JPH11140436A - Heat-sensitive coloring material and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems on a heat-sensitive material that develops a color irreversibly with change in the tone of the developed color cannot be produced, when a lower temperature rises to room one. SOLUTION: A film of 300 μm thickness is prepared in which each composite fine particle comprises a core part of Ag fine particles and an Au shell layer covering the surface of the core Ag fine particles are dispersed in a matrix substance. When it is stored at a low temperature, no change is observed in its color, but in case that it was allowed to stand at room temperature, its color changes from pale yellow via yellow to orange or reddish orange with the passage of time. In addition, when it is permitted to stand at 20 deg.C for 1 hour, clear difference is noticed from the case at 10 deg.C for 1 hour.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosensitive coloring material utilizing plasmon absorption exhibited by a fine particle structure, and is used, for example, for a cooling system, temperature control of refrigerated and frozen foods.

[0002]

2. Description of the Related Art Conventionally, as a heat-sensitive coloring material, there is PCT International Publication No. WO97 / 28228. As shown in FIG. 7 (a), as shown in FIG. It is configured to be dispersed in a matrix material 2 composed of an organic composite layer or a resin layer. As shown in FIG. 7B, the temperature history can be confirmed by the fact that the metal fine particles 1 in the material grow irreversibly by the application of heat and exhibit surface plasmon absorption.

[0003]

The above-mentioned materials have the following problems because only one kind of metal constitutes the fine particles contained in the material.

That is, since the surface plasmon absorption wavelength of the metal fine particles shows almost no dependence on the particle diameter, the conventional thermosensitive coloring material has a problem that the color tone is limited to one color. Taking a conventional thermosensitive coloring material containing 1 wt% of gold ions as an example, the absorption wavelength peak wavelength at the start of coloring and at the completion of coloring changes only by about 20 nm, and the change in color tone can be confirmed with the naked eye. It was difficult. For this reason, the evaluation of the temperature history could be performed only by the density of the material and the degree of coloring of the element.

When the conventional heat-sensitive coloring material is left at 25 ° C., the difference in luminance between the lapse of one hour and the lapse of two hours is about 8%, and it is difficult to determine the difference with the naked eye. It has been difficult to evaluate the temperature history by using.

Further, conventional thermosensitive coloring materials are used at 20 ° C. and 10 ° C.
The difference in luminance when each was left in an atmosphere of ° C. for one hour was only about 5%, and it was extremely difficult to distinguish the difference with the naked eye. For this reason, it has been difficult to evaluate the temperature history using conventional materials.

In addition, when a conventional thermosensitive coloring material is placed on frozen or refrigerated products for sale, it is difficult to read and evaluate temperature history information in a short time.

[0008]

SUMMARY OF THE INVENTION The present invention is directed to a heat-sensitive method that enables a clear temperature history evaluation not only by a change in the color luminance but also by a large change in the color tone when the color is formed by applying heat. The purpose is to provide coloring materials.

In order to solve the above-mentioned problems, a first aspect of the present invention is described.
The thermosensitive coloring material of the present invention comprises a composite material having a core portion made of a metal chalcogenide compound, a metal halide, or a metal, and a metal shell structure or a structure in which metal fine particles are attached to at least a part of the surface of the core. And the size of the composite fine particles is irreversibly increased by the application of heat. Since the absorption peak wavelength caused by surface plasmon changes due to the increase in shell thickness and the particle size of the deposited metal, it is possible to provide a thermosensitive coloring material with a large change in color tone and perform a clear temperature history evaluation. Become.

In the thermosensitive coloring material of the present invention, the matrix material is selected from the group consisting of an inorganic material, an inorganic / organic composite, and a resin. The inorganic material or the inorganic material constituting the inorganic / organic composite is at least one selected from silicon oxide, aluminum oxide, and titanium oxide, and the organic material is at least one selected from polyacrylic acid, polyacrylate, and polyethylene oxide. 1
It is preferably one. Further, it is preferable that the resin layer is at least one selected from polyvinyl alcohol, polyvinyl butyral, polystyrene, acrylonitrile / styrene copolymer, and fluororesin.

In the heat-sensitive coloring material of the present invention, the metal material is preferably at least one selected from gold, platinum, silver, copper, tin, rhodium, palladium and iridium. Further, in the thermosensitive coloring material of the present invention, when the core portion is formed of a chalcogenide compound or a halide, the material may be a compound of a metal element forming a shell portion and a chalcogenide element or a halogen element. preferable.

The second thermosensitive coloring material of the present invention is characterized in that at least two or more kinds of fine metal particles are dispersed in a matrix material, and the particle diameter of the fine particles is irreversibly increased by applying heat. Things.

The first method for producing a thermosensitive coloring material of the present invention comprises the steps of: preparing a mixture containing a metal ion, an α-hydrogen-containing alcohol, and a matrix-forming material; Irradiating, and preparing a metal ion different from the metal ion into a mixture, and ultraviolet light or γ
Performing a second irradiation of any of the lines.

The second method for producing a thermosensitive coloring material of the present invention comprises the steps of: preparing a mixture containing a metal ion, an α-hydrogen-containing alcohol, and a matrix-forming material; And a step of preparing a mixture of a metal ion different from the metal ion and a surfactant, and a step of subjecting the mixture to a second irradiation with either ultraviolet light or γ-rays. It is a feature.

Further, the third method for producing a thermosensitive coloring material of the present invention comprises a step of preparing a mixture containing a metal ion, an α-hydrogen-containing alcohol, and a matrix-forming material, and adding the chalcogenide compound or the halide to the mixture. To prepare a mixture, and a step of irradiating the mixture with either ultraviolet light or γ-rays.

Further, the fourth method for producing a thermosensitive coloring material of the present invention comprises a step of preparing a mixture containing a metal ion, an α-hydrogen-containing alcohol, and a matrix-forming material, and adding the chalcogenide compound or a halide to the mixture. And adding a surfactant to prepare a mixture, and irradiating the mixture with either ultraviolet light or γ-rays.

Further, the fifth method for producing a thermosensitive coloring material of the present invention comprises a step of preparing a mixture containing at least two or more kinds of metal ions, an α-hydrogen-containing alcohol, a surfactant and a matrix substance. The method includes a step of irradiating either ultraviolet rays or γ rays.

In the method for producing a thermosensitive coloring material of the present invention, the surfactant is a carboxylic acid group, a sulfonic acid group,
It is preferably at least one selected from a material group having a sulfate ester group, a phosphate ester group, and a phosphonic acid group.

Further, the first thermosensitive coloring device of the present invention comprises a base and a thermosensitive coloring material disposed on the base, wherein the thermosensitive coloring material has a core portion of a metal chalcogenide compound or a metal halide, or It is composed of any one of metals, and contains a composite material having a metal shell structure or metal fine particles on at least a part of the surface of the nucleus, and a matrix material.The particle size of the composite fine particles is agglomerated by application of heat. And irreversibly increases.

Further, a second thermosensitive coloring element of the present invention comprises a base and a thermosensitive coloring material disposed on the base, wherein the thermosensitive coloring material comprises metal fine particles comprising at least two or more single metal elements. And a matrix material for dispersing the fine particles, wherein the particle diameter of each fine particle is irreversibly increased by agglomeration due to application of heat.

The first method for producing a thermosensitive coloring device of the present invention comprises the steps of: preparing a mixture containing a metal ion, an α-hydrogen-containing alcohol, and a matrix-forming material;
A step of irradiating the mixture with any one of ultraviolet rays or γ-rays, a step of adding a metal ion different from the metal ions to the mixture to form a mixture, a step of placing the mixture on the substrate, and a step of placing the mixture on the substrate To the mixture
A second step of irradiating either ultraviolet rays or γ-rays to form a thermosensitive coloring material.

The second method for producing a thermosensitive coloring device of the present invention comprises the steps of: preparing a mixture containing a metal ion, an α-hydrogen-containing alcohol, and a matrix-forming material;
A step of irradiating the mixture with either a second ultraviolet ray or γ-ray, a step of adding a metal ion different from the metal ion to the mixture, and a surfactant to form a mixture, and a step of placing the mixture on a substrate And a second step of irradiating the mixture disposed on the substrate with either ultraviolet light or γ-rays to form a thermosensitive coloring material.

In the method for producing a thermosensitive coloring material according to the present invention, the prepared mixture is placed on a substrate before the first step of irradiating the substrate with ultraviolet light or γ-rays. Alternatively, irradiation of γ-rays is performed, and then the second irradiation of ultraviolet rays or γ-rays is performed on the substrate on which a mixture containing a metal ion of a type different from the metal ions contained in the mixture is arranged. The same effect can be obtained by the manufacturing method in which

Further, the third method for producing a thermosensitive coloring device of the present invention comprises a step of preparing a mixture containing a metal ion, an α-hydrogen-containing alcohol and a matrix-forming material, and the step of preparing a mixture comprising a chalcogenide compound or a halide. Adding and preparing the mixture, arranging the mixture on the substrate, and irradiating the mixture arranged on the substrate with either ultraviolet light or γ-ray to form a thermosensitive coloring material. Is what you do.

The fourth method for producing a thermosensitive coloring device of the present invention comprises the steps of preparing a mixture containing a metal ion, an α-hydrogen-containing alcohol, and a matrix-forming material, and adding the mixture containing a chalcogenide compound or a halide to the mixture. Or a step of adding and preparing a surfactant, a step of disposing the mixture on a substrate, and a step of irradiating the mixture disposed on the substrate with either ultraviolet light or γ-ray to form a thermosensitive coloring material. It is characterized by doing.

The fifth method for producing a thermosensitive coloring device of the present invention comprises the steps of: preparing a mixture containing at least two kinds of metal ions, an α-hydrogen-containing alcohol, a surfactant, and a matrix-forming material; A step of disposing the mixture on the substrate, a step of irradiating the mixture disposed on the substrate with ultraviolet light or any of γ rays to form a thermosensitive coloring material,
It is characterized by including.

In the method for producing a thermosensitive coloring device of the present invention, the mixture containing metal ions is applied by a dipping method, a coating method,
Alternatively, it is preferable to arrange on the substrate surface by at least one method selected from spin coating.

Further, the thermosensitive coloring element of the present invention can be used in the case where heat is applied and when no heat is applied by arranging a thermosensitive coloring material in a conventionally used bar code information display portion. This is a thermo-sensitive coloring element characterized by displaying different bar code information, and enables temperature history evaluation in a short time using a conventionally used bar code reading system.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Thermosensitive Coloring Material> The first thermosensitive coloring material of the present invention will be described below.

FIG. 1 shows the structure of the produced thermosensitive coloring material. FIG. 1A shows the structure before heat application.
(B) and (c) show the structure after heat application. FIG.
The composite fine particles 3 in (b) and (c) are the core fine particles 4
And a fine particle having a composite structure in which a metal shell structure 5 or a metal fine particle 6 is attached to at least a part of the core surface. The composite fine particles 3 are dispersed in the matrix material 2. The fine particles 7 in FIG. 1A showing the state before the application of heat become the core fine particles 4 after the application of heat. Before heat application, metal fine particles 1 having a smaller particle diameter than fine particles 7 are present,
After the application of heat, the particles are aggregated on the surface of the fine particles 7 to form the metal shell 5 or the attached fine metal particles 6. The core portion 4 of the fine particles 7 and the composite fine particles 3 is formed of any of a metal chalcogenide compound, a metal halide, or a metal. When the nucleus 4 is a metal, the nucleus 4 and the metal part 5 or 6 are composed of another kind of metal.

The thermosensitive coloring material constituted as described above is
As shown in FIG. 1A, when the standing time at a specific temperature is short, the light absorption is small because the particle size of the fine particles 7 is small. On the other hand, by applying heat of a certain amount or more, the composite fine particles 3
And the surface plasmon absorption becomes remarkable.

The surface plasmon absorption wavelength of the fine particles composed of a single composition is almost independent of the particle diameter and is constant, but the plasmon absorption wavelength of the composite fine particles 3 composed of a plurality of compositions is Or the particle diameter of the metal fine particles 6 attached to the nucleus. For this reason, in the coloring process due to the application of heat, not only the luminance changes but also the color tone changes greatly. The change in the color tone allows a clearer evaluation of the temperature history.

