JP5707752B2 - Liquid ejection device - Google Patents

Description

  The present invention relates to a liquid ejection apparatus.

2. Description of the Related Art Conventionally, as one of liquid ejecting apparatuses, an ink jet printer that performs printing by ejecting a liquid such as ink onto various ejected media such as paper, cloth, and film is known. Ink jet printers are inexpensive, and liquid can be used efficiently and running cost is low because liquid is ejected only on the required image area and image formation is performed directly on the medium to be ejected. Furthermore, since an inkjet printer has low noise, it is excellent as an image forming method.

However, when bubbles or dissolved gas is present in the liquid used in the ink jet printer, the liquid is not sufficiently compressed at the time of discharge, and thus the discharge performance is lowered and stable liquid particles cannot be generated. That is, in such a case, the printing stability is inferior. In addition, there is a problem that dot dropout or printing failure occurs, and the reliability of inkjet printing is lowered. Therefore, attempts have been made to prevent bubbles and dissolved gases from being present in the liquid used.

For example, Patent Document 1 discloses a method for degassing ink by allowing ink for inkjet recording after heating to pass through a gas-permeable film. Patent Document 2 discloses an ink jet recording apparatus having a vacuum deaeration mechanism in which the degree of deaeration vacuum is adjusted to a predetermined range.

JP 2003-253169 A JP 2008-87273 A

However, the ink degassing method disclosed in Patent Document 1 and the ink jet recording apparatus disclosed in Patent Document 2 still have practical problems in terms of printing stability, missing dots, and defective printing.

Accordingly, an object of the present invention is to provide a liquid ejecting apparatus such as an ink jet recording apparatus that is excellent in printing stability and hardly causes dot dropout and printing defects.

In order to solve the above problems, the inventor of the present application has intensively studied an ink deaeration unit in an ink jet recording apparatus which is an example of a liquid ejecting apparatus.

Inks include pigment-based inks and dye-based inks depending on the color material used. Pigment-based inks are suitable as display inks because they are superior in storage stability of recorded matter compared to dye-based inks. However, there is a problem peculiar to pigment-based inks, namely precipitation of pigment particles. In particular, when the pigment-based ink is a white ink, titanium oxide is often used to maintain whiteness. However, because titanium oxide has a large specific gravity, sedimentation is noticeable. As a countermeasure for preventing such sedimentation, the recording apparatus is provided with a stirring mechanism.

On the other hand, air bubbles are not preferable in the inkjet ink from the viewpoint of ejection reliability. When the ink jet recording apparatus was equipped with a stirring mechanism, it was found that bubbles in the ink were involved during recording, and as a result, the ejection reliability of the ink jet ink was adversely affected.

Therefore, as a result of further investigations by the inventors of the present application, sedimentation of the pigment is eliminated and the ejection reliability is excellent by the liquid ejection apparatus, that is, the ink jet recording apparatus, equipped with both the stirring mechanism and the vacuum degassing mechanism. The present invention was completed.

Furthermore, solvent-based inks with high viscosity, such as UV curable inks, require a long time for deaeration of the ink in a normal stationary state, but the present invention performs stirring together with deaeration of the ink. As a result, it became clear that the degassing time could be shortened.

That is, the present invention is as follows.
[1]
A printer head that discharges liquid from a nozzle toward the discharge medium; a discharge medium transfer unit that transfers the discharge medium to a position facing the printer head; and a supply path that supplies the liquid to the printer head. A reservoir that communicates with the supply path and stores the liquid; a vacuum degassing mechanism that degass the liquid in the reservoir; and a stirring mechanism that stirs the liquid in the reservoir. A liquid discharge apparatus.
[2]
The liquid ejection apparatus according to [1], wherein the liquid is a liquid composition containing a metal oxide.
[3]
The degree of vacuum in the reservoir by the vacuum degassing mechanism is 0.03 to 0.08 MPa.
The liquid ejection device according to [1] or [2].
[4]
The liquid ejecting apparatus according to any one of [1] to [3], wherein the printer head is provided on a carriage and the reservoir is provided on the carriage.
[5]
The liquid ejecting apparatus according to any one of [1] to [3], wherein the printer head is provided in a carriage and the reservoir is provided in a place other than the carriage.
[6]
The liquid ejecting apparatus according to any one of [1] to [5], wherein the reservoir is a cartridge.
[7]
The liquid ejection device according to any one of [1] to [6], further including a transport pump provided in the supply path.

It is a schematic block diagram which shows an example of the inkjet recording device of this invention. It is a schematic block diagram which shows an example of the inkjet recording device of this invention. It is a schematic block diagram which shows an example of the inkjet recording device of this invention. It is a schematic block diagram which shows an example of the inkjet recording device of this invention. It is a schematic block diagram which shows an example of the inkjet recording device of this invention. It is a flowchart which shows an example of the recording method of the inkjet recording device used by this invention. It is a flowchart which shows an example of the recording method of the inkjet recording device used by this invention. It is a flowchart which shows an example of the recording method of the inkjet recording device used by this invention.

Hereinafter, embodiments for carrying out the present invention will be described in detail. In addition, this invention is not restrict | limited to the following embodiment, A various deformation | transformation can be implemented within the range of the summary.

In the present specification, as described above, the “liquid ejecting apparatus” performs printing by ejecting liquid such as ink onto various ejected media such as paper, cloth, and film, and includes an ink jet printer. . As described above, this ink jet printer ejects liquid only to a required image portion and directly forms an image on a medium to be ejected. The “recording apparatus” included in the liquid ejecting apparatus is an image recording apparatus for forming an image on a recording medium such as paper based on an image data signal, and includes an ink jet recording apparatus. This inkjet recording apparatus
Ink is ejected only to the required image area to form an image directly on the recording medium. Accordingly, the ink jet recording apparatus is included as an example of a liquid ejection apparatus.

The on-carriage method and the off-carriage method in this specification are, for example, edited by the Japanese Imaging Society, “Series“ Digital Printer Technology ”Inkjet”, Tokyo Denki University Press, September 10, 2008, first edition, p. 190, 191. Here, the “on-carriage method” means an ink supply method in which an ink cartridge is mounted on a carriage together with a print head. The “off-carriage method” means an ink supply method in which an ink cartridge is not mounted on a carriage but is installed in another place and connected to a print head on the carriage by a tube or the like. The “sub ink tank” is an ink tank that is installed between the print head and the ink cartridge when a tube is connected from the ink cartridge to the print head on the carriage by an off-carriage method. Further, the “sub ink tank” refers to a relay tank installed above the printer head in order to increase the degree of freedom of installation of the main ink tank (ink cartridge), for example, it can be below the print head. .

An ink jet recording apparatus and an ink jet recording method which are examples embodying a liquid ejection apparatus according to each embodiment of the present invention will be described below with reference to the drawings. 1 to 5, the vertical positional relationship between the members is assumed to be as illustrated.

