JP6493663B2 - INK JET DEVICE CLEANING METHOD AND INK JET DEVICE - Google Patents

Description

  The present invention relates to a method for cleaning an inkjet device, and an inkjet device that executes the method.

  Opportunities for printing with radiation curable inkjet compositions that cure with light irradiation used in sign applications are increasing. When an image or a character is recorded with a droplet of a minute inkjet composition (hereinafter also simply referred to as “ink”) ejected from a nozzle of an inkjet head, the ink adheres to the nozzle surface on which the nozzle is provided. The ink adhering to the nozzle surface may thicken or solidify due to evaporation of moisture and other volatile components contained therein. For this reason, when ink adheres to the nozzle surface, normal ink ejection may be hindered. The radiation curable inkjet composition has a higher viscosity than conventional inks, and the ink attached to the nozzle surface is cured and thickened due to the influence of reflected light, leakage light, etc. Simply wiping with a rubber wiper cannot remove the ink sufficiently.

  Therefore, for example, it has been proposed that an ink absorber such as a cloth wiper is impregnated with a solvent and brought into contact with the nozzle surface to wipe off ink adhering to the nozzle surface. For example, Patent Document 1 discloses the use of glycol ethers, particularly diethylene glycol dibutyl ether or triethylene glycol monomethyl ether, as a solvent to be impregnated into a cloth wiper.

JP 2009-274258 A

  However, when the ink described in Patent Document 1 is used to wipe the ink absorber in contact with the nozzle surface, the ink surface, particularly the aggregate derived from the inorganic pigment, is rubbed during wiping, and the nozzle surface is damaged. A sufficient wiping property cannot be obtained.

  Some embodiments according to the present invention solve at least a part of the above-described problems, thereby suppressing aggregation of the radiation-curable inkjet composition and performing a cleaning method for an inkjet apparatus excellent in cleaning properties, and the same. It is to provide an inkjet apparatus.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
One aspect of a method for cleaning an inkjet device according to the present invention is as follows.
In an inkjet apparatus for discharging a radiation curable inkjet composition,
It is characterized by comprising a wiping step of wiping the nozzle surface of the inkjet head with a wiping means comprising an absorbent body impregnated with an organic solvent containing at least one of an ether derivative of glycol and an ester derivative of glycol and a polymerization inhibitor. .

  According to the cleaning method of the ink jet apparatus of Application Example 1, wiping is performed by a wiping means including an absorbent body impregnated with an impregnating liquid containing an organic solvent and a polymerization inhibitor that is at least one of an ether derivative of glycol and an ester derivative of glycol By doing so, aggregation of the radiation curable inkjet composition can be suppressed, and a cleaning method for an inkjet apparatus excellent in cleaning properties can be provided.

[Application Example 2]
In the cleaning method of application example 1,
The polymerization inhibitor may be at least one selected from the group consisting of catechols, hindered amines, phenols, phenothiazines, and condensed aromatic ring quinones.

[Application Example 3]
In the cleaning method of Application Example 1 or Application Example 2,
Content of the said polymerization inhibitor with respect to the said impregnation liquid can be 0.1 mass% or more and 1 mass% or less.

[Application Example 4]
In the cleaning method of any one of Application Examples 1 to 3,
The ether derivative of glycol and the ester derivative of glycol may have 8 or more carbon atoms.

[Application Example 5]
In the cleaning method of any one of application examples 1 to 4,
The absorber can be further impregnated with a surfactant.

[Application Example 6]
In Application Example 5,
The surfactant may be at least one selected from the group consisting of polyether-modified silicones, polyester-modified silicones, and acetylenic diols.

[Application Example 7]
In the cleaning method of any one of Application Examples 1 to 6,
The radiation curable ink jet composition may contain an inorganic pigment.

[Application Example 8]
In the cleaning method of any one of Application Examples 1 to 7,
After the wiping step, a preliminary discharge step of preliminary discharging the radiation curable inkjet composition from the nozzle,
The preliminary ejection step may include a nozzle that performs the preliminary ejection and a nozzle that does not perform the preliminary ejection.

[Application Example 9]
In application example 8,
In the first recording performed after the preliminary ejection step, the nozzle that does not perform the preliminary ejection in at least the first scan that ejects the radiation curable inkjet composition while changing the relative position of the recording medium and the inkjet head. It can be a nozzle that is not used.

[Application Example 10]
One aspect of the inkjet apparatus according to the present invention is as follows.
Cleaning is performed by the cleaning method according to any one of Application Examples 1 to 9.

1 is a diagram schematically illustrating an inkjet apparatus according to an embodiment of the present invention. Schematic which shows typically the nozzle surface of the inkjet apparatus which concerns on one Embodiment of this invention. 1 is a perspective view schematically showing a wiper unit of an ink jet apparatus according to an embodiment of the present invention. 1 is a front view schematically showing a wiper cassette of an ink jet apparatus according to an embodiment of the present invention.

  Several embodiments of the present invention will be described below. Embodiment described below demonstrates an example of this invention. The present invention is not limited to the following embodiments, and includes various modified embodiments that are implemented within a range that does not change the gist of the present invention. Note that not all of the configurations described below are essential configurations of the present invention.

1. Cleaning Method A cleaning method for an inkjet device according to an embodiment of the present invention is a method for cleaning a nozzle surface of an inkjet head using at least one of an ether derivative of glycol and an ester derivative of glycol in an inkjet device that discharges a radiation curable inkjet composition. A wiping step of wiping with a wiping means including an absorbent body impregnated with an organic solvent and a polymerization inhibitor.

  Hereinafter, the cleaning method of the ink jet apparatus according to the present embodiment will be described in detail after describing the structure of the apparatus capable of carrying out the method, the impregnating liquid, and the radiation curable ink jet composition in this order.

1.1. Apparatus Configuration An inkjet apparatus in which the cleaning method according to the present embodiment is implemented includes a nozzle surface provided with a nozzle for discharging a radiation curable inkjet composition, and a wiping means including an absorber impregnated with an impregnating liquid. Prepare. As such an ink jet apparatus, for example, an ink jet printer shown in FIG. An ink jet printer 1 shown in FIG. 1 is a known ink jet printer in which a head cleaning device 26 is incorporated.

The ink jet printer 1 includes a carriage 20 equipped with an ink jet head 22 that ejects a radiation curable ink jet composition from a nozzle into droplets having a minute particle diameter and ejects the liquid onto a recording medium P. A pair of actinic radiations for irradiating actinic radiation to the droplets of the radiation curable ink jet composition deposited on the recording medium P by being ejected from the ink jet head 22 on both side ends along the moving direction of the carriage 20. Irradiation devices 23A and 23B are provided. As shown in FIG. 1, the actinic radiation irradiating device 23A attached to the left side of the ink-jet head 22 applies to the droplets ejected on the recording medium P during the right scanning when the carriage 20 moves in the right direction. Actinic radiation is applied. On the other hand, the actinic radiation irradiating device 23B attached to the right side of the ink jet head 22 irradiates the droplets ejected on the recording medium P during the left scanning in which the carriage 20 moves leftward. . The actinic radiation irradiation devices 23A and 23B are provided with actinic radiation light sources (not shown),
As the active radiation light source, for example, an LED (Light Emitting Diode) or an LD (Laser Diode) is used.

1.1.1. Nozzle surface The inkjet head 22 is a serial head for full-color printing that ejects a plurality of colors of ink, and includes a large number of nozzles for each color. FIG. 2 is a schematic view schematically showing the nozzle surface. As shown in FIG. 2, a nozzle surface 37 is formed on the surface of the inkjet head 22 that faces the recording medium P. The nozzle surface 37 is provided with a plurality of nozzles (nozzle openings) 38 for discharging the radiation curable inkjet composition. A plurality of nozzles 38 are arranged in a predetermined direction to constitute a nozzle row 36. As shown in FIG. 2, a plurality of nozzle rows 36 are provided on the nozzle surface 37.

  A liquid repellent film (not shown) is provided on the nozzle surface 37. The liquid repellent film is not particularly limited as long as it has liquid repellency. For example, a metal alkoxide molecular film having liquid repellency is formed, followed by drying treatment, annealing treatment, and the like. can do. Any metal alkoxide molecular film may be used as long as it has liquid repellency, but a metal alkoxide monomolecular film having a long-chain polymer group containing fluorine (long-chain RF group), or a liquid-repellent group ( For example, a monomolecular film of a metal acid salt having a long-chain polymer group containing fluorine) is desirable. Although it does not specifically limit as a metal alkoxide, For example, silicon, titanium, aluminum, and zirconium are generally used as the metal seed | species. Examples of the long chain RF group include a perfluoroalkyl chain and a perfluoropolyether chain. Examples of the alkoxysilane having a long chain RF group include a silane coupling agent having a long chain RF group. The liquid repellent film is not particularly limited, and for example, a SCA (silane coupling agent) film or a film described in Japanese Patent No. 4249495 can be used. A film having water repellency is called a water repellent film.

