JP2009096910A - Active energy ray-curing ink for inkjet printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active energy ray-curing ink for inkjet printing, the ink having a low viscosity at room temperature and high sensitivity and providing a cured film excellent in flexibility. <P>SOLUTION: The active energy ray-curing ink for inkjet printing comprises: (A) a colorant; (B) as polymerizable monomers, (b1) a compound having at least three polymerizable unsaturated bonds in one molecule, (b2) an alkyleneglycol acrylate compound and (b3) a compound having one or two polymerizable unsaturated bonds in one molecule, except for the compound (b2); and (C) a photopolymerization initiator comprising a compound expressed by formula (2). In the formula, each of R<SP>2</SP>and R<SP>3</SP>independently represents a straight-chain or branched alkyl group having a carbon number of 1 to 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an active energy ray-curable ink for inkjet printing.

In recent years, an ink jet method using active energy rays has been actively studied (for example, Patent Document 1). In this method, liquid ink is applied to paper, plastic, etc., and then cured and crosslinked by ultraviolet (UV) light. Unlike conventional ink-jet systems that cure and crosslink with heat, ink-jet systems that cure and crosslink with UV have advantages such as quick-drying, no solvent, and printing on media that does not absorb ink. ing.
There are a wide variety of coating media in the ink jet system, and as the demand for stretchable substrates and the like increases, the followability of the ink cured film to the substrate and the flexibility of the ink cured film also for ink for inkjet printing. Flexibility such as sex has been required. In order to impart flexibility to the ink cured film, it is usually necessary to use a polymer having a high viscosity, a crosslinking agent, or the like. If these are used, the resulting ink will also have a high viscosity. However, if the ink viscosity is high in the ink jet printing method, the continuous ejection stability of the ink may be impaired, or the nozzle head may be clogged. In general, in the ink jet system, it is desired that the viscosity of the ink is 30 mPa · s or less at room temperature from the viewpoint of continuous discharge stability and prevention of clogging of the nozzle head. In addition, in order to impart flexibility to the ink cured film, there is a method such as not using a compound having three or more polymerizable unsaturated bonds as a curing agent, but one or two polymerizable unsaturated bonds are used. There is a problem that sufficient strength cannot be obtained with only the compound having it, and the cured ink film is brittle and easily torn.
Accordingly, there is a strong demand for an active energy ray-curable ink for ink jet printing, which ensures sufficient flexibility of the ink cured film, has sufficient strength of the ink cured film, and has a viscosity of 30 mPa · s or less at room temperature. It has been.
Special table 2004-526820

  An object of the present invention is to provide a high-sensitivity active energy ray-curable ink for inkjet printing, which has a low viscosity at room temperature and has a cured film with excellent flexibility.

The present invention, first,
(A) Colorant, (B) As a polymerizable monomer, (b1) a compound having three or more polymerizable unsaturated bonds in one molecule, (b2) a compound represented by the following formula (1), and (b3) Contains a photopolymerization initiator comprising a compound other than the above (b2) having one or two polymerizable unsaturated bonds in one molecule, and (C) a compound represented by the following formula (2). And an active energy ray-curable ink for ink jet printing.

(In the formula, R ¹ represents a hydrogen atom or a methyl group, and n is an integer of 0 to 6.)

(In the formula, each of R ² and R ³ independently represents a linear or branched alkyl group having 1 to 4 carbon atoms.)
The term “radiation” as used in the present invention means one containing ultraviolet rays, far ultraviolet rays, X-rays, electron beams, molecular beams, γ rays, synchrotron radiation, proton beam rays, and the like.

  The active energy ray-curable ink for inkjet printing according to the present invention has low viscosity and high sensitivity, and the cured film has excellent flexibility, and can stably provide high-definition and high-quality printed matter with high productivity. Can do.

Hereinafter, the present invention will be described in detail.
(A) Colorant The colorant in the present invention is not particularly limited in color tone, and is appropriately selected according to the use, and may be any of a pigment, a dye, or a natural colorant.
As the colorant in the present invention, a colorant having high color developability and a high heat resistance, particularly a colorant having a high heat decomposability is preferable, and usually a pigment, particularly preferably an organic pigment or carbon black is used.
Examples of the organic pigment include compounds classified as Pigment in the Color Index (CI; issued by The Society of Dyers and Colorists), specifically, the following Color Index (C.I. ) Can be listed.

C. I. Pigment yellow 1, C.I. I. Pigment yellow 3, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 16, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 20, C.I. I. Pigment yellow 24, C.I. I. Pigment yellow 31, C.I. I. Pigment yellow 55, C.I. I. Pigment yellow 60, C.I. I. Pigment yellow 61, C.I. I. Pigment yellow 65, C.I. I. Pigment yellow 71, C.I. I. Pigment yellow 73, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 81, C.I. I. Pigment yellow 83, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 95, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 98, C.I. I. Pigment yellow 100, C.I. I. Pigment yellow 101, C.I. I. Pigment yellow 104, C.I. I. Pigment yellow 106, C.I. I. Pigment yellow 108, C.I. I. Pigment yellow 109, C.I. I. Pigment yellow 110, C.I. I. Pigment yellow 113, C.I. I. Pigment yellow 114, C.I. I. Pigment yellow 116, C.I. I. Pigment yellow 117, C.I. I. Pigment yellow 119, C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 126, C.I. I. Pigment yellow 127, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 129, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 139, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 152, C.I. I. Pigment yellow 153, C.I. I. Pigment yellow 154, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 156, C.I. I. Pigment yellow 166, C.I. I. Pigment yellow 168, C.I. I. Pigment yellow 175, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185;

C. I. Pigment orange 1, C.I. I. Pigment orange 5, C.I. I. Pigment orange 13, C.I. I. Pigment orange 14, C.I. I. Pigment orange 16, C.I. I. Pigment orange 17, C.I. I. Pigment orange 24, C.I. I. Pigment orange 34, C.I. I. Pigment orange 36, C.I. I. Pigment orange 38, C.I. I. Pigment orange 40, C.I. I. Pigment orange 43, C.I. I. Pigment orange 46, C.I. I. Pigment orange 49, C.I. I. Pigment orange 51, C.I. I. Pigment orange 61, C.I. I. Pigment orange 63, C.I. I. Pigment orange 64, C.I. I. Pigment orange 71, C.I. I. Pigment orange 73;
C. I. Pigment violet 1, C.I. I. Pigment violet 19, C.I. I. Pigment violet 23, C.I. I. Pigment violet 29, C.I. I. Pigment violet 32, C.I. I. Pigment violet 36, C.I. I. Pigment violet 38;

