JP2017095531A - Ink composition for photosetting inkjet printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink composition for photosetting inkjet printing capable of forming a cured film even when integration light volume of irradiation energy of ultraviolet is small and the cured film having sufficient adhesiveness, solvent resistance and scratch resistance even when integration light volume of irradiation energy of ultraviolet is small by using the composition.SOLUTION: There is provided an ink composition for photosetting inkjet printing containing a polymerizable compound and a photoinitiator, in which the polymerizable compound contains a monomer A represented by the formula (1) and an acrylamide-based monomer, percentage of the monomer A is 1 to 90 mass%, percentage of the acrylamide-based monomer is 1 to 90 mass% and percentage of total of the monomer A and the acrylamide-based monomer is 20 mass% or more in the polymerizable compound. CH=CR-COOR-O-CH=CH-R(1).SELECTED DRAWING: None

Description

  The present invention relates to a photocurable ink composition for ink jet printing, a cured film formed from the photocurable ink composition for ink jet printing, and an ink jet printing method using the photocurable ink composition for ink jet printing.

  In recent years, an ink jet printing system has been increasingly used for outdoor large-scale advertisements that require a large image area. In addition, as a base material (printed medium) for these large-scale advertisements and the like, chlorides that can withstand outdoor use, such as sheets made of vinyl chloride resin and tarpaulin sheets made of composite materials such as vinyl chloride resin and synthetic fibers, etc. Vinyl resin sheet is used. And as the ink composition for inkjet printing which prints (prints) on this polyvinyl chloride resin sheet, the photocurable ink composition for inkjet printing which does not contain volatile components, such as a solvent, is used.

  In order for the above-mentioned large advertisements and the like to withstand wind and rain, the photocurable ink composition for inkjet printing must be capable of forming a tough cured film. However, generally, a tough cured film formed from a photocurable ink composition for inkjet printing has a high film hardness and tends to have poor adhesion to a substrate.

  Therefore, in order to improve the adhesion of the cured film to the substrate, a method of incorporating a component for improving the adhesion into the photocurable ink composition for inkjet printing is employed. For example, in Patent Document 1, an epoxy group-containing polymer is used as a component for improving adhesion, and in Patent Document 2, N-vinylcaprolactam is used.

  Moreover, since the photocurable ink composition for inkjet printing contains a photoinitiator, there was a concern that the obtained cured film may be colored. Patent Document 3 proposes that the above problem can be solved by using an acylphosphine oxide containing a predetermined amount of monoacylphosphine oxide as a photopolymerization initiator.

JP 2012-158638 A JP 2012-116934 A JP 2012-117027 A

Furthermore, in recent years, from the viewpoint of environmental protection, the light source of the photocurable ink composition for inkjet printing is being replaced by a light emitting diode (LED) from a mercury lamp or a metal halide lamp. In addition, from the viewpoint of production efficiency, there has been a demand for a photocurable ink composition for inkjet printing that can be sufficiently cured even when the irradiation energy of the LED is small (for example, the integrated light amount is 100 mJ / cm ² or less).

However, the photocurable ink composition for inkjet printing disclosed in Patent Documents 1 to 3 does not have sufficient curability when the integrated light amount of ultraviolet irradiation energy is small (for example, the integrated light amount is 100 mJ / cm ² or less). There is a fear.

Therefore, the present invention is a photocurable ink jet printing capable of forming a cured film even when the integrated light amount of irradiation energy of ultraviolet rays (particularly, ultraviolet rays using LEDs as light sources) is small (for example, the integrated light amount is 100 mJ / cm ² or less). It is an object of the present invention to provide an ink composition.

  It is another object of the present invention to provide a cured film having sufficient adhesion, solvent resistance, and abrasion resistance even when the cumulative amount of ultraviolet irradiation energy is small.

  As a result of intensive studies to solve the above problems, the present inventors have obtained the following photocurable ink composition for ink jet printing, a cured film formed from the photocurable ink composition for ink jet printing, and a photocurable ink composition. The inventors have found an ink jet printing method using an ink composition for ink jet printing.

That is, the present invention is a photocurable ink composition for inkjet printing containing a polymerizable compound and a photopolymerization initiator, and the polymerizable compound is represented by the following general formula (I):
CH ₂ = CR ¹ —COOR ² —O—CH═CH—R ³ (wherein R ¹ is a hydrogen atom or a methyl group, R ² is a divalent organic residue having 2 to 20 carbon atoms, R ³ is a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms.) And an acrylamide monomer, and the ratio of the monomer A in the polymerizable compound is 1 to 90% by mass, the ratio of the acrylamide monomer is 1 to 90% by mass, and the total ratio of the monomer A and the acrylamide monomer is 20% by mass or more. .

In the photocurable ink composition for ink jet printing of the present invention, the acrylamide monomer is represented by the following general formula (II):
CH ₂ ═CR ⁴ —CON (R ⁵ ) R ⁶ (wherein R ⁴ is a hydrogen atom or a methyl group. R ⁵ and R ⁶ are the same or different and represent a hydrogen atom or a substituted or unsubstituted carbon number) 1 to 8 alkyl groups, but they are not hydrogen atoms, or R ⁵ and R ⁶ may be bonded to each other to form a ring with an adjacent nitrogen atom.) Monomer B is preferred.

  In the photocurable ink composition for ink jet printing according to the present invention, the monomer A is one or more of 2- (vinyloxyethoxy) ethyl acrylate and 2- (vinyloxyethoxy) ethyl methacrylate. Is preferred.

  In the photocurable ink composition for inkjet printing of the present invention, the photopolymerization initiator contains an acylphosphine oxide photopolymerization initiator, and the acylphosphine oxide photopolymerization initiator contains the polymerizable compound. It is preferable that it is 2-20 mass parts with respect to 100 mass parts.

