JP5491134B2 - Container with hidden mark - Google Patents

Description

  The present invention relates to a container formed with a hidden mark for manufacturing process and distribution route tracking, and more specifically, whitening and discoloration due to retort sterilization are prevented, and transparent and resolution by ultraviolet rays. The present invention relates to a container in which a high hidden mark is formed.

2. Description of the Related Art Conventionally, a container having a hidden mark that can be visually recognized by performing a special operation such as irradiating ultraviolet rays for tracking a manufacturing process or a distribution route or for preventing counterfeit products has been known.
Such a hidden mark is, for example, printed using a laser-printed film or metal (Patent Document 1), or ink-jet printing ink that fluoresces and becomes visible when irradiated with ultraviolet rays. (Patent Document 2).

JP 2001-63730 A JP 2004-59831 A

However, the concealed mark engraved with a laser has disadvantages such that the unevenness is easy to read by the reflected light from the outer surface, so that the appearance characteristics are inferior, and a pinhole is generated when the container is engraved with the laser.
In addition, when forming a hidden mark using inkjet printing ink that is visible by ultraviolet irradiation, if the container with the hidden mark is placed under high-temperature and high-humidity conditions such as retort sterilization, whitening due to resin deterioration or Due to the coloring, a hidden mark may be visually recognized in a normal situation (under visible light). In addition, when using the ink jet printing ink described in Patent Document 2, although it has a composition that can reduce the occurrence of whitening due to retort sterilization, the hidden mark is formed on the outermost surface of the container, The effect of retort sterilization cannot be avoided, and the hidden mark formed on the surface of the container may be rubbed during transportation, so that the hidden mark may not be displayed reliably.
The fact that the hidden mark becomes visible in a normal use state is particularly a problem in art cans that are often used for cosmetics containers or confectionery applications that require a beautiful appearance of the container. In many cases, hidden marks were not given to containers.

Therefore, the object of the present invention is that even when retorting is performed, there is no whitening or discoloration, and even when the container is rubbed, it is excellent in invisibility under visible light, transparent, ultraviolet It is to provide a container with a hidden mark with high resolution.
Another object of the present invention is to provide a container with a hidden mark that is excellent in appearance characteristics and can be applied to containers for cosmetics, art cans, and the like that have conventionally been difficult to provide a hidden mark.

According to the present invention, in a container having at least a finish varnish layer formed on the outer surface of the container, a hidden mark ink layer is formed below the finish varnish layer, and the hidden mark ink layer is made of styrene. Made of resin (a), fluorescent colorant (b), conductive agent (c) and organic solvent (d) comprising at least one of resin, acrylic resin, epoxy resin and polyester resin, and does not contain wax A container with a hidden mark is provided which is formed from an ink composition .
In the container with a hidden mark of the present invention,
1. And this print layer between the finishing varnish layer and the hidden marks ink layer is formed,
2 . Tree fat (a) is a styrene - that it is a maleic anhydride copolymer resin,
3 . A hidden mark ink composition, in an amount of 5 to 25% by weight of resin (a) on a solids basis that,
4 . That container is a seamless can,
Is preferred.

In the container with a hidden mark according to the present invention, it is an important feature that an ink layer for a hidden mark is formed below the finished varnish layer in a container having at least a finished varnish layer formed on the outer surface of the container. is there.
In other words, since the conventional hidden mark was formed on the outermost surface of the container, even if the hidden mark is formed using ink with reduced whitening or discoloration due to retort sterilization, it is directly affected by retort sterilization. Therefore, it has been difficult to reliably prevent whitening and discoloration, but the container with a hidden mark of the present invention has an ink layer for the hidden mark formed below the finished varnish layer, so the effect of retort sterilization Therefore, whitening and discoloration can be surely prevented, and problems such as deterioration and elution of ink components due to retort sterilization do not occur.
Moreover, since the conventional hidden mark was additionally formed on the container surface, the hidden mark ink was only dried at room temperature, whereas the hidden mark ink layer of the present invention was used for the hidden mark. Since the finishing varnish to be applied after the ink layer is formed is subjected to a baking process, the ink for the hidden mark can be thermally cured at the same time. It becomes possible to effectively prevent whitening and discoloration due to sterilization.

