JP5355001B2 - Inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink set for inkjet recording, which features excellent ink flocculation properties and rapid recording capability, and an inkjet recording method which enables recording at a higher speed than in a conventional method. <P>SOLUTION: This ink set includes an ink composition containing a coloring material and a self-dispersible polymer particle and a cationic organic compound. In addition, the ink set includes a treatment liquid which can form a flocculate by coming into contact with the ink composition. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

This onset Ming, ink relates Louis inkjet recording method to record an image by ejecting an inkjet method.

  The ink jet recording method performs recording by ejecting ink from a large number of nozzles provided in an ink jet head in the form of liquid droplets. The noise during the recording operation is low, the running cost is low, and a wide variety of recording media. However, it is widely used because it can record high-quality images.

  As the ink jet recording method, there is known a two-component reaction type recording method in which fixing of ink is promoted by reacting two liquids of an ink and a treatment liquid for aggregating the ink and aggregating the ink. For example, an ink jet recording method in which an ink composition containing a pigment and a resin emulsion and a reaction liquid containing a polyvalent metal salt are attached to a recording medium is known, and image bleeding and image unevenness can be suppressed. (For example, refer to Patent Document 1).

  In addition, an ink-jet ink composition containing self-dispersing polymer particles has been disclosed in order to give good water resistance and stain resistance (see, for example, Patent Document 2).

  On the other hand, when recording on plain paper or the like, sufficient performance may not be obtained in terms of fixability (for example, scratch resistance) and resolution in addition to the color density. In particular, when ink jet recording is performed at high speed, it is difficult to obtain good fixability and resolution. Therefore, recording is not performed when shuttle recording is used, but when recording is performed at high speed using a single pass method that can be recorded with a single head operation. There is a need for improved aptitude.

In connection with the above, an inkjet ink comprising a first liquid vehicle, a pigment colorant, and a latex-containing colloidal suspension and a second liquid vehicle to obtain excellent image permanence and smudge resistance. And a system for forming an image using a fixing agent composition composed of a cationic polymer (see, for example, Patent Document 3).
JP-A-9-207424 Patent 3069543 JP 2008-105422 A

  However, the conventional two-component reaction type recording method described above has an insufficient ink aggregation rate and is difficult to apply to a higher-speed inkjet recording method. In particular, high-speed printing represented by line-type printing requires a system in which aggregation proceeds at a higher speed.

  A system using an inkjet ink containing the latex-containing colloidal suspension is also a two-component reaction type recording method, but is insufficient in terms of ink aggregation rate. Since the latex-containing colloidal suspension in this ink-jet ink is synthesized by emulsion polymerization using an emulsifier, the ink contains an emulsifier, and the emulsifier cannot necessarily adsorb to the polymer particles. It is considered that this is present in the liquid while maintaining the equilibrium state between adsorption and free, and this free emulsifier becomes an excess component in the ink and delays the aggregation action.

  The present invention has been made in view of the above, and is an ink set for ink jet recording that is excellent in ink cohesion and capable of high-speed recording more than before, and an image recording that is superior in hue and image drawing performance at a higher speed than before. It is an object of the present invention to provide an ink jet recording method capable of performing the above-mentioned and to achieve the object.

  The present invention has the effect that the emulsifier is mixed at the same time when the polymer particles are contained as a component in the ink, and the presence of the emulsifier free in the liquid has an influence on the aggregation rate when the aggregation component is supplied from the outside. This is based on the knowledge that it cannot be ignored, and has been achieved based on this knowledge.

Specific means for achieving the above object are as follows.
<1> An ink composition containing a coloring material and self-dispersing polymer particles has a water absorption coefficient Ka of 0.05 mL / m ² · ms ^{1/2 to} 0.5 mL / m ² · ms ^1/2. An ink application process that directly applies to a recording medium made of coated paper by an inkjet method, and a treatment liquid that contains a cationic organic compound and can form an aggregate by contact with the ink composition. An aromatic group-containing monomer in which the self-dispersing polymer is selected from a hydrophilic structural unit, phenoxyethyl (meth) acrylate, and benzyl (meth) acrylate Ink jet recording method which is a water-insoluble polymer containing a structural unit derived from
<2> The inkjet recording method according to <1>, wherein the cationic organic compound is a cationic polymer.
<3> The inkjet recording method according to <1> or <2>, wherein the color material is a pigment.
<4> The inkjet recording method according to any one of <1> to <3>, wherein the color material is a pigment coated with a polymer dispersant.

<5> The inkjet recording method according to any one of <1> to <4>, wherein the self-dispersing polymer has a carboxyl group and has an acid value of 25 to 100.
<6> The self-dispersing polymer particles are synthesized in an organic solvent, neutralized part or all of the carboxyl groups, and prepared as a polymer dispersion having water as a continuous phase. 1> - Ru inkjet recording method der according to any one of the <5>.

<7 > The inkjet recording method according to any one of <1> to < 6 >, wherein the ink composition further contains a hydrophilic organic solvent.
< 8 > In the ink application step, at least two types of the ink compositions are ejected by a line method with a droplet ejection interval between the ink compositions being 1 second or less, and an image is recorded. < 7 > The inkjet recording method according to any one of the above.

  According to the present invention, there is provided an ink set for ink jet recording which is excellent in ink aggregation and capable of higher speed recording than before, and an ink jet recording method capable of recording an image having higher hue and image drawing performance at a higher speed than before. Can be provided.

  Hereinafter, the ink set for ink jet recording of the present invention and the ink jet recording method using the ink set will be described in detail.

<Ink set>
The ink set for ink-jet recording of the present invention contains a colorant and self-dispersing polymer particles, a cationic organic compound, and a treatment liquid capable of forming an aggregate by contact with the ink composition Are provided.

  In general, polymer particles such as latex are synthesized by emulsion polymerization using an emulsifier. At this time, all of the emulsifier cannot be adsorbed on the polymer particles, and the liquid is kept in an equilibrium state between adsorption and free. It exists in the inside, that is, the free emulsifier exists as an excess component for aggregation, and the aggregation property when the aggregation component comes into contact with the ink tends to be lowered. In the present invention, by using a self-dispersing polymer as a component of the ink composition, the aggregating component directly acts to easily cause an aggregating reaction, so that the components in the ink composition can be aggregated at high speed. . As a result, bleeding and color mixing between ink droplets can be prevented, and an image excellent in hue and drawing performance (reproducibility of fine lines and fine portions in an image) can be obtained at a higher speed than before.

-Ink composition-
The ink composition according to the present invention includes a coloring material and self-dispersing polymer particles, and can be configured using a dispersant, a surfactant, and other components as necessary.

(Color material)
The ink composition contains at least one colorant.
As the coloring material, known dyes, pigments and the like can be used without particular limitation. Among these, from the viewpoint of ink colorability, a color material that is almost insoluble or hardly soluble in water is preferable. Specific examples include various pigments, disperse dyes, oil-soluble dyes, dyes forming J aggregates, and the like, and pigments are more preferable.
In the present invention, the water-insoluble pigment itself or the pigment itself surface-treated with a dispersant can be used as the color material.

  There is no restriction | limiting in particular as a pigment in this invention, A conventionally well-known organic and inorganic pigment can be used. For example, polycyclic pigments such as azo lakes, azo pigments, phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, diketopyrrolopyrrole pigments, thioindigo pigments, isoindolinone pigments, quinophthaloni pigments, basic Examples include dye lakes such as dye-type lakes and acid dye-type lakes, organic pigments such as nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments, and inorganic pigments such as titanium oxide, iron oxide, and carbon black. Any pigment not described in the color index can be used as long as it can be dispersed in the aqueous phase. Further, it is of course possible to use a pigment whose surface is treated with a surfactant, a polymer dispersing agent or the like, or graft carbon. Among the pigments, it is particularly preferable to use an azo pigment, a phthalocyanine pigment, an anthraquinone pigment, a quinacridone pigment, or a carbon black pigment.

Specific examples of the organic pigment used in the present invention are shown below.
Examples of organic pigments for orange or yellow 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, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. And CI Pigment Yellow 185.

  Examples of organic 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. Pigment red 222C. I. Pigment violet 19 and the like.

Examples of organic 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 15: 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. Pigment Green 7 and siloxane-crosslinked aluminum phthalocyanine described in US Pat. No. 4,311,775.
Examples of organic pigments for black include C.I. I. Pigment black 1, C.I. I. Pigment black 6, C.I. I. Pigment black 7 and the like.

~ Dispersant ~
When the colorant in the present invention is a pigment, it is preferably dispersed in an aqueous solvent by a dispersant. The dispersant may be a polymer dispersant or a low molecular surfactant type dispersant. The polymer dispersant may be either a water-soluble dispersant or a water-insoluble dispersant.
The low molecular surfactant type dispersant (hereinafter sometimes referred to as “low molecular dispersant”) may be added for the purpose of stably dispersing the organic pigment in an aqueous solvent while keeping the ink at a low viscosity. it can. The low molecular dispersant herein is a low molecular dispersant having a molecular weight of 2000 or less. Moreover, 100-2000 are preferable and, as for the molecular weight of a low molecular dispersing agent, 200-2000 are more preferable.

  The low molecular weight dispersant has a structure including a hydrophilic group and a hydrophobic group. In addition, the hydrophilic group and the hydrophobic group may be independently contained in one molecule or more, and may have a plurality of types of hydrophilic groups and hydrophobic groups. In addition, a linking group for linking a hydrophilic group and a hydrophobic group can be appropriately included.

Examples of the hydrophilic group include an anionic group, a cationic group, a nonionic group, and a betaine type combining these.
The anionic group is not particularly limited as long as it has a negative charge, but may be a phosphate group, phosphonic acid group, phosphinic acid group, sulfuric acid group, sulfonic acid group, sulfinic acid group or carboxylic acid group. Preferably, it is a phosphoric acid group or a carboxylic acid group, more preferably a carboxylic acid group.

The cationic group is not particularly limited as long as it has a positive charge, but is preferably an organic cationic substituent, more preferably a cationic group containing nitrogen or phosphorus, and nitrogen. More preferably, it is a cationic group. Among these, a pyridinium cation or an ammonium cation is particularly preferable.
The nonionic group is not particularly limited as long as it has no negative or positive charge. For example, a polyalkylene oxide, polyglycerin, a part of sugar unit, etc. are mentioned.