C. I. Pigment red 1, C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 4, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 8, C.I. I. Pigment red 9, C.I. I. Pigment red 10, C.I. I. Pigment red 11, C.I. I. Pigment red 12, C.I. I. Pigment red 14, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 17, C.I. I. Pigment red 18, C.I. I. Pigment red 19, C.I. I. Pigment red 21, C.I. I. Pigment red 22, C.I. I. Pigment red 23, C.I. I. Pigment red 30, C.I. I. Pigment red 31, C.I. I. Pigment red 32, C.I. I. Pigment red 37, C.I. I. Pigment red 38, C.I. I. Pigment red 40, C.I. I. Pigment red 41, C.I. I. Pigment red 42, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 48: 2, C.I. I. Pigment red 48: 3, C.I. I. Pigment red 48: 4, C.I. I. Pigment red 49: 1, C.I. I. Pigment red 49: 2, C.I. I. Pigment red 50: 1, C.I. I. Pigment red 52: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 57: 2, C.I. I. Pigment red 58: 2, C.I. I. Pigment red 58: 4, C.I. I. Pigment red 60: 1, C.I. I. Pigment red 63: 1, C.I. I. Pigment red 63: 2, C.I. I. Pigment red 64: 1, C.I. I. Pigment red 81: 1, C.I. I. Pigment red 83, C.I. I. Pigment red 88, C.I. I. Pigment red 90: 1, C.I. I. Pigment red 97, C.I. I. Pigment red 101,

C. I. Pigment red 102, C.I. I. Pigment red 104, C.I. I. Pigment red 105, C.I. I. Pigment red 106, C.I. I. Pigment red 108, C.I. I. Pigment red 112, C.I. I. Pigment red 113, C.I. I. Pigment red 114, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 144, C.I. I. Pigment red 146, C.I. I. Pigment red 149, C.I. I. Pigment red 150, C.I. I. Pigment red 151, C.I. I. Pigment red 166, C.I. I. Pigment red 168, C.I. I. Pigment red 170, C.I. I. Pigment red 171, C.I. I. Pigment red 172, C.I. I. Pigment red 174, C.I. I. Pigment red 175, C.I. I. Pigment red 176, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. Pigment red 179, C.I. I. Pigment red 180, C.I. I. Pigment red 185, C.I. I. Pigment red 187, C.I. I. Pigment red 188, C.I. I. Pigment red 190, C.I. I. Pigment red 193, C.I. I. Pigment red 194, C.I. I. Pigment red 202, C.I. I. Pigment red 206, C.I. I. Pigment red 207, C.I. I. Pigment red 208, C.I. I. Pigment red 209, C.I. I. Pigment red 215, C.I. I. Pigment red 216, C.I. I. Pigment red 220, C.I. I. Pigment red 224, C.I. I. Pigment red 226, C.I. I. Pigment red 242, C.I. I. Pigment red 243, C.I. I. Pigment red 245, C.I. I. Pigment red 254, C.I. I. Pigment red 255, C.I. I. Pigment red 264, C.I. I. Pigment red 265;

C. I. Pigment blue 15, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 15: 6, C.I. I. Pigment blue 60;
C. I. Pigment green 7, C.I. I. Pigment green 36, C.I. I. Pigment green 58;
C. I. Pigment brown 23, C.I. I. Pigment brown 25;
C. I. Pigment black 1, C.I. I. Pigment Black 7.
These organic pigments can be used after being purified by, for example, a sulfuric acid recrystallization method, a solvent washing method, or a combination thereof.

Examples of the inorganic pigment include titanium oxide, barium sulfate, calcium carbonate, zinc white, lead sulfate, yellow lead, zinc yellow, red bean curd (red iron oxide (III)), cadmium red, ultramarine blue, bitumen, and chromium oxide. Examples include green, cobalt green, amber, titanium black, synthetic iron black, and carbon black.
In the present invention, the organic pigment and the inorganic pigment can be used alone or in combination of two or more, and the organic pigment and the inorganic pigment can be used together. Preferably, one or more organic pigments are used, and when forming the black matrix, two or more organic pigments and / or carbon black are preferably used.

  In the present invention, each of the pigments can be used by modifying the particle surface with a polymer, if desired. Examples of the polymer that modifies the pigment particle surface include the polymers described in JP-A-8-259876, and various commercially available pigment-dispersing polymers or oligomers.

Further, the colorant in the present invention can be used together with a dispersant as desired.
Examples of the dispersant include cationic, anionic, nonionic, amphoteric, silicone, and fluorine surfactants.
Examples of the surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether; polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonyl Polyoxyethylene alkyl phenyl ethers such as phenyl ether; polyethylene glycol diesters such as polyethylene glycol dilaurate and polyethylene glycol distearate; sorbitan fatty acid esters; fatty acid-modified polyesters; tertiary amine-modified polyurethanes; polyethyleneimines In addition, KP (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow (manufactured by Kyoeisha Chemical Co., Ltd.), F-Top (manufactured by Tochem Products), Fuck (Dainippon Ink Chemical Co., Ltd.), Florard (Sumitomo 3M Co., Ltd.), Asahi Guard, Surflon (manufactured by Asahi Glass Co., Ltd.), Disperbyk (Bicchemy Japan Co., Ltd.), Sol Sparse ( Seneca Co., Ltd.).
These surfactants can be used alone or in admixture of two or more.
The usage-amount of surfactant is 50 parts weight or less normally with respect to 100 weight part of coloring agents, Preferably it is 0-30 weight part.

  In the present invention, the content of the colorant in the ink is usually 0.5 to 10% by weight, preferably 1 to 6% by weight. If the content of the colorant is too small, it may be difficult to obtain a sufficient color density. On the other hand, if the content is too large, the stability of continuous ejection from the nozzle head tends to decrease.

