WO2013153910A1 - Inkjet recording device - Google Patents

Description

Inkjet recording device

The present invention relates to head cleaning of an ink jet recording apparatus.

Conventionally, in an inkjet recording apparatus that transports a recording medium and forms an image by ejecting ink droplets from a recording head onto the transported recording medium, as a method of head cleaning for maintaining a good ink ejection state, Wiping the ink discharge surface of the recording head is performed. As one of the wiping means, as described in Patent Document 1, a method of wiping the ink discharge surface by rotating the outer peripheral portion that has absorbed the cleaning liquid of the cleaning roller in contact with the ink discharge surface has been proposed. ing. Here, the ink ejection surface is a surface on which ejection openings of nozzles that eject ink are formed, and is a surface that faces a recording medium during image recording.
According to this method, a high cleaning effect can be obtained by the wiping by the relative movement of both at the contact portion between the cleaning roller and the ink ejection surface and the ink removing action by the cleaning liquid.

Japanese Patent No. 3924979

However, when the ink discharge surface of the recording head is wiped with the cleaning roller that has absorbed the cleaning liquid as in the above-described prior art, high ink removability can be obtained, but the cleaning liquid remains on the ink discharge surface after wiping, and the remaining cleaning liquid There is a problem of causing a problem in ink ejection in the next recording operation.
This is because, for example, the cleaning liquid remaining on the ink discharge surface remains in the form of water droplets so as to cover the ink discharge ports, or remains in the vicinity of the ink discharge ports so that the ink droplets are not discharged. It appears as a phenomenon such as the flight direction of the aircraft changing.

Accordingly, the present invention provides an ink jet recording apparatus having a head cleaning device for wiping the ink ejection surface of a recording head with a cleaning roller that has absorbed a cleaning liquid, while achieving ink removability by wiping, and an ink ejection surface after wiping. It is an object of the present invention to maintain a good ink discharge performance by suppressing the remaining amount of the cleaning liquid.

The invention according to claim 1 for solving the above-described problems is an inkjet recording apparatus that forms an image by ejecting ink droplets from an inkjet head.
A head cleaning device for wiping the ink discharge surface of the inkjet head with a cleaning roller that has absorbed the cleaning liquid;
A control device that controls rotation of the cleaning roller and movement of the inkjet head to control head cleaning work;
The control device controls the head cleaning operation as follows:
The ink jet head is moved to bring the ink discharge surface into contact with the outer peripheral surface of the cleaning roller, and a relative speed between the ink discharge surface in contact with the outer peripheral surface in contact with the ink discharge surface is controlled to a predetermined value or more. 1 control,
After the first control, the relative speed between the ink discharge surface and the outer peripheral surface in contact with the ink discharge surface and the outer peripheral surface is controlled to zero or a value lower than the predetermined value. An ink jet recording apparatus that executes a second control for separating the ink discharge surface and the outer peripheral surface.

According to a second aspect of the present invention, in the first control, the control device controls the moving direction of the inkjet head and the moving direction of the outer peripheral surface at the contact portion with the ink discharge surface in opposite directions. The inkjet recording apparatus according to Item 1.

The invention according to claim 3 is the ink jet recording apparatus according to claim 1 or 2, wherein the control device controls the predetermined value as 100 mm / s in the first control.

According to a fourth aspect of the present invention, in the first, second, or third aspect, the control device controls the relative speed in the second control to be not less than −30 mm / s and not more than 30 mm / s. Inkjet recording apparatus.

According to a fifth aspect of the present invention, the head cleaning device comprises:
A cleaning liquid container for supplying the cleaning liquid to the wiping member by immersing the wiping member constituting the outer peripheral surface of the cleaning roller in the cleaning liquid;
The impregnation amount adjusting means for adjusting the amount of the cleaning liquid impregnated in the wiping member by squeezing a part of the cleaning liquid impregnated in the wiping member from the wiping member. An ink jet recording apparatus according to claim 1.

According to a sixth aspect of the present invention, the control device executes a control for discharging ink from the nozzles of the inkjet head before the first control as the control of the head cleaning operation. Item 6. The inkjet recording device according to any one of Items 5 above.

According to the present invention, the cleaning roller that has absorbed the cleaning liquid by the first control is wiped by sliding at a high relative speed with respect to the ink ejection surface of the inkjet head, thereby effectively removing the ink and cleaning. After that, the cleaning liquid remaining on the ink discharge surface during the first control is cleaned by bringing the cleaning roller into contact with the ink discharge surface of the inkjet head at a relative speed of zero or low relative speed by the second control. Since the ink is removed by being absorbed by the roller, it is possible to maintain good ink discharge properties by suppressing the amount of cleaning liquid remaining on the ink discharge surface after wiping while achieving ink removability by wiping.

1 is a perspective view showing a main configuration of an ink jet recording apparatus according to a first embodiment of the present invention. It is sectional drawing of the cleaning apparatus which concerns on 1st Embodiment of this invention, and an inkjet is also shown. It is sectional drawing which shows the process of the cleaning operation | work which concerns on 1st Embodiment of this invention, Comprising: The state immediately before 1st control is shown. It is sectional drawing which shows the process of the cleaning operation | work which concerns on 1st Embodiment of this invention, Comprising: The state immediately before 2nd control is shown. It is a control flowchart of the cleaning operation | work which concerns on 1st Embodiment of this invention. It is sectional drawing of the cleaning apparatus which concerns on 2nd and 3rd embodiment of this invention. It is sectional drawing which shows the process of the cleaning operation | work which concerns on 2nd Embodiment of this invention, Comprising: The state immediately before 1st control is shown. It is sectional drawing which shows the process of the cleaning operation | work which concerns on 2nd Embodiment of this invention, Comprising: The state immediately before 2nd control is shown. It is sectional drawing which shows the process of the cleaning operation | work which concerns on 3rd Embodiment of this invention, Comprising: The state immediately before 1st control is shown. It is sectional drawing which shows the process of the cleaning operation | work which concerns on 3rd Embodiment of this invention, Comprising: The state immediately before 2nd control is shown. It is a typical block diagram of the head cleaning apparatus in the apparatus of an example of embodiment of this invention. It is a typical block diagram of the head cleaning apparatus in the apparatus of an example of embodiment of this invention. It is a typical perspective view of an example of the washing | cleaning liquid supply mechanism in the apparatus of an example of embodiment of this invention. It is typical sectional drawing of an example of the washing | cleaning liquid supply mechanism in the apparatus of an example of embodiment of this invention. It is a typical block diagram of an example of the washing | cleaning liquid supply mechanism in the apparatus of an example of embodiment of this invention. It is a typical block diagram of an example of the washing | cleaning liquid supply mechanism in the apparatus of an example of embodiment of this invention. It is a typical block diagram of an example of the washing | cleaning liquid collection | recovery mechanism in the apparatus of an example of embodiment of this invention. It is a typical block diagram of an example of the washing | cleaning liquid collection | recovery mechanism in the apparatus of an example of embodiment of this invention. It is a typical block diagram of an example of the cleaning roller drive mechanism in the apparatus of an example of embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following is one embodiment of the present invention and does not limit the present invention.