In the present invention, the hydrophilic group is preferably an anionic group from the viewpoint of dispersion stability and aggregation of the pigment.
Moreover, when a low molecular weight dispersing agent has an anionic hydrophilic group, it is preferable that the pKa is 3 or more from a viewpoint of making it contact with an acidic process liquid and promoting aggregation reaction. The pKa of the low molecular dispersant in the present invention is determined experimentally from a titration curve by titrating a solution of 1 mol / L of the low molecular dispersant in tetrahydrofuran-water = 3: 2 (V / V) solution with an acid or alkaline aqueous solution. It is the calculated value.
Theoretically, if the pKa of the low molecular dispersant is 3 or more, 50% or more of the anionic groups are in a non-dissociated state when in contact with a treatment solution having a pH of about 3. Accordingly, the water solubility of the low molecular weight dispersant is remarkably lowered, and an agglomeration reaction occurs. That is, the aggregation reactivity is improved. From this viewpoint, it is preferable that the low molecular dispersant has a carboxylic acid group as an anionic group.

  On the other hand, the hydrophobic group may have any structure such as hydrocarbon-based, fluorocarbon-based, and silicone-based, but is particularly preferably hydrocarbon-based. Further, these hydrophobic groups may have a linear structure or a branched structure. The hydrophobic group may have a single chain structure or two or more chain structures, and may have a plurality of types of hydrophobic groups in the case of a structure having two or more chains.

  The hydrophobic group is preferably a hydrocarbon group having 2 to 24 carbon atoms, more preferably a hydrocarbon group having 4 to 24 carbon atoms, and further preferably a hydrocarbon group having 6 to 20 carbon atoms.

  Among the polymer dispersants in the present invention, a hydrophilic polymer compound can be used as the water-soluble dispersant. For example, natural hydrophilic polymer compounds include plant polymers such as gum arabic, tragan gum, guar gum, karaya gum, locust bean gum, arabinogalactone, pectin, quince seed starch, seaweeds such as alginic acid, carrageenan and agar. Examples include molecules, animal polymers such as gelatin, casein, albumin and collagen, and microorganism polymers such as xanthene gum and dextran.

  Examples of hydrophilic polymer compounds chemically modified from natural products include fibrin polymers such as methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, sodium starch glycolate, sodium starch phosphate, etc. And seaweed polymers such as alginic acid propylene glycol ester.

  Synthetic water-soluble polymer compounds include vinyl polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl methyl ether, acrylic polymers such as polyacrylamide, polyacrylic acid or alkali metal salts thereof, and water-soluble styrene acrylic resins. Resin, water-soluble styrene maleic acid resin, water-soluble vinyl naphthalene acrylic resin, water-soluble vinyl naphthalene maleic resin, polyvinyl pyrrolidone, polyvinyl alcohol, alkali metal salt of β-naphthalene sulfonic acid formalin condensate, quaternary ammonium, amino group, etc. And a polymer compound having a cationic functional group salt in the side chain.

  Among these, from the viewpoint of pigment dispersion stability and aggregation, a polymer compound containing a carboxyl group is preferable. For example, an acrylic resin such as a water-soluble styrene acrylic resin, a water-soluble styrene maleic resin, and a water-soluble vinyl naphthalene. High molecular compounds containing a carboxyl group such as an acrylic resin and a water-soluble vinyl naphthalene maleic resin are particularly preferred.

  As the water-insoluble dispersant among the polymer dispersants, a polymer having both a hydrophobic part and a hydrophilic part can be used. For example, styrene- (meth) acrylic acid copolymer, styrene- (meth) acrylic acid- (meth) acrylic acid ester copolymer, (meth) acrylic acid ester- (meth) acrylic acid copolymer, polyethylene glycol ( Examples thereof include a meth) acrylate- (meth) acrylic acid copolymer and a styrene-maleic acid copolymer.

  The weight average molecular weight of the polymer dispersant in the present invention is preferably 3,000 to 200,000, more preferably 5,000 to 100,000, still more preferably 5,000 to 80,000, and particularly preferably 10,000. 000-60,000.

  Further, the mixing mass ratio of the pigment and the dispersant (pigment: dispersant) is preferably in the range of 1: 0.06 to 1: 3, more preferably in the range of 1: 0.125 to 1: 2. Preferably it is 1: 0.125 to 1: 1.5.

In the present invention, when a dye is used as the coloring material, a material in which the dye is held on a water-insoluble carrier can be used as the water-insoluble colored particles. As the dye, known dyes can be used without particular limitation. For example, the dyes described in JP-A-2001-115066, JP-A-2001-335714, JP-A-2002-249677 and the like can be used in the present invention. It can be used suitably. The carrier is not particularly limited as long as it is insoluble in water or hardly soluble in water, and inorganic materials, organic materials, and composite materials thereof can be used. Specifically, the carriers described in JP-A-2001-181549, JP-A-2007-169418, etc. can be suitably used in the present invention.
The carrier holding the dye (water-insoluble colored particles) can be used as an aqueous dispersion using a dispersant. As the dispersant, the above-described dispersants can be suitably used.

The color material in the present invention preferably contains a pigment and a dispersant, more preferably contains an organic pigment and a polymer dispersant, and a polymer containing an organic pigment and a carboxyl group, from the viewpoint of light resistance and quality of the image. It is particularly preferable to contain a dispersant.
Moreover, it is preferable that a coloring material is coat | covered with the polymer dispersing agent which has a carboxyl group from a cohesive viewpoint, and is water-insoluble.
Furthermore, in the present invention, from the viewpoint of cohesion, it is preferable that the acid value of the self-dispersing polymer particles is smaller than the acid value of the polymer dispersant.

The average particle diameter of the color material is preferably 10 to 200 nm, more preferably 10 to 150 nm, and still more preferably 10 to 100 nm. When the average particle size is 200 nm or less, the color reproducibility is good, the droplet ejection characteristics when droplets are ejected by the ink jet method are good, and when it is 10 nm or more, the light resistance is good. Further, the particle size distribution of the color material is not particularly limited, and may be either a wide particle size distribution or a monodisperse particle size distribution. Two or more color materials having a monodisperse particle size distribution may be mixed and used.
The average particle size and particle size distribution of the polymer particles are determined by measuring the volume average particle size by a dynamic light scattering method using a nanotrack particle size distribution measuring device UPA-EX150 (manufactured by Nikkiso Co., Ltd.). It is

You may use a color material individually by 1 type or in combination of 2 or more types.
The content of the color material in the ink composition is preferably 1 to 25 mass%, more preferably 2 to 20 mass%, and more preferably 5 to 20 mass% with respect to the ink composition from the viewpoint of image density. % Is more preferable, and 5 to 15% by mass is particularly preferable.

(Self-dispersing polymer particles)
The ink composition contains at least one kind of self-dispersing polymer particles. This self-dispersing polymer has a function of fixing the ink composition by destabilizing and agglomerating and thickening the ink when contacted with the treatment liquid described above or a dried region thereof, The fixability of the ink composition to the recording medium and the scratch resistance of the image can be further improved. Self-dispersing polymers are also preferred resin particles from the viewpoints of ejection stability and liquid stability (particularly dispersion stability) of a system containing the coloring material (particularly pigment).

  Self-dispersing polymer particles are water-insoluble polymers that can be dispersed in an aqueous medium by the functional groups (especially acidic groups or salts thereof) of the polymer itself in the absence of other surfactants. Means water-insoluble polymer particles which do not contain free emulsifiers.

Here, the dispersed state refers to an emulsified state (emulsion) in which a water-insoluble polymer is dispersed in an aqueous medium in a liquid state and a dispersed state (suspension) in which a water-insoluble polymer is dispersed in an aqueous medium in a solid state. It includes both states.
The water-insoluble polymer in the present invention is preferably a water-insoluble polymer that can be in a dispersed state in which the water-insoluble polymer is dispersed in a solid state from the viewpoint of aggregation speed and fixing property when an ink composition is used.

  The dispersion state of the self-dispersing polymer particles refers to a solution in which 30 g of a water-insoluble polymer is dissolved in 70 g of an organic solvent (for example, methyl ethyl ketone), a neutralizing agent that can neutralize 100% of the salt-forming groups of the water-insoluble polymer (salt After mixing and stirring (equipment: stirring device with stirring blade, rotation speed 200 rpm, 30 minutes, 25 ° C.), sodium hydroxide if the generating group is anionic, acetic acid if cationic, and 200 g of water are mixed, It means a state in which even after removing the organic solvent from the mixed solution, it can be visually confirmed that the dispersion state exists stably at 25 ° C. for at least one week.

  The water-insoluble polymer means a polymer having a dissolution amount of 10 g or less when the polymer is dried at 105 ° C. for 2 hours and then dissolved in 100 g of water at 25 ° C., and the dissolution amount is preferable. Is 5 g or less, more preferably 1 g or less. The dissolution amount is the dissolution amount when neutralized with sodium hydroxide or acetic acid according to the kind of the salt-forming group of the water-insoluble polymer.

  The aqueous medium is configured to contain water, and may contain a hydrophilic organic solvent as necessary. In the present invention, it is preferably composed of water and 0.2% by mass or less of a hydrophilic organic solvent with respect to water, and more preferably composed of water.

  The main chain skeleton of the water-insoluble polymer is not particularly limited. For example, a vinyl polymer or a condensation polymer (epoxy resin, polyester, polyurethane, polyamide, cellulose, polyether, polyurea, polyimide, polycarbonate, etc.) is used. it can. Of these, vinyl polymers are particularly preferred.

Preferable examples of the vinyl polymer and the monomer constituting the vinyl polymer include those described in JP-A Nos. 2001-181549 and 2002-88294. In addition, radical transfer of vinyl monomers using dissociable groups (or substituents that can be induced to dissociable groups), polymerization initiators, and iniferters, or dissociable groups on either initiators or terminators A vinyl polymer in which a dissociable group is introduced at the end of a polymer chain by ionic polymerization using a compound having (or a substituent that can be derived from a dissociable group) can also be used.
Moreover, as a suitable example of the monomer which comprises a condensation type polymer and a condensation type polymer, what is described in Unexamined-Japanese-Patent No. 2001-247787 can be mentioned.

  The self-dispersing polymer particles preferably contain a water-insoluble polymer containing a hydrophilic constituent unit and a constituent unit derived from an aromatic group-containing monomer from the viewpoint of self-dispersibility.

