JP6326925B2 - Radiation curable inkjet composition, radiation curable inkjet composition container, inkjet method, and method for producing radiation curable inkjet composition - Google Patents

Description

  The present invention relates to a radiation curable inkjet composition, a radiation curable inkjet composition container, and an inkjet method.

  Conventionally, various methods have been used as a method of forming an image on a recording medium such as paper based on an image data signal. Among these, the ink jet system is an inexpensive apparatus, and ink is ejected only to a required image portion to form an image directly on a recording medium. Therefore, the ink can be used efficiently, and the running cost is low. Furthermore, the inkjet method is excellent as a recording method because of its low noise.

  In recent years, an ultraviolet curable ink composition for ink jet recording that cures when irradiated with ultraviolet rays in an ink jet recording method in order to form an image having high water resistance, solvent resistance, scratch resistance, etc. on the surface of a recording medium. Things are being used.

  For example, Patent Document 1 discloses an ink container containing an ultraviolet curable ink jet recording ink composition containing a specific vinyl ether group-containing (meth) acrylic acid and a hindered amine compound and having a dissolved oxygen content of 20 ppm. ing.

JP2013-177525A

  However, the ink composition described in Patent Document 1 has not yet been satisfactory in curability and ejection stability.

  Accordingly, an object of the present invention is to provide a radiation curable inkjet composition that is excellent in curability and excellent in ejection stability.

Another object of the present invention is to provide an ink jet container containing the radiation curable ink jet composition and an ink jet method using the radiation curable ink jet composition.
Another object of the present invention is to provide a method for producing a radiation curable inkjet composition having excellent ejection stability and excellent curability.

  The present inventors diligently studied to solve the above problems, and found that the following problems can be solved by the present invention, thereby completing the present invention.

That is, the present invention is as follows.
[1]
It contains a bifunctional or higher functional acylphosphine oxide photopolymerization initiator and a polymerizable compound that are solid at room temperature at a simple substance, and the dissolved oxygen content of the composition is 0 to 8.0 kPa, and is contained in the composition container. Radiation curable ink jet composition.

[2]
The radiation curable inkjet composition according to [1], wherein the content of the photopolymerization initiator with respect to the composition is 1 to 15% by mass.

[3]
The radiation curable inkjet composition according to [1] or [2], which contains a benzene ring-containing (meth) acrylate as the polymerizable compound.

[4]
The radiation curable inkjet composition according to any one of [1] to [3], which contains phenoxyethyl (meth) acrylate as the polymerizable compound.

[5]
When preparing a radiation curable ink jet composition, ultrasonic treatment that emits ultrasonic waves to a mixture obtained by mixing the photopolymerization initiator and at least a part of the polymerizable compound, or heating that heats the mixture The radiation curable inkjet composition according to any one of [1] to [3], which has been subjected to at least one of treatments.

[6]
In the composition container, a container formed of a member having an oxygen permeability of 5.0 cc · 20 μm / (m ² · day · atm) or less is filled with a radiation curable inkjet composition [1 ] The radiation curable inkjet composition in any one of [5].
[7]
The radiation curable inkjet composition according to [5], wherein the treatment is performed by stirring the mixture while performing at least one of irradiation with ultrasonic waves or heating on the mixture.

[8]
The composition container which accommodated the radiation-curable inkjet composition in any one of [1]-[7].

[9]
The inkjet method which discharges the radiation-curable inkjet composition in any one of [1]-[7] from an inkjet head.

[10]
A method for producing a radiation-curable inkjet composition comprising a bifunctional or higher functional acylphosphine oxide photopolymerization initiator and a polymerizable compound that is solid at room temperature at a simple substance,
A method for producing a radiation-curable inkjet composition, wherein the dissolved oxygen content of the composition is 0 to 8.0 kPa.

It is a disassembled perspective view which shows an example of the ink container of this invention. It is a figure which shows an example of the supply means of the inkjet apparatus of this invention, and a discharge means.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. In addition, this invention is not restrict | limited to the following embodiment, A various deformation | transformation can be implemented within the range of the summary.

  In this specification, “curability” refers to a property of curing in response to light. “Storage stability” refers to the property of being stable without precipitation of foreign matter before and after storage of the composition. “Low-temperature storage stability” refers to foreign matter before and after storage, particularly when the composition is stored at low temperatures. It is a stable property without precipitation. “Discharge stability” refers to the property of ejecting a stable composition droplet from a nozzle without clogging the nozzle. “Abrasion resistance” refers to the ability of a cured film to be hardly removed or peeled off when the surface of a cured film to which a composition has been applied and cured is rubbed.

  In the present specification, “(meth) acrylate” means at least one of acrylate and its corresponding methacrylate, “(meth) acryl” means at least one of acrylic and its corresponding methacryl, “(Meth) acryloyl” means at least one of acryloyl and methacryloyl corresponding thereto.

[Radiation curable inkjet composition]
The radiation curable inkjet composition of the present embodiment (hereinafter also simply referred to as an inkjet composition or a composition) is a composition used by being discharged from an inkjet head by an inkjet method. Hereinafter, a radiation curable inkjet ink composition (also simply referred to as an ink composition or an ink) may be described as one embodiment of the radiation curable inkjet composition, but the composition may be a composition other than the ink composition. . Moreover, although it may describe as "ultraviolet ray curable type" as one embodiment of "radiation curable type", in this embodiment, if the composition is a radiation curable composition used by being cured by irradiation with radiation. Well, an ultraviolet curable composition or an ultraviolet curable composition may be read as a radiation curable composition or a radiation curable composition. Examples of radiation include ultraviolet rays, infrared rays, visible rays, and X-rays. As the radiation, ultraviolet rays are preferable because a radiation source is easily available and widely used, and a material suitable for curing by irradiation with ultraviolet rays is easily available and widely used. The inkjet composition in the present embodiment includes a bifunctional or higher functional acylphosphine oxide photopolymerization initiator that is solid as a single substance at room temperature and a polymerizable compound. Hereinafter, additives (components) that are or can be included in the ink jet composition in the present embodiment will be described.

[A bifunctional or higher-functional acylphosphine oxide photopolymerization initiator that is solid at room temperature alone]
The composition of the present embodiment includes a bifunctional or higher-functional acylphosphine oxide (also referred to as acylphosphine oxide) -based photopolymerization initiator that is solid as a single substance at room temperature as a photopolymerization initiator. The term “solid at room temperature and simple substance” means that the photopolymerization initiator is simple substance at 25 ° C. The solid may be a powder, a granule or the like. The acyl group is bifunctional or more, and bifunctional is preferable. Hereinafter, the above photo heavy initiator is also referred to as a specific photo polymerization initiator.

  By including the photopolymerization initiator, the composition is excellent in curability, and in particular, the curability due to the curing process by the UV-LED tends to be further excellent. On the other hand, the photopolymerization initiator tends to have poor solubility in the polymerizable compound described later. Therefore, when obtaining the composition which is excellent in sclerosis | hardenability using the said photoinitiator, embodiment of this invention is needed. The above-mentioned tendency can be said even when compared with a monofunctional acylphosphine oxide photopolymerization initiator (monoacylphosphine oxide photopolymerization initiator).

  The photopolymerization initiator is not particularly limited, and specifically, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis- (2,6-dimethoxybenzoyl) -2,4,4 -Trimethylpentylphosphine oxide etc. are mentioned.

  Although it does not specifically limit as a commercial item of the said photoinitiator, For example, IRGACURE 819 (bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide), IRGACURE1800 (bis- (2,6-dimethoxybenzoyl)) -2,4,4-trimethylpentylphosphine oxide and 1-hydroxy-cyclohexyl-phenyl ketone in a mass ratio of 25:75). The content of the photopolymerization initiator is preferably 1 to 20% by mass, more preferably 15% by mass or less, in terms of further excellent curability and ejection stability with respect to the total mass (100% by mass) of the composition. 13 mass% or less is more preferable, and 10 mass% or less is especially preferable. Moreover, 3 mass% or more is further more preferable, and 5 mass% or more is especially preferable.

(Other photopolymerization initiators)
The ink composition may further contain other photopolymerization initiator. By using ultraviolet rays (UV) among the radiation, the safety is excellent and the cost of the light source lamp can be suppressed. Other photopolymerization initiators are not limited as long as they generate active species such as radicals and cations by light (ultraviolet) energy and initiate polymerization of the polymerizable compound. Or a cationic photopolymerization initiator, and it is preferable to use a radical photopolymerization initiator.

  The above radical photopolymerization initiator is not particularly limited. For example, aromatic ketones, monoacylphosphine oxide compounds, aromatic onium salt compounds, organic peroxides, thio compounds (such as thiophenyl group-containing compounds), α -Aminoalkylphenone compounds, hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon halogen bond, and alkylamine compounds.

  Although it does not specifically limit as radical photopolymerization initiator, For example, acetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, tria Phenylamine, carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4′-dimethoxybenzophenone, 4,4′-diaminobenzophenone, Michler's ketone, benzoinpropyl ether, benzoin ethyl ether, benzyldimethyl ketal, 1- (4- Isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and - like-1-one - methyl-1- [4- (methylthio) phenyl] -2-morpholino.

