JP2008266548A - Photocurable inkjet ink and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocurable inkjet ink capable of expressing black without containing carbon black. <P>SOLUTION: The photocurable inkjet ink is a black photocurable inkjet ink and comprises at least a plurality of coloring agents, a polymerizable compound and a polymerization initiator. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a photocurable ink for ink jet and an ink jet recording method using the ink.

  In recent years, development of photocurable ink that is cured by light such as ultraviolet rays has been advanced. This photo-curable ink is capable of quick-drying in printing on a non-absorbing medium that does not absorb water-based ink such as plastic, and can achieve printing that prevents ink bleeding.

  The photocurable ink is composed of a polymerizable compound, a polymerization initiator, a pigment, and the like, and can be classified into a radical polymerization system and a cationic polymerization system depending on the composition, polymerization method, and the like. In order to cure the radical polymerization type photocurable ink, it is necessary to excite the polymerization initiator by irradiating light such as ultraviolet rays, to generate radicals, and to smoothly proceed the polymerization reaction (for example, Patent Document 1).

On the other hand, carbon black has been often used as a pigment for black ink. However, when carbon black is added to the photocurable ink, it absorbs light in the ultraviolet region, and it is difficult to start the polymerization reaction. Moreover, since carbon black adsorbs radicals generated by irradiating the polymerization initiator with ultraviolet rays, the polymerization reaction cannot proceed smoothly. Thus, since carbon black has an adverse effect on the curing process of the photocurable ink, it has been desired to develop a photocurable black ink that does not contain carbon black.
JP 2006-123542 A

  An object of the present invention is to provide a photocurable ink for inkjet which can express black without containing carbon black.

  The inkjet photocurable ink according to the present invention is a black inkjet photocurable ink, and includes at least a plurality of colorants, a polymerizable compound, and a polymerization initiator.

  In the photocurable ink for ink jet according to the present invention, the ink may include at least three colorants of cyan, magenta, and yellow.

  The inkjet photocurable ink according to the present invention is a black inkjet photocurable ink, and (A) a cyan inkjet photocurable ink containing at least a polymerizable compound, a polymerization initiator, and a colorant, (B) Magenta inkjet photocurable ink containing at least a polymerizable compound, a polymerization initiator and a colorant, and (C) Yellow inkjet photocurable containing at least a polymerizable compound, a polymerization initiator and a colorant. It was prepared by previously mixing at least three types of mold inks.

  In the photocurable ink for inkjet according to the present invention, the colorant may be a pigment.

  The photocurable ink for ink jet according to the present invention can contain no carbon black.

  In the photocurable ink for ink jet according to the present invention, the polymerizable compound may include at least one of an allyl compound and an N-vinyl compound.

  In the photocurable ink for ink jet according to the present invention, the polymerizable compound may include at least one of a dendritic polymer and a urethane oligomer.

  In the photocurable ink for inkjet according to the present invention, the allyl compound may be allyl glycol.

  In the photocurable ink for inkjet according to the present invention, the N-vinyl compound may be N-vinylformamide.

  The inkjet recording method according to the present invention is characterized in that a black film of an image is formed using the above-described inkjet photocurable ink, and the film is cured by irradiation with light.

  The inkjet photocurable ink according to the present invention (hereinafter also referred to as “composite black ink”) is a black inkjet photocurable ink, and includes at least a plurality of colorants, a polymerizable compound, and a polymerization initiator. Is included.

  Further, the composite black ink according to the present invention includes (A) a photocurable ink for cyan inkjet containing at least a polymerizable compound, a polymerization initiator and a colorant, and (B) at least a polymerizable compound, a polymerization initiator and a color. Prepared by premixing at least three types of magenta inkjet photocurable ink containing an agent and (C) yellow inkjet photocurable ink containing at least a polymerizable compound, a polymerization initiator and a colorant. It may be what was done.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

1. Composite Black Ink The composite black ink according to the present embodiment is a photocurable ink characterized by not containing carbon black.

  The composite black ink according to the present embodiment is obtained by mixing at least a plurality of colorants, a polymerizable compound, and a polymerization initiator.

  The composite black ink according to the present embodiment can also be obtained by previously mixing an appropriate amount of at least three photocurable ink compositions of cyan, magenta, and yellow. Since the ink is a photocurable ink, it contains at least a polymerizable compound, a polymerization initiator and a colorant, and can contain no aqueous solvent. Since the ink does not contain carbon black, it does not absorb light in the ultraviolet region and does not adsorb radicals generated by irradiating the polymerization initiator with ultraviolet light. As a result, the black film of the image formed by landing the ink can be cured by starting a polymerization reaction by irradiating light such as ultraviolet rays.

