JP2008303235A - Non-aqueous ink jet ink, its manufacturing method, and ink jet recording method using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-aqueous ink jet ink excellent in working safety, being free from the problem of odor, excellent in drying property after recording and capable of recording an image having sharp and sufficient rubbing-resistant property, even when a resin base material not containing a plasticizer or a non-absorbing inorganic base material is used as a recording medium, and to provide its manufacturing method and an ink jet recording method using it. <P>SOLUTION: The non-aqueous ink jet ink recorded on the recording medium making the resin base material not containing the plasticizer or the non-absorbing inorganic base material as a constitution element contains a pigment, a fixing resin, and a compound selected from the group consisting of the compounds represented by a specific structural formula. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a non-aqueous inkjet ink, a method for producing the same, and an inkjet recording method using the same.

  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 a plurality of inkjet inks, such as a hot melt ink that heats and melts solid ink for printing, and an actinic ray curable ink that is cured by actinic rays such as light after printing.

  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 an ink jet ink to be used, a non-aqueous ink containing a large amount of cyclohexanone or the like has been conventionally used. For example, an ink jet ink containing cyclohexanone is disclosed ( 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 inks characterized by not containing cyclohexanone have been developed and sold. For example, as a solvent for dissolving polyvinyl chloride, a non-aqueous ink containing a solvent such as N-methylpyrrolidone or amide is disclosed in place of cyclohexanone having the above-described problems (Patent Document 2,). 3). Also, non-aqueous inks to which a fixing resin such as vinyl chloride-vinyl acetate copolymer or acrylic is added for the purpose of improving image fastness such as scratch resistance are disclosed (see Patent Documents 4 and 5). 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.

A large amount of plasticizer is added to soft polyvinyl chloride for the purpose of ensuring the flexibility of the substrate. In general, phthalic acid ester compounds, adipic acid ester compounds, and the like are used as plasticizers, but solvents such as cyclohexanone and N-methylpyrrolidone are characterized by high affinity with these plasticizers. Due to this feature, it has been found that a recorded image with good image quality can be formed on soft polyvinyl chloride by a non-aqueous inkjet ink containing these solvents. However, when resin materials that do not contain these plasticizers are used as recording media, the affinity between the solvent and the substrate is poor, so the scratch resistance of the resulting image is less than when soft polyvinyl chloride is used. It has been found that it has the disadvantage of being greatly reduced. Further, it has been clarified that the image sharpness and drying performance are also greatly reduced. Therefore, there is an ink jet recording method for recording a sharp and sufficient scratch-resistant image when a resin base material that does not contain a plasticizer or an inorganic base material such as a glass plate is used. The current situation does not exist yet.
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

  The present invention has been made in view of the above-described problems and situations, and the problem to be solved is when a non-absorbable inorganic base material such as a resin base material or a glass plate containing no plasticizer is used as a recording medium. , Non-water-based inkjet ink capable of recording images having excellent work safety, no odor problems, excellent drying properties after recording, and sharp and sufficient scratch resistance, a method for producing the same, and use thereof An inkjet recording method is provided.

  As a result of various studies on the non-aqueous ink-jet ink, the present inventor has found that the conventionally known non-aqueous ink-jet ink containing a solvent such as N-methylpyrrolidone and amide is included in the soft polyvinyl chloride used as a base material. It has been found that it has excellent recording properties for soft polyvinyl chloride because of its excellent compatibility with plasticizers. However, due to its characteristics, it is not suitable for resin base materials that do not contain a plasticizer, for example, resin base materials such as ABS resin and PC resin, or inorganic base materials such as glass plates and metal plates. It was found to be inferior in property, scratch resistance and drying.

  On the other hand, the present inventors have studied various solvents and combinations thereof in view of the above problems, and as a result, the sulfoxide represented by the general formula (1), the sulfone represented by (2), and (3 The combination of one or more compounds (A) selected from the group of urea compounds represented by) and a non-aqueous inkjet ink containing a pigment and a fixing resin, and a substrate that does not contain a plasticizer, provides excellent drying properties. The present inventors have found a means for providing a non-aqueous ink jet ink capable of giving a sharp image and forming an image excellent in scratch resistance, a method for producing the same, and an ink jet recording method using the same.

  That is, the said subject which concerns on this invention is solved by the following means.

