JPH0777774B2 - Temperature instruction label - Google Patents

Description

TECHNICAL FIELD The present invention relates to a temperature indicating label. More specifically, it relates to a temperature instruction label for instructing two or more control temperatures.

Frozen food, chilled food, fresh flowers, pharmaceuticals, etc. require strict temperature control during transportation and storage. Therefore, there is a demand for a method of easily determining whether or not each article is under the temperature to be controlled.

(Prior Art) As an indicator for temperature control, one utilizing the melting phenomenon of a colored solid resin acid and the capillary phenomenon of a blotter paper, as already proposed in USP3954011, JP-B-57-4319.
No. 57-28559 and the like, which utilize the fact that the degree of activation of lipase enzyme differs depending on the temperature, and the degree to which the lipase enzyme can be colored with a pH indicator is proposed.

(Problems to be Solved by the Invention) However, these methods are disadvantageous in that they are expensive as a temperature control indicator that can be applied to each of a large amount of articles and cannot be used easily.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a temperature indicating label which enables strict temperature control and is easy to use.

(Means for Solving Problems) The inventors of the present invention have already conducted enormous studies to solve such problems, and have developed a color development system using a methine dye precursor and an oxidizing material into a temperature display unit. Apply,
An extremely characteristic and effective unit has been found (JP-A-60-053984). That is, the unit is
(1) A hydrophobic organic compound having an arbitrary melting point, (2) a methine dye precursor, and (3) an oxidizing material are used as essential constituent materials. Then, this temperature management unit comprises:
(2) and (3) or microcapsules in which (2) is dissolved in (1) and (3) are held as an essential component on a support.

In this unit, the hydrophobic organic compound (1) is used by selecting its melting point at a temperature near the upper limit of the storage temperature of the applied article to be temperature-controlled. Therefore, the management of the storage temperature by this unit is performed by the following processing and mechanism. That is, when the unit is applied to an article, the microcapsules on the support are broken by an appropriate method. Since the melting point of (1) in the microcapsule is near the upper limit of the storage temperature of the article to which the unit is applied, it is solid at the desired storage temperature of the article and does not cause contact between the methine dye and the oxidizing material. When the temperature exceeds the desired control temperature, (1) melts and diffuses, and both are brought into contact with each other to develop the color of the methine dye precursor.

The feature of this unit is that it utilizes the irreversible color development of this methine dye, and once it develops under abnormal temperature, it does not disappear, so it is possible to ensure that the temperature control status of an article is abnormal. I can know.

The present invention is to provide a temperature indicating label that makes it possible to know the managed temperature in detail by making use of the characteristics of the temperature managing display unit as described above. That is, in the present invention, a methine dye precursor is dissolved on the same support in a temperature management display unit using a hydrophobic organic compound having an arbitrary melting point, a methine precursor dye, and an oxidizing material. A temperature-indicating label, characterized in that microcapsules containing two or more kinds of hydrophobic organic compounds each having an arbitrary melting point are held separately to indicate two or more control temperatures, and a methine dye. 2 precursors
Two or more kinds may be used depending on the hydrophobic organic compound having an arbitrary melting point of one kind or more. An object of the present invention is to enhance color development sensitivity to temperature by dissolving a methine dye precursor in a hydrophobic organic compound and then microencapsulating it for use.

In the temperature indicating label of the present invention, various film-like webs, specifically, paper, impregnated paper, synthetic paper (various synthetic resin-based paper-like films), various plastic films, etc. are used as the support. To be

Since the temperature indicating label is often used for refrigerated or frozen foods that are exposed to a water-rich environment, the support is preferably water-resistant synthetic paper, various plastic films or resin-impregnated paper.

The thickness of the support is generally 30 to 200 µ.

