JP2010127634A - Reusable time indicator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reusable time indicator which tarnishes with the passage of time without being accompanied by movement and volatilization of components, and enables visual determination of the passage of a predetermined period. <P>SOLUTION: The time indicator is composed of, as a component which tarnishes with the passage of time, a composition which is a thermochromic composition comprising an electron-donative color-developing organic compound(s), an electron-accepting compound(s), and a desensitizer and uses, as the electron-accepting compound(s), one or more compounds each of which has two aromatic rings, is represented by specific general formula, and has a melting point exceeding 150°C. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a time indicator for visually determining the passage of a predetermined time based on a change in color tone, and relates to a time indicator that can be reused by heat treatment.

  Various time indicators (also called time indicators) using changes in color tone have already been proposed. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2-290591) can match the change in color tone with the effective period of a product, is easy to manufacture, and has an electron donating property as an economical and low-cost time indicator. A mixture of a colorable organic compound, a compound having a phenolic hydroxyl group having volatility, and an organic compound that is liquid at room temperature is held on a base material, and the compound having the phenolic hydroxyl group is volatilized when exposed to the atmosphere. We have proposed a time indicator that uses a constant color fading change.

  In Patent Document 1, a compound having a phenolic hydroxyl group is an electron-accepting compound, and forms a color by being combined with an electron-donating color-forming organic compound. Organic compounds that are liquid at room temperature (that is, hardly volatile) act as desensitizers. The time indicator in the same document changes from colored to colorless due to the volatilization of compounds with phenolic hydroxyl groups over time and the color-reducing effect of less volatile organic compounds, and the expiration date (end point) is visually identified by the change. enable.

  On the other hand, Patent Document 2 (Japanese Patent Laid-Open No. 7-27878) discloses that the time indicator as described in Patent Document 1 is a problem of environmental pollution due to volatilization of the additive component into the use environment, and a problem of color fading of the indicator. In addition, the color change period is easily affected by the use environment, and it is difficult to change the color. In this document, in order to solve these problems, when the A layer and the B layer made of a thermoplastic resin or an adhesive are superposed, the distribution coefficient between the two layers [distribution coefficient = (B layer at the time of distribution equilibrium) Electron donating colorable organic compound) / (concentration of electron donating colorable organic compound in layer A during distribution equilibrium)] is 0.1 or more. The layer A that is in a decolored state and contains the B layer that has an electron accepting property and is in a decolored state causes the color development of the B layer to become darker over time. Proposes a time indicator that can indicate the passage of time since.

  In Patent Document 3 (Japanese Patent Laid-Open No. 7-27879), in order to solve the same problem as that described in Patent Document 2, the A layer and the B layer made of a thermoplastic resin or an adhesive are overlapped. When 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 distribution equilibrium) )] Containing an electron-accepting organic compound and an electron-donating color-forming organic compound having a value of 0.1 or more, and superposing the A layer in a colored state and the B layer in a decolored state over time, In addition, a time gin indicator has been proposed that can indicate the passage of time since the layers A and B are superposed when the layer A is decolored and the color fades.

  Patent Document 4 (Japanese Patent Application Laid-Open No. 6-41442) discloses that the time indicator described in Patent Document 1 uses three components as essential components, whereas the end point of the medicinal effect is more accurately determined by the color change caused by the action between the two components. A medicinal effect indicating resin composition that makes it possible to easily determine the remaining amount of a medicinal component within an effective period is proposed. Specifically, this document describes a medicinal effect indicating resin composition obtained by melt-kneading a thermoplastic resin, a volatile electron-accepting organic compound, and a non-volatile electron-donating color-forming organic compound. is suggesting.

