JPH0371057B2 - - Google Patents

Description

[Detailed description of the invention] Industrial applications 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 at a predetermined temperature or higher, but if the deteriorated products are stored at low temperatures again, they may become indistinguishable from unaltered products in terms of appearance. In order to check in advance for deterioration due to poor management of low-temperature-preserved products along the sales route, 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 that.

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., in place of metal complex crystals or liquid crystals, which are limited in the color-changing temperature range and type of color. Thermochromic compositions consisting of electron-accepting color-changing organic compounds, electron-donating organic nitrogen compounds, alcohols, esters, etc. have been proposed.
Although it is possible to freely select the discoloration temperature range and color type over the above wide temperature range, the present invention provides a composition that discolors depending on temperature and time. I haven't reached the point yet.

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 encapsulated in microcapsules and heated to a predetermined temperature for a predetermined period of time. A thermally integrated thermochromic composition has also been proposed in which the discoloration property depends on two factors, time and temperature, by destroying the capsules, but in this case, the microcapsules are destroyed by heating to a temperature above room temperature. , which is a composition that changes color and cannot be applied to products stored at low temperatures as the object of the present invention. As a temperature indicator at low temperatures, a method has been proposed that detects changes in shape or color (combined with dye) when frozen brine melts, but in this case, the temperature that can be controlled is 0°C or lower, and Since changes depending on temperature and time cannot be detected, this method is not suitable for the present invention, which aims at managing general low-temperature storage materials including those stored at temperatures of 0° C. or higher.

Temperature indicator labels that change color after a certain period of time at a certain temperature have also been proposed;
This temperature indicator label required manufacturing and storage below the discoloration temperature, making it inconvenient to use.

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

Structure of the Invention The present invention has () a coloring agent that melts at a predetermined temperature, () a diaphragm through which the molten coloring agent passes, and () a display layer that absorbs the molten coloring agent. A temperature indicating sheet is encapsulated in destructible microcapsules and is placed on the opposite side of the display layer through a diaphragm, and the diaphragm has parts of different thicknesses or is partially made of different materials. provide.

The present invention will be explained based on FIGS. 1 to 6.

FIG. 1 shows a temperature indicating sheet with diaphragms 1 and 1' of different thicknesses. A coloring agent 2 that melts at a predetermined temperature is microencapsulated on one side of the diaphragm, and a display layer 3 is arranged on the opposite side of the diaphragm. Diaphragms 1 and 1' are made of the same material but have different thicknesses.

When a sheet of microcapsules 4 destroyed by external pressure is attached to a frozen food, etc., when the temperature of the frozen food rises above a predetermined temperature, the coloring agent 2 melts.
It leaches out of the microcapsule 4. Coloring agent 2 is
For example, it is a wax-like substance colored with dyes, pigments, etc., which economically passes through the diaphragms 1 and 1' and is adsorbed to the display layer 3, whereby a change in color is observed. Since the diaphragms 1 and 1' have different thicknesses, there is a difference in the time it takes for the molten coloring agent to reach the display layer.
It becomes possible to know the thermal history of frozen foods.

A diaphragm 1 having a thickness of 3 or more may be used, thereby allowing a more detailed thermal history to be known.

FIG. 2 shows coloring agent 2 as diaphragms 1 and 1'.
This is an embodiment using membranes of the same thickness that have different permeation rates. Of course, the material and thickness may be changed at the same time. The microcapsules 4 contain a coloring agent, for example, a coloring agent 5 (for example, a leuco dye) dissolved in wax, and the outside contains a coloring agent 6.
(e.g., phenols). If a sheet containing destroyed microcapsules is attached to a frozen food before use, when the temperature of the frozen food rises above a predetermined temperature, the wax dissolves and the coloring agent 5 and color changing agent 6 come into contact, causing discoloration. The coloring agent that has changed color passes through the diaphragms 1 and 1' over time and passes through the display layer 3.
It is possible to observe the color change after the adsorption. Since the permeation rates of diaphragms 1 and 1' are different, the first
As explained in the figure, you can know the thermal history.

