JP2013006945A - Nonaqueous inkjet ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the storage stability and discharge stability of nonaqueous inkjet ink.SOLUTION: The nonaqueous inkjet ink includes at least a coloring agent and a solvent. The ink further includes a calixarene represented by general formula, wherein n is 5 or less, R is 1-20C saturated or unsaturated alkyl, and the alkyl may be straight or branched, and further may have a substituent.

Description

  The present invention relates to a non-aqueous inkjet ink suitable for use in an inkjet recording apparatus.

  Inkjet recording is a method in which high-fluidity inkjet ink is ejected as ink particles from fine head nozzles, and images are recorded on printing paper placed facing the nozzles, enabling high-speed printing with low noise. Therefore, it has been spreading rapidly in recent years. As an ink used for such an ink jet recording method, there is a so-called non-aqueous ink in which a pigment is finely dispersed in a non-water-soluble solvent.

  Even if the non-aqueous ink stabilizes the solubility of the dispersant and suppresses the aggregation of the pigment, there is a problem that a precipitate such as a precipitate of the pigment, a gel-like foreign matter, or a rod-like crystal is generated due to a change with time. When the stagnation occurs, clogging occurs in the nozzles and the ink supply path, and the stability of ink ejection deteriorates. One cause of starch generation is that a solvent oxidized with time and a typical metal element ion (hereinafter also simply referred to as a metal ion) form a salt.

  In view of such problems, the applicant has proposed a non-aqueous ink-jet ink containing a chelating agent soluble in a solvent in Patent Document 1. This non-aqueous ink-jet ink uses a chelating agent that captures pigments, pigment derivatives, impurities at the time of pigment synthesis, metal ions derived from containers and ink paths, and chelating agents that capture metal ions (typical metal element ion chelate). ) Constitutes a solvation together with metal ions, so that the metal ions do not precipitate in the ink, which makes it possible to suppress the occurrence of starch over time, and has excellent storage stability and ejection performance. is there.

JP 2005-298585 A

Inkjet recording methods can produce images easily and inexpensively, and have recently been applied to various printing fields such as photography, various printing, special printing such as marking, color filters, etc. In view of the above, it is necessary to further improve storage stability and discharge performance. In particular, conventionally, the resolution of an inkjet head has been 300 dpi, but the demand for images has increased, and stable ejection is required even with higher-definition inkjet heads. Such a high-definition inkjet head has a small nozzle diameter, and the presence of foreign matter in the ink greatly affects the ejection stability.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a non-aqueous inkjet ink capable of further improving storage stability and ejection stability.

The non-aqueous ink-jet ink of the present invention is a non-aqueous ink-jet ink comprising at least a colorant and a solvent, and is a calixarene represented by the following general formula (wherein n is 5 or less, and R is a carbon number of 1 to 20 saturated or unsaturated alkyl group, wherein the alkyl group may be linear or branched and may further have a substituent) It is.
In the calixarene represented by the general formula, n is preferably 4 or 5, and R has more preferably 1 to 4 carbon atoms.

  Since the non-aqueous inkjet ink of the present invention contains the calixarene represented by the above general formula, it is possible to suppress the generation of foreign matter over time and further improve storage stability and ejection stability.

It is a photograph of the residue on a filter of Example 1, the comparative example 2, and pigment washing ink.

The non-aqueous ink-jet ink of the present invention (hereinafter also simply referred to as ink) is an ink comprising at least a colorant and a solvent, and further includes calixarene represented by the following general formula.

  In the above formula, n is 5 or less, R is a saturated or unsaturated alkyl group having 1 to 20 carbon atoms, and the alkyl group may be linear or branched, and further has a substituent. You may have. Examples of R include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a t-butyl group, and a pentyl group, and more preferably has 1 to 4 carbon atoms. It is desirable. Examples of the substituent include hydrocarbon groups such as methyl group, ethyl group and n-propyl group, halogeno groups such as fluoro group, bromo group, iodo group and chloro group, hydroxy group and carboxyl group.

  The addition amount of calixarene is desirably 0.1% by mass or more, more preferably 0.3% by mass or more and 0.5% by mass or less based on the total amount of ink. The amount of calixarene added depends on the amount of metal ions to be trapped, and 0.1 mass% or more based on the total amount of ink is sufficient to supplement the metal ions derived from the pigment and the ink flow path. On the other hand, the upper limit of the amount of calixarene added depends on the amount dissolved in the solvent to be used. However, if the cost is taken into consideration, even if 0.5% by mass or more is added, excessive addition occurs.

