JP2012040817A - Image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method by which the blocking, blotting and a change in brilliance of a printed matter are suppressed while load on environment is suppressed when forming an aqueous image by an inkjet method.SOLUTION: The image forming method includes: an image recording process of recording an image on a recording medium by the inkjet method by using an ink composition containing water and a pigment; a particle imparting process of imparting a particle-containing composition onto the image, the particle-containing composition containing water and cross-linked organic particles or inorganic particles having a volume average particle size of 15 to 60 μm; a polymer imparting process of imparting a polymer-containing composition which contains a polymer onto the image; and a filming process of filming the polymer.

Description

  The present invention relates to an image forming method suitable for image formation.

Printed matter printed by a commercial printing machine such as offset printing is 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 intimate contact with another stacked printed matter, and when the adhered printed matter is pulled away, the ink is peeled off from the printed matter and adheres to the other printed matter (blocking). May occur. In order to suppress this blocking, in offset printing, after printing, a powder such as starch is sprayed as a blocking inhibitor to adhere to the surface of the printed material, thereby preventing ink sticking.
For example, Patent Document 1 proposes a method of spraying a small amount of powder on a printed material surface in offset printing. Patent Document 2 discloses a method of improving the blocking property and the like by applying a coating agent containing a granular wax and an emulsion resin on the offset printing surface.

JP-A-10-130621 JP 2007-296637 A

However, the powder applied on the image by the method of Patent Document 1 easily spills from the image during paper movement during printing or paper sorting after printing, and there is still room for improvement in blocking suppression. is there.
Further, since the method described in Patent Document 2 is used when an image is formed by offset printing (oil-based ink), if the method of Patent Document 2 is applied to an image formed with water-based ink, problems such as image blurring occur. Will occur.
The present invention has been made in view of the above, and provides an image forming method in which blocking of printing, blurring, and gloss change are suppressed while an environmental load is suppressed when an aqueous image is formed by an inkjet method. The purpose is to do.

Specific means for solving the above problems are as follows.
Item 1. An image recording step of recording an image on a recording medium by an ink jet method using an ink composition containing water and a pigment, and a particle-containing composition containing water and crosslinked organic particles or inorganic particles having a volume average particle diameter of 15 μm to 60 μm An image forming method comprising: a particle applying step for applying an object onto the image; a polymer applying step for applying a polymer-containing composition containing a polymer onto the image; and a film forming step for forming the polymer into a film.
Item 2. Item 2. The image forming method according to Item 1, wherein the crosslinked organic particles in the particle-containing composition are particles containing poly (meth) acrylate, polystyrene, polyacrylonitrile, or polyethylene.
Item 3. Item 2. The image forming method according to Item 1, wherein the inorganic particles in the particle-containing composition are silica particles.
Item 4. Item 4. The image forming method according to any one of Items 1 to 3, wherein the volume average particle diameter of the crosslinked organic particles or inorganic particles in the particle-containing composition is 20 μm to 40 μm.
Item 5. Item 5. The image forming method according to any one of Items 1 to 4, wherein a lower glass transition temperature Tg or melting point Tm of the polymer is -50 ° C to 90 ° C.
Item 6. Item 6. The image forming method according to any one of Items 1 to 5, wherein the particle applying step is a step of supplying the particle-containing composition to the surface of a heating roller and pressing the heating roller against the recording medium.

  According to the present invention, it is possible to provide an image forming method in which blocking, blurring, and gloss change of a printed matter are suppressed while suppressing an environmental load.

  Hereinafter, the image forming method of the present invention will be described in detail.

The image forming method of the present invention includes an image recording step of recording an image on a recording medium by an inkjet method using an ink composition containing water and a pigment, and crosslinked organic particles having water and a volume average particle diameter of 15 to 60 μm. Alternatively, a particle applying step of applying a particle-containing composition containing inorganic particles onto the image, a polymer applying step of applying a polymer-containing composition containing a polymer onto the image, and a film forming step of forming the polymer into a film It is characterized by including.
Generally, when an aqueous liquid is applied on an image recorded using an aqueous ink composition, the image recorded with the aqueous ink composition is dissolved, and problems such as bleeding occur. Therefore, it is not considered to apply an aqueous liquid on an image recorded with an aqueous ink composition. However, in the present invention, after recording an image with an ink composition containing water, a particle-containing composition containing water and a polymer-containing composition are applied onto the image, thereby blocking image bleeding. Succeeded in suppressing resistance and gloss change. Furthermore, because water is used, it has become possible to reduce the burden on the environment, and has succeeded in suppressing changes in glossiness.

