JP2008274034A - Nonaqueous inkjet ink and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous inkjet ink having favorable printability (scratch resistance, resistance to wiping with an alcohol) for polyvinyl chloride, excellent in ejection stability, safety and storage stability, free of the problem of odor and usable stably even in use of a prolonged period, and to provide an inkjet recording method using it. <P>SOLUTION: In the nonaqueous inkjet ink consisting at least of a pigment, a fixing resin and an organic solvent, the fixing resin is polyvinyl chloride or a polymer obtained by the copolymerization of vinyl chloride and a monomer other than vinyl chloride, and further a dehydrochlorination preventing agent for polyvinyl chloride or its copolymer is contained in the ink. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a novel non-aqueous inkjet ink and inkjet recording method.

  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.

  As the ink-jet ink used in such an ink-jet recording method, water-based ink mainly containing water, non-volatile solvent which does not volatilize at room temperature, oil-based ink which does not substantially contain water, solvent which volatilizes at room temperature A non-aqueous ink that is substantially free of water, a hot melt ink that heats and melts solid ink at room temperature, an actinic ray curable ink that cures with actinic rays such as light after printing, and the like. There are inkjet inks, and they are properly used depending on the application.

  On the other hand, plastic recording media such as polyvinyl chloride and polyethylene are used as recording media for outdoor postings that require long-term weather resistance and printed materials that require adhesion to curved objects. Recording media made of soft polyvinyl chloride are used in a wide range of applications. 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. (See 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, a non-aqueous inkjet ink containing a solvent such as N-methylpyrrolidone or amide as a solvent for dissolving polyvinyl chloride is disclosed instead of cyclohexanone having the above-described problems (Patent Document 2). 3). In addition, non-aqueous inkjet inks to which a fixing resin such as vinyl chloride-vinyl acetate copolymer is added for the purpose of improving image fastness such as scratch resistance are also disclosed (see Patent Documents 4 and 5). With these configurations, it was possible to obtain an ink-jet ink capable of suppressing odor to some extent and forming an image having scratch resistance against polyvinyl chloride.

  However, when printing on a plastic recording medium such as polyvinyl chloride using such ink-jet ink, glossiness is observed between the printed and unprinted parts, or between the high density part and the low density part of the printed part. It became clear that there was a problem that the difference was different, or the concentration decreased in the low concentration part and it appeared white. Further, it has been found that when these ink-jet inks are used for a long period of time, there is a problem that abnormal operation of the ink-jet head is caused and normal image formation cannot be performed gradually.

Accordingly, the present situation is that a non-aqueous inkjet ink that has no safety and odor problems, has sufficient suitability when printed on polyvinyl chloride, and can be used stably over a long period of time has not yet been obtained.
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-mentioned problems, and has the object of having printability (abrasion resistance, alcohol wiping resistance) on a plastic recording medium such as polyvinyl chloride, emission stability, and safety. It is an object of the present invention to provide a non-aqueous ink jet ink that is excellent in quality, has no odor problem, and can be used stably even for a long period of time, and an ink jet recording method using the same.

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

  1. In a non-aqueous inkjet ink containing at least a pigment, a fixing resin, and an organic solvent, the fixing resin is polyvinyl chloride or a copolymer of vinyl chloride and a monomer other than vinyl chloride, and the polyvinyl chloride or its A non-aqueous ink-jet ink comprising a copolymer dehydrochlorination inhibitor.

  2. 2. The non-aqueous system according to 1 above, wherein the dehydrochlorination reaction inhibitor is at least one selected from metal soaps, epoxy compounds, phosphites, thiodipropionic esters and thiolcarboxylic anhydrides. Inkjet ink.

  3. The organic solvent contains the following compound (A) and the following compound (B), the content of the compound (A) is 1.5% by mass or more and 30% by mass or less, and the compound (B) The non-aqueous inkjet ink according to 1 or 2 above, wherein the content of is from 50% by mass to 90% by mass.

  Compound (A): One or more compounds selected from the group of compounds represented by the following general formulas (1) and (2) and 1,3-dimethyl-2-imidazolidinone.

[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. ]
Compound (B): One or more compounds selected from the compound group represented by the following general formulas (3) and (4).

