JP5724165B2 - Ink jet ink and ink jet recording method - Google Patents

Description

  The present invention relates to a water-based inkjet ink that exhibits good recording characteristics and image quality with respect to a non-water-absorbing recording medium, and further exhibits high image abrasion resistance, and an inkjet recording method using the same.

  In recent years, an inkjet recording method can be easily and inexpensively produced an image, and thus has been applied to various printing fields such as photographs, various printing, marking, and special printing such as a color filter.

  As an inkjet ink used in such an inkjet recording method, an aqueous inkjet ink composed of water and a small amount of an organic solvent, a non-aqueous inkjet ink substantially free of water using an organic solvent, and a solid ink heated at room temperature. There are a plurality of ink-jet inks such as hot-melt inks that are melted and printed, and actinic ray-curable ink-jet inks that are cured by actinic rays such as ultraviolet rays after printing.

  In recent years, inkjet inks that can be directly printed on non-water-absorbing recording media such as vinyl chloride sheets have been developed as industrial inkjet inks. Examples of these ink-jet inks include solvent ink-jet inks using an organic solvent as a vehicle, and ultraviolet curable ink-jet inks mainly composed of a polymerizable monomer. The solvent inkjet ink has a problem that there are many VOCs (volatile organic solvents) which are socially problematic because the solvent is dried and evaporated in the atmosphere. In addition, there are concerns about odors and safety effects on workers, and facilities such as sufficient ventilation are required. On the other hand, UV curable ink-jet inks are cured immediately after printing, so VOC is close to zero, but there are problems that many monomers have skin sensitization depending on the monomers used, and expensive UV irradiation light source There is a restriction that it is incorporated into an inkjet printer.

  In such a background, development of an ink-jet ink that can be directly printed on a non-water-absorbing recording medium with a water-based ink-jet ink that has a small environmental burden and has been widely used in home printers and the like has been underway.

  A water-based inkjet ink containing a water-soluble organic solvent selected from the group consisting of glycol and glycol ether has been proposed. In addition, inkjet inks have been proposed that contain a graft copolymer binder that has a hydrophobic main chain and nonionic, hydrophilic side chains, dissolves in an aqueous vehicle, but is insoluble in water (eg, , See Patent Document 1). Further, water-based pigment inks are disclosed in which a recording medium coated with a vinyl film or a vinyl resin is used as a recording medium and heat-fixed using an ink-soluble resin (see, for example, Patent Documents 2 and 3). In addition, many water-based inkjet inks to which resin fine particles not dissolved in the ink are added as a binder resin have been proposed (see, for example, Patent Documents 4 to 7).

  However, the ink-jet ink described in each of these patent documents lacks the texture of the image depending on the type of the recording medium, lacks the ejection stability in ink-jet, nozzle clogging recovery, and ink storage. The development of inkjet ink that solves these problems is desired.

JP 2000-44858 A JP 2005-113147 A JP 2007-297586 A JP 2004-114692 A JP 2005-220352 A JP 2006-22328 A JP 2006-282822 A

  The present invention has been made in view of the above-mentioned problems, and the purpose thereof is to obtain a recorded image with good gloss, and to obtain an image with good abrasion resistance and banding resistance. An object of the present invention is to provide a water-based inkjet ink excellent in ink storage stability and head maintenance returnability, and an inkjet recording method using the same.

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

  1. a) Carbon black having a pH measured in accordance with JIS K 6221 of 6.0 or more and 8.0 or less, b) a polymer dispersant having an acid value of less than 50 mgKOH / g, c) acid neutralized by amine A water-soluble resin having water groups or water-dispersible resin particles, d) at least one water-soluble organic solvent selected from glycol ethers and 1,2-alkanediols having 4 or more carbon atoms, and e) water. An inkjet ink characterized by the above.

  2. The mass ratio of the water-soluble resin or water-dispersible resin fine particles to the carbon black (water-soluble resin or water-dispersible resin fine particles / carbon black) is 1.0 or more and 3.0 or less, The inkjet ink according to 1.

  3. 3. The inkjet ink as described in 1 or 2 above, wherein a mass ratio of the polymer dispersant to the carbon black (polymer dispersant / carbon black) is 0.2 or more and 1.0 or less.

  4). 4. The inkjet ink as described in any one of 1 to 3 above, which contains a silicone-based surfactant or a fluorine-based surfactant.

  5. The glycol ether is at least one selected from diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether and propylene glycol monopropyl ether. The inkjet ink of any one of 1-4.

  6). 5. The ink-jet ink according to any one of 1 to 4, wherein the 1,2-alkanediol is 1,2-hexanediol.

  7). 7. The total amount of the glycol ethers or 1,2-alkanediols having 4 or more carbon atoms is 5.0% by mass or more and 30% by mass or less. Inkjet ink.

  8). 8. An ink jet recording method comprising recording on a non-water-absorbing recording medium using the ink jet ink according to any one of 1 to 7 above.

  9. 9. The ink jet recording method according to 8 above, wherein recording is performed by heating the non-water-absorbing recording medium so that the surface temperature is 40 ° C. or higher and 80 ° C. or lower.

  10. 10. The inkjet recording according to 8 or 9, further comprising a step of drying the inkjet ink applied to the non-water-absorbing recording medium by a drying unit after discharging the inkjet ink onto the non-water-absorbing recording medium. Method.

  According to the present invention, a recorded image having a good gloss can be obtained, and an image having a good rubbing resistance and banding resistance can be obtained. Further, the ejection stability, the storage stability of ink, and the head maintenance recovery ability are excellent. An aqueous inkjet ink and an inkjet recording method using the same can be provided.

