JP5428887B2 - Liquid ejecting apparatus and maintenance method - Google Patents

Description

  The present invention relates to a liquid ejecting apparatus and a maintenance method.

  Ink jet printers form printed images on printing paper by ejecting ink droplets from the nozzles of the print head. However, if the ink thickens or solidifies inside the nozzles, ink droplet ejection failure occurs. End up. In order to prevent such ejection failure, generally, an ink jet printer is provided with maintenance means having a cap as disclosed in Patent Document 1.

  Here, the cap disclosed in Patent Document 1 is provided with an air communication port, and a tube is connected to the air communication port. A communication valve is provided. Further, the cap is provided with a suction port, and this suction port is connected to a suction device. In Patent Document 1, in order to solve the so-called hole clogging, the ink remaining in the cap is solidified, and a sealing plate for sealing the cap is provided, and the cleaning liquid is supplied via the atmosphere communication valve. A configuration for sucking or discharging a cleaning liquid from a suction port is disclosed.

Japanese Patent Application Laid-Open No. 9-240000 (see abstract, FIG. 4, FIG. 5, etc.)

  By the way, when the cap is brought into contact with the nozzle forming surface of the print head and the suction device is operated, the tube connected to the atmosphere communication port is also contracted by the action of the negative pressure. Here, when the negative pressure in the cap is eliminated when the atmosphere is released, the above-described shrinkage of the tube is also eliminated, but a small amount of ink is sucked from the cap when the shrinkage is eliminated. Then, the ink entering from the atmosphere communication port is solidified, so that the flow path such as the tube may be blocked. Moreover, the ink that has entered from the atmosphere communication port becomes a film shape and may be solidified in the film shape. In these cases, even if the atmospheric communication valve is switched to the open side, air may be prevented from flowing into the cap.

  Such a problem is not solved even when the configuration of Patent Document 1 described above is employed.

  The present invention has been made on the basis of the above circumstances, and an object of the present invention is to provide a liquid ejecting apparatus and a maintenance method capable of preventing the liquid entering from the air communication port from solidifying in the flow passage. To do.

In order to solve the above problems, a liquid ejecting apparatus of the present invention includes a first ejecting nozzle row that ejects ink containing a colorant, and a cleaning liquid that can dissolve the colorant contained in the ink. An ejection head having a second ejection nozzle row to be ejected, and a sealed space is formed in contact with the nozzle formation surface of the ejection head, and ejection is performed from at least one of the first ejection nozzle row and the second ejection nozzle row. A cap for receiving the ink and / or the cleaning liquid, a suction unit that performs suction from the suction port of the sealed space, and an atmosphere release unit that opens the atmosphere from the atmosphere communication port of the sealed space. injection nozzle row, the than the first discharge nozzle rows are arranged on the side of the atmosphere communication port, the first discharge nozzle row is provided with a plurality so as to correspond to the type of ink In both cases, the lower the viscosity of the ink ejected from each of the plurality of first ejection nozzle rows, the straight line passing through the first ejection nozzle row and parallel to the ink ejection direction, and the air communication. The distance between the mouth is short .

In such a configuration, the second injection nozzle row is disposed closer to the atmosphere communication port than the first injection nozzle row, so that the liquid present in the vicinity of the atmosphere communication port A large amount of cleaning liquid is ejected from the row. As a result, even if liquid enters from the atmosphere communication port, since the liquid is in a state where there is a lot of cleaning liquid, rather than solidification like ink occurs in the downstream side in the flow path from this atmosphere communication port, On the contrary, when there are many washing | cleaning liquids, the solidified body solidified in the past melt | dissolves and it becomes possible to ensure the fluidity | liquidity of a liquid more. For this reason, it is possible to satisfactorily prevent the liquid that has entered from the air communication port from solidifying in the flow passage.

  According to another aspect of the present invention, in the above-described invention, a plurality of first ejection nozzle arrays are provided corresponding to the type of ink, and ink is ejected from each of the plurality of first ejection nozzle arrays. It is preferable that the lower the viscosity is, the shorter the distance between the straight line passing through the first ejection nozzle row and parallel to the ink ejection direction and the air communication port.

  In such a configuration, the first ejection nozzle row is arranged so that the lower the ink viscosity is, the closer to the atmosphere communication port, so that the ink with high viscosity is kept away from the atmosphere communication port. It is done. Thereby, it is possible to satisfactorily prevent high viscosity ink from flowing from the air communication port.

  Furthermore, in another aspect of the present invention, in the above-described invention, it is preferable that a plurality of first ejection nozzle arrays include a first ejection nozzle array that ejects white ink.

  In such a configuration, the liquid present in the vicinity of the atmosphere communication port has a large amount of components of the cleaning liquid. Therefore, the white ink is in the atmosphere downstream of the atmosphere communication port in the flow path. It is possible to satisfactorily prevent solidification by entering from the communication port. In addition, since the white ink is disposed at a position away from the atmosphere communication port among the plurality of first ejection nozzle arrays, it is possible to satisfactorily prevent the white ink having a high viscosity from entering from the atmosphere communication port.

  In addition, according to another aspect of the present invention, in each of the above-described inventions, the ink ejected from at least one first ejection nozzle array of the plurality of first ejection nozzle arrays includes a colorant, water, and an alcohol solvent. And at least a polyglycol solvent, the alcohol solvent preferably contains a hardly water-soluble alkanediol, and the polyglycol solvent preferably contains a polyalkylene glycol.

  In such a configuration, the ink becomes high-viscosity ink. However, when such high-viscosity ink enters from the air communication port, the ink is solidified in the downstream flow passage. However, since the liquid present in the vicinity of the air communication port has a large amount of components of the cleaning liquid, high-viscosity ink enters from the air communication port on the downstream side of the flow channel from the air communication port. It is possible to satisfactorily prevent solidification.

  Furthermore, in another aspect of the present invention, in each of the above-described inventions, the ejection head is controlled and driven by the control unit, and the control mode during maintenance of the control unit is in a state where a sealed space is formed. Alternatively, there is a control mode in which the cleaning liquid is ejected from the second ejection nozzle array at the same time as the ink is ejected from the first ejection nozzle array in a state where the ejection head and the cap face each other even if the sealed space is not formed. It is preferable.

  In such a configuration, the control mode during maintenance of the control unit includes a control mode in which the cleaning liquid is ejected from the second ejection nozzle array at the same time as the ink is ejected from the first ejection nozzle array. . Thus, even in a maintenance operation such as flushing, for example, the cleaning liquid is ejected from the second ejection nozzle, so that the liquid present in the vicinity of the atmosphere communication port is in a state where the cleaning liquid ejected from the second ejection nozzle row is large. Thereby, even if the liquid enters from the air communication port, it is possible to satisfactorily prevent the liquid from solidifying in the flow passage.

  Further, according to another aspect of the present invention, in each of the above-described inventions, the suction means includes a first tube connected to the suction port, an openable / closable discharge valve provided in a middle portion of the first tube, And a suction pump that is provided in the middle of one tube and is further away from the sealed space than the discharge valve, and that drives to apply a negative pressure to the sealed space. It is preferable to include a second tube connected to the mouth, and an air release valve that is provided in the middle of the second tube and is open to the atmosphere.

  In the case of such a configuration, it is possible to satisfactorily prevent the liquid from entering and solidifying inside the second tube.

In addition, a maintenance method according to another aspect of the present invention has a first ejection nozzle row that ejects ink containing a colorant, and ejects a cleaning liquid that can dissolve the colorant contained in the ink. An ejection head having a second ejection nozzle row, and a sealed space is formed in contact with the nozzle formation surface of the ejection head, and ejected from at least one of the first ejection nozzle row and the second ejection nozzle row. A cap for receiving ink and / or cleaning liquid; a suction means for performing suction from the suction port of the sealed space; and an atmosphere opening means for opening the atmosphere from the atmosphere communication port of the sealed space; column, is arranged on the side of the atmosphere communication port than the first discharge nozzle row, the first injection nozzle row and in correspondence with the type of ink provided with a plurality In addition, the lower the viscosity of the ink ejected from each of the plurality of first ejection nozzle rows, the straight line passing through the first ejection nozzle row and parallel to the ink ejection direction and the atmosphere communication The cleaning liquid is also sucked from the second jet nozzle row during a maintenance operation in which the distance from the mouth is short and the ink is sucked or jetted from the first jet nozzle row. Or jetted.

In such a configuration, the second injection nozzle row is disposed closer to the atmosphere communication port than the first injection nozzle row, so that the liquid present in the vicinity of the atmosphere communication port A large amount of cleaning liquid is ejected from the row. Accordingly, during a maintenance operation in which ink is sucked or ejected from the first ejection nozzle row, the cleaning liquid is also sucked or ejected from the second ejection nozzle row, so that the liquid enters from the atmosphere communication port. Even so, the liquid is in a state with a large amount of cleaning liquid. As a result, on the downstream side of the flow path from the air communication port, rather than solidification like ink occurs, conversely, because there is a lot of cleaning liquid, the solidified body solidified in the past melts, ensuring more liquid flowability. It becomes possible to do. For this reason, it is possible to satisfactorily prevent the liquid that has entered from the air communication port from solidifying in the flow passage.

1 is a schematic diagram illustrating a configuration of a printer according to an embodiment of the present invention. It is the schematic which shows the structure of the line head in the printer of FIG. It is the schematic which shows the structure of a short head and a suction mechanism. It is a figure which shows the positional relationship of a nozzle and an atmosphere communicating port. It is a figure which shows the processing flow in case a suction pump act | operates. It is a figure which shows the state in which the liquid has accumulated by the curve of the 2nd tube. It is a figure which shows the state with less liquid than the case shown in FIG.

  Hereinafter, a printer 10 as a liquid ejecting apparatus according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 7.

<Schematic configuration of printer>
First, an outline of the configuration of the printer 10 will be described. FIG. 1 is a diagram illustrating a schematic configuration of a printer 10 according to an embodiment of the present invention. The printer 10 includes a paper feed mechanism 20, an ink supply mechanism 30, a line head 40, a suction mechanism 50, and a control unit 70.

  The paper feed mechanism 20 includes a paper feed motor (PF motor) 21 and a paper feed roller 22 to which the driving force from the paper feed motor 21 is transmitted, and supplies a print medium P such as print paper. It can be conveyed from the part toward the paper discharge side. The ink supply mechanism 30 includes a cartridge holder 31, a cartridge 32, and an ink supply path 33. Among these, a cartridge 32 is detachably attached to the cartridge holder 31. Therefore, the printer 10 of the present embodiment has a so-called off-carriage type configuration. Here, the cartridge 32 includes a cartridge 32 a that stores ink for forming a print image by being ejected onto the print medium P during printing, and a cartridge 32 b that stores the cleaning liquid to be ejected to the cap 51. When there is no need to distinguish between the cartridge 32a and the cartridge 32b, both are referred to as the cartridge 32.

  An ink supply path 33 is provided between the cartridge 32 and the line head 40. Through this ink supply path 33, it is possible to supply ink from the cartridge 32 a to the line head 40 and to supply cleaning liquid from the cartridge 32 b to the line head 40.

  Further, the line head 40 has a width dimension wider than that of the print medium P. As shown in FIG. 2, the line head 40 has a plurality of short heads (corresponding to an example of an ejection head) 41 that alternately move back and forth in the sub-scanning direction (Y direction; a direction orthogonal to the line direction). They are arranged along the direction (X direction; line direction). Further, as shown in FIG. 1, in each short head 41, nozzles 42 as ink ejection locations are arranged in a row in a direction orthogonal to the transport direction of the print medium P (width direction of the print medium P). Yes.

  Here, each short head 41 has a region overlapping with the nozzle 42 of the adjacent short head 41 in the line direction (X direction). Further, the short head 41 constitutes a nozzle row 43 by the nozzles 42 forming a row in the line direction (X direction). A nozzle row 43 (hereinafter referred to as a nozzle row 43a) that ejects cyan, magenta, yellow, and black colored ink (printing ink) is applied to the nozzle row 43; the nozzle row 43a is a first nozzle row 43a. (Corresponding to an example of the injection nozzle row). In addition, the surface in which the nozzle row | line | column 43 is provided among the short heads 41 is called the nozzle formation surface 41a.

  The ink has a higher viscosity than the cleaning liquid described later. Among such inks, an ink having a higher viscosity than that of a normal printing ink may be used. In addition, the high viscosity said by this application means a viscosity in the range whose viscosity of the ink at the time of use is 5 mPa * s or more and 15 mPa * s or less. Such high viscosity ink will be described later.

