JP2009226732A - Inkjet ink set and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous type inkjet ink set being excellent in drying property, offset tolerance, sharpness and scratch resistance of a formed image, and to provide an inkjet recording method using the inkjet ink set. <P>SOLUTION: This inkjet ink set is constituted of the nonaqueous type inkjet ink and a cohesion accelerating liquid. In this case, the nonaqueous type inkjet ink contains at least a pigment, an anchoring resin, and a compound (A) consisting of one kind or more of compounds being selected from a compound group represented by general formula (1) R<SB>1</SB>-S(O)<SB>n</SB>-R<SB>2</SB>and general formula (2). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an inkjet ink set composed of a non-aqueous inkjet ink and an inkjet recording method using the inkjet ink set.

  In recent years, the inkjet recording method can be easily and inexpensively created images, and thus has been applied to various printing fields such as photographs, various printing, marking, and special printing such as color filters.

  Ink jet inks used in such an ink jet recording method include water-based inks mainly containing water, oil-based inks mainly containing non-volatile solvents, non-aqueous inks mainly containing volatile solvents, and room temperature. There are inkjet inks with various characteristics, such as hot melt ink that heats and melts solid ink for printing, and actinic ray curable ink that cures with actinic rays such as light after printing. Yes.

  On the other hand, recording media made of soft polyvinyl chloride are used in a wide range of applications such as outdoor postings that require long-term weather resistance and printed materials that require adhesion to curved objects. There are many methods for printing on soft polyvinyl chloride, but there is an inkjet recording method as a method suitable for the production of a small variety of products because there is no need to prepare a plate and the time to finish is short.

  When ink jet recording is performed on soft polyvinyl chloride, as the ink jet ink to be used, conventionally, a non-aqueous ink jet ink containing a large amount of cyclohexanone or the like has been used. For example, an ink jet ink containing cyclohexanone is disclosed. (For example, refer to Patent Document 1). This cyclohexanone has a high solubility in soft polyvinyl chloride, and since the pigment in the ink-jet ink enters into the soft polyvinyl chloride, good scratch resistance and glossiness can be obtained. However, cyclohexanone has been designated as a first type organic solvent, which is not only a problem in safety, but also has a drawback that a local exhaust device is required when handling inkjet ink containing cyclohexanone.

  On the other hand, non-aqueous inkjet inks characterized by not containing cyclohexanone have been developed and sold. For example, a non-aqueous ink containing a solvent such as N-methylpyrrolidone or amide has been disclosed as a solvent for dissolving polyvinyl chloride in place of cyclohexanone having the above-mentioned problems (for example, Patent Documents). 2 and 3). Further, for the purpose of improving image fastness such as scratch resistance, a non-aqueous inkjet ink to which a fixing resin such as vinyl chloride-vinyl acetate copolymer or acrylic is added is disclosed (for example, Patent Documents 4 and 5). reference.). By using these inkjet inks, it is possible to suppress the odor during the recording operation and to form an image having scratch resistance against soft polyvinyl chloride.

  In recent years, there has been a demand for a higher printing speed in order to increase production efficiency. When a non-aqueous inkjet ink such as a conventional solvent ink is used, if a large amount of inkjet ink is applied on a non-absorbent recording medium in a short time, a phenomenon that the ink collects at the interface portion (hereinafter referred to as a liquid side) occurs. It has been found that density differences are formed in an image that is generated and should be uniform, and image quality deteriorates.

  In addition, due to the same phenomenon, it has become clear that the sharpness of fine image portions such as fine lines deteriorates. This indicates a phenomenon in which a plurality of fine lines are partially united when fine lines are printed at high density.

  Furthermore, when applying a large amount of inkjet ink in a short time, there is a high possibility that the drying will be insufficient, so that the adhesion of the image will be insufficient, and the image will be transferred to the back side when the images are superimposed. The phenomenon (hereinafter also referred to as setback) has become clear.

  A technique for obtaining an image with less blur using an ink jet ink set comprising a non-aqueous ink jet ink and an aggregation accelerating liquid containing water has been disclosed (for example, see Patent Document 6).

  In the invention described in Patent Document 6, blurring of an image is prevented by applying an aqueous flocculating liquid, but the improvement of the above-mentioned objects and effects is not described. In addition, since the aggregating liquid is non-aqueous, when applied on a non-absorbing support such as vinyl chloride, it is difficult to apply dots uniformly due to poor spread of the dots, and it is difficult to uniformly mix with ink. The effect is also limited.

Further, since the dispersion state of the coloring material is forcibly broken and aggregated by adding water, the aggregated particles of the coloring material become large and the resistance to rubbing deteriorates. It was also found that large aggregated particles cover the image surface and the surface gloss deteriorates.
Japanese translation of PCT publication No. 2002-526631 JP 2005-15672 A Japanese Patent Laid-Open No. 2005-60716 JP 2005-36199 A WO2004 / 007626 pamphlet JP-A-2005-290216

  The present invention has been made in view of the above problems, and its purpose is to provide a non-aqueous ink jet ink set excellent in the drying property, set-off resistance, sharpness and scratch resistance of the formed image, and ink jet recording using the same. It is to provide a method.