FIG. 3 shows an embodiment in which the thickness of the diaphragm 1 changes continuously. Contrary to FIG. 2, the color change agent 6 is microencapsulated together with a wax-like substance, and the color forming agent 5 is present outside the microcapsule. Of course, the opposite may be true. The principle of measuring the thermal history is the same as that described in the explanation of FIG. Figure 4 shows diaphragm 1
and 1' have different thicknesses. A color forming agent 5 dissolved in wax is encapsulated in the microcapsule, and a color changing agent 6 is arranged on the opposite side of the diaphragm. The coloring agent (wax+coloring agent) melted above a predetermined temperature passes through the diaphragms 1 and 1', comes into contact with the color-changing agent, causes a color change, and is adsorbed onto the display layer 3.
Since the adsorption rate in the display layer varies depending on the thickness of the diaphragm, the thermal history of the frozen food can be determined by observing the discoloration of the display layer.

FIG. 5 shows an embodiment in which the color changing agent 6 in FIG. 4 is microencapsulated and the coloring agent 5 is placed on the opposite side of the diaphragm. The principle of measuring thermal history is the same as that shown in FIG.

FIG. 6 shows an embodiment in which a color change agent 6 and a color forming agent 5 are adsorbed onto the display layer. In this embodiment, the display layer is colored in advance, but by using alcohol as a coloring agent, the color disappears upon contact with the alcohol. The measurement principle is the same as that explained in FIGS. 1 to 5.

In the present invention, a coloring agent refers to an agent that causes discoloration of the display layer when adsorbed to the display layer.
Examples include substances that are themselves colored, substances colored with dyes or pigments, and substances that are colorless in themselves but cause discoloration in the display layer by reacting with other components. This coloring agent itself may be a colored one-component system, or a wax-like material itself that melts at a predetermined temperature may be colored with a dye or the like. Further, a color former (for example, leuco dye) or a color change agent (for example, phenols) 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 highest 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 support sheet for a test object that must be stored at a temperature lower than 20℃. In this case, the predetermined temperature is 20°C. This temperature is determined by the storage temperature required for the type of specimen, and the coloring agent 2 may be arbitrarily selected depending on the temperature. It is usually stored at a temperature of 5 to 20°C, especially around 10°C or lower, and is selected from substances having a melting point within that range. Of course, this temperature is not limiting.

As mentioned above, the coloring agent is usually used by blending a coloring agent, a color former and/or a color changing agent with a wax-like substance, but it may be possible to use it alone.

Examples of wax-like substances used in the present invention include aliphatic hydrocarbons such as pentadecane, tetradecane, hexadecane, 1-heptadecane, and 1-octadecane, aromatic hydrocarbon compounds such as dodecylbenzene and p-xylene, and tricaprine glyceride. , 1-elide-2,3-dicaprin glyceride, 1-linoleo-2,3-laurin glyceride, 2-oleo-1,3-dilaurine glyceride, 1-myrist-2,3-diolein glyceride, 1- Palmito-2,3-diolein glyceride, ethyl myristate, methyl myristate, butyl myristate, methyl caproate, methyl caprate, methyl laurate, ethyl laurate, methyl palmitate, ethyl stearate, methyl stearate, Esters such as pentadecyl acetate, alcohols such as 2-undecanol, benzyl alcohol, glycerol,
Halogenated hydrocarbons such as tribromomethane and 1,2-dibromoethane, monoethanolamine,
Examples include amines such as ethylenediamine, organic carboxylic acids such as formic acid and acetic acid, and ethers such as dioxane and benzyl ether.

Examples of dyes or pigments for coloring these wax-like substances include Red No. 223, Red No. 225, Yellow No. 204, Red No. 505, and Orange No. 403.

When used in the manner shown in FIGS. 4 and 5, color former 5 or color change agent 6 is used as the color former.
is used in combination with waxes.

In this case, when a leuco dye is used as the color former 5 and an organic carboxylic acid is used as the color change agent 6, 2-undecanol,
When alcohols such as glycerin are used, color development is suppressed, and therefore their use in the embodiments shown in FIGS. 2 to 5 is not preferred. On the contrary, these alcohols are effective in decoloring the display layer colored by leuco dyes, organic carboxylic acids, etc., and therefore are useful in the embodiment shown in FIG. 6.

When the display layer is colored with a leuco dye and an organic carboxylic acid in the embodiment shown in FIG. A compound having a color effect may also be blended. Examples of these compounds having a color erasing effect include alcohols such as those shown below;
These include esters, ketones, ethers, aromatic hydrocarbons, etc.