  In addition, as the above-described ink, white ink having a higher viscosity than other color inks may be used. When white ink with high viscosity is used, a cartridge 32 for storing high-viscosity white ink is provided, and some nozzle rows 43a eject high-viscosity white ink.

  The nozzle row 43 is provided with a nozzle row 43b that ejects a cleaning liquid instead of the printing ink described above. In the present embodiment, the nozzle row 43b that ejects the cleaning liquid is provided so as to be positioned on one end side of the cap 51 described later. That is, the cleaning liquid is supplied from the cartridge 32 b to the nozzles 42 existing in the nozzle row 43 b through the ink supply path 33, and the cleaning liquid is ejected from the nozzles 42. The ejected cleaning liquid is landed on a portion of the ink absorber 52 located in the vicinity of the atmosphere communication port 512 in the cap 51. The nozzle row 43b corresponds to an example of a second injection nozzle row.

  In the following description, the nozzles 42 present in the nozzle row 43a that ejects printing ink are referred to as nozzles 42a. The nozzles 42 present in the nozzle row 43b that ejects the cleaning liquid are referred to as nozzles 42b. The nozzle row 43a described above is not limited to four colors, and may have any number of colors such as six colors, seven colors, and eight colors.

<About cleaning solution>
Further, as the cleaning liquid supplied from the cartridge 32b into the cap 51, a solution that dissolves the colorant used in the ink is used.

  When the ink is a water-based ink, it is preferable to use a liquid containing a water-soluble low-volatile organic solvent and a surfactant as the cleaning liquid. Examples of the organic solvent used in the aqueous ink include glycol compounds such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and dipropylene glycol. For example, when the water-based ink contains ethylene glycol, ethylene glycol is also used for the cleaning liquid. As a result, when the cap 51 is cleaned, it mixes with the color material of the water-based ink, and the cleaning effect increases, and solidification of the ink color material due to drying of the solvent in the cap 51 can be prevented. Furthermore, the cleaning effect can be further increased by adding about 1% by weight of a surfactant.

  When the ink is an oil-based ink, it is preferable to use a liquid containing an oily low-volatile organic solvent as the cleaning liquid. The organic solvent used in the oil-based ink is preferably a polar organic solvent, for example, alcohols (for example, methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, or fluorinated alcohol), ketones (for example, acetone, methyl ethyl ketone) Or cyclohexanone), carboxylic acid esters (eg, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, or ethyl propionate), or ethers (eg, diethyl ether, dipropyl ether, tetrahydrofuran) Or dioxane etc.).

  For example, when diethyl ether contains oil-based ink, diethyl ether is also used for the cleaning liquid. As a result, when the inside of the cap 51 is cleaned, it mixes with the color material of the oil-based ink, and the cleaning effect is increased, and solidification of the ink color material due to drying of the solvent in the cap 51 can be prevented.

<Configuration of suction mechanism>
Next, the configuration of the suction mechanism 50 will be described with reference to FIG. The printer 10 is provided with a suction mechanism 50 as shown in FIG. The suction mechanism 50 includes a cap 51, an ink absorber 52, a first tube 53, a waste liquid tank 54, a discharge valve 55, a suction pump 56, a second tube 57, a waste liquid receiver 58, and an air release valve. 59. The first tube 53, the discharge valve 55, and the suction pump 56 constitute suction means, and the second tube 57 and the atmosphere release valve 59 constitute atmosphere release means.

  Among these, the cap 51 is a portion that seals the nozzle forming surface 41 a of the short head 41 from the outside, but the recess 51 a that is a portion sealed from the outside communicates with the first tube 53. A portion where the first tube 53 is attached to the cap 51 serves as a suction port 511 and protrudes from the bottom of the recess 51a toward the side opposite to the opening side of the recess 51a. The pipe-like portion of the suction port 511 is connected by being inserted into one end side of the first tube 53.

  The cap 51 is provided with an air communication port 512 together with the suction port 511 described above. Similarly to the suction port 511 described above, the atmosphere communication port 512 protrudes from the bottom of the recess 51a toward the side opposite to the opening side of the recess 51a. The pipe-like portion of the atmosphere communication port 512 is connected by being inserted into the second tube 57 or the like. Here, as shown in FIG. 3, the suction port 511 is a part where the ink ejected from the nozzle 42a lands in the ink absorber 52 in the recess 51a rather than the part where the cleaning liquid ejected from the nozzle 42b lands. It is provided so that is closer.

  In addition, as shown in FIG. 3, the air communication port 512 is closer to the portion where the cleaning liquid ejected from the nozzle 42b lands in the recess 51a than the portion where the ink ejected from the nozzle 42a lands. It is provided as follows.

  Due to the positional relationship between the suction port 511 and the atmosphere communication port 512, when the cleaning liquid is ejected together with the ink to the ink absorber 52 in the concave portion 51a, the atmosphere communication port 512 has a large amount of cleaning liquid. Therefore, even if the liquid enters from the atmosphere communication port 512, it becomes possible to make the cleaning liquid in the liquid a lot.

  FIG. 4 shows a positional relationship between the nozzle rows 43a and 43b and the atmosphere communication port 512. As shown in FIG. 4, in the nozzle row 43a, straight lines X1 to Xn that pass through the nozzle row 43a and are parallel to the ink ejection direction, and the atmosphere communication port 512 (center line P of the atmosphere communication port 512). The distances L1 to Ln are set closer to each other as the viscosity of the ejected ink is lower. That is, the values of the distances L1 to Ln are smaller as the ink viscosity is lower (in FIG. 4, the distances are L1, L2,..., Ln in order from the smallest distance). . Further, since the viscosity of the cleaning liquid is lower than that of the ink, the distance M between the straight line Y passing through the nozzle row 43b and parallel to the cleaning liquid ejection direction and the atmosphere communication port 512 is the above-described distances L1 to Ln. It is smaller than either value. Here, the straight line Y preferably passes through the atmosphere communication port 512, and the distance M is preferably equal to or smaller than the radius of the opening portion of the atmosphere communication port 512 or smaller than the radius.

  In the present embodiment, as shown in FIG. 3, an ink absorber 52 is provided in the recess 51 a of the cap 51. The ink absorber 52 is formed of a nonwoven fabric such as felt, for example, and can absorb ink.

  The first tube 53 is a flexible hollow tube member, and the hollow portion serves as a flow path connecting the recess 51 a and the waste liquid tank 54.

  The waste liquid tank 54 is a container for storing ink discharged by the operation of the suction pump 56 or the like. The discharge valve 55 is a valve that is provided in the middle of the first tube 53 and that can be electrically controlled. In the opened state, the ink (or cleaning liquid or a mixture thereof) in the first tube 53 is provided. In the first tube 53 in the valve closed state. The suction pump 56 is provided so as to be able to generate a negative pressure in the first tube 53. When the suction pump 56 is operated, the ink (or the cleaning liquid or a mixture thereof) is passed through the first tube 53. Liquid) is discharged to the waste liquid tank 54.

  Similarly to the first tube 53 described above, the second tube 57 is a flexible hollow tube member, and the hollow portion serves as a flow path connecting the recess 51 a and the waste liquid tank 54. . Note that the atmospheric communication port 512 is connected to one end side of the second tube 57, for example. Further, a waste liquid receiver 58 similar to the waste liquid tank 54 is provided on the other end side of the second tube 57 so that the liquid flowing through the second tube 57 can be received. However, in view of the fact that the amount of liquid flowing through the second tube 57 is not so large, the waste liquid receiver 58 may not be provided on the other end side of the second tube 57.

  The air release valve 59 is a valve that is provided in the middle of the second tube 57 and can be electrically controlled. In the opened state, the air release valve 59 is provided in the recess 51a (sealed space) via the second tube 57. While the atmosphere can be released, the atmosphere cannot be released through the second tube 57 in the closed state.

<Configuration of control unit>
Then, the structure of the control part 70 is demonstrated based on FIG. The control unit 70 includes a CPU (not shown), a memory (ROM, RAM, nonvolatile memory, etc.), an ASIC (Application Specific Integrated Circuit), a bus, a timer, an interface 72 (see FIG. 1), and the like.

  Signals from various sensors are input to the control unit 70. Based on the signals from the sensors, the control unit 70 performs the PF motor 21, the short head 41 (line head 40), the discharge valve 55, and the suction valve. Controls driving of the pump 56, the air release valve 59, and the like.

  By the drive control by the control unit 70, the suction mechanism 50 can execute a sequence as described later. Further, the control unit 70 according to the present embodiment can execute a maintenance control mode in which ink is ejected regardless of printing. Here, in the control mode during maintenance, the cap 51 is in contact with the nozzle forming surface 41a to form a sealed space, or the short head 41 and the cap 51 are not formed even if a sealed space is formed. In some cases, the cleaning liquid is ejected from the nozzle row 43b at the same time as the ink is ejected from the nozzle row 43a. Such a control mode during maintenance is executed by the cooperation of the components of the control unit 70 described above and the programs and data stored in the ROM or nonvolatile memory.

  The control unit 70 described above is connected to the computer 100 via the connector 71 and performs communication. Accordingly, when the printer 10 receives the print signal PS from the computer 100 side, the printer 10 starts processing for printing based on the print signal PS.

<Regarding high viscosity ink components>
Next, the components of the highly viscous ink used in the present embodiment will be described. The ink composition (ink composition) in the present embodiment is an ink composition for ink jet recording comprising at least a colorant, water, an alcohol solvent, and a polyglycol solvent, wherein the alcohol solvent is And a slightly water-soluble alkanediol, and the polyglycol solvent comprises a polyalkylene glycol. Hereinafter, each component will be described.

<Definition>
In the present embodiment, the alkanediol may be either a straight chain or a branched chain.

  Water-soluble means that the solubility in water at 20 ° C. (the amount of solute with respect to 100 g of water) is 10.0 g or more, and poorly water-soluble means the solubility in water (100 g of water). It means that the amount of solute relative to 1.0 g is less than 1.0 g. The miscibility means a translucent solution when the solubility in water (the amount of solute with respect to 100 g of water) at 20 ° C. is 10.0 g.

  The alcohol solvent used in the ink composition in the present embodiment contains at least two kinds of organic solvents containing a hardly water-soluble alkanediol and the polyglycol solvent containing a polyalkylene glycol. By including these two types of organic solvents as essential components, beading of the ink composition is suppressed on printing paper, and high-quality images without bleeding or beading can be realized even when printing at low resolution. In addition, an ink composition having excellent ejection stability can be realized. In the present embodiment, beading is a local similar color that occurs when printing as a surface (for example, printing in a single color (not the number of ink colors) on a 6-inch square). It means density spots, and does not mean that a portion of the print medium surface that is not covered with ink remains. Color material bleeding is a phenomenon in which mixed colors are generated in the vicinity of a boundary line when each single color is printed as an adjacent surface (for example, when each single color is printed as an adjacent surface in 3 inches square). means. In addition, solvent bleeding refers to the movement of coloring material due to solvent bleed in the vicinity of the boundary line when each single color is printed as an adjacent surface (for example, when each single color is printed as an adjacent surface in 3 inches square). Means a phenomenon in which the coating state changes and density spots of similar colors occur.

In the present embodiment, when the printing medium as described above uses thin printing paper having a basis weight of 73.3 to 104.7 g / m ² or 104.7 to 209.2 g / m ^2. Even when thin printing paper having a US basis weight of 73.3 to 104.7 g / m ² is used, it is possible to suppress the occurrence of so-called curling, in which the printing surface warps inward.

  As described above, the reason why a high-quality image without bleeding or beading can be realized by adding polyalkylene glycol as an essential component in addition to poorly water-soluble alkanediol is not clear, but as follows Conceivable.

  Ink beading that occurs when recording on printing paper has high surface tension of the ink dots, resulting in a high contact angle between the printing paper surface and the ink droplets, and the ink droplets are repelled on the printing paper. This is considered to be the cause. The repelled ink droplets mutually flow and combine with adjacent ink droplets, so that beading occurs. Therefore, to suppress ink beading, it is considered preferable to reduce the surface tension of the ink droplets and suppress the fluidity of the ink droplets.

  Ink bleeding that occurs when recording on printing paper is different in surface tension of ink dots, so that ink dots with low surface tension attached to the surface of printing paper wet out and spread over ink dots with high surface tension, It is considered that the cause is that the ink flows. This ink flow is considered to be affected by the difference in the adhesion time between adjacent ink dots, the size of the droplet at the time of adhesion, and the like.