The hydrophilic structural unit is not particularly limited as long as it is derived from a hydrophilic group-containing monomer, and even if it is derived from one kind of hydrophilic group-containing monomer, it contains two or more hydrophilic groups. It may be derived from a monomer. The hydrophilic group is not particularly limited, and may be a dissociable group or a nonionic hydrophilic group.
In the present invention, the hydrophilic group is preferably a dissociable group and more preferably an anionic dissociable group from the viewpoint of promoting self-dispersion and the stability of the formed emulsified or dispersed state. Examples of the dissociable group include a carboxyl group, a phosphoric acid group, and a sulfonic acid group. Among them, a carboxyl group is preferable from the viewpoint of fixability when an ink composition is configured.

The hydrophilic group-containing monomer in the present invention is preferably a dissociable group-containing monomer from the viewpoints of self-dispersibility and aggregation, and is a dissociable group-containing monomer having a dissociable group and an ethylenically unsaturated bond. It is preferable.
Examples of the dissociable group-containing monomer include an unsaturated carboxylic acid monomer, an unsaturated sulfonic acid monomer, and an unsaturated phosphoric acid monomer.

Specific examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, and 2-methacryloyloxymethyl succinic acid.
Specific examples of the unsaturated sulfonic acid monomer include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) acrylate, and bis- (3-sulfopropyl) -itaconate. Can be mentioned.
Specific examples of the unsaturated phosphoric acid monomer include vinylphosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2 -Acryloyloxyethyl phosphate and the like.
Among the dissociable group-containing monomers, from the viewpoint of dispersion stability and ejection stability, unsaturated carboxylic acid monomers are preferable, acrylic monomers are more preferable, and acrylic acid and methacrylic acid are particularly preferable.

The particles of the self-dispersing polymer in the present invention preferably contain a polymer having a carboxyl group from the viewpoint of self-dispersibility and the aggregation rate when the treatment liquid comes into contact, and have a carboxyl group and an acid value (mgKOH / More preferably, g) comprises a polymer of 25-100. Furthermore, the acid value is more preferably from 30 to 90, and particularly preferably from 35 to 65, from the viewpoint of self-dispersibility and the aggregation rate when the treatment liquid comes into contact.
In particular, when the acid value is 25 or more, the stability of self-dispersibility is good, and when it is 100 or less, the cohesiveness is improved.

The aromatic group-containing monomer is not particularly limited as long as it is a compound containing an aromatic group and a polymerizable group. The aromatic group may be a group derived from an aromatic hydrocarbon or a group derived from an aromatic heterocycle. In the present invention, an aromatic group derived from an aromatic hydrocarbon is preferable from the viewpoint of particle shape stability in an aqueous medium.
Further, the polymerizable group may be a condensation polymerizable polymerizable group or an addition polymerizable polymerizable group. In the present invention, from the viewpoint of particle shape stability in an aqueous medium, an addition polymerizable group is preferable, and a group containing an ethylenically unsaturated bond is more preferable.

  The aromatic group-containing monomer in the present invention is preferably a monomer having an aromatic group derived from an aromatic hydrocarbon and an ethylenically unsaturated bond. The aromatic group-containing monomer may be used alone or in combination of two or more.

Examples of the aromatic group-containing monomer include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate, and a styrene monomer. Of these, aromatic group-containing (meth) acrylate monomers are preferred from the viewpoint of the balance between the hydrophilicity and hydrophobicity of the polymer chain and the ink fixability, and include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, and phenyl (meth). At least one selected from acrylates is more preferable, and phenoxyethyl (meth) acrylate and benzyl (meth) acrylate are more preferable.
“(Meth) acrylate” means acrylate or methacrylate.

The self-dispersing polymer in the present invention is preferably an acrylic resin containing a structural unit derived from a (meth) acrylate monomer, preferably an acrylic resin containing a structural unit derived from an aromatic group-containing (meth) acrylate monomer, Includes a structural unit derived from an aromatic group-containing (meth) acrylate monomer, and the content thereof is preferably 10% by mass to 95% by mass. When the content of the aromatic group-containing (meth) acrylate monomer is 10% by mass to 95% by mass, the stability of the self-emulsification or dispersion state can be improved, and further the increase in ink viscosity can be suppressed.
In the present invention, from the viewpoints of stability in a self-dispersing state, stabilization of particle shape in an aqueous medium due to hydrophobic interaction between aromatic rings, and reduction in the amount of water-soluble components due to appropriate hydrophobicization of particles. More preferably, the content is from mass% to 90 mass%, more preferably from 15 mass% to 80 mass%, and particularly preferably from 25 mass% to 70 mass%.

  The self-dispersing polymer in the present invention can be constituted using, for example, a structural unit derived from an aromatic group-containing monomer and a structural unit derived from a dissociable group-containing monomer. Furthermore, other structural units may be further included as necessary.

The monomer that forms the other structural unit is not particularly limited as long as it is a monomer copolymerizable with the aromatic group-containing monomer and the dissociable group-containing monomer. Among these, an alkyl group-containing monomer is preferable from the viewpoint of flexibility of the polymer skeleton and ease of control of the glass transition temperature (Tg).
Examples of the alkyl group-containing monomer include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, Alkyl (meth) acrylates such as t-butyl (meth) acrylate, hexyl (meth) acrylate, ethylhexyl (meth) acrylate, and hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) ) Ethylenically unsaturated monomers having hydroxyl groups such as acrylate, 4-hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate, hydroxyhexyl (meth) acrylate, and dimethyl (Meth) acrylic ester monomers such as dialkylaminoalkyl (meth) acrylates such as ruaminoethyl (meth) acrylate; N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N-hydroxybutyl (meth) N-hydroxyalkyl (meth) acrylamide such as acrylamide, N-methoxymethyl (meth) acrylamide, N-ethoxymethyl (meth) acrylamide, N- (n-, iso) butoxymethyl (meth) acrylamide, N-methoxyethyl (Meth) acrylamide, such as (meth) acrylamide, N-ethoxyethyl (meth) acrylamide, N-alkoxyalkyl (meth) acrylamide such as N- (n-, iso) butoxyethyl (meth) acrylamide, etc. And (meth) acrylamide-based monomers like.

  The molecular weight of the water-insoluble polymer constituting the self-dispersing polymer particles is preferably 3000 to 200,000, more preferably 5000 to 150,000, and more preferably 10,000 to 100,000 in terms of weight average molecular weight. Further preferred. By setting the weight average molecular weight to 3000 or more, the amount of water-soluble components can be effectively suppressed. Moreover, self-dispersion stability can be improved by making a weight average molecular weight into 200,000 or less.

  The weight average molecular weight is measured by gel permeation chromatography (GPC). For GPC, HLC-8220GPC (manufactured by Tosoh Corporation) is used, and TSKgel SuperHZM-H, TSKgel SuperHZ4000, TSKgel SuperHZ2000 (manufactured by Tosoh Corporation, 4.6 mm ID × 15 cm) are used as eluents as columns. Use THF (tetrahydrofuran). The conditions are as follows: the sample concentration is 0.35 / min, the flow rate is 0.35 ml / min, the sample injection amount is 10 μl, the measurement temperature is 40 ° C., and an IR detector is used. In addition, the calibration curve is “standard sample TSK standard, polystyrene” manufactured by Tosoh Corporation: “F-40”, “F-20”, “F-4”, “F-1”, “A-5000”, It is prepared from 8 samples of “A-2500”, “A-1000”, “n-propylbenzene”.

The water-insoluble polymer constituting the self-dispersing polymer particles is derived from a structural unit derived from an aromatic group-containing (meth) acrylate monomer (preferably phenoxyethyl (meth) acrylate) from the viewpoint of controlling the hydrophilicity / hydrophobicity of the polymer. It is preferable that 15-80 mass% of the total mass of a self-dispersing polymer particle is included as a copolymerization ratio for a structural unit and / or a structural unit derived from benzyl (meth) acrylate.
In addition, the water-insoluble polymer has a constitution derived from a carboxyl group-containing monomer having a copolymerization ratio of 15 to 80% by mass of a constitutional unit derived from an aromatic group-containing (meth) acrylate monomer from the viewpoint of controlling the hydrophilicity / hydrophobicity of the polymer. And a structural unit derived from an alkyl group-containing monomer (preferably a structural unit derived from an alkyl ester of (meth) acrylic acid), and a structural unit derived from phenoxyethyl (meth) acrylate and / or Alternatively, a structural unit derived from benzyl (meth) acrylate as a copolymerization ratio of 15 to 80% by mass, a structural unit derived from a carboxyl group-containing monomer, and a structural unit derived from an alkyl group-containing monomer (preferably (meth) Structural unit derived from an alkyl ester having 1 to 4 carbon atoms of acrylic acid) More preferably, the acid value is 25 to 100, the weight average molecular weight is preferably 3000 to 200,000, the acid value is 30 to 90, and the weight average molecular weight is 5000 to 150,000. It is more preferable that

  Specific examples (exemplary compounds B-01 to B-19) of water-insoluble polymers constituting the self-dispersing polymer particles are given below. However, the present invention is not limited to these. The values in parentheses represent the mass ratio of the copolymer component.

