JP2011212938A - Inkjet image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method that improves glossiness of a printed matter, prevents blocking of the printed matter, and improves fixing offset when an image is recorded on a recording medium by an inkjet method.SOLUTION: The inkjet image forming method includes: a recording step for recording the image on the recording medium by the inkjet method using an ink composition containing coloring materials, a polymer particle having a film forming property, a water soluble organic solvent, and water; an applying step for applying a liquid containing a resin particle having a glass transition temperature onto the surface of a heated roller or the image, and a fixing step for bringing the heated roller into contact with the surface of the image. T°C, T°C, and T°C satisfy equation (1):T<T<T, wherein T°C is a minimum film forming temperature measured by mixing the polymer particle and the water soluble organic solvent contained in the ink composition, T°C is the surface temperature of the heated roller, and T°C is the glass transition temperature of the resin particle.

Description

  The present invention relates to an inkjet image forming method.

Inkjet technology has been applied as an image recording method for recording color images in the fields of office printers, home printers, and the like. In recent years, inkjet technology has been improved in mass printing and speeding up as a commercial printing machine. In the commercial printing, printed materials are stacked in a large amount and at a high speed in a paper discharge unit. Then, the ink (image) printed on the printed matter is in close contact with another stacked printed matter, and when these closely attached printed materials are separated, the ink is peeled off from the printed matter and adheres to the other printed matter (blocking). May occur.
In addition, in inkjet printing, there is a case where a fixing process using a fixing roller or the like is performed in order to improve the abrasion resistance, but there is an offset (fixing offset) at which the image portion on the recording medium is transferred to the fixing roller. It may occur.
Here, as a technique for suppressing this blocking, Patent Document 1 discloses that a liquid containing fine powder particles is attached on the paper surface. Patent Document 2 discloses that a resin film containing resin particles is applied to a recording surface to form a resin film. Patent Document 3 discloses that an ink is applied by applying and drying a fine particle-containing liquid.

JP-A-62-246730 JP 2004-50751 A JP 2009-220299 A

However, in each of the above technologies, no consideration has been given to reducing the fixing offset that occurs when fixing an inkjet image.
Furthermore, in each of the above technologies, no consideration has been given to improving the glossiness of the formed image. In particular, in the technology of forming a resin film on the recording surface as in Patent Document 2, the blocking suppression effect and glossiness are improved. Only very inadequate in terms of view can be obtained.
The present invention provides an image forming method in which, when an image is recorded on a recording medium by an ink jet method, the gloss of the printed material is good, blocking of the printed material is suppressed, and further, fixing offset is improved. With the goal.

In view of the above problems, the present inventors have conducted extensive research. As a result, (1) the relationship between the polymer particles contained in the inkjet ink composition and the organic solvent (minimum film-forming temperature), and (2) glass of resin particles applied to the image surface after inkjet to prevent blocking We focused on the relationship between the transition temperature and (3) the temperature of the heating roller in contact with these inks and resin particles. And when the said relationship was adjusted, the new knowledge which affects glossiness, blocking, fixing offset, etc. was discovered, and it came to solve the said problem. More specifically, the present invention relates to the following image forming method.
Item 1. A recording step of recording an image on a recording medium by an inkjet method using an ink composition containing a coloring material, a first polymer particle having film-forming properties, a water-soluble organic solvent, and water;
An applying step of applying a liquid containing second polymer particles having a glass transition temperature to the surface of the heating roller or the image;
A fixing step of bringing a heating roller into contact with the surface of the image,
_A minimum film-forming temperature T _A ° C measured by mixing the first polymer particles contained in the ink composition and the water-soluble organic solvent; a surface temperature T _B ° C of the heating roller; The glass transition temperature T _C ° _C of the polymer particles 2 is represented by the following formula (1):
T _A <T _B <T _C (1)
An inkjet image forming method characterized by satisfying the above.
Item 2. Item 2. The inkjet image forming method according to Item 1, wherein the applying step is a step of bringing a cloth material containing a liquid containing the second polymer particles into contact with a heating roller.
Item 3. Item 3. The inkjet image forming method according to Item 1 or 2, wherein the first polymer is a self-dispersing polymer.
Item 4. Item 4. The inkjet image forming method according to Item 3, wherein the self-dispersing polymer is a polymer including a hydrophilic structural unit and at least one structural unit derived from an alicyclic monomer.
Item 5. Item 5. The inkjet image forming method according to any one of Items 1 to 4, wherein the liquid is a nonvolatile solvent.
Item 6. Item 6. The inkjet image forming method according to any one of Items 1 to 5, wherein the second polymer particles are insoluble in water.
Item 7. Item 7. The inkjet image forming method according to any one of Items 1 to 6, wherein the second polymer particle is polymethyl (meth) acrylate.
Item 8. Wherein _{T A} is 20 to 70 ° C., the inkjet image forming method according to any one of claim 1 to 7.
Item 9. Wherein _{T B} is 40 to 100 ° C., an inkjet image forming method according to any one of claim 1-8.
Item 10. Wherein T _C is 80 ° C. or more, the inkjet image forming method according to any one of claim 1 to 9.

  According to the present invention, when an image is recorded on a recording medium by an inkjet method, the gloss of the printed matter is good, blocking of the printed matter can be suppressed, and further, the fixing offset can be improved. In addition, the abrasion resistance of the recorded image can be improved.

FIG. 1 is a diagram showing a schematic view of an apparatus during the fixing process of the present invention. FIG. 2 is a schematic diagram of an apparatus used in the inkjet image forming method of the present invention.

The image forming method of the present invention is a recording method in which an image is recorded on a recording medium by an ink jet method using an ink composition containing a coloring material, first polymer particles having film-forming properties, a water-soluble organic solvent, and water. And an applying step of applying a liquid containing second polymer particles having a glass transition temperature to the heating roller or the surface of the image, and a fixing step of bringing the heating roller into contact with the surface of the image, _A minimum film-forming temperature T _A ° C measured by mixing the first polymer particles contained in the composition and the water-soluble organic solvent, a surface temperature T _B ° C of the heating roller, and the second a glass transition temperature _{T C} ° C. of the polymer particles is characterized by satisfying the relational expression of _{T a <T B <T C} . Hereinafter, each process is explained in full detail.

1. Recording Step The recording step of the present invention is a step of recording an image on a recording medium by an ink jet method using an ink composition containing a coloring material, film-forming polymer particles, a water-soluble organic solvent, and water. .
(1) Ink composition The ink composition used in the present invention contains a coloring material, at least polymer particles having a film-forming property, a water-soluble organic solvent, and water.

(Coloring material)
The ink composition of the present invention contains at least one coloring material.
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, quinophthalone 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 color material 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 acid value of the polymer dispersant is preferably 100 mgKOH / g or less from the viewpoint of good aggregation when the treatment liquid comes into contact. Furthermore, the acid value is more preferably 25 to 100 mgKOH / g, and particularly preferably 30 to 90 mgKOH / g.

  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 colorant in the present invention preferably contains a pigment and a dispersant, more preferably contains an organic pigment and a polymer dispersant, and a polymer dispersion containing an organic pigment and a carboxyl group from the viewpoint of abrasion resistance and cohesiveness. It is particularly preferable to contain an agent.
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 cohesiveness, it is preferable that the acid value of the self-dispersing polymer particles described later 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 coloring material 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 what

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% by mass and more preferably 2 to 20% by mass with respect to the ink composition from the viewpoint of image density.

(Polymer particles having film-forming properties)
The ink composition of the present invention contains first polymer particles having film-forming properties (hereinafter also referred to as “film-forming polymer particles” or “polymer particles”). In the present invention, the film-forming property means that a film is formed by heating a polymer particle having a minimum film-forming temperature. In the present invention, even when the polymer particles are not formed alone, the film formation may be performed in the presence of a water-soluble solvent constituting the ink as described later.

  Examples of the film-forming polymer particles in the present invention include thermoplastic or modified acrylic, epoxy, polyurethane, polyether, polyamide, unsaturated polyester, phenol, silicone, or fluorine resins. , Polyvinyl resins such as vinyl chloride, vinyl acetate, polyvinyl alcohol or polyvinyl butyral, polyester resins such as alkyd resins and phthalic resins, melamine resins, melamine formaldehyde resins, aminoalkyd cocondensation resins, urea resins, urea resins, etc. And particles of resin having an anionic group such as an amino material or a copolymer or a mixture thereof. Among these, anionic acrylic resins include, for example, an acrylic monomer having an anionic group (anionic group-containing acrylic monomer) and, if necessary, other monomers copolymerizable with the anionic group-containing acrylic monomer. Obtained by polymerization in a solvent. Examples of the anionic group-containing acrylic monomer include an acrylic monomer having one or more selected from the group consisting of a carboxyl group, a sulfonic acid group, and a phosphonic group. Among them, an acrylic monomer having a carboxyl group (for example, acrylic acid) Methacrylic acid, crotonic acid, methacrylic acid, propylacrylic acid, isopropylacrylic acid, itaconic acid, fumaric acid, etc.) are preferred, and acrylic acid or methacrylic acid is particularly preferred.

  The film-forming polymer particles in the present invention are preferably self-dispersing polymer particles from the viewpoint of showing good film-forming properties and agglomeration without the influence of a dispersant, an emulsifier, etc., and self-dispersing polymer particles having a carboxyl group Is more preferable. Self-dispersing polymer particles are water-insoluble polymers that can be dispersed in an aqueous medium by the functional groups (particularly acidic groups or salts thereof) of the polymer itself in the absence of other surfactants, By means of water-insoluble polymer particles containing no free emulsifier.

Here, the dispersed state means both an emulsified state (emulsion) in which a water-insoluble polymer is dispersed in a liquid state in an aqueous medium, and a dispersed state (suspension) in which a water-insoluble polymer is dispersed in a solid state in an aqueous medium. It includes the state of.
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 rate and fixing property when a liquid composition is used.

  The dispersion state of the self-dispersing polymer particles in the present invention refers to a solution obtained by dissolving 30 g of a water-insoluble polymer in 70 g of an organic solvent (for example, methyl ethyl ketone), and a neutralizing agent capable of neutralizing 100% of the salt-forming group of the water-insoluble polymer. After mixing and stirring (apparatus: stirring apparatus with stirring blade, rotation speed 200 rpm, 30 minutes, 25 ° C.) (sodium hydroxide if the salt-forming group is anionic, acetic acid if cationic) and 200 g of water The state in which even after removing the organic solvent from the mixed solution, it can be visually confirmed that the dispersed 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 includes water, and may include a water-soluble organic solvent as necessary. In the present invention, it is preferably composed of water and 0.2% by mass or less of a water-soluble organic solvent, more preferably composed of water.

