Active energy ray-curable inkjet ink, inkjet recorded article, and method for producing inkjet recorded article

Abstract

An active energy ray-curable inkjet ink containing polymerizable compounds and a polymerization initiator, wherein the polymerizable compounds include at least 5 types of polyfunctional polymerizable compounds having molecular weights within a range from 150 to 500, and include substantially no monofunctional polymerizable compounds.

Claims

1. An active energy ray-curable inkjet ink containing polymerizable compounds and a polymerization initiator, wherein the polymerizable compounds include at least 5 types of polyfunctional polymerizable compounds having molecular weights within a range from 150 to 500, the polyfunctional polymerizable compounds include a difunctional polymerizable compound having a homopolymer glass transition temperature of −15° C. to +40° C. in an amount of 5 to 30% by mass relative to the total mass of the ink, and include substantially no monofunctional polymerizable compounds.

2. The active energy ray-curable inkjet ink according to claim 1, wherein the at least 5 types of polyfunctional polymerizable compounds having molecular weights within a range from 150 to 500 are composed of at least one type of compound selected from the group consisting of difunctional polymerizable compounds and trifunctional polymerizable compounds.

3. The active energy ray-curable inkjet ink according to claim 1, wherein the at least 5 types of polyfunctional polymerizable compounds having molecular weights within a range from 150 to 500 are difunctional polymerizable compounds, and the amount of each of the difunctional polymerizable compounds is, independently, from 5 to 50% by mass relative to the total mass of the ink.

4. The active energy ray-curable inkjet ink according to claim 1, wherein one of the polyfunctional polymerizable compounds having molecular weights within a range from 150 to 500 is 2-(vinyloxyethoxy)ethyl acrylate.

5. The active energy ray-curable inkjet ink according to claim 1, wherein at least one of the polyfunctional polymerizable compounds having molecular weights within a range from 150 to 500 is a compound represented by general formula (1) shown below:
CH.sub.2═CH—CO—O—X—O—CO—CH═CH.sub.2  (1) (In the formula, X represents a linear or branched alkylene group of 1 to 12 carbon atoms).

6. The active energy ray-curable inkjet ink according to claim 1, wherein the polyfunctional polymerizable compounds having molecular weights within a range from 150 to 500 include 2-(vinyloxyethoxy)ethyl acrylate and a compound represented by general formula (1) shown below:
CH.sub.2═CH—CO—O—X—O—CO—CH═CH.sub.2  (1) (In the formula, X represents a linear or branched alkylene group of 1 to 12 carbon atoms).

7. The active energy ray-curable inkjet ink according to claim 6, wherein the amount of the compound represented by general formula (1) is from 10 to 50% by mass relative to the amount of the 2-(vinyloxyethoxy)ethyl acrylate.

8. The active energy ray-curable inkjet ink according to claim 1, wherein a molecular weight of the polymerization initiator is within a range from 400 to 600.

9. The active energy ray-curable inkjet ink according to claim 1, wherein the polymerization initiator contains oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone) and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.

10. The active energy ray-curable inkjet ink according to claim 9, wherein an amount of the bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide is from 50 to 80% by mass relative to an amount of the oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone).

11. An inkjet recorded article obtained by printing the active energy ray-curable inkjet ink according to claim 1 onto a recording medium and then curing the ink with an active energy ray.

12. A method for producing an inkjet recorded article, the method including: a jetting step of jetting the active energy ray-curable inkjet ink according to claim 1 so as to impact a recording medium, and a curing step of irradiating an active energy ray onto the active energy ray-curable inkjet ink that has impacted the recording medium, thereby curing the active energy ray-curable inkjet ink.

13. The method for producing an inkjet recorded article according to claim 12, wherein the curing step is conducted under an atmosphere having an oxygen concentration of not more than 1% by volume.

14. The active energy ray-curable inkjet ink according to claim 1, wherein the difunctional polymerizable compound includes at least one of compound selected from the group consisting of EO (2)-modified 1,6-hexanediol di(meth)acrylate, polyethylene glycol (300) di(meth)acrylate, polyethylene glycol (200) di(meth)acrylate, and PO (2)-modified neopentyl glycol di(meth)acrylate.

15. The active energy ray-curable inkjet ink according to claim 1, wherein a viscosity at 25° C. of each polyfunctional polymerizable compound is within a range from 3 to 60 mPa.Math.s.

