JP2003214961A - Heat history discrimination method using heat sensitive ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow a plurality of heat history discrimination marks covering the same history and using the same ink to decolorize at different time points in a heat history discrimination method using heat sensitive ink. <P>SOLUTION: The viscosity of heat sensitive ink, which ultimately decolorizes with the passage of time under heated conditions, is adjusted when it is used for printing though its solid content remains unchanged. As the result, heat history discrimination marks A, B, C are different from each other in film thickness as printed on the external surface of a container, and the marks A, B, C are also different from each other in decolorization time point even when they cover the same heat history. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to filling of containers such as cans, PET bottles, paper packs, etc. with contents such as beverages and foods.
For the sealed product, in order to control the quality of the contents of the product that are stored in a heated state, a heat history identification mark is printed on the outer surface of the container at a suitable place at the time of manufacturing the container with a temperature indicating ink. Discoloration (erasing) of heat history identification mark
More specifically, the present invention relates to a heat history identification method using temperature-sensitive ink for identifying a heat history after manufacturing a product.

[0002]

2. Description of the Related Art For beverage products such as cans and PET bottles, put them in a hot vendor of a vending machine or in a heating greenhouse of a convenience store so that the products can reach the consumers in a warm state. It has been common practice to sell the product from the past, but when selling while storing the product in such a heated state, the storage period in the heated state after the product is manufactured is When it becomes longer, even if there is no change in appearance, the contents are altered by a long-term heat history (temperature × time), which not only gives the consumer a bad impression that the taste is not good, but it is also remarkable. In some cases, it may be subject to complaints from consumers as a quality abnormality.

On the other hand, a temperature history ink that gradually changes color over time in a heated state is used, and a mark (symbol, By printing (graphics, characters, etc.), by observing the degree of discoloration of the heat history identification mark for each product stored in a heated state, and identifying the heat history after manufacturing, It has been conventionally considered that the degree of alteration of the contents can be easily determined, and thereby the quality of the contents of the product is managed in a non-destructive state of the container (for example, Japanese Patent Laid-Open No. H11 (1999) -111945). -189741, JP-A-11-296086, JP-A-2000-
309733, JP 2000-9550 A, etc.).

[0004]

By the way, regarding the products sold while being stored in a heated state by the vending machine or the warming room as described above, usually, a plurality of products having different kinds of contents are the same automatic product. Although sold in the state of being housed in a vending machine or warming greenhouse, the heat history until the contents of the plurality of products are deteriorated by heat due to the difference in the type of contents (until the time of disposal) May be different.
Therefore, even if the products are stored in the same place, the extent to which the heat history is received before the product is disposed of may be different depending on the type of contents.

That is, for example, 55 for canned beverages.
As a result of investigating the alteration rate of the contents when stored in a temperature-controlled room at ℃, unsweetened black coffee felt a heating odor in 2 weeks, and a heating odor became large in 4 to 5 weeks, and the sourness became strong. Becomes unsuitable. Milk coffee has a heating odor and a sour taste in about 4 weeks, and becomes unsuitable for drinking after 7 to 8 weeks. Also, with green tea and oolong tea, astringency increases in 2 to 4 weeks and becomes unsuitable for drinking after 8 weeks. In black tea with milk, separation of milk content is observed in 2 to 4 weeks, and it becomes unsuitable for drinking after 8 weeks. With hot lemon, a strange and offensive odor is felt in 1 to 2 weeks, and it becomes unsuitable for drinking after 4 weeks.

Therefore, when the quality of each product having different contents stored in the same place is controlled, if the same heat history identifying mark is attached by the same temperature indicating ink, the contents of each product It is necessary to judge the time of disposal due to deterioration due to deterioration by the difference in the degree of discoloration of the heat history identification mark attached to each product. It is practically difficult to accurately judge the time when each product is scrapped by distinguishing the difference in the degree of discoloration of the identification mark.

On the other hand, when the heat history identification mark is applied to a plurality of products having different contents, the contents are deteriorated and deteriorated in accordance with the deterioration speed of each contents due to heat ( By using a temperature-sensitive ink that completely erases color with a heat history only up to the time of disposal), it is possible to visually confirm that the heat history identification mark attached to each product is erased. It is conceivable that anyone can easily determine the time to dispose of products with different contents at the point of sale.