  Foreign matter is generated with time in the non-aqueous inkjet ink. These foreign substances are mainly metal salts of fatty acids, but calixarene is present in a stable state in the ink by inclusion of metal ions insoluble in the ink solvent by the hydroxyl group at the 4-position of each phenol unit constituting the calixarene. ) Can be able to. In addition, calixarene is a cyclic structure having no end group, and is therefore thermodynamically stable and can maintain the inclusion state for a long time. As a result, metal ions are more stable when dissolved in ink than when they form a salt with fatty acid, and the generation of foreign matter is suppressed.

  The calixarene of the present invention is preferably soluble in a solvent. Here, being soluble in a solvent means that it dissolves in a solvent to such an extent that the metal ions eluted in the ink can be captured. More specifically, 0.5% by mass or more of calixarene is mixed with the solvent. It means that there is no sediment in a state of standing at room temperature for 1 day after dispersion with a bead mill. This solvent can be appropriately selected from polar organic solvents and nonpolar organic solvents.

  As the colorant, any pigment generally used in the technical field of printing can be used regardless of inorganic pigments, organic pigments, and dyes. Specific examples of the pigment include, for example, carbon black, cadmium red, molybdenum red, chrome yellow, cadmium yellow, titanium yellow, chromium oxide, pyridian, cobalt green, ultramarine blue, Prussian blue, cobalt blue, and phthalocyanine pigments. Quinacridone pigments, isoindolinone pigments, dioxazine pigments, selenium pigments, perylene pigments, perinone pigments, thioindigo pigments, quinophthalone pigments, metal complex pigments, and the like can be used.

  Further, insoluble azo pigments such as β-naphthol, naphthol AS, acetoacetyl arylide, pyrazolone, etc. (disazo yellow, lake red 4R, etc.), soluble azo pigments such as Ca lake, Ba lake, Sr lake, Mn lake, etc. Brilliant carmine 6B, lake red C, watching red, etc.), basic dyed lake pigments such as tannic acid lake, phosphomolybdic acid lake, phosphotungstic acid lake, phosphomolybdenum tungstic acid lake (rhodamine B lake, rhodamine 6G lake, methyl violet) Rake pigments such as orange rake, quinoline yellow rake, and the like, such as lake rake, Ba lake, Ca lake, Al lake, and Pb rake.

As the dye, conventionally known dyes can be used, azo dyes, metal complex dyes, naphthol dyes, anthraquinone dyes, indigo dyes, carbonium dyes, quinoneimine dyes, xanthene dyes, cyanine dyes, quinoline dyes, nitro dyes, nitroso dyes, Preferable examples include oil-soluble dyes such as benzoquinone dyes, naphthoquinone dyes, phthalocyanine dyes, and metal phthalocyanine dyes.
These colorants may be used alone or in appropriate combinations, but are desirably contained in the range of 0.01 to 20% by mass with respect to the entire ink.

  As the polar organic solvent, ester solvents, alcohol solvents, higher fatty acid solvents, ether solvents, and mixed solvents thereof can be used. The polar organic solvent is selected from those that form a single phase when mixed with a solvent other than the polar organic solvent.

  Specifically, examples of the ester solvent include higher fatty acid esters having 5 or more, preferably 9 or more, more preferably 12 to 32 carbon atoms in one molecule, such as methyl laurate and isopropyl laurate. , Isopropyl myristate, isopropyl palmitate, isostearyl palmitate, methyl oleate, ethyl oleate, isopropyl oleate, butyl oleate, methyl linoleate, isobutyl linoleate, ethyl linoleate, isopropyl isostearate, methyl soybean oil, Soybean oil isobutyl, tall oil methyl, tall oil isobutyl, diisopropyl adipate, diisopropyl sebacate, diethyl sebacate, propylene glycol monocaprate, tri-2-ethylhexanoate trimethylolpropane, tri-2-ethyl Examples of ester solvents and alcohol solvents such as glyceryl hexanoate include aliphatic higher alcohols having 12 or more carbon atoms in one molecule, such as isomyristyl alcohol, isopalmityl alcohol, isostearyl alcohol, and oleyl. Alcohol solvents such as alcohol, isononanoic acid, isomyristic acid, hexadecanoic acid, isopalmitic acid, oleic acid, isostearic acid and other higher fatty acid solvents, diethyl glycol monobutyl ether, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, propylene glycol Examples include ether solvents such as dibutyl ether.

