JPH1194653A - Temperature history indicator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the structure of an indicator make the indicator inexpensively manufacturable, to make it stably storable, and to make it surely storable a temperature history from a low temperature range to a high temperature range, by forming a dye permeable sheet out of a low density polyethylene or an intermediate density polyethylene film. SOLUTION: The dye permeable sheet 1 comprising a film of a super low density polyethylene or low density polyethylene, and a dye supporting sheet 3 having a dye containing sheet 2 on its surface are formed separately to be stored separately when not yet used. When both of them are laminated at the starting time of use to be laid together with a food of a temperature monitoring object, a dye is permeably diffused into the sheet 1 in response to its temperature history, and hue in response to the temperature history of a dye color is observed through the sheet 1. Since super low density polyethylene or low dencity polyethylene is opaque, the dye color is not observed in the initial stage of the lamination because of incomplete permeating diffusion of the dye, and the permeating diffusion of the dye progresses with the lapse of time to allow the dye color to be observed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature history indicator capable of expressing how long exposure to a certain temperature has been made by an irreversible color change, and is used for temperature control of low-temperature circulating foods and pharmaceuticals. Is what is done.

[0002]

2. Description of the Related Art Mismanagement of temperature during preservation or distribution of food leads to deterioration of quality, spoilage, and the risk of food poisoning. In particular, low-temperature food products are susceptible to the rise in temperature, and are often discarded due to the risk of fungal contamination due to failure in temperature control. Also, in the medical field, the role of low-temperature management of special drugs, blood, and specimens plays an extremely important role. Recently,
With the enforcement of the PL law, the importance of temperature control for quality assurance of these products is increasing.

There is a temperature history indicator for continuously monitoring the storage state of a low-temperature storage item. For example, Japanese Patent Publication No. 51-33432 discloses an enzyme and a pH indicator, and Japanese Patent Application Laid-Open Nos. 61-13116 and 62-197486 disclose a temperature history indicator using microcapsules. I have. However, when these are actually used for managing low-temperature storage items, there are problems in their production cost, stability, ease of use, accuracy, and the like.

Japanese Patent Application Laid-Open No. 60-151578 discloses a method utilizing the property of dye penetration (migration) into a urethane resin. Japanese Patent Application Laid-Open No. 8-101285 discloses that a dye permeates and diffuses into a vinyl chloride sheet. The indicator sheet used is described. These are relatively easy to produce, but have poor performance, especially poor migration of the dye into the resin at low temperatures, making them unsuitable for the management of cold storage. In the case of utilizing resin migration, in which a plasticizer is present in the resin, the plasticizer oozes out and there is a defect in the stability of the sheet when stored at room temperature.

[0005] Japanese Patent Application Laid-Open No. 7-20783 discloses the use of a polymer having a glass transition temperature of 0 ° C. or less in a coating film for forming a dye diffusion layer in utilizing the diffusion of a dye into a resin. Have been. However, in this method in which the diffusion layer is a coating film type, since the transparent substrate, the concealing layer, the dye diffusion layer, and the adhesive layer are complicated in structure, strict control of the coating thickness of the concealing layer and the dye diffusion layer is required. Otherwise, an accurate temperature history indicator cannot be obtained.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a simple structure, can be manufactured at low cost, can be stably stored at room temperature, and can be accurately displayed from a low temperature range to a high temperature range. It is an object of the present invention to provide an easy-to-use temperature history indicator that can be colored to leave a temperature history.

[0007]

Means for Solving the Problems The inventors of the present invention have developed a film of ultra-low-density polyethylene or low-density polyethylene (or a derivative thereof) having sufficient flexibility in a low-temperature region without mixing a plasticizer. The present inventors have found that the dye is brought into contact with the dye to cause the dye to permeate and diffuse, thereby completing the present invention.