In the container with a hidden mark of the present invention, since the hidden mark is covered with the finishing varnish, the hidden mark is not read by the reflected light or the like because the unevenness of the printed mark does not appear on the surface of the container. In addition, it is also effectively prevented that the containers are rubbed due to contact between the containers when the containers are conveyed.
Furthermore, even if the hidden mark is located below the finished varnish or the printed layer, the hidden mark can be clearly seen by irradiating with ultraviolet rays.
As described above, the container with a hidden mark of the present invention is not readable in a normal use state under visible light (hereinafter, this effect may be referred to as “invisibility”), and the hidden mark is printed. Since there are no irregularities on the surface of the container, the appearance characteristics of the container are also excellent.

It is a figure which shows an example of the cross-sectional structure of the container side wall of this invention.

(Layer structure)
FIG. 1 is a diagram showing an example of a cross-sectional structure of a container side wall of a container with a hidden mark according to the present invention.
A base coat layer 2 is formed on a base material 1 constituting a container of a container with a hidden mark of the present invention, and a patterned hidden mark ink layer 3 is formed on the base coat layer 2. A printing layer 4 is formed on the hidden mark ink layer 3, and a finishing varnish layer 5 is formed on the printing layer 4.
By providing the hidden mark ink layer above the base coat layer, for example, even when a base coat containing a pigment is applied, the readability of the hidden mark under an ultraviolet light is not deteriorated. Moreover, when using a hidden mark for can manufacturing lot management, since it is preferable to print in the process close | similar to the last process, forming on a basecoat layer is preferable. In addition, by forming the hidden mark ink layer below the printed layer, the hidden property of the mark is improved, and after printing the hidden mark with an inkjet device, printing and finishing varnish are continuously provided with a curved surface printing machine. Therefore, manufacturing efficiency can be increased.

In the container with a hidden mark according to the present invention, in the container having at least a finished varnish layer formed on the outer surface of the container, it suffices that the hidden mark ink layer is formed below the finished varnish layer, as shown in FIG. In addition to being formed on the base coat layer, a hidden mark ink layer may be formed under the base coat layer, or a hidden mark ink layer may be formed on the print layer. Further, after the printing label is wound around the outer surface of the container and heat-sealed, a hidden mark ink layer and a finishing varnish layer may be sequentially formed on the outer surface.
In addition to the solid printing shown in FIG. 1, the printing layer may of course be partially formed by a printing pattern, and conventionally employs printing inks and printing methods used in the field of containers. can do.
Further, depending on the material of the substrate, as shown in FIG. 1, the base coat layer and / or the print layer may not necessarily be provided, and a hidden mark layer may be directly formed on the substrate. Alternatively, as described later, a hidden mark layer may be formed on the resin coating or the surface treatment layer or directly on the metal surface instead of the base coat layer.

(Ink composition for hidden mark)
In the present invention, as an ink composition for forming a hidden mark, a resin (a) composed of at least one of a styrene resin, an acrylic resin, an epoxy resin, and a polyester resin, a fluorescent colorant (b), a conductive agent It is preferable to use an ink composition comprising (c) and an organic solvent (d).
Such an ink composition is transparent and cannot be visually recognized under visible light, but can form a visible hidden mark by irradiating with ultraviolet rays, and can be used under high temperature and high humidity conditions such as retort sterilization treatment. Whitening and discoloration due to heat treatment are reduced, and as described above, in combination with forming a hidden mark layer below the finished varnish layer, whitening or discoloration due to retort treatment can be effectively prevented. is there.

