US-12617961-B2 - UV-curable aqueous inkjet printing ink composition

Abstract

A UV-curable aqueous inkjet printing ink composition contains: water-soluble acrylamide-based monomers by 20.0 to 70.0% by mass, water-soluble hydroxyl group-containing monofunctional monomers by 5.0 to 60.0% by mass, and water-insoluble polymerizable compounds by 8.0 to 35.0% by mass, relative to the total mass of all polymerizable components; a photopolymerizable initiator and/or sensitizer by 3.0 to 10.0 parts by mass relative to 100 parts by mass representing the total mass of all polymerizable components; a pigment; and water; wherein the ratio of the water-soluble acrylamide-based monomers and water-soluble hydroxyl group-containing monofunctional monomers, (water-soluble acrylamide-based monomers/water-soluble hydroxyl group-containing monofunctional monomers), is 0.3 to 10.0; and the ink composition has ability to be partially cured by being irradiated with a UV-LED light having a peak wavelength between 365 and 405 nm, to a cumulative light quantity of 100 mJ/cm 2 or less.

Inventors

• Daigo SHIOZAKI
• Jun KINJOH
• Okinori NAKASHIMA

Assignees

• SAKATA INX CORPORATION

Dates

Publication Date

20260505

Application Date

20211124

Priority Date

20210226

Claims (10)

