JP2008073878A - Method for detecting deviation of droplet hitting point - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for detecting a deviation of a droplet hitting point accurately and simply calculating a positional deviation of the droplet hitting point. <P>SOLUTION: A plurality of ink droplets are respectively delivered from a delivering part to form a plurality of the droplet hitting points on a recording medium. An image composed of the droplet hitting points formed on the recording medium are read as a read image to read in the image, and by performing image processing of the read-in image, the central positions of respective droplet hitting points are calculated as information on the positions of the droplet hitting points. The information on the positions of the droplet hitting points is classified on every delivering part delivering respective droplet hitting points as the classified information on the positions of the droplet hitting points. From the classified information on the positions of the droplet hitting points, an approximate straight line connecting a plurality of the droplet hitting points delivered from one delivering part is calculated on every delivering part by making the inclination of the approximate straight line common. A distance between the approximate straight lines obtained on respective delivering parts is calculated to solve the problem. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a droplet ejection point deviation detection method for detecting a deviation in landing positions of ink droplets ejected from each ejection unit of an image recording apparatus including a plurality of ejection units that eject ink droplets.

As a method for recording an image on a recording medium, there is an ink jet drawing method in which ink droplets are ejected in accordance with an image signal, landed on the recording medium, and an image is recorded.
As an image drawing apparatus using such an ink jet drawing method, an ejection unit (nozzle) that ejects ink droplets is arranged in a line corresponding to the entire area of one side of the recording medium, and the recording medium is ejected by the ejection unit. There is a full-line head type image drawing apparatus that records an image on the entire area of a recording medium by being conveyed in a direction orthogonal to the recording medium.
The full line head type image drawing apparatus can draw an image on the entire area of the recording medium by transporting the recording medium without moving the ejection unit, and can increase the recording speed.

  However, the line head type image drawing apparatus has a problem that streaks and unevenness occur in an image recorded on a recording medium due to variations in manufacturing such as positional deviation of the ejection unit.

  As a method for reducing such streaks and unevenness, Patent Document 1 detects an abnormal nozzle whose droplet flying direction is deviated, and a part of dots ejected from a nozzle adjacent to the abnormal nozzle has a size. An image forming apparatus is described in which large compensation dots are ejected, a gap formed between the dot rows is filled with the compensation dots, and streaks and unevenness due to the gaps are reduced.

  Further, in Cited Document 2, as a dot shift detection method, an image acquisition step for acquiring an electronic image of a dot array formed on an object to be inspected, and image processing of the electronic image makes it possible to perform dot processing on the electronic image. A dot coordinate acquisition step for acquiring the X coordinate and Y coordinate of the center of each dot when the direction substantially parallel to the X axis direction is the X axis direction and the direction orthogonal to the X axis direction is the Y axis direction; A first reference line determination step for determining a first reference line by a least square method based on the X coordinate and the Y coordinate, and a distance between the first reference line and the center of each dot, thereby obtaining a Y-axis direction. Describes a dot deviation detection method including a Y-axis direction deviation amount acquisition step of acquiring information regarding the positional deviation amount of each dot.

Japanese Patent Laid-Open No. 2005-70956 JP 2006-130383 A

Here, for example, in an ink jet drawing apparatus that draws an image with a resolution of 300 dpi (dot per inch) to 650 dpi, the interval between ink droplet ejection positions is 85 to 42.5 μm. That is, as the resolution of the ink jet drawing apparatus increases, the interval between the ink droplet ejection positions becomes shorter.
For this reason, in order to efficiently and accurately reduce streaks and unevenness, it is necessary to accurately detect the positional deviation of the droplet ejection point.

However, Patent Document 1 describes a method of reducing streaks and unevenness at the time of recording, but does not particularly describe a method of calculating a dot ejection point position shift.
Further, in the detection method described in Patent Document 2, in order to accurately calculate the dot interval, it is necessary to read with a high-resolution image reading device and calculate the center position of the dot.
Further, in the detection method described in Patent Document 2, it is difficult to determine the center of a dot when the dot adheres to an adjacent dot due to bleeding on the recording medium or the like, and the interval between droplet ejection positions is reduced. There is also a problem that it cannot be calculated accurately.

  An object of the present invention is to provide a droplet ejection point deviation detection method capable of solving the problems based on the above prior art and calculating the deviation of the droplet ejection point position accurately and easily.

  In order to solve the above-described problems, the present invention is directed to ejecting ink droplets that are ejected from each ejection unit of a recording head in which a plurality of ejection units that eject ink droplets are arranged in a line and land on a recording medium. A droplet ejection point deviation detection method for detecting a positional deviation of dots, wherein a plurality of ink droplets are ejected from the ejection unit to form a plurality of droplet ejection points on the recording medium, and the recording medium An image reading step for reading an image formed by the droplet ejection points formed thereon as a read image, and performing image processing on the read image, whereby the center position of each droplet ejection point is used as droplet ejection point position information. A droplet ejection point position information calculating step, a droplet ejection point position information classification step for classifying the droplet ejection point position information as droplet ejection point position classification information for each ejection unit that ejected each droplet ejection point; For drop position classification information Therefore, an approximate straight line calculation step for calculating an approximate straight line connecting a plurality of droplet ejection points discharged from one discharge unit for each of the discharge units as a common slope of the approximate straight line is obtained for each discharge unit. And an approximate straight line interval calculating step for calculating an interval between the approximate straight lines.

Here, the approximate straight line is preferably calculated by a least square method.
Further, it is preferable that the droplet ejection point is not in contact with a droplet ejection point adjacent in the width direction of the recording medium or in a direction orthogonal to the width direction.
In addition, it is preferable that the droplet ejection point rows are formed in a plurality of different portions in a direction orthogonal to the extending direction of the ejection portion on the recording medium. Alternatively, it is preferable that the rows of droplet ejection points formed on the recording medium are formed at different positions in a direction orthogonal to the arrangement direction of the ejection units, depending on the arrangement position of the ejection units.
Further, it is preferable that after every other droplet ejection point row is formed among the plurality of ejection portions, the droplet ejection point rows of the remaining ejection portions are formed. Alternatively, after ejecting ink droplets from every other ejection portion of the plurality of ejection portions and forming the row of droplet ejection points on the recording medium, ink droplets are ejected from the remaining ejection portions. It is preferable to form a row of droplet ejection points on the recording medium by discharging.

  Further, it is preferable that the droplet ejection point is a droplet ejection point having a size such that adjacent droplet ejection points in the width direction of the recording medium or in the direction orthogonal to the width direction do not contact each other.

  According to the present invention, by calculating the positional deviation of the droplet ejection points at a plurality of droplet ejection points, the interval between the droplet ejection points can be accurately calculated, and the positional deviation of the droplet ejection points is accurately detected. be able to. Further, even when the image of the droplet ejection point is read at a low resolution, the positional deviation of the droplet ejection point can be accurately detected.

  A droplet ejection point deviation detection method according to the present invention will be described in detail based on an embodiment shown in the accompanying drawings.

FIG. 1 is a front view showing a schematic configuration of an ink jet drawing apparatus 10 that uses the droplet ejection point deviation detection method of the present invention, and FIG. 2 shows a suction conveyance belt section 36 and recording of the ink jet drawing apparatus 10 shown in FIG. FIG. 2 is a top view showing the head unit 50. The ink jet drawing apparatus 10 basically transports the recording medium P supplied from the supply unit 12 and the recording medium P supplied from the supply unit 12 while maintaining flatness. A conveyance unit 14, a recording head unit 50 that is disposed opposite to the conveyance unit 14 and draws an image on the recording medium P, an ink storage / loading unit 52 that stores ink to be supplied to the recording head unit 50, and the like. The drawing unit 16, the heating and pressing unit 18 that heats and presses the recording medium P on which an image is drawn, the discharge unit 20 that discharges the recording medium P on which an image is drawn, and the like It has a control unit 22 for controlling, and a misregistration detection unit 24 for reading an image recorded on the recording medium P by the drawing unit 16.

The supply unit 12 includes a magazine 30, a heating drum 32, and a cutter 34.
The magazine 30 stores a roll-shaped recording medium P. At the time of image drawing, the recording medium P is supplied from the magazine 30 to the heating drum 32.
The heating drum 32 is disposed on the downstream side of the magazine 30 in the conveyance path of the recording medium P, and the recording medium P sent out from the magazine 30 is bent in a direction opposite to the direction stored in the magazine 30. Heat.
By heating the recording medium P by the heating drum 32, the winding habit attached to the recording medium P is removed while being stored in the magazine 30. That is, the heating drum 32 performs a decurling process on the recording medium P.
At this time, it is preferable that the heating temperature of the recording medium P is controlled so that the printing surface is weakly curled outward.

The cutter 34 has a fixed blade 34A having a length equal to or larger than the conveyance path width of the recording medium P, and a round blade 34B that moves along the fixed blade 34A. The blade 34B is disposed, and the fixed blade 34A is disposed on the surface facing the conveyance path.
The cutter 34 cuts the recording medium P supplied through the heating drum 32 into a desired size.

  Here, in the present embodiment, a single supply unit magazine is provided, but the present invention is not limited to this, and for example, a plurality of magazines containing recording media having different paper widths, paper qualities, and types may be arranged. Further, a cassette in which a large number of recording media that have been cut in advance to a predetermined length can be used instead of or in addition to the magazine. Further, when only the recording medium P that has been cut in advance to a predetermined length is used as the recording medium P, the above-described heating roller and cutter are not necessarily provided.

  Further, when a plurality of magazines and / or cassettes are used and a plurality of types of recording paper can be used, an information recording body such as a bar code or a wireless tag in which the paper type information is recorded is used as the magazine and / or cassette. Attach and read the information of the information recording medium with a predetermined reader to automatically determine the type of paper to be used, and perform ink ejection control to realize appropriate ink ejection according to the type of paper Preferably it is done.

  The conveyance unit 14 includes an adsorption belt conveyance unit 36, an adsorption chamber 39, a fan 40, a belt cleaning unit 42, and a heating fan 44. The conveyance unit 14 draws a recording medium P that has been decurled by the supply unit 12 and cut to a predetermined length. The image is conveyed to a position, that is, a position where an image is drawn by a drawing unit 16 described later.

The suction belt conveyance unit 36 is disposed on the downstream side of the cutter 34 in the conveyance path of the recording medium P, and includes a roller 37 a, a roller 37 b, and a belt 38.
The belt 38 is an endless belt having a width that is wider than the width of the recording medium P, and is stretched between rollers 37a and 37b. The belt 38 has a plurality of suction holes (not shown) formed on the belt surface.
Further, at least an image drawing (printing) position of the suction belt conveyance unit 36, that is, a nozzle surface of a recording head unit 50 described later of the drawing unit 16, and an image detection position, that is, a sensor surface of a positional deviation detection unit 24 described later. The portion facing the surface is held horizontally (flat) with respect to the nozzle surface and the sensor surface.
At least one of the rollers 37a and 37b around which the belt 38 is wound is connected to a motor (not shown), and the power of the motor is transmitted to the belt 38 through at least one of the rollers 37a and 37b. Is driven in the clockwise direction in FIG. 1, and the recording medium P held on the belt 38 is conveyed from left to right in FIG.

  Here, the conveyance means of the recording medium P is not particularly limited, and a roller / nip conveyance mechanism can be used instead of the suction belt conveyance unit 36. However, when the drawing area is conveyed by the roller / nip, the roller contacts the printing surface immediately after printing, so that there is a problem that the image is likely to spread. Therefore, the printing area does not contact the image surface as in the present embodiment. Adsorption belt conveyance is preferred.

The suction chamber 39 is provided inside the belt 38 at a position facing a nozzle surface of a recording head unit 50 (to be described later) of the drawing unit 16 and a sensor surface of the misregistration detection unit 24. The fan 40 is connected to the suction chamber 39. By sucking the suction chamber 39 with the fan 40 to make it a negative pressure, the recording medium P on the belt 38 is sucked and held on the belt 38.
By adsorbing the recording medium P to the belt, the recording medium P can be stably held.

The belt cleaning unit 42 is disposed on the outer side of the belt 38, that is, on the side facing the ring-shaped outer peripheral surface, and at a position away from the conveyance path of the recording medium P. That is, the belt 38 passes through the drawing unit 16, discharges the recording medium P to a pressure roller 54 described later, and then passes a position facing the belt cleaning unit 42.
The belt cleaning unit 42 removes ink adhering to the belt 38 by performing borderless printing or the like. Examples of the belt cleaning unit 42 include a method of niping a brush / roll, a water absorbing roll, etc., an air blow method of spraying clean air, or a combination thereof. In the case where the cleaning roll is nipped, the cleaning effect is great if the belt linear velocity and the roller linear velocity are changed.

The heating fan 44 is disposed outside the belt 38 and on the upstream side of a recording head unit 50 described later of the drawing unit 16 on the conveyance path of the recording medium P.
The heating fan 44 blows heated air onto the recording medium P before drawing to heat the recording medium P. By heating the recording medium P immediately before drawing, the ink is easily dried after landing.

  The drawing unit 16 includes a recording head unit 50 that draws (prints) an image, and an ink storage / loading unit 52 that supplies ink to the recording head unit 50.

The recording head unit 50 includes recording heads 50K, 50C, 50M, and 50Y, and is disposed to face the surface of the belt 38 on which the recording medium P is placed.
The recording heads 50K, 50C, 50M, and 50Y are inkjet heads that discharge black (K), cyan (C), magenta (M), and yellow (Y) ink from the discharge unit, respectively. The recording heads 50K, 50C, 50M, and 50Y are arranged in the order closer to the heating fan 44 on the downstream side in the transport direction of the recording medium P from the heating fan 44, facing the surface on which the medium P is placed. Yes.
Further, as shown in FIG. 2, the recording heads 50K, 50C, 50M, and 50Y include a plurality of ejection units in a region where the width in the direction orthogonal to the conveyance direction of the recording medium P exceeds the maximum width of the recording medium P to be conveyed. This is a full line type ink jet head in which (nozzles) are arranged in a line. The configuration around the ejection portions of the recording heads 50K, 50C, 50M, and 50Y will be described later.

As in this embodiment, the recording head is a full line type, so that the recording medium P and the drawing unit 16 are relatively once in the direction (sub-scanning direction) orthogonal to the extending direction of the ejection unit of the recording head. The image can be recorded on the entire surface of the recording medium P by being moved (that is, by one scanning). Thereby, it is possible to perform high-speed printing as compared with the shuttle type head in which the recording head reciprocates in the main scanning direction, and productivity can be improved.
Further, a color image can be formed on the recording medium P by ejecting the color inks from the recording heads 50K, 50C, 50M, and 50Y while conveying the recording medium P.

Here, in this embodiment, the recording head unit has a configuration of KCMY standard colors (four colors), but the combination of ink colors and the number of colors is not limited to this embodiment, and for example, light ink, dark ink May be added. More specifically, it is possible to add a recording head that discharges light ink such as light cyan and light magenta.
Further, the recording head unit can be used only as a recording head that discharges K (black) ink, that is, a monochrome recording head unit, and can be used as an image drawing apparatus that draws a monochrome image.

The ink storage / loading unit 52 includes an ink supply tank that stores ink of a color corresponding to each of the recording heads 50K, 50C, 50M, and 50Y.
As the ink supply tank, for example, a system that replenishes ink into a tank from a replenishing port (not shown) or a cartridge system that replaces the entire tank when the ink remaining amount is low can be used.
Each ink supply tank of the ink storage / loading unit 52 communicates with each recording head 50K, 50C, 50M, 50Y via a pipe line (not shown), and supplies ink to each recording head 50K, 50C, 50M, 50Y. To do.

Here, the ink storage / loading unit 52 includes notifying means (display means, warning sound generating means, etc.) for notifying that when the ink remaining amount is low, and a mechanism for preventing erroneous loading between colors. It is preferable to have.
Further, when the ink type is changed according to the intended use, it is preferable to use a cartridge system. In addition, it is preferable that the ink type information is identified by a barcode or the like, and ejection control is performed according to the ink type.

The heating / pressurizing unit 18 includes a post-drying unit 46 and a pressure roller pair 54, and heats and pressurizes the recording medium P on which an image is drawn by the drawing unit 16, thereby drying and fixing the image part.
The post-drying unit 46 is disposed on the downstream side of the recording head unit 50 in the conveyance path of the recording medium P and at a position facing the belt 38. The post-drying unit 46 is a heating fan or the like, blows hot air on the image surface of the recording medium P, and dries the drawn image.
Here, the post-drying section 46 is preferably blown with hot air using a heating fan.
By drying the ink in the image area on the recording medium with the heating fan, the ink can be dried without contacting the image area. Thereby, it is possible to prevent the image drawn on the recording medium P from causing image defects and image stains.

The pressure roller pair 54 is disposed on the downstream side of the post-drying unit 46 in the conveyance path of the recording medium P. The pressure roll pair 54 sandwiches and conveys the recording medium P separated from the belt 38 after passing through the post-drying unit 46.
The pressure roller pair 54 is a means for controlling the glossiness of the image surface, and has a predetermined surface uneven shape while heating the image surface of the recording medium P conveyed by the suction belt conveyance unit 36. The pressure is applied at 54 to transfer the uneven shape onto the image surface.