  The main chain skeleton of the resin constituting the polymer particles in the present invention is not particularly limited, and examples thereof include vinyl polymers, condensation polymers (epoxy resins, polyesters, polyurethanes, polyamides, celluloses, polyethers, polyureas, polyimides, polycarbonates, etc. ) Can be used. Among them, vinyl polymers are particularly preferable, and (meth) acrylic polymer particles are more preferable from the viewpoint of dispersion stability of polymer particles. The (meth) acrylic resin means a methacrylic resin and an acrylic resin.

  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, the thing of Unexamined-Japanese-Patent No. 2001-247787 can be mentioned.

  The self-dispersing polymer particles in the present invention include a hydrophilic constituent unit and at least one constituent unit derived from an alicyclic monomer as a hydrophobic constituent unit from the viewpoint of self-dispersibility, film-forming temperature, and the like. It is preferable to contain a water-insoluble polymer containing. The water-insoluble polymer may further contain a structural unit derived from an aromatic group-containing monomer.

  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. The hydrophilic group is preferably a dissociable group and more preferably an anionic dissociative 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 is preferably a dissociable group-containing monomer from the viewpoint of self-dispersibility and aggregability, and is preferably a dissociable group-containing monomer having a dissociable group and an ethylenically unsaturated bond. . 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, and dibutyl-2. -Acryloyloxyethyl phosphate and the like.
Among the dissociable group-containing monomers, an unsaturated carboxylic acid monomer is preferable from the viewpoint of dispersion stability and ejection stability, and at least one of acrylic acid and methacrylic acid is more preferable.

Examples of the monomer having a nonionic hydrophilic group include 2-methoxyethyl acrylate, 2- (2-methoxyethoxy) ethyl acrylate, 2- (2-methoxyethoxy) ethyl methacrylate, ethoxytriethylene glycol methacrylate, and methoxy. Ethylenically unsaturated monomers containing (poly) ethyleneoxy groups or polypropyleneoxy groups, such as polyethylene glycol (molecular weight 200-1000) monomethacrylate, polyethylene glycol (molecular weight 200-1000) monomethacrylate, hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate Rate, ethylenically unsaturated monomer having a hydroxyl group such as hydroxymethyl (meth) acrylate.
The monomer having a nonionic hydrophilic group is more stable in terms of particle stability and water-soluble component content than an ethylenically unsaturated monomer having a hydroxyl group at the end, and an ethylenically unsaturated monomer having an alkyl ether at the end. It is preferable from the viewpoint.

As the hydrophilic structural unit, an embodiment containing only a hydrophilic unit having an anionic dissociative group, and a hydrophilic structural unit having an anionic dissociative group and a hydrophilic having a nonionic hydrophilic group It is preferable that it is either of the aspects containing both of these structural units.
In addition, an embodiment containing two or more hydrophilic units having an anionic dissociable group, a hydrophilic constituent unit having an anionic dissociative group, and two hydrophilic constituent units having a nonionic hydrophilic group are provided. It is also preferable that more than one species be used in combination.

The content of the hydrophilic constituent unit in the self-dispersing polymer is preferably 25% by mass or less, more preferably 1 to 25% by mass, from the viewpoints of the viscosity and the temporal stability of the ink composition. The content is more preferably 2 to 23% by mass, and particularly preferably 4 to 20% by mass.
Moreover, when it has 2 or more types of hydrophilic structural units, it is preferable that the total content rate of a hydrophilic structural unit exists in the said range.

  The content of the structural unit having an anionic dissociable group in the self-dispersing polymer is preferably in a range where the acid value is in a suitable range described later. The content of the structural unit having a nonionic hydrophilic group is preferably 0 to 25% by mass, more preferably 0 to 20% by mass, from the viewpoint of ejection stability and stability over time, Particularly preferred is 0 to 15% by mass.

  The self-dispersing polymer particles preferably contain a polymer having a carboxyl group from the viewpoints of self-dispersibility and the aggregation rate when recording with the processing liquid described below when contacting with the processing liquid. It is more preferable to include a polymer having an acid value (mgKOH / g) of 25 to 100. Furthermore, the acid value is more preferably from 25 to 80, and particularly preferably from 30 to 65, from the viewpoints of self-dispersibility and the aggregation rate when contacted with the treatment liquid. 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 alicyclic monomer is not particularly limited as long as it is a compound containing an alicyclic hydrocarbon group and a polymerizable group, but from the viewpoint of dispersion stability, film-forming temperature, etc., an alicyclic (meth) acrylate It is preferable that
The alicyclic (meth) acrylate includes a structural part derived from (meth) acrylic acid and a structural part derived from alcohol, and the structural part derived from alcohol is unsubstituted or substituted. It has a structure containing at least one hydrocarbon group. The alicyclic hydrocarbon group may be a structural site derived from alcohol itself, or may be bonded to a structural site derived from alcohol via a linking group. The “alicyclic (meth) acrylate” means methacrylate or acrylate having an alicyclic hydrocarbon group.

The alicyclic hydrocarbon group is not particularly limited as long as it contains a cyclic non-aromatic hydrocarbon group, and is a monocyclic hydrocarbon group, a bicyclic hydrocarbon group, a tricyclic or more polycyclic group. A hydrocarbon group is mentioned. Examples of the alicyclic hydrocarbon group include a cycloalkyl group such as a cyclopentyl group and a cyclohexyl group, a cycloalkenyl group, a bicyclohexyl group, a norbornyl group, an isobornyl group, a dicyclopentanyl group, a dicyclopentenyl group, and an adamantyl group. , Decahydronaphthalenyl group, perhydrofluorenyl group, tricyclodecanyl group, and bicyclononane. The alicyclic hydrocarbon group may further have a substituent. Examples of the substituent include an alkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkoxy group, a hydroxyl group, a primary amino group, a secondary amino group, a tertiary amino group, an alkyl or arylcarbonyl group, and a cyano group. Is mentioned. Further, the alicyclic hydrocarbon group may further form a condensed ring.
As an alicyclic hydrocarbon group in this invention, it is preferable that carbon number of an alicyclic hydrocarbon group part is 5-20 from a viscosity or a soluble viewpoint.

  Examples of the linking group that connects the alicyclic hydrocarbon group and the structural portion derived from the alcohol include an alkylene group, an alkenylene group, an alkynylene group, an arylalkylene group, an oxyalkylene group, mono or oligo group having 1 to 20 carbon atoms. Suitable examples include ethyleneoxy group, mono- or oligopropyleneoxy, and the like.

Specific examples of the alicyclic (meth) acrylate are shown below, but the present invention is not limited thereto. These can be used alone or in admixture of two or more.
Monocyclic (meth) acrylates include cyclopropyl (meth) acrylate, cyclobutyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, cyclooctyl (meth) acrylate, and cyclononyl. Examples thereof include cycloalkyl (meth) acrylates having 3 to 10 carbon atoms in the cycloalkyl group such as (meth) acrylate and cyclodecyl (meth) acrylate. Examples of the bicyclic (meth) acrylate include isobornyl (meth) acrylate and norbornyl (meth) acrylate. Examples of the tricyclic (meth) acrylate include adamantyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and dicyclopentenyloxyethyl (meth) acrylate. Among these, from the viewpoints of dispersion stability, fixability, and blocking resistance of the self-dispersing polymer particles, at least one bicyclic (meth) acrylate or a tricyclic or higher polycyclic (meth) acrylate is used. Preferably, it is at least one selected from isobornyl (meth) acrylate, adamantyl (meth) acrylate, and dicyclopentanyl (meth) acrylate.

  In the present invention, the content of the structural unit derived from the alicyclic (meth) acrylate contained in the self-dispersing polymer particles is based on the stability of the self-dispersing state and the hydrophobic interaction between the alicyclic hydrocarbon groups. From the viewpoint of stabilizing the particle shape in an aqueous medium and reducing the amount of water-soluble components due to appropriate hydrophobicity of the particles, it is preferably 20% by mass or more and 90% by mass or less, and 40% by mass or more and 90% by mass or less. It is more preferable that Particularly preferred is 50 mass% or more and 80 mass% or less. Fixing property and blocking can be improved by making the structural unit derived from the alicyclic (meth) acrylate 20% by mass or more. On the other hand, the stability of the polymer particles is improved when the structural unit derived from the alicyclic (meth) acrylate is 90% by mass or less.

  Moreover, when it has a structural unit derived from an aromatic group-containing monomer, 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. From the viewpoint of particle shape stability in an aqueous medium, an addition polymerizable polymerizable group is preferable, and a group containing an ethylenically unsaturated bond is more preferable.

  The aromatic group-containing monomer 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 fixing property. Phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, and phenyl (meth) are preferred. At least one selected from acrylates is more preferable, and phenoxyethyl (meth) acrylate and benzyl (meth) acrylate are more preferable. Moreover, when using a styrene-type monomer as an aromatic group containing monomer, it is preferable that the structural unit derived from a styrene-type monomer is 20 mass% or less from a stability viewpoint at the time of setting it as a self-dispersion polymer particle. More preferably, the content is less than or equal to 5% by mass, still more preferably less than or equal to 5% by mass, and an embodiment that does not include a structural unit derived from a styrene monomer is particularly preferable. Here, the styrene monomer refers to styrene, substituted styrene (α-methylstyrene, chlorostyrene, etc.), and a styrene macromer having a polystyrene structural unit.

Self-dispersing polymer particles, for example, as a hydrophobic structural unit, in addition to the structural unit derived from the alicyclic monomer, in addition to the structural unit derived from the aromatic group-containing monomer, if necessary, other A structural unit may be further included. The monomer that forms other structural unit (hereinafter, also referred to as “other copolymerizable monomer”) can be copolymerized with the hydrophilic group-containing monomer, aromatic group-containing monomer, and alicyclic monomer. If it is a monomer, there will be no restriction | limiting in particular. 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; hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) Ethylenically unsaturated monomers having a hydroxyl group such as acrylate, 4-hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate, hydroxyhexyl (meth) acrylate; Dialkylaminoalkyl (meth) acrylates such as ru (meth) acrylate; N-hydroxyalkyl (meth) such as N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N-hydroxybutyl (meth) acrylamide Acrylamide; N-methoxymethyl (meth) acrylamide, N-ethoxymethyl (meth) acrylamide, N- (n-, iso) butoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, N-ethoxyethyl (meta And (meth) acrylamides such as N-alkoxyalkyl (meth) acrylamides such as acrylamide and N- (n-, iso) butoxyethyl (meth) acrylamide.

