JP2012171330A - Liquid droplet discharge device and method for recording image by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid droplet discharge device for recording an image excellent in fixability.SOLUTION: The liquid droplet discharge device has: a selection means for selecting one of multiple kinds of ink; a nozzle for discharging the ink circulated from the selection means; and a liquid supply path for connecting the selection means to the nozzle. A first ink and a second ink of the multiple kinds of ink have substantially the same color, and each of them contains a resin component. The first ink does not contain alkylpolyol having ≥280°C boiling point substantially but the second ink contains the alkylpolyol having ≥280°C boiling point. A relationship between the content [WA] of the resin component in the first ink and that [WB] of the resin component in the second ink satisfies WA>WB. The amount of the first ink to be used when the second ink in the liquid supply path is replaced with the first ink is larger than the amount of the second ink to be used when the first ink in the liquid supply path is replaced with the second ink.

Description

  The present invention relates to a droplet discharge device and an image recording method using the same.

  A droplet discharge device is required to be able to handle recording on various recording media using a single device. When recording on various recording media using one apparatus, it is necessary to use an ink suitable for the type of recording media. For this reason, every time the type of recording medium is changed, the currently installed ink cartridge is temporarily removed and replaced with an ink cartridge filled with a desired ink.

  However, the replacement of the ink cartridge is a cumbersome operation for the user of the droplet discharge device, which imposes an excessive burden on the user.

  Therefore, Patent Document 1 proposes a droplet discharge device including a switching unit that can replace ink discharged from the same nozzle as needed without replacing the ink cartridge. According to this, for example, one of photo black and mat black can be selectively ejected from the same nozzle.

  On the other hand, water-based ink compositions based on water as a solvent have been conventionally used. Such a water-based ink composition is used not only for recording on plain paper that easily absorbs ink but also for recording on media such as plastic that does not easily absorb ink from the viewpoint of the global environment and safety. It has become. However, the conventional water-based ink composition (hereinafter also referred to as “normal ink”) is not excellent in fixing to a medium that hardly absorbs ink. For this reason, in a water-based ink composition (hereinafter also referred to as “resin ink”) used for a medium that does not easily absorb ink, the content of the resin component for fixing the ink is higher than that of ordinary ink, and the boiling point is increased. For example, the content of the solvent at 280 ° C. or higher is lowered. However, since resin ink may cause problems in ejection stability due to the content of the resin component and the content of the organic solvent having a boiling point of 280 ° C. or higher, both the normal ink and the resin ink are combined by the switching means. It is being considered.

JP 2007-230006 A

  When the above-described normal ink and resin ink are applied to a droplet discharge device having an ink switching unit as described above, the normal ink and the resin ink are mixed with each other when the ink is switched. For this reason, there is a case where the components contained in the switched ink are discharged from the nozzles as they are in a state where the components are not originally mixed.

  In particular, it is important that the resin ink has excellent fixability to a recording medium that hardly absorbs the ink. Therefore, a resin component in the ink (a component that contributes to fixability to the recording medium) and a boiling point of 280 ° C. It is necessary to keep the content of the above organic solvent (a component that contributes to quick drying when printed on a recording medium) and a certain standard. For this reason, when recording on a recording medium that is difficult to absorb ink using resin ink, if the components contained in the switched ink deviate significantly from the originally blended ratio, the fixability of the recorded image is improved. There may be a problem that it is not excellent.

  An object of some embodiments of the present invention is to provide a droplet discharge device capable of recording an image having excellent fixability on various types of recording media.

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

[Application Example 1]
One aspect of the droplet discharge device according to the present invention is:
Selecting means for selecting one kind of ink from a plurality of kinds of ink;
A nozzle for discharging the ink circulated from the selection means;
A liquid supply path connecting the selection means and the nozzle;
Have
Of the plurality of types of inks, the first ink and the second ink are substantially the same color and contain a resin component,
The first ink substantially does not contain an alkyl polyol having a boiling point under 1 atm of 280 ° C. or higher,
The second ink contains an alkyl polyol having a boiling point under 1 atm of 280 ° C. or higher,
The relationship between the content [WA (mass%)] of the resin component in the first ink and the content [WB (mass%)] of the resin component in the second ink is (WA> WB). ), And
The amount of the first ink used when replacing the second ink in the liquid supply path with the first ink is the same as the first ink used when replacing the first ink in the liquid supply path with the second ink. More than 2 inks.

  According to the droplet discharge device of Application Example 1, it is possible to record images having excellent fixability on various types of recording media.

[Application Example 2]
In application example 1,
When the internal volume of the liquid supply path is an internal volume A, and the replacement amount B of the second ink used when replacing the first ink in the liquid supply path with the second ink,
The relationship between the internal volume A and the substitution amount B can be (internal volume A> replacement amount B).

[Application Example 3]
In application example 1 or application example 2,
When the internal volume of the liquid supply path is an internal volume A and the replacement amount C of the first ink used when replacing the second ink in the liquid supply path with the first ink,
The relationship between the internal volume A and the replacement amount C can be (replacement amount C> internal volume A).

[Application Example 4]
In any one of Application Examples 1 to 3,
The content [WA (mass%)] of the resin component in the first ink;
The content [WC (% by mass)] of the resin component in the ink ejected after replacing the second ink in the liquid supply path with the first ink;
Relationship
(0.95WA ≧ WC ≧ 0.50WA)
Can be.

[Application Example 5]
In any one of Application Examples 1 to 4,
The content of the alkyl polyol having a boiling point of 280 ° C. or higher at 1 atm in the ink discharged after replacing the second ink in the liquid supply path with the first ink is 2% by mass or less. it can.

[Application Example 6]
In any one of Application Examples 1 to 5,
The first ink can be recorded on a recording medium having low ink absorption or non-ink absorption.

[Application Example 7]
One aspect of the image recording method according to the present invention is:
An image recording method using the droplet discharge device according to any one of Application Example 1 to Application Example 6,
Discharging the first ink droplets from the nozzle and attaching the droplets to a recording medium;
Heating the recording medium to dry the droplets adhered to the recording medium;
including.

FIG. 3 is a schematic perspective view illustrating a main configuration part of a printer including a selection unit. FIG. 2 is a block diagram illustrating an electrical configuration of the printer illustrated in FIG. 1. The flowchart for demonstrating the flow of the process performed when it is set as the 1st filling state. The flowchart for demonstrating the flow of the process performed when it is set as the 2nd filling state. 6 is a flowchart for explaining a flow of switching processing performed before the printer is turned off.

  Hereinafter, preferred embodiments of the present invention will be described. Embodiment described below demonstrates an example of this invention. In addition, the present invention is not limited to the following embodiments, and includes various modifications that are implemented within a range that does not change the gist of the present invention. Note that not all of the configurations described in the following embodiments are indispensable constituent requirements of the present invention.

1. Droplet discharge device 1.1. Apparatus Configuration Hereinafter, a preferred embodiment of a liquid ejection apparatus will be described in detail with reference to the drawings. In addition, an ink jet printer (hereinafter referred to as “printer”) is taken as an example of the droplet discharge device, and the main configuration thereof will be described. FIG. 1 is a schematic perspective view showing main components of the printer, and FIG. 2 is a block diagram showing an electrical configuration of the printer shown in FIG.

  In this embodiment, the printer 20 having the selection unit 56 that can switch between two types of ink will be described with reference to FIGS. 1 and 2, but the selection unit included in the printer according to the present invention includes three or more types. The ink may be switched.

  In the following description, it is assumed that the first ink and the second ink have substantially the same color and each contain a resin component (described later). The content of the resin component in the first ink is higher than the content of the resin component in the second ink. In the case where the third ink is provided, the third ink is a solution having a property that hardly causes precipitation, such as a cleaning liquid.

  In the present specification, “substantially the same color” means having a hue that can be recognized as the same color by visual judgment.

  As shown in FIG. 1, the printer 20 is driven by a paper stacker 22, a paper feed roller 24 driven by a step motor (not shown), a platen 26, a carriage 28, a carriage motor 30, and a carriage motor 30. A pulling belt 32 and a guide rail 34 for guiding the scanning of the carriage 28 can be provided. A recording head 36 having a large number of nozzles is mounted on the carriage 28.