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

  Conventionally, when recording is performed on a non-water-absorbing medium using an ink-jet ink mainly composed of water (hereinafter also referred to as a water-based ink-jet ink), the non-water-absorbing medium has a high ink absorbing ability such as paper. Ink is not absorbed as compared to a recording medium, and spots (hereinafter also referred to as beading) due to coalescence of ink droplets that have landed on the recording medium often occur, resulting in a satisfactory recorded image. The current situation was difficult. In particular, when a recording medium having a low surface energy, such as a recording medium made of polyvinyl chloride, is used, beading due to coalescence of ink droplets is low because water-based inkjet ink has low wettability with respect to those recording media. It was easy to occur.

  The inventor of the present invention has mainly studied the ink-jet ink technology exhibiting good recording characteristics with respect to a non-water-absorbing recording medium, and found that a water-soluble resin having an acidic group neutralized with an amine which is a requirement of the present invention or At least one water-soluble organic solvent selected from water-dispersible resin fine particles (hereinafter collectively referred to as “amine neutralized resin”) and glycol ethers and 1,2-alkanediols having 4 or more carbon atoms It has been found that beading generated on a non-water-absorbing recording medium can be effectively suppressed in a water-based ink-jet ink containing the above. However, in subsequent studies, it has been newly found that there is a problem that image gloss in black ink is likely to deteriorate.

  As a result of further intensive studies on the above problems, the present inventor has obtained carbon black having a pH measured in accordance with JIS K 6221 as a pigment of 6.0 or more and 8.0 or less, and an acid as a pigment dispersant. By using a polymer dispersant having a value of less than 50 mgKOH / g, it has been found that image gloss deterioration can be suppressed, and as soon as the present invention has been achieved.

  Although the mechanism by which the objective effect of the present invention can be achieved by the inkjet ink having the configuration defined in the present invention is not sufficiently clarified, the following estimation is made. That is, when an ink containing an amine neutralized resin is recorded on a medium, it is considered that the amine volatilizes as the image is dried, and the ink pH on the image is lowered. Carbon black with a pH of less than 6.0 has a large amount of acidic groups on the surface, so it is susceptible to pH fluctuations, and it is thought that pigments become unstable due to a decrease in pH and pigments tend to aggregate. . It is presumed that this agglomeration triggers the gloss degradation of the recorded image. In particular, when a non-water-absorbing recording medium is used, the ink is less likely to permeate, and the ink tends to stay on the image surface.

  In addition, when a pigment dispersant having an acid value of 50 mgKOH / g or more is used, since there are many acidic groups in the dispersant that exists in the vicinity of the pigment and stabilizes the dispersion, the same as the above estimation It is considered that due to the mechanism, pigment aggregation occurs with drying, resulting in deterioration of gloss.

  Therefore, by using carbon black having a pH of 6.0 or more and 8.0 or less and a polymer dispersant having an acid value of less than 50 mgKOH / g, pigment aggregation in the ink drying process can be suppressed. Therefore, it is estimated that the gloss deterioration can be effectively suppressed.

  Hereinafter, the details of the inkjet ink (hereinafter also simply referred to as ink) and the inkjet recording method of the present invention will be described.

〔Carbon black〕
The ink of the present invention is characterized by containing carbon black whose pH measured in accordance with JIS K 6221 is in the range of 6.0 to 8.0. Here, the pH measured according to JIS K 6221, which is a JIS test method, is specifically, after adding 100 ml of distilled water to 10 g of carbon black, boiling on a hot plate for 15 minutes and cooling to room temperature. The supernatant was removed with a centrifuge, and the pH of the mud was measured with a glass electrode pH meter.

  The carbon black according to the present invention is produced by pyrolysis or incomplete combustion using hydrocarbons such as oil and natural gas as raw materials. The pyrolysis method is divided into a thermal method using natural gas and an acetylene decomposition method using acetylene gas. The incomplete combustion method is classified into a gas furnace method using natural gas as a raw material, an oil furnace method using aromatic hydrocarbon oil as a raw material, a contact method, and a lamp / pine smoke method. Carbon black produced by the currently mainstream furnace method is also called furnace black and is preferably used in the present invention.

The specific surface area of the carbon black according to the present invention is preferably 200 m ² / g or more and 380 m ² / g or less. By having a specific surface area of 200 m ² / g or more, it is easy to obtain a higher print density and gloss. The upper limit of the specific surface area is not limited to obtain the effects of the present invention, but can stably produce carbon black, and dispersion stability It is preferable that it is 380 m < ² > / g or less from a viewpoint which is easy to acquire property. In addition, the specific surface area said by this invention is a value measured by a nitrogen adsorption method, and is computed based on the test method shown by JISK6217 (1997).

  The volume average particle diameter of the carbon black contained in the ink of the present invention in the dispersed state is preferably 70 nm or more and less than 200 nm. If the volume average particle size is 70 nm or more, the storage stability of the ink can be kept relatively stable, and if it is less than 200 nm, it is easy to obtain a high print density and gloss. The particle size of the pigment dispersion can be determined by a commercially available particle size measuring instrument using a dynamic light scattering method, an electrophoresis method, or the like. Accurate and frequently used. As a specific measurement of the volume particle diameter, for example, it can be obtained by a commercially available particle size measuring instrument using a light scattering method, an electrophoresis method, a laser Doppler method, etc. A laser diffraction particle size measuring device SLAD1100 manufactured by Shimadzu Corporation, a particle size measuring device (HORIBA LA-920), a Malvern Zetasizer 1000, and the like.