That is, as shown in FIG. 1, a temperature history indicator of the present invention made to achieve the above object has a dye-penetrated sheet 1 and a dye-containing sheet for supplying a dye in contact with the dye-penetrated sheet 1. A temperature history indicator comprising a dye support sheet 3 having a layer 2 on the surface, wherein the dye-penetrated sheet 1 is formed of a film of low density polyethylene or medium density polyethylene.

In this temperature history indicator, the dye-permeable sheet 1 and the dye-containing layer 2 are separated from each other in the storage state (a), and the dye-permeable sheet 1 and the dye-containing layer 2 are joined when entering the use state (b). As a result, the dye in the dye-containing layer 2 penetrates and diffuses into the dye-permeable sheet 1, and the color of the dye becomes visible from above the dye-permeable sheet 1. In the conventional indicator sheet, the plasticizer contained in the resin of the dye permeation / diffusion layer bleeds out during storage at room temperature and was not stable. Since it is not mixed, it can be stored at room temperature without deterioration without bleeding.

The low-density polyethylene or medium-density polyethylene constituting the dye-penetrated sheet 1 has a density of 0.91 to 0.91.
Those in the range of 0.940 g / cm ³ are referred to. If the density is less than 0.91 g / cm ³ , it is difficult to form a film, and if it is more than 0.940 g / cm ³ , the dye has poor permeability, which is not preferable.

[0011] Similarly, the temperature history indicator of the present invention comprises:
As shown in FIG. 3, the dye-penetrated sheet 1 has a pressure-sensitive adhesive layer 4 on the surface in contact with the dye-containing layer 2. Therefore, when the pressure-sensitive adhesive layer 4 is brought into contact with the dye-containing layer 2 and attached to the dye-supporting sheet 3 when shifting from the storage state (a) to the use state (b) for temperature monitoring, the pressure-sensitive adhesive layer 4 becomes a medium. The dye penetrates and diffuses into the dye penetrating sheet 1 even in a low temperature range.

Similarly, the dye-containing layer 2 of the temperature history indicator of the present invention is formed by printing a printing ink containing a dye and a thermoplastic resin on a dye support sheet 3. In this way, since the dye is made into an ink and produced by printing, a uniform product can be obtained. Moreover, its manufacture is efficient and inexpensive.

Furthermore, the dye-containing layer 2 of the temperature history indicator of the present invention can be suitably implemented by preferably having a surfactant together with the dye. The surfactant promotes the diffusion of the dye at low temperatures. As the surfactant, an anionic surfactant, a cationic surfactant, a nonionic surfactant, an amphoteric surfactant, and a silicone-based surfactant can be used.
Those that can adjust the speed of penetration and diffusion into the water are selected.

[0014]

FIG. 1 shows an embodiment of a temperature history indicator to which the present invention is applied. The temperature history indicator of FIG. 1 includes a dye-penetrated sheet 1 made of ultra-low density polyethylene or low density polyethylene film,
A dye supporting sheet 3 having a dye-containing layer 2 on the surface. As shown in FIG. 1 (a), the dye-penetrated sheet 1 and the dye-supporting sheet 3 having the dye-containing layer 2 on the surface are formed separately, and stored separately when the temperature history indicator is not used. At the start of use, after bonding as shown in (b) and putting it together with food or the like which is the object of temperature monitoring, the dye penetrates and diffuses into the dye-penetrating sheet 1 according to the temperature history, and the dye color Can be observed from the dye-penetrated sheet 1 according to the temperature history. Since ultra-low density polyethylene or low density polyethylene is opaque, when the dye-penetrated sheet 1 is bonded to the dye-containing layer 2, the dye does not penetrate and diffuse sufficiently, so that the dye color cannot be seen. Penetration diffusion progresses, and the dye color becomes visible.

The dye-penetrated sheet 1 is not limited to a single layer of ultra-low density polyethylene or low density polyethylene film, but may have a multi-layered structure. Further, the transparency of the dye-permeable sheet 1 may be further reduced by mixing a filler or the like with the ultra-low density polyethylene or the low density polyethylene. Alternatively, the dye-penetrated sheet 1 may be a multilayer film, and some of the layers may be colored or colored films.

