JP2012177119A - Oil-based pigment ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil-based pigment ink composition which can attain printer reliability, e.g. continuous mass printing of printed matter having stable quality, also can be printed on a printing medium made of inexpensive film such as polyvinyl chloride without an ink-receiving layer and can withstand outdoor usage environment by improving discharge stability upon high-speed printing at a drive frequency of 10 KHz or more in the oil-based pigment ink composition containing pigment, organic solvent and polymer compound.SOLUTION: The oil-based pigment ink composition contains at least the pigment, the organic solvent and the polymer compound, and when the viscosity measured at a shear rate of 1×10secand at 25°C is defined as A and the viscosity measured at a shear rate of 1×10secis defined as B, according to a measurement method performed while accompanying an increase in the shear rate by the use of a rotational viscometer, the oil-based pigment ink composition has a viscosity B of 1 to 30 mPa s and has a thixotropy coefficient A/B of 1.01 to 1.40, and it can be used for an inkjet printer having a drive frequency of 10KHz or more.

Description

  The present invention relates to an oil-based pigment ink composition containing at least a pigment, an organic solvent, and a polymer compound (for example, a pigment dispersant and / or a fixing resin).

  The oil-based pigment ink composition of the present invention can be used as a printing ink or a writing instrument ink for any recording method such as inkjet printing, offset printing, gravure printing, screen printing, thermal transfer printing, etc. Used as ink for inkjet printing. In particular, it is suitable for use in an ink jet printer having a driving frequency of 10 KHz or more.

  In the ink jet recording system, liquid ink is ejected from a nozzle of an ink jet printer toward a recording medium using pressure, heat, an electric field or the like as a driving source, and characters, images, and the like are printed on the recording medium. Such a recording method is low in running cost, enables high-quality printing, and can be printed using various inks such as water-based ink and oil-based ink according to the application. Yes.

  In the industrial field, large-scale inkjet printers corresponding to A-0 size that can be printed on absorptive recording media such as paper using water-based ink have been developed. Output of indoor posters, CAD drawings, and color matching for printing Used for proofing output for. Furthermore, the printed material is also used for outdoor use by laminating a transparent film on the printed material.

  In recent years, the demand for outdoor applications has increased, and oil-based inks that can be directly printed on plastic films such as polyvinyl chloride have been demanded. The fixability of the colorant on the printing surface is good, and the printed materials can be used without being laminated. Oil-based inks having excellent durability such as water resistance and weather resistance have been developed. As an ink having good fixability, an ink in which a vinyl chloride resin is dissolved in an organic solvent has been proposed. In addition, as an ink excellent in water resistance and weather resistance, an ink in which a pigment having a high color fastness is dispersed in an organic solvent has been proposed.

  Under such circumstances, in addition to improving the image quality and durability of printed matter, there is an increasing demand for improvement in productivity such as an increase in the number of printed copies, and an ink composition that can cope with high-speed printing is strongly demanded. In order to perform high-speed printing, it is necessary to stably and repeatedly eject ink droplets even at a high driving frequency. To that end, it is essential to improve the ink ejection stability at the printer head.

  As an ink corresponding to high-speed printing, a water-based ink that secures good ejection stability by controlling the viscosity with respect to the stretching deformation rate (shear rate) within a specific range is known (Patent Document 1).

Further, regarding oil-based inks, the following ink compositions are disclosed in patent literature.
Patent Document 2 describes that in oil-based inks, by using a vegetable oil and a specific hydrocarbon solvent in combination and setting the surface tension to 32 mN / m or more, it is possible to ensure high-speed ejection properties that can cope with a printing frequency exceeding 7 KHz. is doing.
Patent Document 3 describes that, in an oil-based ink, by using a high-boiling solvent having a boiling point of 150 ° C. or higher and a resin that can be dissolved therein, thickening in a nozzle can be suppressed and clogging can be prevented. is doing.
Patent Document 4 uses a specific carbon black and a specific organic solvent in an oil-based ink, and controls the average particle diameter of the pigment to 0.02 to 0.5 μm, thereby smoothly forming the slit path in the nozzle. It describes that it can pass through and prevent clogging.

  However, conventional oil-based inks cannot follow the high drive frequency in high-speed inkjet printers, for example, where the drive frequency of the printer head is 10 KHz or higher, and print quality such as bleeding due to changes in the amount of ink droplets or generation of satellite droplets. There remains a practical problem such as a drop or insufficient resupply of ink after ejection.

  In other words, oil-based inks containing a large amount of vinyl chloride resin or the like having poor solubility in organic solvents may cause uneven viscosity resistance of the ink when the shear rate frequently changes in the nozzle, It is conceivable that the ejection becomes unstable due to a sudden increase in viscosity due to volatilization of the solvent.