With respect to the above point, the use of temperature indicating ink having a large color difference (erasing color) so that the heat history can be easily identified by the heat history identifying mark is described in, for example, JP-A-11-296086. In addition, the type of temperature indicating ink used for the heat history identification mark (ink) is described in the publication and also according to various storage conditions (for example, a storage period in which the contents of the product deteriorate and deteriorate in a heated state). Changing the solid component) of JP-A-11-18974.
No. 1 publication.

However, when the type of temperature indicating ink (solid component of ink) is changed according to the type of product contents (difference in deterioration rate due to heat history) as described above, the content of the target product is changed. Each time the type changes, the ink stored in the tank of the printing device (inkjet printer, etc.) must be replaced, and the work is troublesome, and there are many types depending on the type of contents of the product. Since it is necessary to prepare the temperature indicating ink in advance, there is a problem that the production cost increases.

[0010] On the other hand, when considering each of the products stored in a heated state, in particular, due to a relatively long-term heat history of green tea or oolong tea, the flavor gradually decreases and becomes unsuitable for drinking. For proper contents, in order to properly manage the quality condition of the contents during the sales period, it is possible to always grasp the heat history at the intermediate point until the contents are completely deteriorated and abandoned. It is preferable to keep
In order to identify the heat history at such an intermediate point, for the heat history identification mark that is gradually discolored, use a colorimetric card for identification or a color difference meter to determine the difference in discoloration. There is a problem that it is necessary to make a detailed inspection, and it is difficult to make a judgment simply by visual inspection.

The present invention is intended to solve the above problems. Specifically, in a heat history identification method using temperature indicating ink, a plurality of heat history identifying marks using one type of temperature indicating ink are used. The challenge is to make the time of bleaching different even with the same heat history.

By doing so, with respect to a plurality of products having different kinds of contents, the time of disposal of each product due to deterioration and deterioration of the contents can be determined without using various kinds of temperature indicating ink. It is possible to easily judge by erasing the identification mark, and for each product, the thermal history at the intermediate point until the contents completely deteriorate and deteriorate, It is possible to easily judge by erasing any of the plurality of heat history identification marks of the product without using a card or a color difference meter.

[0013]

According to the present invention, in order to solve the above-mentioned problems, as described in the above-mentioned claim 1, after the manufacture of the product in which the contents are filled and sealed in the container. In the method of identifying the heat history of the heat history identification mark printed with the temperature indicating ink on the outer surface of the container at a proper place, the temperature indicating ink is finally decolorized with the passage of time in the heated state, and the solid component is By using the same temperature-sensing ink to adjust the ink viscosity when printing this temperature-sensing ink, changing the ink film thickness of the heat-history identification mark printed on the outer surface of the container allows multiple heat-history identification marks. With respect to the above, regarding the same heat history, the time of decoloring is made to be different.

According to the method as described above, various kinds of temperature indicating ink are used by changing the ink film thickness (dry film thickness of the coating film) of each of the plurality of heat history identifying marks. Without using only one type of temperature indicating ink (temperature indicating ink having the same solid component), even when the heat history is the same, the color erasing timing of each heat history identifying mark can be changed.

By implementing the above method as described in claim 3 above, even if the deterioration rate due to the heat history of the contents is different for a plurality of products having different kinds of contents. , It is possible to easily determine the time to dispose of each product due to deterioration and deterioration of the contents, and by implementing as described in claim 4 above,
For each individual product, it is possible to easily determine the heat history at an intermediate point until the contents are altered and completely deteriorated without using a colorimetric card for identification or a color difference meter. it can.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a heat history identifying method using temperature-sensitive ink of the present invention will be described in detail below with reference to the drawings. Regarding the method of the present invention, FIG.
An example of a method for adjusting the ink viscosity at the time of printing is shown by a flowchart, and FIG. 2 shows a plurality of (three) thermal history identifying marks printed with one type of temperature indicating ink and having different ink film thicknesses. FIG. 4 is a graph showing changes in ink color tones with the lapse of days.

Regarding the temperature-sensitive ink used in the method of the present invention, as a solid component, an acid-base discoloring dye which is a coloring component, a substance such as an organic acid which induces a pH change, and a resin which serves as a binder. Which has a component and other suitable components (conductivity-imparting substances, etc.) and is diluted to a desired ink viscosity (ink concentration) by a solvent, and has a film thickness of a printed ink coating film. A leveling agent is added to the ink so as to be uniform throughout.