  In addition, when printing on porous paper with dye-based ink, it is possible to prevent contact with things that cause destruction of dye molecules, such as ozone, by blocking the paper holes by pressurization. The weather resistance of can be improved.

Further, in the inkjet drawing apparatus 10, a cutter (second cutter) 56 is disposed on the downstream side of the pressurizing / heating unit 18 in the conveyance path of the recording medium P.
The cutter 56 includes a fixed blade 56A and a round blade 56B. When a normal image and an image for detecting displacement are formed on the recording medium P, a normal image portion and an image portion for detecting displacement are formed. Separate.

The discharge unit 20 includes a first discharge unit 58A and a second discharge unit 58B, and is disposed on the downstream side of the cutter 56 in the conveyance direction of the recording medium P. The discharge unit 20 discharges the recording medium P on which the image is fixed by the heating / pressurizing unit 18.
Here, in the present embodiment, according to the image recorded on the recording medium P, the sorting unit (not shown) switches the discharging unit for discharging the recording medium P, and the first discharging unit 58A is a recording on which a normal image is drawn. The medium is discharged, and the recording medium on which the image used for detecting the misalignment is drawn is discharged to the second discharge unit 58B.

  Further, it is preferable that the discharge unit 20 is provided with a sorter for collecting images according to orders.

  As in the present embodiment, it is preferable to provide two discharge units so that the discharge unit can be selected according to the purpose. However, the present invention is not limited to this. May be discharged from one discharge section. Moreover, you may provide three or more discharge parts.

  Next, the control unit 22 supplies the recording medium by the supply unit 12, the conveyance unit 14, the drawing unit 16, the heating / pressurizing unit 18, the discharge unit 20, the misregistration detection unit 24, heating, drawing, detection of misregistration, etc. To control. The configuration of the control unit 22 will be described in detail later.

  The misregistration detection unit 24 is disposed at a position facing the outside of the belt 38 and between the recording head unit 50 and the post-drying unit 46. The positional deviation detection unit 24 includes an image sensor (line sensor or the like) for imaging the droplet ejection result of the drawing unit 16 and detects the displacement of the droplet ejection position from the droplet ejection image read by the image sensor.

  The misregistration detection unit 24 of the present embodiment is configured by a line sensor having a light receiving element array wider than the ink ejection width (image recording width) by the recording heads 50K, 50C, 50M, and 50Y. The line sensor includes an R sensor array in which photoelectric conversion elements (pixels) provided with a red (R) color filter are arranged in a line, a G sensor array provided with a green (G) color filter, And a color separation line CCD sensor including a B sensor array provided with a blue (B) color filter. Instead of the line sensor, an area sensor in which the light receiving elements are two-dimensionally arranged can be used.

  The misregistration detection unit 24 reads test patterns drawn by the recording heads 50K, 50C, 50M, and 50Y of the respective colors, detects the droplet ejection point interval of each recording head, and detects the positional deviation of the droplet ejection points. Details of the detection of the positional deviation of the droplet ejection point will be described later.

  Next, the structure of the recording heads 50K, 50C, 50M, and 50Y will be described. Here, since the recording heads 50K, 50C, 50M, and 50Y have the same configuration except for the color of ink to be ejected, the recording head 50K will be described below as a representative.

FIG. 3 is a front view showing an arrangement pattern of the ejection portions 60 of the recording head 50K, and FIG. 4 is an enlarged cross-sectional view showing one ejection portion 60 of the print head 50K.
As shown in FIG. 3, in the recording head 50K, a plurality of ejection units 60 are arranged in a line at regular intervals.

  As shown in FIG. 4, one ejection unit 60 includes an ink chamber unit 61 and an actuator 66. Further, the ink chamber unit 61 is connected to the common flow path 65. The common flow path 65 is connected to the ink chamber units 61 of the plurality of ejection units 60.

The ink chamber unit 61 has a nozzle 62, a pressure chamber 63, and a supply port 64.
The nozzle 62 is an opening that discharges ink droplets, and has one end opened on a surface facing the recording medium P and the other end connected to the pressure chamber 63.
The pressure chamber 63 has a rectangular parallelepiped shape whose plane shape perpendicular to the direction in which the ink droplets are ejected, and both corners on the diagonal are connected to the nozzle 62 and the supply port 64.
The supply port 64 has one end connected to the pressure chamber 63 and the other end communicating with the common flow path 65.

The actuator 66 is disposed on a surface (top surface) opposite to the connection surface of the pressure chamber 63 with the nozzle 62 and the supply port 64, and includes a pressure plate 67 and an individual electrode 68.
The actuator 66 deforms the pressure plate 67 by applying a driving voltage to the individual electrode 68.

An ink discharge method of the discharge unit 60 will be described.
Ink is supplied from the common flow path 65 to the pressure chamber 63 and the nozzle 62 via the common port 64.
When a drive voltage is applied to the individual electrode 68 while the pressure chamber 63 and the nozzle 62 are filled with ink, the pressure plate 67 is deformed, the pressure chamber 63 is pressurized, and ink is ejected from the nozzle 62. The By driving the actuator 66 in this way, ink droplets can be ejected from the nozzle 62.
When ink is ejected, new ink is supplied from the common flow path 65 through the supply port 64 to the pressure chamber 63.

  In addition, the arrangement structure of the discharge part of this invention is not limited to the example of illustration. In this embodiment, a method of ejecting ink droplets by deformation of an actuator 66 typified by a piezo element (piezoelectric element) is adopted. However, the present invention is not limited to this, and a method of ejecting ink is particularly used. The present invention is not limited, and various methods such as a thermal jet method in which bubbles are generated by heating ink with a heating element such as a heater and ink droplets are ejected by the pressure can be applied instead of the piezo method.

Next, the relationship between the recording head unit 50 and the ink storage / loading unit 52 will be described in more detail.
FIG. 5 is a schematic diagram showing a configuration of an ink supply system and a head peripheral portion in the ink jet drawing apparatus 10. Since the relationship between the recording heads 50K, 50C, 50M, and 50Y and the ink storage / loading unit 52 is the same except for the type of ink, the recording head 50K and the ink storage / loading are hereinafter described. Only the relationship with the unit 52 will be described, and the description with respect to the relationship between the recording heads 50C, 50M, and 50Y and the ink storage / loading unit 52 will be omitted.

The ink supply tank 70 is a tank that stores a color corresponding to the recording head 50 </ b> K, that is, black ink, and is disposed inside the ink storage / loading unit 52. The recording head 50K and the ink supply head 70 are connected by a supply pipe.
A filter 72 is provided in the middle of the flow path connecting the ink supply tank 70 and the recording head 50K to remove foreign substances and bubbles. The filter mesh size of the filter 72 is preferably equal to or smaller than the nozzle diameter (generally about 20 μm).

  A sub tank is preferably provided in the vicinity of the recording head 50K or integrally with the recording head 50K. By providing the sub tank, it is possible to obtain a damper effect that prevents fluctuations in the internal pressure of the head, and to improve refill.

  As shown in FIG. 5, the ink jet drawing apparatus 10 includes a cap 74, a suction pump 77, a recovery tank 78, and a recording head as means for preventing drying of the nozzle 62 or preventing increase in ink viscosity near the nozzle. A cleaning blade 76 is provided as a cleaning means for the 50K nozzle surface, that is, the surface where the opening of the nozzle 50 is formed.

  The maintenance unit including the cap 74 and the cleaning blade 76 can be moved relative to the recording head 50 by a moving mechanism (not shown), and is moved from a predetermined retracted position to a maintenance position below the recording head 50K as necessary. .

The cap 74 is disposed at a position facing the recording head 50K in the maintenance position, and is supported so as to be movable up and down relatively with respect to the recording head 50 by an elevator mechanism (not shown).
The cap 74 is raised to a predetermined raised position by an elevating mechanism (not shown) when the power is turned off or during standby for printing, is in close contact with the recording head 50K, and covers the nozzle surface of the recording head 50K with the cap 74.
As described above, the cap 74 covers the nozzle surface of the recording head 50K and seals it, so that the ink in the nozzles is dried and fixed, and the ink solvent evaporates to increase the ink viscosity. Can be prevented.

Further, the cap 74 may be attached to the recording head 50K at the time of maintenance or at regular intervals, and the actuator 66 may be driven to eject ink from the nozzles 62.
In the recording head 50K, if the frequency of use of a specific nozzle 62 is low during drawing or standby, and ink is not ejected for a certain period of time, the ink solvent near the nozzle evaporates and the ink viscosity increases. As a result, ink may not be ejected from the nozzle 62. However, when ink is preliminarily ejected to the cap 74 (purging, idle ejection, spit), the deteriorated ink in the nozzle 62 (near the nozzle whose viscosity has increased) Ink) can be discharged from the nozzle 62. Thereby, it is possible to prevent the nozzle 62 from being clogged with ink, and it is also possible to prevent the nozzle 62 from having a different ink viscosity and change in ejection characteristics. Thereby, ink droplets can be stably discharged.

The suction pump 77 has one end connected to the cap 74 and the other end connected to the recovery tank 78. The cap 74 is attached to the recording head 50K, and the ink in the nozzle 62 is sucked out by sucking with the suction pump 77 in a state where the cap 74 and the recording head 50K are in close contact with each other. Further, the ink sucked by the suction pump 77 is sent to the collection tank 78.
Thus, by sucking ink by the suction pump 77, for example, bubbles are mixed in the ink (in the pressure chamber 63) in the recording head 50, and the ink can be ejected from the nozzle even if the actuator 66 is operated. Even if it is not possible, the ink in the pressure chamber 63 (ink mixed with bubbles) can be removed by suction by sucking the ink with the suction pump 67. That is, the ink droplets can be ejected.
The suction by the suction pump 77 is preferably performed in order to suck out the deteriorated ink whose viscosity has been increased (solidified) even when the ink is initially loaded into the head or when the ink is used after being stopped for a long time.
Further, since the suction by the suction pump 77 is performed on the entire ink in the pressure chamber 63, the amount of ink consumption increases. Accordingly, when the increase in the viscosity of the ink is small, it is preferable to discharge the ink droplets (preliminary discharge) onto the cap 74 described above.

The cleaning blade 76 is formed of an elastic member such as rubber, and is arranged in contact with the nozzle surface of the recording head 50K during maintenance. The cleaning blade 76 is connected to a blade moving mechanism (wiper) (not shown), and is slid on the nozzle surface by the blade moving mechanism. As the cleaning blade 76 slides on the nozzle surface, ink droplets and foreign matter adhering to the nozzle surface are wiped off. That is, the nozzle surface can be cleaned.
In addition, it is preferable to perform preliminary ejection in order to prevent foreign matter from being mixed into the nozzle 62 by the blade when the dirt on the ink ejection surface is cleaned by the blade mechanism.

FIG. 6 is a principal block diagram showing the system configuration of the control unit 22 of the inkjet drawing apparatus 10.
The control unit 22 includes a communication interface 80, a system controller 82, an image memory 84, a motor driver 86, a heater driver 88, a print control unit 90, an image buffer memory 92, a head driver 94, and the like. The conveyance unit 14, the drawing unit 16, the heating / pressurizing unit 18, the discharge unit 20, and the misregistration detection unit 24 control the conveyance, heating, drawing, misregistration detection, and the like of the recording medium P.

  The system controller 82 is a control unit that controls each unit such as the communication interface 80, the image memory 84, the motor driver 86, and the heater driver 88. The system controller 82 includes a central processing unit (CPU) and its peripheral circuits, and performs communication control with the host computer 96, read / write control of the image memory 84, and the like, as well as a transport system motor 98 and heater 99. A control signal for controlling is generated.

  The communication interface 80 receives image data sent from the host computer 96 and sends it to the system controller 82. As the communication interface 80, a serial interface such as USB, IEEE1394, Ethernet (registered trademark), a wireless network, or a parallel interface such as Centronics can be used. Furthermore, a buffer memory for speeding up communication may be installed.

The image memory 84 is a storage unit that temporarily stores an image input via the communication interface 80, and data is read and written through the system controller 82. The image memory 84 is not limited to a memory composed of semiconductor elements, and a magnetic medium such as a hard disk may be used.
Image data sent from the host computer 96 is taken into the inkjet drawing apparatus 10 via the communication interface 80 and stored in the image memory 84 via the system controller 82.

The motor driver 86 is a driver (drive circuit) that drives the motor 98 in accordance with an instruction from the system controller 82.
The heater driver 88 is a driver that drives the heater 99 such as the post-drying unit 46 in accordance with an instruction from the system controller 82.

  The print control unit 90 has a signal processing function for performing various processes and corrections for generating a print control signal from the image data in the image memory 84 according to the control of the system controller 82, and the generated print It is a control unit that supplies a control signal (print data) to the head driver 94. Necessary signal processing is performed in the print control unit 90, and the ejection amount and ejection timing of the ink droplets of the recording head 50 are controlled via the head driver 94 based on the image data. Thereby, a desired dot size and dot arrangement are realized.

  The print control unit 90 includes an image buffer memory 92, and image data, parameters, and other data are temporarily stored in the image buffer memory 92 when image data is processed in the print control unit 90. In FIG. 6, the image buffer memory 92 is shown in a form associated with the print control unit 90, but it can also be used as the image memory 84. Also possible is an aspect in which the print controller 90 and the system controller 82 are integrated and configured with a single processor.

  The head driver 94 drives the actuators of the ejection units of the recording heads 50K, 50C, 50M, and 50Y of the respective colors based on the image (printing) data supplied from the print control unit 90. The head driver 94 may include a feedback control system for keeping the head driving conditions constant.

Next, a method for creating a print or printed matter using the inkjet recording apparatus 10 will be described.
The recording medium P supplied from the magazine 30 of the supply unit 12 is decurled by the heating drum 32 and flattened. Thereafter, the sheet is cut into a predetermined length by the cutter 34 and then supplied to the transport unit 14.
The recording medium P supplied to the conveyance unit 14 is placed on the belt 38 of the suction belt conveyance unit 36 and conveyed along with the rotation of the belt 38.
The recording medium P conveyed by the suction belt conveyance unit 36 passes through a position facing the heating fan 44 and is heated to a predetermined temperature, and then passes through a position facing the recording head unit 50, and has a surface on each surface. The recording head ejects ink droplets in the order of K, C, M, and Y, and an image is formed on the recording medium P. When the recording medium P passes through a position facing the recording head unit 50, the recording medium P is sucked by the suction chamber 39, and the distance between the recording medium P and the recording head unit 50 is constant.
The recording medium P on which the image is formed by the recording head unit 50 is further conveyed by the belt 38, passes through a position facing the post-drying unit 46, and the image unit formed of ink is dried, and the pressure roller After being fixed at 54, it is discharged from the first discharge portion 58A.

  The ink jet drawing apparatus 10 draws (records) an image on the recording medium P in this way, and produces prints and printed matter.

Here, as shown in FIG. 7A, when the ink droplets ejected from the ejection unit during the image drawing by the recording head unit 50 are ejected in a different direction from the ink droplets ejected from the other ejection units. As shown in FIG. 7B, the positions of the ink droplet landing points are deviated, that is, the landing positions of the ink droplets are deviated, resulting in streaks and unevenness in the formed image.
A method for detecting a positional deviation of a droplet ejection point (a droplet ejection point deviation) that causes streaks and unevenness by the inkjet drawing apparatus 10 will be described.

First, an image to be used for detecting a droplet ejection point position deviation is drawn on the recording medium P by the recording heads 50K, 50C, 50M, and 50Y.
In the present embodiment, when a plurality of discharge units arranged in a row are defined as A1, A2, A3,..., An in order from one end to the other end (see FIG. 7), A1, A3, A5, ... and a predetermined number of ink droplets are ejected only from the odd-numbered ejection sections. At this time, the droplet ejection points formed by the ink droplets ejected from one ejection unit are ejected at intervals that do not contact other droplet ejection points. Also, the droplet ejection points of the ink droplets ejected by the ejection part A1 and the ejection part A3 do not contact each other.
After a predetermined number of ink droplets are ejected from the odd-numbered ejection portions, similarly, a predetermined number of ink droplets are ejected from the even-numbered ejection portions A2, A4, A6,. A droplet ejection point is formed on P. Here, the droplet ejection points formed by ejecting a predetermined number of ink droplets from the even-numbered ejection portions are also formed at positions where each droplet ejection point does not contact other droplet ejection points.