JP 2004-18535 A JP 2003-238852 A JP 2002-302629 A JP 2001-220527 A

  An object of the present invention is an oil-based pigment ink composition containing a pigment, an organic solvent, and a polymer compound, and improves the ejection stability during high-speed printing at a driving frequency of 10 KHz or more, thereby improving printer reliability, for example, Oil-based pigment ink that can achieve continuous mass printing of stable quality prints and can be printed on inexpensive printing media such as PVC (polyvinyl chloride) without a receiving layer and can withstand outdoor use. It is to provide a composition.

In order to solve the above problems, the present invention provides an oil-based pigment ink composition containing at least a pigment, an organic solvent and a polymer compound for use in an inkjet printer having a driving frequency of 10 KHz or more, preferably a driving frequency of 13 KHz or more. The viscosity measured at a shear rate of 1 × 10 ³ sec ⁻¹ at 25 ° C. was measured at a shear rate of 1 × 10 ⁴ sec ⁻¹ at 25 ° C. by a measurement method performed with an increase in shear rate using a rotary viscometer. Provided is an oil-based pigment ink composition, wherein the viscosity B is 1 to 30 mPa · s and the thixotropic coefficient A / B is 1.01 to 1.40.

  The present inventors have found that the ejection stability during high-speed printing of the oil-based pigment ink composition depends on the thixotropy coefficient A / B. In other words, if the thixotropy coefficient A / B of the ink is controlled within the range of 1.01-1.40, even if the shearing speed frequently changes in the nozzle, such as at a driving frequency of 10 KHz or more, the viscosity resistance of the ink is not good. The uniform change is suppressed, and the ejection stability during high-speed printing is improved. In particular, by controlling the thixotropy coefficient A / B in the range of 1.01-1.32, the ink composition can be stably used in higher speed ink jet printers having a driving frequency of 30 KHz.

Ink having a thixotropy coefficient A / B greater than 1.40 cannot follow a rapid increase in driving frequency, resulting in nonuniform droplet formation and unstable ejection. Further, an ink having a thixotropy coefficient A / B smaller than 1.01 has insufficient durability such as pigment fixability, water resistance and weather resistance of printed matter, and storage stability of the ink composition is poor. Become.

  Furthermore, in the present invention, the viscosity B of the oil-based pigment ink composition is controlled in the range of 1 to 30 mPa · s. An ink composition having a viscosity B greater than 30 mPa · s has extremely poor fluidity, while an ink composition having a viscosity B less than 1 mPa · s has an improper composition balance that is a constituent of oil-based ink, Insufficient durability such as pigment fixability and water resistance and weather resistance of printed matter.

  In the oil-based pigment ink composition of the present invention, various known pigments can be used as the pigment. The pigment includes achromatic and chromatic inorganic pigments and organic pigments. The amount of these pigments to be used is generally 0.1 to 10% by weight, preferably 0.2 to 7% by weight, more preferably, based on the total weight of the ink composition from the viewpoint of coloring power and ink fluidity. 0.3 to 6% by weight.

  Examples of inorganic pigments include titanium oxide, zinc oxide, zinc oxide, lithopone, iron oxide, aluminum oxide, silicon dioxide, kaolinite, montmorillonite, talc, barium sulfate, calcium carbonate, silica, alumina, cadmium red, red rose, molybdenum red, Chrome vermilion, molybdate orange, yellow lead, chrome yellow, cadmium yellow, yellow iron oxide, titanium yellow, chromium oxide, pyridian, cobalt green, titanium cobalt green, cobalt chrome green, ultramarine blue, ultramarine blue, bitumen, cobalt blue Cerulean blue, manganese violet, cobalt violet, mica and the like are used.

  When the ink composition of the present invention is used as a conductive ink composition in the production of an antireflection film or a transparent conductive film, the pigment is selected from aluminum, zirconium, gallium, zinc, titanium, tin, antimony and indium. Metal oxide fine particles containing at least one metal, specifically, conductive titanium oxide, tin-doped indium oxide (ITO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), Antimony-doped tin oxide (ATO), zirconium oxide, or the like is used.

  Organic pigments include azo, azomethine, polyazo, phthalocyanine, quinacridone, anthraquinone, indigo, thioindigo, quinophthalone, benzimidazolone, isoindoline, isoindolinone, diacetoacetone There are allirides. Carbon black made of acidic, neutral or basic carbon is also used.

