JP2014108413A - Method of printing information on packaging container surface having tampering prevention performance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve rubbing or scratch resistance in manufacturing process or distribution process of products so as to transmit printing information by an ink jet printer to an end user.SOLUTION: An information printing method by an ink jet printer on a packaging container surface that is a resin layer, the information printing method having a tampering prevention performance, includes: printing information using ink containing solvent soluble and nonionic dyestuff; and heating a part on which the information is printed.

Description

It is required by law to display information such as the date of manufacture, expiration date, or expiration date on products, especially food packaging containers.
As a means for printing such information to be displayed, an ink jet printer that can be implemented arbitrarily and at high speed is currently the mainstream.
In printing information on packaging containers using inkjet printers, because there are restrictions on the material and shape of the container, the heat curing means used at high temperatures used in industrial paints cannot be taken. It must be in a situation.

In the case of such room temperature drying, in the packaging container, because the adhesiveness cannot be increased by means such as heating over time, the printing may be rubbed and blurred in the manufacturing process or distribution process of the product, Or the problem that it was scraped off and disappeared frequently occurred.
In particular, in packaging containers using polyolefin base materials such as polyethylene and polypropylene, the adhesion of the ink film is fragile, so there is a problem that printed information is easily lost due to rubbing or scratching. The improvement measures have been sought for many years.
In order to convey the product information printed by the inkjet printer to the end consumer, various improvement proposals have been made so far in order to improve the resistance to rubbing and scratching in the manufacturing process or distribution process of the product.

JP 2000-38530 A JP-T-2001-520298 Japanese Patent Laid-Open No. 10-204346 JP 2002-201393 A Japanese Patent Laid-Open No. 2002-146245 Japanese Patent Laid-Open No. 10-195356 Special table 2010-518214 gazette JP 2010-275467 A

  Patent Document 1 discloses an ink-jet ink having sufficient adhesion and durability to a packaging film such as polypropylene without corona discharge treatment, and Patent Document 2 and Patent Document 3 show abrasion scratch resistance against polyolefins. A good jet ink is disclosed in Patent Document 4 and Patent Document 5 including an ink containing a binder resin having good adhesion to polyolefin, and other similar techniques are disclosed in Patent Document 6 or Patent Document 7.

As awareness of product liability rises, awareness of hygiene advances, and alcohol spraying or cleaning treatment may be performed in the product or manufacturing environment. For conventional printing and marking, alcohol and other thinners may also be used. Tolerance to varieties is also required.
Patent Document 8 discloses an ink composition that has good resistance to rubbing, abrasion, hand scratches, and the like with respect to a polyolefin substrate, and is also resistant to ethanol.

In the examples disclosed in the previous term, Patent Document 1 is an ink in which the binder resin is a combination of polyamide resin and rosin resin, Patent Document 2 is an ink mainly composed of nitrocellulose as the binder resin, or Patent Documents 4 and 5 are binder resins. Is an ink made of butyral resin, and Patent Documents 1 and 2 show that although the resin itself has some durability, there is almost no adhesion to the polyolefin substrate, and the addition of rosin resin or the like supplements the adhesion. It does not satisfy the abrasion or scratch resistance. Patent Documents 4 and 5 mention that the resin itself has adhesion to the olefin substrate, but practically, resistance such as scratch resistance and abrasion resistance is insufficient.
These inks easily lose print information just by being immersed in ethanol after printing.

  The disclosed example of Patent Document 6 is an ink using a chlorinated polyolefin resin as a binder, and this has better adhesion to a polyolefin substrate than ordinary resins. However, the resin itself is fragile and cannot satisfy mechanical durability such as scratching and abrasion. Ethanol tolerance is not good either.

  Patent Document 7 proposes an ink that does not use methyl ethyl ketone, which is problematic in terms of environmental hygiene, by using non-cyclic acetals with good resin solubility in the solvent, and it can be used for polyolefin substrates. However, it does not outperform the above disclosed example.

  In the patent document 8, the present inventors have proposed an ink using a binder resin in which a vinyl chloride resin having a good mechanical durability and a chlorinated polyolefin are combined. Although these have better mechanical durability and ethanol resistance than conventional known techniques, they are easily lost by thinners that easily affect resins such as methyl ethyl ketone.

