阅读说明：本技术 等离子体电子束处理喷墨印刷装置 (Plasma electron beam treatment ink jet printing device ) 是由 中岛兴范 明濑拓哉 金城润 盐崎大悟 于 2019-10-11 设计创作，主要内容包括：本发明的目的在于得到一种装置,即使在使用不含有光聚合引发剂的油墨来进行印刷的情况下也可切实地固化,并且可进行不使被印刷基材表面发生改性的印刷,此外,由于在各种颜色的印刷后,通过大气压等离子体使得油墨的点的表面固化,因此可得到固化涂膜的耐受性优异的图像。具体而言,作为解决方法,提供有一种喷墨印刷装置,为多色印刷用喷墨印刷装置,设置有：多色用喷墨用喷嘴,相对于被印刷基材的移动方向而在垂直方向上移动且相对于被印刷基材表面而在平行方向上移动；及等离子体喷出口,在该多色用喷墨用喷嘴的下游,朝向印刷在被印刷基材上的多色的油墨表面,并且,在相对于该喷墨用喷嘴和该等离子体喷出口的下游侧,具有朝向被印刷基材的移动方向的电子束照射部。(The purpose of the present invention is to obtain a device that can reliably cure even when printing is performed using an ink that does not contain a photopolymerization initiator, can perform printing without modifying the surface of a substrate to be printed, and can obtain an image with excellent durability of a cured coating film because the surface of dots of the ink is cured by atmospheric pressure plasma after printing of various colors. Specifically, as a solution, there is provided an inkjet printing apparatus for multicolor printing, comprising: a multi-color inkjet nozzle that moves in a direction perpendicular to a moving direction of the substrate to be printed and moves in a direction parallel to a surface of the substrate to be printed; and a plasma ejection port which is provided downstream of the multicolor ink jet nozzle and faces a surface of the multicolor ink printed on the substrate to be printed, and which has an electron beam irradiation portion facing a moving direction of the substrate to be printed on a downstream side of the multicolor ink jet nozzle and the plasma ejection port.)

1. An inkjet printing apparatus for multicolor printing, comprising:

a multi-color inkjet nozzle that moves in a direction perpendicular to a moving direction of the substrate to be printed and moves in a direction parallel to a surface of the substrate to be printed;

and a plasma discharge port which is located downstream of the multicolor ink jet nozzle and faces a surface of the multicolor ink printed on the substrate to be printed,

further, an electron beam irradiation portion is provided on a downstream side of the multicolor ink jet nozzle and the plasma discharge port, the electron beam irradiation portion being directed in a moving direction of the printing substrate.

2. The inkjet printing apparatus according to claim 1, characterized by having: an ink jet printing unit including a multi-color ink jet nozzle moving in a direction perpendicular to a moving direction of a substrate to be printed and moving in a direction parallel to a surface of the substrate to be printed, and a plasma jet port separated from the ink jet nozzle; and an electron beam irradiation unit on a downstream side of the inkjet printing unit in a moving direction of the substrate to be printed.

3. The inkjet printing apparatus according to claim 2, wherein the head provided with each inkjet nozzle for multicolor has a plasma ejection port on a downstream side of the inkjet nozzle.

4. The inkjet printing apparatus according to claim 2 or 3, wherein the inkjet printing apparatus is for multicolor printing, a head is formed for each of the inkjet nozzles of the respective colors, and a head provided with a plasma ejection port is provided downstream of each head with respect to the inkjet nozzles of the respective colors.

5. The inkjet printing apparatus according to any one of claims 2 to 4, wherein the opening of the plasma ejection port is not directed toward the surface of the substrate to be printed.

6. The inkjet printing apparatus according to any one of claims 2 to 5, wherein the opening of the plasma ejection port is directed in the moving direction of the printing substrate so that the plasma ejected from the plasma ejection port is directed in the moving direction of the printing substrate.

7. The inkjet printing apparatus according to any one of claims 2 to 6, wherein a grounded, negatively charged or positively charged substrate that is in contact with the non-printing surface side of the substrate to be printed and is disposed on the opposite side of the substrate to be printed as viewed from the plasma ejection port is disposed in the inkjet printing portion.

8. The inkjet printing apparatus according to any one of claims 2 to 7, comprising a cap covering the plasma ejection port.

9. The inkjet printing apparatus according to any one of claims 2 to 8, characterized by being provided with:

an ink jet printing unit including an ink jet nozzle that moves in a direction perpendicular to a moving direction of a substrate to be printed and moves in a direction parallel to a surface of the substrate to be printed;

and a cover covering the ink-jet printing portion,

and a plasma ejection port is provided in the cap,

the ink jet printing apparatus further includes an electron beam irradiation unit on a downstream side of the ink jet printing unit in a moving direction of the printing substrate.

10. The inkjet printing apparatus according to claim 9, wherein the opening of the plasma ejection port is not directed toward the surface of the substrate to be printed.

11. The inkjet printing apparatus according to claim 9 or 10, wherein the opening portion of the plasma ejection port is directed in the moving direction of the printing substrate so that the plasma ejected from the plasma ejection port is directed in the moving direction of the printing substrate.