  Hereinafter, each component contained in the composite black ink will be described in detail.

1.1 Polymerizable Compound The composite black ink according to the present embodiment can contain at least one of an allyl compound and an N-vinyl compound as the polymerizable compound.

1.1.1 Allyl Compound In the present specification, an allyl compound is a generic name for compounds having a ₂ -propenyl group (—CH ₂ CH═CH ₂ ). The 2-propenyl group is also called an allyl group, and is a common name in the IUPAC nomenclature.

  As the allyl compound, for example, allyl glycol (manufactured by Nippon Emulsifier Co., Ltd.), trimethylolpropane diallyl ether, pentaerythritol triallyl ether, glycerin monoallyl ether (above, manufactured by Daiso Corporation), UNIOX, UNILOVE, polyserine, A polyoxyalkylene compound having an allyl group (Nippon Yushi Co., Ltd.), which is a trade name of Unisafe, can be mentioned. In particular, allyl glycol and trimethylolpropane diallyl ether are preferable.

1.1.2 N-vinyl compounds Examples of N-vinyl compounds include N-vinylformamide, N-vinylcarbazole, N-vinylacetamide, N-vinylpyrrolidone, N-vinylcaprolactam, and their derivatives. it can. In particular, N-vinylformamide is preferable.

  The composite black ink according to the present embodiment can include at least one of a dendritic polymer and a urethane-based oligomer as a polymerizable compound.

1.1.3 Dendritic Polymers Dendritic polymers can be roughly classified into six structures as shown below ("Dendritic Polymers-A World of Higher Functionality Expanded by Multi-Branched Structures") Keigo Aoi / Enomoto Supervised by Masaaki, see NTS Corporation).

I Dendrimer II Linear-dendritic polymer III Dendrigraft polymer IV Hyperbranched polymer V Star hyperbranched polymer VI Hypergraft polymer Among these, I to III have a degree of branching (DB: 1) and no defects While having a structure, IV to VI have a random branched structure which may contain defects. In particular, dendrimers can concentrate reactive functional groups on the outermost surface in a dense and concentrated manner compared to generally used polymers on a straight line. Expectation is high. In addition, although hyperbranched polymers, dendricraft polymers and hypergraft polymers are not as large as dendrimers, many reactive functional groups can be introduced on the outermost surface, and the curability is excellent.

  Unlike conventional linear polymers and branched polymers, these dendritic polymers repeat highly branched structures in three dimensions and are highly branched. Therefore, it is possible to keep the viscosity low as compared with a linear polymer having the same molecular weight.

  Examples of the method of synthesizing the dendrimer that can be used in the present invention include a Divergent method for synthesizing from the center to the outside and a Convergent method for synthesizing from the outside to the center.

  The dendrimer, hyperbranched polymer, dendrigraft polymer and hypergraft polymer that can be used in the present invention are preferably solids at room temperature and have a number average molecular weight in the range of 1,000 to 100,000, particularly 2 Those in the range of 50,000 to 50,000 are preferably used. When it is not solid at room temperature, the maintainability of the formed image is deteriorated. In addition, when the molecular weight is lower than the above range, the fixed image becomes fragile, and when the molecular weight is higher than the above range, the viscosity of the ink becomes too high even if the addition amount is lowered, in terms of flight characteristics. It is no longer practical.

  The dendrimers, hyperbranched polymers, dendrigraft polymers and hypergraft polymers that can be used in the present invention are dendrimers, hyperbranched polymers, dendrigraft polymers and hypergraft polymers having a radically polymerizable functional group on the outermost surface. Preferably there is. By adopting a structure capable of radical polymerization on the outermost surface, the polymerization reaction proceeds rapidly.

  Examples of the polymer having a dendrimer structure include amidoamine dendrimers (US Pat. Nos. 4,507,466, 4,558,120, 4,568,737, 4,587,329, and 4). 631,337, 4,694,064), phenyl ether dendrimers (US Pat. No. 5,041,516, Journal of American Chemistry 112 (1990, 7638-7647)) Etc. As for the amidoamine dendrimer, a dendrimer having a terminal amino group and a carboxylic acid methyl ester group is commercially available from Aldrich as “Starburst ™ (PAMAM)”. In addition, the terminal amino group of the amidoamine-based dendrimer can be reacted with various acrylic acid derivatives and methacrylic acid derivatives to synthesize amidoamine-based dendrimers having corresponding terminals, and then used.