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

n-octyl alcohol, n-nonyl alcohol, n-decyl alcohol, n-lauryl alcohol, n-myristyl alcohol, n-cetyl alcohol, n-stearyl alcohol, oleyl alcohol, cyclohexanol, cyclopentanol, benzyl alcohol, cinnamyl Alcohol, ethylene glycol, polyethylene glycol, propylene glycol, trimethylolpropane, pentaerythritol, sorbitol, etc.

Examples of compounds as esters are shown below.

Amyl acetate, octyl acetate, butyl propionate, ethyl caproate, amyl caprate, ethyl caprate, octyl caprate, lauryl caprate, methyl laurate, octyl laurate, lauryl laurate, methyl myristate,
Hexyl myristate, stearyl myristate, butyl palmitate, myristyl palmitate, methyl stearate, ethyl stearate,
Lauryl stearate, butyl benzoate, amyl benzoate, phenyl benzoate, ethyl acetoacetate, methyl oleate, butyl acrylate, dibutyl oxalate, diethyl malonate, dibutyl tartrate, dimethyl sebatate, dibutyl phthalate, dioctyl phthalate , dibutyl fumarate, diethyl maleate, triethyl citrate, 12-hydroxystearic acid triglyceride, castor oil,
Examples include dioxystearic acid methyl ester and 12-hydroxystearic acid methyl ester.

The following compounds are exemplified as ketones.

Examples include diethyl ketone, ethyl butyl ketone, methylhexyl ketone, mesityl oxide, cyclohexanone, methylcyclohexanone, acetophenone, benzophenone, acetonyl acetone, diacetone alcohol, and the like.

The following compounds are exemplified as ethers.

Examples include butyl ether, hexyl ether, diphenyl ether, dioxane, ethylene glycol dibutyl ether, diethylene glycol dibutyl ether, ethylene glycol diphenyl ether, and ethylene glycol monophenyl ether.

Aromatic hydrocarbons include p-xylene, isopropylbenzene, amylbenzene, mesitylene, cymene, 5-methyl-3-isobutyltoluene, dodecylbenzene, cyclohexylbenzene, biphenyl, methylbiphenyl, ethylbiphenyl, diethylbiphenyl, and trimethylbiphenyl. , benzylbenzene, phenyltolylmethane, xylyl phenylmethane, ditolylmethane,
trioctyldiphenylmethane, tribenzyldiphenylmethane, tolylxylylmethane, dixyllymethane, diphenylethane, tolylphenylethane, dixylylethane, phenylisopropylphenylethane, tolyldiisopropylphenylethane, trimethylisopropylphenylethane, diphenylpropane , ditolylpropane, phenyltolylpropane, phenylxylylpropane, tolylxylylpropane, dibenzylbenzene, dioctylbenzylethylbenzene, dibenzyltoluene, tetrahydronaphthyl phenylmethane, tetrahydromethylnaphthyl phenylethane, etrahydronaphthyl phenyl methane Examples include enylethane, naphthylphenylmethane, methylnaphthylphenyl ethane.

Examples of combinations of the color forming agent 5 and the color changing agent 6 used in the present invention are as follows.

() Electron-donating color-forming organic compounds (color-forming agents) and acids (phenolic hydroxyl group-containing compounds, organic carboxylic acids, inorganic solid acids, etc.) (color-changing agents) () PH indicators (color-forming agents) and acids or alkalis (color-changing agents) () Polyhydric hydroxy compound having an iron compound and a phenolic hydroxyl group Examples of the electron-donating color-forming organic compounds used in the present invention include diarylphthalides, polyarylcarbinols, leucoaulamins, and acylauramines. Mines, arylauramines, rhodamine B-lactams, indolines, spiropyrans,
There are fluorans, etc.

Examples of these compounds are shown below.

Crystal violet lactone, malachite green lactone, Michler hydrol, crystal violet carbinol, malachite green carbinol, N-(2,3-dichlorophenyl)leukouramine, N-benzoyluramine, N-acetyl auramine Min, N-phenyluramine, Rhodamine B lactam, 2-(phenyliminoethanedylidene)3,3-dimethylindoline, N-3,3-trimethylindolinobenzospiropyran, 8'-methoxy-N-3 , 3-trimethylindolinobenzospiropyran, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-methoxyfluorane, 3-diethylamino-6-benzyloxyfluorane, 1,2-benz-6 -diethylaminofluorane, etc.