FIG. 8 is a top view showing an example of an image (test pattern) used for detecting a droplet ejection point position shift.
In this way, an image is drawn on the recording medium, that is, a droplet ejection point is formed, and ink droplets are ejected from odd-numbered ejection portions onto one recording medium P as shown in FIG. a collection G _a droplet ejection points formed Te, to form the aggregate G _B of droplet ejection points formed by ejecting ink droplets from the ejection portion of the even-numbered. In other words, ink droplets are selectively ejected from a plurality of ejection units without ejecting ink droplets simultaneously from all ejection units, and in a direction orthogonal to the extending direction (arrangement direction) of the ejection units on the recording medium. Then, a row of droplet ejection points (a droplet ejection point sequence) is formed in a plurality of different portions. That is, the rows of droplet ejection points formed on the recording medium are formed at different positions in the direction orthogonal to the arrangement direction of the ejection units, according to the arrangement positions of the ejection units. Here, the extending direction of the discharge part is the direction in which the plurality of discharge parts are arranged, that is, the direction in which the line connecting the discharge parts extends, in other words, the longitudinal direction of the recording head (inkjet head), In this embodiment, it is the width direction of the recording medium.

  Next, the image formed on the recording medium P is read by the misalignment detection unit 24. That is, each droplet ejection point is read by the position deviation detection unit 24.

FIG. 9A is a schematic diagram showing one droplet ejection point of an image (read image) read by the misregistration detection unit 24. FIG. 9B shows the image data shown in FIG. It is a schematic diagram which shows an example converted into a value. Here, in FIGS. 9A and 9B, each of the squares is one pixel. By increasing the reading pixel density, that is, the reading resolution, each cell can be made smaller, and one droplet ejection point can be read more finely.
The positional deviation detection unit 24 binarizes the read droplet ejection point image (see FIG. 9A) for each pixel as shown in FIG. 9B. In other words, it is determined whether or not the ink density of each pixel, that is, the density of the read image is equal to or higher than a threshold value. The pixel has no ink component. In other words, each read pixel has only two values with or without an ink component.

Next, binarization is performed, and only the pixels that form the droplet ejection point, that is, pixels with an ink density within a certain level or more are taken out, and the center coordinates of each pixel are averaged to obtain the center coordinates of the droplet ejection point. Is calculated. Here, the coordinate axis of the coordinates to be calculated is the direction perpendicular to the extending direction of the positional deviation detection unit 24, that is, the direction perpendicular to the conveyance direction of the recording medium P, and the direction perpendicular to the X axis, that is, the recording medium P. The direction parallel to the transport direction is the Y-axis direction, and an arbitrary point is the origin. This coordinate axis is a common coordinate axis for all droplet ejection points.
Specifically, as shown in FIG. 10A, the center of the X coordinate of the droplet ejection point can be calculated by averaging the centers in the X axis direction of each pixel, and the Y coordinate of the droplet ejection point. As shown in FIG. 10B, the center of can be calculated by averaging the centers in the Y-axis direction of each pixel.

  Next, the calculated center coordinates (droplet point position information) of each droplet point are classified by discharge unit. Here, the relationship between the droplet ejection point and the ejection unit that ejected the droplet is that each droplet ejection point is ejected according to the relative relationship such as the positional relationship in the recording medium conveyance direction and the direction perpendicular thereto. It can classify | categorize for every discharged part.

Next, with respect to the droplet ejection points classified for each ejection unit, the center coordinates of a plurality of droplet ejection points ejected from one ejection unit are linearly approximated using the least square method, and each ejection point as shown in FIG. An approximate straight line connecting the droplet ejection points for each part is calculated.
Specifically, when the number of the ejection unit is m, the approximate straight line of the droplet ejection point formed by the ejection unit _m is expressed as y = ax + b _m based on the coordinate axis described above.
Note that a is the slope of the approximate line, and b _m is the intercept of the approximate line. The slope a of the approximate line is calculated as a slope common to all approximate lines. Accordingly, the approximate straight lines are all parallel to each other.
The slope a and the intercept b _m are calculated by the following formulas (1) and (2).

ここで、Ｍは、全吐出部数であり、ｍは、吐出部の番号であり、Ｎｍは、直線を算出ために吐出部ｍにより描画した打滴点数であり、（ｘ_ｍｎ，ｙ_ｍｎ）は、吐出部ｍが描画したｎ番目の打滴点の中心座標である。

Here, M is the total number of ejection units, m is the number of ejection units, Nm is the number of droplet ejection points drawn by the ejection unit m to calculate a straight line, and (x _mn , y _mn ) is , The center coordinates of the nth droplet ejection point drawn by the discharge unit m.

Next, the interval between the approximate lines is calculated from the calculated approximate lines a and b _m . When the distance between the approximate line and the approximate line of the discharge portion m + 1 of the discharge portion m was d _m, d _m is calculated by the following equation (3).

  As described above, by calculating the interval between the droplet ejection points, it is possible to calculate the positional deviation of the droplet ejection points of the ink droplets ejected from each ejection unit.

Thus, by calculating an approximate straight line from a plurality of droplet ejection points for each discharge unit and comparing the calculated approximate straight lines with each other to calculate a droplet ejection point interval, it is possible to accurately calculate the droplet ejection points. In addition, it is possible to accurately obtain information (ejection information on the droplet flying direction) of the ejection portion where the position of the droplet ejection point that causes streaks, unevenness, and the like is shifted.
In addition, the number of droplet ejection points read for each ejection unit can be arbitrarily increased, and various settings can be made according to the required accuracy. Furthermore, even when a reading device with low reading accuracy, that is, a low resolution is used for reading the droplet ejection point, the accuracy can be increased by increasing the number of droplet ejection points to be read.
Further, if the droplet ejection points are drawn on the same recording medium, it is not necessary to form the droplet ejection points of all the ejection units on the same straight line in the extending direction of the ejection unit (direction orthogonal to the conveyance direction of the recording medium). For example, even when the droplet ejection points are formed at a plurality of different portions in the direction orthogonal to the extending direction of the ejection portion on the recording medium (the conveyance direction of the recording medium), the interval between the droplet ejection points is preferably calculated. be able to.
In addition, by shifting the position of the droplet ejection point in the direction parallel to the transport direction, even when the arrangement density of the ejection parts is high and adjacent droplet ejection points overlap, the droplet ejection point is not reduced, etc. The drop point interval can be calculated.

Here, the number of droplet ejection points to be read for each ejection unit, the size of the droplet ejection point (resolution of the image formed by the recording head), and the resolution of the image reading device (line sensor) of the positional deviation detection unit The relationship of [number of droplet ejection points drawn by one ejection unit] × [resolution of droplet ejection points (resolution of an image rendered by the recording head, minimum interval)] / [reading resolution of the image reading apparatus] (Minimum reading interval)]> 100 is preferably satisfied.
By satisfying the above formula, it is possible to accurately calculate the interval between the droplet ejection points, and it is possible to accurately calculate the positional deviation of the droplet ejection points.

In the present embodiment, the droplet ejection points formed on the recording medium P, a collection G _A droplet ejection points formed by the odd discharge portion, the droplet ejection points formed by an even number of ejection portions Although divided into aggregate G _B, the present invention is not limited thereto, be formed a row of droplet ejection points in three, be formed a row of droplet ejection points in four Good.

Further, if the adjacent droplet ejection points are not in contact with each other on the recording medium, that is, if the droplet ejection point and the adjacent droplet ejection point are not in contact with each other, the droplet ejection point formed by all the ejection units is set in the conveyance direction of the recording medium. They may be formed on the same straight line in the direction perpendicular to.
For example, if the size of the ejected ink droplet can be adjusted, that is, if the size of the droplet ejection point can be adjusted, the droplet ejection point can be reduced by reducing the droplet ejection point by reducing the ejected ink droplet. You may make it not contact an adjacent droplet ejection point.
Thus, the center of each droplet ejection point can be accurately calculated by not bringing the droplet ejection point adjacent to the droplet ejection point into contact.

Further, in this embodiment, an image is formed in which droplet ejection points are continuously formed only by an odd number of ejection portions and droplet ejection points are continuously formed only by an even number of ejection portions, but the present invention is not limited to this. Alternatively, an image in which droplet ejection points are alternately formed by odd-numbered ejection portions and even-numbered ejection portions may be used.
In this way, even when the adjacent droplet ejection points of each ejection unit are formed apart from each other, that is, in the direction orthogonal to the reference direction, it is formed by another ejection unit between the droplet ejection points formed by the same ejection unit. Even if the formed droplet ejection points are formed, an approximate straight line for each ejection unit can be calculated in the same manner, and the droplet ejection point interval can be calculated (detected).

  Further, in order to accurately calculate the droplet ejection points between all the ejection units, it is preferable to form all the droplet ejection points on one recording medium, but the present invention is not limited to this, and droplet ejection is performed on a plurality of recording media. A dot formation may be performed to calculate the droplet ejection point interval. In this case, ink droplets are always ejected from a part of the ejection units to form a standard droplet ejection point, and the corresponding droplet ejection points between the respective recording media can be used. The positional deviation can be calculated.

  Further, the method of calculating the approximate line is not limited to the least square method, and various calculation methods can be used. For example, the slope (α) and intercept (β) of the approximate line may be calculated by averaging the slope (a) and intercept (b) of the straight line (y = ax + b) calculated from two adjacent points. More specifically, the number of droplet ejection points formed by one ejection unit is N, the x coordinate of the i th point of the droplet ejection point is xi, and the y coordinate of the i th point of the droplet ejection point is As yi, an approximate straight line can be calculated using the following formula (4).

  Further, the calculation method of the center position of each droplet ejection point is not limited to the above method, and various methods can be used. As an example, as shown in FIG. 12, it is assumed that the outer shape of the droplet ejection point 600 is substantially equal to a circle, a plurality of locations on the edge of the droplet ejection point 600 are detected as detection points 610, and a plurality of detected detection points 610 are detected. There is a method in which an approximate circle 620 is obtained based on this, and the center point 630 of the approximate circle 620 is calculated as the center of the droplet ejection point.

  Further, in the present embodiment, the ink jet drawing apparatus that fixes the image on the recording medium P by heating and pressurizing the image recorded on the recording medium P has been described, but the present invention is not limited to this, and will be described later. Although described in detail with specific examples, the active energy curable ink is used as the ink, the active energy curable ink is ejected from the recording head, and an image of the active energy curable ink is formed on the recording medium P. An ink jet drawing apparatus that irradiates a light beam, cures an image, and fixes the image on a recording medium can also be used.

  In the above-described embodiment, the recording head of the drawing unit is a full-line head type in which the ejection units are arranged in a line in a line. However, the recording head is not limited to a single-line arrangement, and as shown in FIG. 640 may be arranged in a staggered manner by shifting a plurality of rows of ejection portions by a certain pitch. In this manner, by arranging the ejection units 60 in a staggered manner and forming one row of droplet ejection points with a plurality of rows of ejection units, it is possible to form an image with higher resolution.

  Further, in this embodiment, the misalignment detection unit is provided inside the ink jet drawing apparatus. However, the present invention is not limited to this, and the misalignment detection unit is not provided inside the ink jet drawing apparatus. A misregistration detection apparatus that reads a recording medium on which an image is drawn by an image reading apparatus and detects misregistration of a droplet ejection point by the same method as described above can also be used.

Further, as shown in FIG. 14, even when the ink jet drawing device 650, the arithmetic device 660, and the image reading device 670 are separate devices, it is possible to detect the positional deviation of the droplet ejection point.
The ink jet drawing apparatus 650 is an apparatus that forms an image on the recording medium P using a full line head type ink jet head, and the arithmetic unit 660 calculates an ejection signal for forming an image on the recording medium from input image data. The image reading device 670 is a device that reads an image formed on the recording medium P by the ink jet drawing device 650. Here, the ejection signal refers to an ejection unit to be driven among a plurality of ejection units of the recording head according to the conveyance of the recording medium P, a timing for ejecting ink droplets from the ejection unit, an amount of ejected droplets, and the like. For example, in the case of a piezo-type ink jet head, it is a signal for controlling the height, length, timing, etc. of the voltage applied to the actuator for each ejection unit.

In the case of such an apparatus configuration, first, image data for detecting a droplet ejection point position deviation is input to the arithmetic unit 660. Specifically, image data of an image as shown in FIG. 8 is input.
The arithmetic device 660 calculates an ejection signal from the input image data and sends it to the inkjet drawing device. The ink jet drawing device 650 forms an image on the recording medium P based on the ejection signal calculated by the arithmetic device 660. In this manner, an image for detecting a droplet ejection point position deviation is formed. In addition, an image for detecting the position deviation of the droplet ejection point is formed on a single recording medium as shown in FIG. 8 at a position where a plurality of droplet ejection points are not in contact with each other for each ejection unit. It is an image.

Next, the image reading device 670 reads an image for detecting a droplet ejection point position shift. The image reading device 670 calculates the positional deviation (interval) of the droplet ejection point from the read image, and sends the calculated information to the arithmetic device 660. The method for calculating the droplet ejection point from the read image data is the same as described above.
The arithmetic device 660 calculates a correction value based on the acquired positional information on the droplet ejection point.
Thereafter, when normal image data is input, the arithmetic device 660 calculates an ejection signal from the input image data while taking into account the calculated correction value.
The ink jet drawing apparatus 650 forms an image on the recording medium P based on the acquired ejection signal.
In this way, an ejection signal is calculated in consideration of the positional deviation of the droplet ejection point, and an image without streaks or unevenness can be drawn by drawing the image with the ink jet drawing apparatus.

  Here, in the present embodiment, the calculation device, the inkjet drawing device, and the image reading device are divided into three, but the present invention is not limited to this, and the calculation device and the inkjet drawing device may be a single device. . In addition, the image reading device only reads the image for detecting the droplet ejection point position deviation, and the calculation device calculates the position of the droplet ejection point from the read image data, calculates the position deviation (interval) of the droplet ejection point, In addition, the correspondence between the droplet ejection point and the ejection portion of the recording head may be calculated.

Hereinafter, together with specific examples, a method for detecting a droplet ejection point position shift will be described in more detail.
FIG. 15A is a schematic top view showing an image (test pattern) used for detecting a droplet ejection point position shift used in this example, and FIG. 15B is a more detailed view of FIG. 15A. It is a schematic top view shown in.
In this embodiment, the ink jet recording apparatus and the image reading apparatus that reads the recording medium on which the droplet ejection point for detecting the position shift is formed are separate apparatuses.
The recording head unit of the ink jet recording apparatus has 2544 ejection portions designed so that droplet ejection points are formed at intervals of 42.3 μm, and ejects UV curable (ultraviolet curable) ink. In this embodiment, the positional deviation of the droplet ejection point of only the recording head that discharges ultraviolet curable cyan ink in the recording head unit is detected.
A general-purpose scanner having a resolution of 4800 dpi (measurement interval = 5.29 μm) was used as the image reading apparatus.
Further, coated paper (manufactured by EPSON, photographic paper (glossy), KA4100PSK) was used as the recording medium P.

Next, the recording medium P was conveyed at 400 mm / s, ink droplets were ejected from the recording head, and 70 droplet ejection points were created on the recording medium P for each ejection unit.
Specifically, the discharge units are divided into four groups 4k-3, 4k-2, 4k-1, 4k (k = 1, 2, 3,...) Based on the numbers of the discharge units, Ink droplets are ejected from the ejection unit with the ejection unit number of 4k-3, and 70 droplet ejection points are formed for each ejection unit. Thereafter, the ink is ejected from the ejection unit with the ejection unit number of 4k-2. 70 droplet ejection points are formed for each ejection unit, and thereafter, similarly, ejection is performed for the ejection unit with the ejection unit number 4k-1 and the ejection unit with the ejection unit number 4k. 70 droplet ejection points are formed for each part.
That is, as shown in FIGS. 15A and 15B, the interval between the droplet ejection points in the width direction of the recording medium P is 169.2 μm on the recording medium P, and the recording medium P is further conveyed. Four lattices (G1, G2, G3, G4) are formed corresponding to the four groups of ejection units, with the droplet ejection point spacing in the direction parallel to the direction being 169.2. Further, these four gratings are formed at positions shifted by 42.3 μm from the adjacent gratings in the width direction of the recording medium P.

In this way, the recording medium P on which the droplet ejection points were created was read by the above-described reader having a resolution of 4800 dpi, and the interval between the droplet ejection points was calculated.
The calculated results are shown in FIG.
As shown in FIG. 16, it can be seen that the deviation between the interval between the droplet ejection points and the design value can be accurately calculated.

  Next, an example in which an ink jet drawing apparatus using the droplet ejection point deviation detection method of the present invention is used in a digital label printing apparatus will be described.

  17 is a schematic configuration diagram illustrating an example of the digital label printing apparatus 100, and FIG. 18 is a longitudinal sectional view of a label printing recording medium used in the digital label printing apparatus 100 illustrated in FIG. ) Is a cross-sectional view showing the main part of the recording medium having irregularities on the image surface, and FIG. 19B is a cross-sectional view showing the main part of the recording medium pressed without smoothing. (C) is sectional drawing which shows the principal part of the recording medium which smoothed the unevenness | corrugation by the smoothing part, and was foil-pressed.

