JP3278986B2 - Time indicator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time indicator. More specifically, fungicides, fungicides, herbicides,
Visually determine the shelf life of products with limited shelf life such as plant growth regulators, pheromone preparations, juvenile hormone mimetics, insect repellents, repellents, deodorants, fragrances, pharmaceuticals, foods, etc. by color change Regarding the time indicator that was made possible.

[0002]

2. Description of the Related Art A composition comprising, as a time indicator, a color-forming organic compound component, a second component for coloring the same, and a third component for decolorizing the two-component coloring system when added to the system. Mainly spread and held on a substrate such as paper or nonwoven fabric, the second or third component of these three components, one component remaining after volatilization in the use environment and a color-forming organic compound component (See, for example, JP-A-62-235562, JP-A-63-60901, and JP-A-2-290591).
Has been conventionally known.

[0003] However, in these methods, the volatilization speed of the second or third component varies greatly depending on the use environment, and when clothes or the like come into contact with the volatilization surface, the transfer speed to the clothes or the like is lower than the volatilization speed. The problem is that the color change period is greatly affected by the use environment and is not constant, for example, because the color change is caused by the large size. In addition, when clothes or the like come into contact with the volatile surface, the color easily discolors to cause discoloration or spots on the clothes or the like, or when spread and held on a base material such as paper or nonwoven fabric, the discoloration period is generally longer. There are drawbacks such as being short and difficult to control the discoloration period. Furthermore, when used as a time indicator when attached to various products that have a validity period, it is applied to uses such as pharmaceuticals and foods from the viewpoint of environmental pollution due to the volatilization of the above second or third component into the use environment. There is also a problem that the use scene is restricted because it is difficult to use as a time indicator in a small space or a closed space because the second or third component is difficult to volatilize.

[0004]

SUMMARY OF THE INVENTION As a result of repeated investigations, the present inventors have distributed components that cause color development or decoloration between two layers, and show the time lapse without releasing the components into the environment. Time indicator that can be used in a wide range of applications without problems such as the discoloration period being affected by the use environment, discoloration, and the inability to easily control the discoloration period. The present inventors have found that the present invention can be used by being attached to a product having a period, and have led to the present invention.

[0005]

Means for Solving the Problems That is, the present invention provides: Partition coefficient between both A and B layers obtained by superimposing A layer and B layer made of a thermoplastic resin or an adhesive [distribution coefficient =
(Concentration of electron-accepting organic compound in layer B during distribution equilibrium)
/ (Concentration of electron-accepting organic compound in layer A at the time of distribution equilibrium)] is 0.1 or more, and the layer A is in a color-developed state containing an electron-accepting organic compound and an electron-donating color-forming organic compound. By superimposing the B layer in the decolored state,
1. A time indicator characterized in that the color of the layer A disappears and the color fades with the lapse of time, indicating that the time has elapsed since the layers A and B were superimposed. When layer A and layer B made of a thermoplastic resin or an adhesive are overlapped, the distribution coefficient between both layers A and B [partition coefficient = (concentration of electron-accepting organic compound in layer B at distribution equilibrium) / (Concentration of electron-accepting organic compound in layer A at the time of distribution equilibrium)] is 0.1 or more, and electron-accepting organic compound is in a decolored state; Is superposed on a layer B made of a thermoplastic resin or a pressure-sensitive adhesive in a decolorized state, so that the layer B develops color over time and becomes darker. A time indicator that indicates the passage of time.

The time indicator of the present invention is one in which the electron-accepting organic compound is distributed from the layer A to the layer B and changes color in the process of reaching a distribution equilibrium. The larger the distribution coefficient of the B layer with respect to the A layer of the electron accepting organic compound at the use temperature and the greater the thickness of the B layer with respect to the A layer, the lower the concentration of the electron accepting organic compound in the A layer at the time of distribution equilibrium. In addition, the color tone changes greatly. When the distribution coefficient of the layer B to the layer A is 0.1 or less, the change in color tone is small, which is not preferable. When the distribution coefficient of layer B with respect to layer A is 0.1, the thickness of layer B is at least 10 times the thickness of layer A, when the distribution coefficient is 1, it is at least 1 time, and when the distribution coefficient is 10, it is 0.1.
It is preferable that the number be twice or more. Here, the distribution coefficient of the B layer with respect to the A layer of the electron accepting organic compound is determined by superposing the A layer and the B layer at the operating temperature and changing the concentration of the electron accepting organic compound in the A layer and the B layer with time. By measuring and knowing the concentration of the electron-accepting organic compound in the A layer and the B layer at the time when the distribution equilibrium is reached, it can be calculated by the following equation. (Partition coefficient of B layer with respect to A layer) = (concentration of electron-accepting organic compound in B layer at distribution equilibrium) / (A at distribution equilibrium)
Concentration of electron-accepting organic compound in the layer)