As a compound having a phenolic hydroxyl group,
There are monophenols and polyphenols,
Furthermore, as a substituent, an alkyl group, an aryl group,
Examples include acyl groups, alkoxycarbonyl groups, and halogens. Examples of these compounds are shown below.

Tertiary-butylphenol, nonylphenol, dodecylphenol, α-naphthol, β
- Naphthol, hydroquinone monomethyl ether, p-chlorophenol, p-bromophenol, o-chlorophenol, o-bromophenol, o-phenylphenol, p-phenylphenol, methyl p-oxybenzoate, 3-isopropylcatechol , p-tertiarybutylcatechol, 4,4'-methylene diphenyl, bisphenol A, 1,2-dioxynaphthalene, 2,3
-dioxynaphthalene, chlorcatechol, bromocatechol, 2,4-dihydroxybenzophenone, phenolphthalein, methyl gallate,
Examples include ethyl gallate, propyl gallate, butyl gallate, hexyl gallate, octyl gallate, dodecyl gallate, cetyl gallate, stearyl gallate, tannic acid, and phenolic resin.

Inorganic solid acids include silica alumina, silica magnesia, bentonite, kaolin, fuller's earth, acid clay, activated clay, montmorillonite, attapulgite, zinc oxide, titanium oxide,
These include calcium sulfate, barium sulfate, aluminum sulfate, aluminum chloride, lead chloride, tin chloride, and arsenic dioxide.

Organic acids include acetic acid, propionic acid, butyric acid,
Such as caproic acid.

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

Examples of the polyhydric aromatic acid having a phenolic hydroxyl group or its ester include gallic acid, tannic acid, methyl gallate, ethyl gallate, propyl gallate, butyl gallate, octyl gallate, dodecyl gallate, and stearyl gallate. and so on.

In the present invention, the diaphragm through which the molten coloring agent permeates is made of ethylene-vinyl acetate copolymer, acrylic ester copolymer, paper, nonwoven fabric, etc. In particular, ethylene-vinyl acetate copolymer and acrylic ester copolymer are used as the diaphragm. Copolymers are preferred. By selecting the material and thickness, the time required for the molten coloring agent to reach the display layer can be adjusted. In other words, by providing diaphragms with different thicknesses within the same sheet, the molten colorant passes through thinner areas more quickly and discolors the display layer in that area, but the test object is When the temperature returns to the freezing temperature, the coloring agent solidifies again in the thicker portions and does not reach the display layer, causing no discoloration. If a frozen food is exposed to a temperature above a predetermined temperature for a long period of time, the display layer corresponding to the thick portion will also change color. As a result, the thermal history (temperature and time) of the frozen food can be known.

Furthermore, within the same sheet, the material of the diaphragm (e.g.
By changing the size of the eyes and the affinity with the coloring agent, the transmission rate of the coloring agent differs, so that the discoloration of the display layer occurs faster or slower in some areas. Of course, the material and thickness of the diaphragm may be changed at the same time.

The thickness of the diaphragm can be selected depending on the type of material, temperature and time required for control, etc., but it is usually 20 μm.
m or less is appropriate.

The diaphragm is usually formed by coating a film-forming resin such as ethylene-vinyl acetate copolymer on the microcapsule layer of the coloring agent or on the display layer.
It is effective to apply it in strips at regular intervals. For areas with different thicknesses of the diaphragm or areas of different materials, the sheet itself should be painted in a different color, or the coloring agent or type of coloring agent should be applied differently so that the coloring agent or coloring agent is different. is more preferable because it is easier to understand.

The display layer is not particularly limited as long as it can adsorb the molten coloring agent and allow observation of the resulting color change. Specifically, paper, woven fabric, nonwoven fabric, etc. are exemplified. Typically it is paper. Although the thickness is not particularly limited, it is preferably 10 to 100 μm.
Furthermore, this display layer may be made of a material on which a color former or a color change agent is adsorbed, and a color former containing a color change agent or a color former may be used in combination. Next, the microencapsulation technology used in the present invention is as follows:
Coacervation method, which is a well-known method, insitu
A polymerization method, an interfacial polymerization method, an underwater curing coating method, a phase separation method from an aqueous solution, a phase separation method from an organic solution, etc. can be used arbitrarily.