  Therefore, in order to suppress ink bleeding, it is considered preferable that the surface tensions of the respective ink droplets are all the same. However, since it is difficult to make the difference in adhesion time between adjacent ink droplets and the size of the droplets at the time of adhesion difficult, it is considered preferable to reduce the fluidity of the ink droplets.

  Therefore, in order to realize a high-quality image without ink beading and bleeding, it is considered preferable to adhere ink dots having low surface tension and low fluidity to the printing paper.

<Polyglycol solvent>
The ink composition in the present embodiment comprises polyalkylene glycol as a polyglycol solvent. Preferably, in order to further suppress aggregation, a water-miscible polyalkylene glycol may be contained.

  The reason why the aggregation is suppressed is not clear, but it is considered that the water-miscible polyalkylene glycol separates the hardly water-soluble alkanediol into a fine oil layer in the ink droplet drying process. In such a separation layer, a pigment that is dispersed by a water-dispersible dispersion resin exists in the water layer, but cannot exist in the oil layer. It is considered that the flow of the pigment in the water layer is suppressed by the wall of the oil layer. Innumerable fine oil droplets are considered to suppress the fluidity of water.

  The moment when the ink is deposited is still in a state where oil droplets are dispersed in water, but in the drying process, water is lost first, and it is considered that the layer transitions from O / W to W / O. Therefore, it is considered that the fluidity of the entire ink droplet is lost instantly.

  The polyalkylene glycol contained in the ink composition in the present embodiment is not particularly limited, but is preferably polypropylene glycol. The polypropylene glycol is not particularly limited, but is preferably a diol type from the viewpoint of ecotoxicity and environmental toxicity. Further, the weight average molecular weight of the polypropylene glycol is not particularly limited, but from the viewpoint of separating the hardly water-soluble alkanediol from the aqueous layer, the weight average molecular weight is preferably 400 to 700, and preferably 400. More preferable.

  Since the polyglycol solvent contained in the ink composition in the present embodiment is difficult to dry even when left at high temperature and low humidity, clogging recovery at 50 ° C./15% HM is improved.

  The polyalkylene glycol in the present embodiment is preferably contained in an amount of 4 to 10% by weight, more preferably 5 to 8% by weight, based on the entire ink composition. The content of 4% by weight or more is preferable because the poorly water-soluble alkanediol can be favorably separated into the oil layer in the ink droplet drying step. On the other hand, when the content is 10% by weight or less, the initial viscosity of the ink does not become too high, and separation into an oil layer can be effectively prevented in a normal ink storage state, which is preferable from the viewpoint of ink storage stability.

<Alcohol solvent>
The ink composition in the present embodiment comprises a slightly water-soluble alkanediol as an alcohol solvent.

  The slightly water-soluble alkanediol in the present embodiment is preferably an alkanediol having 7 or more carbon atoms, more preferably an alkanediol having 7 to 10 carbon atoms. More preferably, it is a poorly water-soluble 1,2-alkanediol and can suppress beading. Examples of the slightly water-soluble 1,2-alkanediol include 1,2-heptanediol, 1,2-octanediol, 5-methyl-1,2-hexanediol, and 4-methyl-1,2-hexanediol. Or 4,4-dimethyl-1,2-pentanediol. Among these, 1,2-octanediol is more preferable. The reason why the beading can be suppressed is not clear, but it is considered that the beading can be suppressed by reducing the surface tension of the ink droplet.

  The slightly water-soluble alkanediol in the present embodiment is preferably contained in an amount of 1 to 4% by weight, more preferably 2 to 4% by weight, and still more preferably 2.5%, based on the entire ink composition. -3.5 wt%. By controlling the amount to 1% by weight or more, it is possible to sufficiently suppress the occurrence of beading. On the other hand, by setting it to 4% by weight or less, the initial viscosity of the ink does not become too high, and the normal ink storage state Can be effectively prevented from separating into an oil layer, which is preferable from the viewpoint of ink storage stability.

  In addition to the hardly water-soluble alkanediol and polyalkylene glycol which are essential components, the occurrence of solvent bleeding can be further suppressed by adding a symmetrical double-terminal alkanediol. The reason is not clear, but is considered as follows.

  Since the poorly water-soluble alkanediol has extremely low surface tension and low evaporability, it is considered that the ink solution continues to spread even after the movement of the coloring material stops. Therefore, in the case of a recorded image having a distribution in which the difference in ink adhesion amount per unit area is large, the solvent oozes out from a portion with a large ink adhesion amount to a portion with a small ink adhesion amount. In order to suppress the bleeding of such a solvent, it is preferable to add a target type both-end alkanediol having a high surface tension.

  If the content of this symmetrical both-end alkanediol is too small, the bleeding of the solvent may not be further suppressed in the case of a recorded image having a distribution with a large difference in the ink adhesion amount. Moreover, when there is too much content of symmetrical type both terminal alkanediol, a slightly water-soluble alkanediol will melt | dissolve too much and beading may not be suppressed further. Although the reason is not clear, since the symmetrical both-end alkanediol has a high ability to dissolve the hardly water-soluble alkanediol and the polyalkylene glycol, the water-miscible polyalkylene glycol is used in the ink droplet drying process. This is considered to inhibit separation of the slightly water-soluble alkanediol into a fine oil layer.

  The water-soluble symmetrical both-end alkanediol in the present embodiment is preferably contained in an amount of 0.1 to 4% by weight, more preferably 0.6 to 1.4% by weight based on the entire ink composition. %. When the content is 0.1% by weight or more, the injection stability can be made sufficient, and the wiping durability does not deteriorate, which is preferable. The wiping performance means deterioration in landing accuracy of ink droplets caused by water repellency deterioration on the peripheral surface of the ink nozzle, which occurs when the cleaning operation is repeatedly performed. Although the reason is not clear, it is considered that the hardly water-soluble alkanediol and the polyalkylene glycol are deposited on the peripheral surface of the ink nozzle. On the other hand, the content of 4% by weight or less is preferable because the slightly water-soluble alkanediol and polyalkylene glycol are not excessively dissolved.

  The water-soluble symmetrical both-end alkanediol used in the present embodiment is a permeable wetting agent that exhibits a lower surface tension than glycerin. For example, the surface tension of 1,6-hexanediol in a 10% aqueous solution is 41.5 mN / m, and the surface tension of 2-methyl-1,3-propanediol in a 10% aqueous solution is The surface tension of 3-methyl-1,5-butanediol in the case of a 10% aqueous solution is 45.8 mN / m.

  In addition, the water-soluble symmetrical both-end alkanediol in the present embodiment is preferably an alkanediol having 3 or more carbon atoms in the main chain, more preferably 4 to 6 carbon atoms in the main chain. Further, the water-soluble symmetrical both-end alkanediol may have a branched chain. In the present specification, “symmetric type” means that in an alkanediol having hydroxyl groups at both ends of an alkyl chain, carbon that is equidistant from both hydroxyl groups, such as 1,5-pentanediol, is the axis of symmetry. , Means both terminal alkanediols. As the water-soluble symmetrical both-end alkanediol in the present embodiment, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 1,5-pentanediol, 1, 6-hexanediol. Among these, from the viewpoint of jetting stability, a water-soluble symmetrical both-end alkanediol having a large number of carbon atoms is preferably used. Water-soluble symmetrical both-end alkanediols having 6 carbon atoms, such as 3-methyl-1,5-pentanediol and 1,6-hexanediol, are excellent in the ability to dissolve poorly water-soluble alkanediols in water. Therefore, the injection stability is improved.

  In particular, 1,6-hexanediol is more preferable because it is easily soluble in water and solid at room temperature, and thus has excellent ability to recover from clogging. Although the reason is not clear, when the solid ink near the nozzle contains solid 1,6-hexanediol which is easily soluble in water, when the liquid ink comes into contact with the liquid ink by the cleaning operation, 1,6 -It is considered that dissolution of hexanediol is a trigger for recovery from clogging.

  In the alcohol solvent and the polyglycol solvent in the present embodiment, the content ratio of the water-soluble symmetrical both-end alkanediol and the polyalkylene glycol is preferably 1: 1 to 1: 100. By setting it within this range, the polyalkylene glycol having a weight average molecular weight of 2000 or less can be stably dissolved in the ink, and the jetting stability is improved. When the ratio of the water-soluble symmetrical both-end alkanediol is larger than the above range, it is difficult to reduce the initial ink viscosity and beading spots. On the other hand, if the ratio of the water-miscible water-soluble symmetrical both-end alkanediol is less than the above range, it will be difficult to stably dissolve the polyalkylene glycol in the ink, and the viscosity change during the course will be suppressed. It becomes difficult to maintain the storage stability. Moreover, wiping durability deteriorates.

  Within the above range, when the proportion of the water-soluble symmetrical both-end alkanediol is small, the molecular weight of the polyalkylene glycol is more preferably 700 or less from the viewpoint of wiping durability.

  In addition, the content ratio of the water-soluble symmetrical both-end alkanediol and the slightly water-soluble alkanediol in the present embodiment is preferably 1:80 to 4: 1, more preferably 1: 40-2: 1. By setting this range, the ink ejection stability can be improved. If the ratio of the water-soluble symmetrical both-end alkanediol is larger than the above range, the ink initial viscosity becomes high and it becomes difficult to reduce beading spots. On the other hand, if the ratio of the water-soluble symmetric type both-end alkanediol is less than the above range, it becomes difficult to stably dissolve the poorly water-soluble alkanediol in the ink, and the viscosity change at the time can be suppressed or stored. It becomes difficult to maintain stability. Moreover, wiping durability improves by making content ratio of the water-soluble symmetrical both terminal alkanediol and the poorly water-soluble alkanediol in this Embodiment into the said range.

  Furthermore, the content ratio of the slightly water-soluble alkanediol and the polyalkylene glycol in the present embodiment is preferably 1: 1 to 1:10, more preferably 1: 1 to 1: 5, respectively. is there. By setting this range, the ink ejection stability can be improved.

  Further, when the symmetrical double-end alkanediol is X, the slightly water-soluble alkanediol is Y, and the polyalkylene glycol is Z, the content ratio is X: (Y + Z) = 1: 140-4: 5 is preferred. By setting it within this range, it is possible to ensure injection stability, storage stability, and wiping durability. Although the reason is not clear, it is thought that water can be lost first in the drying process and a mechanism of layer transition from O / W to W / O can be developed. When the ratio of poorly water-soluble alkanediol is large within the above range and in the range of X: Y = 1: 80 to 4: 1, the molecular weight of the polyalkylene glycol may be 700 or less. From the viewpoint of wiping durability, it is more preferable.

  Such a layer transition is considered to occur because, in the drying process, low molecular weight water is dried immediately, but the slightly water-soluble alkanediol and polyalkylene glycol remain without being dried. The resin adsorbed on the pigment is thought to change from a dispersed state excellent in fluidity to a highly viscous resin in an agglomerated state because water is rapidly lost and at the same time left in the oil layer.

  Further, the sum of the contents of the slightly water-soluble alkanediol and the polyalkylene glycol in the present embodiment is preferably 14% by weight or less based on the ink composition. By setting it within this range, the initial viscosity of the ink can be kept low, and it is excellent in color material bleeding without causing beading in a print medium having low ink absorption such as printing paper.

  In the present embodiment, the sum of the contents of the slightly water-soluble alkanediol, the polyalkylene glycol, and the water-soluble symmetrical both-end alkanediol is 18% by weight or less based on the ink composition. It is preferable. By setting this range, the initial viscosity of the ink can be kept low, and beading spots do not occur on printing media with low ink absorption, such as printing paper, and not only color material bleeding but also solvent bleeding. Excellent. In particular, since it is excellent in solvent bleeding, it has almost no ability to absorb water and has excellent recordability on synthetic paper.

  The alcohol solvent in the present embodiment preferably further comprises 0.1 to 4% by weight of 1,2-hexanediol. By including 0.1 to 4% by weight of 1,2-hexanediol, it is possible to realize a high-quality image without bleeding or beading. Further, it is effective as a regulator when the jetting performance varies depending on the pigment type and the resin amount.

  Moreover, it is preferable that 0.1-4 weight% of 4-methyl- 1, 2-pentanediol is further included as an alcohol solvent in this Embodiment. By including 0.1 to 4% by weight of 1,2-hexanediol, it is possible to realize a high-quality image without bleeding or beading. Further, it is effective as a regulator when the jetting performance varies depending on the pigment type and the resin amount.