In the present invention, a barrier layer which does not easily permeate the environment due to evaporation, migration, and outflow of the electron-donating color-forming organic compound or the electron-accepting organic compound is small. Thus, the loss to the environment can be almost eliminated. In an embodiment in which the barrier layer is used, both the electron-donating color-forming organic compound and the electron-accepting organic compound pass through one surface of each of the A layer and the B layer, which are the outer surfaces when the A layer and the B layer are overlapped. A barrier layer that cannot be laminated may be used, or a layer A and a layer B, which are overlapped, may be covered and sealed with a barrier layer through which both the electron-donating color-forming organic compound and the electron-accepting organic compound cannot pass. The barrier layer used depends on the type of the electron-donating color-forming organic compound and the type of the electron-accepting organic compound, but various films such as polyester, eval, nylon, polyvinylidene chloride, and polypropylene, and transparent materials such as glass are appropriately used. Can be. Also, an opaque material such as aluminum or an inorganic vapor-deposited film may be used for a part of the barrier layer. The barrier layer and / or the A layer and / or the B layer may be printed and colored in advance. For example, a color change such as printing a character such as "end of use" in the same color as the color of the electron-donating color-forming organic compound or coloring it in a color different from the color of the electron-donating color-forming organic compound. Can be made clearer. Further, for example, because a weathering agent for improving the weatherability of the electron-donating color-forming organic compound is blended,
Additives and the like may be added to the barrier layer within a range that does not impair the object of the present invention.

In the present invention, the electron-donating color-forming organic compound is not particularly limited as long as it is a compound whose coloring by the electron-accepting organic compound reversibly occurs at the use temperature. And compounds such as rhodamine lactams, fluorans, triphenylmethane phthalides, phenothiazines, indolyl phthalides, spiropyrans, and leuco auramines. More specifically, for example, rhodamine B base, N-phenyl rhodamine lactam, crystal violet lactone, malachite green lactone, 1,3-dimethyl-6-diethylaminofluoran, 2- (2-chloroanilino) -6-
Dibutylaminofluorane, 3,7-bis (dimethylamino) -10-benzoylphenothiazine, N-3,3-trimethylindolinobenzospiropyran, ethylleucomethylene blue and the like. These electron donating color-forming organic compounds may be used alone or in combination of two or more. Among the above-described electron-donating color-forming organic compounds, those that develop black or blue are widely used as heat-sensitive and pressure-sensitive dyes in heat-sensitive paper and carbon copy paper.

The electron-accepting organic compound according to the present invention comprises:
There is no particular limitation as long as it is a compound (acidic substance) capable of forming an electron-donating color-forming organic compound at a use temperature, and various conventionally known compounds can be appropriately used according to a desired use period and a degree of discoloration. . For example, phenols such as resorcinol, cresol, 1-naphthol, 2-naphthol, hydroquinone, pyrocatechol, pyrogallol, bisphenol A, parachloromethaxylenol, orthophenylphenol, 3-methyl-4-isopropylphenol, and phenols such as salicylic acid Hydrophobic carboxylic acids, benzyl alcohol, alcohols such as 1-octanol, carboxylic acids such as stearic acid and myristic acid, lower alkyl esters of oxybenzoic acid, and the like can be used alone or as a mixture of two or more.

Most of the electron-donating color-forming organic compound and the electron-accepting organic compound used in the present invention are in a crystalline state when they exist alone at ordinary use temperature and pressure. Since these compounds have low color developability in the form of crystals, they are melted by heating or dissolved by a solvent when they are blended in the layer A, whereby these compounds are dispersed in the layer A in a molecular state (a state not crystallized). Is preferred. When it is contained in the layer A in the crystalline state, the coloration is low and the coloration is non-uniform, and a large amount of an electron-donating color-forming organic compound and an electron-accepting organic compound are mixed in order to form a uniform color. It is not preferable because it is necessary to do so.