  1. A non-aqueous ink jet ink for recording on a recording medium comprising a resin base material containing no plasticizer or a non-absorbing inorganic base material, comprising a pigment, a fixing resin, and the following general formula (1), ( A non-aqueous inkjet ink comprising a compound (A) selected from the compound group represented by 2) and (3).

[Wherein, R ₁ and R ₂ each represent a substituent having 1 to 6 carbon atoms, and R ₁ and R ₂ may be bonded to form a ring. ]

[Wherein, R ₃ and R ₄ each represent a substituent having 1 to 6 carbon atoms, and R ₃ and R ₄ may be bonded to form a ring. ]

[Wherein R ₅ , R ₆ , R ₇ and R ₈ represent a hydrogen atom or a substituent having 1 to 6 carbon atoms, and any two or more of R ₅ , R ₆ , R ₇ and R ₈ are substituted. A group may be bonded to form a ring. ]
2. The recording medium is composed of a resin selected from ABS resin, PET resin, PC resin, POM resin, PA resin, PI resin, hard PVC resin not containing plasticizer, acrylic resin, PE resin, and PP resin. 2. The non-aqueous ink-jet ink as described in 1 above, characterized by comprising:

  3. The recording medium according to the item 1 or 2, wherein the recording medium has a resin selected from an ABS resin, a PET resin, a PC resin, a PA resin, a hard PVC resin not containing a plasticizer, and an acrylic resin. The non-aqueous inkjet ink according to 2.

  4). 2. The non-aqueous inkjet ink according to 1 above, wherein the recording medium has a non-absorbing inorganic base material as a constituent element.

  5. 5. The non-aqueous inkjet ink according to 1 or 4 above, wherein the non-absorbing inorganic base material includes an inorganic base material selected from a glass plate, a metal plate, and a ceramic plate as a constituent element. .

  6). Content of the said compound (A) is 3-30 mass%, The non-aqueous inkjet ink as described in any one of said 1-5 characterized by the above-mentioned.

  7. The non-aqueous inkjet ink according to any one of 1 to 6 above, which contains a compound selected from the group of compounds represented by the following general formulas (4) and (5) as a solvent (B).

[Wherein, R ₉ and R ₁₀ each represent a methyl group or an ethyl group, and OX ₁ represents an oxyethylene group or an oxypropylene group. ]

[Wherein, R ₁₁ and R ₁₂ each represent a methyl group or an ethyl group, and OX ₂ represents an oxyethylene group or an oxypropylene group. ]
8). Content of the said solvent (B) is 50-90 mass%, The non-aqueous inkjet ink as described in any one of said 1-7 characterized by the above-mentioned.

  9. Any of 1 to 8 above, wherein the solvent (B) contains a compound selected from diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, ethylene glycol diacetate, and propylene glycol diacetate. The non-aqueous inkjet ink as described in any one of Claims 1-3.

  10. The fixing resin is a vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, vinyl chloride-vinyl acetate-vinyl alcohol having a number average molecular weight in the range of 10,000 to 30,000. 10. The non-aqueous inkjet ink according to any one of 1 to 9 above, which contains a resin selected from a copolymer and a vinyl chloride-vinyl acetate-hydroxyalkyl acrylate copolymer.

  11. A method for producing a non-aqueous inkjet ink, wherein the non-aqueous inkjet ink according to 1 to 10 is produced.

  12 An ink jet recording method for recording on a recording medium comprising a resin base material containing no plasticizer or a non-absorbing inorganic base material, wherein the non-aqueous ink jet ink described in 1 to 10 is used. Inkjet recording method.

  13. 13. The inkjet recording method described in 12 above, wherein the recording medium is heated during recording.

  14 14. The ink jet recording method according to item 13, wherein the surface temperature of the recording medium when the recording medium is heated is 40 to 100 ° C.

  According to the above-mentioned means of the present invention, when a non-absorbable inorganic substrate such as a glass plate or a resin substrate containing no plasticizer is used as a recording medium, it is excellent in work safety, has no odor problem, and recorded. It is possible to provide a non-aqueous ink jet ink which is excellent in later drying properties, can record a sharp and sufficient scratch-resistant image, a method for producing the same, and an ink jet recording method using the same.