[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. ]

[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. ]
4). Any of the above 1 to 3, wherein the compound (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 non-aqueous inkjet ink of Claim 1.

  5. The non-aqueous inkjet ink according to any one of 1 to 4, wherein the fixing resin is a resin synthesized by a solution polymerization method.

  6). The fixing resin is a vinyl chloride-vinyl acetate copolymer, a vinyl chloride-vinyl acetate-maleic anhydride copolymer, a vinyl chloride-vinyl acetate-vinyl alcohol copolymer having a number average molecular weight in the range of 10,000 to 30,000, and 6. The non-aqueous inkjet ink according to any one of 1 to 5, which is at least one selected from a vinyl chloride-vinyl acetate-hydroxyalkyl acrylate copolymer.

  7. 7. An inkjet recording method comprising printing on a polyvinyl chloride recording medium using the non-aqueous inkjet ink according to any one of 1 to 6 above.

  According to the present invention, it has printability (scratch resistance, alcohol wiping resistance) for plastic recording media such as polyvinyl chloride, has excellent emission stability and safety, has no odor problems, and can be used for a long time. In addition, a non-aqueous ink jet ink that can be used stably and an ink jet recording method using the same can be provided.

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

  As a result of various studies on non-aqueous inkjet inks (hereinafter also simply referred to as inkjet inks or inks), the present inventor has found that non-aqueous inkjet inks containing vinyl chloride as a fixing resin are vinyl chlorides contained in the ink. The resin undergoes a dehydrochlorination reaction with light or heat and decomposes to generate hydrochloric acid. The generated hydrochloric acid deteriorates the dispersion stability of the pigment contained in the ink. As a result, the viscosity of the ink increases and normal image formation cannot be performed, or the vinyl chloride resin contained in the ink is decomposed. It has been found that there is a problem that the storage stability of the ink for a long period of time deteriorates, such as coloring.

  In particular, the decomposition of the vinyl chloride resin was remarkable when a nitrogen-containing compound such as N-methylpyrrolidone or amide was contained in the ink. This seems to be because the dehydrochlorination reaction of the vinyl chloride resin is promoted because the nitrogen atom of the nitrogen-containing compound is proton-accepting and these nitrogen-containing compounds are basic solvents.

  In addition, conventionally known non-aqueous inkjet inks containing solvents such as N-methylpyrrolidone and amide exhibit good printability with respect to polyvinyl chloride, but when these inkjet inks are used over a long period of time, inkjet It has been found that there is a problem that abnormal emission of the head is caused and normal image formation cannot be gradually performed. Abnormality of the inkjet head in long-term use is considered to be caused by the solvent such as N-methylpyrrolidone and amide swelling and dissolving the components and adhesive of the inkjet head, and the content of these solvents in the inkjet ink However, in this case, the printability for polyvinyl chloride is insufficient, and an inkjet ink that satisfies both the printability for polyvinyl chloride and the long-term durability of the inkjet head has not yet been obtained. Was the current situation.

  As a result of various studies in view of the above problems, the present inventors have found that, in a non-aqueous inkjet ink containing at least a pigment, a fixing resin, and an organic solvent, the fixing resin is polyvinyl chloride, or polyvinyl chloride and vinyl chloride. A recording material made of plastic such as polyvinyl chloride with a non-aqueous ink-jet ink characterized by containing a polyvinyl chloride or a dehydrochlorination inhibitor of the copolymer. It has been found that a non-aqueous ink-jet ink can be realized which is compatible with printability (fast drying property, scratch resistance) on a medium and long-term print stability, is excellent in safety and has no problem of odor.

  Hereinafter, the configuration of the non-aqueous inkjet ink of the present invention will be specifically described.

  One of the characteristics of the ink-jet ink of the present invention is that it contains a fixing resin (hereinafter also simply referred to as a resin) in order to improve fixability when recording on a plastic recording medium such as polyvinyl chloride. .

  As the fixing resin applicable to the present invention, for example, polyvinyl chloride such as vinyl chloride resin, vinyl chloride-vinyl acetate copolymer resin, or a copolymer thereof is preferably used from the viewpoint of fixability.