In the present invention, the image recording step, the particle applying step, the polymer applying step, and the film forming step may be performed in this order, or the image recording step, the polymer applying step, the particle applying step, and the film forming step may be performed in this order. . Moreover, you may perform a particle | grain provision process and a polymer provision process simultaneously. That is, the particle application step and the polymer application step may be performed simultaneously by applying a composition containing water, crosslinked organic particles or inorganic particles having a volume average particle diameter of 15 to 60 μm, and a polymer onto the image. The image forming method of the present invention is preferably performed in the order of an image recording step, a polymer applying step, a particle applying step, and a film forming step.
Hereinafter, each process will be described in detail. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

≪Image recording process≫
The image forming method of the present invention includes an image recording step of recording an image on a recording medium by an ink jet method using an ink composition containing water and a pigment. The image recording process will be described in detail below.

<Inkjet method>
The ink jet method used in the present invention is not particularly limited, and is a known method, for example, a charge control method for ejecting ink using electrostatic attraction, a drop-on-demand method (pressure pulse using a vibration pressure of a piezo element). Method), acoustic ink jet method in which electric signal is converted into acoustic beam, ink is irradiated and ink is ejected by using radiation pressure, and thermal ink jet (bubble) that heats ink to form bubbles and uses the generated pressure Any of a jet (registered trademark) system may be used. 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.

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.

  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 used in 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.

  The droplet amount of the ink composition ejected from the inkjet head is preferably 0.5 to 15 pl (picoliter), more preferably 1 to 12 pl, and still more preferably 2 to 10 pl, from the viewpoint of obtaining a high-definition image. It is.

<Recording medium>
The image recording process in the present invention is to record an image on a recording medium.
The recording medium is not particularly limited, and general printing paper mainly composed of cellulose, such as so-called high-quality paper, coated paper, and art paper, used for general offset printing and the like can be used.

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

  Among the recording media, so-called coated paper used for general offset printing is preferable. The coated paper is obtained by applying a coating material to the surface of high-quality paper, neutral paper, or the like that is mainly surface-treated with cellulose as a main component and is not surface-treated. In particular, it is preferable to use a coated paper having a base paper and a coat layer containing kaolin and / or calcium bicarbonate. These are more preferably art paper, coated paper, lightweight coated paper, or finely coated paper.

<Ink composition>
The ink composition used in the image recording step in the present invention is not limited as long as it contains water and a pigment, and a known or commercially available one can be used.

(Pigment)
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. The following coloring materials may be used alone or in combination of two or more.
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 222, C.I. 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.

  The pigment in the present invention may be 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.

  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.

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 volume average particle diameter of the pigment is preferably 10 to 200 nm, more preferably 10 to 150 nm, and still more preferably 10 to 130 nm. When the volume average particle diameter 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. The particle size distribution of the pigment 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. In addition, the volume average particle diameter of the particles can be measured with a nanotrack particle size distribution measuring apparatus UPA-EX150 (manufactured by Nikkiso Co., Ltd.).

  The content of the pigment 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)
The ink composition in the present invention preferably contains polymer particles as necessary. Thereby, it is possible to further improve the scratch resistance, fixability, and the like of the image.

  Examples of the polymer particles in the present invention include thermoplastic, thermosetting 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 co-condensation resins, urea resins, urea resins And the like, or particles of a resin having an anionic group such as 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 groups selected from the group consisting of a carboxyl group, a sulfonic acid group, and a phosphone group. Among them, an acrylic monomer having a carboxyl group (for example, (Acrylic acid, methacrylic acid, crotonic acid, ethacrylic acid, propylacrylic acid, isopropylacrylic acid, itaconic acid, fumaric acid, etc.) are preferable, and acrylic acid or methacrylic acid is particularly preferable. The polymer particles can be used singly or in combination of two or more.

