RU2794286C1 - Method for manufacturing the printable object and the printable object itself - Google Patents

Abstract

FIELD: printing techniques.

SUBSTANCE: printable object improves the quality of an inkjet printed image on a printable object regardless of the resolution of the inkjet printable image. In a method for manufacturing a printable object with an area to be printed on its surface, the surface of the printable area is controlled so that the printable area has a surface energy E (mN/m) of 30 or more and 50 or less. The printable object is selected from a can and a container film.

EFFECT: improving quality of printed image.

10 cl, 2 dwg, 1 tbl

Description

FIELD OF TECHNOLOGY

[0001]

The present invention relates to a method for manufacturing an object to be printed and an object to be printed. In particular, the present invention provides a method for manufacturing a printable object and a printable object that can improve the quality of an inkjet printed image on said printable object regardless of the resolution of the inkjet image.

BACKGROUND OF THE INVENTION

[0002]

In the process of making printed cans, patterns or characters are printed on a metal plate that forms the body of the can, or on the body of the can after the body and bottom of the can are molded in one piece. The printing on the metal plate or can body can be done by plate printing or inkjet printing. Inkjet printing does not require plate making and therefore has lower costs, and also has the advantage that the print design can be changed in a short period of time.

[0003]

As a technology for printing on a printed can using inkjet printing, for example, in FIG. 5 of Patent Document 1 discloses a technology for forming a printed image on a mandrel-mounted seamless can by sequentially dispensing droplets of each ink from inkjet heads corresponding to white (W), yellow (Y), magenta (M), cyan (C) and black ( K) ink.

[0004]

On the other hand, in the case of a printing medium with high water repellency, it is difficult to form a continuous image with a uniform film thickness because the droplets merge with each other, and in order to solve such a problem, a technique is disclosed in which the surface energy of the medium to be discharged and the surface energy of the droplet are set with a certain ratio, as well as the diameter of the landing point and the maximum resolution step distance are set with a certain ratio (see Patent Document 2).

[0005]

Patent Document 1: Japanese Published Unexamined Patent Application No. 2012-86870

Patent Document 2: Japanese Published Unexamined Patent Application No. 4903024

DISCLOSURE OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE PRESENT INVENTION

[0006]

As a matter to be considered in printing, in addition to forming an image with a uniform film thickness as in Patent Document 2, it is also important to prevent deterioration in image quality caused by wetting, spreading or repulsion of the ink forming the printed image. The present invention contributes to improving the quality of printed images in inkjet printing of images printed on an object to be printed selected from a can and a container film.

TROUBLESHOOTING TOOLS

[0007]

As a result of research by the present inventors, the present inventors have found that in order to improve the quality of inkjet printed images on an object to be printed from a can and a container film, regardless of the resolution of the inkjet image, it is important to control the free energy of the area to be printed and located on the surface of the object to be printed within a certain range.

[0008]

The present invention provides a method for manufacturing an object to be printed having an area to be printed on its surface, in which

the object to be printed is selected from a can and a container film, and

the method includes a surface adjustment step of adjusting an area to be printed such that it has a surface energy E (mN/m) of 30 or more and 50 or less.

[0009]

Preferably, in the surface adjustment step, an acquisition layer is formed on at least a portion of the area to be printed, and examples of the acquisition layer preferably comprise a hollow-type acquisition layer and a swelling-type acquisition layer.

Preferably, the acquisition layer contains a base resin selected from the group consisting of acrylic resin, polyester resin, epoxy resin and a mixture of these resins, preferably, the acquisition layer is in a semi-cured state, and preferably, the acquisition layer contains titanium oxide.

Preferably, in the surface adjustment step, at least a portion of the area to be printed is treated with surface modification means.

One embodiment of the invention may include a printing step in which an inkjet printing image is formed on the area to be printed, the object to be printed, which is manufactured by the manufacturing method described above, and in a preferred embodiment of the invention, the printing step includes an image forming step in which an inkjet image on the image carriers, and a transfer step in which an inkjet image formed on the image carriers is transferred to an area to be printed.

[0010]

In another embodiment, the present invention provides a printable object that is a can or container film and has an area to be printed on its surface, wherein the area to be printed has a surface energy E (mN/m) of 30 or more and 50 or less.

Preferably, the area to be printed contains an acquisition layer on its surface, and the acquisition layer comprises titanium oxide.

ADVANTAGEABLE EFFECTS OF THE INVENTION

[0011]

The present invention can improve the quality of an inkjet printed image on an object to be printed, regardless of the resolution of the inkjet image.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]

In FIG. 1 is a schematic diagram illustrating one example of a printing system configuration.