  Specifically, SOLBIN (manufactured by Nissin Chemical Industry Co., Ltd.), Viny Blanc (manufactured by Nissin Chemical Industry Co., Ltd.), Saran Latex (manufactured by Asahi Kasei Chemicals Co., Ltd.), Sumilite (manufactured by Sumitomo Chemical Co., Ltd.), Sekisui PVC (manufactured by Sekisui Chemical Co., Ltd.) ), UCAR (manufactured by Dow Chemical Company), and the like.

  As the fixing resin, in addition to the polyvinyl chloride or a copolymer thereof, an acrylic resin, a polyester resin, a polyurethane resin, or the like may be used in combination.

  Specific examples of such resins include acrylic resins such as John Crill (manufactured by Johnson Polymer Co., Ltd.) and ESREC P (manufactured by Sekisui Chemical Co., Ltd.), polyester resins such as Elitel (manufactured by Unitika Ltd.) and Byron (manufactured by Toyobo Co., Ltd.). Examples thereof include polyurethane resins such as resins, Byron UR (manufactured by Toyobo Co., Ltd.), NT-Hilamic (manufactured by Dainichi Seika Co., Ltd.), Crisbon (manufactured by Dainippon Ink & Chemicals), Nipponran (manufactured by Nippon Polyurethane Co., Ltd.), and the like.

  The fixing resin acts as a binder that adheres a coloring material such as a pigment to the recording medium after printing. The larger the molecular weight of the fixing resin, the better the adhesion and durability. In addition, the smaller the molecular weight, the lower the viscosity of the ink, but the lower the viscosity, the lower the energy required to eject the ink during printing, so that the inkjet head is not burdened and it is easier to eject stably. When the average molecular weight is 10,000 or more, the fixability after printing is sufficiently exerted, and when it is 30000 or less, it is preferable because no load is applied to the emission of ink.

  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 wiping resistance can be improved in a balanced manner.

  The alcohol wiping resistance referred to in the present invention is resistance to disturbance such as image peeling when the image surface is wiped with ethanol or a mixed solvent of ethanol and water. Wipe off dirt on the image surface with alcohol on a poster for outdoor use. It is a user need for that.

  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. When the content is 1% by mass or more, the image weather resistance when recorded on polyvinyl chloride is enhanced, and when the content is 10% by mass or less, the ink ejection from the inkjet head is easily stabilized, and more preferable. The range of content is 3-7 mass%.

  Next, the dehydrochlorination reaction inhibitor according to the present invention will be described.

  The dehydrochlorination inhibitor according to the present invention is a compound that suppresses the decomposition of the fixing resin, which is polyvinyl chloride or a copolymer thereof contained in the ink, by causing a dehydrochlorination reaction in the ink. is there.

  In general, it is known that polyvinyl chloride and a copolymer thereof are decomposed by gradually causing a dehydrochlorination reaction when heated to 150 ° C. or more in the case of a polymer alone, but intensely from room temperature to less than 100 ° C. It is known that it is difficult to decompose except under special conditions such as direct light.

  However, as a result of investigations by the present inventors, a dehydrochlorination reaction that is unlikely to occur at room temperature to less than 100 ° C. is observed even when the polyvinyl chloride and its copolymer contained in the non-aqueous inkjet ink are less than 100 ° C. It was found that the dehydrochlorination reaction occurred relatively easily, and generation of hydrochloric acid and coloration of the polymer occurred.

  Hydrochloric acid generated by such a dehydrochlorination reaction makes the dispersion state of the pigment contained in the ink unstable during storage of the ink, causing the ink viscosity to increase and preventing normal image formation.