  Examples of acrylic acid derivatives and methacrylic acid derivatives that can be used include acrylic acid such as methyl, ethyl, n-butyl, t-butyl, cyclohexyl, palmityl, stearyl, alkyl methacrylates, acrylic acid amide, isopropylamide, and the like. Examples include, but are not limited to, acrylic acid or methacrylic acid alkylamides.

Various examples of phenyl ether dendrimers are described in the Journal of American Chemistry Vol. 112 (1990, pages 7638-7647). For example, 3,5-dihydroxybenzyl alcohol is used, A second-generation benzyl alcohol was synthesized by reacting with 5-diphenoxybenzyl bromide, the OH group was converted to Br using CBr ₄ and triphenylphosphine, and then reacted with 3,5-dihydroxybenzyl alcohol in the same manner. The next generation benzyl alcohol is synthesized, and the following reaction is repeated to synthesize the desired dendrimer. As for the phenyl ether dendrimer, the terminal can be substituted with one having various chemical structures instead of the terminal benzyl ether bond. For example, when synthesizing the dendrimer described in Journal of American Chemistry Vol. 112, various alkyl halides are used in place of the benzyl bromide, a phenyl ether dendrimer having a terminal structure having a corresponding alkyl group can be obtained. In addition, polyamine dendrimers (Macromol. Symp. 77, 21 (1994)) and derivatives obtained by modifying terminal groups thereof can be used.

  As the hyperbranched polymer, for example, hyperbranched polyethylene glycol can be used. A hyperbranched polymer uses a monomer that has two or more kinds of reaction points corresponding to a branched portion and one kind of another reaction point corresponding to a connecting portion in one molecule, and the target polymer in one step. It is obtained by synthesis (Non-patent Document 3 (Macromolecules, 29 (1996), pages 3831-3838)). For example, a 3,5-dihydroxybenzoic acid derivative is mentioned as an example of the monomer for hyperbranched polymers. Examples of producing hyperbranched polymers include 3,5-bis obtained from 1-bromo-8- (t-butyldiphenylsiloxy) -3,6-dioxaoctane and methyl 3,5-dihydroxybenzoate. 3,5-bis ((8'-hydroxy-3 ', 6) which is a hydrolyzate of methyl ((8'-(t-butyldiphenylsiloxy) -3 ', 6'-dioxaoctyl) oxy) benzoate The hyperbranched polymer poly [bis (triethyleneglycol) benzoate] can be synthesized by heating methyl '' -dioxaoctyl) oxy) benzoate with dibutyltin diacetate in a nitrogen atmosphere.

  When 3,5-dihydroxybenzoic acid is used, the hyperbranched polymer terminal group becomes a hydroxyl group, and therefore, hyperbranched polymers having various terminal groups are synthesized by using an appropriate alkyl halide for the hydroxyl group. be able to.

  The properties of monodisperse polymers or hyperbranched polymers with a dendrimer structure are governed by the chemical structure of the main chain and the chemical structure of the terminal group, but the characteristics are particularly dependent on the difference of the substituents in the terminal group and chemical structure. Are very different. Those having a polymerizable group at the terminal are particularly useful because of their reactivity, the gelation effect after photoreaction is great. A dendrimer having a polymerizable group can be obtained by chemically modifying a compound having a polymerizable group at the end of one having a basic atomic group such as an amino group, a substituted amino group, or a hydroxyl group at the end.

  For example, it is synthesized by adding, for example, an isocyanate group-containing vinyl compound to a polyfunctional compound obtained by Michael addition of an active hydrogen-containing (meth) acrylate compound to an amino dendrimer. Moreover, the dendrimer which has a polymerizable group at the terminal is obtained by making (meth) acrylic acid chloride etc. react with an amino dendrimer, for example. Examples of the vinyl compound providing such a polymerizable group include compounds having an ethylenically unsaturated bond capable of radical polymerization, and examples thereof include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, and isocrotonic acid. And compounds having various ethylenically unsaturated bonds capable of radical polymerization described later, such as unsaturated carboxylic acids such as maleic acid and salts thereof.