  The above object of the present invention is achieved by the following configurations.

  1. A non-aqueous inkjet ink containing at least a pigment, a fixing resin, and a compound (A) composed of one or more compounds selected from the group of compounds represented by the following general formulas (1) and (2), and at least a flocculant An ink-jet ink set comprising an aggregation promoting liquid.

General formula (1)
R ₁ —S (O) _n —R ₂
[Wherein, R ₁ and R ₂ each represent a substituent having 1 to 6 carbon atoms, and n represents 0, 1, or 2. ]

[Wherein, X represents —O—, —N (R ₃ ) — or —S (O) _m —. R ₃ represents a hydrogen atom or a substituent having 1 to 6 carbon atoms, and m represents 0, 1, or 2. Z represents an atomic group necessary for binding to X to form a 5- or 6-membered heterocyclic compound. ]
2. 2. The inkjet ink set as described in 1 above, wherein the flocculant is water.

  3. 2. The inkjet ink set as described in 1 above, wherein the flocculant is an organic acid.

  4). 2. The inkjet ink set as described in 1 above, wherein the flocculant is an amine.

  5). 5. The inkjet ink set according to 1 to 4, wherein the content of the compound (A) in the non-aqueous inkjet ink is 3% by mass or more and 30% by mass or less.

  6). The said 1-5 characterized by the said non-aqueous inkjet ink containing the solvent (B) which consists of 1 or more types of compounds chosen from the compound group represented by following General formula (3) and (4). Inkjet ink set.

General formula (3)
R ₅ — (OX ₁ ) _p —O—R ₆
[Wherein, R ₅ and R ₆ each represent a methyl group or an ethyl group, and OX ₁ represents an oxyethylene group or an oxypropylene group. p represents an integer of 1 to 4. ]

[Wherein, R ₇ and R ₈ each represent a methyl group or an ethyl group, and OX ₂ represents an oxyethylene group or an oxypropylene group. k represents an integer of 1 to 4. ]
7). 7. The inkjet ink set as described in 6 above, wherein the content of the solvent (B) in the non-aqueous inkjet ink is 50% by mass or more and 90% by mass or less.

  8). 8. The above 6 or 7, wherein the solvent (B) is at least one selected from diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, ethylene glycol diacetate and propylene glycol diacetate. Inkjet ink set.

  9. The fixing resin contained in the non-aqueous inkjet ink has a vinyl chloride-vinyl acetate copolymer and a vinyl chloride-vinyl acetate-maleic anhydride copolymer having a number average molecular weight in the range of 10,000 to 30,000. The said any one of 1-8 characterized by being at least 1 sort (s) chosen from a vinyl chloride-vinyl acetate-vinyl alcohol copolymer and a vinyl chloride-vinyl acetate-hydroxyalkyl acrylate copolymer. Inkjet inkjet ink set.

  10. 10. An inkjet recording method comprising performing image recording using the inkjet ink set according to any one of 1 to 9 above.

  According to the present invention, it was possible to provide a non-aqueous inkjet ink set excellent in the drying property, set-off resistance, sharpness and scratch resistance of the formed image, and an inkjet recording method using the same.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  As a result of intensive studies in view of the above problems, the present inventor has at least a compound composed of at least a pigment, a fixing resin, and one or more compounds selected from the group of compounds represented by the following general formulas (1) and (2) ( A non-aqueous inkjet ink containing A) and an aggregation accelerating liquid containing at least an aggregating agent, and an ink-jet ink set characterized in that the formed image has dryness, set-off resistance, sharpness and abrasion resistance. As a result, the present inventors have found that a non-aqueous inkjet ink set having excellent properties can be realized.

  The inventors of the present invention have studied the types of solvents constituting the ink-jet ink and the combinations thereof for each problem in image formation using the above-described non-aqueous ink-jet ink. As a result, the general formula (1) represents the problem. One or more compounds selected from the group of sulfides, sulfoxides and sulfone compounds, or selected from the group of 5 to 6-membered oxygen-containing, nitrogen and sulfur heterocyclic compounds represented by the general formula (2) By using an inkjet ink set composed of a compound (A) composed of one or more compounds, a non-aqueous inkjet ink containing a pigment and a fixing resin, and an aggregation accelerating liquid, no liquid deviation occurs. Inkjet ink that can produce high-gloss and sharp images, has excellent resistance to rubbing, and has no set-off It was found Tsu bets and an ink jet recording method.

  The reason is not clear, but is estimated as follows.