[First Embodiment]
[Liquid ejection device configuration]
One embodiment of the present invention relates to a liquid ejection apparatus. The liquid ejection apparatus includes: a printer head that ejects liquid from a nozzle toward the ejection medium; a ejection medium conveyance unit that conveys the ejection medium to a position facing the printer head; and the liquid on the printer head. A supply path for supplying the liquid, a reservoir connected to the supply path for storing the liquid, a vacuum degassing mechanism for vacuum degassing the liquid in the reservoir, and stirring the liquid in the reservoir A stirring mechanism to
Have
An ink jet recording apparatus which is an example embodying the liquid ejecting apparatus is a printer head that ejects ink (corresponding to liquid in the liquid ejecting apparatus) from a nozzle toward a recording medium (corresponding to the ejected medium in the liquid ejecting apparatus). A recording medium conveying means for conveying the recording medium to a position facing the printer head (equivalent to an ejection medium conveying means in a liquid ejection apparatus), a supply path for supplying the ink to the printer head, A reservoir that communicates with the supply path and stores the ink; a vacuum degassing mechanism that degass the ink in the reservoir; and a stirring mechanism that stirs the ink in the reservoir. .
FIG. 1 is a schematic configuration diagram illustrating an example of an ink jet recording apparatus according to the present embodiment. The recording apparatus 1 is supplied with a reservoir 2, a stirring mechanism 4, a vacuum degassing mechanism 5, a supply path 6, a check valve 7, and a printer head 8. The reservoir 2 stores the ink 3 for deaeration. The stirring mechanism 4 is for stirring the ink 3 stored in the reservoir 2. The vacuum degassing mechanism 5 is for vacuum degassing the ink 3 stored in the reservoir 2. The vacuum degassing mechanism 5 is, for example, a vacuum pump. The supply path 6 supplies (feeds) the ink 3.
The supply path 6 communicates with the reservoir 2. The supply path 6 may include a liquid feed pump in the middle thereof. The check valve 7 prevents the backflow of the ink 3 that is fed to any location in the supply path 6. The printer head 8 is a destination to which the ink 3 is supplied (liquid feeding) through the supply path 6. The printer head 8 ejects the ink 3 from the nozzle toward the recording medium.

Here, it is preferable that the printer head 8 is provided in the carriage and the reservoir 2 is provided in the carriage. Specifically, the reservoir 2 provided with the stirring mechanism 4 and the vacuum degassing mechanism 5 is preferably an on-carriage ink cartridge. in this case,
Since the distance from the ink cartridge to the printer head is short, the resistance of the flow path is small, and since the ink is supplied using the water head value because it is at the top of the head, a pump is not necessary, and the flow path design cost can be reduced.

Alternatively, it is also preferable that the printer head 8 is provided in a carriage and the reservoir 2 is provided in a place other than the carriage. More specifically, the reservoir 2 may be replaced with at least one of an off-carriage ink cartridge and an ink tank communicating with the off-carriage ink cartridge and the printer head. In this case, the printer head can be reduced in size. In this modification, the mechanisms 4 and 5 are provided in the sub ink tank. In FIG. 3 to be described later, a modification having a sub ink tank is shown.
The printer head 8 includes a nozzle (not shown) for discharging and landing (attaching) the ink 3 toward the recording medium. A recording medium conveying means (not shown) of the present invention for conveying the recording medium is provided at a position facing the printer head 8.

When the ink 3 is an ultraviolet curable ink, a light irradiation means (ultraviolet irradiation lamp) (not shown) is provided downstream from the position facing the printer head 8 in the transport portion of the recording medium.

[Inkjet recording method (operation)]
FIG. 6 is a flowchart showing an example of an ink jet recording method using the ink jet recording apparatus of the present embodiment. The recording method will be briefly described. First, after receiving a printing command (S10), a vacuum stirring operation is performed (S11). After stirring, printing is performed (S12). In this way, during the printer stop time, the reduced pressure stirring operation is performed before starting printing in consideration of any increase in dissolved oxygen amount, sedimentation of ink components, or mixing of bubbles.

Specifically, the ink jet recording method is characterized in that it includes at least a stirring deaeration step and a discharge step. Further, when the ink to be used is an ultraviolet curable ink, the recording method may include a curing step. Hereafter, each process is demonstrated in detail according to the step of a flowchart.

(Print command (S10))
The print command instructs image data to be printed and printing. Image data is transmitted from a computer apparatus (not shown) to the ink jet recording apparatus together with a print command.

(Reduced pressure stirring operation (S11))
The reduced pressure stirring operation corresponds to the stirring deaeration step of the present invention. For example, (1) drive (depressurization) of the vacuum degassing mechanism 5 that is a vacuum pump, (2) start stirring, (3) stop stirring, and (4) stop (depressurization stop) of the vacuum degassing mechanism 5 proceed in this order. To do.

If the agitation is performed first, bubbles are likely to be mixed into the ink 3. Therefore, after the pressure is reduced in the above (1), the agitation can be efficiently performed by starting the stirring in the above (2). In the present embodiment, the liquid level of the ink 3 in the reservoir 2 is made lower than that of the printer head 8 without using the liquid feed pump, and the ink 3 is supplied using the water head difference. Not. Therefore, it is necessary to stop the decompression before printing (flow from (4) to (5) above). However, if the pressure reduction is stopped before the stirring is stopped, bubbles are likely to be mixed into the ink 3. Therefore, after the pressure reduction is stopped after the stirring stop in the above (3), the above (4) is advanced.

The degree of vacuum in the reservoir 3 by the vacuum degassing mechanism 5 is preferably 0.03 to 0.08 MPa, and more preferably 0.05 to 0.07 MPa. When the degree of vacuum is within the above range, sufficient deaeration can be performed, and volatile components are not lost due to unnecessary deaeration.

(Print (S12))
In printing, (5) printing is performed. Specifically, at least the ejection step (5-1) is performed, and when the ink to be used is an ultraviolet curable ink, the curing step (5-2) is performed. The above-described (4) stop (decompression stop) of the decompression deaeration mechanism 5 and (5) above are performed in this order.

(Discharge process (5-1))
The ejection process in the present embodiment is a process for landing the ink 3 after the stirring and deaeration process on the recording medium by ejecting the ink 3 from the printer head 8. As described above, the recording medium transport unit transports the recording medium to a position facing the printer head 8. The printer head 8 ejects the ink 3 onto a recording medium and causes it to land. For example, cyan,
When magenta, yellow, and black inks are required, ink 3 is prepared for each color. The printer head 8 may be a headset in which a plurality of heads for ejecting the ink 3 of each color are arranged along the conveyance direction of the recording medium. Also, the printer head 8
May be provided with a plurality of nozzles for ejecting ink 3 of each color in a direction orthogonal to the conveyance direction of the recording medium.

As described above, a conventionally known method can be used as an ink jet recording method for forming an image by ejecting and landing the ink 3 on a recording medium. Among these, excellent quality can be obtained by using a method of ejecting droplets using vibration of a piezoelectric element, that is, a recording method using an ink jet head that forms ink dots by mechanical deformation of an electrostrictive element. An image can be formed.

(Curing process (5-2))
The curing step in the present embodiment is a step of curing the ink 3 by irradiating light in a specific wavelength region after the ejection step.

As described above, when the ink 3 is an ultraviolet curable ink, a light irradiation means (ultraviolet irradiation lamp) (not shown) is provided. Therefore, the light in the specific wavelength region is preferably an ultraviolet (UV) ray region. The ultraviolet irradiation lamp irradiates the ink (ultraviolet curable ink) 3 landed on the recording medium with ultraviolet rays to cure the ink 3. The specific wavelength range (ultraviolet range) is, for example, in the range of 360 to 450 nm, preferably in the range of 360 to 410 nm, and more preferably in the range of 380 to 400 nm. Cost is low. In addition, when the wavelength range of the ink in the embodiment of the present invention is within the above range, the curability is further improved.

The amount of light irradiation is preferably 10 to 20,000 mJ / cm ² , more preferably 5
0 to 15,000 mJ / cm ² . When the irradiation amount is within the above range, the curing reaction can be sufficiently performed.

Examples of the light emission source (light irradiation means) in the above wavelength range include a mercury lamp and a metal halide lamp. On the other hand, from the viewpoint of environmental protection, since mercury-free is strongly desired, replacement of GaN-based semiconductors with ultraviolet light-emitting devices is progressing. Light emitting diodes (LEDs) and laser diodes (LDs) are being used as light sources for photo-curing inkjet recording because of their small size, high efficiency, and long life. Among these, a light emitting diode (LED) having a peak wavelength in the range of 360 to 400 nm is preferable from the viewpoint of cost and versatility.

