycol, and 2 parts of an epoxy-based crosslinking agent were uniformly mixed and stirred to form a white screen printing ink, which was then solid-printed over the entire surface to form a porous layer, and three water-discoloring sheets measuring 220 mm x 320 mm were obtained. Next, three convex portions made of transparent ABS resin with a diameter of 10 mm and a height of 1.0 mm and a curved tip, each made of a cone-shaped transparent ABS resin, were provided on the underside of a plate-shaped molded article made of transparent hard ABS resin with a thickness of 1.0 mm and dimensions of 200 mm x 300 mm as a transparent substrate, at positions corresponding to the vertices of an isosceles triangle, to obtain transparent cover members (2 sheets). The surface area (s) of the convex portion visible from the top surface of the transparent cover member is 78.5 mm 2 The height (h) of the convex portion was 1.0 mm, and the surface area (s) of the convex portion / height (h) of the convex portion was 78.5. The surface area of ​​the upper surface of the transparent cover member is 600 cm 2 The area of ​​the protrusions visible from the top surface of the transparent cover member is 2.36 cm 2 The ratio of the area occupied by the convex portions visible from the upper surface of the transparent cover member to the surface area of ​​the upper surface of the transparent cover member was 0.39%. A water-coloring body comprising the water-coloring sheets (3 sheets) and the transparent cover members (2 sheets) was obtained.

[0041] The water-discoloring sheet was normally white, but when a writing tool containing water was used to write on the porous layer, a blue water-discoloring image was formed. The water-discolored image was maintained for 5 minutes in an environment of 25°C and 65% RH, but gradually disappeared as the water evaporated, and after 10 minutes the sheet returned to its white state. This phenomenon could be repeated many times. Next, a water-discolored image was formed on the water-discolored sheet by writing with a writing pen containing water, and the transparent cover member was placed on the water-discolored sheet on which the water-discolored image had been formed so that the tips of the convex portions were in contact with the surface of the water-discolored sheet. The water-discolored image was clearly visible through the transparent cover member, and the convex portions prevented the transparent cover member from coming into contact with the water-discolored image, thereby enabling the water-discolored image to be maintained clearly. Furthermore, the water discoloration image maintained the same shape as the water discoloration image immediately after writing, even after being left for 30 minutes in an environment of 25° C. and 65% RH. Next, when the transparent cover was removed from the water-discoloring sheet, the water-discoloring image gradually disappeared as the water evaporated, and after 10 minutes the image was completely decolorized and returned to its original state. This phenomenon could be repeated many times. Furthermore, after removing the transparent cover member from the water-discoloring sheet, a water-discoloring image was formed on another water-discoloring sheet and the transparent cover member was placed on it before the sheet completely faded and returned to its original state, thereby enabling rapid image formation.

