JP2021006390A - Inkjet recording method and inkjet recording apparatus - Google Patents

Abstract

To provide an inkjet recording method and an inkjet recording apparatus capable of increasing the image quality in inkjet recording using aqueous ink and processing liquid on a non-absorbing recording medium or a low-absorbing recording medium.SOLUTION: The inkjet recording method according to the present invention satisfies the following (formula 1) and (formula 2) when the discharge amount of a first ink nozzle part is a first ink nozzle part discharge amount, the discharge amount of a first processing liquid nozzle part is a first processing liquid nozzle part discharge amount, the discharge amount of a second ink nozzle part is a second ink nozzle part discharge amount, and the discharge amount of a second processing liquid nozzle part is a second liquid nozzle part discharge amount. First ink nozzle part discharge amount<second ink nozzle part discharge amount (Formula 1). (First processing liquid nozzle part discharge amount/first ink nozzle part discharge amount)>(second processing liquid nozzle part discharge amount/second ink nozzle part discharge amount) (Formula 2).SELECTED DRAWING: Figure 4

Description

The present invention relates to an inkjet recording method and an inkjet recording device.

In an inkjet recording method, recording using a water-based inkjet ink (hereinafter, also simply referred to as “ink” or “water-based ink”) for a non-absorbent recording medium such as a film or a low-absorbency recording medium is being studied. .. Examples of the water-based ink include inks containing water as a main component and a coloring material and a resin.

In an inkjet recording method for a non-absorbent recording medium or a low-absorbency recording medium using such a water-based ink, there is a technique for recording an image using a treatment liquid containing a coagulant (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2018-138354

Further improvement in image quality is required for inkjet recording on a non-absorbent recording medium or a low-absorbency recording medium using a water-based ink and a treatment liquid.

[1]
An inkjet recording method in which an ink composition and a treatment liquid containing water are ejected to a recording medium selected from a non-absorbent recording medium or a low-absorbency recording medium by a plurality of main scans for recording. There,
The record is
A main scan that ejects the ink composition and the treatment liquid while moving the ink ejection nozzle group and the treatment liquid ejection nozzle group along the main scanning axis.
A sub-scan that moves the recording medium along a sub-scan axis that intersects the main scan axis.
When the ink ejection nozzle group and the processing liquid ejection nozzle group are projected along the main scanning axis, the ink ejection nozzle group and the processing liquid ejection nozzle group overlap each other along the sub-scanning axis. Have,
The length of one sub-scanning is shorter than the length of the ink ejection nozzle group in the sub-scanning axis direction.
Of the recording region to which the ink composition of the recording medium is adhered, the ink composition is adhered to the band region corresponding to the length of one sub-scan by two or more main scans.
The ink ejection nozzle group includes a first ink nozzle portion and a second ink nozzle portion having a length equal to or less than the length of one sub-scanning.
The treatment liquid ejection nozzle group includes a first treatment liquid nozzle portion that overlaps with the first ink nozzle portion along the sub-scanning axis when projected onto the main scanning axis, and the treatment liquid ejection nozzle group when projected onto the main scanning axis. A second processing liquid nozzle portion that overlaps with the second ink nozzle portion along the sub-scanning axis is provided.
In a certain main scan, the ejection amount of the first ink nozzle portion is the ejection amount of the first ink nozzle portion, the ejection amount of the first processing liquid nozzle portion is the ejection amount of the first processing liquid nozzle portion, and the ejection amount of the second ink nozzle portion. Inkjet recording that satisfies the following (Equation 1) and (Equation 2) when the ejection amount is the ejection amount of the second ink nozzle portion and the ejection amount of the second processing liquid nozzle portion is the ejection amount of the second processing liquid nozzle portion. Method.
First ink nozzle discharge amount <Second ink nozzle discharge amount ... (Equation 1)
(Discharge amount of 1st treatment liquid nozzle / Discharge amount of 1st ink nozzle)> (Discharge amount of 2nd treatment liquid nozzle / Discharge amount of 2nd ink nozzle) ... (Equation 2)

[2]
The ink composition is ejected from the second ink nozzle portion in another main scan to the recording area to which the ink composition is ejected and adhered from the first ink nozzle portion in the certain main scan. The inkjet recording method according to [1], wherein the ink is adhered.

[3]
The inkjet recording method according to [1] or [2], wherein the treatment liquid contains a coagulant.

[4]
The inkjet recording method according to any one of [1] to [3], wherein the first ink nozzle portion and the second ink nozzle portion each have 10 or more and 100 or less nozzles.

[5]
In the recording, the ejection amount of the second ink nozzle portion is the largest in the ink ejection nozzle group, and the ejection amount of the first ink nozzle portion is 30% by mass or less of the ejection amount of the second ink nozzle portion. The inkjet recording method according to any one of [1] to [4].

[6]
(Discharge amount of the first treatment liquid nozzle / discharge amount of the first ink nozzle) with respect to (discharge amount of the second treatment liquid nozzle / second ink nozzle) is 1.5 or more and 2.5 or less. The inkjet recording method according to [5].

[7]
The inkjet recording method according to [5] or [6], wherein (second processing liquid nozzle portion ejection amount / second ink nozzle portion ejection amount) is 0.1 or more and 0.5 or less.

[8]
The first ink nozzle portion is located in a region corresponding to one length of the sub-scan from the end of the ink ejection nozzle group.
The second ink nozzle portion according to any one of [1] to [7], wherein the second ink nozzle portion is in a region other than the region corresponding to the length of one sub-scan from the end of the ink ejection nozzle group. Inkjet recording method.

[9]
The inkjet recording method according to any one of [1] to [8], wherein the first ink nozzle portion and the second ink nozzle portion are each at two or more locations in the ink ejection nozzle group.

[10]
The inkjet recording according to any one of [1] to [9], wherein in the first ink nozzle portion, the ejection amount gradually decreases from one end to the other end of the first ink nozzle portion. Method.

[11]
The inkjet recording method according to any one of [1] to [10], wherein the ink composition is a water-based ink composition containing a pigment.

[12]
The inkjet recording method according to any one of [1] to [11], wherein the ink composition has an organic solvent content of 15% by mass or more.

[13]
The inkjet recording method according to any one of [1] to [12], wherein the ink composition contains an organic solvent having a standard boiling point of 180 ° C. or higher and 280 ° C. or lower.

[14]
The number of main scans for ejecting the treatment liquid is smaller than the number of main scans for ejecting the ink composition with respect to the band region.
The inkjet according to any one of [1] to [13], wherein the main scan for ejecting the treatment liquid is completed earlier than the main scan for ejecting the ink composition with respect to the band region. Recording method.

[15]
A step of heating the recording medium is provided.
The inkjet recording method according to any one of [1] to [14], wherein the main scanning is performed on the heated recording medium.

[16]
The ejection amount of the ink ejection nozzle group is the amount of adhesion of the main scan when recording a predetermined single density image on the recording medium, according to any one of [1] to [15]. Ink recording method.

[17]
The main scan includes a first main scan performed in the first direction and a second main scan performed in the second direction opposite to the first direction.
The inkjet according to any one of [1] to [16], wherein in the first main scan and the second main scan, the order of ejection of the treatment liquid and ejection of the ink composition is the same. Recording method.

[18]
An inkjet recording device that ejects an ink composition and a water-containing treatment liquid onto a recording medium selected from a non-absorbent recording medium or a low-absorbency recording medium by a plurality of main scans for recording. There,
The record is
A main scan that ejects the ink composition and the treatment liquid while moving the ink ejection nozzle group and the treatment liquid ejection nozzle group along the main scanning axis.
A sub-scan that moves the recording medium along a sub-scan axis that intersects the main scan axis.
When the ink ejection nozzle group and the processing liquid ejection nozzle group are projected along the main scanning axis, the ink ejection nozzle group and the processing liquid ejection nozzle group overlap each other along the sub-scanning axis. Have,
The length of one sub-scanning is shorter than the length of the ink ejection nozzle group in the sub-scanning axis direction.
Of the recording region to which the ink composition of the recording medium is adhered, the ink composition is adhered to the band region corresponding to the length of one sub-scan by two or more main scans.
The ink ejection nozzle group includes a first ink nozzle portion and a second ink nozzle portion having a length equal to or less than the length of one sub-scanning.
The treatment liquid ejection nozzle group includes a first treatment liquid nozzle portion that overlaps with the first ink nozzle portion along the sub-scanning axis when projected onto the main scanning axis, and the treatment liquid ejection nozzle group when projected onto the main scanning axis. A second processing liquid nozzle portion that overlaps with the second ink nozzle portion along the sub-scanning axis is provided.
In a certain main scan, the ejection amount of the first ink nozzle portion is the ejection amount of the first ink nozzle portion, the ejection amount of the first processing liquid nozzle portion is the ejection amount of the first processing liquid nozzle portion, and the ejection amount of the second ink nozzle portion. Inkjet recording that satisfies the following (Equation 1) and (Equation 2) when the ejection amount is the ejection amount of the second ink nozzle portion and the ejection amount of the second processing liquid nozzle portion is the ejection amount of the second processing liquid nozzle portion. apparatus.
First ink nozzle discharge amount <Second ink nozzle discharge amount ... (Equation 1)
(Discharge amount of 1st treatment liquid nozzle / Discharge amount of 1st ink nozzle)> (Discharge amount of 2nd treatment liquid nozzle / Discharge amount of 2nd ink nozzle) ... (Equation 2)

Schematic cross-sectional view schematically showing an inkjet recording apparatus. The perspective view which shows an example of the structure around the carriage of the inkjet recording apparatus of FIG. The schematic upper view which shows typically the arrangement of the nozzle group in an inkjet head. The figure which conceptually explains the relationship between the processing liquid and the ink ejection amount in the inkjet recording. The figure which conceptually explains the relationship between the processing liquid and the ink ejection amount in the inkjet recording. The figure which conceptually explains the relationship between the processing liquid and the ink ejection amount in the inkjet recording. The figure which conceptually explains the relationship between the processing liquid and the ink ejection amount in the inkjet recording. The figure which conceptually explains the relationship between the processing liquid and the ink ejection amount in the inkjet recording. The figure which conceptually explains the relationship between the processing liquid and the ink ejection amount in the inkjet recording.

Hereinafter, some embodiments of the present invention will be described. The embodiments described below describe an example of the present invention. The present invention is not limited to the following embodiments, and includes various modifications implemented without changing the gist of the present invention. It should be noted that not all of the configurations described below are essential configurations of the present invention.

One aspect of the inkjet recording method according to the present embodiment is characterized by the following.
An inkjet recording method in which an ink composition and a treatment liquid containing water are ejected to a recording medium selected from a non-absorbent recording medium or a low-absorbency recording medium by a plurality of main scans for recording. There,
The record is
A main scan that ejects the ink composition and the treatment liquid while moving the ink ejection nozzle group and the treatment liquid ejection nozzle group along the main scanning axis.
A sub-scan that moves the recording medium along a sub-scan axis that intersects the main scan axis.
When the ink ejection nozzle group and the processing liquid ejection nozzle group are projected along the main scanning axis, the ink ejection nozzle group and the processing liquid ejection nozzle group overlap each other along the sub-scanning axis. Have,
The length of one sub-scanning is shorter than the length of the ink ejection nozzle group in the sub-scanning axis direction.
Of the recording region to which the ink composition of the recording medium is adhered, the ink composition is adhered to the band region corresponding to the length of one sub-scan by two or more main scans.
The ink ejection nozzle group includes a first ink nozzle portion and a second ink nozzle portion having a length equal to or less than the length of one sub-scanning.
The treatment liquid ejection nozzle group includes a first treatment liquid nozzle portion that overlaps with the first ink nozzle portion along the sub-scanning axis when projected onto the main scanning axis, and the treatment liquid ejection nozzle group when projected onto the main scanning axis. A second processing liquid nozzle portion that overlaps with the second ink nozzle portion along the sub-scanning axis is provided.
In a certain main scan, the ejection amount of the first ink nozzle portion is the ejection amount of the first ink nozzle portion, the ejection amount of the first processing liquid nozzle portion is the ejection amount of the first processing liquid nozzle portion, and the ejection amount of the second ink nozzle portion. Inkjet recording that satisfies the following (Equation 1) and (Equation 2) when the ejection amount is the ejection amount of the second ink nozzle portion and the ejection amount of the second processing liquid nozzle portion is the ejection amount of the second processing liquid nozzle portion. Method.
First ink nozzle discharge amount <Second ink nozzle discharge amount ... (Equation 1)
(Discharge amount of 1st treatment liquid nozzle / Discharge amount of 1st ink nozzle)> (Discharge amount of 2nd treatment liquid nozzle / Discharge amount of 2nd ink nozzle) ... (Equation 2)

One aspect of the inkjet recording device according to the present embodiment is characterized by the following.
An inkjet recording apparatus that ejects an ink composition and a water-containing treatment liquid onto a recording medium selected from a non-absorbent recording medium or a low-absorbency recording medium by a plurality of main scans for recording. There,
The record is
A main scan that ejects the ink composition and the treatment liquid while moving the ink ejection nozzle group and the treatment liquid ejection nozzle group along the main scanning axis.
A sub-scan that moves the recording medium along a sub-scan axis that intersects the main scan axis.
When the ink ejection nozzle group and the processing liquid ejection nozzle group are projected along the main scanning axis, the ink ejection nozzle group and the processing liquid ejection nozzle group overlap each other along the sub-scanning axis. Have,
The length of one sub-scan is shorter than the length of the ink ejection nozzle group in the sub-scan axis direction.
Of the recording region to which the ink composition of the recording medium is adhered, the ink composition is adhered to the band region corresponding to the length of one sub-scan by two or more main scans.
The ink ejection nozzle group includes a first ink nozzle portion and a second ink nozzle portion having a length equal to or less than the length of one sub-scanning.
The treatment liquid ejection nozzle group includes a first treatment liquid nozzle portion that overlaps with the first ink nozzle portion along the sub-scanning axis when projected onto the main scanning axis, and the treatment liquid ejection nozzle group when projected onto the main scanning axis. A second processing liquid nozzle portion that overlaps with the second ink nozzle portion along the sub-scanning axis is provided.
In a certain main scan, the ejection amount of the first ink nozzle portion is the ejection amount of the first ink nozzle portion, the ejection amount of the first processing liquid nozzle portion is the ejection amount of the first processing liquid nozzle portion, and the ejection amount of the second ink nozzle portion. Inkjet recording that satisfies the following (Equation 1) and (Equation 2) when the ejection amount is the ejection amount of the second ink nozzle portion and the ejection amount of the second processing liquid nozzle portion is the ejection amount of the second processing liquid nozzle portion. apparatus.
First ink nozzle discharge amount <Second ink nozzle discharge amount ... (Equation 1)
(Discharge amount of 1st treatment liquid nozzle / Discharge amount of 1st ink nozzle)> (Discharge amount of 2nd treatment liquid nozzle / Discharge amount of 2nd ink nozzle) ... (Equation 2)

Hereinafter, the inkjet recording method and the inkjet recording device according to the present embodiment will be described in the order of the inkjet recording device, the inkjet head, the ink composition, the treatment liquid, the recording medium, and the inkjet recording method.