  When the non-aqueous inkjet ink and the aggregation promoting liquid are mixed, the pigment fine particles are aggregated by the effect of the aggregating agent contained in the aggregation promoting liquid and fixed on the recording medium. The non-aqueous inkjet ink used in the present invention contains one or more compounds selected from the compound group represented by the general formulas (1) and (2). These compounds are characterized by being aprotic and highly polar. Due to this feature, the aggregates of pigment fine particles are stabilized in a very fine state, so that the resistance to abrasion is not deteriorated and the surface gloss is not deteriorated. Further, due to this feature, the flocculant contained in the aggregation accelerating liquid can be quickly mixed in the ink, so that a fine aggregate of pigment fine particles can be formed before liquid deviation occurs. Further, it is considered that this feature causes a combined action with the polar part of the molecules constituting the recording medium, gives excellent drying properties, and can prevent set-off.

  Hereinafter, the configuration of the inkjet ink set of the present invention will be specifically described.

  In the non-aqueous inkjet ink of the present invention (hereinafter also referred to as inkjet ink or ink), one or more compounds selected from the group of sulfides, sulfoxides and sulfone compounds represented by the general formula (1), or the general It contains a compound (A) composed of one or more compounds selected from the group of 5 to 6-membered oxygen-containing, nitrogen and sulfur heterocyclic compounds represented by the formula (2).

In the general formula (1), R ₁ and R ₂ each represent a substituent having 1 to 6 carbon atoms, for example, a linear or branched alkyl such as a methyl group, an ethyl group, an n-propyl group, or an isopropyl group. Groups, alkyl groups substituted with heteroatoms such as hydroxyethyl group, acetyl group, and acetonyl group, cyclic groups such as cyclohexyl group and phenyl group, or aromatic substituents, and R ₁ and R ₂ are They may be the same or different, and R ₁ and R ₂ may be bonded to each other to form a ring.

  In the general formula (1), n represents 0, 1, or 2, and 1 or 2 is preferable.

  Examples of the compound represented by the general formula (1) include dimethyl sulfoxide, diethyl sulfoxide, methyl ethyl sulfoxide, diphenyl sulfoxide, dimethyl sulfone, methyl ethyl sulfone, methyl-isopropyl sulfone, and methyl-hydroxyethyl sulfone. Can be mentioned.

In the general formula (2), X represents —O—, —N (R ₃ ) —, or —S (O) _m —. R ₃ represents a hydrogen atom or a substituent having 1 to 6 carbon atoms, for example, a linear or branched alkyl group such as methyl group, ethyl group, n-propyl group, isopropyl group, hydroxyethyl group, acetyl group Group, an alkyl group substituted with a hetero atom such as an acetonyl group, a cyclic group such as a cyclohexyl group and a phenyl group, or an aromatic substituent. M represents 0, 1, or 2 and is preferably 1 or 2.

  In the general formula (2), Z represents an atomic group necessary for bonding with X to form a 5- to 6-membered heterocyclic compound. For example, an alkylene group is mentioned, and it may further have a substituent, and may further contain an oxygen atom, a nitrogen atom, or a sulfur atom.

  Examples of the compound represented by the general formula (2) include furan, tetrahydrofuran, pyran, dihydropyran, tetrahydropyran, pyrrole, N-methylpyrrole, pyrrolidine, piperazine, morpholine, imidazole, imidazolidinone, and thiophene. , Tetrahydrothiophene, tetraethylene sulfoxide, sulfolane, γ-butyrolactone, pyrrolidone, N-methylpyrrolidone, N, N′-dimethylimidazolidinone, oxazolidine, oxazolidinone, N-methyloxazolidinone, and the like.

  These compounds include dimethyl sulfoxide, dimethyl sulfone, tetraethylene sulfoxide, sulfolane, tetrahydrofuran, pyran, imidazolidinone, sulfolane, γ-butyrolactone, pyrrolidone, N-methylpyrrolidone, N, N'-dimethylimidazolidinone, N- Methyl oxazolidinone is preferred, with γ-butyrolactone, N-methylpyrrolidone, N, N′-dimethylimidazolidinone, dimethyl sulfoxide, and sulfolane being particularly preferred.

  The content of the compound (A) in the inkjet ink is preferably 3% by mass or more and 30% by mass or less, more preferably 5% by mass or more and 15% by mass or less. If the content of the compound (A) is 3% by mass or more, the scratch resistance to a resin substrate or an inorganic substrate containing no plasticizer is sufficient, and if it is 30% by mass or less, the ink jet head can be used for a long time. The occurrence of abnormality can be suppressed.

  The inkjet ink according to the present invention can contain a non-aqueous solvent, but contains a solvent (B) composed of one or more compounds selected from the compound group represented by the general formulas (3) and (4). It is preferable to do.

In the general formula (3), R ₅ and R ₆ each represent a methyl group or an ethyl group, and OX ₁ represents an oxyethylene group or an oxypropylene group. p represents an integer of 1 to 4.

In the general formula (4), R ₇ and R ₈ each represent a methyl group or an ethyl group, and OX ₂ represents an oxyethylene group or an oxypropylene group. k represents an integer of 1 to 4.