  Examples of the dehydrochlorination reaction inhibitor for preventing the dehydrochlorination reaction of polyvinyl chloride and its copolymer in the ink include stearic acid such as zinc stearate and barium laurate, lauric acid, myristic acid, palmitic acid. , Metal soaps composed of higher fatty acids such as oleic acid and linoleic acid having 8 or more carbon atoms, such as naphthenic acid, and metal salts such as calcium, magnesium, barium, zinc, cadmium and lead, epoxidized soybean oil, epoxidized animal and vegetable oils and fats, Epoxy compounds such as epoxidized fatty acid esters, phosphites such as triphenyl phosphites, trialkyl phosphites, alkyl-aryl phosphites, oligophosphites, thiodipropionic acid esters, thiolcarboxylic acid anhydrides, acetoacetic acid esters like -Diketo compounds, aminocarboxylic acid compounds such as aminocrotonic acid esters, hindered amine compounds, etc., and particularly preferred dehydrochlorination reaction inhibitors include metal soaps, epoxy compounds, phosphorous acid esters, thiodipropionic acid esters, Thiolcarboxylic anhydride. In the present invention, these dehydrochlorination inhibitors may be used alone or in combination.

  The addition amount of the dehydrochlorination reaction inhibitor is preferably about 0.001 to 1% by mass, depending on the amount of polyvinyl chloride or a copolymer thereof contained in the ink, preferably 0.01 to 0%. .5% by mass is particularly preferred.

  As a method for adding the dehydrochlorination reaction inhibitor to the ink, the dehydrochlorination reaction inhibitor may be dissolved in the ink solvent or added, or the solid dehydrochlorination reaction inhibitor may be dispersed and added in the ink solvent.

  Next, the organic solvent applied to the inkjet ink of the present invention will be described.

  As an organic solvent applied to the non-aqueous ink jet ink, when recording on a plastic recording medium, the organic solvent contained in the ink jet ink dissolves the surface of the recording medium of the print portion, and thereby the ink jet ink is used. Since some of the pigment in the medium enters the recording medium, good scratch resistance can be obtained.

  As organic solvents having such characteristics, cyclohexanone, N-methylpyrrolidone and the like have been used so far. However, these solvents have problems in safety, and the use of inkjet heads due to long-term use. It may cause abnormal operation.

  In the inkjet ink which concerns on this invention, it is preferable that it is an organic solvent comprised from the said compound (A) and the said compound (B) as a non-aqueous organic solvent.

  As the compound (A) according to the present invention, one or more kinds selected from the sulfoxide represented by the general formulas (1) and (2) or the sulfone compound group and 1,3-dimethyl-2-imidazolidinone. It is preferable to contain the compound.

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 methyl, ethyl, n-propyl, or isopropyl. 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 (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 heteroatoms such as hydroxyethyl group, acetyl group, and acetonyl group, cyclic groups such as cyclohexyl group and phenyl group, or aromatic substituents, and further R ³ and R ⁴ are They 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.

  The content of the compound (A) in the inkjet ink is preferably 1.5% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 15% by mass or less. If the content of the compound (A) is 1.5% by mass or more, the scratch resistance against polyvinyl chloride is sufficient, and if it is 30% by mass or less, abnormalities of the ink jet head are caused by long-term use. Can be prevented.

  The compound (B) preferably contains one or more compounds selected from the compound group represented by the general formulas (3) and (4).

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.

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.

  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, ethylene glycol diacetate, propylene Examples thereof include glycol diacetate.

  Among these, the component of the compound (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. The quick-drying property of the ink when printed on vinyl can be further improved. 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 compound (B) in the ink-jet ink is preferably 50% by mass or more and 90% by mass or less. By adopting such a solvent structure, quick drying property and emission stability at the time of printing polyvinyl chloride. In addition, the ink odor can be reduced.

  In the colored inkjet ink according to the present invention, in addition to the compound (A) and the compound (B) according to the present invention, a conventionally known solvent may be contained within a range not impairing the object effect of the present invention. Examples of such solvents include alkylene glycol monoalkyl ethers such as diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, ethylene glycol dibutyl ether, tetraethylene glycol dimethyl ether, and the like. Alkylene glycol dialkyl ethers, and alkylene glycol monoalkyl ether acetates such as ethylene glycol monobutyl ether acetate.

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

  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 plastic recording medium such as polyvinyl chloride 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 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. Vat 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 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 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.), 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.

  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.

  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. In particular, when polyvinyl chloride is used as the recording medium, increasing the surface temperature improves the wettability of the ink with respect to the surface of the recording medium. Therefore, it is more preferable to record at a higher surface temperature.