  The non-aqueous ink-jet ink of the present invention is a non-aqueous ink-jet ink for recording on a recording medium comprising a resin base material that does not contain a plasticizer or a non-absorbing inorganic base material, and includes a pigment, a fixing resin, And a compound (A) selected from the compound group represented by the general formulas (1), (2) and (3). This feature is a technical feature common to the inventions according to claims 1 to 14.

  In addition, although it is not clear about the action mechanism of this invention, it estimates as follows.

  The non-aqueous inkjet ink used in the present invention is characterized by containing one or more compounds selected from the compound group represented by the general formulas (1), (2), and (3). The compound is characterized by being aprotic and highly polar. Due to this feature, it is considered that even if the base material does not contain a plasticizer, it interacts with the polar partial structure of the molecules constituting the base material. Such polar interaction between the solvent and the substrate can facilitate the orientation of the polar partial structure of the pigment, dispersant, and fixing resin into the polar partial structure of the substrate, so that the pigment, dispersant, and fixing resin As a result, the pigment, the dispersant, and the fixing resin can be firmly bonded to the substrate even if the solvent is absorbed or evaporated in the substrate. Therefore, as a result, it is considered that a sharp image can be formed, the scratch resistance is excellent, and sufficient drying property is given.

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

(Non-aqueous inkjet ink)
The non-aqueous ink-jet ink of the present invention comprises a pigment, a fixing resin, and a compound (A) selected from the compound group represented by the general formulas (1), (2) and (3). . Hereinafter, the configuration of the non-aqueous inkjet ink of the present invention will be specifically described.

<Compound (A)>
In the non-aqueous inkjet ink of the present invention (hereinafter also referred to as “inkjet ink” or simply “ink”), one kind selected from the sulfoxides represented by the general formulas (1) and (2) or the sulfone compound group. It contains a compound (A) composed of the above compounds.

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 hetero atoms such as hydroxyethyl group, acetoxyethyl group, dimethylaminoethyl group, methylsulfinylpropyl group, cyclic groups such as cyclohexyl group, phenyl group, or aromatic substituents. Furthermore, R ₁ and R ₂ 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 (2), R ₃ and R ₄ 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 hetero atoms such as hydroxyethyl group, acetoxyethyl group, dimethylaminoethyl group, methylsulfinylpropyl group, cyclic groups such as cyclohexyl group, phenyl group, or aromatic substituents. R ₃ and R ₄ may be the same or different, and R ₃ and R ₄ may be bonded to each other to form a ring.

  Examples of the compound represented by the general formulas (1) and (2) include dimethyl sulfoxide, diethyl sulfoxide, methyl ethyl sulfoxide, diphenyl sulfoxide, tetraethylene sulfoxide, dimethyl sulfone, methyl ethyl sulfone, and methyl-isopropyl sulfone. , Methyl-hydroxyethyl sulfone, sulfolane and the like.

In the general formula (3), R ₅ , R ₆ , R ₇ and R ₈ each represent a hydrogen atom or a substituent having 1 to 6 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group. A linear or branched alkyl group such as, an alkyl group substituted with a heteroatom such as a hydroxyethyl group, an acetoxyethyl group, a dimethylaminoethyl group, a methylsulfinylpropyl group, a cyclohexyl group, a cyclic group such as a phenyl group, or Aromatic substituents and the like, and R ₅ , R ₆ , R ₇ , and R ₈ may be the same or different, and any one of R ₅ , R ₆ , R ₇ , and R ₈ Two or more substituents may be bonded to form a ring.

  Examples of the compound represented by the general formula (3) include N, N-dimethylurea, N, N′-dimethylurea, tetramethylurea, N, N′-diethylurea, N-cyclohexylurea, Examples include imidazolidinone and N, N′-dimethylimidazolidinone.

  As these compounds, dimethyl sulfoxide, diethyl sulfoxide, tetraethylene sulfoxide, dimethyl sulfone, sulfolane, N, N′-dimethylimidazolidinone are preferable, and dimethyl sulfoxide, sulfolane, and N, N′-dimethylimidazolidinone are particularly preferable. .

  The content of the compound (A) in the inkjet ink is preferably 3 to 30% by mass, and more preferably 5 to 15% by mass. When the content of the compound (A) is 3% by mass or more, the scratch resistance against a resin base material or an inorganic base material not containing a plasticizer becomes sufficiently good. It does not cause an abnormal phenomenon of the inkjet head.