As described above, according to the present embodiment, by combining agitation and reduced pressure, sedimentation can be recovered while maintaining printing stability. In particular, when the agitation mechanism is used alone, the printing stability is adversely affected, but when combined with the decompression mechanism, the printing stability is better than that when the decompression mechanism is used alone. Show.

[Second Embodiment]
The second embodiment is different from the first embodiment in that it is determined whether or not the reduced-pressure stirring operation is further performed after determining whether or not a predetermined time has elapsed since the previous reduced-pressure stirring operation.

[Liquid ejection device configuration]
Since the apparatus configuration is the same as that described with reference to FIG. 1, the description thereof is omitted here.

[Inkjet recording method (operation)]
FIG. 7 is a flowchart showing a modification of the ink jet recording method using the ink jet recording apparatus used in this embodiment. According to this recording method, first, after receiving a printing command (S20), it is determined whether or not a predetermined time has elapsed since the previous decompression stirring operation (S21).
. When a predetermined time has elapsed since the previous vacuum stirring operation (S21: Y), vacuum stirring is performed (
S22). Thereafter, printing is performed (S23). On the other hand, when the predetermined time has not elapsed since the previous decompression stirring operation (S21: N), printing is performed without performing decompression stirring (S23).

The cause of the necessity of stirring under reduced pressure includes any of sedimentation of ink components, increase in dissolved oxygen amount, or mixing of bubbles. Therefore, the time that any of these can occur is defined as a predetermined time (
Several hours, one day, several days).
The contents of the printing command (S20), the reduced pressure stirring operation (S22), and the printing (S23) are as follows:
Since these are the same as the contents of the printing command (S10), the vacuum stirring operation (S11), and the printing (S12) described in the first embodiment, the description thereof is omitted here.

As described above, according to the present embodiment, by combining agitation and reduced pressure, sedimentation can be recovered while maintaining printing stability. In particular, when the agitation mechanism is used alone, the printing stability is adversely affected, but when combined with the decompression mechanism, the printing stability is better than that when the decompression mechanism is used alone. Show. In addition, unlike the first embodiment described above, the present embodiment determines whether or not the reduced pressure stirring operation is further performed after determining whether or not a predetermined time has elapsed since the previous reduced pressure stirring operation. Can be suitably controlled, and unnecessary operations can be omitted, so that the time to start printing can be shortened.

[Third Embodiment]
In the third embodiment, two stages of predetermined time are prepared according to the stirring level, and after determining whether or not the predetermined time has passed since the previous vacuum stirring operation, one of the two levels of vacuum stirring operation is performed. Is different from the second embodiment in that it is determined whether or not to perform further.

[Liquid ejection device configuration]
Since it is the same as that described in FIG. 1, the description thereof is omitted here.

[Inkjet recording method (operation)]
FIG. 8 is a flowchart showing a modification of the ink jet recording method using the ink jet recording apparatus used in this embodiment. Here, first, after receiving a print command (S30
), It is determined whether or not the first predetermined time or more has elapsed since the previous decompression stirring operation (S31).
. When the first predetermined time or more has passed since the previous decompression stirring operation (S31: Y), the decompression stirring operation I is performed (S32). Thereafter, printing is performed (S33). When the first predetermined time or more has not elapsed since the previous decompression operation (S31: N), and when the second predetermined time has elapsed since the previous decompression operation (S34: Y), the decompression operation II (S35). Thereafter, printing is performed (S33). When the first predetermined time or more has not passed since the previous decompression stirring operation (S31: N) and when the second predetermined time has not passed since the previous decompression operation (S34: N), the decompression stirring operation I Printing is carried out without performing Steps II and II (S33).

Here, the first predetermined time is a time during which sedimentation of the ink component can occur, and the second predetermined time is a time during which either an increase in the amount of dissolved oxygen or mixing of bubbles can occur. Since the time during which ink sedimentation occurs is longer than the time during which dissolved oxygen increases or bubbles are mixed, the first predetermined time is longer than the second predetermined time. When not only the increase of dissolved oxygen or the mixing of bubbles but also the ink sedimentation occurs, the vacuum stirring operation I is performed. On the other hand, when only dissolved oxygen increases or bubbles are mixed, although the elimination of sedimentation is unnecessary, the reduced pressure stirring operation II is performed in order to increase the efficiency of deaeration and bubble removal. However, since it is not necessary to eliminate sedimentation, the stirring level in the reduced pressure stirring operation II is lower than that in the reduced pressure stirring operation I. On the other hand, when the ink component has settled for the first predetermined time or more after the previous decompression stirring operation, the stirring level in the decompression stirring operation I is compared with the stirring level when no sedimentation has occurred. Higher levels are required.

As one specific example, the stirring rotation speed in the reduced-pressure stirring operation I is high, while the stirring rotation speed in the reduced-pressure stirring operation II is half that of the reduced-pressure stirring operation I. As another specific example, while the reduced pressure stirring time in the reduced pressure stirring operation I is long, the reduced pressure stirring operation I
The reduced pressure stirring time in I is half that of the reduced pressure stirring operation I.
The contents of the printing command (S30), the vacuum stirring operation (S32, S35), and the printing (S33) are the printing command (S10) and the vacuum stirring operation (S11) described in the first embodiment, respectively.
, And printing (S12), the description is omitted here.

As described above, according to the present embodiment, by combining agitation and reduced pressure, sedimentation can be recovered while maintaining printing stability. In particular, when the agitation mechanism is used alone, the printing stability is adversely affected, but when combined with the decompression mechanism, the printing stability is better than that when the decompression mechanism is used alone. Show. In addition, unlike the second embodiment, this embodiment prepares two stages of predetermined time according to the stirring level, and after determining whether or not the predetermined time has elapsed since the previous reduced pressure stirring operation, In order to determine whether or not to further perform one of the two levels of reduced-pressure stirring operation, the reduced-pressure stirring operation can be controlled more favorably, and unnecessary operations can be omitted, thereby shortening the time to start printing. it can.

[Fourth Embodiment]
The fourth embodiment differs from the first embodiment in that a transport pump 9 is further provided in the supply path 6.

[Liquid ejection device configuration]
FIG. 2 is a schematic diagram illustrating a modified example of the ink jet recording apparatus which is an example of the liquid ejection apparatus according to the present embodiment. Unlike the recording apparatus 1 shown in FIG. 1, the recording apparatus 21 in this modification is supplied with a transport pump 9 in the supply path 6. In addition, check valves 7 are provided on both sides of the supply path 6 with the transport pump 9 interposed therebetween.

[Inkjet recording method (operation)]
FIG. 6 is a flowchart showing an example of an ink jet recording method using the ink jet recording apparatus of the present embodiment. Since this flowchart has already been described in the first embodiment, a description common to both embodiments is omitted here. Hereinafter, this embodiment will be described in detail.

(Print command (S10))
The print command instructs image data to be printed and printing. Image data is transmitted from a computer apparatus (not shown) to the ink jet recording apparatus together with a print command.

(Reduced pressure stirring operation (S11))
For example, (1) driving of the vacuum degassing mechanism 5 (decompression), (2) starting of stirring,
3) Start of driving the transport pump 9, (4) printing, (5) stop stirring, and (6) vacuum degassing mechanism 5
The process proceeds in the order of stop (decompression stop). Note that printing may be performed after any operation as long as it is after the operation of (3). (4) Printing will be described later.

If the agitation is performed first, bubbles are likely to be mixed into the ink 3. Therefore, after the pressure is reduced in the above (1), the agitation can be efficiently performed by starting the stirring in the above (2). In this embodiment, since the ink 3 is supplied using the transport pump 9, it can be supplied by the transport pump 9 while reducing the pressure (above (3)). If the decompression is stopped before the stirring is stopped, bubbles are likely to be mixed into the ink 3. Therefore, the decompression in the above (6) is stopped after the stirring in the above (5).