  The carbon black according to the present invention is preferably used after being dispersed by a disperser together with a polymer dispersant and other additives necessary for various desired purposes. As the disperser, a conventionally known ball mill, sand mill, line mill, high-pressure homogenizer, or the like can be used. In particular, the particle size distribution of the ink produced by dispersion with a sand mill is sharp and preferable. The material of the beads used for sand mill dispersion is preferably zirconia or zircon from the viewpoint of contamination of bead fragments and ionic components. Furthermore, the bead diameter is preferably 0.3 mm to 3 mm.

(Polymer dispersant)
One characteristic of the ink of the present invention is that it contains a polymer dispersant having an acid value of less than 50 mgKOH / g. In the dispersion of carbon black, it is preferable to prepare a pigment dispersion using a polymer dispersant having an acid value of less than 50 mgKOH / g and mix this with other components to obtain an ink.

  The mass ratio of the polymer dispersant to the carbon black (polymer dispersant / carbon black) is preferably 0.2 or more and 1.0 or less. By setting it within this range, it becomes easy to improve the dispersion stability of the pigment in the ink, and it is easy to suppress fluctuations in ink physical properties and pigment particle diameter during long-term storage.

  The structure of the polymer dispersant preferably includes a polyethylene oxide group. By including the polyethylene oxide group, it becomes easy to increase the image gloss after printing as well as stabilizing the dispersion of the pigment.

  Examples of the polymer dispersant used in the present invention include a modified polyacrylate, a modified polyurethane, an alkylphenol ethylene oxide adduct, a polyoxyethylene fatty acid ester, a polypropylene glycol ethylene oxide adduct, and a modified product of a styrene-maleic acid copolymer. be able to. Specific examples of the polymer dispersant that can be used in the present invention include Disperbyk-190 (manufactured by Big Chemie Japan, acid value 10 mgKOH / g), Disperbyk-2010 (manufactured by Big Chemie Japan, acid value 20 mgKOH / g), Disperbyk -2015 (manufactured by Big Chemie Japan, acid value 10 mgKOH / g), Floren TG-750W (manufactured by Kyoeisha Chemical Co., acid value 40 mgKOH / g), Pluronic F-68 (manufactured by ADEKA, acid value 0 mgKOH / g) and the like. However, it is not limited to these.

  The acid value in the present invention refers to the number of milligrams of potassium hydroxide required to neutralize the acid contained in 1 g of the polymer dispersant non-volatile component. The acid value measurement and hydrolysis acid value measurement of JIS K 0070 ( An example is a method of applying total acid number measurement). In many cases, the acid value of the product is provided by the manufacturer. At that time, it is shown as an acid value in 1 g of the product, and when the volatile component such as a solvent is contained in the dispersant product, it is assumed to be converted to a non-volatile component of 100%.

  The polymer dispersant according to the present invention may be applied to a general dispersion process, that is, a method of mixing and dispersing a polymer dispersant, carbon black, and a dispersion medium, or a so-called microcapsule pigment. It may be applied to manufacturing. As a method for producing a microcapsule pigment, a low acid value dispersant and a pigment are kneaded in the presence of an organic solvent, and the organic solvent is removed while dispersing in the presence of water and a basic compound. Examples thereof include a method and a method in which a crosslinkable or polymerizable compound is added to the surface of a pigment dispersed with a small amount of a dispersant and reacted.

[Amine neutralized resin]
The ink of the present invention includes a water-soluble resin having an acidic group neutralized with an amine or water-dispersible resin fine particles having an acidic group neutralized with an amine. By including an amine neutralizing resin, the durability of the image film is improved, water resistance is imparted after the amine has volatilized on the recording medium, and during drying, beading and Since it becomes easy to prevent color bleeding, the ink of the present invention can form a particularly good image on a non-water-absorbing recording medium.

  Examples of the acidic group contained in the amine neutralized resin according to the present invention include a carboxyl group and a sulfo group. As amines used for neutralizing these acidic groups, ammonia, alkanolamines, alkylamines and the like can be used. In particular, neutralization with amines having a boiling point of less than 200 ° C. is preferable from the viewpoint of improving the durability of images. Specific examples of amines include ammonia, triethylamine, 2-dimethylaminoethanol, 2-di-n-butylaminoethanol, methyldiethanolamine, 2-amino-2-methyl-1-propanol, diethanolamine, triethanolamine, 2-methyl. Examples include aminoethanol. In particular, ammonia, 2-amino-2-methyl-1-propanol and 2-dimethylaminoethanol are preferable. As the amine-neutralized resin according to the present invention, either an acid group partially neutralized with an amine or a completely neutralized one can be used.

  The mass ratio of the amine neutralized resin to carbon black (resin / carbon black) is preferably 1.0 or more and 3.0 or less, more preferably 2.0 or more and 3.0 or less. By setting the mass ratio to 1.0 or more, it becomes easy to improve the abrasion resistance of the recorded image, and by setting it to 3.0 or less, it becomes easy to improve the ejection stability when the ink is ejected from the head.

  As the amine neutralized resin, a water-soluble resin having an acidic group neutralized with an amine is preferably used. By using the water-soluble resin for the ink, it is easy to remove the ink attached to the ink jet head, and the head maintenance is easy. It is also preferable to use a water-soluble resin and water-dispersible resin fine particles in combination as the amine neutralizing resin.

  Hereinafter, the water-soluble resin having an acidic group neutralized with an amine and the water-dispersible resin fine particles having an acidic group neutralized with an amine will be described in detail.

(Water-soluble resin)
The water-soluble resin having an acidic group neutralized with an amine according to the present invention is preferably a resin obtained by copolymerizing a hydrophobic monomer and a hydrophilic monomer. Among them, it is preferable to use an acrylic resin because it is easy to control the Tg, acid value, and molecular weight of the resin.