  Depending on the brand of the recording medium made of polyvinyl chloride, there may be a difference in wettability and ink drying, so the surface temperature may be adjusted according to the characteristics of each medium.

  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.

  The recording medium used in the ink jet recording method of the present invention is characterized by using polyvinyl chloride. Specific examples of the recording medium made of polyvinyl chloride include SOL-371G, SOL-373M, SOL-4701 (manufactured by Big Technos Co., Ltd.), glossy vinyl chloride (manufactured by Systemgraph Co., Ltd.), KSM-VS, KSM. -VST, KSM-VT (above, manufactured by Kimoto Co., Ltd.), J-CAL-HGX, J-CAL-YHG, J-CAL-WWWG (above, manufactured by Kyo Show Osaka Co., Ltd.), BUS MARK V400 F vinyl, LITEcal V-600F vinyl (above, manufactured by Flexcon), FR2 (manufactured by Hanwha), LLBAU13713, LLSP20133 (above, manufactured by Sakurai Co., Ltd.), P-370B, P-400M (above, manufactured by Kambo Plus Co., Ltd.), S02P, S12P, S13P, S14P, S22P, S24P, 34P, S27P (manufactured by Grafityp), P-223RW, P-224RW, P-249ZW, P-284ZC (manufactured by Lintec Corporation), LKG-19, LPA-70, LPE-248, LPM-45 LTG-11, LTG-21 (manufactured by Shinsei Co., Ltd.), MPI 3023 (manufactured by Toyo Corporation), Napoleon Gloss PVC (manufactured by Futaki Electronics Co., Ltd.), JV-610, Y-114 ( As described above, manufactured by ICC Corporation), NIJ-CAPVC, NIJ-SPVCGT (hereinafter, manufactured by Nichie Corporation), 3101 / H12 / P4, 3104 / H12 / P4, 3104 / H12 / P4S, 9800 / H12 / P4, 3100 / H12 / R2, 3101 / H12 / R2, 3104 / H12 / R 2, 1445 / H14 / P3, 1438 / One Way Vision (manufactured by Inetrcoat), JT5129PM, JT5728P, JT5822P, JT5829P, JT5829R, JT5829PM, JT5829RM, JT5929PM (above, manufactured by Mactac, MP1100, MP1100 MPI2001, MPI2002, MPI3000, MPI3021, MPI3500, MPI3501 (above, manufactured by Avery), AM-101G, AM-501G (above, manufactured by Ginichi Co., Ltd.), FR2 (manufactured by Hanwha Japan Co., Ltd.), AY-15P, AY-60P, AY-80P, DBSP137GGH, DBSP137GGL (above, manufactured by Insight Inc.), SJT-V200F, SJ T-V400F-1 (above, manufactured by Hiraoka Oryome Co., Ltd.), SPS-98, SPSM-98, SPSH-98, SVGL-137, SVGS-137, MD3-200, MD3-301M, MD5-100, MD5- 101M, MD5-105 (manufactured by Metamark), 640M, 641G, 641M, 3105M, 3105SG, 3162G, 3164G, 3164M, 3164XG, 3164XM, 3165G, 3165SG, 3165M, 3169M, 3451SG, 3551G, 3551M, 3631, 3641M , 3651G, 3651M, 3651SG, 3951G, 3641M (above, manufactured by Orafol), SVTL-HQ130 (manufactured by Lamy Corporation), SP300 GWF, SPCLEARAD vinyl l (above, manufactured by Catalina), RM-SJR (produced by Ryoyo Shoji Co., Ltd.), Hi Lucky, New Lucky PVC (above, produced by LG), SIY-110, SIY-310, SIY-320 (above, Sekisui Chemical) Industrial Co., Ltd.), PRINT MI Frontlit, PRINT XL Lightweight banner (above, manufactured by Endutex), RIJET 100, RIJET 145, RIJET165 (above, manufactured by Ritrama), NM-SG, NM-SM Co., Ltd. Manufactured), LTO3GS (manufactured by Lucio Co., Ltd.), easy print 80, performance print 80 (manufactured by Jetgraph Co., Ltd.), DSE 550, DSB 550, DSE 800G, DSE 802/137, V250WG, 300WG, V350WG (manufactured by Hexis Ltd.), Digital White 6005PE, 6010PE (or, Multifix Co., Ltd.).