In FIG. 2 is a schematic diagram illustrating another example of a printing system configuration.

DETAILED DESCRIPTION OF THE INVENTION

[0013]

In one embodiment of the present invention, a method is provided for manufacturing an object to be printed and having an area to be printed on its surface, the method including a surface adjustment step of adjusting the area to be printed such that the area to be printed has a surface energy E (mN/m) of 30 or more and 50 or less.

The object to be printed is selected from cans and container films that are susceptible to ink wetting, bleeding or repulsion. Container films are not limited as long as they are used for containers, and may also be used for bags or may be label films.

[0014]

In the present embodiment, when printing an inkjet printable image on a printable object such as a can, in order to improve the quality of the printable image, the surface energy E (mN/m) of the printable area of the printable object is adjusted to the above-described range . When an image is inkjet printed, the diameter of the inkjet ink droplet incident on the area to be printed from the inkjet nozzle may vary depending on the resolution of the inkjet image to be printed, and the present inventors have found that the surface energy of the area to be printed, is important for improving the quality of an image to be printed regardless of the diameter of the incident inkjet ink droplet, namely, regardless of the resolution of the inkjet image.

[0015]

When the surface energy E is less than 30 mN/m, the surface of the area to be printed is less likely to be wetted, causing ink droplets to be excessively repelled, resulting in lower image quality. On the other hand, when the surface energy E is more than 50 mN/m, the surface of the area to be printed is likely to be wetted, causing ink droplets to flow easily, resulting in fuzzy outlines and muddy colors in the image, resulting in poor quality. Images. Preferably, the surface energy E is 35 mN/m or more and 50 mN/m or less.

[0016]

In the present embodiment, the quality of an image to be printed can be improved regardless of the diameter of the incident inkjet ink droplet, namely, regardless of the resolution of the inkjet image, however, the resolution of the inkjet image is generally 300 dpi (dot per inch, dots per inch) or higher, but not limited to this.

The area to be printed, to be adjusted in the surface adjustment step, may be the entire surface of the can or part of the surface of the can. When adjusting a portion of the can surface, it is preferable to adjust the area to be printed where inkjet printing is applied.

[0017]

In the present embodiment, in order to keep the free surface energy E of the area to be printed in the surface adjustment step in the above-described suitable range, for example, a method of providing a receiving layer on at least a portion of the area to be printed can be used, a method of modifying at least as far as the portion of the area to be printed by means for modifying the surface or the like, but not limited to.

[0018]

The take-up layer is a layer that allows inkjet printing on material where inkjet printing is not available or difficult. Typically, there is a swelling-type acquisition layer with a transparent surface and a hollow-type acquisition layer with a whitish surface.

[0019]

The swelling-type acquisition layer is composed of a resin that readily absorbs ink, and the absorbed ink swells in the resin layer and remains in the acquisition layer, which enables printing.

The base resin contained in the swelling-type acquisition layer is not limited as long as the resin readily absorbs ink, and examples thereof include acrylic resin, polyester resin, epoxy resin, vinyl resin, urethane resin, and a mixture of these resins. Preferably, the content of one or more resins selected from acrylic resin, polyester resin, epoxy resin, urethane resin and a mixture of these resins. When preparing a resin mixture, the ratio of each resin is not particularly limited, and a mixture of two types of resins or a mixture of three or more types of resins may be used.

The swelling-type receiving layer may contain a resin other than these, provided that said function is not inhibited.

[0020]

Preferably, the base resin contained in the swelling-type acquisition layer is in a semi-cured state, since the ink absorption and swelling function may deteriorate when the resin is cured.

[0021]

The void-type acquisition layer contains fine inorganic particles to form voids, which allows ink to penetrate into the voids and remain in the acquisition layer to enable printing. Fine inorganic particles contained in the hollow-type receiving layer are not limited as long as these particles can form voids, and examples thereof include silica, alumina, titanium oxide, and boron nitride, the inorganic particles being preferably selected from silica and alumina .

The size of the inorganic particles is not particularly limited, and the average primary particle size is generally 10 nm or more, may be 50 nm or more, and generally 50 μm or less. The average primary particle size may be determined from measurements of the particle size distribution using a laser diffraction/scattering particle size distribution analyzer or the like, and catalog values may also be used for commercially available products.

The thickness of the receiving layer is not particularly limited and can be set by those skilled in the art.