Examples of the styrene resin include polystyrene, styrene-maleic acid resin, and styrene-acrylic resin.
Examples of acrylic resins include poly (meth) acrylic acid ester copolymers, poly (meth) acrylic acid- (meth) acrylic acid ester copolymers, poly (meth) acrylic acid-styrene- (meth) acrylic acid esters, etc. Can be mentioned.
Epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, flame retardant epoxy resins obtained by substituting these epoxy resins with halogens such as bromine, or various types of epoxy groups blocked at the end of these epoxy resins. An end-capped epoxy resin blocked with an agent can be mentioned.
Examples of the polyester resin include resins composed of combinations of dibasic acids such as terephthalic acid, isophthalic acid, and aliphatic dibasic acids, and various dihydric alcohols such as various ethylene glycols and propylene glycols. As a representative example of such a polyester resin, those commercially available under trade names such as Byron (Toyobo Co., Ltd.) and Eritale (Unitika Ltd.) can be obtained. Of course, it is not limited to these.

As the resin (a) which is a binder resin of the ink composition, a styrene resin, particularly a styrene-maleic acid copolymer resin can be suitably used. That is, compared with styrene-maleic acid copolymer resin, acrylic resin tends to be inferior in adhesion, and epoxy resin tends to be inferior in invisibility under visible light depending on the kind of finishing varnish. Therefore, it is preferable to use a styrene-maleic acid resin, in particular a styrene-maleic anhydride copolymer resin esterified with an alcohol of C2 to C18, and thereby invisibility under visible light, and The adhesion of the hidden mark is further improved.
Of course, an acrylic resin, an epoxy resin, and a polyester resin may be mixed and used in the styrene-maleic anhydride copolymer resin.
These binder resins are effective in maximizing the effects of the present invention, but are not necessarily limited thereto. Any resin that does not deteriorate and discolor due to predetermined heating can be used. For example, heat-stabilized modified rosin resin, phenol resin, ketone resin, modified terpene resin, vinyl chloride copolymer resin, various acrylic copolymer resins, amino resins, and the like can be used alone or in combination with the resins listed above. Compositions generally used in the field of baking paints such as thermosetting polyester, thermosetting epoxy ester, epoxy phenol, epoxy acrylic, thermosetting acrylic, and non-yellowing urethane paint can also be used.

In addition, the whitening resistance in the retort sterilization treatment can be improved by blending the resin component (a) with a cellulosic resin that also serves as a thickener. However, when the cellulosic resin is blended, an ink is used for baking the finished varnish. Therefore, when a cellulose resin is blended, it is desirable to blend in an amount of 3% by weight or less in the resin (a) component.
Examples of the cellulose resin include methyl cellulose, ethyl cellulose, propyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, hydroxyethyl cellulose, and nitrocellulose.

As the fluorescent colorant (b), the fluorescent colorant conventionally used in the ink composition for hidden marks can be used. For example, 4,4′-bis (triazin-2-ylamino) stilbene-2, A stilbene derivative such as a 2'-disulfonic acid derivative, wherein the triazinyl group is a suitable substituent such as anilino, sulfanilic acid, metanilic acid, methylamino, N-methyl-N-hydroxyethylamino, bis (hydroxyethyl) Amino), stilbene derivatives substituted with substituents such as morpholino, diethylamino; mono (azoles) such as 2- (stilben-4-yl) naphthotriazole and 2- (4-phenylstilben-4-yl) benzoxazole -2-yl) stilbene; 4,4′-bis (triazol-2-yl) stilbene-2 Bis (azol-2-yl) stilbene such as 2′-disulfonic acid; styryl derivatives of benzene and biphenyl such as 1,4-bis (styryl) benzene and 4,4′-bis (styryl) biphenyl; Pyrazolines such as diphenyl-2-pyrazoline; bis (benzazol-2-yl) derivatives having alkyl, COO-alkyl and SO ₂ -alkyl as phenyl ring substituents; bis (benzoxazol-2-yl) derivatives; 2 Bis (benzimidazol-2-yl) derivatives such as-(benzofuran-2-yl) benzimidazole; 7-hydroxy and 7- (amino substituted) coumarins, 4-methyl-7-aminocoumarin derivatives, esculetin, β-methyl Umbelliferone, 3-phenyl-7- (triazin-2-yl-amino) coumarin, -Coumarins such as phenyl-7-aminocoumarin, 3-phenyl-7- (azol-2-yl) coumarin, and 3,7-bis (azolyl) coumarin; carbostyril, naphthalimide, alkoxynaphthalimide, dibenzothiophene- Examples include 5,5′-dioxide derivatives, pyrene derivatives, and pyridotriazoles, and 2,5bis [5-t-butylbenzooxazolyl (2)] thiophene is particularly preferably used. can do.