  Furthermore, examples of the polymerizable group include a terminal group having a cationic polymerizable group, and a polymerizable group that undergoes polymerization by cationic polymerization such as an epoxy group or an oxetanyl group, for example, a cyclic ether such as oxirane or oxetane. Compounds such as cycloaliphatic polyepoxides, polyglycidyl esters of polybasic acids, polyglycidyl ethers of polyhydric alcohols and the like can be introduced by reacting with the amino dendrimer. For example, chloromethyloxirane can be reacted with an amino dendrimer to introduce an epoxy type cationic polymerizable group at the terminal. In addition, examples of the terminal group include a cationic polymerizable group selected from styrene derivatives, vinyl naphthalene derivatives, vinyl ethers, N-vinyl compounds, and the like.

  In the composite black ink according to the present embodiment, the above dendrimer, hyperbranched polymer, dendrigraft polymer, and hypergraft polymer may be used alone or in combination with other types of dendrimers, hyperbranched polymers, dendrimers. You may use together with a drigraft polymer and a hypergraft polymer.

  Specific examples of the dendritic polymer include V # 1000 (manufactured by Osaka Organic Chemical Industry Co., Ltd.).

  In the composite black ink according to the present embodiment, the amount of the dendritic polymer added is preferably in the range of about 3 to 30% by mass, more preferably 5 to 25% by mass. If the amount of the dendritic polymer added is less than 3% by mass, the curability as an ink set is insufficient, and if it exceeds 30% by mass, problems such as viscosity, dispersion stability, and storage stability of the ink composition occur. There is a case.

1.1.4 Urethane oligomer When the urethane oligomer is added, the film strength of the ink can be increased, and the curability of the ink can be further improved. Thereby, the ink composition which can form a clear image can be provided.

  In the present specification, the urethane-based oligomer means one having at least one urethane bond and radically polymerizable unsaturated double bond in the molecule. Here, the oligomer used in the present embodiment is a small number of units substantially or conceptually obtained from a molecule having a small relative molecular mass (synonymous with molecular weight), generally about 2 to 20 times. Molecules with a medium relative molecular mass with a degree of repetitive structure. The oligomer used in this embodiment is a so-called photopolymerizable prepolymer, base resin, or acrylic oligomer.

  Since the urethane-based oligomer has 1 to several acryloyl groups as functional groups, it has a property of causing a polymerization reaction with a monomer or the like by ultraviolet irradiation or the like and crosslinking polymerization.

  Examples of urethane oligomers include oligomers produced by addition reactions with polyols, polyisocyanates, and polyhydroxy compounds. Examples thereof include polyester urethane acrylate, polyether urethane acrylate, polybutadiene urethane acrylate, and polyol urethane acrylate. Specific examples of the urethane oligomer include U-4HA and U-15HA (manufactured by Shin-Nakamura Chemical Co., Ltd.).

  The molecular weight of the urethane oligomer is preferably about 500 to 20,000, more preferably about 500 to 10,000.

  The content of the urethane oligomer in the composite black ink according to the present embodiment is preferably 1 to 50% by mass, more preferably 3 to 30% by mass.

1.2 Polymerization Initiator The composite black ink according to the present embodiment preferably includes a radical polymerization or cationic polymerization photopolymerization initiator as a polymerization initiator. A photopolymerization initiator is a compound that generates a chemical change through the action of light or interaction with the electronically excited state of a sensitizing dye to generate at least one of a radical, an acid, and a base. . The photopolymerization initiator is an actinic ray to be irradiated, for example, 400 to 200 nm ultraviolet ray, far ultraviolet ray, g ray, h ray, i ray, KrF excimer laser beam, ArF excimer laser beam, electron beam, X ray, molecular beam. Alternatively, those having sensitivity to an ion beam or the like can be appropriately selected and used.

  Examples of photopolymerization initiators include aromatic ketones, aromatic onium salt compounds, organic peroxides, hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, and carbon halogens. Examples include compounds having a bond.

1.2.1 Aromatic Ketones Preferred examples of aromatic ketones include “RADIATION CURING IN POLYMER SCIENCE AND TECHNOLOGY” P. FOUASSIER J.M. F. Examples thereof include compounds having a benzophenone skeleton or a thioxanthone skeleton described in RABEK (1993), p77-117.

  Examples of aromatic ketones include α-thiobenzophenone compounds described in JP-B-47-6416, benzoin ether compounds described in JP-B-47-3981, α-substituted benzoin compounds described in JP-B-47-22326, and JP-B-47- Benzoin derivatives described in 23664, aroylphosphonic acid esters described in JP-A-57-30704, dialkoxybenzophenones described in JP-B-60-26483, JP-B-60-26403, JP-A-62-81345 Benzoin ethers described in Japanese Patent Publication No. JP-B-34242, US Pat. No. 4,318,791, α-aminobenzophenones described in European Patent No. 0284561A1, and p-di ( Dimethylaminobenzoyl) benzene, JP-A 61- No. 94062, a thio-substituted aromatic ketone, an acylphosphine sulfide described in JP-B-2-9597, an acylphosphine described in JP-B-2-9596, a thioxanthone described in JP-B-63-61950, Examples thereof include coumarins described in Japanese Patent No. 59-42864.

