JPS6113117A - Temperature indicating sheet - Google Patents

Abstract

PURPOSE:To use a sheet for managing the preservation of a frozen food, by containing more than one kind of color identifying agents meltable above a specified temperature but different in the melting point into each of microcapsules and applying them on a sheet to form color in the sheet above the specified temperature. CONSTITUTION:Color identifying agents (e.g. dye) 1 are contained in each of microcapsules 3, as respective by arranged in wax-like substances meltable above a specified temperature but different in the melting point (e.g. methyl myristate and methyl stearate). Then, the capsules 3 thus obtained are applied on a sheet 4 together with a binder 5 (ethylenevinylacetate copolymer) to make a temperature indicating sheet. Then, capsules 2 are broken and stuck on a frozen food. As the frozen food rises above a specified temperature, the color identifying agent with the lower melting point exudes to the binder 5 to form color and then, that with the higher melting point forms color. Thus, this temperature indicating sheet makes it possible to judge on how long the food is exposed to the temperature higher than the specified value.

Description

[Detailed description of the invention] Utilization ratio of “Locus bacterium” 2 The present invention relates to a temperature indication sheet.

Prior Art - Products stored at low temperatures, such as frozen foods, usually change in quality once they are exposed to an environment above a predetermined temperature. However, if the deteriorated food is stored at a low temperature again, it may become indistinguishable from the unaltered product in terms of appearance. In order to check in advance for deterioration due to poor management of low-temperature-preserved products by sales channels, and to supply products without deterioration to consumers with confidence, it is necessary to ensure that low-temperature-preserved products are not exposed to temperatures higher than the specified temperature during the process. It is necessary to be able to easily judge things.

An object of the present invention is to provide a temperature indicator that can be attached directly to a low-temperature-preserved product, or inserted or pasted into a package, to indicate when the low-temperature-preserved product is exposed to a temperature higher than a predetermined temperature. , relates to a temperature instruction sheet that changes color depending on temperature and time.

Conventionally, thermochromic materials include electron-donating color-forming organic compounds, electron-accepting organic compounds, alcohols, esters, etc. instead of metal complex crystals or liquid crystals, which are limited in the color-changing temperature range and type of color. Thermochromic compositions consisting of -10(1'(:
Although it is possible to freely select the discoloration temperature range and the type of color over a wide temperature range from It has not yet been provided.

In addition, in a thermochromic composition consisting of a combination of an electron-donating color-forming organic compound and an electron-accepting compound, one of the components is
A heat-integrating thermochromic composition has also been proposed in which the discoloration property is dependent on two items, time and temperature, by encapsulating one in a microcapsule and heating it to a predetermined temperature for a predetermined time to destroy the microcapsule. In this case, the composition is one in which the microcapsules are destroyed and discolored by heating to a temperature higher than room temperature, and cannot be applied to low-temperature preservation products as the object of the present invention. Temperature at low temperature As a sailor, the shape change or color tone change (dye f) upon thawing of frozen brine
In this case, since the temperature that can be managed is below 0°C and changes depending on temperature and time cannot be detected, it is difficult to detect 0"Cv or higher. It is not suitable for the present invention, which aims to manage general cryopreserved materials containing

A temperature indicator label that changes color after a certain period of time at a certain temperature has also been proposed (Japanese Patent Application No. 58-64352), but this temperature indicator label requires manufacturing and storage below the discoloration temperature, making it difficult to use. It was inconvenient.

Purpose of the Invention The present invention solves the problems of the prior art,
The purpose of the present invention is to obtain a temperature instruction sheet that changes color depending on the temperature and time when exposed to a temperature higher than a predetermined temperature in the temperature control of general low-temperature preservation items.

Structure of the Invention The present invention relates to a temperature indicating sheet in which two or more types of microcapsules that melt at a predetermined temperature or higher and contain coloring agents having different melting points and can be destroyed by external pressure are coated on the sheet.

