Inkjet recording method

Abstract

An inkjet recording method includes: ejecting aqueous ink from a liquid ejection head; and ejecting an aqueous reaction liquid containing a reactant that reacts with the aqueous ink from the liquid ejecting head, in which the liquid ejecting head configured to eject the aqueous reaction liquid includes: an element substrate; a nozzle having a nozzle configured to eject an aqueous reaction liquid, a pressure chamber configured to supply the aqueous reaction liquid to the nozzle, and an energy generating element configured to generate energy to eject the aqueous reaction liquid; an upstream channel configured to supply an aqueous reaction liquid to the pressure chamber; and a downstream passage communicating with the pressure chamber, the element substrate having a surface configured to face the recording medium, and the spout being positioned closer to the pressure chamber than the surface in a direction perpendicular to the surface.

Description

Technical Field

[0001] The present disclosure relates to an inkjet recording method. Background Art

[0002] In recent years, inkjet recording methods have been increasingly used in the field of signs and displays, such as the printing of large-format advertisements and posters. The recording area in this field is characterized by being larger than the recording area of ​​home inkjet recording devices. Moreover, since the image needs to be eye-catching, ink that can record images with high color development properties is required.

[0003] In the field of signs and displays, non-absorbent recording media formed of vinyl chloride (PVC), polyethylene terephthalate (PET), etc. are often used, and the surface of the non-absorbent recording medium has almost no ink absorbency. Therefore, it is necessary to suppress the blurring and unevenness of the image on the non-absorbent recording medium. The recording medium with almost no ink absorbency on the surface is also referred to as "non-absorbent recording medium" hereinafter. In the inkjet recording method for recording on the non-absorbent recording medium, it is important to prevent the ink dots from being repelled on the recording medium, thereby suppressing blurring. For this reason, it is necessary to quickly thicken and fix the ink applied to the recording medium.

[0004] As a method for recording on a non-absorbent recording medium, a recording method using a solvent-based ink mainly including an organic solvent or a curable ink containing a polymerizable monomer is known. However, in recent years, from the perspective of environmental load and safety, there is an increasing demand for a recording method for recording on a non-absorbent recording medium using an aqueous ink.

[0005] The method for recording on a non-absorbent recording medium using aqueous ink may be a method of evaporating the water in the ink on the surface of the non-absorbent recording medium, or a method of condensing the components of the ink using a reaction liquid. The former is advantageous from the perspective of running cost because it is not necessary to provide a unit for applying the reaction liquid, but the productivity is poor because the recording speed needs to be reduced. Therefore, methods using a reaction liquid have been studied.

[0006] Furthermore, in order to improve productivity, it is necessary to shorten the time required for maintenance of the liquid ejection head and realize continuous recording. The liquid ejection head must be maintained to suppress the degradation of ejection performance due to thickening of the reaction liquid or ink or due to solidification of components such as pigments or resins in the reaction liquid or ink in ejection ports that are not mainly used during continuous recording. Therefore, there is a need for an inkjet recording method using a reaction liquid that can maintain stable ejection without interrupting recording even in long-term continuous recording.

[0007] A liquid ejection head having a mechanism for inducing ink flow near a nozzle of the liquid ejection head to suppress stagnation of ink components (such as pigments or resins) in an ink channel of the liquid ejection head has been proposed (see Japanese Patent Laid-Open No. 2007-118611). In addition, in order to improve the cleaning recovery of the nozzle for ejecting a reaction liquid, an inkjet recording method using a liquid ejection head having a circulation channel has been proposed (see Japanese Patent Laid-Open No. 2020-104487). Summary of the invention

[0008] The present inventors have found that a liquid ejecting head having only a circulation channel can have a certain intermittent ejection stability in a liquid ejecting head using a reaction liquid, but may cause image unevenness.

[0009] Therefore, the present disclosure provides an inkjet recording method in which a reaction liquid or ink has high ejection stability.

[0010] The present disclosure discloses an inkjet recording method, comprising: ejecting aqueous ink from a liquid nozzle; and ejecting an aqueous reaction liquid from the liquid nozzle, the aqueous reaction liquid containing a reactant that reacts with the aqueous ink, wherein the liquid nozzle configured to eject the aqueous reaction liquid comprises: an element substrate having a nozzle configured to eject the aqueous reaction liquid, a pressure chamber configured to supply the aqueous reaction liquid to the nozzle, and an energy generating element configured to generate energy for ejecting the aqueous reaction liquid; an upstream channel configured to supply the aqueous reaction liquid to the pressure chamber; and a downstream channel connected to the pressure chamber, the element substrate having a surface configured to face a recording medium in the ejection direction of the aqueous reaction liquid, and the nozzle being positioned to be closer to the pressure chamber than the surface in a direction perpendicular to the surface.

[0011] Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a view of a liquid ejection device according to the present disclosure.

[0013] Figure 2 is a conceptual diagram of a control system according to the present disclosure.

[0014] Figure 3 is a schematic diagram of a circulation path of a liquid according to the present disclosure.

[0015] Figure 4A and Figure 4B is a perspective view of a liquid ejection head according to the present disclosure.

[0016] Figure 5 is an exploded perspective view of a liquid ejecting head according to the present disclosure.

[0017] FIG. 6A to FIG. 6D is a plan view of a channel member according to the present disclosure.

[0018] Fig. 7A and Figure 7B are perspective and cross-sectional views of a channel member and an injection module according to the present disclosure.

[0019] Fig. 8A and Figure 8B are a perspective view and an exploded perspective view of a jetting module according to the present disclosure.

[0020] 9A to 9C is a plan view of a component substrate according to the present disclosure.

[0021] Fig.10 is a cross-sectional view of a device substrate according to the present disclosure.

[0022] Fig.11A and Fig. 11B is a schematic diagram of a temperature regulator in a component substrate according to the present disclosure.

[0023] Fig.12 is a partially enlarged plan view of an adjacent portion of an element substrate according to the present disclosure.

[0024] Fig.13A and Fig. 13B are a plan view and a cross-sectional view of the interior of a liquid ejecting head according to the present disclosure.

[0025] FIG. 14A to FIG. 14H Schematic diagram of the transient steps of the injection phenomenon in the present disclosure.

[0026] Fig.15A and Fig. 15B is an enlarged plan view of the vicinity of a nozzle of a liquid ejecting head according to the present disclosure.

[0027] Fig.16A is a perspective view of a modified example of the ejection module of the liquid ejection head according to the first embodiment, Fig. 16B is its exploded perspective view, and Fig. 16C This is its cross-section diagram.

[0028] Fig.17 yes FIG. 16A to FIG. 16C Schematic diagram of the application state of the adhesive.

[0029] Fig.18 is a perspective view of a modified example of the ejection module of the liquid ejection head according to the first embodiment.

[0030] Fig.19A is a perspective view of a modified example of the ejection module of the liquid ejection head according to the first embodiment, and Fig.19B and Fig.19C This is a partial enlarged view.

[0031] Fig. 20A is a schematic diagram of a jetting module of a liquid jet head according to a first embodiment, Fig. 20B is a partial enlarged view, and Fig. 20C This is its cross-section diagram.

[0032] Fig.21A is a plan view of a plurality of protective members formed in a sheet shape of the liquid ejecting head according to the first embodiment, and Fig. 21B and Fig. 21C This is a partial enlarged view.

[0033] FIG. 22A to FIG. 22C are cross-sectional views of the element substrate according to the first embodiment and cross-sectional views of modified examples thereof.

[0034] FIG. 23A to FIG. 23E It is an enlarged view of a recessed portion and an opening portion of the protective member of the liquid ejecting head according to the first embodiment.

[0035] Fig.24 is an enlarged view of a protective member and an ejection outlet of the liquid ejecting head according to the first embodiment.

[0036] FIG. 25A to FIG. 25D is a sectional view in the vicinity of an ejection outlet of a liquid ejecting head according to a second embodiment. DETAILED DESCRIPTION

[0037] The present disclosure is described in detail in the following examples. In the following description, the reaction liquid and aqueous ink for inkjet may be referred to simply as "reaction liquid" and "ink", respectively.

[0038] <Inkjet Recording Method>

[0039] In the inkjet recording method according to the present disclosure, the aqueous ink and aqueous reaction liquid described below are ejected from the inkjet liquid nozzle to record an image on a recording medium. The method may include: a reaction liquid ejecting step, that is, ejecting an aqueous reaction liquid containing a reactant that reacts with the aqueous ink from a nozzle onto the recording medium; and an ink applying step, that is, applying the aqueous ink to overlap at least a portion of the area to which the aqueous reaction liquid is applied. In addition, the reaction liquid ejecting step may be provided before the ink applying step, or the ink applying step and the reaction liquid ejecting step may be performed in parallel. In the present disclosure, it is not necessary to provide a step of curing the image by irradiating with active energy rays or the like.

[0040] The recording medium can be but not limited to transparent or colored recording medium. The recording medium can be a low-absorption medium (non-absorption medium) with low absorption to liquid medium, such as a resin film. In the case of a so-called serial liquid nozzle and an inkjet recording method in which recording is performed while scanning the recording medium, applying ink to a unit area of ​​the recording medium can be a multi-channel recording performed by multiple relative scans between the liquid nozzle and the recording medium. In particular, when using white ink as described later, applying color ink or aqueous reaction liquid to the unit area and applying white ink can be performed by different relative scans. In particular, white ink and color ink can be applied to the unit area by different relative scans. This increases the time interval between inks that are in contact with each other and easily suppresses the mixing of inks. The unit area can be set to an arbitrary area, such as a pixel or a band.

[0041] (1) Liquid injection device

[0042] A suitable embodiment of a liquid ejection device (inkjet recording device) that can be used for the inkjet recording method according to the present disclosure is described in detail below with reference to the accompanying drawings. However, the following description does not limit the scope of the present disclosure. For example, the present embodiment adopts a thermal system that generates bubbles by a heating element to eject liquid. The present disclosure can also be applied to a liquid ejection head that utilizes a piezoelectric system that uses a piezoelectric element as an energy generating element to eject liquid or utilizes another liquid ejection system. The liquid ejection head that ejects liquid (such as ink) according to the present disclosure and the liquid ejection device equipped with the liquid ejection head can be applied to a printer, a copier, a fax machine including a communication system, or a word processor including a printer unit. They can also be applied to industrial recording devices combined with various processing devices. For example, they can also be applied to applications such as biochip production, electronic circuit printing, and semiconductor substrate production.

[0043] The present embodiment is an inkjet recording device (recording device) in which a liquid (such as ink) circulates between a container and a liquid jet head, but other forms are also possible. For example, instead of circulating the ink, two containers may be provided on the upstream and downstream sides of the liquid jet head, and the ink may flow from one container to another container to induce the flow of ink in the pressure chamber. Although the present embodiment is a so-called line (page width) head, the length of which corresponds to the width of the recording medium, the present disclosure may also be applied to a so-called serial liquid jet head, which performs recording while scanning the recording medium. The serial liquid jet head is, for example, but not limited to, a head having an element substrate for black ink and an element substrate for color ink. It may also be a short-line head having a plurality of element substrates, which are arranged so that the nozzles overlap in the nozzle array direction and are shorter than the width of the recording medium, and the recording medium may be scanned with a short-line head.

[0044] Examples of embodiments of the present disclosure are described below with reference to the accompanying drawings.

[0045] <Basic Configuration of the Present Disclosure>

[0046] Overall configuration of the liquid injection device

[0047] Figure 1 1 is a view of an example of a liquid ejecting device according to the present embodiment. The liquid ejecting device according to the present embodiment is a liquid ejecting device 1000 (hereinafter also simply referred to as device 1000) as an inkjet recording device that records an image on a recording medium 2 by ejecting aqueous ink and an aqueous reaction liquid that reacts with the aqueous ink. In the figure, the X direction is a conveying direction of the recording medium 2, the Y direction is a width direction of the recording medium 2, and the Z direction is a direction intersecting the X direction and the Y direction and is a direction in which liquid is ejected.

[0048] Figure 1 The apparatus 1000 is shown in which the liquid ejecting heads 3 apply liquids (ink and reaction liquid) directly to the recording medium 2 conveyed in the X direction. The recording medium 2 is mounted on the conveying unit 1 and conveyed in the X direction at a predetermined speed under the four liquid ejecting heads 3 (3A, 3B, 3C, and 3D) ejecting different liquids. Figure 1 , four liquid ejecting heads 3 are arranged in the order of 3D, 3C, 3B and 3A along the X direction, and liquid corresponding to each liquid ejecting head 3 is applied to the recording medium 2 in this order. Each liquid ejecting head 3 has a plurality of ejecting orifices arranged along the Y direction and configured to eject liquid. The ejecting orifices are provided in an element substrate described later, and a plane of the element substrate facing the recording medium 2 in the liquid ejecting direction is referred to as an orifice surface.

[0049] As described above, the ink applying step may follow the reaction liquid ejecting step, and Figure 1 The apparatus 1000 in FIG. 1 may be configured so that the liquid ejecting head 3D ejects the reaction liquid and the liquid ejecting heads 3A, 3B, and 3C eject ink.

[0050] Recording medium 2 is Figure 1 The recording medium is cut paper, but may be a continuous form supplied from a roll of paper. The recording medium is not limited to paper, and may be a film or the like.

[0051] This embodiment describes an inkjet recording device in which one liquid ejecting head ejects one type of liquid, one liquid ejecting head (first liquid ejecting head) ejects ink, and one liquid ejecting head (second liquid ejecting head) ejects reaction liquid. However, one liquid ejecting head may be configured to eject multiple types of liquids, and even in a configuration in which one liquid ejecting head is configured to eject aqueous ink and aqueous reaction liquid, the present disclosure may be appropriately used.