(B) Polymerizable monomer (B) The polymerizable monomer in the present invention is (b1) a compound having 3 or more polymerizable unsaturated bonds in one molecule (hereinafter referred to as “polymerizable monomer (b1)”). (B2) The compound represented by the formula (1) (hereinafter referred to as “polymerizable monomer (b2)”) and (b3) the above (b2) having one or two polymerizable unsaturated bonds in one molecule It is a monomer that can be polymerized by irradiation with active energy rays, comprising a compound other than (hereinafter referred to as “polymerizable monomer (b3)”).

Specific examples of the polymerizable monomer (b1) in the present invention include trimethylolpropane tri (meth) acrylate, glycerin tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, and dipentaerythritol. Of tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, propylene oxide modified tri (meth) acrylate of trimethylolpropane, trimethylolpropane Ethylene oxide modified tri (meth) acrylate, ethylene oxide modified tri (meth) acrylate of isocyanuric acid, ε-caprolactone modified (tri (Meth) acryloxy ethyl) isocyanurate, may be mentioned a compound represented by such as the following formula (3).
Of these polymerizable monomers (b1), glycerin tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) ) Acrylate, ε-caprolactone-modified (tris (meth) acryloxyethyl) isocyanurate, a compound represented by the following formula (3), etc. are preferable, and glycerin triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipenta Particularly preferred are erythritol pentaacrylate, dipentaerythritol hexaacrylate, ε-caprolactone-modified (trisacryloxyethyl) isocyanurate, and the like.

  Among these polymerizable monomers (b1), ethylene oxide-modified triacrylates of trimethylolpropane are Aronix M-313 and M-320, and ethylene oxide-modified triacrylates of trimethylolpropane are Aronix M-350, M-360, and isocyanuric. The ethylene oxide-modified triacrylate of acid is Aronix M-315, ε-caprolactone-modified (trisacryloxyethyl) isocyanurate is Aronix M-325 (above, manufactured by Toagosei Co., Ltd.), and the compound represented by the following formula (3) is It is commercially available under the product name UA-31 (manufactured by Toho Chemical Industry Co., Ltd.).

The polymerizable monomer (b2) is a compound represented by the formula (1).
In Formula (1), as n, 0-4 are preferable and 1-3 are especially preferable.
Specific examples of the polymerizable monomer (b2) include vinyl (meth) acrylate, ethylene glycol monovinyl ether (meth) acrylate, diethylene glycol monovinyl ether (meth) acrylate, triethylene glycol monovinyl ether (meth) acrylate, and tetraethylene glycol monovinyl ether. A (meth) acrylate etc. can be mentioned.
These polymerizable monomers (b2) can be used alone or in admixture of two or more.

In the present invention, specific examples of the polymerizable monomer (b3) include
Ethylene glycol di (meth) acrylate, ethylene glycol mono (meth) acrylate, ethylene glycol monomethyl ether (meth) acrylate, ethylene glycol monoethyl ether (meth) acrylate, diethylene glycol di (meth) acrylate, diethylene glycol mono (meth) acrylate, Diethylene glycol monomethyl ether (meth) acrylate, diethylene glycol monoethyl ether (meth) acrylate, triethylene glycol di (meth) acrylate, triethylene glycol mono (meth) acrylate, triethylene glycol monomethyl ether (meth) acrylate, triethylene glycol monoethyl Ether (meth) acrylate, tetraethylene glycol di (meth) a Relate, tetraethylene glycol mono (meth) acrylate, tetraethylene glycol monomethyl ether (meth) acrylate, tetraethylene glycol monoethyl ether (meth) acrylate, polyethylene glycol di (meth) acrylate (the number of ethylene glycol units is 5 to 12), Polyethylene glycol mono (meth) acrylate (5 to 12 ethylene glycol units), polyethylene glycol monomethyl ether (meth) acrylate (5 to 12 ethylene glycol units), polyethylene glycol monoethyl ether (meth) acrylate (ethylene glycol units) (Poly) ethylene glycol (meth) acrylates such as 5-12 in number;

Propylene glycol di (meth) acrylate, propylene glycol mono (meth) acrylate, propylene glycol monomethyl ether (meth) acrylate, propylene glycol monoethyl ether (meth) acrylate, dipropylene glycol di (meth) acrylate, dipropylene glycol mono ( (Meth) acrylate, dipropylene glycol monomethyl ether (meth) acrylate, dipropylene glycol monoethyl ether (meth) acrylate, tripropylene glycol di (meth) acrylate, tripropylene glycol mono (meth) acrylate, tripropylene glycol monomethyl ether (meta ) Acrylate, Tripropylene glycol monoethyl ether (meth) acrylate, Tetrapropy Glycol di (meth) acrylate, tetrapropylene glycol mono (meth) acrylate, tetrapropylene glycol monomethyl ether (meth) acrylate, tetrapropylene glycol monoethyl ether (meth) acrylate, polypropylene glycol di (meth) acrylate (number of propylene glycol units) 5-9), polypropylene glycol mono (meth) acrylate (5-9 propylene glycol units), polypropylene glycol monomethyl ether (meth) acrylate (5-9 propylene glycol units), polypropylene glycol monoethyl ether (meta) ) (Poly) propylene glycol (meth) acrylates such as acrylate (5 to 9 propylene glycol units);

1,3-propanediol di (meth) acrylate, 1,3-propanediol mono (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,4-butanediol mono (meth) acrylate, 1, 5-pentanediol di (meth) acrylate, 1,5-pentanediol mono (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,6-hexanediol mono (meth) acrylate, glycerol di (meth) ) Acrylate, glycerol mono (meth) acrylate, dimethylol tricyclodecane di (meth) acrylate, monomethylol tricyclodecane mono (meth) acrylate, trimethylolpropane mono (meth) acrylate, trimethylolpropane di (meth) acrylate, Bae Esters of other polyhydric alcohol and (meth) acrylic acid such as data pentaerythritol di (meth) acrylate;

Cycloaliphatic esters of (meth) acrylic acid such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, norbornyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate;

Methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, (Meth) acrylic acid esters other than the above, such as tetrahydrofurfuryl (meth) acrylate;

(Poly) ethylene glycol vinyl ethers such as ethylene glycol divinyl ether, ethylene glycol monovinyl ether, diethylene glycol divinyl ether, diethylene glycol monovinyl ether, triethylene glycol divinyl ether, triethylene glycol monovinyl ether, tetraethylene glycol divinyl ether, tetraethylene glycol monovinyl ether ;
(Poly) such as propylene glycol divinyl ether, propylene glycol monovinyl ether, dipropylene glycol divinyl ether, dipropylene glycol monovinyl ether, tripropylene glycol divinyl ether, tripropylene glycol monovinyl ether, tetrapropylene glycol divinyl ether, tetrapropylene glycol monovinyl ether Examples thereof include propylene glycol vinyl ethers, N-vinyl pyrrolidone, N-vinyl-ε-caprolactam and the like.