The material of the layer A and the layer B in the present invention is not particularly limited as long as the combination at which the distribution coefficient of the electron-accepting organic compound at the use temperature is 0.1 or more is not limited, and various thermoplastic resins, adhesives, etc. You can choose from. The thermoplastic resin may be any one that can be thermally processed at a temperature not higher than the thermal decomposition temperature of the electron-accepting organic compound or the electron-donating color-forming organic compound and does not cause the electron-donating color-forming organic compound to develop color. Low-density polyethylene, linear low-density polyethylene which is a copolymer of ethylene and an α-olefin having 4 to 12 carbon atoms, high-density polyethylene, a copolymer of (ethylene and / or butene-1) and propylene, Examples thereof include copolymers of ethylene and vinyl acetate and / or acrylate) and olefinic thermoplastic resins such as polypropylene, and these can be used alone or in combination of two or more.
As the adhesive, conventionally known latex-based, natural rubber-based, SBR-based, polybutadiene-based, butyl rubber-based,
Rubber-based pressure-sensitive adhesives such as synthetic rubbers, acrylic-based pressure-sensitive adhesives such as acrylate esters, silicon-containing pressure-sensitive adhesives, silicone pressure-sensitive adhesives, and urethane-based pressure-sensitive adhesives can be used. As the type of the pressure-sensitive adhesive, any of an aqueous emulsion type, a solvent type, a non-solvent type, a cross-linked type, a non-cross-linked type and the like may be used.
Generally, the higher the degree of crosslinking, the longer the discoloration period. In the selection of the material of the A layer and the B layer in the present invention,
Since the decoloration at the end of use may be insufficient,
It is preferable that the composition does not contain components having an electron accepting property, such as additives, a plasticizer, and a catalyst residue, which cause the electron donating color forming organic compound to be colored. As an agent, for example, a small amount of an electron donating organic compound (basic compound) such as triethanolamine or aminoanthraquinone may be added to the A layer and / or the B layer. In this case, it must be within a range that does not hinder color development by the electron-accepting organic compound (acidic substance). The size of the A layer and the B layer can be appropriately different depending on the intended use. The size and shape of the A layer and the B layer may be the same, but those having different sizes and shapes may be used to clarify a change in color tone. in this case,
The color changes at the portion where the A layer and the B layer are overlapped, and the color of the layer A at the non-overlapping portion does not change.

The amount of the electron-donating color-forming organic compound and the amount of the electron-accepting organic compound can be arbitrarily changed in consideration of a desired color tone and an effective period.
0.001 to 5 parts by weight of the electron-donating color-forming organic compound and 0.1 of the electron-accepting organic compound with respect to 100 parts by weight of the layer.
５０50 parts by weight. When the amount of the electron-donating color-forming organic compound is less than 0.001 part by weight or the amount of the electron-accepting organic compound is less than 0.1 part by weight, the discoloration is unclear and When the compounding amount of the donor color-forming organic compound exceeds 5 parts by weight, or when the compounding amount of the electron-accepting organic compound exceeds 50 parts by weight, it is not preferable because the mating material bleeds to the surface.

The use of the present invention is not particularly limited, and it can be used by being attached to various products having an effective period. For example, the useful life of products such as fungicides / fungicides, herbicides, plant growth regulators, pheromone preparations, juvenile hormone mimics, insecticides, repellents, deodorants, fragrances, pharmaceuticals, animal and plant essential oils, and foods You can know by the discoloration of the time indicator.

The discoloration period of the time indicator of the present invention varies depending on the use temperature, but the diffusivity of the electron-accepting organic compound in the A layer and the B layer, the distribution coefficient of the electron-accepting organic compound, the A layer and the B layer. It can be controlled by factors such as the thickness of the layer, and can be set arbitrarily in a period of several hours to several years. The discoloration period of the time indicator becomes longer as the diffusivity in the A layer and the B layer is lower, the distribution coefficient of the electron-accepting organic compound is smaller, the thickness of the A layer is larger, and the thickness of the B layer is smaller. In order to control the discoloration period, the layer A and / or the layer B may be a multilayer body having on one or both sides thereof a layer made of a thermoplastic resin or an adhesive capable of transmitting an electron-accepting organic compound.