  Patent Document 5 (Japanese Patent Application Laid-Open No. 2002-129139) is a color-changing temporal indicator having a color-changing ink layer and a non-color-changing ink layer that change color according to temperature and / or humidity and elapsed time on a substrate. It has a separating layer that separates the base material from the color-changing ink layer and the non-color-changing ink layer, and the color-changing ink layer and the non-color-changing ink layer are formed on the separating layer so that part or all of the color-changing ink layer is exposed to the outside air Proposal of a discoloration aging indicator characterized by This indicator exhibits a color change performance according to environmental conditions (temperature and / or humidity) and elapsed time over a long period of about one week to two years, and can accurately check the color change (color difference). The effect is demonstrated.

JP-A-2-290591 JP-A-7-27878 JP-A-7-27879 Japanese Patent Laid-Open No. 6-41442 JP 2002-129139 A

  The time indicators described in the above Patent Documents 1 to 5 are all used only once in view of their configuration (that is, a configuration involving movement or volatilization of a dye) and are not repeatedly used. Such a time indicator has an advantage that it can be used easily, but is not necessarily preferable from the viewpoint of resource saving and cost saving. Moreover, if the time indicator can be used repeatedly, it can be considered that the range of use of the time indicator can be greatly widened by attaching it to tableware, storage containers and bottles, and various electric appliances. .

  The present invention has been made in view of the above circumstances, and provides a time-indicator that can be used repeatedly in a composition responsible for discoloration, in which components do not move greatly or volatilize. It was made as a purpose.

  The present invention includes an electron-donating color-forming organic compound, an electron-accepting compound, and a desensitizer. The electron-accepting compound is represented by any one of the following general formulas (1) to (3) and has a melting point. A time indicator comprising a thermochromic composition comprising one or more compounds having a temperature greater than 150 ° C.

(In the general formulas (1) to (3), R ₁ and R ₂ are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a phenyl group, or a cyclohexyl group; , Y and Z are each independently a halogen, an OH group, an alkoxy group, an alkoxyallyl group, an allyl group, a linear or branched alkyl group having 1 to 4 carbon atoms, a phenyl group, or a cyclohexyl group; Is a C5-C8 cycloalkane which may have a substituent or a fluorene ring which may have a substituent.

  The time indicator of the present invention uses a compound represented by a specific chemical formula and having a melting point exceeding 150 ° C. as an electron-accepting compound (that is, a developer), which is a component of a thermochromic composition. It is characterized by. This specific electron-accepting compound reacts with an electron-donating color-forming organic compound (that is, a color former) and changes color with time so that the color density changes with time after coloring. To the sex composition. In addition, the thermochromic composition containing this specific electron-accepting compound undergoes color change with time and is then heated to recover its color development state. Thereafter, the color density changes again over time. Therefore, the time indicator of the present invention containing such a thermochromic composition can be reused because it can change over time, for example, from a dark color to a light color and repeat this color change.

  In the time indicator of the present invention, the thermochromic composition may exist as a thermochromic microcapsule encapsulated in the microcapsule. When the thermochromic composition is encapsulated in the microcapsules, the microcapsules are less susceptible to the influence of substances present in the surroundings.

  The time indicator of the present invention uses a compound represented by the above-mentioned specific general formula and a melting point exceeding 150 ° C. as a developer of the thermochromic composition, and once reacts the color former with the developer. Then, after the color is developed (or decolored), the color density changes with time. Thus, this time indicator can change color over time without the volatilization or significant movement of the components of the thermochromic composition. Further, the time indicator of the present invention can return to the original color development state (that is, the color development state before the color change with time) by heating after the color change over time. Therefore, since the time indicator of the present invention can be used repeatedly, in addition to food management and temporal management of drugs (particularly biopharmaceuticals), repeated temporal management of various articles and products (for example, It attaches to a flower pot and makes it possible to visually check watering when watering every predetermined number of days.

  The time indicator of the present invention comprises an electron-donating color-forming organic compound, an electron-accepting compound, and a desensitizer, and is represented by a specific general formula as an electron-accepting compound and has a melting point exceeding 150 ° C. A thermochromic composition containing one or more of the above. The components constituting the thermochromic composition (hereinafter sometimes simply referred to as “composition”) included in the time indicator of the present invention will be described below.