  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.

Example 1
<Preparation of ink>
[Preparation of Ink 1]
<Preparation of pigment dispersion 1>
C. I. 10 parts of Pigment Blue 15: 3 (hereinafter abbreviated as PB15: 3), 6 parts of Solspers 24000 (manufactured by ICI Japan) as a pigment dispersant, and sulfolane (S- 1) 10 parts, 59 parts of diethylene glycol diethyl ether and 15 parts of ethylene glycol diacetate as solvent (B), and a horizontal bead mill (system manufactured by Ashizawa Co., Ltd.) filled with 60% by volume of 0.5 mm diameter zirconia beads. Zetamini) was used for dispersion, and then the zirconia beads were removed to obtain pigment dispersion 1.

<Preparation of resin solution 1>
10 parts of sulfolane as the compound (A), 64.8 parts of diethylene glycol diethyl ether and 15 parts of ethylene glycol diacetate as the solvent (B), and a vinyl chloride-vinyl acetate copolymer synthesized by a solution polymerization method as a fixing resin. 10 parts of polymer mPVC (trade name VMCC, number average molecular weight 19000, manufactured by Dow Chemicals) and 0.2 part of diphenyl-isooctyl phosphite (A-1) as a dehydrochlorination inhibitor were mixed and dissolved. Resin solution 1 was prepared.

<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 2-33]
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 compound (B), the type and addition amount of the dehydrochlorination reaction inhibitor, the type of other solvent, Inks 2 to 23 were prepared in the same manner except that the addition amount was changed as shown in Table 1. In the case of a dehydrochlorination inhibitor that does not dissolve in the resin solution, the resin solution was dispersed and added in the same manner as the dispersion of the pigment dispersion.

  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
CB; carbon black <fixing resin>
mPVC: solution polymerization vinyl chloride-vinyl acetate copolymer (trade name VMCA, manufactured by Dow Chemicals)
sPVC: suspension polymerization vinyl chloride-vinyl acetate copolymer (trade name SOLBIN TAO, manufactured by Nissin Chemical Co., Ltd.)
Acrylic: butyl methacrylate-methyl methacrylate copolymer (trade name DEGLAN P24, manufactured by Degussa)
<Compound (A)>
S-1: Sulfolane S-2: Dimethyl sulfoxide S-3: Di-n-propyl sulfoxide S-4: Diphenyl sulfoxide S-5: Tetramethylene sulfoxide S-6: Dimethyl sulfone <Compound (B)>
OS1: Diethylene glycol diethyl ether (DEGDEE)
OS2: Diethylene glycol dimethyl ether (DEGDME)
OS3: Dipropylene glycol diethyl ether (DPGDEE)
OS4: Dipropylene glycol dimethyl ether (DPGDME)
OS5: Ethylene glycol diacetate (EGDAc)
OS6: Propylene glycol diacetate (PGDAc)
<Other solvents>
OS7: Diethylene glycol dibutyl ether (DEGDBE)
OS8: Tetraethylene glycol dimethyl ether (TEGDME)
OS9: Ethylene glycol monobutyl ether acetate (EGBEAc)
OS10: Dipropylene glycol monomethyl ether acetate (DPGMEAc)
NMP: N-methylpyrrolidone <Dehydrochlorination reaction inhibitor>
A-1: Diphenyl-isooctyl phosphite A-2: Epoxy octyl oleate A-3: Zinc stearate A-4: Calcium laurate A-5: Cadmium naphthenate A-6: Distearyl pentaerythritol diphosphite A-7: Dilauryl thiodipropionic acid A-8: Thiol lauric anhydride << Evaluation of ink >>
Each of the inks prepared above was evaluated according to the following method.

(Evaluation of light emission)
Piezo-type head having a nozzle diameter of 28 μm, a driving frequency of 12 kHz, a nozzle number of 512, a minimum liquid proper amount of 14 pl, and a nozzle density of 180 dpi (where dpi represents the number of dots per 2.54 cm), and Japanese Patent Laid-Open No. 2002-363469 Using the strobe light emission type ink flight observation device shown in FIG. 2, the ejection cycle and the light emission cycle are synchronized, and the flight status of each ink is monitored by a CCD camera, and the emissivity in an environment of 23 ° C. and 55% RH is obtained. Evaluation was made according to the following criteria.