The dispersion amount of the fine particle portion in the matrix is not particularly limited, but it is easy to control the particle size, hardly causes agglomeration of the fine particles, and 0.01 to 20.
wt%, preferably about 0.01 to 10 wt%. If agglomeration occurs, only a part of the layer undergoes a deep color change, and it is not possible to reliably confirm the presence or absence of a temperature change.

The average particle diameter of the fine particles after growth varies depending on the kind, but is preferably, for example, usually in the range of 1 nm to 100 nm, and particularly 3 nm to 80 nm in order to reduce the particle size distribution and uniform coloring. The range is more preferred.

Further, when the fine metal part is gold, platinum, silver,
According to a preferred embodiment of the present invention, which is at least one selected from copper, tin, rhodium, palladium, and iridium, these metals exhibit a color development based on plasmon absorption, and show oxygen and other metals as compared with other metals. Since relatively pure fine particles can be deposited without being affected by impurities, it is possible to realize a material exhibiting excellent thermosensitive coloring characteristics.

In the present invention, when the core portion of the fine particles 1 is formed of either a chalcogenide compound or a halide of a metal element, the metal element contained in these compounds is formed on the surface of the nucleus by a shell or It is preferably the same as the metal element forming the fine particles.

In the present invention, the matrix forming material in which the fine particles are dispersed is selected from an inorganic substance, an inorganic / organic composite, and a resin.

The inorganic material used as the matrix material is formed from at least one inorganic alkoxide containing silicon, aluminum, or titanium. Such an inorganic substance contains at least one gel selected from the group consisting of silica gel, alumina gel, and titania gel.

The inorganic / organic composite is formed from a composite forming material containing at least one composite forming inorganic component and at least one composite forming organic component. Examples of the complex-forming inorganic component include an inorganic alkoxide containing silicon, aluminum, or titanium. Examples of complex forming organic components include polyacrylic acid, polyacrylates, and polyethylene oxide.

The resin is formed of a matrix forming resin selected from the group consisting of polyvinyl alcohol, polyvinyl butyral, polystyrene, acrylonitrile styrene copolymer, and fluororesin. Fluororesins are preferred because the resulting matrix material is transparent and has excellent mechanical strength.

<Second Thermosensitive Coloring Material> The second thermosensitive coloring material of the present invention will be described below.

FIG. 2 shows the structure of the produced thermosensitive coloring material. FIG. 2A shows the structure before heat application.
(B) shows the structure after heat application.

Prior to the application of heat, single metal particles 1, 8 composed of different metal elements are dispersed in a matrix material. It is assumed that the number of constituent elements of the dispersed metal fine particles is at least two or more. After the application of heat, each fine particle grows by aggregation, so that the surface plasmon absorption of each fine particle becomes remarkable. The complementary color of the superposition of the absorption of the fine particles is the color of the material after color development.

Since the agglomeration rate of each metal fine particle is different, the shape of the absorption spectrum is greatly changed by the application of heat. Not only does the color development luminance of the material change with the temperature history, but also the color tone of the material changes continuously depending on the temperature history such as the standing temperature and the standing time. For this reason, it is possible to more clearly evaluate the temperature history as compared with a conventional thermosensitive coloring material.

The dispersion amount of the fine particles in the matrix, the particle size of the fine particles, and the constituent materials are the same as those of the first thermosensitive coloring material.

<Method for Producing the First Thermosensitive Coloring Material> The first method for producing the thermosensitive coloring material of the present invention will be described below.

First, a mixture containing a metal ion, an α-hydrogen-containing alcohol, and a matrix-forming material is prepared.

Examples of metal ions include gold, platinum, silver,
Examples include ions such as copper, tin, rhodium, palladium and iridium. The metal ion is provided from a metal compound that can be dispersed in the sol-like matrix forming material described below. Examples of such metal compounds include AuHC
l4, AuNaCl4, H2PtCl6, AgClO4, C
uCl2, SnCl2, IrCl3, RhCl3, and P
dCl2. Particularly, AuHCl4 is preferable.

The α-hydrogen-containing alcohol is preferably a dihydric alcohol containing α-hydrogen, and typical examples include ethylene glycol and propylene glycol. The α-hydrogen-containing alcohol is contained in the prepared mixture in an amount of preferably about 0.5 to 1.5 mol per 1 mol of the metal ion.

Examples of the matrix-forming material include any of inorganic alkoxide-based materials, composite-forming materials, and matrix-forming resins.

Examples of the matrix-forming material containing an inorganic alkoxide include, in addition to the inorganic alkoxide, alcohols selected from the group consisting of methanol, ethanol and propanol in which the alkoxide is dispersed, hydrochloric acid or ammonia as a catalyst, and water as a solvent. No.

The complex-forming material contains at least one kind of complex-forming inorganic component and at least one kind of complex-forming organic component. The composite forming material also contains an alcohol, a catalyst, and water, like the inorganic alkoxide-based material.

Inorganic alkoxide, complex forming organic component,
The resin material is as described above in the first embodiment of the thermosensitive coloring material.

Next, the mixture is irradiated with ultraviolet rays or γ rays. Irradiation conditions depend on the type, amount,
It can be arbitrarily selected depending on the desired coloring characteristics. By irradiation with ultraviolet rays or γ-rays, metal ions contained in the mixture are reduced by the α-hydrogen-containing alcohol, and metal fine particles consisting of a simple metal are dispersed in the matrix to be formed. It is preferable to irradiate ultraviolet rays and γ-rays until the intrinsic color of the metal ions in the mixture (for example, pale yellow for gold ions) completely disappears or until immediately before. The reason is that excessive irradiation causes aggregation of metal fine particles irrespective of the application of heat, and insufficient irradiation results in a remarkable decrease in the coloration reaction rate.
The irradiation amount of ultraviolet rays and γ rays is 0.01 mW /
cm 2 to about 100 mW / cm 2, preferably 1 mW / cm 2
It is preferable to set the strength to about 20 to 20 mW / cm 2. This is because it is preferable to avoid performing irradiation at an excessive intensity because the rise in temperature during irradiation causes aggregation of the metal fine particles, and the irradiation time becomes longer when the irradiation is performed at an extremely low intensity. This causes aggregation of the metal fine particles.

Next, a metal ion different from the metal ions contained in the mixture is added to the mixture. Examples of metal ions and examples of metal compounds containing metal ions are as described above. The concentration of metal ions is
As described above, about 0.01 to 20 wt%, preferably 0.05 to 20 wt%, of which no extreme aggregation of the fine particles occurs.
About 10 wt% is good.

Next, the prepared mixture is subjected to a second irradiation of either ultraviolet rays or γ-rays. As in the first irradiation, irradiation conditions can be arbitrarily selected. UV or γ
By the irradiation of the rays, the added metal ions are reduced, and metal fine particles consisting of a single metal are formed, and at the same time, a shell structure is formed around the metal fine particle nuclei that have already been generated.
Agglomeration occurs.

The metal fine particles reduced and generated by the first irradiation of ultraviolet rays or γ rays tend to act as a catalyst for the reduction reaction of metal ions during the second irradiation. For this reason, the probability of the photoreduction reaction at the time of the second irradiation occurring on the surface of the fine particles generated in advance and dispersed in the matrix is higher than the probability of occurring in the dispersion matrix. As a result, a shell structure is formed on the surface of the fine particle nucleus.

Thus, the thermosensitive coloring material of the present invention is manufactured. Since the heat-sensitive coloring material develops color by the application of heat and light, it is preferable that it is stored immediately after production under low-temperature, dark place conditions.

By applying heat to the heat-sensitive coloring material produced by the above method, coloring occurs based on surface plasmon absorption. The surface plasmon absorption wavelength exhibited by the composite fine particles is different from the absorption exhibited by a single metal fine particle, and the absorption wavelength continuously changes as the size ratio between the core and the non-nucleus changes. Further, the change in the color development luminance with the application of heat is the same as in the case of the conventional thermosensitive coloring material. For this reason, the thermosensitive coloring material manufactured by the manufacturing method of the present embodiment shows a clear change in temperature history as compared with the conventional material, and enables more clear temperature history evaluation.

<Method of Manufacturing the Second Thermosensitive Coloring Material> The second method of manufacturing the thermosensitive coloring material of the present invention will be described below.

First, a mixture containing a metal ion, an α-hydrogen-containing alcohol, and a matrix-forming material is prepared.

Examples of each material are as described above. Next, the mixture is irradiated with a first ultraviolet ray or gamma ray.

Next, a metal ion different from the metal ions contained in the mixture and a surfactant are added to the mixture.

The surfactant is preferably at least one selected from the group consisting of materials having a carboxylic acid group, a sulfonic acid group, a sulfate ester group, a phosphate ester group, and a phosphonic acid group. These are materials classified as anionic surfactants. As described in the first embodiment of the method for producing a thermosensitive coloring material, the fine metal particles generated by the first reduction work as a catalyst for the photoreduction reaction of metal ions by the second irradiation of ultraviolet rays or γ rays. Although effective, anionic surfactants have the effect of reducing this effect. For this reason, the introduction of surfactant
This has the effect of preventing the formation of a metal shell structure over the entire area of the metal fine particle surface. The amount of the surfactant is 0.001 to 10
It is preferably introduced at a concentration of about wt%, preferably about 0.005 to 1 wt%. The conditions vary depending on the type of the surfactant, but when 0.05% by weight or less of the surfactant is introduced, composite fine particles are formed and 0.1% by weight is added.
%, Two or more kinds of single metal fine particles are formed without forming composite fine particles.

Next, the prepared mixture is subjected to a second irradiation of either ultraviolet rays or γ-rays. As in the first irradiation, irradiation conditions can be arbitrarily selected. UV or γ
The irradiation of the line reduces the added metal ions and forms metal fine particles composed of a single metal. Aggregation also occurs on the surface of the already formed metal fine particle nuclei, and the metal fine particles adhere to a part of the core surface to form aggregated composite fine particles. When the effect of introducing the surfactant is large, the composite fine particles are not formed, and two or more kinds of metal fine particles composed of a single metal are formed.

It is needless to say that the step of introducing the surfactant into the mixed solution can be performed before the first irradiation step of ultraviolet rays or γ rays. However, the introduction of the surfactant is more preferably performed after the first photoreduction reaction step to reduce the reaction rate of the photoreduction reaction.

Thus, the thermosensitive coloring material of the present invention is manufactured. Since the heat-sensitive coloring material develops color by the application of heat and light, it is preferable that it is stored immediately after production under low-temperature, dark place conditions.

By applying heat to the heat-sensitive coloring material produced by the above method, a coloring due to surface plasmon absorption was obtained.

The surface plasmon absorption wavelength of the composite fine particles is different from the absorption of the single metal fine particles, and the absorption wavelength changes continuously as the size ratio between the core and the non-nucleus changes. I do. Further, the change in the color development luminance with the application of heat is the same as in the case of the conventional thermosensitive coloring material. For this reason, the thermosensitive coloring material manufactured by the manufacturing method of the present embodiment shows a clear change in temperature history as compared with the conventional material, and enables more clear temperature history evaluation.

Further, even when the composite fine particles are not formed, the thermosensitive color tone continuously changes depending on the temperature history. The absorption spectrum of the present material including the fine metal particles composed of two types of simple elements is a superposition of the surface plasmon absorption spectra of the fine metal particles. Since the aggregation rates of the respective metal fine particles are different, the outline of the absorption spectrum is greatly changed by the application of heat. Not only does the color development luminance of the material change with the temperature history, but also the color tone of the material changes continuously depending on the temperature history such as the standing temperature and the standing time. For this reason, it is possible to more clearly evaluate the temperature history as compared with a conventional thermosensitive coloring material.

<Method of Manufacturing Third Thermosensitive Coloring Material> The third method of manufacturing the thermosensitive coloring material of the present invention will be described below.