A hydrophobic organic compound having an arbitrary melting point (hereinafter, simply referred to as a hydrophobic organic compound) is a compound that can be interconverted into a solid-liquid depending on the ambient temperature inside the microcapsule and is released from the microcapsule. Thus, it is a non-volatile hydrophobic organic compound that behaves as a solid below a predetermined temperature and as a liquid above a predetermined temperature. Specific compounds include tricaproin glyceride, nonylbenzene, diethyl pimelic acid, n-butyl benzoate, n-decylcyclopentane, 1-pentylnaphthalene, octyl enanthate, and capric acid in order of increasing melting point. Heptyl, 1-n-butylnaphthalene, azelaic acid-diethyl, methyl caproate, 1-hexylnaphthalene, dodecyl acetate, linolein alcohol, octyl caprylate, decyl acetate, ethyl undecanoate, decylbenzene, 1,6-dimethylnaphthalene, 1-ethylnaphthalene, 1-linoleo-2,3-dicaprylin-glyceride, undecyl acetate, 1-lauro-2,3-dilinolein triglyceride, 1-caproyl-2,3-distearin triglyceride, undecyl caproate, caprylic acid- Heptyl, n- Nylcyclohexane, 1-propylnaphthalene, n-undecylcyclopentane, 1-myristo-2,3-dilinoleintoglyceride, 1-heptylnaphthalene, 2-ethylnaphthalene, 1-caprylyl-2,3-diolein-triglyceride, Diethyl sperate, undecylbenzene, n-dodecyl-cyclopentane, ethyl tridecanoate, butyl laurate, dodecyl caproate, methyl ricinoleate, 2-n-pentylnaphthalene, 1,3-dimethylnaphthalene, dimethyl azelate, sperine Dimethyl acid, 2-n-hexylphthalene, heptyl laurate, 1-n-octylnaphthalene, ethyl laurate, n-decylcyclohexane, diethyl sebacate, 1-linoleo-2,3-dicaprin-
Triglyceride, butyl myristate, 2-n-heptylnaphthalene, tetradecyl caproate, n-dodecylbenzene, 1-oleo-2,3-dicaprin-triglyceride, 2-oleo-1,3-dicaprin-triglyceride, methyl laurate, n-Tridecylcyclopentane, n-undecylcyclohexane, tridecyl caproate, nonylnaphthalene, n-tetradecylcyclopentane, n-pentadecane, tridecylbenzene, 1-heptadecene, 2-n-octylnaphthalene, 2-n- Nonylnaphthalene, 2-undecane, ethyl myristate, n-dodecylcyclohexane, 1-myristo-2,3
-Diolein-triglyceride, isobutyl palmitate, ethyl pentadecanoate, decylnaphthalene, n-tetradecylbenzene, pentadecyl caproate, n-pentadecyl-cyclopentane, 1-octadecene, hexadecane, 1-palmito-2,3-diolein-triglyceride , Butyl palmitate, methyl myristate, methyl pentadecanoate, amyl palmitate, methyl oleate, 2-n-decylnaphthalene, propyl palmitate, n-hexadecylcyclopentane, octadecane, apiol, diethyl benzylidenemalonate, nonadecane, Benzyl cinnamate, diethyl terephthalate, 1
-Tetradecanol, 1,2-diphenylethane, 1,3,5-
Hydrophobic organic compounds such as trimethoxybenzene, p-dimethoxybenzene, octadecanol, 9-ethylanthracene, and p-methylbenzophenone having a sharp melting point at -30 ° C to 70 ° C and having a boiling point of 200 ° C or more are exemplified. However, of course, it is not limited to the exemplified compounds.

The methine dye precursor is a generic term for colorless or light-colored compounds represented by the general formula (I).