  As shown in FIG. 1, the liquid supply path 41 is a flow path that connects a nozzle (not shown) provided in the recording head 36 and the selection means 56. The recording head 36 includes cartridges 11a and 11b via a liquid supply path 41, cartridges 12a and 12b via a liquid supply path 42, cartridges 13a and 13b via a liquid supply path 43, and cartridge 14a via a liquid supply path 44. And 14b.

  As shown in FIG. 1, the cartridge 11a has black ink (K1), the cartridge 11b has black ink (K2), the cartridge 12a has cyan ink (C1), the cartridge 12b has cyan ink (C2), and the cartridge 13a has Magenta ink (M1), the cartridge 13b contains magenta ink (M2), the cartridge 14a contains yellow ink (Y1), and the cartridge 14b contains yellow ink (Y2). K1, C1, M1, and Y1 are inks corresponding to the first ink, and K2, C2, M2, and Y2 are inks corresponding to the second ink.

  Here, the ink classified into the same color is ejected from the same nozzle. For example, the black ink K1 is discharged from the same nozzle as the nozzle from which the black ink K2 is discharged among the nozzles provided in the recording head 36. The other color inks are the same as the black ink.

  A first ink and a second ink are selectively supplied to the liquid supply paths 41 to 44 via the selection means 56, respectively.

  In addition, a cartridge (not shown) is further provided, and the third ink is accommodated in the cartridge, and the first ink, the second ink, and the second ink are supplied to the nozzle from which the first ink is ejected via the selection unit 56. You may comprise so that 3 inks may be filled selectively. In this case, the selection unit 56 is appropriately configured so that the three types of ink can be switched.

  Each cartridge includes an ink pack containing each ink (image forming liquid), and an air chamber is formed around the ink pack. By pressurizing the air chamber by a pressurizing unit (not shown), the ink in each ink pack is supplied to the nozzles in the recording head 36 via the liquid supply paths 41, 42, 43, 44. Thus, in this embodiment, the printer 20 is different from a so-called on-carriage type printer in which an ink cartridge is mounted on the carriage 28, and is an off-carriage type that is fixedly mounted at a predetermined position of the main body of the printer 20. An inkjet printer is exemplified. In addition, here, a mode in which replacement is performed by ejecting (pushing out) ink from the nozzle by the pressurizing unit is illustrated, but a mode in which replacement is performed by ejecting (extracting) ink from the nozzle side using the suction unit. There may be.

  As shown in FIG. 1, one of the selecting means 56 is connected to the cartridges 11a, 11b, 12a, 12b, 13a, 13b, 14a, 14b. The other of the selection means 56 is connected to the liquid supply paths 41, 42, 43, 44. The selection unit 56 can include, for example, a valve that switches ink supplied to the liquid supply paths 41, 42, 43, 44. Thereby, the ink can be selected by opening and closing the valve, and the selected ink can be supplied to the liquid supply paths 41, 42, 43 and 44. Note that the selection unit 56 can switch the currently selected ink in all colors to another ink at once, or can switch only the ink of the selected color among the colors.

  The recording paper P (recording medium) is taken up from the paper stacker 22 by the paper feed roller 24 and fed on the surface of the platen 26 in the sub-scanning direction orthogonal to the main scanning direction of the recording head 36. The carriage 28 is pulled by a pulling belt 32 driven by a carriage motor 30 and moves in the main scanning direction along the guide rail 34.

  As shown in FIG. 2, the printer 20 includes a reception buffer memory 50 that receives a signal supplied from the host computer 90, an image buffer 54 that stores image data, and a system controller 51 that controls the operation of the entire printer 20 ( Control means), a main memory 52, and an EEPROM 53. Various operations of the printer 20 are realized by reading the firmware stored in the EEPROM 53 into the main memory 52 and executing it.

  The system controller 51 is connected to a main scanning drive circuit 61 that drives the carriage motor 30, a sub-scanning drive circuit 62 that drives the paper feed motor 31, and a head drive circuit 63 that drives the recording head 36. ing. The sub-scanning drive circuit 62, the paper feed motor 31 and the paper feed roller 24 constitute a paper feed mechanism.

  The system controller 51 controls the main scanning drive circuit 61 and the sub-scanning drive circuit 62 according to various commands included in the recording data received by the reception buffer memory 50 and setting conditions written in the EEPROM 53 in advance.

  For example, when it is set to record a high-quality image, a so-called interlace method in which an image is recorded while a raster is intermittently formed in the sub-scanning direction by the main scanning driving circuit 61 and the sub-scanning driving circuit 62. Record. It is also possible to perform so-called overlap type recording in which nozzles forming one raster are driven at intermittent timing.

  Further, the system controller 51 is connected with display means 55, selection means 56, timing means 57, and nozzle discharge inspection means 58. The display means 55 displays the display content on the liquid crystal display screen of the printer 20. Alternatively, the display content is transmitted to the printer driver 91 of the host computer 90 and displayed on the driver display screen 91. As described above, the selection unit 56 can include a switching valve, and automatically switches the liquid supplied to the liquid supply path 41 to either the first ink or the second ink in accordance with an instruction from the system controller 51. . Although not shown, the selection unit 56 may be configured to switch between three or more types of ink. The time measuring means 57 measures the time during which the liquid supply path 41 is filled with the first ink and there is no ejection operation (first filling state), that is, the standing time.

  The nozzle ejection inspecting means 58 is disposed in a non-recording area that is out of the area that can be recorded by the recording head 36 on the carriage 28. The carriage 28 moves from the recording area to the non-recording area along the main scanning direction, so that the ejection state is inspected. The nozzle discharge inspection means 58 is disposed below the recording head 36 so as to face each nozzle of the recording head 36 that has moved to the non-recording area. The nozzle ejection inspecting means 58 detects the induced current generated in the conductive ink absorber due to the proximity of the charged ink droplet and the conductive ink absorber for receiving the ink droplet ejected from each nozzle of the recording head 36. A detecting unit that performs charging, a voltage applying unit that applies a voltage to the conductive ink absorber so as to charge the ink droplet when the ink droplet is ejected from each nozzle, and a bottomed container for housing the conductive ink absorber And.

  When the charged ink droplet is ejected from each nozzle toward the conductive ink absorber, an induced current is generated in the conductive ink absorber based on an electrostatic induction phenomenon or the like as the ink droplet approaches. That is, as the ink droplet approaches, an induced current flows through the conductive ink absorber so that a charge having a polarity opposite to that of the ink droplet is induced. The nozzle clogging is inspected based on whether or not the induced current is detected.

1.2. Ink Switching Method A method of switching between the first ink and the second ink in the printer 20 having the above configuration will be described. In the liquid supply channels 41 to 44, the system controller 51 switches from the second filling state filled with the second ink to the first ink filling state filled with the first ink, or from the first filling state to the second filling. Control to switch to a state can be performed. Hereinafter, a process performed when the first filling state is set, a process performed when the second filling state is set, and a switching process performed before the printer 20 is turned off will be described.

(1) Process Performed When Entering First Filled State FIG. 3 is a flowchart for explaining the flow of the process performed when entering the first filled state. When the system controller 51 receives, for example, a signal transmitted when the printer 20 is turned on or a signal transmitted when a print job is input to the printer 20, the flow of FIG. To start.

  First, the system controller 51 reads out information on the ink currently filled in the liquid supply path stored in the EEPROM 53 (step S11).

  Next, the system controller 51 determines from the information read from the EEPROM 53 whether or not the ink filled in the liquid supply path is the first ink (step S12).

  If it is the first ink (Y in Step 12), the system controller 51 causes the nozzle discharge inspection means 58 to perform the nozzle discharge inspection (Step S15), and the nozzle filled with the first ink based on the inspection result. It is determined whether there is a nozzle missing (step 16). As will be described later, the first ink has a higher content ratio of the resin component in the ink than the second ink. Therefore, if the first ink is left as it is, the first ink is dried and solidified or thickened on the nozzle surface of the printer 20. In such a case, nozzle clogging or the like occurs, and discharge failure (nozzle omission, flight bending, etc.) occurs. From the above, when the printer 20 is left in the first filling state, it is preferable to execute the nozzle discharge inspection.

