JP2014005329A - Reversible thermochromic display body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reversible thermochromic display body, capable of visually recognizing various phase changes according to the temperature difference.SOLUTION: A reversible thermochromic display body comprising a reversible thermochromic image containing a reversible thermochromic material A and a reversible thermochromic image containing a reversible thermochromic material B provided on a support. The reversible thermochromic materials A and B show hysteresis curves which starts color developing when reaching a color development starting temperature in a temperature-falling step from a color erased state in a color density-temperature curve, turns into a color development state completely when reaching a complete color development temperature, starts decolorization when reaching a color erasing starting temperature in a temperature-rising step from the color development state, and turns into a color erased state completely when reaching a completely color erasing temperature. The hysteresis curve of the reversible thermochromic material B indwells within the hysteresis curve of the reversible thermochromic material A.

Description

  The present invention relates to a reversible thermochromic display. More specifically, the present invention relates to a reversible thermochromic display capable of visually recognizing various changes in appearance due to temperature changes.

Conventionally, there is disclosed a thermochromic printed material in which a plurality of thermochromic images having different discoloration temperatures provided on a support are provided, and an image appears or disappears at each discoloration temperature due to a temperature change and a dynamic change can be visually recognized. (For example, refer to Patent Document 1).
Even if the thermochromic printed matter can visually recognize a change in appearance due to a change in temperature, when two thermochromic images are provided, three kinds of changes in the appearance are observed in the same manner at the time of temperature increase and at the time of temperature decrease. It is only visually recognized, and in order to visually recognize a further change in the appearance, another thermochromic image is newly required, which is troublesome.

Japanese Utility Model Publication No. 9-21099

  The present invention seeks to provide a display body that can visually recognize a change in appearance due to a change in temperature, and provides a reversible thermochromic display that can easily recognize a variety of changes in appearance.

In the present invention, a reversible thermochromic image including the reversible thermochromic material A and a reversible thermochromic image including the reversible thermochromic material B are provided on a support, and the reversible thermochromic materials A and B are provided. In the color density-temperature curve, color development starts when the color development start temperature is reached in the temperature-decreasing process from the color-erased state, and color development starts when the temperature reaches the complete color development temperature. Is a material that exhibits a hysteresis curve that begins to decolor when it reaches, and becomes completely decolored when it reaches a complete decolorization temperature. The hysteresis curve of reversible thermochromic material B is the hysteresis curve of reversible thermochromic material A. A reversible thermochromic display body inherent in the inside is required.
Further, the reversible thermochromic material A and the reversible thermochromic material B have different hues during color development, a reversible thermochromic image including the reversible thermochromic material A, and a reversible thermochromic material B including the reversible thermochromic material B. The thermochromic image is provided so that there are portions that overlap each other and portions that do not overlap each other, and includes a reversible thermochromic image including the reversible thermochromic material A and / or a reversible thermochromic material B. The reversible thermochromic image is required to contain a non-thermochromic colorant.

  The present invention provides a reversible thermochromic image containing the reversible thermochromic material A and a reversible thermochromic image containing the reversible thermochromic material B, and the hysteresis curve of the reversible thermochromic material B is a reversible thermochromic material. By being inherent in the hysteresis curve of the conductive material A, it is possible to provide a reversible thermochromic display capable of easily recognizing various changes in the appearance due to temperature changes.

The temperature-color density curve of the reversible thermochromic material A is shown. The temperature-color density curve of reversible thermochromic material B is shown. The temperature-color density curve of the reversible thermochromic material A and the reversible thermochromic material B (material A: thick line, material B: thin line) is shown.