  In the photocurable ink composition for ink jet printing according to the present invention, the photopolymerization initiator contains a thioxanthone photopolymerization initiator, and the thioxanthone photopolymerization initiator is based on 100 parts by mass of the polymerizable compound. It is preferable that it is 10 mass parts or less.

The photocurable ink composition for inkjet printing of the present invention preferably further contains a colorant.

  The present invention relates to a cured film formed from the photocurable ink composition for inkjet printing.

  The present invention is an ink jet printing method using the photocurable ink composition for ink jet printing, the step of adhering the photocurable ink composition for ink jet printing to a printing medium, and the photocurable type adhered The present invention relates to an ink jet printing method including a step of irradiating an ink composition for ink jet printing with ultraviolet rays having an emission peak wavelength in a range of 350 to 420 nm to form a cured film.

In the inkjet printing method of the present invention, it is preferable that the irradiation energy of the ultraviolet light is 100 mJ / cm ² or less.

  The photocurable ink jet printing composition of the present invention contains a predetermined amount of the monomer A represented by the general formula (I) and an acrylamide monomer. By using the monomer A and the acrylamide monomer together, a photocurable ink jet printing composition that exhibits good curability can be obtained even when the cumulative amount of ultraviolet irradiation energy is small. In particular, the acrylamide monomer can further improve the curability of the photocurable inkjet printing composition.

The photocurable ink composition for inkjet printing according to the present invention is a cured film even when the integrated light amount of irradiation energy of ultraviolet rays (particularly, ultraviolet rays using LEDs as light sources) is small (for example, the integrated light amount is 100 mJ / cm ² or less). Can be formed.

  In addition, the cured film formed from the photocurable ink composition for ink jet printing of the present invention has sufficient adhesion and solvent resistance even if it is obtained by suppressing the cumulative amount of ultraviolet irradiation energy. And scratch resistance.

  Furthermore, the ink jet printing method using the photocurable ink composition for ink jet printing of the present invention can form a cured film even when the cumulative amount of irradiation energy of ultraviolet rays is small, so that the production efficiency is high and useful. is there.

  The photocurable ink composition for inkjet printing of the present invention (hereinafter also referred to as an ink composition) contains at least a polymerizable compound and a photopolymerization initiator.

<Polymerizable compound>
The polymerizable compound of the present invention is polymerized upon irradiation with ultraviolet rays by the action of a photopolymerization initiator described later, and can cure the ink composition attached to the printing medium. The polymerizable compound contains monomer A and an acrylamide monomer.

<Monomer A>
The monomer A of the present invention has the following general formula (I):
_{^{CH 2 = CR 1 -COOR 2 -O}} -CH = CH-R 3
(In the formula, R ¹ is a hydrogen atom or a methyl group, R ² is a divalent organic residue having 2 to 20 carbon atoms, and R ³ is a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms. A monomer represented by the following formula: By containing the monomer A in the ink composition, the curability of the ink composition can be improved, and the viscosity of the ink composition can be further reduced. As the monomer A, at least one kind may be used, and two or more kinds may be used in combination.

In the general formula (I), the divalent organic residue having 2 to 20 carbon atoms represented by R ² is a linear, branched or cyclic alkylene group having 2 to 20 carbon atoms, in the structure Examples thereof include an alkylene group having 2 to 20 carbon atoms having an oxygen atom by an ether bond and / or an ester bond, and a bivalent aromatic group having 6 to 11 carbon atoms. Among these, C2-C6 alkylene groups such as ethylene group, n-propylene group, isopropylene group, and butylene group, oxyethylene group, oxy n-propylene group, oxyisopropylene group, and oxybutylene group An alkylene group having 2 to 9 carbon atoms having an oxygen atom by an ether bond in the structure is preferred.

In the general formula (I), the monovalent organic residue having 1 to 11 carbon atoms represented by R ³ is a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, carbon number Examples include 6 to 11 aromatic groups. Among these, C6-C2 aromatic groups, such as a C1-C2 alkyl group which is a methyl group or an ethyl group, a phenyl group, and a benzyl group, are preferable.

The divalent organic residue having 2 to 20 carbon atoms represented by R ² and the monovalent organic residue having 1 to 11 carbon atoms represented by R ³ may be substituted with each substituent. . Each substituent is divided into a group containing a carbon atom and a group not containing a carbon atom. When each substituent is a group containing a carbon atom, the carbon atom is included in the carbon number of the organic residue. Although it does not specifically limit as group containing a carbon atom, For example, a carboxyl group, an alkoxy group, etc. are mentioned. Moreover, although it does not specifically limit as a group which does not contain a carbon atom, For example, a hydroxyl group and a halo group are mentioned.