The temperature hysteresis indicator shown in FIG. 2 is constructed by laminating a dye penetrating sheet 1 and a dye supporting sheet 3 having a dye-containing layer 2 on its surface. FIG.
As shown in (a), by freezing until the start of use, the dye is prevented from penetrating and diffusing into the dye-penetrating sheet 1, and by coexisting with the object of temperature monitoring when starting use,
As shown in (b), the hue of the dye color appears on the dye-penetrated sheet 1 according to the temperature history.

Any dye can be used as long as it has permeability, and azo dyes and anthraquinone dyes are preferable because of their good permeability. As azo dyes, for example, CI2610
5, CI12055, CI11021, CI21260, CISolvent Re
d 83, CISolvent Red 83, CI26100, CI12770, C.
I. Disperse Blue 102. Examples of anthraquin-based dyes include CISolvent Red 146, CISolve
nt Blue 78, CISolvent Red 117, CISolvent Blue
36 and CI60755.

These dyes can be used alone or in combination. The concentration of the dye in the dye-containing layer may be any value as long as it can penetrate and diffuse into the dye-penetrating sheet 1, and the concentration is preferably 0.01 to 5%. If it is less than 0.01%, the hue due to permeation is thin, and if it exceeds 5%, the coloring is too conspicuous, resulting in erroneous determination and poor printability. Further, it is also possible to mix dyes having different permeation diffusion rates so that the hue changes over time.

In the temperature history indicator shown in FIG. 3, the dye-penetrated sheet 1 has an adhesive layer 4 on the surface in contact with the dye-containing layer 2, and the dye-containing layer 2 prints a printing ink containing a dye on the dye supporting sheet 3. It is composed. As shown in FIG. 3A, when the temperature history indicator is not used, it is stored as a separate body, and when it is started to be used, it is laminated as shown in FIG. 3B, and then coexists with the temperature monitoring target.

As the pressure-sensitive adhesive layer 4, any type of pressure-sensitive adhesive such as acrylic resin, rubber, and silicone can be used, and the presence of these pressure-sensitive adhesives does not affect the permeation and diffusion of the dye. .

To prepare a printing ink, a resin, a solvent and additives such as talc are mixed with the dye. Surfactants can be added in this inking step. The surfactant can adjust the affinity between the dye-penetrated sheet 1 and the printing ink. The amount of the surfactant is preferably less than 1.0% by weight of the ink. Have a bad effect. Printing methods include screen, flexo,
Various printing methods such as gravure can be used.

As the resin for forming the ink, natural resins, derivatives thereof, and synthetic resins used as vehicles for ordinary printing inks can be used. Examples of the natural resin and its derivatives include rosin, shellac, copearl, cured rosin, maleic acid resin, and fumaric acid resin. As the synthetic resin, for example, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, styrene-acrylonitrile resin,
Styrene resin, vinyl acetate resin, petroleum resin, butyral
Resin, acrylic resin, methacrylic acid resin, epoxy resin, polyurethane resin, polyamide resin, and polyvinyl alcohol resin. These resins may be used alone or in combination of two or more.

The dye support sheet 3 is a sheet on which the above-described printing ink is easily applied, and for example, a polyester film, polystyrene, or polycarbonate can be used.