As the conductive agent (c), a conductive agent that has been conventionally used for ink compositions for hidden marks can be used. For example, tetraethylammonium chloride, tetraethylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium bromide, Examples include tetrabutylphosphonium chloride, tetrabutylphosphonium bromide, and tetraethylammonium p-toluenesulfonate.
These conductive agents can be used alone or in combination of two or more.

There is no restriction | limiting in particular as an organic solvent (d), All the organic solvents normally used for an ink composition can be used.
Suitable organic solvents include acetone, methyl ethyl ketone, diethyl ketone, cyclohexanone and other ketones, ethyl acetate, propyl acetate, butyl acetate, amyl acetate and other esters, benzene, toluene, xylene and other hydrocarbons, methyl cellosolve, Examples thereof include glycol ethers such as ethyl cellosolve, butyl cellosolve and cellosolve acetate.
These organic solvents can be used alone or in admixture of two or more, and within a range not impairing the solubility of the components constituting the ink composition, methanol, ethanol, n-propanol, isopropanol, n -You may mix alcohols, such as butanol, i-butanol, t-butanol, n-pentanol, n-hexanol. In addition, adding high-boiling solvents such as carbitols and pyrrolidones to these organic solvents makes the hidden mark dots easily collapse and suppresses light reflection from the dots, thus improving the invisibility under visible light. .

The ink composition used in the present invention contains the resin (a) in an amount of 5 to 25% by weight, particularly 7 to 15% by weight, based on the solid content, and the fluorescent colorant (b) of 0.1 to 1.5%. It is contained in an amount of 0.3% by weight, especially 0.3 to 1.0% by weight, and the conductive agent (c) is blended in an amount of 0.1 to 1.5% by weight, particularly 0.3 to 1.0% by weight It is preferable to do.
When the content of the resin (a) is larger than the above range, the printing performance of the ink composition is inferior, the invisibility under visible light is inferior, and the adhesion of the hidden mark is also inferior. become. On the other hand, when the content of the resin (a) is less than the above range, a clear mark cannot be formed and it is difficult to read at the time of ultraviolet irradiation.
In the ink composition used in the present invention, it is preferable that no wax is contained as a leveling agent. That is, in general, it is preferable to mix a wax as a leveling agent in the ink composition in order to improve the fluidity of printed dots and to prevent rubbing during transportation when forming hidden marks on the container surface. However, in the container with a hidden mark according to the present invention, it is not always necessary to add wax because the hidden mark is located below the finished varnish, and by adding no wax to the printed surface of the ink composition. The wettability can be improved, and printing can be performed without repelling ink on the surface of the metal container on which the base coat layer is not formed.

In the ink composition used in the present invention, additives for the ink composition other than the components (a) to (d) may be blended within a range that does not impair the properties of the ink composition. Examples of such additives include leveling agents, plasticizers, surfactants, pressure-sensitive adhesives, thickeners, high-boiling solvents, auxiliary colorants, stabilizers, and the like.
In addition, the ink composition used in the present invention preferably has a viscosity at a temperature of 20 ° C. in the range of 0.5 to 1.5 mPa · s from the viewpoint of printing performance.