  Examples of the monomer A include 2-vinyloxyethyl (meth) acrylate, 3-vinyloxypropyl (meth) acrylate, 1-methyl-2-vinyloxyethyl (meth) acrylate, 2-vinyloxypropyl (meth) acrylate, (Meth) acrylic acid 4-vinyloxybutyl, (meth) acrylic acid 1-methyl-3-vinyloxypropyl, (meth) acrylic acid 1-vinyloxymethylpropyl, (meth) acrylic acid 2-methyl-3-vinyloxypropyl 1,1-dimethyl-2-vinyloxyethyl (meth) acrylate, 3-vinyloxybutyl (meth) acrylate, 1-methyl-2-vinyloxypropyl (meth) acrylate, 2-vinyloxybutyl (meth) acrylate, ( (Meth) acrylic acid 4-vinyloxycyclohexyl, (meth) acrylic acid 6-vinyloxy Hexyl, 4-vinyloxymethylcyclohexylmethyl (meth) acrylate, 3-vinyloxymethylcyclohexylmethyl (meth) acrylate, 2-vinyloxymethylcyclohexylmethyl (meth) acrylate, p-vinyloxy (meth) acrylate Methylphenylmethyl, m-vinyloxymethylphenylmethyl (meth) acrylate, o-vinyloxymethylphenylmethyl (meth) acrylate, 2- (vinyloxyethoxy) ethyl (meth) acrylate, (meth) acrylic acid 2 -(Vinyloxyisopropoxy) ethyl, 2- (vinyloxyethoxy) propyl (meth) acrylate, 2- (vinyloxyethoxy) isopropyl (meth) acrylate, 2- (vinyloxyisopropoxy) (meth) acrylate Propyl (meth) acrylic acid 2- (vinylo) Cyisopropoxy) isopropyl, 2- (vinyloxyethoxyethoxy) ethyl (meth) acrylate, 2- (vinyloxyethoxyisopropoxy) ethyl (meth) acrylate, 2- (vinyloxyisopropoxyethoxy) (meth) acrylate ) Ethyl, 2- (vinyloxyisopropoxyisopropoxy) ethyl (meth) acrylate, 2- (vinyloxyethoxyethoxy) propyl (meth) acrylate, 2- (vinyloxyethoxyisopropoxy) propyl (meth) acrylate 2- (vinyloxyisopropoxyethoxy) propyl (meth) acrylate, 2- (vinyloxyisopropoxyisopropoxy) propyl (meth) acrylate, 2- (vinyloxyethoxyethoxy) isopropyl (meth) acrylate, ( (Meth) acrylic acid 2- (vinyloxy) Ciethoxyisopropoxy) isopropyl, (meth) acrylic acid 2- (vinyloxyisopropoxyethoxy) isopropyl, (meth) acrylic acid 2- (vinyloxyisopropoxyisopropoxy) isopropyl, (meth) acrylic acid 2- (vinyloxy) Ethoxyethoxyethoxy) ethyl, (meth) acrylic acid 2- (vinyloxyethoxyethoxyethoxyethoxy) ethyl, (meth) acrylic acid 2- (isopropenoxyethoxy) ethyl, (meth) acrylic acid 2- (isopropenoxyethoxy) Ethoxy) ethyl, 2- (isopropenoxyethoxyethoxyethoxy) ethyl (meth) acrylate, 2- (isopropenoxyethoxyethoxyethoxyethoxy) ethyl (meth) acrylate, polyethylene glycol monovinyl ester (meth) acrylate Ether, and (meth) acrylic acid polypropylene glycol monovinyl ether.

  Among the monomers A, from the viewpoints of lowering the viscosity of the ink composition, having a high flash point, and excellent curability of the ink composition, 2- (vinyloxyethoxy) ethyl (meth) acrylate, that is, At least one of 2- (vinyloxyethoxy) ethyl acrylate and 2- (vinyloxyethoxy) ethyl methacrylate is preferable, and 2- (vinyloxyethoxy) ethyl acrylate is more preferable. In particular, since 2- (vinyloxyethoxy) ethyl acrylate and 2- (vinyloxyethoxy) ethyl methacrylate have a simple structure and a low molecular weight, the viscosity of the ink composition can be significantly reduced. . Examples of 2- (vinyloxyethoxy) ethyl (meth) acrylate include 2- (2-vinyloxyethoxy) ethyl (meth) acrylate and 2- (1-vinyloxyethoxy) ethyl (meth) acrylate. Examples of 2- (vinyloxyethoxy) ethyl acrylate include 2- (2-vinyloxyethoxy) ethyl acrylate and 2- (1-vinyloxyethoxy) ethyl acrylate. Incidentally, 2- (vinyloxyethoxy) ethyl acrylate is superior in terms of curability compared to 2- (vinyloxyethoxy) ethyl methacrylate.

<Acrylamide monomer>
The acrylamide monomer of the present invention can be used without particular limitation as long as the acrylamide monomer is capable of radical polymerization. By using an acrylamide monomer, the curability of the ink composition can be improved. Examples of the acrylamide monomer include the following general formula (II):
_{^{CH 2 = CR 4 -CON (R}} 5) R 6
(In the formula, R ⁴ is a hydrogen atom or a methyl group. R ⁵ and R ⁶ are the same or different and are a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms. Or R ⁵ and R ⁶ may be bonded to each other to form a ring with an adjacent nitrogen atom.), And the curability of the ink composition From the viewpoint of increasing the ratio, it is preferable. As the acrylamide monomer, at least one kind may be used, and two or more kinds may be used in combination.

In the monomer B, the substituted or unsubstituted alkyl group having 1 to 8 carbon atoms represented by R ⁵ and R ⁶ is a linear or branched substituted or unsubstituted alkyl group having 1 to 8 carbon atoms. Groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, and octyl group. And groups in which these groups are substituted with a functional group such as a hydroxyl group, a carbonyl group, or an alkoxy group.

In the monomer B, R ⁵ and R ⁶ may be bonded to each other to form a ring with an adjacent nitrogen atom, and examples of the ring structure include a pyrrolidine ring, a piperidine ring, and a morpholine ring.

  As said monomer B, (meth) acrylamide, (meth) N, N-dimethylacrylamide, (meth) N, N-diethylacrylamide, (meth) N, N-dipropylacrylamide, (meth) N, N-diisopropyl Acrylamide, (meth) acryloylmorpholine, diacetone (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N, N-bishydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N, N-bis Hydroxyethyl (meth) acrylamide, N-hydroxypropyl (meth) acrylamide, N, N-bishydroxypropyl (meth) acrylamide, N-hydroxybutyl (meth) acrylamide, N, N-bishydroxybutyl (meth) acrylic De, and the like.