[0022]

The receiving layer may contain a white pigment such as titanium oxide, zinc sulfide, zinc oxide (zinc sublimation) or lithopone (zinc sulfide + barium sulfate), titanium oxide being particularly preferred. Due to the content of white pigment in the acquisition layer, the design pattern layer formed on the acquisition layer can be more clearly recognized.

[0023]

The surface modification method by the surface modification means is not particularly limited, as long as the area to be printed can be modified and the free surface energy E can be set within the above range, and examples thereof include performing surface modification by blowing a burning flame, containing a silicon compound. By blowing with a burning flame containing a silicon compound, a silicon oxide film can be formed on the area to be printed, and a free surface energy E can be obtained that can satisfy the above range.

[0024]

The silicon compound is not particularly limited, and typical examples thereof include a silane compound such as an alkylsilane or alkoxysilane, among others. These silane compounds may contain nitrogen, a halogen such as chlorine, a vinyl group, an amino group, and the like.

As the surface modification means, corona treatment, plasma treatment, glow discharge treatment, arc discharge treatment, and the like can be used.

By adjusting the area to be printed as described above, the effect of improving the adhesion of the ink to the object to be printed is also exhibited.

[0025]

After manufacturing the printable object by the manufacturing method according to the present embodiment, when the printable object is a can, said manufacturing method may include a printing step in which an inkjet image is printed on the can. When the object to be printed is a container film, the method may include a printing step in which an inkjet image is printed on the container film. The printing step is not particularly limited, and the inkjet printing may be performed directly from the inkjet nozzle onto the area to be printed on the surface of the can or container film, and the printing step may be offset printing in which the inkjet image is printed once from ink jet nozzles on the canvas or the like, and then the inkjet image is transferred to the area to be printed. An example of an inkjet printing system to which an embodiment of the present invention can be applied will be described below.

[0026]

In FIG. 1 is a schematic diagram illustrating the configuration of an inkjet printing system 1 forming an inkjet image on an area to be printed on the surface of a can.

When printing on at least the outer surface of the body of the seamless can, a printing system in which the seamless can is rotatably mounted on a mandrel formed on the mandrel wheel and inkjet printing is performed using a printing station mounted along the mandrel wheel has excellent performance. In the inkjet printing system 1, a plurality of mandrels 3 on a mandrel wheel 2 are evenly spaced a plurality of mandrels 3, wherein the mandrel wheel 2 periodically rotates in a clockwise direction while the mandrels 3 rotate at each station in a clockwise direction. Since the jar 4 mounted on the mandrel 3 is carried in the direction of the arrows, images are printed with a plurality of nozzle heads 5 that emit ink corresponding to white (W), yellow (Y), magenta (M), cyan (C), and black ( K) flowers. The order of these colors is not limited, and the ink colors are not limited to this. Therefore, transparent ink can be used. Each printing station can install two inkjet printheads, and by using such a configuration, it can increase the printing speed and resolution by increasing the dot density, and increase the thickness of the ink layer by superimposing dots with high precision, thereby obtaining a printed image with a high-density feel. The type of ink is not particularly limited, and may be a water-based ink or a UV curable ink.

[0027]

The can 4 on which the image has been printed is temporarily dried by the temporary drying unit 6, and then varnish is applied to the surface of the can by the coating apparatus 7, thereby producing a printed can.

In the printing system 1, means for forming an acquisition layer (comprising coating agents and agents for drying the acquisition layer) which form an acquisition layer on the surface of the can, as well as surface modification means for modifying the surface of the can, may be installed. For example, means for forming the receiving layer or means for modifying the surface may be installed upstream of the nozzle head 5.

The means for forming the receiving layer or the means for modifying the surface may be installed in the process prior to entering the printing system 1.

[0028]

In FIG. 2 is a schematic diagram illustrating the configuration of the inkjet printing system 100.

The inkjet printing system 100 includes: a printing station 10, which is an image forming means; the carrier belt 20, which is the image carrier means; a transfer station 30 which is a transfer means; a mandrel wheel 40 and a mandrel 42 which are carriers for the can; station 50 cleaning, which is a means for cleaning; and a top coat station 60 which is a coater. The inkjet printing system 100 may have other configurations than the above.

[0029]

The printing station 10 includes a printing unit 11, wherein the inkjet printhead provided by the printing unit 11 forms an inkjet image 14 (not shown) on the web provided by the carrier belt 20. The printing station 10 may comprise only one printing unit 11 or may contain a plurality of printing blocks 11. By using a plurality of printing blocks 10, high-speed printing and high-pass printing methods can be supported, thereby improving the quality of printed images and forming high-definition inkjet images 14 on the web 23.