There are knife coaters, brush coaters, reverse roll coaters, bar coaters, air knife coaters, etc. to apply the microcapsules containing the coloring agent onto the diaphragm, but the air knife coater method is used to prevent the microcapsules from being destroyed during application. is desirable. When the sheet is used, the microcapsules that contain the coloring agent are destroyed, but the method is not particularly limited, but changes depending on time and temperature when the entire system is exposed to a temperature higher than a specified temperature. In order to understand this, it is desirable to destroy the material 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 the particle size is 1 μm or less, it is difficult to break, and if the particle size is 300 μm or more, the particle size is large and causes problems in the coating process.

Film-forming components used in microcapsules include gelatin, alginic acid, acrylic polymers, methacrylic polymers, melamine, and epoxy polymers, which 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 coating the microcapsules on the substrate, methods using an organic solvent solution type binder, a nonaqueous emulsion type binder, an aqueous solution type binder, and an aqueous emulsion type binder can be considered.

When an organic solvent type binder is used, the organic solvent itself acts as one of the discoloring components, or the organic solvent extracts the microencapsulated components before the microcapsules are broken and discolors the temperature indicator sheet before use. There are cases. As a result, the discoloration change at the discoloration temperature of the temperature indication sheet becomes unclear, or in some cases, the discoloration cannot be confirmed at all. Furthermore, it is difficult to use industrially because of the odor, flammability and hygiene problems of organic solvents.

Similarly, non-aqueous emulsions suffer from the same drawbacks as those using organic solvent solution type binders. 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, both organic solvent solution type binders and non-aqueous emulsion type aqueous solution type binders have many drawbacks and pose practical problems.

On the other hand, when microcapsules are dispersed in an aqueous emulsion type binder and applied to a substrate, there are no problems such as discoloration caused by solvents or impregnation/elution of the microcapsules as seen with the organic solvent type binders mentioned above, and the discoloration temperature The change in hue becomes extremely 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 can be obtained with low viscosity compared to solid content, the selection range of microcapsule/adhesive solid content weight ratio during application is wide, and the desired color change performance can be determined by adjusting the temperature indication 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 it has been wound 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. Examples include natural polymers such as rubber, glue, and starch, and synthetic polymers such as polyvinyl acetate, vinyl acetate copolymers, acrylic acid ester copolymers, vinylidene chloride copolymers, epoxy resins, and butadiene copolymers. Particularly preferred is vinyl acetate-ethylene copolymer.

The solid content concentration of the emulsion 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. Generally, a solid content concentration of about 10 to 70% by weight is preferred.

The speed of discoloration of the temperature indicator sheet varies depending on the mixing ratio of microcapsules and 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. Furthermore, if the concentration of the emulsion solid content becomes too high, the rate of discoloration of the temperature indicator sheet will slow down. Usually, it is appropriate to use a microcapsule/emulsion weight ratio of about 30/1 to 1/2 in terms of solid content.

Additionally, additives may be added to the coloring agent, the substance that interacts with it to cause discoloration, and the diaphragm to improve the necessary conditions within the range that does not interfere with the irreversible discoloration that is the objective of the present invention. can.
Typical such additives include antioxidants, ultraviolet absorbers, inorganic fillers, pigments, plasticizers,
There are lubricants, antistatic agents, etc.

Methods for attaching the temperature indication sheet of the present invention to cold-preserved products include pasting with an adhesive, hanging it as a label, and directly adhering it to a low-temperature-preserving product container. In this case, it is preferable to provide an opaque layer between the adhesive layer and the coloring agent layer so that the melted coloring agent does not diffuse.

Preferred examples for which the temperature indication sheet can be used include, but are not limited to, kamaboko, raw noodles, yogurt overnight pickles, and patsuku sushi.

Effects of the Invention By using the temperature support sheet of the present invention, it is possible to easily determine how long a frozen food is exposed to a temperature higher than its storage temperature. That is, by knowing the thermal history of frozen foods in more detail, sellers and consumers can 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 20g of methyl myristate was added to a 5% gelatin aqueous solution.
The mixture was mixed with 100 g of oil, heated to 50°C, and stirred to form minute oil droplets.

Subsequently, 75 ml of a 5% carboxymethylcellulose aqueous solution was added to adjust the pH to 4.8, and the mixture was cooled to 5°C.