1. 1. Each configuration 1.1. Inkjet Recording Device An example of an inkjet recording device in which the inkjet recording method according to the present embodiment is implemented will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view schematically showing an inkjet recording device. FIG. 2 is a perspective view showing an example of the configuration around the carriage of the inkjet recording device 1 of FIG. As shown in FIGS. 1 and 2, the inkjet recording device 1 includes an inkjet head 2, an IR heater 3, a platen heater 4, a heating heater 5, a cooling fan 6, a preheater 7, a ventilation fan 8, and the like. It includes a carriage 9, a platen 11, a carriage moving mechanism 13, a transport means 14, and a control unit CONT. In the inkjet recording device 1, the operation of the entire inkjet recording device 1 is controlled by the control unit CONT shown in FIG.

The inkjet head 2 ejects and adheres the ink composition and the treatment liquid that aggregates the components of the ink composition from the ink ejection nozzle group 15 and the treatment liquid ejection nozzle group 16 (see FIG. 3), respectively. It is a means for recording in 10. In the present embodiment, the inkjet head 2 is a serial recording type inkjet head, and the ink composition and the treatment liquid are recorded on the recording medium 10 by performing main scanning a plurality of times along the main scanning axis relative to the recording medium 10. Attach to.

The inkjet head 2 is mounted on the carriage 9 shown in FIG. The inkjet head 2 moves along the main scanning axis relative to the recording medium 10 by the operation of the carriage moving mechanism 13 that moves the carriage 9 in the medium width direction of the recording medium 10, that is, along the main scanning axis. Is scanned multiple times. Scanning along the main scanning axis is also called main scanning.

Here, the main scanning axis is the axis indicated by the arrow MS in FIG. Multiple scanning along the main scanning axis means that one or both of scanning the main scanning axis MS in the S1 to S2 direction and scanning in the S2 to S1 direction are performed a plurality of times. To do. Both the S1 to S2 directions and the S2 to S1 directions in which the carriage 9 on which the inkjet head 2 is moved move are collectively referred to as the main scanning axis direction. That is, the main scanning axis direction is the moving direction of the carriage 9 on which the inkjet head 2 is mounted, and is the width direction of the recording medium 10.

Further, the axis intersecting the main scanning axis is referred to as a sub-scanning axis, and the sub-scanning is to move the recording medium 10 along the sub-scanning axis. In FIG. 2, the sub-scanning axis is the axis indicated by the arrow SS. That is, the direction from T1 to T2, which is the moving direction of the recording medium 10, is the sub-scanning axis SS, which is also called the sub-scanning axis direction. Then, in one scan, scanning is performed in the main scanning axis direction, that is, in any one of the left-right directions of the inkjet recording device 1, and then sub-scanning is performed. Then, the main scan of the inkjet head 2 and the sub-scan, which is the transport of the recording medium 10, are alternately repeated to record on the recording medium 10. One main scan is also called one pass.

Here, in the present specification, in the recording region 10a to which the ink composition of the recording medium 10 shown in FIG. 2 is attached, the length of one sub-scanning, that is, the predetermined width indicated by the arrow 10c in FIG. 2 is obtained. The band-shaped image region is called a band region 10b. In the present embodiment, the ink composition is adhered to the band region 10b by two or more main scans. That is, in the present embodiment, recording is performed with two or more passes for the band region 10b of the recording medium 10.

A conventionally known method can be used for ejection of the inkjet head 2. In this embodiment, a method of ejecting droplets by utilizing the vibration of the piezoelectric element, that is, an ejection method of forming ink droplets by mechanical deformation of the electrolytic strain element is used.

The inkjet recording device 1 provides an IR heater 3, a platen heater 4, and a ventilation fan 8 for heating the recording medium 10 when ejecting the ink composition or the treatment liquid from the inkjet head 2, that is, for primary heating or primary drying. Be prepared. In the present embodiment, when the recording medium 10 is heated in the ink adhesion step described later, at least one of the IR heater 3, the platen heater 4, and the ventilation fan 8 may be used.

When the IR heater 3 is used, the recording medium 10 can be heated from the side of the inkjet head 2. As a result, the inkjet head 2 is likely to be heated at the same time, but the temperature can be raised without being affected by the thickness of the recording medium 10 as compared with the case where the inkjet head 2 is heated from the back surface of the recording medium 10 such as the platen heater 4. Further, if the platen heater 4 is used when heating the recording medium 10, the recording medium 10 can be heated from the side opposite to the inkjet head 2 side. As a result, the inkjet head 2 is relatively less likely to be heated. On the other hand, when the air is blown by the ventilation fan 8, it is preferable that the evaporation of the ink components can be promoted and the drying proceeds easily. Warm air is preferable for blowing air, but room temperature air is also preferable because it can promote evaporation of ink components. These are examples of heating mechanisms.

The upper limit of the surface temperature of the recording medium 10 when the treatment liquid or ink is attached is preferably 45 ° C. or lower, more preferably 40 ° C. or lower, and even more preferably 38 ° C. or lower. It is particularly preferable that the temperature is 35 ° C. or lower. The lower limit of the surface temperature of the recording medium 10 is preferably 25 ° C. or higher, more preferably 28 ° C. or higher, further preferably 30 ° C. or higher, and particularly preferably 32 ° C. or higher. ..

Even when the recording medium is heated by the heating mechanism, since the radiant heat received from the IR heater 3 and the platen heater 4 is small or not received when the temperature is below the above range, the ink composition in the inkjet head 2 and in the vicinity of the nozzle is not received. Drying and composition fluctuation of the substance and the treatment liquid can be suppressed, welding of the ink composition and the treatment liquid component to the inner wall of the inkjet head 2 and thickening and solidification in the vicinity of the nozzle are suppressed. In addition, the ink composition and the treatment liquid can be fixed at an early stage, and the image quality can be improved.

The heater 5 is a heating mechanism for drying and solidifying the ink composition and the treatment liquid adhering to the recording medium 10, that is, for secondary heating or secondary drying. When the heating heater 5 heats the recording medium 10 on which the image is recorded, the water content in the ink composition and the treatment liquid evaporates and scatters more quickly, and the resin contained in the ink forms an ink coating film. Will be done. In this way, the ink coating film is firmly fixed or adhered on the recording medium 10 to obtain excellent film-forming property, and an excellent high-quality image can be obtained in a short time. The upper limit of the surface temperature of the recording medium 10 by the heater 5 is preferably 120 ° C. or lower, more preferably 100 ° C. or lower, and further preferably 90 ° C. or lower. Further, the lower limit of the surface temperature of the recording medium 10 is preferably 60 ° C. or higher, more preferably 70 ° C. or higher, and further preferably 80 ° C. or higher. When the temperature is in the above range, a high-quality image can be obtained in a short time.

The inkjet recording device 1 may have a cooling fan 6. After the ink composition recorded on the recording medium 10 is dried, the ink composition on the recording medium 10 is cooled by the cooling fan 6, so that an ink coating film can be formed on the recording medium 10 with good adhesion.

Further, the inkjet recording device 1 may include a preheater 7 that preheats the recording medium 10 before the ink composition or the treatment liquid adheres to the recording medium 10. Further, the inkjet recording device 1 may be provided with a ventilation fan 8 so that the ink composition and the treatment liquid adhering to the recording medium 10 are dried more efficiently.

Below the carriage 9, a platen 11 on which the recording medium 10 is conveyed, a carriage moving mechanism 13 that moves the carriage 9 relative to the recording medium 10, and a roller that conveys the recording medium 10 in the sub-scanning axis direction. The transport means 14 is provided. The carriage moving mechanism 13 is a scanning means for scanning the inkjet head 2 in the main scanning axis direction. The operations of the carriage moving mechanism 13 and the transport means 14 are controlled by the control unit CONT.

1.2. Ink-jet head As described above, in the present embodiment, the inkjet head 2 ejects and adheres the ink composition and the treatment liquid onto the recording medium 10 while moving in the main scanning axis direction by moving the carriage 9. As described above, in the present embodiment, the inkjet head 2 is scanned and recorded a plurality of times in the main scanning axis direction relative to the recording medium 10.

In the present embodiment, the cartridge 12 that supplies the ink composition and the treatment liquid to the inkjet head 2 is composed of a plurality of independent cartridges. The cartridge 12 is detachably attached to the carriage 9 on which the inkjet head 2 is mounted. Each of the plurality of cartridges is filled with a different type of ink composition or treatment liquid, and the ink composition or treatment liquid is supplied from the cartridge 12 to each nozzle. In the present embodiment, the cartridge 12 is mounted on the carriage 9, but the cartridge 12 is not limited to this, and is provided in a place other than the carriage 9 and is attached to each nozzle by a supply pipe (not shown). It may be in the form of being supplied.

FIG. 3 schematically shows an example of an arrangement of nozzle groups on the nozzle surface 2a of the inkjet head 2. In FIG. 3, MS indicates the main scanning axis, that is, the direction of the main scanning axis, and SS indicates the sub-scanning axis, that is, the direction of the sub-scanning axis. The inkjet head 2 has a nozzle surface 2a including a plurality of nozzles for ejecting an ink composition or a treatment liquid. In the example shown in FIG. 3, on the nozzle surface 2a of the inkjet head 2, a plurality of nozzles filled with ink are arranged in the sub-scanning axis direction, and a plurality of ink ejection nozzle groups 15 used for recording and ejecting ink at the time of recording are used. A plurality of nozzles filled with the treatment liquid are arranged in the sub-scanning axis direction, and have a treatment liquid discharge nozzle group 16 used for recording and discharging the treatment liquid at the time of recording. In FIG. 3, the treatment liquid discharge nozzle group 16 has two rows, but there may be only one row at one end or at the other region. Further, the treatment liquid discharge nozzle group 16 may have one row or two or more rows at the left and right ends of the nozzle surface 2a, respectively.

In the present embodiment, in an example of the arrangement of the nozzle groups shown in FIG. 3, the processing liquid ejection nozzle group 16 has a region where the positions overlap with the ink ejection nozzle group 15 in the sub-scanning axis direction. Here, the overlapping region refers to the length in the sub-scanning axis direction indicated by X in FIG. In the example shown in FIG. 3, the overlapping region X is 100% of the length of the processing liquid ejection nozzle group 16 in the sub-scanning axis direction and 100% of the length of the ink ejection nozzle group 15 in the sub-scanning axis direction. In this example, since the overlapping region X is 100% of the length of each nozzle group in the sub-scanning axis direction, the treatment liquid and the ink can be attached at the same time in one scan, and the recording speed is increased.

In an example of the arrangement of the nozzle groups shown in FIG. 3, only the upstream side of the processing liquid ejection nozzle group 16 in the sub-scanning axial direction is used, and the downstream side of the ink ejection nozzle group 15 in the sub-scanning axial direction. When only the treatment liquid ejection nozzle group 16 and the ink ejection nozzle group 15 are used, the overlapping region X of the processing liquid ejection nozzle group 16 and the ink ejection nozzle group 15 is 0%, and the overlapping region of the processing liquid ejection nozzle group and the ink ejection nozzle group actually used does not exist. In this case, only the processing liquid is first adhered to the recording medium 10 in the main scan of 1, and the ink is adhered to the same position in the main scan after the main scan, so that the image quality is improved. However, since only half of the nozzles of the inkjet head 2 are used, the recording speed becomes slow. In this embodiment, such a case is not considered. In the present embodiment, there is an overlapping region of the processing liquid ejection nozzle group and the ink ejection nozzle group that are actually used, and the overlapping region X is more than% of the length of the processing liquid ejection nozzle group 16 in the sub-scanning axis direction. The length of the ink ejection nozzle group 15 in the sub-scanning axis direction is more than 0%.

As shown in FIG. 3, the ink ejection nozzle group 15 has two first ink nozzle portions 15b having a length equal to or less than the length of one sub-scanning, that is, the length indicated by the arrow 10c in FIG. And a second ink nozzle portion 15a. Similarly, the treatment liquid discharge nozzle group 16 includes two first treatment liquid nozzle portions 16b and a second treatment liquid nozzle portion 16a having a length equal to or less than the length of one sub-scanning, and the first treatment. The liquid nozzle portion 16b overlaps with the first ink nozzle portion 15b along the sub-scanning axis SS when projected onto the main scanning axis MS, and the second processing liquid nozzle portion 16a is projected onto the main scanning axis. It overlaps with the second ink nozzle portion 15a along the line.

In the example shown in FIG. 3, the second ink nozzle portion 15a is located in the A1 region, which is half the length of the central portion of the entire ink ejection nozzle group 15, and is a part of the A1 region. The first ink nozzle portion 15b is located in the B1 region and the B2 region on both sides of the A1 region adjacent to the A1 region, and is at least a part of the B1 region and the B2 region.

In the present embodiment, not limited to the example of FIG. 3, the first ink nozzle portion 15b and the second ink nozzle portion 15a may be provided at one location each in the ink ejection nozzle group 15, but two or more locations are provided for each. You may. Further, the first treatment liquid nozzle portion 16b and the second treatment liquid nozzle portion 16a may be provided at one location each in the treatment liquid discharge nozzle group 16, but may be provided at two or more locations each. Further, it is preferable that the number of nozzles of the first ink nozzle portion 15b and the second ink nozzle portion 15a is 10 or more and 100 or less, respectively. Similarly, the number of nozzles of the first treatment liquid nozzle portion 16b and the second treatment liquid nozzle portion 16a is preferably 10 or more and 100 or less, respectively. Further, the number of nozzles in each nozzle portion is more preferably 10 or more and 50 or less.

The lengths of the first ink nozzle portion 15b and the second ink nozzle portion 15a in the SS direction are each less than or equal to the length of one sub-scan, and are 5% or more and 70% or less of the length of one sub-scan. Is preferable. Further, the number of nozzles of the first ink nozzle portion 15b and the second ink nozzle portion 15a is equal to or less than the number of nozzles of the ink ejection nozzle group existing at one time of the sub-scan, and each of the sub-scans is performed once. It is preferably 5% or more and 70% or less of the number of nozzles of the ink ejection nozzle group existing in the length.

Similarly, the length of each of the first treatment liquid nozzle portion 16b and the second treatment liquid nozzle portion 16a in the SS direction is equal to or less than the length of one sub-scan, and the length of one sub-scan is 5. % To 70% is preferable. Further, the number of nozzles of the first treatment liquid nozzle portion 16b and the second treatment liquid nozzle portion 16a is equal to or less than the number of nozzles of the treatment liquid discharge nozzle group existing at one length of the sub-scan, respectively, and the sub-scan It is preferably 5% or more and 70% or less of the number of nozzles of the treatment liquid discharge nozzle group existing at one time.

In the example of FIG. 3, the A1 region where the first ink nozzle portion 15b and the second processing liquid nozzle portion 16a exist is halved of the entire nozzle group of the ink ejection nozzle group 15 and the processing liquid ejection nozzle group 16. It is a length of 1, and may exceed the length of one sub-scan. In this case, the second ink nozzle portion 15a pays attention to a predetermined part of the A1 region of FIG. 3 which is equal to or less than the length of one sub-scanning. For example, 30 predetermined continuous nozzles in the ink ejection nozzle group 15 existing in the A1 region are referred to as a second ink nozzle portion 15a. The same applies to the first ink nozzle portion 15b, and attention is paid to a predetermined part of the B1 region or the B2 region in FIG. For example, 30 consecutive nozzles centered on the nozzle at the position where the nozzle usage rate is 30% is referred to as a first ink nozzle portion 15b.