16. The active energy ray-curable inkjet ink according to claim 1, wherein the polyfunctional polymerizable compounds include 2-(vinyloxyethoxy)ethyl acrylate and a compound represented by general formula (1) shown below
CH.sub.2═CH—CO—O—X—O—CO—CH═CH.sub.2  (1) (In the formula, X represents a linear or branched alkylene group of 6 to 10 carbon atoms), and the amount of the compound represented by general formula (1) is from 10 to 50% by mass relative to the amount of the 2-(vinyloxyethoxy)ethyl acrylate.

Description

EXAMPLES

(1) The embodiments of the present invention are described below in further detail using a series of examples and comparative examples, but aspects of the present invention are not limited to these examples. In the following tables, “parts” mean “parts by weight” and “%” means “% by weight”.

Examples 1 to 36, Comparative Examples 1 to 13

(2) (Production of Pigment Dispersion)

(3) Twenty parts of a cyan pigment PB15:4 (LIONOL (a registered trademark) BLUE FG-7400G manufactured by Toyo Color Co., Ltd.) as a pigment, 10 parts of a pigment dispersant (a basic dispersant Solsperse (a registered trademark) 32000 manufactured by The Lubrizol Corporation) and 70 parts of a polymerizable compound (dipropylene glycol diacrylate: Laromer (a registered trademark) DPGDA manufactured by BASF Corporation) were mixed together, and the mixture was then dispersed for one hour in an Eiger mill to complete production of a pigment dispersion. The dispersion was conducted using Zr beads with a diameter of 1 mm at a volumetric fill rate of 75%.

(4) (Production of Inks)

(5) The mixed liquids of polymerizable compounds and polymerization initiators shown in Table 1 were added together gradually and stirred, a surface modifier and polymerization inhibitor were then added in the amounts shown in Table 1, and the resulting mixture was then shaken for 6 hours using a shaker to produce an ink. The thus obtained ink was filtered through a PTFE filter having a pore size of 0.5 microns to remove coarse particles, thus preparing an evaluation ink.