  The molecular weight range of the polymer particles in the present invention is preferably 3000 to 200,000, more preferably 5000 to 150,000, and still more preferably 10,000 to 100,000 in terms of weight average molecular weight. The said weight average molecular weight is measured by a gel permeation chromatograph (polystyrene conversion).

  The average particle diameter of the polymer particles is preferably in the range of 10 to 400 nm in terms of volume average particle diameter, more preferably in the range of 10 to 200 nm, still more preferably in the range of 10 to 100 nm, and particularly preferably in the range of 10 to 50 nm. By setting it within this range, suitability for production, storage stability and the like are improved. The average particle diameter of the polymer particles is determined by measuring the volume average particle diameter by a dynamic light scattering method using a nanotrack particle size distribution analyzer UPA-EX150 (manufactured by Nikkiso Co., Ltd.).

  The content of the polymer particles in the ink composition is preferably 1 to 30% by mass and more preferably 2 to 20% by mass with respect to the ink composition from the viewpoint of image glossiness and the like. preferable.

(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.

(Water-soluble organic solvent A)
The ink composition in the present invention may contain a water-soluble organic solvent A in addition to the water as necessary. The term “water-soluble” as used herein means that 0.5% by mass or more dissolves in distilled water at 25 ° C. The water-soluble organic solvent is preferably dissolved in distilled water at 25 ° C. at 1% by mass or more, more preferably 3% by mass or more.
As such a water-soluble organic solvent A, an alkylene oxy alcohol is preferable from the viewpoint of dischargeability. Furthermore, it is particularly preferable to contain two or more water-soluble organic solvents A containing at least one alkyleneoxy alcohol and at least one alkyleneoxy 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, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, ethylene glycol monophenyl ether, and the like.
Moreover, in addition to said water-soluble organic solvent A, you may contain another organic solvent for the purpose of drying prevention, penetration promotion, viscosity adjustment, etc. as needed.

(Other additives)
In addition to the above components, the ink composition can contain other additives as necessary. Other additives include, for example, a polymerizable compound that is polymerized by active energy rays, a polymerization initiator, an antifading agent, an emulsion stabilizer, a penetration accelerator, an ultraviolet absorber, an antiseptic, an antifungal agent, a pH adjuster, Well-known additives, such as a surface tension modifier, an antifoamer, a viscosity modifier, a wax, a dispersion stabilizer, a rust inhibitor, a chelating agent, are mentioned. These various additives may be added directly after the ink composition is prepared, or may be added when the ink composition is prepared.

≪Particle application process≫
The image forming method of the present invention includes a particle applying step of applying a particle-containing composition containing water and crosslinked organic particles or inorganic particles having a volume average particle diameter of 15 to 60 μm on the image.
The method for applying the particle-containing composition is not limited, but known methods such as a transfer method, a spray method, a coating method, and an immersion method can be used. 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. In the present invention, it is particularly preferable to apply the particle-containing composition onto an image by spraying or coating, and it is most preferable to perform coating using a roll.

<Particle-containing composition>
The particle-containing composition used in the particle application step in the present invention is not limited as long as it contains water and crosslinked organic particles or inorganic particles having a volume average particle diameter of 15 to 60 μm.

(water)
The particle-containing composition in the present invention contains water, but the amount of water is not particularly limited. Especially, preferable content of water is 1-99 mass%, More preferably, it is 10-80 mass%, More preferably, it is 15-60 mass%.