As described above, conventionally, printing information on a resin surface by an ink jet printer has the following problems.
1. Since the resin surface of the packaging container, especially the polyolefin resin surface, does not adhere well to the printing ink, the printed product information may be faded or lost if the printed surface is rubbed or scratched. End up.
2. In relation to product liability, from the standpoint of hygiene, there are many opportunities for products to be exposed to solvents such as alcohol and thinner, and printed product information is lost by such solvents.
3. Further, the most important problem is that it is difficult to prevent falsification of merchandise information printed by the ink jet method with the conventional known technology.

As a result of researches on solving the above problems, the present inventors have found that in the ink jet ink comprising a binder resin, a dye, a solvent, and a conductive agent, the dye is a solvent-soluble dye and a nonionic dye, After printing product information by ink jet using ink, by heating the printed part, ethanol is of course, even if you try to scrape with a solvent such as methyl ethyl ketone, the information will not disappear, it will remain in a clear state, It was found that falsification of print information can be prevented.
The inventors previously proposed an information printing method in which print information by an ink jet printer is heated using heated air in Japanese Patent Application No. 2008-285490.

In this prior art, the surface of the polyolefin substrate of the packaging container and the ink film are simultaneously heated to melt both, and the ink film is firmly fused and fixed on the surface of the polyolefin substrate.
However, heating until the polyolefin base material is melted causes sagging of the surface of the container, impairs the appearance of the container, and deteriorates the material of the base material of the heated part if it stays even a little, as a food storage container There is a risk of impairing the quality of the product.

Therefore, the degree of heating is limited, and when a soft polyethylene substrate is rubbed with a thinner such as methyl ethyl ketone, the printed information is barely readable. However, in the case of a polypropylene or rigid polyethylene substrate, methyl ethyl ketone is used. In the case of scraping with a thinner such as that, the print information was almost lost, and it was not yet satisfactory.
When the dye used in the inkjet ink is solvent-soluble and a nonionic dye is used, the present inventors rubbed with methyl ethyl ketone even when heated under milder heating conditions than the various disclosed examples. Also, it has been discovered that clear print information can be retained.

In Patent Documents 3, 4 and 7, metal-containing complex dyes are used as preferred pigments in other disclosed examples, and these metal-containing complex dyes are ion-dissociated in a solvent-dissolved state. However, it is known that it itself exhibits electrical conductivity and is widely used. However, these ionic metal-containing complex dyes are extremely difficult to be dyed onto a packaging container substrate by heating.
As described above, from the disclosure examples of the conventional series of prior patent documents, it has not been found that a specific dye brings about an effect that can prevent such falsification of print information.

The reason is not clear, but it is presumed that when the dye is a solvent-soluble dye and nonionic, it has an affinity for nonpolar polypropylene or polyethylene and easily penetrates into the substrate by heating.
This is because hydrocarbon solvents such as toluene and cyclohexane have an affinity for polyolefin and are easy to diffuse and permeate non-polar polyolefin base materials, while polar solvents such as ketone and alcohol are difficult to diffuse and permeate. It seems the same phenomenon.
In the present invention, it is further characteristic that the same effect is exhibited for a base material such as polyethylene terephthalate which has been impossible in the past.

The present invention will be described in more detail.
[Dye]
The colorant used in the ink composition for a jet printer of the present invention is characterized by being substantially a solvent-soluble dye and a nonionic dye.
Specific examples are CI solvent dye black 3, red 3, 18, 19, 23, 24, 25, 27, 49, 73, yellow 2, 14, 16, 29, blue 4, 5, 11, 35, 38. , Green 3, 5, 7,
Disperse dye blue 1,3,7,26, yellow 3,5,7,8,42,60,64, red 1,4,13,17,60,65, black 1,29,
Violet 1,4,26,28, orange 1,3,5,13,30,
A partially acidic dye such as Acid Red 2 is a typical dye.

Particularly preferred dyes are selected from those having a monoazo, disazo, anthraquinone, or triphenylmethane structure.
These dyes are sold under trade names such as varifast color, oil color (Orient), Brytolb (BR Y chem), Kyalon (Nippon Kayaku)), Eisenspirone (Hodogaya Chemical). In addition, any commercially available dye such as Mitsubishi Kasei or Fine Shoji may be used as long as it is a solvent-soluble dye and a nonionic dye.
These dyes may be used alone or in combination.
The content of the dye in the ink composition is at least 0.3 to 10% by weight (hereinafter, unless otherwise specified, the weight% is simply expressed as%), and if it is less than this, the printed information after heating becomes unpreferable. A preferable content is 1 to 7%.