First, a compound containing either a chalcogen element or a halogen element, which reacts with a metal ion or the above metal element to generate a chalcogenide compound or a halogen compound, an α-hydrogen-containing alcohol, and a matrix A mixture containing the forming materials is prepared.

Examples of metal ions, metal compounds serving as metal ion sources, alcohols, and matrix forming materials are based on the first method for producing a thermosensitive coloring material. The mixing amount of metal ions is 0.01 to 1 wt%
The degree is preferred.

Examples of the chalcogen element source and the halogen element source include Na 2 S, K 2 S, NaCl, and KCl. The mixing amount is preferably about 0.005 to 1 wt%, and preferably does not exceed the concentration of the metal ions.

The prepared mixture is reacted by stirring. Fine particles composed of metal chalcogenide or metal halide are formed and dispersed in the matrix material. The generated fine particles form the core of the composite fine particles at the end of the final step. The particle size of the core fine particles depends on the composition in the mixture. Preferably, the particle size is controlled at about 1 to 10 nm.

Next, the mixture is irradiated with ultraviolet rays or γ rays. Irradiation conditions depend on the type, amount,
It can be arbitrarily selected depending on the desired coloring characteristics. By irradiation with ultraviolet rays or γ-rays, metal ions contained in the mixture are reduced with α-hydrogen-containing alcohol to generate metal fine particles. The reduction reaction is highly likely to occur using nuclear fine particles dispersed in a matrix as a catalyst. For this reason, the metal fine particles are preferentially generated on the surface of the core fine particles to form a shell structure. Further, the metal fine particles generated by the reduction in the matrix also diffuse and agglomerate due to the application of heat, and the thickness of the shell portion increases, whereby the composite fine particles grow. It is preferable to irradiate ultraviolet rays and γ-rays until the intrinsic color of the metal ions in the mixture (for example, pale yellow for gold ions) completely disappears or until immediately before. This is because excessive irradiation causes agglomeration of fine particles regardless of application of heat.

The metal element forming the core portion and the metal element forming the shell portion do not necessarily have to match.
When another element is used, it is necessary to introduce a step of adding a metal compound containing another kind of metal ion and preparing a mixture before the step of irradiating with ultraviolet rays or gamma rays.

Thus, the thermosensitive coloring material of the present invention is produced. Since the heat-sensitive coloring material develops color by the application of heat and light, it is preferable that it is stored immediately after production under low-temperature, dark place conditions.

When heat is applied to the thermosensitive coloring material produced by the above method, a coloring due to surface plasmon absorption is obtained. As the particle size increases, the absorption wavelength of the surface plasmon exhibited by the composite fine particles greatly changes. The color development characteristic accompanied by a change in color tone enables more clear temperature history evaluation.

<Fourth Method for Producing a Thermosensitive Coloring Material> A fourth method for producing a thermosensitive coloring material of the present invention will be described below.

First, a compound containing either a chalcogen element or a halogen element, which reacts with a metal ion or the above metal element to generate a chalcogenide compound or a halogen compound, an α-hydrogen-containing alcohol, A mixture containing the materials and the surfactant is prepared.

For examples of metal ions, metal compounds serving as metal ion sources, and matrix forming materials,
This shall conform to the method for producing the first thermosensitive coloring material. The mixing amount of metal ions is preferably about 0.01 to 1 wt%.

Examples of the source of the chalcogen element and the source of the halogen element conform to the third method for producing a thermosensitive coloring material. The mixing amount is preferably about 0.005 to 1 wt%, and preferably does not exceed the concentration of the metal ions.

Regarding the type of surfactant and the amount introduced,
And the method for producing a thermosensitive coloring material described in (1).

The mixture thus prepared is reacted by stirring. Fine particles comprising either a metal chalcogenide or a metal halide are formed by being dispersed in the mixture. The particle size of the produced fine particles depends on the composition in the mixture. It is preferable that the particle diameter of the fine particles be controlled at about 1 to 10 nm. At the end of the final step, the fine particles form the core of the composite fine particles.

Next, the mixture is irradiated with ultraviolet rays or γ rays. Irradiation conditions depend on the type, amount,
It can be arbitrarily selected depending on the desired coloring characteristics. By irradiation with ultraviolet rays or γ-rays, metal ions contained in the mixture are reduced with α-hydrogen-containing alcohol to generate metal fine particles. Since the core fine particles act as a catalyst for reduction, the metal fine particles are preferentially reduced on the surface of the core fine particles. The surfactant reduces the catalytic effect by binding to the surface of the core fine particles. Therefore, composite fine particles in which metal fine particles adhere to a part of the surface of the core fine particles are generated.

It is needless to say that the step of introducing the surfactant into the mixed solution can be performed before the first irradiation step of ultraviolet rays or gamma rays. However,
The introduction of the surfactant is preferably performed after the first photoreduction reaction step in order to reduce the reaction rate of the photoreduction reaction.

Thus, the thermosensitive coloring material of the present invention is manufactured. Since the heat-sensitive coloring material develops color by the application of heat and light, it is preferable that it is stored immediately after production under low-temperature, dark place conditions.

When heat is applied to the thermosensitive coloring material produced by the above method, the fine metal particles grow and the absorption wavelength of the surface plasmon exhibited by the composite fine particles changes. Due to the coloring characteristics accompanied by a change in color tone, it is possible to evaluate the temperature history more clearly than conventional materials.

<Fifth Method for Producing a Thermosensitive Coloring Material> The fifth method for producing a thermosensitive coloring material of the present invention will be described below.

First, a mixture containing at least two or more metal ions, an α-hydrogen-containing alcohol, a surfactant, and a matrix-forming material is prepared.

Examples of metal ions, metal compounds serving as metal ion sources, alcohols, matrix-forming materials, and surfactants are based on the above-described method for producing a thermosensitive coloring material. The total mixing amount of metal ions is 0.1 to
About 10 wt% is preferable.

The type of the surfactant conforms to the embodiment of the second method for producing a thermosensitive coloring material. The amount of the surfactant introduced into the mixture is 0.001 to 10% by weight.
It is preferably introduced at a concentration of about 0.01 to 5 wt%.

The prepared mixture is irradiated with ultraviolet rays or γ rays to reduce contained metal ions to fine metal particles.

Irradiation conditions include the type of metal ion used,
It depends on the amount and the desired coloring properties and can be chosen arbitrarily. By irradiation with ultraviolet rays or γ-rays, metal ions contained in the mixture are reduced with α-hydrogen-containing alcohol to generate metal fine particles. The surfactant introduced into the mixed solution is adsorbed on the surface of the metal fine particles. The fine particles having a surfactant bonded to the surface are less effective as a catalyst for the reduction reaction. For this reason, the probability that composite fine particles are generated by the introduction of the surfactant is reduced. It is preferable to irradiate ultraviolet rays and γ-rays until the intrinsic color of the metal ions in the mixture (for example, pale yellow for gold ions) completely disappears or until immediately before. This is because excessive irradiation causes aggregation of metal fine particles irrespective of application of heat.

As described above, the thermosensitive coloring material of the present invention is manufactured. Since the heat-sensitive coloring material develops color by the application of heat and light, it is preferable that it is stored immediately after production under low-temperature, dark place conditions.

The heat-sensitive coloring material produced by the above method was
When heat is applied, it shows color due to surface plasmon absorption.
The complementary color of the superposition of the absorption of the metal fine particles is the color of the material after color development. Because the aggregation rate of each metal particle is different,
The general shape of the absorption spectrum changes greatly due to the application of heat. Not only does the color development luminance of the material change with the temperature history, but also the color tone of the material changes continuously depending on the temperature history such as the standing temperature and the standing time. For this reason, it is possible to more clearly evaluate the temperature history as compared with a conventional thermosensitive coloring material.

<First Thermosensitive Coloring Element> The first thermosensitive coloring element of the present invention will be described below.

The first thermosensitive coloring device of the present invention comprises:
A heat-sensitive coloring material disposed on the base;

FIG. 3 shows a cross section of the structure of the produced thermosensitive coloring device. In FIG. 3, reference numeral 9 denotes a substrate, 3 denotes composite fine particles, and 2 denotes a matrix material. The fine particles 3 are fine particles having a nucleus 4 and a composite structure in which a metal shell structure 5 or a metal fine particle 6 is attached to at least a part of the nucleus surface. The nucleus 4 is formed of a metal chalcogenide compound, a metal halide, or a metal. The shell 5 or the attached fine particles 6 are made of metal. When the core 4 is made of a metal, the core 4 and the shell 5 or the fine particles 6 are made of a different kind of metal element.

Examples of each constituent element of the thermosensitive coloring material, such as a metal, a metal chalcogenide compound, a metal halide, a matrix substance, are as described above.

The thermosensitive coloring material is disposed directly on the substrate, disposed via an adhesive layer (for example, an epoxy-based adhesive layer), or impregnated on the substrate. The amount of the thermosensitive coloring material to be disposed is not particularly limited, but is preferably 0.1 m 2 per 1 cm 2 of the substrate.
g to 100 mg, more preferably 1 mg to 10 mg.

The thermosensitive coloring device configured as above is
In a state in which the application of heat is small, the thickness of the shell 5 of the composite fine particles 3 or the particle diameter of the attached fine particles 6 is small. At this time, the color tone of the thermosensitive coloring material layer is adjusted to the core portion 4 of the composite fine particles 3.
Is determined by the absorption wavelength of surface plasmon. On the other hand, by applying a certain amount of heat or more, the shell 5
When the thickness of the fine particles or the particle diameter of the attached fine particles 6 is increased, the surface plasmon absorption of the composite fine particles 3 becomes remarkable.
The color tone of the entire device is determined by the complementary color of the absorption of the composite fine particles. The surface plasmon absorption spectrum of the composite fine particles is different from the surface plasmon absorption of the fine particles in the core portion and the surface plasmon absorption of the metal fine particles constituting the shell portion, and depends on the thickness of the shell 5 or the particle size of the attached fine particles 6. It changes greatly. For this reason, the color of the thermosensitive coloring element of the present invention can not only change the luminance by the application of heat but also change the color tone greatly. For this reason, it is possible to more clearly evaluate the temperature history as compared with a conventional thermosensitive coloring device.

The base material is preferably at least one selected from metal, plastic, cloth, paper and glass.

<Second Thermosensitive Coloring Element> The second thermosensitive coloring element of the present invention will be described below.

The second thermosensitive coloring device of the present invention comprises:
A heat-sensitive coloring material disposed on the base;

FIG. 4 shows a cross section of the structure of the produced thermosensitive coloring device. In FIG. 4, reference numeral 9 denotes a substrate, and 2 denotes a matrix material. Fine particles 1, 8 composed of at least two or more simple metal elements are contained in the matrix material.
Are dispersed. The application of heat increases the particle size of each metal fine particle and develops color by showing surface plasmon absorption. Since the coloring characteristics are different depending on each metal element, the color tone of the element greatly changes during the coloring. For this reason,
It is possible to provide a thermosensitive coloring device accompanied by a large change in coloring color tone, and more quantitative temperature history evaluation becomes possible.

Examples of each component such as a metal and a matrix substance in the thermosensitive coloring material are as described above.

The method of disposing the thermosensitive coloring material on the substrate and the amount of the disposing are in accordance with the embodiment of the first thermosensitive coloring element.

The base material is preferably at least one selected from metal, plastic, cloth, paper and glass.

<Method of Manufacturing First Thermosensitive Coloring Element> A first method of manufacturing a thermosensitive coloring element of the present invention will be described below.

First, a mixture containing a metal ion, an α-hydrogen-containing alcohol, and a matrix-forming material is prepared and stirred.

Next, the mixture is irradiated with a first ultraviolet ray or gamma ray. By the photoreduction reaction, the metal ions are reduced to metal atoms, and the metal particles are dispersed in the matrix material. The generated metal fine particles are core fine particles that form the core of the composite fine particles at the end of the final step.

Next, a metal ion different from the metal ions contained in the mixture is added to the mixture.

Next, the above mixture is placed on a substrate.
The arrangement method and the arrangement amount on the substrate are based on the embodiment of the first thermosensitive coloring element.