The digital label printing apparatus 100 according to the present embodiment is an ultraviolet curable inkjet digital label printing apparatus using an ultraviolet curable ink which is an active energy curable ink, and has a foil stamping unit and is a label printing apparatus capable of foil stamp printing. is there.
Here, foil press printing is a method of pressing a foil such as a gold foil, a silver foil, a color foil, etc. on a book cover or spine against a mating member with a heated letterpress to heat-press (foil press) the foil. Also called a hot stamp.
Further, as shown in FIG. 18, the recording medium P of the present embodiment has a two-sheet structure in which an adhesive sheet 180 having a back surface coated with an adhesive 180a is superposed on a release paper 182 as a mount.

As shown in FIG. 17, the digital label printing apparatus 100 basically includes a transport unit 110, a drawing unit 112, a misalignment detection unit 114, a smoothing unit 116, a foil pressing unit 118, and a label removing unit 120. Have Although not shown, the drawing unit 112, the misregistration detection unit 114, the smoothing unit 116, the foil pressing unit 118, and the label removing unit 120 are connected to the control unit, and various operations are performed by the control unit. Is controlled.
Here, the conveyance unit 110 conveys a continuous paper-like label printing recording medium P (hereinafter referred to as “recording medium P”) in a certain direction (from left to right in FIG. 17), and is a drawing unit. 112, the misregistration detection unit 114, the smoothing unit 116, the foil pressing unit 118, and the label removing unit 120 are arranged in the order of the conveyance direction of the recording medium P, that is, from the upstream to the downstream direction, the drawing unit 112, the misregistration detection unit 114, and the smoothing. The part 116, the foil pressing part 118, and the label removing part 120 are arranged in this order.

The conveyance unit 110 includes a supply roll 122, conveyance roller pairs 124, 126, 128, 130, and 132, and a product winding unit 134.
A continuous paper-like label printing recording medium P is wound around the supply roll 122 in a roll shape. The conveyance roller pairs 124, 126, 128, 130, and 132 are driven to rotate by a conveyance motor (not shown), and the recording medium P is fed out from the supply roll 122 to draw the drawing unit 112, the misalignment detection unit 114, the smoothing unit 116, and the foil presser It conveys to the part 118 and the label removal part 120 one by one.
The product take-up unit 134 is arranged on the most downstream side in the conveyance direction of the recording medium P, and is conveyed by the conveyance roll pairs 124, 126, 128, 130, 132, and the drawing unit 112, the misalignment detection unit 114, and the smoothing unit 116. The recording medium P that has passed through the foil pressing unit 118 and the label removing unit 120 is wound up.

The drawing unit 112 includes a recording head unit 135 and an ultraviolet irradiation unit 138.
The recording head unit 135 has recording heads (inkjet heads) 136Y, 136M, 136C, and 136K, similar to the recording head unit 50 described above, and a position facing the conveyance path of the recording medium P, that is, the front end of the ink ejection unit It is arranged to face the recording medium P.

The recording heads 136Y, 136M, 136C, and 136K are arranged in the order of the recording head 136Y, the recording head 136M, the recording head 136C, and the recording head 136K from upstream to downstream in the conveyance direction of the recording medium P.
The recording heads 136Y, 136M, 136C, and 136K are full-line and piezo-type heads as in the recording head of the recording head unit 50 shown in FIG. Connected to the department.
A color image can be formed on the recording medium P by ejecting the respective color inks from the recording heads 136Y, 136M, 136C, and 136K while the recording medium P is conveyed by the conveying unit 110.

In this embodiment, the recording head is not limited to the piezo element (piezoelectric element) method, but instead of the piezo method, the ink is heated by a heating element such as a heater to generate bubbles, and the ink droplets are generated by the pressure. Various methods such as a flying thermal jet method can be applied.
The ink ejected from the recording head of this embodiment is an ultraviolet curable ink.

The ultraviolet irradiation unit 138 is an active energy irradiation light source, and is arranged on the downstream side of each recording head 136Y, 136M, 136C, 136K corresponding to each recording head 136Y, 136M, 136C, 136K. As the ultraviolet irradiation unit 138, various ultraviolet light sources such as a metal halide lamp, a high-pressure mercury lamp, and a UVLED can be used.
The ultraviolet ray irradiation unit 138 passes the recording heads 136Y, 136M, 136C, and 136K, and irradiates the recording medium P on which the image is formed with ultraviolet rays. That is, the ultraviolet irradiation unit 138 gives the ink on the recording medium the energy that the ink ejected from the recording head and placed on the recording medium P is immediately cured, and cures the ink on the recording medium P.

Here, the ultraviolet irradiation unit 138 is set to a position or a configuration in which the emitted ultraviolet light is irradiated to the ink on the recording medium P and is not irradiated to the ink ejection ports of the recording heads 136Y, 136M, 136C, and 136K. Is preferred. In this way, by preventing the ink ejection port from being irradiated with ultraviolet rays, it is possible to prevent the ink from being cured at the ejection port.
Further, it is preferable to perform a light reflection preventing treatment (for example, a matte black treatment) on each part in the vicinity of the ultraviolet irradiation unit 138.

  The misregistration detection unit 114 has the same configuration as the misregistration detection unit 24 shown in FIG. 1, and calculates the interval between the ejection units of the ejection units that the recording heads 136Y, 136M, 136C, and 136K each have a plurality of. It is. Since the configuration of the misregistration detection unit and the method for calculating the interval between the ejection units are the same, detailed description thereof is omitted.

  Next, the smoothing unit 116 is arranged on the downstream side of the drawing unit in the conveyance direction of the recording medium P, and is transparent on the surface of the recording medium P with an active energy (ultraviolet light in this embodiment) curable liquid (hereinafter referred to as “active energy”). A varnish coater 142 which is a transparent liquid supply means for supplying a “curable transparent liquid” or simply “transparent liquid”) and a flat pressure member 146 which presses and smoothes a later-described foil donation range of the recording medium P. And an ultraviolet irradiation unit 148 which is an active energy irradiation unit for irradiating and curing the transparent liquid with active energy.

The varnish coater 142 includes a pair of application rollers 144 and 145.
The coating rolls 144 and 145 have a transparent liquid attached (impregnated) on the surface, and are disposed at positions where the recording medium P conveyed by the conveying unit 110 is sandwiched. The coating rolls 144 and 145 rotate in response to (synchronously with) the movement of the recording medium P while sandwiching the recording medium P, so that the surface of the recording medium P on which the image is formed through the drawing unit 112. A transparent liquid is applied to (the surface on which the image is formed).

  Here, the transparent liquid applied by the varnish coater 142 is an active energy curable transparent liquid that can be cured by ultraviolet irradiation, and includes at least a polymerizable compound and a photoinitiator as main components, for example, a cationic polymerization composition. , Radical polymerization compositions, aqueous compositions and the like. Details will be described later.

The flat pressure member 146 is arranged on the downstream side of the varnish coater 142 in the conveyance direction of the recording medium P so that the smooth surface 146a faces the recording medium P and is movable in the vertical direction (arrow direction shown in the figure). Has been.
The flat pressure member 146 moves in the vertical direction, contacts the recording medium P, presses at least the surface (image surface) of the foil donation range of the recording medium P with the smooth surface 146a, and presses the surface of the recording medium P. The ink that is ejected and forms an image is smoothed.
The smooth surface 146a has at least an area larger than the foil donation range.

  The ultraviolet irradiation unit 148 is disposed on the downstream side of the flat pressure member 146 in the conveyance direction of the recording medium P. The ultraviolet irradiation unit 148 irradiates the recording medium P with active energy (ultraviolet rays in the present embodiment) to cure the smoothed transparent liquid applied to the surface of the recording medium P. As the ultraviolet irradiation unit 148, for example, a metal highland lamp, a high-pressure mercury lamp, a UV-LED, or the like can be used.

  The varnish coater 142 and the ultraviolet irradiation unit 148 are not essential devices for smoothing the foil donation range of the recording medium P, but can be installed because a smooth surface can be obtained by applying a transparent liquid. preferable.

The foil pressing unit 118 includes a foil supply roll 150, a foil winding roll 152, rollers 154 and 156, a foil 158, and a hot stamp plate 160, and the smoothing unit 116 in the transport direction of the recording medium P It is arranged downstream.
The foil supply roll 150 and the foil take-up roll 152 are arranged at a predetermined interval. Further, the roller 154 and the roller 156 are separated from each other by a predetermined distance, the surface connecting the roller 154 and the roller 156 is parallel to the surface of the recording medium P, and recording is performed more than the foil supply roll 150 and the foil winding roll 152. It is arranged at a position close to the medium P. The rollers 154 and 156 are arranged at positions very close to the recording medium P.
The foil 158 is supplied from the foil supply roll 150, wound around the roller 154 and the roller 156, and then stretched around the foil winding roll 152. Here, the foil 158 between the roller 154 and the roller 156 is parallel to the recording medium P.

The hot stamp plate (letter plate) 160 is disposed between the roller 154 and the roller 156 at a position facing the recording medium P via the foil 158. The hot stamp plate 160 is provided with a relief plate portion 160a that contacts and presses the foil 158 on the surface on the recording medium P side, and is formed of zinc, brass, or the like. Further, the hot stamp plate 160 has a heating device (not shown) for heating the relief plate portion 160a and a moving mechanism for moving the hot stamp plate 160 in a direction approaching or separating from the recording medium P.
The hot stamping plate 160 heat-presses the foil 158 on the recording medium P according to the shape of the relief printing portion 160a by bringing the heated relief printing portion 160a into contact with the recording medium P via the foil 158 and pressing it.

Here, in the present embodiment, a transport buffer is provided between the smoothing unit 116 and the foil pressing unit 118.
By providing the conveyance buffer, it is possible to absorb the slack of the continuous paper-like label printing recording medium P caused by the difference in the conveyance speed between the smoothing unit 116 and the foil pressing unit 118, and the label can be manufactured efficiently. it can.

  The label removing unit 120 is disposed downstream of the ultraviolet irradiation unit 164 in the conveyance direction of the recording medium P, and applies an active energy curable transparent liquid (ultraviolet curable transparent liquid in the present embodiment) to the image surface. Thus, a varnish coater 162 and an ultraviolet irradiation unit 164 for improving gloss, a die cutter 166 for making a label-shaped cut in the continuous paper-like recording medium P, and a residue removing part 172 which is an unnecessary part peeling part are included.

The varnish coater 162 is disposed on the downstream side of the foil pressing unit 118 in the conveyance direction of the recording medium P.
The varnish coater 162 has a pair of coating rolls (impregnated) with an ultraviolet curable transparent liquid attached to the surface thereof, and supports the movement of the recording medium P (synchronously) while sandwiching the recording medium P. By rotating, the ultraviolet curable transparent liquid is applied to the surface (the surface on which the image is formed) of the recording medium P pressed with foil.
The ultraviolet irradiation unit 164 is disposed on the downstream side of the varnish coater 162 in the conveyance direction of the recording medium P. The ultraviolet irradiation unit 164 irradiates the recording medium P with active energy (ultraviolet rays in the present embodiment) to cure the ultraviolet curable transparent liquid applied to the surface of the recording medium P.
By applying and curing an ultraviolet curable transparent liquid on the surface of the recording medium P, the image surface of the recording medium P can be given gloss, and the image quality can be improved.

As shown in FIG. 18, the die cutter 166 has a desired label-shaped cut 180 b only in the printed continuous paper-like label printing recording medium P adhesive sheet 180, and the conveyance direction of the recording medium P 2, a cylinder cutter 168 disposed on the downstream side of the ultraviolet irradiation unit 164 and disposed on the image surface side of the recording medium P, and a receiving roller 170 disposed on the opposite side of the cylinder cutter 168 across the recording medium P. Have.
The cylinder cutter 168 includes a cylindrical cylinder 168a and a plurality of cutting blades 168b wound around the cylindrical surface of the cylinder 168a and formed in a label shape.

  The die cutter 166 oscillates and rotates intermittently in synchronization with the conveyance speed of the recording medium P while holding the recording medium P between the cylinder cutter 168 and the receiving roller 170, so that the cutting blade 168 b adheres to the recording medium P. Only the sheet 180 is cut in a label shape.

  Here, the reason why the die cutter 166 swings and rotates intermittently is to solve the problem caused by the discrepancy between the circumferential length of the cylindrical surface of the cylinder 168a and the required length of the cutting blade 168b. That is, when the die cutter 166 is continuously rotated to make the label-shaped cut 180b, the recording medium P corresponding to the portion without the cutting blade 168b of the cylinder cutter 168 is also fed idle, and the recording medium P is wasted. However, by rotating and rotating the die cutter 166, the cuts 180b can be continuously formed, and the waste of the recording medium P can be eliminated.

The scrap removing part 172 peels off an unnecessary part (peripheral part of the label L) of the pressure-sensitive adhesive sheet 1 that does not become the label (product) L from the release paper 182 and winds it up.
The recording medium P in which the unnecessary portion is wound, that is, the recording medium P in which only the label L is attached to the release paper 182 is wound around the product winding portion 134 to become a product.

Next, a method for creating a label by the digital label printing apparatus 100 will be described.
As shown in FIG. 17, the recording medium P sent out from the supply roll 122 wound in a roll shape is conveyed to the drawing unit 112 by the conveyance roller pairs 124 and 126.

The recording heads 136Y, 136M, 136C, and 136K discharge ink droplets of ultraviolet curable ink onto the recording medium P that passes through the facing position based on control by a control unit (not shown). The recording medium P on which the ink has been ejected is further conveyed, passes through a position facing the ultraviolet irradiation unit 138, is irradiated with ultraviolet rays, and the ink is cured.
That is, when the recording medium P passes through the positions facing the recording heads 136Y, 136M, 136C, and 136K, ink droplets are ejected from the recording heads 136Y, 136M, 136C, and 136K toward the recording medium P, and then the ultraviolet rays are discharged. Ultraviolet rays are irradiated from the irradiation unit 138, and the ink is cured. As a result, an image is formed on the surface of the recording medium P.

  The recording medium P on which the image has been recorded is conveyed to the smoothing unit 116, and the varnish coater 142 has a thickness of 5 so as to cover the entire image 184 formed on the recording medium P as shown in FIG. A transparent liquid 186 of about ˜30 μm (dry film thickness) is applied.

  The recording medium P coated with the transparent liquid 186 is conveyed to a position facing the flat pressure member 146. The flat pressure member 146 moves in a direction approaching the recording medium P, and presses the recording medium P with a smooth surface 146a. By pressing the recording medium P with the smooth surface 146a, the ink on the recording medium P is crushed. Thereby, the ink (image) on the recording medium P becomes smooth. Here, the area of the smooth surface 146a of the flat pressure member 146 is larger than the foil supply range.

  The recording medium P with the smoothed image is conveyed to the foil pressing unit 118 via the conveyance buffer. The recording medium P conveyed to the foil pressing unit 118 is pressed by the hot stamp plate 160 through the foil 158. On the surface of the recording medium P pressed by the hot stamp plate 160, a foil 158 is heat-pressed according to the shape of the relief plate portion 160a of the hot stamp plate 160.

  The recording medium P on which the foil 158 has been heat-pressed, that is, pressed with foil, is transported to the label removing unit 120, applied with an ultraviolet curable transparent liquid by the varnish coater 162, and then irradiated with ultraviolet rays by the ultraviolet irradiation unit 164. The applied ultraviolet curable transparent liquid is cured.

The recording medium P on which the ultraviolet curable transparent liquid is cured is conveyed to the die cutter 166, and the cut 180b is formed in the shape of the label L only on the adhesive sheet 180 by the cylinder cutter 168 and the receiving roller 170.
At this time, as described above, the die cutter 166 inserts the cut line 180b in the shape of the label L while swinging intermittently, so that the cut line 180b can be formed continuously, and the recording medium P is wasted. Will not occur.
Thereafter, unnecessary portions other than the label L of the pressure-sensitive adhesive sheet 180 of the recording medium P are peeled off from the release paper 182 and taken up by the residue removing portion 172. The recording medium P in a state where only the label L is stuck on the release paper 182 is wound around the product winding unit 134 to become a product.
A label is created as described above.

Further, since the digital label printing apparatus 100 of the present embodiment also uses a full-line type inkjet head as a recording head, the ink droplet ejection points ejected from each ejection unit are the same as in the inkjet recording apparatus 10. If it slips, it causes streaks and unevenness.
On the other hand, in the digital label printing apparatus 100, the position deviation detection unit 114 is used to detect the ejection point deviation by the same method as that of the inkjet recording apparatus 10 described above, so that the ejection point can be accurately and easily performed. Can be detected, and by performing correction based on the detected positional deviation, a high-quality image free from streaks and unevenness can be formed.
Note that the method for detecting the position deviation of the droplet ejection point, that is, the method for forming the image for detection, the method for detecting the droplet ejection point, and the method for calculating the interval are the same as those described above for the digital label printing apparatus of the present embodiment. Since it is the same method as the case of the apparatus 10, the description thereof is omitted.