(Bridged organic particles or inorganic particles having a volume average particle diameter of 15 to 60 μm)
The particle-containing composition in the present invention includes crosslinked organic particles having a volume average particle diameter of 15 to 60 μm or inorganic particles having a volume average particle diameter of 15 to 60 μm. The volume average particle diameter of the crosslinked organic particles or inorganic particles is preferably 15 to 40 μm, and more preferably 20 to 40 μm. By setting the volume average particle diameter within this range, it is possible to further suppress the fixing offset of the image portion, and it is possible to further suppress a change in image gloss due to particle scattering when the particles are applied on the image. The volume average particle diameter in the present invention is a value measured by a laser diffraction / scattering particle size analyzer Microtrac MT3000II (manufactured by Nikkiso Co., Ltd.). Measurement may be performed by adding 10 ml of ion-exchanged water to 100 μl of a 20% by weight particle aqueous dispersion to prepare a sample solution for measurement, and adjusting the temperature to 25 ° C.
Unlike the polymer contained in the polymer-containing composition described later, the organic crosslinked particles and inorganic particles in the present invention preferably do not form a film.
The content of the crosslinked organic particles and inorganic particles in the particle-containing composition is preferably 0.5 to 50% by mass, more preferably 10 to 45% by mass, and 15 to 40% by mass. Most preferred.

-Crosslinked organic particles-
The crosslinked organic particles in the present invention are not limited as long as they are crosslinked organic particles. The crosslinked organic particles preferably have a Tg of 100 ° C. or higher, more preferably 120 ° C. or higher, and most preferably 130 ° C. or higher. In the present invention, the glass transition temperature Tg of the crosslinked organic particles can be measured according to JIS K6900.
The presence or absence of the crosslinked structure of the organic particles can be considered as follows. When the Tg of the organic particle is higher than the general Tg of the polymer constituting the organic particle, or when the Tg of the organic particle is not observed below the general Tg of the polymer, the organic particle has a crosslinked structure. It is thought that there is. For example, when Tg of organic particles made of polymethyl methacrylate is measured up to 140 ° C. by DSC and Tg is not observed, the Tg of the organic particles is higher than Tg (105 ° C.) of general polymethyl methacrylate. The organic particles are considered to have a crosslinked structure.
Examples of the crosslinked organic particles in the present invention include acrylonitrile-styrene copolymer, polystyrene, styrene-divinylbenzene copolymer, poly (meth) acrylate alkyl, polyisobornyl methacrylate, polyacrylonitrile, polycarbonate, polytetrafluoroethylene. Polyethylene, and the like. Polystyrene and alkyl poly (meth) acrylate are more preferable, poly (meth) alkyl acrylate is more preferable, and polymethyl (meth) acrylate is particularly preferable. Polymethyl (meth) acrylate means at least one of polymethyl acrylate and polymethyl methacrylate (PMMA).
As the crosslinked organic particles, those already marketed as a dispersion may be used. When commercially available crosslinked organic particles are used as the dispersion, they can be used once powdered by a known method such as freeze drying.

Specific examples of the crosslinked organic particles include MX-1500 (manufactured by Soken Chemical Co., Ltd., crosslinked PMMA 15 μm), MX-2000 (manufactured by Soken Chemical Co., Ltd., crosslinked PMMA 20 μm), MX-3000 (manufactured by Soken Chemical Co., Ltd., crosslinked PMMA 30 μm), MR- 20G (manufactured by Soken Chemical Co., Ltd., crosslinked PMMA 20 μm), MR-30G (manufactured by Soken Chemical Co., Ltd., crosslinked PMMA 30 μm), MR-60G (manufactured by Soken Chemical Co., Ltd., crosslinked PMMA 60 μm), SGP-70C (manufactured by Soken Chemical Co., Ltd., polystyrene 20 μm), YK-30 (Toyobo, 33 μm polyacrylonitrile), and the like, more preferably MX-1500 (manufactured by Soken Chemical Co., Ltd., crosslinked PMMA 15 μm), MX-2000 (manufactured by Soken Chemical Co., Ltd., crosslinked PMMA 20 μm), MX-3000 ( Made by Soken Chemical Co., Ltd., cross-linked PMMA 30 μm), MR-20G (Soken Chemical Co., Ltd.) Manufactured, cross-linked PMMA 20 μm), MR-30G (manufactured by Soken Chemical Co., Ltd., cross-linked PMMA 30 μm), SGP-70C (manufactured by Soken Chemical Co., Ltd., polystyrene 20 μm), YK-30 (Toyobo, 33 μm polyacrylonitrile), and the like are more preferable. MX-2000 (manufactured by Soken Chemical Co., Ltd., crosslinked PMMA 20 μm), MX-3000 (manufactured by Soken Chemical Co., Ltd., crosslinked PMMA 30 μm), MR-20G (manufactured by Soken Chemical Co., Ltd., crosslinked PMMA 20 μm), MR-30G (manufactured by Soken Chemical Co., Ltd., crosslinked) PMMA 30 μm), YK-30 (Toyobo, 33 μm polyacrylonitrile) and the like.
In addition, the numerical value (micrometer) shown in said parenthesis is a volume average particle diameter. The volume average particle diameter is a value measured by a laser diffraction / scattering particle size analyzer Microtrac MT3000II (manufactured by Nikkiso Co., Ltd.). Measurement may be performed by adding 10 ml of ion-exchanged water to 100 μl of a 20% by weight particle aqueous dispersion to prepare a sample solution for measurement, and adjusting the temperature to 25 ° C.
The crosslinked organic particles in the present invention are more effective for long-term storage stability by using crosslinked polymer particles having a crosslinked structure. Specifically, the crosslinking density is preferably 0.01 to 50% by mass, more preferably 0.1 to 40% by mass, and most preferably 1 to 20% by mass. The crosslink density can be measured by a known method.

