ELECTRON BEAM-CURABLE AQUEOUS INKJET INK COMPOSITION

Abstract

Disclosed is an electron beam curable water-based ink-jet ink composition comprising a colorant, a resin emulsion, a water-soluble photopolymerizable monomer, and water, wherein the water-soluble photopolymerizable monomer comprises an acrylamide derivative, wherein a content of the acrylamide derivative is 20 to 55% by mass in the electron beam curable water-based ink-jet ink composition, and wherein a content of the resin emulsion is 1 to 11% by mass in terms of a solid content in the electron beam curable water-based ink-jet ink composition.

Claims

1. An electron beam curable water-based ink-jet ink composition comprising a colorant, a resin emulsion, a water-soluble photopolymerizable monomer, and water, wherein the water-soluble photopolymerizable monomer comprises an acrylamide derivative, wherein a content of the acrylamide derivative is 20 to 55% by mass in the electron beam curable water-based ink-jet ink composition, and wherein a content of the resin emulsion is 1 to 11% by mass in terms of a solid content in the electron beam curable water-based ink-jet ink composition.

2. The electron beam curable water-based ink-jet ink composition of claim 1, wherein the water content is 40 to 75% by mass in the electron beam curable water-based ink-jet ink composition.

Description

EXAMPLES

[0065] Hereinafter, the present invention will be described in more detail with reference to Examples. The present invention is not limited to these Examples. Besides, “%” means “% by mass” and “part” means “part(s) by mass”, unless otherwise specified.

[0066] Raw materials used and preparation methods are shown below.

<Resin Emulsion>

[0067] Urethane-based resin emulsion: solid content: 34%, trade name: R-972, manufactured by DSM

[0068] Acrylic-based resin emulsion: solid content: 19.5%, trade name: A-1125, manufactured by DSM

<Water-Soluble Photopolymerizable Monomer>

[0069] Dimethylacrylamide

[0070] N-hydroxyethyl acrylamide

[0071] Diethyl acrylamide

[0072] Acryloyl morpholine

[0073] PEG (600) diacrylate

[0074] 4-hydroxybutyl acrylate

<Other Additives>

[0075] Acetylenediol-based surface conditioner: Trade name: Olfine E1010, manufactured by Nissin Chemical Co., Ltd.

Example 1. Cyan Ink Composition

[0076] According to the compounding formulation (% by mass) shown in Table 1, a pigment, a pigment dispersant, dimethylacrylamide, a urethane-based resin emulsion, an acetylenediol-based surface conditioner, and water are dispersed, stirred and mixed to obtain a part by mass of the ink composition in Example 1.

TABLE-US-00001 TABLE 1 Example 1 2 3 4 5 6 7 8 9 10 Water 41.7 31.7 36.7 51.7 61.7 31.7 39.5 41.1 42.8 41.7 Dimethylacrylamide 40.0 40.0 30.0 40.0 20.0 50.0 40.0 40.0 40.0 — N-hydroxyethyl — — — — — — — — — 40.0 acrylamide Diethyl acrylamide — — — — — — — — — — Acryloyl morpholine — — — — — — — — — — PEG (600) diacrylate — — — — — — — — — — 4-hydroxybutyl acrylate — — — — — — — — — — Urethane-based 15.0 — 30.0 5.0 15.0 15.0 15.0 15.0 15.0 15.0 (NV: 34%) Acrylic-based — 25.0 — — — — — — — — (NV: 19.5%) Acetylenediol-based 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 surface conditioner Pigment Blue 15:4 2.0 2.0 2.0 2.0 2.0 2.0 — — — 2.0 Pigment Red 19 — — — — — — 3.6 — — — Pigment Yellow 180 — — — — — — — 2.4 — — Carbon black — — — — — — — — 1.2 — Pigment dispersant: 0.8 0.8 0.8 0.8 0.8 0.8 1.4 1.0 0.5 0.8 Solsperse 39000 Total 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 Total content of water 51.6 51.8 56.2 55.0 71.6 41.6 49.3 50.9 52.6 51.5 Storage stability ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Coating film resistance ◯ ◯ ◯ ◯ Δ ◯ ◯ ◯ ◯ ◯ Ejection stability ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Example Comparative example 11 12 13 1 2 3 4 5 Water 41.7 41.7 41.7 41.7 41.7 21.7 31.7 50.7 Dimethylacrylamide — — 30.0 10.0 — 60.0 25.0 45.0 N-hydroxyethyl acrylamide — — — — — — — — Diethyl acrylamide 40.0 — — — — — — — Acryloyl morpholine — 40.0 — — — — — — PEG (600) diacrylate — — 10.0 30.0 — — — 4-hydroxybutyl acrylate — — — — 40.0 — — — Urethane-based (NV: 34%) 15.0 15.0 15.0 15.0 15.0 15.0 40.0 1.0 Acrylic-based (NV: 19.5%) — — — — — — — Acetylenediol-based surface conditioner 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Pigment Blue 15:4 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Pigment Red 19 — — — — — — — — Pigment Yellow 180 — — — — — — — — Carbon black — — — — — — — — Pigment dispersant: Solsperse 39000 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Total 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.0 Total content of water 51.5 51.5 51.5 51.5 51.5 31.6 57.7 51.4 Storage stability ◯ ◯ Δ X X ◯ Δ ◯ Coating film resistance ◯ ◯ ◯ Δ ◯ X ◯ X Ejection stability ◯ ◯ ◯ ◯ Δ ◯ X ◯