By providing the transport pump 9 in the supply path 6 and supplying the ink 3 to the printer head 8, it is not necessary to arrange the reservoir 2 above the printer head 8 without considering the water head difference. Therefore, the freedom degree of the position which provides the storage device 2 increases.

(Print (S12))
In printing, (4) printing is performed. Specifically, at least the ejection step (4-1) is performed, and when the ink to be used is an ultraviolet curable ink, the curing step (4-2) is performed. The printing may be performed after any operation as long as it is after the operation (3).
In addition, since the discharge process and hardening process in this embodiment are the same as that of the said 1st Embodiment, description is abbreviate | omitted here.

  In the flowchart of FIG. 7, a reduced pressure stirring operation is always performed before printing.

In the flowchart of FIG. 8, the reduced pressure stirring operation is performed before printing only when a predetermined time has elapsed since the previous reduced pressure stirring operation.

As described above, according to the present embodiment, by combining agitation and reduced pressure, sedimentation can be recovered while maintaining printing stability. In particular, when the agitation mechanism is used alone, the printing stability is adversely affected, but when combined with the decompression mechanism, the printing stability is better than that when the decompression mechanism is used alone. Show. Moreover, this embodiment differs from said 1st Embodiment, and the freedom degree of the position which provides the storage device 2 increases by providing the transport pump 9 in the supply path | route 6. FIG.

[Fifth Embodiment]
In the fifth embodiment, by providing the sub ink tank 2b, the ink 3 is reduced while decompressing.
Is different from the first embodiment in that a transport pump 9 is provided in the supply path 6.

[Liquid ejection device configuration]
FIG. 3 is a schematic diagram illustrating a modified example of the ink jet recording apparatus which is an example of the liquid ejection apparatus according to the present embodiment. Unlike the recording apparatus 21 shown in FIG. 2, the recording apparatus 31 in this modification is provided with a stirring mechanism 4a and a reservoir 2a provided with a reduced-pressure degassing mechanism 5a, for example, a reduced-pressure pump, and these mechanisms. And no reservoir 2b. Reservoir 2
b is provided closer to the printer head 8 than the transport pump 9 in the supply path 6. The reservoir 2a is a main ink tank, while the reservoir 2b is a sub ink tank.

[Inkjet recording method (operation)]
FIG. 6 is a flowchart showing an example of an ink jet recording method using the ink jet recording apparatus of the present embodiment. Since this flowchart has already been described in the first embodiment, the description of the contents common to these embodiments is omitted here. Less than,
This embodiment will be described in detail.

(Print command (S10))
The print command instructs image data to be printed and printing. Image data is transmitted from a computer apparatus (not shown) to the ink jet recording apparatus together with a print command.

(Reduced pressure stirring operation (S11))
For example, (1) driving of the vacuum degassing mechanism 5 (decompression), (2) starting of stirring,
3) Supply of ink 3 to the sub ink tank 2b, (4) printing, (5) stop stirring, and (6)
It progresses in order of the stop (decompression stop) of the decompression deaeration mechanism 5. Note that printing may be performed after any operation as long as it is after the operation of (3). (4) Printing will be described later.

If the agitation is performed first, bubbles are likely to be mixed into the ink 3. Therefore, after the pressure is reduced in the above (1), the agitation can be efficiently performed by starting the stirring in the above (2). In this embodiment, since the ink 3 is supplied to the sub ink tank 2b using the transport pump 9 ((3) above), it is possible to supply the ink while reducing the pressure. After supplying the degassed ink 3 to the sub ink tank 2b, the stirring deaeration may be stopped. If the decompression is stopped before the stirring is stopped, bubbles are likely to be mixed into the ink 3. Therefore, the decompression in the above (6) is stopped after the stirring in the above (5).

Here, the sub ink tank 2b is provided, and the sub ink tank 2 is provided by the transport pump 9.
By supplying the ink 3 to b, the main ink tank 2a is connected to the printer head 8
It becomes unnecessary to arrange | position above. Therefore, the degree of freedom of the position of the main ink tank 2a is increased.

(Print (S12))
In printing, (4) printing is performed. Specifically, at least the ejection step (4-1) is performed, and when the ink to be used is an ultraviolet curable ink, the curing step (4-2) is performed.
In addition, since the discharge process and hardening process in this embodiment are the same as that of the said 1st Embodiment, description is abbreviate | omitted here.

  In the flowchart of FIG. 7, a reduced pressure stirring operation is always performed before printing.

In the flowchart of FIG. 8, the reduced pressure stirring operation is performed before printing only when a predetermined time has elapsed since the previous reduced pressure stirring operation.
Also, in the present embodiment, unlike the first embodiment, if the tank is depressurized when there is no pump, the tank side has a negative pressure, so that ink is not supplied to the printer head. Therefore, an advantage of providing a transport pump is that ink is supplied even when the tank side is under negative pressure due to reduced pressure, that is, printing can be performed while performing a reduced pressure stirring operation.

As described above, according to the present embodiment, by combining agitation and reduced pressure, sedimentation can be recovered while maintaining printing stability. In particular, when the agitation mechanism is used alone, the printing stability is adversely affected, but when combined with the decompression mechanism, the printing stability is better than that when the decompression mechanism is used alone. Show. In addition, unlike the first embodiment, this embodiment can supply the ink 3 while reducing the pressure by providing the sub ink tank 2b, and the main ink tank by providing the transport pump 9 in the supply path 6. The degree of freedom of the position 2a is increased.

[Sixth Embodiment]
In the sixth embodiment, the ink 3 is reduced while the pressure is reduced by providing the sub ink tank 2b.
And the first degassing mechanism 5b is provided in the sub ink tank 2b.
Different from the embodiment.

[Liquid ejection device configuration]
FIG. 4 is a schematic diagram illustrating a modified example of the ink jet recording apparatus which is an example of the liquid ejection apparatus according to the present embodiment. Unlike the recording apparatus 31 shown in FIG. 3, the recording apparatus 41 in this modification includes a stirring mechanism 4 b and a vacuum degassing mechanism 5 b in the reservoir 2 b instead of including the transport pump 9 in the supply path 6. ing. The vacuum degassing mechanism 5b is, for example, a vacuum pump. The reservoir 2a is a main ink tank, while the reservoir 2b is a sub ink tank. The ink is supplied to the reservoir 2b by driving the vacuum degassing mechanism 5b.

The reservoir 2b is provided in the recording device 41. When the ink in the reservoir 2b runs out or becomes low, the reservoir 2b is replenished with ink.

[Inkjet recording method (operation)]
FIG. 6 is a flowchart showing an example of an ink jet recording method using the ink jet recording apparatus of the present embodiment. Since this flowchart has already been described in the first embodiment, the description of the contents common to these embodiments is omitted here. Less than,
This embodiment will be described in detail.

(Print command (S10))
The print command instructs image data to be printed and printing. Image data is transmitted from a computer apparatus (not shown) to the ink jet recording apparatus together with a print command.

(Reduced pressure stirring operation (S11))
For example, (1) driving (depressurization) of the vacuum degassing mechanism 5a, (2) stirring mechanism 4
a) stirring start, (3) stirring stop of stirring mechanism 4a, (4) stop of vacuum degassing mechanism 5a, (5)
Driving (decompression) of the vacuum degassing mechanism 5b, (6) start of stirring of the stirring mechanism 4b, (7) stirring mechanism 4b
(8) Stop the vacuum degassing mechanism 5b, and (9) Print.

If the agitation is performed first, bubbles are likely to be mixed into the ink 3. Therefore, after the pressure is reduced in the above (1), the agitation can be efficiently performed by starting the stirring in the above (2). Sub ink tank 2
The supply of ink 3 to b utilizes the reduced pressure in the sub ink tank 2b obtained by (5) above. Thereby, further deaeration can be performed in the sub ink tank 2b, and a transport pump is not required.