  The liquid repellent film may be formed by forming a conductive film on a substrate (nozzle plate) on which a nozzle is formed, and forming the conductive film on the conductive film. (Plasma Polymerization Silicone film) may be formed and formed on this base film. Through this base film, the silicone material and the liquid repellent film of the nozzle plate can be blended.

  The liquid repellent film preferably has a thickness of 1 nm to 30 nm, more preferably has a thickness of 1 nm to 20 nm, and still more preferably has a thickness of 1 nm to 15 nm. By being in the above range, the nozzle surface tends to be more excellent in liquid repellency, film deterioration is relatively slow, and liquid repellency can be maintained for a longer period. Moreover, it is excellent in terms of cost and ease of film formation.

The nozzle surface 37 may be provided with a nozzle plate cover that covers at least a part of the nozzle surface 37. In the example of FIG. 2, the nozzle plate cover 35 is provided so as to surround all the nozzle rows 36 (nozzles 38). The nozzle plate cover 35 serves to fix the chip on the nozzle surface 37 of the ink jet head 22 formed by a combination of a plurality of nozzle chips (hereinafter simply referred to as “chips”), or the recording medium is lifted to raise the nozzles 38. It is provided to fulfill at least one of the roles of preventing the recording medium from coming into direct contact. The nozzle plate cover 35 is provided so as to protrude from the nozzle when viewed from the side surface by covering at least a part of the nozzle surface 37. When the nozzle plate cover 35 is provided, the radiation curable inkjet composition tends to remain in the corner (gap) between the nozzle surface 37 and the nozzle plate cover 35 protruding from the nozzle surface 37, and the remaining radiation curing. Due to the solidification of the pigment or the like of the type ink jet composition, there may be a problem that the capping operation becomes poor due to insufficient adhesion between the cap and the nozzle surface. The problem becomes particularly noticeable depending on the type of resin contained in the radiation curable inkjet composition. Therefore, when a wiping means described later is brought into contact between the nozzle plate cover 35 and the nozzle 38, the radiation curable inkjet composition deposited in the gap can be removed, and the capping operation is stabilized. It will be good.

  The nozzle surface 37 is wiped while the impregnating liquid adheres to the nozzle 38 when performing the wiping process described later. Specifically, when carrying out the wiping step, the impregnating liquid is impregnated in the absorbent body of the wiping means in advance, and the nozzle surface 37 is wiped by the absorbent body of the wiping means holding the impregnating liquid.

1.1.2. As shown in FIG. 1, a head cleaning device 26 for cleaning the inkjet head 22 is provided at the home position HP provided on the right side of the recording area in which the recording medium P is transported in the frame 12. ing. FIG. 3 is a perspective view schematically showing a wiper unit 34 which is an example of the head cleaning device 26. 4A is a front view of the wiper unit 34, and FIG. 4B is a front view of the wiper unit 34 with the housing omitted.

  The wiper unit 34 includes a wiper cassette 31 on which the wiping means 30 is mounted, a wiper holder 32 to which the wiper cassette 31 is detachably mounted, and the wiper holder 32 in the nozzle row direction of the inkjet head 22 (in FIG. 1, recording). A moving mechanism 33 that moves the medium P in the conveyance direction) is provided. In addition to the wiper unit 34 shown in FIG. 3, the head cleaning device 26 includes a cap (not shown) that can be brought into contact with the nozzle surface 37 of the inkjet head 22 so as to surround the nozzle 38, and the cap. There may be provided a suction pump (not shown) that is driven to suck and discharge the ink having increased viscosity from the inside of the inkjet head 22 as waste ink.

  As shown in FIG. 4, a pair of axes having an axis extending horizontally in the front-rear direction, which is the short direction of the casing 80, is provided inside the casing 80 having a substantially rectangular box shape that forms the exterior of the wiper cassette 31. The rollers 81 and 82 are accommodated at a distance in the left-right direction, which is the longitudinal direction of the housing 80. A long wiping means 30 for wiping ink from the nozzle surface 37 of the inkjet head 22 is hung between the pair of rollers 81 and 82. Of the pair of rollers 81 and 82, the feeding roller 81 provided on the left side closer to the recording area where the ink jet head 22 performs recording on the recording medium P is used for wrapping unused wiping. The means 30 is paid out. On the other hand, of the pair of rollers 81, 82, the winding roller 82 on the right side that is opposite to the recording area where the inkjet head 22 performs recording on the recording medium P is unwound from the feeding roller 81. The used wiping means 30 used for wiping is wound up. The feeding roller 81 and the take-up roller 82 are located at substantially the same height. A feeding gear is provided at one end portion (front end portion) in the axial direction of the feeding roller 81 exposed to the outside of the housing 80 so as to be integrally rotatable with the feeding roller 81. In addition, winding gears 84 and 85 are provided at both ends in the axial direction of the winding roller 82 exposed to the outside of the casing 80 so as to be rotatable together with the winding roller 82.

In addition, on the inside of the housing 80, a plurality of (four in this embodiment) rollers 86, 88, 89 and a pressing member 87 are provided on the feeding path of the wiping means 30 from the feeding roller 81 to the take-up roller 82. Is provided. These rollers 86, 88, 89 and the pressing member 87 extend in the front-rear direction in parallel with the feeding roller 81 and the take-up roller 82, and the bearing portions in which both ends in the front-rear direction are provided on the side wall portion of the housing 80. Is supported rotatably.

  Specifically, a portion of the wiping means 30 that is fed from the feeding roller 81 is wound around the pressing member 87 that is provided obliquely above and to the right of the feeding roller 81. The shaft portions 87 a at both ends in the axial direction of the pressing member 87 are supported from below by bar springs 90 fixed to the outer surfaces on both front and rear sides of the housing 80. The bar spring 90 supports the shaft portion 87a of the pressing member 87 from below at an intermediate position in the longitudinal direction. Note that the shaft portion 87 a of the pressing member 87 is inserted back and forth with respect to the bearing hole 91 provided in the housing 80, and is a hole on the upper side of the bearing hole 91 according to the upward biasing force acting from the bar spring 90. It is in close contact with the edge. The shaft portion 87a of the pressing member 87 is supported between the bar spring 90 and the hole edge of the bearing hole 91 so as to be rotatable from both upper and lower sides. The uppermost portion of the circumferential surface of the pressing member 87 is located above the upper surface of the housing 80, and the portion of the wiping means 30 that is wound around the pressing member 87 protrudes upward from the upper surface of the housing 80. Yes. Further, the uppermost portion of the circumferential surface of the pressing member 87 is located above the nozzle surface 37 of the inkjet head 22.

  The drive mechanism including at least the bar spring 90 and the pressing member 87 can apply the pressing load by pressing the wiping means 30 containing the impregnating liquid against the nozzle surface 37 by the upward biasing force of the bar spring 90. . In the present embodiment, the pressing load refers to a spring load. As long as the mechanism for applying the pressing load can press the wiping means 30 against the nozzle surface 37 with a certain load, not only a spring but also rubber may be used, The load may be applied by a method such as applying a load by controlling the mechanical member.

  Further, a relay roller 89 is provided below the pressing member 87 so as to wind a portion of the wiping unit 30 that is fed from the pressing member 87. A sandwiching roller 92 that sandwiches the wiping unit 30 with the relay roller 89 is provided at a position on the opposite side of the wiping unit 30 with respect to the relay roller 89. A spring member 93 as an urging member is interposed between the inner surface of the bottom wall of the housing 80 and the sandwiching roller 92. The clamping roller 92 is urged in a direction approaching the relay roller 89 by the spring member 93.

  The relay gear 94 can rotate integrally with the relay roller 89 at the end portion of the shaft portion 89a on the one side (rear side in FIG. 4) in the axial direction exposed to the outside from the side wall portion of the housing 80 in the relay roller 89. Is provided. Further, the shaft portions 92 a at both ends in the axial direction of the sandwiching roller 92 are exposed at the outer ends from the notch groove-shaped bearing portions formed when the elastic piece portions are cut out and formed on the side wall portions of the housing 80. Yes.

  Further, on the feeding path of the wiping unit 30 from the feeding roller 81 to the take-up roller 82, the wiping unit 30 is provided between the feeding roller 81 and the pressing member 87 and between the pressing member 87 and the relay roller 89. There are provided tension rollers 86 and 88 for applying tension. It should be noted that end portions of the shaft portions 86 a and 88 a at both ends in the axial direction of the tension rollers 86 and 88 are exposed to the outside from the circular concave bearing portion provided on the side wall portion of the housing 80.