  Specific compounds represented by the general formulas (3) and (4) according to the present invention include, for example, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, triethylene glycol dimethyl ether, triethylene glycol dimethyl ether, Examples include propylene glycol dimethyl ether, ethylene glycol diacetate, and propylene glycol diacetate.

  Among these, the component of the solvent (B) is preferably at least one selected from diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, ethylene glycol diacetate and propylene glycol diacetate, and a plasticizer It is possible to further improve the quick-drying property of ink when printed on a resin base material or inorganic base material that does not contain. Among them, a particularly preferable solvent (B) is one containing diethylene glycol diethyl ether and ethylene glycol diacetate in a ratio of at least 1: 1 to 10: 1.

  The content of the solvent (B) in the ink-jet ink is preferably 50% by mass or more and 90% by mass or less. By adopting such a solvent configuration, a resin substrate or an inorganic substrate that does not contain a plasticizer. In addition to good quick drying and printing stability during printing, the odor of the ink can be reduced.

  In addition to the compound (A) and the solvent (B) according to the present invention, the inkjet ink according to the present invention may contain a conventionally known solvent as long as the object and effects of the present invention are not impaired. Examples of the solvent include alkylene glycol monoalkyl ethers such as diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, and tripropylene glycol monomethyl ether, and alkylenes such as ethylene glycol dibutyl ether and tetraethylene glycol dimethyl ether. Examples include glycol dialkyl ethers and alkylene glycol monoalkyl ether acetates such as ethylene glycol monobutyl ether acetate.

  Next, details of the aggregation promoting liquid according to the present invention will be described.

  The aggregation promoting liquid according to the present invention contains an aggregating agent having an effect of destabilizing the dispersion state of the pigment fine particles and forming an aggregate.

  The compound (A) used in the present invention has an effect of stabilizing even if the dispersed state of the pigment fine particles is destabilized and forms an aggregate, so that the aggregate does not increase excessively and is thereby uniform. Thus, agglomerated particles having a relatively small particle size can be obtained, and adhesion (friction) and gloss are not deteriorated.

  In addition, by quickly mixing the ink and these aggregating agents, aggregation of the pigment fine particles occurs quickly and adheres to the surface of the recording medium. The image failure that gathers in the less likely to occur. For the same reason, sharpness is less likely to deteriorate.

  As the flocculant exhibiting such an action, any compound can be used as long as it has a function of inhibiting the stabilization of the pigment fine particles.

  As a result of intensive studies by the present inventor, it has been found that, among compounds having the above characteristics, water, organic acids, and amine compounds are particularly effective. In addition, polyamines having no polymer side chain (for example, polyallylamine) are also effective. In particular, organic acids and amine compounds have an excellent effect of aggregating pigment fine particles by inhibiting the interaction between the pigment fine particle surface by inhibiting the interaction between the dispersant that stabilizes the pigment fine particles in the dispersed state and the pigment fine particle surface. . In addition, polyamines having polymer side chains are widely used as polymer dispersants, because the polymer side chains have an action of inhibiting the proximity and aggregation of pigments, When used as a flocculant in the present invention, it is preferable to use polyamines having no such side chain.

  Examples of organic acids include acetic acid, propionic acid, dodecanecarboxylic acid, maleic acid, adipic acid, benzoic acid, 2,4-t-amylbenzoic acid, carboxylic acids such as citric acid and phthalic acid, and trifluoromethylsulfonic acid. And sulfonic acids such as benzenesulfonic acid.

  In the case where the organic acid contains an alkyl group having a large molecular weight as a substituent, an organic acid that does not have a substituent having a very large molecular weight is preferable because a dispersion effect may be exhibited. On the other hand, if the molecular weight is too small, the volatility of the flocculant itself becomes a problem. The appropriate molecular weight here refers to a range of about 100 to 200 in general.

  Examples of amines include triethylamine, triethanolamine, octylamine, dodecylamine, ethylenediamine, pyrrolidine, piperidine, dimethylpiperidine, pyridine, DABCO ([2.2.2] diazabicyclooctane), aniline, toluidine and the like. Examples include amines.

  For the same reason as organic acids, amines are also preferably within an appropriate molecular weight range. The appropriate molecular weight here refers to a range of about 100 to 200, as in the case of organic acids.

  As amines, polyamines having no polymer side chain can also be preferably used. Examples of such polyamines include polyallylamine and polypropyleneamine.

  As the organic acid, an aromatic carboxylic acid is preferable. As the amines, tertiary amines and heterocyclic amines are preferable. Polyallylamine is also preferred.

  The aggregation accelerating liquid according to the present invention is constituted by dissolving the aggregating agent in various solvents. The applicable solvent is not limited as long as it dissolves the above-mentioned flocculant, and examples thereof include the solvent (B) according to the present invention. Moreover, the aggregation promotion liquid which concerns on this invention can contain another additive, for example, the compound (A) based on this invention, surfactant, etc. can be added.

  The addition amount of the flocculant is not limited as long as the aggregation effect is exhibited, but is preferably 1% to 30%, and particularly preferably 3 to 10%.