  Examples of the pigment contained in the cyan ink composition include C.I. I. Pigment blue 1, 2, 3, 15: 3, 15: 4, 15:34, 16, 22, 60, and the like. Preferably, C.I. I. One or a mixture of two or more selected from CI Pigment Blue 15: 3 and 15: 4 is used.

  Examples of the pigment contained in the magenta ink composition include C.I. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 122, 123, 168, 184, 202, 209, C.I. I. Pigment violet 19 and the like. Preferably, C.I. I. Pigment red 57: 1, 122, 202, 209, C.I. I. One or a mixture of two or more selected from Pigment Violet 19 is used.

  Examples of the pigment contained in the yellow ink composition include C.I. I. Pigment Yellow 1, 2, 3, 12, 13, 14C, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 120, 128, 129, 130, 138, 150, 151, 154, 155, 180, 185 and the like. Preferably, C.I. I. One or a mixture of two or more selected from CI Pigment Yellow 14, 74, 83, 109, 110, 120, 150, 151, 155, and 180 is used.

  The pigments contained in the black ink composition include Mitsubishi Chemical Corporation HCF, MCF, RCF, LFF, SCF, Cabot Monarch, Legal, Degussa Huls Color Black, Special Black, Printex, Tokai Carbon Corporation Examples include company-made Toka Black and Columbian Raven. Preferably, Mitsubishi Chemical Corporation HCF # 2650, # 2600, # 2350, # 2300, MCF # 1000, # 980, # 970, # 960, MCF88, LFFMA7, MA8, MA11, MA77, MA100, Degussa Huls One or a mixture of two or more selected from Printex 95, 85, 75, 55, 45, 25, etc. are used.

  In the oil-based pigment ink composition of the present invention, the polymer compound is used as a pigment dispersant or / and a fixing resin. The pigment dispersant is excellent in affinity with the pigment to be used and has a function of stabilizing the dispersion. The fixing resin has excellent adhesion to the substrate and has an effect of imparting durability of the printed matter. The effect is exhibited as an ink by appropriately selecting a pigment dispersant and a fixing resin according to the type of pigment, organic solvent, printing medium, and the like. Some types of polymer compounds have both of the above functions.

  It is desirable that the pigment dispersant and the fixing resin have as low a solubility as possible in water or ethanol. That is, the pigment dispersant and the fixing resin remain on the surface or the surface layer of the substrate after printing by the ink jet recording method, and are dried and fixed. If the resin component is readily soluble in water, the water resistance of the printed matter is reduced, and the printed portion may flow due to rain or the like when used outdoors. Also, when using printed materials as posters, etc., there are cases where the surface is sprayed with a coating agent, etc., but since many coating agents contain an alcohol component as a solvent, polymer compounds are used as alcohol solvents. If it is easily soluble, the printed material may drop off due to the coating agent.

  As the pigment dispersant, an ionic or nonionic (low molecular weight) surfactant or an anionic, cationic or nonionic polymer compound is used, but the dispersion stability of the composition, water resistance, From the viewpoint of the strength of the printed matter such as scratch resistance, a polymer compound is preferred, and a polymer compound containing a cationic group or an anionic group is particularly preferred.

  Since the pigment dispersant stabilizes the dispersion of the pigment by an acid-base interaction between the pigment and the dispersant in an organic solvent, the pigment dispersant contains at least one of a cationic group or an anionic group which is a pigment adsorption site. It is important to control the type and amount of the cationic group or anionic group in the dispersant depending on the type of pigment.

  As a pigment dispersant which is a polymer compound, “SOLSPERSE” manufactured by Lubrizol, “DISPERBYK” manufactured by BYK Chemie, “EFKA” manufactured by Fuka Additives, “TEXAPHOR” manufactured by Cognis, etc. are commercially available. The ink composition of the invention can also be preferably used.

  Among these, SOLPERSE 24000, 32000, 32500, 32550, 32600, 35600, 35100, 36600, 37500, 39000 (above, manufactured by Lubrizol), DISPERBYK101, 109, 130, 161, 162, 163, 164, 165, 166, 167, 167, 168 (above, manufactured by Big Chemie), EFKA 4050, 4055, 4060 (above, manufactured by Fuka Additives), TEXAPHOR P60, P61 P63 and SF73 (manufactured by Cognis) are particularly preferable. By using these in accordance with the type of pigment and solvent, the pigment can be favorably dispersed in the ink composition.

  As the fixing resin, at least one resin selected from the group consisting of acrylic resins, polyester resins, polyurethane resins, vinyl chloride resins, and nitrocellulose is preferably used. These resins are basically excellent in fixing property to vinyl chloride, and water resistance, dispersion stability, printability, etc. can be controlled by changing the types of functional groups contained in the resin and the resin structure. it can. Particularly preferred is a vinyl chloride resin.