[First Embodiment]
First, a first embodiment of the present invention will be described with reference to FIGS.
The ink jet recording apparatus 1 according to the present embodiment shown in FIG. 1 adopts a scanning recording method. In the scanning image recording apparatus, a recording head is mounted on a carriage and reciprocates in the main scanning direction X, and the recording medium 20 is conveyed in the sub-scanning direction Y.
In FIG. 1, 10 is a head unit, 11 is an inkjet head, 12 is an ink pack, 13 is an ink sub-tank, 14 and 15 are ink cables, and 16 is a cable damper.
The head unit 10 is a unit in which a plurality of inkjet heads 11 are mounted. Although FIG. 1 illustrates an inkjet recording apparatus on which four inkjet heads 11 are mounted, this is merely an example, and the number of inkjet heads 11 is not limited. The head unit 10 is transported in the X direction by a head transport mechanism (not shown).
The ink cables 14 and 15 form an ink supply path, and connect the ink pack 12 to the ink jet head 11 through the ink sub tank 13. The cable damper 16 is a shock absorber that holds a portion of the ink cable 15 near the ink jet head 11 and is transported in the X direction together with the head unit 10. The force applied to the ink in the ink cable 15 by the cable damper 16 during acceleration of the head unit 10 is relaxed, and the ink pressure in the head 11 is prevented from changing.
The recording medium 20 is hung on the conveyance rollers 21 and 22, the lower surface is supported by the platen 23, and is disposed to face the inkjet head 11. The recording medium 20 is arranged in the Y direction by a recording medium conveyance mechanism (not shown) including the conveyance rollers 21 and 22. Be transported. The forms of the recording medium 20 and the recording medium transport mechanism are not particularly limited.

A head cleaning device 30 is disposed next to the X direction of the recording medium 20 at a portion facing the head 11. The head cleaning device 30 includes a cleaning roller 31, a cleaning liquid storage container 32, and a squeezing roller 33 that constitutes an impregnation amount adjusting means. A cleaning liquid tank 40 is connected to the cleaning liquid storage container 32, and the cleaning liquid is supplied from the cleaning liquid tank 40 to the cleaning liquid storage container 32. Further, a suction pump 41 is connected to the cleaning liquid storage container 32 so that the cleaning liquid stored in the cleaning liquid storage container 32 can be sucked. The suction pump 41 is also connected to the head cap 42, and the suction pump 41 and the head cap 42 constitute a suction device that sucks ink and the like from the head 11.

As shown in FIG. 2, the cleaning roller 31 has a wiping member 31a that absorbs the cleaning liquid. 31b is a shaft member. The outer peripheral surface of the cleaning roller 31 is constituted by a wiping member 31a. The outer peripheral surface is brought into contact with the ink discharge surface 11a of the inkjet head 11, and the ink discharge surface 11a is wiped by the wiping member 31a. The ink jet head 11 is formed with nozzles for ejecting ink droplets, and the ink ejection surface 11a is a surface on which an ejection port of a nozzle for ejecting ink is formed, and is a surface facing the recording medium 20 during image recording. is there. By immersing the wiping member 31a in the cleaning liquid 34 stored in the cleaning liquid storage container 32, the cleaning liquid is supplied to the wiping member 31a. An alkaline cleaning liquid is used as the cleaning liquid 34. The amount of the cleaning liquid impregnated in the wiping member 31a is adjusted by pressing the squeezing roller 33 against the wiping member 31a to squeeze a part of the cleaning liquid impregnated in the wiping member 31a from the wiping member 31a.
The cleaning roller 31 is rotationally driven by a drive mechanism (not shown) and can move up and down. As shown in FIG. 2, the apex height T of the cleaning roller 31 can be raised to a range higher than the height B of the ink ejection surface 11a, and the wiping member 31a is ejected by passing the head 11 in this state. It can be pressed against the surface 11a.
Further, it can be lowered to a position where the apex height T is lower than the height B. In this state, the head 11 can be passed without contacting the cleaning roller 31.

The ink jet recording apparatus of the present embodiment has a control device (not shown) that controls the above-described units. That is, the control device controls the inkjet head 11, the head transport mechanism, the recording medium transport mechanism, the head cleaning device 30, and the suction pump 41, and controls the head cleaning operation described below in addition to the image recording operation. In particular, in the control of the head cleaning operation, the control device controls not only the movement of the inkjet head 11 but also the rotation and vertical movement of the cleaning roller 31.

First, an outline of the head cleaning operation will be described with reference to FIGS. 3A and 3B. 3A and 3B, the cleaning liquid container 32 is not shown (the same applies to FIGS. 6A, 6B, 7A, and 7B).
The control performed by the control device to realize a series of head cleaning operations includes a first control and a second control.
As the first control, as shown in FIG. 3A, the cleaning roller 31 is controlled to a height that presses the ink discharge surface as described above, the head unit 10 is moved, and the ink discharge surface 11a is moved to the cleaning roller 31. Is brought into contact with the outer peripheral surface 31c of the top. The moving speed V1 of the head unit 10 and the moving speed of the outer peripheral surface of the cleaning roller 31 are R1. The speed R1 is not the rotational speed but the moving speed of the outer peripheral surface. Therefore, the moving speed R1 depends on the radius of the cleaning roller 31.
The control device controls the moving direction of the inkjet head 11 and the moving direction of the outer peripheral surface 31c at the contact portion with the ink discharge surface 11a in opposite directions. Therefore, as indicated by the arrows in FIG. 3A, the speed V1 and the speed R1 are in opposite directions. At this time, the relative speed Vo of the outer peripheral surface 31c to the ink ejection surface 11a is expressed as Vo = V1 + R1. The control device causes the cleaning roller 31 to wipe the ink ejection surface 11a at a speed of (V1 + R1). In response to this first control, the head cleaning device 30 wipes the ink ejection surface 11 a of the inkjet head 11 by the cleaning roller 31 that has absorbed the cleaning liquid 34.
While the ink 60 adhering to the ink discharge surface 11a is softened and dissolved by the cleaning liquid impregnated in the wiping member 31a of the cleaning roller 31, the ink 60 is efficiently removed from the ink discharge surface 11a by the action of wiping. In order to obtain a sufficient ink removing effect, Vo ≧ 100 (mm / s). That is, in the first control, the control device controls the lower limit value of the relative speed Vo as 100 mm / s.