[0015]

According to the present invention, the discoloration period is not affected by the use environment, the color is hardly discolored, the discoloration period can be easily controlled, and the environmental pollution due to the volatilization of the added component into the use environment is achieved. Thus, it is possible to provide a very useful time indicator that can be used in conjunction with a product having an effective period in a wide range of applications without using it.

[0016]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 As a layer A, low density polyethylene (Sumitomo Chemical Co., Ltd.)
100 parts by weight of Sumikasen F208-0, manufactured by Sumikasen Co., Ltd.
2 parts by weight of 4 parts by weight of parachlorometaxylenol (manufactured by Wako Pure Chemical Industries, Ltd .; hereinafter, referred to as PCMX) were melt-kneaded in a closed pressure kneader (manufactured by Moriyama Seisakusho) using shear heat generation. After that, 300μ in thickness, 5cm by press molding
A corner sheet was obtained. As the B layer, a 300 μm-thick, 5 cm square press sheet of an ethylene-vinyl acetate copolymer (Evatate H2011 manufactured by Sumitomo Chemical Co., Ltd.) was used.

The A layer and the B layer are overlapped with each other, and the A layer and the B layer, which are two layers of a 200 μm-thick 10 cm square polyethylene terephthalate film (hereinafter referred to as PET) as a barrier layer, are placed at the center of the PET. P
Table 1 shows the results of observing the change over time in color tone at room temperature with the end face of ET fixed with aluminum tape. In the superposed layers A and B, the initial deep blue color gradually decreased, and almost disappeared after three months. Further, the PCMX concentration in the A layer and the B layer at this time was analyzed by gas chromatography of the acetone extract of the A layer and the B layer, and as a result, the distribution coefficient was 13.

Example 2 Table 1 shows the results of observing the change over time in color tone at room temperature in the same manner as in Example 1 except that the thickness of the layer B was changed to 150 μm. In the superposed layers A and B, the initial dark blue color gradually decreased, and almost disappeared after 6 months. Also,
As a result of analyzing the PCMX concentration in the A layer and the B layer at this time,
The partition coefficient was 13.

Example 3 Table 1 shows the results of observing the change over time in color tone at room temperature in the same manner as in Example 1 except that the thickness of the layer A was 450 μm and the thickness of the layer B was 150 μm. In the superimposed layers A and B, the initial dark blue color gradually decreased, and almost disappeared after 12 months. Also, the PC in the A layer and the B layer at this point
As a result of analyzing the MX concentration, the distribution coefficient was 13.

Comparative Example 1 The thickness of the layer A was 450 μm and the thickness of the layer B was 150 μm.
Table 1 shows the results of observing the change over time in color tone at room temperature in the same manner as in Example 1 except that low-density polyethylene (Sumikasen F208-0 manufactured by Sumitomo Chemical Co., Ltd.) was used as the layer. In this case, even after 12 months had passed, the color was slightly reduced as compared with the initial stage, but remained in the color-developed state.
At this time, the PCMX concentrations in the A layer and the B layer were almost equal, and the partition coefficient was 1. It is probable that this system had already reached the distribution equilibrium, but did not lose color due to the small thickness of the B layer. As described in the specification, when the distribution coefficient of the layer B to the layer A is 1, the thickness of the layer B is preferably at least one time.

Comparative Example 2 Low-density polyethylene (Sumitomo Chemical Co., Ltd.)
Sumikasen F208-0 (manufactured by Taoka Chemical Industry Co., Ltd.) was mixed with 0.04 part by weight to 100 parts by weight of Sumikasen F208-0, and the same procedure as in Example 1 was carried out except that parachloromethaxylenol was removed. Table 1 shows the results obtained by observing the change over time in the color tone in the above. Because there is no electron-accepting organic compound (parachlorometaxylenol),
The superimposed layers A and B remained bleached for 12 months.

Comparative Example 3 As layer A, low density polyethylene (Sumitomo Chemical Co., Ltd.)
Sumikasen F208-0) (100 parts by weight) was mixed with 2 parts by weight of parachloromethaxylenol, and the results of observing the time-dependent change in color tone at room temperature in the same manner as in Example 1 except that crystal violet lactone was removed were obtained. The results are shown in Table 1. Due to the absence of the electron-donating color-forming organic compound (crystal violet lactone), the superposed A and B layers remained decolorized for 12 months.