The temperature history indicator shown in FIG. 4 has a pressure-sensitive adhesive layer 4 overlaid on a dye-penetrated sheet 1, and a dye-containing layer 2 is printed on a dye support sheet 3. The dye-penetrating sheet 1 and the dye-supporting sheet 3 are directly adhered to each other by the adhesive layer 4 at the end 6, but the separation sheet 5 is interposed in many parts where the dye-containing layer 2 exists. An adhesive layer 7 is provided on the lower surface of the dye support sheet 3 and is covered with a release paper 8. When the temperature history indicator is not used, it is stored in the state shown by the solid line in the drawing, so that the dye in the dye-containing layer 2 does not permeate and diffuse into the dye-penetrating sheet 1. When starting to use, as shown by an arrow line, the separation sheet 5 is first separated from the dye support sheet 3 (see a chain line), and then peeled off from the pressure-sensitive adhesive layer 4 of the dye-penetrated sheet 1 and removed. Next, the pressure-sensitive adhesive layer 4 of the dye-penetrated sheet 1 is superposed on the dye-supporting sheet 3 and pressed down, so that the dye-containing layer 2 adheres to the dye-penetrated sheet 1 via the pressure-sensitive adhesive layer 4.
Further, when the release paper 8 is peeled off and affixed onto a package of food or the like whose temperature is to be monitored with the adhesive layer 7, the dye in the dye-containing layer 2 permeates and diffuses into the dye-penetrating sheet 1 according to the temperature change. Then, the hue of the dye can be observed from the dye-penetrated sheet 1.

The temperature history indicator can be implemented in a label shape or a tape shape.

[0026]

Embodiments of the present invention will be described below in detail.

Example 1 900 parts by weight of an ink vehicle (NSP medium, manufactured by Jujo Kako Co., Ltd.), 12 parts by weight of a dye (CI. 26125), 90 parts by weight of a solvent (cyclohexanone), 12 parts by weight of an additive (talc) Was kneaded to produce a permeable printing ink. This printing ink was screen-printed on a polyester film by a 150-mesh silk screen to form a dye-containing layer 2 on a dye support sheet 3 shown in FIG. On the other hand, a low-density polyethylene film having a three-layer structure (white: film thickness 20 μm / white: film thickness 20)
μm / gray: film thickness 20 μm) and adhesive (Y-9460P)
C, 3M) to form an adhesive layer 4 on the dye-penetrated sheet 1 to obtain a temperature history indicator. As shown in (b) of this temperature history indicator, the dye-containing layer 2 and the pressure-sensitive adhesive layer 4 were overlapped, and the dye-supporting sheet 3 and the dye-penetrating sheet 1 were bonded together. By measuring the discoloration state of the surface of the dye-penetrated sheet 1 at each temperature, the relationship between the dye penetration amount and time was examined. Use a color difference meter (cr-321 manufactured by Minolta Co., Ltd.) to change the color difference (△ E
When a.b.) was measured, as shown in Table 1, a color difference ΔE according to the temperature was shown from a low temperature range to a high temperature range. Further, although the temperature once increased was lowered, the color did not change, indicating that the color change of this temperature history indicator was irreversible and stable.

[0028]

[Table 1]

Examples 2 to 7 In order to confirm the effect of promoting the penetration and diffusion of a dye when a surfactant is mixed in the dye-containing layer 2, the composition of Example 1 was added to an anionic interface manufactured by NOF Corporation. Activator Trax K-
0.8% of 40 (Example 2), 0.8% of a cationic surfactant New-Elegant ASK manufactured by NOF Corporation (Example 3),
Nonionic surfactant nonion DS-60HN manufactured by NOF Corporation
0.5% (Example 4), 0.5% (Nissan Anone BF, an amphoteric surfactant manufactured by NOF CORPORATION) (Example 5), and 0.1% of a nonionic surfactant Amyt 105 from Kao Corporation. 5% (Example 6), silicone surfactant L- manufactured by Unitika Japan Co., Ltd.
7604 was added to each of 0.5% (Example 7) to produce a printing ink. A temperature history indicator was prepared in the same manner as in Example 1 using these printing inks. For these temperature history indicators, the color difference ΔE at 10 ° C. was measured in the same manner as in Example 1, and the results are shown in Table 2.

[0030]

[Table 2]

As is clear from Table 2, the temperature history indicators of Examples 2 to 7 in which the surfactant was mixed into the dye-containing layer 2 were more than the temperature history indicators of Example 1 in which no surfactant was mixed. The color difference ΔE is large, and it can be seen that the penetration of the dye is promoted by mixing the surfactant.