A: Ink droplets are ejected normally, and no abnormalities such as bending, missing, or speed variation occur even if the ejection is resumed after stopping for 3 minutes. O: The ink droplets are ejected normally and emitted. No problem occurs even after restarting after stopping for 1 minute, but there is a nozzle that bends and has a speed variation when restarting after stopping for 3 minutes. Δ: Ink droplets are ejected normally, but ejection There are nozzles that bend and vary in speed when restarted after being stopped for 1 minute. ×: There are nozzles that are difficult to normally eject ink droplets and cause bending, and many nozzles when ejection is resumed after stopping for 1 minute. Bending, speed variation, and missing parts [Evaluation of odor resistance]
Ink 1 to 23 are put in a polyethylene bottle of 250 ml each up to about half, and odor perception is evaluated by 20 subjects. Five cases are determined to be almost odorless, and 1 case is determined to be a very unpleasant odor. Points were scored in 5 stages, and odor resistance was evaluated according to the following criteria.

A: The average score of 20 subjects is 4.0 points or more. ○: The average score of 20 subjects is 3.0 points or more and less than 4.0 points. Δ: The average score of 20 subjects is 2.0 points or more and less than 3.0 points ×: The average score of 20 subjects is less than 2.0 points [Evaluation of ink storage stability]
Inks 1 to 23 were each placed in a 50 ml glass bottle, sealed and stored in a dark place at 60 ° C. for 10 weeks. The viscosity before and after storage was measured to determine the viscosity increase ratio after storage, and the ink storage stability was evaluated according to the following criteria.

A: Ratio of viscosity before and after ink storage is 0.8 or more and less than 1.2 ○: Ratio of viscosity before and after ink storage is 1.2 or more and less than 1.4 Δ: Ratio of viscosity before and after ink storage 1.4 or more and less than 2.0 ×: The ratio of the viscosity before and after ink storage is 2.0 or more [Evaluation of formed image]
(Image formation)
Each ink is supplied to an on-demand type ink jet printer equipped with a piezo head having a nozzle diameter of 28 μm, a driving frequency of 12 kHz, a nozzle number of 512, a minimum liquid amount of 14 pl, a nozzle density of 180 dpi, and a heater having a maximum recording density of 720 × 720 dpi. Was loaded. Next, each ink was ejected, and a solid image of 10 cm × 10 cm was recorded on JT5929PM (manufactured by Mactac) which is a recording medium made of polyvinyl chloride. During printing, the recording medium was heated from the back surface, and the heater temperature was set so that the surface temperature of the recording medium during image recording was 40 ° C. The surface temperature of the recording medium was measured using a non-contact thermometer (IT-530N type, manufactured by Horiba, Ltd.).

(Image evaluation)
According to the above method, each image created from the inks 1 to 23 was 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 an image cannot be taken even if it is rubbed with a finger is less than 3 minutes immediately after image recording. ○: The time when an image is not taken even if rubbed with a finger is 3 minutes or more and less than 4 minutes immediately after image recording. The time that an image cannot be taken even if it is rubbed with a finger is 4 minutes or more and less than 5 minutes immediately after image recording. X: The time that an image cannot be taken even if rubbed with a finger takes 5 minutes or more immediately after image recording. Evaluation>
The surface of the image recorded on polyvinyl chloride was rubbed with dry cotton, and scratch resistance was evaluated according to the following criteria.

A: The image hardly changes even after rubbing 51 times or more. ○: Slight scratches remain after rubbing 50 times, but hardly affects the image density. Δ: Image density decreases while rubbing 25 to 49 times. : Image density decreases while rubbing less than 25 times <Evaluation of alcohol wiping resistance>
The image recorded on polyvinyl chloride was rubbed with cotton containing a 2: 1 mixed solution of ethanol and water, and the alcohol wiping resistance was evaluated according to the following criteria.