-Inorganic particles-
Examples of the inorganic particles in the present invention include particles of silica (silicon dioxide), titanium oxide, aluminum hydroxide, and the like, and it is preferable to use silica particles.
As titanium oxide particles, MT-150A (Taika, 15 μm), MT-100HD (Taika, 15 μm), MT-300HD (Taika, 25 μm), MT-500HD (Taica, 30 μm), MT -500B (manufactured by Teica, 35 μm), MT-500SA (manufactured by Teica, 35 μm), MT-600B (manufactured by Teica, 50 μm), MT-600SA (manufactured by Teica, 50 μm) and the like.
Examples of the aluminum hydroxide particles include B303 (manufactured by Nippon Light Metal Co., Ltd., 30 μm), B153 (manufactured by Nippon Light Metal Co., Ltd., 15 μm), and the like.
As silica particles, SUNIL-150H-SC (SUNJIN CHEM., Silica 15 μm), silica microbead P-4000 (manufactured by JGC Catalysts & Chemicals, Inc., 20 μm) and the like can be used.
In addition, the numerical value (micrometer) shown in said parenthesis is a volume average particle diameter. The volume average particle diameter is a value measured by a laser diffraction / scattering particle size analyzer Microtrac MT3000II (manufactured by Nikkiso Co., Ltd.). Measurement may be performed by adding 10 ml of ion-exchanged water to 100 μl of a 20% by weight particle aqueous dispersion to prepare a sample solution for measurement, and adjusting the temperature to 25 ° C.

(Water-soluble organic solvent B)
The particle-containing composition in the present invention may contain a water-soluble organic solvent B. The term “water-soluble” as used herein means that 0.5% by mass or more dissolves in distilled water at 25 ° C. The water-soluble organic solvent B is preferably dissolved in distilled water at 25 ° C. in an amount of 1% by mass or more, more preferably 3% by mass or more.
Examples of the water-soluble organic solvent B include alcohol-based media, amide-based media, sulfone-based media, and nitrile-based media, more preferably alcohol-based media, amide-based media, and sulfone-based media, and further preferably Alcohol-based media and amide-based media are exemplified, and alcohol-based media are particularly preferable.
Alcohol-based media include methanol, ethanol, propanol, isopropanol, butanol, glycerin, ethylene glycol, ethylene glycol monoethyl glycol, propylene glycol, diethylene glycol, diethylene glycol monoethyl ether, dipropylene glycol, triethylene glycol, 1,2-butane Diol, 1,3-butanediol, ethyl lactate, methyl lactate, trimethylolpropane, MFG, GP-250, triethylene glycol monomethyl ether, 1,2-hexanediol, etc., methanol, ethanol, propanol, isopropanol, Butanol, ethylene glycol monoethyl glycol, diethylene glycol monoethyl ether, 1,2-butanedio 1,3-butanediol, ethyl lactate, methyl lactate, trimethylolpropane, MFG, 1,2-hexanediol, etc., more preferably propanol, isopropanol, butanol, ethylene glycol monoethyl glycol, diethylene glycol mono Examples include ethyl ether, 1,2-butanediol, 1,3-butanediol, trimethylolpropane and 1,2-hexanediol.
Examples of the amide medium include 2-pyrrolidone, N-methylpyrrolidone, dimethylimidazolinone, dimethylformamide, dimethylacetamide, and the like, more preferably, 2-pyrrolidone and dimethylimidazolinone are more preferable. 2-pyrrolidone.
Examples of the sulfone medium include sulfolane and dimethyl sulfoxide.
An example of the nitrile medium is acetonitrile.
The water-soluble organic solvent B may be used alone or in combination of two or more. When the particle | grain containing composition in this invention contains the water-soluble organic solvent B, it is preferable that content of the water-soluble organic solvent B in particle | grain containing composition is 1-90 mass%, and is 2-70 mass%. More preferably, it is most preferable that it is 5-50 mass%.