[Electron-donating colored organic compound]
The electron-donating color-forming organic compound is also called a color former and reacts with the electron-accepting compound to give a color. A known compound may be arbitrarily used as the electron-donating color-forming organic compound. Specifically, fluorans, fluorenes, diphenylmethane phthalides, diphenylmethane azaphthalides, indolyl phthalides, phenyl indolyl phthalides, phenyl indolyl azaphthalides, styrylquinolines, diazarhodamine Lactones, pyridine compounds, quinazoline compounds, bisquinazoline compounds, ethylenophthalide compounds, and ethylenoazaphthalide compounds are examples of electron donating color-forming organic compounds. Two or more kinds of electron-donating color-forming organic compounds may be used in combination.

The electron donating color-forming organic compound is preferably
2- (2-chloroanilino) -6-dibutylaminofluorane,
3,6-bis (diphenylamino) fluorane.

  The content of the electron-donating color-forming organic compound is preferably 0.1% by weight to 50% by weight, based on the total weight of the composition, and 0.8% by weight to 15% by weight. More preferably. When the content of the electron-donating color-forming organic compound is small, the color density may be low. When the content is high, the background color (color density in the decolored state) may be large. is there.

[Electron-accepting compound]
The electron-accepting compound is also called a color developer and is a compound that reacts with an electron-donating color-forming organic compound to give a color. Specifically, the electron-accepting compound is a compound having an active proton, a pseudo-acidic compound, or an electron empty compound. A compound having pores. Furthermore, in the present invention, a compound represented by any one of the following general formulas (1) to (3) and having a melting point exceeding 150 ° C. is used as the electron-accepting compound.

In the general formulas (1) to (3), R ₁ and R ₂ are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a phenyl group, a cyclohexyl group, Y and Z are each independently halogen, OH group, alkoxy group, alkoxyallyl group, allyl group, linear or branched alkyl group having 1 to 4 carbon atoms, phenyl group, or cyclohexyl group, and C is , A C5-C8 cycloalkane which may have a substituent or a fluorene ring which may have a substituent.

  In the general formula (2), when C is a cycloalkane having 6 carbon atoms (that is, cyclohexane), the general formula (2) is represented by the following formula.

  Specifically, 4-hydroxy-4′-propoxydiphenyl sulfone, 1,1-bis (4-hydroxyphenyl) -1-isobutylethane, 2,2-bis (4-hydroxyphenyl) propane, 4-hydroxy- 4′-allyloxydiphenyl sulfone, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,1-bis (4-hydroxyphenyl) cyclohexane and biscresol fluorene are preferably used. In particular, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, biscresol fluorene, 4-hydroxy-4′-allyloxydiphenyl sulfone, and 4-hydroxy-4′-propoxydiphenyl sulfone are heat resistant. For example, it is suitable for being kneaded into a thermoplastic resin.

  Only one kind of the compound represented by any of the above three general formulas and having a melting point exceeding 150 ° C. may be used, or a plurality of kinds may be used in combination. By mixing a plurality of types of compounds, a thermochromic composition having better characteristics can be obtained utilizing the characteristics of each compound.

  The content of the electron-accepting compound is preferably 0.05% to 98% by weight, more preferably 0.5% to 77% by weight, based on the weight of the entire composition. preferable. When the content of the electron-accepting compound is small, the color density may be low, and when the content is high, the background color may be large. The electron-accepting compound is preferably contained in an amount of 0.1 to 100 parts by weight, and 0.5 to 20 parts by weight, based on 1 part by weight of the electron-donating color-forming organic compound More preferably.

[Desensitizer]
The desensitizer is a compound that can dissolve the electron-donating color-forming organic compound and the electron-accepting compound, and can control the color reaction by the solidification or melting characteristics thereof. In the present invention, for example, by selecting a widely used desensitizer, the color can be changed at -10 ° C to 60 ° C. Specifically, a hardly volatile hydrophobic organic medium (or solvent or solvent) is used as a desensitizer.

