US 11,866,593 B2
Ultraviolet curable inkjet ink
Yohei Konda, Tokyo (JP); and Gosuke Kikutsuji, Tokyo (JP)
Assigned to TOYO INK SC HOLDINGS CO., LTD., Tokyo (JP); and TOYOCOLOR CO., LTD., Tokyo (JP)
Appl. No. 17/634,332
Filed by TOYO INK SC HOLDINGS CO., LTD., Tokyo (JP); and TOYOCOLOR CO., LTD., Tokyo (JP)
PCT Filed Aug. 11, 2021, PCT No. PCT/JP2021/029663
§ 371(c)(1), (2) Date Feb. 10, 2022,
PCT Pub. No. WO2022/137634, PCT Pub. Date Jun. 30, 2022.
Claims priority of application No. 2020-216783 (JP), filed on Dec. 25, 2020.
Prior Publication US 2023/0002630 A1, Jan. 5, 2023
Int. Cl. C09D 11/38 (2014.01); C09D 11/101 (2014.01); C09D 11/326 (2014.01)
CPC C09D 11/101 (2013.01) [C09D 11/326 (2013.01); C09D 11/38 (2013.01)] 9 Claims
 
1. An ultraviolet curable inkjet ink comprising a colorant, a polymerizable monomer, and a photopolymerization initiator, wherein
the polymerizable monomer comprises a compound represented by the following General formula (A),
the photopolymerization initiator comprises
an ethoxyphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, and
an acylphosphine oxide photopolymerization initiator different than the ethoxyphenyl(2,4,6-trimethylbenzoyl)phosphine oxide,
the ratio of the content of the compound represented by the General formula (A) and the content of the ethoxyphenyl(2,4,6-trimethylbenzoyl)phosphine oxide is 2:1 to 8.5:1 by mass ratio,
the ratio of the content of the ethoxyphenyl(2,4,6-trimethylbenzoyl)phosphine oxide and the content of the acylphosphine oxide photopolymerization initiator is 0.5:1 to 3:1 by mass ratio, and
the content of a monofunctional monomer in the ultraviolet curable inkjet ink is 25% by mass or less,
CH2═CH—CO—(O—CH2CH2)n—O—R  General formula (A):
wherein in General formula (A), R represents an acryloyl group or a vinyl group, and n represents an integer from 2 to 10,
wherein the acylphosphine oxide photopolymerization initiator different than the ethoxyphenyl(2,4,6-trimethylbenzoyl)phosphine oxide comprises bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and
wherein the content of the compound represented by the General formula (A) in the ultraviolet curable inkjet ink is 8 to 20% by mass.