◎: Image hardly changes even after rubbing 31 times or more ○: Slight scratch remains at the stage of rubbing 30 times, but hardly affects the image density Δ: Image density decreases while rubbing 15 to 29 times × : Image density decreases while rubbing less than 15 times <Evaluation of long-term durability of head>
Twenty-three ink jet heads were prepared, inks 1 to 23 were filled in the respective heads, and stored in that state at room temperature. The ink jet head was incorporated into a recording device once a week, and the image formation was performed for 6 months. Subsequently, the long-term durability of the inkjet head was determined by evaluating an image formed after the lapse of 6 months. A performance of △ or higher was regarded as an acceptable level.

◎: The image after 6 months and the initial image are the same, and the inkjet head has not deteriorated. ○: Although there is a variation in density in part of the image after 6 months, it is almost the same as the initial image. Identical and almost no deterioration of the inkjet head Δ: Slight white streaks appear in the image after 6 months, and partial deterioration of the inkjet head is observed ×: After 6 months Table 2 shows the results obtained in the above manner because white streaks occur frequently and the ink jet head is greatly deteriorated.

  As is apparent from the results shown in Table 2, the ink-jet ink having the constitution defined in the present invention is excellent in the ink emission property, odor property, and storage stability, and the speed of an image recorded on polyvinyl chloride as a recording medium. It can be seen that it is excellent in all the characteristics of dryness and image abrasion resistance, alcohol wiping resistance and long-term durability of the head.

Example 2
For the inks 1, 2, 22, and 23 prepared in Example 1, immediately after the ink preparation, each ink was diluted with 10 times pure water, filtered, and extracted with the same amount of toluene as the filtrate. The pH of the aqueous layer after extraction was neutral. Further, for each of inks 1, 2, 22, and 23, each was sealed in a glass bottle and stored in an environment at 60 ° C. for 10 weeks, and then the same operation was performed to measure the pH of the water tank. Although it was neutral, the ink 23 was acidic with a pH of 3.2. The aqueous layer extracted from the ink 23 was concentrated by a rotary evaporator, and white smoke was generated when a filter paper containing ammonia water was passed over the concentrated liquid. This smoke was ammonium chloride formed by the reaction of hydrogen chloride gas and ammonia, and it was confirmed that hydrochloric acid was generated in the ink 23 during storage.

Claims (7)

In a non-aqueous inkjet ink containing at least a pigment, a fixing resin, and an organic solvent, the fixing resin is polyvinyl chloride or a copolymer of vinyl chloride and a monomer other than vinyl chloride, and the polyvinyl chloride or its A non-aqueous ink-jet ink comprising a copolymer dehydrochlorination inhibitor. The non-hydrochloric acid reaction inhibitor is at least one selected from metal soaps, epoxy compounds, phosphites, thiodipropionic esters, and thiolcarboxylic anhydrides. Water-based inkjet ink. The organic solvent contains the following compound (A) and the following compound (B), the content of the compound (A) is 1.5% by mass or more and 30% by mass or less, and the compound (B) The non-aqueous inkjet ink according to claim 1 or 2, wherein the content of is not less than 50% by mass and not more than 90% by mass.
Compound (A): One or more compounds selected from the group of compounds represented by the following general formulas (1) and (2) and 1,3-dimethyl-2-imidazolidinone.

[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. ]
Compound (B): One or more compounds selected from the compound group represented by the following general formulas (3) and (4).

[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. ]

[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. ] The compound (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 non-aqueous inkjet ink according to any one of the above. The non-aqueous inkjet ink according to claim 1, wherein the fixing resin is a resin synthesized by a solution polymerization method. The fixing resin is a vinyl chloride-vinyl acetate copolymer, a vinyl chloride-vinyl acetate-maleic anhydride copolymer, a vinyl chloride-vinyl acetate-vinyl alcohol copolymer having a number average molecular weight in the range of 10,000 to 30,000, and The non-aqueous inkjet ink according to any one of claims 1 to 5, wherein the non-aqueous inkjet ink is at least one selected from vinyl chloride-vinyl acetate-hydroxyalkyl acrylate copolymers. 7. An ink jet recording method comprising printing on a polyvinyl chloride recording medium using the non-aqueous ink jet ink according to claim 1.