The reversible thermochromic material A and the reversible thermochromic material B are obtained by (i) an electron donating color-forming organic compound, (b) an electron accepting compound, and (b) the electron transfer reaction of (b). (C) a reversible thermochromic pigment comprising resin granules containing a resin containing a reversible thermochromic composition comprising three components of an organic compound medium, and a microcapsule of the three components. And reversible thermochromic microcapsule pigments encapsulated in
The microcapsule pigment is a known microencapsulation method, for example, interfacial polymerization method, in situ polymerization method, in-liquid curing coating method, phase separation method from aqueous solution, phase separation method from organic solvent, melt dispersion cooling method, It can be obtained by applying an air suspension coating method, a spray drying method, or the like.
By using the reversible thermochromic composition in a microcapsule, the reversible thermochromic composition can be maintained in the same composition under various conditions of use, and can exhibit the same action and effect. And physically stable pigments.
The reversible thermochromic microcapsule pigment has a particle size of 0.1 to 30 μm, preferably 0.5 to 20 μm, more preferably 1 to 15 μm. It is effective in terms of processability.
Examples of the reversible thermochromic material A include Japanese Patent Publication No. 4-17154, Japanese Patent Application Laid-Open No. 7-33997, Japanese Patent Application Laid-Open No. 7-179777, Japanese Patent Application Laid-Open No. 8-39936,
Discoloration showing a large hysteresis width (ΔH _A ) described in JP 2005-1369 A, JP 2006-137886 A, JP 2006-188660 A, JP 2008-280523 A, etc. Reversible thermochromic material with color memory, that is, the shape of the curve plotting the change in color density due to temperature change is the color change temperature range contrary to the case where the temperature is raised from the lower temperature side than the color change temperature range more discolored follow very different paths as if going lowered from the high temperature side, T ₁ following a low temperature range or T ₄ or more materials the state of changing it tautomeric manner memory retention in a high temperature range is valid Yes (see FIG. 1).
The reversible thermochromic material B is described in Japanese Patent Publication No. 51-35414, Japanese Patent Publication No. 51-44706, Japanese Patent Publication No. 1-17154, Japanese Patent Laid-Open No. 7-186546, etc. proposed by the present applicant. A hysteresis width of 3 ° C. or less ( _A ), which is a thermochromic material having a relatively small hysteresis width (ΔH _B ) or a fatty acid ester exhibiting a ΔT value (melting point-cloud point) of 3 ° C. or less as a component (c) ( A highly sensitive reversible thermochromic material (Japanese Patent Publication No. 1-29398) that expresses ΔH _B ) can be mentioned (see FIG. 2). This type of reversible thermochromic material changes color before and after the color change temperature, and only one specific state can exist in the normal temperature range between both states before and after the color change. In other words, the other state is maintained while the heat or cold heat required to develop the state is applied, but when the heat or cold heat is no longer applied, the state returns to the original state exhibited in the normal temperature range. This is a thermochromic material.
As the reversible thermochromic material B, a material having a relatively small hysteresis width (ΔH _B ) is preferably used. However, the reversible thermochromic material B only needs to be included in the hysteresis curve of the reversible thermochromic material A. A material having a relatively large (ΔH _B ) can also be used.
The hysteresis characteristic in the color density-temperature curve of the reversible thermochromic material will be described with reference to the graph of FIG.
In FIG. 1, the vertical axis represents color density and the horizontal axis represents temperature. The change in color density due to the temperature change proceeds along the arrow. Here, A is a point indicating a density at a temperature T ₄ (hereinafter referred to as a complete decoloring temperature) that reaches a completely decolored state, and B is a temperature T ₃ (hereinafter referred to as a decoloring start temperature) at which decoloring starts. C is a point indicating a density at a temperature T ₂ at which color development starts (hereinafter referred to as a color development start temperature), and D is a temperature T ₁ (hereinafter referred to as a complete color development state). , Referred to as a complete color development temperature).
The length of the line segment EF is a scale indicating the discoloration contrast, and the length of the line segment HG is a temperature width indicating the degree of hysteresis (hereinafter referred to as hysteresis width ΔH). It is easy to maintain each state before and after the color change.
Here, the difference between T ₄ and T ₃ , or the difference between T ₂ and T ₁ is a scale indicating the sensitivity of discoloration.

  The present invention is a reversible thermochromic material A that changes color with a large hysteresis width, and has a hysteresis width smaller than the reversible thermochromic material A, and discolors inherent in the color change temperature region of the reversible thermochromic material A. And a reversible thermochromic image including the reversible thermochromic material A and a reversible thermochromic image including the reversible thermochromic material B on the support. Such a change in the appearance is visually recognized, and an unexpected change of color change, an exquisite taste of change of color, a multicolor change of color, and the like are to be effectively expressed.