  More specifically, examples of the desensitizer include aliphatic monohydric alcohols having 10 or more carbon atoms, fatty acids having 10 or more carbon atoms, fatty acid monoamides having 6 or more carbon atoms, and ester compounds having 13 or more carbon atoms in total. it can

Further, it is composed of an arbitrary combination of an aliphatic, aromatic and alicyclic monobasic acid and any one of an aliphatic, aromatic and alicyclic monohydric alcohol used as a general-purpose desensitizer. An ester compound having a total carbon number of 13 or more and having the following form can be used in the present invention.
-The general-purpose desensitizer acid is a polybasic acid.
-The general-purpose desensitizer alcohol is a polyhydric alcohol.
-The general-purpose desensitizer acid is a polybasic acid and the alcohol is a polyhydric alcohol.

  Alternatively, an aliphatic ketone compound having a total carbon number of 10 or more and an aliphatic ether compound having a total carbon number of 10 or more, which are general-purpose desensitizers, can be used in the present invention.

  Even more specifically, as a desensitizer, methyl laurate, lauric acid amide, methyl myristate, palmitic acid amide, methyl palmitate, myristic acid amide, stearic acid methyl, stearic acid amide, methyl behenic acid, and behenine Mention may be made of acid amides.

  The content of the desensitizer is preferably 1% by weight to 99% by weight, and more preferably 19% by weight to 99% by weight, based on the weight of the entire composition. When the content of the electron-donating color-forming organic compound is small, the background color may increase, and when the content is large, the color density may decrease. Further, the desensitizer is preferably contained in an amount of 1 to 500 parts by weight, more preferably 5 to 100 parts by weight, with respect to 1 part by weight of the electron donating color-forming organic compound. .

  The thermochromic composition constituting the time indicator may contain other components contained in a normal thermochromic composition. Hereinafter, other components will be described.

[Ultraviolet absorber]
The thermochromic composition may contain an ultraviolet absorber. The ultraviolet absorber selectively absorbs ultraviolet rays contained in sunlight. Ultraviolet rays cause the color former to deteriorate by photoreaction. UV absorbers are used to prevent this.

  UV absorbers are broadly classified into benzophenone, benzotriazole, cyanoacrylate, triazine, salicylic acid, oxalic anilide, malonic ester, benzoic acid, cinnamic acid, and dibenzoylmethane. The More specifically, benzotriazole-based Tinuvin 326, triazine-based Tinuvin 40 (all manufactured by Ciba Specialty Chemicals), oxalic acid anilide-based Hostavin 3260HP, malonic ester-based Hostavin PR25 (all manufactured by Clariant), benzophenone-based siasorb UV531 (made by Cytec Industries) can be used.

  The content of the ultraviolet absorber is preferably up to 96% by weight, more preferably up to 61% by weight, based on the weight of the entire composition. When the content of the ultraviolet absorber is large, the color density may be lowered, discoloration may not be sharp, and / or discoloration temperature hysteresis may be increased. Moreover, it is preferable that an ultraviolet absorber is contained in the quantity up to 50 weight part with respect to 1 weight part of electron-donating colorable organic compounds, and it is more preferable that it is contained in the quantity up to 10 weight part.

[Ultraviolet scattering agent]
The thermochromic composition may contain an ultraviolet scattering agent. The ultraviolet scattering agent physically reflects or scatters ultraviolet rays contained in sunlight. As a result, the action of ultraviolet rays on the color former is prevented. The ultraviolet scattering agent is, for example, metal oxide fine particles such as zinc oxide, titanium oxide, α-iron oxide, and cerium oxide.

[Light stabilizer]
The thermochromic composition may include a light stabilizer. The light stabilizer prevents the coloring agent from deteriorating due to the reaction between the radicals generated by ultraviolet rays and the coloring agent. Specifically, hindered phenols or hindered amines may be used as light stabilizers.