(6) TABLE-US-00001 TABLE 1 molecular Exam- Exam- Exam- Exam- Exam- Exam- weight ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 pigment PB15:4 3.00 3.00 3.00 3.00 3.00 3.00 pigment dispersant SP32000 1.50 1.50 1.50 1.50 1.50 1.50 polymerizable monofunctional LA 240 compound difunctional VEEA-Al 188.2 30.00 30.00 30.00 30.00 65.00 39.00 DPGDA 242 25.00 20.00 10.00 5.00 5.00 25.00 TPGDA 300 5.00 5.00 5.00 tricylodecane dimethanol 304 diacrylate PO-modified 328 15.00 15.00 15.00 10.00 5.00 15.00 (2) neopentyl glycol diacrylate EO-modified 314 5.00 5.00 (2) 1,6-hexanediol diacrylate PEG200DA 308 10.00 10.00 10.00 10.00 5.00 1.00 PEG300DA 408 5.00 compound 1,6-HDDA 226 5.00 5.00 5.00 5.00 5.00 5.00 represented 3-methyl-1,5-pentanediol 226 by general diacrylate formula (1) 1,9-NDDA 268 5.00 5.00 1,10-DDDA 282 5.00 trifunctional trimethylolpropane triacrylate 296 EO-modified 560 (6) trimethylolpropane triacrylate tetrafunctional pentaerythritol tetraacrylate 352 EO-modified 528 (4) pentaerythritol tetraacrylate pentafunctional dipentaerythritol pentaacrylate 525 photopolymerization Omnirad 819 418.5 4.00 4.00 4.00 4.00 4.00 4.00 initiator EsaONE 438 6.00 6.00 6.00 6.00 6.00 6.00 Omnirad 127 340 Omnirad 379 380.5 Omnipol 910 1024 SPEEDCURE7010 1899 Genorad BP-1 980 polymerization inhibitor Ionol CP 0.20 0.20 0.20 0.20 0.20 0.20 surface adjusting agent TegoGlide432 0.30 0.30 0.30 0.30 0.30 0.30 total 100.00 100.00 100.00 100.00 100.00 100.00 evaluation result overall amount of migration (OML) A A A A B C amounts of migration (SML) A A A A C A jetting A A A B B A shrinkage properties A A A A A A flexibility A A A A A A molecular Exam- Exam- Exam- Exam- Exam- Exam- weight ple 7 ple 8 ple 9 ple 10 ple 11 ple 12 pigment PB15:4 3.00 3.00 3.00 3.00 3.00 3.00 pigment dispersant SP32000 1.50 1.50 1.50 1.50 1.50 1.50 polymerizable monofunctional LA 240 compound difunctional VEEA-Al 188.2 30.00 30.00 30.00 30.00 30.00 30.00 DPGDA 242 25.00 25.00 30.00 30.00 30.00 30.00 TPGDA 300 tricylodecane dimethanol 304 diacrylate PO-modified 328 14.00 15.00 15.00 15.00 15.00 15.00 (2) neopentyl glycol diacrylate EO-modified 314 (2) 1,6-hexanediol diacrylate PEG200DA 308 10.00 4.50 4.50 PEG300DA 408 compound 1,6-HDDA 226 5.00 5.00 5.00 5.00 5.00 5.00 represented 3-methyl-1,5-pentanediol 226 by general diacrylate formula (1) 1,9-NDDA 268 1.00 1,10-DDDA 282 trifunctional trimethylolpropane triacrylate 296 10.00 5.00 0.50 EO-modified 560 (6) trimethylolpropane triacrylate tetrafunctional pentaerythritol tetraacrylate 352 5.00 0.50 EO-modified 528 (4) pentaerythritol tetraacrylate pentafunctional dipentaerythritol pentaacrylate 525 photopolymerization Omnirad 819 418.5 4.00 4.00 4.00 4.00 4.00 4.00 initiator EsaONE 438 6.00 6.00 6.00 6.00 6.00 6.00 Omnirad 127 340 Omnirad 379 380.5 Omnipol 910 1024 SPEEDCURE7010 1899 Genorad BP-1 980 polymerization inhibitor Ionol CP 0.20 0.20 0.20 0.20 0.20 0.20 surface adjusting agent TegoGlide432 0.30 0.30 0.30 0.30 0.30 0.30 total 100.00 100.00 100.00 100.00 100.00 100.00 evaluation result overall amount of migration (OML) A C B A B A amounts of migration (SML) A C B A B A jetting A C B A B A shrinkage properties A C B A C A flexibility A C B A C A molecular Exam- Exam- Exam- Exam- Exam- Exam- weight ple 13 ple 14 ple 15 ple 16 ple 17 ple 18 pigment PB15:4 3.00 3.00 3.00 3.00 3.00 3.00 pigment dispersant SP32000 1.50 1.50 1.50 1.50 1.50 1.50 polymerizable monofunctional LA 240 compound difunctional VEEA-Al 188.2 10.00 20.00 40.00 50.00 60.00 DPGDA 242 30.00 30.00 30.00 20.00 15.00 5.00 TPGDA 300 15.00 5.00 tricylodecane dimethanol 304 diacrylate PO-modified 328 15.00 20.00 20.00 10.00 5.00 5.00 (2) neopentyl glycol diacrylate EO-modified 314 (2) 1,6-hexanediol diacrylate PEG200DA 308 15.00 10.00 10.00 10.00 10.00 5.00 PEG300DA 408 compound 1,6-HDDA 226 10.00 10.00 5.00 5.00 5.00 10.00 represented 3-methyl-1,5-pentanediol 226 by general diacrylate formula (1) 1,9-NDDA 268 1,10-DDDA 282 trifunctional trimethylolpropane triacrylate 296 EO-modified 560 (6) trimethylolpropane triacrylate tetrafunctional pentaerythritol tetraacrylate 352 EO-modified 528 (4) pentaerythritol tetraacrylate pentafunctional dipentaerythritol pentaacrylate 525 photopolymerizaton Omnirad 819 416.5 4.00 4.00 4.00 4.00 4.00 4.00 