  Although it does not specifically limit as a commercial item of radical photopolymerization initiator, For example, IRGACURE 651 (2,2-dimethoxy-1,2-diphenylethane-1-one), IRGACURE 184 (1-hydroxy-cyclohexyl-phenyl-) Ketone), DAROCUR 1173 (2-hydroxy-2-methyl-1-phenyl-propan-1-one), IRGACURE 2959 (1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl -1-propan-1-one), IRGACURE 127 (2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propane-1- ON}, IRGACURE 907 (2-methyl-1- (4-methylthiol Nyl) -2-morpholinopropan-1-one), IRGACURE 369 (2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1), IRGACURE 379 (2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone), IRGACURE 784 (bis (η5-2,4-cyclopentadien-1-yl)- Bis (2,6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium), IRGACURE OXE 01 (1.2-octanedione, 1- [4- (phenylthio)-, 2- (O -Benzoyloxime)]), IRGACURE OXE 02 (ethanone, 1- [9-ethyl-6- (2-methylbenzoy) ) -9H-carbazol-3-yl]-, 1- (O-acetyloxime)), IRGACURE 754 (oxyphenylacetic acid, 2- [2-oxo-2-phenylacetoxyethoxy] ethyl ester and oxyphenylacetic acid, 2 -(2-hydroxyethoxy) ethyl ester mixture (above, BASF), Speedcure TPO (above, Lambson), Lucirin TPO, LR8883, LR8970 (above, BASF), and Ubekrill P36 (UCB) Manufactured).

  Although it does not specifically limit as a cationic polymerization initiator, Specifically, a sulfonium salt, an iodonium salt, etc. are mentioned.

  Although it does not specifically limit as a commercial item of a cationic polymerization initiator, Specifically, Irgacure250, Irgacure270, etc. are mentioned.

(Thioxanthone photopolymerization initiator)
Among other photopolymerization initiators, in particular, a thioxanthone photopolymerization initiator excellent in curability, solubility, safety, and cost may be included. The thioxanthone photopolymerization initiator is used to form a print by curing the ink present on the surface of the recording medium by photopolymerization by irradiation with ultraviolet rays, and contains a thioxanthone photopolymerization initiator. The curability of the ink composition can be improved. By using ultraviolet rays (UV) among the radiation, the safety is excellent and the cost of the light source lamp can be suppressed.

  Although it does not specifically limit as a thioxanthone type photoinitiator, Specifically, it is preferable that 1 or more types chosen from the group which consists of thioxanthone, diethyl thioxanthone, isopropyl thioxanthone, and chloro thioxanthone is included. Although not particularly limited, 2,4-diethylthioxanthone is preferable as diethylthioxanthone, 2-isopropylthioxanthone is preferable as isopropylthioxanthone, and 2-chlorothioxanthone is preferable as chlorothioxanthone. An ink composition containing such a thioxanthone photopolymerization initiator tends to be more excellent in curability, storage stability, and ejection stability. Among these, a thioxanthone photopolymerization initiator containing diethyl thioxanthone is preferable. By including diethylthioxanthone, there is a tendency that a wide range of ultraviolet light (UV light) can be converted into active species more efficiently.

  Although it does not specifically limit as a commercial item of a thioxanthone type photoinitiator, Specifically, Speedcure DETX (2, 4- diethyl thioxanthone), Speedcure ITX (2-isopropyl thioxanthone) (above, Lambson company make), KAYACURE, DETX-S (2,4-diethylthioxanthone) (manufactured by Nippon Kayaku Co., Ltd.).

  The content of the thioxanthone photopolymerization initiator is preferably 0.5 to 4% by mass and more preferably 1 to 4% by mass with respect to the total mass (100% by mass) of the ink composition. When the content is 0.5% by mass or more, the curability of the ink tends to be further improved. Moreover, it exists in the tendency for the outstanding discharge stability to be more effectively maintained as content is 4 mass% or less. The thioxanthone photopolymerization initiator is less susceptible to oxygen inhibition, and is preferable in that it can be made into a composition having further excellent curability when used in combination with a bifunctional or higher-functional acylphosphine oxide photopolymerization initiator that is a solid at room temperature. .

  The said photoinitiator may be used individually by 1 type, and may be used in combination of 2 or more type.

  The total content of all photopolymerization initiators is preferably 1 to 20% by mass relative to the total mass (100% by mass) of the ink composition. When the content is within this range, the ultraviolet curing rate can be sufficiently exerted, and the undissolved portion of the photopolymerization initiator and coloring derived from the photopolymerization initiator can be avoided.

(Polymerizable compound)
The composition includes a polymerizable compound. The polymerizable compound can be polymerized at the time of radiation irradiation alone or by the action of a photopolymerization initiator to cure the printed ink composition. The polymerizable compound is not particularly limited, and specifically, a conventionally known polymerizable functional group, particularly a polymerizable functional group having an unsaturated double bond between carbons, monofunctional, bifunctional, and Trifunctional or higher polyfunctional monomers and oligomers can be used. A polymeric compound may be used individually by 1 type, and may be used in combination of 2 or more type. Hereinafter, these polymerizable compounds will be exemplified.

  The monofunctional, bifunctional, and trifunctional or higher polyfunctional monomers are not particularly limited, and examples thereof include unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid, crotonic acid, isocrotonic acid, and maleic acid; Unsaturated carboxylic acid salts; esters, urethanes, amides and anhydrides of the unsaturated carboxylic acids; acrylonitrile, styrene, various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes. Examples of monofunctional, bifunctional, and trifunctional or higher polyfunctional oligomers include, for example, oligomers formed from the above monomers such as linear acrylic oligomers, epoxy (meth) acrylates, oxetane (meth) acrylates, and fats. Group urethane (meth) acrylate, aromatic urethane (meth) acrylate and polyester (meth) acrylate.

  Moreover, an N-vinyl compound may be included as another monofunctional monomer or polyfunctional monomer. The N-vinyl compound is not particularly limited, and examples thereof include N-vinylformamide, N-vinylcarbazole, N-vinylacetamide, N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, and derivatives thereof. Can be mentioned.

  Of the polymerizable compounds, esters of (meth) acrylic acid, that is, (meth) acrylates are preferred.

  Although it does not specifically limit as monofunctional (meth) acrylate, For example, isoamyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, isomyristyl (meta) ) Acrylate, isostearyl (meth) acrylate, 2-ethylhexyl-diglycol (meth) acrylate, 2-hydroxybutyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxydiethylene glycol (meth) acrylate , Methoxypolyethylene glycol (meth) acrylate, methoxypropylene glycol (meth) acrylate, phenoxyethyl (meth) acrylate, tetra Drofurfuryl (meth) acrylate, isobornyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, lactone-modified flexibility (meta ) Acrylate, t-butylcyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and dicyclopentenyloxyethyl (meth) acrylate. Among these, phenoxyethyl (meth) acrylate is preferable.

  The content of the monofunctional (meth) acrylate is preferably 30 to 85% by mass and more preferably 40 to 75% by mass with respect to the total mass (100% by mass) of the ink composition. By setting it as the said preferable range, it exists in the tendency which is excellent with sclerosis | hardenability, initiator solubility, storage stability, and discharge stability.

  Examples of the monofunctional (meth) acrylate include those containing a vinyl ether group. Such monofunctional (meth) acrylates are not particularly limited, and examples thereof include, for example, 2-vinyloxyethyl (meth) acrylate, 3-vinyloxypropyl (meth) acrylate, and 1-methyl-2- (meth) acrylate. Vinyloxyethyl, 2-vinyloxypropyl (meth) acrylate, 4-vinyloxybutyl (meth) acrylate, 1-methyl-3-vinyloxypropyl (meth) acrylate, 1-vinyloxymethylpropyl (meth) acrylate, ( 2-methyl-3-vinyloxypropyl (meth) acrylate, 1,1-dimethyl-2-vinyloxyethyl (meth) acrylate, 3-vinyloxybutyl (meth) acrylate, 1-methyl-2-vinyl (meth) acrylate Loxypropyl, 2-vinyloxybutyl (meth) acrylate, 4-vinyloyl (meth) acrylate Cycyclohexyl, 6-vinyloxyhexyl (meth) acrylate, 4-vinyloxymethylcyclohexylmethyl (meth) acrylate, 3-vinyloxymethylcyclohexylmethyl (meth) acrylate, 2-vinyloxymethyl (meth) acrylate Cyclohexylmethyl, (meth) acrylic acid p-vinyloxymethylphenylmethyl, (meth) acrylic acid m-vinyloxymethylphenylmethyl, (meth) acrylic acid o-vinyloxymethylphenylmethyl, (meth) acrylic acid 2- ( Vinyloxyethoxy) ethyl, 2- (vinyloxyisopropoxy) ethyl (meth) acrylate, 2- (vinyloxyethoxy) propyl (meth) acrylate, 2- (vinyloxyethoxy) isopropyl (meth) acrylate, ( 2-methacrylic acid (meth) acrylic acid Poxy) propyl, 2- (vinyloxyisopropoxy) isopropyl (meth) acrylate, 2- (vinyloxyethoxyethoxy) ethyl (meth) acrylate, 2- (vinyloxyethoxyisopropoxy) ethyl (meth) acrylate, 2- (vinyloxyisopropoxyethoxy) ethyl (meth) acrylate, 2- (vinyloxyisopropoxyisopropoxy) ethyl (meth) acrylate, 2- (vinyloxyethoxyethoxy) propyl (meth) acrylate, (meth ) 2- (vinyloxyethoxyisopropoxy) propyl acrylate, 2- (vinyloxyisopropoxyethoxy) propyl (meth) acrylate, 2- (vinyloxyisopropoxyisopropoxy) propyl (meth) acrylate, (meth) Acrylic acid 2- (vinyloxyethoxyethoxy) Ii) Isopropyl, 2- (vinyloxyethoxyisopropoxy) isopropyl (meth) acrylate, 2- (vinyloxyisopropoxyethoxy) isopropyl (meth) acrylate, 2- (vinyloxyisopropoxyisopropoxy) (meth) acrylate ) Isopropyl, 2- (vinyloxyethoxyethoxyethoxy) ethyl (meth) acrylate, 2- (vinyloxyethoxyethoxyethoxyethoxy) ethyl (meth) acrylate, 2- (isopropenoxyethoxy) ethyl (meth) acrylate , 2- (Isopropenoxyethoxyethoxy) ethyl (meth) acrylate, 2- (Isopropenoxyethoxyethoxyethoxy) ethyl (meth) acrylate, 2- (Isopropenoxyethoxyethoxyethoxyethoxy) acrylate (meth) acrylate ethyl,( Data) Polyethylene glycol monovinyl ether acrylate, and (meth) acrylic acid polypropylene glycol monovinyl ether, phenoxyethyl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate. Among these, 2- (vinyloxyethoxy) ethyl (meth) acrylate, phenoxyethyl (meth) acrylate, isobornyl (meth) acrylate, and benzyl (meth) acrylate are preferable.