B-01: Phenoxyethyl acrylate / methyl methacrylate / acrylic acid copolymer (50/45/5)
B-02: Phenoxyethyl acrylate / benzyl methacrylate / isobutyl methacrylate / methacrylic acid copolymer (30/35/29/6)
B-03: Phenoxyethyl methacrylate / isobutyl methacrylate / methacrylic acid copolymer (50/44/6)
B-04: Phenoxyethyl acrylate / methyl methacrylate / ethyl acrylate / acrylic acid copolymer (30/55/10/5)
B-05: benzyl methacrylate / isobutyl methacrylate / methacrylic acid copolymer (35/59/6)
B-06: Styrene / phenoxyethyl acrylate / methyl methacrylate / acrylic acid copolymer (10/50/35/5)
B-07: benzyl acrylate / methyl methacrylate / acrylic acid copolymer (55/40/5)
B-08: Phenoxyethyl methacrylate / benzyl acrylate / methacrylic acid copolymer (45/47/8)
B-09: Styrene / phenoxyethyl acrylate / butyl methacrylate / acrylic acid copolymer (5/48/40/7)
B-10: benzyl methacrylate / isobutyl methacrylate / cyclohexyl methacrylate / methacrylic acid copolymer (35/30/30/5)
B-11: Phenoxyethyl acrylate / methyl methacrylate / butyl acrylate / methacrylic acid copolymer (12/50/30/8)
B-12: benzyl acrylate / isobutyl methacrylate / acrylic acid copolymer (93/2/5)
B-13: Styrene / phenoxyethyl methacrylate / butyl acrylate / acrylic acid copolymer (50/5/20/25)
B-14: Styrene / butyl acrylate / acrylic acid copolymer (62/35/3)
B-15: Methyl methacrylate / phenoxyethyl acrylate / acrylic acid copolymer (45/51/4)
B-16: Methyl methacrylate / phenoxyethyl acrylate / acrylic acid copolymer (45/49/6)
B-17: Methyl methacrylate / phenoxyethyl acrylate / acrylic acid copolymer (45/48/7)
B-18: Methyl methacrylate / phenoxyethyl acrylate / acrylic acid copolymer (45/47/8)
B-19: Methyl methacrylate / phenoxyethyl acrylate / acrylic acid copolymer (45/45/10)

  The production method of the water-insoluble polymer constituting the self-dispersing polymer particles in the present invention is not particularly limited. For example, emulsion polymerization is performed in the presence of a polymerizable surfactant, and the surfactant and the water-insoluble polymer are mixed. And a method of copolymerizing the monomer mixture containing the hydrophilic group-containing monomer and the aromatic group-containing monomer by a known polymerization method such as a solution polymerization method or a bulk polymerization method. Among the polymerization methods, a solution polymerization method is preferable and a solution polymerization method using an organic solvent is more preferable from the viewpoint of aggregation rate and droplet ejection stability when an ink composition is used.

  The self-dispersing polymer in the present invention includes a polymer synthesized in an organic solvent from the viewpoint of aggregation rate, the polymer has a carboxyl group, and the polymer (preferably has an acid value of 25 to 100, more (Preferably, the acid value is 30 to 90, and more preferably the acid value is 35 to 65) A part or all of the carboxyl group is neutralized and prepared as a polymer dispersion having water as a continuous phase It is preferable that That is, the production of the self-dispersing polymer particles in the present invention includes a step of synthesizing a polymer in an organic solvent and a dispersion step of making an aqueous dispersion in which at least a part of the carboxyl groups of the polymer is neutralized. It is preferable to do so.

The dispersion step preferably includes the following step (1) and step (2).
Step (1): Step of stirring a mixture containing a polymer (water-insoluble polymer), an organic solvent, a neutralizing agent, and an aqueous medium Step (2): Step of removing the organic solvent from the mixture

The step (1) is preferably a treatment in which a polymer (water-insoluble polymer) is first dissolved in an organic solvent, then a neutralizing agent and an aqueous medium are gradually added, mixed and stirred to obtain a dispersion. In this way, by adding a neutralizing agent and an aqueous medium to a water-insoluble polymer solution dissolved in an organic solvent, a self-dispersing polymer having a particle size with higher storage stability without requiring strong shearing force. Particles can be obtained.
There is no restriction | limiting in particular in the stirring method of this mixture, Dispersing machines, such as a generally used mixing stirring apparatus and an ultrasonic disperser, a high-pressure homogenizer, can be used as needed.

Preferred examples of the organic solvent include alcohol solvents, ketone solvents, and ether solvents.
Examples of the alcohol solvent include isopropyl alcohol, n-butanol, t-butanol, ethanol and the like. Examples of the ketone solvent include acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone. Examples of ether solvents include dibutyl ether and dioxane. Among these solvents, ketone solvents such as methyl ethyl ketone and alcohol solvents such as isopropyl alcohol are preferable. It is also preferable to use isopropyl alcohol and methyl ethyl ketone in combination for the purpose of moderating the polarity change during the phase inversion from oil to water. By using this solvent in combination, it is possible to obtain self-dispersing polymer particles having a fine particle size with high dispersion stability without aggregation and sedimentation and fusion between particles.

  The neutralizing agent is used so that a part or all of the dissociable group is neutralized and the self-dispersing polymer forms a stable emulsified or dispersed state in water. When the self-dispersing polymer of the present invention has an anionic dissociative group (for example, a carboxyl group) as a dissociable group, the neutralizing agent used is basic such as an organic amine compound, ammonia, or an alkali metal hydroxide. Compounds. Examples of organic amine compounds include monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monopropylamine, dipropylamine, monoethanolamine, diethanolamine, triethanolamine, N, N-dimethyl-ethanolamine, N, N-diethyl-ethanolamine, 2-dimethylamino-2-methyl-1-propanol, 2-amino-2-methyl-1-propanol, N-methyldiethanolamine, N-ethyldiethanolanine, monoisopropanolamine, di Examples include isopropanolamine and triisopropanolamine. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide. Among these, sodium hydroxide, potassium hydroxide, triethylamine, and triethanolamine are preferable from the viewpoint of stabilizing the dispersion of the self-dispersing polymer particles of the present invention in water.

  These basic compounds are preferably used in an amount of 5 to 120 mol%, more preferably 10 to 110 mol%, still more preferably 15 to 100 mol%, based on 100 mol% of the dissociable group. . By setting it as 15 mol% or more, the effect which stabilizes dispersion | distribution of the particle | grains in water expresses, and there exists an effect which reduces a water-soluble component by setting it as 100 mol% or less.

  In the step (2), the aqueous dispersion of the self-dispersing polymer particles is obtained by distilling off the organic solvent from the dispersion obtained in the step (1) by a conventional method such as distillation under reduced pressure and phase-inversion into an aqueous system. A dispersion can be obtained. The organic solvent in the obtained aqueous dispersion has been substantially removed, and the amount of the organic solvent is preferably 0.2% by mass or less, more preferably 0.1% by mass or less.

The average particle diameter of the self-dispersing polymer particles is preferably in the range of 10 nm to 400 nm, more preferably in the range of 10 to 200 nm, and still more preferably in the range of 10 to 100 nm. When the volume average particle size is 10 nm or more, the production suitability is improved, and when it is 1 μm or less, the storage stability is improved.
The particle size distribution of the self-dispersing polymer particles is not particularly limited, and may be either a wide particle size distribution or a monodispersed particle size distribution. Further, two or more water-insoluble particles may be mixed and used.
The average particle size and particle size distribution of the self-dispersing polymer particles are measured by the dynamic light scattering method using Nanotrac particle size distribution analyzer UPA-EX150 (manufactured by Nikkiso Co., Ltd.). Is required.

  The glass transition temperature (Tg) of the self-dispersing polymer is preferably 30 ° C. or higher, more preferably 40 ° C. or higher, and further preferably 50 ° C. or higher, from the viewpoint of the storage stability of the water-based ink.

  The self-dispersing polymer particles can be used singly or in combination of two or more. The content of the self-dispersing polymer particles in the ink composition is preferably 0.5 to 20% by mass with respect to the ink composition from the viewpoints of aggregation rate and image glossiness. More preferably, it is 10 mass%, and 2-8% is still more preferable.

  In addition, the content ratio of the coloring material and the self-dispersing polymer particles in the ink composition (for example, water-insoluble colored particles / self-dispersing polymer particles) is 1/2 from the viewpoint of image scratch resistance. It is preferably 0.5 to 1/10, and more preferably 1/1 to 1/4.

(water)
The ink composition contains water, but the amount of water is not particularly limited. Especially, the preferable content of water is 10 to 99% by mass, more preferably 30 to 80% by mass, and still more preferably 50 to 70% by mass.

(Hydrophilic organic solvent)
The ink composition contains water as a solvent, but can further contain at least one hydrophilic organic solvent. By containing the hydrophilic organic solvent, drying prevention and penetration promotion can be achieved. When a hydrophilic organic solvent is used as an anti-drying agent, nozzle clogging that may occur due to ink drying at the ink discharge port is effectively prevented when an ink composition is discharged by an inkjet method to record an image. be able to.

In order to prevent drying, a hydrophilic organic solvent having a vapor pressure lower than that of water is preferable. Specific examples of hydrophilic organic solvents suitable for drying prevention include ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, thiodiglycol, dithiodiglycol, 2-methyl-1,3-propanediol, 1,2 , 6-hexanetriol, acetylene glycol derivative, glycerin, polyhydric alcohols represented by trimethylolpropane, ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monoethyl (or butyl) ) Lower alkyl ethers of polyhydric alcohols such as ethers, heterocyclic rings such as 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-ethylmorpholine, Horan, dimethyl sulfoxide, sulfur-containing compounds such as sulfolane, diacetone alcohol, polyfunctional compounds such as diethanolamine, and urea derivatives.
Of these, polyhydric alcohols such as glycerin and diethylene glycol are preferred. Moreover, these may be used individually by 1 type, or may use 2 or more types together. These hydrophilic organic solvents are preferably contained in the ink composition in an amount of 10 to 50% by mass.

  In order to promote penetration, a hydrophilic organic solvent is preferably used from the viewpoint of allowing the ink composition to penetrate better into the recording medium. Specific examples of hydrophilic organic solvents suitable for promoting penetration include alcohols such as ethanol, isopropanol, butanol, di (tri) ethylene glycol monobutyl ether, 1,2-hexanediol, sodium lauryl sulfate, and sodium oleate. And nonionic surfactants. A good effect is acquired by containing these 5-30 mass% in an ink composition. These hydrophilic organic solvents are preferably used within a range of addition amounts that do not cause printing / image bleeding and paper loss (print-through).

In addition to the above, the hydrophilic organic solvent can be used for adjusting the viscosity. Specific examples of hydrophilic organic solvents that can be used to adjust the viscosity include alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, t-butanol, pentanol, hexanol, Cyclohexanol, benzyl alcohol), 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), glycol derivatives (eg, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether) Tellurium, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, Triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, ethylene glycol monophenyl ether), amine (eg, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, Tylenediamine, diethylenetriamine, triethylenetetramine, polyethyleneimine, tetramethylpropylenediamine) and other polar solvents (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, acetonitrile, acetone).
In addition, you may use a hydrophilic organic solvent individually by 1 type or in mixture of 2 or more types.