Among these polymerizable monomers (b3), (poly) ethylene glycol (meth) acrylates, (meth) acrylic acid alicyclic esters, (poly) ethylene glycol vinyl ethers, N-vinylpyrrolidone, N-vinyl -Ε-caprolactam and the like are preferable. Further, among (poly) ethylene glycol (meth) acrylates, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate (the number of ethylene glycol units is 5 to 9) and the like are preferable, and (meth) acrylic Among the alicyclic esters of acid, isobornyl (meth) acrylate and the like are preferable, and among the (poly) ethylene glycol vinyl ethers, triethylene glycol divinyl ether and the like are preferable.
A polymerizable monomer (b3) can be used individually or in mixture of 2 or more types.

  In the present invention, specific examples of the polymerizable monomer (B) include (b-1) trimethylolpropane tri (meth) acrylate, glycerin tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth). ) Acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, propylene oxide modified tri (meth) of trimethylolpropane Acrylate, trimethylolpropane ethylene oxide modified tri (meth) acrylate, isocyanuric acid ethylene oxide modified tri (meth) acrylate, ε-caprolactate At least one selected from the group of modified (tris (meth) acryloxyethyl) isocyanurate and the compound represented by the formula (3); vinyl (meth) acrylate, ethylene glycol monovinyl ether (meth) acrylate, diethylene glycol mono At least one selected from the group consisting of vinyl ether (meth) acrylate, triethylene glycol monovinyl ether (meth) acrylate and tetraethylene glycol monovinyl ether (meth) acrylate; and (poly) ethylene glycol (meth) acrylates, (meth) acrylic A mixture comprising at least one selected from the group consisting of alicyclic esters of acids, (poly) ethylene glycol vinyl ethers, N-vinylpyrrolidone and N-vinyl-ε-caprolactam It can gel,

  Specific examples of preferred (B) polymerizable monomers include (b-2) glycerin tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, and dipentaerythritol penta (meth) acrylate. At least one selected from the group consisting of dipentaerythritol hexa (meth) acrylate, ε-caprolactone-modified (tris (meth) acryloxyethyl) isocyanurate and the compound represented by the formula (3); vinyl (meth) Acrylate, ethylene glycol monovinyl ether (meth) acrylate, diethylene glycol monovinyl ether (meth) acrylate, triethylene glycol monovinyl ether (meth) acrylate and tetraethylene glycol monobi At least one selected from the group of ruether (meth) acrylates; tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate (5 to 9 ethylene glycol units), isobornyl (meth) acrylate, triethylene And a mixture of at least one selected from the group of glycol divinyl ether, N-vinyl pyrrolidone and N-vinyl-ε-caprolactam,

  Specific examples of (B) polymerizable monomers that are particularly preferred include (b-3) glycerol triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, and ε-caprolactone modification. At least one selected from the group of (trisacryloxyethyl) isocyanurate; vinyl (meth) acrylate, ethylene glycol monovinyl ether (meth) acrylate, diethylene glycol monovinyl ether (meth) acrylate, triethylene glycol monovinyl ether (meth) acrylate And at least one selected from the group of tetraethylene glycol monovinyl ether (meth) acrylate; Mention is made of a mixture comprising at least one selected from the group of tylene glycol di (meth) acrylate, isobornyl (meth) acrylate and N-vinylpyrrolidone, optionally further containing triethylene glycol divinyl ether or N-vinyl-ε-caprolactam be able to.

  In the present invention, the content of the polymerizable monomer (b1) in the ink is usually 0.1 to 20% by weight, preferably 0.5 to 18% by weight, and particularly preferably 1.0 to 15% by weight. . In this case, if the content of the polymerizable monomer (b1) is too small, the strength of the cured film may be insufficient, while if it is too large, the flexibility of the cured film may be insufficient.

  In the present invention, the content of the polymerizable monomer (b2) in the ink is usually 5 to 80% by weight, preferably 10 to 50% by weight, and particularly preferably 15 to 40% by weight. In this case, if the content of the polymerizable monomer (b2) is too small, the viscosity when used as an ink tends to increase, whereas if it is too large, the strength of the cured film may be insufficient.

  In the present invention, the content of the polymerizable monomer (b3) in the ink is usually 5 to 90% by weight, preferably 20 to 80% by weight, and particularly preferably 40 to 70% by weight. In this case, if the amount of other monomers used is too small, the film strength tends to deteriorate when used as an ink, and if too large, curing failure tends to occur.

(C) Photopolymerization Initiator The (C) photopolymerization initiator in the present invention contains a compound represented by the formula (2) (hereinafter referred to as “acetophenone compound (2)”) and is active. It is a component which has the effect | action which raise | generates the polymerization reaction of the polymerizable unsaturated bond in (B) polymeric monomer by irradiation of an energy ray. The acetophenone compound (2) is an essential component as a photopolymerization initiator (C) because it has good sensitivity and excellent solubility in (B) a polymerizable monomer.

In the formula (2), examples of the linear or branched alkyl group having 1 to 4 carbon atoms of R ² and R ³ include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n- A butyl group, i-butyl group, sec-butyl group, and t-butyl group can be mentioned.
Of these alkyl groups, a methyl group and an ethyl group are preferable, and a methyl group is particularly preferable.

Specific examples of the preferred acetophenone compound (1) include
2- (4-Methylbenzyl) -2- (dimethylamino) -1- (4-morpholinophenyl) ethane-1-one, 2- (4-ethylbenzyl) -2- (dimethylamino) -1- ( 4-morpholinophenyl) ethane-1-one, 2- (4-n-propylbenzyl) -2- (dimethylamino) -1- (4-morpholinophenyl) ethane-1-one, 2- (4- n-butylbenzyl) -2- (dimethylamino) -1- (4-morpholinophenyl) ethane-1-one,

2- (4-Methylbenzyl) -2- (diethylamino) -1- (4-morpholinophenyl) ethane-1-one, 2- (4-ethylbenzyl) -2- (diethylamino) -1- (4- Morpholinophenyl) ethane-1-one, 2- (4-n-propylbenzyl) -2- (diethylamino) -1- (4-morpholinophenyl) ethane-1-one, 2- (4-n-butyl) And benzyl) -2- (diethylamino) -1- (4-morpholinophenyl) ethane-1-one.