Next, the thermosensitive coloring material layer disposed on the substrate is irradiated with ultraviolet rays or γ rays for the second time, and the metal ions are photoreduced with alcohol. Since the fine nuclear particles formed by the first irradiation act as a catalyst for the photoreduction reaction by the second irradiation, the reduction reaction occurs at a high probability on the surface of the fine nuclear particles. For this reason, composite fine particles in which another type of metal element forms a shell structure over the entire surface of the metal fine particles are formed.

The details of the mixture, each constituent element of the substrate, the drying treatment, the conditions for the irradiation of the ultraviolet rays or γ rays twice, and the mixing ratio of the metal ions are as described above.

Thus, the thermosensitive coloring device of the present invention is manufactured. Since the thermosensitive coloring element develops color by the application of heat and light, it is preferable that the thermosensitive coloring element be stored immediately after production under low-temperature, dark place conditions.

When heat is applied to the thermosensitive coloring element produced by the above method, color development based on surface plasmon absorption occurs. The surface plasmon absorption wavelength exhibited by the composite fine particles is different from the absorption exhibited by a single metal fine particle, and the absorption wavelength continuously changes as the size ratio between the core portion and the shell portion changes. In addition, the change in the coloring luminance with the application of heat is the same as in the conventional thermosensitive coloring element. For this reason, the thermosensitive coloring device manufactured by the manufacturing method of the present embodiment shows a clear change in the temperature history compared with the conventional device, and enables more clear temperature history evaluation.

In the above embodiment, the first ultraviolet light,
Alternatively, irradiation with γ-rays was performed before the step of arranging the mixture containing metal ions on the substrate. However, even when the order of the steps was reversed, a similar thermosensitive coloring element can be produced. . In this case, the first ultraviolet ray or γ
Irradiation of the radiation is performed on the substrate on which the mixture is arranged. A mixture containing a different type of metal ion than the metal ion disposed on the substrate is prepared as a second mixture. The second mixture includes an α-hydrogen containing alcohol, a matrix forming material. The first mixture is arranged, the second mixture is arranged on the substrate which has been irradiated once with ultraviolet light or γ-ray, and the second irradiation with ultraviolet light or γ-ray is performed.

<Method of Manufacturing Second Thermosensitive Coloring Element> A second method of manufacturing a thermosensitive coloring element of the present invention will be described below.

First, a mixture containing a metal ion, an α-hydrogen-containing alcohol, and a matrix-forming material is prepared and stirred.

Next, the mixture is first irradiated with ultraviolet rays or γ rays. The metal fine particles generated in this step are:
The core portion of the composite fine particles generated in the thermosensitive coloring material at the end of the final step is constituted.

Next, a metal ion different from the metal ions contained in the mixture and a surfactant are added to the mixture.

Next, the above mixture is placed on a substrate.
Next, the thermosensitive coloring material layer disposed on the substrate is irradiated with ultraviolet light or γ-ray for the second time, and the metal ions are photoreduced with alcohol. By introducing the surfactant into the thermosensitive coloring material, the effect of the metal fine particles generated by the first photoreduction reaction acting as a catalyst is reduced. For this reason, the probability that the metal fine particles generated by the second photoreduction reaction cover the entire surface of the core fine particles as a shell decreases. As a result, a composite fine particle structure in which the metal fine particles adhere to the surface of the nuclear metal fine particles is formed.

The selection of the mixture and the surfactant, the components of the substrate, the method of disposing the thermosensitive coloring material on the substrate, the disposition amount, the drying treatment, the irradiation conditions of the ultraviolet ray or γ-ray twice, the metal ion Details such as the mixing ratio are as described above.

It is needless to say that the surfactant can be introduced into the mixture before the first irradiation with ultraviolet rays or gamma rays. However, the introduction of the surfactant is preferably performed after the first photoreduction reaction step to reduce the reaction rate of the photoreduction reaction.

Thus, the thermosensitive coloring device of the present invention is manufactured. Since the thermosensitive coloring element develops color by the application of heat and light, it is preferable that the thermosensitive coloring element be stored immediately after production under low-temperature, dark place conditions.

When heat is applied to the thermosensitive coloring element produced by the above method, coloring based on surface plasmon absorption occurs. The surface plasmon absorption wavelength exhibited by the composite fine particles is different from the absorption exhibited by a single metal fine particle, and the absorption wavelength continuously changes as the size ratio between the core and the non-nucleus changes. In addition, the change in the coloring luminance with the application of heat is the same as in the conventional thermosensitive coloring element. For this reason, the thermosensitive coloring device manufactured by the manufacturing method of the present embodiment shows a clear change in the temperature history compared with the conventional device, and enables more clear temperature history evaluation.

In the above embodiment, the first ultraviolet light,
Alternatively, irradiation with γ-rays was performed before the step of arranging the mixture containing metal ions on the substrate. However, even when the order of the steps was reversed, a similar thermosensitive coloring element can be produced. . In this case, the first ultraviolet ray or γ
Irradiation of the radiation is performed on the substrate on which the mixture is arranged. A mixture containing a different type of metal ion than the metal ion disposed on the substrate is prepared as a second mixture. The second mixture includes an α-hydrogen containing alcohol, a matrix forming material, and a surfactant. Disposing the first mixture;
A second UV light or γ-ray is irradiated on the substrate once irradiated.
Is placed, and then UV or γ-ray 2
The second irradiation is performed. In this case, the same effect can be obtained when the surfactant is contained in the mixture prepared for the first time.

<Method of Manufacturing Third Thermosensitive Coloring Element> A method of manufacturing the third thermosensitive coloring element of the present invention will be described below.

First, a metal ion, a compound containing either a chalcogen element or a halogen element, which reacts with the above-mentioned metal element to produce either a chalcogenide compound or a halogen compound, an α-hydrogen-containing alcohol, and a matrix-forming material Is prepared.

By reacting the prepared mixture by stirring, a fine particle structure composed of either a metal chalcogen compound or a metal halide is formed. The fine particles form the core of the composite fine particle structure that is finally formed.

Next, the mixture is placed on a substrate. Next, the thermosensitive coloring material layer arranged on the base is irradiated with ultraviolet rays or γ-rays. Due to the catalytic effect of the core particles, photoreduction of metal ions to metal atoms occurs at a high probability on the surface of the core particles. As a result, a composite fine particle structure in which the surface of the fine particles of the core is covered with the metal shell structure is formed by being dispersed in the matrix material.

The details of the mixture, each component of the substrate, the method of arranging it on the substrate, the drying treatment, the irradiation conditions of ultraviolet rays or γ rays, etc. are as described above.

Thus, the thermosensitive coloring device of the present invention is manufactured. Since the thermosensitive coloring element develops color by the application of heat and light, it is preferable that the thermosensitive coloring element be stored immediately after production under low-temperature, dark place conditions.

When heat is applied to the thermosensitive coloring element produced by the above method, coloring based on surface plasmon absorption occurs. The surface plasmon absorption wavelength of the composite fine particles changes continuously as the size ratio between the core and the shell changes. In addition, the change in the coloring luminance with the application of heat is the same as in the conventional thermosensitive coloring element. For this reason, the thermosensitive coloring element manufactured by the manufacturing method of the present embodiment shows a clear change in the temperature history compared with the conventional element, and enables a more clear evaluation of the temperature history.

<Fourth Method of Manufacturing Thermosensitive Coloring Element> A method of manufacturing the fourth thermosensitive coloring element of the present invention will be described below.

First, a metal ion, a compound containing either a chalcogen element or a halogen element, which reacts with the above-mentioned metal element to generate either a chalcogenide compound or a halogen compound, an α-hydrogen-containing alcohol, and a matrix-forming material Is prepared.

By reacting the prepared mixture by stirring, a fine particle structure composed of either a metal chalcogen compound or a metal halide is formed. The fine particles form the core of the composite fine particle structure that is finally formed.

Next, the mixture is placed on a substrate. Next, the thermosensitive coloring material layer arranged on the base is irradiated with ultraviolet rays or γ-rays. Due to the catalytic effect of the core particles, photoreduction of metal ions to metal atoms occurs at a high probability on the surface of the core particles. As a result, a composite fine particle structure in which the surface of the fine particles of the core is covered with the metal shell structure is formed by being dispersed in the matrix material.

The details of the mixture, each component of the substrate, the method of arranging it on the substrate, the drying treatment, the irradiation conditions of ultraviolet rays or γ rays, etc. are as described above.

It is needless to say that the surfactant can be introduced into the mixture before the first irradiation with ultraviolet rays or gamma rays. However, the introduction of the surfactant is preferably performed after the first photoreduction reaction step to reduce the reaction rate of the photoreduction reaction.

Thus, the thermosensitive coloring device of the present invention is manufactured. Since the thermosensitive coloring element develops color by the application of heat and light, it is preferable that the thermosensitive coloring element be stored immediately after production under low-temperature, dark place conditions.

When heat is applied to the thermosensitive coloring element produced by the above method, coloring based on surface plasmon absorption occurs. The surface plasmon absorption wavelength of the composite fine particles changes continuously as the size ratio between the core and the non-nucleus changes. In addition, the change in the coloring luminance with the application of heat is the same as in the conventional thermosensitive coloring element. For this reason, the thermosensitive coloring element manufactured by the manufacturing method of the present embodiment shows a clear change in the temperature history compared with the conventional element, and enables a more clear evaluation of the temperature history.

<Fifth Method of Manufacturing Thermosensitive Coloring Element> A fifth method of manufacturing a thermosensitive coloring element of the present invention will be described below.

First, a mixture containing two or more metal ions, an α-hydrogen-containing alcohol, a surfactant, and a matrix-forming material is prepared and stirred.

Next, the mixture is placed on a substrate.
The thermosensitive coloring material layer is disposed directly on the substrate, disposed via an adhesive layer (for example, an epoxy-based adhesive layer), or disposed on the substrate by impregnation. In the case where the thermosensitive coloring material is arranged by bonding, it is necessary to perform a drying treatment.

Next, the mixture placed on the substrate is irradiated with ultraviolet rays or γ-rays. As a result, metal ions are reduced to metal atoms by a photoreduction reaction. Since the generated metal fine particles in which metal atoms are aggregated act as a catalyst when different types of metal ions are photoreduced, a surfactant is introduced into the mixture to reduce this effect. By introducing a surfactant, metal fine particles composed of a single metal element are formed without aggregation of different kinds of metals to form composite fine particles.

The details of the selection of the mixture and the surfactant, the components of the substrate, the drying treatment, the irradiation conditions of the ultraviolet ray or the γ-ray twice, and the mixing ratio of the metal ions are as described above.

Thus, the thermosensitive coloring device of the present invention is manufactured. Since the thermosensitive coloring element develops color by the application of heat and light, it is preferable that the thermosensitive coloring element be stored immediately after production under low-temperature, dark place conditions.

The thermosensitive coloring device produced by the above method was
When heat is applied, it shows color due to surface plasmon absorption.
The complementary color of the superposition of the absorptions of the metal fine particles is the color of the element after color development. Because the aggregation rate of each metal particle is different,
The absorption spectrum changes significantly with the application of heat. Not only does the color development luminance of the element change with the temperature history, but also the color tone of the element changes continuously depending on the temperature history such as the standing temperature and the standing time. For this reason, it is possible to more clearly evaluate the temperature history as compared with a conventional thermosensitive coloring device.

<Thermosensitive element> The thermosensitive element of the present invention will be described below.

FIG. 7 shows a conceptual diagram of the thermosensitive coloring device of the present invention. A thermosensitive coloring material application area 12 is set in the barcode display area 11 of the thermosensitive coloring element attached to the frozen or chilled storage product 10. As shown in FIG. 7A, when no heat is applied, normal barcode information is read and given to the reading device. When heat is applied as shown in FIG. 7B, the thermosensitive coloring material develops a color and displays barcode information different from normal.

In this way, it is possible to evaluate the temperature history in a short time by using the conventionally used bar code reading system.

[0156]

Embodiments of the present invention will be described below. In addition,
The present invention is not limited to these examples.