1.2.2 Aromatic Onium Salt Compounds Aromatic onium salt compounds include Group V, VI, and VII elements of the Periodic Table, specifically N, P, As, Sb, Bi, O, S , Se, Te, or I aromatic onium salts. For example, iodonium salts described in European Patent No. 104143, US Pat. No. 4,837,124, Japanese Patent Laid-Open No. 2-150848, Japanese Patent Laid-Open No. 2-96514, European Patent Nos. 370693, 233567, and 297443 are disclosed. , 294442, 279210, and 422570, U.S. Pat. Nos. 3,902,144, 4,933,377, 4,760013, 4,734,444, and 2,833,827, sulfonium salts and diazonium salts (Such as benzenediazonium which may have a substituent), diazonium salt resins (formaldehyde resin of diazodiphenylamine, etc.), N-alkoxypyridinium salts, etc. (for example, US Pat. No. 4,743,528, JP 63-1383 No. 5, JP-A-63-142345, JP-A-63-142346, and JP-B-46-42363, specifically, 1-methoxy-4-phenylpyridinium tetrafluoro Borate and the like), and compounds described in JP-B Nos. 52-147277, 52-14278, and 52-14279 are preferable.

1.2.3 Organic peroxides Organic peroxides include almost all organic compounds having at least one oxygen-oxygen bond in the molecule. Examples thereof include 3, 3 ', 4, 4'-tetra- (t-butylperoxycarbonyl) benzophenone, 3,3 ', 4,4'-tetra- (t-amylperoxycarbonyl) benzophenone, 3,3', 4,4'-tetra- ( t-hexylperoxycarbonyl) benzophenone, 3,3 ', 4,4'-tetra- (t-octylperoxycarbonyl) benzophenone, 3,3', 4,4'-tetra- (cumylperoxycarbonyl) Peracids such as benzophenone, 3,3 ', 4,4'-tetra- (p-isopropylcumylperoxycarbonyl) benzophenone, di-t-butyldiperoxyisophthalate Ester is preferable.

1.2.4 Hexaarylbiimidazole compound Examples of the hexaarylbiimidazole include lophine dimers described in JP-B-45-37377 and JP-B-44-86516, such as 2,2′-bis (o -Chlorophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-bromophenyl) -4,4', 5,5'-tetraphenylbiimidazole, 2,2 '-Bis (o, p-dichlorophenyl) -4,4', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetra ( m-methoxyphenyl) biimidazole, 2,2'-bis (o, o'-dichlorophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bi (O-nitrophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-methylphenyl) -4,4', 5,5'-tetraphenylbiimidazole, Examples include 2,2'-bis (o-trifluorophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole.

1.2.5 Ketooxime Ester Compound Examples of the ketoxime ester include 3-benzoyloxyiminobutan-2-one, 3-acetoxyiminobutan-2-one, 3-propionyloxyiminobutan-2-one, 2- Acetoxyiminopentan-3-one, 2-acetoxyimino-1-phenylpropan-1-one, 2-benzoyloxyimino-1-phenylpropan-1-one, 3-p-toluenesulfonyloxyiminobutane-2- ON, 2-ethoxycarbonyloxyimino-1-phenylpropan-1-one, and the like.

1.2.6 Borate Compound Examples of the borate compound include compounds described in US Pat. Nos. 3,567,453 and 4,343,891, European Patents 109,772 and 109,773. Can do.

1.2.7 Azinium salts As the azinium salt compounds, JP-A 63-138345, JP-A 63-142345, JP-A 63-142346, JP-A 63-143537, and JP-B 46- The compound group which has NO bond of 42363 description can be mentioned.

1.2.8 Metallocene Compounds Examples of metallocene compounds include JP 59-152396, JP 61-151197, JP 63-41484, JP 2-249, and JP 2-4705. And the iron-arene complexes described in JP-A-1-304453 and JP-A-1-152109.

