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US-12617962-B2 - Aqueous ink, ink ejection device, image recording device, and printing method

US12617962B2US 12617962 B2US12617962 B2US 12617962B2US-12617962-B2

Abstract

An aqueous ink includes water, a solvent group A having a vapor pressure of 0.07 Pa or more at 25° C., a thickener, and a binder polymer. The solvent group A is present in the aqueous ink in a weight percent of 31.0 wt % to 55.0 wt % with respect to a total amount of the aqueous ink. The thickener is present in the aqueous ink in a weight percent of 13.0 wt % or less with respect to the total amount of the aqueous ink. The aqueous ink has a viscosity of 10 mPa·s to 14 mPa·s at 25° C.

Inventors

  • Hirofumi KURIKI
  • Taro NAGANO

Assignees

  • BROTHER KOGYO KABUSHIKI KAISHA

Dates

Publication Date
20260505
Application Date
20240301
Priority Date
20230302

Claims (14)

  1. 1 . An aqueous ink, comprising: water; a solvent group A having a vapor pressure of 0.07 Pa or more at 25° C.; a thickener; and a binder polymer, wherein: the solvent group A is present in the aqueous ink in a weight percent of 31.0 wt % to 55.0 wt % with respect to a total amount of the aqueous ink, the thickener is present in the aqueous ink in a weight percent of 13.0 wt % or less with respect to the total amount of the aqueous ink, the thickener includes a high viscosity binder polymer dispersion liquid in which the binder polymer is dispersed, the high viscosity binder polymer dispersion liquid has a viscosity of 100 mPa·s or more and less than 5000 mPa·s at 25° C. when being added to a high viscosity binder polymer dispersion medium such that the binder polymer is present in the high viscosity binder polymer dispersion liquid at 38.0 wt %, the binder polymer is present in the aqueous ink in a weight percent of 4.2 wt % or less with respect to the total amount of the aqueous ink, the binder polymer is an acrylic polymer, the aqueous ink has a viscosity of 10 mPa·s to 14 mPa·s at 25° C., and an evaporation rate is 70% or more when 5 g of the aqueous ink is placed in an upwardly opened container having a diameter of 60 mm and heated at 100° C. for 4 hours indoors at a room temperature of 25° C. and a humidity of 65%.
  2. 2 . The aqueous ink according to claim 1 , further comprising: a surfactant, wherein the solvent group A includes two different solvents.
  3. 3 . The aqueous ink according to claim 1 , wherein the thickener includes a solvent group B having a vapor pressure of less than 0.07 Pa at 25° C., and the solvent group B is present in the aqueous ink in a weight percent of 3.0 wt % or less with respect to the total amount of the aqueous ink.
  4. 4 . An ink ejection device, comprising: a head including a nozzle configured to eject the aqueous ink according to claim 1 ; and a heater configured to heat at least one of a non-absorbing medium to which the aqueous ink ejected from the nozzle is attached and the aqueous ink attached to the non-absorbing medium.
  5. 5 . The ink ejection device according to claim 4 , wherein the heater is configured to heat at a heating temperature of 60° C. or higher.
  6. 6 . The ink ejection device according to claim 5 , wherein the nozzle is configured to eject the aqueous ink in a vertical direction.
  7. 7 . The ink ejection device according to claim 5 , wherein the nozzle is configured to eject the aqueous ink in a horizontal direction.
  8. 8 . The ink ejection device according to claim 5 , further comprising: a cap configured to abut against the head and cover the nozzle; a suction pump configured to suction an ink in the cap; and a controller, wherein the controller is configured to periodically execute a purge process of driving the suction pump in a state where the cap covers the nozzle during an image recording process of ejecting the aqueous ink from the nozzle.
  9. 9 . A printing method, comprising: ejecting the aqueous ink according to claim 1 from a nozzle; and heating, by a heater, at least one of a non-absorbing medium to which the aqueous ink ejected from the nozzle is attached and the aqueous ink attached to the non-absorbing medium.
  10. 10 . The printing method according to claim 9 , wherein in the heating, the heater is configured to heat at least one of the non-absorbing medium and the aqueous ink at 60° C. or higher.
  11. 11 . The printing method according to claim 10 , wherein in the ejecting, the nozzle is configured to eject the aqueous ink in a vertical direction.
  12. 12 . The printing method according to claim 10 , wherein in the ejecting, the nozzle is configured to eject the aqueous ink in a horizontal direction.
  13. 13 . The printing method according to claim 9 , further comprising: periodically executing, by a controller, a purge process of driving a suction pump configured to suction an ink in a cap in a state where the cap covers the nozzle during an image recording process of recording an image on the non-absorbing medium by ejecting the aqueous ink from the nozzle.
  14. 14 . The printing method according to claim 13 , further comprising: conveying, by a conveyer, the non-absorbing medium to a position facing a head before the first ejecting is performed.