<Solvent (B)>
The inkjet ink of 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 (4) and (5). It is preferable.

In the general formula (4), R ₉ and R ₁₀ each represent a methyl group or an ethyl group, and OX ₁ represents an oxyethylene group or an oxypropylene group.

In the general formula (5), R ₁₁ and R ₁₂ each represent a methyl group or an ethyl group, and OX ₂ represents an oxyethylene group or an oxypropylene group.

  Specific compounds represented by the general formulas (4) and (5) according to the present invention include, for example, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, ethylene glycol diacetate, propylene Examples thereof include 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 to 90% by mass. By using such a solvent configuration, the speed of printing on a resin base material or inorganic base material that does not contain a plasticizer. In addition to good dryness and emission stability, the odor of the ink can be reduced.

  In the inkjet ink of the present invention, in addition to the compound (A) and the solvent (B) according to the present invention, a conventionally known solvent may be contained within a range that does not impair the object effects of the present invention. 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 alkylene glycols such as ethylene glycol dibutyl ether and tetraethylene glycol dimethyl ether. Examples include dialkyl ethers and alkylene glycol monoalkyl ether acetates such as ethylene glycol monobutyl ether acetate.

<Fixing resin>
In the ink-jet ink of 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. The

  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 (Nihon Polyurethane Co., Ltd.), etc. (Nissin Chemical 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 the composition is vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, vinyl chloride-vinyl acetate-vinyl. And at least one resin selected from an alcohol copolymer and a vinyl chloride-vinyl acetate-hydroxyalkyl acrylate copolymer, and a vinyl chloride-vinyl acetate copolymer and a vinyl chloride-vinyl acetate-maleic anhydride copolymer. They may be used as a mixture. Furthermore, 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 of the present invention, the emission stability, abrasion resistance and alcohol resistance can be improved in a 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 of 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.

<Pigment>
By using a pigment as a coloring material in the non-aqueous ink jet ink of the present invention, the weather resistance of a recorded matter recorded on a resin base material or an inorganic base material not containing a plasticizer can be improved.

  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, for example, azo, azomethine, methine, diphenylmethane, triphenylmethane, quinacridone, anthraquinone, perylene, indigo, quinophthalone, isoindolinone, isoindoline, azine, oxazine, thiazine, 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 178, C.I. I. Pigment red 184, C.I. I. Pigment red 202, 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, 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 23, 37;
C. I. Pigment green 36;
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 of 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 of the present invention is preferably 10 to 200 nm, and more preferably 50 to 150 nm. 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.), Azisper (manufactured by Ajinomoto Fine-Techno Co., Ltd.), Demole (manufactured by Kao Corporation), Homogenol, Emulgen (manufactured by Kao Corporation), Solspurs (manufactured by Avicia), Nikkor (manufactured by Nikko Chemical Co., Ltd.), etc. Is mentioned.

  The content of the dispersant in the inkjet ink of 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.

<Other additives>
In addition to the above description, the inkjet ink of the present invention is publicly known depending on the purpose of improving the emission stability, print head and ink cartridge compatibility, storage stability, image storage stability, and other various performances as necessary. Various 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.

(recoding media)
The recording medium used in the present invention is a recording medium comprising a resin base material containing no plasticizer or a non-absorbing inorganic base material as a constituent element. The recording medium can be used by using the following various base materials as a constituent element, one kind of base material alone, or a combination of plural kinds of base materials. Hereinafter, various base materials will be described.

<Resin base material not containing plasticizer>
Examples of the resin base material containing no plasticizer used in the present invention include ABS resin, polycarbonate (PC) resin, polyacetal (POM) resin, polyamide (PA) resin, polyethylene terephthalate (PET) resin, and polyimide (PI) resin. , Acrylic resin, polyethylene (PE) resin, polypropylene (PP) resin, hard polyvinyl chloride (PVC) resin containing no plasticizer, and the like.

  These resins are characterized by not containing a plasticizer, but there are no particular restrictions on other properties such as thickness, shape, color, softening temperature, and hardness.

  The recording medium used in the present invention is preferably ABS resin, PET resin, PC resin, POM resin, PA resin, PI resin, hard PVC resin not containing a plasticizer, acrylic resin, PE resin, and PP resin. More preferred are ABS resin, PET resin, PC resin, PA resin, hard PVC resin not containing plasticizer, and acrylic resin.