  If the system controller 51 determines that there is a missing nozzle (Y in step S16), the system controller 51 causes the nozzle to be cleaned to eliminate the missing nozzle (step S17). The cleaning of the nozzle can be performed by suction of ink in the nozzle using a suction mechanism (not shown) or a so-called flushing operation that discharges droplets from the nozzle to eliminate clogging of the nozzle. This flow is completed through these steps.

  On the other hand, if it is the second ink (N in Step 12), the system controller 51 switches the second ink in the liquid supply path to the first ink (Step S13). In step S <b> 13, the system controller 51 instructs the selection unit 56 to close the second ink side valve and open the first ink side valve. Next, the system controller 51 drives the pressurizing means (not shown) of each cartridge to supply the first ink to the liquid supply path. In this way, the first ink supplied to the liquid supply path is filled in the nozzle position. That is, the second ink that has been filled up to that point is pushed out of the nozzle by the first ink and switched to the first ink (step S13).

  Further, the system controller 51 rewrites the information of the ink filled in the liquid supply path stored in the EEPROM 53 as the first ink together with the ink switching (step 13) (step 14). In this way, this flow ends.

  In step S12 in this flow, it is assumed that switching from the second ink to the first ink has been set in advance. The setting for switching from the second ink to the first ink is performed based on input information that the first ink is used, for example. The input information is input to the system controller 51 by, for example, an operation of input means (an input means provided in the printer 20 or an input means such as a PC connected to the printer 20 by wire or wireless) by the user.

(2) Processing Performed when Entering Second Filling State FIG. 4 is a flowchart for explaining the flow of processing performed when entering the second filling state. For example, when the system controller 51 receives a signal transmitted when the printer 20 is turned on or a signal transmitted when a print job is input to the printer 20, the flow of FIG. To start.

  First, the system controller 51 reads out information on the ink currently filled in the liquid supply path stored in the EEPROM 53 (step S21).

  Next, the system controller 51 determines from the information read from the EEPROM 53 whether or not the ink filled in the liquid supply path is the second ink (step S22). If it is the second ink (Y in Step 22), this flow ends.

  On the other hand, if it is the first ink (N in Step 22), the system controller 51 switches the first ink in the liquid supply path to the second ink (Step S23). In step S <b> 23, the system controller 51 instructs the selection unit 56 to close the first ink side valve and open the second ink side valve. Next, the system controller 51 drives the pressurizing means (not shown) of each cartridge to supply the second ink to the liquid supply path. In this way, the second ink supplied to the liquid supply path is filled in the nozzle position. That is, the first ink that has been filled is pushed out from the nozzle by the second ink and switched to the second ink (step S23).

  Further, the system controller 51 rewrites the information of the ink filled in the liquid supply path stored in the EEPROM 53 as the second ink together with the ink switching (step 23) (step 24).

  Next, the system controller 51 causes the nozzle discharge inspection means 58 to perform a nozzle discharge inspection (step S25), and determines whether or not there is a missing nozzle in the nozzle filled with the second ink based on the inspection result. (Step 26). If the system controller 51 determines that there is a missing nozzle (Y in step S26), it cleans the nozzle and eliminates the missing nozzle (step S27). The cleaning of the nozzles can be performed by the same method as “1.2. Ink switching method (1) Processing in the first filling state”. This flow is completed through these steps. If the system controller 51 determines in step 26 that there is no nozzle missing (N in step S26), this flow ends.

  In step S22 in this flow, it is assumed that switching from the first ink to the second ink has been set in advance. Such a setting for switching from the first ink to the second ink can be performed by a method similar to “1.2. Ink switching method (1) Processing performed in the first filling state”. .

(3) Switching process performed before the printer 20 is turned off Next, a switching process performed before the printer 20 is turned off will be described. FIG. 5 is a flowchart for explaining the flow of switching processing performed before the printer is turned off. When the system controller 51 is instructed to turn off the power of the printer 20 from the outside (Y in step S31), the system controller 51 instructs the printer driver 91 of the host computer 90 to display a message prompting the user to input the scheduled power off duration time. (Step S32). When the user who has read the displayed message inputs the scheduled power-off duration, the input value is transmitted to the printer 20.

  When the system controller 51 detects an input (Y in step S33), the system controller 51 determines whether or not the scheduled power-off continuation time transmitted from the printer driver 91 is longer than a preset month (step S34). If the system controller 51 determines that the scheduled power off duration is 1 month or longer (Y in step S34), the system controller 51 closes the first ink side valve and opens the second ink side valve with respect to the selection means 56. Instruct. Next, a pressure unit (not shown) of the cartridge is driven to supply the second ink to the liquid supply path. Then, the second ink is filled in the nozzle position. That is, the first ink that has been filled up to that point is pushed out of the nozzle by the second ink and switched to the second ink (step 35). Further, the system controller 51 rewrites the information on the ink filled in the liquid supply path stored in the EEPROM 53 as the second ink together with the ink switching (step 35) (step 36). Then, the system controller 51 executes a power OFF process (step S37). After such steps, this flow ends.

  On the other hand, if the system controller 51 determines in step S34 that the scheduled power-off duration is shorter than one month (N in step S34), the system controller 51 performs the power-off process without switching the first ink to the second ink. Execute (step S27). After such steps, this flow ends.

  As described above, even when there is an instruction to turn off the power, it is possible to switch from the state filled with the first ink to the state filled with the second ink before executing the power-off process. That is, the second ink can be filled in the liquid supply path while the power is off. Thereby, it is possible to prevent the liquid supply path from being left for a long time while being filled with the first ink. On the other hand, when the scheduled power-off duration is shorter than one month, which is empirically obtained as the time when the nozzles are clogged, the power is turned off without being filled with the second ink. That is, since the power is turned on before the clogging occurs and the ejection operation is scheduled to be performed, the possibility of clogging is low, and the power is turned off without filling the second ink. Thereby, it is possible to prevent the second ink from being wasted.

  As described in the above (1) to (3), the printer 20 automatically switches to either the first filling state or the second filling state in accordance with an instruction from the system controller 51 under a predetermined condition. . Therefore, it is not necessary for the user to manually switch the ink. For this reason, the liquid supply path is automatically filled with the first ink or the second ink.

  Further, when the selection unit 56 is configured to switch between three or more types of ink and switches between the first ink, the second ink, and the third ink, the selection unit 56 receives an instruction from the system controller 51. Accordingly, the first filling state, the second filling state, and the third filling state in which the liquid supply path is filled with the third ink can be switched at any timing. In this way, it is possible to fill the liquid supply path with a desired type of ink.

1.3. Switching amount In the droplet discharge device according to the present embodiment, the amount of ink used for switching is set in advance based on the components contained in the ink used, the nature of the ink, the volume of the liquid supply path, and the like. This setting is input to the system controller 51 by, for example, an operation of input means (an input means provided in the printer 20 or an input means such as a PC connected to the printer 20 by wire or wireless) by the user. Can be done.

  In the droplet discharge device according to the present embodiment, the resin component content [WA (% by mass)] in the first ink is higher than the resin component content [WB (% by mass)] in the second ink. In addition, the content of the alkyl polyol having a boiling point of 280 ° C. or higher at 1 atm (hereinafter referred to as a high-boiling solvent) is higher in the second ink than in the first ink (of the high-boiling solvent in the first ink). The case where the content is 0% by mass is also included in “the second ink is higher than the first ink”). Therefore, the amount of the first ink used when replacing the second ink with the first ink is set to be larger than the amount of the second ink used when replacing the first ink with the second ink. .

  The reason for this is related to image recording performed after ink replacement. This will be specifically described below.