initiator EsaONE 438 6.00 6.00 6.00 6.00 6.00 6.00 Omnirad 127 340 Omnirad 379 380.5 Omnipol 910 1024 SPEEDCURE7010 1899 Genorad BP-1 960 polymerization inhibitor Ionol CP 0.20 0.20 0.20 0.20 0.20 0.20 surface adjusting agent TegoGlide432 0.30 0.30 0.30 0.30 0.30 0.30 total 100.00 100.00 100.00 100.00 100.00 100.00 evaluation result overall amount of migration (OML) C B A A A A amounts of migration (SML) C B B A A B jetting B B A A A A shrinkage properties A A A A A A flexibility A A A A A A molecular Exam- Exam- Exam- Exam- Exam- Exam- weight ple 19 ple 20 ple 21 ple 22 ple 23 ple 24 pigment PB15:4 3.00 3.00 3.00 3.00 3.00 3.00 pigment dispersant SP32000 1.50 1.50 1.50 1.50 1.50 1.50 polymerizable monofunctional LA 240 compound difunctional VEEA-Al 188.2 30.00 30.00 30.00 30.00 30.00 30.00 DPGDA 242 20.00 20.00 25.00 25.00 25.00 25.00 TPGDA 300 tricylodecane dimethanol 304 diacrylate PO-modified 328 15.00 10.00 15.00 15.00 15.00 15.00 (2) neopentyl glycol diacrylate EO-modified 314 (2) 1,6-hexanediol diacrylate PEG200DA 308 10.00 10.00 10.00 10.00 10.00 10.00 PEG300DA 408 5.00 compound 1,6-HDDA 226 10.00 20.00 represented 3-methyl-1,5-pentanediol 226 5.00 by general diacrylate formula (1) 1,9-NDDA 268 5.00 1,10-DDDA 282 5.00 trifunctional trimethylolpropane triacrylate 296 EO-modified 560 (6) trimethylolpropane triacrylate tetrafunctional pentaerythritol tetraacrylate 352 EO-modified 528 (4) pentaerythritol tetraacrylate pentafunctional dipentaerythritol pentaacrylate 525 photopolymerizaton Omnirad 819 416.5 4.00 4.00 4.00 4.00 4.00 4.00 initiator EsaONE 438 6.00 6.00 6.00 6.00 6.00 6.00 Omnirad 127 340 Omnirad 379 380.5 Omnipol 910 1024 SPEEDCURE7010 1899 Genorad BP-1 960 polymerization inhibitor Ionol CP 0.20 0.20 0.20 0.20 0.20 0.20 surface adjusting agent TegoGlide432 0.30 0.30 0.30 0.30 0.30 0.30 total 100.00 105.00 100.00 100.00 100.00 100.00 evaluation result overall amount of migration (OML) A B B A A A amounts of migration (SML) A B B A A A jetting A A C B B C shrinkage properties A A A A A A flexibility A A A A A A molecular Exam- Exam- Exam- Exam- Exam- Exam- weight ple 25 ple 26 ple 27 ple 28 ple 29 ple 30 pigment PB15:4 3.00 3.00 3.00 3.00 3.00 3.00 pigment dispersant SP32000 1.50 1.50 1.50 1.50 1.50 1.50 polymerizable monofunctional LA 240 compound difunctional VEEA-Al 188.2 40.00 40.00 40.00 40.00 30.00 30.00 DPGDA 242 25.00 20.00 10.00 10.00 22.00 25.00 TPGDA 300 10.00 tricylodecane dimethanol 304 diacrylate PO-modified 328 15.00 15.00 15.00 (2) neopentyl glycol diacrylate EO-modified 314 10.00 15.00 (2) 1,6-hexanediol diacrylate PEG200DA 308 15.00 10.00 10.00 PEG300DA 408 10.00 15.00 compound 1,8-HDDA 226 5.00 5.00 5.00 5.00 7.50 5.00 represented 3-methyl-1,5-pentanediol 226 by general diacrylate formula (1) 1,9-NDDA 288 5.00 1,10-DDDA 282 trifunctional trimethylolpropane triacrylate 296 EO-modified 560 0.50 (6) trimethylolpropane triacrylate tetrafunctional pentaerythritol tetraacrylate 352 EO-modified 528 (4) pentaerythritol tetraacrylate pentafunctional dipentaerythritol pentaacrylate 525 photopolymerization Omnirad 819 418.5 4.00 4.00 4.00 4.00 4.00 3.00 initiator EsaONE 438 6.00 6.00 6.00 6.00 6.00 7.00 Omnirad 127 340 Omnirad 379 380.5 Omnipol 910 1024 SPEEDCURE7010 1899 Genorad BP-1 960 polymerization inhibitor Ionol CP 0.20 0.20 0.20 0.20 0.20 0.20 surface adjusting agent TegoGlide432 0.30 0.30 0.30 0.30 0.30 0.30 total 100.00 100.00 100.00 100.00 100.00 100.00 evaluation result overall amount of migration (OML) A A A A A B amounts of migration (SML) A A A A A B jetting A A A A B A shrinkage properties A A A A B A flexibility C A A A B A molecular Exam- Exam- Exam- Exam- Exam- Exam- weight ple 31 ple 32 ple 33 ple 34 ple 35 ple 36 pigment PB15:4 3.00 3.00 3.00 3.00 3.00 3.00 pigment dispersant SP32000 1.50 1.50 1.50 1.50 1.50 1.50 polymerizable monofunctional LA 240 compound difunctional VEEA-Al 188.2 30.00 30.00 30.00 30.00 30.00 30.00 DPGDA 242 25.00 25.00 25.00 25.00 25.00 25.00 TPGDA 300 tricylodecane dimethanol 304 diacrylate PO-modified 328 15.00 15.00 15.00 15.00 15.00 15.00 (2) neopentyl glycol diacrylate EO-modified 314 (2) 1,6-hexanediol diacrylate PEG200DA 308 10.00 10.00 10.00 10.00 10.00 10.00 PEG300DA 408 compound 1,8-HDDA 226 5.00 5.00 5.00 5.00 5.00 5.00 represented 