(Surfactant)
A surfactant may be added to the particle-containing composition in the present invention for the purpose of improving the dispersibility of the particles or improving the coating property when applied onto an inkjet image. Examples of the surfactant include a nonionic surfactant, a cationic surfactant, an anionic surfactant, and a betaine surfactant. JP-A-59-157636, pages (37) to (38), Research Disclosure No. The surfactants described in 308119 (1989) can also be used. In addition, fluorine (fluorinated alkyl-based) surfactants, silicone-based surfactants and the like described in JP-A Nos. 2003-322926, 2004-325707, and 2004-309806 are also included. Scratch resistance can also be improved.

≪Polymer application process≫
The image forming method of the present invention includes a polymer application step of applying a polymer-containing composition containing a polymer onto the image. The polymer contained in the polymer-containing composition is characterized in that it is formed into a film in the film forming step described later.
The step of applying the polymer-containing composition is not limited, and can be performed by applying a known method such as a transfer method, 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. In the present invention, it is particularly preferable to apply the polymer-containing composition onto an image by an ink jet method.

  It is preferable to apply the polymer particle-containing composition by an inkjet method because the polymer application step can be selectively performed in a desired range.

In the method of the present invention, the applied amount of the polymer-containing composition on the image is preferably 5 mg / m ² or more and 200 mg / m ² or less, more preferably 10 mg / m ² or more and 150 mg / m ² or less, and still more preferably. Is 20 mg / m ² or more and 100 mg / m ² or less.

<Polymer-containing composition>
The polymer-containing composition used in the polymer application step in the present invention is not limited as long as it contains a polymer. Further, the polymer in the polymer-containing composition is characterized by being formed into a film by heating or the like.

(polymer)
The polymer that can be used in the present invention is a polymer or copolymer of acrylic acid (or methacrylic acid) or a derivative thereof (for example, methyl acrylate, ethyl acrylate, methacrylic acid, or methyl methacrylate). Acrylic acid polymer, or rubber polymer such as polyurethane, styrene-butadiene rubber (SBR), ethylene-vinyl acetate (EVA), methyl methacrylate-butadiene rubber (MBR) or acrylonitrile-butadiene rubber (NBR), starch , Natural starch such as modified starch, gelatin, casein, or soy protein, or cells such as carboxymethylcellulose (CMC), hydroxyethylcellulose (HEC), or hydroxypropylcellulose (HPC) Modified polymer or polyvinyl alcohol (PVA), modified PVA, polyacrylamide, polyethylene, polyacetal resin, guar gum, polyester, polyvinyl pyrrolidone, ethylene-polyvinyl alcohol copolymer, polyethylene oxide, polypropylene oxide, polyethylene oxide-polypropylene oxide Examples include copolymers, block polymers thereof, block polymers of polyethylene oxide-polypropylene oxide-polyethylene oxide, block polymers of polypropylene oxide-polyethylene oxide-polypropylene oxide, and the like. Use one or more of these. Can do.
Among these, it is preferable to use a polymer containing (meth) acrylic acid polymer, polyurethane, polyvinyl alcohol, polyethylene oxide or polypropylene oxide. Here, the (meth) acrylic acid polymer means a methacrylic acid polymer or an acrylic acid polymer.
The number average molecular weight of the polymer is not particularly limited, but is preferably 1,000 to 500,000, more preferably 1,000 to 200,000, and 1,000 to 100,000. More preferably, it is 1,000-70,000.