Here, the ink ejection nozzle group 15 and the processing liquid ejection nozzle group 16 can adjust the ejection amount of the ink or the processing liquid by adjusting the usage frequency of the nozzles, respectively. The frequency of use of this nozzle is also called the nozzle usage rate (%). The usage rate of the nozzles may be expressed as nozzles in the ink ejection nozzle group 15 and the processing liquid ejection nozzle group 16 that spend a lot of time ejecting ink or processing liquid during the main scanning, or the ink or processing liquid may be expressed. It may be expressed as a nozzle with a large number of discharges.

Here, an example of the nozzle usage rate will be described. For example, when recording an image having a predetermined density on a recording medium, the number of times ink is ejected is the largest when the main scan is performed from one end to the other end in the main scan axis direction of the image in a certain main scan. For example, a nozzle with a large number of nozzles has a nozzle usage rate of 100%. At that time, the nozzle usage rate is calculated by counting the number of times the ink is ejected for the other nozzles as compared with the nozzle having a nozzle usage rate of 100%. The nozzle usage rate of a nozzle that does not eject ink even once in one main scan is 0%. The density of the predetermined image is, for example, the density of the highest density image recorded at the time of recording. In this way, the nozzle usage rate is calculated.

As will be described later, in the present embodiment, the following (Equation 1) and (Equation 2) are set to be satisfied. Then, in this embodiment, it is sufficient to set so as to satisfy the following (Equation 1) and (Equation 2), and the usage rate of each of the above nozzles is not limited.
First ink nozzle discharge amount <Second ink nozzle discharge amount ... (Equation 1)
(Discharge amount of 1st treatment liquid nozzle / Discharge amount of 1st ink nozzle)> (Discharge amount of 2nd treatment liquid nozzle / Discharge amount of 2nd ink nozzle) ... (Equation 2)

The first ink nozzle portion 15b is in a region corresponding to the length of one sub-scan from the end of the ink ejection nozzle group 15, and the second ink nozzle portion 15a is subordinate from the end of the ink ejection nozzle group 15. It is preferably in a region other than the region corresponding to the length of one scan. By setting the first ink nozzle portion 15b and the second ink nozzle portion 15a in this way, the image quality is improved in inkjet recording on a non-absorbent recording medium or a low-absorbency recording medium using water-based ink and a treatment liquid. To do.

1.3. Ink Composition Next, an ink composition (hereinafter, also referred to as “water-based ink composition”, “water-based ink”, or “ink”), which is a water-based inkjet ink used in the inkjet recording method according to the present embodiment, will be described. ..

The water-based ink composition used in the present embodiment is used together with a treatment liquid containing a coagulant, and contains water as a main component.

Here, the inkjet ink is an ink composition used in a recording method by an inkjet method. An "aqueous" composition is one in which water is one of the main solvents. The content of water in the ink composition is preferably 40% by mass or more, more preferably 45% by mass or more, more preferably 50% by mass or more, and particularly preferably 60% by mass or more. The upper limit is not limited, but for example, 98% by mass or less is preferable. The basic composition of each ink composition is the same except that the hue angle is different due to the type of coloring material used, or the content of the coloring material used is different and the color density of the ink is different. Things can be illustrated.

Further, in the present embodiment, the ink composition may or may not contain an organic solvent, and the content of the organic solvent in the ink composition will be described later. If necessary, a coloring material, a resin, a wax, a defoaming agent, and a surfactant can be included.

Hereinafter, the components contained in the ink composition used in the present embodiment and the components that can be contained will be described.

13.1. Water In this embodiment, the ink composition contains water. Water is the main medium of water-based inkjet ink, and is a component that evaporates and scatters when dried. The water is preferably water from which ionic impurities such as pure water or ultrapure water such as ion-exchanged water, ultra-filtered water, reverse osmosis water, and distilled water have been removed as much as possible. Further, it is preferable to use water sterilized by irradiation with ultraviolet rays or addition of hydrogen peroxide because the growth of mold and bacteria can be suppressed when the ink composition is stored for a long period of time.

The water content is preferably 40% by mass or more, more preferably 45% by mass or more, more preferably 50% by mass or more, and particularly preferably 60% by mass or more, based on the total mass of the ink composition.

1.3.2. Color material In the present embodiment, the ink composition may be a color ink containing a color material. Further, a plurality of color inks may be used, or a clear ink containing no coloring material may be used.

As the coloring material, either a dye or a pigment can be used. Pigments are preferably used because they have the property of being resistant to fading to light, gas, and the like. An image formed on a recording medium using a pigment not only has excellent image quality, but also has excellent water resistance, gas resistance, light resistance, and the like, and has good storage stability. This property is particularly remarkable when an image is formed on a non-absorbent recording medium or a low-absorbency recording medium that is low-absorbent or non-absorbent ink.

The pigments that can be used in this embodiment are not particularly limited, and examples thereof include inorganic pigments and organic pigments. As the inorganic pigment, in addition to titanium oxide and iron oxide, carbon black produced by a known method such as a contact method, a furnace method, or a thermal method can be used. On the other hand, as the organic pigment, for example, azo pigment, polycyclic pigment, nitro pigment, nitroso pigment, aniline black and the like can be used. Examples of the azo pigment include azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments and the like. Examples of polycyclic pigments include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinoflorone pigments and the like.

Among specific examples of pigments that can be used in the present embodiment, examples of pigments used in black ink include carbon black. The carbon black is not particularly limited, but for example, furnace black, lamp black, acetylene black, channel black, etc. (CI Pigment Black 7), and commercially available products No. 2300, 900, MCF88, No. 20B, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA77, MA100, No. 2200B etc. (all product names, manufactured by Mitsubishi Chemical Corporation), Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Pretex 35, U, V, 140U, Special Black 6, 5, 4A 4,250, etc. (all product names, manufactured by Degussa), Conductex SC, Raven 1255, 5750, 5250, 5000, 3500, 1255, 700, etc. (all product names, manufactured by Columbia Carbon), Regal 400R, 330R, 660R, Mogul L, Monarch 700, 800, 880, 900, 1000, 1100, 1300, 1400, Elftex 12 and the like (all of the above are trade names, manufactured by Cabot Japan Co., Ltd.).

The pigment used in the white ink is not particularly limited, but for example, C.I. I. Pigment White 6, 18, 21, titanium oxide, zinc oxide, zinc sulfide, antimony oxide, magnesium oxide, and zirconium oxide white inorganic pigments. In addition to the white inorganic pigment, white organic pigments such as white hollow resin fine particles and polymer particles can also be used.

The pigment used for the yellow ink is not particularly limited, but for example, C.I. I. Pigment Yellow 1,2,3,4,5,6,7,10,11,12,13,14,16,17,24,34,35,37,53,55,65,73,74,75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, 120, 124, 128, 129, 133, 138, 139, 147, 151, 153, 154, 167, 172, 180 can be mentioned.

The pigment used in the magenta ink is not particularly limited, but for example, C.I. I. Pigment Red 1,2,3,4,5,6,7,8,9,10,11,12,14,15,16,17,18,19,21,22,23,30,31,32, 37, 38, 40, 41, 42, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 88, 112, 114, 122, 123, 144, 146, 149, 150, 166, 168 , 170, 171, 175, 176, 177, 178, 179, 184, 185, 187, 202, 209, 219, 224, 245, or C.I. I. Pigment Violet 19, 23, 32, 33, 36, 38, 43, 50.

The pigment used for the cyan ink is not particularly limited, but for example, C.I. I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15:34, 15: 4, 16, 18, 22, 25, 60, 65, 66, C.I. I. Bat blue 4, 60 can be mentioned.

The pigment used for color inks other than magenta, cyan, and yellow is not particularly limited, but for example, C.I. I. Pigment Green 7, 10, C.I. I. Pigment Brown 3, 5, 25, 26, C.I. I. Pigment Orange 1, 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, 63.

The pearl pigment is not particularly limited, and examples thereof include pigments having pearl luster and interference luster such as titanium dioxide-coated mica, fish scale foil, and acidified bismuth.

The metallic pigment is not particularly limited, and examples thereof include particles made of simple substances or alloys such as aluminum, silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, and copper.

The lower limit of the content of the coloring material that can be contained in the color ink is preferably 0.5% by mass or more, more preferably 1% by mass or more, based on the total mass of the ink composition. It is more preferably mass% or more. On the other hand, the upper limit of the content of the color material that can be contained in the color ink is preferably 10% by mass or less, more preferably 7% by mass or less, based on the total mass of the ink composition. It is more preferably mass% or less. When the content of the coloring material is within the above range, the image formed on the recording medium is excellent in water resistance, gas resistance, light resistance, and the like, and the ink storage stability is also good.

When the coloring material is a pigment, it can be used in the state of a pigment dispersion liquid. As a method for dispersing the pigment, a dispersant that makes the pigment particles dispersible can be used. The pigment dispersion liquid may contain a solvent in addition to the pigment and the dispersant, if necessary. Examples of the solvent include water and hydrophilic solvents such as diethylene glycol. Moreover, as a dispersant, a styrene-acrylic acid copolymer can be mentioned. Although not particularly limited, the acid value of the dispersant is preferably 20 mgKOH / g or more from the viewpoint of its dispersibility.

Further, in the present embodiment, when clear ink is used as the ink composition, the content of the color material of the clear ink is preferably 0.2% by mass or less, and preferably 0.1% by mass or less. More preferably, it is 0.05% by mass or less, and the lower limit of the content may be 0% by mass. The clear ink is not an ink used for coloring a recording medium, but an ink used for other purposes. Other purposes include, but are limited to, improving characteristics such as scratch resistance of recorded materials, adjusting the glossiness of recording media, and improving the fixability and color development of color inks. It's not a thing. Further, the clear ink is not a treatment liquid described later and does not contain a coagulant.

1.3.3. Organic Solvent In this embodiment, the ink composition preferably contains an organic solvent. Since the ink composition contains an organic solvent, it has excellent clogging resistance during recording. Further, since the ink composition contains an organic solvent, the drying property of the ink composition ejected on the recording medium is improved, and an image having excellent image quality and abrasion resistance can be obtained.

The organic solvent used in the ink composition is preferably a water-soluble organic solvent. By using a water-soluble organic solvent, the drying property of the ink becomes better, and an image having excellent image quality and abrasion resistance can be obtained.

The water-soluble organic solvent is not particularly limited, and examples thereof include alkanediols, polyols, nitrogen-containing solvents, esters, glycol ethers, cyclic esters, and the like.

Examples of the alkanediols include 1,2-alkanediols such as 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol, and 1,6-hexanediol. .. These can be used alone or in admixture of two or more. The alkanediols are excellent in the action of increasing the wettability of the ink composition to the recording medium and uniformly wetting it, and the action as a penetrating solvent for the recording medium. Among these, 1,2-alkanediols are particularly preferable because they have an excellent action as a penetrating solvent. Examples of the alkane diols include alkane diols having 5 or more carbon atoms. The carbon number of the alkane is preferably 5 to 9, and may be a linear type or a branched type.

Examples of polyols include ethylene glycol, propylene glycol, 1,2-propanediol, 1,2-butanediol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, triethylene glycol, and dipropylene glycol. , 2-Ethyl-2-methyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1, 3-Propanediol, 3-methyl-1,3-butanediol, 2-ethyl-1,3-hexanediol, 3-methyl-1,5-pentanediol, 2-methylpentane-2,4-diol, tri Examples thereof include methylol propane and glycerin. It can be used alone or in combination of two or more. Polyols have an excellent action as a moisturizer. Examples of the polyols include alkanes having 2 or more hydroxyl groups and having 4 or less carbon atoms, and alkanes having 2 or more hydroxyl groups and having 4 or less carbon atoms in which the hydroxyl groups are intermolecularly condensed. The number is preferably 2-4. Here, the polyols are compounds having two or more hydroxyl groups in the molecule, and in the present embodiment, the number of hydroxyl groups is preferably 2 or 3.

Examples of the nitrogen-containing solvent include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-pyrrolidone, N-butyl-2-pyrrolidone, and 5-methyl-2-. Examples thereof include pyrrolidones such as pyrrolidone. These can be used alone or in admixture of two or more. The nitrogen-containing solvent acts as a good dissolving agent for the resin, and can obtain a recorded material having excellent image quality and abrasion resistance, and can prevent clogging of the inkjet head and the nozzle.

Examples of the nitrogen-containing solvent include alkoxyalkylamides, for example, 3-methoxy-N, N-dimethylpropionamide, 3-methoxy-N, N-diethylpropionamide, 3-methoxy-N, N-. Methylethylpropionamide, 3-ethoxy-N, N-dimethylpropionamide, 3-ethoxy-N, N-diethylpropionamide, 3-ethoxy-N, N-methylethylpropionamide, 3-n-butoxy-N, N-Dimethylpropionamide, 3-n-butoxy-N, N-diethylpropionamide, 3-n-butoxy-N, N-methylethylpropionamide, 3-n-propoxy-N, N-dimethylpropionamide, 3 -N-propoxy-N, N-diethylpropionamide, 3-n-propoxy-N, N-methylethylpropionamide, 3-iso-propoxy-N, N-dimethylpropionamide, 3-iso-propoxy-N, N-diethylpropionamide, 3-iso-propoxy-N, N-methylethylpropionamide, 3-tert-butoxy-N, N-dimethylpropionamide, 3-tert-butoxy-N, N-diethylpropionamide, 3 -Tart-butoxy-N, N-methylethylpropionamide and the like can be exemplified.

An amide-based solvent can also be mentioned as the nitrogen-containing solvent. Examples of the amide-based solvent include cyclic amide-based solvents and non-cyclic amide-based solvents, which are preferable. Examples of the cyclic amide solvent include the above-mentioned pyrrolidones. Examples of the acyclic amide solvent include the above-mentioned alkoxyalkylamides.

As esters, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl Glycol monoacetates such as ether acetate and methoxybutyl acetate, ethylene glycol diacetate, diethylene glycol diacetate, propylene glycol diacetate, dipropylene glycol diacetate, ethylene glycol acetate propionate, ethylene glycol acetate butyrate, diethylene glycol acetate butyrate. , Diethylene glycol acetate propionate, diethylene glycol acetate butyrate, propylene glycol acetate propionate, propylene glycol acetate butyrate, dipropylene glycol acetate butyrate, dipropylene glycol acetate propionate and other glycol diesters.

The glycol ethers may be alkylene glycol monoethers or diethers, and alkyl ethers are preferable. Specific examples include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylenel glycol monomethyl ether, and triethylene glycol. Monoethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether , Dipropylene glycol monomethyl ether, Dipropylene glycol monoethyl ether, Dipropylene glycol monopropyl ether, Dipropylene glycol monobutyl ether, Tripropylene glycol monobutyl ether and other alkylene glycol monoalkyl ethers, and ethylene glycol dimethyl ether, ethylene glycol diethyl ether. Ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl butyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, triethylene glycol methyl butyl ether, Examples thereof include alkylene glycol dialkyl ethers such as tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, and tripropylene glycol dimethyl ether. Be done. These can control the wettability of the ink composition with respect to the recording medium.