3-methyl-1,5-pentanediol 226 by general diacrylate formula (1) 1,9-NDDA 288 1,10-DDDA 282 trifunctional trimethylolpropane triacrylate 296 EO-modified 560 (6) trimethylolpropane triacrylate tetrafunctional pentaerythritol tetraacrylate 352 EO-modified 528 (4) pentaerythritol tetraacrylate pentafunctional dipentaerythritol pentaacrylate 525 photopolymerization Omnirad 819 418.5 3.40 3.50 4.40 5.00 4.00 initiator EsaONE 438 6.60 6.50 5.60 5.00 6.00 Omnirad 127 340 Omnirad 379 380.5 4.00 Omnipol 910 1024 SPEEDCURE7010 1899 Genorad BP-1 960 6.00 polymerization inhibitor Ionol CP 0.20 0.20 0.20 0.20 0.20 0.20 surface adjusting agent TegoGlide432 0.30 0.30 0.30 0.30 0.30 0.30 total 100.00 100.00 100.00 100.00 100.00 100.00 evaluation result overall amount of migration (OML) A A A A C A amounts of migration (SML) A A A A C A jetting A A A B A C shrinkage properties A A A A A A flexibility A A A A A A Com- Com- Com- Com- Com- Com- par- par- par- par- par- par- molec- ative ative ative ative ative ative ular Exam- Exam- Exam- Exam- Exam- Exam- weight ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 pigment PB15:4 3.00 3.00 3.00 3.00 3.00 3.00 pigment dispersant SP32000 1.50 1.50 1.50 1.50 1.50 1.50 polymeri- monofunctional LA 240 zable difunctional VEEA-Al 186.2 30.00 30.00 30.00 30.00 compound DPGDA 242 40.00 40.00 35.00 25.00 35.00 25.00 TPGDA 300 20.00 tricylodecane dimethanol 304 diacrylate PO-modified 328 15.00 20.00 15.00 15.00 15.00 (2) neopentyl glycol diacrylate EO-modified 314 (2) 1,6-hexanediol diacrylate PEG200DA 308 15.00 15.00 15.00 PEG300DA 408 compound 1,6-HDDA 226 15.00 15.00 5.00 represented 3-methyl-1,5-pentanediol 226 by general diacrylate formula (1) 1,9-NDDA 268 1,10-DDDA 282 trifunctional trimethylolpropane 298 triacrylate EO-modified 560 10.00 (8) trimethylolpropane triacrylate tetrafunctional pentaerythritol tetraacrylate 352 EO-modified 528 (4) pentaerythritol tetraacrylate pentafunctional dipentaerythritol 525 pentaacrylate photopolymerization Omnirad 819 418.5 4.00 4.00 4.00 4.00 4.00 4.00 initiator EsaONE 438 6.00 6.00 6.00 6.00 6.00 6.00 Omnirad 127 340 Omnirad 379 380.5 Omnipol 910 1024 SPEEDCURE7010 1899 Genorad BP-1 960 polymerization inhibitor Ionol CP 0.20 0.20 0.20 0.20 0.20 0.20 surface adjusting agent TegoGlide432 0.30 0.30 0.30 0.30 0.30 0.30 total 100.00 100.00 100.00 100.00 100.00 100.00 evaluation overall amount migration (OML) E E E D E D result amounts of migration (SML) E C D D E C jetting B B B A B D shrinkage properties A A A A A B flexibility C B A A A B Com- Com- Com- Com- Com- Com- Com- par- par- par- par- par- par- par- molec- ative ative ative ative ative ative ative ular Exam- Exam- Exam- Exam- Exam- Exam- Exam- weight ple 7 ple 8 ple 9 ple 10 ple 11 ple 12 ple 13 pigment PB15:4 3.00 3.00 3.00 3.00 3.00 3.00 3.00 pigment dispersant SP32000 1.50 1.50 1.50 1.50 1.50 1.50 1.50 polymeri- monofunctional LA 240 5.00 5.00 5.00 zable difunctional VEEA-Al 186.2 30.00 30.00 30.00 30.00 30.00 72.50 compound DPGDA 242 30.00 25.00 25.00 20.00 20.00 TPGDA 300 5.00 tricylodecane dimethanol 304 30.00 diacrylate PO-modified 328 19.50 15.00 15.00 15.00 15.00 5.00 (2) neopentyl glycol diacrylate EO-modified 314 (2) 1,6-hexanediol diacrylate PEG200DA 308 10.00 10.00 PEG300DA 408 compound 1,6-HDDA 226 5.00 5.00 10.00 5.00 represented 3-methyl-1,5-pentanediol 226 by general diacrylate formula (1) 1,9-NDDA 268 1,16-DDDA 282 trifunctional trimethylolpropane 298 triacrylate EO-modified 560 0.50 30.00 (8) trimethylolpropane triacrylate tetrafunctional pentaerythritol 352 tetraacrylate EO-modified 528 10.00 20.00 (4) pentaerythritol tetraacrylate pentafunctional dipentaerythritol 525 20.00 pentaacrylate photopolymerization Omnirad 819 418.5 4.00 4.00 4.00 4.00 4.00 4.00 initiator EsaONE 438 6.00 6.00 6.00 6.00 6.00 Omnirad 127 340 2.50 Omnirad 379 380.5 Omnipol 910 1024 5.00 SPEEDCURE7010 1899 1.00 Genorad BP-1 960 polymerization inhibitor Ionol CP 0.20 0.20 0.20 0.20 0.20 0.20 0.20 surface adjusting agent TegoGlide432 0.30 0.30 0.30 0.30 0.30 0.30 0.30 total 100.00 100.00 100.00 100.00 100.00 100.00 100.00 evaluation overall amount migration (OML) D D E E E D D result amounts of migration (SML) D D E E E D E jetting B E A A A D E shrinkage properties A C A A A E E flexibility A C A A A E D