1. 1 . A UV-curable aqueous inkjet printing ink composition, which comprises, relative to a total mass of all polymerizable components, each of: water-soluble acrylamide-based monomers by 20.0 to 70.0% by mass, water-soluble hydroxyl group-containing monofunctional monomers by 5.0 to 60.0% by mass, and water-insoluble polymerizable compound(s) by 8.0 to 35.0% by mass, which includes polymerizable oligomers by 5.0 to 25.0% by mass; which further comprises, relative to 100 parts by mass representing a total mass of all polymerizable components, a photopolymerizable initiator and/or sensitizer by 3.0 to 10.0 parts by mass; which further contains: a pigment; a pigment dispersant having a maleimide structure, or a pigment dispersant having a maleimide structure and a pigment dispersant having a pyridine ring; and water; wherein a ratio of the water-soluble acrylamide-based monomers and the water-soluble hydroxyl group-containing monofunctional monomers, (water-soluble acrylamide-based monomers/water-soluble hydroxyl group-containing monofunctional monomers), is from 0.3 to 10.0; and the ink composition has ability to be partially cured by being irradiated with a UV-LED light having a peak wavelength between 365 and 405 nm, at a cumulative light quantity of 100 mJ/cm 2 or less, wherein the partially cured ink composition is non-flowable while maintaining uncured components and water.
2. 2 . The UV-curable aqueous inkjet printing ink composition according to claim 1 , wherein the water-soluble acrylamide-based monomers include acryloyl morpholine.
3. 3 . The UV-curable aqueous inkjet printing ink composition according to claim 1 , wherein the water-soluble hydroxyl group-containing monofunctional monomers include 4-hydroxybutyl acrylate.
4. 4 . The UV-curable aqueous inkjet printing ink composition according to claim 1 , wherein a content of the water is 10.0 to 40.0% by mass relative to the ink composition as a whole.
5. 5 . A method for printing using a UV-curable aqueous inkjet printing ink composition, which comprises, relative to a total mass of all polymerizable components, each of: water-soluble acrylamide-based monomers by 20.0 to 70.0% by mass, water-soluble hydroxyl group-containing monofunctional monomers by 5.0 to 60.0% by mass, and water-insoluble polymerizable compound(s) by 8.0 to 35.0% by mass, which includes polymerizable oligomers by 5.0 to 25.0% by mass; which further comprises, relative to 100 parts by mass representing a total mass of all polymerizable components, a photopolymerizable initiator and/or sensitizer by 3.0 to 10.0 parts by mass; which further contains: a pigment; a pigment dispersant having a maleimide structure, or a pigment dispersant having a maleimide structure and a pigment dispersant having a pyridine ring; and water; wherein a ratio of the water-soluble acrylamide-based monomers and the water-soluble hydroxyl group-containing monofunctional monomers, (water-soluble acrylamide-based monomers/water-soluble hydroxyl group-containing monofunctional monomers), is from 0.3 to 10.0; said method comprising: a step to discharge the ink composition on a substrate by inkjet printing; a step to partially curing the ink composition by irradiating it using a UV-LED lamp having a peak wavelength between 365 and 405 nm, at a cumulative light quantity of 100 mJ/cm 2 or less, wherein the partially cured ink composition is non-flowable while maintaining uncured components and water; and a step to subsequently fully cure it with ultraviolet ray.
6. 6 . The method for printing using a UV-curable aqueous inkjet printing ink composition according to claim 5 , wherein the ink composition contains acryloyl morpholine as the water-soluble acrylamide-based monomers.
7. 7 . The method for printing using a UV-curable aqueous inkjet printing ink composition according to claim 5 , wherein the water-soluble hydroxyl group-containing monofunctional monomers include 4-hydroxybutyl acrylate.
8. 8 . The method for printing using a UV-curable aqueous inkjet printing ink composition according to claim 5 , wherein a content of the water is 10.0 to 40.0% by mass relative to the ink composition as a whole.
9. 9 . The UV-curable aqueous inkjet printing ink composition according to claim 1 , wherein the polymerizable oligomers include one or more oligomers selected from amine-modified (meth)acrylate oligomers and epoxy (meth)acrylate oligomers.
10. 10 . The method for printing using a UV-curable aqueous inkjet printing ink composition according to claim 5 , wherein the polymerizable oligomers in the ink composition include one or more oligomers selected from amine-modified (meth)acrylate oligomers and epoxy (meth)acrylate oligomers.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is the U.S. National Phase under 35 U.S.C. § 371 of International Application PCT/JP2021/042931, filed Nov. 24, 2021, which claims priority to Japanese Patent Application No. JP2021-030998, filed Feb. 26, 2021. The International Application was published under PCT Article 21(2) in a language other than English. TECHNICAL FIELD The present invention relates to a UV-curable aqueous inkjet printing ink composition and a method for printing. BACKGROUND ART Patent Literature 1 describes a UV-curable aqueous inkjet printing ink composition containing water-soluble resin or emulsion resin and UV-curable compound, as well as an art of applying primary drying and secondary drying by means of heating post-printing, followed by irradiation of ultraviolet ray, to obtain a final printed matter, while Patent Literature 2 describes a UV-curable water-based inkjet recording ink containing monomer components selected from n-butyl acrylate, t-butylacrylamide, 2-hydroxyethyl acrylate, etc., as well as an art of curing the ink with a single irradiation of ultraviolet ray. BACKGROUND ART LITERATURE Patent Literature Patent Literature 1: Japanese Patent Laid-open No. 2012-111822Patent Literature 2: Japanese Patent Laid-open No. 2006-028377 SUMMARY OF THE INVENTION Problems to be Solved by the Invention According to the invention described in each of the aforementioned patent literatures, what is proposed can be printed as an inkjet printing ink composition; however, no consideration is given to improving its compatibility and storage stability as a UV-curable aqueous inkjet printing ink composition or to eliminating the grainy feel of printed areas. An object of the present invention is to obtain a UV-curable aqueous inkjet printing ink composition, as well as a method for printing using the same, offering excellent compatibility and storage stability, and also capable of forming printed areas free of grainy feel while demonstrating excellent curability and water resistance, by conducting partial curing after printing, followed by full curing. Means for Solving the Problems As a result of studying in earnest to achieve the aforementioned object, the inventors of the present invention found that the aforementioned object could be achieved by a specific composition and a specific method for printing, and eventually completed the present invention. 1. A UV-curable aqueous inkjet printing ink composition, comprising, relative to a total mass of all polymerizable components, each of: water-soluble acrylamide-based monomers by 20.0 to 70.0% by mass,water-soluble hydroxyl group-containing monofunctional monomers by 5.0 to 60.0% by mass, andwater-insoluble polymerizable compound(s) by 8.0 to 35.0% by mass; further comprising, relative to 100 parts by mass representing a total mass of all polymerizable components, a photopolymerizable initiator and/or sensitizer by 3.0 to 10.0 parts by mass;further containing:a pigment; andwater;wherein a ratio of the water-soluble acrylamide-based monomers and the water-soluble hydroxyl group-containing monofunctional monomers (acrylamide-based monomers/hydroxyl group-containing monofunctional monomers) is from 0.3 to 10.0; andthe ink composition is for printing that includes a step in which it is partially cured by irradiating it with a UV-LED light having a peak wavelength between 365 and 405 nm, at a cumulative light quantity of 100 mJ/cm2 or less. 2. The UV-curable aqueous inkjet printing ink composition according to 1, wherein the water-soluble acrylamide-based monomers include acryloyl morpholine. 3. The UV-curable aqueous inkjet printing ink composition according to 1 or 2, wherein the water-soluble hydroxyl group-containing monofunctional monomers include 4-hydroxybutyl acrylate. 4. The UV-curable aqueous inkjet printing ink composition according to any one of 1 to 3, wherein the content of the water is 10.0 to 40.0% by mass relative to the ink composition as a whole. 5. The UV-curable aqueous inkjet printing ink composition according to any one of 1 to 4, wherein it contains a pigment dispersant having a maleimide structure and/or pigment dispersant having a pyridine ring. 6. A method for printing using a UV-curable aqueous inkjet printing ink composition, which comprises, relative to a total mass of all polymerizable components, each of: water-soluble acrylamide-based monomers by 20.0 to 70.0% by mass,water-soluble hydroxyl group-containing monofunctional monomers by 5.0 to 60.0% by mass, andwater-insoluble polymerizable compound(s) by 8.0 to 35.0% by mass; which further comprises, relative to 100 parts by mass representing a total mass of all polymerizable components, a photopolymerizable initiator and/or sensitizer by 3.0 to 10.0 parts by mass;further containing:a pigment; andwater;wherein a ratio of the water-soluble acrylamide-based monomers and the water-soluble hydroxyl group-containing monofunctiona