Next, the control device executes second control.
In the second control, the cleaning liquid 61 remaining on the ink ejection surface 11a during the first control is absorbed by the cleaning roller 31 and removed. Therefore, as shown in FIG. 3B, the head unit 10 is moved at the moving speed V2 in the direction opposite to that in the first control, the ink discharge surface 11a is brought into contact with the top outer peripheral surface 31c of the cleaning roller 31, and is left as it is. Pass as shown by reference numeral 10A. At this time, the relative speed Vf of the outer peripheral surface 31c to the ink ejection surface 11a is expressed as Vf = V2-R1. In the present embodiment, the height and rotation state of the cleaning roller 31 in the second control are the same as those in the first control.
In this second control, the cleaning roller 31 is not rubbed against the ink ejection surface 11a in order to effectively absorb the cleaning liquid 61 by the cleaning roller 31. That is, Vf is set to zero as much as possible and the head unit 10 is passed while maintaining the contact position between the ink discharge surface 11a and the cleaning roller 31 as little as possible, thereby separating the ink discharge surface 11a from the outer peripheral surface 31c.
Due to the action of the squeezing roller 33, the wiping member 31a in which the amount of the cleaning liquid impregnated is moderately adjusted is separated through a period in which the wiping member 31a is pressed against the ink ejection surface 11a without almost rubbing the ink ejection surface 11a. The cleaning liquid 61 remaining on the ink ejection surface 11a during the control is absorbed by the wiping member 31a and removed from the ink ejection surface 11a.
As a result, the amount of the cleaning liquid remaining on the ink ejection surface 11a after wiping is suppressed, the ink ejection performance of the inkjet head 11 can be maintained well, and an image can be recorded with high accuracy.
In order to sufficiently suppress the amount of the cleaning liquid remaining on the ink discharge surface 11a so as not to affect the image recording, -30 (mm / s) ≦ Vf ≦ 30 (mm / s) is set. That is, the control device controls the relative speed Vf in the second control to be −30 mm / s or more and 30 mm / s or less.
When the relative speed Vf is positive, the speed V2 is greater than the speed R1, and the outer peripheral surface 31c moves slightly backward in the movement direction of the head 11 with respect to the ink ejection surface 11a. When the relative speed Vf is negative, the speed R1 is greater than the speed V2, and the outer peripheral surface 31c moves slightly forward in the moving direction of the head 11 with respect to the ink discharge surface 11a.

Next, cleaning operation control will be described with reference to the flowchart of FIG. The control device executes the following control steps as control of the cleaning operation.
First, after the head unit 10 is moved onto the head cap 42, the head cap 42 is raised, and the lower end portion of the inkjet head 11 where the ink ejection surface 11a is disposed is capped with the head cap 42 (step S1). .
Next, the suction pump 41 is driven to perform ink suction through the head cap 42, and the ink is discharged from the nozzles of the inkjet head 11 (step S2). In addition, since it is only necessary to realize the discharge of the ink, the pressure in the head 11 may be increased to discharge the ink from the nozzle instead of the suction from the ink discharge port of the nozzle.
After the ink is discharged, the suction pump 41 is stopped (step S3).

Next, the cleaning roller 31 is rotationally driven, and the cleaning roller 31 is raised and arranged at the height when the above-described first control and second control are performed (step S4).
On the other hand, the head cap 42 is lowered and separated from the head 11 so that the head unit 10 can be transported without interfering with the head cap 42 (step S5).
Next, the head wiping by the first control described above is performed (step S6).
Next, the cleaning liquid suction process by the second control described above is performed (step S7).
Next, the inkjet head 11 is flushed, and if there is any remaining cleaning liquid in the nozzles of the head 11 or the like, this is discharged (step S9).
Through the above control steps, the ink is removed from the ink ejection surface 11a of the inkjet head 11, and the remaining cleaning liquid in the nozzles and the ink ejection surface 11a is also removed.
Next, after moving the head unit 10 onto the head cap 42, the head cap 42 is raised, and the lower end portion of the inkjet head 11 where the ink ejection surface 11 a is disposed is capped with the head cap 42, and image recording is performed. It is made to wait for operation (step S10). The control of the cleaning operation is thus completed.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS. 5, 6A and 6B.
The ink jet image forming apparatus according to the present embodiment has the same configuration as that of the first embodiment, and includes an additional head cleaning device 30 and two head cleaning devices 30J and 30K as shown in FIG. The control device controls the cleaning operation described below. The head cleaning device 30J includes a cleaning roller 31J, a cleaning liquid container 32J, and a squeezing roller 33J. The head cleaning device 30K includes a cleaning roller 31K, a cleaning liquid container 32K, and a squeezing roller 33K.

As the control content of the cleaning operation, the first control (head wiping step S6) and the second control (cleaning liquid suction processing step S7) in the first embodiment are replaced with those shown in FIGS. 6A and 6B. The rest is processed according to the flowchart of FIG. 4 as in the first embodiment.
As shown in FIGS. 6A and 6B, the cleaning roller 31J and the cleaning roller 31K are controlled to rotate reversely at the same speed value R1. In the first control, the cleaning roller 31J is wiped, and in the second control, the cleaning roller 31K is wiped. By moving the head unit 10 in one direction and passing the two cleaning rollers 31J and 31K, the first control and the second control are performed. The moving speed of the head unit 10 in the first control is V1. The moving speed of the head unit 10 in the second control is V2. Speed V1 and speed V2 are in the same direction. The speed R1 of the cleaning roller 31J is opposite to the speed V1. The speed R1 of the cleaning roller 31K is in the same direction with respect to the speed V2.