  Among the monomers B, N-hydroxyethyl (meth) acrylamide, (meth) acryloylmorpholine, and diacetone (meth) acrylamide are preferable from the viewpoint of enhancing the curability of the ink composition, and N-hydroxyethylacrylamide, acryloylmorpholine, Diacetone acrylamide is particularly preferred.

  Furthermore, as the polymerizable compound of the present invention, other polymerizable components other than the monomer A and the acrylamide monomer can be used in combination. Other polymerizable components can be used without particular limitation as long as they are ethylenic double bond-containing compounds, and examples thereof include monomers, prepolymers, and oligomers.

  Examples of the other polymerizable components include low viscosity polymerizable components such as isobutyl acrylate, isooctyl acrylate, and isodecyl acrylate, urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, and 2-hydroxyethyl. (Meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, t-butyl (meth) acrylate, N-vinylcaprolactam, N-vinylpyrrolidone, benzyl (meth) acrylate, alkanediol di (Meth) acrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate and the like. 1 type (s) or 2 or more types can be used for another polymeric component.

  Below, the ratio of each component in the polymeric compound of this invention is demonstrated.

  The ratio of the monomer A in the polymerizable compound is 1 to 90% by mass. The ratio of the monomer A in the polymerizable compound is 2 from the viewpoint of increasing the curability of the photocurable ink composition for inkjet printing of the present invention and from the viewpoint of increasing the solvent resistance of the cured film formed from the ink composition. It is preferable that it is -88 mass%, and it is more preferable that it is 4-86 mass%.

  The ratio of the acrylamide monomer in the polymerizable compound is 1 to 90% by mass. The ratio of the acrylamide monomer in the polymerizable compound is from the viewpoint of increasing the curability of the photocurable ink composition for inkjet printing of the present invention and from the viewpoint of increasing the solvent resistance of the cured film formed from the ink composition. The content is preferably 2 to 88% by mass, and more preferably 4 to 86% by mass.

  The total ratio of the monomer A and the acrylamide monomer in the polymerizable compound is 20% by mass or more. The total ratio of the monomer A and the acrylamide monomer in the polymerizable compound is based on the viewpoint of enhancing the curability of the photocurable ink composition for inkjet printing of the present invention, and the solvent resistance of the cured film formed from the ink composition. From the viewpoint of increasing the amount, it is preferably 25% by mass or more, more preferably 30% by mass or more, and further preferably 35% by mass or more.

  The ratio of the other polymerizable component in the polymerizable compound is preferably 5 to 80% by mass and more preferably 6 to 60% by mass from the viewpoint of not reducing the effect of the present invention.

<Photopolymerization initiator>
The photopolymerization initiator of the present invention is used for curing an ink composition attached to the surface of a substrate (printed medium) by photopolymerization by irradiation with ultraviolet rays.

  The photopolymerization initiator is not limited as long as it generates active species such as radicals and cations by light energy and initiates polymerization of the polymerizable compound. Cationic polymerization initiators can be used, and among them, it is preferable to use a radical photopolymerization initiator. 1 type (s) or 2 or more types can be used for a photoinitiator.

  Examples of the photo radical polymerization initiator include acyl phosphine oxide photopolymerization initiators and thioxanthone photopolymerization initiators.

<Acylphosphine oxide photopolymerization initiator>
The acyl phosphine oxide photopolymerization initiator of the present invention is an acyl phosphine oxide photopolymerization initiator that exhibits an initiator function by light having a wavelength of 300 to 450 nm. By using such an acylphosphine oxide-based photopolymerization initiator, it is possible to impart curability to a light-emitting diode (LED) to the photocurable ink composition for inkjet printing of the present invention. The expression of the initiator function by the light having a wavelength of 300 to 450 nm means that the light has absorption characteristics over the entire wavelength range of 300 to 450 nm.

  Examples of the acylphosphine oxide photopolymerization initiator include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (trade name: TPO, manufactured by Lambson), bis (2,4,6-trimethylbenzoyl)- Examples thereof include phenylphosphine oxide (trade name: IRGACURE 819, manufactured by BASF).

<Thioxanthone photopolymerization initiator>
As the photopolymerization initiator of the present invention, it is preferable to use a thioxanthone photopolymerization initiator together with the acylphosphine oxide photopolymerization initiator. The thioxanthone photopolymerization initiator has light absorption characteristics mainly in the ultraviolet wavelength region of 400 nm or more, and the sensitization function of the curing reaction is manifested by light in the wavelength range. Curability can be promoted. Note that the expression of the sensitizing function by the light having a wavelength of 400 nm or more means that the light absorption characteristic is obtained in a wavelength region of 400 nm or more.

  Examples of the thioxanthone photopolymerization initiator include thioxanthone compounds such as 2,4-diethylthioxanthone, 2-isopropylthioxanthone, and 4-isopropylthioxanthone. Representative examples of commercially available products include DETX and ITX (manufactured by Lambson).

  The content of the acylphosphine oxide photopolymerization initiator is preferably 2 to 20 parts by mass with respect to 100 parts by mass of the polymerizable compound. The content of the acylphosphine oxide-based photopolymerization initiator is preferably 3 parts by mass or more, preferably 5 parts by mass or more with respect to 100 parts by mass of the polymerizable compound, from the viewpoint of enhancing curability. More preferred. In addition, the content of the acylphosphine oxide photopolymerization initiator is 19 parts by mass with respect to 100 parts by mass of the polymerizable compound from the viewpoint of enhancing the storage stability of the photocurable ink composition for inkjet printing of the present invention. It is more preferable that the amount is not more than parts.