12. The inkjet printing apparatus according to any one of claims 9 to 11, wherein a grounded, negatively charged or positively charged substrate that is in contact with the non-printing surface side of the substrate to be printed and is disposed on the opposite side of the substrate to be printed as viewed from the plasma ejection port is disposed in the inkjet printing portion.

13. The inkjet printing device according to claim 1, characterized in that there are provided:

an ink jet printing unit including a multi-color ink jet nozzle that moves in a direction perpendicular to a moving direction of a substrate to be printed and moves in a direction parallel to a surface of the substrate to be printed;

and a plasma ejection port on a downstream side in a moving direction of the substrate to be printed with respect to the ink jet printing portion,

the plasma discharge port has an electron beam irradiation portion on a downstream side in a moving direction of the printing substrate.

14. The inkjet printing apparatus according to claim 13, wherein the opening of the plasma ejection port is not directed toward the surface of the substrate to be printed.

15. The inkjet printing apparatus according to claim 13 or 14, wherein the opening portion of the plasma ejection port is directed in the moving direction of the printing substrate so that the plasma ejected from the plasma ejection port is directed in the moving direction of the printing substrate.

16. The inkjet printing apparatus according to any one of claims 13 to 15, wherein a grounded, negatively charged or positively charged substrate that is in contact with the non-printing surface side of the substrate to be printed and is in contact with the non-printing surface side of the substrate to be printed is disposed on the opposite side of the substrate to be printed as viewed from the plasma ejection port.

17. The inkjet printing apparatus according to any one of claims 13 to 16, comprising a cap covering the plasma ejection port.

18. An inkjet printing apparatus comprising: an inkjet nozzle provided with a line head type nozzle for printing 2 or more colors of ink; and a plasma ejection port provided on the downstream side in the moving direction of the printing substrate for each nozzle of each color.

19. An inkjet printing apparatus comprising: an inkjet nozzle provided with a line head type nozzle for printing 2 or more colors of ink; and a plasma ejection port on a downstream side in a moving direction of the printing substrate, as viewed from the line head type nozzle, for each of the nozzles for printing 2 or more colors.

Technical Field

The present invention relates to an inkjet printing apparatus.

Background

As described in patent document 1, it is known that the ink on a printing substrate immediately after ink jet printing is irradiated with ultraviolet rays at a low oxygen concentration to form a polymer in the surface layer of the ink, and then irradiated with an electron beam (hereinafter also referred to as "EB") to form a polymer in the deep part, thereby curing the entire ink.

Further, as described in patent document 2, it is known that the ink on the printing substrate immediately after the ink jet printing is subjected to corona discharge treatment in an atmosphere having an oxygen concentration of less than 20000ppm to polymerize the surface layer of the ink, and then irradiated with an electron beam to polymerize the deep part, thereby curing the entire ink.

According to these curing units, although it is not necessary to add a photopolymerization initiator to the ink, an atmosphere having a low oxygen concentration is required.

According to the background art described above, although it is possible to reliably cure an energy ray polymerizable ink containing no photopolymerization initiator, it is necessary to form a region having a particularly low oxygen concentration. In particular, as in the invention described in patent document 1, irradiation with ultraviolet light is sometimes required, and thus it is practically difficult to cure the surface layer of an energy ray-curable ink containing no photopolymerization initiator.

In the case of corona discharge treatment, it is difficult to stably perform the treatment without narrowing the distance between the electrodes to several millimeters or so. In this case, depending on the thickness of the printing paper and the degree of vertical movement of the moving printing paper, the ink may contact the electrodes before the surface of the printed ink is cured, thereby disturbing the printing. Further, depending on the strength of the corona discharge treatment, there is a possibility that the surface of a substrate to be printed such as paper to which no ink is attached is modified.

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-132895

Patent document 2: japanese patent No. 6353618

Disclosure of Invention

The invention aims to provide a device which can reliably cure ink without containing photopolymerization initiator and can perform printing without modifying the surface of a printing substrate.

The present invention has been made to solve the above problems, and as a result, the following inventions have been completed.

1. An inkjet printing apparatus for multicolor printing, comprising: a multi-color inkjet nozzle that moves in a direction perpendicular to a moving direction of the substrate to be printed and moves in a direction parallel to a surface of the substrate to be printed; and a plasma discharge port which is provided downstream of the multicolor ink jet nozzle and faces a surface of the multicolor ink printed on the substrate to be printed, and which is provided downstream of the multicolor ink jet nozzle and the plasma discharge port with an electron beam irradiation portion facing a moving direction of the substrate to be printed.

2. The inkjet printing apparatus according to claim 1, comprising: an ink jet printing unit including a multi-color ink jet nozzle moving in a direction perpendicular to a moving direction of a substrate to be printed and moving in a direction parallel to a surface of the substrate to be printed, and a plasma jet port separated from the ink jet nozzle; and an electron beam irradiation unit on a downstream side of the inkjet printing unit in a moving direction of the substrate to be printed.

3. The inkjet printing apparatus according to claim 2, wherein the head including the respective inkjet nozzles for multicolor has a plasma ejection port on a downstream side of the inkjet nozzles.

4. The inkjet printing apparatus according to claim 2 or 3, wherein the inkjet printing apparatus is for multicolor printing, a head is formed for each of the inkjet nozzles of the respective colors, and a head provided with a plasma ejection port is provided downstream of each head with respect to the inkjet nozzles of the respective colors.