Similar to the first embodiment, the relative speed Vo in the first control is Vo = V1 + R1. The control device causes the cleaning roller 31J to wipe the ink ejection surface 11a at a speed of (V1 + R1). Under this first control, the head cleaning device 30J wipes the ink ejection surface 11a of the inkjet head 11 by the cleaning roller 31J that has absorbed the cleaning liquid 34. The effects of wiping and the conditions of preferred relative speed are the same as in the first embodiment.
Similar to the first embodiment, the relative speed Vf in the second control is Vf = V2−R1. As in the first embodiment, Vf is set to zero as much as possible, and the head unit 10 is allowed to pass while maintaining the mutual contact position between the ink ejection surface 11a and the cleaning roller 31K as little as possible. The effect of the cleaning liquid suction by the second control and the condition of the preferable relative speed are the same as those in the first embodiment.
According to the present embodiment, the first control and the second control can be performed by moving the head unit 10 in one direction without reciprocating the head unit 10.
Further, according to the present embodiment, the degree of squeezing by the squeezing roller 33J is set appropriately in order to exhibit good ink removability by wiping by the first control, and independently of this, the degree of squeezing by the squeezing roller 33K is set. It is possible to improve the cleaning liquid suction in the second control by appropriately setting.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIGS. 5, 7A and 7B.
The inkjet image forming apparatus according to the present embodiment has the same configuration as that of the first embodiment, and the head cleaning device 30 is added as shown in FIG. 5 to include two head cleaning devices 30J and 30K. This is the same as in the second embodiment. The control device controls the cleaning operation described below.

As the control contents of the cleaning operation, the first control (head wiping step S6) and the second control (cleaning liquid suction processing step S7) in the first embodiment are replaced with those shown in FIGS. 7A and 7B. The rest is processed according to the flowchart of FIG. 4 as in the first embodiment.
As shown in FIGS. 7A and 7B, the cleaning roller 31J and the cleaning roller 31K are controlled to rotate reversely at different speed values R1 and R2. In the first control, the cleaning roller 31J is wiped, and in the second control, the cleaning roller 31K is wiped. By moving the head unit 10 in one direction and passing the two cleaning rollers 31J and 31K, the first control and the second control are performed. The moving speed of the head unit 10 is constant at V1. The speed R1 of the cleaning roller 31J is opposite to the speed V1. The speed R1 of the cleaning roller 31K is in the same direction as the speed V1.

The first control is the same as in the second embodiment.
The relative speed Vf in the second control is Vf = V1−R2. As in the first embodiment, Vf is set to zero as much as possible, and the head unit 10 is allowed to pass while maintaining the mutual contact position between the ink ejection surface 11a and the cleaning roller 31K as little as possible. The effect of the cleaning liquid suction by the second control and the condition of the preferable relative speed are the same as those in the first embodiment.
According to the present embodiment, the first control and the second control can be performed by moving the head unit 10 in one direction without reciprocating the head unit 10.
Further, according to the present embodiment, the degree of squeezing by the squeezing roller 33J is set appropriately in order to exhibit good ink removability by wiping by the first control, and independently of this, the degree of squeezing by the squeezing roller 33K is set. It is possible to improve the cleaning liquid suction in the second control by appropriately setting.
Furthermore, according to the present embodiment, unlike the second embodiment, the head unit 10 is moved in one direction at a constant speed V1, so that the first control and the second control can be performed without changing the moving speed of the head unit 10. Control can be performed and the cleaning operation can be performed stably.

According to the first, second, or third embodiment described above, the following operational effects are obtained.
Even when dry curable ink such as water-based pigment ink is cured and fixed on the ink discharge surface, in the first control, the cleaning roller that has absorbed the cleaning liquid supplies the cleaning liquid to the ink discharge surface to soften and dissolve the fixed ink. Since wiping is performed, ink can be efficiently removed from the ink ejection surface. Therefore, it is preferable to select a cleaning liquid having excellent solubility with respect to the ink to be used. In the case of the second and third embodiments, the cleaning liquid excellent in solubility with respect to such ink is applied to the cleaning device 30J that performs cleaning by the first control, and the other cleaning device 30K is wiped. For the purpose of obtaining flexibility due to water absorption of the member, the same cleaning liquid or a pure cleaning liquid may be applied.
By the action of the squeezing roller, the wiping member whose amount of impregnation of the cleaning liquid is moderately adjusted deviates after a period in which the wiping member is pressed against the ink discharge surface without almost rubbing the ink discharge surface. The cleaning liquid remaining on the surface is absorbed by the wiping member and removed from the ink ejection surface. As a result, the amount of the cleaning liquid remaining on the ink discharge surface after wiping can be suppressed, the ink discharge property of the ink jet head can be maintained well, and an image can be recorded with high accuracy.
In the second control, the relative speed of the cleaning roller applied to the ink ejection surface is low, and the rotation speed of the cleaning roller is also low in accordance with the movement speed of the inkjet head. It is possible to prevent bubbles from adhering to the discharge surface.
Since the ink discharge surface is cleaned through two times of the first control and the second control in which the relative speeds of the ink discharge surface and the outer peripheral surface of the cleaning roller are different, the mechanical action for cleaning is concentrated on one time. Therefore, the meniscus can be satisfactorily held without applying a large pressure to the meniscus formed by the ink in the nozzle.

[Results]
The implementation result which confirms the cleaning effect of this invention is disclosed.
Under the conditions of the relative speeds Vo and Vf described in Table 1, a cleaning operation of the inkjet head 11 in which the ink adhered to the ink ejection surface through a certain recording operation was performed. The wiping member 31a is made of polyvinyl alcohol (PVA), has pores of 300 μm or less for absorbing the cleaning liquid, and the cleaning roller 31 has a diameter of 32 mm. After the cleaning operation, ink droplets are ejected from all the nozzles onto the recording medium to cause the inkjet head to perform a recording operation for forming ink dots corresponding to each nozzle on the recording medium, and there is no lack of ink dots on the recording medium. I confirmed. The results are shown in the right column of Table 1.

 

 

Under the condition of 0 ≦ Vo ≦ 100 (mm / s), the ink removal effect by the first control was insufficient, so the second control was not executed, and as a result, ink dots were missing. It was observed in more than 2% of all nozzles (x).
Under the conditions of 100 (mm / s) ≦ Vo and 75 (mm / s) ≦ Vf, the effect of removing the cleaning liquid remaining on the ink ejection surface was insufficient, so that ink dots were missing in all nozzles. It was recognized in excess of% (×). On the other hand, if the condition is 30 (mm / s) ≦ Vf ≦ 75 (mm / s), the missing ink dots are reduced to 2% or less of all nozzles (◯), and further −30 (mm / s) When ≦ Vf ≦ 30 (mm / s), no missing ink dots were observed (（).