In the present invention, a commercially available product can be used as the acetophenone compound (2).
As a commercially available product of 2- (4-methylbenzyl) -2- (dimethylamino) -1- (4-morpholinophenyl) ethane-1-one, for example, Irgacure 379 (Ciba Specialty) Chemicals).
In the present invention, the acetophenone compound (2) can be used alone or in admixture of two or more.

In the present invention, the acetophenone compound (2) is used as the photopolymerization initiator (C) from the viewpoint of reducing the odor of the decomposition product of the photopolymerization initiator (C) generated upon irradiation with active energy rays. In addition, it is preferable to use another photopolymerization initiator in combination.
Examples of the other photopolymerization initiator include other acetophenone compounds, biimidazole compounds, benzophenone compounds, benzoin compounds, α-diketone compounds, polynuclear quinone compounds, xanthone compounds, phosphine compounds, A triazine type compound, an O-acyl oxime type compound, etc. can be mentioned.

  Specific examples of the other acetophenone compounds include 2,2-dimethoxyacetophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2′-dimethoxy-1,2-diphenyl. Ethan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-i-propylphenyl) -2-hydroxy-2-methylpropan-1-one, 1- [ 4- (methylthio) phenyl] -2-methyl-2-morpholinopropan-1-one, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 1- (4-morpholino Phenyl) -2-benzyl-2-dimethylaminobutan-1-one, 1- (2-bromo-4-morpholinophenyl) -2-benzi 2-dimethylaminobutan-1-one, 1- (4-morpholinophenyl) -2- (2-bromobenzyl) -2-dimethylaminobutan-1-one, 1- (4-morpholinophenyl)- 2- (4-Bromobenzyl) -2-dimethylaminobutan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1,2-diphenylethane-1-one and the like can be mentioned.

As specific examples of the biimidazole compound,
2,2′-bis (2-chlorophenyl) -4,4 ′, 5,5′-tetrakis (4-ethoxycarbonylphenyl) -1,2′-biimidazole, 2,2′-bis (2-bromophenyl) ) -4,4 ′, 5,5′-tetrakis (4-ethoxycarbonylphenyl) -1,2′-biimidazole, 2,2′-bis (2-chlorophenyl) -4,4 ′, 5,5 ′ -Tetraphenyl-1,2'-biimidazole, 2,2'-bis (2,4-dichlorophenyl) -4,4 ', 5,5'-tetraphenyl-1,2'-biimidazole, 2,2 '-Bis (2,4,6-trichlorophenyl) -4,4', 5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis (2-bromophenyl) -4, 4 ′, 5,5′-tetraphenyl-1,2′-biimidazole, 2,2′-bis (2,4 -Dibromophenyl) -4,4 ', 5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis (2,4,6-tribromophenyl) -4,4', 5 , 5′-tetraphenyl-1,2′-biimidazole and the like.

In the present invention, when a biimidazole compound is used in combination as another photopolymerization initiator, it is preferable to add a hydrogen donor described below in terms of further improving sensitivity.
The “hydrogen donor” as used herein means a compound that can donate a hydrogen atom to a radical generated from a biimidazole compound by exposure.
As such a hydrogen donor, a mercaptan compound defined below, an amine compound defined below, and the like are preferable.
The mercaptan-based compound is a compound having a benzene ring or a heterocyclic ring as a mother nucleus and having one or more, preferably 1 to 3, more preferably 1 to 2, mercapto groups directly bonded to the mother nucleus (hereinafter referred to as “mercaptan”). It is referred to as “system hydrogen donor”).
The amine compound is a compound having a benzene ring or a heterocyclic ring as a mother nucleus and having 1 or more, preferably 1 to 3, more preferably 1 to 2 amino groups directly bonded to the mother nucleus (hereinafter referred to as “the amine compound”). "Amine-based hydrogen donor").
These hydrogen donors can also have a mercapto group and an amino group at the same time.

The mercaptan-based hydrogen donor can have one or more benzene rings or heterocyclic rings, and can have both a benzene ring and a heterocyclic ring. When two or more of these rings are present, It may or may not be formed.
Further, when the mercaptan-based hydrogen donor has two or more mercapto groups, one or more of the remaining mercapto groups are substituted with an alkyl, aralkyl or aryl group as long as at least one free mercapto group remains. Furthermore, as long as at least one free mercapto group remains, a structural unit in which two sulfur atoms are bonded via a divalent organic group such as an alkylene group, or two sulfur atoms are It can have structural units linked in the form of disulfides.
Furthermore, the mercaptan-based hydrogen donor may be substituted with a carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted phenoxycarbonyl group, a nitrile group, or the like at a place other than the mercapto group.

Specific examples of such mercaptan hydrogen donors include 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzoimidazole, 2,5-dimercapto-1,3,4-thiadiazole, 2-mercapto- 2,5-dimethylaminopyridine and the like can be mentioned.
Of these mercaptan-based hydrogen donors, 2-mercaptobenzothiazole and 2-mercaptobenzoxazole are preferable, and 2-mercaptobenzothiazole is particularly preferable.

The amine-based hydrogen donor can have one or more benzene rings or heterocyclic rings, and can have both a benzene ring and a heterocyclic ring. When two or more of these rings are present, It may or may not be formed.
In the amine-based hydrogen donor, at least one of the amino groups may be substituted with an alkyl group or a substituted alkyl group, and a carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted group may be substituted at a position other than the amino group. Alternatively, it may be substituted with an unsubstituted phenoxycarbonyl group, nitrile group or the like.

  Specific examples of such amine-based hydrogen donors include 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamino) benzophenone, 4-diethylaminoacetophenone, 4-dimethylaminopropiophenone, Examples include ethyl 4-dimethylaminobenzoate, i-amyl 4-dimethylaminobenzoate, 4-dimethylaminobenzoic acid, 4-dimethylaminobenzonitrile and the like.