  Among these, (meth) acrylates containing a linear alkyl group having 1 to 8 carbon atoms from the viewpoint of flexibility of the polymer skeleton and ease of control of the glass transition temperature (Tg) and from the viewpoint of dispersion stability of the self-dispersing polymer. Preferably, it is a (meth) acrylate having a chain alkyl group having 1 to 4 carbon atoms, and particularly preferably methyl (meth) acrylate or ethyl (meth) acrylate. Here, the chain alkyl group refers to an alkyl group having a straight chain or a branched chain.

  Other copolymerizable monomers may be used singly or in combination of two or more. When the self-dispersing polymer particles contain other constituent units, the content is preferably 10 to 80% by mass, more preferably 15 to 75% by mass, and particularly preferably 20 to 70%. % By mass. When using the monomer which forms another structural unit in combination of 2 or more types, it is preferable that the total content is the said range.

  From the viewpoint of dispersion stability, the self-dispersing polymer in the present invention contains at least one alicyclic (meth) acrylate, another copolymerizable monomer containing an aromatic group-containing (meth) acrylate, and a hydrophilic group. It is also preferable that the polymer is obtained by polymerizing at least three types of monomers. At least one type of alicyclic (meth) acrylate, alkyl group-containing (meth) acrylate having 1 to 8 carbon atoms or a straight chain or branched chain And a polymer obtained by polymerizing at least three of the hydrophilic group-containing monomers. In the present invention, from the viewpoint of dispersion stability, substitution with a large hydrophobicity derived from a (meth) acrylate having a linear or branched alkyl group having 9 or more carbon atoms, an aromatic group-containing macromonomer or the like The content of the structural unit having a group is preferably substantially not contained, and more preferably not contained at all.

  The self-dispersing polymer may be a random copolymer in which each constituent unit is irregularly introduced, or a block copolymer that is regularly introduced. Each constitutional unit may be synthesized in any order of introduction, and the same constitutional component may be used twice or more, but a random copolymer is from the viewpoint of versatility and manufacturability. preferable.

  The molecular weight range of the self-dispersing polymer is preferably 3000 to 200,000 in terms of weight average molecular weight, more preferably 5000 to 150,000, and still more preferably 10,000 to 100,000. In addition, the acid value (mgKOH / g) is preferably 25 to 100 and the weight average molecular weight is preferably 3000 to 200,000, the acid value is 25 to 95 and the weight average molecular weight is 5000 to 150,000. More preferably. 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). GPC uses HLC-8020GPC (manufactured by Tosoh Corporation), TSKgel SuperHZM-H, TSKgel SuperHZ4000, TSKgel SuperHZ200 (4.6 mm ID × 15 cm, Tosoh Corporation) as columns and THF (tetrahydrofuran) as an eluent. Is used.

The self-dispersing polymer in the present invention is a structural unit derived from an alicyclic (meth) acrylate (preferably isobornyl (meth) acrylate, adamantyl (meth) acrylate, and dicyclopenta) from the viewpoint of controlling the hydrophilicity / hydrophobicity of the polymer. A structural unit derived from at least one of nyl (meth) acrylates) as a copolymerization ratio and containing 15 to 80% by mass of the total mass of the self-dispersing polymer particles, and having an acid value (mgKOH / g) of 25 to 100 and weight The average molecular weight is preferably 3000 to 200,000.
Self-dispersing polymers are structural units derived from alicyclic (meth) acrylates (preferably isobornyl (meth) acrylate, adamantyl (meth) acrylate, and dicyclopentanyl) from the viewpoint of controlling hydrophilicity / hydrophobicity of the polymer. A structural unit derived from a structural unit derived from at least one of (meth) acrylates) having a copolymerization ratio of 15 to 80% by mass, a structural unit derived from a carboxyl group-containing monomer, and a structure derived from an alkyl group-containing monomer Unit (preferably a structural unit derived from an alkyl ester of (meth) acrylic acid), and isobornyl (meth) acrylate, adamantyl (meth) acrylate, and dicyclopentanyl (meth) acrylate. Copolymerization ratio of structural units derived from at least one 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 derived from an alkyl ester of (meth) acrylic acid having 1 to 4 carbon atoms). It is more preferable that the acid value is 25 to 95 and the weight average molecular weight is 5000 to 150,000.

  In addition, the self-dispersing polymer of the present invention has a structure derived from an alicyclic (meth) acrylate (preferably isobornyl (meth) acrylate, adamantyl (meth) acrylate, and dicyclo) from the viewpoint of controlling the hydrophilicity / hydrophobicity of the polymer. A structural unit derived from at least one of pentanyl (meth) acrylate) having a copolymerization ratio of 20% by mass to 90% by mass, a structure derived from a dissociable group-containing monomer, and a chain having 1 to 8 carbon atoms At least one structure derived from a (meth) acrylate containing an alkyl group, an acid value (mgKOH / g) of 20 to 120, and a total content of hydrophilic structural units of 25% by mass or less. A vinyl polymer having a weight average molecular weight of 3000 to 200,000 is also preferable. Furthermore, a structure derived from a bicyclic or tricyclic or higher polycyclic (meth) acrylate (preferably at least one of isobornyl (meth) acrylate, adamantyl (meth) acrylate, and dicyclopentanyl (meth) acrylate) A structural unit derived from (meth) acrylate containing a chain alkyl group having 1 to 4 carbon atoms and a copolymerization ratio of 10 to 10 as a copolymerization ratio. 80% by mass and a structure derived from a carboxyl group-containing monomer having an acid value in the range of 25 to 100, the total content of hydrophilic structural units being 25% by mass or less, and a weight average molecular weight of 10,000 to 200,000 More preferred is a vinyl polymer. Furthermore, a structure derived from a bicyclic or tricyclic or higher polycyclic (meth) acrylate (preferably at least one of isobornyl (meth) acrylate, adamantyl (meth) acrylate, and dicyclopentanyl (meth) acrylate) A structural unit derived from one) as a copolymerization ratio of 40 mass% to 80 mass%, and at least a structure derived from methyl (meth) acrylate or ethyl (meth) acrylate as a copolymerization ratio of 20 to 70 mass%, A vinyl polymer containing a structure derived from acrylic acid or methacrylic acid in an acid value range of 30 to 80, a total content of hydrophilic structural units of 25% by mass or less, and a weight average molecular weight of 30,000 to 150,000 It is particularly preferred that

  Hereinafter, specific examples of the polymer constituting the polymer particles include alicyclic group-containing polymers, but the present invention is not limited thereto. The values in parentheses represent the mass ratio of the copolymer component. Further, when the glass transition temperature is “calculation Tg”, it is a value calculated by using the Tg value of the homopolymer of each of the following monomers according to the calculation formula (S) described later [Tg = methyl methacrylate: 105 ° C., Isobornyl methacrylate: 156 ° C., benzyl methacrylate: 54 ° C., methacrylic acid: 130 ° C., adamantyl methacrylate: 140 ° C., dicyclopentanyl methacrylate: 128 ° C.].

Methyl methacrylate / isobornyl methacrylate / methacrylic acid copolymer (20/72/8), Tg 180 ° C.
Methyl methacrylate / isobornyl methacrylate / methacrylic acid copolymer (30/62/8), Tg 170 ° C.
Methyl methacrylate / isobornyl methacrylate / methacrylic acid copolymer (40/52/8), Tg 160 ° C.
Methyl methacrylate / isobornyl methacrylate / methacrylic acid copolymer (50/42/8), Tg 150 ° C.
Methyl methacrylate / isobornyl methacrylate / benzyl methacrylate / methacrylic acid copolymer (30/50/14/6), Tg 123 ° C.
Methyl methacrylate / dicyclopentanyl methacrylate / methacrylic acid copolymer (40/50/10), Tg 130 ° C.
Methyl methacrylate / dicyclopentanyl methacrylate / phenoxyethyl methacrylate / methacrylic acid copolymer (30/50/14/6), Tg 101 ° C.
Methyl methacrylate / isobornyl methacrylate / methoxypolyethylene glycol methacrylate (n = 2) / methacrylic acid copolymer (30/54/10/6), Tg 110 ° C.
Methyl methacrylate / dicyclopentanyl methacrylate / methoxypolyethylene glycol methacrylate (n = 2) / methacrylic acid copolymer (54/35/5/6), Tg 100 ° C.
Methyl methacrylate / adamantyl methacrylate / methoxypolyethylene glycol methacrylate (n = 23) / methacrylic acid copolymer (30/50/15/5), Tg 112 ° C.
Methyl methacrylate / isobornyl methacrylate / dicyclopentanyl methacrylate / methacrylic acid copolymer (20/50/22/8), Tg 139 ° C.
Ethyl methacrylate / cyclohexyl methacrylate / acrylic acid copolymer (50/45/5), Tg 67 ° C
Isobutyl methacrylate / cyclohexyl methacrylate / acrylic acid copolymer (40/50/10), Tg 70 ° C.
N-butyl methacrylate / cyclohexyl methacrylate / styrene / acrylic acid copolymer (30/55/10/5), Tg 86 ° C.
・ Methyl methacrylate / dicyclopentenyloxyethyl methacrylate / methacrylic acid copolymer (40/52/8), Tg 78 ° C.
-Lauryl methacrylate / dicyclopentenyloxyethyl methacrylate / methacrylic acid copolymer (3/87/10), Tg 53 ° C.