The wiping means 30 provides an absorber (not shown) on the surface facing the nozzle surface 37. The absorbent body wipes the nozzle surface 37 while retaining the impregnating liquid, and adheres to the nozzle 38 and the nozzle surface 37 (for example, a radiation curable inkjet composition, a cured product of the radiation curable inkjet composition, The nozzle 38 and the nozzle surface 37 are used for cleaning (cleaning) by absorbing or adsorbing fibers, paper, dust, and the like. Thereby, since the pigment particle | grains and hardened | cured material contained in a radiation curable inkjet composition are absorbed inside an absorber, a pigment particle and hardened | cured material do not remain on the absorber surface of the wiping means 30. FIG. For this reason, it is possible to prevent the water-repellent film formed on the nozzle surface 37 from being damaged by the pigment particles or the cured product.

  The absorbent body of the wiping means 30 is not particularly limited as long as it is liquid absorptive, and examples thereof include cloth (woven fabric, knitted fabric, nonwoven fabric, etc.), sponge, pulp and the like. Among these, a fabric is preferable. This is because it is easy to bend if it is a fabric, and particularly when the nozzle plate cover 35 is provided, it is easier to wipe off ink adhering to the nozzle surface 37. Although it does not specifically limit as a material which comprises a fabric, For example, what consists of a cupra, polyester, polyethylene, a polypropylene, a lyocell, rayon etc. can be mentioned. At this time, it is preferable to select a material that is not easily deteriorated by the impregnating liquid.

  The thickness of the absorber can be appropriately set as desired, and can be, for example, 0.1 mm or more and 3 mm or less. When the thickness is 0.1 mm or more, it becomes easier to hold the impregnating liquid. When the thickness is 3 mm or less, it becomes a compact wiping means, the entire wiper unit can be miniaturized, and mechanical transport of the wiping means becomes easier.

The areal density of the absorber, 0.005 g / cm ² or more 0.15 g / cm ² or less. More preferably, the 0.02 g / cm ² or more 0.13 g / cm ² or less. By being the said range, it becomes easier to hold | maintain an impregnation liquid. Furthermore, in order to retain the impregnating liquid, it is preferable to use a fabric that can easily design the surface density and thickness of the absorber.

  It is preferable that the absorbent body retains the impregnation liquid at the time of shipment. As a result, the nozzle surface 37 can be wiped immediately, and there is no need to provide a mechanism for spraying or applying the impregnating liquid to the nozzle surface 37. Here, “holding the impregnating liquid at the time of shipment” means that the state in which the absorbent body of the wiping means already holds the impregnating liquid or the wiping means when the ink jet apparatus provided with the wiping means is installed. It means that the absorber of the wiping means already holds the impregnating liquid when installed in the ink jet apparatus, or that the absorber of the wiping means for replacement holds the impregnating liquid. Here, “installation of the ink jet device” means that the ink jet device is prepared for the first use, and “installation of the wiping means” means that the wiping means is prepared for the first use. In the present embodiment, the wiping of the nozzle surface 37 performed using the wiping unit 30 may be performed as long as at least the nozzle surface 37 is wiped by the wiping unit 30, and at least a part of the adhered matter attached to the nozzle surface 37 by wiping is used. It is preferable to pay. Note that the amount of the impregnating liquid retained by the absorber is preferably an amount that does not damage the water-repellent film formed on the nozzle surface 37 and does not deteriorate the handling property.

1.1.3. Drive Mechanism The ink jet apparatus according to the present embodiment has a drive mechanism. The drive mechanism moves at least one of the wiping means 30 and the inkjet head 22 relative to the other, and executes a wiping process for removing the deposits attached to the nozzle surface 37 by the wiping means 30. It is. The drive mechanism used in the present embodiment is a mechanism for pressing the wiping means 30 containing the impregnating liquid and the nozzle surface 37. As described above, at least the pressing member 87 in FIG. , And a moving mechanism 33 may be included.

  It is preferable that the pressing member 87 relatively presses the wiping means 30 and the nozzle surface 37 at 50 gf or more and 700 gf or less, preferably 75 gf or more and 500 gf or less. When the pressing force is 50 gf or more, the cleaning property is improved. Further, even when there is a step between the nozzle plate and the nozzle plate cover 35, it is excellent in preventing or removing ink from adhering and accumulating in the gap. Further, when the pressing force is 700 gf or less, the liquid repellent film formed on the nozzle surface 37 can be wiped without being damaged, and the storage stability of the liquid repellent film is further improved.

  As described above, the driving mechanism is not limited to the mechanism that presses the wiping unit 30 from the side opposite to the side that contacts the nozzle surface 37 to bring the wiping unit 30 and the nozzle surface 37 into contact with each other. The wiping means 30 and the nozzle surface 37 may be brought into contact with each other by driving. The load referred to here is the sum of the loads applied to the nozzle surface 37 from the entire drive mechanism.

  Further, it is preferable that the drive mechanism relatively moves the wiping means 30 and the inkjet head 22 at a speed of 1 cm / s or more and 10 cm / s or less. By being in the above range, the cleaning property and the storage stability of the liquid repellent film are further improved. The speed of the cleaning operation is a slow speed of about 1/5 to 1/20 as compared with the speed at which the normal recording head moves when recording an image, but is limited to this speed relationship. I don't mean.

  Although the pressing member 87 is not specifically limited, For example, what was covered with the elastic member is preferable. The Shore A hardness of the elastic member is preferably 10 or more and 60 or less, and more preferably 10 or more and 50 or less. Thereby, a pressing member and the wiping means 30 bend at the time of a press, and it can push a wiping means into the back with respect to the uneven surface which consists of a nozzle surface. In particular, when there is a nozzle plate cover 35, the wiping means can be pushed deeply into the corner (gap) between the nozzle surface 37 and the nozzle plate cover 35 protruding therefrom, thereby suppressing ink accumulation. it can. As a result, the cleaning property is further improved.

1.2. Impregnation liquid In the method for cleaning an ink jet apparatus according to this embodiment, an impregnation liquid containing an organic solvent that is at least one of an ether derivative of glycol and an ester derivative of glycol and a polymerization inhibitor is used. The impregnating liquid adheres to the nozzle surface 37 by being held by the absorbent body of the wiping means 30 when performing the wiping step. Hereinafter, components contained in the impregnation liquid and components that may be contained will be described.

<Organic solvent>
The impregnation liquid contains an organic solvent (hereinafter also referred to as “specific organic solvent”) that is at least one of an ether derivative of glycol and an ester derivative of glycol. These specific organic solvents may be used alone or in combination of two or more.

  The specific organic solvent is excellent in the action of dissolving (softening) the radiation curable inkjet composition attached to the nozzle surface 37. For this reason, by using the impregnating liquid containing a specific organic solvent, aggregation of the radiation curable inkjet composition adhering to the nozzle surface 37 can be suppressed, and the cleaning performance of the nozzle surface 37 is improved. Further, since the nozzle surface 37 can be gently wiped, cleaning can be performed without damaging the water-repellent film, particularly when ink containing an inorganic pigment is used.

  In the specific organic solvent, it is preferable that the ether derivative of glycol and the ester derivative of glycol have 8 or more carbon atoms. Since the radiation curable inkjet composition is a hydrophobic ink, by making the impregnating liquid in contact with the hydrophobic ink, aggregation of the radiation curable inkjet composition is suppressed and the cleaning property is further improved. Further, since the carbon number is 8 or more, the volatility of the impregnating liquid can be reduced, the occurrence of clogging of the nozzle accompanying the drying of the impregnating liquid can be reduced, and the ejection stability of the radiation curable ink jet composition is improved. .

Specific examples of the glycol ether derivatives and glycol ester derivatives having 8 or more carbon atoms include ethyl diglycol acetate, butyl diglycol acetate, diethylene glycol diethyl ether, and triethylene glycol monobutyl ether. These organic solvents can be used individually by 1 type or in mixture of 2 or more types.

  As the specific organic solvent, those having a normal boiling point of 170 ° C. or higher are preferably used, and those having a standard boiling point of 250 ° C. or higher are more preferably used. Thereby, generation | occurrence | production of the clogging of the nozzle accompanying drying of an impregnating liquid can be reduced, and the discharge stability of a radiation curable inkjet composition becomes favorable.

  As the specific organic solvent, one having a vapor pressure of 1 hPa or less at 20 ° C. is preferably used, more preferably 0.5 hPa or less, and more preferably 0.1 hPa or less. Is more preferable, and it is particularly preferable to use a material having a pressure of 0.01 hPa or less. Thereby, generation | occurrence | production of the clogging of the nozzle accompanying drying of an impregnating liquid can be reduced, and the discharge stability of a radiation curable inkjet composition becomes favorable.

  Moreover, as said specific organic solvent, it is preferable to use the thing whose surface tension in 20 degreeC is 25 mN / m or more and 35 mN / m or less. Thereby, since compatibility with the radiation curable inkjet composition described later is improved, the cleaning property tends to be further improved. The surface tension is measured by using an automatic surface tension meter CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.) by confirming the surface tension when the platinum plate is wetted with an organic solvent in an environment of 20 ° C. can do.