<Colorant>
As the coloring material (coloring agent) used in the ink composition for ink jet recording in the present embodiment, both dyes and pigments can be used, but pigments can be preferably used from the viewpoint of light resistance and water resistance. .

  As the pigment, inorganic pigments and organic pigments can be used, and each can be used alone or in combination. As the inorganic pigment, for example, in addition to titanium oxide and iron oxide, carbon black produced by a known method such as a contact method, a furnace method, or a thermal method can be used. Examples of the organic pigment include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments), polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, Dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinofullerone pigments, etc.), dye chelates (for example, basic dye-type chelates, acidic dye-type chelates), nitro pigments, nitroso pigments, aniline black, and the like can be used.

  Specific examples of the pigment are appropriately given according to the type (color) of the ink composition to be obtained. For example, as a pigment for a yellow ink composition, C.I. I. Pigment Yellow 1, 2, 3, 12, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 128, 129, 138, 139, 147, 150, 151, 154, 155, 180, 185 and the like, and one or more of these are used. Of these, C.I. I. It is preferable to use one or more selected from the group consisting of CI Pigment Yellow 74, 110, 128, and 129. Examples of the pigment for the magenta ink composition include C.I. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 122, 123, 168, 184, 202, 209; I. Pigment violet 19 or the like, and one or more of these may be used. Of these, C.I. I. Pigment red 122, 202, 209, and C.I. I. It is preferable to use 1 type, or 2 or more types selected from the group consisting of Pigment Violet 19, and these may be solid solutions. Examples of the pigment for the cyan ink composition include C.I. I. Pigment Blue 1, 2, 3, 15: 3, 15: 4, 15:34, 16, 22, 60; I. Vat Blue 4, 60 and the like are listed, and one or more of these are used. Of these, C.I. I. Pigment Blue 15: 3 and / or 15: 4 are preferably used, especially C.I. I. Pigment Blue 15: 3 is preferably used.

  Examples of the pigment for the black ink composition include lamp black (CI pigment black 6), acetylene black, furnace black (CI pigment black 7), and channel black (CI pigment black). 7), carbon blacks such as carbon black (CI Pigment Black 7), inorganic pigments such as iron oxide pigments, and organic pigments such as aniline black (CI Pigment Black 1). In this form, carbon black is preferably used. Specifically, as carbon black, # 2650, # 2600, # 2300, # 2200, # 1000, # 980, # 970, # 966, # 960, # 950, # 900, # 850, MCF-88, # 55, # 52, # 47, # 45, # 45L, # 44, # 33, # 32, # 30 (above, manufactured by Mitsubishi Chemical Corporation), SpecialBlaek4A, 550, Printex95, 90, 85, 80, 75 , 45, 40 (above, manufactured by Degussa), Regal660, RmogulL, monarch1400, 1300, 1100, 800, 900 (above, manufactured by Cabot), Raven7000, 5750, 5250, 3500, 3500, 2500 ULTRA, 2000, 1500, 1255 , 1200, 1190 ULTRA, 1170, 1100 ULTRA, Raven5000UIII (above, Colombian) and the like.

  The concentration of the pigment is not particularly limited because it may be adjusted to an appropriate pigment concentration (content) when the ink composition is prepared, but in the present embodiment, the solid content concentration of the pigment is 7% by weight or more. It is preferable to make it 10% by weight or more. When ink droplets adhere to the print medium, the ink wets and spreads on the surface of the print medium, but by increasing the pigment solid concentration to 7% by weight or more, the fluidity of the ink after the wet spread stays early. Therefore, when printing is performed on a printing medium such as printing paper at a low resolution, bleeding can be further suppressed. That is, by using a combination of the above two specific organic solvents, the ink spreads even on a print medium with low ink absorbency, and at the same time, by increasing the solid content concentration of the ink, It is considered that bleeding of ink can be suppressed by reducing the fluidity of ink. In particular, when the weight of one ink droplet is 6 ng or more, the effect of suppressing beading and bleeding is significant.

  The pigment is a pigment that has been kneaded with a dispersant, which will be described later, to achieve both the glossiness of the image, the prevention of bronzing, and the storage stability of the ink composition, and to form a color image that is further excellent in glossiness. From the viewpoint of being able to.

<Dispersant>
In the ink composition of the present embodiment, the dispersant for dispersing the colorant is selected from the group consisting of styrene-acrylic acid copolymer resins, oxyethyl acrylate resins, urethane resins, and fluorene resins. It is preferable that at least one resin selected from the group consisting of an oxyethyl acrylate resin and a fluorene resin is included. These copolymer resins are adsorbed on the pigment to improve dispersibility.

  Specific examples of the hydrophobic monomer in the copolymer resin include, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, iso-propyl acrylate, iso-propyl methacrylate, n- Butyl acrylate, n-butyl methacrylate, sec-butyl acrylate, sec-butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate, n-octyl acrylate, n-octyl methacrylate, iso- Octyl acrylate, iso-octyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, Sil acrylate, decyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-dimethylaminoethyl acrylate, 2 -Dimethylaminoethyl methacrylate, 2-diethylaminoethyl acrylate, 2-diethylaminoethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, allyl acrylate, allyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, phenyl acrylate, phenyl methacrylate, nonyl phenyl acrylate, noni Phenyl methacrylate, benzyl acrylate, benzyl methacrylate, dicyclopentenyl acrylate, dicyclopentenyl methacrylate, bornyl acrylate, bornyl methacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,4-butane Diol diacrylate, 1,4-butanediol dimethacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetra Ethylene glycol dimethacrylate, polyethylene glycol di Acrylate, polyethylene glycol dimethacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, dipropylene glycol diacrylate, dipropylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylol Mention may be made of methylolpropane trimethacrylate, glycerol acrylate, glycerol methacrylate, styrene, methylstyrene, vinyltoluene, hydroxyethylated orthophenylphenol acrylate and the like. You may use these individually or in mixture of 2 or more types.

  Specific examples of the hydrophilic monomer include acrylic acid, methacrylic acid, maleic acid, itaconic acid and the like.

  From the viewpoint that the copolymer resin of the hydrophobic monomer and the hydrophilic monomer can form a color image having both glossiness of the color image, prevention of bronzing, and storage stability of the ink composition and excellent glossiness. , Styrene- (meth) acrylic acid copolymer resin, styrene-methylstyrene- (meth) acrylic acid copolymer resin, or styrene-maleic acid copolymer resin, (meth) acrylic acid- (meth) acrylic acid ester copolymer resin Or a styrene- (meth) acrylic acid- (meth) acrylic acid ester copolymer resin or a hydroxyethylated orthophenylphenol acrylic acid ester- (meth) acrylic acid copolymer resin.

  The copolymer resin may be a resin (styrene-acrylic acid resin) containing a polymer obtained by reacting styrene with acrylic acid or an ester of acrylic acid. Alternatively, the copolymer resin may be an acrylic acid-based water-soluble resin. Alternatively, salts thereof such as sodium, potassium, ammonium, triethanolamine, triisopropanolamine, triethylamine, and diethanolamine may be used.

  The acid value of the copolymer resin is preferably 50 to 320 from the viewpoint of achieving both color image glossiness, bronzing prevention, and storage stability of the ink composition, and forming a color image having further excellent glossiness. More preferably, it is 100-250.

  The weight-average molecular weight (Mw) of the copolymer resin is preferable from the viewpoint of achieving a color image having both glossiness of a color image, prevention of bronzing, and storage stability of the ink composition and excellent glossiness. Is from 2,000 to 30,000, more preferably from 2,000 to 20,000.

  The glass transition temperature (Tg; measured in accordance with JISK6900) of the copolymer resin is a viewpoint capable of forming a color image having both glossiness of a color image, prevention of bronzing, and storage stability of the ink composition and excellent glossiness. Is preferably 30 ° C. or higher, more preferably 50 to 130 ° C.

  The copolymer resin may be adsorbed to the pigment in the pigment dispersion or may be free, and achieves both glossiness of the color image, prevention of bronzing, and storage stability of the ink composition. From the viewpoint of forming a color image with further excellent gloss, the copolymer resin preferably has a maximum particle size of 0.3 μm or less, and an average particle size of 0.2 μm or less (more preferably 0.1 μm or less). ) Is more preferable. The average particle diameter is an average value of the dispersion diameter (cumulative 50% diameter) as the particles actually formed in the dispersion liquid. For example, Microtrac UPA (Microtrac Inc.) is used. Can be measured.

  The content of the copolymer resin is 100 parts by weight of the pigment from the viewpoint of achieving both color image glossiness, bronzing prevention, and storage stability of the ink composition and at the same time forming a more glossy color image. The amount is preferably 20 to 50 parts by weight, and more preferably 20 to 40 parts by weight.

  In the present embodiment, an oxyethyl acrylate resin can be used as the copolymer resin. The use is more preferable because it reduces the initial viscosity of the ink, is excellent in storage stability at high temperatures, and is excellent in clogging recovery.

  The oxyethyl acrylate resin is not particularly limited, but is preferably a compound represented by the following formula (I). The compound represented by the following formula (I) is, for example, CAS No. 7-2009-86-0 ortho-hydroxyethylated phenylphenol acrylate, 45-55%, CAS No. CAS No. 79-10-7 acrylic acid 20-30%. Resins containing 20-30% of 79-41-4 methacrylic acid. These may be used alone or in admixture of two or more. The monomer composition ratio is not particularly limited, but preferably CAS No. 7-2009-86-0 ortho-hydroxyethylated phenylphenol acrylate, 70-85%, CAS No. 79-10-7 acrylic acid 5-15%, CAS No. 79-41-4 methacrylic acid is 10-20%.

（Ｒ１および/またはＲ３は水素原子またはメチル基であって、Ｒ２はアルキル基またはアリール基である。ｎは１以上の整数である。）

(R1 and / or R3 is a hydrogen atom or a methyl group, R2 is an alkyl group or an aryl group. N is an integer of 1 or more.)

  The compound represented by the above formula (I) is preferably nonylphenoxy polyethylene glycol acrylate or polypropylene glycol # 700 acrylate.

  From the viewpoint that the content of the oxyethyl acrylate-based resin is compatible with the initial viscosity of the ink composition and the storage stability of the ink composition, suppresses aggregation spots, and can form a color image having excellent filling properties. Preferably it is 10-40 weight part with respect to 100 weight part of said pigments, More preferably, it is 15-25 weight part.

  The total of the resin composition ratio derived from the monomer having a hydroxyl group selected from the group of acrylic acid and methacrylic acid in the oxyethyl acrylate resin is compatible with the initial viscosity of the ink composition and the storage stability of the ink composition, From the viewpoint of clogging recovery, it is preferably 30 to 70%, more preferably 40 to 60%.

  The number average molecular weight (Mn) before crosslinking of the oxyethyl acrylate resin is preferably 4000 to 9000, more preferably from the viewpoint of achieving both the initial viscosity of the ink composition and the storage stability of the ink composition. 5000 to 8000. Mn is measured by, for example, GPC (gel permeation chromatography).

  The oxyethyl acrylate-based resin may be adsorbed to the pigment in the pigment dispersion or may be liberated, achieving both color image gloss, bronzing prevention, and storage stability of the ink composition. In addition, from the viewpoint of being able to form a color image having further excellent gloss, the maximum particle size of the copolymer resin is preferably 0.3 μm or less, and the average particle size is 0.2 μm or less (more preferably 0.2 μm or less). More preferably, it is 1 μm or less. The average particle diameter is an average value of the dispersion diameter (cumulative 50% diameter) as the particles actually formed in the dispersion liquid. For example, Microtrac UPA (Microtrac Inc.) is used. Can be measured.

  The content of the oxyethyl acrylate resin is such that the pigment 100 is capable of forming a color image having both glossiness of a color image, prevention of bronzing, and storage stability of the ink composition and excellent glossiness. Preferably it is 20-50 weight part with respect to a weight part, More preferably, it is 20-40 weight part.

  In this embodiment, by using a urethane-based resin as a fixing pigment dispersant, the gloss of the color image, the prevention of bronzing, and the storage stability of the ink composition are compatible and the gloss is further improved. Color images can be formed. The urethane-based resin is a resin containing a polymer obtained by reacting a diisocyanate compound and a diol compound. In the present embodiment, a resin having a urethane bond and / or an amide bond and an acidic group. It is preferable that

  Examples of the diisocyanate compound include aromatic aliphatic diisocyanate compounds such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate, aromatic diisocyanate compounds such as toluylene diisocyanate and phenylmethane diisocyanate, and modified products thereof. .

