JP2012097238A - Method for producing inkjet ink, inkjet ink, and coated pigment dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing inkjet ink which is an inexpensive production method and gives inkjet ink excellent in dispersion stability, ejection stability and shininess.SOLUTION: This production method of inkjet ink is to produce aqueous inkjet ink containing a pigment and water. The method includes a coated pigment formation step of dispersion treating a pigment mixture containing a polymer compound dispersion where a polymer compound particle of ≤500 nm average particle size is dispersed in water, the pigment and water, and preparing a coated pigment dispersion containing coated pigment particles, obtained by coating the pigment with the polymer compound, dispersed therein; and an ink formation step of producing the aqueous inkjet ink using the coated pigment dispersion.

Description

  The present invention relates to a method for producing an ink-jet ink used in an ink-jet recording method, and more particularly to a method for producing a water-based ink-jet ink.

  Encapsulated pigment technology is known for the purpose of improving the storage stability of aqueous pigment inkjet inks and the purpose of improving the durability of images. This technique is a technique in which a water-insoluble resin is mainly used and encapsulated by depositing a water-insoluble resin on the pigment surface.

  In the method called phase inversion method, the resin is dissolved in a solvent such as methyl ethyl ketone, and pigment, water, and an alkali equivalent to the amount of neutralized resin are added and dispersed, and then methyl ethyl ketone is distilled off under reduced pressure to obtain a dispersion. It is the method of obtaining (refer patent document 1, patent document 2, and patent document 3).

  However, this method has a manufacturing problem in the process of distilling off methyl ethyl ketone. The storage stability of the pigment dispersion in the ink varies depending on the distillation conditions of methyl ethyl ketone, and is difficult to control.

  For this reason, since the distillation of methyl ethyl ketone is performed under milder conditions, the production time is increased and the production cost is increased. In addition, a decompression device is necessary and there is a device load. Furthermore, it has been found that the use of methyl ethyl ketone itself greatly deteriorates the dispersion stability of some pigments.

  Furthermore, it is difficult to distill off the entire amount of methyl ethyl ketone from the dispersion, and it remains several percent in the dispersion. The same problem cannot be solved when methyl ethyl ketone is changed to another solvent.

  In the encapsulated pigment technology, there is also known a method of depositing on the pigment surface by controlling the pH after being dispersed with an alkali-soluble resin, but the deposition is difficult to control and the processing is complicated.

  Further, a method is disclosed in which a pigment is dispersed with an activator having a polymerizable group, and then a monomer is supplied to perform polymerization on the surface of the pigment to encapsulate it. However, it is difficult to control polymerization and is not practical.

JP 2004-217916 A JP 2009-84493 A JP 2010-202765 A

  An object of the present invention is to provide an ink-jet ink manufacturing method that provides an ink-jet ink excellent in dispersion stability, injection stability, and glossiness, which is an inexpensive manufacturing method.

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

  1. A method for producing an inkjet ink comprising an aqueous inkjet ink containing a pigment and water, wherein a polymer compound dispersion in which particles of a polymer compound having an average particle size of 500 nm or less are dispersed in water, the pigment, A coated pigment forming step of dispersing a pigment mixture containing water to produce a coated pigment dispersion in which the pigment is coated with the polymer compound, and the coated pigment dispersion A method for producing an ink-jet ink, characterized by comprising an inking step for producing an aqueous ink-jet ink.

  2. 2. The method for producing an ink-jet ink as described in 1 above, wherein the polymer compound particles have an average particle size of 100 nm or less.

  3. 3. The method for producing an inkjet ink according to 1 or 2, wherein the pigment mixture to be dispersed contains 5 mass% or less of a ketone or ester solvent having a boiling point of 100 ° C. or less.

  4). Any one of 1 to 4 above, wherein the polymer compound contains a repeating unit represented by the following general formula 1 in an amount of 30% by mass to 80% by mass with respect to the polymer compound. The manufacturing method of the inkjet ink of description.

General formula 1
_{- (CH 2 -CR 1 (L} 1 -L 2 -Ar)) -
(Wherein R ₁ represents a hydrogen atom or a methyl group, L ₁ represents —COO—, —CONH—, —OCO— or —NHCO—, L ₂ represents a divalent linking group, and Ar represents an aromatic ring. Represents.)
5). 5. The method for producing an ink-jet ink according to any one of 1 to 4, wherein the water-based ink-jet ink contains alkanediol or glycol ether.

  6). 6. The method for producing an inkjet ink according to any one of 1 to 5, wherein the aqueous inkjet ink contains a solvent capable of plasticizing or dissolving vinyl chloride.

  7). The method for producing an ink-jet ink according to any one of 1 to 6, wherein the water-based ink-jet ink contains a resin.

  8). 8. An inkjet ink produced by the inkjet ink production method according to any one of 1 to 7 above.

  9. 9. A coated pigment dispersion used in the method for producing an inkjet ink according to any one of 1 to 8, comprising a pigment, particles of a self-dispersing polymer compound having an average particle diameter of 500 nm or less, and water. A coated pigment dispersion, which is a coated pigment dispersion produced by dispersing a pigment mixture.

  According to the above-mentioned means of the present invention, an inexpensive method for producing an ink-jet ink that gives an ink-jet ink excellent in dispersion stability, injection stability, and glossiness, ink-jet ink produced by the method, and coated pigment used therein A dispersion can be provided.

  The present invention relates to a method for producing an inkjet ink for producing an aqueous inkjet ink containing a pigment and water, wherein the polymer compound dispersion in which particles of a polymer compound having an average particle size of 500 nm or less are dispersed in water; A coated pigment forming step of producing a coated pigment dispersion in which the pigment mixture containing the pigment and water is dispersed to produce coated pigment dispersion in which the pigment is coated and coated with the polymer compound; and It is characterized by having an inking step for producing a water-based inkjet ink using a coated pigment dispersion.

  In particular, the present invention is an inexpensive production method for producing a pigment coated with a polymer compound by using particles of the polymer compound dispersed in water, and the coated pigment dispersion produced by this method is used. Thus, it is possible to provide an ink-jet ink manufacturing method that provides an ink-jet ink excellent in dispersion stability, injection stability, and glossiness by producing the ink.