<Non-absorbable inorganic substrate>
Examples of the non-absorbing inorganic base material used in the present invention include a glass plate, a metal plate such as iron or aluminum, and a ceramic plate. These inorganic substrates are characterized by not having an ink-absorbing layer on the surface. These non-absorbing inorganic base materials are not particularly limited with respect to other properties such as thickness, shape, color, softening temperature, and hardness.

(Inkjet recording method)
The ink-jet head used when forming an image by discharging the ink-jet ink 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 of the present invention, for example, an ink jet recorded image is obtained by ejecting ink from an ink jet head based on a digital signal and adhering it to a recording medium by a printer loaded with the ink jet ink. . 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 property of the ink used, but is preferably 40 to 100 ° C. Increasing the surface temperature improves ink wettability with respect to the surface of the recording medium, so 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, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. 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 dispersion so that the solid content was 20% by mass. Hereinafter, the amount of the pigment dispersant and the fixing resin used is a solid content conversion value.

<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) as a pigment dispersant, 1 part of dimethyl sulfoxide (S-1) as a compound (A), solvent As (B), 64 parts of diethylene glycol diethyl ether and 20 parts of ethylene glycol diacetate were mixed and dispersed using a horizontal bead mill (System Zetamini manufactured by Ashizawa Co., Ltd.) filled with zirconia beads having a diameter of 0.5 mm at a volume ratio. 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 and 20 parts of ethylene glycol diacetate as the solvent (B), and vinyl chloride-vinyl acetate copolymer (trade name VYHD, Dow) as the fixing resin A resin solution 1 was prepared by mixing and dissolving 10 parts of 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 21 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. In addition, the numerical value of content described in Table 1 is 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 [Fixing resin]
PVC: Vinyl chloride-vinyl acetate copolymer (trade name VYHD, manufactured by Dow Chemicals)
Acrylic: butyl methacrylate-methyl methacrylate copolymer (trade name DEGLAN P24, manufactured by Degussa)
[Compound (A)]
S-1: Dimethyl sulfoxide S-2: Di-n-propyl sulfoxide S-3: Tetramethylene sulfoxide S-4: Dimethyl sulfone S-5: Methyl isopropyl sulfone S-6: Sulfolane S-7: Tetramethylurea S- 8: N, N′-dimethylimidazolidinone [solvent (B)]
DEGDEE: Diethylene glycol diethyl ether EGDAc: Ethylene glycol diacetate [Other solvents]
EGBEAc: ethylene glycol monobutyl ether acetate NMP: N-methylpyrrolidone << Evaluation of ink >>
For each of the inks prepared above, images 1-41 were formed according to the following method using the combinations of ink and recording medium shown in Table 2, and each evaluation was performed.

[Image formation]
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 (“dpi” represents the number of dots per 2.54 cm) is mounted, and the maximum recording density is mounted. Each ink was loaded into an on-demand type ink jet printer equipped with a heater of 1440 × 1440 dpi. Next, each ink was ejected, and a solid image of 10 cm × 10 cm was recorded on each recording medium. 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 odor resistance]
In a closed room of 3 m wide, 2 m deep, and 2 m high, the above-mentioned image formation was continuously performed on 20 recording media, and then odor evaluation was performed by 10 subjects. The case where it was determined that the odor was almost odorless was assigned 5 points, and the case where it was determined that the odor was very unpleasant was assigned 1 point. The odor resistance was evaluated according to the following criteria.

A: The average score of 10 subjects is 4.0 points or more. ○: The average score of 10 subjects is 3.0 points or more and less than 4.0 points. Δ: The average score of 10 subjects is 2.0 points or more and less than 3.0 points x: The average score of 10 subjects is less than 2.0 points.

<Evaluation of formed image>
[Evaluation of image]
According to the said method, the created images 1-41 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 recording an image on polyvinyl chloride, the solid image was rubbed with a finger and the quick drying property was evaluated according to the following criteria.

A: The time when the image cannot be taken even after rubbing with a finger is less than 3 minutes immediately after image recording. ○: The time when the image is not taken even after rubbing with the finger is 3 minutes or more and less than 4 minutes immediately after image recording. The time when the image cannot be taken even after rubbing is 4 minutes or more and less than 5 minutes immediately after the image recording. X: The time when the image cannot be taken even if rubbing with a finger takes 5 minutes or more immediately after the image recording.