The acid-base discoloring dyes include thymol blue, methyl yellow, methyl orange, methyl red,
Phenol Red, Cresol Red, Phenolphthalein, Alizarin Yellow, Bromophenol Red,
Dyes such as chlorophenol red, xylinol orange, and phenolsulfophthalein are used.

Examples of substances that induce pH changes include organic acids such as salicylic acid, citric acid, malic acid, levulinic acid, maleic acid and phthalic acid, and ethylamine, diethylamine, triethylamine, butylamine, tributylamine, hexanediamine, hexylamine. , Amines such as benzylamine and methylamine, or basic substances such as ammonia, sodium hydroxide and sodium benzoate.

As the resin component serving as a binder, phenol resin, butyral resin, epoxy resin, polyamide resin, rosin-modified maleic acid resin, acrylic resin, etc. are used, and the solvent is methyl ethyl ketone, ethanol, methyl isobutyl ketone, methanol, isopropanol. , Cyclohexanone, etc. are used.

Silicon is used as the leveling agent. The amount of this leveling agent added is 3 to 6
% (Content in the ink diluted with the solvent) is preferable, and when the leveling agent is added in an unnecessarily large amount,
When the shape of the ink coating film becomes thick in the central part like a mountain, and vice versa, when it is too small, the shape of the ink coating film becomes thin in the central part like a crater, and in any case, it is uniform throughout. Ink coating film having a film thickness cannot be obtained.

In order to make the film thickness of the ink coating film when the temperature-sensitive ink is printed, it is preferable to use an appropriate amount of the leveling agent as described above. When the thermal history identification mark is printed with the temperature-sensitive ink. If the film thickness of the ink coating film is not uniform, discoloration unevenness easily occurs when heated, and it becomes difficult to accurately identify the heat history by the color change of the heat history identification mark.

Explaining the principle of discoloration in the temperature-sensitive ink having the above components, the solvent evaporates from the printed temperature-sensitive ink to cause an ink coating film of a predetermined color by the acid-base color-changing dye (depending on the solid component). When an ink coating film is formed and the ink coating film is heated, substances such as organic acids are decomposed and the pH of the ink coating film is changed, so that the structure of the acid-base discolorable dye is changed. The color gradually diminishes, and further heating causes the dye to sublimate and decompose, eventually becoming colorless (resin color).

By the way, the discoloration speed of the temperature-sensitive ink, which is finally erased by the heat history according to the principle of discoloration as described above, is closely related to the dry film thickness of the ink coating film printed and applied on the outer surface of the container. Therefore, there is a property that when the film thickness is thin, the color change speed becomes fast, and when the film thickness is thick, the color change speed becomes slow. The method of the present invention utilizes this property, and for a plurality of thermal history identification marks by one type of temperature indicating ink (temperature indicating ink having the same solid component), its color change speed can be determined, for example, from the content of the product. It can be adjusted according to the difference in type (difference in deterioration rate due to heat history), or for each of a plurality of heat history identification marks given to the same product, and can be appropriately adjusted.

That is, when the heat history identification mark using the temperature indicating ink is given to each product having a different type of contents, conventionally, the ink target is set according to the deterioration rate of the contents due to the heat history. Set the color change speed,
By making the solid component of the temperature indicating ink an ink compounding composition suitable for the solid component, the discoloration speed is made different according to the difference in the deterioration speed of the contents. In addition, when judging the degree of deterioration of the contents of each product due to the heat history, conventionally, the color history of the heat history is gradually changed by using a colorimetric card for identification or a color difference meter. The degree of discoloration of the identification mark is inspected.

On the other hand, in the method of the present invention, in the first embodiment, the temperature indicating ink that is finally erased with the passage of time in the heated state is used, and the kind of the contents is different. When printing the heat history identification mark on the outer surface of the container with temperature-sensitive ink that has the same solid content for each of multiple products, depending on the difference in the rate of deterioration of the contents due to heat, By adjusting the ink viscosity of the product, the ink film thickness of the heat history identification mark printed on the outer surface of the container of each product can be changed to prevent deterioration and deterioration of the contents of multiple products with different types of contents. The presence or absence (that is, the time when the contents are abandoned due to deterioration and deterioration) is determined by erasing the heat history identification mark of each product.