[0042] Example 15 Preparation of hydrochromic bodies A colored layer was formed on a support made of white synthetic paper by screen printing using a 180-mesh screen stencil, using a screen printing ink prepared by uniformly mixing and stirring 5 parts of blue pigment, 50 parts of acrylic ester emulsion (solids content 50% by weight), 0.2 parts of silicone antifoaming agent, 3 parts of thickener, 2 parts of wetting agent, 1 part of leveling agent, 10 parts of water, and 2.5 parts of epoxy crosslinking agent. Next, on the colored layer, 15 parts of finely divided silica produced by a wet process (trade name: Nipsil E-200A, manufactured by Nippon Silica Kogyo Co., Ltd.), 50 parts of an aqueous urethane resin as a binder resin (trade name: Hydran AP-10, polyester-based urethane resin, solid content 30% by weight, manufactured by Dainippon Ink and Chemicals, Inc.), 30 parts of water, 0.5 parts of a silicone-based antifoaming agent, 3 parts of an aqueous ink thickener, 1 part of ethylene glycol, and 2 parts of an epoxy-based crosslinking agent were uniformly mixed and stirred to form a white screen printing ink, which was then solid-printed over the entire surface to form a porous layer, yielding a water-discoloring sheet measuring 220 mm x 320 mm. Separately, a water-discoloring sheet was obtained in which a letter frame was formed on the porous layer using a non-discoloring black ink, and a water-discoloring sheet in which a model consisting of the outline of a letter was formed on the porous layer using a non-discoloring black ink. Next, three convex portions made of transparent ABS resin with a diameter of 10 mm and a height of 1.0 mm and a curved tip, each made of a cone-shaped transparent ABS resin, were provided on the underside of a plate-shaped molded article made of transparent hard ABS resin with a thickness of 1.0 mm and dimensions of 200 mm x 300 mm as a transparent substrate, at positions corresponding to the vertices of an isosceles triangle, to obtain transparent cover members (3 pieces). The surface area (s) of the convex portion visible from the top surface of the transparent cover member is 78.5 mm 2 The height (h) of the convex portion was 1.0 mm, and the surface area (s) of the convex portion / height (h) of the convex portion was 78.5. The surface area of ​​the upper surface of the transparent cover member is 600 cm 2 The area of ​​the protrusions visible from the top surface of the transparent cover member is 2.36 cm 2 The ratio of the area occupied by the convex portions visible from the upper surface of the transparent cover member to the surface area of ​​the upper surface of the transparent cover member was 0.39%. A water-coloring body comprising the water-coloring sheets (3 sheets) and the transparent cover members (3 sheets) was obtained.

[0043] The water-discoloring sheet is normally white, but when a specific character is written on the porous layer with a character frame and a character outline formed using a cursive writing tool containing water, a blue water-discoloring image is formed. The water-discolored image was maintained for 5 minutes in an environment of 25°C and 65% RH, but gradually disappeared as the water evaporated, and after 10 minutes the sheet returned to its white state. This phenomenon could be repeated many times. Next, a water-discolored image was formed on the water-discolored sheet by writing with a writing pen containing water, and the transparent cover member was placed on the water-discolored sheet on which the water-discolored image had been formed so that the tips of the convex portions were in contact with the surface of the water-discolored sheet. The water-discolored image was clearly visible through the transparent cover member, and the convex portions prevented the transparent cover member from coming into contact with the water-discolored image, thereby enabling the water-discolored image to be maintained clearly. Furthermore, the water discoloration image maintained the same shape as the water discoloration image immediately after writing, even after being left for 30 minutes in an environment of 25° C. and 65% RH. Next, when the transparent cover was removed from the water-discoloring sheet, the water-discoloring image gradually disappeared as the water evaporated, and after 10 minutes the image was completely decolorized and returned to its original state. This phenomenon could be repeated many times. Furthermore, after removing the transparent cover member from the water-discoloring sheet, a water-discoloring image was formed on another water-discoloring sheet and the transparent cover member was placed on it before the sheet completely faded and returned to its original state, thereby enabling rapid image formation. Furthermore, by combining the water-discoloring body with an erasable writing implement (whiteboard marker), it was possible to write on the surface of the transparent cover member with the whiteboard marker to point out and grade the unskilled areas of the water-discoloring image. In addition, the marker marks could be easily removed by rubbing the surface of the transparent cover member with a dry cloth or whiteboard eraser.

[0044] Comparative Example 1 Preparation of hydrochromic bodies A water-discoloring sheet was obtained in the same manner as in Example 1. Next, a transparent cover member was obtained by providing two conical convex portions made of transparent ABS resin with a diameter of 10 mm and a height of 1.0 mm and a curved tip on the underside of a plate-shaped molded object made of transparent hard ABS resin with a thickness of 1.0 mm and dimensions of 200 mm x 300 mm as a transparent substrate. The surface area (s) of the convex portion visible from the top surface of the transparent cover member is 78.5 mm 2 The height (h) of the convex portion was 1.0 mm, and the surface area (s) of the convex portion / height (h) of the convex portion was 78.5. The surface area of ​​the upper surface of the transparent cover member is 600 cm 2 The area of ​​the protrusions visible from the top surface of the transparent cover member is 2.36 cm 2 The ratio of the area occupied by the convex portions visible from the upper surface of the transparent cover member to the surface area of ​​the upper surface of the transparent cover member was 0.39%. A water-coloring body comprising the water-coloring sheet and the transparent cover member was obtained.