[0052] Figure 25 is a block diagram for explaining the control configuration in the device 1000. The control unit 500 includes a CPU, etc., and controls the entire device 1000 while using a RAM 502 as a work area according to the program and various parameters stored in the ROM 501. The control unit 500 performs predetermined image processing on image data received from the host device 600 connected to the outside, and generates ejection data that can be ejected by the liquid ejection head 3 according to the program and parameters stored in the ROM 501. The liquid ejection head 3 is driven according to the ejection data to eject ink at a predetermined frequency. The device 1000 also has a liquid circulation unit 504 that circulates ink and supplies ink to the liquid ejection head 3. The liquid circulation unit 504 controls the entire ink circulation system including the pressure control unit and the switching mechanism under the control of the control unit 500.

[0053] During the ejection operation of the liquid ejecting head 3, the control unit 500 drives the transport motor 503 to transport the recording medium 2 in the X direction at a speed corresponding to the driving frequency. Thus, an image corresponding to the image data received from the host device 600 is recorded on the recording medium 2. In the ROM 501, information on the use area of ​​the nozzles used for ejection in the liquid ejecting head 3 is stored in a rewritable manner for each liquid ejecting head 3. The method of setting the use area will be described in detail later.

[0054] Liquid circulation path

[0055] Figure 3 1 is a schematic diagram showing a liquid circulation path in the apparatus 1000 of this embodiment, in which the liquid ejecting head 3 is fluidically connected to the first circulation pump 1002, the buffer container 1003, etc. Figure 3 Only a path through which liquid of one color of the liquid ejecting head corresponding to the liquid flows is shown, but the main body of the device 1000 has a circulation path corresponding to the type of liquid to be ejected.

[0056] The buffer container 1003, as a sub-container connected to the main container 1006, has an air communication port (not shown) for communicating between the inside and outside of the container, and is capable of discharging bubbles from the liquid to the outside. The buffer container 1003 is also connected to a replenishing pump 1005. When the liquid is consumed in the liquid ejecting head 3 by ejecting (discharging) the liquid from the ejection port of the liquid ejecting head, such as when the liquid is ejected for recording or suction recovery, the replenishing pump 1005 transfers the consumed liquid from the main container 1006 to the buffer container 1003.

[0057] The first circulation pump 1002 has the function of extracting liquid from the liquid connection part 111 of the liquid ejecting head 3 and making the liquid flow to the buffer container 1003. When the liquid ejecting head 3 is driven, a certain amount of liquid flows in the common collection channel 212 through the first circulation pump 1002.

[0058] A negative pressure control unit 230 is provided in the path between the second circulation pump 1004 and the liquid ejection unit 300. The negative pressure control unit 230 has a function of operating so that the pressure on the downstream side (liquid ejection unit 300 side) of the negative pressure control unit 230 can be maintained at a preset constant pressure even when the flow rate of the circulation system fluctuates due to a difference in the duty cycle of performing recording.

[0059] like Figure 3 As shown, the negative pressure control unit 230 includes two pressure regulating mechanisms, and different control pressures are set in the pressure regulating mechanisms. Among the two pressure regulating mechanisms, one pressure regulating mechanism is located on the relatively high pressure side (negative pressure control unit 230H, Figure 3 H in the figure), and another pressure regulating mechanism is located on the relatively low pressure side (negative pressure control unit 230L, in Figure 3 The liquid ejecting unit 300 includes a common supply channel 211, a common collection channel 212, and separate supply channels 213a and separate collection channels 213b, which are connected to their corresponding element substrates having nozzles. The details of the element substrate 10 will be described later. The separate channels 213a and 213b are connected to the common supply channel 211 and the common collection channel 212, and a portion of the liquid flowing out of the second circulation pump 1004 flows from the common supply channel 211 through the internal channel of the element substrate 10 to the common collection channel 212 ( Figure 3 This is because a pressure difference is set between the pressure regulating mechanism H connected to the common supply channel 211 and the pressure regulating mechanism L connected to the common collection channel 212, and the first circulation pump 1002 is connected only to the common collection channel 212.

[0060] Therefore, in the liquid ejection unit 300, there is a liquid flow through the common collection channel 212 and a flow from the common supply channel 211 through each element substrate 10 to the common collection channel 212. This can dissipate the heat generated in each element substrate 10 to the outside of the element substrate 10 through the flow from the common supply channel 211 to the common collection channel 212. During recording with the liquid ejection head 3, this configuration can generate a liquid flow even in the nozzle or pressure chamber that does not participate in the recording, and can suppress the thickening of the liquid in these parts. In addition, the thickened liquid or foreign matter in the liquid can be discharged to the common collection channel 212. Therefore, the liquid ejection head 3 of this embodiment can perform high-speed and high-quality recording.

[0061] Liquid nozzle configuration

[0062] Figure 4A and Figure 4B 2 is a perspective view of a liquid ejecting head 3 according to the present embodiment. The liquid ejecting head 3 is a line liquid ejecting head including 17 element substrates 10 capable of ejecting liquid, and these element substrates 10 are arranged in a straight line (arranged in a straight line). Figure 4A and Figure 4B As shown, the liquid ejector 3 includes an element substrate 10, a flexible printed circuit board 40, and a signal input terminal 91 and a power terminal 92 electrically connected via an electrical wiring board 90. The signal input terminal 91 and the power terminal 92 are electrically connected to the control unit of the device 1000, and respectively provide the element substrate 10 with an ejection drive signal and power required for ejection. The wiring can be centralized by the circuit in the electrical wiring board 90 so that the number of signal input terminals 91 and power terminals 92 is less than the number of element substrates 10. This can reduce the number of electrical connections to be removed when installing the liquid ejector 3 in the device 1000 or when replacing the liquid ejector 3. Figure 4A As shown, the liquid connection portion 111 provided on one side of the liquid ejecting head 3 is connected to the liquid supply system of the device 1000. Therefore, the liquid is supplied from the supply system of the device 1000 to the liquid ejecting head 3, and the liquid passing through the liquid ejecting head 3 is recovered to the supply system of the device 1000. In this way, the liquid can circulate through the path of the device 1000 and the path of the liquid ejecting head 3.

[0063] Figure 5 3 is an exploded perspective view of the components or units constituting the liquid ejecting head 3. The liquid ejecting unit 300, the liquid supply unit 220, and the electrical wiring board 90 are attached to the housing 80. The liquid supply unit 220 is provided with a liquid connection portion 111, and a filter 221 ( Figure 3 ) is used to remove foreign matter from the supplied liquid. The liquid passing through the filter 221 is supplied to the negative pressure control unit 230 on the liquid supply unit 220. The negative pressure control unit 230 includes a pressure regulating valve, and due to the action of the valve, spring member, etc. arranged therein, the change in the pressure drop in the supply system of the device 1000 (the supply system located on the upstream side of the liquid nozzle 3) caused by the change in the liquid flow rate is significantly attenuated. This can stabilize the negative pressure change on the downstream side (the liquid injection unit 300 side) of the negative pressure control unit 230 within a certain range. Two pressure regulating valves are integrated in the negative pressure control unit 230 and are set to different control pressures. Via the liquid supply unit 220, the low-pressure side is connected to the common collection channel 212, and the high-pressure side is connected to the common supply channel 211 in the liquid injection unit 300.

[0064] The housing 80 includes a liquid ejection unit support portion 81 and an electric wiring board support portion 82, supports the liquid ejection unit 300 and the electric wiring board 90, and ensures the rigidity of the liquid ejection head 3. The electric wiring board support portion 82 supports the electric wiring board 90 and is fastened to the liquid ejection unit support portion 81 with screws. The liquid ejection unit support portion 81 has openings 83 and 84, and the joint rubber 100 is inserted into the openings 83 and 84. The liquid supplied from the liquid supply unit 220 is guided to the second channel member 60 constituting the liquid ejection unit 300 via the joint rubber 100.

[0065] Next, the configuration of the channel member 210 in the liquid ejecting unit 300 is described. Figure 5 As shown, the channel member 210 includes a stacked first channel member 50 and a second channel member 60. The channel member 210 distributes the liquid supplied from the liquid supply unit 220 to each jetting module 200, and returns the liquid circulated from the jetting module 200 to the liquid supply unit 220. The plurality of jetting modules 200 are bonded to the bonding surface of the first channel member 50 with an adhesive (not shown). The channel member 210 is fastened to the liquid jetting unit support portion 81 with screws, which suppresses bending or deformation of the channel member 210.

[0066] FIG. 6A to FIG. 6D It is an explanatory diagram of the detailed configuration of the channel member 210. Fig. 6A The support member 30 is shown on the surface of the first channel member 50 on which the injection module 200 is to be mounted, and Figure 6B The surface of the first channel member 50 to be in contact with the support member 30 is shown. Figure 6C is a cross-sectional view of a surface of the first channel member 50 , which is perpendicular to the Z direction and close to the center in the Z direction, and Fig.6D The surface of the second channel member 60 to be in contact with the liquid ejecting unit supporting portion 81 is shown. FIG. 6A to FIG. 6C is seen from the injection module 200 side, and Fig.6D This is seen from the liquid ejecting unit supporting portion 81 side.

[0067] A plurality of support members 30 arranged in the Y direction are disposed on the surface of the first channel member 50 opposite to the second channel member 60, and one element substrate 10 is disposed on each support member 30. The number of arrays of the ejection modules 200 can be adjusted to configure liquid ejection heads 3 of various sizes.

[0068] like Fig. 6A As shown, the support member 30 has a communication port 31 on the surface in contact with the element substrate 10, and the communication port 31 is fluidically connected to the element substrate 10 and is used as the above reference Figure 3 The separate supply channel 213a and the separate collection channel 213b described above are shown in FIG. Figure 6B As shown, the communication port 31 is in fluid communication with the common supply channel 211 or the common collection channel 212 via the communication port 51 of the channel member 50 .

[0069] like Figure 6C As shown, in the middle layer near the center of the first channel member 50 in the Z direction, the common channels 61, 62 extend in the Y direction and serve as reference. Figure 3 The common supply channel 211 and the common collection channel 212 described. Fig.6D As shown, a common communication port 63 in fluid communication with the liquid supply unit 220 is formed at both ends or one end of the common channels 61 and 62 .

[0070] Fig. 7A and Figure 7B 3 are a perspective view and a cross-sectional view for explaining a channel structure formed inside the liquid ejecting unit 300. Fig. 7A is an enlarged perspective view of the channel member 210 as seen from the Z direction, and Figure 7B is along Fig. 7A A cross-sectional view taken along line VIIB-VIIB.

[0071] The element substrate 10 of the injection module 200 is mounted on the communication port 51 of the first channel member 50 via the support member 30. Figure 7B Only the communication port 51 corresponding to the common supply channel 211 is shown, but FIG. 6A to FIG. 6D As shown in another cross section, the common collecting channel 212 is communicated with the communication port 51. In the support member 30 and the element substrate 10 included in each ejection module 200, a channel member 50 is formed for supplying liquid from the first channel member 50 to the recording element 15 on the element substrate 10 (see 9A to 9C ). In addition, in the support member 30 and the element substrate 10, a channel for recovering (circulating) a part or all of the liquid supplied to the recording element 15 to the first channel member 50 is formed.

[0072] As described above, the common supply channel 211 is connected to the negative pressure control unit 230H with a relatively high pressure, and the common collection channel 212 is connected to the negative pressure control unit 230L with a relatively low pressure. FIG. 6A to FIG. 6D ), the common supply channel 211 and the communication port 31 to supply the liquid to the channel formed in the element substrate 10. Similarly, a supply path is formed from the channel in the element substrate 10 through the communication port 31, the communication port 51, the common collection channel 212 and the common communication port 63 (see Fig.6DWhile the liquid circulates in this manner, an ejection operation according to ejection data is performed in the element substrate 10, and the liquid supplied through the supply path and not consumed by the ejection operation is collected through the collection path.

[0073] Injection module configuration

[0074] Fig. 8A is a perspective view of a spray module 200, and Figure 8B The exploded view is shown. In the method of producing the injection module 200, first, the element substrate 10 and the flexible printed circuit board 40 are bonded to the support member 30 pre-set with the communication port 31. Then, the terminal 16 on the element substrate 10 and the terminal 41 on the flexible printed circuit board 40 are electrically connected to each other by wire bonding, and then the wire bonding portion (electrical connection portion) is covered and sealed with a sealant (sealing portion 110). The terminal 42 of the flexible printed circuit board 40 opposite to the element substrate 10 is connected to the connection terminal 93 of the electrical wiring board 90 (see Figure 5 ) is electrically connected. The support member 30 is a support body for supporting the element substrate 10, and is a channel member for fluid communication between the element substrate 10 and the channel member 210, which can have high flatness and can be bonded to the element substrate with sufficiently high reliability. The material can be, for example, alumina or a resin material.

[0075] Configuration of component substrate

[0076] The configuration of the element substrate 10 according to the embodiment is described below. Fig. 9A is a plan view of the plane of the element substrate 10 on which the nozzle 13 is formed, Fig. 9B yes Fig. 9A an enlarged view of the portion indicated by IXB in FIG. 1 , and Fig. 9C yes Fig. 9A Plan view of the back surface of . Fig.10 is along Fig. 9A 1 is a cross-sectional perspective view of the element substrate 10 taken along line XX of FIG. The direction in which the nozzle array of the plurality of nozzles 13 extends is hereinafter referred to as a "nozzle array direction".