[Additional explanation about the head cleaning device]
Additional description will be given regarding the head cleaning device.
In the head cleaning device 30, the new roller surface constantly carries away dirt on the ink discharge surface as the cleaning roller 31 rotates, so that it is far more than the conventional cleaning blade that always wipes off the same surface of the blade. Increases dirt wiping ability.

In addition, since the ink discharge surface is wiped by the outer peripheral surface that constantly circulates as the cleaning roller 31 rotates, the wiping per wiping area is the same as that of a conventional cleaning blade that is always wiped by the same surface of the blade. There is an advantage that the wear of the member is much less. For this reason, the frequency of replacement | exchange of the wiping member 31a by wear can be reduced significantly.

In addition, by selecting the rotation speed of the cleaning roller 31, optimal cleaning conditions can be easily realized. That is, since not only the traveling speed of the head unit 10 but also the rotational speed of the cleaning roller 31 can be selected, the degree of freedom in adjusting cleaning conditions is increased, and it becomes easy to perform optimum cleaning.

Furthermore, by combining the adjustment of the amount of cleaning liquid squeezed by the squeezing roller 33, the degree of freedom in adjusting the cleaning conditions can be increased by one more, making it easier to perform the optimum cleaning. Further, since the squeezed cleaning liquid 34 is returned to the container 32 and reused, there is an advantage that the usage efficiency of the cleaning liquid 34 is high.

It is preferable to apply the following conditions and configuration as the head cleaning device 30.

The relative speed Vo is 900 mm / s or less. Appropriate cleaning is performed by setting the relative speed Vo to 900 mm / s or less.

The wiping member has an outer diameter of 5 to 50 mm and an inner diameter of 1 to 40 mm. By using a wiping member having an outer diameter of 5 to 50 mm and an inner diameter of 1 to 40 mm, appropriate liquid impregnation and wiping properties are realized.

The wiping member is made of a porous material having open cells. An appropriate liquid impregnation property and wiping property are realized by a wiping member using a porous material having open cells.

The porous material has an average porosity of 70% or more. By using a porous material having an average porosity of 70% or more, an appropriate liquid impregnation property and wiping property are realized.

The porous material has an average pore diameter of 400 μm or less. Appropriate liquid impregnation and wiping properties are realized by using a porous material having an average pore diameter of 400 μm or less.

¡Squeeze out an appropriate amount of cleaning liquid by partially reducing the outer diameter of the wiping member with the impregnation amount adjusting means (squeezing roller). By appropriately reducing the wall thickness of the wiping member by 50% or less, 0.5 mm or more by the impregnation amount adjusting means, an appropriate adjustment of the cleaning liquid impregnation amount is realized.

The head cleaning device 300 shown in FIGS. 8 and 9 can be suitably applied as the head cleaning device 30 in the above embodiment.

A head cleaning device 300 is configured as shown in FIGS. The cleaning liquid supply port 306 is connected to the cleaning liquid tank 40 (FIG. 1) on the one hand, and communicates with the container 305 on the other hand. The cleaning liquid discharge port 308 is connected to the suction pump 41 (FIG. 1) on the one hand and communicates with the outer container 307 on the other hand. As an example, the cleaning liquid overflowing from the container 305 is temporarily stored in the outer container 307 and discharged from the cleaning liquid discharge port 308. The support plate 312 can be moved up and down by a pair of cams 315 and 316. Thereby, the head cleaning apparatus 300 moves up and down as a whole. The cams 315 and 316 are an example of an embodiment of the advance / retreat means of the head cleaning device 300 including the container 305. FIG. 8 shows a state where it is lifted up. In the lowered state, the cleaning roller 301 is separated from the inkjet heads 51 to 54 as shown in FIG. It waits in this state when not cleaning. At this time, the support arm 310 is swung using the engagement between the pin 313 and the elongated hole 314, and the wiping member 303 is released from the squeezing roller 309 as shown in FIG. This is preferable in view of avoiding the deformation of 303.

The cams 315 and 316 are rotated by driving the cleaning roller 301 in one direction by using a driving source common to the cleaning roller 301 and interposing a clutch mechanism. The cams 315 and 316 may be driven by rotation.

The head cleaning device 300 moves away from the inkjet heads 51 to 54 by removing the cleaning roller 301 from the travel path of the head carriage 50 by moving in a direction perpendicular to the paper surface in FIG. May be.

For example, as shown in FIGS. 10A and 10B, the cleaning liquid 304 is supplied to the wiping member 303 of the cleaning roller 301 by providing a flow path 332 in the roller shaft 302 and supplying the cleaning liquid 304 from the inside to the wiping member 303 through the flow path 332. You may make it do. Alternatively, for example, as shown in FIG. 11, the cleaning liquid 304 may be temporarily absorbed by the absorber 333 and transferred to the wiping member 303. Alternatively, for example, as shown in FIG. 12, the cleaning liquid 304 may be supplied from the liquid supply nozzle 334 to the wiping member 303. All of these are preferable in that a cleaning liquid container in which the wiping member 303 is immersed becomes unnecessary.

For example, as shown in FIG. 13, the used cleaning liquid may be discharged through a discharge port 308a provided at the deepest position of the container 305. This is preferable in that the used cleaning liquid 304 is discharged together with the dirt deposited on the bottom of the container 305. The discharge is performed by opening the valve 338 in a timely manner.

In addition, while the ink discharge surfaces of the inkjet heads 51 to 54 are cleaned by the cleaning roller 301, the cleaning liquid impregnated in the wiping member 303 of the cleaning roller 301 is increased by increasing the pressure in the inkjet head (nozzle). It is possible to prevent backflow from the ejection port into the ink head (nozzle), and further to prevent decap. In particular, it is preferable to increase the pressure in the ink jet head (nozzle) during contact between the ink ejection unit and the cleaning roller 301.

For this purpose, for example, while the ink discharge surfaces of the inkjet heads 51 to 54 are cleaned by the cleaning roller 301, control is performed so that ink is discharged from the ink discharge portion, particularly during the contact between the ink discharge surface and the cleaning roller 301. The inkjet head may be controlled by the apparatus.