[Others]
As a component other than the components shown above, any of antioxidants (phenolic, phosphorous, and sulfur-based), infrared absorbers, fluorescent brighteners, non-thermochromic dyes, and non-thermochromic pigments One or more components may be included. When the thermochromic composition contains a non-thermochromic dye or a non-thermochromic pigment, the color produced by the reaction between the electron-donating color-forming organic compound and the electron-accepting compound, the dye or the The color mixture with the color of the pigment is changed over time to the color of only the dye or the color of the pigment. Therefore, when a dye or pigment that does not discolor due to heat is used in combination, it may be easier to visually check the passage of time.

  Next, the manufacturing method of this thermochromic composition is demonstrated. The composition can be produced by heating and dissolving an electron-donating color-forming organic compound, an electron-accepting compound, a desensitizer, and, if necessary, other components. The temperature at that time is selected so that the component having the highest melting point among all the components is dissolved, and is generally in the range of 120 ° C to 180 ° C.

  Alternatively, the thermochromic composition may be encapsulated in microcapsules. Due to the microencapsulation, the problems that occur when the thermochromic composition is used as it is, for example, in an ink or plastic molding, that is, 1) the migration of components to repeat the solid-liquid state change during discoloration. 2) Avoids or reduces the problem that vehicle components (resins, solvents, etc.) tend to affect the discoloration and may have an adverse effect. Is done. This is because the microencapsulation blocks the contact with the surrounding atmosphere during use, thereby preventing the influence of substances present in the vicinity.

  Microencapsulation of the thermochromic composition can be performed according to the following procedure. First, the capsule wall raw material and the thermochromic composition are uniformly dissolved in the desensitizer using a solubilizing agent as necessary. The solubilizing agent can uniformly dissolve the thermochromic composition and the capsule wall raw material, and does not impair the thermochromic performance or needs to be removed in a subsequent process. Specifically, an ester solvent, a ketone solvent, an ether solvent, a glycol ether solvent, a hydrocarbon solvent, an aromatic solvent, a nitrogen-containing solvent, a silicon solvent, and a halogen-containing solvent are dissolved. Can be used as an agent. More specifically, ethyl acetate, acetone, and methyl ethyl ketone are preferably used.

  The capsule wall raw material includes a resin main component and a crosslinking agent. The resin main component is a compound that reacts with a crosslinking agent at the interface of an O / W emulsion having a capsule inclusion as a dispersed phase to form a capsule wall. The crosslinking agent is a compound that reacts with the resin main component at the interface of the O / W emulsion having the capsule inclusion as a dispersed phase to form a capsule wall.

  Examples of combinations of the resin main agent and the crosslinking agent are as follows.

  Next, a solution containing the capsule wall raw material and the thermochromic composition is added to the aqueous emulsifier solution heated to 30 to 60 ° C. while being subjected to medium shear stirring. After the addition, high shear stirring is performed to obtain an O / W emulsion having an average particle size of several μm. An emulsifier is an amphiphilic substance that is adsorbed on the interface of an O / W emulsion having a capsule inclusion as a dispersed phase to stabilize the system. Specifically, the emulsifier is a natural water-soluble polymer, a synthetic water-soluble polymer, a low molecular surfactant, and inorganic fine particles. The emulsifiers according to the combination of the resin main agent and the crosslinking agent are as follows.

  The aqueous emulsifier solution is preferably an aqueous solution containing 0.1 to 15% by weight of an emulsifier, and more preferably an aqueous solution containing 0.5 to 8% by weight of an emulsifier. If the concentration of the emulsifier is too high, foaming may occur, and if it is too low, the particle size may increase or emulsification may not be possible.

  After high-shear stirring, switch to low-shear stirring and slowly drop the aqueous crosslinking agent solution. After dropping, the reaction is carried out at 60-90 ° C. for 3-12 hours, and then cooled to room temperature. Thereby, a slurry in which microcapsules are dispersed can be obtained.