(Finish varnish)
In the present invention, as the finishing varnish formed above the hidden mark layer, conventionally known finishing varnishes can be used, such as acrylic resins, polyester resins, vinyl resins, epoxy resins, melamine resins, etc. A coating material made of the above resin can be exemplified, but those having retort resistance are particularly desirable, and although not limited thereto, thermosetting acrylic resins, acrylic epoxy resins, acrylic amino resins, and the like can be used.
The coating amount of the finishing varnish varies depending on the type of the container to which the hidden mark is applied and cannot be generally defined. However, in the case of a metal can, it is preferably in the range of 50 to 70 mg / dm ² , and the finish varnish layer is formed. The baking conditions for the above can not be generally defined by the type of the substrate of the container, but in the case of a metal can, baking is preferably performed at a temperature of 170 to 190 ° C. for 240 to 360 seconds. By this baking step, the hidden mark ink composition applied below the finished varnish layer is also thermally cured, and a stable hidden mark layer that is not affected by retort sterilization or the like can be formed.

(Container with hidden mark)
The container with a hidden mark of the present invention is formed by printing the above-described ink composition for a hidden mark on the surface of the container to form a hidden mark layer, applying a finish varnish thereon, and baking it.
In the present invention, the hidden mark layer can be directly formed on the surface of the container, and the base coat layer is not necessarily required, but when applied to a metal can, the base coat layer is formed and the hidden mark layer is formed on the base coat layer. It is desirable to improve the printability. Also, the base coat layer can be formed above the hidden mark layer.
As the base coat, a resin similar to the resin used for the finishing varnish described above can be used as the base resin, and a pigment such as titanium dioxide, a bright pigment such as mica, or the like may be blended in the base resin.
In addition, in a metal can formed from a resin-coated metal plate or a surface-treated metal plate according to a conventional method, a hidden mark can be printed on the polyester resin-coated or surface-treated layer without forming a base coat layer. Further, the metal can after molding can be subjected to surface treatment according to a conventional method, and a hidden mark can be printed on the surface treatment layer.

As a container for applying a hidden mark, metal containers such as seamless cans and welded cans, glass containers, bottles, trays, cups, tubes, pouches and the like made of a laminate of plastic or metal foil and a plastic film, etc. In the present invention, in particular, a metal plate such as a surface-treated steel plate or an aluminum alloy plate, or a resin-coated metal plate in which a thermoplastic resin such as polyester is coated on one or both surfaces of the metal plate is drawn and ironed. A seamless can formed by drawing, redrawing and ironing can be suitably used.
Examples of the method for providing the hidden mark include conventionally known printing methods such as conventionally known inkjet printing, inkjet printing, offset printing, and gravure printing. In the present invention, it is particularly preferable to form the hidden mark by inkjet printing. Is preferred.
In the case where a hidden mark is formed on the pouch, it is preferable to perform ultraviolet curable or electron beam curable sheet-fed printing or sheet-fed finishing varnish after the hidden mark is printed.
Furthermore, the container with a hidden mark of the present invention prints a hidden mark on the gravure printing surface of the film, and then pre-forms a film or label formed with a finished varnish layer, and attaches the film or label to the outer surface of the container It may be what you did.

The thickness of the hidden mark is preferably in the range of 0.5 μm or more, particularly in the range of 0.5 to 2 μm, from the viewpoint of ensuring readability by ultraviolet irradiation and making it impossible to read under visible light.
Even if the printed layer is formed above the hidden mark layer, the visibility of the hidden mark layer may be impaired when the printed layer is formed by the printing ink and printing method normally used for packaging containers. There is no.
The container with a hidden mark of the present invention can be visually recognized and read by irradiating ultraviolet rays with a black light or the like to cause the hidden mark to develop a fluorescent color.