  Specifically, as the acrylic resin, “John Krill” manufactured by Johnson Polymer Co., Ltd., “S-Lec P” manufactured by Sekisui Chemical Co., Ltd., and as polyester resin, “Elitel” manufactured by Unitika Co., Ltd., “Toyobo Co., Ltd.” “Byron” and polyurethane resins include “Byron UR” manufactured by Toyobo Co., Ltd., “NT-Hilamic” manufactured by Dainichi Seika Co., Ltd., “Crisbon” manufactured by Dainippon Ink & Chemicals, Inc. “Nipporan” and vinyl chloride resins include “Solvine” manufactured by Nissin Chemical Industry Co., Ltd., “Sekisui PVC-TG, Sekisui PVC-HA” manufactured by Sekisui Chemical Co., Ltd., “UCAR Series” manufactured by Dow Chemical Company, and nitrocellulose Asahi Kasei Corporation “HIG, LIG, SL, VX”, Daicel Chemical Industries, Ltd. The company made "industrial nitrocellulose RS, SS" and the like are preferable.

  Such a fixing resin preferably has a weight average molecular weight of 2,000 to 100,000, more preferably 5,000 to 70,000. When the weight average molecular weight of the fixing resin is less than 2000, the effect of steric repulsion is hardly obtained when the anionic resin is adsorbed to the pigment particles in the ink composition, and the effect of improving the storage stability is small. It is difficult to obtain the effect of improving the fixability between the pigment particles and the pigment particles, and there is a possibility that the coating strength cannot be sufficiently obtained. On the other hand, when the weight average molecular weight of the fixing resin exceeds 100,000, the effect is saturated and the viscosity of the ink is increased, and the fluidity may not be sufficiently exhibited.

  In addition, in this specification, the weight average molecular weight of a high molecular compound means the value calculated | required as a polystyrene conversion molecular weight by gel permeation chromatography.

  In the present invention, when a pigment dispersant made of a polymer compound is used, the amount of the pigment dispersant used varies depending on the type of pigment, the solvent used for dispersion, the dispersion conditions, etc. In particular, when an organic pigment is used, 40 to 150% by weight is more preferable, and when an inorganic pigment is used, 5 to 60% by weight is more preferable.

  When a fixing resin made of a polymer compound is used, the amount of the fixing resin used varies depending on the type and molecular weight of the fixing resin, the type of the pigment and the solvent, and the like. % By weight is preferred.

  In the oil-based pigment ink composition of the present invention, in order to achieve both the discharge stability during high-speed printing and the fixability of the pigment, it is particularly preferable to use a vinyl chloride resin having a weight average molecular weight of 10,000 to 25,000 as the polymer compound. preferable. This is because the solubility in an organic solvent is high and there is an action of promoting the dispersion stabilization of the pigment. As a result, it is easy to control the thixotropy coefficient A / B of the ink composition within a range of 1.01 to 1.40, and the viscosity resistance of the ink composition is suppressed from changing unevenly, and the ejection stability during high-speed printing is suppressed. Improves. The amount of the polymer compound added is preferably in the range of 0.5 to 10.0% by weight and more preferably in the range of 1.0 to 7.0% by weight with respect to the total weight of the ink composition.

  Specific examples of the polymer compound as described above include Solvain CL (molecular weight 25000), AL (molecular weight 22000), TAO (molecular weight 15000), and MK6 (molecular weight 13000) (manufactured by Nissin Chemical Industry Co., Ltd.). ), UCAR Solution Vinyl Resin VYHD (molecular weight 22000), VMCC (molecular weight 19000), VMCA (molecular weight 15000), VERR-40 (molecular weight 15000), VAGD (molecular weight 22000), VAGC (molecular weight 24000), same VROH (molecular weight 15000), Ucarmag 569 (molecular weight 22000) (manufactured by Dow Chemical Co., Ltd.) and the like are included.

  In the oil-based pigment ink composition of the present invention, various known organic solvents can be used as the organic solvent. Particularly preferred are mono- and polyalkylene glycol derivatives (hereinafter collectively referred to as (poly) alkylene glycol derivatives) and methoxybutyl acetate derivatives.

  These organic solvents are generally used in a proportion of 30 to 99% by weight, preferably 50 to 98% by weight, based on the total weight of the ink composition. In particular, the (poly) alkylene glycol derivative or methoxybutyl acetate derivative is generally used in a proportion of 30 to 99% by weight, preferably 50 to 90% by weight, based on the total weight of the ink composition.