[0077] like Fig. 9BAs shown, a heating resistor element 15 is arranged at a position corresponding to each nozzle 13, and the heating resistor element 15 is a heating element (pressure generating element) that uses the generated heat energy to bubble the liquid. The pressure chamber 23 in which the heating resistor element 15 is included is partitioned by a partition 22, and the partition 22 is formed by the first layer 121 (described later) of the channel forming member 12. The heating resistor element 15 is electrically connected to the terminal 16 through an electrical wiring (not shown) provided on the element substrate 10. The heating resistor element 15 is based on the control circuit from the liquid ejecting device 1000 via the electrical wiring board 90 (see Figure 5 ) and a flexible printed circuit board 40 (see Fig. 8A and Figure 8B ) generates heat and boils the liquid. The liquid is ejected from the nozzle 13 by the bubbling force caused by boiling. Fig. 9B As shown, along each nozzle array, a liquid supply channel 18 extends on one side, and a liquid collection channel 19 extends on the other side. The liquid supply channel 18 and the liquid collection channel 19 are channels extending along the nozzle array direction provided in the element substrate 10, and are connected to the nozzle 13 via the supply port 17a and the collection port 17b, respectively. 9A to 9C An element substrate 10 having 16 nozzle arrays is shown as an example.

[0078] like Fig. 9C and Fig.10 As shown, the sheet-like cover plate 20 is disposed on the back surface of the element substrate 10 opposite to the plane on which the nozzle 13 is formed. Fig. 9C As shown, the cover plate 20 has a plurality of openings 21, which are communicated with the liquid supply channel 18 and the liquid collection channel 19 described later. In the present embodiment, the cover plate 20 has four supply openings 21a for one liquid supply channel 18 and three collection openings 21b for one liquid collection channel 19, but the number of openings is not limited thereto. Fig. 9B As shown, each opening 21 in the cover plate 20 is Fig. 7A The cover plate 20 is connected to the communication port 51 shown. The cover plate 20 can be made of a material having sufficient corrosion resistance to the liquid, and the shape and position of the opening 21 need to be highly accurate in order to supply the liquid to the pressure chamber. Therefore, a photosensitive resin material or a silicon plate can be used as a material for the cover plate 20 to provide the opening 21 by photolithography. Therefore, the cover plate 20 changes the pitch of the channel through the opening 21, and from the viewpoint of pressure loss, strength, and processability, it is desirable that the cover plate is formed of a thin film member having a thickness in the range of about 30 to 600 μm.

[0079] Next, the liquid flow in the element substrate 10 is described. In the element substrate 10, a substrate 11 formed of silicon and a channel forming member (nozzle forming member) 12 formed of a photosensitive resin are stacked. In the present embodiment, the channel forming member 12 includes a first layer 121 (middle layer) for forming a pressure chamber 23 and a second layer 122 (upper layer) having a nozzle 13. The channel forming member 12 is formed by sequentially stacking (laminating) the first layer 121 and the second layer 122 on the plane (first plane 11a) of the substrate 11, patterning them by exposing them to light having their respective optimal photosensitivity wavelengths, and then developing them. The channel forming member 12 can be produced by a method of stacking the first layer and the second layer or by any other method (such as a method of forming a pressure chamber and a nozzle using a mold material, etc.). The cover plate 20 is bonded to the back surface of the substrate 11. The cover plate 20 serves as a cover that forms a part of the wall of the liquid supply channel 18 and the liquid collection channel 19 formed in the substrate 11 of the element substrate 10. In the element substrate 10, the heating resistor element 15 is formed on one plane side of the substrate 11 (see 9A to 9C ), and grooves constituting a liquid supply channel 18 and a liquid collection channel 19 extending along the nozzle array are formed on its back surface. The liquid supply channel 18 and the liquid collection channel 19 formed by the substrate 11 and the cover plate 20 are respectively connected to the common supply channel 211 and the common collection channel 212 in the channel member 210 (see Fig. 7A and Figure 7B ) is connected, and a pressure difference is generated between the liquid supply channel 18 and the liquid collection channel 19. This pressure difference forms a circulation flow C ( Fig.10 In the nozzle 13 and the pressure chamber 23 where no ejection operation is performed, the flow can collect thicker ink, bubbles, foreign matter, etc. generated by evaporation from the nozzle 13 to the liquid collection channel 19. This can also suppress the thickening of the ink in the nozzle 13 or the pressure chamber 23 or the increase in the density of the coloring material. Fig. 7A and Figure 7B As shown, the liquid collected in the liquid collection channel 19 is collected through the opening 21 of the cover plate 20 and the connecting port 31 of the support member 30 in the order of the connecting port 31 of the support member 30, the connecting port 51 of the first channel member 50 and the common collecting channel 212, and is collected in the supply path of the liquid injection device 1000.

[0080] In other words, the liquid supplied from the liquid ejection device body to the liquid ejection head 3 flows and is supplied and collected in the following order. The liquid first flows into the liquid ejection head 3 from the liquid connection portion 111 of the liquid supply unit 220. The liquid is then sequentially supplied to the joint rubber 100, the common communication port 63 in the second channel member, the common channel 61 in the first channel member, and the communication port 51. The liquid is then sequentially supplied to the pressure chamber 23 via the communication port 31 in the support member 30, the opening 21 in the cover plate 20, and the liquid supply channel 18 and the supply port 17a in the substrate 11. The liquid supplied to the pressure chamber 23 and not ejected from the ejection port 13 sequentially flows through the collection port 17b and the liquid collection channel 19 in the substrate 11, the opening 21 in the cover plate 20, and the communication port 31 in the support member 30. The liquid then flows through the communication port 51 and the common channel 62 in the first channel member, the common communication port 63 in the second channel member, and the joint rubber 100. The liquid then flows from the liquid connection portion 111 provided in the liquid supply unit to the outside of the liquid ejecting head 3. Figure 3 In the form of the circulation path shown, the liquid flowing out from the liquid connection part 111 is supplied to the joint rubber 100 through the negative pressure control unit 230 .

[0081] The liquid ejecting head of the present embodiment further includes a temperature control mechanism in the element substrate 10 . Fig.11A and Fig. 11B Schematic diagram of dividing the element substrate 10 into a plurality of zones for temperature adjustment. Each zone is provided with a temperature sensor 301 and a sub-heater 302 which can be controlled separately, and a control unit 500 (see Figure 2) uses the temperature sensor 301 and the sub-heater 302 to adjust the temperature based on the temperature (target temperature) set for each zone. Therefore, the control unit 500 drives the sub-heater 302 only in the zone where the temperature detected by the temperature sensor 301 is equal to or lower than the target temperature. The target temperature of the element substrate 10 can be set to a relatively high temperature to reduce the viscosity of the liquid and appropriately perform the ejection operation or cycle. Such temperature control is performed in order to suppress the temperature change within the element substrate 10 or the temperature change between multiple element substrates 10 within a predetermined range. This can reduce the change in the ejection amount caused by the temperature change and suppress the density unevenness in the recorded image. When all the heating resistor elements 15 are driven at the assumed highest driving frequency, the target temperature of the element substrate 10 can be set to a temperature equal to or higher than the equilibrium temperature of the element substrate 10. The temperature sensor 301 can be a diode sensor, an aluminum sensor, etc. The heating unit of the element substrate 10 can also be a heating resistor element 15, which is a heating element. More specifically, the element substrate 10 can be heated by applying a voltage that does not cause bubbling to the heating resistor element 15. For example, the heating unit may not be the sub-heater 302 but may be the heating resistor element 15 or a combination of the sub-heater 302 and the heating resistor element 15 .

[0082] Positional relationship between component substrates

[0083] Fig.12 FIG. 1 is a partially enlarged plan view of adjacent portions of the element substrates in two adjacent injection modules. 9A to 9C As shown in FIG. 1 , in this embodiment, a component substrate having an approximately parallelogram shape is used. Fig.12 As shown, each nozzle array (14a to 14d) in which the nozzles 13 are arranged in each element substrate 10 is inclined at a certain angle relative to the conveying direction of the recording medium. Therefore, the nozzle arrays in adjacent parts of the element substrate 10 are arranged so that at least one nozzle overlaps in the conveying direction of the recording medium. Fig.12 In the example, two nozzles on line D overlap. With such an arrangement, even if the position of the element substrate 10 is slightly offset from the predetermined position, the black stripes or white spots on the recorded image can be made less noticeable by driving and controlling the overlapping nozzles. Even when a plurality of element substrates 10 are arranged linearly (straightly) rather than staggered, Fig.12 The configuration of the present disclosure takes measures to prevent black streaks or white spots in the overlapping portion between the element substrates 10 while suppressing an increase in the length of the liquid ejecting head 3 in the recording medium conveying direction. Although the element substrate 10 has a parallelogram-shaped main surface in the present embodiment, the present disclosure is not limited thereto. For example, even when an element substrate having a rectangular, trapezoidal, or other shape is used, the configuration of the present disclosure can be applied.

[0084] Liquid flow near the pressure chamber

[0085] Fig.13A and Fig. 13B shows the interior of the liquid ejector head, Fig.13A is a plan view (perspective view) of the heating resistor element and the channel, and Fig. 13B is along Fig.13A A cross-sectional view taken along line XIIIB-XIIIB of the element substrate 10 is shown. A plurality of pressure chambers 23, and inlet channels 24a and outlet channels 24b communicating with the respective pressure chambers 23 are provided between the substrate 11 of the element substrate 10, and each pressure chamber 23 has a nozzle 13. The pressure chambers 23 are separated by the wall portion (partitioning member 22) of the channel forming member 12. The substrate 11 is configured to form a circulation flow C (see FIG. 1 ) in which the liquid in the liquid supply channel 18 flows to the liquid collection channel 19 via the supply port 17a, the inlet channel 24a, the pressure chamber 23, the outlet channel 24b and the collection port 17b. Fig.10 ). The rate of the circulating flow C in the pressure chamber is preferably, for example, 1.0 mm / s or more and 250 mm / s or less, and even in the ejection operation performed in the liquid flow state, the influence on the landing accuracy and the like is small. Fig. 13B As shown, the nozzle 13 is an opening portion located at the end of a cylindrical nozzle portion 25 formed in the channel forming member 12, and the nozzle portion 25 communicates between the nozzle 13 and the pressure chamber 23. The direction of the liquid ejected from the nozzle 13 ( Fig. 13B The vertical direction in the pressure chamber 23 is called the “injection direction”, and the liquid flow direction in the pressure chamber 23 ( Fig. 13B The horizontal direction in the image) is referred to as the “flow direction”.

[0086] A plurality of supply ports 17a form a supply port array, and a plurality of collection ports 17b form a collection port array. A nozzle array with a plurality of nozzles 13 arranged is formed between the supply port array and the collection port array. In the present embodiment, as described above, a pressure difference is provided between the liquid supply channel 18 and the liquid collection channel 19. Due to the pressure difference, liquid is introduced from the supply port 17a through the inlet channel 24a into the pressure chamber 23, thereby generating a circulation flow C in which the liquid flows from the outlet channel 24b to the collection port 17b.

[0087] The heating resistor element 15 is provided on the bottom surface of the pressure chamber 23 facing the nozzle 13. The nozzle portion (nozzle) 25 penetrates the channel forming member 12 at a position facing the pressure chamber 23. The outer end portion of the nozzle portion 25, that is, the end portion opposite to the heating resistor element 15, forms the nozzle 13 through which the liquid is ejected. The nozzle portion 25 or the nozzle 13 is provided at a position facing the heating resistor element 15. In this specification, the nozzle 13 is an opening in the outer surface of the channel forming member 12 facing the recording medium 2, and the nozzle portion 25 is a portion communicating between the nozzle 13 and the pressure chamber 23 and refers to a through hole penetrating the channel forming member 12.

[0088] like Fig.13A and Fig. 13B As shown, the present embodiment does not have a filter (such as a columnar structure), which is usually arranged on the inlet channel 24a or the outlet channel 24b in the liquid spray head to prevent foreign matter such as dust from entering the pressure chamber 23. This can reduce flow resistance, enhance the refilling performance of the liquid, and increase the injection frequency. In the present embodiment, as described later, foreign matter can be captured by the channel (inlet channel 24a) with a lower height in the channel forming member, and therefore the filter can be omitted. Of course, the filter can be arranged in the inlet channel 24a and the outlet channel 24b on both sides of each pressure chamber 23, and can also be arranged near the inlet and outlet.

[0089] In the liquid ejecting head of the present embodiment, the inlet channel 24a, the pressure chamber 23, the ejection port 13, the recording element 15 and the outlet channel 24b constitute a single channel 24 as a ejection unit, and the liquid supply channel 18 (upstream channel) for supplying liquid and the liquid collecting channel 19 (downstream channel) for liquid outflow are connected to a plurality of ejection units (single channels). Interposing a single channel between the upstream channel and the downstream channel separated from each other can produce an effect of more easily preventing the ejection liquid from concentrating.

[0090] Liquid ejection step and satellite droplet formation

[0091] Figures 14A to 14H yes Fig. 13B Schematic diagram of the transient steps of the injection phenomenon in Section XIV. Figures 14A to 14H In, omitted Fig.13A The protrusion of the nozzle 13 in the middle. Liquid is supplied to the pressure chamber 23 from the inlet channel 24a. When electric energy is applied to the recording element 15, the recording element 15 generates thermal energy for ejecting liquid. The liquid near the recording element 15 is heated by the thermal energy and evaporates, thereby forming a bubble B ( Fig. 14B ). The pressure at the initial stage of the generation of the bubble B is high, and the bubble B pushes the liquid between the bubble B and the nozzle 13 toward the nozzle 13 (see Fig. 14CThe bubble B grows and enters the nozzle portion 25. As the bubble B grows, its internal pressure quickly changes from positive pressure to negative pressure below atmospheric pressure ( Fig.14D ). The bubble B contracts due to the negative pressure, and the tail end portion of the droplet is pulled toward the recording element 15, thereby increasing the tail length (see Fig.14E and Fig.14F ). When the bubble B further advances in the nozzle portion 25, the bubble B communicates with the atmosphere inside or outside the nozzle portion 25. Therefore, the negative pressure of the bubble B disappears rapidly, and the growth of the tail length stops (see Figure 14G ). Through these steps, the liquid between the generated bubble B and the nozzle 13 is ejected from the nozzle 13 by the pressure of the bubble B. The ejected liquid is ejected mainly as a main droplet, but a satellite droplet S or mist is formed behind the main droplet (see Fig.14H ). When the air communication timing of the bubble B is delayed, the tail becomes longer, and the droplet is more easily separated into the main droplet and the satellite droplet due to the above-mentioned speed difference and the surface tension of the liquid, which may cause the recording quality to deteriorate due to the influence of the satellite droplet. Therefore, in order to reduce the degradation of the recording quality caused by the satellite droplet, it is effective to advance the air communication timing and shorten the tail.