Further, among the above-mentioned glycol ethers, diethers tend to dissolve or swell the resin in the ink more easily than monoethers, and are more preferable in that the scratch resistance of the formed image is improved. The content of glycol ethers in the ink is preferably 1% by mass or more and 30% by mass or less, more preferably 2% by mass or more and 20% by mass or less, and 3% by mass or more and 10% by mass or less. Is even more preferable.

Cyclic esters include β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, β-butyrolactone, β-valerolactone, γ-valerolactone, β-hexanolactone, and γ-hexanolactone. , Δ-Hexanolactone, β-Heptanolactone, γ-Heptanolactone, δ-Heptanolactone, ε-Heptanolactone, γ-Octanolactone, δ-Octanolactone, ε-Octanolactone, δ Cyclic esters (lactones) such as −nonalactone, ε-nonalactone, and ε-decanolactone, and compounds in which the hydrogen of the methylene group adjacent to their carbonyl group is replaced by an alkyl group having 1 to 4 carbon atoms. Can be done.

The total content of the organic solvent is preferably 1% by mass or more, preferably 3% by mass or more, more preferably 5% by mass or more, and 10% by mass or more with respect to the total mass of the ink composition. Is more preferable, and 15% by mass or more is particularly preferable. The total content of the organic solvent is preferably 40% by mass or less, more preferably 35% by mass or less, and further preferably 30% by mass or less with respect to the total mass of the ink composition. preferable. Further, it is more preferably 25% by mass or less, and particularly preferably 23% by mass or less. When the content of the organic solvent is within the above range, it is more excellent and preferable in terms of clogging resistance, image quality and abrasion resistance of the ink composition.

The standard boiling point of the organic solvent is preferably 180 ° C. or higher, more preferably 200 ° C. or higher, and even more preferably 210 ° C. or higher. The standard boiling point of the organic solvent is preferably 300 ° C. or lower, preferably 280 ° C. or lower, more preferably 270 ° C. or lower, and even more preferably 250 ° C. or lower. When the standard boiling point of the organic solvent is within the above range, it is more excellent and preferable in terms of clogging resistance, image quality and scratch resistance of the ink composition.

Since a polyol-based organic solvent having a standard boiling point of more than 280 ° C., such as triethylene glycol or glycerin, functions as a moisturizer, when it is contained, it suppresses the drying of the inkjet head and has excellent clogging resistance. On the other hand, a polyol-based organic solvent having a standard boiling point of more than 280 ° C. absorbs water in the ink composition to thicken the ink near the inkjet head or reduce the dryness of the ink when it adheres to a recording medium. In some cases. Therefore, in the present embodiment, the content of the polyol-based organic solvent having a standard boiling point of more than 280 ° C. is preferably 3% by mass or less based on the total mass of the ink composition. It is more preferably mass% or less, more preferably 1 mass% or less, further preferably 0.8 mass% or less, and particularly preferably 0.1 mass% or less. In this case, the drying property of the ink composition on the recording medium becomes high, so that the ink composition is particularly suitable for recording on a non-absorbent recording medium or a low-absorbency recording medium, and an image having excellent scratch resistance can be obtained. Be done. Furthermore, it is more preferable that the content of an organic solvent having a standard boiling point of more than 280 ° C. is in the above range, not limited to polyols, because an image having excellent scratch resistance can be obtained.

1.3.4. Resin In the present embodiment, the ink composition preferably contains a resin. The resin has an action of solidifying the ink composition and further firmly fixing the solidified ink on the recording medium. In the present embodiment, the resin may be in either a state of being dissolved in the ink composition or a state of being dispersed in the ink composition. As the resin in the dissolved state, the above-mentioned resin dispersant used when dispersing the pigment of the ink, or an organic solvent-soluble or water-soluble resin can be used. Further, as the resin in the dispersed state, a resin that is poorly soluble or insoluble in the liquid medium of the ink can be contained in the form of fine particles, that is, in an emulsion state or a suspension state.

The resin used in the present embodiment is not particularly limited, and for example, acrylic resin, vinyl acetate resin, vinyl chloride resin, butadiene resin, styrene resin, polyester resin, cross-linked acrylic resin, cross-linked styrene resin, benzoguanamine resin, and phenol resin. , Silicone resin, epoxy resin, urethane resin, paraffin resin, fluororesin, and water-soluble resin, and copolymers in which the monomers constituting these resins are combined. The copolymer is not particularly limited, and examples thereof include styrene butadiene resin, styrene acrylic resin, polyether polyurethane resin, and polyester polyurethane resin. Further, as the resin, a polymer latex containing these resins can be used. Examples thereof include polymer latex containing fine particles of acrylic resin, styrene acrylic resin, styrene resin, crosslinked acrylic resin, crosslinked styrene resin, and urethane resin. The resin may be used alone or in combination of two or more.

The acrylic resin is a resin which is a homopolymer or a copolymer obtained by polymerizing at least an acrylic monomer as a monomer. Examples of the acrylic monomer include (meth) acrylate, (meth) acrylic acid, acrylamide, acrylonitrile and the like. When the acrylic resin is a copolymer, an acrylic-vinyl resin using a vinyl-based monomer as another monomer can be mentioned, and a styrene acrylic resin using styrene as a vinyl-based monomer can be mentioned. Among these resins, acrylic resin, urethane resin, polyester resin and the like are preferable because they are easily available and can be easily obtained as a resin having desired characteristics.

The lower limit of the total resin content is preferably 1% by mass or more, more preferably 2% by mass or more, still more preferably 3% by mass, based on the total mass of the ink composition in terms of solid content. That is all. The upper limit of the resin content is preferably 15% by mass or less, more preferably 10% by mass or less, and further preferably 7% by mass or less, based on the total mass of the ink composition. When the resin content is within the above range, clogging resistance during recording is ensured, and an image having excellent image quality and abrasion resistance can be obtained even on a non-absorbent recording medium or a low-absorbency recording medium. Can be formed.

1.3.5. Surfactant In this embodiment, the ink composition preferably contains a surfactant. The surfactant is not particularly limited, and examples thereof include an acetylene glycol-based surfactant, a fluorine-based surfactant, and a silicone-based surfactant, and it is preferable to contain at least one of these, among these. It is more preferable to contain an acetylene glycol-based surfactant or a silicone-based surfactant. When the ink composition contains an acetylene glycol-based surfactant or a silicone-based surfactant, the dynamic surface tension of the ink can be lowered and the clogging resistance can be improved.

The acetylene glycol-based surfactant is not particularly limited, but for example, Surfinol 104, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 104S, 420, 440, 465, 485, SE, SE- F, 504, 61, DF37, CT111, CT121, CT131, CT136, TG, GA, DF110D (all product names, manufactured by Air Products Japan Co., Ltd.), Orfin B, Y, P, A, STG, SPC, E1004, E1010, PD-001, PD-002W, PD-003, PD-004, EXP. 4001, EXP. 4036, EXP. 4051, AF-103, AF-104, AK-02, SK-14, AE-3 (all product names above, manufactured by Nisshin Kagaku Kogyo Co., Ltd.), acetylenol E00, E00P, E40, E100 (all product names above, all product names, Kawaken Fine Chemical Co., Ltd.).

The silicone-based surfactant is not particularly limited, but a polysiloxane-based compound is preferably mentioned. The polysiloxane-based compound is not particularly limited, and examples thereof include polyether-modified organosiloxane. Commercially available products of the polyether-modified organosiloxane include, for example, BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348 (trade names, Big Chemie Japan Co., Ltd.). KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6020, X- 22-4515, KF-6011, KF-6012, KF-6015, KF-6017 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), Silface SAG503A, Silface SAG014 (trade name, Nisshin Chemical Industry Co., Ltd.) Made) and the like.

As the fluorine-based surfactant, it is preferable to use a fluorine-modified polymer, and specific examples thereof include BYK-340 (trade name, manufactured by Big Chemie Japan Co., Ltd.).

When a surfactant is contained, the content thereof is preferably 0.1% by mass or more and 1.5% by mass or less with respect to the total mass of the ink composition.

1.3.6. Wax In this embodiment, the ink composition may contain wax. Examples of the wax include those that dissolve in the ink composition and those that disperse in the form of fine particles such as emulsions. By using such a wax, it tends to be possible to obtain a recorded material having excellent image quality and abrasion resistance. In particular, it tends to contribute to the improvement of scratch resistance due to uneven distribution on the surface of the ink coating film on the recording medium, that is, at the interface between the air and the ink coating film. Such waxes are not particularly limited, and examples thereof include ester waxes of higher fatty acids and higher monohydric alcohols or dihydric alcohols, paraffin waxes, microcrystalline waxes or polyolefin waxes, or mixtures thereof.

Examples of the polyolefin wax include waxes produced from olefins such as ethylene, propylene and butylene or derivatives thereof and copolymers thereof, and specific examples thereof include polyethylene wax, polypropylene wax, polybutylene wax and the like. As the polyolefin wax, commercially available ones can be used. Specifically, Nopcoat PEM17 (trade name, manufactured by San Nopco Co., Ltd.), Chemipearl W4005 (trade name, manufactured by Mitsui Chemicals, Inc.), AQUACER515, AQUACER593. (The above product name, manufactured by Big Chemie Japan Co., Ltd.) can be used.

The content of the wax is preferably 0.1% by mass or more and 5% by mass or less, more preferably 0.2% by mass or more and 4% by mass or less, based on the total mass of the ink composition, and is 0. It is more preferably 3% by mass or more and 3% by mass or less. When the wax content is within the above range, the image quality and abrasion resistance are improved, the viscosity of the ink is lowered, and the ejection stability and the clogging recovery are excellent, which is preferable.

1.3.7. Defoaming agent The defoaming agent is not particularly limited, and examples thereof include a silicone-based defoaming agent, a polyether-based defoaming agent, a fatty acid ester-based defoaming agent, and an acetylene glycol-based defoaming agent. Commercially available antifoaming agents include BYK-011, BYK-012, BYK-017, BYK-018, BYK-019, BYK-020, BYK-021, BYK-022, BYK-023, BYK-024, BYK. -025, BYK-028, BYK-038, BYK-044, BYK-080A, BYK-094, BYK-1610, BYK-1615, BYK-1650, BYK-1730, BYK-1770 (Manufactured by Co., Ltd.), Surfinol DF37, DF110D, DF58, DF75, DF220, MD-20, Envilogem AD01 (all of the above are trade names, manufactured by Nissin Chemical Industry Co., Ltd.). The defoaming agent may be used alone or in combination of two or more.

The content of the defoaming agent is preferably 0.03% by mass or more and 0.7% by mass or less, and is 0.05% by mass or more and 0.5% by mass or less, based on the total mass of the ink composition. More preferably, it is more preferably 0.08% by mass or more and 0.3% by mass or less.

1.3.8. Other Ingredients In the present embodiment, the ink composition is used to maintain good storage stability and ejection stability of the inkjet head, to improve clogging, or to prevent deterioration of the ink. Dissolving aids, viscosity modifiers, pH adjusters, antioxidants, preservatives, antifungal agents, anticorrosive agents, non-organic moisturizers, and chelating agents for capturing metal ions that affect dispersion. Various additives such as, etc. can be added as appropriate.

1.3.9. Method for Preparing Ink Composition In the present embodiment, the ink is obtained by mixing the above-mentioned components in an arbitrary order and, if necessary, filtering or the like to remove impurities. As a method of mixing each component, a method of sequentially adding materials to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer and stirring and mixing them is preferably used. As the filtration method, centrifugal filtration, filter filtration and the like can be performed as needed.

1.3.10. Physical Properties of Ink Composition In this embodiment, the ink composition has a surface tension (static surface tension) of 18 mN / m or more and 40 mN at 20 ° C. from the viewpoint of a balance between image quality and reliability as an ink for inkjet recording. It is preferably 20 mN / m or more and 35 mN / m or less, and more preferably 22 mN / m or more and 33 mN / m or less. The surface tension is measured by, for example, using an automatic surface tension meter CBVP-Z (trade name, manufactured by Kyowa Interface Science Co., Ltd.) to measure the surface tension when the platinum plate is wetted with ink in an environment of 20 ° C. It can be measured by checking.

In the present embodiment, the viscosity of the ink at 20 ° C. is preferably 3 mPa · s or more and 10 mPa · s or less from the viewpoint of the balance between the image quality of the ink composition and the reliability of the ink for inkjet recording. -It is more preferable that it is s or more and 8 mPa · s or less. The viscosity can be measured by using, for example, a viscoelasticity tester MCR-300 (trade name, manufactured by Pysica) in an environment of 20 ° C.

1.4. Treatment Liquid Next, the treatment liquid used together with the above ink composition in the inkjet recording method according to the present embodiment will be described.

In the present embodiment, the treatment liquid is a water-containing composition that aggregates the components of the ink composition, and an aqueous treatment liquid is preferable. A composition containing a flocculant that aggregates the components of the ink composition is preferable. Examples of the ink component that reacts with the treatment liquid include a coloring material and a resin. The content of the above-mentioned coloring material in the treatment liquid is 0.2% by mass or less, preferably 0.1% by mass or less, more preferably 0.05% by mass or less, and the lower limit is 0% by mass. is there.
The treatment liquid is not the above-mentioned ink used for coloring the recording medium, but an auxiliary liquid used by adhering to the recording medium at the same time as the ink.

Adhering the ink and the treatment liquid at the same time means adhering to a predetermined area of the recording medium within the same scanning. The predetermined region is the band region 10b (see FIG. 2) described above, which extends in the main scanning axis direction of the recording medium and has a predetermined width in the sub scanning axis direction. That is, when the above-mentioned ink ejection nozzle group and processing liquid ejection nozzle group are projected along the main scanning axis, the ink ejection nozzle group and the processing liquid ejection nozzle group have an overlapping region along the sub-scanning axis. This is the case.

The treatment liquid can contain components other than the coloring material that may be contained in the above-mentioned ink composition, and their contents, characteristics, composition, and the like can be the same as those of the above-mentioned ink composition. It can be independent of the ink composition. In the present embodiment, an image having excellent image quality can be recorded by using the processing liquid. On the other hand, the use of the treatment liquid may reduce the scratch resistance and clogging resistance of the obtained image.

1.4.1. Water The treatment liquid used in this embodiment is an aqueous composition using water as a main solvent. This water is a component that evaporates and scatters due to drying after the treatment liquid is attached to the recording medium. As the water, it is preferable that ionic impurities such as pure water such as ion-exchanged water, ultra-filtered water, reverse osmosis water, and distilled water or ultrapure water are removed as much as possible. Further, it is preferable to use water sterilized by irradiation with ultraviolet rays or addition of hydrogen peroxide because the growth of mold and bacteria can be prevented when the treatment liquid is stored for a long period of time. The content of water contained in the treatment liquid can be, for example, 40% by mass or more, preferably 50% by mass or more, and more preferably 60% by mass or more, based on the total mass of the treatment liquid. , More preferably 70% by mass or more.