Since the thermochromic materials A and B are both colored in the temperature range of T ₁ or lower, the images of the materials A and B are visually recognized. In the temperature range of t _{4 to} T ₃ due to temperature rise, the material B is decolored, since the material a maintains a colored state, is visually recognized image of only the material a, the T ₄ above temperature range, the image will not be visually recognized by the material a, B together decolorization. The temperature range of t ₁ through T ₂ lowering the temperature, only the material B is colored, to be seen the image of the material B is, each by further lowering the temperature, T ₁ following temperature range in again materials A, B The image is visible. As described above, the reversible thermochromic display of the present invention uses two reversible thermochromic materials, so that the discoloration aspect differs between when the temperature is increased and when the temperature is decreased, and four types of states (or aspects) can be visually recognized.
Each image of the materials A and B may be an image that changes to the same color using a material having the same hue at the time of color development, or an image that changes to a different color using a material having a different hue at the time of color development. It may be.
In addition, a non-thermochromic colorant can be mixed in the images of the materials A and B.
When the image by the material A is discolored to colored different color from the colored, the T ₁ following the temperature range, the thermochromic material A, B are both in the colored state, the material A, the image of B is visually recognized In the temperature range of t _{4 to} T _{3 due to} the temperature rise, the image of the material B is decolored and the material A maintains the colored state, so the image of the material A is visually recognized, and the temperature range of T ₄ or higher. Then, the image of the material A is in a discolored state. In the temperature range from t _{1 to} T _{2 when} the temperature is lowered, a state in which the image of the material B is colored (the image of the material A is discolored) is visually recognized, and the temperature is further lowered and again in the temperature range of T ₁ or less. Each image in a colored state by the materials A and B is visually recognized.
Further, if the image formed by the material B is discolored to colored different color from the colored, the T ₁ following the temperature range, the thermochromic material A, B are both in the colored state, the material A, the respective images of the B Since the image of the material B is discolored in the temperature range of t _{4 to} T _{3 due to} the temperature rise and the material A is in a colored state, the image of the material A and the image of the discolored material B are visible. is, in the T ₄ above temperature range, a state in which the image of the material a was decolored. In the temperature range from t _{1 to} T _{2 when} the temperature is lowered, the state where the image of the material B is discolored (the image of the material A is decolored) is visually recognized, and the temperature is further lowered, and in the temperature range below T ₁ Each image of the colored state by the materials A and B is visually recognized again.
Further, when the material A, the image formed by B is discolored to colored different from the color of the color, the T ₁ following the temperature range, the thermochromic material A, B are both in the colored state, the material A, the B Each image is visually recognized, and in the temperature range from t _{4 to} T ₃ due to temperature rise, the state in which the image of the material B is discolored (the state in which the image of the material A is not discolored) is visually recognized, and the temperature region is equal to or higher than T _4. Then, both the images of materials A and B are in a discolored state. In the temperature range from t _{1 to} T _{2 when} the temperature is lowered, a state in which the image of the material B is colored (the image of the material A is discolored) is visually recognized, and the temperature is further lowered and again in the temperature range of T ₁ or less. Each image in a colored state by the materials A and B is visually recognized.
Examples of the non-thermochromic colorant include known general dyes, general pigments, fluorescent pigments, metal powders, pearl pigments, white pigments such as titanium oxide, phosphorescent pigments, photochromic colorants, and the like. Used in it.