Specific embodiments of the present invention are shown in FIGS. 1 to 6.

These are merely examples and do not limit the invention.

Figure 1 shows the coloring agent (1), the top layer (2), or a component that melts at a predetermined temperature (e.g., a wax-like substance), and a suitable coloring agent (2).
For example, it is colored with dye), which is made into microcapsules (3) and applied to a profiteering sheet (.1ll-).

1, as a coloring agent, two types of lamps with different melting temperatures and colors i
The thing used is 1]. In Figure 1, both! 17
: They may be combined or, of course, may be laminated separately as shown in Figures 2 onwards.

When the microcapsules (3) inside this temperature indication sheet are destroyed by applying pressure before use, the coloring agent (1) and (
2) Or leaching. Immediately apply this pressure-treated sheet) to Cold 7 East foods, etc. (=t L). When frozen, the coloring agents (1) and (2) solidify, and no color change is observed on the outside. Frozen foods When exposed to a predetermined temperature for a certain period of time, the coloring agent with a lower melting point (for example, (1)) leaches out to the surface, and the color of the coloring agent (1) (for example, blue) appears on the outside. , over time, the color former (2) with a higher melting point leaches out to the surface, and the external blue color is a mixture of color former (2) (e.g. yellow) and color former (1) (e.g. , green).Therefore,
By observing the color of the temperature indicator sheet, you can know the thermal history of frozen foods.

FIG. 2 shows seven colorants (1) and (2) in the embodiment of FIG.
) are the same color but have different melting points), and the temperature indicator sheet is shown in which the microcapsules are separately coated. Coloring agent (
]) area changes color first, and then the coloring agent (2) area changes color. That is, the thermal history of the frozen food can be known from the discolored area of the sheet.

FIG. 3 shows a temperature indicating sheet in which the melting point and color of the coloring agent is changed in the embodiment of FIG. 2, and the sheet is applied to different areas. The processing method and color change principle are the same as in FIG. With this sheet, the thermal history can be known from both the discolored area and the color, and the discoloration can be clearly observed.

In Figure 4, coloring agents (1) and (2) with different melting points are applied to different areas of a sheet, and the coloring agent (1) and (2) are applied to a component that melts at a predetermined temperature (for example, a wax-like substance). 5
) and (5') (for example, leuco dye), and the coloring agent (5) is added to the outside of the microcapsule.
and (5'), which contains a substance (for example, phenol) that changes color when it comes into contact with it. When in use, this sheet is pressed to break the internal capsule (3) and attached to the frozen food.

When a frozen food is exposed to a predetermined temperature, the coloring agent (1) with a low melting point begins to melt, producing a discoloration in that area, and when left to stand further, the coloring agent (1) with a high melting point begins to melt. 2) begins to melt and the area becomes discolored. As a result, knowing the thermal history of frozen foods can help. By using different compounds as the color formers (5) and (5') in the color formers (1) and (2), the color in each region can be changed. The color changing agents (6) and (6') may be changed as appropriate depending on the type of the color formers (5) and (5'), and even when the color formers are different, the same color changing agent may be used.

FIG. 5 shows the discolorant (6) and (6'), contrary to FIG.
) is placed in a microcapsule, and the coloring agent (5) and (
5') is dispersed outside the microcapsules,
The operation and color change principle is similar to that described in FIG. In both Figures 4 and 5, as in Figure 1, two
It is also possible to use a temperature indicating sheet coated with different types of capsules.

In Figure 6, color forming agents (5) and (5') and color changing agent (6) are shown.
) and (6') are dispersed outside the microcapsules of color formers (1) and (2), and the microcapsules of color formers (1) and (2) having different melting points are arranged in different areas of the sheet. It is. Color formers (5) and (5') do not necessarily have to be different compounds, and may exhibit the same color.