Example 1 A solution composed of the materials shown in Table 1 below was prepared.

[0158]

[Table 1]

In the above solution, 0.05 g as a metal compound was added.
AgClO4 was added and the mixture was stirred at room temperature for 10 minutes. After the stirring, γ rays were irradiated for 1 minute. At this time, the color of the solution was colorless. In the solution in this state, the particle diameter is 1 n.
It is considered that silver particles of m or less are dispersed. 0.1 g of AuHCl4 was added to this mixed solution. After the mixture was stirred at room temperature for 1 minute, it was cast on a plate and placed at 5 ° C.
For 5 days to obtain a transparent thin yellow gel film having a thickness of 300 μm.

By irradiating this film with ultraviolet rays having a wavelength of 254 nm using a UV lamp, a film discolored to yellow was obtained. UV irradiation intensity is 5mW / cm2
The irradiation time was 1 minute. The ultraviolet irradiation increases the particle size of the silver fine particles, reduces gold ions, and generates fine gold fine particles. When the absorption spectrum was measured, surface plasmon absorption of the silver fine particles was confirmed at a wavelength of about 380 nm.

One of the films was left at room temperature, and the other was stored in a dark place at -20 ° C. After several minutes, the film left at room temperature gradually grew from yellow to reddish and eventually turned red-orange. During this time, the color tone of the film showed a change that could be clearly confirmed with the naked eye. In addition, the degree of color development became visibly deeper as time passed.

In a conventional thermosensitive coloring material, the wavelength change of the absorption peak at the start of coloring and at the completion of coloring is at most 20 nm.
Met. The thermosensitive coloring material described in this example achieved a change in the wavelength of the absorption peak at 150 nm at the start of coloring and at the completion of coloring. In addition, a shift of the absorption peak by as much as 40 nm was obtained after the lapse of 10 minutes and after the lapse of 30 minutes, indicating that the color tone was clearly changed.

FIG. 6 shows the change in absorption spectrum after standing at room temperature.
Shown in For a sufficient time after standing at room temperature, the wavelength 38
The absorption peak near 0 nm was sharp and intense. this is,
By the application of heat, a particle size (number n) showing surface plasmon absorption
m or more). Thereafter, the peak intensity of surface plasmon absorption of the silver fine particles sharply decreased, and the absorption wavelength shifted to the longer wavelength side, and finally shifted to around 520 nm. 520n
The intensity of the absorption peak near m increased 30 minutes after standing at room temperature. The short wavelength side of the wavelength of 520 nm had broad absorption, whereas the long wavelength side hardly had absorption. As a result, the final color reached orange with a strong reddish tinge. Since the surface plasmon absorption peak of silver fine particles disappears and the surface plasmon absorption peak (wavelength of 550 nm) of gold fine particles does not exist,
Finally, it is considered that composite fine particles having a structure in which silver fine particles are nuclei and whose surface is covered with gold are present in the film.

The same γ is applied to the mixed solution not subjected to the drying treatment.
Irradiation with X-rays and ultraviolet light showed similar changes in the absorption spectrum. When a part of the mixed solution developed to the final stage was observed by a TEM photograph, fine particles having a particle size of about 35 nm were dispersed in the matrix material. The shape of the fine particles was almost spherical. Since there are no single gold and silver fine particles, it is considered that composite fine particles are formed.

On the other hand, the film stored at low temperature did not change in color tone and chromaticity during storage for 2 months. When the film after the low-temperature storage was led to room temperature, a color developed from yellow to reddish orange.

Table 2 shows the coloring characteristics at room temperature of the thermosensitive coloring material of this example and comparison with the coloring properties of the conventional thermosensitive coloring material. In the present specification, as a value for evaluating the degree of color development, a change rate of the luminance of a material is defined and used as the color development luminance.

[0167]

[Table 2]

As is clear from the above table, it was found that when the heat-sensitive coloring material of the present invention was compared with the conventional example, a large change in the color tone was obtained during coloring. The change in the color tone allows a more quantitative evaluation of the standing time than conventional materials.

Further, the above materials were heated at 20 ° C., 10 ° C., 0 ° C.,
Each was left for 3 hours in a temperature atmosphere of −10 ° C. and −20 ° C. Table 3 shows the details of the coloring characteristics together with comparison with the conventional material characteristics.

[0170]

[Table 3]

As is clear from the above table, when compared with the conventional thermosensitive coloring material which had a constant color tone independent of the standing temperature, the heat-sensitive material of the present embodiment was accompanied by a clear color tone change depending on the standing temperature. It enables color developing materials and more quantitative evaluation of standing temperature.

The same reaction as described above was confirmed using not only gold and silver but also the above-mentioned various metals. However, considering that the metal with the highest efficiency of the photoreduction reaction by ultraviolet irradiation is gold, and that the color tone and chromaticity are clear, the fine particle structure in which the core is silver and the shell is gold Could show the temperature history change most clearly.

Further, the photoreduction of metal ions was possible by irradiation of both ultraviolet rays and γ rays.

As the matrix forming material, not only the case where the inorganic alkoxide of the above example was used, but also
Even when using any of the organic composite and the resin,
It was possible to obtain similar coloring characteristics.

Example 2 A solution having the composition shown in Table 1 was
0.05 g of AgClO4 was added as a metal compound,
The mixture was stirred at room temperature for 10 minutes. After the stirring, γ rays were irradiated for 1 minute. At this time, the color of the solution was colorless. It is considered that silver fine particles having a particle size of 1 nm or less are dispersed in the solution in this state. 0.1 g to this mixed solution
Of AuHCl4 was added. After the mixture was stirred at room temperature for 1 minute, it was applied to a 100 μm thick kraft paper (substrate) by a spin coating method. After the application, a drying treatment was performed at 5 ° C. for 1 day to obtain a laminate having a transparent light yellow thin gel film having a thickness of about 0.5 μm on a substrate.

A wavelength of 2 was applied to this laminate using a UV lamp.
Irradiation with an ultraviolet ray of 54 nm yielded a film that turned yellow. UV irradiation intensity is 5mW / cm2
The irradiation time was 2 minutes.

One of the laminates was left at room temperature, and the other was stored in a dark place at −20 ° C. The laminate left at room temperature gradually grew from yellow to reddish after several tens of minutes, and finally turned red-orange. During this time,
The color tone of the laminate showed a change that was clearly visible to the naked eye. In addition, the degree of color development became visibly deeper as time passed. The color change of the laminate showed almost the same characteristics as the color change of the gel film described in Example 1. From this, it is considered that the composite fine particles are dispersed in the film disposed on the kraft paper, and the particle diameter is irreversibly changed by the application of heat.

On the other hand, the film stored at low temperature did not change in color tone and chromaticity during storage for 2 months. When the film after the low-temperature storage was led to room temperature, a color developed from yellow to reddish orange.

The same coloring characteristics as described above were obtained not only in the above example using kraft paper but also in any case using a material selected from metals, plastics, cloths and papers as the base material.

Example 3 To a mixed solution shown in Table 1 were added 0.02 g of AuHCl4 as a metal compound and 0.01 g of Na2S as a chalcogenide compound, and the mixture was stirred at room temperature for 1 minute. At this point, the color of the solution was clear yellow-green. It is considered that Au2S fine particles having a particle diameter of several nm or less are dispersed in the solution in this state. The mixture was cast on a flat plate and dried at 5 ° C. for 5 days to obtain a transparent thin yellow-green gel film having a thickness of 300 μm.

By irradiating this film with ultraviolet rays having a wavelength of 254 nm using a UV lamp, a film turned yellow-green was obtained. UV irradiation intensity is 5mW / cm
In 2, the irradiation time was 30 seconds. By the ultraviolet irradiation, gold ions are reduced, and fine gold fine particles are generated.

One of the films was left at room temperature and the other was stored in a dark place at -20 ° C. The film left at room temperature gradually increased from green to reddish after several tens of minutes, turned brownish, and finally turned dark green. During this time, the color tone of the film showed a change that could be clearly confirmed with the naked eye. In addition, the degree of color development became visibly deeper as time passed.

When the absorption spectrum of the film immediately after standing at room temperature was measured, it was confirmed that the surface plasmon absorption of the fine gold particles was observed at a wavelength of about 540 nm.

On the other hand, a peak appeared on a long wavelength side different from the surface plasmon absorption peak of the fine gold particles. After the absorption peak appeared at a wavelength of about 700 nm, it moved to about 900 nm for several tens of minutes toward the longer wavelength side with the passage of the standing time. Thereafter, as the time elapses, the absorption peak wavelength moves to the shorter wavelength side up to 650 nm while increasing the absorption intensity. This absorption is considered to be caused by plasmon absorption of fine particles having a structure in which Au2S fine particles are used as a core portion and a shell portion made of gold is provided around the fine particles. Table 4 shows the dependence of the peak wavelength of surface plasmon absorption of the composite fine particles on the standing time at room temperature. In addition, the surface plasmon absorption intensity of the gold fine particles increased with the passage of time.

[0185]

[Table 4]

On the other hand, the film stored at low temperature did not change in color tone and chromaticity during storage for 2 months. When the film after storage at low temperature was brought to room temperature, it exhibited the same color change as the above change.

The change in color tone was confirmed not only when the standing time was changed but also when the standing temperature was changed. When the color tone changes according to the degree of application of heat, more quantitative temperature history evaluation becomes possible.

The same reaction as described above was confirmed not only with gold and silver but also with the various metals described above. Also,
As an element that reacts with metal to form the core of fine particles,
Chalcogen elements, halogen group elements, etc. could be used. Further, even when the metal element constituting the core portion and the metal element constituting the shell portion were different, similar coloring characteristics were confirmed. However, considering that the metal with the highest efficiency of the photoreduction reaction by ultraviolet irradiation is gold, and that the color tone and chromaticity are clear, the core is composed of a chalcogenide compound of gold and the shell is composed of gold. Particle configuration could most clearly show a change in temperature history.

Further, not only the case where the inorganic alkoxide of the above example was used as the matrix forming material,
Even when an organic composite or a resin is used, similar coloring characteristics can be obtained.

Example 4 To a mixed solution shown in Table 1 was added 0.02 g of AuHCl 4 as a metal compound and 0.01 g of Na 2 S as a chalcogenide compound, and the mixture was stirred at room temperature for 1 minute. At this point, the color of the solution was clear yellow-green. It is considered that Au2S fine particles having a particle diameter of about several nm are dispersed in the solution in this state. The mixture was applied on kraft paper (substrate) having a thickness of 100 μm by a spin coating method. After the application, the coating was dried at 5 ° C. for 1 day to obtain a laminate having a transparent thin yellow-green thin film gel film having a thickness of about 0.5 μm on the substrate.

A wavelength of 2 was applied to this laminate using a UV lamp.
By irradiating with a 54 nm ultraviolet ray, a laminate which turned yellowish green was obtained. UV irradiation intensity is 5mW / cm2
The irradiation time was 30 seconds.

One of the laminates was left at room temperature, and the other was stored in a dark place at -20 ° C. The laminate left at room temperature began to show color and luminance changes after a sufficient time. After several tens of minutes, the color gradually increased from green to reddish, then changed to brownish color, and finally to dark green. During this time, the color tone of the laminate showed a change that could be clearly confirmed with the naked eye. In addition, the degree of color development became visibly deeper as time passed. The dependence of the color tone change on the standing time at room temperature was similar to that of the gel film described in Example 3.

On the other hand, the laminate stored at a low temperature did not change in color tone and luminance during storage for 2 months.
When the film after storage at low temperature was brought to room temperature, it exhibited the same color change as the above change.

The same coloring characteristics as described above were obtained not only in the above example using kraft paper but also in any case using a material selected from metals, plastics, cloths and papers as the base material.

Example 5 To the mixed solution shown in Table 1 was added 0.05 g of AgClO 4 as a metal compound, and the mixture was stirred at room temperature for 10 minutes. After the stirring, γ rays were irradiated for 1 minute. At this time, the color of the solution was colorless. Silver ions are photoreduced by γ-ray irradiation, and silver atoms are generated. γ
It is considered that silver fine particles having a particle diameter of 1 nm or less are dispersed in the solution after the irradiation with the rays.