  The lower limit of the specific organic solvent content is preferably 30% by mass or more and more preferably 50% by mass or more with respect to the total mass (100% by mass) of the impregnating liquid. When the content of the specific organic solvent is 50% by mass or more, the cleaning performance of the nozzle surface 37 is further improved. The upper limit of the content of the specific organic solvent with respect to the impregnating liquid is not limited and may be 100% by mass.

  When performing the wiping step described later using the wiping means 30 including the absorbent body impregnated with the impregnating liquid, the impregnating liquid held in the absorbent body is based on 100 parts by mass of the absorbent body. It is preferable that a specific organic solvent of 10 parts by mass or more is contained, more preferably 15 parts by mass or more, still more preferably 20 parts by mass or more, and further preferably 40 parts by mass or more. It is preferably 50 parts by mass or more. The upper limit is preferably 150 parts by mass or less, and more preferably 100 parts by mass or less. When the amount is 10 parts by mass or more, the ink solidified on the nozzle surface 37 is easily dissolved (softened), so that the cleaning property is further improved. When the amount is 150 parts by mass or less, the ink is easily absorbed by the absorber, so that abnormal ejection or non-ejection of the nozzles 38 due to unwiping of ink hardly occurs, and ink ejection stability is improved.

<Polymerization inhibitor>
The impregnation liquid according to this embodiment contains a polymerization inhibitor in addition to the specific organic solvent. Since the impregnating solution contains a polymerization inhibitor, the radiation curable inkjet composition adhering to the nozzle surface 37 is reduced from being cured by leakage light, heat, or the like, and the components contained in the radiation curable inkjet composition are aggregated. This prevents the nozzle surface 37 from being cleaned.

  The polymerization inhibitor contained in the impregnating liquid is preferably at least one selected from the group consisting of catechols, hindered amines, phenols, phenothiazines, and condensed aromatic ring quinones. Thereby, the effect | action which reduces that the radiation-curable inkjet composition adhering to the nozzle surface 37 hardens | cures by leak light improves, and cleaning property becomes still better.

Among the above polymerization inhibitors, a photopolymerization inhibitor is preferable because it is excellent in the action of reducing the radiation curable inkjet composition attached to the nozzle surface 37 from being cured by leakage light. In such a condition, the usable polymerization inhibitor is not limited to the photopolymerization inhibitor. Specific examples of the polymerization inhibitor include hydroquinone monomethyl ether and 4-hydroxy 2,2,6,6-tetramethylpiperidine-N-oxyl. A polymerization inhibitor can be used individually by 1 type or in mixture of 2 or more types.

  The content of the polymerization inhibitor with respect to the impregnating liquid is preferably 0.1% by mass or more and 1% by mass or less, and 0.3% by mass or more and 0.8% by mass with respect to the total mass (100% by mass) of the impregnating liquid. % Or less is more preferable. When the content of the polymerization inhibitor with respect to the impregnating liquid is in the above range, the action of the radiation curable inkjet composition adhering to the nozzle surface 37 is cured by leakage light is improved, and the cleaning property is further improved. If the content of the polymerization inhibitor with respect to the impregnating liquid is more than the above range, the ink may not be hardened when printed, or the print may become thin.

<Surfactant>
The impregnating liquid according to this embodiment may further contain a surfactant in addition to the specific organic solvent and the polymerization inhibitor. When the impregnating liquid contains the surfactant, the surface tension of the impregnating liquid is reduced and the wettability with respect to the nozzle surface 37 is increased. Therefore, not only the action of dissolving (softening) the radiation curable ink jet composition attached to the nozzle surface 37 but also the re-adhesion of the ink pigment to the nozzle surface 37 can be suppressed, and the cleaning property of the nozzle surface 37 can be reduced. Will be further improved.

  The surfactant is preferably at least one selected from the group consisting of polyether-modified silicones, polyester-modified silicones, and acetylenic diols. Thereby, the cleaning property is further improved. Specific examples of the surfactant include, for example, silicone surfactants (commercially available products such as BYK UV3700 (trade name manufactured by Big Chemie Japan)), acetylene surfactants (commercially available products include, for example, , Surfinol E1010 (trade name, manufactured by Nissin Chemical Industry Co., Ltd.)). Surfactant can be used individually by 1 type or in mixture of 2 or more types.

  The content of the surfactant with respect to the impregnating liquid is preferably 0.3% by mass or more and 0.8% by mass or less with respect to the total mass (100% by mass) of the impregnating liquid.

  The surfactant may be contained in the impregnation liquid as described above, or may be impregnated in advance in the absorbent body of the wiping means 30. Moreover, when performing a wiping process, you may supply and adhere to the nozzle surface 37 using a well-known spraying apparatus etc.

<Other ingredients>
The impregnation liquid according to the present embodiment may contain an organic solvent other than the specific organic solvent. Examples of such an organic solvent include the organic solvents exemplified in the radiation curable ink jet composition described later, and a description thereof will be omitted.

  The impregnation liquid according to the present embodiment can further contain substances for imparting predetermined performance such as a pH adjuster, a chelating agent, an antiseptic / antifungal agent, and a rust inhibitor.

The impregnating liquid according to the present embodiment uses an impregnating liquid containing an organic solvent that is at least one of an ether derivative of glycol and an ester derivative of glycol, and a polymerization inhibitor, thereby aggregating the radiation curable inkjet composition. Suppressing, and preventing ink agglomerates, especially agglomerates derived from inorganic pigments, from rubbing during wiping, damages the liquid-repellent film on the nozzle surface and deteriorates durability. Moreover, hardening of the radiation-curable inkjet composition adhering to the nozzle surface by the polymerization inhibitor is suppressed. For this reason, it is possible to realize a method for cleaning an ink jet apparatus having excellent cleaning properties.

1.3. Radiation curable inkjet composition An inkjet apparatus to which the cleaning method according to the present embodiment is applied records an image on a recording medium P using the radiation curable inkjet composition.

  In the present invention, the “radiation curable ink jet composition” is used for an ink jet recording method having a curing step of obtaining a cured film by irradiating the radiation curable ink jet composition attached to a recording medium with active radiation. A known ink composition can be used.

  The radiation curable inkjet composition used in one embodiment of the present invention contains a pigment, a monomer that forms an ink film, a polymerization initiator, and an organic solvent. Hereinafter, components included in the radiation curable inkjet composition and components that may be included will be described in detail.

<Pigment>
In the inkjet composition, a pigment can be used as a coloring material, and any of an inorganic pigment and an organic pigment can be used as the pigment.

  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.

  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, quinophthalone pigments, etc. Polycyclic pigments, dye chelates (eg basic dye chelates, acid dye chelates, etc.), dye rakes (basic dye rakes, acid dye rakes), nitro pigments, nitroso pigments, aniline black, daylight A fluorescent pigment is mentioned.

The carbon black used as the black color material is not particularly limited. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. 2200B, etc. (Mitsubishi Chemical Corporation), Raven
5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Raven 700, etc. (above, Columbia Carbon (Carbon
(Columbia)), Regal 1 400R, Regal 1 330R, Regal 1 660R, Mogu L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1300, MonC K.)), Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color B1ack S150, Color Black S160, Color Black S160, Color Black S160, Color Black S160, Color Black SFW, Color Black FW2V, Color Black FW2 140U, Special Black 6, Special Black 5, Special Black 4A, Special Black 4 (manufactured by Degussa).

Although it does not specifically limit as a pigment used as a yellow color material, For example, C.I. I.
Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, 120, 124, 128, 129, 133, 138, 139, 147, 151, 153, 154, 155, 167, 172, 180.

  Although it does not specifically limit as a pigment used as a white color material, For example, C.I. I. Pigment white 6, 18, 21, basic lead carbonate, zinc oxide, titanium oxide, strontium titanate and the like.

  Although it does not specifically limit as a pigment used as a magenta color material, For example, C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 88, 112, 114, 122, 123, 144, 146, 149, 150, 166, 168 170, 171, 175, 176, 177, 178, 179, 184, 185, 187, 202, 209, 219, 224, 245, or C.I. I. Pigment violet 19, 23, 32, 33, 36, 38, 43, 50.

  Although it does not specifically limit as a pigment used as a cyan color material, For example, C.I. I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15:34, 15: 4, 16, 18, 22, 25, 60, 65, 66, C.I. I. Bat Blue 4, 60.

  The pigments other than magenta, cyan, and yellow color materials are not particularly limited. I. Pigment green 7,10, C.I. I. Pigment brown 3, 5, 25, 26, C.I. I. Pigment orange 1, 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, 63.

  The said pigment may be used individually by 1 type, and may use 2 or more types together.

  When the above pigment is used, the average particle diameter of the pigment is preferably in the range of 10 nm to 200 nm, more preferably in the range of 50 nm to 150 nm.