  Among these, since the viscosity of the ink can be further lowered, the flash point is high, and the curability of the ink is excellent, 2- (vinyloxyethoxy) ethyl (meth) acrylate, that is, 2- (vinyloxy) acrylate At least one of ethoxy) ethyl and 2- (vinyloxyethoxy) ethyl methacrylate is preferable, and 2- (vinyloxyethoxy) ethyl acrylate is more preferable. Since both 2- (vinyloxyethoxy) ethyl acrylate and 2- (vinyloxyethoxy) ethyl methacrylate have a simple structure and a small molecular weight, the viscosity of the ink 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.

Among the above-mentioned monofunctional (meth) acrylates containing a vinyl ether group, vinyl ether group-containing (meth) acrylic acid esters represented by the following general formula (I) are preferable in terms of the above points.
_{^{CH 2 = CR 1 -COOR 2 -O}} -CH = CH-R 3 ··· (I)
Wherein 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. Group.)

  When the ink composition contains the vinyl ether group-containing monofunctional (meth) acrylic acid esters, the ink curability can be improved, and the ink viscosity can be lowered. In addition, it is better to use a compound having both a vinyl ether group and a (meth) acryl group in one molecule than to use a compound having a vinyl ether group and a compound having a (meth) acryl group separately. It is preferable for improving curability.

In the above general formula (I), the divalent organic residue having 2 to 20 carbon atoms represented by R ² is a linear, branched or cyclic substituted having 2 to 20 carbon atoms. May be an alkylene group, an optionally substituted alkylene group having an oxygen atom by an ether bond and / or an ester bond in the structure, and an optionally substituted divalent alkylene group having 6 to 11 carbon atoms. Aromatic groups are preferred. 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 due to an ether bond in the structure is preferably used.

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 substituted group having 1 to 10 carbon atoms. Suitable alkyl groups and optionally substituted aromatic groups having 6 to 11 carbon atoms are preferred. 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 used suitably.

  When each of the organic residues is an optionally substituted group, the substituent is divided into a group containing a carbon atom and a group not containing a carbon atom. First, when the substituent is a group containing a carbon atom, the carbon atom is counted in the carbon number of the organic residue. Examples of the group containing a carbon atom include, but are not limited to, a carboxyl group and an alkoxy group. Next, examples of the group not containing a carbon atom include, but are not limited to, a hydroxyl group and a halo group.

  The vinyl ether group-containing monofunctional (meth) acrylic acid esters, in particular, the polymerizable compound represented by the general formula (1), among them, the content of 2- (vinyloxyethoxy) ethyl (meth) acrylate is 10-70 mass% is preferable with respect to the total mass (100 mass%) of an ink composition, and 30-50 mass% is more preferable. When the content is 10% by mass or more, the viscosity of the ink can be reduced and the curability of the ink can be further improved. On the other hand, when the content is 70% by mass or less, the storage stability of the ink can be maintained in an excellent state.

  Among the (meth) acrylates, examples of the bifunctional (meth) acrylate include triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, and dipropylene glycol di ( (Meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonane Di (meth) acrylate, neopentyl glycol di (meth) acrylate, dimethylol-tricyclodecane di (meth) acrylate, EO (ethylene oxide) adduct di (meth) acrylate of bisphenol A Bisphenol A PO (propylene oxide) adduct di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol Examples thereof include di (meth) acrylate and trifunctional or higher functional (meth) acrylate having a pentaerythritol skeleton or a dipentaerythritol skeleton. Among these, dipropylene glycol di (meth) acrylate is preferable. Among them, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, pentaerythritol skeleton or dipentaerythritol skeleton having 3 or more functional groups (Meth) acrylate is preferred. More preferably, the ink composition contains polyfunctional (meth) acrylate in addition to monofunctional (meth) acrylate.

  The content of the bifunctional or higher polyfunctional (meth) acrylate is preferably 5 to 60% by mass and preferably 15 to 60% by mass with respect to the total mass (100% by mass) of the ink composition. More preferably, it is 20-50 mass%. By setting it as the said preferable range, it exists in the tendency which is excellent with sclerosis | hardenability, storage stability, and discharge stability.

  Among the above (meth) acrylates, trifunctional or more polyfunctional (meth) acrylates include, for example, trimethylolpropane tri (meth) acrylate, EO-modified trimethylolpropane tri (meth) acrylate, and pentaerythritol tri (meth) acrylate. , Pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, glycerin propoxytri (meth) acrylate, cowprolactone modified trimethylolpropane tri (meth) acrylate, pentaerythritol Examples include ethoxytetra (meth) acrylate and caprolactam-modified dipentaerythritol hexa (meth) acrylate.

  Among these, it is preferable that a polymeric compound contains monofunctional (meth) acrylate. In this case, the ink composition has a low viscosity, is excellent in solubility of the photopolymerization initiator and other additives, and is easy to obtain ejection stability during ink jet recording. Furthermore, since the toughness, heat resistance, and chemical resistance of the coating film are increased, it is more preferable to use a monofunctional (meth) acrylate and a bifunctional (meth) acrylate, and among them, phenoxyethyl (meth) acrylate and dipropylene glycol. It is more preferable to use di (meth) acrylate in combination.

  The composition of the present embodiment is a non-aqueous composition containing the largest amount of the polymerizable compound among medium components in which solid components such as a photopolymerization initiator and a coloring material are dissolved or dispersed. From the viewpoint of stability and storage stability. The medium component having the largest mass ratio among the medium components contained in the composition is a polymerizable compound. The content of the polymerizable compound is preferably 40 to 95 mass%, more preferably 50 mass% or more, still more preferably 60 mass% or more, and 90 mass% or less with respect to the total mass (100 mass%) of the ink composition. Is more preferable, and 80 mass% or less is still more preferable. When the content of the polymerizable compound is within the above range, the viscosity and odor can be further reduced, and the solubility and reactivity of the photopolymerization initiator can be further improved.

[Benzene ring-containing (meth) acrylate]
Among the polymerizable compounds described above, the benzene ring-containing (meth) acrylate (benzene ring-containing (meth) acrylic monomer) is a photopolymerization initiator, particularly the solubility of the specific photopolymerization initiator described above used in the present embodiment. It is preferable in terms of excellent storage stability (especially low-temperature storage stability) and ejection stability of the excellent composition and further excellent curability. A benzene ring-containing (meth) acrylate is a polymerizable compound having an unsubstituted or substituted benzene ring and having a (meth) acryloyl group as a polymerizable functional group. The number of (meth) acryloyl groups is preferably 2 or less, more preferably 1 in that the solubility of the photopolymerization initiator is particularly excellent and the viscosity is low. The number of polymerizable functional groups is preferably 2 or less, and more preferably 1. When the benzene ring is substituted, examples of the substituent include a hydrocarbon group having 1 to 6 carbon atoms, an alkoxy group, and a hydroxyl group. When it is substituted, the number of substitution is 1 to 5, preferably 1 to 3. The substituents may be the same or different. In view of the above effects, no substitution is preferred.

  The number of benzene rings in the molecule is 1 or more, preferably 3 or less, more preferably 2 or less, and even more preferably 1. In the benzene ring-containing (meth) acrylate, the number of carbon atoms in the molecule excluding the (meth) acryloyl group in the molecule is preferably 20 or less, preferably 15 or less, and more preferably 10 or less, from the viewpoint that the above effect is excellent. The lower limit of the carbon number is 6 or more. Examples of benzene ring-containing (meth) acrylate include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate, phenoxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, and the like Can be given. Among the above, phenoxyethyl (meth) acrylate is preferable in that the above effect is particularly excellent. Among the benzene ring-containing (meth) acrylates, a benzene ring-containing acrylate is preferable because the above effect is particularly excellent.

  The content of the benzene ring-containing (meth) acrylate with respect to the composition is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, and more preferably 40% by mass or more from the viewpoint of excellent effects. Is particularly preferred. Moreover, 90 mass% or less is preferable at the point which balances with another component, 80 mass% or less is more preferable, 70 mass% or less is further more preferable, 60 mass% or less is especially preferable, and 50 mass% or less is much more. preferable. Among the benzene ring-containing (meth) acrylates, those having a viscosity at 25 ° C. of 20 mPa · s or less are preferable, and those having a viscosity of 15 mPa · s or less are more preferable. The lower limit of the viscosity is not limited, but may be, for example, 1 mPa · s or more. The viscosity can be measured at a shear rate of 200 using a rheometer MCR-300 manufactured by Anton Paar.