1.4.2. Coagulant The treatment liquid used in the present embodiment preferably contains a coagulant that coagulates the components of the ink composition. When the treatment liquid contains a coagulant, the coagulant and the coloring material, resin, or the like contained in the ink composition react rapidly in the ink adhesion step described later. Then, the dispersed state of the color material and the resin in the ink composition is destroyed and aggregated, and the aggregates hinder the flow of the color material on the recording medium, which is excellent in improving the image quality of the recorded image. It is considered to be a thing.

Examples of the flocculant include polyvalent metal salts, cationic polymers, cationic compounds such as cationic surfactants, and organic acids. These flocculants may be used alone or in combination of two or more. Among these coagulants, at least one coagulant selected from the group consisting of polyvalent metal salts, organic acids, and cationic polymers is used because it has excellent reactivity with the components contained in the ink composition. Is preferable.

The polyvalent metal salt is a compound that is composed of divalent or higher polyvalent metal ions and anions that bind to these polyvalent metal ions and is soluble in water. Specific examples of polyvalent metal ions include divalent metal ions such as Ca ²⁺ , Cu ²⁺ , Ni ²⁺ , Mg ²⁺ , Zn ²⁺ , and Ba ²⁺ ; and trivalent metal ions such as Al ³⁺ , Fe ³⁺ , and Cr ^3+. Be done. Anions include Cl ⁻ , I ⁻ , Br ⁻ , SO ₄ ^2- , ClO ^3- , NO ^3- , and HCOO ⁻ , CH ₃ COO ^{− and the} like. Among these polyvalent metal salts, calcium salt and magnesium salt are preferable from the viewpoint of stability of the treatment liquid and reactivity as a flocculant.

Examples of organic acids include phosphoric acid, polyacrylic acid, acetic acid, glycolic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid, tartaric acid, lactic acid, sulfonic acid, and the like. Ortholic acid, pyrrolidone carboxylic acid, pyron carboxylic acid, pyrrol carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumarin acid, thiophene carboxylic acid, nicotinic acid, derivatives of these compounds, salts thereof and the like are preferably mentioned. .. The organic acid may be used alone or in combination of two or more. Salts of organic acids that are also polyvalent metal salts shall be included in the polyvalent metal salts.

Examples of the cationic polymer include a cationic urethane resin, a cationic olefin resin, a cationic amine resin, and a cationic amide resin. The cationic amine resin may be any resin having an amino group, and examples thereof include allylamine resins, polyamine resins, and quaternary ammonium salt polymers. Examples of the polyamine resin include those having an amino group in the main skeleton of the resin. Examples of the allylamine resin include those having a structure derived from an allyl group in the main skeleton of the resin. Examples of the quaternary ammonium salt polymer include resins having a quaternary ammonium salt in the structure. Among the cationic polymers, the cationic amine resin is preferable because it is not only excellent in reactivity but also easily available.

The concentration of the coagulant in the treatment liquid is preferably 0.5% by mass or more, more preferably 1% by mass or more, and further preferably 3% by mass or more, based on the total mass of the treatment liquid. .. The concentration of the flocculant in the treatment liquid is preferably 20% by mass or less, more preferably 15% by mass or less, and further preferably 10% by mass or less, based on the total mass of the treatment liquid. ..

14.3. Organic solvent The treatment liquid used in this embodiment may contain an organic solvent. By containing an organic solvent, the wettability of the treatment liquid with respect to the recording medium can be improved. As the organic solvent, the same organic solvent as those exemplified in the above-mentioned ink composition can be used. The content of the organic solvent is not particularly limited, but can be, for example, 10% by mass or more and 80% by mass or less, preferably 15% by mass or more and 70% by mass, based on the total mass of the treatment liquid. It is as follows.

The standard boiling point of the organic solvent is contained in a temperature within a preferable range of the standard boiling point of the organic solvent which may be contained in the above-mentioned ink composition, independently of the standard boiling point of the organic solvent which may be contained in the ink composition. can do. Alternatively, the standard boiling point of the organic solvent is preferably 180 ° C. or higher, more preferably 190 ° C. or higher, and even more preferably 200 ° C. or higher. The standard boiling point of the organic solvent is preferably 300 ° C. or lower, more preferably 270 ° C. or lower, and even more preferably 250 ° C. or lower.

As the organic solvent, the treatment liquid preferably has a content of a polyol-based organic solvent having a standard boiling point of more than 280 ° C. of 5% by mass or less, and is preferably 3% by mass or less, similar to the above-mentioned ink composition. More preferably, it is more preferably 2% by mass or less, further preferably 1% by mass or less, further preferably 0.8% by mass or less, and preferably 0.1% by mass or less. Especially preferable. In the above case, since the treatment liquid has good drying property, the treatment liquid is dried quickly. Further, since the ink composition becomes highly dry on the recording medium, it is particularly suitable for recording on a non-absorbent recording medium or a low-absorbency recording medium, and an image having excellent scratch resistance can be obtained. Furthermore, it is more preferable that the content of an organic solvent having a standard boiling point of more than 280 ° C. is in the above range, not limited to polyols, because an image having excellent scratch resistance can be obtained.

1.4.4. Surfactant A surfactant may be added to the treatment liquid used in the present embodiment. By adding a surfactant, the surface tension of the treatment liquid can be reduced and the wettability with the recording medium can be improved. Among the surfactants, for example, the above-mentioned acetylene glycol-based surfactants, silicone-based surfactants, and fluorine-based surfactants can be preferably used. As specific examples of these surfactants, the same surfactants as those exemplified in the above-mentioned ink composition can be used. The content of the surfactant is not particularly limited, but can be 0.1% by mass or more and 5.0% by mass or less with respect to the total mass of the treatment liquid.

1.4.5. Other Ingredients The above-mentioned pH adjuster, preservative / antifungal agent, rust preventive, chelating agent and the like may be added to the treatment liquid used in the present embodiment, if necessary.

1.4.6. Method for preparing the treatment liquid The treatment liquid used in the present embodiment can be produced by dispersing and mixing each of the above components by an appropriate method. After sufficiently stirring each of the above components, filtration is performed to remove coarse particles and foreign substances that cause clogging, and a desired treatment liquid can be obtained.

1.4.7. Physical Properties of Treatment Liquid When the treatment liquid used in this embodiment is discharged by an inkjet head, the surface tension (static surface tension) at 20 ° C. is preferably 18 mN / m or more and 40 mN / m, preferably 20 mN. It is more preferably / m or more and 35 mN / m or less, and further preferably 22 mN / m or more and 33 mN / m or less. For the measurement of surface tension, for example, using an automatic surface tension meter CBVP-Z (trade name, manufactured by Kyowa Interface Science Co., Ltd.), the surface tension when the platinum plate is wetted with the treatment liquid in an environment of 20 ° C. is confirmed. It can be measured by doing.

In the present embodiment, the viscosity of the treatment liquid at 20 ° C. is preferably 3 mPa · s or more and 10 mPa · s or less from the viewpoint of the balance between the image quality and the reliability as the treatment liquid for inkjet recording. It is more preferably 8 mPa · s or less. The viscosity can be measured by using, for example, a viscoelasticity tester MCR-300 (trade name, manufactured by Pysica) in an environment of 20 ° C.

1.5. Recording medium In the present embodiment, since the water-based ink and the treatment liquid are combined and recorded by a predetermined recording method, an image having excellent image quality is recorded on a non-absorbent recording medium or a low-absorbency recording medium. Can be done. This recording is performed with the ink composition by two or more main scans in the band region 10c corresponding to the length of one sub-scan in the recording region 10a of the non-absorbent or low-absorbent recording medium 10. Adhere the liquid.

Examples of the non-absorbent recording medium include those that have not been surface-treated for inkjet recording, that is, those in which plastic is coated on a base material such as a plastic film or paper that does not form an ink absorbing layer, or plastic. Examples thereof include those to which a film is adhered. Examples of the plastic referred to here include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene and the like.

Examples of the low-absorption recording medium include a recording medium having a coating layer provided on the surface for receiving ink. For example, a recording medium whose base material is paper includes art paper, coated paper, and matte. Printing of paper, etc. When this paper is a plastic film, the surface of polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, etc. is coated with a hydrophilic polymer. , Silica, titanium and other particles are coated together with a binder.

Here, the term "non-absorbable recording medium or low-absorbent recording medium" as used herein means that the amount of water absorbed from the start of contact to 30 msec ^1/2 in the "Bristow method" is 10 mL / m ² or less. "Recording medium" is shown. This Bristow method is the most popular method for measuring the amount of liquid absorbed in a short time, and is also adopted by the Japan Pulp and Paper Technology Association (JAPAN TAPPI). For details of the test method, refer to the standard No. of "JAPAN TAPPI Pulp and Paper Test Method 2000 Edition". It is described in 51 "Paper and Paperboard-Liquid Absorption Test Method-Bristow Method".

These recording media may be a translucent recording medium or a transparent recording medium. It can also be suitably used for non-absorbent recording media or low-absorbency recording media having irregularities on the surface such as embossed media.

2. 2. Inkjet Recording Method In the present embodiment, the inkjet recording method is a serial type recording method in which the above-mentioned ink composition and treatment liquid are used and recording is performed by a plurality of main scans. Specifically, in the inkjet recording method according to the present embodiment, in recording, the ink composition is recorded while moving the inkjet head 2 including the ink ejection nozzle group 15 and the processing liquid ejection nozzle group 16 along the main scanning axis MS. The main scan for ejecting the ink and the processing liquid and the sub-scan for moving the recording medium 10 along the sub-scan axis SS intersecting the main scan axis are performed, and the length of one sub-scan is the ink ejection nozzle. The band region 10b, which is shorter than the length in the sub-scan axis direction of the group 15 and corresponds to the length of one sub-scan in the recording region 10a of the recording medium 10, is treated with the ink composition by two or more main scans. Adhere the liquid.

In the case of the serial type recording method, the number of main scans of the ink composition is the ink ejection nozzle group 15 with respect to a predetermined region of the recording region 10a of the recording medium 10, for example, one point of the band region 10b described above. Refers to the number of main scans that pass through facing each other. For example, when a predetermined nozzle group of the ink ejection nozzle group 15 of FIG. 3 is filled and this nozzle group is used for recording, the length of one sub-scan is the length in the sub-scan axis direction of the nozzle group. If it is half the length, the number of main scans of the ink is two. The number of main scans can be increased by shortening the length of one sub-scan, and can be reduced by increasing the length.

The number of main scans is also called the number of passes. The larger the number of main scans, the larger the total amount of the composition to be adhered, which is preferable. Further, since the drying property and the image quality are improved by adhering the ink composition separately in a plurality of main scans, it is preferable that the number of main scans is large. On the other hand, when the number of main scans is small, the recording speed becomes high, which is preferable. In the present embodiment, the number of main scans is the number of main scans when the ink ejection nozzle group 15 is considered as the ejection nozzle group actually used for recording. The number of main scans is preferably 2 or more and 25 or less, more preferably 3 or more and 20 or less, and further preferably 4 or more and 16 or less.

In the present embodiment, the inkjet recording method includes an ink adhesion step of adhering the ink composition to the recording medium 10 by the above-mentioned main scanning and a processing liquid adhering step of adhering the treatment liquid to the recording medium 10 by the above-mentioned main scanning. It has a heating step (primary heating step) and a secondary heating step as needed.

2.1. Treatment Liquid Adhesion Step The treatment liquid adhesion step is a step of adhering the above-mentioned treatment liquid that reacts with the ink composition to the recording medium 10. In the present embodiment, recording is performed using a treatment liquid, and further, by satisfying the following (Equation 1) and (Equation 2), the ink composition is aggregated to suppress the occurrence of bleeding and the like, and an image having excellent image quality is obtained. Obtainable.

In the present embodiment, the treatment liquid adhesion step is performed at the same time as the adhesion of the ink composition. As described above, "simultaneously" means that the treatment liquid is adhered to a predetermined region of the recording medium 10, for example, the band region 10b by the same main scan. In addition, "not at the same time" means that the ink composition is adhered to a predetermined region of the recording medium by the main scan, and the treatment liquid is adhered to the region by another main scan. In the present embodiment, when the ink composition and the treatment liquid are adhered at the same time, banding unevenness and aggregation unevenness resulting from recording with uneven paths by satisfying the following (Equation 1) and (Equation 2) are satisfied. It is possible to obtain an image with excellent image quality.

That is, in the present embodiment, in a certain main scanning, the ejection amount of the first ink nozzle portion is the ejection amount of the first ink nozzle portion, the ejection amount of the first processing liquid nozzle portion is the ejection amount of the first processing liquid nozzle portion, and the second. The following (Equation 1) and (Equation 2) are satisfied when the ejection amount of the ink nozzle portion is defined as the ejection amount of the second ink nozzle portion and the ejection amount of the second processing liquid nozzle portion is defined as the ejection amount of the second processing liquid nozzle portion. ..
First ink nozzle discharge amount <Second ink nozzle discharge amount ... (Equation 1)
(Discharge amount of 1st treatment liquid nozzle / Discharge amount of 1st ink nozzle)> (Discharge amount of 2nd treatment liquid nozzle / Discharge amount of 2nd ink nozzle) ... (Equation 2)

As described above, in the present embodiment, the processing liquid nozzle located side by side with the ink nozzle having a low ink ejection amount in a certain main scan is compared with the processing liquid nozzle located side by side with the ink nozzle having a high ejection amount. , Increase the discharge amount of the processing liquid nozzle with respect to the discharge amount of the ink nozzle. By setting the ejection amount of the ink and the processing liquid in this way, it is possible to obtain an image having excellent image quality.

Here, the ejection amount in a certain main scan is indicated by the mass of the ink composition or the treatment liquid adhering to each unit area in the recording medium, and the unit is indicated by, for example, mg / inch ² . That is, it is the mass of the processing liquid discharged so as to adhere to each unit area of the recording medium in one main scan. When representing the discharge amount of a nozzle portion composed of a plurality of nozzles, it is the average discharge amount of the nozzle portion.

The ejection amount and recording density of the treatment liquid may be smaller than those of the ink composition, and if the ejection amount of the treatment liquid is too small, drying may proceed and the cohesive agent may precipitate to reduce the cohesive force. Further, when the contact probability between the treatment liquid and the ink on the recording medium is extremely lowered, the ink dots may gather together with the adjacent ink dots to cause uneven aggregation.

Therefore, the first ink ejection unit, which has a smaller ejection amount than the second ink ejection portion, sets the ejection amount of the treatment liquid of the first treatment liquid nozzle portion to the ink ejection amount of the first ink nozzle portion, and sets the ejection amount of the treatment liquid in the second ink nozzle portion. The amount of the ink ejected from the second processing liquid nozzle is larger than the amount of the processing liquid ejected. By doing so, the contact probability between the ink dots and the processing liquid dots in a certain main scan increases even in the first ink ejection section where the discharge amount is small and in the area of the recording medium where the ink dots are recorded in a certain main scan. It is possible to prevent the occurrence of uneven aggregation.

In addition, in-plane color difference deterioration may be seen in the image. For example, at the end of the recording area 10a of the recording medium 10 in the main scanning direction, after printing by the main scanning, sub-scanning is immediately performed, and then printing is performed by the main scanning. At this time, there is almost no drying time in the overlapping print areas, but there is a drying time after each scanning in the central portion, which causes a difference in the drying properties of the treatment liquid and the ink. As a result, when recording with a plurality of color inks, a color difference may occur due to a difference in the degree of color mixing and aggregation.