  The (poly) alkylene glycol derivative has (poly) alkylene glycol, that is, a compound having two free hydroxyl groups such as alkylene glycol, or a free hydroxyl group such as a monoalkyl ether compound or monoalkyl ester compound of (poly) alkylene glycol. Compounds having one, compounds having no free hydroxyl group such as monoalkyl ether monoalkyl ester compounds, dialkyl ether compounds, dialkyl ester compounds of (poly) alkylene glycol, and the like.

  Among these, monoalkyl ether monoalkyl ester compounds, dialkyl ether compounds, and dialkyl ester compounds are particularly preferred as compounds having no free hydroxyl group, and monoalkyl ether monoalkyl ester compounds or dialkyl ester compounds are further preferred as compounds having an ester group. Is most preferred. These compounds tend to give good results in the fluidity, fixability, and storage stability of the ink.

  Examples of such (poly) alkylene glycol monoalkyl ether monoalkyl ester compounds, dialkyl ester compounds or dialkyl ether compounds include ethylene glycol monoalkyl ether monoalkyl esters, diethylene glycol monoalkyl ether monoalkyl esters, triethylene glycol monoalkyl ethers. Monoalkyl ester, tetraethylene glycol monoalkyl ether monoalkyl ester, propylene glycol monoalkyl ether monoalkyl ester, dipropylene glycol monoalkyl ether monoalkyl ester, tripropylene glycol monoalkyl ether monoalkyl ester, tetrapropylene glycol monoalkyl ether mono Alkyl ester, D Lenglycol dialkyl ester, diethylene glycol dialkyl ester, triethylene glycol dialkyl ester, propylene glycol dialkyl ester, dipropylene glycol dialkyl ester, tripropylene glycol dialkyl ester, ethylene glycol dialkyl ether, diethylene glycol dialkyl ether, triethylene glycol dialkyl ether, propylene glycol dialkyl Examples include ether, dipropylene glycol dialkyl ether, and tripropylene glycol dialkyl ether. Among these, one of them can be used alone, or two or more of them can be mixed and used.

  Specific examples of methoxybutyl acetate derivatives include 1-methoxybutyl acetate, 2-methoxybutyl acetate, 3-methoxybutyl acetate, and 4-methoxybutyl acetate, but 3-methoxybutyl acetate is generally inexpensive. And often used. However, when 1-methoxybutyl acetate, 2-methoxybutyl acetate, and 4-methoxybutyl acetate are used as the ink solvent, the same effect as 3-methoxybutyl acetate is exhibited.

  In the present invention, in addition to the above (poly) alkylene glycol derivative and methoxybutyl acetate derivative, the use of a solvent that dissolves vinyl chloride and fixes the pigment can improve the fixability of the pigment. preferable. Solvents that dissolve vinyl chloride include ketone compounds such as acetone, methyl ethyl ketone, and cyclohexanone, oxygen-containing heterocyclic compounds such as tetrahydrofuran and tetrahydropyran, and nitrogen-containing heterocyclic compounds such as N-alkyl-2-pyrrolidone. These solvents for dissolving vinyl chloride are usually used in a proportion of 1 to 30% by weight, preferably 5 to 28% by weight, based on the total weight of the ink composition.

  Of the solvents that dissolve vinyl chloride, ketone compounds and tetrahydrofuran have excellent solubility in vinyl chloride, but acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl normal butyl ketone, cyclohexanone, methylcyclohexanone, tetrahydrofuran, etc. only have a strong odor. In addition, those designated as organic solvents under the Industrial Safety Standards Law, and those containing 5% by weight or more of these compounds in the total ink composition can only handle those with specific qualifications, are obligated to undergo a health checkup, etc. There are limitations and handling problems.

  Among the ketone compounds and tetrahydrofuran derivatives other than the above, those having a low molecular weight are excellent in the solubility of vinyl chloride, but many of them have a low flash point, and when used as a solvent for an ink composition, There is a high possibility that the flash point will be less than 61 ° C., and may be restricted during transportation or storage. In addition, these compounds have a strong odor, and even when added in a small amount, there is a risk of generating an odor. High molecular weight compounds have a high flash point and a low odor, but they lack the ability to dissolve PVC and may not sufficiently fix the pigment to the substrate.

  In contrast, many heterocyclic compounds do not fall under the rules of the Industrial Safety and Health Act, and are excellent in safety and have low odor. Are better. That is, the heterocyclic compound has a performance that is very suitable as an organic solvent for the ink as compared with the above-described ketone compound.