In addition, in the second embodiment, a temperature history ink that is finally erased with the passage of time in a heated state is used, and a heat history identification mark is provided for each product. When printing in place on the outer surface, by using the temperature indicating ink with the same solid component, by providing a plurality of thermal history identification marks with different ink film thickness for each product,
For each product, the heat history at an intermediate point until the contents are altered and completely deteriorated (until the time of disposal),
The determination is made by erasing any of the plurality of heat history identification marks of the product.

In each of the embodiments of the method of the present invention as described above, as for the method of adjusting the ink viscosity at the time of printing, the ink viscosity control device (equipped in a printer such as an inkjet printer) connected to a computer is used. ) Using a computer (PC etc.) in advance
Based on the set value of the ink viscosity input to and the actual measurement data obtained by measuring the temperature indicating ink stored in the tank in the printer, by controlling the supply amount of the solvent supplied to the temperature indicating ink by the ink viscosity control device, The ratio of the solid component of the temperature indicating ink and the solvent is adjusted so that the temperature indicating ink ejected from the nozzle of the printer during printing has a target ink viscosity (ink viscosity within a predetermined range from the target value).

At that time, for one computer,
The ink viscosity control device installed in each of one or more printers will be connected, but multiple ink viscosity control devices (printers that incorporate the device) are connected to one computer. In this case, the viscosity setting value is input to each ink viscosity control device individually for each ink viscosity control device in one computer.

When printing one thermal history identifying mark for one product (even if there are a plurality of characters or figures to be printed, all of them have the same ink film thickness), However, even with one printer, it is possible to print thermal history identification marks with different ink film thicknesses on multiple products with different types of contents by changing the ink viscosity depending on the product. It is possible to use multiple printers according to the number of printers), and when printing multiple thermal history identification marks with different ink film thickness on one product at the same time, multiple thermal history identifications It is necessary to have multiple printers corresponding to the service mark.

A method for adjusting the ink viscosity during printing by each printer (one or a plurality of printers) is generally as shown in FIG. Specifically, first, a preset value of the ink viscosity (which can be freely set within the range of 1 to 200) is input in advance in the computer. That is, in the above-described first embodiment, the viscosity setting values are input for a plurality of products having different types of contents. Further, in the above-described second embodiment, a plurality of viscosity setting values are input for each individual product. In addition to the above, the computer is set with environmental data and the measurement interval when measuring the nozzle temperature, the viscometer temperature, the ink viscosity (converted into the actually measured viscosity count value), and the like.

In a printer equipped with an ink viscosity control device connected to a computer, temperature indicating ink having a basic ink viscosity (concentration) is stored in an ink tank, and this temperature indicating ink is transferred from the ink tank to the main tank. While being sent, a replenisher tank (a tank that stores a solvent as a replenisher) or a conditioning tank (when cleaning the nozzle at startup or shutdown,
The solvent stored in the solvent that is supplied from the replenisher tank to the nozzle and that is collected is sent to the main tank under the control of the ink viscosity control device, and The ink viscosity (concentration) is diluted to a substantially target value (within a predetermined range from the target value), and the temperature indicating ink in the main tank is ejected from the nozzle during printing.

That is, a viscometer is installed in the main tank of the printer, and in the ink viscosity control device built into the printer, the nozzle temperature and the viscometer temperature (ink Temperature), measured viscosity count value (value converted from the value measured by the viscometer), etc., and the measured data (viscometer temperature and measured viscosity count value) and the viscosity setting value input to the computer in advance. Based on this, a target value of ink viscosity (target viscosity count value) is calculated, and the solvent supply amount is calculated from the target value of ink viscosity (target viscosity count value) and the measured value (measured viscosity count value), Control the amount of solvent supplied from the conditioning tank or replenisher tank to the main tank so that the calculated solvent supply amount is obtained. There.

As a result, the ratio of the solid component of the temperature indicating ink and the solvent is adjusted in the main tank, and the measured value of the ink viscosity (measured viscosity count value) is substantially equal to the target value (target viscosity count value) (target value). From within the predetermined range), it is determined that printing can be started, and the temperature indicating ink from the main tank is ejected from the nozzle to print the thermal history identification mark. ing.

As to one embodiment (first embodiment) of such a heat history identification method using temperature-sensitive ink of the present invention, a concrete example of a canned product will be described below. In addition,
It goes without saying that the method of the present invention is not limited to canning as shown in the following examples, but can be applied to a product containing a container using other containers such as a PET bottle and a paper pack.