(Polymerization inhibitor)
The ink composition of this embodiment may further contain a hindered amine compound or other substances as a polymerization inhibitor. Other polymerization inhibitors include, but are not limited to, for example, p-methoxyphenol, hydroquinone monomethyl ether (MEHQ), hydroquinone, cresol, t-butylcatechol, 3,5-di-t-butyl-4-hydroxytoluene 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-butylphenol), and 4,4′-thiobis (3-methyl-6-t) -Butylphenol).

  A polymerization inhibitor may be used individually by 1 type, and may be used in combination of 2 or more type. 0.05-0.5 mass% is preferable with respect to the total mass (100 mass%) of a composition, and, as for content of a polymerization inhibitor, 0.1-0.5 mass% is more preferable.

[Color material]
The ink composition may further include a color material. As the color material, at least one of a pigment and a dye can be used.

(Pigment)
By using a pigment as the color material, the light resistance of the ink composition can be improved. As the pigment, both inorganic pigments and organic pigments can be used.

  As the inorganic pigment, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black and channel black, iron oxide, and titanium oxide can be used.

  Organic pigments include insoluble azo pigments, condensed azo pigments, azo lakes and chelate azo pigments, phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc. Polycyclic pigments, dye chelates (eg basic dye chelates, acid dye chelates, etc.), dye rakes (basic dye rakes, acid dye rakes), nitro pigments, nitroso pigments, aniline black, daylight A fluorescent pigment is mentioned.

  More specifically, as a carbon black used for black ink, No. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. 2200B, etc. (Mitsubishi Chemical Corporation), Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Raven 700, etc. (above, Columbia Carbon, Carbon 1 Rubbi 400, Carbon Co. Rega1 330R, Rega1 660R, Mogul L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc. (Cabot Corp. CA Kol. , Color B lack FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color B1ack S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6, Special Black 5, Special Black 4A , Special Black 4 (manufactured by Degussa).

  Examples of pigments used in white ink include C.I. I. Pigment white 6, 18, and 21.

  Examples of pigments used in yellow ink include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, 120, 124, 128, 129, 133, 138, 139, 147, 151, 153, 154, 167, 172, 180.

  Examples of pigments used in magenta ink include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 88, 112, 114, 122, 123, 144, 146, 149, 150, 166, 168 170, 171, 175, 176, 177, 178, 179, 184, 185, 187, 202, 209, 219, 224, 245, or C.I. I. Pigment violet 19, 23, 32, 33, 36, 38, 43, 50.

  Examples of pigments used for cyan ink include C.I. I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15:34, 15: 4, 16, 18, 22, 25, 60, 65, 66, C.I. I. Bat Blue 4, 60.

  Examples of pigments other than magenta, cyan, and yellow include C.I. I. Pigment green 7,10, C.I. I. Pigment brown 3, 5, 25, 26, C.I. I. Pigment orange 1, 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, 63.

  The said pigment may be used individually by 1 type, and may use 2 or more types together.

  When using said pigment, the average particle diameter has preferable 300 nm or less, and 50-200 nm is more preferable. When the average particle diameter is in the above range, the ink composition is more excellent in reliability such as ejection stability and dispersion stability, and an image with excellent image quality can be formed. Here, the average particle diameter in the present specification is measured by a dynamic light scattering method.

(dye)
A dye can be used as the coloring material. The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used. Examples of the dye include C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Red 52, 80, 82, 249, 254, 289, C.I. I. Acid Blue 9, 45, 249, C.I. I. Acid Black 1, 2, 24, 94, C.I. I. Food Black 1, 2, C.I. I. Direct Yellow 1,12,24,33,50,55,58,86,132,142,144,173, C.I. I. Direct Red 1,4,9,80,81,225,227, C.I. I. Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, C.I. I. Directed Black 19, 38, 51, 71, 154, 168, 171, 195, C.I. I. Reactive Red 14, 32, 55, 79, 249, C.I. I. Reactive black 3, 4, and 35 are mentioned.

  The said dye may be used individually by 1 type, and may use 2 or more types together.

  The content of the color material is preferably 1 to 20% by mass with respect to the total mass (100% by mass) of the ink composition because excellent concealability and color reproducibility are obtained. It is good also as a clear composition (clear ink) which does not contain a coloring material or contains a coloring material to such an extent that it does not aim at coloring (for example, 0.1 mass% or less).

[Dispersant]
When the ink composition contains a pigment, it may further contain a dispersant in order to improve pigment dispersibility. Although it does not specifically limit as a dispersing agent, For example, the dispersing agent currently used for preparing pigment dispersion liquids, such as a polymer dispersing agent, is mentioned. Specific examples include polyoxyalkylene polyalkylene polyamines, vinyl polymers and copolymers, acrylic polymers and copolymers, polyesters, polyamides, polyimides, polyurethanes, amino polymers, silicon-containing polymers, sulfur-containing polymers, fluorine-containing polymers, and epoxies. The thing which has 1 or more types of resin as a main component is mentioned. Commercially available polymer dispersants include Ajinomoto Fine Techno's Ajisper series, Solspers series (Solsperse 36000, etc.) available from Avecia and Noveon, and BYK Chemie's Dispersic series. , Disparon series manufactured by Enomoto Kasei.

[Other additives]
The ink composition may contain additives (components) other than the additives listed above. Such components are not particularly limited, and may include, for example, conventionally known slip agents (surfactants), polymerization accelerators, penetration enhancers, wetting agents (humectants), and other additives. Examples of the other additives include conventionally known fixing agents, antifungal agents, preservatives, antioxidants, ultraviolet absorbers, chelating agents, pH adjusting agents, and thickeners.

[Dissolved oxygen content of the composition]
The composition according to the present embodiment has a discharge oxygen and storage stability of the composition (0 to 8.0 kPa) in a state where the composition is contained in a composition container (also simply referred to as a container). This is particularly necessary in terms of low-temperature storage stability. The amount of dissolved oxygen can be measured by the method of Examples described later. The composition may be a composition having a dissolved oxygen amount of 0 to 8.0 kPa at the time when the composition is prepared (when the composition is manufactured).

  The lower limit of the amount of dissolved oxygen in the composition is not limited, but is preferably 1 kPa or more, and more preferably 3 kPa or more. The upper limit is preferably 7 kPa or less, and more preferably 6 kPa or less. When the dissolved oxygen amount is in the above range, the discharge stability and storage stability when discharged from the head are further improved, and the efficiency when preparing the composition is further improved. The amount of dissolved oxygen in the composition can be brought to the above range by performing a treatment described later as a treatment for reducing the amount of dissolved oxygen during preparation of the composition, for example.

  It is preferable that the amount of dissolved oxygen in the composition accommodated in the container is within the predetermined range at least when the composition container is manufactured and shipped. Furthermore, it is more preferable that the period in which the dissolved gas amount is within the predetermined range is from when the ink container containing the ink composition is shipped to when the ink container starts to be used. Further, the dissolved oxygen of the composition may be within the above range when the composition is prepared.

[Production Method of Composition]
Manufacture (preparation) of a composition can be performed by mixing each component contained in the composition and stirring so that the components are sufficiently uniformly mixed. In the present embodiment, the composition is prepared by mixing at least part of a polymerizable compound and a bifunctional or higher-functional acylphosphine oxide-based photopolymerization initiator that is solid at room temperature at a normal temperature in the preparation process. On the other hand, having a step of performing at least one of ultrasonic treatment and heating treatment makes it easy to set the dissolved oxygen content of the prepared composition to 0 to 8.0 kPa, and is excellent in ejection stability and storage stability. It is preferable in that it is easy to make a correction product, and it is more preferable to have a step of performing ultrasonic treatment. The said mixture should just contain said component at least, and may further contain the other component contained in a composition, and may contain all the components contained in a composition. The polymerizable compound included in the mixture may be at least part of the polymerizable compound included in the composition.

[Ultrasonic treatment]
At the time of preparation of the composition, at least a bifunctional or higher-functional acylphosphine oxide photopolymerization initiator (hereinafter also referred to as a specific photopolymerization initiator) that is solid at room temperature and at least a part of the polymerizable compound. Applying ultrasonic treatment to the mixed mixture is easy to make the dissolved oxygen content of the prepared composition 0-8.0 kPa, and it is a corrected product excellent in ejection stability and storage stability. It is preferable in terms of easy. The reason is that the specific photopolymerization initiator has a tendency to have low solubility in the polymerizable compound, and by applying ultrasonic treatment, the fine particles of the photopolymerization initiator are not left, and from the inkjet head. It is presumed that the photopolymerization initiator no longer interferes with the discharge of the photopolymerization or during the storage of the composition. In addition, due to this, bubbles remaining attached to the inside or the surface of the photopolymerization initiator particles are released from the photopolymerization initiator and released into the composition, and the released bubbles are subjected to the composition by ultrasonic vibration. It is estimated that the ejection stability is improved and the dissolved oxygen amount of the composition easily falls within the above range.