5. The inkjet printing apparatus according to any one of claims 2 to 4, wherein an opening of the plasma ejection port is not directed toward a surface of the substrate to be printed.

6. The inkjet printing apparatus according to any one of claims 2 to 5, wherein the opening of the plasma ejection port is directed in a direction in which the substrate to be printed moves, so that the plasma ejected from the plasma ejection port is directed in a direction in which the substrate to be printed moves.

7. The inkjet printing apparatus according to any one of claims 2 to 6, wherein a substrate that is in contact with the non-printing surface side of the substrate to be printed and is grounded, negatively charged or positively charged is disposed on the inkjet printing portion on the opposite side of the substrate to be printed as viewed from the plasma ejection port.

8. The inkjet printing apparatus according to any one of claims 2 to 7, characterized by having a cap covering the plasma ejection port.

9. The inkjet printing apparatus according to any one of claims 2 to 8, characterized by being provided with: an ink jet printing unit including an ink jet nozzle that moves in a direction perpendicular to a moving direction of a substrate to be printed and moves in a direction parallel to a surface of the substrate to be printed; and a cover which covers the ink jet printing portion, has a plasma ejection port provided therein, and has an electron beam irradiation portion on a downstream side in a moving direction of the substrate to be printed with respect to the ink jet printing portion.

10. The inkjet printing apparatus according to claim 9, wherein the opening of the plasma ejection port does not face the surface direction of the substrate to be printed.

11. The inkjet printing apparatus according to 9 or 10, wherein the opening portion of the plasma ejection port is directed in the moving direction of the printing substrate so that the plasma ejected from the plasma ejection port is directed in the moving direction of the printing substrate.

12. The inkjet printing apparatus according to any one of claims 9 to 11, wherein a substrate that is in contact with the non-printing surface side of the substrate to be printed and is grounded, negatively charged or positively charged is disposed on the inkjet printing portion on the opposite side of the substrate to be printed as viewed from the plasma ejection port.

13. The inkjet printing apparatus according to 1, characterized in that: an ink jet printing unit including a multi-color ink jet nozzle that moves in a direction perpendicular to a moving direction of a substrate to be printed and moves in a direction parallel to a surface of the substrate to be printed; and a plasma ejection port provided with an electron beam irradiation portion on a downstream side in a moving direction of the substrate to be printed with respect to the ink jet printing portion and on a downstream side in the moving direction of the substrate to be printed with respect to the plasma ejection port.

14. The inkjet printing apparatus according to claim 13, wherein the opening of the plasma ejection port does not face the surface direction of the substrate to be printed.

15. The inkjet printing apparatus according to 13 or 14, wherein the opening portion of the plasma ejection port is directed in the moving direction of the printing substrate so that the plasma ejected from the plasma ejection port is directed in the moving direction of the printing substrate.

16. The inkjet printing apparatus according to any one of claims 13 to 15, wherein a substrate that is grounded, negatively charged or positively charged and that is in contact with the non-printing surface side of the substrate to be printed is disposed on the opposite side of the substrate to be printed as viewed from the plasma ejection port.

17. The inkjet printing apparatus according to any one of claims 13 to 16, comprising a cap covering the plasma ejection port.

18. An inkjet printing apparatus comprising: an inkjet nozzle provided with a line head type nozzle for printing 2 or more colors of ink; and a plasma ejection port provided on the downstream side in the moving direction of the printing substrate for each nozzle of each color.

19. An inkjet printing apparatus comprising: an inkjet nozzle provided with a line head type nozzle for printing 2 or more colors of ink; and a plasma ejection port on a downstream side in a moving direction of the printing substrate, as viewed from the line head type nozzle, for each of the nozzles for printing 2 or more colors.

According to the printing apparatus of the present invention, it is possible to obtain an apparatus which can obtain an image having excellent resistance of a cured film by curing the surface of the printed ink by atmospheric pressure plasma after printing 2 or more colors of ink in the inkjet printing and then irradiating Electron Beams (EB) thereto to perform curing, thereby reliably curing both the surface and the inner surface of the dot.

Further, an apparatus is obtained in which, when the surface of the dots of the ink is cured by the atmospheric pressure plasma when the atmospheric pressure plasma is irradiated after each printing of each color and the Electron Beam (EB) is irradiated after the full color printing, even if the dots of the inks of the respective colors overlap, the dots do not bleed, and thus a high-quality image can be obtained, and the surface and the inner surface of the dots are reliably cured, so that an image with good resistance of the cured film can be obtained.

Further, while the ink is actively cured by irradiating the atmospheric pressure plasma, the ink trajectory is not disturbed, or the shape of the printed surface of the temporarily printed ink is not disturbed by the air flow.

Drawings

Fig. 1 is a schematic diagram of a cross section of a remote atmospheric pressure plasma irradiation part.

FIG. 2-1 is a view showing a case where an ink jet nozzle and a plasma jet port are integrally provided.

Fig. 2-2 is a view of the case where the ink jet nozzle and the plasma jet port are integrally provided.

Fig. 2 to 3 are views showing a case where the ink jet nozzle and the plasma jet port are integrally provided.