[0092] As a method of bringing forward the timing of air connection and shortening the tail, it is effective to reduce the resistance of the droplets passing through the nozzle. Therefore, in the ejection direction, the distance OH from the plane of the pressure chamber 23 with the recording element 15 to the nozzle 13 is preferably 16 μm or less. Such a dimensional relationship can produce the effect of effectively applying the ejection energy from the recording element to the ejected droplets. This can also further increase the ejection speed of the ejected droplets when the air is connected, and make the configuration stronger (more robust) to resist airflow disturbances caused by the recording medium, etc. On the other hand, too short OH will result in excessively high flow resistance, and therefore OH is preferably 13 μm or greater.

[0093] It is desirable that the inlet channel 24a and the outlet channel 24b have the same flow resistance. The bubbles generated by the heat energy diffuse not only in the ejection direction but also in the directions of the inlet channel 24a and the outlet channel 24b (see Fig. 14B and Fig. 14C ). At this time, the difference in flow resistance between the inlet channel 24a and the outlet channel 24b is large, causing the generated bubbles to spread asymmetrically within the channel. In this case, the tail is also formed asymmetrically, and when the tail shrinks and merges with the main droplet, its axis is offset. Therefore, the droplets cannot be successfully merged and may be formed worse.

[0094] The shape of the nozzle

[0095] Fig.15A FIG. 1 is a plan view of the shape of the nozzle in this embodiment. Fig.15AIn the embodiment, two protrusions 27 are provided on a straight line L passing through the center F of the nozzle 13 so as to protrude toward the center F in the same shape on both sides of the center F. This can produce the effect of shortening the tail length of the ejected droplet. More specifically, the meniscus of the liquid formed between the protrusions 27 is easier to maintain than the meniscus of other parts. Therefore, the tail of the droplet extending from the nozzle 13 can be cut off earlier, thereby suppressing the formation of satellite droplets (mist) which are tiny droplets accompanying the main droplet. The contraction of the bubble narrows the tail end portion of the ejection direction of the ejected droplet that has moved toward the center portion of the recording element 15, and narrows the tail. This can advance the timing of air communication and shorten the tail length, thereby suppressing the satellite droplets formed due to the separation of the droplet from the main droplet. Even if a satellite droplet separated from the main droplet is formed, the satellite droplet is small and the number will be reduced due to the short tail length. In Figures 1 to 14H , the nozzle 13 can be depicted as having no protrusions 27. Wide intervals 28 between the protrusions tend to cause the ejected droplets to have long tail lengths and small satellite droplets. Therefore, the interval 28 is expected to be 7.0μm or less, and more preferably 5.0μm or less. The inventors have found that, for example, when the viscosity of the ejected liquid is 0.002Pa·s or greater and 0.010Pa·s or less, and the surface tension is 20mN / m or greater and 60mN / m or less, the time required for the bubble B to connect to the air may be affected by the shortest interval between the protrusions. It was also found that when the shortest interval between the protrusions is 5.0μm or less, the time required for the bubble to connect to the atmosphere is particularly short. On the other hand, an overly narrow interval may make it difficult to form a protrusion or may result in the formation of two separate ejected droplets. Therefore, the interval 28 is expected to be 2.0μm or greater. Therefore, the interval 28 is desirably 2.0 μm or more and 7.0 μm or less, and more desirably 2.0 μm or more and 5.0 μm or less. In the present embodiment, the interval 28 is 3.0 μm as an example.

[0096] Furthermore, a protrusion 27 having a thick tip (on the center F side) may result in two ejected droplets being divided by the protrusion 27. Therefore, the width 271 of the leading edge of each protrusion 27 is desirably 4.0 μm or less, for example, 2.0 μm in the present embodiment. Fig.15A When the top of the protrusion 27 is rounded as in the present embodiment shown, the width 271 of the leading edge can be defined as the length of the line segment between the intersection of the line perpendicular to the straight line L at the top of the protrusion and the two extension lines of the two long sides of the protrusion, as shown by the dotted line in the figure. In addition, in order to increase the strength of the protrusion 27, the width 272 of the base of each protrusion 27 is desirably greater than the width of the leading edge, and is, for example, 4.0 μm in the present embodiment. Fig.15AAs in the present embodiment shown in FIG. 1 , when the nozzle 13 at the base has a curved shape as shown by the dotted line in the figure, the width 272 of the base can be defined as the length of the line segment between the two extended lines of the two long sides of the protrusion and the circumference line of the nozzle 13 (if the nozzle 13 is circular). Therefore, from the perspective of droplet formation, the protrusion 27 can have a shape in which the width decreases from the base toward the leading edge, and can have a shape as shown in FIG. Fig. 15B The arc shown.

[0097] It is expected that the two protrusions 27 extend in a direction roughly parallel to the conveying direction (X direction) of the recording medium 2. Since the protrusions 27 have a very large influence on the ejection of the droplets, a slight change in the shape of the two protrusions during the production process will cause the droplets to fly out in the direction of one of the protrusions and cause a landing position deviation. Generally, the landing position deviation in the nozzle array direction (Y direction) is easier to be visually identified on the image than the landing position deviation in the conveying direction (X direction) of the recording medium. Therefore, making the direction of the protrusion roughly parallel to the conveying direction of the recording medium 2 can suppress the deviation in the nozzle array direction and have the effect of maintaining good printing. In addition, it is expected that the protrusion 27 extends in the flow direction of the liquid near the pressure chamber. In other words, it is expected that the straight line L where the protrusion is positioned forms an angle of 45 degrees or less with the channel axis connecting the liquid supply channel 18 and the liquid collection channel 19 or connecting the inlet channel 24a and the outlet channel 24b.

[0098] Although in the present embodiment, two protrusions 27 extend toward the center F of the nozzle, good droplet formation can be maintained even with one protrusion 27. However, in this case, the landing may deviate greatly in the direction where the protrusion 27 is not present, and the landing position may be less consistent. Therefore, it is more desirable that the two protrusions 27 extend in the direction of the nozzle center F. The present disclosure can be suitably applied even to a liquid ejecting head having a nozzle without the protrusion 27.

[0099] It is desirable that the opening area of ​​the nozzle 13 is 100 μm 2 Or larger. Alternatively, when the diameter of a circle whose area is equal to the actual area of ​​the nozzle 13 is defined as the effective diameter, it is desirable that the effective diameter of the nozzle 13 is 11 μm or larger. An opening area that is too small will result in increased forward resistance during liquid injection and a longer time required for air communication. This may increase the tail length and the number of satellite droplets. In addition, the opening area of ​​the nozzle 13 affects the speed at which droplets are ejected from the nozzle 13 (described later). It should be noted that a nozzle with a protrusion tends to have a smaller opening area and a lower injection speed than a nozzle with the same diameter and no protrusion.

[0100] Conditions during droplet formation

[0101] In addition, in order to achieve stable ejection quality and high recording quality, it is desired that the dot size of the liquid droplets landing on the recording medium 2 is relatively small and the definition is high, so the ejection amount of the liquid ejecting head of this embodiment is relatively small, 2.0 ng.

[0102] Droplet formation is also affected by the droplet ejection velocity. At an excessively high ejection velocity, the tip of the main droplet may eject before the tail, and the tail may break and form satellite droplets. Therefore, the ejection velocity is desirably 12 m / s or less. On the other hand, at an excessively low droplet ejection velocity, components in the ejected liquid may burn and adhere to the heating element. Therefore, the ejection velocity is desirably 7.0 m / s or greater.

[0103] In inkjet recording devices used in commercial and industrial sectors and the like that require better droplet formation, high solid density inks are used in some cases from the perspectives of image fastness, color development, and the like. The term "solid density" as used herein refers to the density of pigments, resins, waxes, and the like in the ejected liquid. At this time, ejection defects caused by ink concentration due to the evaporation of water from the ink may be more significant. Although the ejection speed can be increased to suppress ink concentration, at an excessively high ejection speed, as described above, the tail is prone to breakage and satellite droplets are prone to appear. In the liquid ejector head of the present embodiment, since the liquid in the pressure chamber can be circulated, even if the water near the nozzle 13 evaporates, fresh liquid that has not evaporated is supplied from the inlet channel 24a. Therefore, even when the ejection liquid is an ink of high solid density, stable ejection can be achieved without excessively increasing the ejection speed. An ink with a high solid density is, for example, an ink in which the non-volatile solvent concentration is adjusted to 10 weight % or more and 20 weight % or less, the pigment concentration is adjusted to 3 weight % or more and 10 weight % or less, the solid density is adjusted to 10 weight % or more and 30 weight % or less, and the viscosity is adjusted to 0.003 Pa·s or more and 0.006 Pa·s or less.

[0104] <Description of Embodiments of the Present Disclosure>

[0105] First embodiment

[0106] The following describes a first embodiment of the present disclosure. Functions and configurations similar to those of the above-described basic configuration will not be described here, but different points will be described.

[0107] Fig.16A is a perspective view of a simplified injection module 200 according to a first embodiment. Fig. 16B for Fig.16A Exploded perspective view of. Fig. 16C For along Fig.16A A cross-sectional view taken along line XVIC-XVIC. Fig.17 for Fig. 16CSchematic diagram of the adhesive application state in FIG. Fig.16A , Fig. 16B , Fig. 16C and Fig.17 In the figure, the configuration is partially simplified for clarity.

[0108] The first embodiment is different from the basic configuration in that a protection member 140 is provided on the surface (ejection surface 120) of the passage forming member 12. More specifically, as shown in FIG. Fig. 16B and Fig. 16C As shown, an opening 141 corresponding to the nozzle array 14 is formed in the protective member 140, and a recess 124 is formed between adjacent nozzle arrays 14 on the ejection surface 120. The ejection surface 120 and the protective member 140 are bonded to each other by an adhesive 150 applied to the recess 124. In this configuration, the protective member 140 is located on the outermost surface of the liquid ejection head 3 in the liquid ejection direction. Therefore, in the direction perpendicular to the head face, the nozzle 13 is positioned closer to the pressure chamber than the head face (i.e., the outermost surface of the liquid ejection head 3). Therefore, mist flying from the outside preferentially adheres to the protective member 140 as the outermost surface, and this can suppress the mist from adhering to the nozzle 13 and prevent the ink or reaction liquid from adhering to the nozzle 13. This improves the ejection stability of the ink or reaction liquid. In order to make the mist adhere to the protective member 140 earlier than the ejection surface 120, the thickness of the protective member 140 in the liquid ejection direction is preferably 1.0 μm or more, and more preferably 10 μm or more. The shortest distance between the nozzle 13 and the protective member 140 in the direction parallel to the ejection surface 120 (hereinafter also referred to as the "plane direction") is preferably 1.0 mm or less, more preferably 300 μm or less. This is because, when the shortest distance is 1.0 mm or more, the protective member 140 is too far away from the nozzle 13, and the possibility of mist adhering to the nozzle 13 increases.

[0109] In addition, the protective member 140 is disposed on the ejection surface 120 and is used to prevent the recording medium 2 from contacting the element substrate 10 when the recording medium 2 is lifted during the conveying process, thereby reducing the risk of damaging the liquid ejection head 3. The recording medium 2 may be offset paper or the like, which may contain mineral particles such as silica or calcium carbonate in the coating. Collisions during the conveying process may cause these particles to fall off, and friction may damage the ejection surface. These minerals have an elastic modulus of tens of gigapascals or more, and therefore the protective member also preferably has an elastic modulus of 50 GPa or more. For example, metal materials such as stainless steel, titanium or aluminum, silicon or aluminum oxide may be suitably used as materials. The length of the opening 141 of the protective member 140 in a direction substantially perpendicular to the nozzle array direction is preferably 250 μm or more and shorter than the interval between adjacent nozzle arrays 14, and the thickness of the protective member 140 is preferably less than 50 μm. At this time, in a direction perpendicular to the head face, the distance between the head face and the nozzle 13 is preferably 1.0 μm or more and 50 μm or less. Thus, when the cleaning mechanism (not shown) of the apparatus 1000 comes into contact with the liquid ejecting head 3 during maintenance at the time of recording, the cleaning mechanism (not shown) can more appropriately collect the liquid in the liquid ejecting head 3. Therefore, the outer shapes of the protective member 140 and the opening 141 can be processed with high precision, for example, by a processing method such as etching, laser processing, or press processing.

[0110] like Fig.17 As shown, adhesive 150 is applied to recess 124. The adhesive applied to recess 124 may have a higher adhesive strength than the adhesive applied to the flat surface portion of ejection surface 120. At this time, ejection surface 120 may repel the liquid ejected from nozzle 13, and recess 124 will not repel the liquid. In this way, adhesive 150 may remain in recess 124 and is unlikely to flow into nozzle 13. Adhesive 150 is suitably, for example, a thermosetting adhesive. In addition, in order to further increase the adhesive strength between ejection surface 120 and protective member 140, a method of forming an adhesive layer (not shown) on at least the ejection surface 120 side of protective member 140 may also be suitably used.