  Examples of the solvent other than the polar organic solvent contained in the solvent include nonpolar solvents such as aliphatic hydrocarbon solvents and aromatic hydrocarbon solvents. As the aliphatic hydrocarbon solvent, for example, “Teclean N-16, Teclean N-20, Teclean N-22, Nisseki Naphthezol L, Nisseki Naphthezol M, Nisseki Naphthezol H, No. 0 Solvent L, manufactured by Nippon Oil Corporation , No. 0 Solvent M, No. 0 Solvent H, Nisseki Isosol 300, Nisseki Isosol 400, AF-4, AF-5, AF-6, AF-7, “Isopar G, Isopar H, Isopar L, Isopar M, manufactured by Exxon Corporation, ExxolD40, ExxolD80, ExxolD100, ExxolD130, ExxolD140 "etc. can be mentioned preferably. As the aromatic hydrocarbon solvent, “Clean Sol G” (alkylbenzene) manufactured by Nippon Oil Corporation can be preferably exemplified.

  Examples of the dispersant usable in the present invention include a hydroxyl group-containing carboxylic acid ester, a salt of a long chain polyaminoamide and a high molecular weight acid ester, a salt of a high molecular weight polycarboxylic acid, a salt of a long chain polyaminoamide and a polar acid ester, and a high molecular weight. Unsaturated acid ester, polymer copolymer, modified polyurethane, modified polyacrylate, polyether ester type anionic activator, naphthalene sulfonic acid formalin condensate salt, aromatic sulfonic acid formalin condensate salt, polyoxyethylene alkyl phosphoric acid Esters, polyoxyethylene nonylphenyl ether, polyester polyamines, stearylamine acetate, and the like can be used.

  Specific examples of the dispersant include “Anti-Terra-U (polyaminoamide phosphate)”, “Anti-Terra-203 / 204 (high molecular weight polycarboxylate)” manufactured by BYK Chemie, “Disperbyk-101 ( Polyaminoamide phosphate and acid ester), 107 (hydroxyl group-containing carboxylic acid ester), 110 (copolymer containing an acid group), 130 (polyamide), 161, 162, 163, 164, 165, 166, 170 (high) Molecular copolymer) ”,“ 400 ”,“ Bykumen (high molecular weight unsaturated acid ester) ”,“ BYK-P104, P105 (high molecular weight unsaturated acid polycarboxylic acid) ”,“ P104S, 240S (high molecular weight unsaturated) Acid polycarboxylic acid and silicon system "," Lactimon (long-chain amine and unsaturated acid polycal Bonic acid and silicon) ”.

  Further, “Efka CHEMICALS” “Efka 44, 46, 47, 48, 49, 54, 63, 64, 65, 66, 71, 701, 764, 766”, “Efka Polymer 100 (modified polyacrylate), 150 (aliphatic) System modified polymer), 400, 401, 402, 403, 450, 451, 452, 453 (modified polyacrylate), 745 (copper phthalocyanine system) "," Kyoeisha Chemical Co., Ltd. "" Floren TG-710 (urethane oligomer) "," “Floren DOPA-15B (acrylic oligomer)”, “Floren SH-290, SP-1000”, “Polyflow No. 50E, No. 300 (acrylic copolymer)”, “Disparon KS-860, 873SN” manufactured by Enomoto Kasei Co., Ltd. 874 (polymer dispersant), # 2150 (aliphatic polyvalent catalyst) Bonn acid), # 7004 (polyether ester type) "," DA-703-50 (polyester acid amide amine salt) "can be mentioned.