  Examples of the diol compound include polyethers such as polyethylene glycol and polypropylene glycol, polyesters such as polyethylene abido and polybutylene abates, and polycarbonates.

  The acid value of the urethane-based resin is preferably 10 to 300 from the viewpoint of achieving color image glossiness, prevention of bronzing, and storage stability of the ink composition and forming a color image having further excellent glossiness. More preferably, it is 20-100. The acid value is the mg amount of KOH required to neutralize 1 g of resin.

  The weight-average molecular weight (Mw) before crosslinking of the urethane resin is compatible from the viewpoint of achieving color image glossiness, prevention of bronzing, and storage stability of the ink composition and at the same time forming a more glossy color image. , Preferably it is 100-200,000, More preferably, it is 1000-50,000. Mw is measured by GPC (gel permeation chromatography), for example.

  The urethane resin has a glass transition temperature (Tg; measured in accordance with JISK6900) from the viewpoint of achieving a color image having excellent glossiness while maintaining the glossiness of the color image, prevention of bronzing, and storage stability of the ink composition. Is preferably −50 to 200 ° C., and more preferably −50 to 100 ° C.

  The urethane resin preferably has a carboxyl group.

  The content of the urethane-based resin is 100 parts by weight of the pigment from the viewpoint of achieving color image glossiness, prevention of bronze, and storage stability of the ink composition and at the same time forming a more glossy color image. The amount is preferably 20 to 50 parts by weight, and more preferably 20 to 40 parts by weight.

  Furthermore, in the present embodiment, a fluorene resin can be used as the fixing pigment dispersant. The use is more preferable because it reduces the initial viscosity of the ink, is excellent in storage stability at high temperatures, and is excellent in fixability to printing paper.

The fluorene-based resin is not limited as long as it has a fluorene skeleton, and can be obtained, for example, by copolymerizing the following monomer units.
Cyclohexane, 5-isocyanate-1- (isocyanatomethyl) -1,3,3-trimethyl (CAS No. 4098-71-9)
Ethanol, 2,2 ′-[9H-fluorene-9-ylidenebis (4,1-phenyleneoxy)] bis (CAS No. 117344-32-8)
Propionic acid, 3-hydroxy-2- (hydroxymethyl) -2-methyl (CAS No. 4767-03-7)
Ethanamine, N, N-diethyl- (CAS No. 121-44-8)

  The fluorene-based resin is not particularly limited. For example, the monomer composition ratio is not particularly limited. 4098-71-9 is 35-45%, CAS No. 117344-32-8 is 40 to 50%, CAS No. 4767-03-7 is 5 to 15%, CAS No. 121-44-8 is 5 to 10%.

  The number average molecular weight (Mn) before crosslinking of the fluorene-based resin is preferably 2000 to 5000, and more preferably 3000 to 5000, from the viewpoint of achieving both the initial viscosity of the ink composition and the storage stability of the ink composition. 4000. Mn is measured by, for example, GPC (gel permeation chromatography).

  The fluorene-based resin has a case where it is adsorbed to a pigment in a pigment dispersion and a case where it is liberated, and achieves both glossiness of a color image, prevention of bronzing, and storage stability of an ink composition. In addition, from the viewpoint of forming a color image having further excellent gloss, the copolymer resin preferably has a maximum particle size of 0.3 μm or less, and an average particle size of 0.2 μm or less (more preferably 0.1 μm). The following is more preferable. The average particle diameter is an average value of the dispersion diameter (cumulative 50% diameter) as the particles actually formed in the dispersion liquid. For example, Microtrac UPA (Microtrac Inc.) is used. Can be measured.

  The content of the fluorene-based resin is 100 parts by weight of the pigment from the viewpoint that both color image fixability, bronzing prevention, and storage stability of the ink composition are compatible and a color image having further excellent fixability can be formed. The amount is preferably 20 to 50 parts by weight, and more preferably 20 to 40 parts by weight.

  The weight ratio (the former / the latter) of the copolymer resin and the fixing pigment dispersant is preferably 1/2 to 2/1. However, the gloss of the color image, the prevention of bronzing, and the storage stability of the ink composition are improved. From the standpoint of being able to form a color image that is compatible and more excellent in gloss, it is more preferably 1 / 1.5 to 1.5 / 1.

  The weight ratio of the solid content of the pigment to the solid content of the copolymer resin and the fixing pigment dispersant (the former / the latter) is effective for the glossiness of the color image, the prevention of bronzing, and the storage stability of the ink composition. From the viewpoint of being able to form a color image that is compatible with both glossiness and glossiness, it is preferably 100/40 to 100/100.

  A surfactant may be used as the dispersant. Such surfactants include fatty acid salts, higher alkyl dicarboxylates, higher alcohol sulfates, higher alkyl sulfonates, condensates of higher fatty acids and amino acids, sulfosuccinate esters, naphthenates, liquid fats. Anionic surfactants such as oil sulfate esters and alkyl allyl sulfonates; Cationic surfactants such as fatty acid amine salts, quaternary ammonium salts, sulfonium salts and phosphoniums; polyoxyethylene alkyl ethers and polyoxyethylene alkyls Nonionic surfactants such as esters, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters and the like can be mentioned. It goes without saying that the surfactant described above also functions as a surfactant by being added to the ink composition.

<Surfactant>
The ink composition for inkjet recording in the present embodiment may contain a surfactant. Glossy print media such as photographic paper, where glossiness is more important by using a surfactant, compared to the print media coated with a resin for receiving ink on the surface. Can be realized. In particular, even when a printing medium such as a printing paper in which a coating layer for receiving oil-based ink is provided on the surface receiving layer is used, bleeding between colors can be prevented. At the same time, it is possible to prevent whitening due to reflected light of light generated with an increase in the amount of ink attached.

  As the surfactant used in the present embodiment, a polyorganosiloxane-based surfactant can be suitably used, and when forming a recorded image, the wettability to the surface of the printing medium is increased to increase the ink permeability. be able to. When a polyorganosiloxane-based surfactant is used, since it contains one kind of alcohol solvent and one kind of polyglycol solvent as described above, the solubility of the surfactant in the ink is improved, and insoluble matter, etc. Therefore, it is possible to realize an ink composition with more excellent ejection stability.

  Commercially available surfactants such as those described above may be used. For example, Olfin PD-501 (manufactured by Nissin Chemical Industry Co., Ltd.), Olphine PD-570 (manufactured by Nissin Chemical Industry Co., Ltd.), BYK. -347 (made by Big Chemie Co., Ltd.), BYK-348 (made by Big Chemie Co., Ltd.), etc. can be used.

（式中、Ｒは水素原子またはメチル基を表し、ａは７〜１１の整数を表し、ｍは３０〜５０の整数を表し、ｎは３〜５の整数を表す。）
で表される一種または二種以上の化合物を含んでなるか、または、上記式（ＩＩ）の化合物において、式中、Ｒは水素原子またはメチル基を表し、ａは９〜１３の整数を表し、ｍは２〜４の整数を表し、ｎは１〜２の整数である一種または二種以上の化合物を含んでなることがより好ましい。また、上記式（ＩＩ）の化合物において、Ｒは水素原子またはメチル基を表し、ａは６〜１８の整数を表し、ｍは０の整数を表し、ｎは１の整数である一種または二種以上の化合物を含んでなることがより好ましい。このような特定のポリオルガノシロキサン系界面活性剤を使用することにより、印刷媒体として印刷用紙に印刷した場合であっても、インクのビーディングとブリーディングがより改善される。 Further, as the polyorganosiloxane surfactant, the following formula (II):

(In the formula, R represents a hydrogen atom or a methyl group, a represents an integer of 7 to 11, m represents an integer of 30 to 50, and n represents an integer of 3 to 5.)
Or a compound represented by the above formula (II), wherein R represents a hydrogen atom or a methyl group, and a represents an integer of 9 to 13. , M represents an integer of 2 to 4, and n preferably includes one or more compounds that are integers of 1 to 2. In the compound of the above formula (II), R represents a hydrogen atom or a methyl group, a represents an integer of 6 to 18, m represents an integer of 0, and n is an integer of 1 or two. More preferably, it comprises the above compound. By using such a specific polyorganosiloxane-based surfactant, ink beading and bleeding are further improved even when printed on a printing paper as a printing medium.

  In the compound of the formula (II), ink beading can be further improved by using a compound in which R is a methyl group.

  Further, in the compound of the above formula (II), ink bleeding can be further improved by using a compound in which R is a hydrogen atom.

  The surfactant is preferably contained in the ink composition in the present embodiment in an amount of 0.01 to 1.0% by weight, more preferably 0.05 to 0.50% by weight. In particular, when the above-described surfactant in which R is a methyl group is used, it is preferable to increase the content as compared with the case in which the above-described surfactant in which R is H is used.

  The ink composition in the present embodiment may further contain other surfactants, specifically, acetylene glycol surfactants, anionic surfactants, nonionic surfactants, amphoteric surfactants, and the like. good.

  Among these, acetylene glycol surfactants include, for example, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6- Diol, or 3,5-dimethyl-1-hexyn-3ol, 2,4-dimethyl-5-hexyn-3-ol and the like can be mentioned. Commercially available acetylene glycol surfactants can also be used. For example, Olphine E1010, STG, Y (trade name, manufactured by Nissin Chemical Co., Ltd.), Surfynol 61, 104, 82, 465, 485 or TG (Trade name, manufactured by Air Products and Chemicals Inc.).

<Water, other ingredients>
The ink composition in the present embodiment contains the above-described specific alcohol solvent, specific polyglycol solvent, surfactant, and other various additives, and also contains water as a solvent. It is preferable to use pure water or ultrapure water such as ion exchange water, ultrafiltration water, reverse osmosis water, or distilled water. In particular, water obtained by sterilizing these waters by ultraviolet irradiation or addition of hydrogen peroxide is preferable because generation of mold and bacteria is prevented for a long period of time.

  The ink composition in the present embodiment preferably contains a penetrant in addition to the above components.

  As the penetrant, glycol ethers can be preferably used.

  Specific examples of glycol ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-iso-butyl ether, ethylene glycol mono-tert -Butyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono-iso-propyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-tert-butyl ether, triethylene Glycol mono-n-bu Ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, propylene glycol mono-n-butyl ether, propylene glycol mono-tert-butyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol-iso-propyl ether, dipropylene glycol mono-n-butyl ether, dipropylene glycol mono-tert-butyl ether, 1-methyl -1-methoxybutanol and the like, and one or a mixture of two or more thereof. It can be used.

  Among the glycol ethers, alkyl ethers of polyhydric alcohols are preferable, and ethylene glycol monoethyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, propylene glycol are particularly preferable. Preference is given to monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether or triethylene glycol mono-n-butyl ether. More preferred is triethylene glycol mono-n-butyl ether.

  The addition amount of the penetrant may be appropriately determined, but is preferably about 0.1 to 30% by weight, more preferably about 1 to 20% by weight.

  In addition, the ink composition in the present embodiment preferably contains a printing medium solubilizer in addition to the above components.

  Pyrrolidones such as N-methyl-2-pyrrolidone can be suitably used as the printing medium solubilizer. The addition amount of the printing medium solubilizer may be appropriately determined, but is preferably about 0.1 to 30% by weight, more preferably about 1 to 20% by weight.

  In addition, it is preferable that the ink composition for inkjet recording in the present embodiment does not substantially contain a wetting agent. A wetting agent has a function of preventing ink from drying and solidifying in an ink jet nozzle or the like. Therefore, when ink is dropped on synthetic paper having particularly low ink absorption performance, the ink does not dry and high-speed printing is possible. Can be problematic. In addition, when ink containing a wetting agent is used, beading spots may occur because the next ink adheres to the print medium in a state where unabsorbed ink is present on the print medium surface. Therefore, in the present embodiment, it is preferable that substantially no wetting agent is included when using a printing medium having such a particularly low ink absorption performance. Even if the ink is dried and solidified in the nozzle 42, the solidified ink can be redissolved by applying a solution containing a wetting agent.

  In particular, in the present embodiment, it is preferable that a wetting agent having a vapor pressure of 2 mPa or less at 25 ° C. is substantially not included. “Substantially free” means that the amount of the wetting agent added is less than 1% by weight based on the ink composition.