[0111] Fig.18 As Fig. 16B 1 is a perspective view of a simplified element substrate 10 of a modified example. Fig.19A As Fig.16A 2 is a perspective view of a simplified injection module 200 of a modified example. Fig.19B yes Fig.19A An enlarged view of the portion indicated by XIXB. Fig.19C yes Fig.19A An enlarged view of the portion indicated by XIXC in FIG. Fig.18 , Fig.19A , Fig.19B and Fig.19C In the embodiment, for the sake of clarity, the configuration is partially simplified. As a modified example of the first embodiment, Fig.18 As shown, the concave portions 124 formed between adjacent nozzle arrays 14 can be connected to each other in a groove shape. Such a configuration can further increase the bonding strength between the ejection surface 120 and the protective member 140. In addition, as another modified example of the first embodiment, as shown in FIG. Fig.19A , Fig.19B and Fig.19C As shown in , an R shape 143 can be formed at the corner of the protective member 140. Such a configuration can reduce the risk of damaging the cleaning mechanism (not shown) due to the corner of the protective member 140 when the cleaning mechanism (not shown) of the device 1000 contacts the liquid ejection head 3 during maintenance during recording. In addition, in order to remove the alignment marks 126a and 126b used for positioning between adjacent element substrates 10, openings 142a and 142b for removing patterns can be formed in the protective member 140. In addition, a notch (not shown) can be formed in the protective member 140 according to the pattern on the element substrate, such as an element substrate number (not shown) for identifying the element substrate 10. At this time, the risk of damaging the cleaning mechanism (not shown) can be reduced by forming an R shape in the notch (not shown).

[0112] FIG. 20A to FIG. 20C yes FIG. 16A to FIG. 16C Schematic diagram of a modified example of the injection module 200 shown in FIG. FIG. 20A to FIG. 20C The protective member 140 of the modified example shown in FIG. 1 has a recess and a protrusion inside the recess. FIG. 20A to FIG. 23E The protection member 140 of the modified example is described in detail.

[0113] Fig. 20A is a schematic diagram of a simplified injection module. Fig. 20B yes Fig. 20A An enlarged view of the portion indicated by XXB. Fig. 20C is along Fig. 20B A cross-sectional view taken along line XXC-XXC.

[0114] In the manufacturing process of the protection member 140, a plurality of protection members are formed on a sheet and connected to each other via a connecting portion. Then, for example, the connecting portion is separated by vibration to provide one protection member. At this time, when the connecting portion is separated, unfortunately, a protrusion is formed in the protection member 140 in a direction perpendicular to the nozzle array 14 of the element substrate 10.

[0115] In view of this, the protection member 140 according to the present modified example is provided with at least one recess 144 located at an end portion parallel to the direction of the nozzle array 14 in a direction perpendicular to the nozzle array 14 of the element substrate 10, and is provided with a protrusion 145 protruding in a direction perpendicular to the nozzle array 14 of the element substrate 10. The protrusion 145 is provided inside the recess 144 of the protection member 140. Therefore, the protrusion 145 is provided in the formation area of ​​the protection member 140 without protruding from the protection member 140.

[0116] In addition, if Fig. 20C As shown, the channel forming member 12 is provided with a recess 12a to correspond to the protrusion 145 of the protective member 140 in a direction perpendicular to the nozzle array 14 of the element substrate 10 and in the vertical direction. The recess 12a of the channel forming member 12 is formed to expose the substrate 11 on the lower side in the vertical direction. The protrusion 145 of the protective member 140 is accommodated in the recess 12a of the channel forming member 12. Therefore, the protrusion 145 is accommodated in the recess 12a and does not contact the ejection surface 120, and thus the floating of the protective member 140 can be suppressed.

[0117] The protective member 140 may have a recess 144 (first recess) at an end portion parallel to the nozzle array direction in a direction perpendicular to the nozzle array 14 of the element substrate 10, and may have a recess 147 (second recess) at the other end portion opposite to the end portion. The recess 144 at the end portion and the recess 147 at the other end portion are formed at the same position as the recess 12a. Therefore, the recess 12a is set to correspond to the protrusion 145 of the protective member 140, can accommodate the protrusion 145, and can suppress the floating of the protective member 140.

[0118] Fig.21A is a plan view in which a plurality of protective members of the liquid ejecting head according to the present disclosure are formed in the shape of one sheet, and Fig. 21B yes Fig.21A Magnified view of section XXIB. Fig. 21C is a partial enlarged view of the protective member 140 after being separated from the sheet, and Fig. 21B correspond.

[0119] In the protection member 140 of the present embodiment, the thickness of the protection member 140 is 50 μm or less for cost reduction, and a plurality of protection members 140 are formed by etching one large material sheet 160 so as not to form burrs in the openings 141 and the like.

[0120] like Fig. 21BAs shown, the plurality of protection members 140 are connected to each other via the connection portion 146. The sheet 160 is vibrated to separate at the connection portion 146, thereby forming a protrusion 145 in a direction in which the protection member 140 is substantially perpendicular to the nozzle array direction, as shown in FIG. Fig. 21C The shape of the connection portion 146 may be tapered so as to become narrower toward the protection member 140, or may be tapered so as to become wider toward the protection member 140. The connection portion 146 may have a tapered shape so as to become narrower toward the protection member 140, but may have a shape in which the connection width with the protection member 140 is short. This can facilitate separation by vibration at the connection portion 146. In addition, in the shape in which the connection width with the protection member 140 is short, the recess 12a of the channel forming member 12 can be formed small.

[0121] Although the protection member 140 can be produced at low cost by separation by vibration as described above, the present inventors have found that vibration may distort the protrusion 145 and deform the protrusion 145 upward or downward in the vertical direction.

[0122] FIG. 22A to FIG. 22C are a schematic cross-sectional view of an element substrate different from the present embodiment, a cross-sectional view of an element substrate 10 according to the present modified example, and a cross-sectional view showing the modified example.

[0123] The following describes a case where the protrusion 145 of the protective member 140 is deformed upward in the vertical direction. Since there is a risk that the cleaning mechanism (not shown) of the device 1000 contacts the protrusion 145 during maintenance at the time of recording and is damaged and broken, it is desirable to set the protrusion 145 at a position where it does not contact the cleaning mechanism.

[0124] In this embodiment, a sealant (sealing portion) 110 (see Fig. 20A ) is higher than the element substrate 10 in the vertical direction, and the cleaning mechanism is driven in the direction of the nozzle array to avoid the sealing portion 110, etc. The protrusion 145 is provided on the side of the protection member 140 parallel to the nozzle array by etching, etc. during the manufacturing process. Fig. 20A to the positions indicated by XXB and F to avoid contact with the cleaning mechanism.

[0125] When the protrusion 145 of the protection member 140 is deformed downward in the vertical direction, as shown in FIG. Fig.22AAs shown, the protrusion 145 may interfere with the ejection surface 120, and the protective member 140 may be deformed and lifted. When the area from the end of the protective member 140 to the opening 141 of the protective member 140 is large, the rigidity of the member of the protective member 140 suppresses floating. However, when the area from the end of the protective member 140 to the opening 141 of the protective member 140 is small, floating may occur. As in the present embodiment, the protrusion 145 may be formed on the element substrate 10 at a position adjacent to the sealing portion 110 (see Fig. 20A In this case, the area from the end of the protection member 140 to the opening 141 of the protection member 140 is small, and thus the deformation of the protrusion 145 downward in the vertical direction may lift the protection member when interfering with the ejection surface 120.

[0126] Therefore, in this embodiment, if Fig. 22B As shown, the channel forming member 12 has the recess 12a so that deformation of the protrusion 145 does not interfere with the ejection surface 120. Therefore, even when the protrusion 145 deforms downward in the vertical direction, the protrusion 145 and the ejection surface 120 do not interfere with each other, and thus floating of the protection member 140 can be suppressed.

[0127] In the channel forming member 12 of the present embodiment, when the nozzle and the pressure chamber are formed on the substrate 11, the channel forming member 12 has a recess 12a at a position corresponding to the protrusion 145, and is formed so as to expose the surface of the substrate 11. The exposed portion of the surface of the substrate 11 is positioned opposite to the sealing portion 110, and the main circuit is not provided inside the substrate and is therefore less likely to be affected by electrical noise from the exposed portion of the substrate 11.

[0128] In addition, if Fig. 22C As shown, the channel forming member 12 may have a recess 12b so that the substrate 11 is not exposed. This reduces the height of the recess in the vertical direction compared to the recess 12a in which the surface of the substrate 11 is exposed, and reduces the distance between the protrusion 145 and the channel forming member 12. However, the substrate 11 is covered with the protective member 140, and thus the resistance to electrical noise is improved.

[0129] In the present embodiment, the protrusion 145 is formed by cutting off the connection between the material sheet and the protection member 140, but the protrusion 145 may be provided on a side of the protection member 140 opposite to the side on which the protrusion 145 is formed. Fig. 20A As shown, the protrusion 145 is provided on the sealing portion 110 side of the protection member 140 (see Fig. 20AThe element substrate 10 has a long distance from the nozzle array 14 on the sealing portion 110 side closest to the element substrate 10 to the end of the channel forming member 12 near the sealing portion 110 to guide the wiring in the substrate from the sealing portion 110 side to the nozzle array. Therefore, when the protective member 140 is provided on the element substrate 10, the area of ​​the protective member 140 on the sealing portion 110 side can be increased. If Fig. 20A If a recess corresponding to the protrusion 145 is provided at the position indicated by the middle region F, floating of the protection member 140 can be further suppressed. On the other hand, if no recess is provided, electrical noise contamination due to exposure of the substrate 11 can be suppressed.

[0130] The concave portion of the passage forming member 12 may have any shape that does not interfere with the ejection surface 120 when the protrusion 145 of the protection member 140 is deformed downward in the vertical direction. FIG. 23A to FIG. 23C As shown, the recess 12b may have a trapezoidal shape, a semicircular shape, or a rectangular shape. In addition, it is not limited to a recess, and an opening portion capable of accommodating the protrusion 145 may be provided. For example, Fig.23D and Fig.23E As shown, a quadrilateral opening or a circular opening may be provided. The protrusion 145 may be accommodated in each provided opening. This can suppress the floating of the protection member 140 due to the interference between the protrusion 145 of the protection member 140 and the ejection surface 120.

[0131] Although in the above example, one nozzle array 14 is provided in one opening 141 of the protection member 140, the configuration of the present disclosure is not limited thereto. Fig.24 As shown in the enlarged view of the vicinity of the nozzle 13 in FIG. 1 , the protection member 140 may have one opening 141 for one nozzle 13. Such a one-to-one correspondence between the nozzle 13 and the opening 141 may enhance the effect of suppressing the attachment of mist near the nozzle 13.

[0132] Second embodiment

[0133] A second embodiment of the present disclosure is described below. Functions and configurations similar to those of the first embodiment will not be described here, and different points will be described.

[0134] Fig.25A This is a cross-sectional view in the direction perpendicular to the head surface, passing through the center of the nozzle 13 in the second embodiment.

[0135] In the second embodiment, on the ejection surface 120 side of the channel forming member 12 as the head face, a recess 123 is provided, which has a height difference between the vicinity of the nozzle 13 and other parts, and the nozzle 13 is located in the recess 123. More specifically, in the direction perpendicular to the head face, the nozzle 13 is positioned closer to the pressure chamber 23 than the ejection surface 120 of the channel forming member 12. Therefore, the nozzle 13 is positioned closer to the pressure chamber 23 than the head face as the outermost surface of the liquid ejection head 3. By such a configuration, mist or the like flying from the outside preferentially adheres to the ejection surface 120, and this can suppress the attachment of mist to the nozzle 13, and prevent the ink or reaction liquid from adhering to the nozzle 13. This improves the ejection stability of the ink or reaction liquid. In order to make the mist adhere to the ejection surface 120 earlier than the nozzle 13, the height difference H between the ejection surface 120 and the nozzle 13 in the ejection direction is preferably 1.0 μm or more.

[0136] The shortest distance L between the nozzle 13 and the ejection surface 120 in the direction parallel to the ejection surface is preferably 1.0 mm or less, more preferably 300 μm or less. This is because a shortest distance L of 1.0 mm or more causes the ejection surface 120 to be too far from the nozzle 13 and increases the possibility of mist adhering to the nozzle 13.

[0137] The shape and configuration of the recess 123 in the nozzle 13 of the passage forming member 12 may be any shape as long as the nozzle 13 is positioned closer to the pressure chamber 23 than the ejection surface 120. It may be as follows Fig.25B The surface shown, or it can be Fig.25C In addition, Fig.25D As shown, in the passage forming member 12 having a layered structure, the recessed portion 123 can be formed by making the opening size near the ejection port 13 different in each layer.

[0138] Furthermore, the ejection surface of the passage forming member 12 may be recessed toward the pressure chamber 23 in each nozzle 13, or a plurality of nozzles 13 may be provided in one recess. The one-to-one correspondence between the nozzles 13 and the recesses 123 can enhance the effect of suppressing the attachment of mist near the nozzles 13.

[0139] (2) Reaction solution

[0140] The components and the like used in the aqueous reaction liquid of the present disclosure are described in detail below.

[0141] Reactants

[0142] The reaction liquid contacts the ink, reacts with the ink, and condenses the components in the ink (components having anionic groups, such as resins or self-dispersible pigments), and contains polyvalent metal salts, organic acids, cationic resins, etc. as reactants. Any reactant can be added to the reaction liquid as long as the desired characteristics such as high storage stability of the reaction liquid, high intermittent ejection stability, and suppression of image unevenness can be achieved.

[0143] In a reaction liquid containing a polyvalent metal salt, the polyvalent metal salt (i.e., a compound formed by the combination of a divalent or higher-valent metal ion and an anion) dissociates into polyvalent metal ions in the reaction liquid and can cause the dispersed coloring material to condense under the action of the anion groups contained in the ink.