0.1 g of AuH was added to the mixed solution after γ-ray irradiation.
Cl4 and 20 mg of surfactant were added. As a surfactant, an alkylbenzene sulfonate having 12 carbon atoms (RC6H4SO3Na, R = C12) was used. The mixture was stirred at room temperature for 1 minute, then cast on a plate,
By performing a drying treatment at 5 ° C. for 5 days, a thickness of 300 μm is obtained.
m clear yellow gel film was obtained.

By irradiating this film with ultraviolet light having a wavelength of 254 nm using a UV lamp, a film discolored to yellow was obtained. UV irradiation intensity is 5mW / cm2
The irradiation time was 2 minutes. The ultraviolet irradiation increases the particle size of the silver fine particles, reduces gold ions, and generates fine gold fine particles. When the absorption spectrum was measured, surface plasmon absorption of the silver fine particles was confirmed at a wavelength of about 380 nm.

One of the films was left at room temperature and the other was stored in a dark place at -20 ° C. After several minutes, the film left at room temperature gradually grew from yellow to reddish and eventually turned red-orange. During this time, the color tone of the film showed a change that could be clearly confirmed with the naked eye. In addition, the degree of color development became visibly deeper as time passed.

For a sufficient time after standing at room temperature, the absorption peak near the wavelength of 380 nm becomes sharper and stronger with the passage of time. This is considered to be due to the fact that the concentration of silver fine particles having a particle size (several nm or more) exhibiting surface plasmon absorption increases due to the application of heat. Thereafter, the peak intensity of the surface plasmon absorption of the silver fine particles sharply decreases, and the absorption wavelength shifts to the longer wavelength side, and finally moves to around 530 nm. The absorption peak intensity around 530 nm is 1 after standing at room temperature.
It increased after the passage of time. Also, broad absorption exists on the short wavelength side of the wavelength of 530 nm, whereas almost no absorption exists on the long wavelength side. For this reason, the final attained color is orange with a strong red tint.

The same γ was applied to the mixed solution without performing the drying treatment.
Irradiation with X-rays and ultraviolet light showed similar changes in the absorption spectrum. When a part of the mixed solution developed to the final stage was observed by a TEM photograph, fine particles having a particle size of about 20 nm were dispersed in the matrix material. The shape of the fine particles was not constant, and many of them had irregularities on the surface. Since there is no surface plasmon peak represented by simple gold and silver fine particles, it is considered that composite fine particles are formed.

It is considered that the surfactant introduced into the mixed solution is adsorbed on the surface of the silver fine particles. Since the silver fine particles have a strong tendency to be electrically positively charged, an attractive force acts on the electrically negative gold chloride ion. For this reason, the silver fine particles act as a catalyst in the photoreduction reaction of gold ions, and gold is reduced while forming a shell structure on the surface of the silver fine particles as a nucleus. However, the surfactant introduced in the present example has an effect of electrically adsorbing on the surface of silver atoms and reducing the function as a catalyst. For this reason, in the material produced in this example, spherical composite fine particles whose entire surface was completely covered were not formed, and it was considered that composite fine particles in which two types of simple metal fine particles were bonded were formed. It is.

On the other hand, the film stored at a low temperature did not change in color tone and chromaticity during storage for 2 months. When the film after the low-temperature storage was led to room temperature, a color developed from yellow to reddish orange.

In this embodiment, an example in which an alkylbenzene sulfonate is used as a surfactant has been described. However, from the group of materials having a carboxylic acid group, a sulfonic acid group, a sulfate ester group, a phosphate ester group, and a phosphonate group, A similar effect was obtained with at least one selected use.

Further, when the amount of the surfactant in the mixture was increased, the aggregating speed of each single metal fine particle was decreased, and the coloring speed was decreased. Therefore, by adjusting the amount of surfactant,
It was possible to obtain desired coloring characteristics.

Example 6 To a mixed solution shown in Table 1 was added 0.05 g of AgClO 4 as a metal compound, and the mixture was stirred at room temperature for 10 minutes. After the stirring, γ rays were irradiated for 1 minute. At this time, the color of the solution was colorless. Silver ions are photoreduced by γ-ray irradiation, and silver atoms are generated. γ
It is considered that silver fine particles having a particle diameter of 1 nm or less are dispersed in the solution after the irradiation with the rays.

[0206] 0.1 g of AuH was added to the mixed solution after γ-ray irradiation.
Cl4 and 20 mg of surfactant were added. As a surfactant, an alkylbenzene sulfonate having 12 carbon atoms (RC6H4SO3Na, R = C12) was used. After the mixture was stirred at room temperature for 1 minute, it was applied to a 100 μm thick kraft paper (substrate) by a spin coating method.
After coating, dry at 5 ° C for 5 days, thickness about 0.3mm
Having a transparent thin yellow thin gel film on a substrate.

A wavelength of 2 nm was applied to this laminate using a UV lamp.
By irradiating with 54 nm ultraviolet rays, the color was changed to yellow. The ultraviolet irradiation intensity was 5 mW / cm 2 and the irradiation time was 2 minutes. The ultraviolet irradiation increases the particle size of the silver fine particles, reduces gold ions, and generates fine gold fine particles. After the irradiation of the ultraviolet rays, the laminated body became prominent in surface plasmon absorption of the grown silver fine particles and turned yellow.

One of the laminates was left at room temperature, and the other was stored in a dark place at −20 ° C. The laminate left at room temperature gradually grew from yellow to reddish after several tens of minutes, and finally turned reddish orange.
During this time, the color tone of the film showed a change that could be clearly confirmed with the naked eye. In addition, the degree of color development became visibly deeper as time passed.

On the other hand, the laminate stored at low temperature did not change in color tone and luminance during storage for 2 months.
When the layered product after the low-temperature storage was led to room temperature, the color developed from yellow to reddish orange. The low-temperature storage had no effect on the coloring characteristics, and the same characteristics were obtained after the low-temperature storage.

In this embodiment, an example in which an alkylbenzene sulfonic acid salt is used as a surfactant has been described. However, from the group of materials having a carboxylic acid group, a sulfonic acid group, a sulfate ester group, a phosphate ester group, and a phosphonate group, A similar effect was obtained with at least one selected use.

Further, when the amount of the surfactant in the mixture was increased, the aggregating speed of each single metal fine particle was reduced, and the color developing speed was reduced. Therefore, by adjusting the amount of surfactant,
It was possible to obtain desired coloring characteristics.

Example 7 0.02 g of AuHCl 4 as a metal compound and 0.01 g of Na 2 S as a chalcogenide compound were added to the mixed solution shown in Table 1, and the mixture was stirred at room temperature for 1 minute. At this point, the color of the solution was clear yellow-green. It is considered that Au2S fine particles having a particle diameter of several nm or less are dispersed in the solution in this state. Next, 20 mg of a surfactant was added to the mixed solution. As a surfactant, an alkylbenzene sulfonate having 12 carbon atoms (RC6H4SO3Na, R = C12) was used. The mixture after addition of the activator was cast on a flat plate and dried at 5 ° C. for 5 days to give a thickness of 30%.
A 0 μm clear, pale yellow-green gel film was obtained.

By irradiating this film with ultraviolet rays having a wavelength of 254 nm using a UV lamp, a film turned yellow-green was obtained. UV irradiation intensity is 5mW / cm
In 2, the irradiation time was 30 seconds. By the ultraviolet irradiation, gold ions are reduced, and fine gold fine particles are generated.

This film was left at room temperature on one side and stored in the dark at -20 ° C. on the other side. The film left at room temperature gradually grew from green to reddish after several tens of minutes, once turned brownish, and finally turned dark blue-green through green. During this time, the color tone of the film showed a change that could be clearly confirmed with the naked eye. In addition, the degree of color development became clearer as time passed. It is considered that composite fine particles having Au2S fine particles as nuclei and gold fine particles adhered to a part of the nucleus surface are formed in the film. Table 5 shows the dependence of the coloring property of the thermosensitive coloring material of this example on the standing time at room temperature together with the coloring property of the conventional material.

[0215]

[Table 5]

As is clear from Table 5, the thermosensitive coloring material of this example exhibited coloring characteristics accompanied by a clear change in color tone as compared with the conventional material.

The film stored at a low temperature did not show any color change for two months, but when introduced into an atmosphere at room temperature, it exhibited a color-forming reaction similar to the above-described color-forming characteristics.

In comparison with the thermosensitive coloring material of Example 3 in which no surfactant was introduced, the thermosensitive coloring material of this example was:
Two characteristics were obtained, that is, a reduction in the reaction rate of thermosensitive coloring and a change in the ultimate color tone from green to bluish green. This is considered to be due to the fact that the introduced surfactant binds to the surface of the Au2S fine particles and reduces the effect of acting as a catalyst during the photoreduction reaction of gold ions. Due to the reduction of the catalytic effect, the reduction reaction rate of gold ions is reduced, and the color development rate is also reduced. For this reason, an effective thermosensitive coloring material can be provided when milder thermosensitive coloring properties are required. In addition, it is possible to provide a thermosensitive coloring material with a wider range of color tone change due to the change in the final color tone.

Further, the above film was treated at 20 ° C., 10 ° C., 0 °
Each was left for 3 hours in a temperature atmosphere of -10 ° C, -10 ° C, and -20 ° C. Table 6 shows the details of the coloring characteristics together with a comparison with the conventional example.

[0220]

[Table 6]

As is clear from the above table, the heat-sensitive coloring material of this example achieved the heat-sensitive coloring characteristics accompanied by a distinct change in the color tone as compared with the conventional material which could only develop a certain color tone. With this characteristic, it is possible to evaluate the leaving temperature more clearly.

From the above characteristics, the thermosensitive coloring material of this example can achieve the thermosensitive coloring property with a distinct change in color tone,
It enables a clearer evaluation of temperature history than conventional materials.

The photoreduction of metal ions was possible by irradiation of both ultraviolet rays and γ rays.

Further, not only the case where the inorganic alkoxide of the above example was used as the matrix forming material,
Even when using any of the organic composite and the resin,
It was possible to obtain similar coloring characteristics.

Example 8 To a mixed solution shown in Table 1 was added 0.02 g of AuHCl 4 as a metal compound and 0.01 g of Na 2 S as a chalcogenide compound, and the mixture was stirred at room temperature for 1 minute. At this point, the color of the solution was clear yellow-green. It is considered that Au2S fine particles having a particle diameter of several nm or less are dispersed in the solution in this state. Next, 20 mg of a surfactant was added to the mixed solution. An alkylbenzene sulfonate having 12 carbon atoms (RC6H4SO3Na, R = C12) was used as a surfactant. The mixture after addition of the activator was cast on kraft paper (substrate) having a thickness of 100 μm and dried at 5 ° C. for 5 days to form a transparent thin yellow-green gel film having a thickness of 300 μm on the substrate. Was obtained.

A wavelength of 2 nm was applied to this laminate using a UV lamp.
By irradiating with a 54 nm ultraviolet ray, a laminate which turned yellowish green was obtained. UV irradiation intensity is 5mW / cm2
The irradiation time was 30 seconds. By the ultraviolet irradiation, gold ions in the film are reduced, and fine gold particles are generated.

One of the laminates was left at room temperature, and the other was stored in a dark place at −20 ° C. The laminate that has been left at room temperature gradually increases from green to reddish after several tens of minutes,
Once it turned brownish, it turned green and finally dark blue-green. The color tone of the laminate during color development is
The changes were clearly visible to the naked eye. In addition, the degree of color development became clearer as time passed. It is considered that composite fine particles having Au2S fine particles as nuclei and gold fine particles adhered to a part of the nucleus surface are formed in the film.