  When the content of the wetting agent having a vapor pressure at 25 ° C. of 2 mPa or less is less than 1% by weight with respect to the ink, not only the printing medium with low ink absorption such as printing paper but also the ink absorption ability Even for metals and plastics that are not present, printing can be performed by the ink jet recording method. In addition, although it is clear for those skilled in the art that a part of the above-described penetrating solvent also acts as a wetting agent, in the present specification, the above-described penetrating solvent is not included in the wetting agent. . In the present specification, the above alcohol solvent and polyglycol solvent are not included in the wetting agent.

  Examples of the wetting agent include wetting agents used in ordinary inks for inkjet recording. Specifically, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, trimethylol propane, trimethylol methane, trimethylol ethane. Etc. As a preferred aspect of the present embodiment, the ink composition contains 0.1 to 8% by weight or less of glycerin. When the printing medium is a printing paper with particularly low ink absorption performance, these wetting agents can be added as appropriate.

  The ink composition in the present embodiment further includes a nozzle clogging preventive agent, an antiseptic, an antioxidant, a conductivity adjusting agent, a pH adjusting agent, a viscosity adjusting agent, a surface tension adjusting agent, an oxygen absorber, and the like. be able to.

  Examples of preservatives and fungicides include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-dibenzthiazoline-3-one ( ICI's Proxel CRL, Proxel BND, Proxel GXL, Proxel XL-2, Proxel TN) and the like.

  Further, examples of pH adjusters, solubilizers, or antioxidants include amines such as diethanolamine, triethanolamine, propanolamine, morpholine and their modified products, potassium hydroxide, sodium hydroxide, lithium hydroxide, etc. Inorganic salts, ammonium hydroxide, quaternary ammonium hydroxides (tetramethylammonium, etc.), carbonates such as potassium carbonate, sodium carbonate, lithium carbonate and other phosphates, or N-methyl-2-pyrrolidone, urea, thio Examples include ureas such as urea and tetramethylurea, allophanates such as allophanate and methyl allophanate, biurets such as biuret, dimethylbiuret and tetramethylbiuret, and L-ascorbic acid and salts thereof.

Further, the ink composition in the present embodiment may contain an antioxidant and an ultraviolet absorber, and examples thereof include Tinuvin manufactured by Ciba Specialty Chemicals.
328, 900, 1130, 384, 292, 123, 144, 622, 770, 292, Irgacor 252 153, Irganox 1010, 1076, 1035, MD1024, lanthanide oxide, and the like.

  The ink composition in the present embodiment can be produced by dispersing and mixing the above components by an appropriate method. Preferably, the pigment, polymer dispersant, and water are first used in a suitable dispersing machine (for example, ball mill, sand mill, attritor, roll mill, agitator mill, Henschel mixer, colloid mill, ultrasonic homogenizer, jet mill, ang mill, etc.). Mix to prepare a uniform pigment dispersion, then add separately prepared resin (resin emulsion), water, water-soluble organic solvent, sugar, pH adjuster, preservative, fungicide, etc. An ink solution is prepared. After sufficiently stirring, the target ink composition can be obtained by performing filtration in order to remove the coarse particle diameter and foreign matters that cause clogging.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by these Examples.

<Preparation of ink composition>
Each ink was prepared by mixing each component according to the composition of Table 1 below and filtering through a 10 μm membrane filter. The oxyethyl acrylate resins in the table are CAS No. This is a resin having a molecular weight of 6900, which contains a monomer having an oxyethyl acrylate structure represented by 72009-86-0 and having a monomer composition ratio of about 75% by weight.
Fluorene-based resin is CAS No. It is a resin having a molecular weight of 3300, containing a monomer having a fluorene skeleton represented by 117344-32-8 and a monomer composition ratio of about 50% by weight.
Further, the surfactant used is a polyorganosiloxane surfactant, and in the above formula (II), R is a methyl group, a is an integer of 6 to 18, and m is an integer of 0. In the compound where n is an integer of 1 and the above formula (II), R is a hydrogen atom, a is an integer of 7 to 11, m is an integer of 30 to 50, and n is 3 In the compound which is an integer of ˜5 and the above formula (II), R is a methyl group, a is an integer of 9 to 13, m is an integer of 2 to 4, and n is 1 to 2 A surfactant comprising a compound that is an integer.

＜表１（つづき）＞

＜表１（つづき）＞

<Table 1>

<Table 1 (continued)>

<Table 1 (continued)>

Examples 9 to 16 and Comparative Example 2
Further, Example 9 was carried out in the same manner as in Example 9 except that 1,2-octanediol, which is the alcohol solvent of the ink sets of Examples 1 to 8 and Comparative Example 1, was changed from 2% by weight to 4% by weight. -16 and Comparative Example 2 ink sets were prepared.

Examples 17-32
Furthermore, a diol type polypropylene glycol (weight average molecular weight 400) (manufactured by Wako Pure Chemical Industries, Ltd.), which is a polyglycol solvent of the ink sets of Examples 1 to 16, was used as a diol type polypropylene glycol (weight average molecular weight 1000). ) Ink sets of Examples 17 to 32 were prepared in the same manner except that it was changed to (made by Wako Pure Chemical Industries, Ltd.).

Examples 33-48
Further, in the same manner as in Examples 33 to 48 except that 1,2-octanediol, which is the alcohol solvent of the ink sets of Examples 1 to 16, was changed from 2% by weight or 4% by weight to 1% by weight. An ink set was prepared.

  Further, an ink set of Comparative Example 3 was prepared in the same manner except that 1,2-octanediol, which is the alcohol solvent of Comparative Example 1, was changed from 2% by weight to 1% by weight.

<Evaluation>
Ink bleeding (image quality) evaluation (part 1) (bleeding 1)
Each of the Y, M, C, and K inks obtained above is used as an ink set and mounted on an ink cartridge of an ink jet printer (PX-G920, manufactured by Seiko Epson Corporation), and is 720 dpi in the main scanning (head drive) direction. In addition, it was possible to record at 360 dpi in the sub-scanning (recording medium conveyance) direction. Next, the voltage applied to the piezo element of the printer head is adjusted so that the dot size upon landing is approximately 7 ng, and one drive is 720 × 360 dpi, and OKT + (made by Oji Paper Co., Ltd.) of about 128 g / square meter. A solid image of 720 × 720 dpi was recorded. Recording was performed in a low temperature and high humidity (15 ° C., 65% humidity) environment. At this time, the ink adhesion amount of a single color duty of 100% was approximately 3.6 mg / inch square meters. The distance between the recording paper and the recording head was 3 mm.
The recorded image is an image in which 2 to 8 pixel ruled lines of the primary color of 60% duty are brought into contact with the secondary color of 120% duty of 60% duty.

The obtained image was evaluated according to the following criteria.
A: A 2/720 inch ruled line can be reproduced without bleeding.
B: The 4/720 inch ruled line can be reproduced without bleeding, but the 2/720 inch ruled line cannot be reproduced due to bleeding.
C: The 6/720 inch ruled line can be reproduced without bleeding, but the 4/720 inch ruled line cannot be reproduced due to bleeding.
D: The 8/720 inch ruled line is bleeding and cannot be reproduced.
The evaluation results were as shown in Table 2 below.

Ink bleeding (image quality) evaluation (part 2) (bleeding 2)
Each of the Y, M, C, and K inks obtained above is used as an ink set and mounted on an ink cartridge of an ink jet printer (PX-G920, manufactured by Seiko Epson Corporation), and is 720 dpi in the main scanning (head drive) direction. In addition, it was possible to record at 360 dpi in the sub-scanning (recording medium conveyance) direction. Next, the voltage applied to the piezo element of the printer head is adjusted so that the dot size upon landing is approximately 7 ng, and one drive is 720 × 360 dpi, and OKT + (made by Oji Paper Co., Ltd.) of about 128 g / square meter. A solid image of 720 × 720 dpi was recorded. Recording was performed in a low temperature and high humidity (15 ° C., 65% humidity) environment. At this time, the ink adhesion amount of a single color duty of 100% was approximately 3.6 mg / inch square meters. The distance between the recording paper and the recording head was 3 mm.
The recorded image is an image in which 2 to 8 pixel ruled lines of the primary color of Duty 60% are brought into contact with the tertiary color of Duty 180% of Duty 60%.

The obtained image was evaluated according to the following criteria.
A: A 2/720 inch ruled line can be reproduced without bleeding.
B: The 4/720 inch ruled line can be reproduced without bleeding, but the 2/720 inch ruled line cannot be reproduced due to bleeding.
C: The 6/720 inch ruled line can be reproduced without bleeding, but the 4/720 inch ruled line cannot be reproduced due to bleeding.
D: The 8/720 inch ruled line is bleeding and cannot be reproduced.

Ink bleeding (image quality) evaluation (part 3) (bleeding 3)
Each of the Y, M, C, and K inks obtained above is used as an ink set and mounted on an ink cartridge of an ink jet printer (PX-G920, manufactured by Seiko Epson Corporation), and is 720 dpi in the main scanning (head drive) direction. In addition, it was possible to record at 360 dpi in the sub-scanning (recording medium conveyance) direction. Next, the voltage applied to the piezo element of the printer head is adjusted so that the dot size upon landing is approximately 3 ng, and one drive is 720 × 360 dpi, and OKT + (made by Oji Paper Co., Ltd.) of about 128 g / square meter. A solid image of 720 × 720 dpi was recorded. Recording was performed in a low temperature and high humidity (15 ° C., 65% humidity) environment. At this time, the ink adhesion amount of a single color duty of 100% was approximately 1.6 mg / inch square meters. The distance between the recording paper and the recording head was 3 mm.
The recorded image is an image in which 2 to 8 pixel ruled lines of the primary color of 60% duty are brought into contact with the secondary color of 120% duty of 60% duty.

The obtained image was evaluated according to the following criteria.
A: A 2/720 inch ruled line can be reproduced without bleeding.
B: The 4/720 inch ruled line can be reproduced without bleeding, but the 2/720 inch ruled line cannot be reproduced due to bleeding.
C: The 6/720 inch ruled line can be reproduced without bleeding, but the 4/720 inch ruled line cannot be reproduced due to bleeding.
D: The 8/720 inch ruled line is bleeding and cannot be reproduced.
The evaluation results were as shown in Table 2 below.

Ink bleeding (image quality) evaluation (part 4) (bleeding 4)
Each of the Y, M, C, and K inks obtained above is used as an ink set and mounted on an ink cartridge of an ink jet printer (PX-G920, manufactured by Seiko Epson Corporation), and is 720 dpi in the main scanning (head drive) direction. In addition, it was possible to record at 360 dpi in the sub-scanning (recording medium conveyance) direction. Next, the voltage applied to the piezo element of the printer head is adjusted so that the dot size upon landing is approximately 3 ng, and one drive is 720 × 360 dpi, and OKT + (made by Oji Paper Co., Ltd.) of about 128 g / square meter. A solid image of 720 × 720 dpi was recorded. Recording was performed in a low temperature and high humidity (15 ° C., 65% humidity) environment. At this time, the ink adhesion amount of a single color duty of 100% was approximately 1.6 mg / inch square meters. The distance between the recording paper and the recording head was 3 mm.
The recorded image is an image in which 2 to 8 pixel ruled lines of the primary color of Duty 60% are brought into contact with the tertiary color of Duty 180% of Duty 60%.

The obtained image was evaluated according to the following criteria.
A: A 2/720 inch ruled line can be reproduced without bleeding.
B: The 4/720 inch ruled line can be reproduced without bleeding, but the 2/720 inch ruled line cannot be reproduced due to bleeding.
C: The 8/720 inch ruled line is bleeding and cannot be reproduced.
The evaluation results were as shown in Table 2 below.

Ink beading (image quality) evaluation (Part 1) (Beading 1)
Each of the Y, M, C, and K inks obtained above is used as an ink set and mounted on an ink cartridge of an ink jet printer (PX-G920, manufactured by Seiko Epson Corporation), and is 720 dpi in the main scanning (head drive) direction. In addition, it was possible to record at 360 dpi in the sub-scanning (recording medium conveyance) direction. Next, the voltage applied to the piezo element of the printer head is adjusted so that the dot size upon landing is approximately 7 ng, and one drive is 720 × 360 dpi, and OKT + (made by Oji Paper Co., Ltd.) of about 128 g / square meter. A solid image of 720 × 720 dpi was recorded. Recording was performed in a low temperature and high humidity (15 ° C., 65% humidity) environment. At this time, the ink adhesion amount of a single color duty of 100% was approximately 3.6 mg / inch square meters. The distance between the recording paper and the recording head was 3 mm.
The recorded image is a secondary color image obtained by mixing single colors having the same duty.