Fig. 2 to 4 are views showing a case where the ink jet nozzle and the plasma jet port are integrally provided.

FIG. 3-1 is a view showing a case where an ink jet nozzle and a plasma jet port are integrally provided.

Fig. 3-2 is a view of the case where the ink jet nozzle and the plasma jet port are integrally provided.

Fig. 3-3 are views showing the case where the ink jet nozzle and the plasma discharge port are integrally provided.

Fig. 4 is a view in which the ink jet nozzle and the plasma discharge port are provided separately.

Fig. 5 is a view showing only the plasma jet apparatus in which the ink jet nozzle and the plasma jet port are provided separately.

Description of the symbols

10-atmospheric pressure plasma generating means; 11-a pair of electrodes; 12-an insulator; 21-a plasma ejection port; 30-atmospheric pressure plasma processing apparatus for pretreatment; 31-a pair of electrodes; 32-an insulator; 33-a plasma-ejection tube; 34-supporting rolls; 36-a cover; 40-a plasma treatment device; 41-a pair of electrodes; 42-an insulator; 43-plasma jet pipe; 44-support rolls; 45-cover; g-a gas for plasma generation; p-atmospheric pressure plasma; s-a substrate to be printed; n-inkjet nozzles; c-cover; r-supporting roller.

Detailed Description

The apparatus of the present invention will be described in detail below.

(ink jet printing part)

The ink jet printing unit of the present invention may be configured to have various known ink jet nozzles for printing 2 or more colors of ink, or may be configured to have nozzles corresponding to a known ink jet system.

The ink jet printing section is a printing target substrate that is known to be capable of ink jet printing, such as coated paper, plain paper, various resin films, and laminated films having a metal layer or a metal compound layer, and is capable of performing printing using a known principle.

Such an ink jet printing unit may include an ink jet nozzle that moves in a direction perpendicular to the moving direction of the printing substrate and moves in a direction parallel to the surface of the printing substrate, or may include an ink jet nozzle that is fixed to a line head (line head).

In this case, the transported print substrate may be supported by a backup roller rotating at a constant speed, but the backup roller may not be provided.

The inkjet nozzle is constituted by 1 or more nozzles corresponding to 1 or more colors. The printing data is calculated to determine a precise printing portion (a position at which ink is ejected from each nozzle) for each color, and the timing at which ink of each color is ejected from each ink-jet nozzle so that printing can be performed at the printing position, and then ink-jet printing is performed based on the calculation result.

(plasma discharge port (when provided integrally with head of ink jet nozzle))

The plasma ejection port in the present invention is an ejection port for irradiating atmospheric plasma to cure the surface of a dot of ink printed on a substrate to be printed by introducing atmospheric plasma formed by the atmospheric plasma irradiation device 10 shown in fig. 1.

The atmospheric pressure plasma irradiation apparatus 10 shown in fig. 1 uses a plasma processing apparatus, and includes: a discharge space having a blow-out port; and a pair of electrodes 11 for discharge, which are opposed to each other at an interval of about 0.5 to 5.0mm in order to generate an electric field in the discharge space, and which have insulators 12. In this plasma processing apparatus, when the plasma generating gas G is supplied to the discharge space, the pressure in the discharge space is maintained at about atmospheric pressure, a voltage is applied to the pair of electrodes 11 for discharge, and a discharge is generated in the discharge space by exceeding a discharge start voltage, atmospheric pressure plasma P is generated in the discharge space.

In the present invention, the plasma discharge port is used to simultaneously cure a plurality of inks at once after printing the inks of a plurality of colors.

In the case of the multi-color serial head (serial head) system, the plasma ejection port for performing the atmospheric pressure plasma irradiation may be provided on the downstream side of the movement of the substrate to be printed of the same head as the inkjet nozzle, or may be provided separately from the inkjet head so as to be arbitrarily moved, or the like. Further, a plasma ejection port for ejecting atmospheric pressure plasma may be integrally provided in the line head type inkjet nozzle.

In the case of the serial head type and the line head type, the same head may be provided with 1 or more such heads, each having an ink jet nozzle and a plasma ejection port of 2 or more colors. Further, as shown in fig. 2-1, the respective ink-jet nozzles N and the plasma ejection ports 21 for the plurality of colors may be provided on the same head. For example, as shown in fig. 2-2, the plasma ejection port 21 may be provided for each color on the downstream side of the nozzle N for each color of CMYK.

Further, as shown in fig. 2 to 3, a plasma ejection port 21 may be provided downstream of these ink jet nozzles so that the atmospheric pressure plasma P can be used for collective processing after printing by the plurality of ink jet nozzles of CMYK. Although fig. 2 to 3 show a combination of an ink jet nozzle for 4 colors and an atmospheric pressure plasma ejection port located downstream thereof, a combination of an ink jet nozzle for 2 colors and an atmospheric pressure plasma ejection port located downstream thereof may be used. As the color of the ink jet ink provided upstream of 1 plasma ejection port and the characteristics of the ink, 2 or more kinds can be selected.

In addition, the serial head system and the line head system may be provided with the arrangements shown in fig. 2-2 and 2-3.

As seen obliquely from below in fig. 2 to 4, the line head system basically has a structure in which a plurality of ink jet nozzles N and plasma ejection ports 21 are provided above a printing substrate S so as to cross the width direction of the printing substrate.