Further, by providing the reversible thermochromic image including the reversible thermochromic material A and the reversible thermochromic image including the reversible thermochromic material B so that there are portions that overlap each other and portions that do not overlap each other. It is possible to visually recognize complex and various changes in the appearance.
To explain this specifically,
The T ₁ following the temperature range, the thermochromic material A, B are both in the colored state, the material A, and the image of the portion not overlapping each other B, the material A, B is the image of mixed color overlapping each other visually In the temperature range of t _{4 to} T _{3 due to} the temperature rise, the material B is decolored and the material A is in a colored state. Therefore, the image of the material A is visually recognized, and in the temperature range of T ₄ or higher, The materials A and B are decolored and the image is not visually recognized. In the temperature range from t _{1 to} T _{2 when} the temperature is lowered, the material B develops color, so the image of the material B is visually recognized, and the temperature is further lowered, and in the temperature range below T ₁ , the materials A and B overlap each other again. An image of the mismatched portion and a mixed color image in which the materials A and B overlap each other are visually recognized.

In addition, by specifying the ΔH value of the reversible thermochromic material A in the range of 10 to 80 ° C., preferably 15 to 50 ° C., the color is developed or decolored by the living environment temperature or simple heat or cold means, and the color development The aspect due to the color change in the state or the decolored state can be stored and held interchangeably in the normal temperature range. If the ΔH value is less than 10 ° C, the color memory function is insufficient, and if it exceeds 80 ° C, the color memory function is fulfilled. However, depending on the living environment temperature or simple heat or cold means, a tautomatic color memory function is exhibited. It is difficult to let it.
On the other hand, the ΔH value of the reversible thermochromic material B is sensitive to temperature changes by specifying a range of 0.5 to 40 ° C., preferably 0.5 to 10 ° C., more preferably 0.5 to 5 ° C. sensitive to quickly return to the original color upon removal of the application of heat or cold required for the change, will be the color change is reversibly expressed in the region of the [Delta] H _a, area of the [Delta] H _a Various changes in the appearance are made visible by the relationship with the image of the thermochromic material A stored in the memory.

The reversible thermochromic materials A and B may be formed by blending 0.1 to 40% by mass, preferably 0.2 to 25% by mass, into a thermoplastic resin to form sheets or various forms of shaped articles. It is possible to form a reversible thermochromic image with the sheet or the modeled object, but for general purposes, the material is dispersed in a vehicle containing a binder resin and applied to various supports as paints or inks. Thus, a reversible thermochromic image can be easily formed and put to practical use.
Examples of coating methods include screen printing, offset printing, gravure printing, coater, tampo printing, transfer printing, and other means such as brush coating, spray coating, electrostatic coating, and electrodeposition coating. It is.

When the reversible thermochromic materials A and B are used as coloring materials for paints and inks, it is preferable to use a microcapsule pigment, and the reversible thermochromic image contains 5 to 60% by mass, preferably 10 to 50% by mass. This is effective in view of the thermal discoloration effect. If it is less than 5% by weight, the color density is low and the color change cannot be clearly seen. On the other hand, if it exceeds 60% by weight, the residual color is visible and it is difficult to visualize a clear decolored state.
The binder resin contained in the vehicle is preferably a transparent film-forming resin, and is exemplified below.
Ionomer resin, isoprene-maleic anhydride copolymer resin, acrylonitrile-acrylic styrene copolymer resin, acrylonitrile-styrene copolymer resin, acrylonitrile-butadiene-styrene copolymer resin, acrylonitrile chlorinated polyethylene-styrene copolymer resin, ethylene-vinyl chloride Copolymer resin, ethylene-vinyl acetate copolymer resin, ethylene-vinyl acetate-vinyl chloride graft copolymer resin, vinylidene chloride resin, vinyl chloride resin, chlorinated vinyl chloride resin, vinyl chloride-vinylidene chloride copolymer resin, chlorinated polyethylene Resin, chlorinated polypropylene resin, polyamide resin, high density polyethylene resin, medium density polyethylene resin, linear low density polyethylene resin, polyethylene terephthalate resin, polybutylene terephthalate tree , Polycarbonate resin, polystyrene resin, high impact polystyrene resin, polypropylene resin, polymethylstyrene resin, polyacrylate resin, polymethyl methacrylate resin, epoxy acrylate resin, alkylphenol resin, rosin modified phenolic resin, rosin modified alkyd resin, phenol modified Alkyd resin, epoxy-modified alkyd resin, styrene-modified alkyd resin, acrylic-modified alkyd resin, amino alkyd resin, vinyl chloride-vinyl acetate resin, styrene-butadiene resin, epoxy resin, unsaturated polyester resin, polyurethane resin, vinyl acetate emulsion resin , Styrene-butadiene emulsion resin, acrylic ester emulsion resin, water-soluble phenol resin, water-soluble epoxy resin, water Sex butadiene resins, cellulose acetate, nitrate cellulose, mention may be made of ethylcellulose, and the like.