  Here, as shown in FIG. 19A, the image surface of the recording medium P is three-dimensionally swelled by overlapping the cured inks 184 of multiple colors. The rising height of the ink varies depending on the ink absorbability of the recording medium P (higher as the absorbency is lower), but is approximately 10 μm per color, and when one multicolor ink is used. May be approximately 40 μm. The image surface of the recording medium P is uneven. The unevenness greatly affects the adhesion between the foil 158 and the recording medium P (more specifically, the ink 184 on the recording medium P) when foil is pressed onto the image surface of the recording medium P.

  That is, as shown in FIG. 19B, when foil pressing is performed on an image surface in which the foil donation range is not smoothed (in other words, the ultraviolet curable ink is discharged and cured in the drawing unit 112), The foil 158 is heated and pressure-bonded only on the concave and convex peak portions, and is not pressed on the valley portions. That is, the degree of adhesion between the foil 158 and the recording medium P is low, and is easily peeled off.

  On the other hand, in the present embodiment, the foil donation range is smoothed in advance by the flat pressure member 146 and then pressed onto the recording medium P. As a result, as shown in FIG. 19C, the foil 158 can be heat-bonded to a smooth surface having a large area, and the foil pressing with high adhesion between the recording medium P and the foil 158 can be performed. .

That is, according to the digital label printing apparatus 100 of the present embodiment, a smoothing unit that smoothes at least the ink 184 and the transparent liquid 186 in the foil donation range on the recording medium P by the flat pressure member 146 upstream of the foil pressing unit 118. By disposing 116, the foil 158 can be provided and pressed in a range smoothed by the smoothing unit 116.
Thereby, the adhesiveness of the recording medium P and foil 158 can be improved, and favorable foil stamp printing can be performed. Moreover, since it is smoothed by the flat pressure member 146, it can be smoothed in a short time, and productivity can be improved.

  Further, the smoothing unit 116 is active in a transparent liquid supply means (varnish coater) 142 that supplies a transparent active energy curable liquid on the image surface on the recording medium P, and an active energy curable liquid (transparent liquid) after the supply. Active energy irradiation means (ultraviolet irradiation unit) 148 for irradiating energy is provided, and the image surface is covered with a transparent active energy curable liquid and smoothed, so that even if the image surface has large irregularities, A foil donating range with good flatness can be formed.

  Furthermore, by using a varnish coater as the transparent liquid supply means, the transparent liquid 186 can be stably applied to the surface of the recording medium P on which an uneven image is formed with a simple and inexpensive mechanism.

  Here, the formation of the film of the ultraviolet curable transparent liquid by the varnish coater 162 and the ultraviolet irradiation unit 164 is not necessarily required because it is intended to give the image surface a gloss and obtain a high-quality image. When not required, it can be set not to form a film of an ultraviolet curable transparent liquid.

  Further, the position of the transport buffer is not particularly limited, and may be arranged between the drawing unit 112 and the smoothing unit 116 as in the digital label printing apparatus 101 shown in FIG. Similarly, the transfer buffer may be arranged between the drawing unit 112 and the smoothing unit 116 in the following embodiments.

Next, another example of the digital label printing apparatus will be described with reference to FIG.
The digital label printing apparatus 200 shown in FIG. 21 has the same configuration as the digital label printing apparatus 100 shown in FIG. 17 except for the smoothing unit 216. Therefore, the same reference numerals are given to the same constituent elements in both, and the detailed description thereof will be omitted, and the following will focus on the points peculiar to the digital label printing apparatus 200.

  The smoothing unit 216 of the digital label printing apparatus 200 has a configuration in which the varnish coater 142 and the ultraviolet irradiation unit 148 are removed from the smoothing unit 116 of the digital label printing apparatus 100 shown in FIG. That is, the smoothing unit 216 includes only the flat pressure member 146.

Therefore, in the digital label printing apparatus 200, the image surface formed by the drawing unit 112 is pressed and smoothed by the flat pressure member 146 as it is (without applying a transparent liquid).
As described above, by covering the entire image surface with the transparent liquid, it is possible to further smooth the surface and increase the degree of adhesion between the recording medium P and the foil 158. However, as in the present embodiment, the flat pressure member 146 alone, after smoothing the image surface of the recording medium P, even when the foil 158 is pressed, the image surface can be smoothed, and the adhesion between the recording medium P and the foil 158 is improved. Foil stamp printing can be performed.

FIG. 22 is a schematic configuration diagram illustrating another example of the digital label printing apparatus.
The digital label printing apparatus 300 shown in FIG. 22 has the same configuration as the digital label printing apparatus 100 shown in FIG. 17 except for the smoothing unit 316. Therefore, the same reference numerals are given to the same constituent elements in both, and detailed description thereof will be omitted. Hereinafter, points unique to the digital label printing apparatus 300 will be mainly described.

  The smoothing unit 316 includes an inkjet head 344 that supplies a transparent activation energy curable liquid (transparent liquid) to the surface of the recording medium P, and a flat pressure member 146 that presses and smoothes the foil supply range of the recording medium P. And an ultraviolet irradiation unit 148 that irradiates the recording medium P with ultraviolet rays to cure the transparent liquid. Here, the flat pressure member 146 and the ultraviolet irradiation unit 148 are the same as the flat pressure member 146 and the ultraviolet irradiation unit 148 of the digital label printing apparatus 100 shown in FIG.

The inkjet head 344 discharges the transparent liquid onto the surface of the recording medium P on which the image is formed by the drawing unit 112, and the unevenness of the image formed by curing the ultraviolet curable ink on the recording medium is formed into a film of the transparent liquid. Cover with.
Here, as the ink jet head 344, the various types of ink jet heads described as the recording head of the drawing unit 122, such as a piezo method and a thermal jet method, can be used.
The recording medium P on which the transparent liquid film is formed is then pressed by the smooth surface 146a of the flat pressure member 146, irradiated with ultraviolet rays by the ultraviolet irradiation unit 148, and the transparent liquid is cured.

  Thus, by using an inkjet head as the transparent liquid supply means, an optimal amount of the transparent liquid is supplied to the image surface of the uneven recording medium P while finely controlling the supply amount (application amount) of the transparent liquid. be able to. That is, the thickness of the transparent liquid can be adjusted according to the position of the recording medium P, and the smoothness of the recording medium P can be further improved.

FIG. 23 is a schematic configuration diagram illustrating another example of the digital label printing apparatus.
The digital label printing apparatus 400 shown in FIG. 23 has the same configuration as the digital label printing apparatus 100 shown in FIG. 17 except that the varnish coater 162 and the ultraviolet irradiation unit 164 are not arranged and the smoothing unit 416 is arranged. It is. Therefore, the same reference numerals are given to the same constituent elements in both, and the detailed description thereof will be omitted. Hereinafter, points unique to the digital label printing apparatus 400 will be mainly described.

  The smoothing unit 416 includes a varnish coater 142 that supplies a transparent active energy curable liquid (transparent liquid) to the surface of the recording medium P, and a flat pressure member 446 that presses and smoothes the foil supply range of the recording medium P. And an ultraviolet irradiation unit 448 that cures the transparent liquid by irradiating the recording medium P with ultraviolet rays. Here, the varnish coater 142 is the same as the varnish coater 142 of the digital label printing apparatus 100 shown in FIG.

The flat pressure member 446 is disposed on the downstream side of the varnish coater 142 in the conveyance direction of the recording medium P, has a transparent portion 446b that can transmit ultraviolet rays in the vicinity of the center, and the flat surface 446a having a smooth surface on the recording medium P side. Is formed.
The ultraviolet irradiation unit 448 is disposed at a position facing the recording medium P via the transparent portion 446 b of the flat pressure member 446. That is, the transparent portion 446b of the flat pressure member is disposed between the ultraviolet irradiation unit 448 and the recording medium P.
The ultraviolet rays irradiated from the ultraviolet irradiation section 448 are transmitted through the transparent section 446b and irradiated onto the recording medium P.

In the digital label printing apparatus 400, a transparent liquid is applied to the recording medium P on which an image is formed by the drawing unit 112 by the varnish coater 142.
The recording medium P coated with the transparent liquid is further conveyed and pressed by the smooth surface 446a of the flat pressure member 446, while the ultraviolet light emitted from the ultraviolet irradiation unit 448 passes through the transparent part 446b and is recorded on the recording medium. The transparent liquid on the recording medium P is cured by irradiating P.

According to the digital label printing apparatus 400, the surface of the recording medium P in contact with the flat pressure member 446 can be irradiated with ultraviolet rays. That is, the transparent liquid in contact with the flat pressure member 446 can be cured.
In this way, the transparent liquid can be cured in a state of being blocked from oxygen in the air by irradiating with ultraviolet rays while being pressed by the flat pressure member 446.

  Since the transparent liquid can be cured in a state where the contact with air is blocked, even if the transparent liquid is a radical active energy curable liquid that causes polymerization inhibition due to oxygen in the atmosphere, the polymerization inhibition is suppressed. Therefore, it is possible to use an inexpensive light source (ultraviolet irradiation unit) with low light intensity. Further, the curing of the transparent liquid and the smoothing of the surface of the recording medium P by the flat pressure member 446 can be performed at the same time, and the productivity can be improved.

  In the present embodiment, the varnish coater 162 and the ultraviolet irradiation unit 164 of the label removing unit 120 are not provided, but the varnish coater 162 and the ultraviolet irradiation unit 164 may be arranged as necessary in the same manner as in the above embodiment.

FIG. 24 is a schematic configuration diagram illustrating another example of the digital label printing apparatus.
In the digital label printing apparatus 500 shown in FIG. 24, the configuration of each part is the same except that the drawing unit 112 and the smoothing unit 116, the foil pressing unit 118, and the label removing unit 120 are independent individual devices. Basically, it has the same configuration as the digital label printing apparatus 200 shown in FIG. Therefore, the same reference numerals are given to the same components in both, and the detailed description thereof will be omitted, and the following will focus on the points peculiar to the digital label printing apparatus 500.

  As shown in FIG. 24, the digital label printing apparatus 500 includes a pre-processing device 501 having a drawing unit 112 and a smoothing unit 116, and a post-processing device 502 having a foil pressing unit 118 and a label removing unit 120.

Next, a characteristic part of the digital label printing apparatus 500 will be described together with a method for creating a label by the digital label printing apparatus 500.
The recording medium P is installed on the first supply roll 510 of the pretreatment device 501 and is conveyed to the drawing unit 112 by the conveyance rolls 124 and 126 and the like. An image is formed on the surface of the recording medium P conveyed to the drawing unit 112 by the recording heads 136Y, 136M, 136C, and 136K and the ultraviolet irradiation unit 138. The recording medium P on which the image is formed is pressed by the flat pressure member 146 of the smoothing unit 216, the image on the recording medium P is crushed, and the foil donation range is smoothed. The smoothed recording medium P is wound up on the collecting roll 512.

  The recording medium P on which the image has been formed and smoothed, that is, the recording medium P wound up on the collection roll 512, is installed on the second supply roll 514 of the post-processing device 502. The recording medium P installed on the second supply roll 514 is conveyed to the foil pressing unit 118 by the conveyance rolls 128, 130, and 132.

The recording medium P conveyed to the foil pressing unit 118 is pressed by the hot stamp plate 160 through the foil 158. Thereby, the foil 158 is thermocompression bonded onto the recording medium P in accordance with the shape of the hot stamp plate 160 (the relief plate portion 160a).
Also in the present embodiment, the foil 158 can be thermocompression bonded to a smooth surface of a large area on the recording medium P because the foil donation range is smoothed by the smoothing unit 216.
Thereby, the recording medium P and the foil 158 can be heat-bonded with a high degree of adhesion, and the foil 158 can be made difficult to peel from the recording medium P.

The foil-pushed recording medium P is transported to the label removing unit 120, and an ultraviolet curable transparent liquid is applied by the varnish coater 162. Thereafter, the applied ultraviolet curable transparent liquid is cured by being irradiated with ultraviolet rays from the ultraviolet irradiation unit 164. Is done.
Thereafter, the recording medium P is cut only by the die cutter 166 on the adhesive sheet corresponding to the shape of the label L, and further, the waste part 172 peels off unnecessary portions of the recording medium P adhesive sheet from the release paper. Taken. On the other hand, the recording medium P in which the unnecessary portion is wound and only the label portion of the pressure-sensitive adhesive sheet and the release paper are wound is wound around the product winding portion 134 to become a product.

In this way, the digital label printing device is a separate device as a pre-processing device and a post-treatment device, so that the pre-processing step of label L printing and image surface smoothing, foil stamping, transparent liquid application (glossy surface) The post-processing steps such as formation), scoring, and scrap removal can be performed as separate operations, and post-processing of various types of labels L can be performed collectively.
In general, the time required for printing is often slower than the time required for post-processing such as scrap removal, and one post-processing device 502 can handle a plurality of pre-processing devices 501. Efficient processing is possible.

  In the above-described embodiment, the digital label printing apparatus has been described as an ultraviolet curable inkjet head label printing machine. However, the present invention is not limited to this, and can be applied to any type of printing apparatus capable of foil stamp printing. Have the same effect.

Here, the recording medium is not particularly limited, and ordinary non-coated paper, paper such as coated paper, various non-absorbent resin materials used for so-called soft packaging, or a resin film obtained by forming it into a film shape is used. Examples of various plastic films include PET film, OPS film, OPP film, ONy film, PVC film, PE film, and TAC film. In addition, examples of the plastic that can be used as the recording medium material include polycarbonate, acrylic resin, ABS, polyacetal, PVA, and rubbers. Metals and glass can also be used as a recording medium, and a surface-treated support serving as a printing plate substrate is used as the recording medium, and an image is formed on the surface of the support with ink-repellent ink. A printing plate can also be formed.
In the ink composition, when a material with low heat shrinkage at the time of curing is selected, the adhesion between the cured ink composition and the recording medium is excellent. Films that are easily deformed, such as PET film, OPS film, OPP film, ONy film, PVC film, and the like that can be shrunk by heat, have an advantage that a high-definition image can be formed.

In the above embodiment, ultraviolet curable ink and ultraviolet curable transparent liquid are used as the ink and the transparent liquid, and the ultraviolet light source is used as the light source for curing the ink and the liquid. However, the present invention is not limited to this. However, various active energy curable inks and active energy curable transparent liquids can be used as the ink, and a light source that irradiates active energy is used as a light source for curing the ink and the transparent liquid. it can.
Here, the “active energy” as used in the present invention is not particularly limited as long as it can impart energy capable of generating a starting species in the ink and the transparent liquid by the irradiation, and is broadly expressed by α rays. , Γ rays, X rays, ultraviolet rays, visible rays, electron beams, and the like. Among these, from the viewpoints of curing sensitivity and device availability, ultraviolet rays and electron beams are preferable, and ultraviolet rays are particularly preferable. Therefore, the active energy curable ink and the active energy curable transparent liquid are preferably inks and transparent liquids that can be cured by irradiation with ultraviolet rays.

  Hereinafter, an active energy curable ink and a transparent liquid that can be suitably used in an ink jet drawing apparatus using an active energy curable ink as in the above-described embodiment in the ink jet drawing apparatus using the positional deviation detection method of the present invention, The active energy for curing the ink will be described in detail. The active energy type transparent liquid is the same as the active energy curable ink except that it does not have a coloring material. Therefore, the active energy type ink will be mainly described below.

The peak wavelength of the active energy is, for example, 200 to 650 nm, preferably 300 to 450 nm, more preferably 350, although it depends on the absorption characteristics of the sensitizing dye in the ink (hereinafter also referred to as “ink composition”). It is suitable that it is ˜450 nm. In addition, the (a) electron transfer start system of the ink of the present invention has sufficient sensitivity even with low output active energy. Therefore, the output of active energy is, for example, 2,000 mJ / cm ² or less, preferably 10 to 2,000 mJ / cm ² , more preferably 20 to 1,000 mJ / cm ² , and still more preferably 50 to 800 mJ. An irradiation energy of / cm ² is appropriate. The active energy exposure surface illuminance (the maximum illuminance of the surface of the recording medium) is, for example, 10 to 2,000 mW / cm ^2, preferably, suitably be irradiated at 20 to 1,000 mW / cm ² is there.
In particular, in the ink jet recording apparatus used in the present invention, active energy irradiation is performed using ultraviolet rays having an emission wavelength peak of 390 to 420 nm and a maximum illuminance on the recording medium surface of 10 to 1,000 mW / cm ^2. Irradiation is preferably from a generated light emitting diode.

In the ink jet drawing apparatus using the present invention, it is appropriate that the active energy is applied to the ink composition ejected on the recording medium, for example, 0.01 to 120 seconds, preferably 0.1 to 90 seconds. It is.
Furthermore, in the ink jet drawing apparatus using the present invention, the ink is heated to a constant temperature, and the time from the landing of the ink on the recording medium to the irradiation of the active energy may be 0.01 to 0.5 seconds. Desirably, preferably 0.02-0.3 seconds, more preferably 0.03-0.15 seconds. As described above, by controlling the time from the landing of the ink to the recording medium to the irradiation of the active energy in an extremely short time, it is possible to prevent the landed ink from spreading before being cured.