  Among the heterocyclic compounds, oxygen-containing heterocyclic compounds and nitrogen-containing heterocyclic compounds are particularly preferable because they are particularly excellent in safety such as flash point and toxicity. Among oxygen-containing heterocyclic compounds, compounds having a lactone structure such as 2-acetylbutyrolactone, γ-butyrolactone, δ-lactone, and ε-caprolactone are often less odorous and are particularly suitable as ink solvents from the viewpoint of safety. preferable.

  In particular, a heterocyclic compound having a lactam structure such as N-alkyl-2-pyrrolidone is preferable because it has a high flash point, a low odor, and excellent vinyl chloride solubility. Specifically, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N- (2-hydroxyethyl) -2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, N-octyl-2-pyrrolidone, N-dodecyl-2-pyrrolidone, N-vinyl-2-pyrrolidone and the like can be mentioned. In particular, 2-pyrrolidone, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone have low viscosity, low odor, excellent solubility in vinyl chloride, good biodegradability, and low acute toxicity. It is particularly preferable from the viewpoint of safety.

  The oil-based pigment ink composition of the present invention achieves a thixotropy coefficient A / B in the range of 1.01-1.40, which is one of the features of the present invention, and discharge stability and pigment fixability during high-speed printing. As a preferable means for achieving both, a (poly) alkylene glycol derivative and / or a methoxybutyl acetate derivative as an organic solvent and a vinyl chloride resin having a weight average molecular weight of 10,000 to 25,000 as a polymer compound may be used. More preferably, a solvent for dissolving vinyl chloride such as N-alkyl-2-pyrrolidone is blended. That is, in such a combination, the vinyl chloride resin is uniformly dissolved in the solvent and the interaction of the pigment with the dispersed particles is small, so that the fluidity in the printer head tube and the formation of dot droplets are uniform. The ink composition is particularly suitable for use in a high-speed ink jet printer in which the drive frequency of the printer head is 10 KHz or higher, particularly 13 KHz or higher.

  The oil-based pigment ink of the present invention is required to finely disperse the pigment and stably exist in the organic solvent, and to adjust the viscosity B of the ink in the range of 1 to 30 mPa · s. And using a stirrer.

Any disperser that is generally used can be used as the disperser. For example, container drive media mills such as ball mills and planetary ball mills, medium agitation mills such as sand mills and stirring tank mills, kneaders such as kneaders and three roll mills, agitators such as dispersers, mixers such as line mixers, high-pressure injection mills , Homogenizer, ultrasonic wave and the like. In addition, for the purpose of removing coarse particles of pigment, classification treatment such as centrifuge, filter, and cross flow may be performed. As dispersion media used in the disperser, glass beads, steel beads, ceramic beads, etc. are used. It is done. Among these, it is preferable to use ceramic beads having a diameter of 0.01 to 1.0 mm. Dispersion conditions are not particularly limited, but in a sand mill, it is preferable to carry out at a ceramic bead filling rate of 50 to 90% and a peripheral speed of 5 to 20 m / sec.

  In addition to the colorant, organic solvent, and polymer compound, the oil-based pigment ink composition of the present invention includes a pH adjuster, a surfactant, a surface conditioner, a leveling agent, an antifoaming agent, an antioxidant, if necessary. Known general additives such as charge imparting agents, bactericides, antiseptics, deodorants, charge control agents, wetting agents, anti-skinning agents, perfumes, and pigment derivatives can be used.

  The oil-based pigment ink composition of the present invention, particularly the oil-based pigment ink composition for an ink jet recording system, preferably has a surface tension at 25 ° C. of 20 to 35 mN / m. The pigment particles preferably have a dispersion average particle size of 30 to 200 nm, more preferably 50 to 160 nm. In order to avoid clogging at the head, the maximum dispersed particle size of the pigment particles is preferably 1000 nm or less.

  The oil-based pigment ink composition of the present invention can be used as printing ink and ink for writing instruments for all recording methods such as inkjet printing, offset printing, gravure printing, screen printing, thermal transfer printing, etc. Is preferred.

  Hereinafter, examples of the present invention will be described in more detail. In the examples, “parts” means “parts by weight” unless otherwise specified.