(Inkjet ink)
(Polymer compound dispersion)
The polymer compound dispersion according to the present invention is a dispersion in which particles of a polymer compound having an average particle diameter of 500 nm or less are dispersed in water.

  In the present invention, the average particle diameter can be easily measured using a commercially available measuring apparatus using a light scattering method. Specifically, the value measured using Zetasizer 1000 (made by Malvern) is said.

  In the present invention, the average particle diameter needs to be 500 nm or less from the viewpoint of the storage stability of the inkjet ink, the injection stability, the glossiness after printing, and the dispersion stability of the coating pigment dispersion described later. More preferably, it is more preferably 5 nm or more and 50 nm or less.

  As the polymer compound according to the present invention, those that produce self-dispersing particles when the polymer compound is used as particles are preferably used.

  Self-dispersing particles are particles that can be stably dispersed in water without using an activator or other dispersant.

  That is, self-dispersing polymer compound particles are preferably used as the polymer compound particles of the present invention. The polymer compound particles of the present invention preferably contain substantially no activator or other dispersant.

  As the self-dispersing polymer compound particles, urethane polymer compound particles, polyester polymer compound particles, acrylic polymer compound particles, and the like can be used. Among these, acrylic polymer compound particles can be preferably used from the viewpoint of dispersion stability.

  The self-dispersing polymer compound is composed of, as a polymer compound, a hydrophobic constituent unit such as a styrene monomer or an acrylate monomer and a hydrophilic constituent unit such as an acrylic monomer having a carboxy group or a hydroxyl group. It can be obtained by using a polymer compound.

  Self-dispersing polymer particles can be obtained by dispersing a polymer polymerized by an emulsion polymerization method, a solution polymerization method or the like.

  For example, as a preferred specific example, an acrylic copolymer having an appropriate acid value necessary for self-dispersion is synthesized by solution polymerization, and after adding an alkali around the neutralization amount of the acidic group of the resin, the dispersion is dispersed. Self-dispersing polymer particles can be produced.

  Examples of the monomer used in the polymer compound of the self-dispersing polymer compound particle include the following, and a copolymer of these monomers is used as the polymer compound.

  For example, styrene derivatives such as styrene and methylstyrene, acrylic acid esters (examples of ester parts include methyl, ethyl, propyl, n-butyl, n-hexyl, cyclohexyl, n-octyl, 2-ethylhexyl, etc.), methacrylic acid Esters (examples of ester moieties include methyl, ethyl, propyl, n-butyl, n-hexyl, cyclohexyl, n-octyl, 2-ethylhexyl, etc.), acidic groups and anhydride monomers thereof include acrylic acid, methacrylic acid , Itaconic acid, maleic acid, maleic anhydride and acrylamide.

  In the present invention, it is particularly preferable in terms of ink stability to use an acrylic acid ester or a methacrylic acid ester of the following general formula 1.

  More preferably, it is particularly preferable that the monomer of the general formula 1 is contained in the polymer compound in a total amount of 30% by mass to 80% by mass.

General formula 1
_{- (CH 2 -CR 1 (L} 1 -L 2 -Ar)) -
In the formula, R ₁ represents a hydrogen atom or a methyl group, L ₁ represents —COO—, —CONH—, —OCO—, —NHCO—, L ₂ represents a divalent linking group, and Ar represents an aromatic ring. To express.

Specific examples of the divalent linking group represented by L ₂ include an alkylene group (1-10 carbon atoms), an alkenylene group, (1-10 carbon atoms), —CO—, —NR ₂ — (R ₂ is hydrogen). alkyl group atoms or carbon atoms 1~6), - O -, - S -, - SO -, - SO 2 - linking group selected from the preferred. Two or more of the divalent linking groups may be combined. Particularly preferred linking groups are methylene, ethylene, propylene, oxyethylene, oxyethoxyethylene groups.

  As the aromatic ring represented by Ar, a monovalent group derived from a phenyl group, a condensed ring type aromatic ring compound, a heterocyclic compound in which an aromatic ring is condensed, or a compound in which two or more benzenes are linked is preferably used. It is done.

  As specific examples, monovalent groups derived from benzene, naphthalene, biphenyl, triphenylmethane, phthalimide, acridone, fluorene, anthracene, phenanthrene, diphenylmethane, or carbazole are preferable. Ar may have a substituent.

  Examples of the substituent include an alkyl group, an alkoxyl group, an alkylcarbonyl group, an alkylcarbonyloxy group, an alkyloxycarbonyloxy group, a halogen group, and a cyano group.

  The appropriate acid value required for self-dispersion can be adjusted by the amount of acidic groups and anhydride monomers used for copolymerization. The acid value can be selected from the range of 40 or more and less than 120, and is preferably in the range of 65 to 90.

  The weight average molecular weight of the polymer is preferably adjusted in the range of 10,000 to 150,000, more preferably 20,000 or more and 100,000 or less, from the viewpoints of image durability, injection positiveness, and glossiness.

  The glass transition temperature (Tg) of the polymer compound is preferably adjusted in the range of 0 ° C. to 120 ° C. in terms of ink storage stability, gloss, and injection stability. It is particularly preferable to adjust to a range of 50 ° C to 100 ° C.

  The following method is preferred as a method for obtaining the polymer compound dispersion.

  The polymer compound, a mixture of alkalis before and after the neutralization amount of the acidic group of the polymer compound, and ion-exchanged water can be dispersed by various dispersion methods. At this time, an auxiliary solvent is added as necessary.

  As the alkali, an alkali metal hydroxide, ammonia, or other organic amine (dimethylaminoethanol or the like) can be used.

  As the auxiliary solvent, it is preferable to use a solvent capable of dissolving the resin before neutralization at a concentration of 10% by mass or more. For example, acetone, methyl ethyl ketone, ethyl acetate, glycol ethers (diethylene glycol methyl, diethylene glycol butyl, dipropylene glycol methyl, dipropylene glycol propyl, etc.), amide solvents (dimethylformamide, dimethylacetamide), 2-PDN, N-methyl Such as pyrrolidone. In addition, alcohols (methanol, ethanol, i-propyl alcohol) can be used. The auxiliary solvent can be distilled, if necessary, after the dispersion, by heating under normal pressure or reduced pressure, to completely or partially distill off the auxiliary solvent. The auxiliary solvent is preferably used in the range of 2 to 10 times the amount of the polymer compound.