In the ink composition, other pigments can be added in addition to the above dyes. Examples of these pigments include metal-containing complex dyes, basic dyes, acid dyes, organic pigments, and inorganic pigments.
The total content of the pigments in the ink composition is typically 2% to 10%, and if it is less than this, the color tone of the printed information becomes light. On the other hand, if it is too large, ink jet suitability or ink film physical properties will be weakened.

[Binder resin]
Various acrylic resins and copolymer resins such as acrylic resin, styrene-acrylic resin, acrylic ester resin, acrylic-maleic acid resin, styrene resin, maleic acid resin, styrene-maleic acid resin, epoxy resin, epoxy ester resin, rosin and rosin Ester resin, rosin-modified maleic resin, phenol-modified rosin, butyral resin, ketone resin, phenol resin, ester resin, terpene resin, coumarin resin, petroleum resin, polyester resin, vinyl chloride resin, chlorinated polyolefin resin, cellulose resin, Any general resin such as various cellulose resins such as cellulose nitrate resin may be used.

These may be used alone or in combination of two or more, and can be arbitrarily selected according to the use of the ink composition or the performance to be provided.
Particularly preferred are acrylic ester copolymer resins, polyester resins, vinyl chloride resins, and the like. When it is desired to impart adhesion to polyolefin, polyamide resin, chlorinated polyolefin resin, rosin-modified resin, ester resin, or the like may be used in combination with these resins.

The resin content in the ink composition is typically 5 to 30% based on the total ink weight.
The resin content is determined by the characteristics of the binder resin to be used, but if it is less than 5%, the viscosity is lowered, and the ink jet suitability or the dye retention is lowered. On the other hand, if it exceeds 30%, the ink viscosity becomes too high, and the inkjet suitability is also lowered.
A preferable content is 5 to 20%.

[solvent]
Ketone solvents such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone, diethyl ketone, methyl isobutyl ketone, alcohols such as methanol, ethanol, n-propanol, isopropanol, butanol, isobutanol, methyl acetate, ethyl acetate, Acid esters such as propyl acetate and methyl propionate, ethylene glycol monomethyl ether, dimethoxyethane, ethylene glycol monoethyl ether, monomethoxypropanol, ethylene glycol monoacetyl ester, ethylene glycol monoacetyl-methyl ether such as glycol ethers, esters, 1,1 dimethoxyethane, acetals such as 1,1 diethoxyethane, cyclic ethers such as furan, toluene, And aromatic hydrocarbons such as cyclohexylene and the like.
Any solvent can be used as long as it dissolves the binder resin to be used, and a plurality of these may be used in combination.

[Conductive agent]
In the continuous ink jet, the ink needs to have conductivity.
In general, when the pigment is ion dissociable in a solvent, it is often unnecessary to add a conductive agent, but a conductive agent is necessary because the dye of the present invention is not a metal-containing complex salt or an ionic dye. It is.
Conductive agents include inorganic salts such as lithium chloride, potassium bromide and sodium iodide, potassium thiocyanate, ammonium thiocyanate, alkyl and aryl quaternary ammonium salts and phosphonium salts, alkyl and arylamine and alkanolamine hydrochlorides There are various organic salts. Of course, it is not restricted to the electrically conductive agent described here, The electrically conductive agent generally used in this field | area can be used.
These may be used alone or in admixture of two or more.
The addition amount of the conductive agent is in the range of 0.2 to 1.0%, and if it is small, the ink jet suitability is impaired, and if it is large, the physical properties of the printed film are impaired.

[Heating method]
In the method of the present invention, it is essential that the pigment is a solvent-soluble dye and contains a nonionic dye, but it is also essential to heat the print information part.
As a preferable heating method, there is a method in which heated air is blown onto a printed information portion of a product moving on a conveyor. The heating air should just be the air heated to 400 degreeC or more at least.
In addition, a method of pressing a jig such as a heating roll against the print information part, or a method of heating the packaging container itself to which the print information has been applied in a heating oven may be used. It is necessary to heat under conditions that do not impair the quality.

Further, as a method of heating the packaging container itself, there is a method of using heating by heat sterilization treatment as necessary after filling and sealing the contents in the packaging container. For example, sterilization treatment at 100 ° C. or higher can be mentioned.
The heating method is not limited to the methods listed here.
[Other additives]
In the present invention, in addition to the binder resin, dye, solvent, and conductive agent, surfactants, plasticizers, alkoxysilanes, and other additives are used as long as the properties of the ink composition of the present invention are not impaired. May be.