Example 1
The following components were dispersed in the following proportions using a zirconia bead having a diameter of 0.3 mm for 2 hours using a paint conditioner (manufactured by Toyo Seiki Co., Ltd.), followed by classification for 30 minutes using a centrifuge at 14,000 G. Dispersion A was obtained.
Carbon black MA8 (carbon black pigment manufactured by Mitsubishi Chemical Corporation) 25.0 parts SOLPERSE 24000 (dispersant, manufactured by Lubrizol) 12.0 parts Propylene glycol diacetate (organic solvent) 63.0 parts

The dispersion A and the following components were measured in a beaker, stirred for 30 minutes with a magnetic stirrer, and then suction filtered using glass fiber filter GFP (manufactured by Kiriyama Seisakusho Co., Ltd., supplemental particles 0.8 μm) to obtain an oily substance. Black ink composition A was prepared.
Dispersion A 12.0 parts UCAR Solution Vinyl Resin VYHD (polymer compound, molecular weight 22000, vinyl chloride resin manufactured by Dow Chemical Company) 2.0 parts ethylene glycol monobutyl ether acetate (organic solvent) 40.0 parts dipropylene glycol Dimethyl ether (organic solvent) 25.0 parts N-methyl-2-pyrrolidone (organic solvent) 21.0 parts

(Example 2)
A dispersion B was obtained by repeating the same procedure as in Example 1 except that the following components were used.
Fastogen Blue TGR (copper phthalocyanine blue pigment manufactured by Dainippon Ink and Chemicals, Inc.) 20.0 parts SOLPERSE 5000 (additive, manufactured by Lubrizol) 1.0 part BYK161 (dispersant, manufactured by Big Chemie) 35.0 parts dipropylene Glycol monomethyl ether acetate (organic solvent) 44.0 parts

An oily cyan ink composition B was prepared by repeating the same procedure as in Example 1 except that this dispersion B and the following components were used.
Dispersion B 18.0 parts UCAR Solution Vinyl Resin VMCC (polymer compound, molecular weight 19000, vinyl chloride resin manufactured by Dow Chemical Company) 3.3 parts dipropylene glycol monomethyl ether acetate (organic solvent) 43.7 parts 3- Methoxybutyl acetate (organic solvent) 20.0 parts N-ethyl-2-pyrrolidone (organic solvent) 15.0 parts

(Example 3)
The same procedure as in Example 1 was repeated for the following composition to obtain Dispersion C.
Hosterperm Pink EB transp. (Clariant quinacridone pigment) 20.0 parts SOLPERSE 32500 (dispersing agent, manufactured by Lubrizol) 30.0 parts ethylene glycol monobutyl ether acetate (organic solvent) 50.0 parts

The same procedure as in Example 1 was repeated for this dispersion C and the following composition to prepare an oily magenta ink composition C.
Dispersion C 22.5 parts Solvain AL (polymer compound, molecular weight 22000, vinyl chloride resin manufactured by Nissin Chemical Industry Co., Ltd.) 2.7 parts ethylene glycol monobutyl ether acetate (organic solvent) 34.8 parts dipropylene glycol dimethyl ether (Organic solvent) 25.0 parts N-methyl-2-pyrrolidone (organic solvent) 15.0 parts

Example 4
The same procedure as in Example 1 was repeated for the following composition to obtain a dispersion D.
Novoperm Yellow 4G (azo pigment manufactured by Clariant) 18.0 parts Hostapell Yellow H4G-N (azo pigment manufactured by Clariant) 2.0 parts SOLPERSE 32500 (dispersant, manufactured by Lubrizol) 50.0 parts 3-methoxybutyl acetate ( Organic solvent) 30.0 parts

An oily yellow ink composition D was prepared by repeating the same procedure as in Example 1 for this dispersion D and the following composition.
Dispersion D 15.0 parts UCAR Solution Vinyl Resin VROH (polymer compound, molecular weight 15000, vinyl chloride resin manufactured by Dow Chemical Company) 1.5 parts propylene glycol diacetate (organic solvent) 40.0 parts propylene glycol monomethyl ether (Organic solvent) 35.0 parts Cyclohexanone (organic solvent) 8.5 parts

(Example 5)
The same procedure as in Example 1 was repeated, except that the same amount of Byron UR8300 (polymer compound, polyurethane resin manufactured by Toyobo Co., Ltd.) was used instead of UCAR Solution Vinyl Resin VYHD in Example 1. Composition E was obtained.

(Example 6)
The composition of 20.0 parts of SN-100P (pigment, antimony-doped tin oxide manufactured by Ishihara Sangyo Co., Ltd.), 30.0 parts of SOLSPERSE 32500, and 50.0 parts of ethylene glycol monobutyl ether acetate (organic solvent) is the same as in Example 1. This procedure was repeated to prepare dispersion F. Next, an oily conductive ink composition F was obtained by repeating the same procedure as in Example 2, except that the same amount of the dispersion F was used instead of the dispersion B in Example 2.

(Comparative Example 1)
In Example 1, instead of UCAR Solution Vinyl Resin VYHD, the same amount of Solvein C5R (polymer compound, molecular weight 27000, vinyl chloride resin manufactured by Nissin Chemical Industry Co., Ltd.) was used. The procedure was repeated to obtain an oily black ink composition G.