  The addition amount of the pigment that can be added to the radiation curable inkjet composition according to the present embodiment is 0.1% by mass or more and 25% by mass or less, and more preferably with respect to the total mass of the radiation curable inkjet composition. Is 0.5 mass% or more and 15 mass% or less.

  In addition to a pigment, a dye can be used as a color material. The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used.

<Polymerizable compound>
The radiation curable inkjet composition may contain a polymerizable compound. The polymerizable compound can be polymerized at the time of light irradiation alone or by the action of a photopolymerization initiator to cure the ink jet composition on the recording medium. The polymerizable compound is not particularly limited, and specifically, conventionally known monofunctional, bifunctional, and trifunctional or higher polyfunctional monomers and oligomers can be used. A polymeric compound may be used individually by 1 type, and may be used in combination of 2 or more type. Hereinafter, these polymerizable compounds will be exemplified.

  Monofunctional, bifunctional, and trifunctional or higher polyfunctional monomers are not particularly limited, and examples thereof include unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid, crotonic acid, isocrotonic acid and maleic acid; Saturated carboxylic acid salts; unsaturated carboxylic acid esters, urethanes, amides and anhydrides; acrylonitrile, styrene, various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes. In addition, monofunctional, bifunctional, and trifunctional or higher polyfunctional oligomers are not particularly limited. For example, oligomers formed from the above monomers such as linear acrylic oligomers, epoxy (meth) acrylates, oxetanes ( Mention may be made of (meth) acrylates, aliphatic urethane (meth) acrylates, aromatic urethane (meth) acrylates and polyester (meth) acrylates.

  Moreover, an N-vinyl compound may be included as another monofunctional monomer or polyfunctional monomer. The N-vinyl compound is not particularly limited, and examples thereof include N-vinylformamide, N-vinylcarbazole, N-vinylacetamide, N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, and derivatives thereof. It is done.

  Although it does not specifically limit as monofunctional (meth) acrylate, For example, isoamyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, isomyristyl (meta) ) 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, tetra Drofurfuryl (meth) acrylate, isobornyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, lactone-modified flexibility (meta ) Acrylate, t-butylcyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and dicyclopentenyloxyethyl (meth) acrylate. Among these, phenoxyethyl (meth) acrylate is preferable.

  30-85 mass% is preferable with respect to the total mass (100 mass%) of a radiation-curable inkjet composition, and, as for content of monofunctional (meth) acrylate, 40-75 mass% is more preferable. By setting it as the said preferable range, it exists in the tendency which is excellent with sclerosis | hardenability, initiator solubility, storage stability, and discharge stability.

Examples of the monofunctional (meth) acrylate include those containing a vinyl ether group. Such monofunctional (meth) acrylates are not particularly limited, and examples thereof include, for example, 2-vinyloxyethyl (meth) acrylate, 3-vinyloxypropyl (meth) acrylate, and 1-methyl-2- (meth) acrylate. Vinyloxyethyl, 2-vinyloxypropyl (meth) acrylate, 4-vinyloxybutyl (meth) acrylate, 1-methyl-3-vinyloxypropyl (meth) acrylate, 1-vinyloxymethylpropyl (meth) acrylate, ( 2-methyl-3-vinyloxypropyl (meth) acrylate, 1,1-dimethyl-2-vinyloxyethyl (meth) acrylate, 3-vinyloxybutyl (meth) acrylate, 1-methyl-2-vinyl (meth) acrylate Loxypropyl, 2-vinyloxybutyl (meth) acrylate, 4-vinyloyl (meth) acrylate Cycyclohexyl, 6-vinyloxyhexyl (meth) acrylate, 4-vinyloxymethylcyclohexylmethyl (meth) acrylate, 3-vinyloxymethylcyclohexylmethyl (meth) acrylate, 2-vinyloxymethyl (meth) acrylate Cyclohexylmethyl, (meth) acrylic acid p-vinyloxymethylphenylmethyl, (meth) acrylic acid m-vinyloxymethylphenylmethyl, (meth) acrylic acid o-vinyloxymethylphenylmethyl, (meth) acrylic acid 2- ( Vinyloxyethoxy) ethyl, 2- (vinyloxyisopropoxy) ethyl (meth) acrylate, 2- (vinyloxyethoxy) propyl (meth) acrylate, 2- (vinyloxyethoxy) isopropyl (meth) acrylate, ( 2-methacrylic acid (meth) acrylic acid Poxy) propyl, 2- (vinyloxyisopropoxy) isopropyl (meth) acrylate, 2- (vinyloxyethoxyethoxy) ethyl (meth) acrylate, 2- (vinyloxyethoxyisopropoxy) ethyl (meth) acrylate, 2- (vinyloxyisopropoxyethoxy) ethyl (meth) acrylate, 2- (vinyloxyisopropoxyisopropoxy) ethyl (meth) acrylate, 2- (vinyloxyethoxyethoxy) propyl (meth) acrylate, (meth ) 2- (vinyloxyethoxyisopropoxy) propyl acrylate, 2- (vinyloxyisopropoxyethoxy) propyl (meth) acrylate, 2- (vinyloxyisopropoxyisopropoxy) propyl (meth) acrylate, (meth) Acrylic acid 2- (vinyloxyethoxyethoxy) Ii) Isopropyl, 2- (vinyloxyethoxyisopropoxy) isopropyl (meth) acrylate, 2- (vinyloxyisopropoxyethoxy) isopropyl (meth) acrylate, 2- (vinyloxyisopropoxyisopropoxy) (meth) acrylate ) Isopropyl, 2- (vinyloxyethoxyethoxyethoxy) ethyl (meth) acrylate, 2- (vinyloxyethoxyethoxyethoxyethoxy) ethyl (meth) acrylate, 2- (isopropenoxyethoxy) ethyl (meth) acrylate , 2- (Isopropenoxyethoxyethoxy) ethyl (meth) acrylate, 2- (Isopropenoxyethoxyethoxyethoxy) ethyl (meth) acrylate, 2- (Isopropenoxyethoxyethoxyethoxyethoxy) acrylate (meth) acrylate ethyl,( Data) Polyethylene glycol monovinyl ether acrylate, and (meth) acrylic acid polypropylene glycol monovinyl ether, phenoxyethyl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate. Among these, 2- (vinyloxyethoxy) ethyl (meth) acrylate, phenoxyethyl (meth) acrylate, isobornyl (meth) acrylate, and benzyl (meth) acrylate are preferable.

  Among these, the radiation-curable inkjet composition can have a lower viscosity, has a high flash point, and is excellent in the curability of the inkjet composition. Therefore, 2- (vinyloxyethoxy) ethyl (meth) acrylate, that is, At least one of 2- (vinyloxyethoxy) ethyl acrylate and 2- (vinyloxyethoxy) ethyl methacrylate is preferable, and 2- (vinyloxyethoxy) ethyl acrylate is more preferable. Since both 2- (vinyloxyethoxy) ethyl acrylate and 2- (vinyloxyethoxy) ethyl methacrylate have a simple structure and a small molecular weight, the viscosity of the radiation-curable inkjet composition should be significantly reduced. Can do. Examples of 2- (vinyloxyethoxy) ethyl (meth) acrylate include 2- (2-vinyloxyethoxy) ethyl (meth) acrylate and 2- (1-vinyloxyethoxy) ethyl (meth) acrylate. Examples of 2- (vinyloxyethoxy) ethyl acrylate include 2- (2-vinyloxyethoxy) ethyl acrylate and 2- (1-vinyloxyethoxy) ethyl acrylate. Incidentally, 2- (vinyloxyethoxy) ethyl acrylate is superior in terms of curability compared to 2- (vinyloxyethoxy) ethyl methacrylate.

The vinyl ether group-containing (meth) acrylic acid esters, particularly the content of 2- (vinyloxyethoxy) ethyl (meth) acrylate, is 10 with respect to the total mass (100% by mass) of the radiation curable inkjet composition. -70 mass% is preferable, and 30-50 mass% is more preferable. When the content is 10% by mass or more, the viscosity of the radiation curable inkjet composition can be lowered, and the curability of the radiation curable inkjet composition tends to be more excellent. On the other hand, when the content is 70% by mass or less, the storability of the inkjet composition is more excellent and the surface gloss of the printed matter tends to be more excellent.

  Among the (meth) acrylates, the bifunctional (meth) acrylate is not particularly limited. For example, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 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-nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, dimethylol-tricyclodecane di (meth) acrylate, EO (ethylene oxide) addition of bisphenol A Di (meth) acrylate, PO (propylene oxide) adduct of bisphenol A di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate , Triethylene glycol di (meth) acrylate, and trifunctional or higher functional (meth) acrylate having a pentaerythritol skeleton or a dipentaerythritol skeleton. Among these, dipropylene glycol di (meth) acrylate is preferable. Among them, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, pentaerythritol skeleton or dipentaerythritol skeleton having 3 or more functional groups (Meth) acrylate is preferred. More preferably, the radiation curable ink jet composition contains polyfunctional (meth) acrylate in addition to monofunctional (meth) acrylate.