  The recording of the image after the second ink is replaced with the first ink to the first filling state is performed by ejecting ink (droplet) from the nozzle and attaching the ink to the recording medium. In such a case, the ink adhering to the recording medium in the initial stage of image recording is often composed of an ink in which the first ink and the second ink are mixed. Since the content rate of the resin component in the second ink is lower than the content rate of the resin component in the first ink, the content rate of the resin component in the ink in which the first ink and the second ink are mixed is It is lower than the content of the resin component in one ink. In addition, since the content of the high boiling point solvent in the first ink is lower than the content of the high boiling point solvent in the second ink, the high boiling point solvent in the ink in which the first ink and the second ink are mixed is used. The content rate is higher than the content rate of the high boiling point solvent in the first ink. Therefore, when recording on a recording medium (described later) with low ink absorption and non-ink absorption after the second ink is replaced with the first ink, the fixability and quick drying of the recorded image are reduced. There is.

  On the other hand, the image recording after the first ink is replaced with the second ink to be in the second filling state is mainly performed on an ink-absorbing recording medium (described later). Therefore, the fixability of the recorded image is less likely to be a problem than the image recording performed after the first filling state described above.

  From the above, when replacing the second ink in the liquid supply path with the first ink, the amount of the first ink used for the replacement is the same as the amount of the second ink used when replacing the first ink with the second ink. It is necessary to sufficiently replace the liquid supply path with the first ink by increasing the amount.

  Further, the internal volume A of the liquid supply path 41 connecting the selection means 56 and the nozzle is set as an internal volume A, and the replacement amount B of the second ink necessary for replacing the first ink in the liquid supply path 41 with the second ink, It is preferable that the content A> the substitution amount B. As a result, the ink ejection stability is improved while reducing the amount of ink used.

  Further, when the replacement amount C of the first ink necessary for replacing the second ink with the first ink is set, it is preferable that the replacement amount C> the internal capacity A. Thereby, the fixability of the ink discharged from the nozzle is improved.

1.4. Others In the droplet discharge device according to this embodiment, the resin component content [WA (mass%)] in the first ink and the resin component in the ink discharged after the second ink is replaced with the first ink The content ratio [WC (mass%)] is preferably 0.95WA ≧ WC ≧ 0.50WA, more preferably 0.95WA ≧ WC ≧ 0.80WA, and 0.95WA It is particularly preferred that ≧ WC ≧ 0.88WA.

  When the relationship between WA and WC is 0.95WA ≧ WC ≧ 0.50WA, the fixing property of the ink to the recording medium having low ink absorption and non-ink absorption is good, and the amount of ink used Can be reduced. Further, when the relationship between WA and WC is within the range of 0.95WA ≧ WC ≧ 0.80WA, the amount of the first ink used when replacing the second ink with the first ink is reduced, and the ink is reduced. It is possible to further improve the fixing property of the ink to the recording medium having low absorption and non-ink absorption. In particular, if the relationship between WA and WC is 0.95WA ≧ WC ≧ 0.88WA, while reducing the amount of the first ink used when replacing the second ink with the first ink, low ink absorption and It is possible to further improve the fixability of the ink onto the non-ink-absorbing recording medium.

  In the droplet discharge device according to the present embodiment, the resin component content [WB (% by mass)] in the second ink and the resin in the ink discharged after the first ink is replaced with the second ink are used. The content ratio [WD (% by mass)] of the component is preferably 3.1WB ≧ WD ≧ WB, more preferably 2.1WB ≧ WD ≧ WB, and 1.6WB ≧ WD ≧ WB is particularly preferable. When WB and WD are in the above relationship, after replacing the first ink with the second ink to the second filling state, when discharging the ink, problems such as nozzle clogging and flight bending are reduced. Can do.

  The content of the high boiling point solvent in the ink ejected after replacing the second ink with the first ink is preferably 2% by mass or less, more preferably 1.2% by mass or less, It is still more preferable that it is 0.5 mass% or less. As a result, it is possible to perform recording while maintaining quick-drying even on a recording medium with low ink absorption and non-absorption.

1.5. Composition of ink The first ink and the second ink used in the droplet discharge device according to the present embodiment have substantially the same color. Therefore, even after ink replacement, the change in the hue of the ink ejected from the nozzle can be reduced.

  The relationship between the resin component content [WA (mass%)] in the first ink and the resin component content [WB (mass%)] in the second ink is (WA> WB). is there. The content of the high boiling point solvent in the first ink is lower than the content of the high boiling point solvent in the second ink (even when the content of the high boiling point solvent in the first ink is 0% by mass, “The first ink is lower than the second ink”). For this reason, the first ink is preferably used for recording on a recording medium having low ink absorption and non-ink absorption, and the second ink is used for recording on an ink-absorbing recording medium. preferable.

  Hereinafter, the components contained in the first ink and the second ink described above will be described in detail. The first ink and the second ink may contain components that are different from each other, or may contain the same components and may have different contents. Therefore, in the following, unless otherwise specified, any one of the first ink and the second ink is simply referred to as “ink”.

(1) Resin Component The ink used for the droplet discharge device according to the present embodiment contains a resin component. One of the functions of the resin component is to solidify the ink and firmly fix the solidified ink on the recording medium. Examples of such resin components include acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester, acrylonitrile, cyanoacrylate, acrylamide, olefin, styrene, vinyl acetate, vinyl chloride, vinyl alcohol, vinyl ether, vinyl pyrrolidone, vinyl Examples thereof include homopolymers or copolymers of pyridine, vinyl carbazole, vinyl imidazole, and vinylidene chloride, modified products thereof, polyurethane, fluororesin, and natural resin. The copolymer may be in any form of a random copolymer, a block copolymer, an alternating copolymer, and a graft copolymer. When polyurethane is used as the resin, polycarbonate-based or polyether-based polyurethane is preferable in terms of good dispersibility in the ink and good adhesion to the recording medium when attached to the recording medium. Furthermore, when using polyurethane, a known method can be applied to the synthesis of the polyurethane. For example, a compound having two or more isocyanate groups is reacted with a compound having two or more hydroxyl groups. The method can be used. The ink may contain a plurality of types of resin components.

  The content of the resin component contained in the first ink is preferably 0.25 parts by mass or more and 1 part by mass or less, more preferably 0, in terms of solid content with respect to 1 part by mass of the pigment in the first ink. .3 parts by mass or more and 0.8 parts by mass or less. When the resin component in the first ink is within the above range, the first ink can be solidified and fixed even on a recording medium having low ink absorption and non-ink absorption.

  The content of the resin component contained in the second ink is preferably 0.05 parts by mass or more and 0.7 parts by mass or less, more preferably in terms of solid content, with respect to 1 part by mass of the pigment in the second ink. Is 0.1 parts by mass or more and 0.5 parts by mass or less. When the resin component in the second ink is within the above range, solidification of the ink on the nozzle surface of the droplet discharge device can be reduced.

  The content of the resin component contained in the first ink is preferably 2% by mass or more and 15% by mass or less, more preferably 3% by mass or more and 10% by mass or less in terms of solid content with respect to the total mass of the first ink. It is as follows. When the resin component in the first ink is within the above range, the first ink can be solidified and fixed even on a recording medium having low ink absorption and non-ink absorption.

  The content of the resin component contained in the second ink is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.5% by mass, in terms of solid content, with respect to the total mass of the second ink. The amount is 5% by mass or less. When the resin component in the second ink is within the above range, solidification of the ink on the nozzle surface of the droplet discharge device can be reduced.

  Note that when the droplet discharge device according to the present embodiment is configured to switch between three or more types of ink, a third ink made of a cleaning liquid can be used. The cleaning liquid is used for maintenance of the apparatus when the operation of the droplet discharge apparatus is suspended for a long period of time. Therefore, it is preferable that the cleaning liquid does not contain the resin component having properties such as solidifying ink.

(2) Water The ink used in the droplet discharge device according to this embodiment can contain water. Examples of water that can be used for the ink include pure water such as ion exchange water, ultrafiltration water, reverse osmosis water, and distilled water, or ultrapure water. In particular, water obtained by sterilizing these waters by ultraviolet irradiation or addition of hydrogen peroxide is more preferable because it can suppress the generation of mold and bacteria for a long period of time and can keep the ink stable for a long period of time.

  The water content when water is contained in the ink of the present embodiment is not limited, but is preferably 50% by mass or more and 95% by mass or less with respect to the total amount of the ink. When the content of water in the ink is within this range, for example, the dispersibility of the pigment when the pigment is blended with the ink can be enhanced, and the storage stability of the ink can be enhanced.