  Next, the fixing resin according to the present invention will be described.

  In the ink-jet ink according to the present invention, various fixing resins (hereinafter also simply referred to as resins) are added in order to improve fixability when recorded on a resin base material or inorganic base material that does not contain a plasticizer.

  Examples of the resin to be added include acrylic resins, polyester resins, polyurethane resins, vinyl chloride resins, vinyl chloride-vinyl acetate copolymer resins, and the like.

  Specifically, acrylic resins such as John Crill (manufactured by Johnson Polymer Co., Ltd.), ESREC P (manufactured by Sekisui Chemical Co., Ltd.), polyester resins such as Elitel (manufactured by Unitika Ltd.) and Byron (manufactured by Toyobo Co., Ltd.), Byron UR ( Toyobo Co., Ltd.), NT-Hilamic (Daiichi Seika Co., Ltd.), Crisbon (Dainippon Ink Chemical Co., Ltd.), Nipporan (Nippon Polyurethane Co., Ltd.) and other polyurethane resins, SOLBIN (Nisshin Chemical Co., Ltd.), Vinyl Blanc (Nissin Chemical Industry Co., Ltd.), Saran Latex (Asahi Kasei Chemicals Co., Ltd.), Sumielite (Sumitomo Chemical Co., Ltd.), Sekisui PVC (Sekisui Chemical Co., Ltd.), UCAR (Dow Chemical Co., Ltd.) Can be mentioned.

  Particularly preferred fixing resins have a number average molecular weight in the range of 10,000 to 30,000, and compositions include vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, vinyl chloride-vinyl acetate- At least one resin selected from vinyl alcohol copolymer and vinyl chloride-vinyl acetate-hydroxyalkyl acrylate copolymer, vinyl chloride-vinyl acetate copolymer and vinyl chloride-vinyl acetate-maleic anhydride copolymer These vinyl chloride-vinyl acetate copolymers and vinyl chloride-vinyl acetate-maleic anhydride copolymers may be mixed with acrylic resins, polyester resins, polyurethane resins, etc. May be used.

  By adding these fixing resins to the ink according to the present invention, the emission stability, abrasion resistance and alcohol resistance can be improved in a well-balanced manner.

  Alcohol wiping resistance refers to the resistance against image peeling when the image surface is wiped with ethanol or a mixed solvent of ethanol and water. User needs to wipe off the image surface with alcohol in posters for outdoor use It is.

  As a method for synthesizing the fixing resin according to the present invention, a suspension polymerization method, an emulsion polymerization method, a solution polymerization method, and the like can be applied without particular limitation. Among them, the solution polymerization method is preferable.

  The solution polymerization method is one of the methods used for radical polymerization of a monomer having a vinyl group. The monomer and initiator are dissolved in a solvent in which the polymer to be generated is soluble, and the polymerization is performed by heating. Is the method.

  The fixing resin synthesized by the solution polymerization method has high solubility even if it has a relatively high molecular weight, and more resin can be contained in the ink, so that the abrasion resistance can be improved.

  The content of the fixing resin in the ink according to the present invention is preferably 1 to 10% by mass. By setting the content to 1% by mass or more, the image weather resistance when recorded on a resin base material or inorganic base material not containing a plasticizer is enhanced, and by setting the content to 10% by mass or less, ink discharge from the ink jet head The range of 3-7 mass% is more preferable.

  Next, the pigment according to the present invention will be described.

  By using a pigment as a coloring material in the non-aqueous inkjet ink according to the present invention, it is possible to improve the weather resistance of a recorded matter recorded on a resin base material or an inorganic base material not containing a plasticizer.

  As the pigment that can be used in the present invention, conventionally known pigments can be used without particular limitation. For example, organic pigments such as insoluble pigments and lake pigments, and inorganic pigments such as carbon black can be preferably used.

  The insoluble pigment is not particularly limited. Dioxazine, thiazole, phthalocyanine, diketopyrrolopyrrole and the like are preferable.

  Specific pigments that can be preferably used include the following pigments.

  Examples of the magenta or red pigment include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 12, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48 (Ca), C.I. I. Pigment red 48 (Mn), C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57 (Ca), C.I. I. Pigment red 57: 1, C.I. I. Pigment red 112, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 168, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. Pigment red 184, C.I. I. Pigment red 202, C.I. I. Pigment red 209, C.I. I. Pigment red 222, C.I. I. Pigment red 254, C.I. I. Pigment violet 19 and the like.

  Examples of the pigment for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 1, C.I. I. Pigment yellow 2, C.I. I. Pigment yellow 3, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 15: 3, C.I. I. Pigment yellow 16, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 73, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 75, C.I. I. Pigment yellow 83, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 95, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 98, C.I. I. Pigment yellow 109, C.I. I. Pigment yellow 110, C.I. I. Pigment yellow 114, C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 129, C.I. I. Pigment yellow 130, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 147, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 154, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185, C.I. I. Pigment yellow 213, C.I. I. And CI Pigment Yellow 214.