The cleaning liquid squeezed out from the wiping member 303 by the squeezing roller 309 may be absorbed by the absorber 335 as shown in FIG. The absorber 335 is configured using, for example, a porous material. Alternatively, an absorbent made of a highly water-absorbing polymer may be used. These are preferable from the viewpoint of eliminating the fluidity of the cleaning liquid 304 and disposing it.

The driving force for rotating the cleaning roller 301 may be performed using traveling of the head carriage 50 as shown in FIG. That is, as shown in the figure, a gear 322 is coaxially provided on the roller shaft 302 of the cleaning roller 301, and a rack 501 that engages with the gear 322 is provided on the head carriage 50, and cleaning is performed as the head carriage 50 travels. The roller 301 may be rotated to wipe the ink ejection surface with the wiping member 303. This is preferable in that the number of parts is reduced by sharing a motor or the like as a drive source. Note that another gear is interposed between the rack 501 and the gear 322 to increase the rotation amount of the cleaning roller 301 per movement amount of the head carriage 50, or the rotation direction of the cleaning roller 301 is the travel of the head carriage 50. It is preferable to face the direction in terms of improving the wiping property by the wiping member 303.

〔ink〕
As the ink, it is preferable to apply an aqueous inkjet recording ink containing a pigment and a resin. Details of the resin and pigment contained in the water-based inkjet recording ink will be described below.

(resin)
In the resin for the water-based inkjet recording ink, the total mass of the alkyl methacrylate having 2 to 8 carbon atoms in the alkyl group, methyl methacrylate, and the acid monomer is 80% by mass or more and 100% by mass or less of the total mass of the resin. . If it is 80 mass% or more, the intended abrasion resistance and adhesiveness can be obtained, and at the same time, the gloss is improved. Although it is not certain about this factor, I guess as follows. The methacrylic acid alkyl ester having 2 to 8 carbon atoms in the alkyl group, methyl methacrylate and three-component resin of acid monomer can coexist stably with many aqueous pigment dispersions, and the coating is very uniform. A film can be formed, and gloss reduction is very small. Further, the alkyl methacrylate having 2 to 8 carbon atoms in the alkyl group also has high abrasion resistance and adhesiveness because it also enhances the adhesiveness to the substrate. On the other hand, when a large amount of styrene or styrene which may have a substituent is added, the adhesiveness to the substrate is lowered, and the abrasion resistance and the adhesiveness are extremely lowered. In addition, the acrylic ester component has a bad effect on the formation of a stable coating film with many aqueous pigment dispersions, so that the coating film uniformity is reduced, transparency is impaired, and gloss and optical density are reduced. I think it will cause. Furthermore, when the number of carbon atoms of the alkyl group of the methacrylic acid alkyl ester is 9 or more, the injection stability is deteriorated, which is not preferable.

Further, in the resin relating to the water-based inkjet recording ink, it is preferable that the acid value is 50 mgKOH / g or more and less than 200 mgKOH / g. If the acid value of the resin is 50 mgKOH / g or more, it can be removed by dissolution removal or physical rubbing operation even when drying occurs at the nozzle part of the inkjet head, so that good maintenance suitability is imparted. Can do. Moreover, if the acid value is less than 200 mgKOH / g, good abrasion resistance, adhesiveness and gloss can be obtained.

Also, the resin relating to the water-based inkjet recording ink has a glass transition temperature (Tg) of 20 ° C. or higher and lower than 100 ° C. If Tg is 20 ° C. or higher, sufficient abrasion resistance can be obtained, and occurrence of blocking can be suppressed. Moreover, if Tg is less than 100 degreeC, favorable abrasion resistance can be maintained.

Further, the resin related to the water-based inkjet recording ink has a weight average molecular weight (Mw) of 20000 or more and less than 100,000. If the weight average molecular weight of the resin is 20000 or more, sufficient abrasion resistance can be obtained. Moreover, if the weight average molecular weight is less than 100,000, good injection stability and maintainability can be obtained. From the viewpoint of further improving all of the rub resistance, injection stability and maintainability, the weight average molecular weight is preferably 30000 or more and less than 60000.

Hereinafter, the resin relating to the water-based inkjet recording ink will be described more specifically.

In the resin relating to the water-based inkjet recording ink, as a copolymerization monomer, a monomer composed of an alkyl group having 2 to 8 carbon atoms in an alkyl group, a methyl methacrylate, a methyl methacrylate, and an acid monomer may be used as necessary. Other copolymerizable monomers may be added within a range of less than 20% of the resin component.

In the resin relating to the water-based inkjet recording ink, methyl methacrylate is preferably copolymerized in the range of 20% by mass or more and 50% by mass or less of the total resin mass from the viewpoint of improving the abrasion resistance and adhesiveness. More preferred.

The alkyl methacrylate having 2 to 8 carbon atoms in the alkyl group is at least selected from ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate and 2-ethylhexyl methacrylate. One type is preferable. The alkyl methacrylate having 2 to 8 carbon atoms in the alkyl group can be copolymerized with one or more kinds. Among them, it is preferable to copolymerize at least one of ethyl methacrylate or n-butyl methacrylate from the viewpoint of further improving injection stability.

It is more preferable that the alkyl methacrylate having 2 to 8 carbon atoms in the alkyl group is copolymerized in the range of 25% by mass or more and 70% by mass of the total resin mass from the viewpoint of improving the abrasion resistance and adhesiveness. .

Examples of the acid monomer include acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic acid half ester, etc. Among them, acrylic acid and methacrylic acid have higher injection stability and maintainability. It is preferable at the point which is favorable.

In the resin relating to the water-based inkjet recording ink, a more preferable embodiment is that the total mass of the alkyl methacrylate having 2 to 8 carbon atoms in the alkyl group and methyl methacrylate is 80% or more and less than 90% of the total mass of the resin. Therefore, it is preferable from the viewpoint of forming a film having excellent abrasion resistance and adhesiveness.

Further, in the resin relating to the water-based inkjet recording ink, a monomer obtained by neutralizing all or part of the portion corresponding to the acid monomer with an alkali can be used. As the neutralizing base, alkali metal-containing bases such as sodium hydroxide and potassium hydroxide, and amines (for example, ammonia, alkanolamine, alkylamine and the like) can be used. In particular, neutralization with amines having a boiling point of less than 200 ° C. is preferable from the viewpoint of improving image durability. In particular, an acid monomer neutralized with ammonia has a fast drying property after printing, It is also preferable from the standpoint that printed matter can be stacked immediately after printing and ink mixing can be prevented. In addition, it is preferable in terms of injection stability to use N, N-dimethylaminoethanol, 2-amino-2-methylpropanol, or N-methylaminoethanol as a counter salt.