(7) Details of each material in Table 1 are shown in Table 2.

(8) TABLE-US-00002 TABLE 2 pigment PB15:4 Pigment Blue 15:4 pigment dispersant SP32000 Basic dispersant “Solsperse 32000” manufactured by Lubrizole polymerizable monofunctional LA lauryl acrylate compound difunctional VEEA-Al acrylic acid 2-(2-vinyloxyethoxy) ethyl DPGDA dipropylene glycol diacylate TPGDA tripropylene glycol diacrylate tricylodecane dimethanol diacrylate PO-modified (2) neopentyl glycol diacrylate EO-modified (2) 1,8-hexanediol diacrylate PEG200DA polyethylene glycol (200) diacrylate PEG300DA polyethylene glycol (300) diacrylate compound 1,6-HDDA 1,8-hexanediol diacrylate represented 3-methyl-1,5-pentanediol diacrylate by general 1,9-NDDA 1,9-nonanediol diacrylate formula (1) 1,10-DDDA 1,10-decanediol diacrylate trifunctional trimethylolpropane triacrylate EO-modified (8) trimethylolpropane triacrylate tetrafunctional pentaerytritol tetraacrylate EO-modified (4) penaerythritol tetraacrylate pentafunctional dipentaerythritol pentaacrylate photopolymerization Omnirad 819 bis (2,4,6-trimethylbenzoyl)-phenylphosphine oxide initiator EsaONE oligo (2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl) propanone) Omnirad 127 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one Omnirad 379 2-(dimethylamino)-2-[(4-ethylphenyl)methyl]-1-[4-(4-morpholinly)phenyl]- 1-butanone Omnipol 910 polyethylene glycol (200) di(β-4(4-(2-dimethylammino-2-benzyl) butaonylphenyl] piperazine) SPEEDCURE 1,3-di({α-[1-chloro-9-oxo-9H-thioxenthen-4-yl]oxy}acetylpoly[oxy(1- 7010 methylethylene)])oxy)-2,2-bis([α-(1-chloro-9-oxo- 9H-thioxanthen-4-yl]oxy}acetylpoly[oxy(1-methylethylene)])oxymethyl) propane Genorad BP-1 (carboxymethoxymethoxy-benzophenone)-(polytetramethylene glycol 250) diester polymerization Ionol CP 2,6-di-tert-butyl-4-methylphenol inhibitor surface adjusting TegoGlide432 Polyether-modified siloxane copolymer “TegoGlide 432” agent manufactured by Evonik Degussa GmbH pigment PB15:4 “LIONOL BLUE FG-7400G” manufactured by Toyocolor Co., Ltd. pigment dispersant SP32000 Basic dispersant “Solsperse 32000” manufactured by Lubrizole polymerizable monofunctional LA “Sartomer SR355” manufactured by Arkema Inc. compound difunctional VEEA-Al “VEEA-Al” manufactured by Nippon shokubai co., Ltd. DPGDA “Laromer DPGDA” manufactured by BASF TPGDA “Sartomer SR306” manufactured by Arkema Inc. tricylodecane dimethanol “Sartomer SR833” manufactured by Arkema Inc. diacrylate PO-modified (2) neopentyl “Sartomer SR9003” manufactured by Arkema Inc. glycol diacrylate EO-modified (2) “MIRAMER M202” manufactured by MIWON 1,8-hexanediol diacrylate Speciality Chemical co., Ltd. PEG200DA “Sartomer SR259” manufactured by Arkema Inc. PEG300DA “MIRAMER M282” manufactured by MIWON Speciality Chemical co., Ltd. compound 1,6-HDDA “Sartomer SR238” manufactured by Arkema Inc. represented 3-methyl-1,5-pentanediol “LIGHT ACRYLATE MPD-A” manufactured by by general diacrylate Kyoeisha chemical co., Ltd. formula (1) 1,9-NDDA “Viscoat #260” manufactured by Osaka organic chemical industry Ltd. 1,10-DDDA “Sartomer CD595” manufactured by Arkema Inc. trifunctional trimethylolpropane “Sartomer SR351” manufactured by Arkema Inc. triacrylate EO-modified (8) “Sartomer SR449” manufactured by Arkema Inc. trimethylolpropane triacrylate tetrafunctional pentaerytritol “Sartomer SR295” manufactured by Arkema Inc. tetraacrylate EO-modified (4) “Sartomer SR494” manufactured by Arkema Inc. penaerythritol tetraacrylate pentafunctional dipentaerythritol “Sartomer SR399” manufactured by Arkema Inc. pentaacrylate photopolymerization Omnirad 819 “Omnirad 819” manufactured by IGM Resins B.V. initiator EsaONE “Esacure One” manufactured by Lamberti Omnirad 127 “Omnirad 127” manufactured by IGM Resins B.V. Omnirad 379 “Omnirad 379” manufactured by IGM Resins B.V. Omnipol 910 “Ominipol 910” manufactured by IGM Resins B.V. SPEEDCURE 7010 “SPEEDCURE 7010” manufactured by Lambson Ltd. Genorad BP-1 “Genorad BP-1” manufactured by Rahn AG polymerization Ionol CP “Ionol CP” manufactured by Japan Chemtech inhibitor surface adjusting TegoGlide432 Polyether-modified siloxane copolymer “TegoGlide agent 432” manufactured by Evonik Degussa GmbH
[Evaluation Items]
(Migration Evaluation Method)