  5-60 mass% is preferable with respect to the total mass (100 mass%) of a radiation curable inkjet composition, and, as for content of polyfunctional (meth) acrylate more than bifunctional, 15-60 mass% is more preferable, 20-50 mass% is further more preferable. By setting it as the said preferable range, it exists in the tendency which is excellent by sclerosis | hardenability, storage stability, discharge stability, and the surface gloss of printed matter.

  Among the above (meth) acrylates, trifunctional or higher polyfunctional (meth) acrylates are not particularly limited, and examples thereof include 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 ethoxytetra (meth) acrylate, and caprolactam-modified dipentaerythritol hexa (meth) acrylate.

  Among these, it is preferable that a polymeric compound contains monofunctional (meth) acrylate. In this case, the radiation curable inkjet composition has a low viscosity, is excellent in solubility of the photopolymerization initiator and other additives, and is easy to obtain ejection stability during inkjet recording. Furthermore, since the toughness, heat resistance, and chemical resistance of the cured film are increased, it is more preferable to use a monofunctional (meth) acrylate and a bifunctional (meth) acrylate together. Among them, phenoxyethyl (meth) acrylate and dipropylene glycol are more preferable. It is more preferable to use di (meth) acrylate in combination.

5-95 mass% is preferable with respect to the total mass (100 mass%) of a radiation-curable inkjet composition, and, as for content of the said polymeric compound, 15-90 mass% is more preferable. When the content of the polymerizable compound is within the above range, the viscosity and odor can be further reduced, and the solubility and reactivity of the photopolymerization initiator and the surface gloss of the printed material should be further improved. Can do.

<Photopolymerization initiator>
The radiation curable inkjet composition may contain a photopolymerization initiator. The photopolymerization initiator is not particularly limited as long as it generates active species such as radicals and cations by irradiating actinic radiation and initiates the polymerization reaction of the monomer. As the photopolymerization initiator, a radical photopolymerization initiator or a cationic photopolymerization initiator can be used, but it is preferable to use a radical photopolymerization initiator.

  In addition, it is excellent in safety | security by using an ultraviolet-ray (UV) among radiation, and the cost of a light source lamp can be held down. Therefore, the photopolymerization initiator preferably has an absorption peak in the ultraviolet region.

  Examples of the photo radical polymerization initiator include aromatic ketones, acylphosphine oxide compounds, aromatic onium salt compounds, organic peroxides, thio compounds (thioxanthone compounds, thiophenyl group-containing compounds, etc.), hexaarylbiimidazole compounds, and the like. Ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon halogen bond, and alkylamine compounds.

  Among these, at least one selected from an acylphosphine oxide compound and a thioxanthone compound is preferable from the viewpoint of obtaining an advantageous effect that the solubility in the monomer and the curability are good, and the acylphosphine oxide compound and the thioxanthone compound are used in combination. More preferably.

  Specific examples of the photo 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, diethyl Oxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, bis (2,4,6-trimethylbenzoyl) -phenyl Phosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2,4-diethylthioxanthone, and bis- (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide Can be mentioned.

Examples of commercially available photo 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 2959 (1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane- 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-morpholine Propan-1-one), IRGACURE 369 (2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1), IRGACURE 379 (2- (dimethylamino) -2-[(4- Methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone), DAROCUR 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. -Octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)]), IRGACURE OXE 02 (ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazole) -3-yl]-, 1- (O-acetyloxime)), IRGACURE 754 (oxyphenylacetic acid, 2- [2-oxo-2-phenylacetoxyethoxy] ethyl ester and oxyphenylacetic acid, 2- (2-hydroxy Mixture of ethoxy) ethyl ester), Lucirin TPO, LR8883, LR8970 (above, manufactured by BASF Japan), KAYACURE DETX-S (2,4-diethylthioxanthone) (manufactured by Nippon Kayaku Co., Ltd.), Ubekrill P36 (manufactured by UCB) ), Speedcure TPO (diphenyl-2,4 6- trimethyl benzoyl phosphine oxide), Speedcure DETX (2,4-diethyl thioxanthone-9-one) (or include Lambson Corp.).

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

  The content of the photopolymerization initiator is preferably 0.5% by mass or more and 10% by mass or less with respect to the total mass of the radiation curable inkjet composition. When the content of the photopolymerization initiator is within the above range, the ultraviolet curing rate is sufficiently high, and the photopolymerization initiator is hardly dissolved and there is almost no color derived from the photopolymerization initiator. As described above, when the photopolymerization initiator contained in the inkjet composition is an acyl phosphine oxide compound and / or a thioxanthone compound, the content of the acyl phosphine oxide compound is the total mass of the radiation curable inkjet composition. It is preferable that it is 2 mass% or more with respect to. On the other hand, the content of the thioxanthone compound is preferably 1% by mass or more with respect to the total mass of the radiation curable inkjet composition.

  Although the addition of a photopolymerization initiator can be omitted by using a photopolymerizable compound as the above-mentioned monomer, the use of a photopolymerization initiator can easily adjust the start of polymerization. Can be preferred.

<Surfactant>
The inkjet composition according to this embodiment can further include a surfactant. Although it does not specifically limit as surfactant, For example, silicone type surfactant (As a commercial item, BYK UV3500, UV3570 (BIC Chemie Japan brand name)), an acrylic surfactant (BYK350 (BIC Chemie), for example)・ Japan trade name)). Among these, by including a silicone surfactant, the surface tension lowering ability is excellent, the wettability to the recording medium is improved, the solid filling is excellent, and the surface tension tends to be easily adjusted.

The content of the surfactant is preferably 0.20% by mass or more, more preferably 0.30% by mass or more, further preferably 0.40% by mass or more with respect to the total mass (100% by mass) of the inkjet composition. 0.50% by mass or more is particularly preferable. Further, the content is preferably 1.0% by mass or less, more preferably 0.8% by mass or less, and further preferably 0.7% by mass or less. When the content of the surfactant is 0.20% by mass or more, the wettability to the recording medium tends to be more excellent. Further, when the content of the surfactant is 1.0% by mass or less, the liquid repellency of the head nozzle plate tends to be kept good and the ejection stability tends to be excellent.

  The surface tension of the inkjet composition is preferably 23 mN / m or less, and more preferably 22 mN / m or less. Further, the lower limit of the surface tension is not particularly limited, and the lower the better. When the surface tension is within the above range, the wettability to the recording medium tends to be more excellent. As a method for measuring the surface tension, a commonly used surface tension meter (for example, surface tension meter CBVP-Z manufactured by Kyowa Interface Science Co., Ltd.) is used and measured at a liquid temperature of 25 ° C. by the Wilhelmy method. A method can be exemplified.

  As the silicone surfactant, a polysiloxane compound is preferably used, and examples thereof include polyether-modified organosiloxane. Moreover, a commercial item can be used, for example, BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348 (above, trade name, manufactured by Big Chemie Japan Co., Ltd.) KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6020, X-22-4515 , KF-6011, KF-6012, KF-6015, KF-6017 (trade names, manufactured by Shin-Etsu Chemical Co., Ltd.).

<Dispersant>
When the radiation curable inkjet composition contains a pigment, it may further contain a dispersant in order to improve the pigment dispersibility. Although it does not specifically limit as a dispersing agent, For example, the dispersing agent currently used in preparing pigment dispersion liquids, such as a polymer dispersing agent, is mentioned. Specific examples include polyoxyalkylene polyalkylene polyamines, vinyl polymers and copolymers, acrylic polymers and copolymers, polyesters, polyamides, polyimides, polyurethanes, amino polymers, silicon-containing polymers, sulfur-containing polymers, fluorine-containing polymers, and epoxies. The thing which has 1 or more types of resin as a main component is mentioned. Commercially available polymer dispersants include Ajinomoto Fine Techno's Ajisper series, Solspers series (Solsperse 36000, etc.) available from Avecia and Noveon, and BYK Chemie's Dispersic series. , Disparon series manufactured by Enomoto Kasei.

<Other additives>
The radiation curable inkjet composition may contain additives (components) other than the additives listed above. Such components are not particularly limited, and may include, for example, conventionally known slip agents (surfactants), polymerization accelerators, penetration enhancers, wetting agents (humectants), and other additives. The other additive is not particularly limited, and examples thereof include conventionally known fixing agents, antifungal agents, preservatives, antioxidants, ultraviolet absorbers, chelating agents, pH adjusting agents, and thickeners. Can be mentioned.

<Method for preparing radiation curable inkjet composition>
The radiation curable inkjet composition according to this embodiment is obtained by mixing the components described above in an arbitrary order, and removing impurities by filtering or the like as necessary. As a method for mixing the components, a method in which materials are sequentially added to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer and stirred and mixed is suitably used. As a filtration method, centrifugal filtration, filter filtration, or the like can be performed as necessary.