Silicon-based, fluorine-based and other surfactants can improve printing bleeding.
Of these, silicon surfactants are preferable from the viewpoint of solvent solubility and ease of adjustment, and various examples include alkyl-modified silicon, alkoxy-modified silicon, polyoxyethylene-modified, polyalkyl ether-modified silicon, and other polyalkyl ether siloxane compounds. .
The falsification preventing method of the present invention shows a remarkable effect when the packaging container itself or the resin layer on the packaging container surface is formed of a polyolefin resin such as polyethylene or polypropylene and a polyethylene terephthalate resin.
The polyolefin resin layer on the surface of the packaging container may be formed by coating or lamination, but the packaging container itself or the surface of the packaging container is not limited to these resins.

For example, a metal can coated with a thermosetting resin, a flexible packaging container with a surface layer formed of nylon resin, cellulose resin, vinyl chloride resin, etc., or other various resins or various resins The coated packaging container can also have a sufficient anti-tampering effect.
Specific examples of the present invention are shown below.

Example 1
A binder resin composed of 7% by weight of an acrylic resin (Paraloid B67, ROM & HASS), 6% by weight of an ester resin (Halitak E10, Harima Chemical) (hereinafter referred to simply as%), and further oil black 860 (Dye 1; Solvent) Black 3 Orient Chemical) 4%, Silicon Oil (FZ2123, Toray Dow Corning) 0.5%, and conductive agent tetraethylammonium chloride 0.6% dye, conductive agent and leveling agent 1,2-ethylene glycol An ink composition for an inkjet printer of Example 1 of the present invention was prepared by dissolving in dimethyl ether and a 4/6 weight ratio solvent of ethanol and filtering with Toyo Roll Paper 5C.

The paper milk filling container whose surface is coated with polyethylene is moved on a conveyor at a speed of 20 m / min, and the date is printed with the ink of this embodiment using a Hitachi continuous ink jet printer, followed by heating with hot air. The apparatus was heated by spraying heated air at 600 ° C. on the date printing section.
The date printed part thus heated after printing was kept in a clear state although the date printed part was slightly thinner even when rubbed with a cloth soaked with methyl ethyl ketone, and could not be tampered with. .

Further, the heated portion of the surface-covered polyethylene base material was in a normal state without any sagging or the like because the gloss was slightly weakened.
Further, when the heating air temperature was set to 800 ° C., 700 ° C., 500 ° C., and 400 ° C., the date printing became thin when it was rubbed with a waste impregnated with methyl ethyl ketone when heated at 500 ° C., but it was sufficiently legible. In the case of heating at 400 ° C., when the same treatment was performed with methyl ethyl ketone, the date print was considerably thinned, but it was readable and not tampered with.

In these cases, the heated portion of the polyethylene-coated substrate was normal with no change.
On the other hand, when the heating air temperature was 800 ° C. and 700 ° C., even when rubbing with a waste impregnated with methyl ethyl ketone, the date printing was clear and almost the same as before the treatment with methyl ethyl ketone. The heated part of the surface-coated polyethylene base material was slightly sagging at 700 ° C, but there was no problem with the product quality, but when heated at 800 ° C, the surface melted and became quite sagging. It was not a preferable state.

Comparative Example 1
In Example 1, when the temperature of the hot air heating apparatus was not heated and was heated at a temperature of 300 ° C., the date printing disappeared when rubbed with a waste impregnated with methyl ethyl ketone without heating. Although the date prints remain slightly when heated at 300 ° C, they are difficult to read. In these cases, reprinting is possible from above, and tampering is possible by heating at a temperature of about 600 ° C with a hot air heating device. It was.
The results of Example 1 and Comparative Example 1 are summarized in Table 1.

(Evaluation): The date printed part after printing and heating was evaluated by visually checking the remaining date printed state and the state of the coating on the resin surface of the container surface according to the following criteria when rubbing several times with a cloth soaked with methyl ethyl ketone. It was evaluated with.
Date printing remaining state A: Almost no change, and a clear state was maintained before methyl ethyl ketone treatment.
○: Slightly thin and cannot be tampered. △: Very thin but sufficiently decipherable and impossible to tamper. ×: Slightly remaining but difficult to decipher and tamperable.

State of the resin surface of the container surface after heating A: Normal state with almost no change.
○: The gloss is slightly thin and the normal state is maintained. △: The gloss is lost and slightly sagging is observed, but there is no problem with the container quality. ×: The surface is considerably sagging and the product quality is improved. Problem

Comparative Example 2
An ink prepared in the same manner as in Example 1 except that VariFast Black 3820 (Dye 2; Solvent Black 27, Azochrome Complex Salt Orient Chemistry), which is an ionic dye, is used instead of the oil black 860 of the dye in Example 1. The paper milk container was printed and heated under the same conditions as in Example 1.
When this date printed part was rubbed with a cloth soaked with methyl ethyl ketone, the date printed disappeared and nothing remained.