  Monomers that can be used in the acrylic resin include monomers having an acidic group such as acrylic acid, methacrylic acid, and maleic acid, methyl acrylate, methyl methacrylate, butyl acrylate, cyclohexyl acrylate, and 2-hydroxy methacrylate. Examples include (meth) acrylic acid esters such as ethyl, acrylamides such as acrylamide, methacrylamide, N-methylacrylamide, and N-isopropylacrylamide, and monomers having an aromatic ring such as styrene and α-methylstyrene.

  The acid value of the water-soluble resin is preferably 60 mgKOH / g or more and 250 mgKOH / g or less, more preferably 60 mgKOH / g or more and 160 mgKOH / g or less, and 60 mgKOH / g or more and 120 mgKOH / g or less. Is most preferable from the viewpoint of improving the abrasion resistance.

  The weight average molecular weight of the water-soluble resin is preferably 6000 or more and 80000 or less, more preferably 10,000 or more and 50000 or less, and more preferably 20000 or more and 40000 or less.

  The Tg of the water-soluble resin is preferably −30 ° C. or higher and 120 ° C. or lower, and more preferably 20 ° C. or higher and 80 ° C. or lower.

(Water-dispersible resin particles)
As the water-dispersible resin fine particles having an acidic group neutralized with an amine according to the present invention, a dispersion polymerized in an aqueous system may be used as it is or may be treated, or a polymer polymerized in a solvent system may be used. Those dispersed in an aqueous system may be used. Resins applied to water-dispersible resin particles include acrylic, urethane, styrene, vinyl acetate, vinylidene chloride, vinyl chloride, styrene-butadiene, styrene-acrylonitrile, polybutadiene, polyethylene, poly Examples include resins such as isobutylene and polyester.

  As the physical properties of the ink, it is preferable that there is no shear dependency on the viscosity. From this viewpoint, as a dispersion form of the water-dispersible resin fine particles, an emulsifier such as a surfactant is made as low as possible or a soap-free type that does not use an emulsifier The water dispersible resin fine particles are preferred. A preferred water-dispersed resin fine particle is a self-dispersing dispersion of a copolymer obtained by polymerizing unsaturated vinyl having a carboxyl group as at least a monomer component. For example, an acrylic monomer such as ethyl acrylate alone or an acrylic monomer A dispersion obtained by emulsion polymerization or suspension polymerization of acrylic acid or maleic acid as a carboxylic acid monomer in a composition comprising an ethylenically unsaturated monomer that can be copolymerized with an alkaline compound is swelled with an alkaline compound, and then mechanically An acrylic hydrosol obtained by dividing particles by shearing. Among acrylic hydrosols, it is preferable to contain styrene in the monomer composition from the viewpoint of increasing the refractive index of the resin and obtaining a high gloss feeling.

  Specific examples of the acrylic hydrosol include, for example, John Crill series manufactured by Johnson Polymer Co., Ltd.

  The volume average particle diameter of the water-dispersible resin fine particles according to the present invention is preferably 300 nm or less, more preferably 130 nm or less, from the viewpoint that the nozzle of the head is not clogged and a good gloss feeling is obtained. The lower limit of the average particle diameter is preferably 10 nm or more from the viewpoint of production stability of fine particles.

[Glycol ethers, 1,2-alkanediols having 4 or more carbon atoms]
The ink of the present invention is characterized by containing at least one water-soluble organic solvent selected from glycol ethers and 1,2-alkanediols having 4 or more carbon atoms.

  Examples of glycol ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, dipropylene glycol mono Examples include ethyl ether, dipropylene glycol monopropyl ether, and tripropylene glycol monomethyl ether.

  Examples of 1,2-alkanediols having 4 or more carbon atoms include 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, and the like. It is done.

  Among these, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, propylene glycol monopropyl ether, and 1,2-hexanediol are the effects of the present invention and the ink storage stability. It is particularly preferable in terms of achieving compatibility.

  The total content of these solvents is preferably 5.0% by mass or more and 30% by mass or less with respect to the total mass of the ink. By setting it to 5.0% by mass or more, it becomes easy to suppress beading particularly when recording on a non-water-absorbing recording medium, and by setting it to 30% by mass or less, it becomes easy to improve the storage stability of the ink.

[Other water-soluble organic solvents]
In addition to the glycol ethers and 1,2-alkanediols according to the present invention, conventionally known water-soluble organic solvents can be added to the ink of the present invention as long as the object effects of the present invention are not impaired.

  Specifically, for example, alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, etc.), polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, Polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, etc.), amines (eg, ethanolamine, diethanolamine, triethanolamine, N-methyl) Diethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, Ethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.), amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.) It is done.

  In the present invention, when a non-water-absorbing recording medium made of polyvinyl chloride is used as the recording medium, the ink preferably contains a water-soluble organic solvent that is highly swellable or soluble in polyvinyl chloride. As a result, the fixability of the recorded image is improved and the durability of the image is easily improved. Specific examples of water-soluble organic solvents having high swellability or solubility in polyvinyl chloride include water-soluble heterocyclic compounds (for example, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2- Pyrrolidone, γ-butyrolactone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc.), sulfolane, dimethyl sulfoxide and the like.

[Surfactant]
In the ink of the present invention, it is also preferable to use a surfactant in order to impart sufficient wettability to the non-water-absorbing recording medium to the ink. In particular, it is preferable that the ink contains a silicone-based surfactant or a fluorine-based surfactant having a high surface tension reducing ability from the viewpoint of improving the suitability for recording on a non-water-absorbing recording medium.