  Specific examples of the titanocene compound include di-cyclopentadienyl-Ti-di-chloride, di-cyclopentadienyl-Ti-bis-phenyl, and di-cyclopentadienyl-Ti-bis-2,3. 4,5,6-pentafluoro-phen-1-yl, di-cyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-cyclopentadienyl-Ti -Bis-2,4,6-trifluorophen-1-yl, di-cyclopentadienyl-Ti-2,6-difluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2, 4-difluorophenyl-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl, di-methylcyclopentadienyl-T -Bis-2,3,5,6-tetrafluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,4-difluorophen-1-yl, bis (cyclopentadienyl)- Bis (2,6-difluoro-3- (pyridin-1-yl) phenyl) titanium, bis (cyclopentadienyl) bis [2,6-difluoro-3- (methylsulfonamido) phenyl] titanium, bis (cyclo And pentadienyl) bis [2,6-difluoro-3- (N-butylbialoyl-amino) phenyl] titanium.

1.2.9 Active Ester Compound Examples of the active ester compound include European Patent Nos. 0290750, 046083, 156153, 271851, and 0388343, U.S. Pat. Nos. 3,901,710 and 4,181,531. Nitrobenzol ester compounds described in JP-A-60-198538 and JP-A-53-133022, European Patents 0199672, 84515, 199672, 0441115, and 0101122 Specifications, U.S. Pat. Nos. 4,618,564, 4,371,605, and 4,431,774, JP-A 64-18143, JP-A-2-245756, and JP-A-4-36548, respectively. Shoko 62-62 No. 3, JP-B-63-14340, and include compounds described in JP-59-174831 each publication.

1.2.10 Compound having a carbon halogen bond As a compound having a carbon halogen bond, for example, Wakabayashi et al., Bull. Chem. Soc. Examples include compounds described in Japan, 42, 2924 (1969), compounds described in British Patent 1388492, compounds described in JP-A-53-133428, compounds described in German Patent 3333724, and the like. .

  F.F. C. J. Schaefer et al. Org. Chem. 29, 1527 (1964), compounds described in JP-A-62-258241, compounds described in JP-A-5-281728, and the like. A compound as described in German Patent No. 2641100, a compound as described in German Patent No. 3333450, a compound group as described in German Patent No. 3021590, or a compound group as described in German Patent No. 3021599, etc. Can be mentioned.

  Also, Vice 10, 30 (manufactured by Stauffer Chemical), Irgacure 127, 184, 500, 651, 2959, 907, 369, 379, 754, 1700, 1800, 1850, 819, OXE01, Darocur 1173, TPO, ITX (Ciba・ Use of photo radical polymerization initiators available under the trade names of Specialty Chemicals, Quanture CTX (Aceto Chemical), Kayacure DETX-S (Nippon Kayaku) and ESACURE KIP150 (Lamberti) can do.

1.3 Colorant The composite black ink according to the present embodiment includes a colorant. The colorant used in this case may be either a dye or a pigment. The composite black ink according to the present embodiment is often used for the purpose of directly printing on non-absorbing media that do not absorb water-based ink such as plastic media. Therefore, the pigment is preferable from the viewpoint of durability of the printed matter.

  Examples of pigments used in yellow ink include C.I. I. Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 120, 128, 129, 138, 150, 151, 154, 155, 180, 185, 213 and the like.

  Examples of pigments used in magenta ink include C.I. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 122, 123, 168, 184, 202, 209, C.I. I. Pigment violet 19 and the like.

  Examples of pigments used for cyan ink include C.I. I. And CI Pigment Blue 1, 2, 3, 15: 3, 15: 4, 60, 16, and 22.

  The average particle diameter of the pigment is preferably in the range of 10 to 200 nm, more preferably in the range of 50 to 150 nm.

  The addition amount of the pigment of the composite black ink according to the present embodiment is preferably 0.1 to 25% by mass, and more preferably 0.5 to 15% by mass.

  The composite black ink according to this embodiment can be prepared by mixing a plurality of colorants, a polymerizable compound, a polymerization initiator, and the like. As the composite black colorant, for example, three color pigments used in the yellow, magenta and cyan ink compositions can be selected. Here, an appropriate amount of two types of pigments selected from yellow, magenta and cyan may be mixed. However, in order to further improve the color tone as black, at least three pigments of yellow, magenta and cyan should be mixed. Is preferred. In addition to the above-described three color pigments of yellow, magenta, and cyan, the same series of light color pigments such as light magenta and light cyan can be added.