  The method for producing the water-insoluble polymer constituting the self-dispersing polymer particles in the present invention is not particularly limited. For example, emulsion polymerization is carried out in the presence of a polymerizable surfactant to obtain a surfactant and a water-insoluble polymer. Examples include a method of covalent bonding, and a method of copolymerizing a 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 particles in the present invention include a polymer synthesized in an organic solvent from the viewpoint of aggregation rate, and the polymer has a carboxyl group (preferably having an acid value of 20 to 100). Part or all of the carboxyl groups of the polymer are preferably neutralized and prepared as a polymer dispersion having water as a continuous phase. 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 film-forming polymer particles (particularly self-dispersing polymer particles) is preferably in the range of 10 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. Especially preferably, it is the range of 10-50 nm. Manufacturability is improved by having an average particle diameter of 10 nm or more. Moreover, storage stability improves by setting it as an average particle diameter of 400 nm or less. Further, the particle size distribution of the film-forming 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 film-forming polymer particles are measured by a dynamic light scattering method using a nanotrack particle size distribution analyzer UPA-EX150 (manufactured by Nikkiso Co., Ltd.). Is required.

The content of the film-forming polymer particles (particularly self-dispersing polymer particles) in the ink composition is 1 to 20% by mass in terms of solid content with respect to the ink composition from the viewpoint of glossiness of the image. It is preferable and it is more preferable that it is 2-10 mass%.
The film-forming polymer particles (particularly self-dispersing polymer particles) can be used singly or in combination of two or more.

(Water-soluble organic solvent)
The ink composition contains water as a solvent and contains at least one water-soluble organic solvent. By containing this water-soluble organic solvent together with the film-forming polymer particles, the minimum film-forming temperature of the polymer particles in the ink composition can be lowered, and the fixing effect can be obtained more effectively, and the glossiness of the image In addition, the abrasion resistance and the like can be kept good.

  As the water-soluble organic solvent constituting the ink composition, alkyleneoxy alcohol and alkyleneoxyalkyl ether are preferable from the viewpoint that the minimum film-forming temperature can be suitably adjusted within a range lower than the surface temperature of the heating roller. For the same reason, the ink composition preferably contains two or more water-soluble organic solvents, and when it contains two or more water-soluble organic solvents, at least one of them is an alkyleneoxy alcohol. Further, it is particularly preferable to contain two or more water-soluble organic solvents containing at least one alkyleneoxy alcohol and at least one alkyleneoxyalkyl ether.

  The alkyleneoxy alcohol is preferably propyleneoxy alcohol. Examples of the propylene oxyalcohol include Sannix GP250 and Sannix GP400 (manufactured by Sanyo Chemical Industries, Ltd.).

  The alkyleneoxyalkyl ether is preferably ethyleneoxyalkyl ether having 1 to 4 carbon atoms in the alkyl moiety or propyleneoxyalkyl ether having 1 to 4 carbon atoms in the alkyl moiety. Examples of the alkylene oxyalkyl ether include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 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, tripropylene glycol monoethyl ether, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, ethylene glycol monophenyl ether, etc. That.

  In the present invention, the film-forming polymer particles are self-dispersing polymer particles, and the water-soluble organic solvent is propyleneoxyalcohol and ethyleneoxyalkyl ether (carbon number of 1 to 4 in the alkyl moiety) and / or propyleneoxyalkyl ether. The case where it is (C1-C4 of an alkyl part) is preferable. Furthermore, the polymer particles are self-dispersing polymer particles including a water-insoluble polymer including a hydrophilic structural unit and a structural unit derived from an alicyclic group-containing monomer, wherein the water-soluble organic solvent is propyleneoxyalcohol and The case of ethyleneoxyalkyl ether (C1-C4 of alkyl part) and / or propyleneoxyalkyl ether (C1-C4 of alkyl part) is preferable.

In addition to the above water-soluble organic solvent, other organic solvents may be contained as necessary for the purpose of preventing drying, promoting penetration, adjusting viscosity, and the like.
When an organic solvent is used as an anti-drying agent, it is possible to effectively prevent nozzle clogging that may occur due to drying of the ink at the ink discharge port when the ink composition is discharged by an inkjet method to record an image. it can.
In order to prevent drying, a water-soluble organic solvent having a vapor pressure lower than that of water is preferable. Specific examples of water-soluble organic solvents suitable for preventing drying include ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, thiodiglycol, dithiodiglycol, 2-methyl-1,3-propanediol, 1,2 , 6-hexanetriol, acetylene glycol derivatives, polyhydric alcohols represented by glycerin, trimethylolpropane, etc., 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N -Heterocycles such as ethylmorpholine, sulfur-containing compounds such as sulfolane, dimethyl sulfoxide and 3-sulfolene, polyfunctional compounds such as diacetone alcohol and diethanolamine, and urea derivatives. Of these, polyhydric alcohols such as glycerin and diethylene glycol are preferred.
In order to promote penetration, an organic solvent may be used for the purpose of better penetrating the ink composition into the recording medium. Specific examples of organic solvents suitable for promoting penetration include alcohols such as ethanol, isopropanol, butanol and 1,2-hexanediol, sodium lauryl sulfate, sodium oleate, and nonionic surfactants.
In addition to the above, the water-soluble organic solvent can be used for adjusting the viscosity. Specific examples of water-soluble organic solvents that can be used to adjust the viscosity include alcohols (eg, methanol, ethanol, propanol, etc.), amines (eg, ethanolamine, diethanolamine, triethanolamine, ethylenediamine, diethylenetriamine, etc.) And other polar solvents (for example, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, sulfolane, 2-pyrrolidone, acetonitrile, acetone, etc.).
The content of the water-soluble organic solvent in the ink composition is preferably 1 to 30% by mass, more preferably 5 to 25% by mass, and still more preferably 10 to 20% by mass.

(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.

(Minimum film-forming temperature T _A )
The minimum film formation temperature in the ink composition of the present invention (T _A), a minimum film-forming temperature in the mixed solution obtained by mixing the water-soluble organic solvent and the polymer particles contained in the ink composition is there. In particular, in the present invention, the minimum film-forming temperature (hereinafter referred to as “the ratio of the film-forming polymer particles and the water-soluble organic solvent in the ink composition” is 40 parts by mass with respect to 100 parts by mass of the former. MFT ^40% ").

Specifically, an aqueous solution of 25 parts by mass of film-forming polymer particles, 10 parts by mass of a water-soluble organic solvent, and 65 parts by mass of water is prepared, and the thickness of the coating film on the support is 300 μm. After coating with a blade with a length of 50 cm and a width of 3 cm, the coating film was heated from the back side to apply a temperature gradient from 20 ° C. to 74 ° C. for 4 hours in an environment of 20 ° C. and 22% RH. After drying, the value is calculated by measuring the boundary between a non-film-formed part where a white powdery precipitate is formed and a film-formed part where a transparent film is formed.
The minimum film-forming temperature is lower than the surface temperature of a heating roller (described later). Thereby, the glossiness, abrasion resistance, and the like of the image can be improved. For example, it is preferably 70 ° C. or lower, more preferably 65 ° C. or lower, and further preferably 60 ° C. or lower. Although a minimum is not limited, For example, it is 20 degreeC or more, More preferably, it is 30 degreeC or more, More preferably, it is 40 degreeC or more.

In the present invention, the minimum film-forming temperature is the composition of the film-forming polymer particles (for example, the content of each monomer such as the alicyclic (meth) acrylate), the film-forming polymer particles and the water-soluble organic solvent. Therefore, the minimum film-forming temperature (MFT ^40% ) can be adjusted by appropriately adjusting these ratios and the like.

In the present invention, as a result of paying attention to the above-mentioned minimum film forming temperature (MFT ^40% ), a specific ink composition having the minimum film forming temperature is used, and fixing is performed with a heating roller higher than the minimum film forming temperature. As a result, it has been found that the film-forming polymer particles are effectively formed to exhibit the effect of improving the glossiness and abrasion resistance of the image.

  This is because a part of the water-soluble organic solvent contained in the ink composition after the specific ink composition is jetted onto the recording medium by the ink jet method and fixed by the heating roller is recorded on the recording medium. Penetrate inside. As a result, the image formed on the surface of the recording medium contains the solid content in the ink and the remainder of the water-soluble organic solvent, and the content ratio is about 40 parts by mass of the latter with respect to 100 parts by mass of the former. . Then, a fixing process is performed with a heating roller. In the fixing process, if the fixing temperature is higher than the film forming temperature of the ink composition at that concentration, it is presumed that the image is sufficiently formed and the effect of improving the glossiness and abrasion resistance of the image is exhibited. Is done.

(Other additives)
In addition to the above components, the ink composition can contain other additives as necessary. Other additives include, for example, waxes, ultraviolet absorbers, antifading agents, emulsion stabilizers, penetration enhancers, antiseptics, antifungal agents, pH adjusting agents, surface tension adjusting agents, antifoaming agents, viscosity adjusting agents. , Known additives such as dispersants, dispersion stabilizers, rust inhibitors and chelating agents. These various additives may be added directly after the ink composition is prepared, or may be added when the ink composition is prepared.

  As the wax, for example, wax particles having a temperature of 40 ° C. or higher and lower than 100 ° C. can be suitably used. By including the wax, the press blocking resistance of the image can be improved.

Examples of the wax of the wax particles include natural wax and synthetic wax.
Examples of natural waxes include petroleum-derived waxes (petroleum-based waxes), plant-derived waxes (plant-based waxes), and animal and plant-derived waxes.
Examples of petroleum-derived wax include paraffin wax, microcrystalline wax, and petrolatum; plant-derived wax includes carnauba wax, candelilla wax, rice wax, and wood wax; and animal plant-derived wax includes lanolin and beeswax. be able to.
Synthetic waxes include synthetic hydrocarbon waxes and modified waxes.
Examples of synthetic hydrocarbon waxes include polyethylene wax and Fischer-Tropsch wax, and examples of modified wax systems include paraffin wax derivatives, montan wax derivatives, and microcrystalline wax derivatives.

The wax in the present invention may be contained in the ink composition by any method such as a solution form dissolved in an appropriate solvent, an emulsified dispersion form, and a solid fine particle dispersion form.
Particularly preferred is the emulsification dispersion method, and it is preferable to add fine particles having an average particle size of 0.01 μm to 10 μm, preferably 0.05 μm to 5 μm, more preferably 0.1 μm to 2 μm.

  The wax preferably has a wax solid content concentration of 0.001 to 20% by mass in the ink composition from the viewpoint of improvement in abrasion resistance, press blocking resistance and ink ejection properties (immediately, after aging). More preferably, the content is 0.01 to 10% by mass. More preferably, it is 0.1-5 mass%.

  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
, The same No. 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 is measured under conditions of 25 ° C. by the plate method 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.