  The polymer content in the polymer-containing composition is preferably 1% by mass to 50% by mass, more preferably 2% by mass to 40% by mass, and further preferably 2% by mass to 30% by mass. Most preferred.

  The glass transition temperature Tg (or melting point Tm) of the polymer is not particularly limited, but is preferably −50 ° C. to 90 ° C., more preferably −30 ° C. to 80 ° C., and most preferably −20 ° C. to 70 ° C. The Tg (or Tm) of the polymer can be measured according to JIS K6900. In addition, when both Tg and Tm are present in the polymer, it is preferable that the lower of Tg and Tm falls within the above range, and when only one of Tg and Tm is present, the value is as described above. It is preferable to fall within the range.

(water)
The polymer particle-containing composition in the present invention preferably contains water. 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.

≪Filming process≫
The image forming method of the present invention includes a film forming step of forming a film on the polymer. The film forming process will be described in detail below.

The film forming step in the present invention is not particularly limited as long as the polymer can be formed into a film, and can be appropriately selected depending on the purpose.
Film formation in the present invention can be performed by heating or the like. It is preferable to perform the film-forming step by heating the image to which the polymer-containing composition has been applied, and it is more preferable to press the heating roller against the image to which the polymer-containing composition has been applied. The heating temperature when forming a film by heating needs to be higher than the glass transition temperature of the polymer. Thereby, it becomes possible to promote film formation of the polymer.

  The film-forming step in the present invention can be performed, for example, by pressing a recording medium (printed material) provided with the ink composition and the polymer-containing composition with a heating roller. At this time, by attaching the particle-containing composition to the surface of the heating roller, particles of 15 μm to 60 μm can be applied to the surface of the printed material and the polymer can be formed into a film. This is preferable because it can be performed in the process.

  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 in contact with the surface, and (iv) a combination of these methods.

  The surface temperature (heating temperature) of the heating roller is not limited as long as it is a temperature at which the polymer in the polymer-containing composition can be formed into a film, and may be at least Tg (or Tm) of the polymer. Thereby, the film | membrane intensity | strength of an image can be improved.

  The heating method is not particularly limited, but a non-contact heating 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 or the like. 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.

  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.

  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.

  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 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.
In the image forming method of the present invention, after any of the image recording step, the particle applying step, the polymer applying step, or the film forming step, a drying step may be performed by providing an apparatus such as an ink drying zone.

≪Processing liquid application process≫
In the present invention, in addition to an image recording step of recording an image on a recording medium by an ink jet method using the ink composition, a treatment liquid containing an aggregating agent that aggregates components in the ink composition is applied to the recording medium. It is preferable to provide a treatment liquid application step. The treatment liquid application step may be provided either before or after the image recording step in the present invention.

  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 agent capable of aggregating dispersed particles such as pigments in the ink composition to form an aggregate, and may be configured using other components as necessary. can do.

(Processing liquid)
The treatment liquid contains at least an aggregating agent for aggregating the components in the ink composition described above, and can be configured using other components as necessary.

The flocculant in the present invention is capable of aggregating (fixing) the ink composition by contacting with the ink composition on the recording medium, and functions as a fixing agent. For example, when the treatment liquid is applied to a recording medium (preferably coated paper), the ink composition further drops and comes into contact with the aggregating agent in the state where the aggregating agent is present on the recording medium. In addition, the components in the ink composition can be aggregated to fix the ink composition on the recording medium.
Examples of the flocculant include acidic compounds, polyvalent metal salts, and cationic polymers. These may be used alone or in combination of two or more. In the present invention, an acidic compound is preferable from the viewpoint of cohesiveness of the ink composition.