The resin relating to the water-based inkjet recording ink can be obtained according to a conventionally known polymer synthesis method. Below, an example of the synthesis | combining method of resin which concerns on this invention is shown.

<Synthesis of copolymer resin of n-butyl methacrylate, methyl methacrylate, methacrylic acid (mass ratio 39: 46 :: 15)>
A mechanical stirrer, a nitrogen introducing tube, a condenser, and a dropping funnel are set in a 500 ml four-necked flask, and 185 g of isopropyl alcohol is added to the flask, and heated and refluxed while bubbling nitrogen gas. Next, 46 g of methyl methacrylate, 39 g of n-butyl methacrylate, 15 g of methacrylic acid and 0.5 g of azobisisobutyronitrile (AIBN) as an initiator are mixed and dissolved in the dropping funnel, and it takes about 2 hours. It was dripped in the state heated and refluxed. After the dropwise addition, the mixture is further heated under reflux for 6 hours, and further 0.05 g of AIBN in isopropyl alcohol is added dropwise over 15 minutes. Thereafter, the mixture is further heated to reflux for 5 hours.

After allowing the reaction solution to cool, the solvent isopropyl alcohol is distilled off under reduced pressure. To this residue, 12.4 g of 28% aqueous ammonia and 553 g of ion-exchanged water as alkali neutralized bases were added and dissolved by heating with stirring to prepare an ammonia salt of the resin. The solid content concentration of this resin is about 15% by mass. As a result of measuring the acid value of this resin according to JIS K-0070 acid value measurement and hydrolysis acid value measurement (total acid value measurement), it was 102 mgKOH / g, and the glass transition temperature was measured using DSC. 79 ° C., and the weight average molecular weight measured by GPC was 46000. The details of the method of measuring each characteristic value are shown in the examples described later.

The resin relating to the water-based inkjet recording ink is preferably contained in the range of 1% by mass to 15% by mass of the total mass of the ink, and more preferably 2% by mass to 10% by mass.

Further, it is preferable that the resin relating to the water-based inkjet recording ink is added in an amount of 1 to 4 times the pigment solid content.

(Pigment)
Next, the pigment relating to the water-based inkjet recording ink will be described. In the water-based inkjet recording ink, a pigment is used as a coloring material.

The pigment used in the water-based inkjet recording ink may be any pigment that can be stably dispersed in an aqueous system. A pigment dispersion dispersed with a polymer resin, a capsule pigment coated with a water-insoluble resin, a pigment surface is modified and a dispersion resin is not used. Even a self-dispersible pigment that can be dispersed can be selected. When emphasis is particularly placed on the storage stability of the ink, it is preferable to select a capsule pigment coated with a water-insoluble resin.

When using a pigment dispersion dispersed with a polymer resin, a water-soluble polymer resin can be used, and a styrene-acrylic acid-acrylic acid alkyl ester copolymer is preferably used as the water-soluble resin. Styrene-acrylic acid copolymer, styrene-maleic acid copolymer, styrene-maleic acid-alkyl acrylate copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-alkyl acrylate copolymer And water-soluble resins such as a styrene-maleic acid half ester copolymer, a vinyl naphthalene-acrylic acid copolymer, and a vinyl naphthalene-maleic acid copolymer.

As a method for dispersing the pigment, various dispersing means such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, and a paint shaker can be used.

In the water-based inkjet recording ink, it is also preferable to use a centrifugal separator or a filter for the purpose of removing coarse particles in the pigment dispersion.

The water-insoluble resin using a capsule pigment coated with a water-insoluble resin is a resin that is insoluble in water in a weakly acidic to weakly basic range, and preferably has a solubility in an aqueous solution of pH 4 to 10. % Resin.

Such water-insoluble resins include acrylic, styrene-acrylic, acrylonitrile-acrylic, vinyl acetate, vinyl acetate-acrylic, vinyl acetate-vinyl chloride, polyurethane, silicone-acrylic, acrylic silicon , Polyester-based, and epoxy-based resins. In addition, as the resin according to the present invention, a resin containing a hydrophobic monomer and a hydrophilic monomer can be used.

Examples of hydrophobic monomers include acrylic acid esters (eg, n-butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate), methacrylic acid esters (eg, ethyl methacrylate, butyl methacrylate, glycidyl methacrylate). Etc.), styrene and the like. Examples of the hydrophilic monomer include acrylic acid, methacrylic acid, acrylamide, and the like, and those having an acidic group such as acrylic acid can preferably be those neutralized with a base after polymerization.

As the molecular weight of the water-insoluble resin, those having a weight average molecular weight of 3000 to 500,000 can be used. Preferably, 7,000 to 200,000 can be used.

A water-insoluble resin having a Tg of about −30 ° C. to 100 ° C. can be used. Preferably, a temperature of about −10 ° C. to 80 ° C. can be used.

As the polymerization method, solution polymerization or emulsion polymerization can be used. The polymerization may be synthesized separately from the pigment in advance, or may be performed by supplying a monomer into the system in which the pigment is dispersed.

As a method of coating the pigment with the water-insoluble resin, various known methods can be used. Preferably, in addition to the phase inversion emulsification method and the acid precipitation method, the pigment is dispersed using a polymerizable surfactant. It is preferable to select a method in which a monomer is supplied thereto and coating is performed while polymerizing.

As a more preferred method, the water-insoluble resin is dissolved in an organic solvent such as methyl ethyl ketone, and the acid groups in the resin are partially or completely neutralized with a base, and then dispersed by adding a pigment and ion-exchanged water. Thereafter, a production method in which the organic solvent is removed and water is added as necessary can be mentioned.

The mass ratio of the pigment and the water-insoluble resin can be selected in the range of 100/40 to 100/150 as the pigment / water-insoluble resin ratio. In particular, the image durability, ejection stability, and ink storage stability are in the range of 100/60 to 100/110. The average particle diameter of the pigment particles coated with the water-insoluble resin is preferably about 80 to 150 nm from the viewpoint of ink storage stability and color developability.

Further, as the self-dispersing pigment, commercially available products that have been surface-treated can also be used. Etc.