<Ink set>
In addition to the ink composition of the present invention described, the ink jet image forming method of the present invention may be used in combination with a treatment liquid capable of forming an aggregate by contact with the ink composition. In the present invention, an ink set includes the ink composition of the present invention described above and the treatment liquid.

-Treatment liquid-
The treatment liquid in the present invention is configured to be able to form an aggregate by contact with the ink composition described above. Specifically, the treatment liquid preferably includes at least an aggregating component capable of aggregating dispersed particles such as coloring material particles (pigments, etc.) in the ink composition to form an agglomerate. It can comprise using the component of. 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).

(Aggregating component)
The treatment liquid can contain at least one aggregation component capable of forming an aggregate upon contact with the ink composition. By mixing the treatment liquid with the ink composition ejected by the ink jet method, aggregation of pigments and the like stably dispersed in the ink composition is promoted.

Examples of the treatment liquid include a liquid capable of generating an aggregate by changing the pH of the ink composition. At this time, the pH (25 ° C.) of the treatment liquid is preferably 1 to 6, more preferably 1.2 to 5, and preferably 1.5 to 4 from the viewpoint of the aggregation rate of the ink composition. More preferably it is. In this case, the pH (25 ° C.) of the ink composition used in the ejection step is preferably 7.5 to 9.5 (more preferably 8.0 to 9.0).
Among these, in the present invention, from the viewpoint of image density, resolution, and speedup of inkjet recording, the pH (25 ° C.) of the ink composition is 7.5 or more, and the pH (25 ° C.) of the treatment liquid is. The case of 1.5-3 is preferable.
The aggregating components can be used alone or in combination of two or more.

  The treatment liquid can be configured using at least one acidic compound as an aggregation component. 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) may be used. it can. Among these, from the viewpoint of the aggregation rate of the ink composition, a compound having a phosphate group or a carboxyl group is more preferable, and a compound having a carboxyl group is still more preferable.

  The compound having a carboxyl group includes polyacrylic acid, acetic acid, glycolic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid, tartaric acid, lactic acid, sulfonic acid, orthophosphoric acid. , Pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, derivatives of these compounds, or salts thereof (for example, polyvalent metal salts), etc. It is preferable to be selected from among These compounds may be used alone or in combination of two or more.

The treatment liquid in the present invention can be configured to further contain an aqueous solvent (for example, water) in addition to the acidic compound and the like.
As content in the processing liquid of an acidic compound, it is preferable that it is 5-95 mass% with respect to the total mass of a processing liquid from a viewpoint of the aggregation effect, and it is more preferable that it is 10-80 mass%. More preferably, it is 15-50 mass%.

  Moreover, the process liquid which added the polyvalent metal salt is mentioned, and high-speed aggregation property can be improved. Examples of the polyvalent metal salt include alkaline earth metals belonging to Group 2 of the periodic table (eg, magnesium, calcium), transition metals belonging to Group 3 of the periodic table (eg, lanthanum), and cations from Group 13 of the periodic table. (For example, aluminum) and salts of lanthanides (for example, neodymium). As the metal salt, carboxylate (formic acid, acetic acid, benzoate, etc.), nitrate, chloride, and thiocyanate are suitable. Among them, preferred are calcium salts or magnesium salts of carboxylic acids (formic acid, acetic acid, benzoates, etc.), calcium salts or magnesium salts of nitric acid, calcium chloride, magnesium chloride, and calcium salts or magnesium salts of thiocyanic acid.

  The content of the metal salt in the treatment liquid is preferably 1 to 10% by mass, more preferably 1.5 to 7% by mass, and still more preferably 2 to 6% by mass from the viewpoint of the aggregation effect. It is.

  Moreover, a process liquid can be comprised using at least 1 sort (s) of a cationic organic compound as an aggregation component. Examples of the cationic organic compound include poly (vinyl pyridine) salt, polyalkylaminoethyl acrylate, polyalkylaminoethyl methacrylate, poly (vinyl imidazole), polyethyleneimine, polybiguanide, polyguanide, and polyallylamine and derivatives thereof. Mention may be made of cationic polymers.

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. The weight average molecular weight is
When it 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. Cationic compounds, for example, amino acid type amphoteric surfactants, carboxylate type amphoteric surfactants (eg stearyl dimethyl betaine, lauryl dihydroxyethyl betaine, etc.), sulfate ester type, sulfonic acid type, or phosphate ester type And amphoteric surfactants that exhibit a cationic property in a desired pH range.
Of these, divalent or higher cationic organic compounds are preferred.

  As content in the processing liquid of a cationic organic compound, 1-50 mass% is preferable from a viewpoint of the aggregation effect, More preferably, it is 2-30 mass%.

  Among the above, the aggregating component is preferably a divalent or higher carboxylic acid or a divalent or higher cationic organic compound from the viewpoint of aggregability and image scratch resistance.

(Other ingredients)
The treatment liquid in the present invention can generally contain a water-soluble organic solvent in addition to the aggregating component, and can be constituted using other various additives within a range not impairing the effects of the present invention. 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.
In addition, surface tension is Automatic Surface Tensiometer C
It is measured under conditions of 25 ° C. using BVP-Z (manufactured by Kyowa Interface Science Co., Ltd.).

<Recording process>
The recording step in the present invention is a step of recording an image on the recording medium by the ink jet method using the ink composition of the present invention described above on the recording medium. If necessary, a treatment liquid application step for applying a treatment liquid capable of forming an aggregate by contacting the ink composition to the recording medium may be provided. The recording process in the present invention can be constituted by providing other processes as required.

  In this step, the ink composition can be selectively applied onto the recording medium, and a desired visible image can be formed. Details of each component in the ink composition of the present invention and details such as 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. Sho 54-59936 causes an abrupt volume change of the ink subjected to the action of thermal energy, and the ink is ejected from the nozzle by the action force due to 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 ink jet 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. Further, (2) there is a method of forcibly ejecting ink droplets from the nozzles 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 simultaneously applying pressure and a print information signal to the ink liquid by a piezoelectric element, ejecting ink droplets from the nozzles toward the recording medium, and recording an image on the recording medium (piezo), (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 recording process according to the present invention, in the case of the line method, not only one type of ink composition but also two or more types of ink compositions are used, and an ink composition (nth color (nth ≧ 1), for example, the second color) and the ejection (droplet ejection) interval between the ink composition (n + 1th color, for example, third color) to be ejected subsequently is preferably set to 1 second or less to perform recording. Can do. In the present invention, an ejection interval of 1 second or less in the line method prevents bleeding and color mixing between ink droplets, and has excellent scratch resistance under high-speed recording higher than that of the prior art, and occurrence of blocking. A suppressed image can be obtained. In addition, an image having excellent hue and drawability (reproducibility of fine lines and fine portions in the image) 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 present invention, a treatment liquid application step may be provided before or after the recording step.
In the treatment liquid application step, a treatment liquid 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, dispersed particles such as polymer particles and color materials (for example, pigments) in the ink composition aggregate to fix the image on the recording medium. The details and preferred embodiments of each component in the treatment liquid 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 blade coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater or the like can be used. The details of the inkjet method are as described above.

  In the present invention, an embodiment in which a recording 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 application amount of the treatment liquid is not particularly limited as long as the ink composition can be aggregated, but preferably, the application amount of the aggregation component (for example, a divalent or higher carboxylic acid or a cationic organic compound) is 0.1 g. / M ² or more. Especially, the quantity from which the provision amount of an aggregation component will be 0.1-1.0 g / m < ² > is preferable, More preferably, it is 0.2-0.8 g / m < ² >. When the amount of the aggregating component is 0.1 g / m ² or more, the agglomeration reaction proceeds favorably, and when it is 1.0 g / m ² or less, the glossiness is not excessively increased.

  In the present invention, a recording 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 recording step, ink coloring properties such as prevention of bleeding are improved, and a visible image having a 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.

2. Application Step The application step of the present invention is a step of applying a liquid containing resin particles having a glass transition temperature to the heating roller or the surface of the image. That is, it may be a method in which the resin particle-containing liquid is applied to the heating roller, and the resin particles are applied to the surface of the image through the heating roller having the resin particles applied to the surface (first aspect). The resin particle-containing liquid may be directly applied to the surface of the image (second aspect).

(Resin particle-containing liquid)
The second polymer particles (hereinafter also referred to as “resin particles”) having a glass transition temperature used for the resin particle-containing liquid can suppress blocking and have a glass transition temperature higher than the surface temperature of the heating roller. The resin particles are not limited.
It is essential that the lower limit of the glass transition temperature is higher than the surface temperature of the heating roller. Thereby, it exists as a particle on an image after fixing, and adhesion between images is suppressed, and a blocking improvement effect is exhibited. For example, it is 80 ° C. or higher, preferably 90 ° C. or higher, more preferably 100 ° C. or higher. The upper limit is not particularly limited.
Here, the measurement Tg obtained by actual measurement is applied as the glass transition temperature (Tg) in the present invention. Specifically, the measurement Tg means a value measured under normal measurement conditions using a differential scanning calorimeter (DSC) EXSTAR 6220 manufactured by SII Nanotechnology.

However, when measurement is difficult due to decomposition of the resin particles or the like, a calculated value Tg calculated by the following calculation formula (S) is applied.
1 / Tg = Σ (X _i / Tg _i ) (S)
Here, it is assumed that the resin particles to be calculated are copolymerized with n types of monomer components from i = 1 to n. X _i is the weight fraction of the i-th monomer (ΣX _i = 1), and Tg _i is the glass transition temperature (absolute temperature) of the homopolymer of the i-th resin. However, Σ is the sum from i = 1 to n. Incidentally, adopting the value of a homopolymer glass transition temperature values of each resin (Tg _i) the Polymer Handbook (3rd Edition) (J.Brandrup , EHImmergut al (Wiley-Interscience, 1989)) .

The resin particles may be either poorly water-soluble or water-insoluble, but are preferably water-insoluble in the present invention. As a result, when the resin particles are applied onto the recorded image, the resin particles dissolve or permeate inside the recorded image, thereby eliminating the blocking suppression effect and preventing the occurrence of unevenness on the recorded image surface. Can do. In the present invention, water-insoluble means that the amount dissolved in 100 parts by mass (25 ° C.) of water is 5.0 parts by mass or less. The liquid contained in the resin particles of the present invention is preferably in a dispersed state, that is, a resin particle dispersion.
Examples of such resin particles include polymethyl (meth) acrylate, polystyrene, polyester, and the like. Among these, polymethyl (meth) acrylate is preferable from the viewpoint of blocking inhibition and the like. Polymethyl (meth) acrylate means at least one of polymethyl acrylate and polymethyl methacrylate (PMMA).