  The content of the thioxanthone photopolymerization initiator is preferably 10 parts by mass or less with respect to 100 parts by mass of the polymerizable compound. The content of the thioxanthone photopolymerization initiator is preferably 8 parts by mass or less and more preferably 6 parts by mass or less with respect to 100 parts by mass of the polymerizable compound from the viewpoint of preventing excessive addition. .

<Colorant>
The photocurable ink composition for inkjet printing of the present invention preferably further contains a colorant.

  As the colorant, pigments and dyes conventionally used in ordinary photocurable ink compositions for ink jet printing can be used without particular limitation. From the viewpoint of enhancing light resistance, pigments such as organic pigments and inorganic pigments can be used. Use is preferred. 1 type (s) or 2 or more types can be used for a coloring agent.

  Examples of the organic pigment include dye lake pigments, azo, benzimidazolone, phthalocyanine, quinacridone, anthraquinone, dioxazine, indigo, thioindico, perylene, perinone, diketopyrrolopyrrole, and isoindo Examples include linone, nitro, nitroso, anthraquinone, flavanthrone, quinophthalone, pyranthrone, and indanthrone pigments. Examples of the inorganic pigment include carbon black, titanium oxide, bengara, graphite, iron black, chromium oxide green, and aluminum hydroxide.

  Moreover, the said pigment can be illustrated for every hue of the ink composition for photocurable inkjet printing of this invention.

  As a yellow pigment for use as a yellow ink composition for photo-curable ink jet printing, a color index name: C.I. I. Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 42, 73, 74, 75, 81, 83, 87, 93, 95, 97, 98, 108, 109, 114, 120, 128, Organic pigments such as 129, 138, 139, 150, 151, 155, 166, 180, 184, 185, 213, and the like. I. Pigment Yellow 150, 155, 180, 213 and the like.

  Examples of magenta pigments for use as a photocurable ink jet magenta ink composition include the color index name: C.I. I. Pigment Red 5, 7, 12, 22, 38, 48: 1, 48: 2, 48: 4, 49: 1, 53: 1, 57, 57: 1, 63: 1, 101, 102, 112, 122, 123, 144, 146, 149, 168, 177, 178, 179, 180, 184, 185, 190, 202, 209, 224, 242, 254, 255, 270, C.I. I. Organic pigments such as CI Pigment Violet 19, and the like. I. Pigment Red 122, 202, Pigment Violet 19, and the like.

  As a cyan pigment for use as a cyan ink composition for photocurable ink jet printing, a color index name: C.I. I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 18, 22, 27, 29, 60, etc., preferably, C. I. Pigment Blue 15: 4 and the like.

  Examples of the black pigment for use as the photocurable black ink composition for inkjet printing include inorganic pigments such as carbon black (color index name: CI Pigment Black 7).

  Examples of the white pigment for use as a white ink composition for photo-curable ink jet printing include inorganic pigments such as titanium oxide and aluminum oxide, and preferably an oxidized surface-treated with various materials such as alumina and silica. Titanium is mentioned.

  The ratio of the colorant is preferably 1% by mass or more, and more preferably 2% by mass or more, in the photocurable ink composition for inkjet printing, from the viewpoint of improving the image quality of the obtained printed matter. More preferably 4% by mass or more. The proportion of the colorant is preferably 20% by mass or less, and 18% by mass in the photocurable ink jet printing ink composition from the viewpoint of maintaining good viscosity characteristics of the photocurable ink jet printing ink composition. More preferably, it is more preferably 15% by mass or less.

  When the colorant is a yellow pigment, a magenta pigment, a cyan pigment, and a black pigment, the ratio of the yellow pigment, the magenta pigment, the cyan pigment, and the black pigment is photocured from the viewpoint of improving the image quality of the obtained printed matter. The content is preferably 1% by mass or more, more preferably 1.2% by mass or more, in the ink composition for type inkjet printing. The ratio of the yellow pigment, magenta pigment, cyan pigment, and black pigment is 5% by mass in the photocurable ink jet printing ink composition from the viewpoint of maintaining the good viscosity characteristics of the photocurable ink jet printing ink composition. Or less, more preferably 4% by mass or less.

  When the colorant is a white pigment, the proportion of the white pigment is preferably 3% by mass or more in the photocurable ink composition for inkjet printing from the viewpoint of improving the image quality of the obtained printed matter. More preferably, it is at least mass%. The proportion of the white pigment is preferably 15% by mass or less in the photocurable inkjet printing ink composition from the viewpoint of maintaining good viscosity characteristics of the photocurable inkjet printing ink composition. The following is more preferable.

  In addition, when the photocurable ink composition for inkjet printing of the present invention contains the pigment, the thioxanthone photopolymerization initiator tends to change the color of the ink composition to yellow. Therefore, it is preferable to appropriately determine the content of the thioxanthone photopolymerization initiator for each pigment.

  For example, the content of the thioxanthone photopolymerization initiator is preferably not used in a white ink composition and a clear ink composition that are susceptible to changes in color.

  Further, in the magenta ink composition and the cyan ink composition, a change in hue becomes a problem, and therefore, it is preferably used in a range where no problem occurs in the hue. The content of the thioxanthone photopolymerization initiator is preferably 150 parts by mass or less, more preferably 130 parts by mass or less, based on 100 parts by mass of magenta or cyan pigment described later. It is preferable to use at 40 parts by mass or more, and more preferable to use at 60 parts by mass or more.

  In addition, the black ink composition and the yellow ink composition are unlikely to affect the hue even if there is discoloration, and the photopolymerizability is poorer than other hues. It can be used in large amounts in comparison. The content of the thioxanthone photopolymerization initiator is preferably 300 parts by mass or less, more preferably 280 parts by mass or less, and 100 parts by mass with respect to 100 parts by mass of the black pigment described later. It is preferable to use it at more than 150 parts by weight, and more preferable to use at 150 parts by weight or more. Furthermore, the content of the thioxanthone-based photopolymerization initiator is preferably 300 parts by mass or less, more preferably 250 parts by mass or less, with respect to 100 parts by mass of the yellow pigment described later. It is preferably used at 100 parts by mass or more, and more preferably at 150 parts by mass or more.