  In order to obtain a color image using the ink jet recording apparatus using the present invention, it is preferable to superimpose in order from the color with the lowest brightness. By overlapping in this way, the active energy can easily reach the lower ink, and good curing sensitivity, reduction of residual monomers, reduction of odor, and improvement of adhesion can be expected. In addition, although irradiation with active energy can be performed by injecting all the colors and exposing them together, exposure for each color is preferable from the viewpoint of promoting curing.

  In addition, as described above, since the active energy curable ink desirably has a constant temperature for the ejected ink, temperature control by heat insulation and heating is performed from the ink supply tank to the recording head (inkjet head) portion. It is preferable to carry out. The recording head unit to be heated is preferably thermally shielded or insulated so that the apparatus main body is not affected by the temperature of the outside air. In order to shorten the printer start-up time required for heating or to reduce the loss of heat energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

  Further, mercury lamps and gas / solid lasers are mainly used as active energy sources, and mercury lamps and metal halide lamps are widely known as UV irradiation parts for curing UV photocurable ink. Yes. Furthermore, replacement with a GaN-based semiconductor ultraviolet light emitting device is very useful industrially and environmentally. Furthermore, LED (UV-LED) and LD (UV-LD) are small, have a long lifetime, high efficiency, and low cost, and can be suitably used as an active energy curable inkjet radiation source (active light source).

  Further, as described above, a light emitting diode (LED) and a laser diode (LD) can be used as the active energy source. In particular, when an ultraviolet light source is required, an ultraviolet LED and an ultraviolet LD can be used. For example, Nichia Corporation has introduced a purple LED whose main emission spectrum has a wavelength between 365 nm and 420 nm. Furthermore, when shorter wavelengths are required, US Pat. No. 6,084,250 discloses an LED that can emit active energy centered between 300 nm and 370 nm. Other ultraviolet LEDs are also available and can radiate radiation in different ultraviolet bands. A particularly preferable active energy source in the present invention is a UV-LED, and a UV-LED having a peak wavelength of 350 to 420 nm is particularly preferable.

Below, each component used for the active energy curable ink which can be used suitably by this invention is demonstrated one by one.
Examples of the ink that can be suitably used in the present invention and can be cured by irradiation with active energy include a cationic polymerization ink composition, a radical polymerization ink composition, and a water-based ink composition. These compositions will be described in detail below.

(Cationically-polymerized ink composition)
The cationic polymerization-type ink composition contains (a) a cationic polymerizable compound, (b) a compound that generates an acid upon irradiation with active energy, and (c) a colorant. If desired, it may further contain an ultraviolet absorber, a sensitizer, an antioxidant, an antifading agent, a conductive salt, a solvent, a polymer compound, a surfactant and the like.
Hereafter, each component used for a cationic polymerization type ink composition is demonstrated one by one.

[(A) Cationic polymerizable compound]
The (a) cationic polymerizable compound used in the active energy curable ink is a compound that causes a polymerization reaction by an acid generated from a compound that generates an acid upon irradiation with active energy (b), which will be described later, and is cured. There is no restriction | limiting, The various well-known cationically polymerizable monomer known as a photocationic polymerizable monomer can be used. Examples of the cationic polymerizable monomer include various publications such as JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, and JP-A-2001-220526. Examples thereof include epoxy compounds, vinyl ether compounds, oxetane compounds and the like.

Examples of the epoxy compound include aromatic epoxides, alicyclic epoxides, and aliphatic epoxides.
Aromatic epoxides include di- or polyglycidyl ethers produced by the reaction of polyphenols having at least one aromatic nucleus or their alkylene oxide adducts and epichlorohydrin, such as bisphenol A or its alkylene oxides. Examples thereof include di- or polyglycidyl ethers of adducts, di- or polyglycidyl ethers of hydrogenated bisphenol A or its alkylene oxide adducts, and novolak-type epoxy resins. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  As the alicyclic epoxide, cyclohexene oxide obtained by epoxidizing a compound having at least one cycloalkane ring such as cyclohexene or cyclopentene ring with a suitable oxidizing agent such as hydrogen peroxide or peracid. Or a cyclopentene oxide containing compound is mentioned preferably.

  Examples of the aliphatic epoxide include dihydric polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. Typical examples include diglycidyl ether of ethylene glycol, diglycidyl ether of propylene glycol or diglycidyl ether of alkylene glycol such as diglycidyl ether of 1,6-hexanediol, di- or tri- or di- or tri-glycol or adducts thereof. Polyglycidyl ether of polyhydric alcohol such as glycidyl ether, diglycidyl ether of polyethylene glycol or alkylene oxide adduct thereof, diglycidyl ether of polyalkylene glycol represented by diglycidyl ether of polypropylene glycol or alkylene oxide adduct thereof, etc. Can be mentioned. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

The epoxy compound may be monofunctional or polyfunctional.
Examples of monofunctional epoxy compounds that can be suitably used for the active energy curable ink include, for example, phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, 1,2-butylene oxide, 1,3-butadiene monooxide, 1,2-epoxydodecane, epichlorohydrin, 1,2-epoxydecane, styrene oxide, cyclohexene oxide, 3-methacryloyloxymethylcyclohexene oxide, 3- Examples include acryloyloxymethylcyclohexene oxide and 3-vinylcyclohexene oxide.

  Examples of polyfunctional epoxy compounds include, for example, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether, brominated bisphenol F diglycidyl ether, and brominated bisphenol. S diglycidyl ether, epoxy novolac resin, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxy 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane-meta-dioxane, bis (3,4-epoxy Hexylmethyl) adipate, vinylcyclohexene oxide, 4-vinylepoxycyclohexane, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxy-6-methylcyclohexyl-3 ', 4'-epoxy- 6'-methylcyclohexanecarboxylate, methylenebis (3,4-epoxycyclohexane), dicyclopentadiene diepoxide, ethylene glycol di (3,4-epoxycyclohexylmethyl) ether, ethylenebis (3,4-epoxycyclohexanecarboxylate) ), Dioctyl epoxyhexahydrophthalate, di-2-ethylhexyl epoxyhexahydrophthalate, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl Ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ethers, 1,1,3-tetradecadiene dioxide, limonene dioxide, 1,2,7,8 -Diepoxyoctane, 1,2,5,6-diepoxycyclooctane and the like.

  Among these epoxy compounds, aromatic epoxides and alicyclic epoxides are preferable from the viewpoint of excellent curing speed, and alicyclic epoxides are particularly preferable.

  Examples of the vinyl ether compound include ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, Di- or trivinyl ether compounds such as methylolpropane trivinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexane dimethanol monovinyl ether, n-propyl Pills vinyl ether, isopropyl vinyl ether, isopropenyl ether -O- propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, and octadecyl vinyl ether.

The vinyl ether compound may be monofunctional or polyfunctional.
Specifically, examples of monofunctional vinyl ethers include, for example, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, t-butyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, lauryl vinyl ether, cyclohexyl vinyl ether, Cyclohexylmethyl vinyl ether, 4-methylcyclohexyl methyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, ethoxyethoxyethyl vinyl ether , Methoxypolyethyleneglycol Vinyl ether, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexyl methyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutyl vinyl ether, Examples include chloroethoxyethyl vinyl ether, phenylethyl vinyl ether, phenoxypolyethylene glycol vinyl ether, and the like.

  Examples of polyfunctional vinyl ethers include ethylene glycol divinyl ether, diethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, hexanediol divinyl ether, bisphenol A alkylene oxide divinyl ether, and bisphenol F. Divinyl ethers such as alkylene oxide divinyl ether; trimethylolethane trivinyl ether, trimethylolpropane trivinyl ether, ditrimethylolpropane tetravinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol Hexavinyl ether, ethylene oxide-added trimethylolpropane trivinyl ether, propylene oxide-added trimethylolpropane trivinyl ether, ethylene oxide-added ditrimethylolpropane tetravinyl ether, propylene oxide-added ditrimethylolpropane tetravinyl ether, ethylene oxide-added pentaerythritol tetravinyl ether, propylene oxide addition Examples thereof include polyfunctional vinyl ethers such as pentaerythritol tetravinyl ether, ethylene oxide-added dipentaerythritol hexavinyl ether, and propylene oxide-added dipentaerythritol hexavinyl ether.

  As the vinyl ether compound, a di- or trivinyl ether compound is preferable from the viewpoints of curability, adhesion to a recording medium, surface hardness of the formed image, and the like, and a divinyl ether compound is particularly preferable.

The oxetane compound in the present invention refers to a compound having an oxetane ring, and a known oxetane compound is arbitrarily selected and used as described in JP-A Nos. 2001-220526, 2001-310937, and 2003-341217. it can.
As the compound having an oxetane ring, a compound having 1 to 4 oxetane rings in the structure is preferably used. By using such a compound, it becomes easy to maintain the viscosity of the ink composition within a good handling range, and obtain high adhesion between the cured ink composition and the recording medium. Can do.

The compound having such an oxetane ring is described in detail in the above-mentioned JP-A No. 2003-341217, paragraph numbers [0021] to [0084], and the compounds described herein can be suitably used in the present invention.
Among the oxetane compounds used in the present invention, it is preferable to use a compound having one oxetane ring from the viewpoint of the viscosity and tackiness of the ink.

In the active energy curable ink, these cationic polymerizable compounds may be used alone or in combination of two or more. From the viewpoint of effectively suppressing shrinkage during ink curing. It is preferable to use a vinyl ether compound in combination with at least one compound selected from an oxetane compound and an epoxy compound.
The content of the (a) cationic polymerizable compound in the ink is suitably 10 to 95% by mass, preferably 30 to 90% by mass, more preferably 50 to 85% by mass, based on the total solid content of the composition. Range.

[(B) Compound that generates acid upon irradiation with active energy]
The active energy curable ink that can be used in the present invention contains a compound that generates an acid upon irradiation with active energy (hereinafter, appropriately referred to as “photo acid generator”).
Examples of the photoacid generator that can be used in the present invention include photoinitiators for photocationic polymerization, photoinitiators for photoradical polymerization, photodecolorants for dyes, photochromic agents, and light used for microresists. (400-200 nm ultraviolet rays, far ultraviolet rays, particularly preferably g-line, h-line, i-line, KrF excimer laser beam), ArF excimer laser beam, electron beam, X-ray, molecular beam, ion beam, etc. A compound capable of generating can be appropriately selected and used.

  As such a photoacid generator, for example, an onium salt such as a diazonium salt, an ammonium salt, a phosphonium salt, an iodonium salt, a sulfonium salt, a selenonium salt, an arsonium salt, which decomposes upon irradiation with active energy to generate an acid, Organic halogen compounds, organic metal / organic halides, photoacid generators having an o-nitrobenzyl type protecting group, compounds that generate photosulfonic acids by photolysis, such as iminosulfonates, disulfone compounds, diazoketo A sulfone and a diazo disulfone compound can be mentioned.

  As the photoacid generator, oxazole derivatives and s-triazine derivatives described in JP-A No. 2002-122994, paragraphs [0029] to [0030] are also preferably used. Furthermore, onium salt compounds and sulfonate compounds exemplified in JP-A-2002-122994, paragraph numbers [0037] to [0063] can also be suitably used as the photoacid generator.

(B) A photo-acid generator can be used individually by 1 type or in combination of 2 or more types.
The content of the (b) photoacid generator in the ink composition is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, and still more preferably in terms of the total solid content of the ink composition. Is 1-7 mass%.

[(C) Colorant]
The active energy curable ink can form a visible image by adding a colorant. For example, when forming an image area of a lithographic printing plate, it is not always necessary to add it, but it is also preferable to use a colorant from the viewpoint of plate inspection of the obtained lithographic printing plate.
There is no restriction | limiting in particular in the coloring agent which can be used here, According to a use, well-known various color materials and (pigment, dye) can be selected suitably, and can be used. For example, when forming an image excellent in weather resistance, a pigment is preferable. As the dye, both water-soluble dyes and oil-soluble dyes can be used, but oil-soluble dyes are preferred.

[Pigment]
The pigments preferably used for the active energy curable ink will be described.
The pigment is not particularly limited, and all commercially available organic and inorganic pigments or pigments dispersed in an insoluble resin or the like as a dispersion medium, or the resin is grafted onto the pigment surface Can be used. Moreover, what dye | stained the resin particle with dye can be used.
Examples of these pigments include, for example, “Pigment Dictionary” (2000), edited by Seijiro Ito. Herbst, K.M. Hunger “Industrial Organic Pigments”, JP 2002-12607 A, JP 2002-188025 A, JP 2003-26978 A, and JP 2003-342503 A3.

  Specific examples of organic pigments and inorganic pigments that can be used in the active energy curable ink include C.I. I. Pigment Yellow 1 (Fast Yellow G etc.), C.I. I. A monoazo pigment such as C.I. Pigment Yellow 74; I. Pigment Yellow 12 (disaji yellow AAA, etc.), C.I. I. Disazo pigments such as C.I. Pigment Yellow 17; I. Non-benzidine type azo pigments such as CI Pigment Yellow 180; I. Azo lake pigments such as C.I. Pigment Yellow 100 (eg Tartrazine Yellow Lake); I. Condensed azo pigments such as CI Pigment Yellow 95 (Condensed Azo Yellow GR, etc.); I. Acidic dye lake pigments such as C.I. Pigment Yellow 115 (such as quinoline yellow lake); I. Basic dye lake pigments such as CI Pigment Yellow 18 (Thioflavin Lake, etc.), anthraquinone pigments such as Flavantron Yellow (Y-24), isoindolinone pigments such as Isoindolinone Yellow 3RLT (Y-110), and quinophthalone yellow Quinophthalone pigments such as (Y-138), isoindoline pigments such as isoindoline yellow (Y-139), C.I. I. Nitroso pigments such as C.I. Pigment Yellow 153 (nickel nitroso yellow, etc.); I. And metal complex salt azomethine pigments such as CI Pigment Yellow 117 (copper azomethine yellow, etc.).

  C. As a thing which exhibits red or magenta color, C.I. I. Monoazo pigments such as CI Pigment Red 3 (Toluidine Red, etc.); I. Disazo pigments such as C.I. Pigment Red 38 (Pyrazolone Red B, etc.); I. Pigment Red 53: 1 (Lake Red C, etc.) and C.I. I. Azo lake pigments such as C.I. Pigment Red 57: 1 (Brilliant Carmine 6B); I. Condensed azo pigments such as C.I. Pigment Red 144 (condensed azo red BR, etc.); I. Acidic dye lake pigments such as C.I. Pigment Red 174 (Phloxine B Lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Red 81 (Rhodamine 6G 'lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Red 177 (eg, dianthraquinonyl red); I. Thioindigo pigments such as C.I. Pigment Red 88 (Thioindigo Bordeaux, etc.); I. Perinone pigments such as C.I. Pigment Red 194 (perinone red, etc.); I. Perylene pigments such as C.I. Pigment Red 149 (perylene scarlet, etc.); I. Pigment violet 19 (unsubstituted quinacridone), C.I. I. Quinacridone pigments such as CI Pigment Red 122 (quinacridone magenta, etc.); I. Isoindolinone pigments such as CI Pigment Red 180 (isoindolinone red 2BLT, etc.); I. And alizarin lake pigments such as CI Pigment Red 83 (Mada Lake, etc.).

  As a pigment exhibiting blue or cyan, C.I. I. Disazo pigments such as C.I. Pigment Blue 25 (Dianisidine Blue, etc.); I. Phthalocyanine pigments such as C.I. Pigment Blue 15 (phthalocyanine blue, etc.); I. Acidic dye lake pigments such as C.I. Pigment Blue 24 (Peacock Blue Lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Blue 1 (Viclotia Pure Blue BO Lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Blue 60 (Indantron Blue, etc.); I. And alkali blue pigments such as CI Pigment Blue 18 (Alkali Blue V-5: 1).

As a pigment exhibiting green, C.I. I. Pigment green 7 (phthalocyanine green), C.I. I. Phthalocyanine pigments such as C.I. Pigment Green 36 (phthalocyanine green); I. And azo metal complex pigments such as CI Pigment Green 8 (Nitroso Green).
As a pigment exhibiting an orange color, C.I. I. An isoindoline pigment such as C.I. Pigment Orange 66 (isoindoline orange); I. And anthraquinone pigments such as CI Pigment Orange 51 (dichloropyrantron orange).

Examples of the black pigment include carbon black, titanium black, and aniline black.
Specific examples of the white pigment include basic lead carbonate (2PbCO ₃ Pb (OH) ₂ , so-called silver white), zinc oxide (ZnO, so-called zinc white), titanium oxide (TiO ₂ , so-called titanium white), Strontium titanate (SrTiO ₃ , so-called titanium strontium white) or the like can be used.

  Here, titanium oxide has a smaller specific gravity than other white pigments, a large refractive index, and is chemically and physically stable, so that it has a large hiding power and coloring power as a pigment. Excellent durability against other environments. Therefore, it is preferable to use titanium oxide as the white pigment. Of course, other white pigments (may be other than the listed white pigments) may be used as necessary.