Further, a cover C covering the plasma ejection port 21 may be provided, and the plasma ejection port may be provided toward the cover so as to increase the concentration of the atmospheric pressure plasma in the atmosphere inside the cover.

The atmospheric pressure plasma used in the present invention includes all gases in which a raw material gas is modified by plasmatization.

When the plasma ejection port itself is provided between or near the nozzles of the respective colors for ink jet printing and moved integrally with these nozzles, an ejection port for irradiating the ink immediately after printing with atmospheric pressure plasma may be used, and it is preferable to irradiate the ink with atmospheric pressure plasma in a range of 1 to 10mm in diameter, and more preferably in a range of 1 to 5mm in diameter.

The inkjet nozzle during printing can also reciprocate relative to the surface of the substrate to be printed. In this case, for each of the groups of multi-color nozzles of the multi-color inkjet nozzles for printing, nozzles for ejecting atmospheric pressure plasma may be provided between the groups. Further, not only the nozzles of the respective colors, but also 1 nozzle for ejecting the atmospheric pressure plasma may be provided on each of the outer sides (outer sides in the width direction of the printing substrate) of the nozzles located at both ends of the arranged nozzles of the respective colors.

Similarly, when the inkjet nozzle is provided in the line head system, a plasma ejection port may be provided so that atmospheric pressure plasma can be ejected to a multicolor ink after printing is performed with the multicolor ink.

Fig. 3-1 is a cross-sectional view of the device of fig. 2-1 viewed in the transverse direction. In fig. 3-1, the plasma ejection port 21 is provided to eject atmospheric pressure plasma in the same direction as the ink jet nozzle N. Even with the apparatus having such a structure, sufficient printing and curing can be achieved. Further, a cap C covering the plasma ejection port 21 may be provided.

However, it is also necessary to prevent the ink cured in the opening of the ink jet nozzle N from being deposited by the atmospheric pressure plasma ejected from the plasma ejection port 21 for ejecting the atmospheric pressure plasma. Therefore, it is necessary to eject the atmospheric pressure plasma from the plasma ejection port 21 for the atmospheric pressure plasma, which is provided as a or B described below, so that the atmospheric pressure plasma ejected from the plasma ejection port 21 ejecting the atmospheric pressure plasma does not contact the ink jet nozzle N while colliding with the uncured ink adhering to the surface of the substrate S to be printed.

A. As shown in fig. 3-2, the plasma ejection port 21 for ejecting the atmospheric pressure plasma is disposed on the upstream side in the moving direction of the printing substrate S with respect to the ink jet nozzle N, and is disposed at a position on the same level as or closer to the ink jet nozzle N with respect to the printing substrate S so as to eject the atmospheric pressure plasma in the same direction as the moving direction of the printing substrate. Further, since the ink jet nozzle N is moved immediately after printing, the plasma ejection port 21 for ejecting the atmospheric pressure plasma can be provided in a direction for ejecting the atmospheric pressure plasma to the ink which is in a positional relationship not opposed to the ink jet nozzle N.

B. As shown in fig. 3 to 3, the plasma ejection port 21 for ejecting the atmospheric pressure plasma is disposed on the downstream side in the moving direction of the printing substrate S with respect to the ink jet nozzle N, and is disposed at a position on the same level as or closer to the ink jet nozzle N with respect to the printing substrate S so as to eject the atmospheric pressure plasma in the direction opposite to the moving direction of the printing substrate S. Further, since the ink jet nozzle N is moved immediately after printing, the plasma ejection port 21 for ejecting the atmospheric pressure plasma can be provided in the direction for ejecting the atmospheric pressure plasma to the ink which is in a positional relationship not opposed to the ink jet nozzle N.

In the case of using the apparatus shown in fig. 3-2 and 3-3, the atmospheric pressure plasma may be irradiated immediately after the ink of any color is attached to the substrate to be printed, in accordance with the movement of the ink jet nozzle N and the discharge of the ink of any color. Further, since the atmospheric pressure plasma does not contact the ink jet nozzles N, the ink cured on the ink jet nozzles N does not adhere or accumulate.

In the case of fig. 3-2 and 3-3, the atmospheric pressure plasma may be made to collide with the inks of the respective colors immediately after the ejection at a timing before the ejection of the ink of the next color.

As a result, even if the ink of the next color is ejected, since at least the surface is cured to some extent by the atmospheric pressure plasma, the ink of the next color does not mix with the ink of the previous color, and the printed outline can be made clearer.

As shown in fig. 2-1 to 2-4, as another inkjet printing apparatus, a full-color inkjet nozzle N for printing may be provided on a print head, and a plurality of plasma ejection ports 21 corresponding to each color may be provided on the same print head. Alternatively, 1 head may be provided with ink jet nozzles of 3 colors, 4 colors, or some other colors, and the plasma jet ports 21 may be provided to cure the inks of these colors. Alternatively, 1 or more such heads are provided, and heads having different ink colors are provided so that full-color ink ejection can be performed as a whole, and the surface of each ink is cured by plasma.