In the present invention, the hydrogen donor can be used alone or in admixture of two or more. However, one or more mercaptan hydrogen donors and one or more amine hydrogen donors are used in combination. It is preferable that the cured product obtained after the exposure is difficult to drop off from the substrate and that the cured product has high strength and sensitivity.
Specific examples of a preferred combination of a mercaptan hydrogen donor and an amine hydrogen donor include 2-mercaptobenzothiazole / 4,4′-bis (dimethylamino) benzophenone, 2-mercaptobenzothiazole / 4,4′-. Bis (diethylamino) benzophenone, 2-mercaptobenzoxazole / 4,4′-bis (dimethylamino) benzophenone, 2-mercaptobenzoxazole / 4,4′-bis (diethylamino) benzophenone, and the like are further preferable combinations. Are 2-mercaptobenzothiazole / 4,4′-bis (diethylamino) benzophenone and 2-mercaptobenzoxazole / 4,4′-bis (diethylamino) benzophenone, and a particularly preferred combination is 2-mercaptobenzothia A Lumpur / 4,4'-bis (diethylamino) benzophenone.
The weight ratio of mercaptan hydrogen donor to amine hydrogen donor in the combination of mercaptan hydrogen donor and amine hydrogen donor is usually 1: 1 to 1: 4, preferably 1: 1 to 1: 3.

  In the present invention, when other acetophenone compounds are used in combination as other photopolymerization initiators, one or more hydrogen donors can be added.

Specific examples of the benzophenone compounds include benzophenone, 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamino) benzophenone, and the like.
Specific examples of the benzoin compound include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and methyl-2-benzoyl benzoate.
Specific examples of the α-diketone compound include diacetyl, dibenzoyl, methylbenzoyl formate, and the like.
Specific examples of the polynuclear quinone compound include anthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 1,4-naphthoquinone, and the like.
Specific examples of the xanthone compound include xanthone, thioxanthone, and 2-chlorothioxanthone.
Specific examples of the phosphine compound include bis (2,4,6-trimethyl) phenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, and 2,4,6-trimethylbenzoyldiphenyl. A phosphine oxide etc. can be mentioned.

  Specific examples of the triazine compound include 2,4,6-tris (trichloromethyl) -s-triazine, 2-methyl-4,6-bis (trichloromethyl) -s-triazine, 2- [2 -(Furan-2-yl) ethenyl] -4,6-bis (trichloromethyl) -s-triazine, 2- [2- (5-methylfuran-2-yl) ethenyl] -4,6-bis (trichloro Methyl) -s-triazine, 2- [2- (4-diethylamino-2-methylphenyl) ethenyl] -4,6-bis (trichloromethyl) -s-triazine, 2- [2- (3,4-dimethoxy) Phenyl) ethenyl] -4,6-bis (trichloromethyl) -s-triazine, 2- (4-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4- Triazine-based compounds having a halomethyl group such as xystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4-n-butoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine Etc.

Specific examples of the O-acyloxime compound include 1- [4- (phenylthio) phenyl] -heptane-1,2-dione 2- (O-benzoyloxime), 1- [4- (phenylthio). Phenyl] -octane-1,2-dione 2- (O-benzoyloxime), 1- [4- (benzoyl) phenyl] -octane-1,2-dione 2- (O-benzoyloxime), 1- [9 -Ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl] -ethanone 1- (O-acetyloxime), 1- [9-ethyl-6- (3-methylbenzoyl) -9H-carbazole -3-yl] -ethanone 1- (O-acetyloxime), 1- (9-ethyl-6-benzoyl-9H-carbazol-3-yl) -ethanone 1- (O-acetyl) Oxime), ethanone-1- [9-ethyl-6- (2-methyl-4-tetrahydrofuranylbenzoyl) -9H-carbazol-3-yl] -1- (O-acetyloxime), ethanone-1- [9 -Ethyl-6- (2-methyl-4-tetrahydropyranylbenzoyl) -9H-carbazol-3-yl] -1- (O-acetyloxime), ethanone-1- [9-ethyl-6- (2- Methyl-5-tetrahydrofuranylbenzoyl) -9H-carbazol-3-yl] -1- (O-acetyloxime), ethanone-1- [9-ethyl-6- (2-methyl-5-tetrahydropyranylbenzoyl) -9H-carbazol-3-yl] -1- (O-acetyloxime), ethanone-1- [9-ethyl-6- {2-methyl-4- (2,2-dimethyl-) , 3-Dioxolanyl) benzoyl} -9H-carbazol-3-yl] -1- (O-acetyloxime), ethanone-1- [9-ethyl-6- (2-methyl-4-tetrahydrofuranylmethoxybenzoyl)- 9H-carbazol-3-yl] -1- (O-acetyloxime), ethanone-1- [9-ethyl-6- (2-methyl-4-tetrahydropyranylmethoxybenzoyl) -9H-carbazol-3-yl ] -1- (O-acetyloxime), ethanone-1- [9-ethyl-6- (2-methyl-5-tetrahydrofuranylmethoxybenzoyl) -9H-carbazol-3-yl] -1- (O-acetyl) Oxime), ethanone-1- [9-ethyl-6- (2-methyl-5-tetrahydropyranylmethoxybenzoyl) -9H-carbazo -3-yl] -1- (O-acetyloxime), ethanone-1- [9-ethyl-6- {2-methyl-4- (2,2-dimethyl-1,3-dioxolanyl) methoxybenzoyl } -9H-carbazol-3-yl] -1- (O-acetyloxime) and the like.
The other photopolymerization initiators can be used alone or in admixture of two or more.

  As other photopolymerization initiators in the present invention, at least one selected from the group of other acetophenone compounds, phosphine compounds and O-acyloxime compounds can avoid poor curing due to oxygen, This is preferable in that the sensitivity is further improved.

  In the present invention, the proportion of the acetophenone compound (2) used is usually 1 to 100% by weight, preferably 5 to 80% by weight, particularly preferably 5 to 60% by weight, based on the total amount of the (C) photopolymerization initiator. %. In this case, if the usage ratio of the acetophenone compound (2) is too small, curing may be insufficient.

In the present invention, the content of the (C) photopolymerization initiator in the ink is usually 1 to 20% by weight, preferably 2 to 15% by weight, and particularly preferably 3 to 10% by weight. In this case, if the content of the (C) photopolymerization initiator is too small, the curing may be insufficient or the film surface may become sticky due to poor curing. Insufficient curing reaction may result in a decrease in film strength.
Furthermore, in the present invention, (C) a photopolymerization initiator may be used in combination with one or more of a sensitizer, a curing accelerator, or a polymer photocrosslinking / sensitizer as necessary.