<Retort whitening>
After the obtained seamless cans were subjected to a stationary retort treatment at 130 ° C. for 30 minutes, n = 5 cans were visually evaluated as follows. The rating of the most inferior can among the 5 cans was taken as the rating in Table 1. ○ and △ are acceptable ranges.
○: Hidden mark has no whitening △: Hidden mark has whitening slightly but is acceptable ×: Hidden mark has clear whitening

<Visibility under fluorescent light>
About 5 obtained seamless cans, the “hiding (invisibility)” of the hidden mark was visually evaluated under a fluorescent lamp. The evaluation criteria are as follows. The rating of the most inferior can among the 5 cans was taken as the rating in Table 1. ○ and △ are permissible ranges ○: I do not know that there are mark characters △: I can see the mark characters slightly but it is within the acceptable range ×: I know that there are clearly mark characters

<Readability under UV light>
After the obtained seamless cans were subjected to a static retort treatment at 130 ° C. for 30 minutes, the readability under UV light was evaluated visually for 5 cans as follows. The UV wavelength of the UV light was 254 to 365 nm. The rating of the most inferior can among the 5 cans was taken as the rating in Table 1. ○ and △ are acceptable ranges.
○: Characters can be clearly read △: Difficult to read but can be read if looked closely ×: Unreadable

<Adhesion>
Five seamless cans obtained were heated and boiled at 100 ° C. for 30 minutes and then dried, and 25 grids were placed on the hidden marks at 1 mm intervals in both vertical and horizontal directions using a cutter knife. (Registered trademark) was adhered and peeled off twice to evaluate the adhesion of the hidden mark interface. The rating of the most inferior can among the 5 cans was taken as the rating in Table 1. ○ and △ are acceptable ranges.
○: No peeling Δ: 2/25 or less peeling ×: 3/25 or more peeling

<Yellowing>
In the yellowing evaluation, a seamless can having a specification in which a finished varnish was provided directly on a hidden mark without providing a printing layer on the can body.
About 5 obtained seamless cans, the degree of yellowing of the hidden mark was visually evaluated under a fluorescent lamp. The evaluation criteria are as follows. The rating of the most inferior can among the 5 cans was taken as the rating in Table 1. ○ and △ are acceptable ranges.
○: No yellowing △: Slightly yellowing but acceptable level ×: Clearly yellowing

<Comprehensive evaluation>
Based on the evaluation results of the above-mentioned retort whitening, visibility under fluorescent light, legibility under UV light, adhesion, and yellowing, comprehensive evaluation was performed. The overall evaluation was scored as follows.
○: All evaluations are “○” △: Each evaluation is “○” or “△” and there is no “×” ×: There is “×” in any of the evaluations

<Example 1>
In a mixed solvent of methyl ethyl ketone: methanol (weight ratio 7: 3), 10% by weight of styrene / maleic anhydride copolymer (SMA 1000P manufactured by Elf Atchem Japan Co., Ltd.) and 2,5-bis [5-t as a fluorescent colorant -Butylbenzooxazolyl (2)] thiophene (UVITEX-08 manufactured by Ciba Specialty Chemicals) 0.5 wt%, tetra-n-butylphosphonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.5 wt. The ink composition was prepared by dissolving in an amount of 1%.
A JIS3004 aluminum alloy plate with a thickness of 0.7 mm is punched out into a disk shape by a conventional method, and after drawing, it is redrawn and ironed, the mouth is trimmed, washed, and a zirconium phosphate surface treatment is performed. A seamless cup was prepared.
The obtained seamless cup was coated on the inner surface and baked, and then a polyesteramino resin was applied to the outer surface of the side wall as a base coat with a coater and baked in an oven at 175 ° C. for 6 minutes. Then, after filtering the ink composition obtained above with a filter, it printed on the outer surface of the cup side wall with "ABCDE" as a hidden mark using the inkjet printer (IJP, Hitachi make). Thereafter, black ink was printed on the outer surface of the side wall by a curved surface printing machine, and then an acrylic amino finish varnish was applied, followed by baking at 180 ° C. for 6 minutes in an oven. Thereafter, neck processing and flange processing were performed to produce a seamless can having a diameter of 50 mm, a height of 175 mm, and a fully-filled internal volume of 294 ml. The seamless can obtained had a layer configuration of “metal layer / base coat layer / hidden mark layer / printing layer / finish varnish layer”.
About the obtained seamless can, retort whitening property, visibility under a fluorescent lamp, legibility under UV light, adhesion, and yellowing were evaluated. The yellowing evaluation can is a seamless can without solid printing. Table 1 shows the container specifications and the evaluation results.