  Furthermore, “Demol RN, N (Naphthalene sulfonic acid formalin condensate sodium salt), MS.C, SN-B (aromatic sulfonic acid formalin condensate sodium salt), EP”, “Homogenol L-18 (poly) Carboxylic acid type polymer), “Emulgen 920, 930, 931, 935, 950, 985 (polyoxyethylene nonylphenyl ether)”, “Acetamine 24 (coconut amine acetate), 86 (stearylamine acetate)”, Lubrizol “Solsperse 5000 (phthalocyanine ammonium salt type), 13940 (polyesteramine type), 17000, 18000 (fatty acid amine type), 22000, 24000, 28000”, “Nikkor T106 (polyoxyethylenesorbitan) manufactured by Nikko Chemical Co., Ltd. Monooleate), MYS-IEX (polyoxyethylene monostearate), Hexagline 4-O (hexaglyceryl tetraoleate) "and the like.

  Among the combinations of solvents and dispersants described above, in the combination of an ester solvent and a dispersant having an ester structure, particularly a dispersant having a polyesteramine structure or a fatty acidamine structure, better dispersion stability, The pigment has a fine particle size, and a stable ink composition can be obtained with little change in particle size and viscosity when left at high temperatures. The ester solvent is preferably contained in the polar organic solvent in an amount of 10% by mass or more, and more preferably 30% by mass or more, and more preferably 50% by mass or more in order to improve the dispersibility of the pigment in the ink. It is preferable to contain.

In addition to pigments and solvents, the non-aqueous inkjet ink of the present invention is used, for example, to improve the adhesion of the ink to the recording medium or to adjust the spread of ink dots on the recording medium. A resin that dissolves in the polar organic solvent may be added. Such resins include acrylic resins, styrene-acrylic resins, styrene-maleic resins, rosin resins, rosin ester resins, ethylene-vinyl acetate resins, petroleum resins, coumarone indene resins, terpenes. Phenol resin, phenol resin, urethane resin, melamine resin, urea resin, epoxy resin, cellulose resin, vinyl chloride resin, xylene resin, alkyd resin, aliphatic hydrocarbon resin, butyral resin, maleic acid resin, fumarate An acid resin or the like is used.
Hereinafter, the present invention will be specifically described by way of examples.

(Examples 1-4)
Soybean oil isobutyl, ethyl oleate, isostearyl alcohol, naphthenic solvent (manufactured by Nippon Oil Co., Ltd. AF-6), calixarene are mixed in the formulation shown in Table 1 (the values shown in Table 1 are parts by mass), Solsperse 13940 (manufactured by Lubrizol) was dissolved as a dispersant, and copper phthalocyanine blue was further added and premixed. Thereafter, it was dispersed in a bead mill with a residence time of about 20 minutes to obtain an ink.

(Example 5)
A 300 ml four-necked flask was charged with 75 g of a naphthenic solvent (AF-6 manufactured by Nippon Oil Corporation), and the temperature was raised to 110 ° C. with aeration of nitrogen gas and stirring. Next, while maintaining the temperature at 110 ° C., the monomer mixture shown in Table 2 was placed in a four-necked flask, and 16.7 g of AF6 and 4 g of t-butylperoxy 2-ethylhexanoate (Japan) A mixture with Oil and Fat Co., Ltd. (Perbutyl O) was added dropwise over 3 hours. Thereafter, 0.2 g of perbutyl O was added after 1 hour and 2 hours while maintaining at 110 ° C. Further, aging was performed at 110 ° C. for 1 hour and diluted with 12.7 g of AF-7 to obtain a colorless and transparent copolymer solution having a nonvolatile content of 50%. A 500 mL four-necked flask is charged with the above copolymer solution 200 g (solid content: 100 g), ethyl oleate 111 g, propylene glycol 4.0 g, and diethanolamine 2.8 g. The temperature was raised and kept at this temperature for 1 hour. 0.2 g of dibutyltin dilaurate was added to the obtained reaction product, and a mixture of 7.3 g of 1,3-bis (isocyanatomethyl) cyclohexane (Takenate 600 manufactured by Mitsui Chemicals Polyurethane Co., Ltd.) and 65.7 g of IOP was mixed. Was added dropwise over 1 hour. After the dropwise addition, the temperature was raised to 120 ° C. and reacted for 6 hours, cooled, 70 g of naphthenic solvent (AF-6 manufactured by Shin Nippon Oil Co., Ltd.) was added, and a urethane-modified methacrylate copolymer having a solid content of 25% ( A dispersion was obtained (referred to as “polymer a”).