(3) Alkyl polyol having a boiling point of 280 ° C. or higher under 1 atm (high boiling point solvent)
The first ink used in the droplet discharge device according to the present embodiment does not substantially contain an alkyl polyol (high boiling point solvent) having a boiling point of 280 ° C. or higher under 1 atm. A typical example of the high boiling point solvent is glycerin (boiling point: 290 ° C.).

  In the present specification, “substantially does not contain” means that the ink contains 0.1% by mass or more, more preferably 0.05% by mass or less, and still more preferably 0.01% by mass. It means not containing more than%.

  The first ink is often used for recording on a recording medium having low ink absorption and non-ink absorption. A recording medium with low ink absorbability and non-ink absorbability has a property that ink does not easily permeate, and thus may not be excellent in drying property of the adhered ink. For this reason, the first ink used in the droplet discharge device according to the present embodiment contains a high boiling point solvent in order to improve the drying property when adhering to a low-ink-absorbing and non-ink-absorbing recording medium. Does not contain substantially.

  On the other hand, since the second ink used in the droplet discharge device according to the present embodiment is preferably used for an ink-absorbing recording medium, it is an object to reduce drying and solidification of ink on the nozzle surface of the head. First, it contains a high boiling point solvent. The content of the high boiling point solvent in the second ink is preferably 0.1% by mass or more and 20% by mass or less with respect to the total mass of the ink.

(4) Organic solvent The ink used for the droplet discharge device according to the present embodiment can contain an organic solvent. The ink may contain a plurality of types of organic solvents. One of the functions of the organic solvent is to prevent clogging or ejection failure by suppressing the drying and solidification of the ink on the nozzle surface of the head. The organic solvent is a solvent different from the surfactant described later.

  Examples of the organic solvent include ethylene glycol (boiling point: 197 ° C.), diethylene glycol (boiling point: 244 ° C.), propylene glycol (boiling point: 188 ° C.), dipropylene glycol (boiling point: 232 ° C.), 1,3-propanediol ( Boiling point: 210 ° C., 1,4-butanediol (boiling point: 230 ° C.), polyhydric alcohols such as 1,6-hexanediol (boiling point: 208 ° C.), triethanolamine (boiling point: 335 ° C.), etc. An organic amine is mentioned.

  When the organic solvent is contained in the ink, the content of the organic solvent is preferably 0.1% by mass or more and 20% by mass or less with respect to the total mass of the ink.

  The first ink preferably does not contain an organic solvent having a boiling point of 280 ° C. or higher under 1 atm, and more preferably does not contain 1.0% by mass or more. It is most preferable not to contain more than 5% by mass. Accordingly, it is possible to further improve the drying property when the first ink adheres to the recording medium having low ink absorption and non-ink absorption. Examples of the organic solvent having a boiling point of 280 ° C. or higher at 1 atm include the above-mentioned triethanolamine (boiling point: 335 ° C.).

(5) 1,2-Alkanediol The ink used in the liquid droplet ejection apparatus according to the present embodiment can contain 1,2-alkanediol. 1,2-alkanediols are excellent in the action of increasing the wettability of the ink with respect to the recording medium having low ink absorption and non-ink-absorbing recording, so that an excellent image is formed on the recording medium. can do.

  Examples of 1,2-alkanediols include 1,2-propanediol (boiling point: 188 ° C.), 1,2-butanediol (boiling point: 194 ° C.), and 1,2-pentanediol (boiling point: 206 ° C.). 1,2-hexanediol (boiling point: 223 ° C.), 1,2-octanediol (boiling point: 131 ° C.), and the like. When 1,2-alkanediols are contained in the ink, the content of 1,2-alkanediols is preferably 1% by mass or more and 20% by mass or less with respect to the total mass of the ink. .

(6) Pyrrolidone derivative The ink used in the droplet discharge device according to the present embodiment can contain a pyrrolidone derivative. The pyrrolidone derivative acts as a good solubilizer for the recording medium, and can improve the fixability of the ink to the recording medium. Examples of pyrrolidone derivatives include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-pyrrolidone, N-butyl-2-pyrrolidone, 5-methyl-2-pyrrolidone, etc. Is mentioned. When the pyrrolidone derivative is contained in the ink, the content of the pyrrolidone derivative is preferably 1% by mass or more and 20% by mass or less with respect to the total mass of the ink.

(7) Surfactant The ink used in the droplet discharge device according to the present embodiment can contain a surfactant. The surfactant can improve the ink wettability with respect to the recording medium and improve the permeability of the ink into the recording medium. In the present invention, the surfactant is distinguished from the above-mentioned organic solvent as a separate solvent. The surfactant that can be used in the ink of the present embodiment is not particularly limited, and examples thereof include the following.

  Examples of the anionic surfactant include alkyl sulfocarboxylates, 瘁 | olefin sulfonates, polyoxyethylene alkyl ether acetates, N-acyl amino acids and salts thereof, N-acyl methyl taurates, alkyl sulfates. Polyoxyalkyl ether sulfate, alkyl sulfate polyoxyethylene alkyl ether phosphate, rosin acid soap, castor oil sulfate ester, lauryl alcohol sulfate ester, alkylphenol type phosphate ester, alkyl type phosphate ester, alkylaryl sulfonate, Examples include diethylsulfosuccinate, diethylhexylsulfosuccinate, dioctylsulfosuccinate, 2-vinylpyridine derivatives, poly-4-vinylpyridine derivatives, and fluorosurfactants.

  Among the fluorosurfactants, sodium fluoroalkylbenzenesulfonate, fluoroalkylphosphonic acid, sodium fluoroalkylcarboxylate, fluoroalkylpolyoxyethylene ether, fluoroalkylammonium iodide, fluoroalkylbetaine, and the like are particularly preferable. Is a sodium fluoroalkylbenzenesulfonate having high water solubility.

  Examples of amphoteric surfactants include lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, polyoctylpolyaminoethylglycine and other imidazolines. Derivatives and the like can be mentioned.

  Examples of the nonionic surfactant include polyoxyethylene nonyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl aryl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, Ethers such as polyoxyalkylene alkyl ether, polyoxyethylene oleate, polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, poly Esters such as oxyethylene monooleate and polyoxyethylene stearate, acetylene glycol surfactants, And the like polysiloxane-based surfactant.

  Among these surfactants, the acetylene glycol surfactant and the surfactant are particularly excellent in the effect of improving the wettability of the ink to the recording medium and improving the permeability of the ink into the recording medium. At least one polysiloxane surfactant can be preferably used.

  Examples of the acetylene glycol surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3, Examples include 5-dimethyl-1-hexyn-3-ol, 2,4-dimethyl-5-hexyn-3-ol, and the like. Moreover, a commercial item can also be utilized for acetylene glycol type-surfactant, for example, Orphine E1010, STG, Y (above, Nissin Chemical Co., Ltd. product), Surfinol 104, 82, 465, 485, TG (above , Air Products and Chemicals Inc.).

  Commercially available products can be used as the polysiloxane surfactant, and examples thereof include BYK-347, BYK-348, BYK-UV3500 (manufactured by Big Chemie Japan Co., Ltd.) and the like.

  When the surfactant is contained in the ink, the content of the surfactant is preferably 0.01% by mass or more and 5% by mass or less, more preferably 0.1% by mass with respect to the total mass of the ink. % To 3% by mass.

(8) Coloring material The ink of the present embodiment may contain at least one selected from pigments, dyes, metal oxides, and particles having a hollow structure as a coloring material. When a color material is contained in the ink, the content of the color material is preferably 1% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 15% by mass or less with respect to the total mass of the ink. .

(I) Pigment The pigment that can be used in the present embodiment is not particularly limited, and examples thereof include inorganic pigments and organic pigments.

  As the inorganic pigment, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black and channel black, iron oxide, and titanium oxide can be used.