[0045] The water-discoloring sheet was normally white, but when a writing tool containing water was used to write on the porous layer, a blue water-discoloring image was formed. The water-discolored image was maintained for 5 minutes in an environment of 25°C and 65% RH, but gradually disappeared as the water evaporated, and after 10 minutes the sheet returned to its white state. This phenomenon could be repeated many times. Next, a water-discolored image was formed on the water-discolored sheet by writing with a writing pen containing water, and the transparent cover member was placed on the water-discolored sheet on which the water-discolored image had been formed so that the tips of the convex portions were in contact with the surface of the water-discolored sheet. The water-discolored image could be seen through the transparent cover member, but there were some areas where the transparent cover member and the water-discolored image came into contact with each other, causing bleeding of the water-discolored image. Furthermore, when the water-discolored image was left in an environment of 25°C and 65% RH, differences occurred in the distance between the transparent cover member and the water-discolored image, which resulted in differences in the time it took for the water-discolored image to fade, making it impossible to maintain a uniform water-discolored image. [Explanation of symbols]

[0046] 1 Water discoloration 2. Discoloration sheet 3 Support 4 Colored layer 5 Porous layer 6 Transparent cover member 7 Transparent base material 8 Convex part 9 Water adhesion tool 10 Water-Colored Body Set

Claims

1. The water-discoloring body comprises a water-discoloring sheet having, as an upper layer of a colored layer, a porous layer in which a low-refractive index pigment is dispersed and fixed in a binder resin, and a transparent cover member that covers a water-discoloring image formed on the surface of the porous layer by adhesion of water, suppressing drying of the water and delaying disappearance of the water-discoloring image, and the underside of the transparent cover member has at least three or more dot-like protrusions that contact the surface of the water-discoloring sheet and maintain a non-contact state between the surface of the water-discoloring sheet and the transparent cover member, and are arranged in a non-linear pattern, the protrusions having a height of 0.4 mm to 12.0 mm, the surface area (s) of the protrusions visible from the top surface of the transparent cover member and the height (h) of the protrusions satisfy the following formula (1), and the area occupied by the protrusions visible from the top surface of the transparent cover member is 10% or less of the surface area of ​​the top surface of the transparent cover member. 1.0≦s / h≦400 (1)

2. A water-discoloring body as described in claim 1, wherein the dot-like protrusions are arranged in a checkerboard pattern.

3. A water-discoloring body as described in claim 1 or 2, wherein the convex portion is transparent.

4. A water-discoloring body as described in claim 1 or 2, wherein the convex portion is white.

5. A water-discoloring body described in any one of claims 1 to 4, wherein the tip of the convex portion has a curved shape.

6. A water-discoloring body according to any one of claims 1 to 5, wherein the transparent cover member is flexible and the number of the convex portions is three or more per 100 cm 2 .

7. A water-discoloring body described in any one of claims 1 to 6, wherein the surface of the transparent cover member is non-glossy.

8. A water-discoloring body described in any one of claims 1 to 7, wherein the transparent cover member has one end attached to the water-discoloring sheet and the other end as a free end, and is attached to the water-discoloring sheet so as to be able to be opened and closed freely.

9. A water-discoloring body described in any one of claims 1 to 7, comprising a plurality of the water-discoloring sheets and a plurality of the transparent cover members.

10. A water-discoloring body described in any one of claims 1 to 9, which has a letter frame or model letters provided on the porous layer of the water-discoloring sheet.

11. A water-discoloring body set comprising a water-discoloring body according to any one of claims 1 to 10 and a water-attaching device for forming a water-discoloring image.

Images