In comparison with the thermosensitive coloring device of Example 4 in which no surfactant was introduced, the thermosensitive coloring device of this embodiment was as follows:
Two characteristics were obtained, that is, a reduction in the reaction rate of thermosensitive coloring and a change in the ultimate color tone from green to bluish green. This is considered to be due to the fact that the introduced surfactant binds to the surface of the Au2S fine particles and reduces the effect of acting as a catalyst during the photoreduction reaction of gold ions. Due to the reduction of the catalytic effect, the reduction reaction rate of gold ions is reduced, and the color development rate is also reduced. For this reason, it is possible to provide a particularly effective thermosensitive coloring element when milder thermosensitive coloring properties are required. Further, the change in the final color tone makes it possible to provide a thermosensitive coloring element with a wider range of color tone changes.

(Example 9) 0.05 g of AgClO4, 0.02 g as a metal compound was added to the mixed solution shown in Table 1.
Of AuHCl4, 35 mg of surfactant was added and stirred at room temperature for 10 minutes. As a surfactant, an alkylbenzene sulfonate having 12 carbon atoms (RC6H4SO3Na,
R = C12) was used. The mixture after addition of the activator was cast on a flat plate and dried at 5 ° C. for 5 days to obtain a transparent, pale yellow gel film having a thickness of 300 μm.

By irradiating this film with ultraviolet light having a wavelength of 254 nm using a UV lamp, a transparent discolored film was obtained. UV irradiation intensity is 5mW / cm2
The irradiation time was 2 minutes.

By irradiation with ultraviolet rays, silver ions and gold ions are photoreduced to form silver fine particles and gold fine particles. The particle size of each fine particle is considered to be about 1 nm or less, and since surface plasmon absorption does not occur at this point, the color of the film changes to transparent. Since the introduction of the surfactant does not form the composite fine particles, only the single metal fine particles are formed.

One of the two films was left at room temperature, and the other was stored in a dark place at -20 ° C. The film that has been left at room temperature will turn brownish after several ten minutes,
After an hour, it began to turn deep blue-purple. Eventually, it turned darker purple. During color development, the color tone of the film showed a change that was clearly visible to the naked eye. In addition, the degree of color development became clearer as time passed.

When the absorption spectrum of the film during color development was measured, the surface plasmon absorption of the silver fine particles became remarkable immediately after the start of color development, and thereafter, the intensity of the surface plasmon absorption of the gold fine particles became dominant.

The elapsed time after standing at room temperature, the color tone, and the surface plasmon peak (38
0 nm) and the surface plasmon peak (550 n) of the fine gold particles.
Table 7 shows the strength comparison of m).

[0235]

[Table 7]

On the other hand, the film stored at low temperature did not change in color tone and chromaticity during storage for 2 months. When the film after storage at low temperature was brought to room temperature, it exhibited a color-forming reaction having characteristics similar to the above-described color-forming characteristics.

As is clear from the above table, the thermosensitive coloring material of this example achieved the thermosensitive coloring characteristics accompanied by a clear change in color tone by utilizing the surface plasmon absorption of two kinds of metal fine particles.

The film produced by the above method was
0 ° C, 10 ° C, 0 ° C, -10 ° C, -20 ° C
Left for hours. Table 8 shows details of the coloring characteristics after standing.

[0239]

[Table 8]

As is clear from the above table, the heat-sensitive coloring material of this example achieved the heat-sensitive coloring characteristics with a clear change in the color tone, as compared with the conventional material which could only develop a color with a constant tone. With this characteristic, it is possible to evaluate the leaving temperature more clearly.

From the above characteristics, the thermosensitive coloring material of this example achieves the thermosensitive coloring property with a clear change in color tone,
It enables a clearer evaluation of temperature history than conventional materials.

The same reaction as described above was confirmed not only by using gold and silver but also by using the above-mentioned various metals. However, the metals with high efficiency of the photoreduction reaction by ultraviolet irradiation are gold and silver, and the color tone and chromaticity are clear,
In view of the above, the result that it is preferable to use two kinds of materials, gold and silver, was obtained.

In addition, photoreduction of metal ions was possible by irradiation with both ultraviolet rays and γ rays.

In addition to the case where the inorganic alkoxide of the above example was used as the matrix forming material,
Even when using any of the organic composite and the resin,
It was possible to obtain similar coloring characteristics.

(Example 10) In the mixed solution shown in Table 1,
0.05 g of AgClO4, 0.02 as a metal compound
g AuHCl4, 35 mg surfactant was added and stirred at room temperature for 10 minutes. As a surfactant, carbon number 12
Alkylbenzene sulfonate (RC6H4SO3N
a, R = C12) was used. The mixture after adding the activator is
By casting on kraft paper (substrate) and drying at 5 ° C. for 5 days, a laminate having a 300 μm thick transparent thin yellow gel film formed on the substrate was obtained.

A wavelength of 2 nm was applied to this laminate using a UV lamp.
By irradiating with 54 nm ultraviolet rays, the color tone of the film portion of the laminate became transparent. UV irradiation intensity is 5m
The irradiation time was 2 minutes at W / cm2.

By irradiation with ultraviolet rays, silver ions and gold ions are photoreduced to form silver fine particles and gold fine particles. It is considered that the particle diameter of each fine particle immediately after the ultraviolet irradiation is about 1 nm or less. Since the introduction of the surfactant stops the formation of the composite fine particles, the fine particles formed are considered to be composed of a single metal.

One of the two kinds of the laminated bodies was left at room temperature, and the other was stored in a dark place at -20 ° C. The laminate that had been left at room temperature became brownish after several tens of minutes, and began to change to deep blue-purple after one hour. Eventually, it turned darker purple. During color development, the color tone of the laminate showed a change that was clearly visible to the naked eye. Also,
As time passed, the degree of color development became clearly deeper.

On the other hand, the laminate stored at a low temperature did not change in color tone and chromaticity during storage for 2 months.
When the layered product after storage at low temperature was brought to room temperature, a color-forming reaction having characteristics similar to the above-described color-forming characteristics was exhibited. Compared with a conventional thermosensitive coloring device that can only develop a color tone that is independent of the storage time, the thermosensitive coloring device of the present embodiment enables a clearer evaluation of the storage time.

Further, when the three kinds of laminates produced by the above method were stored at 20 ° C., 10 ° C., and 0 ° C. for 3 hours, the respective layers developed dark black, purple, and brown in different colors. Compared with a conventional thermosensitive coloring device that can only produce a color tone regardless of the storage temperature, the thermosensitive coloring device of the present embodiment enables a clearer evaluation of the storage temperature.

The same reaction as described above was confirmed not only with gold and silver but also with the various metals described above. However, the metals with high efficiency of the photoreduction reaction by ultraviolet irradiation are gold and silver, and the color tone and chromaticity are clear,
In view of the above, the result that it is preferable to use two kinds of materials, gold and silver, was obtained.

In addition, photoreduction of metal ions was possible by irradiation with both ultraviolet rays and γ rays.

In addition to the case where the inorganic alkoxide of the above example was used as the matrix forming material,
Even when using any of the organic composite and the resin,
It was possible to obtain similar coloring characteristics.

(Example 11) In the mixed solution shown in Table 1,
0.18 g of HAuCl4 was added as a metal compound,
The mixture was stirred at room temperature for 10 minutes. Next, the above-mentioned mixed solution was applied to a display area of a bar code attached to a general product. The application area is between the two leftmost bars of the barcode display area. The bar code is then
After drying for a day, UV irradiation was performed at room temperature using a UV lamp at an intensity of 5 mW / cm 2 for 1 minute.

Immediately after the irradiation with the ultraviolet rays, when the barcode information produced by the above method was read by a barcode reader, normal barcode information was read.

The bar code was brought to -20 ° C. Barcodes stored at low temperature showed normal barcode information.

After storage at −20 ° C. for 2 months, when the bar code was led to room temperature, the area where the thermosensitive coloring material was applied showed purple color over time. Up to 30 minutes after standing at room temperature, color development was such that it was faintly visible to the naked eye. In this state, the bar code information remains normal.
On the other hand, when the room temperature standing time exceeded 45 minutes and the color development was clearly confirmed, it became impossible to read the barcode information. This is because the application of heat of a certain amount or more causes the color of the thermosensitive coloring material application area to develop color, and indicates different barcode information.

The three types of barcodes produced by the above method were left at temperatures of 20 ° C., 10 ° C., and 0 ° C., respectively. If bar code information is read after 3 hours, 0
Compared to a bar code left at 20 ° C. giving normal bar code information, it was impossible to read bar code information from a bar code left at 20 ° C. or 10 ° C. This is because the application of heat of a certain amount or more causes the color of the thermosensitive coloring material application area to develop color, and indicates different barcode information.

As described above, by arranging the thermosensitive coloring material in the barcode display area by the above-described method, it is possible to read the thermosensitive history information simultaneously with reading the barcode information. As a result, it is also possible to quickly check a product that has undergone an abnormal temperature history at the time of sale.

In the embodiment, the application area of the thermosensitive coloring material is set to be between the bars at the left end of the barcode. However, it is needless to say that the embodiment of applying the thermosensitive coloring material to other parts is also possible.

[0261]

As described above, according to the first thermosensitive coloring material of the present invention, the composite fine particles dispersed in the matrix material exhibit a coloring with a distinct color tone change by the application of heat. It is possible to provide a thermosensitive coloring material capable of managing the temperature history more quantitatively than the material.

According to the second thermosensitive coloring material of the present invention, at least two or more kinds of different metal fine particles dispersed in a matrix material grow by application of heat, and exhibit a color development accompanied by a clear change in color tone. This makes it possible to provide a thermosensitive coloring material capable of performing more quantitative temperature history management as compared with conventional materials.

In the thermosensitive coloring material of the present invention, the core of the composite fine particles is at least one metal selected from gold, platinum, silver, copper, tin, rhodium, palladium, or iridium, or an oxide of the metal. , Sulfide,
Selenide, telluride, fluoride, chloride, bromide,
According to a preferred example, which is composed of any one of iodides and adheres to the core portion, and in which the shell portion is composed of any of the above metals, the photoreduction reaction speed of metal ions is high and the production is easy. In addition, it is possible to provide a thermosensitive coloring material having advantages such as clear coloring.

According to the first method for producing a thermosensitive coloring material of the present invention, a metal ion, an α-hydrogen-containing alcohol,
And preparing a mixture containing a matrix-forming material, irradiating ultraviolet rays or γ rays, preparing a metal ion different from the metal ions into the mixture, irradiating a second ultraviolet ray or γ rays, The inclusion makes it possible to provide a thermosensitive coloring material having a large change in color tone.

According to the second method for producing a thermosensitive coloring material of the present invention, a metal ion, an α-hydrogen-containing alcohol,
And a step of preparing a mixture containing the matrix-forming material, a step of irradiating ultraviolet rays or γ rays, a step of preparing a metal ion different from the metal ions, and a surfactant in the mixture, a second ultraviolet ray, or γ rays. By including the step of irradiating, it is possible to provide a thermosensitive coloring material having a large change in color tone.

According to the third method for producing a thermosensitive coloring material of the present invention, a metal ion, an α-hydrogen-containing alcohol,
And a step of preparing a mixture containing a matrix-forming material, a step of adding either a chalcogen compound or a halide to the mixture, and a step of irradiating with ultraviolet light or γ-rays. It becomes possible to provide a coloring material.

According to the fourth method for producing a thermosensitive coloring material of the present invention, a metal ion, an α-hydrogen-containing alcohol,
And a step of preparing a mixture containing a matrix-forming material, a step of adding a chalcogen compound or a halide to the mixture, and a surfactant, and a step of irradiating ultraviolet light or γ-rays. It is possible to provide a thermosensitive coloring material having a large change in color tone.

According to the fifth method for producing a thermosensitive coloring material of the present invention, at least two types of metal ions, α
-By preparing a mixture containing a hydrogen-containing alcohol, a matrix-forming material, and a surfactant, and irradiating with ultraviolet rays or γ-rays, it is possible to provide a thermosensitive coloring material having a large change in coloring color tone. Become.

Further, according to the first thermosensitive coloring element of the present invention, the thermosensitive coloring material layer disposed on the substrate and containing the composite fine particles dispersed in the matrix substance is accompanied by a clear change in color tone due to the application of heat. By exhibiting color development, it becomes possible to provide a thermosensitive coloring element capable of performing more quantitative temperature history management than conventional elements.