  In addition, anionic surfactants such as dioctylsulfosuccinate, which have high ability to reduce dynamic surface tension, relatively low molecular weight polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, acetylene glycols, pluronic type surface activity Nonionic surfactants such as agents and sorbitan derivatives can also be used. It is also preferable to use a silicone surfactant or a fluorosurfactant in combination with a surfactant having a high ability to reduce dynamic surface tension.

  The silicone surfactant is preferably a dimethylpolysiloxane whose side chain or terminal is modified with polyether. Specific examples thereof include KF-351A and KF-642 manufactured by Shin-Etsu Chemical, and BYK-347 manufactured by Big Chemie. , BYK-348 and the like.

  The fluorine-based surfactant is one in which a part or all of the fluorine-based surfactant is substituted with a fluorine atom instead of the hydrogen atom bonded to the carbon of the hydrophobic group of the normal surfactant. Among these, a fluorosurfactant having a perfluoroalkyl group or a perfluoroalkenyl group in the molecule is preferable, and specific examples thereof include Megafac F manufactured by DIC, Surflon manufactured by Asahi Glass, Examples include Zonyl manufactured by EI DuPont Nemeras and Company, and Footage series manufactured by Neos.

  Moreover, although a fluorosurfactant has anionic property, nonionicity, amphoteric, etc., all can be used preferably. Examples of anionic fluorosurfactants include Neos's Footgent 100 and 150, and nonionic fluorosurfactants include, for example, DIC's Megafax F470 and Asahi Glass. Surflon S-141, 145, etc. can be mentioned. Examples of amphoteric fluorine-based surfactants include Surflon S-131 and 132 manufactured by Asahi Glass.

[Other ink additives]
In addition to the above-described additives, the ink of the present invention may be used in accordance with 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 known additives such as viscosity modifiers, specific resistance modifiers, film forming agents, UV absorbers, antioxidants, anti-fading agents, antifungal agents, rust preventives, pH adjusters, etc. are appropriately selected. For example, oil droplet fine particles such as liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil, JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476 UV absorbers described in JP-A-57-74192, 57-87989, 60-72785, 61-146591, JP-A-1-95091 and 3- No. 3376, the discoloration inhibitors described in JP-A Nos. 59-42993, 59-52689, 62-280069, 61-242871, and JP-A-4-219266. The fluorescent whitening agent described can be mentioned.

[Ink properties]
The viscosity of the ink of the present invention is not particularly limited, but is preferably 1 mPa · s or more and 15 mPa · s or less at 25 ° C.

  Examples of the apparatus that can be used for measuring the viscosity of the ink of the present invention include a rotary type, a vibration type, and a capillary type viscometer. Examples thereof include Tokimec, cone-plate E type viscometer, and Toki Sangyo E Type. Viscometer (rotary viscometer), B-type viscometer BL manufactured by Tokyo Keiki, FVM-80A manufactured by Yamaichi Denki, Viscoliner manufactured by Nametore Industries, VISCO MATE MODEL VM-1A manufactured by Yamaichi Electric, DD-1 Equipment is commercially available.

  The surface tension of the ink of the present invention is preferably 18 mN / m or more and 35 mN / m or less, more preferably 18 mN / m or more and 28 mN / m or less. By setting the surface tension to 18 mN / m or more, it becomes easy to stabilize the ink ejection state, and by setting it to 35 mN / m or less, the image quality particularly when recorded on a non-water-absorbing recording medium is likely to be good. The surface tension (mN / m) of the ink referred to in the present invention is a value of the surface tension measured at 25 ° C., and the measuring method is described in general interface chemistry and colloid chemistry reference books. For example, New Experimental Chemistry Course Volume 18 (Interface and Colloid), The Chemical Society of Japan, published by Maruzen Co., Ltd. 68-117 can be referred to. Specific examples of the measuring method include a ring method (Dunoi method) and a platinum plate method (Wilhelmy method), but it is preferable to measure by the platinum plate method. As a commercially available apparatus, a surface tension meter CBVP manufactured by Kyowa Interface Science. There is -Z.

〔recoding media〕
Next, the non-water absorbent recording medium according to the present invention will be described.

  The ink of the present invention is suitable not only for printing on a non-absorbent medium such as a vinyl chloride sheet, but also for printing on plain paper, coated paper, inkjet dedicated paper, and the like.

  Examples of the non-water-absorbing recording medium include a polymer sheet, a board (for example, soft vinyl chloride, hard vinyl chloride, acrylic plate, polyolefin, etc.), glass, tile, rubber, and synthetic paper. Examples of the low-absorbency or absorbent recording medium include plain paper (for example, copy paper, plain paper for printing), coated paper, art paper, ink jet exclusive paper, ink jet glossy paper, cardboard, wood and the like.

  In particular, a preferable non-water-absorbing recording medium capable of obtaining a good image and high image fastness is a recording medium having at least polyvinyl chloride on the recording surface side.