The preferred amounts of the above raw materials and additives used in microencapsulation (more preferred amounts in parentheses) are as follows.
Thermochromic composition: 5 to 50 parts by weight (10 to 40 parts by weight)
Dissolving aid: 0 to 100 parts by weight (0 to 40 parts by weight)
Emulsifier aqueous solution: 100 parts by weight Resin main ingredient: 1-50 parts by weight (2-10 parts by weight)
Cross-linking agent: 0.5 to 25 parts by weight (1 to 5 parts by weight)

  If the amount of the thermochromic composition is too large, emulsification may not be possible, and if it is too small, the productivity may deteriorate. If the amount of the solubilizing agent is too large, the productivity may be deteriorated, and if it is too small, the color density may be lowered. If the amount of the resin main component is too large or too small, the reaction may be insufficient and the capsule strength and heat resistance may be reduced. Similarly, if the amount of the crosslinking agent is too large or too small, the reaction may be insufficient and the strength and heat resistance of the capsule may be reduced.

  The thermochromic composition described above has the property that the color density changes over time (generally lowers) after thermal color change (that is, after color development) at a predetermined temperature. The form of change over time in the color density (for example, the speed of change over time) can be adjusted by a combination of a desensitizer and a developer. Furthermore, this thermochromic composition is such that, after the color density changes with time, by heating, the color development state returns to before the change with time (that is, the color density increases). Has the property of changing. Therefore, when a time indicator is composed of this thermochromic composition, it can be used repeatedly. Although it depends on the components of the composition, the heating is generally performed at a temperature of about 100 to 150 ° C. for 10 seconds to 5 minutes. Heating may be performed using, for example, a hair dryer.

  The time indicator of the present invention may be provided in sheet form by impregnating or applying the thermochromic composition described above into paper, cloth, film, board and other sheet materials. Alternatively, the aging indicator may be provided in the form of a molded body by kneading and molding the thermochromic composition into a thermosetting or thermoplastic resin. Alternatively, the time indicator may be applied to glass, ceramic and ceramic surfaces and provided in the form of a coating. Or you may package the indicator of said form with a breathable film or a nonwoven fabric further. Alternatively, the indicator in the above form may be subjected to extrusion lamination.

  The time-lapse indicator of the present invention is used when an effective period or an expiration date of an article having an expiration date has expired, or when an expiration date has been reached, or at a certain time before the expiration of the effective period or before the expiration date (for example, one week before ) Can be used to visually confirm that it has reached. Such articles are foods, fungicides, fungicides, herbicides, plant growth regulators, pheromone formulations, insect repellents, repellents, deodorants, fragrances, pharmaceuticals, bio-related reagents and the like. Alternatively, the time indicator of the present invention can be used when it is necessary to repeatedly manage a certain period or time, for example, watering and fertilizing plants, feeding animals, and the like.

(Examples 1 to 26, Comparative Examples 1 to 16)
A thermochromic composition was prepared using an electron-donating color-forming organic compound (color former), an electron-accepting compound (developer) and a desensitizer shown in Tables 3-6. Specifically, these three components were heated and dissolved at a temperature in the range of 120 to 180 ° C.

(Preparation of measurement sample)
A thermochromic composition heated to 70-100 ° C. A sample for measurement was prepared by dropping 0.05 g onto 5C filter paper and impregnating it by heating at 70 ° C. for 10 minutes. However, for the sample for measuring a thermochromic composition using an electron-accepting compound having a melting point of 100 ° C. or higher, the impregnation condition was 100 ° C. for 10 minutes.

Using the color difference meter CR-300 manufactured by Konica Minolta (formerly Minolta), the white color proofing of the initial color development state and ground color development state of the obtained measurement sample and the color development state (color density) after storage Evaluation was made by determining the color difference from the plate. The color difference is expressed by the following formula. In the formula, L ^* represents a lightness index, and a ^* and b ^* represent a chromaticness index. Details are described in the instruction manual of the device (especially page 77). It can be said that the larger the ΔE ^{*, the} higher the color density or background color density.