As the support, all materials such as plastic, glass, metal, ceramics, cloth, paper, synthetic paper, leather, synthetic leather, wood and stone are effective.
The support may have a planar shape or a three-dimensional shape.
The support may be colored using the aforementioned non-thermochromic colorant.

Examples are described below. In addition, the part in an Example is a mass part.
The compositions of reversible thermochromic compositions 1 to 4 are shown in the following table. The numbers in parentheses in the table represent parts by mass.

Reversible thermochromic compositions 1 to 4 are encapsulated in a capsule wall film made of a cured product of aromatic polyisocyanate and aliphatic amine to prepare reversibly thermochromic microcapsule pigments 1 to 4 having an average particle size of 5 μm. did.
The following table shows the color change and the color change temperature of reversible thermochromic microcapsule pigments 1 to 4.

Example 1
5 parts of the reversible thermochromic microcapsule pigment 1 (T ₁ : 25 ° C., T ₂ : 27 ° C., T ₃ : 27 ° C., T ₄ : 29 ° C., changed from pink to colorless) into 95 parts of oil-based ink vehicle An oil-based spray ink was prepared by dispersing.
5 parts of the reversible thermochromic microcapsule pigment 2 (t ₁ : 20 ° C., t ₂ : 22 ° C., t ₃ : 31 ° C., t ₄ : 34 ° C., changed from green-blue to colorless) into 95 parts of oil-based ink vehicle An oil-based spray ink was prepared by dispersing.
A white plastic minicar as a support is spray-coated with an oil-based spray ink containing the reversible thermochromic microcapsule pigment 1, and the arrow pattern (reversible thermochromic is set so that the arrow heads from the rear to the front of the minicar. Image B) was formed.
The arrow tip of the reversible thermochromic image B is spray-coated with an oil-based spray ink containing the reversible thermochromic microcapsule pigment 2 so that the arrow tip overlaps, and the arrow tip is directed from the front to the rear of the minicar. A pattern (reversible thermochromic image A) was formed to obtain a reversible thermochromic display in the form of a minicar.

In the reversible thermochromic display, at a temperature of 20 ° C. or less, the front part of the minicar is pink by the reversible thermochromic image A, the rear part is green blue by the reversible thermochromic image B, and the two reversible thermochromic images are in the center. Overlapping purple double arrow images are visible. When heated from this state, the reversible thermochromic image B disappears at 29 ° C. or higher, and only the arrow of the green-blue reversible thermochromic image A is visible. When the temperature was further raised to 34 ° C. or higher, the reversible thermochromic image A was discolored and became a white minicar.
When cooled from this state, the reversible thermochromic image B developed at 25 ° C. or lower, and a pink arrow was visually recognized. When the temperature was further cooled to 20 ° C. or lower, the original state was restored.
The reversible thermochromic display showed four state changes with temperature change, and the color change behavior could be reproduced repeatedly.

Example 2
5 parts of the reversible thermochromic microcapsule pigment 2 (T ₁ : 20 ° C., T ₂ : 22 ° C., T ₃ : 31 ° C., T ₄ : 34 ° C., change from green to blue to colorless) into 95 parts of oil-based ink vehicle An oil-based spray ink was prepared by dispersing.
5 parts of the reversible thermochromic microcapsule pigment 3 (t ₁ : 13 ° C., t ₂ : 16 ° C., t ₃ : 38 ° C., t ₄ : 41 ° C., changed from pink to colorless) and non-thermochromic colorant [Yellow fluorescent pigment, trade name: Epocolor FP-117, manufactured by Nippon Shokubai Co., Ltd.] 0.5 parts were dispersed in 94.5 parts of an oil-based ink vehicle to prepare an oil-based spray ink.
A white plastic minicar as a support is spray-coated with an oil-based spray ink containing the reversible thermochromic microcapsule pigment 2 so that the color density gradually decreases from the front to the center of the minicar (gradient ) A reversible thermochromic image B was formed.
Next, spray coating is performed using an oil-based spray ink containing the reversible thermochromic microcapsule pigment 3 and a non-thermochromic colorant so that the color density gradually decreases from the rear to the center of the minicar (gradation). A reversible thermochromic image A was formed to obtain a reversible thermochromic display in the form of a minicar.
Note that the reversible thermochromic image B and the reversible thermochromic image A overlap at the center of the minicar.