  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, Kimoto Co., Ltd.), J-CAL-HGX, J-CAL-YHG, J-CAL-WWWG (above, Kyosho 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, S34 , S27P (above, manufactured by Grafityp), P-223RW, P-224RW, P-249ZW, P-284ZC (above, manufactured by Lintec Corporation), LKG-19, LPA-70, LPE-248, LPM-45, LTG -11, LTG-21 (above, manufactured by Shinsei Co., Ltd.), MPI 3023 (produced by Toyo Corporation), Napoleon Gloss PVC (manufactured by Futaki Electronics Co., Ltd.), JV-610, Y-114 (above, IKEC Corporation) NIJ-CAPVC, NIJ-SPVCGT (Nichie Co., Ltd.), 3101 / H12 / P4, 3104 / H12 / P4, 3104 / H12 / P4S, 9800 / H12 / P4, 3100 / H12 / R2, 3101 / H12 / R2, 3104 / H12 / R2, 1445 / 14 / P3, 1438 / One Way Vision (manufactured by Inetrcoat), JT5129PM, JT5728P, JT5822P, JT5829P, JT5829R, JT5829PM, JT5829RM, JT5929PM (above, manufactured by Mactac), MPI1005, MPI1MP 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, SJT-V400F-1 (hereafter Manufactured by Hiraoka Orizome Co., Ltd.), SPS-98, SPSM-98, SPSH-98, SVGL-137, SVGS-137, MD3-200, MD3-301M, MD5-100, MD5-101M, MD5-105 (and above) (Made by Metamark), 640M, 641G, 641M, 3105M, 3105SG, 3162G, 3164G, 3164M, 3164XG, 3164XM, 3165G, 3165SG, 3165M, 3169M, 3451SG, 3551G, 3551M, 3631, 3641M, 3651G, 3651M, 3651G 3641M (above, manufactured by Orafol), SVTL-HQ130 (made by Lamy Corporation), SP300 GWF, SPCLEARAD vinyl (above, Catalina) ), RM-SJR (manufactured by Ryoyo Shoji Co., Ltd.), Hi Lucky, New Lucky PVC (manufactured by LG), SIY-110, SIY-310, SIY-320 (manufactured by Sekisui Chemical Co., Ltd.), PRINT MI Frontlit, PRINT XL Light weight banner (above, manufactured by Endutex), RIJET 100, RIJET 145, RIJET165 (above, made by Ritrama), NM-SG, NM-SM (manufactured by Nihon Kaiko Co., Ltd.), LTO3GS , Easy Print 80, Performance Print 80 (above, manufactured by Jetgraph Corporation), DSE 550, DSB 550, DSE 800G, DSE 802/137, V250WG, V300WG, V350WG (above, He XS), Digital White 6005PE, 6010PE (and above, manufactured by Multifix), and the like.

[Inkjet recording method]
In the inkjet recording method of the present invention, when an image is recorded on a recording medium using the ink of the present invention, it is preferable to record by heating the recording surface side of the recording medium. By heating the recording medium, the drying property and the thickening speed of the ink are improved, and beading and color bleeding are suppressed, so that a high-quality recorded image is obtained. In addition, the durability of the formed image is also improved. Easy to improve.

  As the heating temperature, it is preferable to heat the recording medium so that the surface temperature on the recording surface side is 40 ° C. or higher and 80 ° C. or lower. By heating to 40 ° C. or higher, the above effects are likely to be sufficient, and by setting the heating temperature to 80 ° C. or lower, ink ejection is good and stable recording can be easily performed over a long period of time.

  As a heating method, select a method in which a heating heater is incorporated in the recording medium conveyance system or the platen member and heated from the lower side of the recording medium in a contact type, or a method of heating in a non-contact manner from the lower side or the upper side of the recording medium by a lamp or the like Can do.

  Furthermore, in the ink jet recording method of the present invention, it is preferable to use a drying means for the purpose of removing unnecessary organic solvents after recording. The ink drying means is not particularly limited. For example, the recording medium is volatilized by a method in which the back surface of the recording medium is dried by contacting with a heating roller or a flat heater, a means for blowing hot air on the print surface with a dryer, or a decompression process. Methods for removing the components and the like can be appropriately selected or combined.

[Inkjet head]
There is no limitation on the inkjet head applicable to the ink of the present invention, and an electro-mechanical conversion method (for example, single cavity type, double cavity type, bender type, piston type, shear mode type, shared wall type, etc.), electric -Thermal conversion method (for example, thermal ink jet type, bubble jet (registered trademark) type, etc.), electrostatic attraction method (for example, electric field control type, slit jet type, etc.) and discharge method (for example, spark jet type, etc.) An ink jet head can be used. From the viewpoint of the cost and productivity of the inkjet head, it is preferable to use an electro-mechanical conversion type or an electro-thermal conversion type head.

  The size of the ink droplets to be ejected is not limited, but is preferably 2 pl or more and 20 pl or less, more preferably 4 pl or more and 15 pl or less from the viewpoint of the balance between image productivity and recording speed.

  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.

<Preparation of inkjet ink>
[Preparation of Pigment Dispersion 1]
Carbon black: # 950 (Mitsubishi Chemical, pH 7.5) 15 parts by mass Polymer dispersing agent: DISPEBYK-2010 (Bicchemy Japan, acid value 20 mgKOH / g) 7.5 parts by mass 2-pyrrolidone 10 parts by mass Ion exchange 67.5 parts by weight of water The above additives were mixed and dispersed using a horizontal bead mill (System Zeta Mini, manufactured by Ashizawa) filled with zirconia beads having a diameter of 0.5 mm by 80% by volume. Thereafter, the zirconia beads were removed, and a pigment dispersion 1 having a solid content concentration of carbon black of 15% by mass was prepared.

[Preparation of Ink 1]
Ink 1 was prepared by mixing the pigment dispersion 1, solvent, surfactant, and amine neutralized resin so that each additive contained in the ink had the following composition, followed by filtration with a 5 μm filter.