(Other additives)
In addition to the above components, the ink composition can contain other additives as necessary. Other additives include, for example, antifading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, antiseptics, antifungal agents, pH adjusters, surface tension adjusters, antifoaming agents, viscosity adjusters, and dispersions. Well-known additives such as an agent, a dispersion stabilizer, a rust inhibitor, and a chelating agent can be used. These various additives may be added directly after the ink composition is prepared, or may be added when the ink composition is prepared.

  The ultraviolet absorber can improve the storage stability of the image. Examples of ultraviolet absorbers include benzotriazoles described in JP-A Nos. 58-185677, 61-190537, JP-A-2-782, JP-A-5-97075, JP-A-9-34057, and the like. Compounds, benzophenone compounds described in JP-A-46-2784, JP-A-5-194443, US Pat. No. 3,214,463, etc., JP-B-48-30492, JP-A-56-21141 Cinnamic acid compounds described in JP-A-10-88106, JP-A-4-298503, JP-A-8-53427, JP-A-8-239368, JP-A-10-182621, JP The triazine compounds described in JP-A-8-501291, Research Disclosure No. Compounds described in No. 24239, compounds that emit fluorescence by absorbing ultraviolet rays typified by stilbene-based and benzoxazole-based compounds, so-called fluorescent brighteners, can also be used.

  The anti-fading agent can improve the storage stability of the image. As the antifading agent, various organic and metal complex antifading agents can be used. Organic anti-fading agents include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, heterocycles, etc. Complex, zinc complex and the like. More specifically, Research Disclosure No. No. 17643, Nos. VII to I, J; 15162, ibid. No. 18716, page 650, left column, ibid. No. 36544, page 527, ibid. No. 307105, page 872, ibid. The compounds described in the patent cited in Japanese Patent No. 15162 and the compounds included in the general formulas and compound examples of typical compounds described on pages 127 to 137 of JP-A-62-215272 can be used.

  Examples of the antifungal agent include sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, p-hydroxybenzoic acid ethyl ester, 1,2-benzisothiazolin-3-one and salts thereof. These are preferably used in the ink composition in an amount of 0.02 to 1.00% by mass.

  As the pH adjuster, a neutralizer (organic base, inorganic alkali) can be used. From the viewpoint of improving the storage stability of the ink composition, the pH adjuster is preferably added so that the ink composition has a pH of 6 to 10, and more preferably added to have a pH of 7 to 10.

Examples of the surface tension adjusting agent include nonionic surfactants, cationic surfactants, anionic surfactants, betaine surfactants, and the like.
Further, the addition amount of the surface tension adjusting agent is preferably an addition amount for adjusting the surface tension of the ink composition to 20 to 60 mN / m in order to favorably discharge by the ink jet method, and an addition for adjusting to 20 to 45 mN / m. The amount is more preferable, and the addition amount adjusted to 25 to 40 mN / m is more preferable. On the other hand, when ink is applied by a method other than the inkjet method, the range of 20 to 60 mN / m is preferable, and the range of 30 to 50 mN / m is more preferable.
The surface tension of the ink composition can be measured by the Wilhelmi method using a platinum plate using an Automatic Surface Tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.).

Specific examples of surfactants include fatty acid salts, alkyl sulfate esters, alkylbenzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphate esters, naphthalene sulfonate formalin condensates in hydrocarbons, Anionic surfactants such as polyoxyethylene alkyl sulfate salts, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkyl Nonionic surfactants such as amines, glycerin fatty acid esters and oxyethyleneoxypropylene block copolymers are preferred. Further, SURFYNOLS (Air Products & Chemicals), which is an acetylene-based polyoxyethylene oxide surfactant, is also preferably used. An amine oxide type amphoteric surfactant such as N, N-dimethyl-N-alkylamine oxide is also preferred.
Furthermore, pages (37) to (38) of JP-A-59-157636, Research Disclosure No. The surfactants described in 308119 (1989) can also be used.
Further, fluorine (fluorinated alkyl type) surfactants, silicone type surfactants and the like described in JP-A Nos. 2003-322926, 2004-325707, and 2004-309806 are disclosed. By using, the abrasion resistance can be improved.
Further, the surface tension adjusting agent can also be used as an antifoaming agent, and fluorine compounds, silicone compounds, chelating agents represented by EDTA, and the like can also be used.

The viscosity of the ink composition is preferably in the range of 1 to 30 mPa · s, preferably 1 to 20 mPa · s, from the viewpoint of ejection stability and the aggregation rate when contacted with the treatment liquid when applied by ink jetting. The range of s is more preferable, the range of 2 to 15 mPa · s is more preferable, and the range of 2 to 10 mPa · s is particularly preferable.
In addition, when the ink composition is applied by a method other than the inkjet method, the range of 1 to 40 mPa · s is preferable, and the range of 5 to 20 mPa · s is more preferable.
The viscosity of the ink composition can be measured using, for example, a Brookfield viscometer.

-Treatment liquid-
The treatment liquid in the present invention contains a cationic organic compound, and is configured so as to be able to form an aggregate by contacting with the ink composition described above. If necessary, other components are used. Can be configured. By using the treatment liquid together with the ink composition, it is possible to increase the speed of ink jet recording, and an image with excellent density and resolution can be obtained even when recording at high speed (for example, reproducibility of fine lines and fine portions).

(Cationic organic compounds)
The treatment liquid is a cationic organic compound as an aggregating component capable of agglomerating particles such as pigments and self-dispersing polymer particles in the ink composition when contacted with the ink composition described above. Containing at least one of the following.

  Examples of the cationic organic compound include poly (vinyl pyridine) salt, polyalkylaminoethyl acrylate, polyalkylaminoethyl methacrylate, poly (vinyl imidazole), polyethyleneimine, polybiguanide, polyguanide, polyamine and derivatives thereof, or polyallylamine. And cationic polymers such as derivatives thereof. Commercially available cationic polymers include PAA-HCL-01, PAA-HCL-03, PAA-HCL-05, PAA-HCL-3L, PAA-H-HCL, and PAA-HCL- manufactured by Nittobo Co., Ltd. Allylamine hydrochloride polymers such as 10L, PAA-05, PAA-D11-HCL, PAS-H-1L, PAS-M-1L, PAS-A-1, PAS-J-81L, PAS-880, PAS- Diallyl-based amine polymers such as 92.

  The weight average molecular weight of the cationic polymer is preferably smaller in terms of the viscosity of the treatment liquid. When the treatment liquid is applied to the recording medium by an ink jet method, the range of 1,000 to 500,000 is preferable, the range of 1,500 to 200,000 is more preferable, and still more preferably 2,000 to 100,000. Range. When the weight average molecular weight is 1000 or more, it is advantageous from the viewpoint of the aggregation rate, and when it is 500,000 or less, it is advantageous from the viewpoint of ejection reliability. However, this is not the case when the treatment liquid is applied to the recording medium by a method other than inkjet.

Furthermore, as the cationic organic compound, for example, a primary, secondary, or tertiary amine salt type compound is preferable. Examples of the amine salt type compounds include compounds such as hydrochloride or acetate (for example, laurylamine, cocoamine, stearylamine, rosinamine), quaternary ammonium salt type compounds (for example, lauryltrimethylammonium chloride, cetyltrimethyl). Ammonium chloride, lauryldimethylbenzylammonium chloride, benzyltributylammonium chloride, benzalkonium chloride, etc.), pyridinium salt type compounds (eg, cetylpyridinium chloride, cetylpyridinium bromide, etc.), imidazoline type cationic compounds (eg, 2-heptadecenyl- Hydroxyethyl imidazoline etc.), ethylene oxide adducts of higher alkylamines (eg dihydroxyethyl stearylamine etc.), etc. And cationic compounds, for example, amino acid type amphoteric _{surfactants, R-NH-CH 2 CH} 2 -COOH type compounds, carboxylic acid salt type amphoteric surfactants (e.g., stearyl dimethyl betaine, lauryl dihydroxyethyl betaine, etc. ), Amphoteric surfactants exhibiting a cationic property in a desired pH range, such as amphoteric surfactants such as sulfate ester type, sulfonic acid type, and phosphate ester type.

  As the cationic organic compound in the present invention, a cationic polymer is preferable from the viewpoint of aggregability and image scratch resistance, and a polymer containing a pyridinium salt, an imidazolium salt or a quaternary ammonium salt is particularly preferable. And derivatives thereof (for example, allylamine hydrochloride polymer) and polybiguanide are more preferable.

  Further, the treatment liquid may contain an acidic compound as another aggregating component from the viewpoint of the aggregating speed of the ink composition, if necessary. As the acidic compound, a compound having a phosphoric acid group, a phosphonic acid group, a phosphinic acid group, a sulfuric acid group, a sulfonic acid group, a sulfinic acid group, or a carboxyl group, or a salt thereof (for example, a polyvalent metal salt) can be used. .

  As content in the processing liquid of a cationic organic compound, it is preferable that it is 0.5-30 mass% with respect to the total mass of a processing liquid from a viewpoint of the aggregation effect, and it is 1-25 mass%. Is more preferably 4 to 20% by mass.

  In the present invention, among the constitutions of the ink composition and the treatment liquid, the cationic organic contained in the treatment liquid from the viewpoint that high-speed aggregation can be performed and the hue of the image and the image drawing property under high-speed recording are further improved. The compound is preferably in dissolved form, and the polymer particles in the ink composition are preferably acrylic resins having an acid value of 30 to 90 mgKOH / g.

(Other ingredients)
The treatment liquid in the present invention can generally contain a water-soluble organic solvent in addition to the aggregating component including the cationic organic compound, and further various other additives within the range not impairing the effects of the present invention. Can be used. The details of the water-soluble organic solvent are the same as those in the ink composition described above.

  Examples of the other additives include a drying inhibitor (wetting agent), an antifading agent, an emulsion stabilizer, a penetration accelerator, an ultraviolet absorber, an antiseptic, an antifungal agent, a pH adjuster, a surface tension adjuster, Known additives such as antifoaming agents, viscosity modifiers, dispersants, dispersion stabilizers, rust preventives, chelating agents are listed, and specific examples of other additives included in the ink composition described above The listed ones are applicable.

The viscosity of the treatment liquid is preferably in the range of 1 to 30 mPa · s, more preferably in the range of 1 to 20 mPa · s, still more preferably in the range of 2 to 15 mPa · s, from the viewpoint of the aggregation rate of the ink composition. The range of 10 mPa · s is particularly preferable.
The viscosity is measured under a condition of 20 ° C. using VISCOMETER TV-22 (manufactured by TOKI SANGYO CO. LTD).