Comparative Example 3
The heating air temperature after date printing in Comparative Example 2 was increased to 700 ° C. and 800 ° C. and heated. In the case of 700 ° C heated air, the resin film on the surface of the container is slightly sagging, but there is no problem with the quality of the container, but the date print is slightly browned when rubbed with a cloth soaked with methyl ethyl ketone. Interpretation was difficult to the extent that it remained. When the heated air was heated to 800 ° C. and heated, the date print remained dark brown and could be read, but the coating resin on the surface of the container became considerably rough and the appearance as a container was impaired.

Example 2
Using the ink of Example 1, after the date was printed on a polypropylene cup container and a polyethylene terephthalate pouch container as the packaging container, the heated air temperature was 800 ° C, 700 ° C, 600 ° C, and After heating under the condition of 500 ° C., rubbing evaluation was performed with a waste impregnated with methyl ethyl ketone.

Comparative Example 4
Date printing and heating were performed in the same manner as in Example 2 using the ink used in Comparative Example 2.
The evaluation results of Example 2 and Comparative Example 4 are summarized in Table 2.

  As shown in Table 2, it can be seen that even when the container resin base material is polypropylene or polyethylene terephthalate, the ink of the present invention can prevent tampering.

Example 3
Similar to Example 1 except that Oil Red 5B (Dye 3; Solvent Red 25 Orient Chemistry) was used in place of the oil black 860 of the dye in Example 1, using the ink prepared in the same manner as in Example 1. When the paper milk container was printed and heated under the conditions described above, even if it was rubbed with a waste impregnated with methyl ethyl ketone, the date print did not disappear and the clear state was maintained.
Evaluation was performed in the same manner as in Example 1 using the dyes shown in Table 1 below.

Dye 4; oil scarlet 318 (solvent red 18
Dye 5; oil blue 2N (solvent blue 35
Dye 6; oil green 530 (solvent green 3
Dye 7; Oil Red 25 / Oil Green 530 1/1 Blend Dye 8; Disperse Blue 3
Dye 9; Disper thread 17
Dye 10; Disperse Black 1
Dye 1 Disazo type Dye 3 Disazo type
Dye 4 Triphenylmethane
Dye 5 Anthraquinone Dye 6 Anthraquinone Dye 8 Anthraquinone Dye 9 Monoazo Dye 10 Monoazo

  When rubbing with a cloth impregnated with methyl ethyl ketone, Example 3 was easy to read and not tampered with, although the residual darkness of the print was thin. In all of Examples 4-9, the remaining darkness of the print was sufficient, and of course, falsification was impossible.

Comparative Example 5
Using each ionic dye of the comparative example shown in Table 4, an ink was prepared and evaluated in the same manner as in Example 1.
In either case, the print was lost, and it was not possible to prevent tampering.

Dye 11; Bali Fast Black 1815 (Acid Black 1)
Dye 12; Acid Black 26
Dye 13; Acid Red 18
Dye 14; Basic Black 2
Dye 15; Basic Violet 1 (Methyl Violet)

Example 10
A paper butter outer container coated with polyethylene using the ink of Example 1 was subjected to date printing, then passed through an oven at 120 ° C. for 1 minute, and then rubbed with a waste impregnated with methyl ethyl ketone. However, although the date printing is slightly thinner, it remains in a clear state and cannot be tampered with.
Comparative Example 10
In Example 10, when the evaluation was made in the same manner as in Example 10 except that the ink of Comparative Example 2 was used, date printing disappeared. Tampering is now possible.

Example 11
Byron 240 (resin 1; polyester resin Toyobo) as binder resin, 4% oil black 860 (dye 1), leveling agent FZ2123 0.4%, and potassium thiocyanate 0.6% as conductive agent Then, it was dissolved in methyl ethyl ketone and filtered through Toyo Roshi 5C to prepare an ink composition for an ink jet printer.
Using this ink, evaluation was performed under the same conditions as in Example 1.
Hereinafter, inks having the compositions shown in Table 3 were prepared as examples and evaluated.
In either case, it was sufficient for the purpose of the present invention.