(In the formula, X, Y and Z are phenyl group which may have a substituent, naphthyl group which may have a substituent, β-styryl group which may have a substituent or aromatic which may have a substituent. And a heterocyclic ring residue, which may be the same or different, and two of X, Y and Z may combine to form a ring. When the number of aromatic heterocyclic ring residues is 1 or less, at least one amino group, a substituted amino group or a lower alkoxy group in the phenyl group, naphthyl group or β-styryl group at the para position with respect to the central methine group of the molecule Group), typically, for example, 4,4 ', 4 "-tris (dimethylamino) triphenylmethane, 4,4', 4" -tris (diethylamino) triphenylmethane, 4,4'-bis (Methylamino) -4 "-dimethyl Triamino triphenylmethane dyes, such as amino triphenyl methane, e.g.
4,4'-bis (dimethylamino) triphenylmethane,
4,4'-bis (dimethylamino) -4 "-methyltriphenylmethane, 4,4'-bis (N-benzyl-N-ethylamino) triphenylmethane, 4,4'-bis (dimethylamino)- Diaminotriphenylmethane dyes such as 4 ″ -methoxytriphenylmethane, eg 4,4 ′
Monoaminotriphenylmethane type dyes such as -dimethoxy-4 "-dimethylaminotriphenylmethane and 4,4'-dimethoxy-3" -methyl-4 "-methylaminotriphenylmethane, for example, bis- (4- Naphthylmethane dyes such as dimethylamino-naphthyl-1) -4'-dimethylaminophenylmethane, for example bis (4
-Dimethylaminophenyl) -β-styrylmethane, β-styrylmethane-based dyes such as bis (4-dimethylaminophenyl) -β- (4'-dimethylaminostyryl) -methane, for example, bis (1-ethyl- 2-Methylindol-3-yl)-(4'-ethoxyphenyl)-
Methane, bis (1-ethyl-2-methyl-indole-
Examples thereof include indolylmethane type dyes such as 3-yl)-(4'-dimethylaminophenyl) -methane, and the methine type dyes described in JP-A-58-74389 can be used.

The methine dye precursor represented by the general formula (1) is
After being dissolved in a hydrophobic organic compound, it is microencapsulated and used for the label of the present invention. Among these methine dye precursors, those having a tendency to gradually undergo air oxidation coloring during storage or exposure to light are (1) water-soluble alkanolamines, (2) in order to increase the storage stability of the compound. An appropriate amount of one or more selected from water-soluble sequestering agents and (3) quaternary ammonium salts is added to a coating or printing composition containing microcapsules.

The water-soluble alkanolamines of (1) are alkanolamines having a tertiary amino group, such as tris-N- (2-hydroxyethyl) amine and tris-N-.
(2-hydroxypropyl) amine, tris-N- (3
-Hydroxypropyl) amine, N, N-dipropyl-N
Specific examples include-(2-hydroxyethyl) amine and the like.

Examples of the sequestering agent (2) include ethylenediamine-tetraacetic acid, N-hydroxyethyl-ethylenediamine-N, N ', N'-triacetic acid, diethylenetriamine-pentaacetic acid, N-hydroxyethyl-iminodiacetic acid, ethylenediamine-N. Specific examples include, N'-diacetic acid, 1,3-diaminopropan-2-oltetraacetic acid, nitrilotriacetic acid and their alkali metal salts. Further, as the quaternary ammonium salt of (3), lauryl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, distearyl dimethyl ammonium chloride, trimethyl benzyl ammonium and the like can be mentioned as specific examples.

When (1) an alkanolamine, (2) a sequestering agent, and (3) a quaternary ammonium salt are used, the total amount thereof is 1 to 100 relative to 100 parts by weight of the methine dye.
The amount is 00 parts by weight, preferably 1-1000 parts by weight.

The hydrophobic organic compound in which the methine dye precursor is dissolved can be prepared by various known methods such as (1) coacervation method using gelatin, (2) interfacial polymerization method, or (3) In-
It is microencapsulated by the Situ polymerization method. Among these, the microcapsules using the amino-aldehyde resin by the In-Situ polymerization method as a membrane material have (a) a dense wall membrane with low permeability, (b) a high solid content concentration, ( c) It is preferable in that it does not rot.

As the oxidizable material, a developer having the ability to form a colored dye by oxidizing the methine dye precursor by molecular contact with a methine dye precursor described later is used, and a preferable one is generally A non-volatile benzoquinone derivative substituted with an electron-withdrawing group represented by formula (I) or (II) can be given.

(In the formula, R _{1 to} R ₈ are a halogen atom, a cyano group, a nitro group,
Electron withdrawing selected from carboxyl group, alkoxycarbonyl group, aryloxycarbonyl group, aralkyloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group, aralkylsulfonyl group, alkoxysulfonyl group, aryloxysulfonyl group, aralkyloxysulfonyl group and acyl group. Which has at least one functional group and the other is a hydrogen atom, an alkyl group, an alkoxy group, an aralkyloxy group, an alkylthio group, or an arylthio group, and an adjacent carboxyl group may form an imide ring) Among them, preferred benzoquinone derivatives are
A non-volatile p-benzoquinone derivative in which two or more electron-withdrawing groups are substituted.