[0030]

The inkjet print head provided by the print unit 11 typically includes a plurality of nozzle heads 12 that emit white (W), yellow (Y), magenta (M), cyan (C), and black (K) inks, respectively. The order of these colors is not limited, and the ink colors are not limited to this. Therefore, transparent ink can be used.

[0031]

The printing unit 11 may include a nozzle that emits a primer layer (Pr), in which case the nozzle is positioned downstream of the inkjet printhead to coat the formed inkjet image 14 with a primer layer.

The printing unit 11 may further comprise a UV irradiation unit 13 as curing means. When the ink emitted by the inkjet print head is a UV curable ink, by semi-curing the ink with UV irradiation, ink residues that may be generated when the inkjet image 14 is transferred to the can 41 at the transfer station can be eliminated.

Instead of the UV block 13, this block may contain drying agents as curing agents. The drying means can semi-harden the inkjet image 14 by a method such as blowing warm air onto the inkjet image.

[0032]

The carrier belt 20 is annular and passes through the first roller 21 and the second roller 22, and by rotating in the direction of the arrow shown in the drawing, the inkjet image printed on the web 23 of the carrier belt 20 is transferred to the transfer station 30. The number of webs 23 arranged on carrier belt 20 may be determined according to the circumference of the annular carrier belt and according to the operating speed of the printing system.

[0033]

The carrier belt 20 may be flexible, but when the material is too flexible, the tension of the belt may be insufficient and misalignment may occur during printing or transfer. The material of the carrier belt 20 is not specifically limited.

For purposes of guiding the carrier belt, there may be one or more auxiliary rollers other than the first roller 21 and the second roller 22.

[0034]

The web 23 on which the inkjet image 14 is formed is carried around the periphery of the first roller 21 to the transfer station 30 . On the other hand, a plurality of cans 41 are transferred to the transfer station 30 by means of a mandrel wheel 40. When the end of the web 23 comes into contact with the transfer can 41 or just before it comes into contact with the can 41, the can 41 begins to rotate, and after contact to form ink jet print images on the surface of can 41, the ink jet print image 14 formed on the web 23 is transferred in the circumferential direction of the can 41. The web 23 and the can 41 can be properly aligned, and this alignment can be performed in a known manner.

When the end of the web 23 comes into contact with the transfer can 41, the rotation of the mandrel wheel 40 itself may be stopped, the can 41 on the mandrel 42 may be rotated while the mandrel 40 is stopped, and the ink jet image 14 formed on the can 41 may be transferred to the can. canvas 23. This embodiment of the invention can also be applied to such intermittent printing.

[0035]

After transferring the inkjet image 14 from the web 23 to the surface of the can 41 at the transfer station 30, the cleaning station 50 may clean the surface of the web 23. In the present embodiment, a cleaning station 50 may be provided to flush ink from the web 23, since it is possible that not all ink can be transferred to canvas 23.

[0036]

Cleaning station 50 typically includes a cleaner supply unit 51 that dispenses cleaner onto web 23 and a scraper 52 that wipes ink from web 23. Web 23, the surface of which has been cleaned at cleaning station 50, is guided through a second roller 22 and transferred again. to the printing station 10, where an inkjet image 14 is formed on it.

[0037]

The jar 41 to which the inkjet image 14 has been transferred is transferred to the topcoat station 60 by means of the mandrel 40 . The topcoat station 60 coats the inkjet image 14 transferred to the surface of the can 41. Although varnish is typically used for this coating, other material may be used provided that the material can protect the inkjet image and increase durability, and on inkjet image 14 no varnish can be applied.

[0038]

In the printing system 100, means for forming the receiving layer (comprising means for coating and means for drying the receiving layer) that form the receiving layer on the surface of the can, as well as means for modifying the surface that performs surface modification of the can, can be installed. For example, the means for forming the receiving layer and the means for modifying the surface may be installed upstream of the can carrier transfer station.

Needless to say, the printing system 100 may be used to pre-print cans.

EXAMPLES

[0039]

Specific results of confirming the relationship between the surface energy E (mN/m) of a can and the quality of a printed image during inkjet printing of an image are described below.

A can as an object to be printed was prepared by integrally molding an aluminum can body and a can bottom.

The prepared can was subjected to the treatment shown below in Table 1, and the surface energy E of the can was measured. The surface energy E was measured using a contact goniometer (DropMaster DM500 manufactured by Kyowa Interface Science Co., Ltd.).