  Organic pigments include insoluble azo pigments, condensed azo pigments, azo lakes and chelate azo pigments, phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone. Polycyclic pigments such as pigments, dye chelates (for example, basic dye type chelates, acidic dye type chelates), dyeing lakes (basic dye type lakes, acid dye type lakes), nitro pigments, nitroso pigments, aniline black, A daylight fluorescent pigment is mentioned. The said pigment may be used individually by 1 type, and may use 2 or more types together.

  More specifically, examples of the inorganic pigment used for black include the following carbon blacks, for example, No. manufactured by Mitsubishi Chemical. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, or No2200B, etc .; Columbia Raven5750, Raven5250, Raven5000, Raven3500, Raven1255, Raven700, etc .; Cabot Regal 400R, Regal 330R, Regal 660L, Monal 660R 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc .; or Color Black FW1, Color Black FW2, Clk Black FW2C, Decksa's Color Black FW2 FW200, Color Black S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6, and Special Black 5S.

  Examples of yellow organic pigments include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, 120, 124, 128, 129, 133, 138, 139, 147, 151, 153, 154, 155, 167, 172, 180, 185, 213 and the like.

  Examples of magenta organic pigments include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 88, 112, 114, 122, 123, 144, 146, 149, 150, 166, 168 170, 171, 175, 176, 177, 178, 179, 184, 185, 187, 202, 209, 219, 224, 245, 254, 264 or C.I. I. Pigment violet 19, 23, 32, 33, 36, 38, 43, 50 and the like.

  Examples of cyan organic pigments include C.I. I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 15:34, 16, 18, 22, 25, 60, 65, 66, C.I. I. Bat Blue 4, 60 and the like.

  Examples of organic pigments other than magenta, cyan and yellow include C.I. I. Pigment green 7, 10, C.I. I. Pigment brown 3, 5, 25, 26, C.I. I. Pigment orange 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, 63, and the like.

(Ii) Dyes As dyes, various dyes used for normal ink jet recording such as direct dyes, acid dyes, food dyes, basic dyes, reactive dyes, disperse dyes, vat dyes, soluble vat dyes, reactive disperse dyes, etc. Can be used.

  Examples of yellow dyes include C.I. I. Acid Yellow 1, 3, 11, 17, 19, 23, 25, 29, 36, 38, 40, 42, 44, 49, 59, 61, 70, 72, 75, 76, 78, 79, 98, 99, 110, 111, 127, 131, 135, 142, 162, 164, 165, C.I. I. Direct Yellow 1, 8, 11, 12, 24, 26, 27, 33, 39, 44, 50, 58, 85, 86, 87, 88, 89, 98, 110, 132, 142, 144, C.I. I. Reactive Yellow 1, 2, 3, 4, 6, 7, 11, 12, 13, 14, 15, 16, 17, 18, 22, 23, 24, 25, 26, 27, 37, 42, C.I. I. Food Yellow 3, 4, C.I. I. Solvent yellow 15, 19, 21, 30, 109 etc. are mentioned.

  Examples of magenta dyes include C.I. I. Acid Red 1, 6, 8, 9, 13, 14, 18, 26, 27, 32, 35, 37, 42, 51, 52, 57, 75, 77, 80, 82, 85, 87, 88, 89, 92, 94, 97, 106, 111, 114, 115, 117, 118, 119, 129, 130, 131, 133, 134, 138, 143, 145, 154, 155, 158, 168, 180, 183, 184, 186, 194, 198, 209, 211, 215, 219, 249, 252, 254, 262, 265, 274, 282, 289, 303, 317, 320, 321, 322, C.I. I. Direct Red 1, 2, 4, 9, 11, 13, 17, 20, 23, 24, 28, 31, 33, 37, 39, 44, 46, 62, 63, 75, 79, 80, 81, 83, 84, 89, 95, 99, 113, 197, 201, 218, 220, 224, 225, 226, 227, 228, 229, 230, 231, C.I. I. Reactive Red 1, 2, 3, 4, 5, 6, 7, 8, 11, 12, 13, 15, 16, 17, 19, 20, 21, 22, 23, 24, 28, 29, 31, 32 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 45, 46, 49, 50, 58, 59, 63, 64, C.I. I. Sorbize red 1, C.I. I. Food red 7, 9, 14 etc. are mentioned.

  Examples of cyan dyes include C.I. I. Acid Blue 1, 7, 9, 15, 22, 23, 25, 27, 29, 40, 41, 43, 45, 54, 59, 60, 62, 72, 74, 78, 80, 82, 83, 90, 92, 93, 100, 102, 103, 104, 112, 113, 117, 120, 126, 127, 129, 130, 131, 138, 140, 142, 143, 151, 154, 158, 161, 166, 167, 168, 170, 171, 182, 183, 184, 187, 192, 199, 203, 204, 205, 229, 234, 236, 249, C.I. I. Direct Blue 1, 2, 6, 15, 22, 25, 41, 71, 76, 77, 78, 80, 86, 87, 90, 98, 106, 108, 120, 123, 158, 160, 163, 165, 168, 192, 193, 194, 195, 196, 199, 200, 201, 202, 203, 207, 225, 226, 236, 237, 246, 248, 249, C.I. I. Reactive Blue 1, 2, 3, 4, 5, 7, 8, 9, 13, 14, 15, 17, 18, 19, 20, 21, 25, 26, 27, 28, 29, 31, 32, 33 , 34, 37, 38, 39, 40, 41, 43, 44, 46, C.I. I. Solvize Bat Blue 1, 5, 41, C.I. I. Bat Blue 4, 29, 60, C.I. I. Food Blue 1, 2, C.I. I. Basic blue 9, 25, 28, 29, 44 etc. are mentioned.

  Examples of dyes other than magenta, cyan and yellow include C.I. I. Acid Green 7, 12, 25, 27, 35, 36, 40, 43, 44, 65, 79, C.I. I. Direct Green 1, 6, 8, 26, 28, 30, 31, 37, 59, 63, 64, C.I. I. Reactive Green 6, 7, C.I. I. Acid Violet 15, 43, 66, 78, 106, C.I. I. Direct violet 2, 48, 63, 90, C.I. I. Reactive violet 1, 5, 9, 10, C.I. I. Direct black 154 etc. are mentioned.

(Iii) Metal oxide particles Examples of the metal oxide particles include titanium dioxide, zinc oxide, alumina, and magnesium oxide.

The average particle diameter (d ₅₀ ) of the metal oxide particles is preferably 30 nm or more and 600 nm or less, and more preferably 200 nm or more and 400 nm or less. When the average particle diameter exceeds the above range, the dispersion stability may be impaired due to precipitation of particles in the ink composition, and the reliability such as clogging of the head may be impaired. On the other hand, if the average particle size is less than the above range, a desired color may not be obtained.

  The average particle diameter of the metal oxide particles can be measured with a particle size distribution measuring apparatus based on a laser diffraction / scattering method. Examples of the particle size distribution measuring apparatus include a particle size distribution meter (for example, “Microtrack UPA” manufactured by Nikkiso Co., Ltd.) having a dynamic light scattering method as a measurement principle.

(Iv) Particles having a hollow structure The particles having a hollow structure are not particularly limited, and known ones such as those formed from an organic compound such as styrene-acrylic resin and those formed from an inorganic compound are used. be able to.

  As the particles having a hollow structure and made of an organic compound, for example, particles described in specifications such as US Pat. No. 4,880,465 and Japanese Patent No. 3,562,754 can be preferably used. A method for preparing particles having a hollow structure and made of an organic compound is not particularly limited, and a known method can be applied.

  Commercially available particles may be used as the particles having a hollow structure and made of an inorganic compound. When manufacturing the particle | grains which have a hollow structure and consist of an inorganic compound, it does not specifically limit as the manufacturing method, A well-known method is applicable.

The average particle diameter (outer diameter) (d ₅₀ ) of the particles having a hollow structure is preferably 200 nm or more and 1000 nm or less, more preferably 400 nm or more and 800 nm or less, and particularly preferably 600 nm or more and 800 nm or less. preferable. If the outer diameter of the particles having a hollow structure is within the above range, the dispersion in the white ink can be kept good, and an image with good whiteness can be obtained when attached to the recording medium. Can do. The inner diameter of the particles having a hollow structure is suitably about 100 nm to 800 nm. The average particle size d ₅₀ of the particles having a hollow structure can be measured by the same method as the average particle size d ₅₀ of the metal oxide particles.