  The composite black ink according to this embodiment can also be prepared by mixing at least three types of photocurable ink compositions of yellow ink, magenta ink, and cyan ink. In addition to the three colors of yellow ink, magenta ink, and cyan ink, the same series of light colors such as light magenta ink and light cyan ink can be added.

  Since the composite black ink does not contain carbon black or titanium black, it hardly absorbs ultraviolet rays, and carbon black does not absorb radicals generated when the polymerization initiator is exposed to ultraviolet rays. Therefore, the composite black ink according to the present embodiment can be cured using ultraviolet rays.

1.4 Other Additives The composite black ink according to the present embodiment can also contain a surfactant. For example, polyester-modified silicone or polyether-modified silicone is preferably used as the silicone surfactant, and polyether-modified polydimethylsiloxane or polyester-modified polydimethylsiloxane is particularly preferably used. Specific examples include BYK-347, 348, BYK-UV3500, 3510, 3530, 3570 (manufactured by Big Chemie Japan Co., Ltd.).

  The composite black ink according to this embodiment may be added with other publicly known wetting agents, penetrating solvents, pH adjusting agents, preservatives, antifungal agents, and the like as other components. Furthermore, a leveling additive, a matting agent, a polyester resin for adjusting film properties, a polyurethane resin, a vinyl resin, an acrylic resin, a rubber resin, and waxes can be added as necessary. Moreover, when using the composite black ink which concerns on this embodiment with an inkjet recording method, it is preferable on use that the viscosity is 10 mPa * s or less at 25 degreeC.

2. Inkjet Recording Method The inkjet recording method according to the present embodiment is a method in which photocurable composite black ink is ejected onto a recording medium to form a black film, and then irradiated with light such as ultraviolet rays.

  In the ink jet recording method according to the present embodiment, photocurable composite black ink can be ejected onto a recording medium using an ink jet printer. The ink jet printer mainly includes an ink jet recording head, a main body, a tray, a head driving mechanism, a carriage, and a light irradiation device mounted on a side surface of the carriage. The ink jet recording head includes at least four ink cartridges of cyan, magenta, yellow, and black, and is configured to perform full color printing. The black ink cartridge is filled with the composite black ink according to the present embodiment and installed. The ink jet printer includes a dedicated controller board and the like, and can control ink ejection timing of the ink jet recording head and scanning of the head driving mechanism.

For the light irradiation, a light irradiation device mounted on the side surface of the carriage in the ink jet printer can be applied. The wavelength of the irradiation light source is not particularly limited, but is preferably 350 nm or more and 450 nm or less. A light irradiation amount is preferably 10 mJ / cm ² or more and 20,000mJ / cm ² or less, more preferably 50 mJ / cm ² or more, conducted at 15,000 / cm ² or less. If the amount of light irradiation is within this range, the curing reaction can be sufficiently performed.

  Examples of the light irradiation include metal halide lamps, xenon lamps, carbon arc lamps, chemical lamps, low-pressure mercury lamps, and high-pressure mercury lamp lamps. For example, a commercially available product such as an H lamp, a D lamp, or a V lamp manufactured by Fusion System can be used.

  Further, ultraviolet irradiation can be performed by an ultraviolet light emitting semiconductor element such as an ultraviolet light emitting diode (ultraviolet LED) or an ultraviolet light emitting semiconductor laser.

  The ink jet recording method according to the present embodiment can be preferably used for printing on non-absorbent media such as metal, glass and plastic, creation of a color filter, and marking on a printed circuit board.

3. Examples Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto.

3.1 Preparation of Cyan, Magenta, Yellow and Pure Black Pigment Dispersions The pigment dispersions used in Examples 7-12 and Comparative Examples 1-6 were prepared by the method described below. As a coloring agent, C.I. I. 15 parts of Pigment Blue 15: 3, 3.5 parts of Discol N-509 (manufactured by Dainichi Seika Kogyo Co., Ltd.) as a dispersing agent, and 100 parts of the whole by adding allyl glycol (manufactured by Nippon Emulsifier Co., Ltd.) as a monomer And mixed and stirred to obtain a mixture. Similarly, trimethylolpropane diallyl ether (manufactured by Daiso Co., Ltd.) and N-vinylformamide (manufactured by Arakawa Chemical Industries, Ltd.) were added as monomers to make a total of 100 parts, and the mixture was stirred to obtain a mixture. This mixture was subjected to a dispersion treatment for 6 hours together with zirconia beads (diameter 1.5 mm) using a sand mill (manufactured by Yaskawa Seisakusho). Thereafter, the zirconia beads were separated with a separator to obtain a cyan dispersion of an allyl glycol solvent, a cyan dispersion of a trimethylolpropane diallyl ether solvent, and a cyan dispersion of an N-vinylformamide solvent.