  As a dispersing method, it can be dispersed using a ball mill, a colloid mill, a vibrating ball mill, a sand mill, a jet mill, a roller mill, an ultrasonic wave, or the like.

  As a preferred specific method for obtaining the polymer compound dispersion, the amount of the auxiliary solvent in which the polymer compound is dissolved in as little auxiliary solvent as possible is preferably 3 to 6 times that of the polymer compound. Separately, a mixture of ion-exchanged water and a neutralized amount of polymer compound is prepared, and the above-mentioned polymer compound auxiliary solvent solution is added little by little with stirring. At this time, the ratio of the polymer compound / cosolvent / ion exchange water is preferably in the range of 1/3 to 6 / 3-10. This mixture is dispersed by the dispersion method. The dispersion is preferably terminated when the average particle diameter is measured at regular intervals and the average particle diameter becomes substantially constant. During dispersion, heat is generated, so cool it with ice water. If necessary, the obtained dispersion is heated under normal pressure or reduced pressure to distill off all or part of the auxiliary solvent. The present invention is characterized by a simple method without a solvent distillation step after pigment dispersion. Therefore, when a solvent having a boiling point of 100 ° C. or less is used as an auxiliary solvent, the auxiliary solvent used is subjected to atmospheric pressure or reduced pressure. It is preferable to distill off all or a part by heating.

  The synthesized polymer compound is dispersed after adding an alkali around the neutralization amount of the acidic group of the resin. As the main dispersion medium, ion-exchanged water is preferable, and an auxiliary solvent is added as necessary. As the auxiliary solvent, it is preferable to use a solvent capable of dissolving the resin before neutralization at a concentration of 10% by mass or more. For example, acetone, methyl ethyl ketone, ethyl acetate, glycol ethers (diethylene glycol methyl, diethylene glycol butyl, dipropylene glycol methyl, dipropylene glycol propyl, etc.), amide solvents (dimethylformamide, dimethylacetamide), 2-PDN, N-methyl Such as pyrrolidone. In addition, alcohols (methanol, ethanol, i-propyl alcohol) can be used. The auxiliary solvent can be distilled, if necessary, after the dispersion, by heating under normal pressure or reduced pressure, to completely or partially distill off the auxiliary solvent.

  As the alkali to be used, an alkali metal hydroxide, ammonia, or other organic amine (such as dimethylaminoethanol) can be used.

  As a dispersion method, it can be dispersed by ultrasonic dispersion, a screw mixer, a bead mill or the like.

(Pigment)
As the pigment that can be used in the present invention, conventionally known organic and inorganic pigments can be used. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc. Examples include cyclic pigments, dye lakes such as basic dye lakes, and acid dye lakes, organic pigments such as nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments, and inorganic pigments such as carbon black.

  Specific organic pigments are exemplified below.

  Examples of pigments for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the orange or yellow pigment include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 128, C.I. I. Pigment Yellow 138, Pigment Yellow 150, Pigment Yellow 155, and the like.

  Examples of pigments for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  Examples of white organic pigments include organic compound salts disclosed in JP-A No. 11-129613 and alkylene bismelamine derivatives disclosed in JP-A Nos. 11-140365 and 2001-234093. Specific examples of white organic pigments include Shigenox OWP, Shigenox OWPL, Shigenox FWP, Shigenox FWG, Shigenox UL, and Shigenox U (all of these are trade names manufactured by Hackol Chemical).

  Organic pigments having various surface treatments can be used. Those having a surface oxidized such as crystal shape, acid treatment, basic treatment, and self-dispersing pigment can also be used.

  As inorganic pigments, pigments made of metal oxides and the following white pigments can be mainly used.

  The white pigment is not particularly limited as long as it makes the ink composition white, and usually white pigments used in this field can be used. As such a white pigment, for example, a white inorganic pigment, a white organic pigment, or white hollow polymer fine particles can be used. Examples of white inorganic pigments include alkaline earth metal sulfates such as barium sulfate, alkaline earth metal carbonates such as calcium carbonate, silicas such as finely divided silicic acid, and synthetic silicates, calcium silicate, alumina, alumina Hydrates, titanium oxide, zinc oxide, talc, clay and the like can be mentioned. In particular, titanium oxide is known as a white pigment having favorable concealability, colorability, and dispersed particle size.

  Examples of the white hollow polymer fine particles include fine particles showing thermoplasticity substantially made of an organic polymer disclosed in US Pat. No. 4,089,800.

(Coating pigment formation process)
A method for producing an ink-jet ink for producing an aqueous ink-jet ink containing a pigment and water according to the present invention, comprising: a polymer compound dispersion in which particles of a polymer compound having an average particle diameter of 500 nm or less are dispersed in water; The coated pigment forming step for producing a coated pigment dispersion in which the pigment mixture containing the pigment and water is dispersed to disperse and contain coated pigment particles coated with the polymer compound will be described. .

(Pigment mixture)
The pigment mixture can be obtained by mixing the pigment, the polymer compound dispersion, and water.

  About the coating pigment formation process which concerns on this invention, it estimates as follows.

  In general, it is estimated that the pigment dispersion step includes three steps of wetting, crushing, and dispersion stabilization. Crushing of the pigment dispersion process is a central process of dispersion, and by applying energy to the mixture containing the pigment, particle collision and shear are given and crushed. At this time, the dispersant in the mixture Is adsorbed on the surface of the crushed pigment, and it is considered that the dispersion is stabilized.

  In the step of applying the dispersion treatment according to the present invention, by applying energy to the mixture containing the pigment, the polymer compound particles having an average particle size of 500 nm or less are further subdivided into finer particles as the pigment is crushed. I believe that. In addition, the polymer compound is deposited on the pigment surface by colliding and coalescing the finely divided polymer compound particles with the pulverized pigment particles. It is believed that the coated pigment particles are formed.