The surface tension of the treatment liquid is preferably 20 to 60 mN / m, more preferably 20 to 45 mN / m, and more preferably 25 to 40 mN / m from the viewpoint of the aggregation rate of the ink composition. More preferably.
The surface tension is measured under conditions of 25 ° C. using an Automatic Surface Tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.).

<Inkjet recording method>
The ink jet recording method of the present invention comprises an ink application step of applying an ink composition containing a coloring material and self-dispersing polymer particles to a recording medium by an ink jet method, a cationic organic compound, and contacting the ink composition And a treatment liquid application step of applying a treatment liquid capable of forming an aggregate to the recording medium. The ink jet recording method of the present invention can be constituted by further providing other steps as necessary.

  In the present invention, by using a self-dispersing polymer as a component of the ink composition, the free emulsifier generally mixed when resin particles are contained in the liquid is reduced or removed, and the aggregating component acts directly. By making it easy to do, high-speed aggregation of the components in the ink composition becomes possible. As a result, bleeding and color mixing between ink droplets can be prevented, and an image excellent in hue and drawing performance (reproducibility of fine lines and fine portions in an image) can be obtained at a higher speed than before.

Hereafter, each process which comprises the inkjet recording method of this invention is demonstrated.
-Ink application process-
In the ink application process, an ink composition containing a coloring material and self-dispersing polymer particles is applied to a recording medium by an inkjet method. In this step, the ink composition can be selectively applied onto the recording medium, and a desired visible image can be formed. The ink composition contains at least a colorant and self-dispersing polymer particles, and details of the ink composition such as details of each component and preferred embodiments are as described above.

  Specifically, the image recording using the ink-jet method is performed by supplying energy to obtain a desired recording medium, that is, plain paper, resin-coated paper, for example, JP-A-8-169172 and JP-A-8-27693. Publication No. 2-276670, No. 7-276789, No. 9-323475, No. JP-A-62-238783, JP-A-10-153898, No. 10-217473, No. 10- No. 235995, No. 10-337947, No. 10-217597, No. 10-337947, etc. Liquid composition for ink jet paper, film, electrophotographic co-paper, fabric, glass, metal, ceramics, etc. This can be done by discharging objects. As a preferable ink jet recording method for the present invention, the method described in paragraph Nos. 0093 to 0105 of JP-A No. 2003-306623 can be applied.

The inkjet method is not particularly limited, and is a known method, for example, a charge control method that discharges ink using electrostatic attraction, a drop-on-demand method (pressure pulse method) that uses vibration pressure of a piezoelectric element, an electric method An acoustic ink jet system that converts a signal into an acoustic beam, irradiates the ink with ink and ejects the ink using radiation pressure, and a thermal ink jet (bubble jet (registered trademark)) that heats the ink to form bubbles and uses the generated pressure. )) Any method may be used. As an ink-jet method, in particular, the method described in Japanese Patent Application Laid-Open No. 54-59936 causes a sudden volume change of the ink subjected to the action of thermal energy, and the ink is ejected from the nozzle by the action force caused by this state change. Ink jet method can be used effectively.
The ink jet method includes a method of ejecting many low-density inks called photo inks in a small volume, a method of improving image quality using a plurality of inks having substantially the same hue and different concentrations, and colorless and transparent inks. The method using is included.

In addition, an ink jet head used in the ink jet method may be an on-demand method or a continuous method. In addition, as a discharge method, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electro-thermal conversion method (for example, a thermal type) Specific examples include an ink jet type, a bubble jet (registered trademark) type, an electrostatic suction type (for example, an electric field control type, a slit jet type, etc.) and a discharge type (for example, a spark jet type). However, any discharge method may be used.
There are no particular restrictions on the ink nozzles used when recording by the ink jet method, and they can be appropriately selected according to the purpose.

Specific examples of the ink jet recording method are shown below.
As an inkjet recording method, there is (1) a method called an electrostatic attraction method. In the electrostatic suction method, a strong electric field is applied between the nozzle and the acceleration electrode arranged in front of the nozzle, and droplet-like ink is continuously ejected from the nozzle, and the ink droplet passes between the deflection electrodes. In the meantime, by supplying a printing information signal to the deflection electrode, the ink droplets are blown onto the recording medium to fix the ink on the recording medium, and the image is recorded or printing is performed without deflecting the ink droplets. In this method, an image is fixed on a recording medium by ejecting ink droplets from a nozzle toward the recording medium in accordance with an information signal. In addition, (2) there is a method of forcibly ejecting ink droplets from a nozzle by applying pressure to the ink liquid with a small pump and mechanically vibrating the ink jet nozzle with a crystal resonator or the like. The ink droplet ejected from the nozzle is charged at the same time as it is ejected, and while the ink droplet passes between the deflection electrodes, a print information signal is given to the deflection electrode to fly the ink droplet toward the recording medium, This is a method for recording an image on a recording medium. Next, (3) A method of recording an image on a recording medium (piezo) by simultaneously applying pressure and a printing information signal to the ink liquid by a piezoelectric element and ejecting ink droplets from the nozzle toward the recording medium (4) A method for recording an image on a recording medium by injecting the ink liquid from a nozzle toward a recording medium by expanding the bubbles by heating the ink liquid using microelectrodes in accordance with print signal information (bubble Jet (registered trademark).

  As an inkjet head, a short serial head is used, and a shuttle system that performs recording while scanning the head in the width direction of the recording medium, and a line head in which recording elements are arranged corresponding to the entire area of one side of the recording medium There is a line system using. In the line system, an image can be recorded on the entire surface of the recording medium by scanning the recording medium in a direction orthogonal to the arrangement direction of the recording elements, and a carriage system such as a carriage for scanning a short head is not necessary. Further, since complicated scanning control of the carriage movement and the recording medium is not required, and only the recording medium is moved, the recording speed can be increased as compared with the shuttle system. The ink jet recording method of the present invention can be applied to any of these, but generally, when applied to a line system that does not use a dummy jet, the effect of improving ejection accuracy and image scratch resistance is great.

  Furthermore, in the ink application process in the present invention, in the case of the line method, not only one type of ink composition is used but also two or more types of ink compositions are used, and an ink composition (nth color ( n ≧ 1), for example, the second color), and the ink composition (n + 1th color, for example, the third color) to be ejected subsequently is preferably set to 1 second or less for the ejection (droplet ejection) interval to perform recording. be able to. In the present invention, the line method has an ejection interval of 1 second or less, and prevents hue and color mixing caused by interference between ink droplets, while at the same time increasing the speed and hue (drawing line and fineness in the image). An image excellent in the reproducibility of the portion can be obtained.

  The amount of ink droplets ejected from the inkjet head is preferably 0.5 to 6 pl (picoliter), more preferably 1 to 5 pl, and still more preferably 2 to 4 pl from the viewpoint of obtaining a high-definition image. .

-Treatment liquid application process-
In the treatment liquid application step, a treatment liquid containing a cationic organic compound and capable of forming an aggregate by contact with the ink composition is applied to the recording medium, and the treatment liquid is contacted with the ink composition to form an image. In this case, the self-dispersing polymer particles in the ink composition and the dispersed particles such as pigment particles in the case of containing a pigment as the coloring material aggregate to fix the image on the recording medium.
The treatment liquid contains at least a cationic organic compound and is configured to be capable of forming an aggregate when it comes into contact with the ink composition. Details and preferred embodiments of each component are as described above. .

  The treatment liquid can be applied by applying a known method such as a coating method, an ink jet method, or an immersion method. As a coating method, a known coating method using a bar coater, an extrusion die coater, an air doctor coater, a bread coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, a bar coater or the like can be used. The details of the inkjet method are as described above.

  The treatment liquid application step may be provided either before or after the ink application step using the ink composition.

  In the present invention, an embodiment in which the ink application step is provided after the treatment liquid is applied in the treatment liquid application step is preferable. That is, before applying the ink composition to the recording medium, a treatment liquid for aggregating the coloring material (preferably pigment) in the ink composition is applied in advance, and the treatment applied on the recording medium. An embodiment in which an ink composition is applied so as to come into contact with the liquid to form an image is preferable. Thereby, inkjet recording can be speeded up, and an image with high density and resolution can be obtained even at high speed recording.

The amount of treatment liquid applied is not particularly limited as long as the ink composition can be agglomerated, but the amount of the cationic organic compound applied can be preferably 0.1 g / m ² or more. Especially, the quantity from which the provision amount of a cationic organic compound will be 0.1-1.0 g / m < ² > is preferable, More preferably, it is 0.2-0.8 g / m < ² >. When the applied amount of the cationic organic compound is 0.1 g / m ² or more, good high-speed aggregation can be maintained even when a plurality of types of ink compositions are used. Moreover, it is preferable that the amount of the cationic organic compound applied is 1.0 g / m ² or less because gloss does not become too high.

  In the present invention, an ink application step is provided after the treatment liquid application step, and the treatment liquid on the recording medium is heated and dried after the treatment liquid is applied on the recording medium and before the ink composition is applied. It is preferable to further provide a heat drying step. By heating and drying the treatment liquid in advance before the ink application step, ink colorability such as bleeding prevention is improved, and a visible image with good color density and hue can be recorded.

  Heating and drying can be performed by known heating means such as a heater, air blowing means using air blowing such as a dryer, or a combination of these. As the heating method, for example, a method of applying heat with a heater or the like from the side opposite to the treatment liquid application surface of the recording medium, a method of applying warm air or hot air to the treatment liquid application surface of the recording medium, or an infrared heater was used. The heating method etc. are mentioned, You may heat combining these two or more.

-Recording media-
The inkjet recording method of the present invention records an image on a recording medium.
The recording medium is not particularly limited, and general printing paper mainly composed of cellulose, such as so-called high-quality paper, coated paper, and art paper, used for general offset printing and the like can be used. General printing paper mainly composed of cellulose is relatively slow in ink absorption and drying in image recording by a general ink jet method using water-based ink, and color material movement is likely to occur after droplet ejection, and image quality is likely to deteriorate. However, according to the ink jet recording method of the present invention, it is possible to record a high-quality image excellent in color density and hue by suppressing the movement of the color material.