After adding 37% formalin, adjust the pH to 10,
The temperature was gradually raised to 50°C. Microcapsules with a particle size of 1 to 100 μm were obtained. Concentrate the system to 40% moisture
A microcapsule wet cake was obtained. An ink was prepared by mixing wet cake and Polysol P-300 at a ratio of 3:1.

Color the entire surface of commercially available thermal paper, and add 5g of Sumikaflex 830 on one side and the other side as a diaphragm on the back of the coloring.
10 g/m ² of the ink was applied and dried, and 40 g/m ² of the above ink was applied to the coated surface and dried.

Polysol EVA/AD-5 as a permeation prevention agent
was applied to the ink-coated surface at 10 g/m ² and dried.

On the other hand, apply 40 g/m ² of Nikazol TS-444 to the release paper.
It was coated, dried, and laminated with the laminated thermal paper to obtain a test label.

A force of about 20 to 100 kg/cm ² was applied to the label to break the microcapsules, and the microcapsules were placed in a thermostat at 10°C. When observed one week later, no changes were observed. Thereafter, when the temperature was raised to 13° C., the area to which 5 g/m ² of the diaphragm was coated began to change color after 3 hours, and discoloration was completed after 8 hours.

Areas coated with 10 g/m ² of diaphragm began to discolor after 10 hours and were complete after 20 hours.

Example 2 20g of methyl myristate, methyl methacrylate
10g and 50mg of AIBN were mixed and dissolved.

This was dispersed in 100 g of 0.5% methylcellulose aqueous solution to form minute oil droplets, and reacted at 75°C for 5 hours.
Microcapsules with a particle size of 10 to 15 μm were obtained.

The system was concentrated to obtain a microcapsule wet cake with a water content of 30%. Wet cake and polysol
An ink was prepared by mixing MC-5 at a ratio of 3:1.

Color the entire surface of commercially available thermal paper, apply 5 g/m ² of Sumikaflex 830 on one side and Polysol P-25 on the other side as a diaphragm on the back of the color, dry, and apply 50 g/m ² of the above ink on the coated surface. and dried. As a permeation prevention agent, Movinyl 184 was applied at 5 g/m ² to the ink-coated surface and dried.

On the other hand, add 40g/Nicasol TS-444 to the release paper.
m ² was coated, dried, and laminated with the laminated thermal paper to obtain a test label.

A force of about 20 to 100 kg/cm ² was applied to the label to destroy the microcapsules, and the microcapsules were placed in a thermostat at 10°C.
When observed one week later, no changes were observed. Thereafter, when the temperature was raised to 13°C, the area coated with Sumikaflex 830 began to change color after 2 hours, and the color change was completed within 5 hours. Polysol P-
The area where 25 was applied began to discolor after 10 hours and was finished after 24 hours.

Example 3 2g of sodium alginate, 1g of gelatin and 150ml of water
g, and methyl myristate was added dropwise under stirring to form minute oil droplets. 10% calcium chloride aqueous solution
A fine oil droplet dispersion was dropped into 500 g to obtain microcapsules.

The system was concentrated to obtain a microcapsule wet cake with a water content of 40%. Ink was prepared by mixing wet cake and Sumikaflex 400 at a ratio of 5:1.

Commercially available thermal paper was colored on the entire surface, and Sumikaflex 830 was applied on one side as a diaphragm at 3 g/m ² ,
10 g/m ² of the ink was applied to the center and 16 g/m ² to the other side and dried, and 30 g/m ² of the above ink was applied to the coated surface and dried. Cosenol GH as a permeation inhibitor
-20 was applied at 15 g/m ² onto the ink-coated surface and dried.

On the other hand, add 40g/Nicasol TS-444 to the release paper.
m ² was coated, dried, and laminated with the laminated thermal paper to obtain a test label.

A force of about 20 to 100 kg/cm ² was applied to the label to break the microcapsules, and the microcapsules were placed in a thermostat at 10°C. When observed one week later, no changes were observed. Thereafter, when the temperature was raised to 13° C., the area to which 3 g/m ² of the diaphragm was coated began to change color after 1 hour, and discoloration was completed after 3 hours. Diaphragm 10g/m ²
The applied area began to discolor after 6 hours and was complete after 12 hours.

Areas coated with 16 g/m ² of diaphragm began to discolor after 20 hours and were finished after 40 hours.