  Examples of the pigment for green or cyan include C.I. I. Pigment blue 1, C.I. I. Pigment blue 2, C.I. I. Pigment blue 3, C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 22, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

In addition to the above, when red, green, blue and intermediate colors are required, the following pigments are preferably used alone or in combination. I. Pigment red 209, 224, 177, 194;
C. I. Pigment orange 43;
C. I. Bat violet 3;
C. I. Pigment violet 19, 23, 37;
C. I. Pigment green 36, 7;
C. I. Pigment blue 15: 6;
Etc. are used.

  Examples of black pigments include C.I. I. Pigment black 1, C.I. I. Pigment black 6, C.I. I. Pigment black 7 and the like.

  The content of these pigments in the ink according to the present invention is preferably 2 to 10% by mass. In order to reduce the graininess of the image, a light color ink may be used. In this case, the pigment content is preferably 1/5 to 1/2 with respect to the dark color ink.

  The pigment according to the present invention is preferably used after being dispersed by a disperser together with a dispersant and other necessary additives according to other desired purposes. As the disperser, conventionally known dispersers such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, and a paint shaker can be used.

  The average particle size of the pigment dispersion used in the ink according to the present invention is preferably 10 nm or more and 200 nm or less, and more preferably 50 nm or more and 150 nm or less. By making the average particle size 10 nm or more, aggregation of pigment particles is less likely to occur, and by making the average particle size 200 nm or less, it becomes easy to suppress the phenomenon that the pigment settles when stored over a long period of time. By setting the average particle size in the above range, it becomes easy to obtain an ink having good storage stability.

  The particle size of the pigment dispersion can be measured by a commercially available particle size measuring device using a light scattering method, an electrophoresis method, a laser Doppler method or the like. It is also possible to obtain a particle image with a transmission electron microscope on at least 100 particles and perform statistical processing on the image using image analysis software such as Image-Pro (manufactured by Media Cybernetics). Is possible.

  As the pigment dispersant, a surfactant, a polymer dispersant and the like are used, and a polymer dispersant is preferable. Polymer dispersing agents include (meth) acrylic resins, styrene- (meth) acrylic resins, hydroxyl group-containing carboxylic acid esters, salts of long-chain polyaminoamides and high molecular weight acid esters, salts of high molecular weight polycarboxylic acids, long Salt of chain polyaminoamide and polar acid ester, high molecular weight unsaturated acid ester, modified polyurethane, modified polyacrylate, polyether ester type anionic activator, naphthalenesulfonic acid formalin condensate salt, aromatic sulfonic acid formalin condensate salt, Examples thereof include polyoxyethylene alkyl phosphate ester, polyoxyethylene nonyl phenyl ether, stearylamine acetate, and pigment derivatives.

  Specifically, Jonkrill (manufactured by Johnson Polymer), Anti-Terra-U (manufactured by BYK Chemie), Disperbyk (manufactured by BYK Chemie), Efka (manufactured by Efka CHEMICALS), Floren (manufactured by Kyoeisha Chemical), Disparon (manufactured by Enomoto Kasei Co., Ltd.), Ajisper (manufactured by Ajinomoto Fine Techno Co., Ltd.), Demole (manufactured by Kao Corporation), Homogenol, Emulgen (manufactured by Kao Corporation), Solspers (manufactured by Avicia), Nikkor (manufactured by Nikko Chemical Co., Ltd.), etc. Is mentioned.

  The content of the dispersant in the inkjet ink according to the present invention is preferably 10 to 200% by mass with respect to the pigment. By setting the content to 10% by mass or more, the pigment dispersion stability is enhanced, and by setting the content to 200% by mass or less, the ink ejection from the inkjet head is easily stabilized.

  In the ink-jet ink according to the present invention, in addition to the above description, if necessary, according to the purpose of improving the emission stability, print head and ink cartridge compatibility, storage stability, image storage stability, and other various performances, Various known additives such as a viscosity modifier, a specific resistance modifier, a film forming agent, an ultraviolet absorber, an antioxidant, a discoloration inhibitor, an antifungal agent, and a rust inhibitor can be appropriately selected and used. .

  The inkjet head used when forming an image by discharging the inkjet ink and the aggregation accelerator constituting the inkjet set of the present invention may be an on-demand system or a continuous system. In addition, as a discharge method, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electro-thermal conversion method (for example, thermal ink jet) Any ejection method such as a mold, a bubble jet (registered trademark) mold, or the like may be used.

  In the ink jet recording method using the ink jet ink set of the present invention, for example, the ink and the aggregation promoting liquid are ejected from the ink jet head based on the digital signal by an ink jet printer loaded with the ink jet ink and the aggregation accelerator, and the recording medium is discharged. By adhering, an ink jet recording image is obtained. In order to quickly and surely dry the ink adhered to the recording medium, a method of forming an image by increasing the surface temperature of the recording medium is preferable.