  As the recording medium, commercially available media can be used. For example, “OK Prince fine quality” manufactured by Oji Paper Co., Ltd., “Shiorai” manufactured by Nippon Paper Industries Co., Ltd., and Nippon Paper Industries ( Fine coated paper such as “New NPI fine quality” manufactured by Co., Ltd., “OK Everlight Coat” manufactured by Oji Paper Co., Ltd., and “Aurora S” manufactured by Nippon Paper Industries Co., Ltd., Oji Lightweight coated paper (A3) such as “OK Coat L” manufactured by Paper Industries Co., Ltd. and “Aurora L” manufactured by Nippon Paper Industries Co., Ltd. “OK Top Coat +” manufactured by Oji Paper Co., Ltd. and Nippon Paper Industries Co., Ltd. ) Coated paper (A2, B2) such as “Aurora Coat” manufactured by Oji Paper Co., Ltd. Art paper (A1) such as “OK Kanfuji +” manufactured by Oji Paper Co., Ltd. and “Tokuhishi Art” manufactured by Mitsubishi Paper Industries Co., Ltd. Is mentioned. It is also possible to use various photographic papers for ink jet recording.

Among these, from the viewpoint of obtaining a high-quality image having a large color material movement suppression effect and better color density and hue than before, the water absorption coefficient Ka is preferably 0.05 to 0.5. a recording medium mL ^/ m 2 ^{· ms 1/2,} more preferably recording medium 0.1~0.4mL ^/ m 2 ^{· ms 1/2,} more preferably 0.2-0.3 ml / It is a recording medium of m ² · ms ^1/2 .

  The water absorption coefficient Ka is synonymous with that described in JAPAN TAPPI paper pulp test method No. 51: 2000 (issued by Japan Paper Pulp Technology Association). Specifically, the absorption coefficient Ka is an automatic scanning absorption meter. It is calculated from the difference in the amount of hand transfer of water between a contact time of 100 ms and a contact time of 900 ms using KM500Win (manufactured by Kumagai Riki Co., Ltd.).

  Among the recording media, so-called coated paper used for general offset printing is preferable. The coated paper is obtained by applying a coating material to the surface of high-quality paper, neutral paper, or the like that is mainly surface-treated with cellulose as a main component and is not surface-treated. The coated paper tends to cause quality problems such as image gloss and scratch resistance in image formation by ordinary aqueous inkjet, but in the inkjet recording method of the present invention, gloss unevenness is suppressed and gloss and resistance are reduced. An image having good rubbing properties can be obtained. In particular, it is preferable to use a coated paper having a base paper and a coat layer containing kaolin and / or calcium bicarbonate. More specifically, art paper, coated paper, lightweight coated paper, or finely coated paper is more preferable.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof. Unless otherwise specified, “part” is based on mass.

  The weight average molecular weight was measured by gel permeation chromatography (GPC). GPC uses HLC-8220GPC (manufactured by Tosoh Corporation), and as a column, TSKgeL SuperHZM-H, TSKgeL SuperHZ4000, TSKgel SuperHZ2000 (both trade names made by Tosoh Corporation) are connected in series. THF (tetrahydrofuran) was used as an eluent. The conditions were as follows: the sample concentration was 0.35 / min, the flow rate was 0.35 ml / min, the sample injection amount was 10 μl, the measurement temperature was 40 ° C., and an IR detector was used. In addition, the calibration curve is “standard sample TSK standard, polystyrene” manufactured by Tosoh Corporation: “F-40”, “F-20”, “F-4”, “F-1”, “A-5000”, It produced from eight samples of "A-2500", "A-1000", and "n-propylbenzene".

<Preparation of water-based ink>
(Synthesis of polymer dispersant P-1)
According to the following scheme, a polymer dispersant P-1 was synthesized as shown below.

To a 1000 ml three-necked flask equipped with a stirrer and a condenser tube, 88 g of methyl ethyl ketone was added and heated to 72 ° C. in a nitrogen atmosphere. Here, 50 g of methyl ethyl ketone was mixed with 0.85 g of dimethyl 2,2′-azobisisobutyrate and 60 g of benzyl methacrylate. Then, a solution in which 10 g of methacrylic acid and 30 g of methyl methacrylate were dissolved was dropped over 3 hours. After completion of the dropwise addition, the reaction was further continued for 1 hour, and then a solution of 0.42 g of dimethyl 2,2′-azobisisobutyrate in 2 g of methyl ethyl ketone was added, heated to 78 ° C. and heated for 4 hours. The obtained reaction solution was reprecipitated twice in a large excess of hexane, and the precipitated resin was dried to obtain 96 g of polymer dispersant P-1 (pigment dispersant).
The composition of the obtained resin was confirmed by ¹ H-NMR, and the weight average molecular weight (Mw) determined by GPC was 44,600. Furthermore, when the acid value was calculated | required by the method as described in JIS specification (JIS K0070: 1992), it was 65.2 mgKOH / g.

(Preparation of dispersion C of resin-coated pigment particles)
Pigment Blue 15: 3 (phthalocyanine blu-A220, manufactured by Dainichi Seika Co., Ltd .; cyan pigment), 5 parts of the polymer dispersant P-1, 42 parts of methyl ethyl ketone, and 1N aqueous NaOH solution 5.5 Part and 87.2 parts of ion-exchanged water were mixed and dispersed with a bead mill using 0.1 mmφ zirconia beads for 2 to 6 hours.
After removing methyl ethyl ketone at 55 ° C. under reduced pressure and removing a part of water in the obtained dispersion, using a high-speed centrifugal cooler 7550 (manufactured by Kubota Seisakusho), using a 50 mL centrifuge, Centrifugation was performed at 8000 rpm for 30 minutes, and the supernatant liquid other than the precipitate was collected. Thereafter, the pigment concentration was determined from the absorbance spectrum, and a dispersion C of resin-coated pigment particles (pigment coated with a polymer dispersant) having a pigment concentration of 10.2% by mass was obtained.

(Preparation of dispersion M of resin-coated pigment particles)
In the preparation of resin-coated pigment particle dispersion C, Pigment Red 122 (magenta pigment) was used instead of Pigment Blue 15: 3 (cyan pigment). In the same manner as in the preparation, a dispersion M of resin-coated pigment particles (pigment coated with a polymer dispersant) was prepared.

(Preparation of dispersion Y of resin-coated pigment particles)
In the preparation of Resin-coated pigment particle dispersion C, Pigment Yellow 74 (yellow pigment) was used instead of Pigment Blue 15: 3 (cyan pigment). In the same manner as in the preparation, a dispersion Y of resin-coated pigment particles (pigment coated with a polymer dispersant) was prepared.

(Preparation of dispersion K of resin-coated pigment particles)
Resin-coated pigment except that carbon black (NIPEX 160-IQ manufactured by Degussa) was used instead of Pigment Blue 15: 3 (cyan pigment) in the preparation of dispersion C of resin-coated pigment particles In the same manner as the preparation of the particle dispersion C, a dispersion K of resin-coated pigment particles (pigment coated with a polymer dispersant) was prepared.

(Preparation of self-dispersing polymer fine particles)
-Synthesis Example 1
360.0 g of methyl ethyl ketone was charged into a 2-liter three-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, and the temperature was raised to 75 ° C. While maintaining the temperature in the reaction vessel at 75 ° C., 180.0 g of phenoxyethyl acrylate, 162.0 g of methyl methacrylate, 18.0 g of acrylic acid, 72 g of methyl ethyl ketone, and “V-601” (manufactured by Wako Pure Chemical Industries, Ltd.) A mixed solution consisting of 44 g was added dropwise at a constant speed so that the addition was completed in 2 hours. After completion of the dropwise addition, a solution composed of 0.72 g of “V-601” and 36.0 g of methyl ethyl ketone was added thereto, stirred at 75 ° C. for 2 hours, and further a solution composed of 0.72 g of “V-601” and 36.0 g of isopropanol. And stirred at 75 ° C. for 2 hours. Thereafter, the temperature was raised to 85 ° C., and stirring was further continued for 2 hours to obtain a resin solution of a phenoxyethyl acrylate / methyl methacrylate / acrylic acid (= 50/45/5 [mass ratio]) copolymer.
The weight average molecular weight (Mw) of the obtained copolymer was 64000 (calculated in terms of polystyrene by gel permeation chromatography (GPC)), and the acid value was 38.9 mgKOH / g.

Next, 668.3 g of the obtained resin solution was weighed, 388.3 g of isopropanol and 145.7 ml of 1 mol / L NaOH aqueous solution were added thereto, and the temperature in the reaction vessel was raised to 80 ° C. Next, 720.1 g of distilled water was added dropwise at a rate of 20 ml / min to disperse in water. Thereafter, the temperature in the reaction vessel was maintained at 80 ° C. for 2 hours, 85 ° C. for 2 hours, and 90 ° C. for 2 hours under atmospheric pressure, and then the reaction vessel was depressurized, and isopropanol, methyl ethyl ketone, and distilled water totaled 913. 7 g was distilled off to obtain an aqueous dispersion (emulsion) of self-dispersing polymer fine particles B-01 having a solid content concentration of 28.0% by mass.
In addition, the structure of the self-dispersing polymer fine particle B-01 is as follows, and the number on the lower right of each structural unit in the structure below represents “mass ratio”.

In addition, the aqueous dispersion of the above self-dispersing polymer fine particles B-01 is appropriately diluted to a concentration suitable for measurement, and the dynamic dispersion is measured using an ultrafine particle size distribution analyzer Nanotrac UPA-EX150 (manufactured by Nikkiso Co., Ltd.). The volume average particle diameter was measured by a dynamic light scattering method. The measurement conditions were particle permeability: transmission, particle refractive index: 1.51, particle shape: non-spherical, density: 1.2 g / cm ³ , solvent: water, cell temperature: 18-25 ° C. The measurement results are shown in Table 1 below.

<Synthesis Example 2>
In the synthesis of the self-dispersing polymer fine particles (B-01) of Synthesis Example 1, instead of 180.0 g of phenoxyethyl acrylate, 162.0 g of methyl methacrylate, and 18.0 g of acrylic acid, the corresponding structural units and mass The self-dispersing polymer fine particles (B-02) to (B-05) shown below were prepared in the same manner as in Synthesis Example 1 except that the type of monomer used and the mixing amount thereof were changed so as to achieve the ratio. An aqueous dispersion (emulsion) was obtained.
The physical properties of the self-dispersing polymer fine particles (B-02) to (B-05) are shown in Table 1 below. In addition, the amount of 1 mol / L NaOH aqueous solution was adjusted so that the neutralization degree of these self-emulsifying polymers might be 0.75 mol equivalent with respect to 1 mol of dissociative groups.