Example 4 An oil-soluble dye (Oil Violet #732, manufactured by Orient Chemical Co., Ltd.) was dissolved in methyl myristate to form a 1% solution. 40 g of the monomer MMA, 60 g of the above solution, and 0.2 g of AIBN were uniformly mixed and dispersed in 150 g of a 0.5% methyl cellulose aqueous solution to form minute oil droplets. When the reaction was carried out at 75°C for 5 hours, microcapsules with a particle size of 10 to 50 μm were obtained. A cake with a solid content of 65% was obtained by filtration.

This wet cake and Sumikaflex #830 (manufactured by Sumitomo Chemical Co., Ltd.) as a binder were mixed at a ratio of 3:1 and applied to the surface of 55 g of high-quality paper. The coating amount was 40 g/m ² . This capsule processed paper-
After cooling to 10° C., the microcapsules were destroyed by applying a force of about 20 to 100 kg/m ² and left at room temperature. The back surface immediately began to change color to light purple, and color development was completed in 1 to 2 hours. When measured at 13℃, 1
It starts to change color after hours, and the coloring is completed in about 6 hours.
No coloration was observed even after leaving it overnight at 10°C.

Next, when the amount of microcapsules applied was 70 g/m ² , the behavior of color development was similar to that of 40 g/m ² or the color developed more clearly.

Next, in order to control the speed of color development, we investigated a transmission control membrane. Movinyl 184E (manufactured by Hoechst Synthesis Co., Ltd.) was coated on the base paper at a thickness of 3 g/m ² , and after drying, microcapsule ink was coated at 70 g/m ² . When the microcapsules were destroyed and left at room temperature, color development started after 1 hour. At 13°C, color development started after 5 hours and completed after about 10 hours.

Example 5 Crystal Viret Lactone (CVL) 0.5g
was dissolved in 60 g of methyl myristate. As monomers, MMA40g, above solution 60g, AIBN0.2
Dissolve g uniformly into 0.5% methyl cellulose solution.
It was dispersed in 150 g using a homogenizer to form minute oil droplets. After reacting at 75℃ for 5 hours, filter and incubate for 10~
A wet cake of 50 μm microcapsules was obtained. This wet cake (solid content 68%) and Polysol MC-5 (manufactured by Showa Kobunshi Co., Ltd.; solid content 50%) were mixed at a ratio of 3:1, and commercially available bottom paper (Kanzaki Paper Co., Ltd.) was mixed.
It was coated on the back side of a 40g/m ² film (manufactured by J.D.) at a thickness of 40g/m 2 . After destroying the microcapsules by applying a pressure of 20 to 100 kg/cm ² , the microcapsules were left in a thermostat at 13° C., and color development started in about 1 hour and was completed in about 6 hours.

Next, use Sumikaflex #830 on the back side of the bottom paper.
After applying 3g/ ^m2 of microcapsules, 40g/m2 of
The same color development test as above was conducted on the product coated with ^m2 . There was no change at all for about 3 hours,
Thereafter, discoloration started gradually and was completed in 8 hours.

Similarly, 3 g/ ^m2 of Polysol P-25 (manufactured by Showa Kobunshi Co., Ltd.) was applied to the back side of the bottom paper, and 40
g/ ^m2 coated with microcapsules is 13
The discoloration started in about 6 hours at ℃ and was completed in 10 hours.

Example 6 50 g of ethyl laurate was mixed with 150 g of a 1% Euramin P-6300 aqueous solution to form minute oil droplets. PH4
-5 and reacted at 50°C for 5 hours to obtain microcapsules. The system was concentrated to obtain a microcapsule wet cake with a water content of 30%. Ink was prepared by mixing wet cake and Polysol MC-5 at a ratio of 5:1.

A commercially available thermal paper was colored on its entire surface, and 5 g/m ² of Sumikaflex 830 was coated on one side and 10 g/m 2 on the other side as a diaphragm on the back side of the colored paper, and dried. 40 g/m ² of the above ink was coated on the coated surface and dried. As a permeation prevention agent, apply Polysol EVA AD-5 to the in-applied surface.
g/m ² coated and dried.

On the other hand, add 40g/Nicasol TS-444 to the release paper.
m ² was coated, dried, and laminated with the laminated thermal paper to obtain a test label. 20~100Kg/ on label
The microcapsules were broken by applying a force of about cm ² and placed in a -15°C incubator. When observed two weeks later, no changes were observed. After that-
When the temperature was raised to 5° C., the area coated with 5 g/m ² of diaphragm began to change color after 2 days, and discoloration was completed after 4 days. The area to which 10 g/m ² of diaphragm was applied began to discolor after 4 days and was completed after 7 days.