  The volume average particle diameter of the resin particles is usually 0.05 μm or more and 20.0 μm or less, preferably 2 μm or more and 15 μm or less, more preferably 4 μm or more and 12 μm or less. The volume average particle diameter of the present invention is a value measured by a nanotrack particle size distribution measuring apparatus UPA-EX150 (manufactured by Nikkiso Co., Ltd.). The measurement can be performed by adding 10 ml of ion-exchanged water to 100 μl of a 20% by mass resin particle aqueous dispersion to prepare a sample solution for measurement, and adjusting the temperature to 25 ° C.

Although the content of the resin particles to be contained in the liquid is not limited, for example, it may be about 1 to 50% by mass, preferably about 5 to 40% by mass with respect to the total amount of the resin particle-containing liquid.
The liquid used for the resin particle-containing liquid may be any liquid that can disperse the resin particles. In the present invention, it is preferable to use a non-volatile solvent. The non-volatile solvent in the present invention refers to a solvent that does not boil at 150 ° C. or less at 1 atmosphere. Examples of such liquids include silicone oils such as dimethyl silicone oil, fluorine oil, fluorosilicone oil, and amino-modified silicone oil, or fluorine-based oils; liquid paraffin, and the like. Among these, silicone oil or fluorine-based oil is preferable from the viewpoint of forming a uniform release agent layer on the heating roller surface layer and easily transferring the resin particles to the surface of the recording image.

  Examples of these liquids include “KF-96-10cs”, “KF-96-20cs, KF-96-30cs”, “KF-96-50cs”, and “KF-96” manufactured by Shin-Etsu Chemical Co., Ltd. -100cs "," KF-96-200cs "," KF-96-300cs "," KF-96-500cs "," KF-96-1000cs "," KF-96-3000cs "," KF-96-5000cs " ”,“ KF-96-10,000 cs ”, dimethyl silicone oils such as“ SH200-10CS ”,“ SH200-100CS ”,“ SH200-1000CS ”,“ SH200-10000CS ”manufactured by Toray Dow Corning Co., Ltd .; “KF-393”, “KF-859”, “KF-860”, “KF-861”, “KF-864” manufactured by Shin-Etsu Chemical Co., Ltd. "KF-865", "KF-867", "KF-868", "KF-869", "KF-6012", "KF-880", "KF-8002", "KF-8004", "KF -8005 "," KF-877 "," KF-8008 "," KF-8010 "," KF-8012 "," X-22-3820W "," X-22-3939A "," X-22-161A " ”,“ X-22-161B ”,“ X-22-1660B-3 ”,“ BY16-871 ”,“ BY16-853U ”,“ FZ-3705 ”,“ SF8417 ”of Toray Dow Corning Co., Ltd., “BY16-849”, “FZ-3785”, “BY16-890”, “BY16-208”, “BY16-893”, “FZ-3789”, “BY16-878”, “BY16-891”, etc. Mino-modified silicone oil; “FL-5”, “X22-821”, “X-22-822”, “FL-100-100CS”, “FL-100-450CS” manufactured by Shin-Etsu Chemical Co., Ltd., “ Fluorosilicone oils such as “FL-100-1000CS”, “FL-100-10000CS”, “FS1265-300CS”, “FS1265-1000CS”, “FS1265-10000CS” of Toray Dow Corning Co., etc .; .

The resin particle-containing liquid (particularly resin particles) in the present invention is preferably one that does not form a film or polymerize when applied to the image surface. In particular, it is preferable not to form a film under fixing process conditions. For example, it is preferable that the content ratio of the resin particles and the water-soluble organic solvent does not show the minimum film-forming temperature when the latter is 40 parts by mass with respect to the former 100 parts by mass. Thereby, fixing offset can be improved more and blocking can be suppressed more effectively. The minimum film forming temperature may be measured in the same manner as in the above T _A.
The resin particle-containing liquid may contain a known additive as long as the effect of the present application is not impaired.

(Heating roller)
It is essential that the surface temperature (heating temperature) of the heating roller is higher than the minimum film-forming temperature (MFT ^40% ) and lower than the glass transition temperature of the resin particles. Thereby, glossiness is improved and blocking is improved by allowing the resin particles to exist on the image in the form of particles while promoting the formation of a film-forming polymer in the image. The temperature may be, for example, about 40 to 100 ° C., preferably about 50 to 90 ° C.

  The method of heating is not particularly limited, but a non-contact drying method such as a method of heating with a heating element such as a nichrome wire heater, a method of supplying warm air or hot air, a method of heating with a halogen lamp, an infrared lamp, etc. Preferably, it can be mentioned.

  The heating roller may be a metal metal roller, and a roller provided with a coating layer made of an elastic body and, if necessary, a surface layer (also referred to as a release layer) on the surface of a metal cored bar. It may be. The metal roller and the metal core can be formed of a cylindrical body made of, for example, iron, aluminum, or SUS. The coating layer is particularly preferably formed of a silicone resin or fluororesin having releasability. In addition, it is preferable that a heating element is built in one core of the heating roller, and heat treatment and pressure treatment are performed simultaneously by passing a recording medium between the rollers, or as necessary. Then, the recording medium may be sandwiched and heated using two heating rollers. As the heating element, for example, a halogen lamp heater, a ceramic heater, a nichrome wire or the like is preferable.

(Applying to the surface of the heating roller)
The applying step of the first aspect of the present invention is a step of applying the liquid containing the resin particles (resin particle-containing liquid) to the surface of the heating roller. For example, a method of bringing the cloth material impregnated with the resin particle-containing liquid into contact with the surface of the heating roller, a method of spraying the resin particle-containing liquid onto the surface of the heating roller, a method of applying with a roll coater, and the like are exemplified. In particular, the method of bringing the cloth material into contact with the heating roller is preferable from the viewpoint of supplying an appropriate amount of resin particle-containing liquid to the roller surface without unevenness. The cloth material (web member) at this time may be any of a woven fabric, a non-woven fabric, etc., and a commercially available or known material may be used, but a heat resistant material is preferable because it is brought into contact with the heating roller. Examples thereof include polyvinylidene chloride, polyethylene, aramid, polyester, and mixtures thereof.

  An example of the application process of the first aspect will be described with reference to FIG. A cloth material 5 containing a resin particle-containing liquid is pressed against a heating roller (fixing roller) 1 by a web pressing roller 3. While the cloth material 5 is wound by the rotation of the feed roller 2 and the take-up roller 4, the cloth material 5 is in contact with the heating roller 1 to continuously supply the resin particle-containing liquid to the surface of the heating roller.

(Applying to the image surface)
The applying step according to the second aspect of the present invention is a step in which the resin particle-containing liquid is directly applied to the recording medium on which the image is recorded instead of the heating roller.
The application of the second aspect can be performed by applying a known method such as a spray method, 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 blade coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater or the like can be used. The details of the inkjet method are as described above.

3. Fixing Step The fixing step is a step of bringing a heating roller into contact with the surface of the image.
It is essential that the surface temperature of the heating roller of the present invention satisfies the formula (1), that is, higher than the minimum film-forming temperature (MFT ^40% ) and lower than the glass transition temperature of the resin particles. As a result, film formation of the film-forming polymer contained in the recorded image can be promoted and fixed, and the resin particles can be efficiently applied to the image surface in the form of particles. Properties can be imparted. Also, the fixing offset can be improved.

In the fixing step of the present invention, for example, in the first aspect, a resin roller containing resin particles is pressed onto a recording medium (printed material) on which an image is recorded by pressing a heating roller having a resin particle-containing liquid adhered to the roller surface. The image can be fixed while being applied to the surface of the printed material. In the second aspect, the resin particles already exist on the surface of the printed material before the contact with the heating roller, and the image can be fixed together with the resin particles by the contact with the heating roller. In the present invention, the first embodiment is preferable from the viewpoint that the resin particles can be suitably attached to the image surface and blocking can be effectively suppressed.
The pressing method is not limited. For example, (i) a pressure roller is further used so that the recorded image surface is in contact with the surface of the heating roller between the pair of rollers (the heating roller and the pressure roller). (Ii) a method of using two heating rollers and passing between the pair of heating rollers, and (iii) a printed image conveyed on a conveying belt on which the recorded image surface is a heating roller Examples of the method include a method of passing through the surface and (iv) a combination of these methods.

  The pressure at the time of pressing is preferably in the range of 0.1 MPa to 3.0 MPa, more preferably in the range of 0.1 MPa to 1.0 MPa, and still more preferably in the range of 0.1 MPa to 1.0 MPa from the viewpoint of surface smoothing. The range is 0.5 MPa.

  A preferable nip time when the recording medium passes through the heating roller is 1 millisecond to 10 seconds, more preferably 2 milliseconds to 1 second, and further preferably 4 milliseconds to 100 milliseconds. Moreover, a preferable nip width is 0.1 mm to 100 mm, more preferably 0.5 mm to 50 mm, and still more preferably 1 mm to 10 mm.

  In order to achieve the pressure (nip pressure), for example, an elastic member such as a spring having tension is selected so that a desired nip pressure can be obtained in consideration of the nip gap at both ends of a roller such as a heating roller. And install.

  The belt base material for transporting the recording medium is not limited. For example, seamless nickel brass is preferable, and the thickness of the base material is preferably 10 μm to 100 μm. Further, as the material of the belt base material, aluminum, iron, polyethylene or the like can be used in addition to nickel. When silicone resin or fluororesin is provided, the thickness of the layer formed using these resins is preferably 1 μm to 50 μm, more preferably 10 μm to 30 μm.

The conveyance speed of the recording medium is preferably in the range of 200 mm / second to 700 mm / second, more preferably 300 mm / second to 650 mm / second, and still more preferably 400 mm / second to 600 mm / second.
The amount of resin particles applied to the recording medium is not limited, and can be appropriately adjusted by the amount supplied to the heating roller, the concentration of the resin particle-containing liquid, and the like. Furthermore, in the method using the cloth material impregnated with the resin-containing liquid, the amount of the cloth material impregnated and the amount of the cloth material fed can be adjusted.
In the image forming process of the present invention, a drying process may be performed by providing an apparatus such as an ink drying zone between the recording process, the applying process, and the fixing process or after the applying process.