In the reversible thermochromic display, the reversible thermochromic image B becomes green blue and the reversible thermochromic image A becomes red at a temperature of 13 ° C. or lower, so that the front part is green-blue from the front to the rear of the minicar. The appearance of a black gradation on the part and a red gradation on the last part was visually recognized.
When heated from this state, the reversible thermochromic image B is decolored at a temperature of 34 ° C. or higher, so that the green-blue and black colors of the minicar are decolored and further heated to a temperature of 41 ° C. or higher. Since the reversible thermochromic image A was discolored, the color changed from yellow to gray from the rear to the center.
When re-cooling from this state, the reversible thermochromic image B develops at 20 ° C. or lower, so that the front portion becomes a green-blue gradation and the central portion becomes a green gradation. Returned to.
The reversible thermochromic display showed four state changes with temperature change, and the color change behavior could be reproduced repeatedly.

Example 3
Water-based ink containing 25 parts of the above reversible thermochromic microcapsule pigment 1 (T ₁ : 25 ° C., T ₂ : 27 ° C., T ₃ : 27 ° C., T ₄ : 29 ° C., changed from pink to colorless) An aqueous screen ink was prepared by dispersing in 75 parts of a vehicle.
25 parts of the reversible thermochromic microcapsule pigment 4 (t ₁ : −12 ° C., t ₂ : −4 ° C., t ₃ : 50 ° C., t ₄ : 58 ° C., change from green blue to colorless) contains a binder resin A water-based screen ink was prepared by dispersing in 75 parts of a water-based ink vehicle.
Using a water-based screen ink containing the reversible thermochromic microcapsule pigment 1 on a white T-shirt (cotton) as a support, a large number of star patterns (reversible thermochromic image B were formed with a 100-mesh screen plate. Next, using a water-based screen ink containing the reversible thermochromic microcapsule pigment 4, a large number of star patterns (reversible thermochromic image A) are printed so as to overlap a part of the star pattern of the reversible thermochromic image B. Thus, a reversible thermochromic display in the form of a T-shirt was obtained.

In the reversible thermochromic display, the reversible thermochromic image A and the reversible thermochromic image B are colored at a temperature of −12 ° C. or lower, and are composed of a pink star pattern, a green blue star pattern, and a purple star pattern. Is visible. When heated from this state, at a temperature of 29 ° C. or higher, the reversible thermochromic image B is decolored and only a green-blue star pattern is visible. When further heated to a temperature of 58 ° C. or higher, the reversible thermochromic image A was discolored and became a plain white T-shirt.
When cooled again from this state, the reversible thermochromic image B developed at a temperature of 25 ° C. or lower, and a pink star pattern was visually recognized. When the temperature was further decreased to −12 ° C. or lower, the initial state was restored.
The reversible thermochromic display showed four state changes with temperature change, and the color change behavior could be reproduced repeatedly.
The reversible thermochromic display was cooled at a temperature of −12 ° C. or lower and then worn at room temperature (25 ° C.). As a result, the green-blue star pattern did not change and the pink star pattern did not appear on the body. Only the part warmed by contact was erased, and the purple star pattern changed to greenish blue only in the part warmed by contact with the body.
After the display body was heated to a temperature of 58 ° C. or higher to be in a plain state and left at room temperature (25 ° C.), only a pink star pattern was visible, but it was worn The pink star pattern on the part that was warmed in contact with the body disappeared.