  Assuming such a mechanism, it is considered that the smaller the particle system, the higher the polymer particles deposited by colliding and coalescing with the crushed pigment surface. This is because the smaller the polymer particle size, the greater the stability of the polymer when combined with the pigment, and the more uniform the amount of polymer deposited. Considering that the particle diameter of the pigment after pulverization is usually about 50 nm to 200 nm, it is considered that the polymer particle deposited on the pigment surface is preferably about 10 nm to 100 nm. In order to form such a polymer dispersion with small particles in the pigment dispersion process of the present invention, it is presumed that the average particle diameter of the polymer compound before dispersion needs to be 500 nm or less. Furthermore, the average particle diameter is preferably 100 nm or less, and more preferably 5 nm or more and 50 nm or less, which is presumed to be because the above-mentioned subdivision is easier and uniform coating.

  The coated pigment dispersion can be obtained by dispersing the pigment mixture. That is, pigment particles coated with a polymer compound can be prepared by applying dispersion energy to the pigment mixture.

  The dispersion treatment is preferably carried out by carrying out the dispersion treatment with the solid content concentration of the pigment in the pigment mixture in the range of about 5% by mass to 25% by mass. From the viewpoint of dispersion time, dispersion cost, etc., 10% by mass. To 20% by mass is particularly preferable.

  The polymer compound dispersion used in the pigment mixture may be used in combination of a plurality of types.

  The addition amount of the polymer compound dispersion to the pigment mixture is preferably selected in the range of 0.2 to 1.5 times based on the solid content concentration of the pigment. Among these, it is particularly preferable to select from a range of 0.3 times to 1 time in terms of ink storage stability and ejection stability.

  Examples of the dispersion method used for the dispersion treatment include various dispersion means such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, and a paint shaker.

  Among these, a wet disperser (bead mill) can be preferably used. At this time, beads having a particle diameter of 0.1 mm to 5 mm can be used. Among these, 0.1 mm to 1 mm is preferable. The beads are preferably made of zirconia, and particularly preferably the yttrium-stabilized type. The bead filling ratio is preferably 50% or more and 85% or less, and more preferably 75 to 85%. Since the temperature of the dispersion is increased by the dispersion energy, it is preferable to use the dispersion after cooling the disperser. The dispersion temperature is preferably controlled to 3 ° C to 30 ° C, more preferably 5 ° C to 20 ° C.

  In the present invention, the pigment coated with the polymer compound can be confirmed by observing a cross-sectional photograph with an electron microscope. The pigment surface may be partially coated with a polymer compound, but a state where the entire surface is coated is a preferred embodiment.

  The main medium of the pigment dispersion is water, but an organic solvent, an activator, a pH adjuster, an antifungal agent and the like may be added as necessary.

  As an organic solvent, what was raised to the auxiliary solvent at the time of the said high molecular compound dispersion manufacture can be used. The use of an organic solvent that must be distilled off after the pigment dispersion step is preferably as small as possible. In particular, the addition amount of a ketone-based or istel-based organic solvent having a boiling point of 100 ° C. or less, such as methyl ethyl ketone, is preferably 5% or less, preferably 3% or less, more preferably 1% or less.

  The pH of the coated pigment dispersion after the dispersion treatment can be adjusted with a pH adjuster or the like. A preferred pH adjustment range is in the range of 6.5 to 9.5.

  Further, after the dispersion treatment, it is preferable to remove coarse particles, dust and the like by using a centrifugal separator and a filtration filter alone or in combination.

  The obtained coated pigment dispersion is subjected to an aging process as necessary, and is converted into an ink by an ink-making process in which the following red-down liquid containing components necessary for inkjet ink is added and adjusted to the coated pigment dispersion. The

  The aging step is a step of improving the stabilization of the pigment dispersion, and can be stored in an environment of 15 to 60 ° C. for 1 to 30 days. After the aging step, it is preferable to remove coarse particles again by using a centrifugal separator and a filtration filter alone or in combination.

(Inking process)
In the ink forming process, various organic solvents, activators, resins, pH adjusters, fungicides, and the like can be added to the red down liquid used.

(Organic solvent)
It is preferable to add a low surface tension solvent to the inkjet ink of the present invention. By adding a low surface tension solvent, it is possible to further suppress ink mixing even on various resin substrates such as vinyl chloride sheets and paper supports with slow ink absorption speed such as printing paper. Print image can be obtained. The low surface tension solvent has an effect of improving the wettability of the ink with respect to vinyl chloride or the like.

  In the present invention, it is preferable to add glycol ether or alkanediol as the low surface tension solvent.

  An example of a low surface tension solvent suitable for the ink of the present invention is shown below. In addition, the numerical value in a parenthesis represents the surface tension (mN / m) of a solvent.

  Examples of the glycol ether include ethylene glycol monoethyl ether (28.2), ethylene glycol monobutyl ether (27.4), diethylene glycol monoethyl ether (31.8), diethylene glycol monobutyl ether (33.6), and triethylene glycol. Examples thereof include monobutyl ether (32.1), propylene glycol monopropyl ether (25.9), dipropylene glycol monomethyl ether (28.8), tripropylene glycol monomethyl ether (30.0) and the like.

  As the alkanediol, 1,2-alkanediol or 1,3-alkanediol is preferable. For example, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol (28.1), 1,2-heptanediol, 2-methyl-1,3-propanediol and the like can be mentioned.

  Further, by adding a solvent having an action capable of dissolving, softening or swelling a recording medium such as vinyl chloride, the adhesion between vinyl chloride and the ink solid content is further improved, and excellent image adhesion and resistance. It is preferable from the viewpoint of obtaining rubbing properties.

  Examples of such solvents include cyclic solvents containing nitrogen or sulfur atoms, cyclic ester solvents, lactic acid esters, alkylene glycol diethers, alkylene glycol monoether monoesters, and dimethyl sulfoxide.