The obtained image was evaluated according to the following criteria.
AA: Up to secondary color Duty 180% of each single color Duty 90% can be reproduced without beading.
A: Up to 160% of the secondary color Duty of each single color Duty 80% can be reproduced without beading.
B: Up to secondary color Duty of 140% of each single color Duty can be reproduced without beading.
C: Up to secondary color Duty of 120% for each single color Duty can be reproduced without beading.
The evaluation results were as shown in Table 2 below.

Ink beading (image quality) evaluation (Part 2) (Beading 2)
Each of the Y, M, C, and K inks obtained above is used as an ink set and mounted on an ink cartridge of an ink jet printer (PX-G920, manufactured by Seiko Epson Corporation), and is 720 dpi in the main scanning (head drive) direction. In addition, it was possible to record at 360 dpi in the sub-scanning (recording medium conveyance) direction. Next, the voltage applied to the piezo element of the printer head is adjusted so that the dot size upon landing is approximately 3 ng, and one drive is 720 × 360 dpi, and OKT + (made by Oji Paper Co., Ltd.) of about 128 g / square meter. A solid image of 720 × 720 dpi was recorded. Recording was performed in a low temperature and high humidity (15 ° C., 65% humidity) environment. At this time, the ink adhesion amount of a single color duty of 100% was approximately 1.6 mg / inch square meters. The distance between the recording paper and the recording head was 3 mm.
The recorded image is a secondary color image obtained by mixing single colors having the same duty.

The obtained image was evaluated according to the following criteria.
AA: Up to secondary color Duty 180% of each single color Duty 90% can be reproduced without beading.
A: Up to 160% of the secondary color Duty of each single color Duty 80% can be reproduced without beading.
B: Up to secondary color Duty of 140% of each single color Duty can be reproduced without beading.
C: Up to secondary color Duty of 120% for each single color Duty can be reproduced without beading.
The evaluation results were as shown in Table 2 below.

Evaluation of wiping durability The above ink cartridge and ink jet printer were used. About 0.25 g of ink for each color per time was discarded in the cap, and then the operation of the wiper wiping the head surface was repeated 3000 times. Evaluation was carried out in a low temperature and high humidity (15 ° C., 65% humidity) environment.
A: No wet bending occurs.
B: Wet bending has occurred.
The evaluation results were as shown in Table 2 below.

Evaluation of initial viscosity of ink The ink viscosity of each ink obtained as described above was evaluated. Using a vibration viscometer (MV100 model, manufactured by Yamaichi Electronics Co., Ltd.), the viscosity of the ink after 1 hour from the preparation of the ink was measured and evaluated according to the following criteria. The measurement temperature was 20 ° C.
A: The viscosity is more than 3.5 mPa · s and 4.5 mPa · s or less.
B: The viscosity is more than 4.5 mPa · s and not more than 5.5 mPa · s.
C: The viscosity exceeds 5.5 mPa · s.
The evaluation results were as shown in Table 2 below.

Evaluation of clogging recovery property Using the ink cartridge and the ink jet printer described above, the ink replacement button was pressed, and then the outlet was removed. In this way, after the head cap was removed, the printer was left in an environment of 50 ° C. and 15% RH for 2 days.

After leaving, the cleaning operation was repeated until all nozzles ejected at the same level as the initial stage, and the ease of recovery was evaluated according to the following criteria.
AA: The clogging is recovered by repeating the cleaning operation three times.
A: The clogging is recovered by repeating the cleaning operation six times.
B: The clogging is recovered by repeating the cleaning operation 12 times.
C: The clogging does not recover even if the cleaning operation is repeated 12 times.
The results were as shown in Table 2 below.

＜表２（つづき）＞

<Table 2>

<Table 2 (continued)>

<Operation for cleaning>
(1) Case where the suction pump operates Next, in the printer 10 having the above-described configuration, the operation when the suction pump 56 operates among the operations when performing the cleaning will be described with reference to FIG. To do. In the following description of the operation, steps S01 to S05 can be executed sequentially.

  Step S01: First, the discharge operation inside the recess 51a of the cap 51 is performed according to a command from the control unit 70. At this time, the suction pump 56 is operated by the control command of the control unit 70, the discharge valve 55 is opened, and the air release valve 59 is opened. Thereby, negative pressure is exerted on the concave portion 51a through the suction port 511 and the first tube 53, and the ink remaining in the concave portion 51a due to the negative pressure acts on the suction port 511 and the first tube 53. Through the waste liquid tank 54. In the operation of step S01, the cap 51 may or may not be in contact with the nozzle forming surface 41a.

  Step S02: In response to a command from the control unit 70, the operation of the suction pump 56 that has been operated in Step S01 is stopped. Further, according to a command from the control unit 70, the discharge valve 55 is closed, and the atmosphere release valve 59 is also closed.

  Step S03: Next, according to a command from the control unit 70, the discharge valve 55 is opened and the atmosphere release valve 59 is closed. In this state, the suction pump 56 is operated by a command from the control unit 70. At this time, the cap 51 is brought into contact with the nozzle forming surface 41a. In step S01 described above, when the cap 51 is not in contact with the nozzle forming surface 41a, a mechanism for raising and lowering the cap 51 (not shown) is operated prior to the operation of the suction pump 56 described above. An operation for contacting the nozzle forming surface 41a is performed.

  By executing the operation of step S03, the inside of the recess 51a (sealed space) of the cap 51 becomes negative pressure. Accordingly, ink is sucked out from the nozzle 42a and cleaning liquid is sucked out from the nozzle 42b. Then, the sucked out ink or cleaning liquid adheres to the ink absorber 52, and the ink or cleaning liquid penetrates into the ink absorber 52. At this time, the ink absorber 52 located in the vicinity of the suction port 511 is in a state of being impregnated with a large amount of ink. Further, the ink absorber 52 located in the vicinity of the atmosphere communication port 512 is in a state of being impregnated with a large amount of cleaning liquid.

  Further, as described above, the negative pressure is also applied to the region from the one end side to the discharge valve 55 in the first tube 53 due to the negative pressure inside the recess 51a (sealed space). The first tube 53 contracts so that the volume of the internal space of the first tube 53 is reduced. Similarly, since a negative pressure is also applied to a region from the one end side to the atmosphere release valve 59 in the second tube 57, the second tube 57 is formed so that the volume of the internal space of the second tube 57 in this region is reduced. Shrink.

  Step S04: The operation of the suction pump 56 that has been operated in Step S03 is stopped by a command from the control unit 70. Further, according to a command from the control unit 70, the discharge valve 55 is closed, and the atmosphere release valve 59 is also closed.

  Here, when the operation of the suction pump 56 is stopped, the negative pressure inside the recess 51a (sealed space) gradually decreases. That is, the pressure inside the recess 51a (sealed space) gradually approaches atmospheric pressure. Therefore, the contraction state of the region from the one end side to the atmosphere release valve 59 in the second tube 57 is gradually released. That is, as the negative pressure gradually decreases, the region from one end side to the atmosphere release valve 59 in the second tube 57 gradually expands. Due to the swelling of the second tube 57, the liquid present in the vicinity of the atmosphere communication port 512 among the liquid impregnated in the ink absorber 52 is drawn into the second tube 57.

  Here, in the conventional cap, the liquid present in the vicinity of the atmosphere communication port 512 among the liquid impregnated in the ink absorber 52 is ink ejected from the nozzle 42 a, so that the ink is in the second tube 57. Get inside. Then, the ink that has entered from the atmosphere communication port 512 is solidified, and the flow path inside the second tube 57 may be blocked. In addition, the ink that has entered from the atmosphere communication port 512 becomes a film shape, and the film shape may solidify. For this reason, even if the atmosphere release valve 59 is switched to the open side, the flow path inside the second tube 57 is blocked, so that air may be prevented from flowing into the cap.

  However, in the present embodiment, the ink absorber 52 located in the vicinity of the atmosphere communication port 512 is in a state of being impregnated with a large amount of cleaning liquid. Therefore, even if the liquid is drawn into the second tube 57, the liquid is in a state where there is a lot of cleaning liquid. For this reason, in the inside of the second tube 57, rather than solidification like ink occurs, conversely, the cleaning liquid flows, so that the solidified body solidified in the second tube 57 in the past melts, and the liquid flowability is further improved. It will be secured. That is, even if a liquid with a large amount of cleaning liquid flows into the second tube 57, the flowability of the liquid inside the second tube 57 is maintained.

  Step S05: After step S04 described above, the same operation as step S01 is executed. That is, the discharge operation inside the recess 51a of the cap 51 is performed according to a command from the control unit 70. At this time, the suction pump 56 is operated by the control command of the control unit 70, the discharge valve 55 is opened, and the air release valve 59 is opened. As a result, negative pressure is exerted on the concave portion 51a via the suction port 511 and the first tube 53, and the liquid remaining in the concave portion 51a due to the negative pressure acts on the suction port 511 and the first tube 53. Through the waste liquid tank 54.

  Here, in the conventional configuration, even if the suction operation in step S05 is executed, it is difficult to completely discharge the liquid that has entered the second tube 57 through the first tube 53.

  An example of this state is shown in FIG. As shown in FIG. 6, a case is considered where the second tube 57 is curved and a portion where the liquid accumulates exists due to the curvature. In this state, it is desirable that the liquid is discharged to the cap 51 side when a suction force is applied by the operation of the suction pump 56. However, even if a suction force is applied by the operation of the suction pump 56, the air sucked from the other end of the second tube 57 passes through the staying liquid as bubbles, and the air is discharged. There are also cases where the liquid is not drained. Also, as shown in FIG. 7, when the amount of liquid staying is smaller than in the case shown in FIG. 6, the flow path inside the second tube 57 is not blocked by the liquid. Is more difficult to be discharged to the cap 51 side.

  For this reason, in the cases as shown in FIGS. 6 and 7, it is difficult to completely discharge the liquid that has entered the second tube 57 through the first tube 53. Then, for example, when the portion where the liquid is accumulated as shown in FIG. 6 is dried and solidified, the circulation of the second tube 57 is hindered.

  However, in the present embodiment, even if a liquid is drawn into the second tube 57, the liquid is in a state where there is a lot of cleaning liquid. Therefore, inside the second tube 57, rather than solidifying like ink, the solidified material solidified in the second tube 57 in the past melts due to the large amount of cleaning liquid. In addition, even if there is a liquid in the second tube 57 that is not discharged to the waste liquid receiver 58, the amount of ink in the liquid is significantly reduced compared to the conventional case. That is, the ink is greatly diluted and is present inside the second tube 57. Therefore, it is possible to reduce the amount of the solidified body solidified inside the second tube 57.

(2) About operation | movement in case of performing flushing Next, operation | movement which performs flushing is demonstrated among the operations at the time of cleaning in the printer 10 which has the above structures.

  When execution of flushing is instructed by the control command of the control unit 70 based on a control mode such as maintenance, ink is ejected from all the nozzles 42a of the short head 41 and cleaning liquid is ejected from all the nozzles 42b. It is done.

  Then, the ejected ink or cleaning liquid adheres to the ink absorber 52, and the ink or cleaning liquid penetrates into the ink absorber 52. At this time, the ink absorber 52 located in the vicinity of the suction port 511 is in a state of being impregnated with a large amount of ink. Further, the ink absorber 52 located in the vicinity of the atmosphere communication port 512 is in a state of being impregnated with a large amount of cleaning liquid.

  For this reason, even if the liquid enters the inside of the second tube 57, the liquid is in a state where there is a lot of cleaning liquid. For this reason, in the inside of the second tube 57, rather than solidification such as ink occurs, conversely, due to a large amount of cleaning liquid, the solidified body solidified in the second tube 57 in the past melts, and the flowability of the liquid is further improved. It will be secured. That is, even if a liquid with a large amount of cleaning liquid flows into the second tube 57, the flowability of the liquid inside the second tube 57 is maintained.