(plasma discharge port (when provided separately from inkjet nozzle))

In the present invention, the plasma ejection port may be provided separately from the head of the inkjet nozzle. At this time, 1 or more heads for printing only 1 color are arranged along the moving direction of the printing target substrate. Alternatively, 1 or more individual plasma jet apparatuses are provided on the downstream side of the multi-color combined head.

In fig. 4, the inkjet nozzle N is a nozzle for ejecting ink of 1 color. In the case of performing multicolor printing, the ink jet nozzles N of the desired number of colors are provided downstream of the arrow indicating the direction of movement of the printing substrate S. Fig. 4 shows only 1 color, and ink jet nozzles N are provided at positions facing the backup roller R provided as needed.

After the ink of the 1 st color is printed by the ink jet nozzles N, the ink is transported to a plasma processing apparatus 40 similar to the plasma processing apparatus shown in fig. 1. Here, a plasma processing apparatus is used which includes a discharge space into which an atmospheric pressure plasma generating gas G is introduced, which has a blow-out port and is formed of an insulator 42, and a pair of electrodes 41 for discharge, which are opposed to each other at an interval of about 0.5 to 5.0mm in order to generate an electric field in the discharge space. In this plasma processing apparatus, when the plasma generating gas G is supplied to the discharge space, the pressure in the discharge space is maintained at about atmospheric pressure, a voltage is applied to the pair of electrodes 41 for discharge, and a discharge is generated in the discharge space by exceeding a discharge start voltage, atmospheric pressure plasma P is generated in the discharge space.

Then, the generated atmospheric pressure plasma P is irradiated on the ink on the printing substrate through the plasma discharge pipe 43. At this time, the cover 45 may be provided so as to increase the concentration of the atmospheric pressure plasma inside the cover 45.

In the case of performing the inkjet printing in the line head system, a plasma processing device may be provided on the downstream side thereof for each head for printing 1 color ink of the line head system, and further, a plasma processing device may be provided on the downstream side thereof for each head for printing 2 colors or more of ink. Further, after printing of the full color ink, a plasma processing device may be provided downstream thereof so as to eject atmospheric pressure plasma to the ink of all colors.

Further, a backup roller 44 may be provided on the opposite side of the plasma discharge pipe 43, and the roller may be grounded or charged oppositely to the atmospheric pressure plasma so that the atmospheric pressure plasma of high concentration is present on the surface of the printing substrate S.

Fig. 5 shows an apparatus for treating ink on a substrate 104 to be printed on a roll 105 by ejecting atmospheric pressure plasma through an atmospheric pressure plasma introduction pipe 103 and a nozzle 102 provided at the tip end thereof. With such a configuration, the plasma jet pipe 43 is fixed, and the plasma jet pipe can form a slit-like nozzle opening portion so that the entire width of the moving printing substrate can be processed.

Alternatively, in fig. 4, the movement of the ink jet nozzles N capable of printing the multi-color ink in the width direction of the substrate to be printed may be delayed by the amount of time for which the substrate to be printed moves from the ink jet nozzles N to the downstream atmospheric pressure plasma processing apparatus 40, and the plasma discharge pipe 43 may be moved in the same manner as the ink jet nozzles N to irradiate the atmospheric pressure plasma with the ink printed by the ink jet nozzles N as an important object.

Although not shown, the configuration is such that, for inks of plural colors, printing of an ink jet ink using the ink jet nozzle N shown in fig. 4 as described above and surface curing of the ink after printing by the plasma treatment device 40 are performed as 1 plasma treatment device and as 1 unit, and the same number of units as the number of colors necessary for the entire printing are provided.

In fig. 4, a plasma treatment apparatus 30 for pretreatment may be provided upstream of the inkjet nozzle N. The surface of the substrate to be printed before printing can be subjected to plasma treatment by the atmospheric pressure plasma treatment apparatus 30 for pretreatment. As a result of the treatment performed by the atmospheric pressure plasma treatment apparatus 30 for pretreatment, plasma species remain on the surface of the printing substrate during printing. Therefore, even when the inkjet printing is performed by the inkjet nozzle N, the charged groups formed by the plasma treatment remain, and the inside of the printing portion can be slightly cured after the printing.

The pretreatment atmospheric pressure plasma processing apparatus 30 has a basic configuration common to the plasma processing apparatus 40, and a plasma processing apparatus including a discharge space into which an atmospheric pressure plasma generating gas G is introduced, which has an ejection port and is formed of an insulator 32, and a pair of electrodes 31 opposed to each other at an interval of about 0.5 to 5.0mm for generating an electric field in the discharge space can be used.

In this plasma processing apparatus, when the plasma generating gas G is supplied to the discharge space, the pressure in the discharge space is maintained at about atmospheric pressure, a voltage is applied to the pair of electrodes 31 for discharge, and a discharge is generated in the discharge space by exceeding a discharge start voltage, atmospheric pressure plasma P is generated in the discharge space.

Then, the generated atmospheric pressure plasma P is irradiated on the ink on the printing substrate through the plasma discharge pipe 33. At this time, the shield 35 may be provided so as to increase the concentration of the atmospheric pressure plasma inside the shield 35.

Further, a backup roller 34 may be provided on the opposite side of the plasma discharge pipe 33, and the backup roller may be grounded or charged oppositely to the atmospheric pressure plasma so that the atmospheric pressure plasma of high concentration is present on the surface of the printing substrate S.