(9) Other components When the ink of the present embodiment contains a pigment, a pigment dispersant for dispersing the pigment may be added. As a preferable dispersant, a dispersant conventionally used for preparing a pigment dispersion, for example, a polymer dispersant can be used. As such a dispersant, any dispersant used in normal ink can be used. The content of the pigment dispersant in the ink is 5% by mass or more and 200% by mass or less, preferably 30% by mass or more and 120% by mass or less, based on the content of the pigment in the ink. It is advisable to select appropriately depending on the pigment to be used.

  In addition, the ink used in the droplet discharge device according to the present embodiment may further contain a pH adjuster, polyolefin wax, antiseptic / antifungal agent, rust inhibitor, chelating agent, and the like. Addition of these materials is preferable from the viewpoint of further improving the properties of the ink.

  Examples of the pH adjuster include potassium dihydrogen phosphate, disodium hydrogen phosphate, sodium hydroxide, lithium hydroxide, potassium hydroxide, ammonia, diethanolamine, triethanolamine, triisopropanolamine, potassium carbonate, sodium carbonate, Examples thereof include sodium hydrogen carbonate.

  Examples of polyolefin waxes include waxes produced from olefins such as ethylene, propylene, butylene or derivatives thereof and copolymers thereof, specifically, polyethylene waxes, polypropylene waxes, polybutylene waxes, and the like. As the polyolefin wax, commercially available products can be used. Specifically, Nopcoat PEM17 (trade name, manufactured by San Nopco Co., Ltd.), Chemipearl W4005 (trade name, manufactured by Mitsui Chemicals, Inc.), AQUACER 515, AQUACER 593 (The product name, manufactured by Big Chemie Japan Co., Ltd.) can be used.

  Examples of antiseptics and fungicides include sodium benzoate, sodium pentachlorophenol, 2-pyridinethiol-1-oxide sodium, sodium sorbate, sodium dehydroacetate, 1,2-dibenzisothiazoline-3-one Etc. Examples of commercially available products include Proxel XL2, Proxel GXL (above trade name, manufactured by Avicia), Denside CSA, NS-500W (above trade name, manufactured by Nagase ChemteX Corporation), and the like.

  Examples of the rust inhibitor include benzotriazole.

  Examples of the chelating agent include ethylenediaminetetraacetic acid and salts thereof (such as ethylenediaminetetraacetic acid dihydrogen disodium salt).

2. Image Recording Method (1) Image Recording Method Using First Ink An image recording method (hereinafter also referred to as “image recording method using first ink”) according to an embodiment of the present invention is the above-described droplet discharge. A step of discharging a first ink droplet from a nozzle and attaching the droplet to a recording medium (hereinafter also referred to as an “attaching step”), and heating the recording medium. And a step of drying the droplets attached to the recording medium (hereinafter also referred to as “drying step”). Through this step, an image can be formed on the recording medium. In addition, the printer 20 shown as one aspect | mode of the droplet discharge apparatus mentioned above can be used for the droplet discharge apparatus used for the image recording method using 1st ink.

  Drying of the droplets adhering to the recording medium can be performed, for example, by a heating unit (not shown) provided in the printer 20.

  As a heating method by the heating unit, for example, a method in which a heat source is brought into direct contact with a recording medium and heating is performed. And a method of blowing warm air. These methods can be used alone or simultaneously. Thereby, the drying temperature at the time of recording can be adjusted.

  In the case where the printer 20 does not have a heating unit, the recording medium to which the droplets are attached may be dried with a dryer or a thermostat set to a predetermined temperature.

  The heating temperature of the recording medium is 40 ° C. or higher, preferably 40 ° C. or higher and 80 ° C. or lower, more preferably 40 ° C. or higher and 60 ° C. or lower. If the heating temperature of the recording medium is 40 ° C. or higher, it is possible to effectively promote evaporation and scattering of the liquid medium in the ink.

  The heating time of the recording medium is not particularly limited as long as the liquid medium present in the ink can be evaporated and scattered and the curing of the resin component can be promoted.

  Examples of the recording medium used in the image recording method using the first ink include an ink-absorbing recording medium, and an ink non-absorbing and ink low-absorbing recording medium.

  Since the image recording method using the first ink includes a drying step, it is preferable that the image recording method is performed using a low-ink-absorbing and non-ink-absorbing recording medium among the above-described recording media. This is because a low-ink-absorbing and non-ink-absorbing recording medium has poor ink absorptivity and does not have excellent drying properties of the attached ink.

  Examples of the ink-absorbing recording medium include plain paper such as electrophotographic paper, inkjet paper (an ink absorbing layer composed of silica particles or alumina particles, or polyvinyl alcohol (PVA) or polyvinyl pyrrolidone (PVP)). Inkjet special paper provided with an ink absorbing layer composed of a hydrophilic polymer).

  Examples of the recording medium having low ink absorption include printing paper such as art paper, coated paper, and matte paper.

  As a non-ink-absorbing recording medium, for example, a plastic film is coated on a substrate such as a plastic film or paper that is not surface-treated for inkjet printing (that is, has no ink-absorbing layer formed). And those to which a plastic film is bonded. Examples of the plastic here include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene.

  Here, in this specification, the “ink-absorbing and non-ink-absorbing recording medium” means “the water absorption amount from the start of contact to 30 msec1 / 2 in the Bristow method is 10 mL / m 2 or less. Recording medium ". This Bristow method is the most popular method for measuring the amount of liquid absorbed in a short time, and is also adopted by the Japan Paper Pulp Technology Association (JAPAN TAPPI). For details of the test method, refer to Standard No. of “JAPAN TAPPI Paper Pulp Test Method 2000”. 51 "Paper and paperboard-Liquid absorbency test method-Bristow method".

(2) Image Recording Method Using Second Ink An image recording method using the second ink is performed using the above-described droplet discharge device, and the droplets of the second ink are discharged from the nozzles, and the liquid A step of attaching a droplet to a recording medium. Through this step, an image can be formed on the recording medium. Since the image recording method using the second ink is mainly used for recording on an ink-absorbing recording medium, it is not necessary to include the heating step described in the image recording method using the first ink.

3. EXAMPLES Hereinafter, the present invention will be specifically described by the following experimental examples, but the present invention is not limited to these examples.

3.1. Preparation of ink In the compounding amounts shown in Table 1, a color material, a resin component, an organic solvent, 1,2-hexanediol, 2-pyrrolidone, a surfactant, ion-exchanged water, and the like are mixed and stirred to form a metal filter having a pore size of 5 μm. The solution was filtered and degassed using a vacuum pump. In this way, the first ink and the second ink were prepared. In addition, the unit of the density | concentration described in Table 1 is the mass%.

Each component shown in Table 1 is as follows.
-Titanium dioxide pigment (trade name “NanoTek® Slurry” manufactured by C-I Kasei Co., Ltd., solid content concentration 15%, average particle size 300 nm)
Urethane resin (Mitsui Chemicals, trade name “W635”, particle size 150 nm)
-Glycerin-Propylene glycol-1,2-hexanediol-2-pyrrolidone-BYK-348 (trade name, manufactured by Big Chemie Japan, polysiloxane surfactant)
-Ion-exchanged water Titanium dioxide pigment is a dispersion in which titanium dioxide particles are dispersed in a dispersion solvent. Each ink was added so that the content of titanium dioxide particles (solid content) was 10% by mass in terms of solid content.

3.2. Comparative test of rubbing resistance An ink jet printer having a selection means 56 as shown in FIG. 1 is prepared, the cartridge 11a is filled with the first ink, the first ink is ejected from the recording head 36, and a PET film. A solid pattern image composed of the first ink was recorded on (trade name “Lumirror”, manufactured by Toray Industries, Inc.). In this way, Sample 1 for a comparative test of abrasion resistance was obtained. Note that the recording was performed at a resolution of 1440 × 720 dpi and 100% duty.