Resin 2; Chlorinated polyolefin resin 224H (Nippon Paper Chemicals)
Resin 3; Chlorinated polyolefin resin S2510S (Nippon Paper Chemicals)
Resin 4; Epoxy resin # 1007 (Mitsubishi Chemical)
Resin 5; Acrylic resin Paraloid B66 (ROM & HASS)
Resin 6; Polyester resin Byron 614 (Toyobo)
Resin 7; Vinyl chloride resin E15 / 40A (wacker)
Resin 8; Rosin-maleic acid modified resin (Hitachi Chemical)

Example 19
Using the ink of Example 1 and Example 6 and printing the date on the polyethylene cap of the milk bottle in the same manner as in Example 1, then changing the temperature conditions of the heated air to 700 ° C, 600 ° C, and 500 ° C and heating Processed.
As a result, at 500 ° C., the print was considerably thin and difficult to read. Further, at 600 ° C., the date printing is slightly thinner, but can be read and cannot be tampered with. In the case of 700 ° C., although the surface state of the polyethylene cap in the heated portion was slightly sagged, there was no problem with the quality of the product, and the date printing was kept clear.

Comparative Example 11
Evaluation was performed in the same manner as in Example 19 using the inks of Comparative Examples 2 and 9, but the date printing disappeared neatly.
Although the heated air temperature was raised to 700 ° C., the print was still left slightly by the waste treatment soaked with methyl ethyl ketone, but it was difficult to read and tampering was possible. When the heated air temperature was 800 ° C., the resin base material in the heated portion was distorted and the container quality was impaired.
As described above, according to the method of the present invention, it is possible to prevent tampering, which has been impossible in the past, without impairing the quality of the polyolefin plastic packaging container.

Example 20
After printing on the bottom of a metal can for coffee beverages (TULC can and heat-cured paint-coated can) using the inks of Examples 1 and 6, heat treatment was performed under the same conditions as in Example 1, and then methyl ethyl ketone was added. When the wiping treatment was performed with the soaked waste, the print remained slightly thin but clear.

Example 21
The metal can used in Example 20 and the outermost package were subjected to date printing on the polyethylene terephthalate-coated pouch container using the ink used in Example 20, followed by retort sterilization at 121 ° C. for 20 minutes, and then the date printing part. Was rubbed with a cloth impregnated with methyl ethyl ketone, but the print remained clear without disappearing.

Comparative Example 12
In Example 21, the evaluation was performed in the same manner as in Example 21 except that the ink of Comparative Example 2 was used, but the date printing was lost.

  The present invention relates to an inkjet ink composed of a binder resin, a pigment, a solvent, and a conductive agent, and a solvent-soluble dye and a nonionic dye are used as the pigment, and information is printed by inkjet using the ink of the composition. , By heating the information printing part, ethanol is of course, even if you try to scrape with a solvent such as methyl ethyl ketone, the information does not disappear, it remains in a clear state, and it can prevent falsification of the printed information, In particular, it can be suitably used for printing production date and the like on a synthetic resin food container.

Claims (9)

  An information printing method using an ink jet printer on the surface of a packaging container whose surface is a resin layer, using an ink containing a solvent-soluble and nonionic dye, printing information with the ink, and then heating the information printing part An information printing method having anti-falsification performance, characterized by:   The information printing method according to claim 1, wherein the heating temperature is 100 ° C. or more.   The information printing method according to claim 1, wherein the heating is heating with heated air, and is local heating in which heated air is blown onto the information printing unit.   The information printing method according to claim 1 or 2, wherein the heating is heating in a heating oven or heat sterilization, and the container on which information printing has been performed is heated.   The information printing method according to claim 1, wherein the information printing method is a printing method using a continuous ink jet printer.   6. The information printing method according to claim 1, wherein the packaging container itself or the resin layer on the packaging container surface is formed of polyethylene, polypropylene, or polyethylene terephthalate.   The information printing method according to claim 1, wherein the resin layer on the surface of the packaging container is formed by coating or lamination. The solvent-soluble and nonionic dyes are CI solvent dyes Black 3, Red 3, 18, 19, 23, 24, 25, 27, 49, 73, Yellow 2, 14, 16, 29, Blue 4, 5 , 11, 35, 38, Green 3, 5, 7,
Disperse dye blue 1,3,7,26, yellow 3,5,7,8,42,60,64, red 1,4,13,17,60,65, black 1,29,
Violet 1,4,26,28, orange 1,3,5,13,30,
The information printing method according to claim 1, wherein the information printing method is one or more selected from partially acidic dyes such as Acid Red 2.   A packaging container comprising a resin surface layer printed by the information printing method according to claim 1.