Measurement of ΔE ^* in the colored state was performed in a -5 ℃ cooler box, the measurement of the ΔE ^* in the background color development (color erasing) state was carried out on a 100 ℃ hot plate. The color development state after storage was evaluated by measuring ΔE ^* after storing at 32 ° C. for 4 days. From the ΔE ^* before and after storage, the rate of change in color density was calculated according to the following formula.

Furthermore, the erasability over time was evaluated from the value of change rate (absolute value) according to the following criteria.
Good (◯): | Change rate |> 10
Bad (×): | Change rate | ≦ 10

Tables 3 to 6 show the evaluation results of the measurement samples prepared using the discoloration compositions of the examples and the comparative examples. In each Example and each Comparative Example, the melting point of the electron-accepting compound was measured using TG / DTA6220 manufactured by SII Nanotechnology. The measurement was performed at an N ₂ flow rate of 200 ml / min and a heating rate of 10 ° C./min, and the melting start temperature appearing on the DTA curve was taken as the melting point.

(Examples 27-31, Comparative Examples 21-25)
Microcapsules were prepared using the compositions selected from the thermochromic compositions prepared in Examples 1 to 26 and Comparative Examples 1 to 20 as inclusions. The materials and amounts used for the production of the microcapsules are as follows.

  Using these materials, the thermochromic composition and the resin main agent are uniformly dissolved in the solubilizer, and then this solution is added to the aqueous emulsifier solution heated to 60 ° C. with medium shear stirring. did. Next, high shear stirring was performed to obtain an O / W emulsion having an average particle size of several μm. Then, low shear stirring was performed and the aqueous crosslinking agent solution was gradually added dropwise. After dropping, the mixture was reacted at 60 ° C. for 1 hour and 90 ° C. for 1 hour, cooled to room temperature, and a slurry in which microcapsules were dispersed was obtained.

A microencapsulated thermochromic composition in which a sample for measurement was cooled to room temperature, One filter paper was coated with a doctor blade (200 μm) and dried at room temperature for 2 hours. Using this sample, the measurement of the ΔE ^* in the colored state and the background color development (color erasing) state, the measurement of ΔE ^* in the colored state after storage was performed. These measurements were made by the method described in connection with Examples 1-26. Table 8 shows the initial color development and ground color development of each example and each comparative example, the rate of change in color density after storage, and the color erasability over time.

All the examples and comparative examples are reversible thermochromic compositions that can develop a black color at a temperature lower than that at a color change temperature of about 30 ° C. and repeat the change to become colorless at a higher temperature. In Examples 1 to 6 using an electron-accepting compound having a melting point> 150 ° C., the absolute value of the change rate of ΔE ^* after storage was larger than 10 and could function well as an indicator. In Comparative Examples 1 to 4 using an electron-accepting compound having a melting point ≦ 150 ° C., the absolute value of the change rate of ΔE ^* after storage was within 10 and did not show erasability over time.

In Examples 7-12, in which stearamide was added as a desensitizing agent to the thermochromic compositions of Examples 1-6, the absolute value of the rate of change of ΔE ^* after storage was greater than 10 and good as an indicator. It could function. In Comparative Examples 5 to 8 in which stearic acid amide was added to the thermochromic compositions of Comparative Examples 1 to 4, the absolute value of the rate of change of ΔE ^* after storage was within 10 and did not show erasability over time. .

In Examples 13 to 17 in which two kinds of electron accepting compounds having a melting point> 150 ° C. were used in combination, the absolute value of the rate of change of ΔE ^* after storage was larger than 10 and could function well as an indicator. In Comparative Examples 9 to 12, in which two types of electron-accepting compounds having a melting point ≦ 150 ° C. were used in combination, the absolute value of the change rate of ΔE ^* after storage was 10 or less and did not show erasability over time.