  The cyclic solvent containing a nitrogen atom is preferably a cyclic amide compound, particularly a 5- to 7-membered ring, such as 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone 1,3-dimethyl. Examples include imidazolidinone, 1,3-dimethyl-2-imidozolidinone, ε-caprolactam, methylcaprolactam, and 2-azacyclooctanone. As the cyclic solvent containing a nitrogen atom other than the cyclic amide, formylmorpholine, and as the cyclic solvent containing a sulfur atom, a cyclic amide compound is preferable, and a 5- to 7-membered ring is preferable, and examples thereof include sulfolane. Examples of the cyclic ester solvent include γ-butyrolactone and ε-caprolactone, and examples of the lactic acid ester include butyl lactate and ethyl lactate. Examples of the alkylene glycol diether include diethylene glycol diethyl ether. Examples of the alkylene glycol monoether monoester include diethylene glycol monoethyl monoacetate.

  In the present invention, from the viewpoint of ink ejection stability from the ink jet head, maintainability, and gloss of the formed image, as one of the solvents, a water-soluble alkanolamine is 0.30% by mass or more of the total mass of the ink, It is preferable to contain 2.0 mass% or less, More preferably, it is 0.3 mass% or more and 1.8 mass% or less.

  Examples of water-soluble alkanolamines that can be preferably applied to the present invention include N, N-dimethylaminoethanol, 2-amino-2-methylpropanol, and N-methylaminoethanol.

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

  In the present invention, the amount of the organic solvent used is preferably 10% by mass or more and 50% by mass or less of the total mass of the ink-jet ink.

(resin)
As the resin that can be used in the present invention, both those dissolved in ink and those dispersed in ink can be used.

  As an example of what is dissolved in the ink, a water-soluble resin can be used. The water-soluble resin is one in which 10% by mass or more is dissolved in water, and various water-soluble resin compositions can be used.

  In addition to general water-soluble acrylic resins, water-soluble polyester resins, water-soluble polyurethane resins, water-soluble polyamide resins, water-soluble polyether resins, water-soluble polyvinyl alcohol, and water-soluble polyvinyl pyrrolidone can be used.

  The water-soluble resin can have an anionic group such as a carboxylic acid group or a sulfonic acid group as a partial structure in the resin so as to be water-soluble. Moreover, nonionic groups, such as a polyoxyalkylene group, can also be included as a partial structure in the water-soluble resin.

  The weight average molecular weight of the water-soluble resin is preferably selected from a range of 1000 or more and 100,000 or less. More preferably, it is 5000 or more and 70,000 or less. The glass transition temperature of the water-soluble resin can be from room temperature or lower to 150 ° C. or lower. Preferably, the thing of 0 to 100 degreeC can be used.

  Said water-soluble resin may be used independently and may use multiple types together.

  Particularly preferred as the water-soluble resin is a water-soluble acrylic resin.

  As the water-soluble acrylic resin, the following can be particularly preferably used. As is well known, vinyl copolymer resins such as acrylic resins can be freely designed from a large number of monomers, have the advantage that they are easily polymerized and can be produced at low cost. In particular, as described above, an acrylic resin having a high degree of design freedom is suitable for answering a large number of requirements required when added to ink.

  As a mechanism for dissolving the water-soluble acrylic resin in the ink, according to the study by the present inventors, the water-soluble portion accompanying the separation of the acidic group of the resin, the nonionic hydrophilic structure portion in the resin, and the ink in the ink Promotion of solubilization of organic solvents is the main one. Among these, the role of the water-soluble part accompanying the dissociation of the acidic group of the resin is particularly significant, that is, the acid value affects the ink solubility of the resin.

  The acid value of the resin is preferably 50 mgKOH / g or more and 120 mgKOH / g or less from the viewpoint of coating strength and maintainability.

  The adjustment of the acid value can be performed by adjusting the introduction amount of the acidic component.

  The weight average molecular weight of the water-soluble acrylic resin is preferably 20000 or more and 100,000 or less from the viewpoint of coating strength and injection stability.

  Among them, an acrylic acid alkyl ester having 2 to 8 carbon atoms in the alkyl group or a methacrylic acid alkyl ester having 2 to 8 carbon atoms in the alkyl group, and an alkyl alkyl ester or alkyl having 2 to 8 carbon atoms in the alkyl group are included. A water-soluble acrylic resin in which the total amount of methacrylic acid alkyl ester having 2 to 8 carbon atoms in the group is 10% by mass or more and 80% by mass or less in the water-soluble acrylic resin composition is preferable.

  In the study by the present inventors, the alkyl group includes an alkyl acrylate ester having 2 to 8 carbon atoms or an alkyl group alkyl methacrylate having 2 to 8 carbon atoms, and the alkyl group having 2 to 8 carbon atoms. When the total amount of acrylic acid alkyl ester or alkyl methacrylate having 2 to 8 carbon atoms in the alkyl group is 10% by mass or more and less than 80% by mass, image durability is particularly high for non-absorbing substrates such as vinyl chloride. It is particularly effective for obtaining sex.

  Examples of the alkyl acrylate ester having 2 to 8 carbon atoms in the alkyl group include ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, and n-hexyl acrylate. , Cyclo-hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, and the like.

  Examples of the alkyl methacrylate having 2 to 8 carbon atoms in the alkyl group include ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, and n-hexyl methacrylate. , Cyclo-hexyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate and the like.

  These are more stable in injection and particularly excellent in maintainability than acrylic acid alkyl esters having 9 or more carbon atoms in the alkyl group or methacrylic acid alkyl esters having 9 or more carbon atoms in the alkyl group.

  For the water-soluble acrylic resin, a monomer obtained by neutralizing all or part of the acidic group with an alkali can be used in order to stably dissolve in the ink. As the neutralizing base, alkali metal-containing bases such as sodium hydroxide and potassium hydroxide, and amines (for example, ammonia, alkanolamine, alkylamine 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 image durability. In particular, an acid monomer neutralized with ammonia has a fast drying property after printing, It is also preferable from the standpoint that printed matter can be stacked immediately after printing and ink mixing can be prevented. In addition, it is preferable in terms of injection stability to use N, N-dimethylaminoethanol, 2-amino-2-methylpropanol, or N-methylaminoethanol as a counter salt.