<Physical properties of radiation curable ink jet composition>
The viscosity at 20 ° C. of the radiation curable inkjet composition used in the present embodiment is preferably 5 mPa · s to 50 mPa · s, more preferably 20 mPa · s to 40 mPa · s. When the viscosity at 20 ° C. of the radiation curable inkjet composition is within the above range, an appropriate amount of the radiation curable inkjet composition is ejected from the nozzle, and the flight bending and scattering of the radiation curable inkjet composition can be further reduced. Therefore, it can be suitably used for an ink jet apparatus. The viscosity was measured by using a viscoelasticity tester MCR-300 (manufactured by Pysica), increasing the Shear Rate to 10 to 1000 in an environment of 20 ° C., and reading the viscosity at Shear Rate 200 hours.

  The surface tension at 20 ° C. of the radiation curable inkjet composition used in the present embodiment is preferably 20 mN / m or more and 30 mN / m or less. When the surface tension at 20 ° C. of the radiation curable ink jet composition is within the above range, the radiation curable ink jet composition is less likely to be wetted by the liquid-repellent treated nozzle. Accordingly, an appropriate amount of the radiation curable ink jet composition is discharged from the nozzle, and flight bending and scattering of the radiation curable ink jet composition can be further reduced, so that it can be suitably used for an ink jet apparatus. The surface tension was measured by using an automatic surface tension meter CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.) to confirm the surface tension when the platinum plate was wetted with ink in an environment of 20 ° C.

1.4. Wiping process In the wiping process according to the present embodiment, as described above, the wiping means 30 includes an absorbent body impregnated with an organic solvent containing at least one of an ether derivative of glycol and an ester derivative of glycol and a polymerization inhibitor. The nozzle surface 37 of the inkjet head 22 is wiped off.

  More specifically, in the wiping process according to the present embodiment, as described above, the pressing member 87 presses the long wiping member 30 against the nozzle surface 37 of the inkjet head 22 to apply a pressing load. The nozzle surface 37 is wiped off. In addition, during the recording process of discharging the radiation curable inkjet composition onto the recording medium P, the absorber impregnated with the impregnating liquid containing the organic solvent is waited, and the wiping process is performed after the recording process is completed.

  In an inkjet apparatus that records an image by irradiating a radiation curable inkjet composition with light, nozzle clogging due to reflected light or leakage light from light irradiation tends to occur. However, in the cleaning method according to this embodiment, the above-described cleaning method is used. Since the wiping process using the impregnating liquid is performed, the cleaning performance of the nozzle surface 37 is excellent, and occurrence of problems such as nozzle clogging can be effectively suppressed.

1.5. Preliminary ejection process The inkjet device cleaning method according to the present embodiment includes a preliminary ejection process in which a radiation curable inkjet composition is preliminarily ejected from the nozzle after the wiping process, and in this preliminary ejection process, a nozzle that performs preliminary ejection; It is preferable to have a nozzle that does not perform preliminary discharge. Immediately after cleaning of the nozzle surface 37, a large amount of the polymerization inhibitor diffuses into the nozzle 38, so that the radiation curable inkjet composition is hard to be photocured. The image quality is impaired. Therefore, the nozzle rows and nozzles used in the printed image are discarded after cleaning to make the ink in the nozzles fresh. On the other hand, for the nozzle rows and nozzles that are not used in the printed image, by maintaining a state where the photocuring is not performed, curing of the ink in the vicinity of the nozzle due to the influence of leakage light during the next printing is prevented, and alignment deterioration, that is, ejection reliability Suppresses the decline.

The nozzle that does not perform the preliminary ejection is at least the first that ejects the radiation curable inkjet composition while changing the relative positions of the recording medium P and the inkjet head 22 in the first recording performed after the preliminary ejection process. This nozzle is not used in this scanning. The scanning is an operation of moving the carriage 20 once with respect to the recording medium P shown in FIG. In the case of a carriage type printer, if there are flushing boxes on both sides of the printer, it can be discarded after one scan, so at least nozzles not used in the first scan do not need to be pre-discharged before the first scan. In the case of a line printer, since printing is completed in one scan, a nozzle that does not perform preliminary ejection is selected depending on whether it is used or not at all.

  Presence / absence of preliminary ejection may be selected in units of nozzle rows or in units of nozzles. For example, when the presence / absence of use is determined in units of ink, such as white ink and color ink, it is preferably performed in units of nozzle rows. .

2. EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited only to these examples.

2.1. Preparation of radiation curable ink jet composition Prior to evaluation on wiping, a pigment dispersion was first prepared. As a pigment used in composition 1, 2 parts by mass of carbon black and 1 part by mass of solspers 36000 (manufactured by THE LUBRIZOL CORP) as a dispersant were added to make a total of 100 parts by mass, followed by mixing and stirring to obtain a mixture. This 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 Co., Ltd.). Then, the black pigment dispersion liquid was obtained by isolate | separating a zirconia bead with a separator. Similarly, a cyan pigment dispersion, a magenta pigment dispersion, a yellow pigment dispersion, and a white pigment dispersion were obtained.

Next, a polymerizable compound, a surfactant, a polymerization inhibitor, a polymerization initiator, and a dispersant were mixed and completely dissolved so that the composition (mass%) shown in Table 1 was obtained, and then at room temperature for 1 hour. Mixing and stirring were performed, and the pigment dispersion was added dropwise thereto while stirring so that the concentration of the black pigment was as shown in Table 1. After completion of dropping, the mixture was stirred for 1 hour at room temperature, and further filtered through a 5 μm membrane filter to obtain a black radiation curable ink jet composition of composition 1. Similarly, composition 2 (magenta radiation curable inkjet composition), composition 3 (cyan radiation curable inkjet composition), composition 4 (yellow radiation curable inkjet composition), and composition 5 (white radiation curable inkjet composition). Product).
The components used in Table 1 are as follows.
(1) Polymerizable compound / PEA (phenoxy acrylate, Osaka Organic Chemical Industry Co., Ltd., trade name “Biscoat # 192”)
VEEA (2- (2-hydroxyethoxy) ethyl acrylate, manufactured by Nippon Shokubai Co., Ltd.) SR508 (dipropylene glycol diacrylate, manufactured by Sartomer)
DPHA (dipentaerythritol hexaacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.) (2) Surfactant BYK-UV3500 (manufactured by Big Chemie Japan Co., Ltd., polydimethylsiloxane having a polyether-modified acrylic group)
(3) Polymerization inhibitor / MEHQ (p-methoxyphenol, manufactured by Kanto Chemical Co., Inc.)
(4) Polymerization initiator IRGACURE 819 (Ciba Japan, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide)
Speedcure DETX (manufactured by Lambson, 2,4-diethylthioxanthen-9-one)
(5) For dispersant and color: solpers 36000 (manufactured by THE LUBRIZOL CORP)
・ For titanium oxide: BYK180 (manufactured by BYK)
(6) Pigment, carbon black, PB15: 3 (CI pigment blue 15: 3)
・ PR122 (CI Pigment Red 122)
・ PY155 (CI Pigment Yellow 155)
・ Titanium oxide

2.2. Evaluation on wiping Evaluation on wiping was performed using an impregnating solution having the composition shown in Table 2.

2.2.1. Evaluation of ink wiping property before exposure to nozzle surface light Epson SC-S50650 was remodeled and used as a printer. Irradiation light source LEDs having a peak wavelength of 395 nm were mounted as light sources on the left and right sides of the carriage head. Five nozzle rows of heads were filled with different color inks (5 colors prepared in 2.1.) For each nozzle row. Here, one nozzle row is the number of 360 nozzles. First, printing for ejecting ink onto a recording medium using all nozzles was performed for 5 minutes. Here, the light source was turned off for the test. Subsequently, all nozzles were capped and subjected to suction cleaning, and then the following wiping was performed to evaluate the wiping property of the nozzle surface.

  A cellulose long-fiber nonwoven fabric (trade name Benize) was used for the absorbent body (cloth wiper), and impregnating liquid was impregnated so as to be 80 wt% with respect to 100 wt% of the absorbent body. In the wiping operation, the wiping means (absorber) is brought into contact with the nozzle plate and pressed on the surface from the back of the wiping means to the nozzle plate with a pressing member with a load of 350 gf in a direction perpendicular to the nozzle row. It was moved 20 cm from end to end. As shown in FIG. 3, the wiping means has a roll shape, and a new part is pulled out and used for the next wiping. In Example 6, the same procedure as in Example 3 was performed except that the weight of wiping was set to 110 kf.

The evaluation criteria for the ink wiping property are as follows.
A: The ink is cleanly wiped off including the nozzle plate and the step portion of the nozzle plate and the head cover.
◯: Some ink remains on the step.
X: There is a lot of ink remaining on the nozzle plate.