[0036]

Examples [Components of temperature-sensitive ink] -Methyl yellow (0.7% by weight with respect to resin) as an acid-base discoloring dye-Zinc salicylate (15% by weight with respect to resin) as a substance that induces pH change Sodium benzoate (15% by weight with respect to resin) -Ammonium thiocyanate as a conductivity imparting agent (2% by weight with respect to resin) -Methyl ethyl ketone and ethanol as a solvent-Binder resin, phenol resin-Silicone as a leveling agent Add 5% to ink (including solvent)

Regarding the temperature indicating ink having the above components,
The ratio of solvent (solvent in which methyl ethyl ketone and ethanol were mixed at a ratio of 85:15) to the resin was 20:80.
The basic ink viscosity (concentration) is the same as above, and the retort sterilization is performed after the filling and winding process using a charge type inkjet printer (equipped with Keyence MK-8500 / automatic viscosity control system) connected to a computer. For canned foods that have not yet been processed and shipped as products, adjust the ink viscosity of the temperature-sensitive ink according to the rate of deterioration due to the heat history of the contents, and then discharge the temperature-sensitive ink from the printer nozzle. Then, a heat history identification mark is printed on the outer surface of the can (below the manufacturing date on the bottom of the can) (logo mark, manufacturing time, symbol, figure, etc. printed in dots).
is doing.

When printing the temperature-sensitive ink on the outer surface of the can, if the surface temperature of the can is between 25 ° C. and 40 ° C., the difference in film thickness (dot film thickness) of the printed ink coating film is Although it is minute and has little effect on temperature, when the surface temperature of the can is high, such as immediately after retort sterilization, or when the surface temperature of the can is particularly low in cold regions, the film of the printed ink coating film The thickness is affected by temperature, so in order to stabilize the film thickness of the printed ink coating, the surface temperature of the can is set to 2
It is necessary to prepare the environment so that the temperature is between 5 ° C and 40 ° C. In this embodiment, printing is performed with the surface temperature of the can set at 30 ° C.

Regarding the adjustment of the ink viscosity (concentration) of the temperature-sensitive ink corresponding to the contents, a computer connected to the ink viscosity control device (automatic viscosity control system) equipped in the printer is used to make a plurality of different contents. For each product, the ink viscosity setting value (1-
It can be set freely within the range of 200) in advance, and based on the data (viscosimeter temperature and measured viscosity count value) measured in the printer and the viscosity setting value previously input to the computer in the ink viscosity control device. To calculate the target value of ink viscosity (target viscosity count value),
The amount of solvent supplied is calculated from the target value of ink viscosity (target viscosity count value) and the measured value (measured viscosity count value), and the basic amount stored in the ink tank is set so as to be the calculated amount of solvent supply. By controlling the supply amount of the solvent to be supplied from the main tank to the temperature indicating ink of viscosity (the ratio of the solvent to the resin is 20:80),
By adjusting the ratio of the solid component (component that forms the coating film) and the solvent (component that volatilizes) in the temperature-sensitive ink in the main tank,
The temperature-sensitive ink ejected from the nozzle has a target ink viscosity according to the type of canned contents.

Specifically, in this embodiment, the heat history identification mark is maintained at 55 ° C. in response to canned foods in which the quality of the contents deteriorates in 2 weeks at 55 ° C. The setting value of the ink viscosity was set to 25 so that the color changed from red to colorless in 2 weeks. The target viscosity count value calculated based on this set value was 667, and the measured viscosity count value of the temperature indicating ink after the solvent was supplied was 674 based on this target viscosity count value. The viscosity thermometer was 35.0 ° C, and the value measured by the rotary vibration viscometer was 2.13 mPa · S / 25 ° C. In the heat history identification mark (A) printed under such conditions, the film thickness (dry film thickness) of the ink coating film was 2.3 to 2.7 μm (measured with a laser focus displacement meter).

In addition, the ink viscosity (concentration) of the temperature-sensitive ink is increased in response to canning in which the quality of the contents deteriorates in 4 weeks under heating at 55 ° C., and heat is applied under heating at 55 ° C. The ink viscosity set value was set to 100 so that the history identification mark changed from red to colorless in 4 weeks. The target viscosity count value calculated based on this setting was 745, and the actually measured viscosity count value of the temperature indicating ink after the solvent was supplied based on this target viscosity count value was 751. The viscosity thermometer was 35.9 ° C, and the value measured by the rotary vibration viscometer was 2.71 mPa · S / 25 ° C. In the heat history identification mark (B) printed under such conditions, the ink coating film thickness (dry film thickness) is 2.8 to
It was 3.6 μm (measured with a laser focus displacement meter).