According to the second thermosensitive coloring element of the present invention, a thermosensitive coloring material layer in which a single metal fine particle composed of at least two or more metal elements is dispersed in a matrix material is disposed on a substrate. Since the thermosensitive coloring material layer exhibits thermosensitive coloring characteristics accompanied by a large change in color tone, it is possible to provide a thermosensitive coloring device capable of performing more quantitative temperature history management than conventional devices.

According to the first method for producing a thermosensitive coloring device of the present invention, a metal ion, an α-hydrogen-containing alcohol,
And a step of preparing a mixture containing a matrix-forming material, a step of irradiating ultraviolet rays or γ rays, a step of adding a metal ion different from the metal ions, a step of disposing the mixture on a substrate, and a step of irradiating the mixture on the substrate with ultraviolet rays. Or a step of irradiating any of γ-rays, it is possible to provide a thermosensitive coloring element accompanied by a large change in coloring color tone.

According to the second method for producing a thermosensitive coloring device of the present invention, a metal ion, an α-hydrogen-containing alcohol,
Preparing a mixture containing a matrix-forming material, irradiating ultraviolet rays or γ-rays, adding a metal ion different from the metal ions, and a surfactant, arranging the mixture on a substrate, By irradiating the above mixture with either ultraviolet rays or γ-rays, it is possible to provide a thermosensitive coloring element having a large change in coloring color tone.

According to the third method for producing a thermosensitive coloring device of the present invention, a metal ion, an α-hydrogen-containing alcohol,
And a step of preparing a mixture containing a matrix-forming material, a step of mixing the mixture with a chalcogen compound or a halide, a step of disposing the mixture on a substrate, and a step of irradiating ultraviolet light or γ-rays. Accordingly, it is possible to provide a thermosensitive coloring element having a large change in color tone.

According to the fourth method for producing a thermosensitive coloring device of the present invention, a metal ion, an α-hydrogen-containing alcohol,
And preparing a mixture containing a matrix-forming material, a step of mixing the mixture with a chalcogen compound or a halide, and a surfactant, a step of disposing the mixture on a substrate, a step of irradiating ultraviolet rays or γ-rays. , It is possible to provide a thermosensitive coloring element accompanied by a large change in color tone.

According to the fifth method for producing a thermosensitive coloring element of the present invention, at least two or more metal ions, α
-Preparing a hydrogen-containing alcohol, a surfactant, and a matrix material, placing the mixture on a substrate,
By including the step of irradiating ultraviolet rays or γ-rays, it is possible to provide a thermosensitive coloring element accompanied by a large change in color tone.

Further, according to the thermosensitive coloring element of the present invention, a thermosensitive coloring material which irreversibly develops color by applying heat is arranged in the barcode display area of the frozen or refrigerated storage material, and the barcode information is read. At this time, by giving different barcode information when the thermosensitive coloring material develops a color, it is possible to perform a temperature history evaluation in a short time by using a conventionally used barcode system.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a first thermosensitive coloring material of the present invention. (A) Diagram showing a state before heat is applied. (B), (c) Diagram showing a state after heat is applied.

FIG. 2 is a conceptual diagram of a second thermosensitive coloring material of the present invention. (A) Diagram showing a state before heat is applied. (B) Diagram showing a state after heat is applied.

FIG. 3 is a conceptual diagram of a first thermosensitive coloring device of the present invention.

FIG. 4 is a conceptual diagram of a second thermosensitive coloring device of the present invention.

FIG. 5 is a conceptual diagram of the thermosensitive coloring device of the present invention. (A) A diagram showing a case where heat is applied. (B) A diagram showing a case where no heat is applied.

FIG. 6 is a graph showing the time dependence of the change in absorption spectrum of the thermosensitive coloring material of Example 1 of the present invention after being left at room temperature.

FIG. 7 is a diagram showing the configuration of a conventional thermosensitive coloring material. (A) Diagram showing a state before heat is applied. (B) Diagram showing a state after heat is applied.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 metal fine particle 2 matrix substance 3 composite fine particle 4 core fine particle 5 metal shell 6 adhered metal fine particle 7 fine particle 8 metal fine particle (single metal fine particle different from metal fine particle whose constituent element is 1) 9 substrate 10 frozen or refrigerated storage 11 Barcode display area 12 Thermal coloring material

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09C 1/00 G06K 1/12 A G06K 1/12 B41M 5/18 101D 19/06 G06K 19/00 E

Claims (21)

[Claims] 1. A composite fine particle having a core portion made of a metal chalcogenide compound, a metal halide or a metal, and having a metal shell structure or a structure having metal fine particles on at least a part of the surface of the nucleus. A thermosensitive coloring material, which is dispersed in a substance and irreversibly increases the particle size of the composite fine particles by applying heat, thereby changing the color tone of the thermosensitive coloring material. 2. A thermosensitive coloring material characterized in that at least two or more kinds of metal fine particles are dispersed in a matrix material, and the application of heat causes the fine particles to irreversibly increase and change the color tone of the thermosensitive coloring material. 3. The core portion is at least one metal selected from gold, platinum, silver, copper, tin, rhodium, palladium or iridium, or an oxide or sulfide of the metal,
Selenide, any of telluride, or fluoride of the metal, chloride, bromide, consisting of any of iodide, the metal shell structure, or the metal fine particles,
The thermosensitive coloring material according to claim 1, wherein the thermosensitive coloring material is made of at least one metal selected from the metal materials. 4. The method according to claim 1, wherein the matrix material is an inorganic material,
The thermosensitive coloring material according to claim 1, which is selected from the group consisting of an organic composite and a resin. 5. A metal ion, an α-hydrogen-containing alcohol,
And preparing a mixture containing a matrix-forming material, and irradiating the mixture with ultraviolet rays or γ-rays, and preparing a metal ion different from the metal ions into a mixture, and further mixing the mixture with ultraviolet rays or γ-rays. Irradiating any of them, a method for producing a thermosensitive coloring material. 6. A metal ion, an α-hydrogen-containing alcohol,
And preparing a mixture containing a matrix-forming material, and irradiating the mixture with ultraviolet light or γ-rays, and preparing a metal ion different from the metal ions, and a surfactant into the mixture, and further comprising: A method for producing a thermosensitive coloring material, comprising a step of irradiating either ultraviolet rays or γ rays. 7. A metal ion, an α-hydrogen-containing alcohol,
And a step of preparing a mixture containing a matrix-forming material, a step of adding a chalcogen compound to the mixture, or a halide to prepare a mixture, and a step of irradiating the mixture with either ultraviolet light or γ-rays. A method for producing a thermosensitive coloring material. 8. A metal ion, an α-hydrogen-containing alcohol,
And a step of preparing a mixture containing a matrix forming material, a step of preparing a mixture by adding a chalcogen compound or a halide to the mixture, and a surfactant, and applying either ultraviolet light or γ-rays to the mixture. A method for producing a thermosensitive coloring material, comprising a step of irradiating. 9. At least two kinds of metal ions, α
A hydrogen-containing alcohol, and a matrix-forming material,
A method for producing a thermosensitive coloring material, comprising a step of preparing a mixture containing a surfactant and a step of irradiating the mixture with either ultraviolet rays or γ-rays. 10. A metal chalcogenide compound having a core portion,
A heat sensitive material composed of a metal halide, or a metal, and comprising at least a portion of the surface of the nucleus having a metal shell structure or a composite fine particle having a structure provided with metal fine particles, and a matrix material in which the composite fine particles are dispersed; A thermosensitive coloring device, wherein a coloring material is disposed on a substrate, and the particle size of the composite fine particles is irreversibly increased by agglomeration due to the application of heat, thereby changing the color tone of the device. 11. A thermosensitive coloring material in which metal fine particles composed of at least two or more metal elements are dispersed in a matrix material, is disposed on a substrate, and the particle diameter of the metal fine particles is irreversibly agglomerated by application of heat. A thermosensitive coloring device characterized by increasing the color tone of the device. 12. The method according to claim 12, wherein the substrate is metal, plastic, fabric,
The material is made of at least one material selected from the group consisting of paper and glass.
2. The thermosensitive coloring device according to item 1. 13. A step of preparing a mixture containing a metal ion, an α-hydrogen-containing alcohol, and a matrix-forming material, a step of irradiating the mixture with either ultraviolet light or γ-rays, wherein the mixture is different from the metal ion. A step of preparing a mixture by adding various kinds of metal ions, a step of disposing the mixture on a substrate, and a step of irradiating the mixture disposed on the substrate with any of ultraviolet rays or γ rays to form a thermosensitive coloring material A method for producing a thermosensitive coloring device, comprising: 14. A step of preparing a mixture containing a metal ion, an α-hydrogen-containing alcohol, and a matrix-forming material, a step of disposing the mixture on a substrate, and irradiating the mixture on the substrate with either ultraviolet light or γ-rays. Α-hydrogen-containing alcohol, matrix forming material,
And a step of preparing a mixture containing a metal ion of a type different from the metal ions, a step of disposing the mixture on the substrate, and further irradiating the substrate with either ultraviolet light or γ-rays to form a thermosensitive coloring material. A method for producing a thermosensitive coloring element, comprising the steps of: 15. A step of preparing a mixture containing a metal ion, an α-hydrogen-containing alcohol, and a matrix-forming material, a step of irradiating the mixture with either ultraviolet light or γ-rays, wherein the mixture is different from the metal ion. Preparing a mixture by adding a type of metal ion and a surfactant, disposing the mixture on a substrate,
And a method for producing a thermosensitive coloring element, which further comprises irradiating the mixture disposed on the substrate with either ultraviolet rays or γ rays to form a thermosensitive coloring material. 16. A step of preparing a mixture containing a metal ion, an α-hydrogen-containing alcohol, and a matrix-forming material, a step of disposing the mixture on a substrate, and irradiating the mixture on the substrate with either ultraviolet light or γ-rays. Α-hydrogen-containing alcohol, matrix forming material,
A step of preparing a mixture containing a surfactant and a metal ion different from the metal ions, a step of disposing the mixture on the substrate, and further irradiating the substrate with any of ultraviolet rays or γ-rays, A method for producing a thermosensitive coloring element, comprising a step of forming a coloring material. 17. A step of preparing a mixture containing a metal ion, an α-hydrogen-containing alcohol, and a matrix-forming material, a step of adding either a chalcogen compound or a halide to the mixture, and preparing the mixture with a substrate. A method for producing a thermosensitive coloring element, comprising the steps of arranging the mixture and irradiating the mixture arranged on the substrate with either ultraviolet light or γ-ray to form a thermosensitive coloring material. 18. A step of preparing a mixture containing a metal ion, an α-hydrogen-containing alcohol, and a matrix-forming material, a step of adding either a chalcogen compound or a halide to the mixture and a surfactant, A method for producing a thermosensitive coloring element, comprising: arranging the mixture on a substrate; and irradiating the mixture arranged on the substrate with either ultraviolet light or γ-ray to form a thermosensitive coloring material. 19. at least two or more metal ions;
preparing a mixture comprising an α-hydrogen-containing alcohol, a surfactant, and a matrix-forming material, arranging the mixture on a substrate, and irradiating the mixture disposed on the substrate with either ultraviolet light or γ-rays. A method for producing a thermosensitive coloring element, comprising a step of forming a thermosensitive coloring material. 20. The method according to claim 6, wherein the surfactant is selected from at least one of materials having a carboxylic acid group, a sulfonic acid group, a sulfate ester group, a phosphate ester group, and a phosphonic acid group. 18. The method for producing a thermosensitive coloring material according to claim 8, 8, or 9, or the method for producing a thermosensitive coloring element according to claim 14, 16, or 17. 21. A thermosensitive coloring element used for temperature control of a frozen or refrigerated storage product, wherein the storage product is provided with a barcode display area, and irreversibly develops color by applying heat to the barcode display area. A thermosensitive coloring material, wherein different barcode information is provided when the thermosensitive coloring material develops a color when reading the barcode information.