  Soybean oil isobutyl, ethyl oleate, isostearyl alcohol, naphthenic solvent, calixarene are mixed in the formulation shown in Table 1 (the numerical values shown in Table 1 are parts by mass), polymer a is dissolved in this, and copper is further added. Phthalocyanine blue was added and premixed. Thereafter, it was dispersed in a bead mill with a residence time of about 20 minutes to obtain an ink.

(Comparative Examples 1-3)
An ink was obtained in the same manner as in Example 1 except that a chelating agent was used in Comparative Example 1 except that n = 6 calixarene and Comparative Examples 2 and 3 were used instead of calixarene.

(Evaluation method)
(Solubility)
After ink preparation, the presence or absence of sediment when the ink was allowed to stand for 1 day and the permeability when the ink was filtered using a 0.8 μm membrane filter were evaluated according to the following criteria.
○: There is no sediment and filterability is good. Δ: There is some sediment, but filter permeability is good. ×: There is a large amount of sediment and it does not pass through the filter at all.

(Foreign matter generation amount)
The ink was allowed to stand in an airtight environment at 70 ° C. for 1 month, and then the residue on the filter was visually confirmed when the ink was filtered using a 0.2 μm membrane filter, and evaluated according to the following criteria. In the following pigment-cleaned product, copper phthalocyanine (Pigment Blue) was mixed with ion exchange water so that the amount was 10% by mass, stirred and dispersed for 1 hour, and then the dispersion was filtered, and this was repeated three times. The unpigmented product is the product before washing.
○: No foreign matter (equivalent to pigment-cleaned product)
Δ: Some foreign matter ×: Large amount of foreign matter (equivalent to unwashed pigment product)

(Discharge stability)
After the ink is left in a sealed state in an environment of 70 ° C. for one month, a solid image (main scanning 318 dots / sub scanning 3000 dots) is continuously printed 100 times using the ink jet head (CF1) manufactured by Toshiba TEC. The image was visually confirmed and evaluated according to the following criteria.
○: Uniform solid image △: Uniform solid image is obtained in the initial stage, but the image is distorted after printing several tens of times. X: Image is distorted from the initial stage. The evaluation results are shown together with the prescriptions of Examples and Comparative Examples. It is shown in 1.

  As is apparent from Table 1, the ink of the present invention has extremely high solubility in a solvent and a small amount of foreign matter generated, and thus the ejection stability is good. On the other hand, calixarene with n = 6 did not dissolve in the solvent. Further, GEDTA of Comparative Example 3 was also poorly soluble in the organic solvent used in this example. Furthermore, although the benzo 18-crown-6-ether of Comparative Example 2 was soluble in the solvent, the amount of foreign matter produced was larger than that of the Example.

  The photograph of the residue on a filter at the time of evaluating the foreign material production amount of Example 1 and Comparative Example 2 is shown together with the photograph of the residue on the filter when an ink using a pigment-cleaned product as a pigment is similarly passed through the filter. It is shown in 1. As can be seen from FIG. 1, the ink of the present invention is not different from the pigment cleaning ink, and has less foreign matter generation than the pigment cleaning ink. This is because pigment ions, pigment derivatives, and metal ions derived from impurities during pigment synthesis are removed by washing in pigment cleaning ink, but metal ions derived from the container and ink path and a solvent oxidized over time form a salt. This is because the foreign matter is deposited. On the other hand, calixarene of this example includes not only pigments, pigment derivatives, and metal ions derived from impurities during pigment synthesis, but also metal ions derived from containers and ink paths are clathrated by the hydroxyl group at the 4-position of calixarene. 1 can be stably present (dissolved state) in the ink, and it can be seen from the photograph shown in FIG. 1 that its trapping power is far superior to the chelating agent.

  In the present example, copper phthalocyanine was used as the pigment. However, from the mechanism of capturing metal ions by calixarene, it is presumed that similar results can be obtained with other pigments.

Claims (3)

A non-aqueous inkjet ink comprising at least a colorant and a solvent, wherein the calixarene represented by the following general formula (wherein n is 5 or less and R is a saturated or unsaturated alkyl group having 1 to 20 carbon atoms) And the alkyl group may be linear or branched, and may further have a substituent).
    The non-aqueous inkjet ink according to claim 1, wherein n of the calixarene represented by the general formula is 4 or 5.   3. The non-aqueous inkjet ink according to claim 1, wherein R in the calixarene represented by the general formula has 1 to 4 carbon atoms.