By providing the sub ink tank 2b and the decompression deaeration mechanism 5b to the sub ink tank 2b and supplying the ink 3 to the sub ink tank 2b by the decompression of the decompression deaeration mechanism 5b, the main ink tank 2a is connected to the printer head 8 It becomes unnecessary to arrange | position above. This is because the ink 3 can be supplied from the main ink tank 2a having a higher pressure to the sub ink tank 2b having a lower pressure by utilizing the pressure difference. Therefore, the degree of freedom of the position of the main ink tank 2a is increased.

Here, with regard to the operations (6) and (7) described above, stirring in the sub ink tank 2b may be performed when necessary, and may not be performed when only the ink 3 supply is required.
Therefore, a device configuration in which the sub ink tank 2b does not have the stirring mechanism 4b is given as a modification of the present embodiment.

(Print (S12))
In printing, (9) printing is performed. Specifically, at least the ejection step (9-1) is performed, and when the ink to be used is an ultraviolet curable ink, the curing step (9-2) is performed.
In addition, since the discharge process and hardening process in this embodiment are the same as that of the said 1st Embodiment, description is abbreviate | omitted here.

  In the flowchart of FIG. 7, a reduced pressure stirring operation is always performed before printing.

In the flowchart of FIG. 8, the reduced pressure stirring operation is performed before printing only when a predetermined time has elapsed since the previous reduced pressure stirring operation.
In the present embodiment, unlike the first embodiment, the vacuum degassing mechanism 5b cannot be driven during printing, that is, the pressure becomes negative and ink cannot be supplied to the head, but only the main ink tank 2a drives the vacuum stirring operation. I can keep it. In other words, since a vacuum stirring operation can be performed during printing,
Work time can be shortened.

As described above, according to the present embodiment, by combining agitation and reduced pressure, sedimentation can be recovered while maintaining printing stability. In particular, when the agitation mechanism is used alone, the printing stability is adversely affected, but when combined with the decompression mechanism, the printing stability is better than that when the decompression mechanism is used alone. Show. Also, in the present embodiment, unlike the first embodiment, the ink 3 can be supplied while the pressure is reduced by providing the sub ink tank 2b, and the pressure degassing mechanism 5b is provided in the sub ink tank 2b. The degree of freedom of the position of the main ink tank 2a is increased.

[Seventh Embodiment]
The seventh embodiment is different from the first embodiment in that the reservoir is provided in the recording apparatus by the ink cartridge mounting portion.

[Liquid ejection device configuration]
FIG. 5 is a schematic diagram illustrating a modified example of the ink jet recording apparatus that is an example of the liquid ejection apparatus according to the present embodiment. The recording device 51 includes a reservoir (ink cartridge) 2c, a stirring mechanism 4c, a drive unit 4cd, a vacuum degassing mechanism 5c, a supply path 6, a printer head 8, a reservoir mounting unit (ink cartridge mounting unit) 10, and a stirrer chip 11. The vacuum degassing mechanism mounting hole 12, the ink outlet 13, and the ink supply needle 15 are supplied.

The ink cartridge 2c corresponding to the reservoir is detachably attached to the recording apparatus 51 by the reservoir mounting portion 10 which is an ink cartridge mounting portion, and is for storing the ink 3 to be deaerated. The ink cartridge can be removed when the amount of ink is low. The stirring mechanism 4 c includes a stirrer chip 11 and a drive unit 4 cd that drives the stirrer chip 11. The stirring mechanism 4c is provided for stirring the ink 3 stored in the reservoir 2c, and the drive unit 4cd is provided in the reservoir mounting portion 10 outside the reservoir 2c. The stirrer chip 11 provided inside the reservoir 2c is for stirring the ink 3 without contacting the drive unit 4cd, for example, by driving the drive unit 4cd using magnetic force. For this reason, if the stirrer piece is provided in advance in the cartridge, the stirrer piece can be provided in the stirring mechanism as the cartridge is mounted. The vacuum degassing mechanism mounting hole 12 at the upper part of the reservoir 2c is sealed with a cap or the like before the vacuum degassing mechanism 5c, which is a vacuum pump, for example, and is attached to the vacuum degassing mechanism 5c when performing vacuum degassing. Can be attached. An ink supply needle 15 having an ink supply port is attached to the ink outlet 13 at the bottom of the reservoir 2c and the lower part of the reservoir mounting portion 10. The supply path 6 is provided for feeding the ink 3, and the ink supply needle 15 is provided.
And communicates with the reservoir 2c. The supply path 6 may include a liquid feed pump in the middle thereof. The ink 3 is supplied to the printer head 8 through the supply path 6.
The ink supply port is positioned below the tip of the ink supply needle 15 (reference numeral 1 in FIG. 5).
3 position). The ink outlet 13 is an ink supply needle 1 on the outer wall of the ink cartridge.
It is located where 5 penetrates.
A stirrer chip 11 is provided in advance in the ink cartridge 2c. This
Stirring can be performed in a non-contact manner from the drive unit 4cd provided in the reservoir mounting unit 10 outside the ink cartridge 2c. The vacuum degassing mechanism mounting hole 12 at the top of the ink cartridge 2c is sealed with a cap or the like before mounting, and the vacuum degassing mechanism 5c is mounted during use. An ink supply needle 15 provided in the reservoir mounting portion 10 is attached to the ink outlet 13 below the ink cartridge 2c.

In each of the above-described embodiments, there are a mode in which ink is supplied from the main ink tank to the printer head without passing through the sub ink tank, and a mode in which ink is supplied from the main ink tank to the printer head via the sub ink tank. is there. In the present invention, a reservoir in which vacuum degassing by the vacuum degassing mechanism and stirring by the stirring mechanism are performed is a main ink tank,
Alternatively, when a sub ink tank is provided, it can be at least one of a sub ink tank. If the degassing and stirring are performed in at least one of the reservoirs, the effect of the present invention can be obtained in the reservoir. The main ink tank may be provided in a carriage on which the printer head is mounted, or may be provided in a place different from the carriage. Further, when the main ink tank is provided at a location different from the carriage, the sub ink tank may be provided at the carriage, or may be provided at a location different from the carriage in the same manner as the main ink tank. Further, as a liquid ejecting apparatus in which the printer head is not mounted on the carriage, for example, a line ink jet printer may be used. In that case,
The main ink tank and the sub ink tank are not provided on the carriage.
In this case, the reservoir may be an ink cartridge or any container that is not an ink cartridge. In any of the above-described forms, the main ink tank may be configured as a removable ink cartridge.

[Inkjet recording method (operation)]
FIG. 6 is a flowchart showing an example of an ink jet recording method using the ink jet recording apparatus of the present embodiment. Since this flowchart has already been described in the first embodiment, the description of the contents common to these embodiments is omitted here. Less than,
This embodiment will be described in detail.

(Print command (S10))
The print command instructs image data to be printed and printing. Image data is transmitted from a computer apparatus (not shown) to the ink jet recording apparatus together with a print command.

(Reduced pressure stirring operation (S11))
The reduced pressure agitation operation is, for example, (1) driving (reduced pressure) of the reduced pressure deaeration mechanism 5c which is a reduced pressure pump
(2) Stirring start, (3) Stirring stop, (4) Stop of decompression deaeration mechanism 5c (stop decompression), and (
5) Proceed in the order of printing.

If the agitation is performed first, bubbles are likely to be mixed into the ink 3. Therefore, after the pressure is reduced in the above (1), the agitation can be efficiently performed by starting the stirring in the above (2). In the present embodiment, the liquid level of the ink 3 in the ink cartridge 2c is usually lower than that of the printer head 8, and the ink 3 is supplied utilizing the water head difference. Therefore, in the case where a liquid feed pump that supplies the ink 3 from the ink cartridge 2c to the printer head 8 is not provided, the ink 3 may not be supplied if the pressure is reduced in the ink cartridge 2c. Therefore, it is necessary to stop the decompression before printing (flow from (4) to (5) above). However, if the pressure reduction is stopped before the stirring is stopped, bubbles are likely to be mixed into the ink 3. Therefore, after the pressure reduction is stopped after the stirring stop in the above (3), the above (4) and (5) are advanced in this order.