  When the ultrasonic treatment is performed, the mixture is subjected to ultrasonic treatment, and the remaining components contained in the composition are further mixed with the mixture after the application to obtain a final composition. This is preferable in that the solubility is further excellent, the dissolved oxygen content of the composition after preparation is easily within the above range, and the remaining components are not subjected to ultrasonic treatment, so that the stability of the composition can be maintained. Examples of the remaining components include the remaining polymerizable compounds and other components, and particularly, components included in the composition in a dispersed state of pigments and the like.

  The treatment time of the ultrasonic treatment is preferably 20 minutes to 200 minutes, and more preferably 30 to 100 minutes, from the viewpoint of obtaining the above effects sufficiently and improving the efficiency of preparation of the composition. Moreover, the output of the ultrasonic wave of an ultrasonic treatment is 400-1000W with the same point, and 400-800W is more preferable. In addition, the frequency of the ultrasonic wave for ultrasonic treatment is preferably 20 to 30 kHz from the same point.

In the ultrasonic treatment, another treatment may be further performed while irradiating ultrasonic waves or before or after the ultrasonic treatment. Other treatments include stirring, heating, vacuum degassing and the like. Moreover, you may perform said other process to what added the remaining component to the mixture which performed the ultrasonic process.
In the ultrasonic treatment, it is assumed that the composition is stirred while irradiating the mixture with ultrasonic waves, and it is possible to emit ultrasonic waves uniformly throughout the mixture, which is the effect of ultrasonic discharge stability. In view of further excellent properties and storage stability. This presumes that the dissolution of the photopolymerization initiator is further promoted. Stirring may be performed at least in a part of the time period for irradiating ultrasonic waves in ultrasonic treatment, and it is preferably performed for 30% or more of the total time period for irradiating ultrasonic waves in view of the above effects. It is more preferable to carry out at% or more. Stirring may be performed using a screw, a stirrer or the like so that almost the entire mixture circulates.

  The ultrasonic treatment can be performed by providing an ultrasonic vibrator in a container or a wall surface containing the composition. GSD150AT (manufactured by Ginsen), GSD300AT (manufactured by Ginsen), GSD600AT (manufactured by Ginsen), GSD1200AT (manufactured by Ginsen), GSD600MCVP-5 (manufactured by Ginsen), GSD600MCVP-10 (manufactured by Ginsen), GSD600MAT-5 ( Ginsen), GSD600MAT-10 (Ginsen), GSD1200MAT-10 (Ginsen), UH-50 (SMT), UH-150 (SMT), UH-300 (SMT), UH-600 (made by SMT), UH-600S (made by SMT), UH-600SR (made by SMT), UH-1200SR (made by SMT), UH-600SR-1 (made by SMT), UH-1200SR -1 (D (MMT), UH-600SR-2 (SMTT), UH-600SR-3 (SMMT), etc. It may be carried out using an ultrasonic cleaner.

[Warming treatment]
When preparing the composition, the mixture similar to the mixture described as the mixture to be subjected to ultrasonic treatment described above may be subjected to a heating treatment for heating instead of or in addition to the ultrasonic treatment. It is presumed that the effect similar to the ultrasonic treatment was obtained by heating the mixture to promote the dissolution of the photopolymerization initiator and eliminating the remaining fine particles of the polymerization initiator. The conditions and method of the heating treatment can be the same as those of the above-described ultrasonic treatment except that they are described here.
Heating is preferably performed at a temperature of 40 ° C. or higher as the temperature of the mixture from the viewpoint of obtaining the above effect, and more preferably 40 to 50 ° C. The treatment time for the heating treatment is preferably 20 minutes to 200 minutes from the viewpoint of sufficiently obtaining the above effects and improving the efficiency of composition preparation. Heating may be performed by directly or indirectly imparting heat generated from the heating element to the composition or irradiating infrared rays or the like. In this embodiment, the heating process for heating is also referred to as a heating process for heating.

The warming treatment may be further performed while warming or before or after warming. Other treatments include stirring, vacuum degassing, and ultrasonic waves. In particular, stirring is preferable as in the case of ultrasonic treatment.
In the heating treatment, it is preferable that the mixture is degassed under pressure while heating the mixture or after heating, from the viewpoint that the above-described effect is more excellent, and the degassing is performed while heating. Is more preferable. It is presumed that vacuum degassing was effective for expelling the bubbles released from the photopolymerization initiator by heating and released into the composition. The vacuum degassing is preferably performed at a reduced pressure of −70 to −90 MPa from the viewpoint of the efficiency of the above effect.

[Composition container]
The composition container of the present embodiment contains an ultraviolet curable inkjet composition. Hereinafter, the ink container may be described as an embodiment of the composition container, but the composition container is not limited to the ink container. Although the aspect of the composition container of this embodiment is not limited to the following, for example, an ink cartridge, a pack, a bottle, a tank, a bottle, and a can are mentioned. Among these, ink cartridges, packs, bottles and tanks are preferred, packs are more preferred, and film packs are particularly preferred because they are widely used and the oxygen permeability described below can be easily controlled to a desired value. Of the parts provided in the container, a part that comes into contact with the composition and is directly filled with the composition is particularly called a container. For example, in the case of a composition container that is an ink cartridge, an ink pack provided inside the ink cartridge is a container. It is good also as a container which a container itself is a container, for example, a container which consists only of a container. For example, a bottle.

  As a usage mode of the ink container of the present embodiment, (A) a form separate from the recording apparatus, such as an ink cartridge that is attached to the recording apparatus and sequentially supplies ink to the recording apparatus, and (B) recording. The apparatus is separate from the apparatus, and when ink is used, at least the ink is transferred from the ink container such as a bottle to the recording apparatus, and (C) the form of a tank or the like that is provided in the recording apparatus in advance and stores the ink is at least Can be mentioned.

The above (A) and (B) can be said to be ink containers from when the ink containers are shipped to just before the ink is supplied (transferred) to the recording apparatus. The above (C) can be said to be an ink container from when the recording apparatus is shipped to before the first use of ink in the recording apparatus is started.
Note that the above (A) and (C) can be referred to as an ink container that performs printing on the recording apparatus in a state where ink is supplied from the ink container to the recording apparatus via a connecting portion such as an ink tube. it can.

  The above (B) can be said to be an ink container that performs printing with the recording apparatus after ink is transferred from the ink container to the recording apparatus. In addition, as the target to which the ink is transferred in (B), a tank or the like provided in the recording apparatus can be cited.

  Further, the constituent materials of the members constituting the container are not limited to the following. For example, plastics such as polyethylene terephthalate (PET) and polypropylene (PP), various metals (including alloys), polyethylene, and ethylene acetate Examples thereof include vinyl copolymers and polyolefins such as polypropylene. Further, the present invention is not limited thereto, and a polymer obtained by blending or laminating each of the above polymers at an appropriate ratio, a film thereof, or the like may be used. The member is preferably a film in terms of weight reduction and flexibility of the container.

Oxygen permeability of members constituting the container is preferably ^{5.0cc · 20μm / (m 2 ·} day · atm) or ^{less, 3.0cc · 20μm / (m 2} · day · atm) or less are preferred, 2.0 cc 20 μm / (m ² · day · atm) or less is preferable, 1.0 cc · 20 μm / (m ² · day · atm) or less is preferable, and 0.5 cc · 20 μm / (m ² · day · atm) or less is more preferable More preferred. The lower limit is not limited and can be 0.0 cc · 20 μm / (m ² · day · atm) or more. When the oxygen permeability is in the above range, the amount of dissolved oxygen in the ink composition of the container is unlikely to increase during storage, and the ejection stability during use can be further improved.

  The constituent material or member is not particularly limited. In the case of an ink pack, the film can be heat-sealed (heat sealed) and processed into a bag shape. Examples of the film used for the ink pack include high-density, low-density, or linear low-density polyethylene, polypropylene, an ethylene-vinyl alcohol copolymer, and stretched plastic films such as polystyrene. Among them, ethylene-vinyl alcohol copolymer (EVOH), polyethylene terephthalate (PET), polypropylene (PP), and polyethylene (PE) are preferable because the gas permeability is easily within a preferable range and the durability of the film is excellent.

  The film may be a laminated film in which a plurality of layers are laminated. When the gas permeability is obtained with the above film, the film may be composed of only the film, or the gas permeability layer may be laminated on the above film to ensure the oxygen permeability and the nitrogen permeability. The gas barrier layer may be a metal layer such as an aluminum layer, an inorganic oxide layer such as a silicon oxide or aluminum oxide layer, or an ethylene-vinyl alcohol copolymer having a low gas permeability among the above films, polyvinyl. Alcohol or the like may be laminated. The total film thickness of the film is preferably 50 μm or more, more preferably 70 μm or more, preferably 200 μm or less, and more preferably 150 μm or less. When the film thickness is above, the amount of dissolved gas in the ink composition being stored hardly changes, and the strength and flexibility of the pack can be obtained. Among these, a film made of an ethylene-vinyl alcohol copolymer is preferable in terms of low gas permeability and excellent strength. In addition, in the case of a container other than a pack, in addition to the above, other synthetic resins, glass, metal, and the like can be given.

In this embodiment, the oxygen permeability of the member is expressed in units of cc · 20 μm / (m ² · day · atm), and the “atm” is 20 ° C. and dry gas (relative humidity 0%). The pressure (atm). In addition, the oxygen permeability was determined by the method defined in ISO 14663-2: 1999 (Annex C), that is, the oxygen permeation rate permeating the film using a coulometric sensor (relative humidity reached an equilibrium state). Sometimes it can be calculated by measuring.

  0.1-5L is preferable and, as for the accommodation volume of the composition of a container, 0.5-4L is more preferable.