<Effect>
According to the printer 10 configured as described above, the nozzle row 43b is provided closer to the atmosphere communication port 512 than the nozzle row 43a. Therefore, the liquid present in the vicinity of the atmosphere communication port 512 is in a state where there is a lot of cleaning liquid ejected from the nozzle row 43b. Thereby, even if the liquid enters from the atmosphere communication port 512, the liquid is in a state where there is much cleaning liquid. Therefore, on the downstream side in the flow path of the second tube 57 from the air communication port 512, on the contrary, solidification like ink occurs, and conversely, due to a large amount of cleaning liquid, the solidified body solidified in the past is dissolved and liquid It is possible to further secure the distribution of the product. For this reason, it is possible to satisfactorily prevent the liquid that has entered from the air communication port 512 from solidifying in the flow path.

  In the present embodiment, a plurality of nozzle rows 43a are provided corresponding to the type of ink, and the lower the viscosity of the ink ejected from each of the plurality of nozzle rows 43a, the more the nozzle rows 43a pass through the nozzle row 43a. The distances L1 to Ln between the straight lines X1 to Xn parallel to the ink ejection direction and the atmosphere communication port 512 are short. Therefore, the part where the ink having high viscosity adheres to the ink absorber 52 is kept away from the atmosphere communication port 512. Thereby, it is possible to satisfactorily prevent high viscosity ink from flowing in from the air communication port 512.

  Further, in the present embodiment, among the plurality of nozzle rows 43a, one that ejects white ink having a higher viscosity than other types of ink may be provided. In such a configuration, since the liquid present in the vicinity of the atmosphere communication port 512 has a large amount of components of the cleaning liquid, it is closer to the downstream side in the flow path of the second tube 57 than the atmosphere communication port 512. Thus, it is possible to satisfactorily prevent the white ink from entering from the atmosphere communication port 512 and solidifying. In addition, since the white ink is disposed at a position away from the atmosphere communication port 512 among the plurality of nozzle rows 43a, it is possible to favorably prevent white ink having a high viscosity from entering from the atmosphere communication port 512.

  Further, in the present embodiment, the ink ejected from at least one of the plurality of nozzle rows 43a includes at least a coloring material, water, an alcohol solvent, and a polyglycol solvent, and an alcohol solvent. However, the water-soluble alkanediol may be contained, and the polyglycol solvent may contain polyalkylene glycol. In such a configuration, the ink becomes a high-viscosity ink. However, when such a high-viscosity ink enters from the atmosphere communication port 512, the ink is solidified in the downstream flow passage. However, since the liquid present in the vicinity of the atmosphere communication port 512 has a large amount of components of the cleaning liquid, the ink having a high viscosity is disposed downstream of the atmosphere communication port 512 in the flow path of the second tube 57. Can be satisfactorily prevented from entering through the atmosphere communication port 512 and solidifying.

  Further, in the present embodiment, the control mode at the time of maintenance of the control unit 70 includes the short head 41 and the cap 51 in the state where the above-described sealed space is formed or even if the sealed space is not formed. There is a control mode in which the cleaning liquid is ejected from the nozzle row 43b at the same time as the ink is ejected from the nozzle row 43a in the opposed state. For this reason, even in a maintenance operation such as flushing, for example, the cleaning liquid is ejected from the nozzle row 43b, so that the liquid present in the vicinity of the atmosphere communication port 512 is in a state where the cleaning liquid ejected from the nozzle row 43b is large. Thereby, even if the liquid enters from the air communication port 512, it is possible to satisfactorily prevent the liquid from solidifying in the flow passage.

  In the present embodiment, the suction mechanism 50 includes a first tube 53, a discharge valve 55, and a suction pump 56 as constituents of the suction means, and the suction mechanism 50 further includes As a constituent of the atmosphere release means, a second tube 57 and an atmosphere release valve 59 are provided. For this reason, it is possible to satisfactorily prevent the liquid from entering and solidifying inside the second tube 57.

<Modification>
Although one embodiment of the present invention has been described above, the present invention can be variously modified. This will be described below.

  In the above-mentioned embodiment, the case where the line head 40 comprised from the some short head 41 is used is demonstrated. Here, in the above-described embodiment, each short head 41 corresponds to an ejection head. However, the line head 40 may correspond to the ejection head. Further, the line head is not limited to the one composed of a plurality of short heads, and a long line head having a width dimension larger than the width dimension of the print medium P may be used.

  In the above-described embodiment, the line head 40 is used, and each of the plurality of short heads 41 is an example of one corresponding to the ejection head. However, instead of the line head, a print head that can move along the main scanning direction may be an example of one corresponding to the ejection head.

  In addition, a configuration in which a plurality of suction ports 511 in the above-described embodiment may be employed, or a configuration in which a plurality of air communication ports 512 are provided may be employed.

  In the above-described embodiment, the nozzle row 43 b corresponding to an example of the second ejection nozzle row that ejects the cleaning liquid is provided so as to be positioned on one end side of the cap 51. However, the nozzle row corresponding to the second injection nozzle row may be provided not only at one end side of the cap 51 but also at an arbitrary position between the one end side and the other end side of the cap 51. Even in such a configuration, the second injection nozzle row is present in the vicinity of the atmosphere communication port 512 as long as the second injection nozzle row satisfies the fact that it is closer to the atmosphere communication port than the first injection nozzle row. As a result, the amount of the cleaning liquid ejected from the nozzle row 43b is large. Accordingly, it is possible to satisfactorily prevent the liquid that has entered from the air communication port 512 from solidifying in the flow path.

  Further, the height in the vertical direction around the atmosphere communication port 512 in the above-described embodiment may be made higher than the other part of the bottom of the cap 51. In the case of such a configuration, it becomes possible to make the liquid more difficult to enter from the atmosphere communication port 512.

  Further, in the above-described embodiment, the case where the short head 41 is located at the upper part of the cap 51 and the ink droplets are ejected from the upper side to the lower side has been described. However, the positional relationship between the short head 41 and the cap is not limited to the case of being positioned in the vertical direction, and the ink droplet ejection direction is not limited to the vertical direction. For example, when the nozzle forming surface 41a of the short head 41 is inclined with respect to the vertical direction, the ink droplet ejection direction is also oblique. In this case, the liquid ejected from the nozzle 42b is communicated with the atmosphere. The positional relationship is preferably set so as to adhere to the periphery of the mouth 512. That is, the straight line passing through the ink droplet ejection direction and passing through the nozzle 42b should be shorter than the straight line passing through the ink droplet ejection direction and passing through the nozzle 42a. The positional relationship between the short head 41 and the cap may be an oblique arrangement.

  In the above-described embodiment, the control unit 70 may be realized by software, or may be realized by a circuit.

  Further, the liquid ejecting apparatus according to the above-described embodiment may include both the functions of the printer 10 and the computer 100.

  In addition, the printer 10 may be a multifunction device including a scanner device, a fax device, a copy device, and the like other than the printing function as the printer of the present invention.

  Further, the concept of the printer 10 in the above-described embodiment includes fluids such as liquids other than ink (liquids themselves, liquids obtained by dispersing or mixing functional material particles in liquids, and gels). It is also possible to include a fluid ejecting apparatus that ejects or ejects (including a material). As such, a liquid containing a material such as an electrode material or a color material (pixel material) used for manufacturing a liquid crystal display, an EL (electroluminescence) display, and a surface emitting display is dispersed or dissolved. There are a liquid ejecting apparatus, a fluid ejecting apparatus that ejects a bio-organic matter used for biochip manufacturing, a fluid ejecting apparatus that ejects a liquid that is used as a precision pipette and serves as a sample, and the like.

  Further, the concept of the printer 10 of the present invention includes a micro hemispherical lens (optical lens) used in a fluid ejecting apparatus, an optical communication element, and the like that ejects lubricating oil pinpoint to a precision machine such as a watch or a camera. A fluid ejecting apparatus that ejects a transparent resin liquid such as an ultraviolet curable resin onto a substrate to form a substrate, a fluid ejecting apparatus that ejects an etchant such as an acid or an alkali to etch the substrate, etc. ) And the like.

DESCRIPTION OF SYMBOLS 10 ... Printer (corresponding to an example of a liquid ejecting apparatus), 20 ... Paper feed mechanism, 21 ... PF motor, 22 ... Paper feed roller, 30 ... Ink supply mechanism, 31 ... Cartridge holder, 32, 32a, 32b ... Cartridge, 33 ... ink supply path, 40 ... line head, 41 ... short head (corresponding to ejection head), 41a ... nozzle forming surface, 42, 42a, 42b ... nozzle, 43 ... nozzle row, 43a ... nozzle row (first ejection nozzle row) ), 43b... Nozzle row (corresponding to an example of the second ejection nozzle row), 50... Suction mechanism, 51... Cap, 51a. 54 ... waste liquid tank, 55 ... discharge valve (corresponding to a part of an example of suction means), 56 ... suction pump (corresponding to a part of an example of suction means), 57 Second tube (corresponds to a part of an example of the air release means), 58 ... waste liquid receiver, 59 ... Air release valve (corresponds to a part of an example of the air release means), 70 ... control unit, 100 ... computer, 511 ... Suction port, 512 ... Air communication port

Claims (6)

An ejection head having a first ejection nozzle row for ejecting ink containing a colorant and a second ejection nozzle row for ejecting a cleaning liquid capable of dissolving the colorant contained in the ink;
A cap that contacts the nozzle formation surface of the ejection head to form a sealed space, and that receives ink and / or cleaning liquid ejected from at least one of the first ejection nozzle row and the second ejection nozzle row;
Suction means for performing suction from the suction port of the sealed space;
Atmospheric release means for releasing the atmosphere from the atmosphere communication port of the sealed space;
Comprising
The second injection nozzle rows is arranged on the side of the atmosphere communication port than the first injection nozzle array,
A plurality of the first ejection nozzle rows are provided corresponding to the type of ink,
The lower the viscosity of the ink ejected from each of the plurality of first ejection nozzle rows, the straight line passing through the first ejection nozzle row and parallel to the ink ejection direction, and the air communication port The distance between is provided short,
A liquid ejecting apparatus. The liquid ejecting apparatus according to claim 1 ,
Among the plurality of first ejection nozzle arrays, the first ejection nozzle arrays that eject white ink are provided.
A liquid ejecting apparatus. The liquid ejecting apparatus according to claim 1 ,
Ink ejected from at least one first ejection nozzle row of the plurality of first ejection nozzle rows is
Comprising at least a colorant, water, an alcohol solvent, and a polyglycol solvent,
The alcohol solvent comprises a sparingly water-soluble alkanediol, and the polyglycol solvent comprises a polyalkylene glycol;
A liquid ejecting apparatus. The liquid ejecting apparatus according to any one of claims 1 to 3 ,
The ejection head is controlled and driven by a control unit,
The control mode during maintenance of the control unit includes the first mode in a state where the sealed space is formed, or in a state where the ejection head and the cap face each other even if the sealed space is not formed. There is a control mode in which the cleaning liquid is ejected from the second ejection nozzle array at the same time as the ink is ejected from the ejection nozzle array.
A liquid ejecting apparatus. The liquid ejecting apparatus according to any one of claims 1 to 4 ,
The suction means includes a first tube connected to the suction port, an openable / closable discharge valve provided in a middle portion of the first tube, and a middle portion of the first tube, which is more than the discharge valve. A suction pump that is provided on the side away from the sealed space and that drives to exert a negative pressure on the sealed space; and
The atmosphere release means includes a second tube connected to the atmosphere communication port, an atmosphere release valve provided in the middle of the second tube and capable of opening to the atmosphere,
A liquid ejecting apparatus comprising: An ejection head having a first ejection nozzle row for ejecting ink containing a colorant and a second ejection nozzle row for ejecting a cleaning liquid capable of dissolving the colorant contained in the ink, and the ejection head And a cap for receiving ink and / or cleaning liquid ejected from at least one of the first ejection nozzle row and the second ejection nozzle row, and a closed space of the sealed space. A suction unit that performs suction from the suction port, and an atmospheric release unit that performs atmospheric release from the atmospheric communication port of the sealed space,
The second injection nozzle row is disposed closer to the atmosphere communication port than the first injection nozzle row,
A plurality of the first ejection nozzle rows are provided corresponding to the type of ink,
The lower the viscosity of the ink ejected from each of the plurality of first ejection nozzle rows, the straight line passing through the first ejection nozzle row and parallel to the ink ejection direction, and the air communication port The distance between is short,
In the maintenance operation by sucking or ejecting the ink from the first ejection nozzle row, the cleaning liquid is also sucked or ejected from the second ejection nozzle row.
A maintenance method characterized by that.

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