<Evaluation of scratch resistance>
The surface of the image recorded on polyvinyl chloride was rubbed with dry cotton, and scratch resistance was evaluated according to the following criteria.

◎: Image hardly changes even after rubbing 50 times or more ○: Slight scratch remains at the stage of rubbing 50 times, but hardly affects the image density Δ: 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 clear from the results shown in Table 3, the ink having the configuration defined in the present invention has a quick drying property when images are recorded on various recording media containing no odor or plasticizer compared to the comparative example. In addition, it can be seen that all the properties of image abrasion resistance are excellent.

Claims (14)

A non-aqueous ink jet ink for recording on a recording medium comprising a resin base material containing no plasticizer or a non-absorbing inorganic base material, comprising a pigment, a fixing resin, and the following general formula (1), ( A non-aqueous inkjet ink comprising a compound (A) selected from the compound group represented by 2) and (3).

[Wherein, R ₁ and R ₂ each represent a substituent having 1 to 6 carbon atoms, and R ₁ and R ₂ may be bonded to form a ring. ]

[Wherein, R ₃ and R ₄ each represent a substituent having 1 to 6 carbon atoms, and R ₃ and R ₄ may be bonded to form a ring. ]

[Wherein R ₅ , R ₆ , R ₇ and R ₈ represent a hydrogen atom or a substituent having 1 to 6 carbon atoms, and any two or more of R ₅ , R ₆ , R ₇ and R ₈ are substituted. A group may be bonded to form a ring. ] The recording medium is composed of a resin selected from ABS resin, PET resin, PC resin, POM resin, PA resin, PI resin, hard PVC resin not containing plasticizer, acrylic resin, PE resin, and PP resin. The non-aqueous inkjet ink according to claim 1, wherein the non-aqueous inkjet ink is provided. 2. The recording medium has a resin selected from an ABS resin, a PET resin, a PC resin, a PA resin, a hard PVC resin not containing a plasticizer, and an acrylic resin as its constituent elements. Or the non-aqueous inkjet ink of 2. The non-aqueous inkjet ink according to claim 1, wherein the recording medium has a non-absorbing inorganic base material as a constituent element. 5. The non-aqueous inkjet according to claim 1, wherein the non-absorbing inorganic base material includes an inorganic base material selected from a glass plate, a metal plate, and a ceramic plate as a constituent element thereof. ink. 6. The non-aqueous inkjet ink according to claim 1, wherein the content of the compound (A) is 3 to 30% by mass. The non-aqueous inkjet ink according to any one of claims 1 to 6, comprising a compound selected from the group of compounds represented by the following general formulas (4) and (5) as a solvent (B).

[Wherein, R ₉ and R ₁₀ each represent a methyl group or an ethyl group, and OX ₁ represents an oxyethylene group or an oxypropylene group. ]

[Wherein, R ₁₁ and R ₁₂ each represent a methyl group or an ethyl group, and OX ₂ represents an oxyethylene group or an oxypropylene group. ] The non-aqueous inkjet ink according to claim 1, wherein the content of the solvent (B) is 50 to 90% by mass. 9. The solvent according to claim 1, wherein the solvent (B) contains a compound selected from diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, ethylene glycol diacetate, and propylene glycol diacetate. The non-aqueous inkjet ink as described in any one of Claims. The fixing resin is a vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, vinyl chloride-vinyl acetate-vinyl alcohol having a number average molecular weight in the range of 10,000 to 30,000. The non-aqueous inkjet ink according to any one of claims 1 to 9, further comprising a resin selected from a copolymer and a vinyl chloride-vinyl acetate-hydroxyalkyl acrylate copolymer. A method for producing a non-aqueous ink-jet ink, wherein the non-aqueous ink-jet ink according to claim 1 is produced. An ink jet recording method for recording on a recording medium comprising a resin base material containing no plasticizer or a non-absorbing inorganic base material, wherein the non-aqueous ink jet ink according to claim 1 is used. An inkjet recording method. The ink jet recording method according to claim 12, wherein the recording medium is heated during recording. 14. The ink jet recording method according to claim 13, wherein the surface temperature of the recording medium when the recording medium is heated is 40 to 100 [deg.] C.