In the present invention, a coloring agent refers to a substance that causes a discoloration that is visible to the naked eye on the temperature indicator sheet when melted, and includes, for example, a substance that itself is colored, a substance colored with a dye or pigment, It includes those that are colorless themselves or that react with other components to cause discoloration. The coloring agent itself may be a colored one-component system, or a wax-like substance that melts at a predetermined temperature may itself be colored with a dye or the like.

Further, a color former (for example, leuco dye) or a color change agent (for example, phenol) may be dissolved or dispersed before use.

The coloring agent (2) must be melted at a temperature higher than a predetermined temperature. The predetermined temperature refers to the maximum temperature at which the test object (for example, frozen food, etc.) must be stored at a low temperature. For example, in the case of a temperature instruction sheet for a test object that must be stored at a temperature lower than 20°C. In this case, the predetermined temperature is 20°C. This temperature is determined by the type of specimen and the required storage temperature, and the coloring agents (1) and (2) may be arbitrarily selected according to the temperature. Usually 5-20℃ 1 Especially 1
It is often stored at around 0''C or below, and is selected from substances that have a melting point within that range.Of course, this temperature is not limited.

The coloring agent is used by separately microencapsulating two or more components having different melting points. When a test object, such as a frozen food, is left at room temperature, a coloring agent with a low melting point first melts, and its color is displayed. As more time passes, the coloring agent with a high melting point melts and the color appears. The difference in melting point of the coloring agent on one temperature indicator sheet is not necessarily constant depending on the storage temperature, required information on heat history, etc., but it is practically within the range of 0°5 to 30°C, especially 1 to 20°C. It is preferable to select from

As the color former, it is preferable to use two or more kinds of colorants that exhibit a high level of color change, but it is also possible to make the same color by changing the application area.

As mentioned above, the coloring agent is usually used by blending a coloring agent, a coloring agent and/or a color-changing agent with a waxy substance, but it may also be used alone.

Examples of waxy substances used in the present invention include pentadecane, tetradecane, hexadecane, 1-
aliphatic hydrocarbons such as heptadecane, ]-octadecane,
Aromatic hydrocarbon compounds such as dodecylbenzene, I]-xylene, tri-power printer lyceride, 1-elide-2,
3-coupling glyceride, 1-1) / rheo2,3
-Laurin glyceride, 2-oleo-1,3-one laurin glyceride, 1-myristo-2,3-diolein glyceride, 1-palmito-2,3-diolein glyceride, ethyl myristate, methyl myristate, myristicin butyl acid, methyl caproate, methyl caproate,
Esters such as methyl laurate, ethyl laurate, methyl palmitate, ethyl stearate, methyl stearate, pentadecyl acetate, 2-undeca-7-
alcohols such as alcohol, benzyl alcohol, and glycerol; halokenate hydrocarbons such as triflomomethane and 1,2-Schiflomoethane; amines such as monoethanolamine and ethylenenoamine; Examples include carboxylic acids and ethers such as oxane and bennoether.

Dyes or pigments for coloring these waxy substances include Red No. 223, Red No. 225, Yellow 2F
I, No. 1, red No. 505, orange, and 4 o No. 3 hats are exemplified.

When used in the manner shown in Figures 1 and 5, color formers (5), (5') or color changing agents (6), (6') are combined with one lath as the seven coloring agents. use

In this case, a leuco dye is used as the coloring agent (5), (5'), an organic carboxylic acid is used as the color changing agent (6), (6'), and an alcohol such as 2-undecanol or glycerin is used as the waxy substance. If such a compound is used, color development will be suppressed, so it is not preferable to use it in the manner shown in FIGS. 4 and 5. On the contrary, these alcohols are effective in erasing colors produced by leuco dyes, organic carboxylic acids, etc., and are therefore useful in the embodiment shown in FIG. Decoloring of a colored product is also included in the discoloration of the present invention.

When using a leuco dye and a polycarboxylic acid in the embodiment shown in FIG. Compounds having a color erasing effect may be blended with alcohols, esters, ketones, ethers, aromatic hydrocarbons, etc. as exemplified below.