(9) A migration evaluation image was printed with the prepared ink using a OnePass JET device manufactured by Tritek Co., Ltd. The prepared ink was injected into an inkjet head manufactured by Kyocera Corporation using a syringe, a 100% solid printed image (with a film thickness equivalent to 6μ) was output at a printing speed of 50 m/minute and a head temperature of 40° C., and the image was then cured using a UV lamp (240 W) manufactured by Nordson Advanced Technology Corporation. A semigloss paper (60 #) manufactured by Avery Products Corporation was used as the printing substrate.

(10) The obtained printed article was bonded uniformly to a PET substrate (Lumirror (a registered trademark) manufactured by Toray Industries, Inc.) with a thickness of 25 μm using a hand roller to prepare an evaluation sample.

(11) Using this evaluation sample, an evaluation of the overall amount of migration (OML) through the PET substrate, and evaluations of the specific amounts of migration (SML) of the polymerizable compounds, the polymerization initiators and the polymerization inhibitor were conducted in accordance with the conditions prescribed in European Regulation (EU) No. 10/2011, CEN Standard EN 1186-1 and CEN Standard EN 13130-1.

(12) The overall amount of migration (OML) was evaluated using the following criteria.

(13) A evaluation: less than 1 ppm

(14) B evaluation: at least 1 ppm but less than 5 ppm

(15) C evaluation: at least 5 ppm but less than 10 ppm

(16) D evaluation: at least 10 ppm but less than 20 ppm

(17) E evaluation: 20 ppm or greater

(18) Evaluations of C or better were judged to indicate a practically usable level.

(19) The evaluation results are shown in Table 1.

(20) The specific amounts of migration (SML) were evaluated by measuring the amounts of migration of the polymerizable compounds and the polymerization initiators, and then evaluating the measured amounts against the following criteria.