<Example 2>
A seamless can was produced in the same manner as in Example 1 except that the content of styrene / maleic anhydride copolymer in the ink composition was 5% by weight, and the same evaluation as in Example 1 was performed. Table 1 shows the container specifications and the evaluation results.

<Example 3>
A seamless can was produced in the same manner as in Example 1 except that the content of the styrene / maleic anhydride copolymer in the ink composition was 20% by weight, and the same evaluation as in Example 1 was performed. Table 1 shows the container specifications and the evaluation results.

<Example 4>
A seamless can was produced in the same manner as in Example 1 except that the content of styrene / maleic anhydride copolymer in the ink composition was 25% by weight, and the same evaluation as in Example 1 was performed. Table 1 shows the container specifications and the evaluation results.

<Example 5>
A seamless can was prepared in the same manner as in Example 1 except that the resin in the ink composition had a styrene-acrylic copolymer (John Cryl 586 manufactured by Johnson Polymer Co., Ltd.) content of 10% by weight. The same evaluation was performed. Table 1 shows the container specifications and the evaluation results.

<Example 6>
A seamless can was prepared in the same manner as in Example 1 except that the resin in the ink composition was 10% by weight of acrylic copolymer (Rohm and Haas Paraloid B-72). Example 1 The same evaluation was performed. Table 1 shows the container specifications and the evaluation results.

<Example 7>
A seamless can was produced in the same manner as in Example 1 except that the resin in the ink composition was 10% by weight of epoxy resin (Epicoat # 1004 manufactured by Japan Epoxy Resin Co., Ltd.). Evaluation was performed. Table 1 shows the container specifications and the evaluation results.

<Example 8>
A seamless can was prepared in the same manner as in Example 1 except that the content of the polyester resin (Byron 240 manufactured by Toyobo Co., Ltd.) was 10% by weight, and the same evaluation as in Example 1 was performed. It was. Table 1 shows the container specifications and the evaluation results.

<Example 9>
A seamless can was prepared in the same manner as in Example 1 except that ethyl cellulose (Ethcel # 10 manufactured by Dow Chemical Co., Ltd.) as a thickener was added to the ink composition so as to be 3% by weight. Evaluation was performed. Table 1 shows the container specifications and the evaluation results.

<Example 10>
Example 1 except that the resin in the ink composition was 5% by weight of styrene / maleic anhydride copolymer and 5% by weight of acrylic copolymer (Rohm and Haas Paraloid B-72). Similarly, seamless cans were prepared and evaluated in the same manner as in Example 1. Table 1 shows the container specifications and the evaluation results.

<Example 11>
The solvent of the ink composition is a mixed solvent of methyl ethyl ketone: methanol (weight ratio 8: 2), ethyl cellulose (Etocel # 10 manufactured by Dow Chemical Co., Ltd.) is 2% by weight as a thickening agent, and silicon wax (Nihon Unicar Co., Ltd.) as a leveling agent. A seamless can was produced in the same manner as in Example 1 except that FZ-2123) manufactured at 0.1% by weight was added, and the same evaluation as in Example 1 was performed. Table 1 shows the container specifications and the evaluation results.

<Example 12>
A seamless can was produced in the same manner as in Example 1 except that 25% by weight of a titanium oxide pigment was contained in a polyesteramino resin as a base coat, and the same evaluation as in Example 1 was performed. The obtained seamless can had a layer configuration of “metal layer / base coat layer with pigment / hidden mark layer / printing layer / finish varnish layer”. Table 1 shows the container specifications and the evaluation results.

<Example 13>
A seamless can was produced in the same manner as in Example 1 except that the base coat was not provided, and the same evaluation as in Example 1 was performed. The seamless can obtained had a layer configuration of “metal layer / hidden mark layer / printing layer / finish varnish layer”. Table 1 shows the container specifications and the evaluation results.