Furthermore, the ink viscosity (concentration) of the temperature-sensitive ink is increased to cope with canning in which the quality of the contents deteriorates in 8 weeks under heating at 55 ° C., and heat is applied under heating at 55 ° C. The ink viscosity setting value was set to 150 so that the history identification mark changed from red to colorless in 8 weeks. The target viscosity count value calculated based on this setting was 793, and the measured viscosity count value of the temperature indicating ink after the solvent was supplied based on this target viscosity count value was 794. The viscosity thermometer was 35.7 ° C, and the value measured by the rotary vibration viscometer was 2.88 mPa · S / 25 ° C. In the heat history identification mark (C) printed under such conditions, the film thickness (dry film thickness) of the ink coating film is 5.5.
.About.6.2 μm (measured with a laser focus displacement meter).

As described above, the heat history identification marks (A), (B), and (C) in which the film thickness (dry film thickness) of the ink coating film differs depending on the contents, in a thermostatic chamber at 55 ° C. As a result of observing the change in ink color tone of each heat history identification mark (A), (B), (C), as shown in FIG. The heat history identification mark (B) for 4 weeks corresponds to the erasing level after 4 weeks, and the heat history identification mark (C) corresponding to 8 weeks corresponds to the erasing level after 8 weeks. It was confirmed that In addition, the color tone (a value) is measured by an average value measured at three points with a minute area color difference meter manufactured by Nippon Denshoku.

According to the first embodiment of the method of the present invention as specifically described in the above example, one type of temperature indicating ink (temperature indicating ink having the same solid component) is provided for each product having different contents. ) To print the heat history identification mark, the ink film thickness (dry film thickness) of each heat history identification mark can be adjusted according to the difference in deterioration rate due to the heat history of each content. By changing the heat history, even when the heat history is the same, the time when the heat history identification mark is decolored varies depending on the product. Therefore, even if the deterioration rate of each product due to the heat history is different, visually observing the decoloration of the heat history identification mark makes it easier to dispose of each product due to the deterioration of the contents. Can be judged.

In the method of this embodiment, an ink viscosity control device (equipped in each printer) connected to a computer is used to supply the temperature-sensitive ink sent from the ink tank to the main tank in the printer. By adjusting the supply amount of the solvent, the ratio of the solid component of the temperature-sensitive ink and the solvent is adjusted so that the temperature-sensitive ink ejected from the printer nozzle during printing is approximately the target ink viscosity (within the specified range from the target value). Therefore, the adjustment work of the ink viscosity according to the kind of the contents can be easily and surely performed only by the computer operation.

By the way, the second embodiment of the method of the present invention will be further described with respect to the first embodiment of the method of the present invention as described above. In the first embodiment, each product is While one kind of heat history identification mark is provided (even if there are a plurality of prints, all of them have the same ink film thickness and are erased at the same time), in the second embodiment, By adding various types of heat history identification marks (a plurality of marks that are erased at different times) with different ink film thickness to each product, it is possible to manage the sales status of each product in detail. There is.

That is, in the first embodiment, two weeks are set so that the disposal time can be easily visually determined for each of the three types of products (canned products) having different deterioration rates due to the heat history of the contents. Corresponding heat history identification mark (A) and heat history identification mark (B) corresponding to 4 weeks,
Either the heat history identification mark (C) corresponding to 8 weeks is applied, and the color erasing time of the heat history identification mark applied to each product is determined as the disposal time of the product. However, for example, when it has a heat history of 8 weeks or more, such as green tea, it becomes unsuitable for drinking, but in the case of contents whose flavor gradually decreases, until it becomes completely unsuitable for drinking. It is preferable for quality control to always identify the thermal history at the midpoint of the period.