Other compounding components The active energy ray-curable ink for ink jet printing according to the present invention further includes, as components other than those described above, for example,
A polymerization inhibitor for enhancing the storage stability as an ink;
Antioxidants such as 2,2′-thiobis (4-methyl-6-tert-butylphenol), 2,6-di-tert-butylphenol;
UV absorbers such as 2- (3-t-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, alkoxybenzophenones;
Dispersing aids such as blue pigment derivatives and yellow pigment derivatives such as copper phthalocyanine derivatives;
Fillers such as glass and alumina;
Polymer compounds such as polyvinyl alcohol, polyethylene glycol monoalkyl ethers, poly (fluoroalkyl acrylates);
Nonionic, cationic and anionic surfactants;
Vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltri Methoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-chloropropyl Adhesion promoters such as methyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane;
Anti-agglomeration agents such as sodium polyacrylate;
Thermal radical generators such as 1,1′-azobis (cyclohexane-1-carbonitrile) and 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile can be blended.
The active energy ray-curable ink for inkjet printing according to the present invention comprises the components (A) to (C) as essential components, optionally further containing the other blending components, and basically does not contain a solvent. However, if necessary, a small amount of a solvent can be contained. Here, the solvent is a non-reactive and liquid compound at room temperature, and does not include the component (B) and other compounding components. In the present invention, the content of the solvent in the ink is 10% by weight or less, preferably 5% by weight or less, and particularly preferably 2% or less. In this case, when there is too much content of a solvent, there exists a possibility that hardening may become inadequate or the odor after printing may arise.

  The active energy ray-curable ink for inkjet printing of the present invention can be prepared by an appropriate method. For example, the component (A), the component (B), the component (C) and the like are mixed by a conventional method. However, when a pigment is blended as the component (A), the pigment is mixed and dispersed while being pulverized in the presence of a dispersant, for example, using a bead mill, a roll mill, etc. to obtain a pigment dispersion. It can also be prepared by adding (B) component, (C) component and the like and mixing them.

  The viscosity of the active energy ray-curable ink for ink jet printing of the present invention is 30 mPa · s or less, preferably 5 to 24 mPa · s at room temperature (25 ° C.). When the ink has such a viscosity, it can be stably discharged continuously from the nozzle head, and a high-definition printed matter can be stably obtained.

Printing Method Here, a printing method using the active energy ray-curable ink for inkjet printing of the present invention (hereinafter also simply referred to as “the ink of the present invention”) will be described.
This printing method basically includes [I] a step of printing the ink of the present invention on the surface of a printing material by an inkjet method, and [II] a step of crosslinking and curing the ink by exposing energy rays. It is. However, the ink of the present invention can be widely applied to various types of printing other than the inkjet method, such as a printing method using a spinner.

Hereinafter, each process will be described.
[I] Process The ink of the present invention can be used, for example, in addition to normal uncoated paper or coated paper, plastic, rubber, wood, metal, glass, ceramics, etc., regardless of the presence or absence of ink absorptivity. It can be applied to various printing materials regardless of the presence or absence.
Examples of the plastic include polyester (for example, polyethylene terephthalate, polybutylene terephthalate, etc.), polycarbonate, polyacetal, OPS, OPP, ONy, TAC, polyethylene, polyvinyl chloride, acrylic resin, and impact-resistant styrenic resin (for example, ABS resin and the like) and polyvinyl alcohol. These plastics can be used with or without heat shrinkability.

  Examples of the rubber include olefin rubber (for example, ethylene-propylene rubber, ethylene-propylene-nonconjugated diene rubber, butyl rubber, etc.), halogen-containing rubber (for example, chlorinated polyolefin rubber, fluorine rubber, etc.), styrene. Block copolymers (eg, styrene-butadiene, styrene-butadiene-styrene, styrene-isoprene, styrene-isoprene-styrene, etc.), polyurethane elastomers, polyester elastomers, polyamide elastomers, and the like. These rubbers can be used regardless of whether they are vulcanized or crosslinked.

When printing on the surface of the printing material, the ink and the nozzle head are maintained at a constant temperature of, for example, usually 10 to 100 ° C., preferably 15 to 60 ° C. so that stable continuous ejection is possible. Is preferred.
The amount of ink ejected from the nozzle head is, for example, usually 2 to 15 picoliters / second, preferably 4 to 12 picoliters / second.
When printing on a printing material, the amount of ink discharged varies depending on the purpose of use of the printing material, but the total film thickness after curing is, for example, usually 1 to 25 μm, preferably 3 to 15 μm. Is desirable.

[II] Step The exposure is usually performed within 0.001 to 2.0 seconds, preferably 0.001 to 1.0 seconds after the landing of the ink. In order to perform high-definition printing, an earlier exposure timing is appropriate.
In printing, it may be printed in a single layer or multiple layers, and may be printed in a single color or multiple colors. In addition, when printing in a multilayered stack, it is desirable to expose each time after printing each layer.

As the energy rays used for exposure, for example, ultraviolet rays, far ultraviolet rays, visible rays, X rays, electron rays, molecular rays, γ rays, synchrotron radiation, proton beam rays, etc. can be used. Ultraviolet light having a wavelength of 200 to 500 nm, preferably 240 to 420 nm is desirable. Further, the total power consumption of the light source used in the ink jet method is generally over 1 kW · hr, but the ink of the present invention has high sensitivity and the total power consumption is 1 kW · hr or less. Light sources such as fluorescent tubes, cold cathode tubes, light emitting diodes (LEDs), etc. can also be used.
The exposure amount is usually 1,000 to 15,000 J / m ² , preferably 3,000 to 10,000 J / m ² .
As the exposure method, for example, a method described in JP-A-60-132767 and US Pat. No. 6,145,795, more specifically, a shuttle method, an optical fiber method, or the like can be employed.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples. Here, “part” is based on weight.