  In this embodiment, it is preferable that the expiration date of a container is 20 months or less, and it is more preferable that it is 15 months or less. The expiration date of the container is the time designated by the manufacturer / seller of the container as the time until the expiration date when the container can be used after the container is manufactured and shipped. The lower limit of the expiration date is not limited, but is preferably 5 months or longer, more preferably 10 months or longer. When the expiration date is within the above range, it is more preferable in terms of storage stability, ejection stability, and deaeration efficiency, and further, the expiration date of the container can be reduced.

  Here, an ink cartridge which is an example of the ink container of the present embodiment will be described. FIG. 1 is an exploded perspective view showing the ink cartridge 40. The ink cartridge 40 includes an ink pack 70 that is a container filled with ink, and a cartridge case 72 that includes a main body case 76 that protects the ink pack 70 by being stored therein, and a lid portion 78. The ink pack 70 has an ink supply port. 74, the main body case 76 includes a flange portion 84, a notch portion 80, and a pressing portion 82. The material of the ink pack 70 can use the above-mentioned materials.

[Inkjet device]
The ink jet apparatus of the present embodiment discharges a radiation curable ink jet composition from a composition container to an ink jet head (head) via a flow path, and discharges an ultraviolet curable ink jet composition from the ink jet head. The discharge means to perform is provided. You may provide the deaeration means which deaerates an ultraviolet curable inkjet composition in the flow path between a composition container and an inkjet head.
In the present embodiment, an ink jet recording apparatus or an ink jet printer is also described as one embodiment of the ink jet apparatus, but the ink jet apparatus may be an ink jet apparatus other than the recording apparatus or the printer. In addition to the ejection unit, the ink jet apparatus can also include a curing unit that cures the ejected composition by ultraviolet irradiation.

[Discharging means, feeding means]
The ink jet apparatus ejects the ultraviolet curable ink composition for ink jet recording from a head. Hereinafter, although it demonstrates concretely using drawing, a discharge means is not restricted to the following. FIG. 2 is a schematic view showing an example of the periphery of the head of the ink jet recording apparatus of the present embodiment. The sub tank 200 is supplied with ink from an ink cartridge (not shown), and passes through a deaeration module 204, which is an example of a deaeration mechanism, and a heater 220 in order by a pressure pump 202. 100.

  A head 100, which is a specific example of the ejection means, ejects ink onto a recording medium (not shown). The pressure adjusting valve 108 is opened by a valve opening actuator 320 to adjust the pressure of ink when supplying ink from the sub tank 200 to the head 100.

  The ink that has passed through the deaeration module 204 flows into the branch joint 106 when the pressure adjustment valve 108 is opened. Inside the branch joint 106, the forward path 214 is branched into a plurality of passages and connected to the plurality of heads 100.

  The ink that has not been ejected from the head 100 is circulated to the sub tank 200 via the integrated joint 210 and the return path 216 in a state where the opening / closing valve 212 is open. By circulating the ink between the sub tank 200 and the head 100, when the ink stays for a long time and the ink components are separated and settled, it can be recovered or the temperature of the circulating ink can be made constant. . When the ink is heated by the heaters 218, 220, and 222, the viscosity decreases, the viscosity becomes suitable for ejection from the head 100, and the ink is ejected from the head 100.

These devices are provided in the main scanning movement table 64, and main scanning is performed to eject ink from the head 100 to the recording medium while moving with respect to the recording medium together with the main scanning movement table 64.
The feeding unit is a device that feeds the composition from the composition container to the discharge unit. A path through which the composition from the composition container to the discharge means is fed is called a flow path. As the flow path, the ink path from the ink cartridge to the sub tank 200 in FIG. 2, the sub tank 200, the path from the sub tank 200 to the head 100, the path until the ink is ejected from the nozzle of the head inside the head 100, the head An example of the circulation path is that ink is returned from 100 to the subtank 200 and ink can be fed from the subtank 200 to the head 100 again.

[Deaeration means]
The ink jet apparatus according to the present embodiment may include a deaeration unit (also referred to as a deaeration mechanism). In the case where it is provided, the ejection stability can be improved by performing deaeration of removing gas such as bubbles and oxygen from the composition in the ink jet apparatus. Before supplying to the head 100, bubbles or oxygen may enter the composition during long-term storage of the composition container or in the feeding means via the ink pack or the feeding means member, In view of the above, it is preferable to provide deaeration means. Hereinafter, a deaeration module will be described as an embodiment of the deaeration means. In the deaeration module 204 of FIG. 2, a deaeration chamber (not shown) into which ink flows and a decompression chamber (in contact with the deaeration chamber through a separation membrane that does not allow a liquid such as ink to pass through such as air). (Not shown). A hollow fiber membrane or the like can be used as the separation membrane. When the decompression chamber is depressurized by a decompression pump (not shown), bubbles such as bubbles mixed in the ink in the deaeration chamber and gases dissolved in the ink are released. Ink having a dissolved oxygen concentration lower than that of the ink sent to the module 204 can be supplied to the head 100 and discharged from the head 100. The deaeration module 204 of the recording apparatus can continuously deaerate ink while supplying ink from the sub tank 200 to the head 100. The deaeration means is preferably provided between the ink container and the ink path of the head from the viewpoint of deaeration efficiency. The degassing means is preferably a vacuum degassing means having pressure reducing means such as a pump from the viewpoint of degassing efficiency.

  The above recording apparatus can be configured as shown in FIG. 4 (FIG. 2 of the present specification) of Japanese Patent Application Laid-Open No. 2011-240565, for example. Note that the above-described apparatus may be configured as a line printer in which ink is ejected from the head toward the recording medium while the recording medium moves relative to the head without moving the apparatus. This embodiment is particularly useful because of the large amount of use. Further, instead of the degassing module continuously degassing the ink as described above, the pressure adjusting valve is closed without providing the separation membrane, and the pressure reducing chamber is depressurized to reduce the ink. And when the deaeration is completed, the decompression chamber is returned to the normal pressure and the pressure adjusting valve 108 is opened to supply the ink to the head alternately. Also good. The former is preferable in that the ink can be continuously deaerated, and the latter is preferable in that the deaeration ability is high.

  It is preferable that the composition is degassed by a degassing means and the dissolved oxygen content is lower than the dissolved oxygen content of the composition before degassing from the viewpoint of further improving the discharge stability. The dissolved oxygen content of the composition deaerated by the deaeration means is preferably 8.0 kPa or less from the viewpoint that the discharge stability can be further improved. The amount of dissolved oxygen in the degassed composition is more preferably 6.0 kPa or less, and the lower limit is not limited, but is preferably 0.1 kPa or more, more preferably 1 kPa or more in terms of degassing efficiency, and 2 kPa or more. Is more preferable. When the amount of dissolved oxygen in the degassed composition is within the above range, the discharge stability is further improved. In the present embodiment, the deaeration efficiency can be indicated by, for example, the deaeration time necessary for performing the deaeration, and the shorter the deaeration time, the better the deaeration efficiency. In order to bring the dissolved gas amount of the degassed composition into the above range, for example, the degree of degassing of the composition by the degassing means may be adjusted. For example, in the case of the above degassing module, the degassing module is depressurized. The degree of deaeration of the chamber may be adjusted, or the flow rate of the composition flowing through the deaeration module may be adjusted.

  When the amount of dissolved oxygen in the composition contained in the container is in the above range and the amount of dissolved gas in the composition deaerated by the degassing means is in the above range, the storage stability of the composition, It is more preferable in terms of excellent discharge stability and deaeration efficiency.

[Discharge target]
The composition is used by, for example, ejecting the ink composition onto a target to be ejected using an inkjet method. Although a recording medium is described as an embodiment of an ejection target, the ejection target is not limited to a recording medium. Examples of the recording medium include an absorptive or non-absorptive recording medium. The following inkjet recording methods are widely used for recording media having various absorption performances, from non-absorbing recording media that are difficult to penetrate water-soluble ink compositions to absorbent recording media that are easy to penetrate ink compositions. Applicable. However, when the ink composition is applied to a non-absorbable recording medium, it may be necessary to provide a drying step after being cured by irradiation with ultraviolet rays.

  The absorbent recording medium is not particularly limited. For example, plain paper such as electrophotographic paper having high ink permeability, ink jet paper (an ink absorbing layer composed of silica particles or alumina particles, or polyvinyl alcohol ( Art paper, coated paper, etc. used for general offset printing with relatively low ink permeability, such as PVA) and polyvinyl pyrrolidone (PVP). Examples include cast paper.

  The non-absorbable recording medium is not particularly limited. For example, films and plates of plastics such as polyvinyl chloride, polyethylene, polypropylene, and polyethylene terephthalate (PET), and metals such as iron, silver, copper, and aluminum are used. Examples thereof include a plate, a metal plate produced by vapor deposition of these various metals, a plastic film, a plate made of an alloy such as stainless steel or brass.

[Inkjet method]
The ink jet method using the ultraviolet curable ink jet composition accommodated in the container according to the present embodiment includes a discharge step of discharging the composition to the discharge target by the ink jet method, and the composition discharged by the discharge step. And a curing step of curing the composition by irradiating with ultraviolet rays. In this way, a cured product is formed by the composition cured by the discharge target. Examples of the ink jet method include an ink jet recording method, an ink jet molding method, and the like, and any material that discharges a composition by the ink jet method may be used. Hereinafter, an inkjet recording method will be described as an embodiment of the inkjet method.

