JP2022098425A - Aqueous inkjet printing device - Google Patents

Abstract

To enable aqueous inkjet printing to be performed on a plastic film.SOLUTION: In a hot-air drying passage of an aqueous inkjet printing device configured so that a film F to be printed passes through an inkjet head part and runs on the hot-air drying passage while being applied with constant tension, the film is conveyed while being adsorptively fixed onto a belt 31 of a belt conveyor 30, so as to enable the film to stably run so that the film neither flogs nor meanders.SELECTED DRAWING: Figure 1

Description

The present invention relates to a water-based inkjet printing apparatus, and particularly to a printing apparatus most suitable for a plastic film packaging material used for a packaging bag for accommodating a food product or a lid of a food container.

Nowadays, when distributing foods, instead of face-to-face sales in which foods prepared on the spot are packaged and sold, packaged foods in which processed foods, breads, confectionery, etc. prepared in advance at a food factory are packaged are used as conveniences. The method of selling at retail stores such as stores and supermarkets is becoming mainstream.

In the above-mentioned sales method, the packaged food is displayed on a display shelf in a retail store, and the customer picks it up and examines it when purchasing. Therefore, it is necessary to devise a design so that the packaging itself attracts customers'willingness to purchase and makes it easier for customers to see.

In the above case, since the primary purpose of the packaging material itself is to wrap food, it is not possible to change the shape so as to impair its function, and the design and / or characters applied to the surface (hereinafter referred to as "hereinafter"). The role of "design, etc.") is very important.

Printing is generally used as a means for applying the above-mentioned patterns to the lids of packaging bags and food containers, and when printing on the lids of packaging bags and food containers, printing is performed on the back side of these (back printing). There are two types of printing methods, one is to print on the front side and the other is to print on the front side (front printing). In this case, in food packaging materials, the Food Sanitation Law prohibits printing ink from coming into contact with food. Therefore, when printing on the back side of these, protective plastic is placed on the side of the printing layer of the plastic film. The films had to be laminated.

On the other hand, when printing on the front side of the packaging material, there are no restrictions as described above, but since the printing layer is exposed, it is printed on the back side of the film when it is printed on the packaging bag or lid and wound up. Care must be taken to prevent the printed layer from becoming unclear due to physical friction or solvent (alcohol or oil) due to contact, contact with other packaging materials or articles during distribution or exhibition, or contact with human fingers. did not become.

In the above case, since the plastic film is a base material that does not easily absorb liquid unlike paper, gravure printing using gravure ink having high coating adhesion and flexographic printing using flexo ink have been adopted for printing. (For example, Patent Document 1).

By the way, inkjet printing, which does not require plate making for printing and can generate images for printing from digital data, has excellent on-demand properties and should be originally useful for food packaging materials that must print various patterns at any time. However, it could not be adopted.

The reason is that the water-based inkjet ink capable of inkjet printing does not have various physical properties such as abrasion resistance, alcohol resistance, oil resistance, and water resistance, and the ink easily falls off and the coating film adhesion is weak. In this case, since the viscosity of the gravure ink and the flexographic ink having high adhesion to the coating film is too high, it cannot be used because it is impossible to smoothly eject the ink from the nozzle in the inkjet printing in which the ink is ejected and adhered from the nozzle.

Improve production efficiency in food packaging materials that are consumed in a short period of time rather than fixed durable consumer goods with fixed types such as patterns, and that must be printed with a wide variety of patterns according to the contents at any time. Therefore, speeding up printing is indispensable.

However, gravure printing and flexographic printing, in which plates must be prepared for new designs and set on the production line each time, take time to start printing, and there is a limit to speeding up. rice field.

For example, in the case of food packaging materials in which patterns are printed by gravure printing, it takes a total of 12 days for the work required before printing (block copy submission + plate making) and printing, and other post-processing (film lamination, finishing processing). ), Which took 6 days and a total of 18 days.

In addition, as described above, gravure printing requires time and effort for color separation and plate making, so the minimum order lot is inevitably large, and the customer has no choice but to purchase more packaging material than necessary, resulting in waste loss.

On the other hand, the option of adopting inkjet printing when printing on the back side of the bag can be easily made, but this requires a process of laminating the plastic film on the side of the printing layer of the plastic film, which requires cost and time. I had a problem.

In this regard, the inventor of the present application created the following invention.
In the first invention, in order to print a pattern and / or a character on a surface located on the front side at the time of making a bag of a plastic film to be composed of a food packaging material, the pattern and / or the character was inkjet printed using an inkjet ink. Later, the invention is characterized in that a transparent inkjet ink is overprinted on the print area by inkjet printing.

Further, the second invention is to print a design and / or a character on a surface located on the front side of a plastic film to be composed of a food packaging material, after the design and / or the character is inkjet printed using an inkjet ink. The invention is characterized in that transparent UV ink is overprinted.

Further, the third invention is to print a design and / or a character on a surface located on the front side of a plastic film to be composed of a food packaging material, after the design and / or the character is inkjet printed using an inkjet ink. The invention is characterized in that transparent EB ink is overprinted.

JP 2000-273379

According to the above-mentioned invention by the inventor of the present application, when printing a pattern or the like on the surface located on the front side of the lid of a packaging bag or a food container, even if the print is inkjet printed using a water-based inkjet ink, the printed area is transparent. Ink ink, transparent UV ink, or transparent EB ink is overprinted to protect the print layer such as a pattern, so that the print layer such as a pattern is not exposed.