In the present embodiment, by setting the discharge amount of the processing liquid to satisfy the above (Equation 1) and (Equation 2), the contact probability between the processing liquid and the ink is secured, and an image having excellent image quality is obtained. Can be done. Further, it is preferable to set as described above in terms of reducing the in-plane color difference. Furthermore, it is possible to obtain an image having excellent scratch resistance, which is preferable.

On the other hand, if the discharge amount of the treatment liquid is too large, the amount of the liquid on the recording medium becomes large, the drying property deteriorates, and the abrasion resistance may decrease. Further, when a small amount of ink is dropped in a large amount of processing liquid, over-aggregation occurs, and since the dots do not spread, pinholes occur and it becomes difficult to obtain excellent image quality. Therefore, as will be described later, the image quality is ensured by setting the discharge amount and the like within a predetermined range.

In the present embodiment, the discharge amount of the treatment liquid in a certain main scan is (the discharge amount of the first treatment liquid nozzle portion / the first ink nozzle) with respect to (the discharge amount of the second treatment liquid nozzle portion / the discharge amount of the second ink nozzle portion). The partial discharge amount) is more than 1, preferably 1.3 or more and 4 or less, more preferably 1.5 or more and 3 or less, and further preferably 2 or more and 2.5 or less.

(Discharge amount of the second processing liquid nozzle portion / ejection amount of the second ink nozzle portion) is preferably 0.1 or more and 0.5 or less.

(Emission amount of the first treatment liquid nozzle portion / ejection amount of the first ink nozzle portion) is preferably 0.1 or more and 2 or less, more preferably 0.3 or more and 1 or less, and further preferably 0.4 or more and 0.8 or less. ..

For example, in the present embodiment, the discharge amount of the treatment liquid per droplet is preferably 4 ng or more, preferably 10 ng or more, and preferably 14 ng or more. The amount of the treatment liquid discharged per droplet is preferably 25 ng or less, preferably 20 ng or less, and preferably 18 ng or less. By setting the discharge amount of the treatment liquid in the above range, the contact probability between the treatment liquid and the ink can be further secured, and an image with better image quality can be obtained. Furthermore, an image having excellent scratch resistance can be obtained.

In the present embodiment, in the region for recording on the recording medium, it is preferable to have a region in which the total ejection amount of the treatment liquid is 10% by mass or more of the ejection amount of the ink composition, and the region is 15% by mass or more. It is more preferable to have a region of 20% by mass or more. Further, the total ejection amount of the treatment liquid preferably has a region of 50% by mass or less, more preferably 40% by mass or less, and 35% by mass or less of the ejection amount of the ink composition. It is more preferable to have a certain region. When the processing liquid ejection amount with respect to the ink ejection amount is within the above range, better image quality can be obtained with respect to the non-absorbent recording medium or the low-absorbency recording medium, and further, the scratch resistance of the obtained image can be obtained. It is possible to prevent deterioration of sex.

Here, the treatment liquid ejection amount with respect to the ink ejection amount is a predetermined value means that the processing liquid adhesion amount with respect to the ink adhesion amount is a predetermined value in the adhesion region where the ink and the processing liquid adhere to each other on the recording medium. Means having at least a region. Preferably, in the adhesion region where the ink adhesion amount is maximum in the adhesion region, the treatment liquid adhesion amount with respect to the ink adhesion amount is preferably in the above range. Alternatively, it is preferable that the amount of the treatment liquid adhered to the amount of ink adhered is in the above range in the region where the amount of the treatment liquid adhered to the amount of ink adhered is maximum in the adhered region.

The recording density of the treatment liquid dots is preferably 300 dpi × 300 dpi or more, preferably 600 dpi × 600 dpi or more, and preferably 720 dpi × 720 dpi or more. When the recording density is equal to or higher than the above range in the amount of the treatment liquid adhered, the wett spread of the ink composition and the treatment liquid is adjusted, which is better than the non-absorbent recording medium or the low-absorbency recording medium. High image quality can be obtained, and further, deterioration of scratch resistance of the obtained image can be prevented.

It is preferable that the recording medium 10 is heated by a heating mechanism such as the preheater 7 shown in FIG. 1 before the treatment liquid adhesion step, or by the heating mechanism shown in FIG. 1 during the treatment liquid adhesion step. By adhering the treatment liquid on the heated recording medium 10, the treatment liquid and ink discharged on the recording medium 10 can be easily spread and spread on the recording medium 10, and the treatment liquid and ink can be uniformly applied. .. Therefore, the ink and the treatment liquid react sufficiently, and excellent image quality can be obtained. Further, since the water content of the treatment liquid and the ink evaporates on the recording medium 10, the fluidity is lowered and the deterioration of the image quality such as unevenness can be suppressed.

Here, the surface temperature of the recording medium 10 when the treatment liquid is adhered is preferably 45 ° C. or lower, more preferably 40 ° C. or lower, and further preferably 38 ° C. or lower. Further, the lower limit of the surface temperature of the recording medium 10 when the treatment liquid is adhered is preferably 20 ° C. or higher, more preferably 25 ° C. or higher, and further preferably 30 ° C. or higher. When the surface temperature of the recording medium 10 when the treatment liquid is adhered is within the above range, the treatment liquid can be uniformly applied to the recording medium 10, and the abrasion resistance and the image quality can be improved. In addition, the influence of heat on the inkjet head 2 can be suppressed. In the present embodiment, since the ink and the treatment liquid are adhered at the same time, it is preferable that the surface temperature of the recording medium 10 at the time of adhering the ink is also in the above range.

2.2. Ink Adhesion Step The ink adhesion step is a step of ejecting the above-mentioned ink composition from the inkjet head 2 and ejecting it onto a non-absorbent or low-absorbency recording medium 10 to adhere it. More specifically, it is a step of adhering the ink composition to the band region 10b corresponding to the length of one sub-scan in the recording region 10a of the recording medium 10 by two or more main scans.

In the present embodiment, the ink adhesion step satisfies the above-mentioned (Equation 1) and (Equation 2) in a certain main scan.

In the present embodiment, since recording is performed so as to satisfy the above (Equation 1), the amount of ink adhered to the recording medium is unevenly adhered to the recording medium by two or more main scans. As described above, when the ink is unevenly adhered to the recording medium, there are a main scan in which the dot generation rate (also referred to as “dot density”) of the ink droplets adhered to a certain place is high and a main scan in which the ink is low. Further, in a certain main scanning performed by using the nozzle group, there are a nozzle portion having a high dot generation rate of ink droplets and a nozzle portion having a low dot generation rate in the nozzle group. A nozzle portion having a high dot generation rate of ink droplets in one main scan, that is, a nozzle portion having a low dot generation rate in another main scan, that is, a first ink is attached to a region where ink droplets are adhered by the second ink nozzle portion 15a. By adhering the ink droplets on the nozzle portion 15b, the amount of ink adhering to the final image can be adjusted according to the image to be recorded.

By doing so, for example, in order to lower the dot generation rate in the first ink nozzle portion 15b and adhere the ink, the first ink nozzle portion 15b ejects per ink droplet as compared with the second ink nozzle portion 15a. Even if the accuracy of the mass and the accuracy of the landing position of the ink droplets are inferior, it is possible to suppress these effects on the entire image and suppress the pixel deterioration due to these.

For example, banding unevenness of an image may occur in the recorded area due to various mechanical factors such as variations in sub-scanning accuracy and variations in printing accuracy. In particular, in each nozzle group of FIG. 3, a portion near the upper end or a portion near the lower end in the SS axis direction may be more prone to banding unevenness or the like than a portion near the center in the SS axis direction. As various mechanical factors, for example, when the head is installed on the carriage, the head is installed by rotating around the MS axis in FIG. 3 and tilted, or on an axis extending toward the front in the figure of FIG. On the other hand, there is a case where the installation is tilted by rotating clockwise or counterclockwise.

Of the nozzle group, the part near the upper end and the part near the lower end in the SS axis direction have a larger pressure generated during ink ejection in the pressure chamber for ejecting ink than the portion near the center in the SS axis direction. The accuracy of the ink may be inferior. In that case, the accuracy of the ejection amount per ink droplet and the accuracy of the landing position of the ink droplet are lowered in the portion near the upper end and the portion near the lower end in the SS axis direction.

Of the nozzle group, the ink droplets ejected from the portion near the upper end or the lower end in the SS axis direction are affected by the wind and the landing position shifts as compared with the ink droplets ejected from the portion near the center in the SS axis direction. Is likely to grow.

In such a case, the ejection amount in the main scan with the first ink nozzle group belonging to the portion near the upper end or the portion near the lower end in the SS axis direction is set to the ejection amount in the main scan with the second ink nozzle group belonging to the portion near the center. It is less than the discharge amount in. By doing so, it is possible to reduce banding unevenness and improve the image quality as compared with the case where the ejection amount of the first ink nozzle group and the ejection amount of the second ink nozzle group in a certain main scan are the same.

The decrease in the accuracy of the ejection amount per ink droplet and the accuracy of the landing position of the ink droplet due to mechanical factors is not limited to the above. Therefore, the relationship between the positions of the first ink nozzle group and the second ink nozzle group is not limited to the above. For example, in the nozzle group, the portion near the center in the SS axis direction may reduce the accuracy of the ejection amount per ink droplet and the accuracy of the landing position of the ink droplet. For example, in the portion near the center of the nozzle group, the heat generated by driving the head is difficult to escape, so that the temperature of the head becomes high and the accuracy of the ink droplet ejection amount may decrease. In such a case, it is preferable to provide the first ink nozzle group in a portion near the center in the SS axis direction and provide the second ink nozzle portion in a portion farther from the center than the first ink nozzle portion.

The reason for providing the first ink nozzle group and the second ink nozzle group is not limited to mechanical factors. For example, by providing the first ink nozzle group having a small ejection amount and the second ink nozzle group having a large ejection amount, the image quality is more excellent, the recording speed is relatively high, and the balance between the image quality and the recording speed is excellent. You can record the image.

In the present embodiment, in a recording method in which the ink ejection nozzle group 15 and the processing liquid ejection nozzle group 16 are simultaneously ejected side by side, the ejection amount of the processing liquid nozzle corresponds to the ejection amount of a certain ink nozzle in a certain main scanning. Is also adjusted so that the amount of ink adhered unevenly to the recording medium. In the present embodiment, by setting the dot generation rate of the processing liquid nozzle so as to satisfy the above (Equation 1) and (Equation 2), the droplets of the processing liquid can easily react with the first ink nozzle portion as well. Banding unevenness is suppressed and image quality is improved.

In the present embodiment, in a certain main scanning, the ejection amount of the second ink nozzle portion is the maximum in the ink ejection nozzle group 15, and the ejection amount of the first ink nozzle portion is 30 of the ejection amount of the second ink nozzle portion. It is preferably 5% by mass or less, more preferably 25% by mass or less, and further preferably 20% by mass or less. Here, the maximum ejection amount means that the ink ejection nozzle group 15 is divided into nozzle portions having the same number of nozzles as the number of nozzles of the second ink nozzle portion 15a, and the ejection amount of each nozzle portion is focused on. 2 It means that the ejection amount of the ink nozzle portion 15a is the largest. For example, when the number of nozzles of the second ink nozzle portion 15a is 30, the ink ejection nozzle group 15 is divided into the nozzle portions of 30 nozzles each, and attention is paid to the ejection amount for each nozzle portion. However, if the nozzles remain, they are treated as less than 30 nozzles.

Further, in the present embodiment, (the discharge amount of the first treatment liquid nozzle / the discharge amount of the first ink nozzle) is 1.5 or more with respect to (the discharge amount of the second treatment liquid nozzle / the second ink nozzle). It is preferably 30 or less, more preferably 1.8 or more and 2.5 or less, more preferably 1.8 or more and 2.3 or less, and preferably 2.0 or more and 2.2 or less. More preferred. By being in the above range, the image quality is further improved.

Further, in the present embodiment, (second processing liquid nozzle portion ejection amount / second ink nozzle portion ejection amount) is preferably 0.1 or more and 0.5 or less, and 0.2 or more and 0.4 or less. More preferably. By being in the above range, the image quality is further improved.

(Emission amount of the first treatment liquid nozzle portion / ejection amount of the first ink nozzle portion) is preferably 0.1 or more and 1.0 or less, more preferably 0.3 or more and 0.6 or less, and is 0. More preferably, it is 5.5 or more and 0.7 or less. By being in the above range, the image quality is further improved.

In the present embodiment, it is preferable that the ejection amount gradually decreases from one end of the first ink nozzle portion 15b toward the other end. By adjusting the ink ejection amount of the first ink nozzle portion 15b in this way, the image quality is further improved.

Further, in the present embodiment, the number of main scans for ejecting the treatment liquid is smaller than the number of main scans for ejecting the ink composition to the band region 10b, and the ink composition is ejected for the band region 10b. It is preferable that the main scan for discharging the processing liquid is completed earlier than the main scan for discharging the processing liquid. In this way, by adhering the treatment liquid before adhering the ink, the treatment liquid dries during the main scanning, so that the image quality is further improved.

The ejection amount of the ink ejection nozzle group 15 is preferably the amount of adhesion of a certain main scan when a predetermined single density image is recorded on the recording medium 10. That is, when a solid image having a single density is recorded, the ejection amount of the ink ejection nozzle group 15 may be the amount of adhesion of a certain main scan when a predetermined single density image is recorded on the recording medium 10. preferable.

In FIG. 3, the processing liquid ejection nozzle group is arranged at both left and right ends in the direction of the MS axis in FIG. 3, and the ink ejection nozzle group is arranged between them, or the processing liquid ejection nozzle group is arranged in the direction of the MS axis in FIG. It is preferable to arrange the ink ejection nozzles in the center of the surface and to arrange the ink ejection nozzles on both the left and right sides thereof. By doing so, it is possible to align the order of adhesion of the treatment liquid and ink in the first main scan performed in the first direction and the second main scan performed in the second direction. In this case, since the order of adhesion of the treatment liquid and the adhesion of the ink is always the same, the occurrence of color banding is suppressed without causing a difference in color development due to the order of coloring, and the image quality is further improved. Here, when a plurality of ink ejection nozzle groups of the same color are arranged as necessary so that the inks are symmetrical on the left and right in the direction of the MS axis in FIG. 3, the order of adhesion between the inks is also the first main. The order of the scan and the second main scan is aligned, which is more preferable.

The maximum amount of the ink composition adhered to the recording medium 10 per unit area in recording is not particularly limited as long as the above conditions are satisfied, but is preferably 5 mg / inch ² or more, and more preferably 7 mg / inch ² or more. It is more preferably 10 mg / inch ² or more. The upper limit of the adhesion amount of the ink composition per unit area of the recording medium is, for example, preferably 20 mg / inch ² or less, preferably 18 mg / inch ² or less, and particularly preferably 16 mg / inch ² or less. The maximum adhesion amount of the ink composition is the total of the adhesion amounts of all the ink compositions to be adhered.