  The surface temperature is adjusted according to the durability of the recording medium and the drying properties of the ink used and the aggregation accelerator, but is preferably 40 to 100 ° C. Increasing the surface temperature improves the wettability of the ink and the aggregation accelerator with respect to the surface of the recording medium. Therefore, it is preferable to increase the surface temperature for recording.

  When recording is performed by increasing the surface temperature of the recording medium, it is preferable to mount a heater on the ink jet recording apparatus, and by heating the recording medium before or during transport of the recording medium, the surface temperature of the recording medium alone by the ink jet recording apparatus Can be adjusted.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

  Further, the pigment dispersant and fixing resin described below were used after diluting the low boiling point solvent by distillation under reduced pressure and diluting with an organic solvent used for pigment dispersion so that the solid content was 20% by mass. Hereinafter, the amounts of the pigment dispersant and the fixing resin used are shown in terms of solid content.

<Preparation of ink>
[Preparation of Ink 1]
(Preparation of pigment dispersion 1)
C. I. 10 parts of Pigment Red 122 (hereinafter abbreviated as PR122), 5 parts of Solsperz 24000 (manufactured by Noveon) which is a pigment dispersant, 1 part of dimethyl sulfoxide (S-1) as a compound (A), solvent (B ) And 64 parts of diethylene glycol diethyl ether and 20 parts of ethylene glycol diacetate are mixed and dispersed using a horizontal bead mill (system zeta mini manufactured by Ashizawa) filled with zirconia beads having a diameter of 0.5 mm at a volume ratio of 60%. Thereafter, the zirconia beads were removed to obtain a pigment dispersion 1.

(Preparation of resin solution 1)
1 part of dimethyl sulfoxide as the compound (A), 69 parts of diethylene glycol diethyl ether as the solvent (B), 20 parts of ethylene glycol diacetate, and vinyl chloride-vinyl acetate copolymer (trade name VYHD, A resin solution 1 was prepared by mixing and dissolving 10 parts of Dow Chemicals).

(Preparation of ink)
While stirring 50 parts of the resin solution 1, 50 parts of the pigment dispersion 1 was mixed and then filtered through a 0.8 μm filter to obtain ink 1.

[Preparation of inks 2 to 19]
In the preparation of the ink 1, the pigment type, the fixing resin type, the type and addition amount of the compound (A), the type and addition amount of the solvent (B), the type and addition amount of other solvents are as shown in Table 1. Inks 2 to 15 were prepared in the same manner except that the changes were made.

  In addition, the detail of each additive described by the abbreviation in Table 1 is as follows. Moreover, the numerical value of content of Table 1 is the mass%.

<Pigment>
PB15: 3; C.I. I. Pigment Blue 15: 3
PY150; C.I. I. Pigment Yellow 150
PR122; C.I. I. Pigment Red 122
C. B. Carbon black <Compound (A)>
S-1: Dimethylsulfoxide S-2: Sulfolane S-3: γ-butyrolactone S-4: N-methylpyrrolidone S-5: N, N′-dimethylimidazolidinone <Solvent (B)>
DEGDEE: Diethylene glycol diethyl ether EGDAc: Ethylene glycol diacetate <Other solvents>
EGBEAc: ethylene glycol monobutyl ether acetate << Preparation of aggregation promoter >>
[Preparation of aggregation promoting liquids 1 to 5]
The compound (A) described in Table 2, a solvent, and an aggregating agent were mixed to prepare aggregation promoting liquids 1 to 5.

<Evaluation of ink set>
Each ink prepared above and each aggregation promoting liquid were combined to prepare ink sets shown in Table 3. Using this, images 1 to 22 were formed according to the following method.

[Image formation]
Mounted with a piezo-type head having a nozzle diameter of 28 μm, a driving frequency of 10 kHz, a nozzle number of 512, a minimum liquid amount of 14 pl, and a nozzle density of 180 dpi (in this invention, dpi represents the number of dots per 2.54 cm), Each ink and the aggregation accelerating liquid were loaded into an on-demand type ink jet printer equipped with a heater having a maximum recording density of 1440 × 1440 dpi. A4 size polyvinyl chloride was used on the recording medium, and the aggregation promoting liquid and each ink were ejected, and a solid image of 20 cm × 25 cm and characters of “melancholy” were recorded at 4, 6, and 10 point character sizes. . During printing, the recording medium was heated from the back side, and the heater temperature was set so that the surface temperature of the recording medium during image recording was 45 ° C. The surface temperature of the recording medium was measured using a non-contact thermometer (IT-530N type, manufactured by Horiba, Ltd.).

<Evaluation of formed image>
[Evaluation of image]
According to the said method, the created images 1-22 were evaluated according to the following method. In all cases, the performance of Δ or higher was regarded as an acceptable level.

<Evaluation of quick drying>
After image recording, the solid image surface was rubbed with a finger, and quick drying property was evaluated according to the following criteria.