  In addition, the following can also be used with commercially available resin. For example, JONCRYL 67, 678, 586, 611, 680, 682, 683, 690, 819, JDX-C3000, JDX-C3080, 52J, 57J, 60J, PDX6650, 61J, 62J, 63J, 70J, manufactured by BASF HPD-96J, PDX-6137A, 501J, 354J, 6610, JDX-6500, PDX-6102B, PDX6124, JDX-6108, and the like.

  Next, the ink dispersible resin will be described.

  As the ink dispersible resin, a hydrophobic resin dispersed in the ink using a surfactant, or a so-called soap-free type capable of being dispersed in a portion derived from an acidic monomer can be used. The resin may be polymerized in a solution system or the like dispersed in ink, or may be polymerized by so-called emulsion polymerization.

  As the ink dispersible resin, a vinyl resin such as an acrylic resin is preferable, but a polyester resin, a polyamide resin, a polyether resin, a polyolefin resin, or a composite resin thereof can be used.

  As the particle diameter of the ink dispersion resin, those having an average particle diameter of about 20 nm to about 300 nm can be used. In view of the effect of the present invention, it is preferable to use a recording agent pigment having an average particle diameter of about 1/2 to 2 times.

  As the glass transition temperature of the ink dispersion resin, those having a temperature of 30 ° C. or more and less than 100 ° C. can be used.

  The acid value of the ink dispersion resin is preferably less than 60 gKOH / g.

  It is preferable to use a partially crosslinked ink dispersion resin in the structure. Among them, it is a vinyl resin such as an acrylic resin, and includes an alkyl acrylate alkyl ester having 2 to 8 carbon atoms or a methacrylic acid alkyl ester having 2 to 8 carbon atoms and an alkyl group having 2 carbon atoms. It is particularly preferable that the total amount of -8 alkyl acrylates or alkyl alkyl methacrylates having 2 to 8 carbon atoms is 40% by mass or more and less than 90% by mass in the water-soluble acrylic resin composition. When these ink-dispersible resins are used in combination with the water-soluble acrylic resin contained in the ink of the present invention, a highly durable image film can be formed without any special high-temperature treatment, high gloss and high optical density. Is preferable. Specific examples of the alkyl ester having 2-8 carbon atoms in the alkyl group or the alkyl ester having 2-8 carbon atoms in the alkyl group may be those described in the description of the water-soluble acrylic resin. .

  In addition, the following can also be used with commercially available resin. For example, as JONCRYL series manufactured by BASF, JONCRYL 7100, 390, 711, PDX-7157, PDX-7182, PDX-7163, 7001, 1532, 741, 450, 840, 8380, 8300, 74J, 8383, 142, 1919, 734, 540, PDX7677, 7600, 775, 1915, 537J, PDX-7692, 7611, PDX-7630A, 352J, 538J, 8311, 7640, 631, 790, 780, and the like.

  The addition of the resin as described above is preferable because the image durability can be improved for various media.

  However, the addition of a resin increases the ink viscosity and makes it difficult to eject, or increases the viscosity during storage of the ink, and has a side that is difficult to use.

  The addition of a water-soluble resin is preferable because it can control the viscosity increase after ink landing, and can prevent the liquid from being dripped particularly when printing on a non-absorbent medium.

  However, when a water-soluble resin is added to the ink, the ink storage stability may deteriorate, and the amount used has been limited.

  Since the storage stability is greatly improved when the pigment dispersion of the present invention is used, the use of the resin can maintain the ink storage stability in a good state while taking advantage of the ink performance described above. Particularly preferred.

(Other additives)
In the inkjet ink of the present invention, it is preferable to add a silicone-based or fluorine-based surfactant as the surfactant.

  Addition of silicone-based or fluorine-based surfactants further suppresses ink mixing even on vinyl resin sheets and other resin substrates and paper supports with slow ink absorption speeds such as printing paper. And a high-quality printed image can be obtained. Further, it is particularly preferable to use in combination with a low surface tension solvent.

  The silicone surfactant is preferably a polyether-modified polysiloxane compound, and examples thereof include KF-351A and KF-642 manufactured by Shin-Etsu Chemical Co., and BYK345, BYK347, and BYK348 manufactured by Big Chemie.

  The fluorosurfactant means a compound in which a part or all of the fluorosurfactant is substituted with fluorine in place of hydrogen bonded to carbon of a hydrophobic group of a normal surfactant. Among these, those having a perfluoroalkyl group in the molecule are preferable.

  Among the fluorosurfactants, certain types are traded under the trade name Megafac F from DIC, and Surflon from Asahi Glass, Minnesota Mining and Manufacturing Company Under the trade name Fluorad FC from the company, under the trade name Monflor from Imperial Chemical Industry, and under the trade name Zonyls from EI Dupont Nemeras & Company, They are also commercially available from Farbeberke Hoechst under the trade name Licobet VPF.

  Examples of the nonionic fluorosurfactant include Megafax 144D manufactured by DIC, Surflon S-141 manufactured by Asahi Glass Co., Ltd., and 145, and the amphoteric fluorosurfactant. Can include, for example, Surflon S-131 and 132 manufactured by Asahi Glass Co., Ltd.

  The following surfactants can be used in combination with the silicone-based or fluorine-based surfactant.

  For example, anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene blocks Nonionic surfactants such as copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. In particular, an anionic surfactant and a nonionic surfactant can be preferably used.

  In addition to the above-described explanation, the inkjet ink of the present invention, if necessary, according to the purpose of improving the emission stability, print head and ink cartridge compatibility, storage stability, image storage stability, and other various performances, Various known additives such as polysaccharides, viscosity modifiers, specific resistance modifiers, film forming agents, ultraviolet absorbers, antioxidants, anti-fading agents, anti-fouling agents, rust preventives and the like are appropriately selected and used. For example, oil droplet fine particles such as liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil, and ultraviolet absorbers described in JP-A Nos. 57-74193, 57-87988 and 62-261476 JP-A-57-74192, JP-A-57-87989, JP-A-60-72785, JP-A-61-146591, JP-A-1-95091 and JP-A-3-95091. No. 3376, etc., and JP-A Nos. 59-42993, 59-52689, 62-280069, 61-242871, and JP-A-4-219266. Examples thereof include a fluorescent brightening agent.