  A preferred example of the forming process of the present invention will be described with reference to the schematic view of the apparatus shown in FIG. When the recording medium 11 is fed into the apparatus by the conveyor belt 10 or the like, first, the treatment liquid is applied by the treatment liquid application bar 13 in the treatment liquid application unit 12, and then the recording medium is supplied by the heating and drying unit 14. Dried. Thereafter, when the ink jet recording unit 16 is reached, ink is ejected from the ink jet nozzle 17 toward the recording medium, and a recorded image is formed on the recording medium. The recording medium (printed material) on which the image is recorded is further conveyed to the fixing unit via the heat drying unit 14. The fixing unit includes a heating roller (fixing roller) 1 and a pressure roller 6. In the heating roller, the cloth material 5 partially impregnated with the resin particle-containing liquid is pressed, and as a result, the resin particles adhere to the roller surface. The conveyed printed matter passes between the heating roller 1 and the pressure roller 6. By this passage, the image formed on the recording medium is fixed, and the resin particles adhering to the surface of the heating roller are transferred to the surface of the printed material. Thereafter, the sheet is cut into a predetermined size as necessary, and then discharged from the discharge port, and the printed matter is stacked on a discharge tray (not shown). In FIG. 2, first, a treatment liquid application unit 12 is provided, and a treatment liquid application step (described later) is performed on the surface of the recording medium by contacting the treatment liquid application bar. Although the heating drying part 14 is provided after 16 and the drying process is performed, these process liquid provision processes and a heating process are not essential.

  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 0.45 mass%, the flow rate was 0.35 ml / min, the sample injection amount was 10 μl, the measurement temperature was 40 ° C., and the RI 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 ink composition>
(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 amount of hexane, and the precipitated resin was dried to obtain 96 g of a polymer dispersant P-1.
The composition of the obtained polymer dispersant P-1 was confirmed by 1H-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 further removing a part of the water under reduced pressure, using a high-speed centrifugal cooler 7550 (manufactured by Kubota Seisakusho), using a 50 mL centrifuge tube, 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 (cyan 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 preparing the dispersion C of resin-coated pigment particles, Pigment Red 122 (CROMOPHTAL Jet Magenta DMQ, manufactured by Ciba Japan Co., Ltd .; magenta pigment) was used instead of Pigment Blue 15: 3 (Cyan Pigment). Prepared a dispersion M (magenta dispersion M) of resin-coated pigment particles (pigment coated with a polymer dispersant) in the same manner as in the preparation of dispersion C of resin-coated pigment particles.

(Preparation of dispersion Y of resin-coated pigment particles)
Other than using Pigment Yellow 74 (Irgalite Yellow GS, manufactured by Ciba Japan Co., Ltd .; Yellow Pigment) instead of Pigment Blue 15: 3 (Cyan Pigment) in preparing Resin-coated pigment particle dispersion C Prepared a dispersion Y (yellow dispersion Y) of resin-coated pigment particles (pigment coated with a polymer dispersant) in the same manner as the preparation of dispersion C of resin-coated pigment particles.

(Preparation of dispersion K of resin-coated pigment particles)
Resin-coated pigment except that carbon black (NIPEX160-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 (black dispersion K) of resin-coated pigment particles (pigment coated with a polymer dispersant) was prepared.

(Preparation of self-dispersing polymer particles)
-Synthesis Example 1
-Preparation of aqueous dispersion of polymer particles B-1-
In a 2 L three-necked flask equipped with a mechanical stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, 540.0 g of methyl ethyl ketone was charged, and the temperature was raised to 75 ° C. While maintaining the temperature in the reaction vessel at 75 ° C., 108 g of methyl methacrylate, 388.8 g of isobornyl methacrylate, 43.2 g of methacrylic acid, 108 g of methyl ethyl ketone, and a polymerization initiator (“V-601”, Wako Pure Chemical Industries, Ltd.) )) A mixed solution consisting of 2.16 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 consisting of 1.08 g of “V-601” and 15.0 g of methyl ethyl ketone was added, stirred for 2 hours at 75 ° C., and then a solution consisting of 0.54 g of “V-601” and 15.0 g of methyl ethyl ketone was added. After stirring at 75 ° C. for 2 hours, the temperature was raised to 85 ° C., and stirring was further continued for 2 hours to obtain a methyl methacrylate / isobornyl methacrylate / methacrylic acid (= 20/72/8 [mass ratio]) copolymer. A resin solution was obtained.
The obtained copolymer had a weight average molecular weight (Mw) of 61,000. The acid value determined by the method described in JIS standard (JIS K0070: 1992) was 52.1 mgKOH / g.

  Next, 588.2 g of the above resin solution was weighed, 165 g of isopropanol, 120.8 ml of 1 mol / L sodium hydroxide aqueous solution was added, and the temperature in the reaction vessel was raised to 80 ° C. Next, 718 g of distilled water was added dropwise at a rate of 20 ml / min to disperse in water. Then, the solvent was distilled off by keeping the reaction vessel internal temperature at 80 ° C. for 2 hours, 85 ° C. for 2 hours and 90 ° C. for 2 hours under atmospheric pressure. Furthermore, the inside of the reaction vessel was decompressed to distill off isopropanol, methyl ethyl ketone, and distilled water, and an aqueous dispersion of self-dispersing polymer particles B-1 (film-forming polymer particles) having a solid content of 26.0% by mass was obtained. Obtained.

The measured value (measured Tg) of the glass transition temperature of the polymer particle B-1 was 180 ° C. The measurement Tg was measured by the following method.
An aqueous dispersion of 0.5 g of polymer particles in solid content was dried under reduced pressure at 50 ° C. for 4 hours to obtain a polymer solid content. Using the obtained polymer solid content, Tg was measured with a differential scanning calorimeter (DSC) EXSTAR 6220 manufactured by SII Nanotechnology. The measurement condition was that 5 mg of the sample was sealed in an aluminum pan, and the DSC peak top value of the measurement data at the second temperature increase was measured Tg in a nitrogen atmosphere with the following temperature profile.
30 ° C → -50 ° C (cooled at 50 ° C / min)
−50 ° C. → 140 ° C. (temperature rising at 20 ° C./min)
140 ° C → -50 ° C (cool at 50 ° C / min)
−50 ° C. → 140 ° C. (temperature rising at 20 ° C./min)

-Preparation method of wax 1-
60 g of microcrystalline wax (HI-MIC1090 manufactured by Nippon Seiwa Co., Ltd., melting point 88 ° C.) and 40 g of compound WA-2 (the following structural formula) were added to a 2 liter stainless steel disperser and heated to 100 ° C. And mixed to obtain a uniform and viscous mixture. To this molten mixture, 800 g of hot water at 95 ° C. was added and dispersed at a high speed with a homogenizer (manufactured by Nippon Seiki Co., Ltd .; 10,000 rpm, 10 minutes). While the stirring was continued, the disperser was cooled and the internal temperature was gradually lowered to obtain wax 1 of solid dispersion. The average particle size of the dispersion was 0.2 μm.

-Preparation of ink composition-
Dispersion of resin-coated pigment particles obtained above (cyan dispersion C, magenta dispersion M, yellow dispersion Y, black dispersion K), dispersion of self-dispersing polymer particles (B-1) Each component was mixed using the product so as to have the following ink composition, packed in a plastic disposable syringe, and a 5 μm pore size filter made of polyvinylidene fluoride (PVDF) (Millex-SV, Millex-SV, diameter 25 mm) The ink composition was prepared by filtration.

(Composition of cyan ink C1)
Cyan pigment (Pigment Blue 15: 3): 4% by mass
-Polymer dispersant P-1 (solid content): 2% by mass
-Self-dispersing polymer particles B-1 (solid content): 4% by mass
・ Sanix GP250: 8% by mass
(Sanyo Chemical Industries, water-soluble organic solvent)
Tripropylene glycol monoethyl ether (TPGmME): 8% by mass
(Wako Pure Chemical Industries, water-soluble organic solvent)
・ Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd., surfactant): 1% by mass
・ Wax 1: 2% by mass
Ion exchange water was added to the above components to prepare 100% by mass.

(Composition of magenta ink M1)
The composition was the same as that of cyan ink C1, except that the cyan pigment in the composition of cyan ink C1 was changed to a magenta pigment (Pigment Red 122) so that the amount of the pigment was the same.

(Composition of yellow ink Y1)
The composition was the same as that of the cyan ink C1 except that the cyan pigment in the composition of the cyan ink C1 was changed to a yellow pigment (Pigment Yellow 74) so that the amount of the pigment was the same.

(Composition of black ink K1)
The composition was the same as that of the cyan ink C1 except that the cyan pigment in the composition of the cyan ink C1 was changed to a black pigment (carbon black) so that the amount of the pigment was the same.

(Composition of cyan ink C2)
Cyan pigment (Pigment Blue 15: 3): 4% by mass
-Polymer dispersant P-1 (solid content): 2% by mass
-Self-dispersing polymer particles B-1 (solid content): 4% by mass
・ Sanix GP250: 16% by mass
(Sanyo Chemical Industries, water-soluble organic solvent)
・ Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd., surfactant): 1% by mass
・ Wax 1: 2% by mass
Ion exchange water was added to the above components to prepare 100% by mass.

(Composition of magenta ink M2)
The composition was the same as that of cyan ink C2, except that the cyan pigment in the composition of cyan ink C2 was changed to a magenta pigment (Pigment Red 122) so that the amount of the pigment was the same.

(Composition of yellow ink Y2)
The composition was the same as that of the cyan ink C2, except that the cyan pigment in the composition of the cyan ink C2 was changed to a yellow pigment (Pigment Yellow 74) so that the amount of the pigment was the same.

(Composition of black ink K2)
The composition was the same as that of the cyan ink C2, except that the cyan pigment in the composition of the cyan ink C2 was changed to a black pigment (carbon black) so that the amount of the pigment was the same.