A: The time until an image cannot be taken even if it is rubbed with a finger is less than 3 minutes immediately after image recording. ○: The time until an image is not taken even if rubbed with a finger is 3 minutes or more and 4 minutes after the image is recorded. Less than △: The time until the image can not be taken even if it is rubbed with a finger is 4 minutes or more and less than 5 minutes immediately after the image is recorded. <Evaluation of set-off resistance>
Using each ink set, a solid image was formed on A4 size polyvinyl chloride, and 10 sheets of this polyvinyl chloride were overlaid and allowed to stand overnight at room temperature. On the next day, the polyvinyl chloride was peeled off, and the surface (back surface) opposite to each image forming surface was visually observed, and the set-off resistance was evaluated according to the following criteria.

◎: There is no show-off of the image in any polyvinyl chloride. ○: Only one piece of the polyvinyl chloride confirmed to be set off. △: Two or three pieces of polyvinyl chloride confirmed to be set off. ×: 4 Alignment was confirmed with more than one sheet of polyvinyl chloride <Evaluation of sharpness>
It was confirmed whether or not the “melancholy” character recorded at each character size was visually distinguishable by 10 subjects from a distance of 30 cm, and the sharpness of the image was evaluated according to the following criteria.

A: More than half of 10 subjects can be discriminated up to 4 points. ○: More than half of 10 subjects can be discriminated up to 6 points. Δ: More than half of 10 subjects can be discriminated up to 10 points. More than half of 10 subjects cannot be identified even with 10 points <Evaluation of scratch resistance>
After image recording, the solid image surface left overnight at room temperature was rubbed with dry cotton and scratch resistance was evaluated according to the following criteria.

A: The image hardly changes even after rubbing 50 times or more. ○: Slight scratches remain at the stage of rubbing 50 times, but the image density is hardly affected. Δ: The image density decreases during rubbing 20 to 50 times. : Image density decreases while rubbing less than 20 times. The results obtained above are shown in Table 3.

  As is apparent from the results shown in Table 3, it can be seen that the image recorded using the ink set defined in the present invention is excellent in all items of drying property, set-off, sharpness, and scratch resistance. . Further, when the surface gloss of these images was visually confirmed, all of them had sufficient gloss.

  On the other hand, the image recorded using the comparative ink set was inferior in any or all of the above items, and the surface gloss was insufficient.

Claims (10)

A non-aqueous inkjet ink containing at least a pigment, a fixing resin, and a compound (A) composed of one or more compounds selected from the group of compounds represented by the following general formulas (1) and (2), and at least a flocculant An ink-jet ink set comprising an aggregation promoting liquid.
General formula (1)
R ₁ —S (O) _n —R ₂
[Wherein, R ₁ and R ₂ each represent a substituent having 1 to 6 carbon atoms, and n represents 0, 1, or 2. ]

[Wherein, X represents —O—, —N (R ₃ ) — or —S (O) _m —. R ₃ represents a hydrogen atom or a substituent having 1 to 6 carbon atoms, and m represents 0, 1, or 2. Z represents an atomic group necessary for binding to X to form a 5- or 6-membered heterocyclic compound. ] The inkjet ink set according to claim 1, wherein the flocculant is water. The inkjet ink set according to claim 1, wherein the flocculant is an organic acid. The inkjet ink set according to claim 1, wherein the flocculant is an amine. 5. The inkjet ink set according to claim 1, wherein the content of the compound (A) in the non-aqueous inkjet ink is 3% by mass or more and 30% by mass or less. The said non-aqueous inkjet ink contains the solvent (B) which consists of 1 or more types of compounds chosen from the compound group represented by following General formula (3) and (4). The inkjet ink set as described.
General formula (3)
R ₅ — (OX ₁ ) _p —O—R ₆
[Wherein, R ₅ and R ₆ each represent a methyl group or an ethyl group, and OX ₁ represents an oxyethylene group or an oxypropylene group. p represents an integer of 1 to 4. ]

[Wherein, R ₇ and R ₈ each represent a methyl group or an ethyl group, and OX ₂ represents an oxyethylene group or an oxypropylene group. k represents an integer of 1 to 4. ] The inkjet ink set according to claim 6, wherein the content of the solvent (B) in the non-aqueous inkjet ink is 50% by mass or more and 90% by mass or less. The solvent (B) is at least one selected from diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, ethylene glycol diacetate, and propylene glycol diacetate. The inkjet ink set as described. The fixing resin contained in the non-aqueous inkjet ink has a vinyl chloride-vinyl acetate copolymer and a vinyl chloride-vinyl acetate-maleic anhydride copolymer having a number average molecular weight in the range of 10,000 to 30,000. It is at least 1 sort (s) chosen from a vinyl chloride-vinyl acetate-vinyl alcohol copolymer and a vinyl chloride-vinyl acetate-hydroxyalkyl acrylate copolymer, The any one of Claims 1-8 characterized by the above-mentioned. Inkjet inkjet ink set. An ink-jet recording method comprising performing image recording using the ink-jet ink set according to claim 1.