(Comparative Example 2)
In Example 2, instead of UCAR Solution Vinyl Resin VMCC, the same amount of sorbine CH (polymer compound, molecular weight 38000, vinyl chloride resin manufactured by Nissin Chemical Industry Co., Ltd.) was used and replaced with N-ethyl-2-pyrrolidone. The same procedure as in Example 1 was repeated except that N-dodecyl-2-pyrrolidone was used to obtain an oily cyan ink composition H.

(Comparative Example 3)
Example 1 except that 1.0 part of Johncrill 680 (polymer compound, molecular weight 4900, manufactured by Johnson Polymer Co., Ltd.) and 1.7 parts of ethylene glycol monobutyl ether acetate were used instead of Solvein AL in Example 3. The same procedure was repeated to obtain an oily magenta ink composition I.

(Comparative Example 4)
An oily yellow ink composition J was prepared by repeating the same procedure as in Example 1 for the dispersion D in Example 4 and the following composition.
Dispersion D 5.0 parts UCAR Solution Vinyl Resin VROH (polymer compound, molecular weight 15000, vinyl chloride resin manufactured by Dow Chemical Company) 0.2 parts ethylene glycol monomethyl ether acetate (organic solvent) 34.8 parts methyl isobutyl ketone (Organic solvent) 50.0 parts Tetrahydrofuran (Organic solvent) 10.0 parts

For the ink compositions prepared in Examples and Comparative Examples, the viscosity (thixotropic coefficient A / B), printer operability and storage stability of each composition, and fixability of the pigment to the PVC film were measured and evaluated as follows. did. The results are shown in Table 1. In addition, FIG. 1 shows changes in viscosity with respect to an increase in shear rate of the ink compositions prepared in Examples 1 and 2.

<Viscosity>
The oil-based pigment ink composition was gradually increased in shear rate at 25 ° C. by using a double-cylindrical high shear sensor HS25 with a rotational viscometer Rheostress 600 (manufactured by Eihiro Seiki Co., Ltd.). The viscosity A at 1 × 10 ³ sec ⁻¹ and the viscosity B at a shear rate of 1 × 10 ⁴ sec ⁻¹ were measured.

<Printer operability>
Using an ink jet printer with a drive frequency of 13 KHz, the ink cartridge was filled with the oil-based pigment ink composition, a continuous printing test was performed, and ejection stability was evaluated according to the following criteria.
A: There is no ejection failure and the discharge state is extremely stable. ○: Satellite droplets are slightly generated, but the discharge state is stable. Δ: Satellite droplets are generated and the state is slightly unstable. Lots of omissions and satellite drops occur, resulting in an unstable state

<Fixability>
The oil-based pigment ink composition was subjected to No. 2 in a thermostatic chamber at a temperature of 25 ° C. and a humidity of 30%. Using a 6 wire bar (manufactured by Toyo Seiki Co., Ltd.), it was applied to glossy polyvinyl chloride (manufactured by Lintec Corporation, P-224RW), and after 1 hour, a scrub test with a finger was performed for 30 seconds. The fixability of the pigment was evaluated according to the following criteria.
◎: No scrub marks ○: Scratch marks slightly generated, but no problem in practical use △: Scrub marks generated ×: Scrub marks generated, substrate visible

<Storage stability>
After sealing the oil-based pigment ink composition in a bottle with a lid and leaving it in a thermostatic bath at 60 ° C. for 30 days, suction filtration is performed using glass fiber filter paper GFP (manufactured by Kiriyama Seisakusho Co., Ltd., supplemental particles 0.8 μm). The state of the residue on the filter paper was confirmed. The storage stability of the ink composition was evaluated according to the following criteria.
○: No residue △: Some residue ×: Large amount of residue

It is a graph which shows the viscosity change with respect to the increase in the shear rate of the ink composition prepared in Example 1 and 2.

Claims (2)

In an oily pigment ink composition containing at least a pigment, an organic solvent, and a polymer compound for use in an inkjet printer having a driving frequency of 10 KHz or more, a measurement method performed with an increase in shear rate using a rotary viscometer, When the viscosity measured at a shear rate of 1 × 10 ³ sec ⁻¹ is A and the viscosity measured at a shear rate of 1 × 10 ⁴ sec ⁻¹ is B at 25 ° C., the viscosity B is 1 to 30 mPa · s, An oil-based pigment ink composition having a thixotropic coefficient A / B of 1.01 to 1.40.   The oil-based pigment ink composition according to claim 1, which is an ink composition for use in an ink jet printer having a driving frequency of 13 KHz or more.

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