In Example 18 in which three kinds of electron accepting compounds having melting points> 150 ° C. were used in combination, the absolute value of the rate of change of ΔE ^* after storage was larger than 10, and could function well as an indicator. In Comparative Example 13 in which three kinds of electron accepting compounds having a melting point ≦ 150 ° C. were used in combination, the absolute value of the rate of change of ΔE ^* after storage was within 10 and did not show erasability over time.

The time-decoloring properties of Examples 19 to 23, 25, and 26 using an electron-accepting compound having a melting point> 150 ° C. and the addition of an ultraviolet absorber are 10 in absolute value of the change rate of ΔE ^* after storage. It was larger and could function well as an indicator. In Comparative Examples 15 and 16 using an electron-accepting compound having a melting point ≦ 150 ° C. and added with an ultraviolet absorber, the absolute value of the change rate of ΔE ^* after storage is 10 or less, and the decoloring property with time is good. Not shown. In Example 24, in which two kinds of electron-donating color-forming organic compounds were used in combination and an electron-accepting compound having a melting point> 150 ° C. was used, the absolute value of the change rate of ΔE ^* after storage was larger than 10, and it was good as an indicator Could function. In Comparative Example 14 in which two kinds of electron-donating color-forming organic compounds were used in combination and an electron-accepting compound having a melting point <150 ° C. was used, the absolute value of the rate of change in ΔE ^* after storage was 10 or less. It did not show color.

Examples 27 to 31 in which the thermochromic compositions (Examples 5, 11, 24, 25, and 26) that function as indicators and have good color erasing properties are microencapsulated have a change rate of ΔE ^* after storage. The absolute values were all greater than 10% and could function well as an indicator. In Comparative Examples 21 to 25, in which Comparative Examples 1, 6, and 14 to 16 were microencapsulated, the absolute values of the change rate of ΔE ^* after storage were all within 10 and did not show erasability over time.

  Further, when the compositions and microcapsules of Examples 1 to 34 that had been erased with time were heated at 100 ° C. for 5 minutes, the color developed before the color was erased with time, and could be used again as an indicator of time.

  Since the time indicator of the present invention is discolorable over time and can be reused by heating after discoloration over time, the end of the period of an article having an effective period or expiration date, such as foodstuffs and drugs, or The deadline can be used for visual discrimination.

Claims (5)

It contains an electron-donating color-forming organic compound, an electron-accepting compound, and a desensitizer. The electron-accepting compound is represented by any one of the following general formulas (1) to (3) and has a melting point of 150 ° C. A time indicator comprising a thermochromic composition comprising one or more compounds in excess.

(In the general formulas (1) to (3), R ₁ and R ₂ are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a phenyl group, or a cyclohexyl group; , Y and Z are each independently a halogen, an OH group, an alkoxy group, an alkoxyallyl group, an allyl group, a linear or branched alkyl group having 1 to 4 carbon atoms, a phenyl group, or a cyclohexyl group; Is a C5-C8 cycloalkane which may have a substituent or a fluorene ring which may have a substituent.   The thermochromic composition comprises 1,1-bis (4-hydroxyphenyl) -1-phenylethane, biscresol fluorene, 4-hydroxy-4′-allyloxydiphenyl sulfone, and 4 as the electron-accepting compound. The time indicator according to claim 1, comprising any one or more of -hydroxy-4'-propoxydiphenylsulfone.   2. The time indicator according to claim 1, wherein the thermochromic composition further comprises one or both of a non-thermochromic dye and a non-thermochromic pigment.   The time indicator according to any one of claims 1 to 3, wherein the thermochromic composition is encapsulated in a microcapsule.   An indicator of the time indicator, comprising: changing the color of the time indicator according to any one of claims 1 to 4 during a certain period and then returning to a colored state at the start of the certain period by heating. Playback method.