[0144] Polyvalent metal ions are, for example, Ca 2+ , Cu 2+ 、Ni 2+ Mg 2+ , Sr 2+ , Ba 2+ or Zn 2+ Divalent metal ions such as Fe 3+ Cr 3+ , Y 3+ or Al 3+ In order to include a polyvalent metal ion in the reaction solution, a polyvalent metal salt (which may be a hydrate) generated by combining the polyvalent metal ion with an anion may be used. Anions are, for example, Cl - ,Br - ,I - ,ClO - ,ClO2 - ,ClO3 - ,ClO4 - ,NO2 - ,NO3 - ,SO4 2- ,CO3 2- ,HCO3 - ,PO4 3- ,HPO4 2- or H2PO4 - Inorganic anions such as HCOO - ,(COO - )2,COOH(COO - ),CH3COO - ,C2H5COO - ,CH3CH(OH)COO - ,C2H4(COO - )2,C6H5COO - ,C6H4(COO- )2 or organic anions such as CH3SO3-. The polyvalent metal salt content (mass %) of the reaction solution is preferably 1.0 mass % or more and 20.0 mass % or less, more preferably 1.0 mass % or more and 5.0 mass % or less, based on the total mass of the reaction solution.

[0145] The water solubility (g / 100 mL) of the polyvalent metal salt at 25° C. is preferably 25.0 g / 100 mL or more. The polyvalent metal salt having a water solubility of less than 25.0 g / 100 mL is easily unstable in the dissolved state in the reaction liquid and easily precipitates. The precipitated polyvalent metal salt may reduce the reactivity with the ink, and thus image unevenness may not be sufficiently suppressed in some cases. The solubility is preferably 50.0 g / 100 mL or less.

[0146] The reaction liquid containing the organic acid has a buffering capacity in the acid region (pH less than 7.0, preferably pH in the range of 2.0 to 5.0), effectively converting the anionic groups of the components present in the ink into acid form and causing the components to condense. The organic acid is, for example: a monocarboxylic acid such as formic acid, acetic acid, propionic acid, butyric acid, benzoic acid, glycolic acid, lactic acid, salicylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, nicotinic acid, thiophene carboxylic acid, levulinic acid, or coumaric acid, or a salt thereof; a dicarboxylic acid such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, itaconic acid, sebacic acid, phthalic acid, malic acid, or tartaric acid, or a salt or hydrogen salt thereof; a tricarboxylic acid such as citric acid or trimellitic acid, or a salt or hydrogen salt thereof; or a tetracarboxylic acid such as pyromellitic acid, or a salt or hydrogen salt thereof. When the organic acid is added, the organic acid content (mass %) in the reaction liquid is preferably 1.0 mass % or more and 50.0 mass % or less based on the total mass of the reaction liquid.

[0147] Cationic resin is, for example, a resin having a primary amine to tertiary amine structure or a resin having a quaternary ammonium salt structure. Specific examples thereof include resins such as vinylamine, allylamine, vinylimidazole, vinylpyridine, dimethylaminoethyl methacrylate, ethyleneimine, guanidine, diallyldimethylammonium chloride, or alkylamine-epichlorohydrin condensate. In order to increase the solubility in the reaction solution, a cationic resin and an acidic compound can be used in combination, or the cationic resin can be quaternized. When the cationic resin is added, the cationic resin content (mass %) in the reaction solution is preferably 0.1 mass % or more and 10.0 mass % or less based on the gross mass of the reaction solution.

[0148] Surfactants

[0149] The reaction liquid contains a nonionic surfactant having an HLB value of 14 or less. In order to further suppress image unevenness, the HLB value of the nonionic surfactant is preferably 12 or less. The "HLB value" of the nonionic surfactant in this specification is a value determined by the Griffin method and is calculated based on the following formula: HLB value = 20×(formula weight of the hydrophilic group of the surfactant) / (molecular weight of the surfactant). The HLB determined by the Griffin method is a physical property indicating the hydrophilicity or lipophilicity of the nonionic surfactant, and ranges from 0 to 20. A lower HLB indicates a higher lipophilicity, and a higher HLB indicates a higher hydrophilicity. The HLB value of the nonionic surfactant is preferably 4 or greater.

[0150] The nonionic surfactant may be a hydrocarbon, fluorinated or silicone surfactant. The nonionic surfactant may be at least one surfactant selected from the group consisting of hydrocarbon surfactants and silicone surfactants. This is because such surfactants have a high ability to easily wet and spread on the recording medium due to their structure, and their effect is not easily weakened even when evaporation, etc., changes the composition of the reaction solution.

[0151] Hydrocarbon nonionic surfactants are, for example, ethylene oxide adducts of polyoxyethylene alkyl ether, acetylene glycol, polyethylene glycol-polypropylene glycol block copolymers or ethylene oxide adducts of polyols. Fluorinated nonionic surfactants are, for example, perfluoroalkyl ethylene oxide adducts. Silicone nonionic surfactants are, for example, polyether-modified siloxane compounds. In particular, hydrocarbon nonionic surfactants and silicone nonionic surfactants can be used. When they are used in combination, the content of hydrocarbon nonionic surfactants can be higher than the content of silicone nonionic surfactants. The nonionic surfactant content (mass %) of the reaction solution is preferably 0.1 mass % or more and 4.0 mass % or less, more preferably 0.2 mass % or more and 2.0 mass % or less.

[0152] Ink can also include various surfactants (other surfactants) other than nonionic surfactants. Other surfactants can be anionic surfactants, cationic surfactants and amphoteric surfactants. Other surfactants can be hydrocarbon surfactants, fluorinated surfactants, silicone surfactants, etc. whose HLB values ​​are outside the above range. Based on the gross mass of the reaction solution, the surfactant (nonionic surfactant and other surfactants total) content (mass %) of the reaction solution is preferably 0.1 mass % or more and 5.0 mass % or less, more preferably 0.2 mass % or more and 3.0 mass % or less.

[0153] Aqueous medium

[0154] The reaction solution contains an aqueous medium as a mixed solvent of water and a water-soluble organic solvent. Water can be deionized water or ion-exchanged water. Based on the gross mass of the reaction solution, the water content (mass %) of the reaction solution is preferably 75.0 mass % or greater. When the content is less than 75.0 mass %, when the liquid component of the reaction solution evaporates in continuous recording, a polyvalent metal salt may precipitate. Therefore, it may not be possible to fully suppress image unevenness. Based on the gross mass of the reaction solution, the water content (mass %) of the reaction solution is preferably 95.0 mass % or less.

[0155] The water solubility (g / 100mL) C of the polyvalent metal salt at 25°C, the polyvalent metal salt content (mass %) c of the reaction liquid, and the water content (mass %) W of the reaction liquid preferably satisfy the relationship of W / (100×c / C)≥4.0. 100×c / C in the relationship represents the amount of water (mass %) required to dissolve the polyvalent metal salt. Therefore, the relationship means that the amount of water contained in the reaction liquid is 4.0 times or more of the amount of water required to dissolve the polyvalent metal salt. When the left side of the relationship is less than 4.0 times, evaporation may make the dissolution of the polyvalent metal salt unstable, and the polyvalent metal salt may precipitate. Therefore, image unevenness may not be fully suppressed.

[0156] The reaction solution includes a first water-soluble organic solvent having an SP value of 14.8 or less and a first water-soluble organic solvent having an SP value of 14.8 or less and a vapor pressure of 1.0×10 -3 kPa or more. Specifically, the second water-soluble organic solvent may include a SP value of 14.8 or less and a vapor pressure of 1.0×10 -2 kPa or more. When the third water-soluble organic solvent is included, the third water-soluble organic solvent is easily evaporated among the liquid components in the reaction liquid during long-term image recording, and thus the composition change of the liquid components can be more effectively suppressed. Therefore, image unevenness can be more effectively suppressed. The water-soluble organic solvent in the reaction liquid may be only one type. In other words, the first water-soluble organic solvent, the second water-soluble organic solvent and the third water-soluble organic solvent may be the same. The vapor pressure of the first water-soluble organic solvent at 25°C is preferably 1.0×10 -1 kPa or less. The SP value of the first water-soluble organic solvent is preferably 10.0 or more.

[0157] The water-soluble organic solvent that meets these conditions can be propylene glycol (1,2-propylene glycol) (SP value: 13.5, vapor pressure: 1.8×10 -2 kPa), ethylene glycol (1,2-ethylene glycol) (SP value: 14.8, vapor pressure: 1.2×10 -2 kPa), 1,2-butanediol (SP value: 12.8, vapor pressure: 2.0×10 -2kPa), 1,2-hexanediol (SP value: 11.8, vapor pressure: 2.6×10 -3 kPa), diethylene glycol monoethyl ether (SP value: 10.8, vapor pressure: 1.7×10 -2 kPa), 2-methyl-1,3-propanediol (SP value: 14.8, vapor pressure: 3.0×10 -3 kPa), or 2-pyrrolidone (SP value: 12.6, vapor pressure: 1.3×10 -3 kPa). In particular, the first water-soluble organic solvent may include 1,2-alkanediol because image unevenness can be more effectively suppressed. This may be because it has a relatively small molecular weight, has a hydrophilic part derived from a hydroxyl group and a hydrophobic part derived from an alkyl chain, and can function as a surfactant. The first water-soluble organic solvent may be 1,2-alkanediol. In this specification, the vapor pressure is a value at 25° C. and 1 atm.

[0158] The ratio (mass %) of the second water-soluble organic solvent in the water-soluble organic solvent having an SP value of 14.8 or less in the reaction solution is preferably 80.0 mass % or more. When the ratio is less than 80.0 mass %, evaporation may change the orientation state of the surfactant, and in some cases, image unevenness cannot be fully suppressed. The ratio can be 100.0 mass %. The ratio (mass %) of the third water-soluble organic solvent in the water-soluble organic solvent having an SP value of 14.8 or less in the reaction solution is preferably 80.0 mass % or more. When the ratio is within the above range, the change in the orientation state of the surfactant caused by evaporation can be further suppressed, and image unevenness can be effectively suppressed. The ratio can be 100.0 mass %.

[0159] In this specification, the SP value (δ) is a value calculated by the Fedors method according to the following formula. Although the unit of the SP value (δ) is omitted in this specification, the unit is ((cal / cm 3 ) 1 / 2 ).

[0160] δ=(ΔE vap / V) 1 / 2

[0161] (Where ΔE vap represents the molar heat of vaporization (cal / mol), and V represents the molar volume at 25°C (cc / mol).

[0162] When the ink contains a plurality of water-soluble organic solvents, the SP values ​​of the water-soluble organic solvents are calculated as an average SP value. The average SP value of the water-soluble organic solvent is calculated by multiplying the SP value of each water-soluble organic solvent by its proportion (mass %) in the total amount of the water-soluble organic solvent in the ink and then adding the products.

[0163] Resin

[0164] The reaction solution according to the present disclosure contains resin. The resin may be an acrylic resin, a polyurethane resin or a urea resin. In particular, an acrylic resin may be used. Based on the gross mass of the reaction solution, the resin content (mass %) of the reaction solution is preferably 1.00 mass % or more and 25.00 mass % or less, more preferably 3.00 mass % or more and 15.00 mass % or less. In particular, 5.00 mass % or more and 15.00 mass % or less are particularly preferred.

[0165] The resin may be included in the reaction solution and the ink described later to improve various properties of the image to be recorded, such as scratch resistance and hiding power. The resin may be a block copolymer, a random copolymer, a graft copolymer, or a combination thereof. The resin may be a water-soluble resin soluble in an aqueous medium or resin particles dispersed in an aqueous medium. The resin particles do not need to contain a coloring material.

[0166] In this specification, the phrase "resin is water-soluble" means that when neutralized with an alkali equivalent to the acid value, the resin is present in an aqueous medium without particles having a particle size measurable by a dynamic light scattering method. Whether a resin is water-soluble can be determined by the following method. First, a liquid (resin solid content: 10% by mass) containing a resin neutralized with an alkali (sodium hydroxide, potassium hydroxide, etc.) equivalent to the acid value is prepared. The prepared liquid is then diluted 10 times (by volume) with pure water to prepare a sample solution. When the particle size of the resin in the sample solution is measured by a dynamic light scattering method, if no particles having a particle size are observed, it can be determined that the resin is water-soluble. The measurement conditions can be, for example, zeroing: 30 seconds, the number of measurements: 3, and the measurement time: 180 seconds. A particle size analyzer using a dynamic light scattering method (e.g., a trade name "UPA-EX150" manufactured by Nikkiso Co., Ltd.) can be used as a particle size distribution analyzer. Of course, the particle size distribution analyzer to be used, the measurement conditions, etc. are not limited to those described above.

[0167] The acid value of the water-soluble resin is preferably 80 mgKOH / g or more and 250 mgKOH / g or less, more preferably 100 mgKOH / g or more and 200 mgKOH / g or less. If resin particles are present, the acid value of the resin particles is preferably 0 mgKOH / g or more and 50 mgKOH / g or less. The weight average molecular weight of the resin is preferably 1000 or more and 30000 or less, more preferably 5000 or more and 15000 or less. The weight average molecular weight of the resin is the polystyrene equivalent molecular weight measured by gel permeation chromatography (GPC).

[0168] Other Ingredients

[0169] If necessary, the reaction liquid may further contain various other components. The other components may be other components that can be contained in the ink described later.

[0170] Physical properties of the reaction solution

[0171] The reaction liquid that can be suitably used in the recording method according to the present disclosure is an aqueous reaction liquid applied to an inkjet system. Therefore, from the perspective of reliability, its physical properties can be appropriately controlled. More specifically, the surface tension of the reaction liquid at 25° C. is preferably 20 mN / m or more and 60 mN / m or less. The viscosity of the reaction liquid at 25° C. is preferably 1.0 mPa·s or more and 10.0 mPa·s or less. The pH of the reaction liquid at 25° C. is preferably 5.0 or more and 9.5 or less, more preferably 6.0 or more and 9.0 or less.