(Print (S12))
In printing, (5) printing is performed. Specifically, at least the ejection step (5-1) is performed, and when the ink to be used is an ultraviolet curable ink, the curing step (5-2) is performed.
In addition, since the discharge process and hardening process in this embodiment are the same as that of the said 1st Embodiment, description is abbreviate | omitted here.

  In the flowchart of FIG. 7, a reduced pressure stirring operation is always performed before printing.

In the flowchart of FIG. 8, the reduced pressure stirring operation is performed before printing only when a predetermined time has elapsed since the previous reduced pressure stirring operation.

In each of the above embodiments, the liquid ejection apparatus is embodied in an ink jet recording apparatus. However, the present invention is not limited to this, and other liquids (for example, liquids in which functional material particles are dispersed, gels) Such a fluid can also be embodied in a liquid ejection device that ejects (injects). For example, a liquid material ejecting apparatus that ejects a liquid material containing materials such as electrode materials and color materials used in the manufacture of liquid crystal displays, color filters, EL (electroluminescence) displays, and surface emitting displays in a dispersed or dissolved form. Further, it may be a liquid ejecting apparatus for ejecting a bio-organic matter used for biochip manufacturing, or a liquid ejecting apparatus that is used as a precision pipette and ejects a liquid as a sample. In addition, a transparent resin liquid such as UV curable resin is used to form a liquid ejection device that ejects lubricating oil pinpoint to precision machines such as watches and cameras, and micro hemispherical lenses (optical lenses) used in optical communication elements. A liquid discharge device that discharges a liquid onto the substrate, a liquid discharge device that discharges an etching solution such as acid or alkali to etch the substrate, and a fluid discharge device that discharges gel. The present invention can be applied to any one of these discharge devices.

As described above, according to the present embodiment, by combining agitation and reduced pressure, sedimentation can be recovered while maintaining printing stability. In particular, when the agitation mechanism is used alone, the printing stability is adversely affected, but when combined with the decompression mechanism, the printing stability is better than that when the decompression mechanism is used alone. Show.
Note that the advantage of the on-carriage method is that it is assumed to be located at the top of the printer head and the flow path to the printer head is short, so there is a difference in flow resistance and water head value when supplying ink to the printer head. Therefore, a system for supplying ink with a pump or the like is not necessary, and as a result, the cost related to the ink supply structure is reduced.

Here, the significance of performing vacuum degassing while stirring, that is, the features from the first embodiment to the seventh embodiment are mainly the following two points. The first point is to remove bubbles that are mixed when stirring is performed to eliminate sedimentation of the pigment component of the ink (cake formation after a long time). The second point is to remove the increased dissolved air by dissolving in the ink from the beginning, dissolving into the ink from the air layer of the ink container, or mixing into the ink container through the wall of the ink container. In the case of deaeration for the purpose of improving the printing stability, the deaeration efficiency can be improved by deaeration while stirring.

〔ink〕
The composition of the ink (hereinafter also referred to as “ink composition”) 3 in the present embodiment is not particularly limited. For example, when the ink is an ultraviolet curable ink, it contains at least a polymerizable compound and a photopolymerization initiator. Further, when the ink is a colored ink other than the clear ink, a color material is also included. Hereinafter, each component contained in or included in the ink composition will be described.

(Polymerizable compound)
The polymerizable compound is not particularly limited as long as it is a compound that polymerizes and solidifies upon irradiation with ultraviolet rays by the action of a photopolymerization initiator described later. For example, various monomers and oligomers having a monofunctional group, a bifunctional group, and a polyfunctional group having three or more functional groups can be used.

Here, the “monomer” in the present specification means a molecule having a weight average molecular weight of 100 to 3,000. As used herein, “oligomer” means a weight average molecular weight of 500 to 20
, 000 molecules.

The monomer is not particularly limited. For example, unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid, crotonic acid, isocrotonic acid and maleic acid, salts or esters thereof, urethane, amide and anhydrides thereof, Examples include acrylonitrile, styrene, various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes.
An N-vinyl compound may be included as another monofunctional monomer or polyfunctional monomer.
N-vinyl compounds include N-vinylformamide, N-vinylcarbazole, N-vinyl
Examples thereof include vinylacetamide, N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, and derivatives thereof.

Examples of the oligomer include oligomers formed from the above monomers such as linear oligomers and hyperbranched oligomers, epoxy (meth) acrylates, aliphatic urethane (meth) acrylates, aromatic urethane (meth) acrylates, poly Examples include ether (meth) acrylate and polyester (meth) acrylate.

Among those listed above, esters of (meth) acrylic acid, that is, (meth) acrylates are preferred. When (meth) acrylate is used as the polymerizable compound, the curability of the ink and the adhesion of the cured film to the adherend can be improved.
In the present specification, “(meth) acrylate” means acrylate and its corresponding methacrylate, and “(meth) acryl” means acryl and its corresponding methacryl.

Among the above (meth) acrylates, monofunctional (meth) acrylates include, for example, isoamyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, iso Myristyl (meth) acrylate, isostearyl (meth) acrylate, 2-ethylhexyl-diglycol (meth) acrylate, 2-hydroxybutyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxydiethylene glycol ( (Meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypropylene glycol (meth) acrylate, phenoxyethyl (meth) acrylate , Tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, lactone-modifiable Examples include flexible (meth) acrylate, t-butylcyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, and isobornyl (meth) acrylate.

Among the (meth) acrylates, examples of the bifunctional (meth) acrylate include triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, and dipropylene glycol di ( (Meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonane Diol di (
(Meth) acrylate, neopentyl glycol di (meth) acrylate, dimethylol-
Tricyclodecane di (meth) acrylate, EO (ethylene oxide) adduct of bisphenol A di (meth) acrylate, PO of bisphenol A (propylene oxide)
Examples include adduct di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, and polytetramethylene glycol di (meth) acrylate.

Among the above (meth) acrylates, trifunctional or more polyfunctional (meth) acrylates include, for example, trimethylolpropane tri (meth) acrylate, EO-modified trimethylolpropane tri (meth) acrylate, and pentaerythritol tri (meth) acrylate. ,
Pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, glycerin propoxytri (meth) acrylate, cowprolactone-modified trimethylolpropane tri (meth) acrylate, pentaerythritol ethoxy Tetra (meth) acrylate,
And caprolactam-modified dipentaerythritol hexa (meth) acrylate.

Among these, since the stretchability of the coating film (coating layer) at the time of curing is high and has a low viscosity, from the viewpoint that injection stability at the time of ink jet recording is easily obtained, as a polymerizable compound,
It is preferable that monofunctional (meth) acrylate is included. Furthermore, it is more preferable to use a monofunctional (meth) acrylate and a bifunctional (meth) acrylate together from the viewpoint of increasing the hardness of the coating layer.

Among the (meth) acrylates listed above, at least one selected from the group consisting of dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, and 1,6-hexanediol acrylate is preferable. At least one of propylene glycol di (meth) acrylate and tripropylene glycol di (meth) acrylate is more preferable. In this case, since the balance of viscosity, curability, and skin irritation is excellent, it is effective for inkjet inks that are easily affected by viscosity during ejection, and skin irritation is also reduced.
In addition to the (meth) acrylate monomer, the photopolymerizable compound is a conventionally known (meth)
An acrylate oligomer may further be included.

  Said polymeric compound may be used individually by 1 type, and may use 2 or more types together.