[0040]

< Surface energy measurement method >

Two liquids with known surface energy (water and diiodomethane) were used to measure the corresponding contact angles of the surface of the target substrate using a contact goniometer. From the theoretical Kölble-Uy equation, the surface energy of the surface of the target substrate was obtained. The results are shown in Table 1.

[0041]

The image was inkjet printed on the treated can using the printing system 1 of FIG. 1. Printing results (visually observable) are shown in Table 1. Evaluation was performed according to the following evaluation criteria.

<Evaluation Criteria>

A: The printed image was very clear.

B: The outline of the image was a little fuzzy, but the image was recognizable enough.

C: The image was not clear.

[0042]

Table 1 Examples/
Comparative
Examples Surface treatment surface energy
(mN/N) Permission
(dpi) Grade Example 1 Swelling type receiving layer:
acrylic resin 40 600 A Example 2 Swelling type receiving layer:
acrylic resin 50 300 A Example 3 Receiving layer of hollow type:
Silica 38 600 A Example 4 Binder Flame Processing 35 600 A Example 5 Corona Treatment 35 600 A Example 6 flame treatment 35 600 A Comparative
Example 1 Corona treatment 55 300 IN Comparative
Example 2 Corona Treatment 55 600 WITH Comparative
Example 3 No processing 28 300 WITH Comparative
Example 4 No processing 28 600 WITH

[0043]

Based on these results, when the surface energy E of the can was in a specific range, regardless of the resolution, the printed inkjet image became sharper and inkjet image of suitable quality on the surface of the can.

[0044]

The present invention will be described in detail with reference to specific examples, but it will be understood by those skilled in the art that various changes and modifications can be made without deviating from the purpose and scope of the present invention.

LIST OF REFERENCES

[0045]

1 Inkjet printing system

2 Arbor wheel

3 mandrel

4 banks

5 Nozzle head

6 Temporary drying unit

7 Varnishing device

100 Inkjet printing system

10 Printing station

11 Print block

12 Nozzle head

13 UV block

14 Inkjet image

20 Carrier belt

21 First video

22 Second roller

23 Canvas

30 Transfer Station

40 Arbor wheel

41 banks

42 Mandrel

50 Cleaning station

51 Cleaner supply unit

52 Scraper

60 Top coat station.

Claims (25)

1. A method for manufacturing an object to be printed containing an area to be printed on its surface, in which the object to be printed is selected from a can and a film for containers, the method includes a surface adjustment step of adjusting the surface of the area to be printed so that it has a surface energy E (mN/m) of 30 or more and 50 or less, in the step of adjusting the surface, the receiving layer is formed on at least a part of the area to be printed, and the receiving layer is in a semi-cured state. 2. The method for manufacturing an object to be printed according to claim 1, wherein the receiving layer is a hollow-type receiving layer. 3. The method for manufacturing an object to be printed according to claim 1, wherein the receiving layer is a swelling type receiving layer. 4. A method for manufacturing an object to be printed according to claim 1, wherein the receiving layer comprises a base resin selected from the group consisting of acrylic resin, polyester resin, epoxy resin, urethane resin, and a mixture of these resins. 5. A method for manufacturing an object to be printed according to claim 1, wherein the receiving layer comprises titanium oxide. 6. A method for manufacturing an object to be printed containing an area to be printed on its surface, in which the object to be printed is selected from a can and a film for containers, the method includes a surface adjustment step of adjusting the surface of the area to be printed so that it has a surface energy E (mN/m) of 30 or more and 50 or less, in the surface adjustment step, at least a portion of the area to be printed is subjected to surface modification by blowing with a burning flame containing a silicon compound. 7. A method for manufacturing a printed material, including a printing step in which an inkjet print image is formed on the area to be printed, the object to be printed, which is made by the method according to any one of paragraphs. 1-6. 8. The method of manufacturing a printed material according to claim 7, in which printing stage includes an imaging step of forming an inkjet printing image on the image carriers, and a transfer step in which an inkjet image formed on the image carriers is transferred to an area to be printed. 9. The object to be printed, which is a can or film for containers and has an area to be printed on its surface, and the area to be printed has a surface energy E (mN/m) of 30 or more and 50 or less, on at least a part of the area to be printed, a film of silicon oxide is formed. 10. The object to be printed according to claim 9, in which the area to be printed contains a receiving layer on its surface, and the receiving layer contains titanium oxide.

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