JP-2026074595-A - Inkjet ink composition and inkjet recording method

Abstract

[Problem] To provide an inkjet ink composition that exhibits excellent clogging recovery and continuous ejection stability. [Solution] An inkjet ink composition according to one embodiment of the present invention is an inkjet ink composition containing a colorant, an organic solvent, and water, wherein the organic solvent contains triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, and one or more selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam. [Selection Diagram] None

Inventors

• 石田 紘平
• 有賀 友洋

Assignees

• セイコーエプソン株式会社

Dates

Publication Date

20260507

Application Date

20241021

Claims (8)

1. An inkjet ink composition containing a colorant, an organic solvent, and water, The aforementioned organic solvent is triethylene glycol monobutyl ether, Tetraethylene glycol monobutyl ether and An inkjet ink composition containing one or more selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam.
2. The inkjet ink composition according to claim 1, wherein the content of the triethylene glycol monobutyl ether is 1.0% by mass or more and 20.0% by mass or less based on the total amount of the inkjet ink composition.
3. The inkjet ink composition according to claim 1, wherein the content of one or more substances selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam is 5.0% by mass or more and 15.0% by mass or less based on the total amount of the inkjet ink composition.
4. The inkjet ink composition according to claim 1, wherein the mass ratio of the tetraethylene glycol monobutyl ether content to the triethylene glycol monobutyl ether content is 5% or more and 15% or less.
5. The inkjet ink composition according to claim 1, wherein the colorant comprises a water-soluble dye.
6. The inkjet ink composition according to claim 5, wherein the water-soluble dye is one or more selected from acid dyes, direct dyes, and reactive dyes.
7. The inkjet ink composition according to claim 5, wherein the content of the water-soluble dye is 5.0% by mass or more and 20.0% by mass or less based on the total amount of the inkjet ink composition.
8. An inkjet recording method comprising the step of ejecting an inkjet ink composition according to any one of claims 1 to 7 from an inkjet head and adhering it to a recording medium.

Description

This invention relates to an inkjet ink composition and an inkjet recording method. Inkjet recording methods, which enable the recording of high-resolution images with relatively simple equipment, are undergoing rapid development in various fields. Within this context, research is being conducted on solvents used in ink compositions to ensure they are suitable for inkjet recording. For example, Patent Document 1 describes a solvent-based inkjet ink composition containing tetraethylene glycol monobutyl ether as an organic solvent. Japanese Patent Publication No. 2024-048626 Table 1 shows the composition examples of the inkjet ink compositions for each example and their evaluation results.Table 2 shows the composition examples of inkjet ink compositions for each example and comparative example, and their evaluation results. The following describes embodiments of the present invention. The embodiments described below illustrate examples of the present invention. The present invention is not limited to the embodiments described below and includes various modifications that do not alter the essence of the invention. Furthermore, not all of the configurations described below are necessarily essential to the present invention. In this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively. In this specification, "(meth)acrylic" means acrylic or methacrylic, and "(meth)acrylate" means acrylate or methacrylate. 1. Inkjet Ink Composition An inkjet ink composition according to one embodiment of the present invention is an inkjet ink composition containing a colorant, an organic solvent, and water, wherein the organic solvent contains triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, and one or more selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam. Triethylene glycol monobutyl ether (hereinafter also referred to as "BTG") has a relatively high hydrophobicity due to the presence of an alkoxy group. Therefore, including BTG can improve the solubility and dispersibility of colorants in water-based inkjet ink compositions, making colorant precipitation and solidification less likely. As a result, the clogging recovery properties of water-based inkjet ink compositions can be improved. On the other hand, BTG has a tendency to increase the viscosity of water-based inkjet ink compositions. When the viscosity of the inkjet ink composition increases, ejection from the inkjet head may become unstable. The present inventors have conducted diligent research and have discovered that by including tetraethylene glycol monobutyl ether (hereinafter also referred to as "BTeG") and one or more substances selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam in addition to BTG, the ejection stability of the inkjet ink composition can be improved. It is presumed that the mixing of BTG and BTeG reduced the viscosity increase caused by BTG while improving the solubility and dispersibility of the colorant. Furthermore, it is presumed that the inclusion of one or more substances selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam mitigated the high hydrophobicity of BTG and BTeG, resulting in a good balance of hydrophilicity and hydrophobicity in the water-based ink components and excellent continuous dispensing stability. Therefore, the inkjet ink composition according to this embodiment provides excellent solubility and dispersibility of the colorant, superior clogging recovery, and excellent continuous ejection stability. The components contained in the inkjet ink composition according to this embodiment will be described below. 1.1 Colorants The inkjet ink composition according to this embodiment contains colorants. Examples of colorants include dyes and pigments. 1.1.1 Dyes Examples of dyes include water-soluble dyes and disperse dyes. In this embodiment, the inkjet ink composition preferably contains a water-soluble dye as the colorant. When the colorant contains a water-soluble dye, precipitation and solidification of the colorant are less likely to occur, and it is easier to achieve a better balance between hydrophilicity and hydrophobicity in the ink components, thus tending to improve clogging recovery and continuous ejection stability. Various water-soluble dyes can be used as water-soluble dyes, including, for example, acid dyes, direct dyes, and reactive dyes. In the inkjet ink composition according to this embodiment, it is preferable that the water-soluble dye is one or more selected from acid dyes, direct dyes, and reactive dyes. When the water-soluble dye is one or more selected from these, precipitation and solidification of the colorant are less likely to occur, and it is easier to achieve a better balance between hydrophilicity and hydrophobicity in the ink components, which tends to improve clogging recovery and continuous ejection stability. Examples of acid dyes