[Discharge process]
In the ejection step, an ink jet recording apparatus described later can be used. When discharging the ink composition, the viscosity of the ink composition is preferably 25 mPa · s or less, more preferably 5 to 20 mPa · s. If the viscosity of the ink composition is as described above with the temperature of the ink composition set to room temperature or without heating the ink composition, the temperature of the ink composition is set to room temperature or the ink composition is not heated. Can be discharged. On the other hand, the ink composition may be discharged to a preferable viscosity by heating to a predetermined temperature. In this way, good discharge stability is realized.

  Since the ultraviolet curable ink composition has a higher viscosity than the water-based ink composition used in a normal inkjet ink, the viscosity fluctuation due to temperature fluctuation at the time of ejection is large. Such fluctuations in the viscosity of the ink have a great influence on the change in the droplet size and the change in the droplet discharge speed, which can cause image quality deterioration. Therefore, it is preferable to keep the temperature of the ink during ejection as constant as possible.

[Curing process]
Next, in the curing step, the ink composition ejected on the recording medium is cured by irradiation with ultraviolet rays (light). In other words, the ink coating film formed on the recording medium becomes a cured film when irradiated with ultraviolet rays. This is because the photopolymerization initiator that can be contained in the ink composition is decomposed by irradiation with ultraviolet rays to generate radicals, acids, bases, and other starting species, and the polymerization reaction of the photopolymerizable compound is the starting species. This is because it is promoted by function. Or it is because the photopolymerization reaction of a polymeric compound starts by irradiation of an ultraviolet-ray. At this time, if a sensitizing dye is present together with the photopolymerization initiator in the ink composition, the sensitizing dye in the system absorbs actinic radiation to be in an excited state and comes into contact with the photopolymerization initiator. Degradation can be accelerated and a more sensitive curing reaction can be achieved.

  Mercury lamps and gas / solid lasers are mainly used as ultraviolet sources, and mercury lamps and metal halide lamps are widely known as light sources used for curing ink compositions for ultraviolet curable ink jet recording. Yes. On the other hand, there is a strong demand for mercury-free from the viewpoint of environmental protection, and replacement with a GaN-based semiconductor ultraviolet light-emitting device is very useful industrially and environmentally. Furthermore, an ultraviolet light emitting diode (UV-LED) and an ultraviolet laser diode (UV-LD) are small, have a long lifetime, high efficiency, and low cost, and are expected as light sources for ultraviolet curable ink jets. Among these, UV-LED is preferable.

Here, it is preferable to use an ink composition that can be cured by irradiating ultraviolet rays having an emission peak wavelength of preferably 365 to 405 nm, more preferably 380 to 400 nm. The irradiation energy is preferably 50~1000mJ / cm ^2, more preferably 100~700mJ / cm ^2, more preferably 200 to 600 mJ / cm ^2.

In the above case, curing at low energy and high speed is possible due to the composition of the ink composition. The irradiation energy is calculated by multiplying the irradiation time by the irradiation intensity. The irradiation time can be shortened by the composition of the ink composition, and in this case, the printing speed is increased. On the other hand, the irradiation intensity can be reduced by the composition of the ink composition in the present embodiment. In this case, UV-LED is preferably used for ultraviolet irradiation. Such an ink composition can be obtained by including a photopolymerization initiator that is decomposed by irradiation with ultraviolet rays in the above wavelength range and a polymerizable compound that initiates polymerization by irradiation with ultraviolet rays in the above wavelength range. The emission peak wavelength may be one or plural within the above wavelength range. Even in the case where there are a plurality, the total irradiation energy of the ultraviolet rays having the emission peak wavelength is set as the irradiation energy.
The ink jet method according to the present embodiment further includes composition feeding (feeding step) performed by the above-described feeding unit and degassing (degassing step) of the composition performed by the above-described degassing unit. Also good.

  Hereinafter, the embodiments of the present invention will be described more specifically by way of examples. However, the present invention is not limited to these examples.

[Raw materials]
The raw materials used in the following examples and comparative examples are as follows.
(Polymerizable compound)
VEEA (2- (2-vinyloxyethoxy) ethyl acrylate, trade name of Nippon Shokubai Co., Ltd., abbreviated as “VEEA” in the table below)
SR508 (dipropylene glycol diacrylate, trade name of Sartomer, abbreviated as “DPGDA” in the table below)
Light acrylate PO-A (phenoxyethyl acrylate, trade name of Kyoeisha Chemical Co., Ltd., abbreviated as “PEA” in the table below)
Biscoat # 150 (tetrahydrofurfuryl acrylate, Osaka Organic Chemical Industry, abbreviated as “THFA” in the table below)

・ P. I. Pigment Blue 15: 4 (manufactured by Dainichi Seika Co., Ltd., cyan pigment)
・ Solsperse 36000 (manufactured by Lubrizol, pigment dispersant)
Methoxyhydroquinone (polymerization inhibitor, manufactured by Tokyo Chemical Industry Co., Ltd., abbreviated as MEHQ in the table below)

(Photopolymerization initiator)
Irgacure 819 (Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, trade name, manufactured by BASF, solid content 100%)
KAYACURE DETX (2,4-diethylthioxanthone, solid content 100%)
Irgacure 369 (2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, trade name, manufactured by BASF, solid content 100%)

[Preparation of ink composition for ultraviolet curable ink jet recording]
An ultraviolet curable inkjet ink composition, which is a radiation curable inkjet composition, was prepared using the components described in the following table so as to have each composition ratio (unit: mass%) described in the table. Example 1 will be specifically described as an example. First, VEEA of a pigment, a pigment dispersant, and a polymerizable compound was weighed so that the mass ratio thereof was the mass ratio of Example 1 in each composition in the table, and placed in a tank for dispersing pigment, and the tank had a diameter of 1 mm. Then, the ceramic bead mill was added and stirred to disperse the pigment in the polymerizable compound. Thus, a pigment dispersion was prepared. Next, separately from the above-mentioned pigment dispersion, a mixture tank that is a stainless steel container is prepared, and components other than those already used in the pigment dispersion among the components used in Example 1 are displayed. And an amount that gives a total mass of the mixture of 20 kg. The tank was equipped with a screw to allow stirring of the mixture in the tank. Furthermore, an ultrasonic transducer was provided in the tank, and ultrasonic waves could be emitted to the mixture in the tank. Further, a heater made of a heating element was attached to the wall of the tank so that the mixture in the tank could be heated. In addition, the tank can be sealed with a lid, and the inside of the tank can be degassed with a vacuum pump.

First, each component placed in the tank with a screw was stirred to obtain a mixture. Next, the ultrasonic vibrator was operated to emit ultrasonic waves at a frequency of 25 kHz to the mixture. The time (minutes) of ultrasonic radiation and the output (wattage) of ultrasonic waves were the conditions described in Example 1 in the table. The screw was rotated so that the entire mixture in the tank circulated during the entire time of radiating ultrasonic waves. The heater was not operated and the mixture was not heated, and the vacuum pump was not operated and vacuum degassing was not performed on the mixture. In this way, the mixture was sonicated. In the tank for preparing the composition, the mixture of the pigment dispersion prepared above and the ultrasonic treatment is weighed in an amount corresponding to the composition ratio of Example 1, and mixed well by stirring with a screw. The final composition of Example 1 was obtained. The prepared composition was filled in a pack made of an ethylene-vinyl alcohol copolymer film having a thickness of 110 μm to form an ink pack. The oxygen permeability of the film was 1.5 cc · 20 μm / (m ² · day · atm). The ink pack was stored in a protective case.

A composition was prepared for each example at a mass ratio of the composition of each example. Examples 3 to 6, 8 and Comparative Examples 1, 2, and 4 are compositions according to Example 1 except that the composition is the composition described in the table and the ultrasonic treatment is performed under the conditions described in the table. It was created. Example 7 was performed in the same manner as Example 1 except that the screw was stopped and stirring was not performed when ultrasonic waves were emitted. In Example 2, instead of emitting ultrasonic waves, the tank heater was operated to warm the mixture in the tank to 45 ° C., and during the heating treatment, stirring was performed in the same manner as in Example 1. The vacuum pump was operated to degas the inside of the tank to -80 MPa.
In Comparative Example 3, the operation of the ultrasonic vibrator was stopped (OFF) with respect to the mixture, the ultrasonic wave was not emitted, the heater was stopped and the heating was not performed, and the mixture was stirred for the time indicated in the table. Except that, the same procedure as in Example 1 was performed. In addition, it is estimated that the dissolved oxygen amount of the comparative example 3 is a saturated dissolved oxygen amount of the composition.
Each composition thus prepared was evaluated as follows. The results are listed in the table below.

[Measurement of dissolved oxygen content]
Immediately after completion of the preparation, the composition was collected from the composition preparation tank, and the dissolved oxygen content of the composition was measured. The dissolved oxygen amount is measured using a dissolved oxygen system (DO meter, 3660EX, manufactured by Hack Ultra) at a temperature of the composition of 25 ° C., and the value after 5 minutes from putting the sensor of the DO meter into the composition. It was measured. The unit of the dissolved oxygen amount is kPa. The DO system is a polarographic method and is preferable to the chromatographic method in that rapid measurement is possible and dissolved oxygen can be confirmed in a short time in the preparation of the composition. The above dissolved oxygen meter is also preferable in terms of high measurement accuracy, and is particularly preferable in terms of high measurement accuracy because it can detect the liquid temperature and perform temperature compensation based on the liquid temperature.