<Pigment dispersant>
In addition, the photocurable ink composition for inkjet printing of the present invention may contain a pigment dispersant as necessary.

  The pigment dispersant is used for improving the dispersibility of the pigment and the storage stability of the ink composition, and those conventionally used can be used without any particular limitation. Among them, the polymer pigment dispersant is used. Is preferably used. 1 type (s) or 2 or more types can be used for a pigment dispersant.

  Examples of the polymer pigment dispersant include a carbodiimide dispersant, a polyesteramine dispersant, a fatty acid amine dispersant, a modified polyacrylate dispersant, a modified polyurethane dispersant, a multi-chain polymer nonionic dispersant, Examples thereof include a polymer ion activator.

  The content of the pigment dispersant is preferably 1 part by mass or more with respect to 100 parts by mass of the pigment, from the viewpoint of enhancing the dispersibility of the pigment and the storage stability of the ink composition. More preferably, it is preferably 100 parts by mass or less, and more preferably 60 parts by mass or less.

<Surfactant>
The photocurable ink composition for ink jet printing according to the present invention preferably contains a surfactant such as a silicone surfactant in order to improve ejection stability, depending on the ink jet head used. Surfactant can use 1 type (s) or 2 or more types.

  Examples of the silicone surfactant include polyether-modified silicone oil, polyester-modified polydimethylsiloxane, and polyester-modified methylalkylpolysiloxane.

  The ratio of the surfactant is 0.005% by mass or more in the photocurable ink composition for ink jet printing from the viewpoint of reducing the surface tension of the ink composition and improving the ejection stability from the ink jet head. Is preferable, and it is more preferable that it is 0.01 mass% or more. Further, the ratio of the surfactant is 1.0% by mass or less in the photocurable ink composition for ink jet printing from the viewpoint of suppressing bubbles generated in the ink composition during blending and improving ejection stability. It is preferable that it is 0.5 mass% or less.

<Other additives>
The photocurable ink composition for inkjet printing of the present invention can contain various additives in order to develop various functions as necessary. Various additives include light stabilizers, surface treatment agents, antioxidants, anti-aging agents, crosslinking accelerators, polymerization inhibitors, plasticizers, preservatives, pH adjusters, antifoaming agents, moisturizing agents, and the like. Can be mentioned.

<Method for Preparing Photocurable Ink Composition for Inkjet Printing>
The method for preparing the photocurable ink composition for ink jet printing of the present invention is not particularly limited, and a conventional method such as a wet dispersion method or a dry dispersion method can be used. It can be prepared by mixing with a three-roll mill or the like.

  In addition, as a method for preparing the photocurable ink composition for inkjet printing, for example, a polymerizable compound, a colorant, and a pigment dispersant are mixed to obtain a concentrated base ink in advance, and then the obtained concentrated ink is obtained. It can be prepared by adding a photopolymerization initiator and, if necessary, a surfactant or other additives to the base ink.

  The photocurable ink composition for ink jet printing according to the present invention preferably has a flash point of 70 ° C. or higher measured using a setter hermetic flash point measuring device by a method according to JIS K2265. By having such a flash point, the ink composition can be at a level corresponding to the flammable liquid category 4 referred to in GHS (Globally Harmonized System for Classification and Display of Chemicals), and safety such as low flammability. Excellent in properties.

  The photocurable ink composition for ink jet printing of the present invention has a viscosity at 25 ° C. of preferably 100 mPa · s or less, and preferably 50 mPa · s or less, from the viewpoint of enhancing the ejection stability of the ink composition. More preferably, it is 20 mPa · s or less, more preferably 1 mPa · s or more, and further preferably 5 mPa · s or more. Moreover, the specific viscosity of the photocurable ink composition for inkjet printing can also be designed so that it can adapt to each inkjet apparatus. In addition, the said viscosity shows the viscosity when it measures on 25 degreeC and 20 rpm conditions using an E-type viscosity meter (Brand name: RE100L type viscometer, the Toki Sangyo company make).

<Curing film>
The cured film of the present invention is formed by irradiating the photocurable ink composition for inkjet printing with ultraviolet rays.

<Printing method using photocurable ink composition for inkjet printing>
An ink jet printing method using the photocurable ink jet printing ink composition of the present invention includes a step of attaching a photocurable ink jet printing ink composition to a printing medium, and a photocurable ink jet ink composition attached thereto. And a step of irradiating the product with ultraviolet rays having an emission peak wavelength in the range of 350 to 420 nm to form a cured film.

  In the printing method using the photocurable ink composition for ink jet printing of the present invention, the base material (printing medium) to be used can preferably be a flooring material, a vinyl chloride resin, polycarbonate, etc. If it is a to-be-printed medium (paper, a plastic film, a capsule, a gel, metal foil, glass, cloth, etc.) used with the ink composition for type | mold inkjet printing, it can print without a problem.

  In the inkjet printing method using the photocurable ink composition for inkjet printing of the present invention, specifically, the ink composition is supplied to a low-viscosity printer head of an inkjet printing (recording) type printer to be printed. There is a method in which an ink composition is ejected from a printer head onto a medium so as to adhere to a medium to be printed, and a coating film of the adhered ink composition is irradiated with ultraviolet rays.

  As the ink jet printing (recording) system printer apparatus, a conventionally used ink jet printing system printer apparatus can be used. In the case of using a continuous type ink jet printing system printer device, it is preferable to further adjust the conductivity by adding a conductivity-imparting agent to the ink composition.