Glycol ethers: Diethylene glycol monoethyl ether 10 parts by mass Glycol ethers: Dipropylene glycol monopropyl ether 8 parts by mass Other water-soluble organic solvents: 2-pyrrolidone 5 parts by mass Other water-soluble organic solvents: 1,3-dimethyl-2- Imidazolidinone 10 parts by mass Silicone surfactant: BYK-347 (manufactured by Big Chemie Japan)
0.5 parts by mass Amine-neutralized resin: methacrylic acid-methyl methacrylate-butyl acrylate copolymer (molecular weight 30000, acid value: 70 mg KOH / g, water-soluble resin neutralized with ammonia)
6 parts by mass Polymer dispersant: DISPEBYK-2010 (manufactured by Big Chemie Japan, acid value 20 mgKOH / g) 1.5 parts by mass Carbon black: # 950 (manufactured by Mitsubishi Chemical, pH 7.5) 3 parts by mass with ion-exchanged water, Finished to 100 parts by weight.

  The amount of polymer dispersant (DISPEBYK-2010), carbon black: # 950 (manufactured by Mitsubishi Chemical, pH 7.5) and 2-pyrrolidone includes the amount brought in from the pigment dispersion 1 using 20 parts by mass. .

[Preparation of inks 2-29]
In the same manner as in the preparation of the ink 1, each pigment dispersion was prepared by appropriately selecting the type of carbon black, the type of the polymer dispersant, and the solvent as shown in Tables 1 and 2.

  Next, in the preparation of the ink 1, the same applies except that each solvent, surfactant, amine neutralized resin, polymer dispersant, and pigment dispersion (carbon black type) are changed to the combinations shown in Tables 1 and 2. Thus, inks 2 to 29 were prepared.

  In addition, the detail of each additive described with the abbreviation in Table 1 and Table 2 is as follows. In addition, the addition amount of each additive described in Tables 1 and 2 represents mass%.

<Glycol ethers>
DEGEE: Diethylene glycol monoethyl ether DEGBE: Diethylene glycol monobutyl ether DPGEE: Dipropylene glycol monoethyl ether DPGPE: Dipropylene glycol monopropyl ether <1,2-alkanediols>
HDO: 1,2-hexanediol <other solvents>
MPDO: 2-methyl-1,3-propanediol PG: propylene glycol PDN: 2-pyrrolidone DMI: 1,3-dimethyl-2-imidazolidinone NEP: N-ethyl-2-pyrrolidone <Surfactant>
BYK: BYK-347 (Bic Chemie Japan, silicone surfactant)
Zonyl: Zonyl FSO (manufactured by DuPont, fluorinated surfactant)
E1010: Olfine E1010 (manufactured by Nissin Chemical Industry Co., Ltd., acetylene glycol surfactant)
<Amine neutralized resin>
Resin 1: Methacrylic acid-methyl methacrylate-butyl acrylate copolymer (molecular weight: 30000, acid value: 70 mg KOH / g, water-soluble resin neutralized with ammonia)
Resin 2: Acrylic resin fine particles (molecular weight: 200000, acid value: 20 mg KOH / g, water-dispersible resin fine particles neutralized with ammonia)
<Polymer dispersant>
Dispersant 1: DISPEBYK-190 (manufactured by Big Chemie Japan, a polymer dispersant having a polyethylene oxide group and an acid value of 10 mgKOH / g)
Dispersant 2: DISPEBYK-2010 (manufactured by Big Chemie Japan, polymer dispersant having an acid value of 20 mg KOH / g having a polyethylene oxide group)
Dispersant 3: TG-750W (manufactured by Kyoei Chemical Co., Ltd., a polymer dispersant having a polyethylene oxide group and an acid value of 14 mgKOH / g)
Dispersant 4: Acrylic acid-styrene-ethyl acrylate copolymer (polymer dispersant having an acid value of 48 mgKOH / g)
Dispersant 5: Joncrill PDX-6102B (manufactured by BASF Japan, polymer dispersant having an acid value of 65 mgKOH / g)
Dispersant 6: Jonkrill 60J (manufactured by BASF Japan, polymer dispersant having an acid value of 215 mgKOH / g)
<Carbon black>
CB1: Carbon black pH 6.0 CB2: # 2600 (Mitsubishi Chemical Co., pH 6.5)
CB3: # 950 (Mitsubishi Chemical Corporation, pH 7.5)
CB4: # 850 (Mitsubishi Chemical Corporation, pH 8.0)
CB5: MA100S (Mitsubishi Chemical Corporation, pH 3.5)
CB6: Carbon black with pH 5.8

《Image formation》
A piezo-type inkjet head having a nozzle diameter of 28 μm, a driving frequency of 18 kHz, a nozzle number of 1024, a minimum droplet amount of 12 pl, and a nozzle density of 360 dpi (dpi represents the number of nozzles per 2.54 cm) is mounted, and the maximum recording density is 1440. Each ink was loaded into an on-demand type ink jet printer of 1440 dpi.

  Next, each ink was emitted under the conditions of bidirectional printing with a printing resolution of 1080 dpi × 720 dpi and a head transport speed of 200 mm / sec, and a wedge image with a Duty of 10% increments was mirror coated gold, which is cast coated paper for printing. (Made by Oji Paper Co., Ltd.) and digital vinyl (made by Meta Mark) which is a recording medium made of polyvinyl chloride.

  During recording, an image was formed while heating the recording medium from the back side. The surface temperature of the recording medium during image recording was controlled with a heater so that it was 40 ° C. for mirror coat gold and 50 ° C. for digital vinyl. After recording the image, the recorded matter was dried using a heating fan. The surface temperature of the recording medium was measured using a non-contact thermometer (IT-530N type, manufactured by Horiba, Ltd.).

<Evaluation of recorded images>
Each recorded image was evaluated according to the following method.

(Beading resistance on printed paper)
The image recorded on the mirror coat gold was visually observed for beading of the printed portion and evaluated according to the following criteria. △ or more was allowed.