(arrangement of means for earthing or charging)

A support roller or a rod for supporting the non-printing surface of the substrate to be printed may be provided at a position facing the inkjet nozzle and/or the nozzle for ejecting the atmospheric pressure plasma with the substrate to be printed interposed therebetween. Further, by grounding the support roller or rod or previously charging the plasma particles with a polarity opposite to the polarity, the atmospheric pressure plasma can be attracted so that the plasma ejected from the plasma ejection port is redirected to collide with the ink on the substrate to be printed, and electric charges for increasing the plasma density on the surface of the ink on the substrate to be printed can be applied.

Further, a small mask may be provided so as to surround the plasma ejection port and the ink before curing on the printing substrate, and plasma may be ejected into the mask so that the plasma existing in the mask moves toward the printing substrate.

In this way, since the gas flow containing the plasma does not directly collide with the ink, it is possible to reduce the possibility that the gas flow collides with the ink before curing on the printing substrate and spreads out 1 dot or outline of the ink.

Further, by providing such a support roller or rod, the density of atmospheric pressure plasma in the ink jet nozzle and the atmosphere around the nozzle can be reduced at the same time. As a result, the ink cured on the inkjet nozzle can be prevented from adhering and accumulating.

(atmospheric pressure plasma irradiation device)

As a plasma irradiation device for supplying plasma to the plasma ejection port, a remote atmospheric pressure plasma irradiation device can be used. In the plasma, when a high voltage is applied between electrodes in a state of a high energy gas, discharge is generated. Atmospheric pressure plasma is plasma generated under atmospheric pressure, and is generally used for the purpose of hydrophilizing the surface of a substance or the like.

As such a device, for example, a plasma processing device as shown in fig. 1 can be used which includes a discharge space having a blow-out port, and discharge electrodes opposed to each other at an interval of about 0.5 to 5.0mm for generating an electric field in the discharge space. In this plasma processing apparatus, when the discharge space is supplied with the plasma generating gas G, the pressure in the discharge space is maintained at about atmospheric pressure, a voltage is applied to the discharge electrode 11, and a discharge is generated in the discharge space due to the discharge starting voltage being exceeded, plasma is generated in the discharge space.

The atmospheric pressure plasma P is blown out from the ejection port and ejected onto the printing substrate, whereby plasma processing can be performed. Examples of such a plasma irradiation apparatus include plasma treatment apparatuses suitable for use in the RT series and the APT series manufactured by the water-logging chemical industry, and plasma treatment apparatuses provided by the dakusho materials company, and plasma irradiation apparatuses used in the apparatuses described in japanese patent application laid-open nos. 2004-207145, 11-260597, and 3-219082.

Further, as a gas used for the atmospheric pressure plasma, air, oxygen, nitrogen, or the like can be used.

The distance between the electrodes is also dependent on the voltage applied, but a high-frequency, pulse wave, microwave, or other electric field may be applied to the electrodes to generate plasma.

Among them, the pulse wave is preferably applied in consideration that the time required for the rise and fall of the electric field (rise and fall means that the voltage continuously increases or decreases) should be short. In this case, the time required for the rise and fall of the electric field is preferably 10 μ s or less, and more preferably 50ns to 5 μ s.

The electric field intensity generated between the electrodes in the plasma irradiation apparatus may be 1kV/cm or more, preferably 20kV/cm or more and/or 1000kV/cm or less, preferably 300kV/cm or less.

When an electric field is applied by a pulse wave, the frequency is preferably 0.5kHz or more, and may be about 10 to 20MHz, or about 50 to 150 MHz.

The electric power applied between the electrodes may be 40W/cm or less, preferably 30W/cm or less.

In order to obtain a stable plasma discharge, it is preferable that the electrode is not in direct contact with the gas. Therefore, it is preferable to coat the surface of the electrode with an insulating film or the like by any known method. Examples of such an insulating coating include vitreous materials such as quartz and alumina, and ceramic materials. In some cases, a dielectric having a permittivity of 2000 or less, such as barium titanate, silicon oxide, aluminum nitride, silicon nitride, or silicon carbide, may be used.

Such a remote atmospheric pressure plasma irradiating section is constituted by, for example, a unit constituted by an atmospheric pressure plasma irradiating section, a plasma discharge tube and the like and a power supply section in the above-described known apparatus. In this apparatus, in order to uniformly process the object substrate in the width direction, a plurality of portions to which the atmospheric pressure plasma is ejected may be arranged in the width direction, or the nozzle may be shaped like a slit.

Fig. 1 is a schematic sectional view of such a remote atmospheric pressure plasma irradiating section. In fig. 1, a gas G turned into plasma passes between a pair of electrodes 11, one of which is grounded and has a layer such as an insulator 12 formed on the surface thereof, and when the gas G passes through the electrodes, the gas G is made into plasma by a voltage applied between the electrodes. Although the gas flow containing the atmospheric pressure plasma P is shown in fig. 1 as directly colliding with the surface of the printed substrate S to be printed, the atmospheric pressure plasma may not be directly collided.