Alcohols include monohydric alcohols, polyhydric alcohols, and derivatives thereof. Examples of these compounds are shown below.

[1-octyl alcohol, n-nonyl alcohol, ■
]-decyl alcohol, I)-lauryl alcohol, 1
1-myristyl alcohol, I+-cetyl alcohol, 11-stearyl alcohol, oleyl alcohol,
Examples include cyclohexanol, cyclopentanol, benol alcohol, nnamyl alcohol, ethylene glycol, polyethylene glycol, propylene glycol, trimethylolpropane, pentaerythritol, and turpinto.

Examples of compounds as esters are shown below.

amyl acetate, octyl acetate, 7-tyl propionate, ethyl caproate, amyl caprylate, ethyl caprate,
Octyl caprate, lauryl caprate, methyl laurate, octyl laurate, lauryl laurate, methyl myristate, hexyl myrimate, stearyl myristate, methyl palmitate, myristyl palmitate, methyl stearate, ethyl stearate, Lauryl stearate, butyl benzoate, amyl benzoate, phenyl benzoate, ethyl acetoacetate, methyl oleate, butyl acrylate, butyl oxalate, noethyl malonate, noacyl tartrate, dimethino sepatate 7
Noacyl talate, nooctyl phthalate, butyl 7malate, noethyl maleate, triethyl citrate 1
Examples include 2-hydroxystearic acid triglyceride, castor oil, dioxystearic acid methyl ester, 12-hydroxystearic acid methyl ester, and the like.

The following compounds are exemplified as ketones.

Noethylketone, ethylbutylketone, methylhexylketone, mesityl oxide, cyclohexanone, methylcyclohexanone, acetophenone, pentethylketone,
Examples include acetonyl acetone and diacetone alcohol.

The following compounds are exemplified as ethers.

Examples include butyl ether, hexyl ether, nophenyl ether, nooxane, ethylene glycol butyl ether, ethylene glycol phenyl ether, and ethylene glycol monophenyl ether.

Aromatic hydrocarbons include 1)-xylene, isopropylbenzene, amylbenzene, mesitylene, cymene,
5-Methyl-3-isobutyltoluene, dotecylbenzene, cyclohexylbenzene, biphenyl, methylbiphenyl, ethylbiphenyl, noethylbiphenyl, trimethylbiphenyl, benolbenzene, phenyltolylmethane, xylylphenylmethane, ditolylmethane, trioctylnophenyl Methane, Tribendiluciphenylmethane, Tolylxylylmethane, Dixylylmethane,
Nophenylethane, tolylphenylethane, xylylethane, phenylisopropylphenylethane, tolylnoisopropylphenylethane, )-methylisopropylphenylethane, diphenylpropane, ditolylpropane, phenyltolylpropane, phenylxylylpropane, tolylxylylpropane , Nobenzylbenzene, Nooctylbennoethylbenzene, Nobenzyltoluene, Tetrahydros7tylphenylmethane, Tetrahydromethylna7thylphenyl ethane, Tetrahytrona 7
Examples include tylphenylethane, naphthylphenylmethane, and methylna-7-tylphenylethane.

Color forming agents (5), (5') and color changing agents (6) used in the present invention
), (6') are exemplified as follows.

(i) Electron-donating color-forming organic compound (color former) and acids (phenolic hydroxyl group-containing compound, organic carboxylic acid,
Inorganic solid acid, etc.) (color change agent) (l) H indicator (
(color former) and acid or alkali (color change agent) (iii) iron compound and polyhydric hydroxy compound having a 7-enolic hydroxyl group The electron-donating color-forming organic compounds used in the present invention include diaryl 7-thalides, These include arylcarbyls, leucoolamines, acylouramines, arylauramines, rhodamine B lactams, indolines, spiropyrans, fluorans, and the like.

Examples of these compounds are shown below.