Examples 2 to 13, Comparative Examples 1 to 5

[0077] Each ink composition was prepared by the similar method as in Example 1 according to the respective compounding formulation shown in Table 1.

<Evaluation on Ink Composition and Printed Matter>

[0078] Using the ink compositions in Examples 1 to 13 and Comparative examples 1 to 5, storage stability, coating film resistance, and ejection stability were evaluated according to the following evaluation methods and evaluation criteria. The results are shown in Table 1.

(1) Storage Stability

[0079] The ink composition was placed in a glass bottle, and a viscosity (m.Math.Pa) at 25° C. was measured using a viscometer (RE100L type viscometer, manufactured by Toki Sangyo Co., Ltd.). Then, it was sealed and stored at 60° C. for 1 month, and a viscosity after storage (25° C.) was measured with the viscometer. Storage stability was evaluated with a rate of change in viscosity (60° C., (viscosity after 1 month-viscosity before storage)/viscosity before storage)).

[Evaluation Criteria]

[0080] ◯: The rate of change in viscosity was less than 10%.

[0081] Δ: The rate of change in viscosity was 10% or more and less than 20%.

[0082] x: The rate of change in viscosity was 20% or more.

(2) Coating Film Resistance

[0083] Each electron beam curable water-based ink-jet ink composition obtained in Examples and Comparative examples was coated on a base material (polyethylene terephthalate film having a corona discharge treatment on one side (Ester film E5100 (manufactured by Toyobo Co., Ltd., trade name), thickness: 12 μm, hereinafter referred to as a PET film) with a #4 bar coater. Next, it was cured with an EB irradiation device under an acceleration voltage of 90 kV and an irradiation dose of 30 kGy to form a cured film. How the cured film was removed from the PET film when the coating film was rubbed with a bleached cloth 500 g×200 times was visually observed using a Gakushin-Type fastness tester (manufactured by Daiei Kagaku Seiki MFG Co., Ltd.). Evaluation was performed according to the following criteria.

[Evaluation Criteria]

[0084] ◯: The cured film was not removed.

[0085] Δ: There was a scratch on the surface of the cured film.

[0086] x: The cured film was removed and the base material was visible.

(3) Ejection Stability

[0087] An inkjet recording device equipped with an inkjet nozzle for low-viscosity ink and each electron beam curable water-based ink-jet ink composition obtained in Examples and Comparative examples were placed under an ambient temperature of 25° C. for 24 hours, and temperatures of the inkjet recording device and each ink composition were set to be 25° C. Then, they were continuously typed on the PET film using each electron beam curable water-based ink-jet ink composition under the ambient temperature of 25° C. to evaluate the ejection stability, and evaluation was performed according to the following evaluation criteria.

[Evaluation Criteria]

[0088] ◯: There was almost no printing turbulence, and a stable ejection was achieved.

[0089] Δ: There was some printing turbulence, but ejection was achieved.

[0090] x: Ejection was not achieved.

[0091] As shown in Table 1, all of the ink compositions in Examples 1 to 13 showed excellent storage stability, coating film resistance, and ejection stability. On the other hand, the ink composition in Comparative example 1 having a small content of the acrylamide derivative was inferior in storage stability and coating film resistance. The ink composition in Comparative example 2 comprising no acrylamide derivative was inferior in storage stability and ejection stability. The ink composition in Comparative example 3 having a large content of the acrylamide derivative was inferior in coating film resistance. The ink composition of Comparative example 4 having a large content of the resin emulsion was inferior in storage stability and ejection stability. The ink composition of Comparative example 5 having a small content of the resin emulsion was inferior in coating film resistance.