(21) A evaluation: the measured values for the polymerizable compounds and the polymerization initiators are below the lower limit for detection (5 ppb)

(22) B evaluation: the measured values for the polymerizable compounds are at least as high as the lower limit for detection (5 ppb) but less than 10 ppb, and the measured values for the polymerization initiators are below the lower limit for detection (5 ppb)

(23) C evaluation: the measured values for the polymerizable compounds are at least as high as the lower limit for detection (5 ppb) but less than 10 ppb, and the measured values for the polymerization initiators are all below the upper limit prescribed in the Swiss Ordinance.

(24) D evaluation: the measured value for only one substance among the polymerizable compounds and the polymerization initiators exceeds the upper limit prescribed in the Swiss Ordinance.

(25) E evaluation: the measured values for two or more substances among the polymerizable compounds and the polymerization initiators exceeds the upper limit prescribed in the Swiss Ordinance.

(26) Evaluations of C or better were judged to indicate a practically usable level.

(27) The evaluation results are shown in Table 1.

(28) (Jetting Evaluation)

(29) Each of the prepared inks was subjected to a jetting evaluation using a Dot View device manufactured by Tritek Co., Ltd. The prepared ink was injected into an inkjet head (20 kHz) manufactured by Kyocera Corporation using a syringe, the ink was then jetted from the head at a head temperature of 40° C. and the jetting speed and the form of the liquid droplets during ink flight were analyzed. An evaluation was conducted using the following criteria.

(30) A evaluation: jetting speed exceeding 8 mi/minute, no divided droplet or satellite droplet

(31) B evaluation: jetting speed of 7 to 8 m/minute, no divided droplet or satellite droplet

(32) C evaluation: jetting speed of 7 to 8 m/minute, no divided droplet but some satellite droplet

(33) D evaluation: jetting speed of 6 to 7 m/minute, no divided droplet but some satellite droplet

(34) E evaluation: jetting speed of 6 to 7 m/minute, both divided droplet and satellite droplet

(35) Evaluations of C or better were judged to indicate a practically usable level.

(36) The evaluation results are shown in Table 1.

(37) (Shrinkage Properties)

(38) A sample prepared by printing the prepared ink at a coverage rate of 100% onto a PET substrate (Lumirror (a registered trademark) manufactured by Toray Industries, Inc.) with a thickness of 50 μm was cut into a short strip of 1 cm×5 cm, one short side of the sample was secured to a metal substrate with tape, and the height to which the non-secured short side of the sample lifted off the metal plate was deemed the initial shrinkage. Subsequently, this sample was left to stand for one day in 45° C. environment inside an oven, the sample was removed from the oven, and the height to which the non-secured portion of the sample had lifted off the metal plate was deemed the shrinkage upon standing. The shrinkage was evaluated against the following criteria.

(39) A evaluation: the initial shrinkage is at least 0 mm but less than 5 mm, and the shrinkage upon standing is at least 0 mm but less than 7 mm

(40) B evaluation: the initial shrinkage is at least 0 mm but less than 5 mm, and the shrinkage upon standing is at least 7 mm but less than 10 mm

(41) C evaluation: the initial shrinkage is at least 0 mm but less than 5 mm, and the shrinkage upon standing is at least 10 mm

(42) D evaluation: the initial shrinkage is at least 5 mm but less than 10 mm, and the shrinkage upon standing is at least 10 mm

(43) E evaluation: the initial shrinkage and the shrinkage upon standing are both 10 mm or greater

(44) Evaluations of C or better were judged to indicate a practically usable level.

(45) The evaluation results are shown in Table 1.

(46) (Flexibility)

(47) A flexibility evaluation was conducted by printing the prepared ink onto a PET film (PET50 K2411 manufactured by Lintec Corporation) in an amount sufficient to form a coating film thickness of 8 μm, curing the printed film, folding the resulting film into a mountain fold with the coating film facing upward, and recording the number of times this folding operation could be performed before cracks occurred. Evaluation was performed against the following criteria.

(48) A evaluation: number of folding repetitions before cracks occurred is at least 4, or no cracks occur

(49) B evaluation: cracks occur on the third folding repetition

(50) C evaluation: cracks occur on the second folding repetition

(51) D evaluation: cracks occur on the first folding repetition

(52) E evaluation: coating film completely destroyed on first folding repetition

(53) Evaluations of C or better were judged to indicate a practically usable level.

(54) The evaluation results are shown in Table 1.

(55) Based on the above results, it was evident that the ink of an embodiment of the present invention exhibited excellent jetting properties at high speed, is resistant to migration and has a cured coating film (with good flexibility and low shrinkage) that is suitable for food packaging.