  The method for measuring the acid value, Tg, and molecular weight in the above description will be described below.

<Measurement of acid value>
The resin was dried, 10 g of the dried and solidified resin was weighed into a 300 ml Erlenmeyer flask, and then about 50 ml of a mixed solvent of ethanol: benzene = 1: 2 (volume ratio) was added to dissolve the ink dispersible resin 1. Next, using a phenolphthalein indicator, titration with a 0.1 mol / L potassium hydroxide ethanol solution that has been standardized in advance, and from the amount of the potassium hydroxide ethanol solution used for the titration, the resin according to the following calculation formula (1) The acid value (mgKOH / g) of is determined.

Formula (1)
A = (B × f × 5.611) / S
In the formula, A is the acid value of the resin (mgKOH / g), B is the amount of 0.1 mol / L potassium hydroxide ethanol solution used for titration (ml), and f is the 0.1 mol / liter potassium hydroxide ethanol solution. The factor, S, is the mass (g) of the ink dispersible resin 1, and 5.611 is the formula amount (56.11 / 10) of potassium hydroxide. Some resins do not dissolve in about 50 ml of the above mixed solvent of ethanol: benzene = 1: 2, and either 50 ml of ethanol or about 50 ml of mixed solvent of ethanol: pure water = 1: 1 is appropriately dissolved. Measure the oxidation in the same way with the others.

<Measurement of glass transition temperature (Tg)>
Using a DSC-7 differential scanning calorimeter (Perkin Elmer) and a TAC7 / DX thermal analyzer controller (Perkin Elmer), Tg is measured according to the following method.

  As a measurement procedure, 10.00 mg of resin is precisely weighed to 2 digits after the decimal point, sealed in an aluminum pan (KITNO.0219-0041), and set in a DSC-7 sample holder. The reference uses an empty aluminum pan.

  The measurement conditions are 0-130 ° C, temperature increase rate 10 ° C / min, temperature decrease rate 10 ° C / min. Heat-cool-heat control is performed, and analysis is performed based on the data in 2nd Heat. went. The measurement was performed under a nitrogen stream condition.

  The glass transition temperature is obtained by drawing an extension of the baseline before the rise of the first endothermic peak and a tangent line indicating the maximum slope between the rising portion of the first peak and the peak apex, and the intersection is defined as the glass transition temperature. To do.

<Measurement of weight average molecular weight>
The weight average molecular weight of the ink dispersible resin 1 is measured using gel permeation chromatography.

  The measurement conditions are as follows.

Solvent: Tetrahydrofuran Column: Tosoh TSKgel G4000 + 2500 + 2000HXL
Column temperature: 40 ° C
Injection volume: 100 μl
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 100000 to 500 samples are used. Thirteen samples are used at approximately equal intervals.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these.

(Synthesis of polymer compound 1)
A four-head flask was provided with a nitrogen inlet tube, a condenser, a thermometer, and a dropping funnel. To the flask was added 230 g of methyl ethyl ketone, nitrogen gas was introduced, and the mixture was heated to reflux with stirring for 30 minutes. Meanwhile, 62.5 g of benzyl methacrylate, 48.8 g of methyl methacrylate, 13.8 g of methacrylic acid, and 0.63 g of AIBN were stirred and mixed at room temperature to dissolve. This monomer / initiator mixture was dropped from the dropping funnel over 2 hours. During the dropwise addition, heating under reflux was maintained. After completion of the dropwise addition, the mixture was further heated to reflux for 5 hours. The reaction solution was allowed to cool and then poured little by little into 2 kg of stirring hexane. The candy-like polymer gradually solidified. When fully solidified, the solid was filtered to obtain polymer compound 1. The weight average molecular weight was 34,000.

(Production of polymer compound dispersion 1)
20 g of the polymer 1 was mixed with 80 g of methyl ethyl ketone, 160 g of ion-exchanged water, and 24.6 g of 1N sodium hydroxide solution, and the mixture was dispersed with an ultrasonic disperser for 30 minutes with stirring under ice-water cooling. The dispersion became almost transparent. Methyl ethyl ketone was distilled off from this dispersion using a rotary evaporator. The temperature of the water bath at this time was 55 ° C. Part of the water was also distilled off, resulting in a polymer compound dispersion 1 having a solid content of 10%. The average particle size was 15 nm. This polymer dispersion is self-dispersing polymer compound particles that do not contain an active agent and other dispersion resins.

(Production of polymer compound dispersions 2 to 10 and comparisons 1 to 4)
In the synthesis of polymer compound 1, polymer compounds 2 to 10 and comparisons 1 to 4 were synthesized in the same manner as the polymer compound 1 except that the monomers listed in Tables 1 and 2 were used. In the same manner as in the preparation of polymer compound dispersion 1, polymer compound dispersions 2 to 10 and comparative 1 were prepared. These are also self-dispersing polymer compound particles that do not contain an active agent and other dispersing resins.

  In the polymer compound dispersion comparison 2, the polymer compound was supplied and mixed not as particles but as a lump having a crystal having a diameter of 5 mm or more. In the polymer compound dispersion comparison 3, the solvents described in Table 2 were added to and mixed with the polymer compound dispersion comparison 1. In the polymer compound dispersion comparison 4, the solvent described in Table 2 was added to the polymer compound dispersion comparison 1, and like the cyan pigment dispersion C1 described in the examples of JP 2010-202765 A, It mixed in the aspect which melt | dissolves and mixes in a solvent, and methyl ethyl ketone was distilled off after dispersion | distribution.

(Production of coated pigment dispersion DC-1)
50 g of cyan pigment (FASTOGEN Blue GNKA-SD), 250 g of the polymer compound dispersion 1 (solid content 10%), and 200 g of ion-exchanged water were premixed to prepare Predispersion 1 (Simple Homogenizer (Ultra Turrax) )It was used).

  Preliminary dispersion 1 was placed in a 1 L pot, and dispersed using a desktop star mill miniature air (manufactured by Ashizawa) using zirconia YZT balls (0.5φ) at a filling rate of 80%.