Crystal high iolent lactone, malachite green lactone, Michler hitrol, crystal high iolent carbinol, malachite green carpil,
N-(2,3-nochlorophenyl)wife auramine,
N-benzoyl auramine, N-acetyl auramine,
N-Phenyluramine, Rhodamine B-lactam, 2-
(phenyliminoethanelidene) 3,3-methylindoline, N-3,1-)trimethylindolinobenzospiropyran, 81-methoxy-N-3,3-trimethylindolinobenzospiropyran, 3- Diethyl 7-mi/-6-methyl-7-chlorofluorane, 3-ethyl amine/-7-medoxy fluorane, 3-diethyl amine/
-6-Benzoloxyfluorane, 1,2-benz-6
-Dinitylami-7 fluorane etc.

Compounds having a phenolic hydroxyl group include polyphenols from moires, and their substituents include alkyl groups, aryl groups, acyl groups, alkoxycarbonyl groups, and halogens. Examples of these compounds are shown below.

Tert-butylfunimer, nonylphenol, dodecyl 7-ethyl, α-su-7-tol, β-na-7-tol,
Hydroquinone monomethyl ether, ρ-chlorophenol, 1]-bromophenol, o90lephael,
o-70 mophenol, 〇-phenylphenol, 1]
-Phenylphenol, methyl p-oxybenzoate, 3
-isopropylcatechol, I)-tert-butylcatechol, 4.4"-methylenetuphenyl, bisphel/-A, 2-dioxynaphthalene, 2.3-')
Oxynaphthalene, chlorcatechol, 70 mocatecol
2,4-hydroxybenzophenone, phenolphthalein, methyl gallate, ethyl gallate, propyl gallate, 7-tyl gallate, hexyl gallate, octyl gallate, dotesyl gallate, cetyl gallate, gallic acid These include stearyl acid, tannic acid, and phenolic resin.

Examples of inorganic solid acids include silica-alumina, silica-magnesia, bentonite, kaolin, seven earths, acid clay, activated clay, montmorillonite, atabalkite, zinc oxide, titanium oxide, calcium sulfate, barium sulfate, aluminum sulfate, and aluminum chloride. , lead chloride,
These include tin chloride and arsenic dioxide.

Examples of right isoacids include acetic acid, propionic acid, butyric acid, and caproic acid.

As the iron compound, ferric stearate, ferric myristate, ferric oleate, etc. are used.

Polyhydric hydroxyl 6hX having 7-ethyl hydroxyl group
Examples of acids or esters thereof include gallic acid, tannic acid,
Methyl gallate, ethyl gallate, propyl gallate,
These include butylene gallate, octylate gallate, dodecyl gallate, and stearyl gallate.

The microencapsulation technique used in the present invention includes a known method, the coacervation method, j II 3
ll', 11 polymerization method, interfacial polymerization method, underwater curing coating method, phase separation method from an aqueous solution, phase separation method from an organic solution, etc. can be used arbitrarily.

There are several methods for applying microcapsules containing a coloring agent to the diaphragm 2, such as a knife coater, brush coater, reverse roll coater, bar coater, and F-knife coater. A knife coater is preferred. When the sheet is used, the microcapsules containing the coloring agent are destroyed, but the method is not particularly limited. In order to understand changes depending on time and temperature when the entire system is exposed to a predetermined temperature, it is desirable to destroy it under a constant load using a hand roller or the like.

The microcapsules have a size of about 1 to 300 μm so that they can be easily broken with a roller or the like during use.

If it is less than 1 μM, it is difficult to break, and if it is more than 300 μM, the branches become large, causing problems in the coating process.

The film-forming ingredients used in microcapsules are gelatin,
These include alginic acid, acrylic polymers, methacrylic polymers, melamine, and epoxy polymers, and these are easily destroyed by external force at low temperatures. .

Capsules containing a coloring agent that melts at a predetermined temperature may be applied by any suitable means.