[0032]

As described above in detail, the temperature history indicator to which the present invention is applied is capable of producing an irreversible color change with a high resolution corresponding to the temperature-elapsed period during the low temperature distribution and storage of foods and pharmaceuticals. As a result, the temperature history can be monitored. By adding a surfactant to the dye, the function of the dye permeating and diffusing into the dye-penetrating sheet at a low temperature is enhanced, and the storage stability at room temperature is excellent by not using a plasticizer. In addition, since the temperature history indicator of the present invention is manufactured by printing a dye using ink, a homogeneous product can be efficiently and inexpensively mass-produced.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of a temperature history indicator to which the present invention is applied.

FIG. 2 is a cross-sectional view of another embodiment of a temperature history indicator to which the present invention is applied.

FIG. 3 is a sectional view of still another embodiment of a temperature history indicator to which the present invention is applied.

FIG. 4 is a sectional view of still another embodiment of a temperature history indicator to which the present invention is applied.

[Explanation of symbols]

1 is a dye penetrating sheet, 2 is a dye-containing layer, 3 is a dye support sheet, 4 is an adhesive layer, 5 is a separation sheet, 6 is an end, 7 is an adhesive layer, and 8 is a release paper.

[Procedure amendment]

[Submission date] October 8, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

[0007]

The inventor of SUMMARY OF THE INVENTION The present invention provides low-density polyethylene without mixing a plasticizer with sufficient flexibility in a low temperature range or medium density polyethylene emission film, is brought into contact with the dye The present inventors have found that dyes can permeate and diffuse, and have completed the present invention.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

[0014]

FIG. 1 shows an embodiment of a temperature history indicator to which the present invention is applied. The temperature history indicator of FIG. 1 includes a dye-permeable sheet 1 made of a low-density polyethylene or a medium-density polyethylene film, and a dye support sheet 3 having a dye-containing layer 2 on the surface. As shown in FIG. 1 (a), the dye-penetrated sheet 1 and the dye-supporting sheet 3 having the dye-containing layer 2 on the surface are formed separately, and stored separately when the temperature history indicator is not used. At the start of use, after bonding as shown in (b) and putting it together with food or the like which is the object of temperature monitoring, the dye penetrates and diffuses into the dye-penetrating sheet 1 according to the temperature history, and the dye color Can be observed from the dye-penetrated sheet 1 according to the temperature history. Because low-density polyethylene or medium-dense <br/> polyethylenes are opaque, dye penetration sheet 1
At the beginning, when the dye is adhered to the dye-containing layer 2, the dye does not penetrate and diffuse sufficiently, so that the dye color cannot be seen. However, as the time elapses, the dye penetrates and diffuses, and the dye color becomes visible.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

The dye-penetrated sheet 1 is not limited to a single layer of a low- density polyethylene or a medium- density polyethylene film, but may have a multilayer structure in which the films are superposed. Further, the transparency of the dye-permeable sheet 1 may be further reduced by mixing a filler or the like with the low- density polyethylene or the medium- density polyethylene. Alternatively, the dye-penetrated sheet 1 may be a multilayer film, and some of the layers may be colored or colored films.

Claims (4)

[Claims] 1. A temperature history indicator comprising a dye-penetrated sheet and a dye-supporting sheet having on its surface a dye-containing layer for supplying a dye in contact with the dye-penetrated sheet, wherein the dye-penetrated sheet comprises low-density polyethylene or A temperature history indicator comprising a medium density polyethylene film. 2. The temperature history indicator according to claim 1, wherein the dye-permeable sheet has a pressure-sensitive adhesive layer on a surface in contact with the dye-containing layer. 3. The temperature history indicator according to claim 1, wherein the dye-containing layer is formed by printing a printing ink containing the dye and a thermoplastic resin on the dye support sheet. 4. The temperature history indicator according to claim 1, wherein the dye-containing layer has a surfactant together with a dye.