(Photopolymerization initiator)
The polymerization initiator is not particularly limited as long as it generates active species such as radicals and cations by the energy of ultraviolet rays and initiates polymerization of the polymerizable compound. A radical polymerization initiator or a cationic polymerization initiator can be used, and among these, it is preferable to use a radical polymerization initiator. By using the radical polymerization initiator, there is no inhibition of polymerization due to humidity as in the case of cationic polymerization, so that an advantageous effect that the printing environment is not selected can be obtained.

In addition, although it does not specifically limit as a cationic polymerization initiator, For example, the chemical amplification type photoresist and the compound utilized for photocationic polymerization are used (Organic Electronics Materials Research Group, "Organic material for imaging", Shin Publishing (1993), pages 187 to 192, Technical Information Association, “Photocuring Technology”, photoacid generator introduced in 2001). As an example of a compound suitable for this embodiment, first, B (C ₆ F ₅ ) ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , aromatic onium compounds such as diazonium, ammonium, iodonium, sulfonium,
CF ₃ SO ₃ ^- salts. Those with borate compounds as counter anions
It is preferable because of its high acid generation ability. Moreover, the sulfonated substance which generate | occur | produces a sulfonic acid, the halide which photogenerates a hydrogen halide, and an iron allene complex are also mentioned suitably. Examples of commercially available cationic polymerization initiators include UV1-6992 (triphenylsulfonium salt, manufactured by The Dow Chemical Company).

Examples of the radical polymerization initiator include aromatic ketones, acylphosphine compounds, aromatic onium salt compounds, organic peroxides, thio compounds, hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, and azinium compounds. , Metallocene compounds, active ester compounds, compounds having a carbon halogen bond, and alkylamine compounds.

Specific examples of the radical polymerization initiator include acetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, Carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4′-dimethoxybenzophenone, 4,4′-diaminobenzophenone, Michler's ketone, benzoin propyl ether, benzoin ethyl ether, benzyldimethyl ketal, 1- (4-isopropylphenyl) 2-hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one,
Thioxanthone, diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, bis (2,4,6-trimethylbenzoyl) ) -Phenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2,4-diethylthioxanthone and bis- (2,6-dimethoxybenzoyl)-
2,4,4-trimethylpentylphosphine oxide is exemplified.

Examples of commercially available radical polymerization initiators include IRGACURE 651 (2,2-
Dimethoxy-1,2-diphenylethane-1-one), IRGACURE 184 (1-
Hydroxy-cyclohexyl-phenyl-ketone), DAROCUR 1173 (2-hydroxy-2-methyl-1-phenyl-propan-1-one), IRGACURE 29
59 (1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one), IRGACURE 127 (2-hydroxy-1- {4
-[4- (2-Hydroxy-2-methyl-propionyl) -benzyl] phenyl] -2-
Methyl-propan-1-one}, IRGACURE 907 (2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one), IRGACURE 36
9 (2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1), IRGACURE 379 (2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone), DAR
OCUR TPO (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide), IRGACURE 819 (bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide), IRGACURE 784 (bis (η5-2,4 -Cyclopentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrole-1)
-Yl) -phenyl) titanium), IRGACURE OXE 01 (1.2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)]), IR
GACURE OXE 02 (ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (O-acetyloxime)), IRGA
CURE 754 (a mixture of oxyphenylacetic acid, 2- [2-oxo-2-phenylacetoxyethoxy] ethyl ester and oxyphenylacetic acid, 2- (2-hydroxyethoxy) ethyl ester) (above, Ciba Japan KK), KAYACU
RE DETX-S (2,4-diethylthioxanthone) (Nippon Kayaku
Co., Ltd.), Lucirin TPO, LR8883, LR8970 (above, BA
SF) and Ubekrill P36 (UCB).

The said photoinitiator may be used individually by 1 type, and may be used in combination of 2 or more type.

[Color material]
The ink composition in the present embodiment may further include a color material. The color material is at least one of a pigment and a dye. Among these, an ink that is an example of a liquid is a liquid containing a pigment because the effect of applying an ink jet recording method characterized by performing degassing under reduced pressure while stirring and an ink jet recording apparatus used for the method is very large It is preferably a composition, more preferably a liquid composition containing a metal oxide, and further preferably a pigment-based white ink.

(Pigment)
In this embodiment, the light resistance of the ink composition can be improved by using a pigment as the color material. As the pigment, both inorganic pigments and organic pigments can be used.

As the inorganic pigment, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black and channel black, iron oxide, and titanium oxide can be used. Among these, as described above, when the pigment-based ink is a white ink, it is preferable to use titanium oxide from the viewpoint of maintaining good whiteness.

Organic pigments include insoluble azo pigments, condensed azo pigments, azo lakes and chelate azo pigments, phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments. Polycyclic pigments such as, dye chelates (for example, basic dye chelates, acid dye chelates, etc.), dye lakes (basic dye lakes, acid dye lakes), nitro pigments,
Examples include nitroso pigments, aniline black, and daylight fluorescent pigments.

The said pigment may be used individually by 1 type, and may use 2 or more types together. Further, any pigment not described in the color index can be used as long as it is insoluble in water.

(dye)
In the present embodiment, a dye can be used as the color material. The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used. Examples of the dye include C.I. I. Acid Yellow 17, 23, 42, 44, 79, 14
2, C.I. I. Acid Red 52, 80, 82, 249, 254, 289, C.I. I. Acid Blue 9, 45, 249, C.I. I. Acid Black 1, 2, 24, 94, C.I. I.
Food Black 1, 2, C.I. I. Direct yellow 1, 12, 24, 33, 50, 55
58, 86, 132, 142, 144, 173, C.I. I. Direct red 1, 4, 9
, 80, 81, 225, 227, C.I. I. Direct blue 1, 2, 15, 71, 86,
87, 98, 165, 199, 202, C.I. I. Directed Black 19, 38, 51,
71,154,168,171,195, C.I. I. Reactive Red 14, 32, 55
79, 249, C.I. I. Reactive black 3, 4, and 35 are mentioned.

The ink composition can also be applied to clear ink that does not contain a color material. That is, even with clear ink that does not contain a pigment, excellent printing stability can be achieved by a system having a degassing step of stirring and degassing. This degassing step can obtain the effectiveness more remarkably in the ink having high viscosity.
Further, the pigment can be used by being dispersed in a dispersant or a surfactant described later.

(Other ingredients)
The ink composition in the present embodiment may contain components other than the components listed above. Although it does not specifically limit as the said component, For example, a dispersing agent is mentioned.

Although it does not specifically limit as said dispersing agent, For example, the dispersing agent currently used for preparing pigment dispersion liquids, such as a polymer dispersing agent, Ajimoto fine techno Co., Ltd. Ajispar series, Abyssia Co., Ltd. Examples include Solspers series manufactured by BYK Chemie, Dispersic series manufactured by BYK Chemie, and Disparon series manufactured by Enomoto Kasei Co., Ltd. The polymer dispersant is not particularly limited, and examples thereof include polyoxyalkylene polyalkylene polyamines, vinyl polymers and copolymers, acrylic polymers and copolymers, polyesters, polyamides, polyimides, polyurethanes, amino polymers, silicon-containing polymers, and the like. The thing which has 1 or more types as a main component among a sulfur polymer, a fluorine-containing polymer, an epoxy resin, etc. is mentioned.

The surfactant is not particularly limited. For example, as a silicone surfactant, a polyester-modified silicone or a polyether-modified silicone can be used.
It is particularly preferable to use polyether-modified polydimethylsiloxane or polyester-modified polydimethylsiloxane. Specific examples include BYK-347, BYK-348, BY
K-UV3500, 3510, 3530, 3570 (BYK Ja
pan KK)).

Further, the ink composition includes a polymerization accelerator, a slip agent, a penetration accelerator, a wetting agent (humectant),
A fixing agent, an antifungal agent, an antiseptic, a surfactant, an antioxidant, a polymerization inhibitor, an ultraviolet absorber, a chelating agent, a pH adjusting agent, and a thickening agent may be included.