<Synthesis Example 3>
Into a 1 liter three-necked flask equipped with a stirrer and a reflux condenser, 8.1 g of Pionein A-43s (manufactured by Takemoto Yushi Co., Ltd .; emulsifier) and 236.0 g of distilled water were added and heated and stirred at 70 ° C. in a nitrogen stream. To this, 6.2 g of styrene, 3.5 g of n-butyl acrylate, 0.3 g of acrylic acid, 1.0 g of ammonium persulfate, and 40 g of distilled water were added and stirred for 30 minutes, followed by 117.8 g of styrene and n-butyl acrylate. A monomer solution consisting of 66.5 g and 5.7 g of acrylic acid was added dropwise at a constant speed so that the addition was completed in 2 hours. After completion of the dropwise addition, an aqueous solution consisting of 0.5 g of ammonium persulfate and 20 g of distilled water was added and stirred at 70 ° C. for 4 hours, then heated to 85 ° C. and stirred for another 2 hours. The reaction liquid was cooled and filtered to obtain a dispersion of polymer fine particles (BH-1) having the following structure. The physical properties of the obtained polymer fine particles are shown in Table 1 below.

-Preparation of water-based ink-
Pigment particle dispersions obtained above (cyan dispersion C, magenta dispersion M, yellow dispersion Y, black dispersion K), self-dispersing polymer fine particles (B-01) to (B- Each component was mixed so that it might become the following ink composition using the dispersion of 05) and the dispersion of polymer microparticles | fine-particles (BH-1), and the aqueous ink was prepared. The obtained water-based ink was packed in a plastic disposable syringe and filtered through a polyvinylidene fluoride (PVDF) pore size 5 μm filter (Millex-SV manufactured by Millipore, diameter 25 mm) to obtain a finished ink.

(Composition of ink C-1)
Cyan pigment (Pigment Blue 15: 3): 4% by mass
-Polymer dispersant P-1: 2% by mass
-Aqueous dispersion of self-dispersing polymer fine particles B-01: 8% by mass
・ Sanix GP250: 10% by mass
(Sanyo Chemical Industries, hydrophilic organic solvent)
・ Diethylene glycol monoethyl ether: 5% by mass
(Wako Pure Chemical Industries, hydrophilic organic solvent)
・ Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd., surfactant): 1% by mass
・ Ion exchange water: 70% by mass

(Composition of ink C-2)
Cyan pigment (Pigment Blue 15: 3): 4% by mass
-Polymer dispersant P-1: 2% by mass
-Aqueous dispersion of self-dispersing polymer fine particles B-01: 8% by mass
・ Diethylene glycol monoethyl ether: 10% by mass
(Wako Pure Chemical Industries, hydrophilic organic solvent)
・ Glycerin (Wako Pure Chemical Industries, hydrophilic organic solvent): 20% by mass
・ Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd., surfactant): 1% by mass
・ Ion exchange water: 55% by mass

(Preparation of inks C-3 to C-8, ink M-1, ink Y-1, and ink K-1)
Ink C-1 was prepared in the same manner as ink C-1, except that the aqueous dispersion of cyan pigment and self-dispersing polymer fine particles B-01 was changed as shown in Table 2 below. C-3 to C-8, ink M-1, ink Y-1, and ink K-1 were prepared.

Table 3 shows the physical property values of the inks obtained above. Each physical property in Table 3 was measured by the following method.
-Surface tension: It measured at 25 degreeC by Wilhelmi method using a platinum plate using CBVP-Z by Kyowa Interface Science Co., Ltd.
・ Viscosity: Measured using a cone-plate (1 ° 34, φ35mm) at 25 ° C with a water-based ink as a stock solution by DV-II + VISCOMETER manufactured by BROOKFIELD, using a cone plate (1 ° 34, φ35mm), and the torque ranges from 20 to 95%. And the average value of the data in the range of 10 to 100 rpm was used as the measurement value.
-Number of coarse particles: Using a FPIA 3000 manufactured by Sysmex, the number of particles having a particle size of 5 μm or more was measured in a high-magnification unit LPF mode for a sample obtained by diluting a stock solution of water-based ink 5 times. / ΜL) was multiplied by 5 to determine the number of coarse particles.
PH: A pH meter WM-50EG manufactured by Toa DKK Co., Ltd. was used, and the aqueous ink was measured at 25 ° C. with the stock solution.
-Particle size: Nanotrack particle size distribution analyzer UPA-EX150 manufactured by Nikkiso Co., Ltd., diluted aqueous ink 50 to 1000 times with ion-exchanged water, 25 ° C, particle permeability: permeation, particle shape: Non-spherical, particle density: The volume average particle diameter Mv was measured under the condition of 1.2.
Particle size with time: The water-based ink was allowed to stand at 60 ° C. for 14 days in a sealed state, and then measured by the same method as the particle size.

<Preparation of treatment solution>
~ Processing liquid T-1 ~
The processing liquid T-1 was prepared by mixing each component so that it might become a composition of following Table 4.

~ Processing liquid T-2 ~
The treatment was performed in the same manner as in the treatment liquid T-1, except that the polybiguanide in the treatment liquid T-1 was changed to PAA-HCL-05 (allylamine hydrochloride polymer) manufactured by Nittobo Co., Ltd. Liquid T-2 was prepared.

~ Treatment liquid T-3
The same method as the treatment liquid T-1 except that the polybiguanide (4 mass%) in the treatment liquid T-1 was changed to PAA-HCL-05 (10 mass%) manufactured by Nittobo Co., Ltd. Thus, the treatment liquid T-3 was prepared.

<Image recording and evaluation>
A GELJET GX5000 printer head (full line head manufactured by Ricoh Co., Ltd.) was prepared, and the ink tanks C-1 to C-8, the ink M-1, the ink Y-1, and the ink K-1 obtained as described above for the storage tanks connected to this. Each was refilled. As a recording medium, Tokuhishi art double-sided N (water absorption coefficient Ka = 0.21 mL / m ² · ms ^1/2 ; manufactured by Mitsubishi Paper Industries Co., Ltd.) was prepared.

Then, the special diamond art both sides N are fixed on a stage that can move at a speed of 500 mm / second in a predetermined linear direction that is the sub-scanning direction during recording, and the processing solution obtained above is fixed to about 10 μm by a wire bar coater. It applied so that it might become the thickness of (cation polymer amount 0.4g / m < ² > equivalency), and it was made to dry at 50 degreeC for 2 second immediately after application | coating. Thereafter, the direction of the line head in which the nozzles are arranged (main scanning direction) is inclined by 75.7 ° with respect to the direction perpendicular to the moving direction of the stage (sub-scanning direction) on the same plane as the GELJET GX5000 printer head. In this case, while the recording medium is moved at a constant speed in the sub-scanning direction, the ink droplet amount is 2.8 pL, the discharge frequency is 24 kHz, the resolution is 1200 dpi × 1200 dpi, and the stage speed is 50 mm / s. A solid image was printed. Immediately after printing, the sample was dried at 60 ° C. for 3 seconds, passed between a pair of fixing rollers heated to 60 ° C., and subjected to a fixing process at a nip pressure of 0.25 MPa and a nip width of 4 mm to obtain an evaluation sample.
Subsequently, the stage moving speed is changed to 50 mm / s, 100 mm / s, and 250 mm / s, and ejection is performed under the conditions in which the ejection frequency is changed so that the droplet ejection amount is the same as described above. did.
The fixing roller is composed of a heating roll in which the surface of the core of a SUS cylindrical body with a halogen lamp inside is coated with a silicone resin, and an opposing roll that is in pressure contact with the heating roller. is there.

About the obtained evaluation sample, the degree of bleeding (interference between droplets) generated between the ink droplets due to the interference between the droplets by visually checking the uniformity of the image is visually observed, and high-speed cohesion is exhibited. The index to be evaluated. The agglomeration speed was evaluated at a stage speed at which no droplet ejection interference was observed. The evaluation results are shown in Table 5 below.
<Evaluation criteria>
A: No droplet ejection interference was observed at 500 mm / s.
○: No droplet ejection interference was observed at 250 mm / s.
Δ: No droplet ejection interference was observed at 100 mm / s.
X: No droplet ejection interference was observed at 50 mm / s.

  As shown in Table 5, all of the inks of the present invention had a high aggregation rate, and an image excellent in hue and drawing performance (reproducibility of fine lines and fine portions in the image) was obtained even by high-speed recording. . On the other hand, in the ink C-8 using fine polymer particles other than the self-dispersing polymer, the aggregation rate when the treatment liquid contacted was inferior.

Claims (8)

The ink composition, the absorption coefficient Ka of water is ^{0.05mL / m 2 · ms 1/2 ~0.5mL} / m 2 · ms 1/2 paint containing a colorant and a self-dispersing polymer particles An ink application step for directly applying the ink jet method to a recording medium made of craft paper;
A treatment liquid applying step of applying to the recording medium a treatment liquid containing a cationic organic compound and capable of forming an aggregate by contact with the ink composition;
An ink jet recording method comprising :
The ink jet recording method, wherein the self-dispersing polymer is a water-insoluble polymer including a hydrophilic constituent unit and a constituent unit derived from an aromatic group-containing monomer selected from phenoxyethyl (meth) acrylate and benzyl (meth) acrylate. .   The inkjet recording method according to claim 1, wherein the cationic organic compound is a cationic polymer.   The inkjet recording method according to claim 1, wherein the color material is a pigment.   The inkjet recording method according to any one of claims 1 to 3, wherein the colorant is a pigment coated with a polymer dispersant.   The inkjet recording method according to any one of claims 1 to 4, wherein the self-dispersing polymer has a carboxyl group and has an acid value of 25 to 100.   6. The self-dispersing polymer particles are synthesized in an organic solvent and prepared as a polymer dispersion in which part or all of the carboxyl groups are neutralized and water is a continuous phase. Inkjet recording method. Wherein the ink composition further ink jet recording method according to any one of claims 1 to 6 containing a hydrophilic organic solvent. The ink applying step, at least two of the ink composition, the droplet ejection interval between the ink composition ejected by a line system in one second or less, any of claims 1 to 7 for recording an image The ink jet recording method according to claim 1.