Specific examples of the benzoquinone derivative used in the present invention include 2,3-dicyano-5,6-dichloro-1,4-benzoquinone and 3,4-dibromo-5,6-dicyano-1,4- Benzoquinone, 2,3,5,6-tetrabromo-1,4-benzoquinone,
2,3,5,6-tetraiodo-1,4-benzoquinone, 2,3,5,6
-Tetraethoxycarbonyl-1,4-benzoquinone, 2,
3,5,6-Tetra-i-butoxycarbonyl-1,4-benzoquinone, 3,4,5,6-tetra-propyloxycarbonyl-1,4-benzoquinone, 2,5-diethoxycarbonyl-1,
4-benzoquinone, 2,5-di-n-hexyloxycarbonyl-1,4-benzoquinone, 2,5-di-cyclohexyloxycarbonyl-1,4-benzoquinone, 2,5-dibenzoyl-1,4-benzoquinone, 2,5-di-n-butoxycarbonyl-3,6-dichloro-1,4-benzoquinone, 2,5-di-
Ethoxycarbonyl-3,6-dibromo-1,4-benzoquinone, 2,5-di-n-octoxycarbonyl-3,6-dibromo-1,4-benzoquinone, 2,5-di-benzyloxycarbonyl-3 , 6-dichloro-1,4-benzoquinone, 2,5-dibenzoyl-3,6-dichloro-1,4-benzoquinone, 2,5
-Diacetyl-3,6-dibromo-1,4-benzoquinone, 2,
5-diethoxycarbonyl-3,6-diphenylsulfonyl-1,4-benzoquinone, 2,5-di-i-butoxycarbonyl-3,6-di-4'-tolylsulfonyl-1,4-benzoquinone, 2, 5-di-cyclohexyloxycarbonyl-3,6
-Di-4'-tolylsulfonyl-1,4-benzoquinone,
2,5-di-n-octyloxycarbonyl-3,6-di-
4'-cyclohexylphenylsulfonyl-1,4-benzoquinone, 2,5-di-n-hexyloxycarbonyl-
3,6-di- (3 ', 4'-dimethylphenylsulfonyl)
-1,4-benzoquinone, 3,4,5,6-tetraethylsulfonyl-1,4-benzoquinone, 2,3,5,6-tetra-n-octylsulfonyl-1,4-benzoquinone, 2,5-di -Cyclohexyloxycarbonyl-3-benzylsulfonyl-1,
4-benzoquinone, 2,5-di-n-butoxycarbonyl-
3- (p-tolyl) -sulfonyl-1,4-benzoquinone, 2,5-diethoxycarbonyl-3- (2 ', 5'-dimethylphenylsulfonyl) -1,4-benzoquinone, 2,5
-Di-n-butoxycarbonyl-3,6-di-n-butoxysulfonyl-1,4-benzoquinone, 2,5-di-4'-toluylsulfonyl-3,6-dibromo-1,4-benzoquinone, 2 -Benzoyl-1,4-benzoquinone, 2-phenylsulfonyl-1,4-benzoquinone, 2- (4'-methylphenyl) sulfonyl-1,4-benzoquinone, 2-
Examples thereof include benzoquinone derivatives such as (4'-diphenylsulfonyl) -1,4-benzoquinone and 2-benzylsulfonyl-1,4-benzoquinone, but the present invention is not limited thereto.

These benzoquinone derivatives are wet-milled in the presence of a surfactant or a protective colloid substance to be used as an aqueous suspension for the preparation of a coating liquid.The indicator label of the present invention has the above essential components on a support. There is something that is retained in the
Various inorganic or organic pigments such as kaolin, talc, titanium carbide, zinc oxide, white carbon, silica, aluminum hydroxide, urea formaldehyde resin fillers, polystyrene dispersions, etc. in order to adjust the surface properties, color development properties, etc. , And water-soluble binders, for example, polyvinyl alcohol, methyl cellulose, hydroxyethyl cellulose, soluble starch, casein, water-soluble binders such as vegetable gums, and further, states for preventing microcapsule from being destroyed by micropressure, for example, , Wheat starch, potato starch, cellulose powder and various synthetic resin particles are generally used in combination.