Example 1
(A) As a colorant, C.I. I. Pigment Blue 15: 4 (2.2 parts), Solsperse S24000 (0.5 parts) as a dispersant, (B) Polymerizable monomer, pentaerythritol tetraacrylate (2.5 parts), diethylene glycol monovinyl ether acrylate (32.7 parts), tetra 22.7 parts of ethylene glycol diacrylate, 6 parts of isobornyl acrylate and 24.6 parts of N-vinylpyrrolidone, (C) 1.0 part of Irgacure 379 as a photopolymerization initiator, 2,2′-dimethoxy-1, 4.0 parts of 2-diphenylethane-1-one (trade name Irgacure 651, manufactured by Ciba Specialty Chemicals) and bis (2,4,6-trimethyl) phenylphosphine oxide (trade names Irgacure 819, Ciba (Specialty Chemicals, Inc.) 3 The ink was prepared by mixing 7 parts.

Next, the obtained ink was evaluated in the following manner.
It was 6.8 mPa * s when the viscosity (25 degreeC) of the ink was measured using the Tokyo Keiki Co., Ltd. ELD type | mold viscosity meter (25 degreeC).
Also, after applying ink to the surface of the polycarbonate substrate with a spinner, the formed coating film is exposed to a metal halide lamp with a single exposure amount of 1,000 J / m ² until the tack disappears with the finger touch. The total exposure amount (necessary exposure amount) required until the tack disappeared repeatedly was 2,000 J / m ² .

In addition, regarding a cured film having a thickness of 30 μm prepared by applying ink by a casting method and exposing the formed coating film with a metal halide lamp at an exposure amount of 10,000 J / m ² , Yasuda Seiki Co., Ltd. A bending test (JIS K-5400) was performed using a coating film bending tester manufactured, and the number of possible bendings was evaluated. As a result, bending of 10 times or more was possible.
The results are shown in Table 1.

  Moreover, the discharge test by an inkjet apparatus was performed using Nanoprinter-1500 (made by Microjet Co., Ltd.). The ink and nozzle head were held at 23 ° C., and an ejection test was conducted at a setting of 6 picoliter per ink drop. After discharging 10,000 inks, the process of taking an interval of 60 s was repeated twice, and further 10,000 inks were discharged, but the ink was not clogged until the end.

Examples 2-9 and Comparative Examples 1-3
An ink was prepared and evaluated in the same manner as in Example 1 except that the type and amount of each component were as shown in Table 1.
The evaluation results are shown in Table 1.

Each component in Table 1 is as follows.
Polymerizable monomer b1-1: Pentaerythritol tetraacrylate b1-2: Dipentaerythritol hexaacrylate b1-3: Compound represented by the above formula (3) (trade name UA-31, manufactured by Toho Chemical Co., Ltd.)
b1-4: caprolactone-modified (trisacryloxyethyl) isocyanurate (trade name M-325, manufactured by Toagosei Co., Ltd.)
b2-1: diethylene glycol monovinyl ether acrylate b3-1: isobornyl acrylate b3-2: tetraethylene glycol diacrylate b3-3: N-vinylpyrrolidone b3-4: triethylene glycol divinyl ether b3-5: ε-vinylcaprolactam

Photopolymerization initiator C-1: 2- (4-methylbenzyl) -2- (dimethylamino) -1- (4-morpholinophenyl) ethane-1-one (trade name Irgacure 379, Ciba Specialty Chemicals) (Made by company)
C-2: 2,2′-dimethoxy-1,2-diphenylethane-1-one (trade name Irgacure 651, manufactured by Ciba Specialty Chemicals)
C-3: Bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (trade name Irgacure 819, manufactured by Ciba Specialty Chemicals)
C-4: 1- (4-morpholinophenyl) -2-benzyl-2-dimethylaminobutan-1-one (trade name Irgacure 369, manufactured by Ciba Specialty Chemicals)
C-5: 1-hydroxycyclohexyl phenyl ketone (trade name Irgacure 184, manufactured by Ciba Specialty Chemicals)
C-6: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (trade name DAROCURE TPO, manufactured by Ciba Specialty Chemicals)
C-7: 1- [9-Ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl] -ethanone 1- (O-acetyloxime) (trade name Irgacure OXE02, Ciba Specialty Chemicals (Made by company)

Pigment A-1: C.I. I. Pigment Blue 15: 4
A-2: C.I. I. Pigment Red 202
A-3: C.I. I. Pigment Bio Red 19
A-4: C.I. I. Pigment Yellow 180
A-5: C.I. I. Pigment White 6
A-6: C.I. I. Pigment Blue 7
Dispersant a-1: Solsperse S24000 (trade name, manufactured by Seneca Corporation)
a-2: Solsperse S32000 (trade name, manufactured by Seneca Corporation)

  In the bending test results, those that can be bent 10 times or more were evaluated as “B”, those that could be bent from 1 time to less than 10 times were “Δ”, and those that could not be bent were “×”.

  As is clear from Table 1, the ink of the present invention has a low viscosity, excellent dischargeability, and can form a flexible and good coating film with a small active energy dose. On the other hand, in Comparative Example 1 in which the polymerizable monomer of the formula (1) (b2) is not used, the coating film cannot be bent and is broken, and the active energy ray sensitivity is low. (C) In Comparative Example 2 in which the photopolymerization initiator does not use the compound of the formula (2), the coating film has poor bendability and the active energy ray sensitivity is low. In Comparative Example 3 in which (b1) is not blended as the polymerizable monomer, the coating film cannot be bent and is broken, and the active energy ray sensitivity is low.

Claims (3)

(A) Colorant, (B) As a polymerizable monomer, (b1) a compound having three or more polymerizable unsaturated bonds in one molecule, (b2) a compound represented by the following formula (1), and (b3) Contains a photopolymerization initiator comprising a compound other than the above (b2) having one or two polymerizable unsaturated bonds in one molecule, and (C) a compound represented by the following formula (2). An active energy ray-curable ink for inkjet printing, characterized by the above.
(In the formula, R ¹ represents a hydrogen atom or a methyl group, and n is an integer of 0 to 6.)
(In the formula, each of R ² and R ³ independently represents a linear or branched alkyl group having 1 to 4 carbon atoms.)   In the ink, the content of the component (b1) is 0.1 to 20% by weight, the content of the component (b2) is 5 to 80% by weight, and the content of the component (b3) is 5 to 90% by weight. The active energy ray-curable ink for ink jet printing according to claim 1.   The active energy ray-curable ink for ink jet printing according to claim 1 or 2, wherein the content of the solvent in the ink is 10% by weight or less.