○: Image mottle is not generated in any density region, and a good image is obtained. Δ: Image mottle is slightly generated in a high density region. X: Mottle is remarkable in any density region. (Beading resistance in polyvinyl chloride)
For the image recorded in digital vinyl, the beading of the printed portion was visually observed and evaluated according to the following criteria. △ or more was allowed.

○: Image mottle is not generated in any density region, and a good image is obtained. Δ: Image mottle is slightly generated in a high density region. X: Mottle is remarkable in any density region. Gloss)
For the image recorded in digital vinyl, the gloss of the printed part was visually observed and evaluated according to the following criteria. △ or more was allowed.

○: A glossy image is obtained in any density region. Δ: Image dullness or white blur occurs in the high density region. ×: Significant white blur or gloss degradation occurs in the medium to high density region. Has occurred (Abrasion resistance)
The image recorded on digital vinyl was rubbed with dry cotton (Kanakin No. 3), and the rub resistance was evaluated according to the following criteria. △ or more was allowed.

◎: No noticeable scratches are observed in the image even after rubbing 30 times. ○: Scratches are confirmed in the image when rubbed 21 to 29 times. Δ: Scratches are confirmed in the image when rubbed 11 to 20 times. X: Remarkable scratches are generated in the image after rubbing 10 times. << Evaluation of ink ejection and storage stability >>
For the inks 1 to 22 in which the evaluations of the recorded images were all acceptable, the ejection properties and the storage stability were evaluated.

(Ejection evaluation)
Each ink was filled in the ink jet recording apparatus, and the wedge images were recorded on digitalvinyl for 2 hours continuously. The recording medium was also heated and dried according to the above conditions. The image at the start of image formation and the image immediately before the end of image formation were visually compared, and the ink ejection properties during continuous use for a long time were evaluated according to the following criteria. △ or more was allowed.

○: The image is almost the same at the start and immediately before the end, and the ink ejectability is good. Δ: The edge of the image just before the end is slightly disturbed, but the ink ejectability is generally good. Noticeable irregularities and white streaks due to missing nozzles appear in the previous image, and ink ejection is poor (head maintenance)
Each ink was filled in the ink jet recording apparatus, and the ink jet head was left for 5 minutes without a cap on the nozzle surface in an environment of 25 ° C. and 30% RH. Thereafter, maintenance work was performed using a wiping blade, the returnability of the nozzles of the inkjet head was confirmed, and head maintenance performance was evaluated according to the following criteria.

○: All nozzles return to normal after maintenance. △: Bends and cutouts remain in 1 to 3 nozzles, but most nozzles return due to maintenance. ×: Bends and cutouts do not recover after 4 nozzles. No nozzle can be restored by one maintenance (ink preservation)
Each ink was put in a glass container, sealed, and stored at 60 ° C. for 1 week. Changes in the viscosity and particle size of each ink before and after storage were measured, and ink storage stability was evaluated according to the following criteria.

<Viscosity stability>
○: Viscosity fluctuation before and after storage is less than 5% and ink storage stability is good Δ: Viscosity fluctuation before and after storage is 5% or more and less than 10%, and ink storage stability is generally good ×: Before and after storage Viscosity fluctuation is 10% or more, and ink storage stability is poor. <Particle size stability>
○: The particle size variation before and after storage is less than 10% and the ink storage property is good. Δ: The particle size variation before and after storage is 10% or more and less than 20%, and the ink storage property is generally good. The particle size variation before and after storage is 20% or more, and the ink storage stability is poor. Table 3 shows the results obtained.

  As is apparent from the results shown in Table 3, the ink of the present invention composed of the composition defined in the present invention is excellent in the ejection property, maintenance performance, and ink storage stability of the ink itself. It can be seen that it has excellent beading resistance, gloss and abrasion resistance.

Claims (10)

a) Carbon black having a pH measured in accordance with JIS K 6221 of 6.0 or more and 8.0 or less, b) a polymer dispersant having an acid value of less than 50 mgKOH / g, c) acid neutralized by amine A water-soluble resin having water groups or water-dispersible resin particles, d) at least one water-soluble organic solvent selected from glycol ethers and 1,2-alkanediols having 4 or more carbon atoms, and e) water. An ink-jet ink for recording on a non-water-absorbing recording medium .   The mass ratio of the water-soluble resin or water-dispersible resin fine particles to the carbon black (water-soluble resin or water-dispersible resin fine particles / carbon black) is 1.0 or more and 3.0 or less. Item 10. The inkjet ink according to Item 1.   The inkjet ink according to claim 1, wherein a mass ratio of the polymer dispersant to the carbon black (polymer dispersant / carbon black) is 0.2 or more and 1.0 or less.   The inkjet ink according to any one of claims 1 to 3, further comprising a silicone-based surfactant or a fluorine-based surfactant.   The glycol ether is at least one selected from diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether and propylene glycol monopropyl ether. The inkjet ink of any one of 1-4.   The inkjet ink according to any one of claims 1 to 4, wherein the 1,2-alkanediol is 1,2-hexanediol.   The total amount of the glycol ethers or 1,2-alkanediols having 4 or more carbon atoms is 5.0% by mass or more and 30% by mass or less, according to any one of claims 1 to 6. The inkjet ink as described.   8. An ink jet recording method comprising recording on a non-water-absorbing recording medium using the ink jet ink according to claim 1.   9. The ink jet recording method according to claim 8, wherein recording is performed by heating the non-water-absorbing recording medium so that the surface temperature is 40 ° C. or more and 80 ° C. or less. 10. The inkjet according to claim 8, further comprising a step of drying the inkjet ink applied to the non-water-absorbing recording medium by a drying unit after the inkjet ink is discharged onto the non-water-absorbing recording medium. Recording method.