  After the dispersion was completed, the dispersion was stored at 60 ° C. for 3 days, then returned to room temperature, and the dispersion was filtered with a 5 μm metal mesh filter. As a result, a coated pigment dispersion DC-1 having a pigment solid content concentration of 10% was obtained. The average particle size was 130 nm.

  Similarly to the production of the coated pigment dispersion DC-1, coated polymer dispersions DC-2 to 14 were produced using the polymer compound dispersions shown in Tables 1 and 2.

(Production of coated pigment dispersions DK-1 to 12)
The coated pigment dispersion DC-1 was coated in the same manner as the coated pigment dispersion DC-1, except that a black pigment was used as the pigment and the conditions described in Tables 3 and 4 were used. Pigment dispersions DK-1 to 12 were produced.

(Preparation of ink (IC-1 to 14, IK-1 to 12, IC-21 to 31))
Solvent, activator, ion-exchanged water and the coated pigment dispersion described in Table 1 were mixed so that the final ink composition shown in Tables 1 to 6 was obtained. The ink was filtered with a 1 μm filter to obtain ink IC-1 to ink IC-14, ink IK-1 to ink IK-12, and ink IC-21 to ink IC-31. The average particle diameter and viscosity of each ink were measured. The results are shown in Tables 1-6.

(Evaluation of ink)
(Dispersion stability)
Place the prepared ink in a sealed bottle, store at 60 ° C. for 20 days, return to room temperature, measure the average particle size, evaluate the change from the average particle size immediately after preparation, and measure the dispersion stability. It was.

(Ejection stability): The ink after ink storage was evaluated using a piezo-type head KM512M at an injection frequency of 13.3 kHz, a droplet velocity of 6 m / sec, and environmental conditions: a temperature of 25 ° C. and a relative humidity of 50% RH. The injection state of each nozzle after 30-minute continuous injection evaluation was observed and evaluated according to the following rank, which was used as an index of injection stability. 3 or more is a practically favorable range.
5: 50 or more 5: No missing or bent in all nozzles (512 nozzles) Stable injection 4: No missing in all nozzles (512 nozzles) 3: Slightly bent in less than 1% nozzles 3: All nozzles ( 512 nozzles), but there is a slight bend with nozzles of 1% or more and less than 5%. 2: Chipping occurs with nozzles of less than 5%. 1: Chipping occurs with nozzles of 5% or more (glossiness).
A solid image was drawn on untreated PVC (METAMARK) using a piezo type head KM512M and a drawing apparatus EB-100, XY-100 (manufactured by Konica Minolta IJ). During printing, the stage was heated, and the vinyl chloride surface temperature was heated to 50 ° C. for printing. After printing, after heating for 5 minutes at 50 ° C., 20 ° gloss was measured and used as a gloss index. 3 or more is a practically favorable range.
5:50 or more 4:40 or more but less than 50 3:30 or more but less than 40 2:20 or more but less than 30 1:20 or less The results are shown in Tables 1 to 6.

BzMA: benzyl methacrylate MMA: methyl methacrylate MAA: methacrylic acid BA: butyl acrylate St: styrene 2-PhOEtMA: 2-phenoxyethyl acrylate 2-EHA: 2-ethylhexyl acrylate 2-PDN: 2-pyrrolidinone 1,2-HD : 1,2-hexanediol MPD: 2-methyl-1,3-propanediol DMI: 1,3-dimethyl-2-imidazolidinone Activator 1 (F): Footage 100 (manufactured by Neos Co., Ltd.)
Activator 2 (EOR): BYK-Dynwet800 (BYK)
Activator 3 (Si): BYK348 (BYK)
Black pigment: Carbon black (Mitsubishi # 950, manufactured by Mitsubishi Chemical)
Latex: Acrylic latex (2-EHA / MMA / MAA) Tg 68 ° C., acid value 52
From Table 1 to Table 6, the inkjet ink produced by the production method of the present invention is an inexpensive production method, particularly without passing through a process such as distilling off the solvent, and includes dispersion stability, injection stability, It can be seen that an ink-jet ink having excellent glossiness is provided.

Claims (9)

  A method for producing an inkjet ink comprising an aqueous inkjet ink containing a pigment and water, wherein a polymer compound dispersion in which particles of a polymer compound having an average particle size of 500 nm or less are dispersed in water, the pigment, A coated pigment forming step of dispersing a pigment mixture containing water to produce a coated pigment dispersion in which the pigment is coated with the polymer compound, and the coated pigment dispersion A method for producing an ink-jet ink, characterized by comprising an inking step for producing an aqueous ink-jet ink.   The method for producing an inkjet ink according to claim 1, wherein an average particle size of the polymer compound particles is 100 nm or less.   The method for producing an inkjet ink according to claim 1 or 2, wherein the pigment mixture to be dispersed contains 5 mass% or less of a ketone or ester solvent having a boiling point of 100 ° C or less. 5. The polymer compound according to claim 1, wherein the polymer compound contains a repeating unit represented by the following general formula 1 in an amount of 30% by mass or more and 80% by mass or less based on the polymer compound. The manufacturing method of the inkjet ink as described in any one of.
General formula 1
_{- (CH 2 -CR 1 (L} 1 -L 2 -Ar)) -
(Wherein R ₁ represents a hydrogen atom or a methyl group, L ₁ represents —COO—, —CONH—, —OCO— or —NHCO—, L ₂ represents a divalent linking group, and Ar represents an aromatic ring. Represents.)   The method for producing an ink-jet ink according to any one of claims 1 to 4, wherein the water-based ink-jet ink contains alkanediol or glycol ether.   The method for producing an inkjet ink according to any one of claims 1 to 5, wherein the aqueous inkjet ink contains a solvent capable of plasticizing or dissolving vinyl chloride.   The method for producing an inkjet ink according to claim 1, wherein the water-based inkjet ink contains a resin.   An ink-jet ink manufactured by the method for manufacturing an ink-jet ink according to claim 1.   A coated pigment dispersion used in the method for producing an inkjet ink according to any one of claims 1 to 8, comprising a pigment, particles of a self-dispersing polymer compound having an average particle size of 500 nm or less, and water. A coated pigment dispersion obtained by dispersing a pigment mixture to be coated.