For dispersing the pigment, for example, a dispersion device such as a ball mill, a sand mill, an attritor, a roll mill, a jet mill, a homogenizer, a paint shaker, a kneader, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, or a wet jet mill is used. be able to.
It is also possible to add a dispersant when dispersing the pigment. Examples of the dispersant include a hydroxyl group-containing carboxylic acid ester, a salt of a long-chain polyaminoamide and a high molecular weight acid ester, a salt of a high molecular weight polycarboxylic acid, a high molecular weight unsaturated acid ester, a high molecular weight copolymer, a modified polyacrylate, an aliphatic Examples thereof include polyvalent carboxylic acids, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl phosphate esters, and pigment derivatives. It is also preferable to use a commercially available polymer dispersant such as the Solsperse series from Zeneca.
Moreover, it is also possible to use a synergist according to various pigments as a dispersion aid. These dispersants and dispersion aids are preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the pigment.

  In the active energy curable ink, as a dispersion medium for various components such as pigments, a solvent may be added, and the above-mentioned (a) cationic polymerizable compound which is a low molecular weight component without solvent is used as a dispersion medium. However, since the ink is cured after being applied to the recording medium, it is preferably solventless. This is because if the solvent remains in the cured ink image, the solvent resistance is deteriorated or a VOC (Volatile Organic Compound) problem of the remaining solvent occurs. From such a viewpoint, as the dispersion medium, (a) a cation polymerizable compound is used, and among them, it is preferable to select a cation polymerizable monomer having the lowest viscosity in terms of dispersion suitability and handling property of the ink composition. .

The average particle size of the pigment is preferably 0.02 to 4 μm, more preferably 0.02 to 2 μm, and more preferably 0.02 to 1.0 μm.
The selection of pigment, dispersant, dispersion medium, dispersion conditions, and filtration conditions are set so that the average particle diameter of the pigment particles is within the above-mentioned preferable range. By controlling the particle size, clogging of the head nozzle can be suppressed, and ink storage stability, ink transparency, and curing sensitivity can be maintained.

〔dye〕
The dye used for the active energy curable ink is preferably oil-soluble. Specifically, it means that the solubility in water at 25 ° C. (the mass of the dye dissolved in 100 g of water) is 1 g or less, preferably 0.5 g or less, more preferably 0.1 g or less. Therefore, a so-called water-insoluble oil-soluble dye is preferably used.

It is also preferable to introduce an oil-solubilizing group into the dye mother nucleus described above in order to dissolve the necessary amount of the dye used in the active energy curable ink in the ink.
As the oil-solubilizing group, long chain, branched alkyl group, long chain, branched alkoxy group, long chain, branched alkylthio group, long chain, branched alkylsulfonyl group, long chain, branched acyloxy group, long chain, branched alkoxycarbonyl group, Long chain, branched acyl group, long chain, branched acylamino group long chain, branched alkylsulfonylamino group, long chain, branched alkylaminosulfonyl group and these long chains, aryl groups containing branched substituents, aryloxy groups, aryloxycarbonyl Group, arylcarbonyloxy group, arylaminocarbonyl group, arylaminosulfonyl group, arylsulfonylamino group and the like.
In addition, for water-soluble dyes having carboxylic acid and sulfonic acid, long chain, branched alcohol, amine, phenol, aniline derivatives are used as oil-solubilizing alkoxycarbonyl groups, aryloxycarbonyl groups, alkylaminosulfonyl groups, A dye may be obtained by conversion to an arylaminosulfonyl group.

The oil-soluble dye preferably has a melting point of 200 ° C. or lower, more preferably has a melting point of 150 ° C. or lower, and still more preferably has a melting point of 100 ° C. or lower. By using an oil-soluble dye having a low melting point, the precipitation of pigment crystals in the ink is suppressed, and the storage stability of the ink is improved.
Further, it is desirable that the oxidation potential is noble (high) in order to improve fading, particularly resistance to oxidizing substances such as ozone and curing characteristics. For this reason, as the oil-soluble dye used in the present invention, those having an oxidation potential of 1.0 V (vs SCE) or more are preferably used. The oxidation potential is preferably higher, the oxidation potential is more preferably 1.1 V (vs SCE) or more, and particularly preferably 1.15 V (vs SCE) or more.

As the yellow dye, a compound having a structure represented by the general formula (Y-I) described in JP-A No. 2004-250483 is preferable.
Particularly preferred dyes are dyes represented by the general formulas (Y-II) to (Y-IV) described in paragraph [0034] of JP-A No. 2004-250483. And the compounds described in paragraph numbers [0060] to [0071] of JP-A-250483. The oil-soluble dye of the general formula (Y-I) described in the publication may be used not only for yellow but also for inks of any color such as black ink and red ink.

The magenta dye is preferably a compound having a structure represented by the general formulas (3) and (4) described in JP-A No. 2002-114930. Specific examples include paragraphs of JP-A No. 2002-114930. Examples include the compounds described in [0054] to [0073].
Particularly preferred dyes are azo dyes represented by the general formulas (M-1) to (M-2) described in paragraph numbers [0084] to [0122] of JP-A No. 2002-121414, and specific examples Examples thereof include compounds described in paragraph numbers [0123] to [0132] of JP-A No. 2002-121414. The oil-soluble dyes represented by the general formulas (3), (4) and (M-1) to (M-2) described in the publication are used not only for magenta but also for any color ink such as black ink and red ink. May be.

Examples of cyan dyes include dyes represented by formulas (I) to (IV) described in JP-A No. 2001-181547, and paragraphs [0063] to [0078] of JP-A No. 2002-121414. The dyes represented by the general formulas (IV-1) to (IV-4) are mentioned as preferable examples, and specific examples include paragraph numbers [0052] to [0066] of JP-A No. 2001-181547. Examples thereof include the compounds described in paragraph Nos. [0079] to [0081] of Kai 2002-121414.
Particularly preferred dyes are phthalocyanine dyes represented by general formulas (CI) and (C-II) described in paragraphs [0133] to [0196] of JP-A No. 2002-121414, A phthalocyanine dye represented by formula (C-II) is preferred. Specific examples thereof include the compounds described in JP-A No. 2002-121414, paragraph numbers [0198] to [0201]. The oil-soluble dyes of the formulas (I) to (IV), (IV-1) to (IV-4), (CI) and (C-II) are not only cyan but also black ink or green ink. The ink may be used for any color ink.

These colorants are preferably added in an amount of 1 to 20% by mass in terms of solid content, and more preferably 2 to 10% by mass.
In addition to the essential components described above, various additives can be used in combination with the active energy curable ink depending on the purpose. These optional components will be described.

[Ultraviolet absorber]
In the active energy curable ink, an ultraviolet absorber can be used from the viewpoint of improving the weather resistance of the obtained image and preventing discoloration.
Examples of the ultraviolet absorber are described in JP-A-58-185679, JP-A-61-190537, JP-A-2-782, JP-A-5-97075, JP-A-9-34057, and the like. Benzotriazole compounds, benzophenone compounds described in JP-A No. 46-2784, JP-A No. 5-194843, US Pat. No. 3,214,463, etc., JP-B Nos. 48-30492 and 56-21141 Cinnamic acid compounds described in JP-A-10-88106, JP-A-4-298503, JP-A-8-53427, JP-A-8-239368, JP-A-10-182621, JP The triazine compounds described in JP-A-8-501291, Research Disclosure No. Examples thereof include compounds described in No. 24239, compounds that emit ultraviolet light by absorbing ultraviolet rays typified by stilbene and benzoxazole compounds, so-called fluorescent brighteners, and the like.
The addition amount is appropriately selected according to the purpose, but is generally about 0.5 to 15% by mass in terms of solid content.

[Sensitizer]
If necessary, a sensitizer may be added to the active energy curable ink for the purpose of improving the acid generation efficiency of the photoacid generator and increasing the photosensitive wavelength. Any sensitizer may be used as long as the photoacid generator is sensitized by an electron transfer mechanism or an energy transfer mechanism. Preferably, aromatic polycondensed compounds such as anthracene, 9,10-dialkoxyanthracene, pyrene and perylene, aromatic ketone compounds such as acetophenone, benzophenone, thioxanthone and Michlerketone, heterocyclic compounds such as phenothiazine and N-aryloxazolidinone Is mentioned. The addition amount is appropriately selected according to the purpose, but is generally 0.01 to 1 mol%, preferably 0.1 to 0.5 mol%, based on the photoacid generator.

〔Antioxidant〕
An antioxidant can be added to improve the stability of the ink. Examples of the antioxidant include European Published Patent No. 223739, No. 309401, No. 309402, No. 310551, No. 310552, No. 4594416, German Published Patent No. 3435443. JP, 54-85535, 62-267047, 63-113536, 63-163351, JP-A-2-262654, JP-A-2-71262, Examples thereof include those described in Kaihei 3-121449, JP-A-5-61166, JP-A-5-119449, US Pat. No. 4,814,262, US Pat. No. 4,980,275, and the like.
The addition amount is appropriately selected according to the purpose, but is generally about 0.1 to 8% by mass in terms of solid content.

[Anti-fading agent]
Various organic and metal complex anti-fading agents can be used for the active energy curable ink. Examples of the organic anti-fading agent include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, and heterocycles. Examples of the metal complex anti-fading agent include nickel complexes and zinc complexes. No. 17643, VII, I to J, No. 15162, ibid. No. 18716, page 650, left column, ibid. No. 36544 at page 527, ibid. 307105, page 872, ibid. The compounds described in the patent cited in No. 15162 and the compounds included in the general formulas and compound examples of representative compounds described in JP-A-62-215272, pages 127 to 137 can be used. .
The addition amount is appropriately selected according to the purpose, but is generally about 0.1 to 8% by mass in terms of solid content.

[Conductive salts]
Conductive salts such as potassium thiocyanate, lithium nitrate, ammonium thiocyanate, and dimethylamine hydrochloride can be added to the active energy curable ink for the purpose of controlling ejection properties.

〔solvent〕
It is also effective to add a very small amount of an organic solvent to the active energy curable ink in order to improve the adhesion to the recording medium.
Examples of the solvent include ketone solvents such as acetone, methyl ethyl ketone, and diethyl ketone, alcohol solvents such as methanol, ethanol, 2-propanol, 1-propanol, 1-butanol, and tert-butanol, and chlorine such as chloroform and methylene chloride. Solvents, aromatic solvents such as benzene and toluene, ester solvents such as ethyl acetate, butyl acetate and isopropyl acetate, ether solvents such as diethyl ether, tetrahydrofuran and dioxane, glycols such as ethylene glycol monomethyl ether and ethylene glycol dimethyl ether And ether solvents.
In this case, it is effective to add the solvent within a range that does not cause the problem of solvent resistance and VOC, and the amount is preferably 0.1 to 5% by mass, more preferably 0.1 to 3% by mass with respect to the whole ink composition. % Range.

[Polymer compound]
Various polymer compounds can be added to the active energy curable ink in order to adjust film physical properties. High molecular compounds include acrylic polymers, polyvinyl butyral resins, polyurethane resins, polyamide resins, polyester resins, epoxy resins, phenol resins, polycarbonate resins, polyvinyl butyral resins, polyvinyl formal resins, shellacs, vinyl resins, acrylic resins. Rubber resins, waxes and other natural resins can be used. Two or more of these may be used in combination. Of these, vinyl copolymer obtained by copolymerization of acrylic monomers is preferred. Furthermore, a copolymer containing “carboxyl group-containing monomer”, “methacrylic acid alkyl ester”, or “acrylic acid alkyl ester” as a structural unit is also preferably used as the copolymer composition of the polymer binder.

[Surfactant]
A surfactant may be added to the active energy curable ink.
Examples of the surfactant include those described in JP-A Nos. 62-173463 and 62-183457. For example, anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene blocks Nonionic surfactants such as copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. An organic fluoro compound may be used in place of the surfactant. The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compounds include fluorine surfactants, oily fluorine compounds (eg, fluorine oil) and solid fluorine compound resins (eg, tetrafluoroethylene resin). No. (columns 8 to 17) and those described in JP-A Nos. 62-135826.

In addition to this, if necessary, for example, leveling additives, matting agents, waxes for adjusting film physical properties, polymerization to inhibit the adhesion to recording media such as polyolefin and PET, and the like, The tackifier which does not do can be contained.
As the tackifier, specifically, a high molecular weight adhesive polymer described in JP-A-2001-49200, 5-6p (for example, (meth) acrylic acid and an alkyl group having 1 to 20 carbon atoms). An ester with an alcohol having, an ester of (meth) acrylic acid with an alicyclic alcohol having 3 to 14 carbon atoms, a copolymer comprising an ester of (meth) acrylic acid with an aromatic alcohol having 6 to 14 carbon atoms) And a low molecular weight tackifying resin having a polymerizable unsaturated bond.

[Preferred physical properties of ink]
The active energy curable ink preferably has an ink viscosity of 20 mPa · s or less, more preferably 10 mPa · s or less at the temperature at the time of injection in consideration of ejection properties. It is preferable to adjust and determine the ratio.

  The common surface tension of the active energy curable ink is preferably 20 to 40 mN / m, more preferably 25 to 35 mN / m. When recording on various recording media such as polyolefin, PET, coated paper, and non-coated paper, 20 mN / m or more is preferable from the viewpoint of bleeding and penetration, and 40 mN / m or less is preferable from the viewpoint of wettability.

  In the printed matter obtained with the active energy curable ink, the image portion is cured by irradiation with active energy such as ultraviolet rays, and the strength of the image portion is excellent. It can be used for various purposes such as formation of a receiving layer (image portion).

[Radical polymerization ink composition]
The radical polymerization ink composition contains (d) a radical polymerizable compound, (e) a polymerization initiator, and (f) a colorant. If desired, it may further contain a sensitizing dye, a co-sensitizer and the like.
Hereinafter, each component used for the radical polymerization ink composition will be sequentially described.

(D) [Radically polymerizable compound]
Examples of the radically polymerizable compound include compounds having an ethylenically unsaturated bond capable of addition polymerization as described below.

[Compound having an ethylenically unsaturated bond capable of addition polymerization]
Examples of compounds having addition-polymerizable ethylenically unsaturated bonds that can be used in active energy curable inks include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc. ) And an aliphatic polyhydric alcohol compound, an amide of the unsaturated carboxylic acid and an aliphatic polyamine compound, and the like.

  Specific examples of the monomer of an ester of an aliphatic polyhydric alcohol compound and an unsaturated carboxylic acid include acrylic acid esters such as ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diacrylate, and tetramethylene glycol. Diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol di Acrylate, Tetraethylene glycol diacrylate, Pentaerythritol diacrylate, Pentaerythritol triacrylate , Pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, polyester acrylate oligomer.

  Methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, Hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p- (3-methacryloxy 2-hydroxypro ) Phenyl] dimethyl methane, bis - [p- (acryloxyethoxy) phenyl] dimethylmethane. Itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate And sorbitol tetritaconate.

  Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate. Examples of isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate. Examples of maleic acid esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate. Furthermore, the mixture of the above-mentioned ester monomer can also be mention | raise | lifted. Specific examples of an amide monomer of an aliphatic polyvalent amine compound and an unsaturated carboxylic acid include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexa. Examples include methylene bis-methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, and xylylene bismethacrylamide.

Other examples include vinyls containing a hydroxyl group represented by the following general formula (A) in a polyisocyanate compound having two or more isocyanate groups per molecule described in JP-B-48-41708. Examples thereof include a vinylurethane compound containing two or more polymerizable vinyl groups in one molecule to which a monomer is added. CH ₂ = C (R) COOCH ₂ CH (R ′) OH (A) (where R and R ′ represent H or CH ₃ ).
Further, as described in JP-A-51-37193, urethane acrylates, JP-A-48-64183, JP-B-49-43191, JP-B-52-30490, etc. Polyfunctional acrylates and methacrylates such as polyester acrylates and epoxy acrylates obtained by reacting an epoxy resin with (meth) acrylic acid can be used. Furthermore, Journal of Japan Adhesion Association vol.20, No. 7, pages 300 to 308 (1984) as photocurable monomers and oligomers can also be used. In the present invention, these monomers can be used in a chemical form such as a prepolymer, that is, a dimer, a trimer and an oligomer, or a mixture thereof and a copolymer thereof.

  The amount of the radical polymerizable compound used is usually 1 to 99.99%, preferably 5 to 90.0%, more preferably 10 to 70% with respect to the total components of the ink. Is).

(E) [Photoinitiator]
Next, the photopolymerization initiator used for the radical polymerization ink composition will be described.
The photopolymerization initiator in the present invention is a compound that undergoes a chemical change through the action of light or interaction with the electronically excited state of a sensitizing dye to generate at least one of radicals, acids, and bases. It is.

  Preferred photopolymerization initiators include (a) aromatic ketones, (b) aromatic onium salt compounds, (c) organic peroxides, (d) hexaarylbiimidazole compounds, (e) ketoxime ester compounds, F) borate compounds, (to) azinium compounds, (thi) metallocene compounds, (li) active ester compounds, (nu) compounds having a carbon halogen bond, and the like.