2.2.2. Evaluation of ejection reliability after exposure to nozzle surface light Turn on the irradiation light source of the printer, perform printing while exposing the nozzle surface to light under light irradiation conditions corresponding to an illuminance of 20 μW / cm ² and a light amount of 4500 mJ / cm ² . 2.2.1. The suction cleaning and wiping described in 1 were performed, followed by a nozzle discharge test. Since the illuminance on the nozzle surface is due to the reflected light or leakage light of the irradiation light source, printing was performed until the accumulated light amount becomes the light amount at the illuminance. Here, illuminance × irradiation time = light quantity (irradiation energy). Cleaning (suction / wiping) and the discharge test were set as one set, and this set was repeated to evaluate the cleaning induction (discharge reliability). The evaluation criteria are as follows.
A: Normal discharge with 2 sets or less.
◯: Normal discharge with 3 sets.
X: Even if 3 sets or more, it may not recover.

2.2.3. Evaluation of ink wiping property after exposure to nozzle surface light 2.2.1. After performing the operation described in 2) until wiping, 2.2.2. Printing is performed under the same conditions as described above, and then 2.2.1. Evaluation after the suction cleaning described in 1. was performed. That is, light exposure is performed with the impregnating liquid attached to the nozzle surface, and then 2.2.1. Wipe as described in 2.2.1. In the same manner as above, the wipeability of the nozzle surface was evaluated.

2.2.4. Evaluation of long-term ink wiping property 2.2.1. Other than using a cloth wiper impregnated with an impregnating solution and using it after being left open for 1 month at room temperature and humidity. And evaluated in the same manner. In Example 6, the same procedure as in Example 3 was performed except that the weight of wiping was set to 110 kf.

2.2.5. Evaluation of durability of water-repellent layer on nozzle surface 2.2.1. The operation from printing to wiping as described in 1 was repeated 15000 times, and the durability of the water repellent layer having a liquid repellent film was evaluated. The evaluation criteria are as follows.
○: Level at which liquid-repellent film peeling cannot be observed Δ: Level at which liquid-repellent film is slightly peeled and discolored, but does not affect discharge ×: Level at which liquid-repellent film is peeled off and affects discharge

2.2.6. Evaluation results regarding wiping Table 2 shows the evaluation results regarding wiping. In Examples including both an ether derivative of glycol having 8 or more carbon atoms and an ester derivative of glycol and a polymerization inhibitor, the ink was wiped cleanly both before and after exposure to nozzle surface light and after leaving open. . However, in comparison with Example 2, in Example 5 that does not contain a surfactant, the wiping property was slightly inferior both before and after exposure to the nozzle surface light. Further, in Example 6 in which the weight of wiping was larger than that in Example 3, the wiping property was improved as compared with Example 3.

  On the other hand, in Comparative Example 1 using an organic solvent that is neither an ether derivative of glycol having 8 or more carbon atoms nor an ester derivative of glycol, the nozzle surface light was obtained despite containing a polymerization inhibitor and a surfactant. There was a lot of ink remaining on the nozzle plate both before and after exposure and after being left open. The same result was obtained in Comparative Example 2 using the same organic solvent as Comparative Example 1 and containing no polymerization inhibitor. Further, in Comparative Example 3 which contains an ester derivative of glycol having 8 or more carbon atoms but does not contain a polymerization inhibitor, the wiping property after exposure to nozzle surface light was deteriorated.

  In addition, with regard to ejection reliability after exposure to light on the nozzle surface, when the impregnating liquid of the example with good wiping property was used, it was solidified by light exposure (partially cured, etc.) when wiping with a cloth wiper. Since the ink was prevented from being rubbed into the nozzle surface, the cleaning induction was good, and all of them were normally ejected within 3 sets. On the other hand, in Comparative Examples 1 and 2 in which the wiping property is inferior, the ejection reliability after exposure to the nozzle surface light was also inferior.

  Further, regarding the durability of the water-repellent layer on the nozzle surface, in Example 6 where the wiping load was larger than that in Example 3, the wiping property was improved as compared with Example 3, but the durability of the water-repellent layer on the nozzle surface was improved. As a result, it was found that the liquid-repellent film peeled off when wiping with a strong force had an effect on ejection. In addition, it was also found that Example 5 which does not contain a surfactant has an influence on ejection because the liquid repellent film is peeled off when wiping with a cloth wiper.

2.3. Evaluation of Preliminary Discharge Process Next, the preliminary discharge process before the discharge process was evaluated. First, in the printer, only two nozzle rows were used, and each was filled with the ink composition 1 shown in Table 1. Next, using the impregnation liquid of Example 1, 2.2.1. The test described in 1 was performed until wiping, and then, one nozzle row was discarded with 1000 drops of ink to the flushing box, and the other nozzle row was not discarded. Next, the irradiation light source was turned on, and printing was performed on the recording medium. The light exposure conditions were such that the nozzle surface was exposed to light with an illuminance of 10,000 μW / cm ² and a light amount of 4000 mJ / cm ² . Here, simulated printing is performed in which only exposure is reproduced without ejecting ink from the nozzles during printing.

  Subsequently, nozzle alignment evaluation was performed. First, after the simulated printing, 2.2.1. Then, the nozzle alignment was visually evaluated by printing (using a microscope). In other words, the nozzle alignment was evaluated by ejecting ink droplets onto the recording medium and evaluating the deviation of the landing position from the normal landing position.

As a result of the nozzle alignment evaluation, no deterioration of the nozzle alignment was observed in the nozzle rows that were not discarded. On the other hand, in the discarded nozzle row, deterioration of nozzle alignment was recognized. Thus, when the impregnating solution contains a polymerization inhibitor, ink curing at the nozzles due to light exposure is prevented, so that the nozzle rows not used in the printed image can be kept in a state where they are not photocured. For this reason, it was possible to prevent the ink in the vicinity of the nozzle from being hardened due to the influence of the leaked light at the time of the next printing, and to suppress the alignment deterioration, that is, the decrease in the ejection reliability.

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

P: Recording paper, HP: Home position, 1 ... Inkjet printer, 12 ... Frame, 20 ... Carriage, 22 ... Inkjet head, 23A, 23B ... Actinic radiation irradiation device, 26 ... Head cleaning device, 30 ... Wiping means, 31 ... Wiper cassette, 32 ... wiper holder, 33 ... moving mechanism, 34 ... wiper unit, 35 ... nozzle plate cover, 36 ... nozzle row, 37 ... nozzle surface, 38 ... nozzle, 80 ... housing, 81 ... feeding roller, 82 ... Winding roller, 84 ... winding gear, 85 ... winding gear, 86 ... tension roller, 86a ... shaft, 87 ... pressing member, 87a ... shaft, 88 ... tension roller, 88a ... shaft, 89 ... relay roller 89a ... Shaft portion, 90 ... Bar spring, 91 ... Bearing hole, 92 ... Nipping roller 92a ... shank, 93 ... spring member 94 ... relay gear

Claims (9)

In an inkjet apparatus for discharging a radiation curable inkjet composition,
A wiping step of wiping the nozzle surface of the inkjet head with a wiping means comprising an absorbent body impregnated with an impregnating liquid containing an organic solvent containing at least one of an ether derivative of glycol and an ester derivative of glycol and a polymerization inhibitor ;
After the wiping step, a preliminary discharge step of preliminary discharging the radiation curable inkjet composition from the nozzle,
A method for cleaning an inkjet apparatus , comprising: a nozzle that performs the preliminary ejection and a nozzle that does not perform the preliminary ejection in the preliminary ejection step . In claim 1,
A method for cleaning an inkjet apparatus, wherein the polymerization inhibitor is at least one selected from the group consisting of catechols, hindered amines, phenols, phenothiazines, and condensed aromatic ring quinones. In claim 1 or claim 2,
A method for cleaning an ink jet apparatus, wherein the content of the polymerization inhibitor in the impregnating liquid is 0.1% by mass or more and 1% by mass or less. In any one of Claims 1 thru | or 3,
A method for cleaning an inkjet device, wherein the ether derivative of glycol and the ester derivative of glycol have 8 or more carbon atoms. In any one of Claims 1 thru | or 4,
A method for cleaning an inkjet apparatus, wherein the absorber is further impregnated with a surfactant. In claim 5,
A method for cleaning an ink jet device, wherein the surfactant is at least one selected from the group consisting of polyether-modified silicones, polyester-modified silicones, and acetylenic diols. In any one of Claims 1 thru | or 6,
A method for cleaning an ink jet apparatus, wherein the radiation curable ink jet composition contains an inorganic pigment. In any one of Claims 1 thru | or 7 ,
In the first recording performed after the preliminary ejection step, the nozzle that does not perform the preliminary ejection in at least the first scan that ejects the radiation curable inkjet composition while changing the relative position of the recording medium and the inkjet head. A method for cleaning an inkjet device, which is a nozzle that is not used. To clean by the cleaning method according to any one of claims 1 to 8, the inkjet apparatus.

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