[Recording medium]
Examples of the recording medium include an absorptive or non-absorbable recording medium. The ink jet recording method of the present embodiment has various absorption performances from a non-absorbable recording medium in which penetration of the water-soluble ink composition is difficult to an absorbent recording medium in which penetration of the water-soluble ink composition is easy. Widely applicable to recording media.

The absorbent recording medium is not particularly limited. For example, plain paper such as electrophotographic paper having high water-based ink permeability, ink jet paper (an ink absorbing layer composed of silica particles or alumina particles, or polyvinyl alcohol). Art paper and coats used for general offset printing with relatively low permeability of water-based ink from (PVA) and inkjet pyrrole (PVP) and other ink-absorbing layers composed of hydrophilic polymers such as polyvinylpyrrolidone (PVP). Examples thereof include paper and cast paper.

The non-absorbable recording medium is not particularly limited. For example, films and plates of plastics such as polyvinyl chloride, polyethylene, polypropylene, and polyethylene terephthalate (PET), and metals such as iron, silver, copper, and aluminum are used. Examples thereof include a plate, a metal plate produced by vapor deposition of these various metals, a plastic film, a plate made of an alloy such as stainless steel or brass.

Hereinafter, the embodiments of the present invention will be described more specifically with reference to examples and comparative examples. However, the embodiments of the present invention are not limited to these examples.

[Materials used]
The materials used in the examples and comparative examples are as shown below.
[Ink composition]
(Photopolymerizable compound)
Dipropylene glycol diacrylate (bifunctional monomer, abbreviated as DPGDA in Table 1)
Tripropylene glycol diacrylate (bifunctional monomer, abbreviated as TPGDA in Table 1)
(Photopolymerization initiator)
・ IRGACURE 819 (manufactured by Ciba Japan KK)
・ DAROCUR TPO (Ciba Japan)
・ KAYACURE DETX-S (Nippon Kayaku Co., Ltd.)
(Pigment)
・ Titanium oxide (dispersant)
・ Polyoxyalkylene polyalkylene polyamine (recording medium)
-Transparent PET film PET50A PL Thin 11BL (Lintec Co.,
Ltd.)

[Example 1, Comparative Examples 1-3]
[Production of UV-curable ink composition]
First, a pigment dispersion was prepared. In Table 1 below, pigments and dispersants whose types and blending amounts are described in parts by mass were mixed and stirred. The obtained mixture was subjected to a dispersion treatment for 6 hours together with zirconia beads (diameter 1.5 mm) using a sand mill (manufactured by Yaskawa Seisakusho). Thereafter, the zirconia beads were separated with a separator to obtain a pigment dispersion used in Examples and Comparative Examples.

Next, after preparing a polymerizable compound and a photopolymerization initiator described in Table 1 below in the pigment dispersion obtained above, these materials were mixed and stirred using a stirrer (content unit is % By mass). In this way, an ultraviolet curable white ink composition was obtained.

[Method for producing inkjet recorded matter]
Inkjet recordings were produced using a line printer having the configuration shown in FIG.
An ultraviolet curable ink composition was discharged onto a transparent PET film so as to have a film thickness of 10 μm,
I landed. Thereafter, this transparent PET film was cured with a metal halide lamp (irradiation energy: 200 mJ / cm ² ). In this way, an ink jet recorded matter having white ink printed on a transparent PET film was produced.
The operation up to printing will be described in the following experimental example.

[Measurement / Evaluation Items]
[Evaluation of printing stability]
The above-mentioned ink was filled in a printer head of a line printer having the configuration shown in FIG. 1, and was left as it was for one week after confirming ejection of ink from all nozzles. Thereafter, the stirring mechanism and the vacuum degassing mechanism were operated with the respective combinations shown in Table 2 below for 30 minutes, and then ink was continuously discharged from all the nozzles for 15 minutes, followed by solid printing, and the ratio of the number of nozzles missing was determined. The results are shown in Table 2 below.

[Measurement of whiteness (L ^* value)]
The above-mentioned ink was filled in a printer head of a line printer having the configuration shown in FIG. 1, and was left as it was for one week after confirming ejection of ink from all nozzles. Then, after operating for 30 minutes with each combination shown in Table 2 below for the stirring mechanism and deaeration mechanism, ink was discharged from all nozzles.
After continuous discharge for 5 minutes, solid printing was performed. Inkjet recording is SpectroScan (GRATAG
L ^* value was measured using Spectrolino (manufactured by GRATAG) on a black table (manufactured by Co., Ltd.) to obtain the whiteness. In the measurement, when there was a missing dot in the ink jet recorded material, a portion where the missing dot was as small as possible was measured. It is shown in Table 2 below.

From the results of Table 2 above, by using the ink jet recording apparatus of the present invention provided with a reservoir (ink tank) equipped with a stirring mechanism and a vacuum degassing mechanism, the ink jet is excellent in printing stability and hardly causes defective printing. It became clear that a record was obtained.

1, 2, 31, 41, 51 ... recording device, 2 ... reservoir, 2a ... reservoir, main ink tank, 2b ... reservoir, sub ink tank, 2c ... reservoir, ink cartridge, 3 ... ink, 4 ... Stirring mechanism, 4a ... stirring mechanism, 4b ... stirring mechanism, 4c ... stirring mechanism, 4cd ... drive unit, 5 ... depressurized degassing mechanism, 5a ... depressurized degassing mechanism, 5b ... depressurized degassing mechanism, 5c ... depressurized degassing mechanism ,
DESCRIPTION OF SYMBOLS 6 ... Supply path, 7 ... Check valve, 8 ... Printer head, 9 ... Transport pump, 10 ... Reservoir mounting part, ink cartridge mounting part, 11 ... Stirrer chip, 12 ... Vacuum deaeration mechanism mounting hole, 13 ... Ink Take-out port, 15 ... ink supply needle.

Claims (10)

A printer head that discharges liquid from a nozzle toward a medium to be discharged; a supply path that supplies the liquid to the printer head; a reservoir that is connected to the supply path and stores the liquid; and the reservoir in the reservoir A vacuum degassing mechanism for vacuum degassing the liquid; an agitation mechanism for stirring the liquid in the reservoir; and a light irradiation means for irradiating the liquid landed on the medium to be ejected with ultraviolet light to cure the liquid. , Degassing while stirring the liquid in the reservoir,
A liquid ejection apparatus, wherein the liquid is an ultraviolet curable ink containing at least a polymerizable compound and a photopolymerization initiator.   The liquid ejecting apparatus according to claim 1, wherein the liquid is a white ink containing a metal oxide as a coloring material.   The liquid ejection apparatus according to claim 1, wherein the ultraviolet curable ink includes at least an acylphosphine oxide compound as a photopolymerization initiator.   The said light irradiation means is a light emitting diode which has a peak wavelength in the range of 360-400 nm, and the irradiation amount of the ultraviolet-ray used for hardening is 50-15,000 mJ / cm <2>, Any one of Claims 1-3. Liquid discharge device.   The liquid discharge apparatus according to any one of claims 1 to 4, wherein a degree of pressure reduction in the reservoir by the vacuum degassing mechanism is 0.03 to 0.08 MPa.   The liquid ejecting apparatus according to claim 1, wherein the printer head is provided in a carriage, and the reservoir is provided in the carriage.   The liquid ejecting apparatus according to claim 1, wherein the printer head is provided in a carriage, and the reservoir is provided in a place other than the carriage.   The liquid ejecting apparatus according to claim 1, wherein the reservoir is a cartridge.   The liquid ejection device according to claim 1, further comprising a transport pump provided in the supply path.   The liquid ejecting apparatus according to claim 1, wherein the reservoir is a sub tank provided in the middle of a supply path.