(F) [Colorant]
The same (c) colorant as described in the cationic polymerization ink composition can be used.
In addition to the essential components described above, various additives can be used in combination with the active energy curable ink depending on the purpose. These optional components will be described.
[Sensitizing dye]
In the present invention, a sensitizing dye may be added for the purpose of improving the sensitivity of the photopolymerization initiator. Examples of preferred sensitizing dyes include those belonging to the following compounds and having an absorption wavelength in the 350 nm to 450 nm region.
Polynuclear aromatics (eg, pyrene, perylene, triphenylene), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine B, rose bengal), cyanines (eg, thiacarbocyanine, oxacarbocyanine), merocyanines ( For example, merocyanine, carbomerocyanine), thiazines (for example, thionine, methylene blue, toluidine blue), acridines (for example, acridine orange, chloroflavin, acriflavine), anthraquinones (for example, anthraquinone), squalium (for example, squalium) ), Coumarins (eg 7-diethylamino-4-methylcoumarin).

[Co-sensitizer]
Furthermore, a known compound having a function of further improving sensitivity or suppressing polymerization inhibition by oxygen may be added to the active energy curable ink as a co-sensitizer.

  Examples of such co-sensitizers include amines such as MR Sander et al., “Journal of Polymer Society”, Vol. 10, page 3173 (1972), Japanese Examined Patent Publication No. 44-20189, Japanese Patent Laid-Open No. 51-82102. Publication, JP 52-134692, JP 59-138205, JP 60-84305, JP 62-18537, JP 64-33104, Research Disclosure 33825 Specifically, triethanolamine, p-dimethylaminobenzoic acid ethyl ester, p-formyldimethylaniline, p-methylthiodimethylaniline and the like can be mentioned.

  Other examples include thiols and sulfides, for example, thiol compounds described in JP-A-53-702, JP-B-55-500806, JP-A-5-142772, and JP-A-56-75643. Examples thereof include disulfide compounds, and specific examples include 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzimidazole, 2-mercapto-4 (3H) -quinazoline, β-mercaptonaphthalene and the like.

  Other examples include amino acid compounds (eg, N-phenylglycine), organometallic compounds described in Japanese Patent Publication No. 48-42965 (eg, tributyltin acetate), and hydrogen described in Japanese Patent Publication No. 55-34414. Donors, sulfur compounds described in JP-A-6-308727 (eg, trithiane), phosphorus compounds described in JP-A-6-250387 (diethylphosphite, etc.), Si-- described in Japanese Patent Application No. 6-191605 H, Ge-H compound, etc. are mentioned.

  Moreover, it is preferable to add 200-20000 ppm of a polymerization inhibitor from a viewpoint of improving storability. The active energy curable ink is preferably ejected by heating and reducing the viscosity in the range of 40 to 80 ° C., and a polymerization inhibitor is preferably added to prevent clogging of the head due to thermal polymerization. Examples of the polymerization inhibitor include hydroquinone, benzoquinone, p-methoxyphenol, TEMPO, TEMPOL, and cuperon Al.

[Others]
In addition, known compounds can be used as necessary. For example, surfactants, leveling additives, matting agents, polyester resins for adjusting film properties, polyurethane resins, vinyl resins, acrylic resins, etc. Resin, rubber resin, wax and the like can be appropriately selected and used. In order to improve the adhesion to a recording medium such as polyolefin or PET, it is also preferable to contain a tackifier that does not inhibit the polymerization. Specifically, high molecular weight adhesive polymers described in JP-A-2001-49200, 5-6p (for example, esters of (meth) acrylic acid and alcohols having an alkyl group having 1 to 20 carbon atoms) , An ester of (meth) acrylic acid and an alicyclic alcohol having 3 to 14 carbon atoms, a copolymer formed of an ester of (meth) acrylic acid and an aromatic alcohol having 6 to 14 carbon atoms), A low molecular weight tackifying resin having a saturated bond.

  It is also effective to add a trace amount of an organic solvent in order to improve the adhesion to the recording medium. In this case, it is effective to add the solvent within a range that does not cause the problem of solvent resistance and VOC. % Range.

  In addition, as a means for preventing a decrease in sensitivity due to the light-shielding effect of the ink color material, it is also preferable to combine a cationic polymerizable monomer having a long polymerization initiator lifetime with a polymerization initiator to obtain a radical-cation hybrid type curable ink. One.

[Water-based ink composition]
The aqueous ink composition contains a water-soluble photopolymerization initiator that generates radicals by the action of a polymerizable compound and active energy. If desired, it may further contain a coloring material and the like.

[Polymerizable compound]
As the polymerizable compound contained in the aqueous ink composition, a polymerizable compound contained in a known aqueous ink composition can be used.
A reactive material can be added to the water-based ink composition in order to optimize the formulation considering end-user characteristics such as curing speed, adhesion, and flexibility. Examples of such reactive materials include (meth) acrylate (ie, acrylate and / or methacrylate) monomers and oligomers, epoxides, and oxetanes.
Examples of acrylate monomers include phenoxyethyl acrylate, octyl decyl acrylate, tetrahydrofuryl acrylate, isobornyl acrylate, hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, polyethylene glycol diacrylate (e.g., tetraethylene glycol). Diacrylate), dipropylene glycol diacrylate, tri (propylene glycol) triacrylate, neopentyl glycol diacrylate, bis (pentaerythritol) hexaacrylate, ethoxylated or propoxylated glycol and polyol acrylate (e.g. propoxylated neopentyl glycol Diacrylate, ethoxylated trimethylol proppant Acrylate), and mixtures thereof.
Examples of acrylate oligomers include ethoxylated polyethylene glycol, ethoxylated trimethylolpropane acrylate and polyether acrylate and ethoxylates thereof, and urethane acrylate oligomers.
Examples of methacrylates include hexanediol dimethacrylate, trimethylolpropane trimethacrylate, triethylene glycol dimethacrylate, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, and mixtures thereof.
The addition amount of the oligomer is preferably 1 to 80% by weight and more preferably 1 to 10% by weight with respect to the total weight of the ink.

[Water-soluble photopolymerization initiator that generates radicals by the action of active energy]
The polymerization initiator that can be used for the active energy curable ink will be described. As an example, for example, a photopolymerization initiator having a wavelength of up to about 400 nm may be mentioned. As such a photopolymerization initiator, for example, a photopolymerization initiator represented by the following general formula (hereinafter referred to as TX) which is a substance having functionality in a long wavelength region, that is, a sensitivity to generate a radical upon receiving ultraviolet rays. In the present invention, it is particularly preferable to select and use them appropriately.

In the general formulas TX-1 to TX-3, R2 represents — (CH ₂ ) _x — (x = 0 or 1), —O— (CH ₂ ) _y — (y = 1 or 2), substituted or unsubstituted Represents a phenylene group. When R2 is a phenylene group, at least one hydrogen atom in the benzene ring is, for example, a carboxyl group or a salt thereof, a sulfonic acid or a salt thereof, a linear or branched alkyl having 1 to 4 carbon atoms. May be substituted with one or more groups or atoms selected from a group, a halogen atom (fluorine, chlorine, bromine, etc.), an alkoxyl group having 1 to 4 carbon atoms, an aryloxy group such as a phenoxy group, and the like. . M represents a hydrogen atom or an alkali metal (for example, Li, Na, K, etc.). R3 and R4 each independently represents a hydrogen atom or a substituted or unsubstituted alkyl group. Examples of the alkyl group include, for example, a linear or branched alkyl group having about 1 to 10 carbon atoms, particularly about 1 to 3 carbon atoms. Moreover, as an example of the substituent of these alkyl groups, a halogen atom (a fluorine atom, a chlorine atom, an oxalic atom etc.), a hydroxyl group, an alkoxyl group (C1-C3 grade) etc. are mentioned, for example. M represents an integer of 1 to 10.

  Furthermore, in the present invention, a water-soluble derivative (hereinafter abbreviated as an IC system) of a photopolymerization initiator Irgacure 2959 (trade name: manufactured by Ciba Specialty Chemicals) having the following general formula may be used. Specifically, IC-1 to IC-3 having the following formulas can be used.

[Prescription for clear ink]
The above-mentioned water-soluble polymerizable compound can be made into a clear ink by making it into the form of a transparent water-based ink without containing the above-mentioned coloring material. In particular, if it is prepared so as to have ink jet recording characteristics, a clear ink for water-based photocurable ink jet recording can be obtained. If such an ink is used, a clear film can be obtained because it does not contain a color material. Clear inks that do not contain color materials can be used for undercoats to give recording materials suitable for image printing, or for surface protection of images formed with ordinary inks, further decoration and gloss The use etc. for the overcoat for the purpose of provision etc. are mentioned. In the clear ink, colorless pigments or fine particles that are not intended for coloring can be dispersed and contained according to these applications. By adding these, it is possible to improve various properties such as image quality, fastness, and workability (handling property) of the printed matter in both the undercoat and the overcoat.

  Prescription conditions for application to such a clear ink include 10 to 85% of a water-soluble polymerizable compound as a main component of the ink, a photopolymerization initiator (for example, an ultraviolet polymerization catalyst), and the above water-soluble polymerization. It is preferable to prepare such that 1 to 10 parts by mass with respect to 100 parts by mass of the active compound and at least 0.5 part of the photopolymerization initiator is simultaneously contained with respect to 100 parts of ink.

[Material composition of colorant-containing ink]
When the above-described water-soluble polymerizable compound is used in an ink containing a color material, the concentration of the polymerization initiator and the polymerizable substance in the ink can be adjusted in accordance with the absorption characteristics of the contained color material. preferable. As described above, the amount of water or solvent is in the range of 40% to 90%, preferably 60% to 75%, based on mass, as the blending amount. Furthermore, the content of the polymerizable compound in the ink is in the range of 1% to 30%, preferably in the range of 5% to 20% on the mass basis with respect to the total amount of the ink. Although the polymerization initiator depends on the content of the polymerizable compound, it is generally in the range of 0.1 to 7%, preferably 0.3 to 5% on the mass basis with respect to the total amount of the ink.

  When a pigment is used as the ink coloring material, the concentration of the pure pigment in the ink is generally in the range of 0.3% by mass to 10% by mass with respect to the total amount of the ink. The coloring power of the pigment depends on the dispersion state of the pigment particles, but if it is in the range of about 0.3 to 1%, it becomes a range used as a light-colored ink. On the other hand, if it is more than that, it gives a density used for general color coloring.

  As described above, the droplet ejection point deviation detection method according to the present invention has been described in detail. However, the present invention is not limited to the above embodiment, and various improvements and modifications can be made without departing from the gist of the present invention. May be performed.

It is a front view which shows schematic structure of an inkjet drawing apparatus. FIG. 2 is a top view showing a suction conveyance bell and a recording head unit of the ink jet drawing apparatus shown in FIG. 1. FIG. 6 is a front view illustrating an arrangement pattern of ejection portions of the recording head. FIG. 4 is an enlarged cross-sectional view illustrating one ejection unit of the recording head illustrated in FIG. 3. It is a schematic diagram which shows the structure of the ink supply system and head peripheral part in an inkjet drawing apparatus. It is a principal block diagram which shows the system configuration | structure of the control part shown in FIG. (A) is a side view showing the relationship between each ejection part of the recording head and the landing position of the ink droplet, and (B) is a top view of (A). It is a top view which shows an example of the image (test pattern) used for a droplet ejection point position shift detection. (A) is a schematic diagram showing an example of one droplet ejection point portion of an image read by a position deviation detection unit, and (B) shows an example of binarizing the image data shown in (A). It is a schematic diagram. (A) And (B) is a schematic diagram explaining an example of the calculation method of the center coordinate of a droplet ejection point, respectively. It is a schematic diagram which shows the approximate straight line computed for every discharge part. It is a schematic diagram which shows another example of the calculation method of the center position of a droplet ejection point. FIG. 10 is a top view illustrating another example of the arrangement pattern of the ejection units of the recording head. It is a schematic block diagram which shows another example of the apparatus structure which can use the droplet ejection point shift | offset | difference detection method of this invention. (A) is the schematic top view which showed the image (test pattern) used for the droplet ejection point position shift detection used for the present Example, (B) is the schematic top view which showed (A) in detail. It is. It is a graph which shows the calculated droplet ejection point space | interval. It is a front view which shows schematic structure of an example of the digital label printing apparatus which can use the droplet ejection point deviation detection method of this invention. It is a longitudinal cross-sectional view which shows the layer structure of a recording medium. The foil pressing state is shown, (A) is a cross-sectional view of the main part of the recording medium having a large unevenness on the image surface, (B) is a cross-sectional view of the main part of the recording medium pressed without smoothing, and (C) is smoothed. It is principal part sectional drawing of the recording medium which smoothed the unevenness | corrugation by the means and pressed the foil. It is a schematic block diagram of the digital label printing apparatus of the modification of the digital label printing apparatus shown in FIG. It is a front view which shows schematic structure of the other example of a digital label printing apparatus. It is a front view which shows schematic structure of the other example of a digital label printing apparatus. It is a front view which shows schematic structure of the other example of a digital label printing apparatus. It is a front view which shows schematic structure of the other example of a digital label printing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inkjet drawing apparatus 12 Supply part 14,110 Conveyance part 16,112 Drawing part 18 Heating / pressurization part 20 Discharge part 22 Control part 24,114 Misalignment detection part 30 Magazine 32 Heating drum 34, 56 Cutter 34a, 56a Fixed blade 34b, 56b Round blade 36 Adsorption belt transport unit 37a, 37b Roller 38 Belt 39 Adsorption chamber 40 Fan 42 Belt cleaning unit 44 Heating fan 46 Post-drying unit 50, 135 Recording head unit 50K, 50C, 50M, 50Y, 136C, 136M, 136Y, 136K recording head (inkjet head)
52 Ink Storage / Loading Unit 54 Pressure Roller 58 Ejection Unit 60 Ejection Unit 61 Ink Chamber Unit 62 Nozzle 63 Pressure Chamber 64 Supply Port 65 Common Channel 66 Actuator 67 Pressure Plate 68 Individual Electrode 70 Ink Supply Tank 72 Filter 74 Cap 76 Cleaning Blade 77 Suction pump 78 Collection tank 80 Communication interface 82 System controller 84 Image memory 86 Motor driver 88 Heat driver 90 Print controller 92 Image buffer memory 94 Head driver 96 Host computer 98 Motor 99 Heater 100, 101, 200, 300, 400, 500 Digital Label Printing Device 116 Smoothing Unit 118 Foil Pressing Unit 120 Label Unloading Unit 122 Supply Roll 124, 126, 128, 130, 132 Feed roller pair 134 Product winding unit 138 Ultraviolet irradiation unit 142 Varnish coater 144, 145 Application roller 146 Flat pressure member 148 Ultraviolet irradiation unit 150 Foil supply roll 152 Foil winding roll 154, 156 Roller 158 Foil 160 Hot stamp plate 162 Varnish coater 164 Ultraviolet irradiation part 166 Die cutter 168 Cylinder cutter 170 Receiving roller 172 Waste removal part P Recording medium

Claims (6)

Droplet point deviation detection that detects the positional deviation of the ink droplet ejection points that are ejected from each ejection part of the recording head in which a plurality of ejection parts that eject ink droplets are arranged in a line and land on the recording medium A method,
A step of discharging a plurality of ink droplets from the discharge portion to form a plurality of droplet ejection points on the recording medium;
An image reading step of reading an image composed of the droplet ejection points formed on the recording medium as a read image;
A droplet ejection point position information calculating step for calculating the center position of each droplet ejection point as droplet ejection point position information by performing image processing on the read image;
A droplet ejection point position information classification step for classifying the droplet ejection point position information as droplet ejection point position classification information for each ejection unit that ejected each droplet ejection point;
Approximate line calculation step for calculating an approximate straight line connecting a plurality of droplet ejection points ejected from a single ejection unit based on the droplet ejection point position classification information, with the slope of the approximate line being common for each ejection unit. When,
An approximate straight line interval calculating step for calculating an interval between the approximate straight lines obtained for each discharge unit;
A droplet ejection point deviation detecting method comprising:   The droplet ejection point deviation detection method according to claim 1, wherein the approximate straight line is calculated by a least square method.   3. The droplet ejection point deviation detection method according to claim 1, wherein the droplet ejection point is in non-contact with a droplet ejection point adjacent in the width direction of the recording medium or in a direction orthogonal to the width direction.   The droplet ejection point deviation detection method according to claim 1, wherein the droplet ejection point rows are formed in a plurality of different portions in a direction orthogonal to the extending direction of the ejection unit on the recording medium.   The droplet ejection point deviation detection method according to claim 4, wherein after another droplet ejection point row is formed among the plurality of ejection units, a droplet ejection point row of the remaining ejection units is formed.   3. The droplet ejection point according to claim 1, wherein the droplet ejection point is a droplet ejection point having a size such that adjacent droplet ejection points in the width direction of the recording medium or in a direction orthogonal to the width direction do not contact each other. Drip point deviation detection method.

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