  “Duty” is a value calculated by the following equation (1).

duty (%) = number of actual recording dots / (vertical resolution × horizontal resolution) × 100 (1)
(In the formula, “number of actual recording dots” is the number of actual recording dots per unit area, and “vertical resolution” and “horizontal resolution” are resolutions per unit area, respectively.)

  Separately, a solid pattern image made of the second ink was recorded on a PET film (trade name “Lumirror”, manufactured by Toray Industries, Inc.) with the print head 36 being completely filled with the second ink. In this way, Sample 2 for a comparative test of abrasion resistance was obtained. Recording was performed under the same conditions as in sample 2.

About sample 1 and sample 2 obtained, white cotton cloth for friction (Kanakin No. 3) under the conditions of Gakushin type friction fastness tester AB-301 (manufactured by Tester Sangyo Co., Ltd., load 200 g, number of frictions 10 times) The surface of the image was visually observed and the evaluation results are shown in Table 2. The evaluation criteria are as follows.
A: No peeling of the image is observed B: 10% or more of the image peels off C: 50% or more of the image peels off D: 70% or more of the image peels off

3.3. Replacement of the second ink with the first ink (1) Scratch resistance test The selection means 56 enables the second ink to be supplied to the recording head 36, and the recording head 36, the supply path 41, and the selection means 56 are replaced with the second ink. Filled with ink. Next, an operation of replacing the second ink with the first ink was performed by the selection means 56 so that the first ink could be supplied to the recording head 36. The amount of the first ink used for the substitution was measured when the total content of the liquid supply paths was 100.

  Specifically, the ink is ejected from the nozzle when the supply amount of the first ink becomes 0, 70, 150, 200, 240, and is recorded on a PET film (trade name “Lumirror”, manufactured by Toray Industries, Inc.). This produced a sample for evaluation. The recording was performed at a resolution of 1440 × 720 dpi, and the recording pattern was a 100% duty solid pattern.

  The obtained sample for evaluation was subjected to a rub resistance test in the same manner as in “3.2. Comparative test of rub resistance”. The evaluation results are shown in Table 3. The evaluation criteria are the same as those in “3.2. Comparative test of abrasion resistance”.

(2) Measurement of WC value After replacing the second ink with the first ink under the same conditions as in “3.3. Replacement of the second ink with the first ink (1) Rubbing resistance test”, For every two ink supply amounts, 1 ml of ink first ejected from the recording head 36 was stored in a sample bottle. And the content rate [WC (mass%)] of the resin component in the obtained ink and the content rate (mass%) of glycerol were measured. The evaluation results are shown in Table 3.

  In Table 3, it can be said that as the value of [(WC / WA) × 100] increases and the glycerin content decreases, the replacement from the second ink to the first ink proceeds.

3.4. Replacement of the first ink with the second ink (1) Ejection stability test The selection means 56 enables the first ink to be supplied to the recording head 36, and the recording head 36, the supply path 41, and the selection means 56 are Filled with ink. Next, the selection means 56 made it possible to supply the second ink to the recording head 36, and an operation of replacing the first ink with the second ink was performed. The amount of the second ink used for the substitution was measured when the total content of the liquid supply path 41 was 100.

Specifically, when the supply amount of the second ink becomes 0, 70, 120, 150, the ink is ejected from the nozzle and continuously on 10 sheets of A4 paper (product name “XeroxP” manufactured by Fuji Xerox Co., Ltd.). Images were recorded. At this time, nozzle dropout and flight bending were observed to evaluate discharge stability. The evaluation results are shown in Table 4. The evaluation criteria are as follows.
A: No missing nozzle and no flying curve B: No missing nozzle, but flying curve C: No more than 10 nozzles are missing D: No more than 90 nozzles are missing

(2) Measurement of WD value After replacing the first ink with the second ink under the same conditions as in “3.4. Replacement of the first ink with the second ink (1) Ejection stability test”, For every two ink supply amounts, 1 ml of ink first ejected from the recording head 36 was stored in a sample bottle. And the content rate [WD (mass%)] of the resin component in the obtained ink and the content rate (mass%) of glycerol were measured. The evaluation results are shown in Table 4.

  In Table 4, it can be said that as the value of [(WD / WB) × 100] decreases and the content of glycerin increases, the replacement from the first ink to the second ink proceeds.

3.5. Evaluation Results The evaluation results in Table 2 showed that the first ink was excellent in fixability because it was excellent in abrasion resistance with respect to a non-ink-absorbing recording medium.

  From the evaluation results in Table 3, it is necessary to replace the second ink with the first ink in order that the first ink requires 240 in order for the fixing performance required for the first ink to be the highest standard. Indicated. On the other hand, from the evaluation results in Table 4, when replacing the first ink with the second ink, 150 second ink is required in order to achieve the highest standard of ejection stability required for the second ink. It was shown that there is. As described above, the amount of the first ink used for replacement of the second ink with the first ink needs to be larger than the amount of the second ink used for switching from the first ink to the second ink. It was shown that. Further, it was found that the replacement amount of the second ink requires a value exceeding 100 for the replacement of the second ink with the first ink.

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

11a, 11b, 12a, 12b, 13a, 13b, 14a, 14b ... cartridge, 20 ... printer, 22 ... paper stacker, 24 ... paper feed roller, 26 ... platen, 28 ... carriage, 30 ... carriage motor, 31 ... paper feed Motor 32 traction belt 34 guide rail 36 recording head 41, 42, 43, 44 liquid supply path 50 reception buffer memory 51 system controller 52 main memory 53 EEPROM 54 ... Image buffer, 55 ... Display means, 56 ... Selection means, 57 ... Timekeeping means, 58 ... Nozzle inspection means, 61 ... Main scanning drive circuit, 62 ... Sub-scanning drive circuit, 63 ... Head drive circuit, 90 ... Host computer, 91: Printer driver, P: Recording medium

Claims (7)

Selecting means for selecting one kind of ink from a plurality of kinds of ink;
A nozzle for discharging the ink circulated from the selection means;
A liquid supply path connecting the selection means and the nozzle;
Have
Of the plurality of types of inks, the first ink and the second ink are substantially the same color and contain a resin component,
The first ink substantially does not contain an alkyl polyol having a boiling point under 1 atm of 280 ° C. or higher,
The second ink contains an alkyl polyol having a boiling point under 1 atm of 280 ° C. or higher,
The relationship between the content [WA (mass%)] of the resin component in the first ink and the content [WB (mass%)] of the resin component in the second ink is (WA> WB). ), And
The amount of the first ink used when replacing the second ink in the liquid supply path with the first ink is the same as the first ink used when replacing the first ink in the liquid supply path with the second ink. A droplet discharge device having more than two inks. In claim 1,
When the internal volume of the liquid supply path is an internal volume A, and the replacement amount B of the second ink used when replacing the first ink in the liquid supply path with the second ink,
The droplet discharge device, wherein the relationship between the internal volume A and the replacement amount B is (internal volume A> replacement amount B). In claim 1 or claim 2,
When the internal volume of the liquid supply path is an internal volume A and the replacement amount C of the first ink used when replacing the second ink in the liquid supply path with the first ink,
The liquid droplet ejection apparatus, wherein the relationship between the internal volume A and the replacement amount C is (replacement amount C> internal volume A). In any one of Claims 1 thru | or 3,
The content [WA (mass%)] of the resin component in the first ink;
The content [WC (% by mass)] of the resin component in the ink ejected after replacing the second ink in the liquid supply path with the first ink;
Relationship
(0.95WA ≧ WC ≧ 0.50WA)
A droplet discharge device. In any one of Claims 1 thru | or 4,
The content of the alkyl polyol having a boiling point of 280 ° C. or higher at 1 atm in the ink ejected after replacing the second ink in the liquid supply path with the first ink is 2% by mass or less. Drop ejection device. In any one of Claims 1 thru | or 5,
The first ink is a droplet discharge device which is recorded on a recording medium having low ink absorption or non-ink absorption. An image recording method using the droplet discharge device according to any one of claims 1 to 6,
Discharging the first ink droplets from the nozzle and attaching the droplets to a recording medium;
Heating the recording medium to dry the droplets adhered to the recording medium;
An image recording method comprising:

Images