Example 4
Reversible thermochromic microcapsule pigment 1 (T ₁ : 25 ° C., T ₂ : 27 ° C., T ₃ : 27 ° C., T ₄ : 29 ° C., changed from pink to colorless) 25 parts, non-thermochromic colorant [Aqueous dispersion of blue pigment, Sundai Super Blue GLL, pigment content of about 24% by weight, manufactured by Sanyo Dye Co., Ltd.] 0.3 part is uniformly dispersed in 74.7 parts of an aqueous ink vehicle containing a binder resin to form an aqueous screen An ink was prepared.
25 parts of the reversible thermochromic microcapsule pigment 3 (t ₁ : 13 ° C., t ₂ : 16 ° C., t ₃ : 38 ° C., t ₄ : 41 ° C., changed from pink to colorless) 25 parts of non-thermochromic coloring Agent [Aqueous dispersion of blue pigment, Sundai Super Blue GLL, pigment content of about 24% by weight, manufactured by Sanyo Dye Co., Ltd.] 0.3 parts is uniformly dispersed in 74.7 parts of a water-based ink vehicle containing an inder resin. A screen ink was prepared.
Using a water-based screen ink containing the reversible thermochromic microcapsule pigment 1 on the surface of white synthetic paper having a pressure-sensitive adhesive layer on the back as a support, a circle of 2 cm in diameter (reversible thermochromic image B ) Was printed. Next, a donut-shaped circle (reversible thermochromic image A) is screen-printed around the reversible thermochromic image B using an aqueous screen ink containing the reversible thermochromic microcapsule pigment 3, thereby reversibly thermochromic in a seal form. A sex indicator was obtained.

In the reversible thermochromic display, the reversible thermochromic image A and the reversible thermochromic image B become purple at a temperature of 13 ° C. or less, and the reversible thermochromic image B surrounds the reversible thermochromic image B. The aspect of was visually recognized. When heated from this state, the reversible thermochromic image B turns blue at 29 ° C. or higher, so that only the inner circle turns blue. When the temperature is further increased to 41 ° C. or higher, the reversible thermochromic image A changes to blue, so the outer donut-shaped circle also changes to blue, and the appearance of a blue double circle is visually recognized.
When cooled again from this state, the reversible thermochromic image B becomes purple at a temperature of 25 ° C. or lower, so that only the inner circle changes to purple, and when it reaches a temperature of 13 ° C. or lower, it returns to the initial state.
The reversible thermochromic display showed four state changes with temperature change, and the color change behavior could be reproduced repeatedly.
The bath toy with the display attached thereon could repeatedly show four types of discoloration states due to temperature changes such as tap water, hot water, and environmental temperature (25 ° C.).

T ₁ complete color development temperature T ₂ color development start temperature T ₃ color erase start temperature T ₄ complete color erase temperature t ₁ complete color development temperature t ₂ color development start temperature t ₃ color erase start temperature t ₄ complete color erase temperature

Claims (4)

  A reversible thermochromic image containing the reversible thermochromic material A and a reversible thermochromic image containing the reversible thermochromic material B are provided on a support, and the reversible thermochromic materials A and B have a color density of − In the temperature curve, color development starts when the color development start temperature is reached in the temperature-decreasing process from the color-erased state, and when the temperature reaches the complete color development temperature, the color is completely developed. It is a material that shows a hysteresis curve that starts to color and becomes completely decolored when the complete decolorization temperature is reached. The hysteresis curve of the reversible thermochromic material B is inherent in the hysteresis curve of the reversible thermochromic material A. A reversible thermochromic display characterized by the above.   The reversible thermochromic material according to claim 1, wherein the reversible thermochromic material A and the reversible thermochromic material B have different hues during color development.   The reversible thermochromic image including the reversible thermochromic material A and the reversible thermochromic image including the reversible thermochromic material B are provided so that there are portions that overlap each other and portions that do not overlap each other. 3. A reversible thermochromic display according to 1 or 2.   4. The reversible thermochromic image containing the reversible thermochromic material A and / or the reversible thermochromic image containing the reversible thermochromic material B contains a non-thermochromic colorant. A reversible thermochromic display as described in 1.

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