Description

REFERENCE TO RELATED APPLICATIONS This application claims priority from Japanese Patent Application No. 2023-031593 filed on Mar. 2, 2023 and Japanese Patent Application No. 2023-186300 filed on Oct. 31, 2023. The entire contents of these priority applications are incorporated herein by reference. BACKGROUND ART As an aqueous ink used in an ink jet recording device, an aqueous ink for ink jet recording of a related art is known. The aqueous ink for ink jet recording of the related art contains water, a water-soluble organic solvent, a pH adjusting agent, a viscosity adjusting agent, a surface tension adjusting agent, an antifungal agent, and the like. In the related art, a viscosity of the ink is adjusted to be low so that the ink is easily ejected from a nozzle of an ink jet head. The above aqueous ink for ink jet recording has an excellent ink ejection property, but it is difficult to obtain a sharp image quality because the viscosity of the ink is low. This can lead to ragged edges. Therefore, in order to improve sharpness, it is conceivable to increase the viscosity beyond that of the above aqueous ink. However, this adjustment might deteriorate the ink ejection property, consume a large amount of solvent, and thus deteriorate a drying property of the ink depending on a type of the solvent and a solvent ratio. Moreover, a higher viscosity could cause the ink attached to the nozzle to dry quickly, increasing the likelihood of clogging, thus deteriorating a so-called decapping property. SUMMARY An object of the present disclosure is to provide an aqueous ink, an ink ejection device, an image recording device, and a printing method that an ink ejection property and image sharpness and also ensure a drying property and a decapping property. An aqueous ink according to one aspect of the present disclosure includes water, a solvent group A having a vapor pressure of 0.07 Pa or more at 25° C., a thickener, and a binder polymer. The solvent group A is present in the aqueous ink in a weight percent of31.0 wt % to 55.0 wt % with respect to a total amount of the aqueous ink. The thickener is present in the aqueous ink in a weight percent of 13.0 wt % or less with respect to the total amount of the aqueous ink. The aqueous ink has a viscosity of 10 mPa·s to 14 mPa·s at 25° C. According to the present disclosure, the ink ejection property and the image sharpness are ensured, and the drying property and the decapping property are ensured. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an external perspective view of an image recording device 100 according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view taken along a line II-II in FIG. 1. FIG. 3 is a schematic diagram showing an ink circuit 113. FIG. 4 is a block diagram showing a controller 130. DESCRIPTION Hereinafter, a preferred embodiment of the present disclosure will be described. The present embodiment is merely one embodiment of the present disclosure, and it is needless to say that the embodiment can be modified without changing the gist of the present disclosure. In the following description, an advancement movement from a start point to an end point of an arrow is expressed as an “orientation”, and a unidirectional or bidirectional movement along a line connecting the start point and the end point of the arrow is expressed as a “direction”. In the following description, an up-down direction 7 is defined with reference to a state where an image recording device 100 is usable (a state in FIG. 1), a front-rear direction 8 is defined with a side where a discharge port 33 is provided as a front side (a front surface), and a left-right direction 9 is defined when the image recording device 100 is viewed from the front side (the front surface). Appearance Configuration of Image Recording Device 100 The image recording device 100 (an example of an ink ejection device) shown in FIG. 1 records an image on a sheet S forming a roll body 37 (see FIG. 2) using an ink jet recording method. As shown in FIG. 1, the image recording device 100 includes a housing 30. The housing 30 has a substantially rectangular parallelepiped shape as a whole. A frame for supporting each member may be appropriately provided inside the housing 30. The slit-shaped discharge port 33 that is long in the left-right direction 9 is formed in a front surface 30F of the housing 30. The image-recorded sheet S (see FIG. 2) is discharged from the discharge port 33. An operation panel 44 is provided on the front surface 30F. A user performs an input on the operation panel 44 to operate the image recording device 100 or confirm various settings. A right cover 35A is located on a right surface 30R of the housing 30. By opening and closing the right cover 35A, a holder 35 and the like (see FIG. 2) located in a sheet storage space 32C are exposed or shielded. A front cover 29 is located on the front surface 30F of the housing 30. The front cover 29 can be opened around a pivot shaft (n