[0172] (3) Ink

[0173] The ink that can be used for the inkjet recording method according to the present disclosure is described in detail below with reference to the examples. In the present disclosure, with respect to salt compounds, although the salt is dissociated into ions in the ink, it is still expressed as "containing salt" for convenience. Aqueous inkjet ink may be referred to as "ink" for short. Unless otherwise specified, physical properties are values ​​at room temperature (25°C). For recording images using white ink, white ink can be used as a bottom layer treatment for color inks. In this case, images can be recorded by applying color inks (black, cyan, magenta, yellow, etc. inks) to overlap at least a portion of the area to which white ink is applied. It can also be used for back printing, i.e., applying white ink to overlap at least a portion of the area to which color ink is applied.

[0174] The ink according to the present disclosure is an aqueous inkjet ink containing a coloring material dispersed by the action of anionic groups. The ink according to the present disclosure is not necessarily a so-called "curable ink". Therefore, the ink according to the present disclosure does not necessarily contain a polymerizable monomer that can be polymerized by external energy (such as heat or light, etc.). The components constituting the ink according to the present disclosure, the physical properties of the ink, the method for producing the ink, etc. are described in detail below.

[0175] Coloring Materials

[0176] The ink comprises a coloring material dispersed by anionic action. The coloring material may be a pigment or a dye. Based on the gross mass of the ink, the coloring material content (mass %) of the ink is preferably 0.1 mass % or more and 15.0 mass % or less, more preferably 1.0 mass % or more and 10.0 mass % or less.

[0177] Specific examples of the pigment include inorganic pigments such as carbon black and titanium oxide; and organic pigments such as azo, phthalocyanine, quinacridone, isoindolinone, imidazolone, diketopyrrolopyrrole, and dioxazine.

[0178] In the method of dispersing the pigment, a resin-dispersed pigment containing a resin as a dispersant, a self-dispersing pigment in which a hydrophilic group is bound to the surface of the pigment particles, etc. can be used. In addition, a resin-bound pigment in which an organic group containing a resin is chemically bound to the surface of the pigment particles, a microcapsule pigment in which the surface of the pigment particles is coated with a resin, etc. can also be used. In particular, a resin-dispersed pigment in which a resin used as a dispersant is physically adsorbed on the surface of the pigment particles can be used instead of a resin-bound pigment or a microcapsule pigment. Therefore, the pigment can be dispersed by a resin (resin dispersant) having an anionic group.

[0179] The resin dispersant for dispersing the pigment in the aqueous medium is a resin dispersant capable of dispersing the pigment in the aqueous medium by the action of anionic groups. The resin dispersant can be a resin described later, particularly a water-soluble resin. The pigment content (mass %) of the ink is preferably 0.3 times or more and 10.0 times or less of the content of the resin dispersant in terms of mass ratio.

[0180] Self-dispersible pigments can be pigments with anionic groups such as carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, etc. directly bonded to the surface of the pigment particles or bonded via other atomic groups (-R-). The anionic group can be acidic or salt-type. The salt type can be in a partially dissociated state or a completely dissociated state. When the anionic group is a salt type, the cation used as a counterion can be an alkali metal cation, ammonium or organic ammonium. Specific examples of other atomic groups (-R-) include: straight-chain or branched alkylene groups having 1 to 12 carbon atoms; arylene groups, such as phenylene or naphthylene groups; carbonyl groups; imino groups; amide groups; sulfonyl groups; ester groups; and ether groups. Combinations of these groups can also be used.

[0181] The dye is a dye having an anionic group. Specific examples of the dye include azo, triphenylmethane, (aza)phthalocyanine, xanthene, anthrapyridone. The coloring material may be a pigment or a resin-dispersed pigment.

[0182] Coloring material (white ink)

[0183] The present disclosure can be suitably used for the inkjet recording method using the ink containing titanium oxide as the coloring material. Since titanium oxide is a white pigment, the ink can be a white ink. As in the present disclosure, as described above, in the inkjet recording method using the aqueous reaction liquid containing the reactant reacting with the aqueous ink, a non-absorbent recording medium formed by vinyl chloride (PVC), polyethylene terephthalate (PET) etc. is often used. In this case, no matter how the color of the recording medium is, the image recording of high color development can be achieved by using the white ink containing titanium oxide. The coloring material in the white ink containing titanium oxide is described below.

[0184] White ink contains titanium oxide as a coloring material (pigment). Titanium oxide can be titanium oxide particles that have been surface-treated with a specific inorganic oxide. Therefore, the ink can contain titanium oxide particles whose surface is coated with a specific inorganic oxide. Based on the total mass of the ink, the titanium oxide particle content (mass %) of the ink is preferably 0.10 mass % or more and 20.00 mass % or less. Based on the total mass of the ink, the titanium oxide particle content (mass %) of the ink is more preferably 1.00 mass % or more and 20.00 mass % or less. Based on the total mass of the ink, the titanium oxide particle content (mass %) of the ink is particularly preferably 1.00 mass % or more and 15.00 mass % or less.

[0185] Titanium oxide is a white pigment and has three crystal forms: rutile, anatase, and brookite. In particular, rutile titanium oxide can be used. Titanium oxide can be produced industrially by a sulfuric acid method or a chlorine method, and the titanium oxide used in the present disclosure can be produced by any method.

[0186] The cumulative 50% particle size based on volume of the titanium oxide particles (hereinafter also referred to as the average particle size) is preferably 200 nm or more and 500 nm or less. In particular, the cumulative 50% particle size based on volume of the titanium oxide particles is more preferably 200 nm or more and 400 nm or less. The cumulative 50% particle size (D50) based on volume of the titanium oxide particles is the particle diameter at the 50% integral value of the total volume of the particles measured from the minimum particle size in the cumulative particle size curve. The D50 of the titanium oxide particles can be measured under the following conditions, for example: zeroing: 30 seconds, number of measurements: 3, measurement time: 180 seconds, shape: non-spherical, and refractive index: 2.60. A particle size analyzer using a dynamic light scattering method can be used as a particle size distribution analyzer. Of course, the measurement conditions, etc. are not limited to the above.

[0187] Titanium oxide can be surface treated with aluminum oxide and silicon oxide. Surface treatment is expected to reduce photocatalytic activity and improve dispersibility. As used herein, the term "alumina" is a general term for aluminum oxides such as aluminum oxide. As used herein, the term "silica" is a general term for silicon dioxide or a substance including silicon dioxide. Most of the aluminum oxide and silicon oxide coating titanium oxide exist in the form of silicon dioxide and aluminum oxide.

[0188] Based on the total mass of the titanium oxide particles, the titanium oxide content (mass %) of the titanium oxide particles is preferably 90.00 mass % or more. Based on the total mass of the titanium oxide particles, the titanium oxide content (mass %) of the titanium oxide particles is preferably 98.50 mass % or less. The aluminum oxide content (mass %) of the titanium oxide particles needs to be 0.50 times or more and 1.00 times or less of the silicon oxide content (mass %) in terms of mass ratio. A mass ratio less than 0.50 times or greater than 1.00 times will result in low jetting stability of the ink. The silicon oxide content (mass %) of the titanium oxide particles is preferably 1.00 mass % or more and 4.00 mass % or less of the total mass of the titanium oxide particles. A silicon oxide content (mass %) less than 1.00 mass % may result in insufficient affinity for the compound represented by the general formula (1), and insufficient jetting stability of the ink. A silicon oxide content (mass %) of more than 4.00 mass % may result in that, even if the surface is treated with aluminum oxide, the compound represented by the general formula (1) is adsorbed on the titanium oxide particles in a large amount, and may result in insufficient ink ejection stability. The aluminum oxide content (mass %) of the titanium oxide particles is preferably 0.50 mass % or more and 4.00 mass % or less based on the total mass of the titanium oxide particles.

[0189] The aluminum oxide content and silicon oxide content of the titanium oxide particles, that is, the amount of aluminum oxide and silicon oxide coating, can be measured, for example, by quantitatively analyzing the aluminum element and the silicon element using inductively coupled plasma (ICP) emission spectrometry. In this case, the obtained values ​​of aluminum and silicon can be converted into their oxides (i.e., aluminum oxide and silicon oxide) by assuming that all atoms covering the surface are oxides for calculation. The aluminum element content (mass %) of the titanium oxide particles determined by inductively coupled plasma emission spectrometry is 0.57 times or more and 1.13 times or less of the silicon element content (mass %) in terms of mass ratio. When this value is converted into its oxide (i.e., aluminum oxide and silicon oxide), the aluminum oxide content (mass %) of the titanium oxide particles is 0.50 times or more and 1.00 times or less of the silicon oxide content (mass %) in terms of mass ratio.

[0190] The surface treatment method of titanium oxide can be wet treatment, dry treatment, etc. For example, titanium oxide can be dispersed in a liquid medium and then reacted with a surface treatment agent (such as sodium aluminate or sodium silicate) for surface treatment, and the proportion of the surface treatment agent can be appropriately changed to adjust to the desired characteristics. In addition to aluminum oxide and silicon oxide, inorganic oxides (such as zinc oxide or zirconium oxide) or organic substances (such as polyols) can also be used for surface treatment without losing the advantages of the present disclosure.

[0191] White ink may contain pigments other than titanium oxide without losing the advantages of the present disclosure. In this case, inks of colors other than white ink may be used. Based on the total mass of the ink, the other pigment content (mass %) of the ink is preferably 0.10 mass % or more and 5.00 mass % or less, more preferably 0.10 mass % or more and 1.00 mass % or less.

[0192] The compound represented by the general formula (1)

[0193] The ink may contain a compound represented by the following general formula (1) as a dispersant for dispersing titanium oxide particles. Based on the total mass of the ink, the amount (mass %) of the compound represented by the general formula (1) in the ink is preferably 0.01 mass % or more and 1.00 mass % or less, 0.02 mass % or more and 0.50 mass % or less.

[0194]

[0195] (In the general formula (1), R1, R2 and R3 each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R4 each independently represents an alkylene group having 2 to 4 carbon atoms. X represents a single bond or an alkylene group having 1 to 6 carbon atoms. n ranges from 6 to 24. a ranges from 1 to 3, b ranges from 0 to 2, and a+b=3)

[0196] In the general formula (1), R1, R2 and R3 each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The alkyl group having 1 to 4 carbon atoms may be a methyl group, an ethyl group, an n-propyl group, an isopropyl group, or an n-butyl group. In particular, from the perspective of ease of hydrolysis, a methyl group may be used. When R1, R2 and R3 each independently represent an alkyl group having more than 4 carbon atoms, it is difficult to form a silanol group by hydrolysis, and affinity for titanium oxide particles cannot be obtained. Therefore, the titanium oxide particles cannot be stably dispersed, and the ink cannot have jetting stability. a representing the number of R1O ranges from 1 to 3, b representing the number of R2 ranges from 0 to 2, and a+b=3. In particular, a is preferably 3, and b is preferably 0, that is, the 3 substituents on the silicon atom can all be R1O.

[0197] In the general formula (1), R4 represents an alkylene group having 2 to 4 carbon atoms independently of one another. The alkylene group having 2 to 4 carbon atoms can be ethylene, n-propylene, isopropylene or n-butylene, and in particular, ethylene can be used. The number of OR4, i.e., the range of n (average value) representing the number of alkylene oxides, is from 6 to 24. An n less than 6 will result in an alkylene oxide chain having a length that is too short, and therefore the repulsive force caused by steric hindrance is insufficient, and the ink has a low jetting stability. An n greater than 24 will result in an alkylene oxide chain having a length that is too long, and therefore the hydrophilicity is enhanced, and it is easily free in an aqueous medium. This results in insufficient affinity for the surface hydroxyl group of titanium oxide particles, and causes the titanium oxide particles to condense. Therefore, the titanium oxide particles cannot be stably dispersed, and the ink cannot have jetting stability.

[0198] In the general formula (1), X represents a single bond or represents an alkylene group having 1 to 6 carbon atoms. When X represents a single bond, it means that the silicon atom is directly bonded to OR4. The alkylene group having 1 to 6 carbon atoms can be a methylene group, an ethylene group, a n-propylene group, an isopropylene group, an n-butylene group, a n-pentylene group, a n-hexylene group, etc. In particular, a n-propylene group can be used. When X represents an alkylene group having more than 6 carbon atoms, the compound represented by the general formula (1) has too high hydrophobicity, the titanium oxide particles cannot be stably dispersed, and the ink cannot have jetting stability.

[0199] The compound represented by the general formula (1) as a dispersant for titanium oxide particles may be a compound represented by the following general formula (2). The compound represented by the general formula (2) has three OR1s bonded to silicon atoms, can be partially hydrolyzed in an aqueous medium, and forms three hydroxyl groups bonded to silicon atoms, thereby increasing the portion having affinity for titanium oxide particles. The compound represented by the following general formula (2) has a repeating structure of ethylene oxide groups. Therefore, the ethylene oxide chain can be moderately extended in an aqueous medium, and a repulsive force caused by steric hindrance can be obtained.

[0200]

[0201] (In the general formula (2), R1 and R3 each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. m ranges from 8 to 24.)

[0202] The amount (mass %) of the compound represented by the general formula (1) in the ink is preferably 0.002 times or more and 0.10 times or less of the titanium oxide particle content (mass %) in terms of mass ratio. A mass ratio of less than 0.002 times may result in a smaller effect of stabilizing the dispersion of titanium oxide particles and insufficient jetting stability of the ink. A mass ratio greater than 0.10 times tends to result in an excessively high proportion of the compound represented by the general formula (1), and intermolecular condensation (self-condensation) of the compound represented by the general formula (1) may occur. This may result in the compound represented by the general formula (1) being consumed and unable to act as a dispersant, a weak effect of stabilizing the dispersion of titanium oxide particles, and insufficient jetting stability of the ink.