COMPARATIVE EXAMPLE 4 Crystal violet lactone and parachlorometa were added to a nonwoven fabric (Unitika Elves S0303WD0) having a thickness of 100 μm and a basis weight of 30 g / m 2 made of concentric fibers having a core layer of polyester and a sheath layer of polyethylene. A non-woven fabric containing 0.04 parts by weight of crystal violet lactone and 2 parts by weight of parachlorometa-xylenol was prepared by uniformly dropping a solution of xylenol in acetone. Table 1 shows the results of observing the change in color tone over time by suspending the nonwoven fabric at room temperature. The non-woven fabric had faded in only 10 days. Incidentally, the residual analysis of parachlorometaxylenol was carried out 10 days later. As a result, the residual amount was 0.

Example 4 A two-layer, three-layer film molded by the following method was used as the A layer.
It was used after being cut into a cm square. Ethylene-methyl methacrylate copolymer (Aclift WH202 manufactured by Sumitomo Chemical Co., Ltd.)
100 parts by weight, 0.04 parts by weight of Rhodamine B base (manufactured by Taoka Chemical Industry Co., Ltd.), and 2 parts by weight of butyl paraoxybenzoate are melt-kneaded in a closed pressure kneader using shear heat generation, and then extruded. It was hot-cut while being extruded and pelletized. Subsequently, a multilayer inflation apparatus equipped with a three-layer three-layer inflation die was used, and the above-mentioned drug-indicating resin-assembled material was supplied to the intermediate layer of the die at a temperature of 170 ° C. and a die temperature of 150 ° C. For both the inner layer and the outer layer, low-density polyethylene (Sumikasen CE2559 manufactured by Sumitomo Chemical Co., Ltd.) was supplied under the conditions of a melting zone of 180 ° C and a die temperature of 150 ° C.
The resin supplied to each layer is bonded inside the die, and a tubular body having a three-layer sandwich structure (outer layer / intermediate layer / inner layer) is taken off at a take-up speed of 4.2 m / min.
There was obtained a two-layer, three-layer film having a total thickness of 50 μm, composed of 0 μ / 30 μm of the intermediate layer / 10 μm of the inner layer. As the layer B, a pressed sheet of ethylene-methyl methacrylate copolymer (Aclift WH202 manufactured by Sumitomo Chemical Co., Ltd.) having a thickness of 100 μm and a square of 5 cm was used. After layer A and layer B overlap,
After sandwiching the A layer and the B layer which were overlapped with the barrier layer in the same manner as in Example 1, the end face of the PET was fixed with aluminum tape,
At room temperature, (1) hanging in the room, (2) hanging in a Western chest so as not to touch the clothing, (3) in a glass petri dish, (4) in a glass petri dish with wool muslin on the bottom Table 2 shows the results of observing the change in color tone over time at each location. In the layer A and the layer B which were superimposed, the initial deep red-purple color development gradually decreased and almost disappeared after three months. The erasing period was constant regardless of the installation location.

Example 5 A PET-based pressure-sensitive adhesive (manufactured by Lintec Co., Ltd.)
Table 2 shows the results of observing color tone changes in the same manner as in Example 4 except that Super Stick PET38CLWP (3) PET3801) was used. In the layer A and the layer B which were superimposed, the initial deep red-purple color development gradually decreased and almost disappeared after 4 months.
The erasing period was constant regardless of the installation location.

Comparative Example 5 The results of observing the change in color tone in the same manner as in Example 4 are shown in Table 2 except that the two- and three-layer films used as the A layer in Example 4 were used alone. This film, with the disappearance of the electron-accepting organic compound (butyl parahydroxybenzoate),
The initial dark reddish purple color gradually fades and disappears,
The erasing period varied greatly depending on the installation location (use environment, conditions). In addition, from the comparison between the case where the suspension was hung indoors and the case where the suspension was placed in a petri dish covered with wool muslin, it was considered that the transfer rate to wool muslin was faster than the evaporation rate of butyl paraoxybenzoate. .