Example 7 Terephthalic acid dichloride and methyl laurate
50 g were mixed and mixed with a 1% aqueous sodium hydroxide solution in which 5 g of bisphenol A was dissolved to form minute oil droplets. The mixture was reacted at 50°C for 2 hours to obtain microcapsules. The system was concentrated to obtain a microcapsule wet cake with a water content of 40%. An ink was prepared by mixing wet cake and Polysol P-300 at a ratio of 4:1.

A commercially available thermal paper was colored over its entire surface, and 5 g/m ² of Sumikaflex 830 was coated on one side and 10 g/m 2 on the other side as a diaphragm on the back side of the colored paper, and dried. 40 g/m ² of the above ink was coated on the coated surface and dried. As a permeation prevention agent, polysol EVA/AD-5 is applied to the ink coating surface.
It was applied at 10 g/m ² and dried.

On the other hand, add 40g/Nicasol TS-444 to the release paper.
m ² was coated, dried, and laminated with the laminated thermal paper to obtain a test label. 20~100Kg/ on label
Destroy the microcapsules by applying a force of about ^cm2 ,
It was placed in a thermostat at 0°C. When observed two weeks later, no changes were observed. Thereafter, when the temperature was raised to 4° C., the area to which 5 g/m ² of the diaphragm was applied began to change color after one day, and discoloration was completed after two days. The area to which 10 g/m ² of diaphragm was applied began to discolor after 2 days and was completed after 4 days.

Example 8 Mix 5 g of Epicol 828 and ethyl myristate to create a 0.5% carboxymethylcellulose aqueous solution.
Disperse in 200g, gradually add curing agent, and heat at 80℃.
The mixture was reacted for 5 hours to obtain microcapsules. The system was concentrated to obtain a microcapsule wet cake with a water content of 30%. An ink was prepared by mixing the wet cake with Sumikaflex 400 at a ratio of 3:1.

A commercially available thermal paper was colored on its entire surface, and 5 g/m ² of Sumikaflex 830 was coated on one side and 10 g/m 2 on the other side as a diaphragm on the back side of the colored paper, and dried. 40 g/m ² of the above ink was coated on the coated surface and dried. As a permeation prevention agent, polysol EVA/AD-5 is applied to the ink coating surface.
It was applied at 10 g/m ² and dried.

On the other hand, add 40g/Nicasol TS-444 to the release paper.
m ² was coated, dried, and laminated with the laminated thermal paper to obtain a test label. 20-100Kg/ ^cm2 on label
Destroy the microcapsules by applying a certain amount of force, and
It was placed in a thermostat at ℃. When observed after 10 days,
No changes were observed. Thereafter, when the temperature was raised to 8° C., the area coated with 5 g/m ² of the diaphragm began to change color after 6 hours, and discoloration was completed after 10 hours. Areas coated with 10 g/m ² of diaphragm began to discolor after 16 hours and were complete after 24 hours.

The materials or product names used in Examples 1 to 8 are products of the following companies: Commercially available thermal paper...manufactured by Honshu Paper Co., Ltd.; SH-65BX-
10 Polysol...Showa Kobunshi Co., Ltd. Sumikaflex...Sumitomo Chemical Co., Ltd. Gohsenol...Nippon Gosei Kagaku Kogyo Co., Ltd. Movinyl...Hoechst Gosei Co., Ltd. Nikazole...Nippon Carbide Co., Ltd. Euramin...Mitsui Higashi Pressure Chemical Co., Ltd. Epicote... Ciel Chemical Co., Ltd.

[Brief explanation of drawings]

1 to 6 are schematic cross-sectional views of the temperature indicating sheet of the present invention. 1,1'...diaphragm, 2...wax-like substance, 3
... Display layer, 4 ... Microcapsule, 5 ... Color former, 6 ... Color change agent.

Claims (1)

[Claims] 1 () A coloring agent that melts at a predetermined temperature () A diaphragm through which the molten coloring agent permeates () A display layer that absorbs the molten coloring agent; 1. A temperature indicating sheet encapsulated in destructible microcapsules, disposed on the opposite side of a display layer with a diaphragm in between, the diaphragm having parts of different thicknesses or partially made of different materials.