Conventionally known organic and inorganic pigments can be used as the pigment that can be used in the water-based inkjet recording ink. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc. Examples include cyclic pigments, dye lakes such as basic dye lakes, and acid dye lakes, organic pigments such as nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments, and inorganic pigments such as carbon black.

Specific organic pigments are exemplified below.

As pigments for magenta or red, C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

¡As pigments for orange or yellow, C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 128, C.I. I. And CI Pigment Yellow 138.

¡As pigments for green or cyan, C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

[Cleaning liquid]
Next, details of the cleaning liquid will be described. In carrying out the present invention, it is preferable to apply the following cleaning liquid.

Since the cleaning liquid contains a base component, it is effective for redissolving or redispersing the acid component-containing resin used in the ink.

The cleaning liquid preferably contains at least a solvent having a surface tension of less than 35 mN / m and a basic compound.

As a function required for the cleaning liquid to be applied, it is important that the cleaning performance is stably maintained for a long period of time and the ejection characteristics of the inkjet head after cleaning are not affected.

One requirement is that a preferable cleaning liquid contains a solvent having a surface tension of less than 35 mN / m. As the solvent having a surface tension of less than 35 mN / m, alkylene glycol monoethers or alkanediols are preferable.

Examples of alkylene glycol monoethers that can be suitably used in the cleaning liquid according to the present invention include ethylene glycol monoethyl ether (28.2), ethylene glycol monobutyl ether (27.4), and diethylene glycol monoethyl ether (31. 8), diethylene glycol monobutyl ether (33.6), triethylene glycol monobutyl ether (32.1), propylene glycol monopropyl ether (25.9), dipropylene glycol monomethyl ether (28.8), tripropylene glycol monomethyl ether (30.0). The numerical value in the parenthesis represents the surface tension value (mN / m).

In addition, as the alkanediols that can be suitably used in the cleaning liquid according to the present invention, 1,2-alkanediols are preferable. For example, 1,2-butanediol, 1,2-pentanediol, 1,2- Examples include hexanediol (28.1) and 1,2-heptanediol.

Among the above solvents, diethylene glycol monoalkyl ethers are preferable, and diethylene glycol monobutyl ether is particularly preferable.

The method for measuring the surface tension of a solvent is described in general interface chemistry and colloid chemistry reference books. For example, New Experimental Chemistry Course Vol. 18 (Interface and Colloid), The Chemical Society of Japan, Maruzen Issued by P.C. 68 to 117 can be referred to, and specifically, it can be obtained by using a ring method (Dunoi method) or a vertical plate method (Wilhelmy method). In the present invention, specifically, the surface tension was measured using a surface tension meter CBVP type A-3 (Kyowa Science Co., Ltd.).

The cleaning liquid according to the present invention preferably contains a basic compound together with a solvent having a surface tension of less than 35 mN / m.

The basic compound applicable to the cleaning liquid of the present invention may be an inorganic basic compound or an organic basic compound, but it is more preferable to use an organic basic compound.

As inorganic base compounds, use hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, carbonates such as potassium carbonate and sodium carbonate, potassium hydrogen carbonate and bicarbonates such as sodium hydrogen carbonate. Can do.

As the organic base compound, ammonia, alkanolamines, alkylamines and the like can be used.

Organic base compounds include ammonia, triethylamine, N, N, -dimethylaminoethanol, N, N-dibutylaminoethanol, N-methyl-diethanolamine, 2-amino-2-methylpropanol, diethanolamine, triethanolamine, N- Methylaminoethanol, N, N-diethylaminoethanol and the like can be used.

Of these, ammonia, N, N, -dimethylaminoethanol, N, N-dibutylaminoethanol, N-methyl-diethanolamine, 2-amino-2-methylpropanol, and N, N-diethylaminoethanol can be preferably used.

In the cleaning liquid according to the present invention, other additives such as a surfactant, a moisturizing agent, a culture medium and the like may be added as necessary.

The present invention can be used to form an image with ink.

DESCRIPTION OF SYMBOLS 10 Head unit 11 Inkjet head 11a Ink ejection surface 12 Ink pack 13 Ink subtan 14 Ink cable 15 Ink cable 16 Cable damper 20 Recording medium 30 Head cleaning device 31 Cleaning roller 31a Wiping member 32 Cleaning liquid container 33 Squeezing roller 34 Cleaning liquid 40 Cleaning liquid tank 41 Suction pump 42 Head cap 60 Ink 61 Cleaning liquid 300 Head cleaning device

Claims (6)

In an inkjet recording apparatus that forms an image by ejecting ink droplets from an inkjet head,
A head cleaning device for wiping the ink discharge surface of the inkjet head with a cleaning roller that has absorbed the cleaning liquid;
A control device that controls rotation of the cleaning roller and movement of the inkjet head to control head cleaning work;
The control device controls the head cleaning operation as follows:
The ink jet head is moved to bring the ink discharge surface into contact with the outer peripheral surface of the cleaning roller, and a relative speed between the ink discharge surface in contact with the outer peripheral surface in contact with the ink discharge surface is controlled to a predetermined value or more. 1 control,
After the first control, the relative speed between the ink discharge surface and the outer peripheral surface in contact with the ink discharge surface and the outer peripheral surface is controlled to zero or a value lower than the predetermined value. An ink jet recording apparatus that executes a second control for separating the ink discharge surface and the outer peripheral surface. 2. The ink jet recording apparatus according to claim 1, wherein in the first control, the control device controls a moving direction of the ink jet head and a moving direction of the outer peripheral surface at a contact portion with the ink discharge surface in opposite directions. . 3. The ink jet recording apparatus according to claim 1, wherein the control device controls the predetermined value as 100 mm / s in the first control. 4. The ink jet recording apparatus according to claim 1, wherein the control device controls the relative speed in the second control to be −30 mm / s or more and 30 mm / s or less. The head cleaning device includes:
A cleaning liquid container for supplying the cleaning liquid to the wiping member by immersing the wiping member constituting the outer peripheral surface of the cleaning roller in the cleaning liquid;
The impregnation amount adjusting means for adjusting the amount of the cleaning liquid impregnated in the wiping member by squeezing a part of the cleaning liquid impregnated in the wiping member from the wiping member. An ink jet recording apparatus according to claim 1. 6. The control device according to claim 1, wherein the control device executes control for discharging ink from the nozzles of the inkjet head before the first control as control of the head cleaning operation. 7. The ink jet recording apparatus described.

Images