[Low temperature storage stability]
The prepared composition was put in a glass bottle and sealed, and stored at −20 ° C. for 4 days. The ink after storage was filtered with a filter paper (Advantech No. 5A), and foreign matters remaining on the filter paper were visually observed. The storage period was confirmed in the same manner by increasing the storage period by 4 days or more by 1 day. The evaluation criteria were as follows. The confirmed foreign matter was a precipitate resulting from the photopolymerization initiator.
A: No deposit foreign matter after 7 days of storage.
B: Precipitated foreign matter was not found after storage for 4-6 days.
C: Precipitated foreign matter is present after storage for 4 days.

[Recording test]
An ink jet apparatus including a feeding unit, a deaeration unit, and a discharge unit as shown in FIG. 2 was prepared. However, the table 64 is fixed, and a recording medium transport mechanism (not shown) is provided to constitute a line printer that discharges ink to the recording medium while transporting the recording medium to the table 64. The head 100 of the discharge means has a discharge nozzle diameter of 20 μm, a discharge drive frequency of 15 kHz, an ink discharge amount per time adjusted to 7 ng, and 360 nozzles per head. Such an ink jet evaluation machine (prototype) was prepared. The ink prepared above was used as a composition in an ink pack. In each case, the ink pack was connected to the ink path to the sub tank 200, and ink was supplied from the ink pack to the sub tank. Ink was supplied from the ink cartridge to the sub tank so that the amount of ink in the sub tank always exceeded a predetermined amount. When the ink in the ink cartridge was finished, it was replaced with an ink cartridge prepared under the same conditions for each example, and the supply of ink to the sub tank was continued. Each ink feeding means was operated to feed ink to the head 100. The deaeration module is for degassing the ink through a hollow membrane, and the ink can be deaerated while feeding the ink. By supplying the ink to the head 100 while deaeration, the air bubbles mixed in the ink in the ink supply path were removed. One of the heads 100 was used for the recording test so that ink was not fed to the other heads. When the ink supplied into the head 100 was collected and the amount of dissolved oxygen was measured by the same method as described above, all of the examples were 8 kPa or less. The heater was operated and the ink temperature was adjusted so that the ink viscosity was suitable for ejection (10 mPa · s or less). And the ink was discharged using the said evaluation machine.

(Discharge stability)
Continuous discharge was performed from the above one head (360 nozzles) at the above discharge frequency. Every 5 minutes, it was inspected whether or not ink was ejected from all the nozzles, and continuous ejection was performed up to a total of 50 minutes. The evaluation criteria were as follows.
A: No discharge nozzle in 50 minutes.
B: No discharge nozzle in 20 to 50 minutes.
C: No discharge nozzle in 15 minutes or less.

[Curing property test]
An amount of ink having a film thickness of 8 μm (film thickness after curing) was applied to the substrate, and the curing energy required for curing was confirmed. It was judged whether it hardened | cured from the states, such as rubbing with a cotton swab. For irradiation, an LED having a peak wavelength at 395 nm and an irradiation intensity of 1100 mW / cm ² were used. A PET film (PET50A PL Thin [trade name], manufactured by Lintec Corporation) was used as the substrate. The irradiated coating film (composition film) was rubbed 10 times with a cotton swab at a load of 100 g, and the curing energy (irradiation energy) at the time when no damage was found was determined.
The irradiation energy [mJ / cm ² ] was determined from the product of the irradiation intensity [mW / cm ² ] on the irradiated surface irradiated from the light source and the irradiation duration [s]. The irradiation intensity was measured using an ultraviolet intensity meter UM-10 and a light receiving unit UM-400 (both manufactured by Konica Minolta Sensing, Inc.). Evaluation was made based on the following criteria from the curing energy.
A: 200 mJ / cm ² or less B: More than 200 mJ / cm ² 300 mJ / cm ² or less C: More than 300 mJ / cm ²

[Abrasion resistance test]
A cured film was prepared by irradiating and curing until the point at which the scratch disappeared under the same conditions as in the evaluation of curability. In accordance with JIS K5701 (ISO 11628) (specifying methods for testing inks, color developed samples, and printed materials used for lithographic printing), the Gakushin friction fastness tester (TESTER SANGYO CO., LTD.) Was used to evaluate the abrasion resistance of the coating film. In the evaluation method, a gold width was placed on the surface of the cured film having a coating thickness of 8 μm, and rubbed with a load of 500 g. After peeling, the peeling of the cured film was visually evaluated. The evaluation criteria are as follows.
A: There is no dirt on the gold width, and there is no peeling or scratching of the recording surface.
B: The gold width is dirty, and the recording surface is not peeled or scratched.
C: The gold width was dirty, and the recording surface was peeled or scratched.

From the above results, the composition contains a bifunctional or higher-functional acylphosphine oxide photopolymerization initiator and a polymerizable compound that are solid at room temperature at a single substance, and the dissolved oxygen content of the composition is 0 to 8.0 kPa. Examples 1 to 8 as radiation curable inkjet compositions contained in a container are compositions excellent in ejection stability and curability, and may also be excellent in low temperature storage stability and abrasion resistance. understood. On the other hand, the composition of the comparative example was inferior in at least one of ejection stability and curability. In addition, since there is a correlation between an example with poor low-temperature storage stability and an example with poor discharge stability, a composition with poor low-temperature storage stability tends to be a foreign substance in the photopolymerization initiator, and the temperature is low Not limited to this, it is presumed that there was some effect of lowering the ejection stability while the composition was used for a long time.
In Comparative Examples 1 and 3, the dissolved oxygen content of the composition was 10.0 kPa, and the discharge stability was poor. Comparative Examples 2 and 4 were inferior in curability. Although not described in the table, apart from Comparative Example 4, except that the treatment was performed under the same conditions as Comparative Example 3 as the treatment conditions for the mixture in the preparation of the composition in Comparative Example 4. When confirmed separately in the same manner as in Comparative Example 4, the low-temperature storage stability was A, but the curability was C as in Comparative Example 4. From this, it was found that the invention of the present application is required when a composition having excellent effectiveness by containing a bifunctional or higher functional acylphosphine oxide photopolymerization initiator that is solid at room temperature at a single substance.

  40 ... ink cartridge, 70 ... ink pack, 72 ... cartridge case, 74 ... ink supply port, 76 ... main body case, 78 ... lid part, 80 ... notch part, 82 ... pressing part, 84 ... collar part, 64 ... main Scanning movement table, 100 ... head, 106 ... branch joint, 108 ... pressure regulating valve, 200 ... sub tank, 202 ... pressure pump, 204 ... deaeration module, 210 ... integrated joint, 212 ... open / close valve, 214 ... outward path, 216 ... return path, 218, 220, 222 ... heater, 320 ... valve opening actuator.

Claims (15)

It contains a bifunctional or higher functional acylphosphine oxide photopolymerization initiator and a polymerizable compound that are solid at room temperature at a simple substance, and the dissolved oxygen content of the composition is 0 to 8.0 kPa, and is contained in the composition container. ,
A radiation curable type, which is obtained by subjecting a mixture obtained by mixing the photopolymerization initiator and at least a part of the polymerizable compound to an ultrasonic treatment in the preparation of a radiation curable inkjet composition. Inkjet composition.   The radiation-curable inkjet composition according to claim 1, wherein the content of the photopolymerization initiator with respect to the composition is 1 to 15% by mass.   The radiation curable inkjet composition according to claim 1 or 2, comprising a benzene ring-containing (meth) acrylate as the polymerizable compound.   The radiation-curable inkjet composition according to any one of claims 1 to 3, comprising phenoxyethyl (meth) acrylate as the polymerizable compound. The radiation curable inkjet composition according to any one of claims 1 to 4 , comprising a pigment . The said composition container is what filled the radiation curable inkjet composition in the container comprised by the member whose oxygen permeability is 5.0 cc * 20 micrometer / (m < ² > * day * atm) or less. The radiation curable inkjet composition according to any one of 1 to 5. The radiation curable ink jet composition according to claim 5, wherein the treatment stirs the mixture while performing ultrasonic irradiation on the mixture.   The radiation curable inkjet composition according to any one of claims 1 to 7, which is a non-aqueous composition having a content of 60% by mass or more based on the total mass of the composition of the polymerizable compound.   The radiation-curable inkjet composition according to any one of claims 1 to 8, wherein the dissolved oxygen content of the composition is 6.0 to 8.0 kPa.   The radiation-curable inkjet composition according to any one of claims 1 to 9, wherein the polymerizable compound contains a benzene ring-containing (meth) acrylate in an amount of 30% by mass or more based on the composition. The radiation curable inkjet composition according to any one of claims 1 to 10, wherein a treatment time of the ultrasonic treatment is 20 to 200 minutes.   The composition container which accommodated the radiation-curable inkjet composition as described in any one of Claims 1-11.   The inkjet method which discharges the radiation-curable inkjet composition as described in any one of Claims 1-12 from an inkjet head. It is a manufacturing method of the radiation-curable inkjet composition as described in any one of Claims 1-11, Comprising: An ultrasonic wave is radiated to the mixture which mixed the said photoinitiator and at least one part of the said polymeric compound. A method for producing a radiation curable inkjet composition, comprising a step of performing ultrasonic treatment. The manufacturing method of the radiation-curable inkjet composition of Claim 14 which has the process of mixing the remaining component which a radiation-curable inkjet composition contains in the mixture which performed the said ultrasonic treatment.

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