[0203] The compound represented by the general formula (1) is hydrogen bonded to the surface hydroxyl groups of the titanium oxide particles, and is believed to partially form a covalent bond through a dehydration reaction. However, in the present disclosure, the compound represented by the general formula (1) can disperse the titanium oxide particles without forming a covalent bond with the titanium oxide particles. Therefore, the amount of the compound represented by the general formula (1) covalently bonded to the titanium oxide particles is very small and can be ignored. Therefore, the content of the titanium oxide particles does not include the covalently bonded compound represented by the general formula (1). According to the research results of the inventors, it was found that an excessive amount of the compound represented by the general formula (1) covalently bonded to the titanium oxide particles would result in a lower jetting stability of the ink. The reason is believed to be as follows. Generally, in a liquid medium with a high dielectric constant such as water, electrostatic attraction is unlikely to work, and the titanium oxide particles move freely without significant environmental impact. However, when the compound represented by the general formula (1) is covalently bonded to the titanium oxide particles, the hydrophilic part (OR4 part) of the structure of the general formula (1) forms a hydrogen bond with the water molecule, and thus may affect the movement of the titanium oxide particles. Therefore, in the case where the liquid is deformed by instantaneous pressure such as in inkjet ejection, the above characteristics manifest as differences in ejection characteristics. Therefore, the amount (mass %) of the compound represented by the general formula (1) covalently bonded to the titanium oxide particles is preferably 0.001 times or less of the titanium oxide particle content (mass %) in terms of mass ratio. A mass ratio greater than 0.001 times may result in insufficient ejection stability of the ink. The mass ratio may be 0.0001 times or less. The amount of the compound represented by the general formula (1) covalently bonded to the titanium oxide particles can be calculated by thermogravimetric analysis or the like.

[0204] Resin

[0205] The ink may contain a resin. The types and amount ranges of the resin that can be used are the same as those of the resin contained in the reaction solution described above, and are not described here. The reaction solution and the ink may contain different types of resins.

[0206] Aqueous medium

[0207] The ink is an aqueous ink containing water as an aqueous medium. The ink may contain water or an aqueous medium as a mixed solvent of water and a water-soluble organic solvent. The water may be deionized water (ion exchange water). Based on the gross mass of the ink, the water content (mass %) of the ink is preferably 50.00 mass % or more and 95.00 mass % or less.

[0208] The water-soluble organic solvent is not particularly limited as long as the solvent is water-soluble (at 25° C., the solvent can be dissolved in water in any proportion). More specifically, monohydric alcohols or polyhydric alcohols, alkylene glycols, glycol ethers, nitrogen-containing polar compounds, sulfur-containing polar compounds, etc. can be used. Based on the total mass of the ink, the water-soluble organic solvent content (mass %) of the ink is preferably 3.00 mass % or greater and 50.00 mass % or less, more preferably 10.00 mass % or greater and 40.00 mass % or less. A water-soluble organic solvent content (mass %) less than 3.00 mass % may cause the ink to solidify in the inkjet recording device, as well as insufficient viscosity resistance. A water-soluble organic solvent content (mass %) greater than 50.00 mass % may cause ink supply failure.

[0209] Other additives

[0210] In addition to the above-mentioned additives, the ink may also include other additives as required, such as surfactants, pH adjusting agents, corrosion inhibitors, preservatives, bactericides, antioxidants, reduction inhibitors, evaporation promoters and / or chelating agents. In particular, the ink may include a surfactant. Based on the gross mass of the ink, the surfactant content (mass %) of the ink is preferably 0.10 mass % or more and 5.00 mass % or less, more preferably 0.10 mass % or more and 2.00 mass % or less. The surfactant may be an anionic surfactant, a cationic surfactant or a nonionic surfactant. In particular, nonionic surfactants that have low affinity to titanium oxide particles and produce an effect even in a small amount can be used to adjust the various physical properties of the ink.

[0211] Physical properties of ink

[0212] The ink is applied to an inkjet system and may have physical properties appropriately adjusted for the inkjet system. The surface tension of the ink at 25°C is preferably 10 mN / m or more and 60 mN / m or less, more preferably 20 mN / m or more and 40 mN / m or less. The surface tension of the ink can be adjusted by appropriately determining the type and amount of the surfactant in the ink. The viscosity at 25°C is preferably 1.0 mPa·s or more and 10.0 mPa·s or less. The pH of the ink at 25°C is preferably 7.0 or more and 9.0 or less. When the ink has a pH within this range, the compound represented by the general formula (1) is hydrolyzed and forms a silanol group, thereby effectively showing a weak affinity for titanium oxide particles. The pH of the ink can be measured with a typical pH meter equipped with a glass electrode.

[0213] Example

[0214] Although the present disclosure is described in more detail below in exemplary embodiments, the present disclosure is not limited to these exemplary embodiments within the scope of the subject matter of the present disclosure. Unless otherwise specified, "parts" and "%" regarding the amounts of ingredients are based on mass. The dispersion of titanium oxide particles is referred to as "pigment dispersion".

[0215] <Preparation of Titanium Oxide>

[0216] Commercially available rutile titanium oxide particles that had been surface treated in advance were used. The cumulative 50% particle size (D ) based on volume of the titanium oxide particles was measured using a particle size analyzer using a dynamic light scattering method (manufactured by Microtrac BEL, trade name "Nanotrac Wave II-EX150"). 50 ). Table 1 shows the properties of the titanium oxide particles.

[0217] Table 1 Characteristics of titanium oxide particles

[0218]

[0219] <Preparation of Pigment Dispersion>

[0220] Pigment dispersion 1

[0221] A styrene-methyl methacrylate-methacrylic acid copolymer (resin 1) having an acid value of 150 mgKOH / g and a weight-average molecular weight of 10,000 was prepared. 20.0 parts of resin 1 were neutralized with potassium hydroxide in an amount equimolar to its acid value, and an appropriate amount of pure water was added to resin 1 to prepare an aqueous solution of resin 1 having a resin content (solid content) of 20.0%. 40.0 parts of titanium oxide particles 1, 40.0 parts of an aqueous solution of resin 1, and ion exchange water, totaling 100.0 parts, were mixed and pre-dispersed using a homogenizer. The product was then dispersed (main dispersion) at 25°C for 12 hours using a paint agitator using 0.5 mm zirconium oxide beads. The zirconium oxide beads were filtered out, and an appropriate amount of ion exchange water was added as needed to prepare a pigment dispersion 1 having a titanium oxide particle content of 40.0% and a resin dispersant (resin 1) content of 8.0%.

[0222] <Preparation of ink>

[0223] 25.0 parts of the pigment dispersion 1 and the following components were mixed and stirred. Pressure filtration was performed using a membrane filter having a pore size of 5.0 μm (manufactured by Sartorius) to prepare an ink 1.

[0224] Details of the mixed ingredients are described below.

[0225] - Acrylic resin particles (manufactured by Nissin Chemical Industry Co., Ltd., trade name "Vinyblan

[0226] 2685", resin particle content: 30%): 20.0 parts

[0227] -Diethylene glycol: 10.0 parts

[0228] -Diethylene glycol isobutyl ether: 10.0 parts

[0229] - Fluorinated surfactant (manufactured by The Chemours Company, trade name "Capstone FS-3100"):

[0230] 1.0 copy

[0231] - Ion exchange water: 34.0 parts

[0232] The viscosity of ink 1 (Pa·s) and the density of the liquid component (g / cm 3 ) are 8Pa·s and 1.16g / cm 3 .

[0233] <Preparation of reaction solution>

[0234] The following components were mixed, stirred sufficiently, and filtered under pressure using a cellulose acetate filter (manufactured by Toyo Co., Ltd.) having a pore size of 3.0 μm to prepare a reaction solution 1.

[0235] -Magnesium sulfate: 2.0%

[0236] -1,2-Butanediol: 20.0%

[0237] - Fluorinated nonionic surfactant (manufactured by Levos Group, trade name "Capstone FS3100"): 0.5%

[0238] - Preservative (produced by Arch Chemical Company, trade name "Proxel GXL (S)"): 0.2%

[0239] - Ion exchange water: 77.3%

[0240] When magnesium sulfate is added, magnesium sulfate heptahydrate is used in an amount corresponding to the prescribed amount of magnesium sulfate.

[0241] <Liquid nozzle>

[0242] Head 1

[0243] preparation Figures 2 to 13B Shown and with Fig. 20A The liquid ejecting head of the protective member 140 is shown as the head 1. The protective member 140 is made of stainless steel.

[0244] Head 2

[0245] A head 2 having the same configuration as the head 1 except that it does not have the protective member 140 is prepared.

[0246] <Evaluation>

[0247] Ink 1 and reaction liquid 1 were set in an inkjet recording apparatus equipped with head 1 or head 2, and the ink was ejected at a temperature of 25° C. and a relative humidity of 50%. The results confirmed that the inkjet recording apparatus equipped with head 1 fully had the advantages of the present disclosure.

[0248] The present disclosure can provide an inkjet recording method having high ejection stability of a reaction liquid or ink.

[0249] Although the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the present disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. An inkjet recording method for recording an image on a recording medium, the method comprising: ejecting aqueous ink from a liquid ejection head; and ejecting an aqueous reaction liquid from a liquid ejecting head, the aqueous reaction liquid containing a reactant that reacts with the aqueous ink, Wherein, the liquid spray head configured to spray the aqueous reaction liquid includes: an element substrate having a nozzle configured to eject the aqueous reaction liquid, a pressure chamber configured to supply the aqueous reaction liquid to the nozzle, and an energy generating element configured to generate energy for ejecting the aqueous reaction liquid; an upstream channel configured to supply the aqueous reaction liquid to the pressure chamber; and a downstream passage communicating with the pressure chamber, The element substrate has a surface arranged to face the recording medium in a spraying direction of the aqueous reaction liquid, and The nozzle is located closer to the pressure chamber than the face in a direction perpendicular to the face.

2. The inkjet recording method according to claim 1, comprising ejecting the aqueous reaction liquid from a liquid ejecting head satisfying the following condition: a distance between the face and the ejection outlet in a direction perpendicular to the face is 1.0 μm or more and 50 μm or less.

3. The inkjet recording method according to claim 1, comprising ejecting the aqueous reaction liquid from a liquid ejecting head that satisfies the following condition: the shortest distance between the face and the ejection outlet in a direction parallel to the face is 1.0 mm or less.

4. The inkjet recording method according to claim 1, comprising: The aqueous reaction liquid is ejected from a liquid ejecting head that satisfies the following conditions: the element substrate includes: a substrate having the energy generating element on a first plane; a passage forming member disposed on the first plane and forming the pressure chamber and the nozzle; and a protection member disposed on a plane having the spout of the passage forming member and having an opening for exposing the spout, and The protection member has the surface.

5. The inkjet recording method according to claim 4, comprising ejecting the aqueous reaction liquid from a liquid ejection head satisfying the following condition: one of the openings of the protective member is provided to correspond to a nozzle array including a plurality of the nozzles arranged.

6. The inkjet recording method according to claim 4, comprising ejecting the aqueous reaction liquid from a liquid ejection head that satisfies the following condition: one of the openings of the protective member is provided to correspond to one of the ejection outlets. 7 . The inkjet recording method according to claim 4 , wherein the protective member contains a metal. 8 . The inkjet recording method according to claim 7 , wherein the protective member comprises stainless steel.

9. The inkjet recording method according to claim 1, comprising: The aqueous reaction liquid is ejected from a liquid ejecting head that satisfies the following conditions: the element substrate includes: a substrate having the energy generating element on a first plane; and a passage forming member disposed on the first plane and forming the pressure chamber and the nozzle, and The passage forming member has the surface. 10 . The inkjet recording method according to claim 9 , wherein the channel forming member has a recessed portion including the ejection opening inside.

11. The inkjet recording method according to claim 9, wherein the channel forming member is formed of a resin.

12. The inkjet recording method according to claim 4 or 9, comprising: The aqueous reaction liquid is ejected from a liquid ejecting head that satisfies the following conditions: the element substrate includes: a plurality of individual channels, each individual channel comprising the nozzle, the pressure chamber and the energy generating element; the upstream channel configured to supply the aqueous reaction liquid to the plurality of individual channels; and The downstream channel is used to allow the aqueous reaction liquid to flow out from the plurality of separate channels.

13. The inkjet recording method according to claim 4 or 9, wherein the aqueous reaction liquid in the pressure chamber is configured to circulate between the pressure chamber and the outside of the pressure chamber.

14. The inkjet recording method according to claim 4 or 9, wherein the aqueous reaction liquid in the pressure chamber circulates between the pressure chamber and the outside of the element substrate.

15. The inkjet recording method according to claim 1, comprising ejecting the aqueous reaction liquid having a viscosity at 25°C of 1.0 mPa·s or more and 10.0 mPa·s or less.

16. The inkjet recording method according to claim 4 or 9, comprising ejecting an aqueous reaction liquid containing a resin.

17. The inkjet recording method according to claim 4 or 9, comprising ejecting an aqueous ink having a solid density of 10 wt% or more and 30 wt% or less.

18. The inkjet recording method according to claim 4 or 9, comprising ejecting an aqueous ink containing titanium oxide.

19. The inkjet recording method according to claim 4 or 9, comprising ejecting the aqueous ink from a first ejection port of the liquid ejection head, and ejecting the aqueous reaction liquid from a second ejection port of the liquid ejection head.

20. The inkjet recording method according to claim 4 or 9, comprising: ejecting the aqueous ink from a second liquid ejecting head, Wherein, the second liquid spray head comprises: an element substrate having a nozzle configured to eject the aqueous ink, a pressure chamber configured to supply the aqueous ink to the nozzle, and an energy generating element configured to generate energy for ejecting the aqueous ink; an upstream channel configured to supply the aqueous ink to the pressure chamber; and a downstream passage communicating with the pressure chamber, The element substrate has a surface configured to face the recording medium in the ejection direction of the aqueous ink, and The ejection outlet of the second liquid ejection head is positioned closer to the pressure chamber than the surface is in a direction perpendicular to the surface.

Images