In consideration of such a case, in the second embodiment of the method of the present invention, for each product, for example, a heat history identification mark (A) corresponding to 2 weeks and 4 weeks. A plurality of heat history identification marks having different ink film thicknesses, such as a corresponding heat history identification mark (B) and a heat history identification mark (C) corresponding to 8 weeks, are provided respectively. The identification mark is designed to be gradually erased, so that at an intermediate point until it becomes completely unsuitable for drinking,
It is possible to easily determine the progress of the heat history up to that point simply by visually observing which mark disappears and which mark remains without using a colorimetric card for identification or a color difference meter.

Although the respective embodiments of the thermal history identifying method using the temperature-sensitive ink of the present invention have been described above, the present invention is not limited to the specific methods as shown in the above-mentioned respective embodiments. As for the method of adjusting the ink viscosity of the temperature indicating ink, an appropriate method is possible, and for each of the products having different types of contents, a plurality of thermal history identifying inks having different ink film thicknesses are provided for each product. Needless to say, a mark may be provided, and further, a heat history identification mark may be provided in advance on the outer surface of the container before filling the contents, and the like.

[0050]

According to the heat history identification method using the temperature indicating ink of the present invention as described above, the same heat history can be obtained by using only one kind of temperature indicating ink without preparing many kinds of temperature indicating ink. Even if there is, it is possible to provide a plurality of heat history identification marks with different erasing times. As a result, for multiple products with different types of contents, the time at which each product was abandoned due to deterioration of the contents was used to identify the heat history that was given to each product without using multiple types of temperature indicating ink. You can easily judge by erasing the mark,
Alternatively, for one product, the heat history at an intermediate point until the contents completely deteriorate and deteriorate is obtained by adding multiple heat history to the product without using a colorimetric card for identification or a color difference meter. It can be easily judged by erasing any of the identification marks.

[Brief description of drawings]

FIG. 1 is a flowchart schematically showing an example of a method for adjusting the ink viscosity during printing in the heat history identification method using temperature-sensitive ink of the present invention.

FIG. 2 is a graph showing a change in each ink color tone with the passage of days for a plurality of (three) thermal history identification marks printed with one type of temperature indicating ink and having different ink film thicknesses.

[Explanation of symbols]

A Heat history identification mark for 2 weeks B 4 weeks compatible heat history identification mark C Heat history identification mark for 8 weeks

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2F056 VA01 VA02 VA10                 3E062 AA01 AA04 AA09 AB02 AC02                       AC03 AC05 BA20 BB06 BB10                       DA02 DA08                 4J039 AB08 AD07 AD09 AE02 AE05                       AE08 BE01 BE02 BE12 BE23                       BE30 GA01 GA02 GA03 GA04                       GA24

Claims (4)

[Claims] 1. A method for identifying a heat history of a product in which contents are filled / sealed in a container by a heat history identification mark printed with temperature indicating ink at an appropriate place on the outer surface of the container in a heated state. It is a temperature-sensitive ink that finally fades over time, using the temperature-sensitive ink with the same solid components,
By adjusting the ink viscosity during printing of this temperature indicating ink, the ink film thickness of the thermal history identification mark printed on the outer surface of the container can be changed, so that multiple thermal history identification marks can be erased even with the same thermal history. A method for identifying heat history using temperature-sensitive ink, characterized in that the timings at which the heat is applied are different. 2. The temperature indicating ink is controlled by controlling the supply amount of the solvent supplied to the temperature indicating ink based on the viscosity setting value preset according to the target ink viscosity and the actual measurement data obtained by measuring the temperature indicating ink. The heat generated by the temperature-sensitive ink according to claim 1, wherein the ratio of the solid component of the ink to the solvent is adjusted so that the temperature-sensitive ink ejected from the nozzle of the printer during printing has a target ink viscosity. History identification method. 3. When a thermal history identifying mark is printed on a plurality of products having different kinds of contents by using the temperature indicating ink having the same solid component, the rate of deterioration of the contents by heat is determined. Depending on the difference, by changing the ink film thickness of the heat history identification mark printed on the outer surface of the container of each product, the presence or absence of deterioration of the contents of multiple products with different types of contents can be checked. The heat history identification method using the temperature indicating ink according to claim 1 or 2, wherein the determination is made by erasing the heat history identification mark. 4. The content of each product is obtained by using a temperature indicating ink having the same solid component for each product and providing a plurality of heat history identification marks having different ink film thicknesses. The heat history at an intermediate point until the product is deteriorated and completely deteriorated is judged by erasing any one of the plurality of heat history identifying marks of the product. The heat history identification method using the temperature indicating ink according to item 3.