As an example of the constitution of the retaining layer, there may be mentioned a microcapsule encapsulating a hydrophobic organic compound in which a methine dye is dissolved and another component retained on the same surface or both surfaces of a support.

Since two or more hydrophobic organic compounds are used in the temperature indicating label of the present invention, it is preferable to form the holding layer containing the hydrophobic organic compound on the support by a printing method.

Therefore, the display label of the present invention is usually one in which a holding layer of a hydrophobic organic compound among the essential components is provided on the outermost layer of the support. The hydrophobic organic compound holding layer is formed so that two or more kinds are not mixed with each other on the support surface.
Preferably, they are formed in the order of the melting point of the hydrophobic organic compound, that is, the display temperature.

A typical example of the supporting layer of the temperature indicating label of the present invention is shown in FIG.

In FIG. 1, a layer (5) containing an oxidizing material is held on the upper surface of the support (6). The spacer layer (4) is held on the layer (5), and the capsule layers (1) to (3) encapsulating the hydrophobic organic compound in which the methine dye is uniformly dissolved are held thereon. In order to hold these layer (6), layer (5) and layer (4) on the support, various methods capable of forming such a holding layer can be adopted. Usually, a coating method is often used.

That is, an oxidizing material is mixed as a fine particle dispersion obtained by finely pulverizing, preferably in the presence of a surfactant, with various other materials such as an inorganic pigment and adhesives to prepare a coating liquid. . This coating liquid is applied onto a support by various coating methods such as air knife coating, bar coating, blade coating, and kiss coating, and dried to form a holding layer (5) containing an oxidizing material.
The coating layer is generally ² to 20 g / m ² .

The spacer layer (4) is held on the layer (5), and the hydrophobic organic compound in which the dyes of the layers (1), (2) and (3) are dissolved is melted and diffused in the spacer layer (4). It is a layer for controlling the time required for contact with the oxidizing material of the layer (5) to develop color. This spacer layer is a layer containing a polymer substance as an essential component.

As the polymer substance, for example, polyvinyl alcohol,
Synthesis of natural, semi-synthetic or synthetic water-soluble polymers such as polyacrylamide, carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, gelatin, casein, starch derivatives, styrene, butadiene rubber latex, methyl methacrylate-butadiene rubber latex, chloroprene rubber latex Rubber latexes, latex modified products, and synthetic resin dispersions obtained by emulsion-polymerizing various unsaturated monomers alone or in the presence of two or more kinds, for example, homopolymers of various acrylic monomers. And a copolymer dispersion (for example, styrene-butyl acrylate copolymer emulsion, acrylonitrile-ethyl acrylate-butyl acrylate copolymer emulsion, styrene-ethyl acrylate). Preparative copolymer) is a water-soluble or water-dispersible polymeric materials typified. These polymer substances are entirely or partially coated on the upper layer of the developer layer containing the benzoquinone derivative. As a coating method, air knife coating,
Conventional means such as Mayer bar coating and blade coating are used. The coating amount is appropriately determined depending on the polymer substance used and the required color development time characteristics. Generally, 0.5 to 10 g / m ^{2 is} coated.
Alternatively, the layer (4) may be formed by a method such as a printing method or a hot melt coating method.

The temperature indicating label of the present invention is such that two or more layers, in which a methine dye precursor is dissolved and microcapsule-containing hydrophobic compounds having different melting points are contained on the layer (4), are mixed with each other. It is characterized in that it is formed without. These layers to be formed on the layer (4) are arranged in the order of the melting point of the hydrophobic compound, or are formed appropriately according to the label design.

The layer (4) is not always necessary depending on the purpose of applying the label, and the layer (5) is not required to be retained.
The layers (1), (2) and (3) may be immediately retained on top of.

FIG. 1 shows three layers (1), (2) and (3) containing microcapsules of hydrophobic organic compounds each having a different melting point formed side by side. In order to form these layers on the layer (4), a printing method is often used because these layers are so-called partially formed.

The coating liquid containing microcapsules is prepared by adding a water-dispersible or water-soluble adhesive to the microcapsule slurry and, if necessary, various additives. As a method of printing such a coating liquid, various printing methods such as screen printing, flexographic printing and gravure printing can be applied.