  Hereinafter, similarly, pigment dispersions corresponding to the respective colors, that is, magenta pigment dispersion (CI Pigment Violet-19), yellow pigment dispersion (CI Pigment Yellow 155), and pure black pigment dispersion (CI Pigment Black 7) was prepared.

3.2 Preparation of ink composition Based on the composition described in Tables 1 to 7, an ink composition was prepared by mixing and completely dissolving a polymerizable compound, a photopolymerization initiator, a dispersant, and the like. The dispersion was gradually dropped into the ink solvent of the ink composition while stirring. After completion of the dropwise addition, the mixture was stirred at room temperature for 1 hour to obtain an ink composition used in Examples and Comparative Examples. Thereafter, each ink composition was filtered through a 5 μm membrane filter to obtain a desired ink composition. Tables 1 to 7 show ink compositions of Examples and Comparative Examples.

  Examples 1 to 6 are examples in which the components described in Table 1 were stirred and mixed to produce a composite black ink composition.

  In Examples 7 to 12, cyan ink (C), magenta ink (M), and yellow ink (Y) having the compositions described in Tables 2 to 7 were prepared, and then these inks were mixed to form a composite black ink composition. This is an example of manufacturing a product.

  Comparative Examples 1 to 6 are examples in which components other than the pigment were the same as in corresponding Examples 7 to 12, but a pure black ink (K) was produced using a pigment containing carbon black.

3.3 Film Curing Test Using an inkjet printer PX-G920 (manufactured by Seiko Epson Corporation), each nozzle was filled with a composite black ink and a pure black ink. A black solid pattern was printed on a PET film by landing ink droplets at room temperature and normal pressure. Then, ultraviolet rays having a wavelength of 365 nm, 380 nm, and 395 nm were irradiated from an ultraviolet irradiation device having an irradiation intensity of 60 mW / cm ² mounted on the side of the carriage. Curing treatment was performed under curing conditions such that the integrated light amount was 150 mJ / cm ^2, and evaluation was performed based on the following indices. The results are shown in Table 8.
A: Completely cured.
B: An uncured part exists on the surface.

  From the results of Comparative Examples 1 to 6, the composite black ink according to the present example has ultraviolet rays, whereas the pure black ink to which the conventional carbon black was added was irradiated with ultraviolet rays, there was an uncured portion on the surface. It was found that it was completely cured when irradiated.

  Also, a composite black ink (Examples 1 to 6) prepared by mixing each component, or a composite black prepared by mixing cyan ink, magenta ink, and yellow ink, and then mixing these inks Regardless of the ink (Examples 7 to 12), it was found that when the composite black ink according to the present example was irradiated with the above ultraviolet rays, it was completely cured.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

Claims (10)

A black inkjet photo-curable ink,
A photocurable ink for inkjet, comprising at least a plurality of colorants, a polymerizable compound, and a polymerization initiator. In claim 1,
The ink is a photocurable ink for inkjet, which contains at least three colorants of cyan, magenta, and yellow. A black inkjet photo-curable ink,
(A) a photocurable ink for cyan inkjet, comprising at least a polymerizable compound, a polymerization initiator, and a colorant;
(B) Magenta inkjet photocurable ink containing at least a polymerizable compound, a polymerization initiator and a colorant, and (C) Yellow inkjet photocurable containing at least a polymerizable compound, a polymerization initiator and a colorant. Mold ink,
A photocurable ink for ink jet prepared by previously mixing at least three inks. In any one of Claims 1 thru | or 3,
The photochromic ink for inkjet, wherein the colorant is a pigment. In any of claims 1 to 4,
Photo-curing ink for inkjet, which does not contain carbon black. In any of claims 1 to 5,
A photocurable ink for inkjet, comprising at least one of an allyl compound and an N-vinyl compound as the polymerizable compound. In any one of Claims 1 thru | or 6.
A photocurable ink for inkjet, comprising at least one of a dendritic polymer and a urethane-based oligomer as the polymerizable compound. In claim 6,
The allyl compound is a photocurable ink for inkjet, which is allyl glycol. In claim 6,
The N-vinyl compound is N-vinylformamide, a photocurable ink for inkjet.   10. An ink jet recording method comprising: forming a black film of an image using the photocurable ink for ink jet according to claim 1; and irradiating the film with light to cure the film.