As the binder used for applying the microcapsules to the base material, it is possible to use an organic solvent solution type binder, a non-aqueous emulsion type binder, an aqueous solution type binder, and an aqueous emulsion type binder.

When an organic solvent-based binder is used, either the organic solvent itself acts as one of the discoloring components, or the organic solvent extracts the microencapsulated components before breaking the microcapsules and discolors the temperature indicator sheet before use. There are cases. As a result, discoloration at the discoloration temperature of the temperature indicator sheet may become light, or in some cases, no discoloration can be confirmed at all.Furthermore, industrially, organic solvent odor, flammability, and sanitary conditions may occur. It is difficult to use because of the second problem.

Similarly, in the case of a non-aqueous emulsion, the same drawbacks as those using an organic solvent solution type binder occur.

Furthermore, with aqueous binders, the solution viscosity of the binder is generally high and the solid content of the adhesive cannot be increased, which limits the selection of the microcapsule/adhesive solid content weight ratio during application, making it difficult to achieve the desired discoloration performance. It may not be possible to set it within an appropriate range. Furthermore, when an aqueous binder is used, when the temperature indicator sheet is wound into a roll, it becomes sticky and difficult to unwind (blocking), resulting in a lack of industrial productivity. For the above reasons,
Organic solvent solution type, non-aqueous emulsion and aqueous solution type binders both have many drawbacks and are problematic in practical use.

On the other hand, when microcapsules are dispersed in an aqueous emulsion-type bindu and applied to a substrate, there are no problems such as discoloration caused by solvents or impregnation/elution of microcapsules, as seen with the aforementioned organic solvent-type binders, and there is no discoloration. The hue change due to temperature is very clear. Moreover, it becomes possible to select the resin material used for the binder from a wide range of materials. Furthermore, since water-based emulsion type paints have a low viscosity compared to their solid content, the selection range of the microcapsule/adhesive solid content weight ratio during application is wide, and the desired discoloration performance can be adjusted to the temperature indicator sheet. It is possible to hold it. Furthermore, since it is insoluble in water after application and drying, it is easy to unwind the temperature indication sheet after winding it up, and it does not become sticky.

Any aqueous polymer emulsion may be used as long as it prevents contact between components involved in discoloration and does not adversely affect discoloration. For example, natural polymers such as rubber, glue, starch, polyvinyl acetate, vinyl acetate polymer,
Examples include synthetic polymers such as acrylic acid ester copolymers, vinylidene chloride copolymers, epoxy resins, and 7-tanoenph polymers. Particularly preferred is vinyl acetate-ethylene fluoropolymer.

The solid content concentration of Emul Noyon is not particularly limited, and it is sufficient that it can be easily coated onto the base sheet when blended with the microcapsules in a desired weight ratio. usually,
A solid content concentration of about 10 to 70% by weight is preferable.

Since the speed of discoloration of the temperature indicator sheet differs depending on the mixing ratio of the microcapsules and the aqueous emulsion, it is necessary to select the mixing ratio depending on the purpose. If the amount of emulsion is too small, it will no longer function as an adhesive and the microcapsules will peel off from the coated sheet. In addition, if the concentration of solid content in the emulsion becomes too high, the discoloration rate of the temperature indicator sheet will be slow.Usually, it is appropriate to use a microcapsule/emulsion solid content weight ratio of about 30/1 to 1/2. .

Additionally, additives can be added to the coloring agent and the substances that interact with it to cause discoloration, to the extent that they do not interfere with irreversible discoloration, which is the objective of the present invention. . Typical such additives include antioxidants, ultraviolet absorbers, inorganic fillers, pigments, plasticizers,
There are lubricants, antistatic agents, etc.

The temperature indicator sheet of the present invention has capsules of a coloring agent coated on a base sheet, and the capsule layer further adsorbs the molten coloring agent so that discoloration can be observed more clearly. A display layer may also be provided. Further, the color forming agent capsule containing the color forming agent or color changing agent and the color changing agent or color forming agent may be arranged in separate layers with a suitable diaphragm interposed therebetween. The molten coloring agent changes color through the diaphragm. An adhesive layer for pasting may be provided on the back surface of the base sheet. Furthermore, an impermeable layer may be provided to prevent the melt colorant from diffusing into the adhesive layer. Alternatively, the entire sheet may be banked with a transparent film and used as a label.