As described above, the temperature indicating label shown in FIG. 1 holds the essential components on the support. At this time, if the methine dye precursor contained in the microcapsules has different hue or color tone corresponding to the hydrophobic organic compound, it is convenient to identify the management situation.

In such a label holding the essential components, a protective layer is further formed if necessary, and an adhesive layer (7) and a release paper (8) are provided on the back surface.

(Operation and effect) The temperature display label of the present invention can be applied to an article to be temperature-controlled, and the management status can be more strictly known in relation to a desired temperature. Therefore, it is possible not only to judge whether the management status is correct or not, but also to grasp the contents of the management status. That is, the present invention provides a temperature instruction label for storage temperature control that can be easily used and that allows the user to know the temperature control condition exactly.

(Examples) Hereinafter, the present invention will be specifically described with reference to Examples.

Example 1 A polypropylene-based synthetic paper (Oji Okaka Synthetic Paper YUPO FPG-90) was coated with an aqueous coating solution (30%) having the following composition.
Used as an aqueous dispersion) Solid parts by weight Kaolin 60 Light calcium carbonate 40 Dispersant 0.4 Binder Polyvinyl alcohol 6 (Used as an aqueous solution) SBR latex 8 (Used as an aqueous dispersion) Oxidizing material * 1) 4 (As an aqueous dispersion Use) * 1) Oxidizing material 2,5-di-isobutoxycarbonyl-3,6-di-p-tolylsulfonyl-1,4-benzoquinone using a Mayer bar coater and the dry coating amount was 6 g / m ² . Thus, a developer layer was provided. Acrylic nitrile and butyl acrylate as the main ingredients are diluted to 20% on the upper layer, and the dry coating amount is
A spacer layer was provided so as to have a weight of 2.5 g / m ² .

Then, on the silicone treated 80g / m ² glassine release paper,
An acrylic emulsion pressure-sensitive adhesive having a thickness of 30 μm was applied and dried, and the pressure-sensitive adhesive surface was bonded to the back surface of the above-mentioned synthetic paper to obtain a printing original fabric.

Next, water-based inks [A], [B] and [C] having a solid content of 40 wt% having the following composition were prepared.

Ink [A] Solid part by weight (1) Undecanoic acid (used as an aqueous dispersion) in which 100 2% by weight of 4,4'-bis- (N-dimethylamide) -4 "-ethoxytriphenylmethane was dissolved Microcapsules of melamine resin film (2) MSBR latex 20 (used as an aqueous dispersion) (3) Trimethylbenzylammonium chloride 1 (4) Sodium alginate 2 (used as an aqueous solution) Ink [B] (1) 4,4 Microcapsules of 1-myristo-2,3-dilinolein glyceride melamine resin film in which 2% by weight of ′, 4 ″ -tris (N-dimethylamino) -triphenylmethane was dissolved (2) MSBR latex 20 (3) Trimethylbenzylammonium chloride 1 (4) Sodium alginate 2 Ink [C] (1) Bis (1-ethyl-2-methylindole) -3-yl) -4'-dimethylaminophenyl 100 Microcapsules of melamine resin film of diethyl sperate dissolved in 2% by weight of methane (2) MSBR latex 20 (3) Trimethylbenzylammonium chloride 1 (4) Sodium alginate 2 The inks [A], [B], and [C] were screen-printed at different positions on the printing original fabric so as not to overlap with each other (dry coating amount: 15 g / m ² ).

Further, a 2 μm-thick overcoat printing containing an acrylic emulsion as a main component was applied on the entire upper layer, and the die was die-cut to obtain a temperature indicating label.

After destroying the microcapsules and activating the label, the label of the ink [A] is green at -18 ° C or higher, and the label of the ink [B] is blue-purple at -12 ° C or higher. C] The printed portion develops red color at -8 ° C or higher.

Comparative Example 1 Synthetic paper was coated with an oxidizing material layer and a spacer layer in the same manner as in Example 1. Furthermore, on the upper layer,
An aqueous suspension obtained by wet milling 4,4′-bis (N-dimethylamino) -4 ″ -ethoxytriphenylmethane in the presence of a small amount of triethanolamine and polyvinyl alcohol has a dry coating amount of It was coated and dried so as to be 1 g / m ² to provide a methine dye precursor-containing layer.