<Example 14>
A seamless can for diameter 66 mm, height 122 mm, 350 ml was prepared in the same manner as in Example 1 except that the seamless cup was prepared as follows and the inner surface coating and base coat were not provided. Evaluation was performed. The obtained seamless can had a layer configuration of “metal layer / PET resin layer / hidden mark layer / printing layer / finish varnish layer”. The production method of the seamless cup was as follows. That is, a chromium phosphate surface treatment is performed on both surfaces of a JIS3004 aluminum alloy having a plate thickness of 0.28 mm, and then a polyethylene terephthalate / isophthalate copolymer resin is extruded and coated from a T die, and then rapidly cooled to provide a double-sided resin-coated aluminum alloy. A plate was produced, punched into a disk shape by a conventional method, drawn, drawn again and ironed, trimmed at the mouth, heated to remove the distortion of the resin, and a seamless cup was produced. Table 1 shows the container specifications and the evaluation results.

<Example 15>
A seamless can was produced in the same manner as in Example 1 except that the hidden mark was printed after printing, and the same evaluation as in Example 1 was performed. The obtained seamless can had a layer configuration of “metal layer / base coat layer / printed layer / hidden mark layer / finish varnish layer”. Table 1 shows the container specifications and the evaluation results.

<Example 16>
A seamless can was produced in the same manner as in Example 1 except that a hidden mark was directly printed on a metal can and then a base coat was applied, and the same evaluation as in Example 1 was performed. The seamless can obtained had a layer configuration of “metal layer / hidden mark layer / base coat layer / printing layer / finish varnish layer”.

<Example 17>
A seamless cup produced in Example 14 was wrapped with a printed label as described below, heat-sealed, a hidden mark was printed on the outer surface of the printed label, a finish varnish was applied and baked, and seamlessly performed in the same manner as in Example 1. A can was produced and evaluated in the same manner as in Example 1. The printed label is a biaxially stretched polyethylene terephthalate film that is gravure-printed on the inner surface of the can and further provided with a thermosetting adhesive. The obtained seamless can had a layer configuration of “metal layer / PET resin layer / adhesive layer / gravure printing layer / biaxially stretched PET resin layer / hidden mark layer / finish varnish layer”.

<Comparative Example 1>
A seamless can was produced in the same manner as in Example 1 except that the hidden mark was not printed before solid printing, neck processing and flange processing were performed, and then the hidden mark was printed on the finishing varnish of the outer surface of the can body with an inkjet printer. Evaluation similar to Example 1 was performed. Table 1 shows the container specifications and the evaluation results.

In the container with a hidden mark of the present invention, there is no whitening or discoloration even when the retort treatment is performed, and it is not affected even when the container is rubbed. Hidden marks with high resolution are formed, and can be suitably applied to seamless cans and cosmetics cans for cosmetics, for which it has been difficult to provide hidden marks.
Moreover, since the whitening etc. by retort processing are prevented effectively, it can be used suitably for the seamless can which uses tea, coffee, etc. which require retort sterilization as a content, or the pouch for retort food use.

  1 base material (container), 2 base coat layer, 3 hidden mark ink layer, 4 print layer, 5 finish varnish layer.

Claims (5)

In a container having at least a finish varnish layer formed on the outer surface of the container, a hidden mark ink layer is formed below the finish varnish layer, and the hidden mark ink layer is formed of a styrene resin or an acrylic resin. , A resin (a) comprising at least one of an epoxy resin and a polyester resin, a fluorescent colorant (b), a conductive agent (c) and an organic solvent (d), and formed from an ink composition containing no wax. hidden marked container, characterized in that is.   The container with a hidden mark according to claim 1, wherein a printed layer is formed between the finish varnish layer and the ink layer for the hidden mark. The container with a hidden mark according to claim 1 or 2 , wherein the resin (a) is a styrene-maleic anhydride copolymer resin. The container with a hidden mark according to any one of claims 1 to 3 , wherein the ink composition contains the resin (a) in an amount of 5 to 25 wt% based on the solid content. The container with a hidden mark according to any one of claims 1 to 4 , wherein the container is a seamless can.

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