The ink adhesion step may include a heating step of heating the recording medium 10 before the ink adhesion step or at the same time as the ink adhesion step as described above, and the main scanning to the recording medium 10 heated by the heating step. Is preferable. The heating step is preferably blowing hot air from the IR heater 3, the platen heater 4, or a fan to the recording medium. By the heating step, the ink can be quickly dried on the recording medium 10 and bleeding is suppressed. In addition, it is possible to form an image having excellent image quality and abrasion resistance. The temperature of the nozzle surface when the ink adheres to the recording medium 10 may be raised due to heat generation of a recording device such as the inkjet head 2 itself, or may be affected by the heat of the heating step. It may be the one received.

2.3. Secondary heating step The inkjet recording method according to the present embodiment is a secondary heating step (“post-heating step” in which the recording medium 10 to which the ink composition is adhered is heated by the heating heater 5 shown in FIG. 1 after the ink adhesion step. It may also have.). As a result, the resin and the like contained in the ink composition on the recording medium 10 are melted to form an ink coating film, and the ink coating film is firmly fixed on the recording medium 10 to have excellent film forming property. High-quality images with excellent scratch resistance can be obtained in a short time.

The upper limit of the surface temperature of the recording medium 10 by the heater 5 is preferably 120 ° C. or lower, more preferably 110 ° C. or lower, and even more preferably 100 ° C. or lower. The lower limit of the surface temperature of the recording medium 10 is preferably 60 ° C. or higher, more preferably 70 ° C. or higher, and even more preferably 80 ° C. or higher. When the temperature is in the above range, the ink coating film is surely formed, so that a high-quality image having excellent scratch resistance can be obtained in a short time.

After the secondary heating step, the cooling fan 6 shown in FIG. 1 may have a step of cooling the ink composition on the recording medium 10.

2.4. Other Steps The recording method according to the present embodiment is not a mechanism for ejecting ink for recording provided by the inkjet head 2, that is, by means other than the pressure generating means for ejecting and recording ink. The mechanism may include a step of circulating the ink composition and the treatment liquid, and a cleaning step of discharging the ink composition.

Examples of the mechanism for ejecting ink for recording included in the inkjet head 2 include a piezo element and a heater element provided in a pressure chamber (not shown) to apply pressure to the ink. This cleaning step may be a step of applying pressure to the inkjet head 2 from the outside to discharge the ink composition or the treatment liquid from the nozzle. By providing this step, even when there is a concern that the resin is welded to the inner wall of the inkjet head 2, this can be suppressed and the ejection stability can be further improved.

Examples of the other mechanism described above include a mechanism for applying a negative pressure, a mechanism for applying a positive pressure from the upstream of the inkjet head, and the like. These are not ink ejection, that is, flushing, due to the function of the inkjet head itself. That is, it is not the discharge using the function of ejecting ink from the inkjet head at the time of recording.

As described above, in the inkjet recording method according to the present embodiment, in recording on a non-absorbent recording medium or a low-absorbency recording medium using a water-based ink and a treatment liquid, as described above, (formula 1) and (formula 1) and (formula) By satisfying 2), the image quality is improved.

3. 3. Examples Hereinafter, embodiments of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present embodiments are not limited to these Examples.

3.1. Preparation of treatment liquid and ink Each component was mixed and stirred with a bead mill so as to have the blending ratios shown in Tables 1 and 2, and filtered through a membrane filter having a pore size of 5 μm to obtain inks 1 to 12 and treatment liquids 1 to 4. .. The pigment was used after being prepared into a pigment dispersion liquid dispersed in water using a water-soluble styrene acrylic dispersant resin in an amount of 50% by mass based on the pigment. The values in Tables 1 and 2 all show mass%, and water was added so that the total mass of the ink and the treatment liquid was 100% by mass. The values of the pigments, resins and waxes shown in Table 1 and the cationic resins shown in Table 2 in terms of solid content are shown.

Details of the substances listed in Tables 1 and 2 are as follows.
Wax emulsion: trade name "AQUACER507", water-based modified paraffin wax emulsion, manufactured by Big Chemie Japan Co., Ltd. Surfactant 1: silicone-based surfactant, trade name "BYK-348", manufactured by Big Chemie Japan Co., Ltd. 2: Fluorine-based surfactant, trade name "Capstone FS-30 (25% aqueous solution)", DuPont surfactant 3: Silicone-based surfactant, trade name "BYK-333", manufactured by Big Chemie Japan Co., Ltd. Defoamer: acetylene diol-based surfactant, trade name "Surfinol DF110D", manufactured by Nisshin Kagaku Kogyo Co., Ltd. Cationic resin: amine / epichlorohydrin condensation type polymer, trade name "Catiomaster PD-7", Yokkaichi Synthetic Co., Ltd. Made

The styrene acrylic resin emulsion is for emulsion polymerization in which the total amount of the monomers of the copolymer having a ratio of styrene / acrylic acid / methyl methacrylate / cyclohexyl methacrylate of 75 / 0.5 / 0.5 / 14.5 / 10 is 100 parts by mass. Emulsion polymerization was carried out by adding 2 parts by mass of the trade name "Newcol NT-30" manufactured by Nippon Emulsifier Co., Ltd., which is a surfactant.

3.2. Recording Method Using the inks and treatment solutions shown in Tables 1 and 2, recording was performed under the conditions shown in Tables 3 to 5. As an apparatus, an inkjet printer manufactured by Seiko Epson Corporation, trade name "SC-S80650" was modified so that the temperature of the heater 4 shown in FIG. 1 could be adjusted. As for each nozzle row of the inkjet head 2, 10 rows are arranged side by side as shown in FIG. Each nozzle row, that is, a nozzle group has 600 nozzles and a nozzle density of 600 npi.

Each nozzle row was filled with ink or a treatment liquid as shown in Arrangement Examples 1 to 3 in Table 3. Nozzle rows 1 → 10 were set from the left end to the right end in FIG. The temperature of the platen heater 4 was adjusted so that the surface temperature of the recording medium 10 at a location facing the inkjet head 2 during recording became the temperature shown in Table 5. The first nozzle portion and the second nozzle portion were set for each recording method shown in Table 4, and the discharge amounts were set as shown in FIGS. 4 to 9 and as shown below. For recording, a main scan by a carriage equipped with a head and a sub scan, which is a paper feed, were alternately performed on a recording medium set in a printer, and bidirectional recording was performed by 4-pass recording. That is, the length of the sub-scan was one-fourth of the length of the nozzle row, and the ink and the treatment liquid were adhered to the band region 10b by four main scans (passes).

4 to 9 are views for conceptually explaining the relationship between the processing liquid and the ink ejection amount in the inkjet recording, and show the nozzle usage rate corresponding to each nozzle number. In FIG. 3, there are 10 nozzle rows, but on the right side of FIGS. 4 to 9, only one row of ink nozzles for ink and one row of treatment liquid nozzles for treatment liquid are represented. Shown. The same applies to the remaining ink nozzle rows and treatment liquid nozzle rows. Each nozzle row had 600 nozzles and a nozzle density of 600 npi.

In the example below, all four passes use the entire area of the nozzle row. For example, in FIG. 4 showing the recording method 1, the colored portions of the treatment liquid nozzle row and the ink nozzle row are the nozzle portions used, and the nozzle portions are shaded according to the nozzle usage rate. On the other hand, the white part indicates a region where the nozzle usage rate is 0%. In the ink nozzle row of FIG. 4, the color closer to the lower end and the side closer to the upper end are gradually lightened, but are not pure white. Only both ends are pure white, and the nozzle usage rate is 0% here. The graph on the left side of FIG. 4 corresponds to the usage rate of the nozzle on the right side. At a usage rate of 100%, the nozzle is fully used, and at 0%, it is not used at all. For example, the Nozzle No. 1 and Nozzle No. 600 of the ink nozzle row are not used at a usage rate of 0%.

The final recording resolution of the recorded image was 1200 dpi in the main scanning direction, 600 dpi or more in the sub-scanning direction, and the ink adhesion amount (mg / inch ² ) was set to the value in Table 5.

Regarding the amount of ink adhered, for example, in the recording method 1 shown in FIG. 4, for example, in a certain band region, the first pass is the B2 region, the second pass is the lower half of the A1 region, and the third pass is the upper half of the A1 region, 4 It is assumed that the pass is recorded in the B1 area. For the 2nd and 3rd passes, the amount of adhesion per pass was 10/3 (mg / inch ² ), and for the 1st and 4th passes using the B1 and B2 regions, 10/3 (mg / inch) for the 2nd pass. ² ) Adhesion amount. The final adhesion amount of the image is 10 (mg / inch ² ) in total of 4 passes.

In each recording method, the 30 nozzles belonging to either the A region or the B region are referred to as the second ink nozzle portion, and the 30 nozzle portions belonging to the other are referred to as the first ink nozzle portion. Details are described below. The first treatment liquid nozzle portion and the second treatment liquid nozzle portion were the same nozzle number as the first ink nozzle portion and the second ink nozzle portion, respectively.

The following recording media 1 to 3 were used as the recording medium, and the amount of liquid absorbed was measured by using the above-mentioned Bristow method. Here, water / 1,2-hexanediol = 95/5 was used as the test solution, and the maximum liquid absorption amount of 30 msec from the start of contact was recorded as non-absorbable at 30 mL / m ² or less. The medium or low absorption recording medium was used.
Recording medium 1: Product name "IJ180Cv3-10", liquid absorption 0.77 mL / m ² , PVC film, manufactured by 3M Japan Co., Ltd. Recording medium 2: Product name "3684 TriSolv Poster Paper Prime 130 Glossy", liquid absorption 1 .85 mL / m ² , coated paper, SiHL recording medium 3: trade name "My Paper", liquid absorption 38.60 mL / m ² , plain paper, manufactured by Ricoh Co., Ltd.

Recording method 1; Fig. 4
Ink adhesion amount 100% to 50% Treatment liquid adhesion amount ratio 25%.
The ink adhesion amount is linearly reduced to 25% to 10% to 50% to 10%.
When the ink adhesion amount is 30%, the treatment liquid adhesion amount is 15.6%.
When the ink adhesion was 10% or less, the treatment liquid was maintained at 10%.
Thirty nozzles centered on a nozzle having an ink nozzle usage rate of 30% in the B2 region were designated as the first ink nozzle portion, and 30 nozzles in the A1 region were designated as the second ink nozzle portion.
(Discharge amount of the first treatment liquid nozzle / discharge amount of the first ink nozzle) is 2.1 times that of (discharge amount of the second treatment liquid nozzle / discharge amount of the second ink nozzle).

Recording method 2; Fig. 5
The B1 and B2 regions are 100% ink and 25% treatment liquid.
The A2 area is 30% ink and 15% treatment liquid.
The A1 region is 70% ink and 17.5% treatment liquid.
Thirty nozzles having an ink nozzle usage rate of 30% in the A2 region were designated as the first ink nozzle portion, and 30 nozzles in the B2 region were designated as the second ink nozzle portion.
(Discharge amount of 1st treatment liquid nozzle / Discharge amount of 1st ink nozzle) is doubled with respect to (Discharge amount of 2nd treatment liquid nozzle / Discharge amount of 2nd ink nozzle).

Recording method 3; Fig. 6
Ink adhesion amount 100% to 25% Treatment liquid adhesion amount ratio 25%.
When the ink adhesion amount is 25% or less, the treatment liquid adhesion amount is linearly reduced from 25% to 15%.
Thirty nozzles centered on a nozzle having an ink nozzle usage rate of 48% in the B3 region were designated as the first ink nozzle portion, and 30 nozzles in the A2 region were designated as the second ink nozzle portion.
(Discharge amount of 1st treatment liquid nozzle / Discharge amount of 1st ink nozzle) is 2.1 times as much as (Discharge amount of 2nd treatment liquid nozzle / Discharge amount of 2nd ink nozzle).

Recording method 4; Fig. 7
Thirty nozzles centered on a nozzle having an ink nozzle usage rate of 30% in the B2 region were designated as the first ink nozzle portion, and 30 nozzles in the A1 region were designated as the second ink nozzle portion.
The processing liquid adhesion amount / ink adhesion amount is the same in the first ink nozzle portion and the second ink nozzle portion.

Recording method 5; Not shown In recording method 2, the treatment liquid adhesion ratio in the A1 and A2 regions was set to be the same as the adhesion ratio (25%) in the B1 region.
The nozzle portion was set to be the same as the recording method 2.
The processing liquid adhesion amount / ink adhesion amount is the same in the first ink nozzle portion and the second ink nozzle portion.

Recording method 6; Not shown In the recording method 1, the amount of adhesion of the B1 and B2 regions of the recording method processing liquid was reduced as compared with the recording method 1.
That is,
100% ink adhesion Same as recording method 1.
The amount of ink adhered is linearly reduced to 100% to 10%.
When the ink adhesion amount is 30%, the treatment liquid adhesion amount is 12.9%.
When the ink adhesion amount is 10% or less, the treatment liquid adhesion amount at 10% is maintained.
The nozzle portion was set to be the same as the recording method 1.
(Discharge amount of 1st treatment liquid nozzle / Discharge amount of 1st ink nozzle) is 1.7 times larger than (Discharge amount of 2nd treatment liquid nozzle / Discharge amount of 2nd ink nozzle).

Recording method 7; not shown, in recording method 1, the amount of adhesion of the B1 and B2 regions of the treatment liquid was increased as compared with recording method 1, that is,
Same as recording method 1 from 100% to 50% of ink adhesion.
The ink adhesion amount is linearly reduced from 25% to 15% to 50% to 10%.
When the ink adhesion amount is 30%, the treatment liquid adhesion amount is 20%.
When the ink adhesion amount is 10% or less, the treatment liquid adhesion amount at 10% is maintained.
The nozzle portion was set to be the same as the recording method 1.
(Discharge amount of 1st treatment liquid nozzle / Discharge amount of 1st ink nozzle) is 2.7 times as large as (Discharge amount of 2nd treatment liquid nozzle / Discharge amount of 2nd ink nozzle).

Recording method 8; Fig. 8
In the recording method 1, the B1 region on the downstream side of the treatment liquid nozzle was not used, and the treatment liquid was recorded in 3 passes. The treatment liquid that was supposed to be attached in the 4th pass was distributed in the 1st to 3rd passes.
Thirty nozzles centered on a nozzle having an ink nozzle usage rate of 48% in the B2 region were designated as the first ink nozzle portion, and 30 nozzles having a nozzle usage rate of 100% in the A1 region were designated as the second ink nozzle portion.
The adhesion amount ratio between the treatment liquid and the ink of the first ink nozzle portion and the second ink nozzle portion was the same as that of the recording method 1.

Recording method 9; Fig. 9
The amount of ink and treatment liquid adhered to each of the A region and the B region was kept constant.
The 30 nozzles in the B2 region were designated as the first ink nozzle portion, and the 30 nozzles in the A2 region were designated as the second ink nozzle portion.