Example 6 A two-layer, three-layer film molded by the following method was used as the A layer.
It was used after being cut into a cm square. Ethylene-methyl methacrylate copolymer (Aclift WH202 manufactured by Sumitomo Chemical Co., Ltd.)
After 100 parts by weight and 2 parts by weight of methyl paraoxybenzoate were melt-kneaded in a closed pressure kneader utilizing shear heat generation, the mixture was supplied to an extruder, extruded, and hot-cut to form pellets. Subsequently, using a multilayer inflation apparatus equipped with a three-layer three-layer inflation die, the above-mentioned medicinal property-indicating resin composition was supplied to the intermediate layer, and in the same manner as in Example 4, the thickness of each layer was 10 μm for the outer layer / 30 μm for the intermediate layer. / Inner layer 10
Thus, a two-layer, three-layer film having a total thickness of 50 μ was obtained. As the layer B, an ethylene-methyl methacrylate copolymer (Aclift WH202 manufactured by Sumitomo Chemical Co., Ltd.) 100
Parts by weight and Rhodamine B base (Taoka Chemical Industry Co., Ltd.)
After melting and kneading 0.04 parts by weight in a closed-type pressure kneader using shear heat, a thickness of 10 wt.
A sheet of 0 μ, 5 cm square was used. After the A layer and the B layer were overlapped, the A layer was overlapped with the barrier layer in the same manner as in Example 1.
After sandwiching the layer and the layer B, the end face of the PET was fixed with an aluminum tape, and the color change over time was observed at a constant temperature of 20 ° C and 40 ° C. The layer A and layer B, which were superimposed, were initially transparent, but the color of reddish purple gradually increased and almost no color change was observed. The discoloration period was one month at 20 ° C and 20 hours at 40 ° C.

[0028]

Continuation of the front page (56) References JP-A-62-235562 (JP, A) JP-A-1-150883 (JP, A) JP-A-4-505213 (JP, A) JP-A-6-501770 (JP) , A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G04F 1/00-1/02

Claims (7)

(57) [Claims] When a layer A and a layer B made of a thermoplastic resin or a pressure-sensitive adhesive are overlapped, a distribution coefficient between both layers A and B [partition coefficient = (electron acceptability in the layer B at the time of distribution equilibrium) (Concentration of organic compound) / (concentration of electron-accepting organic compound in layer A at the time of distribution equilibrium)] is 0.1 or more , and contains an electron-donating color-forming organic compound . The layer A in the color developing state and the layer B in the decolored state are overlapped, and the layer A is decolorized with time and the color fades. A time indicator that can indicate the passage of time. 2. When a layer A and a layer B made of a thermoplastic resin or an adhesive are overlapped, a distribution coefficient between both layers A and B [partition coefficient = (electron acceptance in the layer B at the time of distribution equilibrium) A) which contains an electron-accepting organic compound in which the concentration of the organic accepting compound / (the concentration of the electron-accepting organic compound in the layer A at the time of distribution equilibrium)] is 0.1 or more, and is in a decolored state; When the layer B containing the color-developing organic compound and being in the decolored state is overlapped with each other, the layer B develops color over time and becomes darker. A time indicator that can indicate the progress. 3. The method according to claim 1, wherein the electron-donating color-forming organic compound is selected from the group consisting of rhodamine lactams, fluorans, triphenylmethanephthalides, phenothiazines, indolylphthalides, spiropyrans, leukoauramines, and two of these.
3. The time indicator according to claim 1, wherein the time indicator is a mixture of two or more kinds. 4. The method according to claim 1, wherein the electron-accepting organic compound is resorcin, cresol, hydroquinone, pyrocatechol, pyrogallol, dimethyl oxalate, 1-naphthol, 2-naphthol, salicylic acid, benzyl alcohol, 1-octanol, stearic acid, myristic acid, para-acid. Chlormetaxylenol, orthophenylphenol, bisphenol A, 3-methyl-4-isopropylphenol, 3-
The time indicator according to claim 1 or 2, which is a lower alkyl ester of acetyl-6-methyl-2-pyranone or oxybenzoic acid or a mixture of two or more thereof. 5. The layer A and / or the layer B, wherein the layer A and the layer B
The time indicator according to claim 1 or 2, wherein the time indicator is a multilayer body having a layer made of a thermoplastic resin or a pressure-sensitive adhesive which is permeable to the electron-accepting organic compound. 6. A barrier layer through which both an electron-donating color-forming organic compound and an electron-accepting organic compound cannot permeate on one surface of each of the A layer and the B layer, which are the outer surfaces when the A layer and the B layer are superposed. 6. The time indicator according to claim 1, wherein the time indicators are laminated. 7. The time indicator according to claim 1, wherein the superposed A layer and B layer are covered and sealed with a barrier layer through which both the electron-donating color-forming organic compound and the electron-accepting organic compound cannot pass. .