Therefore, when printing on a packaging bag or lid and winding the film, it may come into contact with the back surface of the film, or it may come into contact with other packaging materials or articles during distribution or exhibition, or with human fingers. This prevents the printed layer such as a pattern from being scraped by friction and becoming unclear or producing shavings.

On the other hand, since printing is completed by inkjet printing with excellent on-demand characteristics, we have to prepare a plate for new patterns and set it on the production line, and start printing like gravure printing and flexographic printing. It is possible to speed up the process without taking time for the process, and dramatically improve the production efficiency of food packaging materials, which must be printed with a wide variety of patterns according to the contents. be able to.

According to the above invention, in printing a plastic film, the water-based inkjet ink does not have various physical properties such as abrasion resistance, alcohol resistance, oil resistance, and water resistance, and the ink easily falls off and the coating film adhesion is weak and cannot be adopted. It breaks the conventional technical wisdom.

However, the inventor of the present invention, who has performed water-based inkjet ink printing on a plastic film that no one has started so far, has faced a new problem.

In water-based inkjet printing where the ink head part (printing part) is non-contact type, the tension of the ink head part to be printed and the tension of the film running on the drying path are the same conditions, so that the drying temperature and the tension of the drying path are the same. The problem is that the effect causes thermal expansion and contraction of the film, making it impossible to control the register and dimensions.

Therefore, in water-based inkjet printing in which the film to be printed passes through the ink head portion and travels on a hot air drying path while being given a certain tension, stable running is performed so that the film does not flutter and meander due to hot air during hot air drying. It became necessary to give the tension that can be produced.

FIG. 3 is one of the measures for that purpose. Here, in the hot air drying path, a plurality of large-diameter rotating drums 41, in which the film F travels while contacting the arc surface on the outer circumference as the film rotates, are prepared and the film is prepared. Is sequentially sent to the next rotating drum, and the film is dried by the heat from the rotating drum with which it contacts and the hot air device 43 arranged on the peripheral side of the rotating drum, so that the film is stable so as not to flutter and meander. It realizes the running. Reference numeral 42 in the figure is a guide roller for guiding the film.

Further, FIG. 4 is one of the other measures for that purpose. Here, in the hot air drying path, the film F is dried with an infrared heater (not shown), and then the hot air device (not shown) is installed. By running along a spiral path in the provided drying furnace and drying with hot air, stable running is realized so that the film does not flutter and meander. Reference numeral 52 in the figure is a guide roller for guiding the film.

The present invention has been created for the purpose of realizing stable running so that the film does not flutter and meander by means different from the above-mentioned measures.

That is, the water-based inkjet printing apparatus of the present invention belts the film in the hot-air drying path of the water-based inkjet printing apparatus in which the film to be printed passes through the ink head portion and travels on the hot-air drying path while being applied with a constant tension. The feature is that stable running is realized so that the film does not flutter and meander by being sucked and fixed on the belt of the conveyor and conveyed.

Further, the invention according to claim 2 is characterized in that, in the above-mentioned water-based inkjet printing apparatus, air is sucked from a large number of small holes formed in a belt of a belt conveyor to serve as a suction means.

According to the water-based inkjet printing apparatus of the present invention, it is possible to apply a tension capable of stable running so that the film does not flutter and meander due to hot air during hot air drying. And the product dimensions are within the standard.

The conceptual diagram of the water-based inkjet printing apparatus of this invention. Same as above, plan view of the main part. Same as above, side view of the main part of the comparative example. Same as above, side view of the main part of other comparative examples.

Hereinafter, specific examples of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a conceptual diagram of the water-based inkjet printing apparatus of the present invention. In the figure, reference numeral F is a film to be printed, and the film passes through the ink head portion 10 and travels on the hot air drying path 20 while being applied with a constant tension. Since the ink head portion 10 is a non-contact type, the conditions are the same as the tension in the drying path 20. In the drying path 20, hot air is blown from the nozzle to the ink surface in the drying furnace to dry the ink.

FIG. 3 is a diagram showing the gist of the present invention. Here, by adsorbing and fixing the film F on the belt 31 of the belt conveyor 30 and transporting the film F in the hot air drying path, stable running is realized so that the film does not flutter and meander. Here, as the suction means, a means for sucking air from a large number of small holes formed in the belt 31 of the belt conveyor 30 is adopted.

In this case, the belt 31 of the belt conveyor 30 has a horizontal plane that moves in the horizontal direction, and the film approaching the horizontal plane is sequentially adsorbed and fixed on the belt by suction of air and transferred in the horizontal direction. Release the fixing sequentially with.

F film 10 Ink head 20 Hot air drying path 30 Belt conveyor 31 Belt 41 Rotating drum 42 Guide roller 43 Hot air device 52 Guide roller

Claims (2)

In the hot air drying path of a water-based inkjet printing device, where the film to be printed passes through the ink head portion and travels on the hot air drying path while being given a constant tension, the film is adsorbed and fixed on the belt of the belt conveyor and conveyed. A water-based inkjet printing device characterized by achieving stable running so that the film does not flutter and meander. The water-based inkjet printing apparatus according to claim 1, wherein the suction means is obtained by sucking air from a large number of small holes formed in a belt of a belt conveyor.

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