Methods for attaching the temperature instruction sheet of the present invention to products stored at low temperatures include "applying it with an adhesive", hanging it as a label,
Examples include direct adhesion to containers for cryogenic storage.

It is preferable to use a temperature indication sheet (for example,
Examples include, but are not limited to, kamaboko, raw noodles, yogurt, night pickles, and bread noodles.

Effects of the Invention By using the temperature indication sheet of the present invention, it is possible to easily determine how long a frozen food has been exposed to a temperature higher than its storage temperature. That is, by knowing the thermal history of frozen foods in more detail, it becomes possible for sellers and consumers to easily evaluate the quality of frozen foods by visual inspection at the time of sale or purchase.

Next, specific examples will be shown, but the present invention is not limited thereto.

Example 1 60 g of methyl myristate and methyl methacrylate, AI
BN is uniformly dissolved, dispersed in a 0.5% methylcellulose aqueous solution using a homogenizer, and reacted at 75° C. for 5 hours. After cooling, it was filtered to obtain a wet cake with a solid content of 65%. The particle size was 5-30 μm. Microcapsules of ethyl stearate were prepared in the same manner.

Each wet cake was mixed with Polysol MC-5 (manufactured by Showa Kobunshi Co., Ltd.) as Ingu in a ratio of 9:1 to prepare an ink. On the other hand, a commercially available black thermal paper was heated to develop color over its entire surface, and the prepared ink was applied to the back surface. At this time, methyl myristate microcapsules were applied on the right side of the thermal paper, and ethyl stearate microcapsules were applied on the left side. Each coating 17 was adjusted to have a weight of 40 g/m2. 1 piece 3 +) ~ 100 kg/r each
When the capsule was destroyed by applying a load of n' and a color development test was conducted at 13℃, the right side started to develop color in about 1 hour.
The treatment was completed in 6 hours, or there was no change in the left side even after 1 day. Next, when the temperature was lowered to 20°C, the left side also began to change color, which was completed within 6 hours.

Example 2 According to the method of Example 1, microcapsules containing ethyl laurate and microcapsules containing ethyl laurate were prepared. Each wet cake and Polysol MC-5 (manufactured by Showa Kobunshi Co., Ltd.)! They were mixed at a ratio of J:1 to prepare an ink.

A commercially available black thermal paper (manufactured by Honshu Paper Industries Co., Ltd.) was colored over its entire surface, and ethyl laurate was applied to the right side and methyl laurate was applied to the left side at 40 g/m 2 . 30-100 kg/
Destroy the microcapsules by applying a load of -1
When stored in a thermostat at 5°C, no changes were observed for one week. When kept at -10°C, the right side started discoloring in about 1 hour and completed discoloration in 6 hours. No change was observed on the left side even after leaving it for one day.

Next, when the temperature was maintained at 5° C., color development started in about 2 hours and was completed in about 6 hours.

Example 3 Microcapsules of methyl myristate and ethyl myristate were prepared in the same manner as in Example 1. Methyl myristate on the right side of the colored black thermal paper,
40 g/m2 capsules of ethyl myristate on the left side
It was applied to a thickness of . After the capsules were broken and stored at 3°C, there was no change overnight. When the product was kept at 7°C and the color change was observed, the left side started to change color in 1 hour and was completed in 6 hours. Next, when the temperature was kept at 13° C., the right side began to change color in 1 hour, and the color change was completed in 6 hours.

Example 4 60 g of 1% methyl myristate solution of oil-soluble dye (Oil Hiolet #732; manufactured by Orient Chemical Co., Ltd.)
, methyl methacrylate 4 f'l g , A I B
N+,').