3.3. Evaluation method 3.3.1. Evaluation of image quality with and without shading banding By the above recording method, solid red, blue, and green images (700 x 120 mm for each color) are printed at 700 mm in the paper feed direction, and light and shade banding that matches the paper feed amount cycle occurs. It was evaluated according to whether or not it was done. The evaluation was performed visually and by observing with a microscope. The shade banding is a banding-like part where the density looks different.
(Evaluation criteria)
A: Light and shade banding is not visually visible in the solid surface.
B: A slight shade of banding can be visually observed in the solid surface.
C: Light and shade banding is clearly visible in the solid surface. When observed under a microscope, the background color (the part where the ink is not attached) cannot be seen.
D: Light and shade banding is clearly visible in the solid surface. When observed under a microscope, there is a part where the background color can be seen.

3.3.2. Evaluation of image quality with and without color banding By the above recording method, solid red, blue, and green images (700 x 120 mm for each color) are printed at 700 mm in the paper feed direction, and color banding that matches the paper feed amount cycle occurs. It was evaluated by. The evaluation was performed by visual observation. Color banding means that the parts that look different in color look like banding.
(Evaluation criteria)
A: No color banding can be seen on the solid surface.
B: Some color banding can be seen in the solid surface.
C: Color banding is clearly seen in the solid surface.

3.3.3. Evaluation of image quality based on the presence or absence of uneven aggregation A solid red, blue, and green image (30 × 30 mm for each color) was printed by the above recording method, and it was evaluated whether uneven aggregation occurred. Each color pattern was recorded and evaluated individually. The evaluation was performed visually and by observing with a microscope. The evaluation results were the same for all color patterns. (Evaluation criteria)
A: No uneven aggregation is observed in the solid surface even when observed with a microscope.
B: Some uneven aggregation is observed in the solid surface under a microscope. I can't see it visually.
C: Even visually, the uneven aggregation of light and shade of less than 2 mm is observed in the solid surface.
D: Coagulation unevenness is clearly seen in the solid surface even visually.

3.4. Evaluation Results of Recording Method Table 5 shows the results of the evaluation test of the recording method.
In each of the examples, (first treatment liquid nozzle part discharge amount / first ink nozzle part discharge amount) is larger than (second treatment liquid nozzle part discharge amount / second ink nozzle part discharge amount), and the treatment is performed. The liquid was used, and all of them were excellent in suppressing light and shade banding. On the other hand, in all the comparative examples in which this was not the case, the shading banding suppression was inferior. Details are described below.

In Example 1, excellent image quality was obtained when all the evaluations were B or higher.
In Example 2, light and shade banding was observed. This is because the A region and the B region alternate, and the ink ejection amount in the first pass is large, so the ink ejection amount is streaky in the part where the ejection amount is excessive due to the variation in paper feed, not the shading banding due to landing interference. It is probable that light and shade banding occurred.
In the third embodiment, a discharge profile is provided so that two ridges are formed corresponding to the paper feed width. In this example, neither streak banding due to variation in paper feed nor shading banding due to landing interference was observed, and no uneven aggregation was observed, and excellent image quality was obtained.
In Example 4, a cationic resin flocculant was used as a coagulant for the treatment liquid, but there was no difference in evaluation from Example 1. However, it was easily clogged by mist.
In Example 5, the treatment liquid does not contain a coagulant. In this case, a shade banding different from the shade banding due to the impact interference was observed. It is considered that this is because the ink component flows because the treatment liquid does not contain a coagulant, the degree of coagulation unevenness varies depending on the ejection density of the ink and the treatment liquid, and the shading unevenness is recognized as a banding.
In Example 6, a fluorine-based surfactant was used as the surfactant in the treatment liquid. In this case, the wettability of the treatment liquid became high, the ink component flowed, and some uneven aggregation was observed.
In Example 7, the solvent of the ink has good wettability, but it is difficult to dry. For this reason, the ink components flowed, and some uneven aggregation was observed.
In Example 8, the ink fillings are symmetrically arranged, but the treatment liquid is closer to one side. In this example, due to bidirectional printing, the coagulant was insufficient on the return trip, and the evaluation of coagulation unevenness was lowered. In addition, the degree of color mixing of the ink components changed between the outward trip and the return trip, and the evaluation of color banding deteriorated.
In Example 9, the ink filling is asymmetric. In this example, the landing order changed on the outward trip and the color development changed, so the evaluation result of the color banding deteriorated considerably. In addition, since the degree of color mixing changes, it was also recognized as uneven aggregation.
In the tenth embodiment, since the printing temperature is high, the drying progresses and the landing droplets become small. Therefore, the impact interference is small and the fluidity of the ink and the treatment liquid is also lowered, so that color mixing and uneven aggregation are unlikely to occur, but there is a possibility of clogging.
Since the printing temperature of Example 11 is low, landing interference, color mixing, and flow are likely to occur, and the image quality is deteriorated.
In Example 12, since the amount of ink ejected was large, it took time to reduce the fluidity of the ink, and the evaluation of aggregation unevenness was lowered.
In Example 13, since the amount of ink ejected was small, the difference between the low and high dot densities was small, and shade banding and color banding were not recognized. Moreover, since the amount of liquid was small, no uneven aggregation was observed.
In Example 14, banding also occurred in coated paper having low liquid absorption. Due to the slight absorbency, the treatment liquid was absorbed, and the difference in the presence or absence of color mixing was conspicuous.

In Reference Examples 1 and 2, which are examples in which recording was performed on plain paper, which is an ink-absorbing recording medium, the plain paper has high ink permeability, so that the treatment liquid is not used. No banding was seen and the image quality did not deteriorate. As described above, the problem of the present invention has not arisen for the absorbent recording medium.

In Comparative Example 1, the processing liquid adhesion amount / ink adhesion amount was the same in the A1 region and the B1 and B2 regions in the entire recording, and banding occurred.
In Comparative Example 2, since the treatment liquid was not used, the evaluation of shading banding and agglutination unevenness was lowered.
In Comparative Example 3, the processing liquid adhesion amount / ink adhesion amount was the same in the A1 region and the B1 and B2 regions, and banding occurred.
In Comparative Example 4, banding occurred because the amount of ink and the treatment liquid adhered to each of the A region and the B region was kept constant.

As shown above, in the examples, images having excellent image quality were obtained in inkjet recording on a non-absorbent recording medium or a low-absorbency recording medium using a water-based ink and a treatment liquid. On the other hand, in the comparative example, the image quality deteriorated and the problem could not be solved. Further, in the reference example using the absorbent recording medium, the image quality did not deteriorate and no problem occurred.

The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the present invention includes a configuration substantially the same as the configuration described in the embodiment (for example, a configuration having the same function, method and result, or a configuration having the same purpose and effect). The present invention also includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. The present invention also includes a configuration that exhibits the same effects as the configuration described in the embodiment or a configuration that can achieve the same object. The present invention also includes a configuration in which a known technique is added to the configuration described in the embodiment.

1 ... inkjet recording device, 2 ... inkjet head, 2a ... nozzle surface, 3 ... IR heater, 4 ... platen heater, 5 ... heating heater, 6 ... cooling fan, 7 ... preheater, 8 ... ventilation fan, 9 ... carriage, 10 ... Recording medium, 10a ... Recording area, 10b ... Band area, 10c ... Predetermined width, 11 ... Platen, 12 ... Cartridge, 13 ... Carriage moving mechanism, 14 ... Conveying means, 15 ... Ink ejection nozzle group, 15a ... 2 ink nozzles, 15b ... 1st ink nozzles, 16 ... processing liquid ejection nozzles, 16a ... 2nd processing liquid nozzles, 16b ... 1st processing liquid nozzles, A1, A2 ... 2nd ink nozzles and second 2 Area where the treatment liquid nozzle part exists, B1, B2 ... Area where the first ink nozzle part and the first treatment liquid nozzle part exist, CONT ... Control unit, MS ... Main scanning axis, SS ... Sub-scanning axis, X ... Overlapping area, Y ... band area

Claims (18)

An inkjet recording method in which an ink composition and a treatment liquid containing water are ejected to a recording medium selected from a non-absorbent recording medium or a low-absorbency recording medium by a plurality of main scans for recording. There,
The record is
A main scan that ejects the ink composition and the treatment liquid while moving the ink ejection nozzle group and the treatment liquid ejection nozzle group along the main scanning axis.
A sub-scan that moves the recording medium along a sub-scan axis that intersects the main scan axis.
When the ink ejection nozzle group and the processing liquid ejection nozzle group are projected along the main scanning axis, the ink ejection nozzle group and the processing liquid ejection nozzle group overlap each other along the sub-scanning axis. Have,
The length of one sub-scan is shorter than the length of the ink ejection nozzle group in the sub-scan axis direction.
Of the recording region to which the ink composition of the recording medium is adhered, the ink composition is adhered to the band region corresponding to the length of one sub-scan by two or more main scans.
The ink ejection nozzle group includes a first ink nozzle portion and a second ink nozzle portion having a length equal to or less than the length of one sub-scanning.
The treatment liquid ejection nozzle group includes a first treatment liquid nozzle portion that overlaps with the first ink nozzle portion along the sub-scanning axis when projected onto the main scanning axis, and the treatment liquid ejection nozzle group when projected onto the main scanning axis. A second processing liquid nozzle portion that overlaps with the second ink nozzle portion along the sub-scanning axis is provided.
In a certain main scan, the ejection amount of the first ink nozzle portion is the ejection amount of the first ink nozzle portion, the ejection amount of the first processing liquid nozzle portion is the ejection amount of the first processing liquid nozzle portion, and the ejection amount of the second ink nozzle portion. Inkjet recording that satisfies the following (Equation 1) and (Equation 2) when the ejection amount is the ejection amount of the second ink nozzle portion and the ejection amount of the second processing liquid nozzle portion is the ejection amount of the second processing liquid nozzle portion. Method.
First ink nozzle discharge amount <Second ink nozzle discharge amount ... (Equation 1)
(Discharge amount of 1st treatment liquid nozzle / Discharge amount of 1st ink nozzle)> (Discharge amount of 2nd treatment liquid nozzle / Discharge amount of 2nd ink nozzle) ... (Equation 2) The ink composition is ejected from the second ink nozzle portion in another main scan to the recording area to which the ink composition is ejected and adhered from the first ink nozzle portion in the certain main scan. The inkjet recording method according to claim 1, wherein the ink is adhered. The inkjet recording method according to claim 1 or 2, wherein the treatment liquid contains a coagulant. The inkjet recording method according to any one of claims 1 to 3, wherein the first ink nozzle portion and the second ink nozzle portion each have 10 or more and 100 or less nozzles. In the recording, the ejection amount of the second ink nozzle portion is the largest in the ink ejection nozzle group, and the ejection amount of the first ink nozzle portion is 30% by mass or less of the ejection amount of the second ink nozzle portion. The inkjet recording method according to any one of claims 1 to 4. (Discharge amount of 1st treatment liquid nozzle / Discharge amount of 1st ink nozzle) is 1.5 or more and 3.0 or less with respect to (Discharge amount of 2nd treatment liquid nozzle / Discharge amount of 2nd ink nozzle). The inkjet recording method according to claim 5. The inkjet recording method according to claim 5 or 6, wherein (second processing liquid nozzle portion ejection amount / second ink nozzle portion ejection amount) is 0.1 or more and 0.5 or less. The first ink nozzle portion is located in a region corresponding to one length of the sub-scanning from the end of the ink ejection nozzle group.
The second ink nozzle portion according to any one of claims 1 to 7, wherein the second ink nozzle portion is located in a region other than the region corresponding to the length of one sub-scanning from the end of the ink ejection nozzle group. Ink recording method. The inkjet recording method according to any one of claims 1 to 8, wherein the first ink nozzle portion and the second ink nozzle portion are each at two or more locations in the ink ejection nozzle group. The inkjet recording according to any one of claims 1 to 9, wherein in the first ink nozzle portion, the ejection amount gradually decreases from one end of the first ink nozzle portion toward the other end. Method. The inkjet recording method according to any one of claims 1 to 10, wherein the ink composition is a water-based ink composition containing a pigment. The inkjet recording method according to any one of claims 1 to 11, wherein the ink composition has an organic solvent content of 15% by mass or more. The inkjet recording method according to any one of claims 1 to 12, wherein the ink composition contains an organic solvent having a standard boiling point of 180 ° C. or higher and 280 ° C. or lower. The number of main scans for ejecting the treatment liquid is smaller than the number of main scans for ejecting the ink composition with respect to the band region.
The inkjet according to any one of claims 1 to 13, wherein the main scan for ejecting the treatment liquid is completed earlier than the main scan for ejecting the ink composition with respect to the band region. Recording method. A step of heating the recording medium is provided.
The inkjet recording method according to any one of claims 1 to 14, wherein the main scanning is performed on the heated recording medium. The ejection amount of the ink ejection nozzle group is the amount of adhesion of the main scan in the case of recording a predetermined single density image on the recording medium, according to any one of claims 1 to 15. Ink recording method. The main scan includes a first main scan performed in the first direction and a second main scan performed in the second direction opposite to the first direction.
The inkjet according to any one of claims 1 to 16, wherein in the first main scan and the second main scan, the order of ejection of the treatment liquid and ejection of the ink composition is the same. Recording method. An inkjet recording device that ejects an ink composition and a water-containing treatment liquid onto a recording medium selected from a non-absorbent recording medium or a low-absorbency recording medium by a plurality of main scans for recording. There,
The record is
A main scan that ejects the ink composition and the treatment liquid while moving the ink ejection nozzle group and the treatment liquid ejection nozzle group along the main scanning axis.
A sub-scan that moves the recording medium along a sub-scan axis that intersects the main scan axis.
When the ink ejection nozzle group and the processing liquid ejection nozzle group are projected along the main scanning axis, the ink ejection nozzle group and the processing liquid ejection nozzle group overlap each other along the sub-scanning axis. Have,
The length of one sub-scanning is shorter than the length of the ink ejection nozzle group in the sub-scanning axis direction.
Of the recording region to which the ink composition of the recording medium is adhered, the ink composition is adhered to the band region corresponding to the length of one sub-scan by two or more main scans.
The ink ejection nozzle group includes a first ink nozzle portion and a second ink nozzle portion having a length equal to or less than the length of one sub-scanning.
The treatment liquid ejection nozzle group includes a first treatment liquid nozzle portion that overlaps with the first ink nozzle portion along the sub-scanning axis when projected onto the main scanning axis, and the treatment liquid ejection nozzle group when projected onto the main scanning axis. A second processing liquid nozzle portion that overlaps with the second ink nozzle portion along the sub-scanning axis is provided.
In a certain main scan, the ejection amount of the first ink nozzle portion is the ejection amount of the first ink nozzle portion, the ejection amount of the first processing liquid nozzle portion is the ejection amount of the first processing liquid nozzle portion, and the ejection amount of the second ink nozzle portion. Inkjet recording that satisfies the following (Equation 1) and (Equation 2) when the ejection amount is the ejection amount of the second ink nozzle portion and the ejection amount of the second processing liquid nozzle portion is the ejection amount of the second processing liquid nozzle portion. apparatus.
First ink nozzle discharge amount <Second ink nozzle discharge amount ... (Equation 1)
(Discharge amount of 1st treatment liquid nozzle / Discharge amount of 1st ink nozzle)> (Discharge amount of 2nd treatment liquid nozzle / Discharge amount of 2nd ink nozzle) ... (Equation 2)