  Examples of the ultraviolet light source include a mercury lamp, a metal halide lamp, a light emitting diode (LED), and the like, but a light emitting diode is preferable from the viewpoint of the environment. The light emitting diode preferably emits ultraviolet light having an emission peak wavelength in the range of 350 to 420 nm.

In the printing method using the photocurable ink composition for ink-jet printing of the present invention, the irradiation energy of ultraviolet rays may also be 100 mJ / cm ² or less, also may be the 90 mJ / cm ² or less, further 80mJ / Cm ² or less.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

The materials used in the following examples and comparative examples are as follows.
<Monomer A>
2- (Vinyloxyethoxy) ethyl acrylate (VEEA, manufactured by Nippon Shokubai Co., Ltd.)
<Acrylamide monomer>
Acryloyl morpholine (ACMO, manufactured by KJ Chemicals)
Diacetone acrylamide (DAAM, Nippon Kasei Co., Ltd.)
Hydroxyethylacrylamide (HEAA, manufactured by KJ Chemicals)
<Other polymerizable components>
Benzyl acrylate (Biscoat # 160, manufactured by Osaka Organic Chemical Industry Co., Ltd.)
1,6-hexanediol acrylate (A-HD-N, manufactured by Shin-Nakamura Chemical Co., Ltd.)
Trimethylolpropane triacrylate (SR351, manufactured by Sartomer)
Pentaerythritol tetraacrylate (A-TMMT, manufactured by Shin-Nakamura Chemical Co., Ltd.)
Vinyl caprolactam (V-CAP, manufactured by ISP Japan)
<Acylphosphine oxide photopolymerization initiator>
2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (TPO, manufactured by Lambson)
<Thioxanthone photopolymerization initiator>
2,4-diethylthioxanthone (DETX, manufactured by Lambson)
<Colorant;Pigment>
Special Black 350 (black pigment, manufactured by Orion)
Novoperm Yellow P-HG (yellow pigment, manufactured by LANXESS)
Heliogen Blue D7110F (cyan pigment, manufactured by BASF)
FASTOGEN Super Magenta RTS (Magenta pigment, manufactured by DIC)
JR-800 (white pigment, manufactured by Teika)
<Pigment dispersant>
Polyesteramine dispersant, Solsperse 32000 (manufactured by Lubrizol)
<Surfactant>
Silicone-based surfactant BYK-UV3500 (manufactured by BYK Chemie)

<Example 1>
<Preparation of photocurable ink jet black ink composition>
56.3 parts by weight of vinyloxyethoxyethyl acrylate as monomer A, 15.0 parts by weight of acryloylmorpholine as an acrylamide monomer, 10.0 parts by weight of benzyl acrylate and 5 parts of trimethylolpropane triacrylate as other polymerizable components 0.0 parts by mass, a mixture containing 1.6 parts by mass of carbon black Special Black 350 as a pigment and 0.6 parts by mass of Solsperse 32000 as a pigment dispersant, Eiger mill (using zirconia beads having a diameter of 0.5 mm as a medium) ) Was used to obtain a black concrete base. To the obtained black concrete base, 7.0 parts by mass of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide as an acyl phosphine oxide photopolymerization initiator, and 2,4- as a thioxanthone photopolymerization initiator. 4.0 parts by mass of diethylthioxanthone and 0.5 parts by mass of BYK-UV3500 as a surfactant were blended, and after stirring and mixing, a black ink composition for photocurable inkjet printing of Example 1 was obtained.

<Examples 2 to 11>
<Preparation of photocurable ink jet black ink composition>
Using the materials shown in Table 1, the methods described in Example 1 were used to obtain photocurable ink jet printing black ink compositions of Examples 2 to 11.

<Example 12>
<Preparation of Photocurable Yellow Ink Composition for Inkjet Printing>
Using the materials shown in Table 1, the method described in Example 1 was used to obtain the photocurable yellow ink composition for inkjet printing of Example 12.

<Example 13>
<Preparation of Photocurable Inkjet Printing Cyan Ink Composition>
Using the materials described in Table 1, the method described in Example 1 was used to obtain a photocurable ink jet printing cyan ink composition of Example 13.

<Example 14>
<Preparation of Photocurable Inkjet Printing Magenta Ink Composition>
Using the materials shown in Table 1, the method described in Example 1 was used to obtain a photocurable ink jet printing magenta ink composition of Example 14.

<Example 15>
<Preparation of photocurable white ink composition for inkjet printing>
Using the materials listed in Table 1, the method described in Example 1 was used to obtain a photocurable white ink composition for inkjet printing of Example 15.

<Comparative Examples 1-7>
Using the materials shown in Table 2, the black ink compositions for photocurable inkjet printing of Comparative Examples 1 to 7 were obtained by the method described in Example 1.

  The following evaluation was performed using the photocurable ink composition for inkjet printing obtained by the said Example and comparative example. The results are shown in Tables 1 and 2.

(1) Measurement of viscosity of ink composition About the ink composition for photocurable ink jet printing obtained in Examples and Comparative Examples, an E-type viscometer (trade name: RE100L viscometer, manufactured by Toki Sangyo Co., Ltd.) is used. The viscosity was measured using a temperature of 25 ° C. and a rotor rotation speed of 20 rpm. The results are shown in Table 1.