Further, the atmospheric pressure plasma ejected from the nozzle for ejecting the atmospheric pressure plasma may be irradiated in advance on the upstream side of the ink jet nozzle to the printing surface of the substrate to be printed supplied to the ink jet nozzle. In this case, the atmospheric pressure plasma can be left on the printing surface of the printing substrate for a short time, and the inkjet printing can be performed in the left state. As a result, the ink adhering to the surface of the substrate to be printed can be slightly cured at the adhering portion.

(Electron Beam irradiation part)

The electron beam irradiation part in the present invention has a function of completely curing the entire inside and outside of the ink obtained by curing the surface of the ink of each color by irradiation of atmospheric pressure plasma at the upstream side of the electron beam irradiation part while performing ink jet printing using the plasma ejection port provided integrally with the ink jet nozzle or using the plasma ejection port provided separately from the ink jet nozzle, or after the ink jet printing. By using such an electron beam irradiation unit and simultaneously using a jet atmospheric pressure plasma, the inkjet ink composition can be made to contain no polymerization initiator, no auxiliary agent therefor, or the like. Moreover, the borders of the adjacent colors are not penetrated, so that an image with high contrast can be formed.

As the electron beam generating device constituting the electron beam irradiating section, a known device can be used.

Furthermore, an introducing/irradiating device for irradiating the ink on the printing substrate with the electron beam generated by the electron beam generating device may be provided.

In addition, as an atmosphere when the electron beam is irradiated, an atmosphere of an inert gas such as nitrogen gas or a rare gas is preferably formed in order to smoothly perform curing.

Further, it is necessary to pass the substrate to be printed through the electron beam irradiation section so that the electron beam generated by the electron beam generating device is uniformly irradiated to the ink on the surface of the substrate to be printed. In the electron beam irradiation unit, for example, an electron beam may be irradiated in a curtain shape on the printing surface of the substrate to be printed. The acceleration voltage of the electron beam is preferably 20 to 300kV, although it may be changed in time according to the specific gravity and the film thickness of the ink. The irradiation amount of the electron beam is preferably in the range of 0.1 to 20 Mrad.

By simultaneously irradiating the electron beam irradiation unit with atmospheric pressure plasma, an energy ray-curable inkjet printing ink can be cured. Further, it is not necessary to previously mix a polymerization initiator, a curing agent, a polymerization initiation assistant, and the like in the ink. Even if these components are not incorporated in the ink, the ink can be sufficiently cured.

Examples

A polyethylene terephthalate film having a width of 21cm was fed to a line inkjet printing apparatus at a printing speed of 12m/min, printed using the compositions of examples and comparative examples shown in table 1 below, and cured under the conditions shown in table 1. The amounts of the components in the table are by mass.

Further, the kind of the intercolor plasma curing gas N2 is an example showing that after printing with inkjet printing inks of various colors and full color printing, atmospheric pressure plasma of a gas kind of nitrogen gas was irradiated from a slit having a width of 300mm at a gas flow rate of 30L/min. EB irradiation with 30kGray90kV is a representation of electron beams generated at a voltage of 90kV by irradiating the ink with 30kGray in an atmosphere purified by nitrogen gas after full color printing.

(film coating erasure)

The state of the coating film being wiped off was evaluated by using a fine white cloth (canequ) No. 3 as a rubbing material and making 200 reciprocations of 500g on the surface of the cured coating film by a chemical vibration type rubbing fastness tester (manufactured by seiko scientific refiner, ltd.).

Good: the coating film is not erased.

And (delta): the coating film was slightly wiped off.

X: and (4) erasing the coating film.

(tackiness)

O: the surface of the coating film was touched with a finger, and no tackiness was observed on the surface of the coating film.

X: the surface of the coating film was touched with a finger, and the coating film had tackiness.

Pigment dispersing agent: solsperse 39000 (manufactured by Lubrizol corporation)

PO modified NPGDA: propoxylated and modified (2) tripropylene glycol diacrylate (SR492, manufactured by SARTOMER Co., Ltd.)

EO (3) -modified trimethylolpropane triacrylate: (SR354, manufactured by SARTOMER Co., Ltd.)

TPO: 2, 4, 6-trimethylbenzoyldiphenylphosphine oxide (manufactured by LAMBERTI Co., Ltd.)

Irgacure184 (manufactured by BASF corporation)

DETX: 2, 4-Diethylthioxanthone (manufactured by Lambson)

BYK 333: silicone additive (BYK Chemie Co., Ltd.)

(Table 1)

According to table 1, when the plasma treatment was performed for printing of only one color for each color, the coating film was not wiped off and was not sticky even by wiping with a fine white cloth (canequim) No. 3 according to the examples. On the contrary, when plasma was not irradiated after printing, the coating film was slightly erased.

Further, when plasma is irradiated without EB irradiation, printing is formed in which the coating film is erased and which has stickiness.

(Table 2)

As shown in table 2, according to example 8 in which ink jet printing was performed using 4 colors of ink in this order, and then plasma treatment and EO irradiation were performed in this order for the first time, printing without causing coating film erasure and without tackiness could be achieved.

On the contrary, in comparative example 6 in which plasma irradiation was not performed, coating film erasure occurred, and in comparative example 7 in which EB curing was not performed, coating film erasure occurred and the adhesiveness was not good.

According to the above embodiments, the apparatus of the present invention can realize printing without erasing a coating film and without tackiness.