Next, an acrylic emulsion pressure-sensitive adhesive was applied to a silicone-treated 80 g / m ² glassine release paper in a thickness of 20 μm, and the dried pressure-sensitive adhesive surface was attached to the back surface of the above-mentioned synthetic paper to obtain a printing raw material.

Next, three types of water-based inks having the following composition and a solid content of 40 wt% were prepared.

(Inks A, B, C) Solid parts by weight Hydrophobic organic solvent [* 1] * 2) * 3] microcapsules 100 (used as an aqueous dispersion) SBR latex 20 (used as an aqueous dispersion) Hydroxyethyl cellulose (Used as an aqueous solution) Polyacrylamide 0.5 (Used as an aqueous solution) * 1) Microcapsules of ethyl undecanoate melamine resin film * 2) Microcapsules of 1-myrista-2,3-dilinolein glyceride melamine resin film * 3) Microcapsules of melamine resin film of diethyl spernate. The above three inks were applied to different places of the methine dye precursor-containing layer of the above-mentioned raw fabric for printing by using a screen printing plate having a polyester mesh of 150 mesh. Partially printed. The dry coating amount of the partially printed portion was 10 g / m ² . The screen-printed sheet was die-cut into a label to obtain a temperature indicating label.

In the label of this example, after the microcapsules are destroyed and activated, when exposed to a temperature of -18 ° C or higher, the printed portion of the ethyl undecanoate microcapsules gradually develops a green color. Further, when exposed to a temperature of -12 ° C or higher, the microcapsule printed part of 1-myristo-2,3-dilinolein ceride gradually develops a green color. Further, when exposed to a temperature of −8 ° C. or higher, the microcapsule printed portion of diethyl sperate also develops a green color.

The temperature indicating labels produced in Example 1 and Comparative Example 1 were
After destroying and activating the microcapsules at -20 ° C,
It was stored under an environment of 15 ° C, and the color development behavior (relationship between time and color density) of the printed part of the ethyl undecanoate capsule was examined. The results are shown in Figure 2. As can be seen from FIG. 2, the temperature indicating label produced in Comparative Example 1 exhibited a slower color development behavior and a lower reached density than that of Example 1.

The reason for this is presumed as follows. That is, in the temperature indicating label produced in Example 1, since the dye exists in a state of being dissolved in the hydrophobic organic compound, the dye and the hydrophobic organic compound immediately penetrate into the spacer at a predetermined temperature, and the oxidizing material Reaches the layer and develops color. On the other hand, in the temperature indicating label of Comparative Example 1, the molten hydrophobic organic compound penetrates the spacer while dissolving the methine dye, reaches the layer of the oxidizing material, and develops color. Therefore, in the temperature display label of Comparative Example 1, the solubility of the methine dye in the hydrophobic organic compound varies depending on the storage temperature, so that the hydrophobic organic compound penetrates into the spacer before the methine dye dissolves, Methine dyes will not be used effectively. For this reason, the temperature indicating label produced in Comparative Example 1 has a slower coloring behavior than that of Example 1, and
It is judged that the density to be reached becomes low, and furthermore, it is difficult to obtain the color-developing behavior with good reproducibility.

[Brief description of drawings]

FIG. 1 is a schematic enlarged cross-sectional view showing one embodiment of the temperature indicating label of the present invention. FIG. 2 shows the coloring behavior of the temperature display labels obtained in Example 1 and Comparative Example 1. In FIG. 1, each symbol has the following meaning. 1, 2 and 3 ... Retaining layer of microcapsules containing methine dye precursors and hydrophobic organic compounds having different melting points, 4 ... Spacer layer, 5 ... Retaining layer of oxidizing material, 6 ... Support Body, 7 ... Adhesive layer, 8 ... Release paper

Claims (2)

[Claims] 1. A temperature control display unit comprising a hydrophobic organic compound having an arbitrary melting point, a methine dye precursor, and an oxidizing material, wherein the methine dye precursor is dissolved on the same support. A temperature-indicating label, characterized in that two or more kinds of hydrophobic organic compounds having an arbitrary melting point are separately held in microcapsules, and two or more control temperatures are indicated. 2. A temperature indicating label according to claim 1, wherein the methine dye precursor is adapted to a hydrophobic organic compound having an arbitrary melting point.