(2) Evaluation of ejection stability of ink composition Inkjet printing (recording) apparatus equipped with inkjet nozzles for low viscosity ink at 25 ° C. ambient temperature, and photocurable type obtained in Examples and Comparative Examples The ink composition for ink jet printing was placed for 24 hours, and the temperature of the ink jet printing apparatus and each ink composition was set to 25 ° C. Thereafter, at 25 ° C., each ink composition was continuously printed (printed) on PVC80 (vinyl chloride resin sheet (12 cm × 18 cm), manufactured by Lintec Corporation) to evaluate discharge stability. Evaluation based on the criteria.
○: Printing is not disturbed and stable ejection is possible ×: Printing is disturbed or ejection is not possible stably

(3) Evaluation of Curability of Ink Composition The photocurable ink composition for inkjet printing obtained in Examples and Comparative Examples was added to PVC80 (vinyl chloride resin sheet (12 cm × 18 cm), manufactured by Lintec Corporation). 4 with a bar coater.
Next, with a UV-LED light lamp manufactured by Foseon Technology, the distance between the lamp and the ink application surface is 2 cm, and the irradiation condition is 1 second per irradiation time (the UV integrated light intensity per ^{second is} 60 mJ / cm ² ). Below, it evaluated by the frequency | count of irradiation until surface tack disappears, and formed the cured film.

(4) Evaluation of adhesion of cured film The cured film obtained in (3) above is cross-cut with a cutter knife, and cellophane tape (product name: cello tape (registered trademark), company name: Nichiban) is applied to the cut portion. Affixed and peeled off, the degree of peeling of the cured film from the vinyl chloride resin sheet was evaluated according to the following criteria.
○: No peeling of the cured film Δ: There was peeling of the cured film, but the peeling area was less than 20% ×: The peeling area of the cured film was 20% or more

(5) Evaluation of solvent resistance of cured film In the cured film obtained in (3) above, a bleached cloth impregnated with isopropyl alcohol using a Gakushin type fastness tester (manufactured by Daiei Kagaku Seisakusho). In order to judge the degree of dissolution of the cured film when the surface of the cured film is rubbed 20 times with a load of 500 g, the condition of the cured film surface rubbed with the exposed fabric is visually observed. The evaluation was based on the following criteria.
○: Neither the bleached cloth nor the cured film is worn. △: The bleached cloth is contaminated, but the cured film is not worn. ×: The bleached cloth is contaminated and the cured film is worn.

(6) Evaluation of abrasion resistance of cured film In the cured film obtained in (3) above, using a Gakken type fastness tester (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.), apply 500 g x 200 times with a bleached cloth. The degree of removal of the cured film from the vinyl chloride resin sheet when the film was rubbed was visually observed and evaluated according to the following criteria.
○: The cured film is not removed. Δ: The surface of the cured film is scratched. ×: The cured film is removed and the vinyl chloride resin sheet is visible.

According to the results shown in Table 1 above, according to Examples 1 to 15 which are the ink compositions for photocurable inkjet printing of the present invention, the integrated light amount of irradiation energy of ultraviolet rays (particularly, ultraviolet rays using LEDs as light sources). It is clear that a cured film can be formed even when the amount of light is small (integrated light quantity is 60 mJ / cm ² ), and the formed cured film has sufficient adhesion, solvent resistance, and abrasion resistance.

  However, in Comparative Examples 1 to 7 that do not satisfy the predetermined amount of acrylamide-based monomer or monomer A, one or more of the curability of the cured film and the solvent resistance of the cured film are poor when the integrated light quantity is small. Became.

Claims (9)

A photocurable inkjet printing ink composition comprising a polymerizable compound and a photopolymerization initiator,
The polymerizable compound has the following general formula (I):
_{^{CH 2 = CR 1 -COOR 2 -O}} -CH = CH-R 3
(In the formula, R ¹ is a hydrogen atom or a methyl group, R ² is a divalent organic residue having 2 to 20 carbon atoms, and R ³ is a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms. A monomer A represented by the following formula: and an acrylamide monomer,
In the polymerizable compound, the ratio of the monomer A is 1 to 90% by mass, the ratio of the acrylamide monomer is 1 to 90% by mass, and the total ratio of the monomer A and the acrylamide monomer is 20% by mass or more. A photocurable ink composition for inkjet printing. The acrylamide monomer is represented by the following general formula (II):
_{^{CH 2 = CR 4 -CON (R}} 5) R 6
(In the formula, R ⁴ is a hydrogen atom or a methyl group. R ⁵ and R ⁶ are the same or different and are a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms. Or R ⁵ and R ⁶ may be bonded to each other to form a ring with an adjacent nitrogen atom.) The photocuring according to claim 1 Ink composition for inkjet printing.   3. The photocurable ink jet printing according to claim 1, wherein the monomer A is one or more of 2- (vinyloxyethoxy) ethyl acrylate and 2- (vinyloxyethoxy) ethyl methacrylate. Ink composition. The photopolymerization initiator contains an acyl phosphine oxide photopolymerization initiator,
The photocurable ink composition for ink jet printing according to any one of claims 1 to 3, wherein the acylphosphine oxide photopolymerization initiator is 2 to 20 parts by mass with respect to 100 parts by mass of the polymerizable compound. object. The photopolymerization initiator contains a thioxanthone photopolymerization initiator,
The said thioxanthone type photoinitiator is a photocurable inkjet printing ink composition in any one of Claims 1-4 which is 10 mass parts or less with respect to 100 mass parts of said polymeric compounds. Furthermore, the ink composition for photocurable inkjet printing in any one of Claims 1-5 containing a coloring agent.   The cured film formed from the ink composition for photocurable inkjet printing in any one of Claims 1-6. An ink jet printing method using the photocurable ink composition for ink jet printing according to any one of claims 1 to 6,
Attaching the photocurable ink composition for inkjet printing to a printing medium;
Irradiating the adhered photocurable ink composition for inkjet printing with ultraviolet rays having an emission peak wavelength in the range of 350 to 420 nm to form a cured film. The inkjet printing method according to claim 8, wherein the irradiation energy of the ultraviolet rays is 100 mJ / cm ² or less.