MFT ^40%: measuring the self-dispersing polymer fine particles (B-01) 25 mass% of _{(T A} MFT containing a hydrophilic organic solvent 40 wt%) (solid content), the solvent used for each ink described in Table 1 (Total amount) An aqueous solution of 10% by mass and 65% by mass of water was prepared and measured using an MFT measuring machine manufactured by YOSHIMITSU SEIKI. Specifically, each aqueous solution obtained was applied onto a PET film (64 cm × 18 cm) with a blade having a length of 50 cm × width of 3 cm so that the thickness of the coating film was 300 μm, and then heated from the back side of the PET film. The coating film was subjected to a temperature gradient of 20 to 74 ° C. and dried in an environment of 20 ° C. and 22% RH for 4 hours. At this time, the boundary temperature [° C.] between the portion where the white powdery precipitate was generated and the portion where the transparent film was formed was measured and set as the minimum film-forming temperature.

Here, the C1 solvent and the C2 solvent are as follows.
C1 solvent: Mixed solvent of SANNICS GP250 and TPGmME (mass ratio 1: 1)
C2 solvent: Sanniks GP250

<Preparation of treatment solution>
A treatment liquid (1) was prepared as follows. The surface tension was measured using an Automatic Surface Tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.) under the condition of 25 ° C. by the Wilhelmi method using a platinum plate.
The viscosity was measured using a VISCOMETER TV-22 (manufactured by TOKI SANGYO CO. LTD) at 30 ° C.
The pH was measured at 25 ° C. with the stock solution using a pH meter WM-50EG manufactured by Toa DKK Co., Ltd.

Each component was mixed so that it might become the following composition, and the process liquid (1) was prepared. The physical properties of the treatment liquid (1) were a viscosity of 2.6 mPa · s, a surface tension of 37.3 mN / m, and a pH of 1.6.
<Composition of treatment liquid (1)>
Malonic acid (divalent carboxylic acid, manufactured by Wako Pure Chemical Industries, Ltd.) 15.0% by mass
・ Diethylene glycol monomethyl ether (Wako Pure Chemical Industries, Ltd.) 20.0% by mass
・ N-oleoyl-N-methyl taurine sodium (surfactant) 1.0% by mass
・ Ion-exchanged water 64.0% by mass

-Production of web members 1-4-
・ Silicone oil 85.0% by mass
("KF-96-100cs", manufactured by Shin-Etsu Chemical Co., Ltd.)
・ Resin particles (resin particles 1 below) 15.0% by mass
1 L of the liquid having the above composition was mixed at 8000 rpm for 10 minutes with a Silverson emulsifier to prepare a resin particle dispersion 1. The web member 1 was produced by impregnating the resin particle dispersion 1 into a nonwoven fabric so as to be 30 g / m ² . The nonwoven fabric was a mixed material of polyamide and polyester, and had a weight of 30 g / m ² and a thickness of 0.1 mm.

  Webs 2 to 4 were produced in the same manner except that the resin particles 1 of the web member 1 were changed to resin particles 2 to 4. In addition, the product in the form of dispersion was once pulverized by freeze-drying or the like and redispersed in silicone oil. In addition, Tg of the following resin particle was measured similarly to Tg of the said polymer particle.

-Resin particles 1:
Cross-linked polymethyl methacrylate particles (Product name: MX-501, manufactured by Soken Chemical Co., Ltd.)
Tg> 140 ° C.
-Resin particles 2:
Cross-linked polystyrene particles (Product name: MX-800, manufactured by Soken Chemical Co., Ltd.)
Tg> 140 ° C.
-Resin particles 3:
Crosslinked acrylate particles (Product name: SX-500H, manufactured by Soken Chemical Co., Ltd.)
Tg = 100 ° C.
-Resin particles 4:
Ethylene-vinyl acetate particles (Product name: Chemipearl V200, manufactured by Mitsui Chemicals, Inc.)
Tg = 85 ° C
About the said resin particles 1-4, ^40% of MFT in the state which contained the solvent 40 mass ^% was measured. The measurement method was the same as described above except that “self-dispersing polymer fine particles (B-01)” were “resin particles 1 to 4”.

  Here, the C1 solvent and the C2 solvent are the same as described above.

<Image formation and evaluation>
As shown below, an image was recorded using ink C1 / M1 / Y1 / K1, and the following evaluation was performed. The evaluation results are shown in Table 3 below.

-Abrasion resistance-
A GELJET GX5000 printer head (full line head manufactured by Ricoh) was prepared, and the storage tank connected thereto was refilled with the cyan ink C1, the magenta ink M1, the yellow ink Y1, and the black ink K1 obtained above. As a recording medium, an OK top coat (Oji Paper Co., Ltd .: basis weight 104.7 g / m ² ) is fixed on a stage (conveyor belt) movable in a predetermined linear direction at 500 mm / sec. The treatment liquid obtained above was applied with a wire bar coater to a thickness of about 1.5 μm (corresponding to malonic acid 0.34 g / m ² ), and dried immediately at 50 ° C. for 2 seconds (FIG. 2). .
Thereafter, when the GELJET GX5000 printer head (full line head manufactured by Ricoh Co., Ltd.) is orthogonal to the direction of movement of the stage (sub-scanning direction), the direction of the line head in which the nozzles are aligned (main scanning direction) is 75. It is fixedly arranged so as to incline by 7 °, and the recording medium is ejected by a line method under the ejection conditions of ink droplet amount 2.4 pL, ejection frequency 24 kHz, resolution 1200 dpi × 1200 dpi while moving at a constant speed in the sub-scanning direction. An image was printed to obtain an evaluation sample. Immediately after printing, it was dried at 60 ° C. for 3 seconds.
Next, the web member installed as shown in FIG. 2 is changed in accordance with each evaluation (Table 3 below), and passes between a pair of rollers (heating roller and pressure roller) heated to the temperature shown in Table 3 As a result, a fixing process was performed at a nip pressure of 0.25 MPa and a nip width of 4 mm, and an evaluation sample was obtained.
The heating roller (fixing roller) shown in FIG. 2 is a SUS cylindrical core whose surface is covered with a silicone resin with a halogen lamp inside.
Wrapped unprinted OK top coat + cut to 10mm x 50mm around paperweight (weight 470g, size 15mm x 30mm x 120mm) (area of contact between unprinted special Nishi art both sides N and evaluation sample is 150mm ² ) The evaluation sample prepared above was rubbed 3 times (corresponding to a load of 260 kg / m ² ). The marking screen after rubbing was visually observed and evaluated according to the following evaluation criteria.

<Evaluation criteria>
A: No peeling of the image on the stamp screen was visible.
B: A slight peeling of the image on the seal screen was visually recognized, but at a level that does not cause any practical problems.
C: Level at which the peeling of the image on the seal screen can be visually confirmed and there is a practical problem.

-Blocking evaluation-
A solid image was prepared in the same manner as the abrasion resistance. Two evaluation samples were cut into a size of 4 cm × 4 cm, bonded so that the recording surfaces overlap each other, and a pressure of 2.0 MPa was applied for 30 seconds with a press to peel off the evaluation sample. The ease of peeling at this time and the color transfer after peeling were observed visually and evaluated according to the following evaluation criteria.

<Evaluation criteria>
A: Peeled naturally and no color transfer to each other's paper was observed.
B: Sticking occurred, and some color transfer to each other's paper was observed.
C: Sticking was strong, and many colors were transferred to each other's paper.

-Glossiness evaluation-
A 70% halftone dot image was produced by the same image forming method as the abrasion resistance. The 60 degree glossiness of the sample was measured and compared with the measured value of an unprinted OK top coat + (white background). Evaluation was performed according to the following evaluation criteria.

<Evaluation criteria>
A: The glossiness was larger than the measured value of the white background, and good glossiness was exhibited.
B: The glossiness is lower than the measured value of the white background, but the difference is within 5%.
C: The glossiness was lower than the measured value of the white background, the difference was more than 5%, and the gloss reduction was remarkable.

-Fixing offset evaluation-
Using the same printing method as that for rubbing resistance, solid printing was performed from each Y / M / C head under the discharge conditions of ink droplet amount 2.4 pL, discharge frequency 24 kHz, resolution 1200 dpi × 1200 dpi, I printed solid. The fixing roller and the image after the printing were observed and evaluated according to the following evaluation criteria.

<Evaluation criteria>
A: Good adhesion with no fouling on the fixing roller and no peeling of the image.
B: Slight adhesion to the fixing roller was observed, but no peeling of the image was observed.
C: Peeling of the image was observed, which was a practical problem.

1. 1. Heating roller 2. Delivery roller 3. Web pressing roller 4. Winding roller Cloth material (web material)
6). Pressure roller 10. Conveyor belt 11. Recording medium 12. Treatment liquid application unit 13. Treatment liquid application bar 14. Heat drying unit 15. Dryer 16. Inkjet recording unit 17. Inkjet nozzle

Claims (10)

A recording step of recording an image on a recording medium by an inkjet method using an ink composition containing a coloring material, a first polymer particle having film-forming properties, a water-soluble organic solvent, and water;
An applying step of applying a liquid containing second polymer particles having a glass transition temperature to the surface of the heating roller or the image;
A fixing step of bringing a heating roller into contact with the surface of the image,
_A minimum film-forming temperature T _A ° C measured by mixing the first polymer particles contained in the ink composition and the water-soluble organic solvent; a surface temperature T _B ° C of the heating roller; The glass transition temperature T _C ° _C of the polymer particles 2 is represented by the following formula (1):
T _A <T _B <T _C (1)
An inkjet image forming method characterized by satisfying the above.   The inkjet image forming method according to claim 1, wherein the applying step is a step of bringing a cloth material containing a liquid containing the second polymer particles into contact with a heating roller.   The inkjet image forming method according to claim 1, wherein the first polymer particles are a self-dispersing polymer.   The inkjet image forming method according to claim 3, wherein the self-dispersing polymer is a polymer including a hydrophilic structural unit and at least one structural unit derived from an alicyclic monomer.   The inkjet image forming method according to claim 1, wherein the liquid is a non-volatile solvent.   The inkjet image forming method according to any one of claims 1 to 5, wherein the second polymer particles are insoluble in water.   The inkjet image forming method according to claim 1, wherein the second polymer particles are polymethyl (meth) acrylate. Wherein _{T A} is 20 to 70 ° C., the inkjet image forming method according to any one of claims 1 to 7. Wherein _{T B} is 40 to 100 ° C., an inkjet image forming method according to any one of claims 1 to 8. Wherein T _C is 80 ° C. or more, the inkjet image forming method according to any one of claims 1 to 9.