2s were uniformly combined (J'L) and dispersed in a 0.5% carboxydimethylcellulose aqueous solution using a homogenizer.

The reaction was carried out at 75° C. for 5 hours to obtain microcapsules with a shoulder size of 10 to 50 μm. Similarly, a dye dissolved in ethyl stearate was microencapsulated.

Each was filtered to yield a wet cake with approximately 65% solids. Inks were prepared by mixing each cake and Polysol Mc-s at a ratio of 9:1.

Microcapsules of methyl myristate and ethyl stearate were applied to the right side and the left side of 55 g of bi-quality paper, respectively. 20-100kg/C71' of microcapsules
When it was kept at 13°C, purple coloring started from the left side after 1 hour and was completed in 6 hours.

No changes were seen on the right side. Next, when the temperature was raised to 20° C., discoloration started in about 2 hours and was completed in 6 to 8 hours.

Example 5 Microcapsules of a 1% methyl myristate solution of Oil Blue #809 (manufactured by Sansui Gosei Kagaku Co., Ltd.) were prepared in the same manner as in Example 4. Next, microcapsules of a 1% ethyl stearate solution of Oil Blue #456 (manufactured by Sansui Gosei Kagaku Co., Ltd.) were prepared in the same manner.

Each is filtered and weighs 1q of wet cake with a solid content of 65%.

An ink was prepared by mixing 30 g of a wet cake of methyl myristate microcapsules, 30 g of a wet cake of ethyl stearate microcapsules, and 20 g of Sumiriki 7 Renkusui 830.

55 g of this ink was applied to high quality paper. Application amount is 40g
/m2. After thoroughly drying, cool the test paper and
20-1001g/cI! The microcapsules were destroyed at a pressure of 7' and kept at a constant temperature of 10°C.

- No change was observed even after leaving it overnight. Next, when the temperature was maintained at 13° C., the portion marked 41 started to change color to red after 1 hour, and the color completely changed in 6 hours. When the temperature was further increased to 20° C., the red colored portion began to become slightly darker after about 20 hours, and the color completely changed to dark purple after about 8 hours.

Example 6 A 1% solution of methyl crystal violet bluestate was microencapsulated in the same manner as in Example 4 and filtered to form a cake with a solid content of 65%.

Next, a 1% solution of C V J- in ethyl stearate was microencapsulated in the same manner and filtered to form a cake with a solid content of 65%.

Inks were prepared by mixing each cake and Polysol MC-5 at a mixing ratio of 9:1. Methyl myristate microcapsule ink was applied to the right side of the back side of bottom paper (manufactured by Kanzaki Paper Co., Ltd.) to a thickness of 40 g/m2.

4. Ethyl stearate microcapsule ink on the left side. It was applied at a thickness of 0 g/m2. After sufficiently cooling the test paper, it was stamped and kept at 10°C, and no change was observed even after one day. When kept at 13°C, the stamped area on the right side began to change color to blue after about 1 hour, and the color change was completed in 6 hours. 20℃
When the temperature is raised to , the stamped area on the left side begins to change color,
The color change was completed after 6-8 hours.

[Brief explanation of drawings]

1 to 6 are schematic cross-sectional views of the temperature indicating sheet of the present invention. (1) Wax-like substances (2) Wax-like substances with different melting points (3) Microcapsules (4) Base sheet (5) Coloring agents (5') Different types of coloring agents (6) Color-changing agents
(6') Different types of color change agents Figure 1 Figure 2 Now Figure 3 Figure 4 → District 5 Procedural Amendment (Self-restraint August 28, 1980)

Claims (1)

[Scope of Claims] 1. A temperature indicating sheet in which two or more types of microcapsules that melt at a predetermined temperature or higher and contain coloring agents having different melting points and can be destroyed by external pressure are coated on the sheet. 2. The sheet according to item 1, wherein the difference in melting point of the coloring agent is 1 to 20°C.