-Acidic compounds-
Examples of acidic compounds include sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, polyacrylic acid, acetic acid, glycolic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid, and tartaric acid. , Lactic acid, sulfonic acid, orthophosphoric acid, metaphosphoric acid, pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, and derivatives of these compounds, etc. Preferably mentioned.

Among these, acidic compounds with high water solubility are preferable. Further, from the viewpoint of fixing the whole ink by reacting with the ink composition, an acidic compound having a valence of 3 or less is preferable, and an acidic compound having a valence of 2 to 3 is particularly preferable.
An acidic compound may be used individually by 1 type, and may use 2 or more types together.

  When the treatment liquid contains an acidic compound, the pH (25 ° C.) of the treatment liquid is preferably 0.1 to 6.8, more preferably 0.5 to 6.0, 0.8 More preferably, it is -5.0.

The content of the acidic compound is preferably 40% by mass or less, and more preferably 15 to 40% by mass with respect to the total mass of the treatment liquid. By setting the content of the acidic compound to 15 to 40% by mass, the components in the ink composition can be more efficiently fixed.
Furthermore, it is preferable that content of an acidic compound is 15 mass%-35 mass% with respect to the total mass of the said processing liquid.

-Multivalent metal salt-
The polyvalent metal salt in the present invention is a compound containing a divalent or higher metal such as an alkaline earth metal and a zinc group metal, and includes acetates, oxides and the like of metal ions such as Ca ²⁺ , Cu ²⁺ , and Al ^3+. Can be mentioned.
In the present invention, the agglomeration reaction of the ink composition when the ink composition is discharged onto a recording medium to which the treatment liquid containing the polyvalent metal salt is applied is represented by particles dispersed in the ink composition, for example, a pigment. This can be achieved by reducing the dispersion stability of particles such as the colorant and resin particles, and increasing the viscosity of the entire ink composition. For example, when particles such as pigments and resin particles in the ink composition have weakly acidic functional groups such as carboxyl groups, the particles are dispersed and stabilized by the action of the weakly acidic functional groups. Can be reduced by interacting with the polyvalent metal salt to lower the dispersion stability. Therefore, the polyvalent metal salt as the immobilizing agent contained in the treatment liquid needs to have a valence of 2 or more, that is, multivalent from the viewpoint of the aggregation reaction, and from the viewpoint of the aggregation reactivity, 3 A polyvalent metal salt composed of a polyvalent metal ion having a valence higher than that is preferable.

  From the above viewpoint, the polyvalent metal salt that can be used in the treatment liquid in the present invention is any one or more of the following salts of polyvalent metal ions and anions, polyaluminum hydroxide, and polyaluminum chloride. Preferably there is.

Examples of the polyvalent metal ions include Ca ²⁺ , Cu ²⁺ , Ni ²⁺ , Mg ²⁺ , Sr ²⁺ , Zn ²⁺ , Ba ²⁺ , Al ³⁺ , Fe ³⁺ , Cr ³⁺ , Co ³⁺ , Fe ²⁺ , La ³⁺ , Nd ³⁺ , Y ³⁺ , Zr ^{4+ and the} like. In order to contain these polyvalent metal ions in the treatment liquid, the polyvalent metal salt may be used.
The salt is a metal salt composed of the above polyvalent metal ions and an anion that binds to these ions, but is preferably soluble in a solvent. Here, the said solvent is a medium which comprises a process liquid with a polyvalent metal salt, for example, water and the organic solvent mentioned later are mentioned.

Preferred anions for forming a salt with the polyvalent metal ion include, for example, Cl ⁻ , NO ₃ ⁻ , I ⁻ , Br ⁻ , ClO ₃ ⁻ , CH ₃ COO ⁻ , SO ₄ ^{2− and the} like. .
A polyvalent metal ion and an anion can form a salt of a polyvalent metal ion and an anion, respectively, using a single species or a plurality of species.

  Examples of other polyvalent metal salts include polyaluminum hydroxide and polyaluminum chloride.

In the present invention, it is preferable to use a salt of a polyvalent metal ion and an anion from the viewpoints of reactivity, colorability, and ease of handling, and examples of the polyvalent metal ion include Ca ²⁺ and Mg ^2+. , Sr ²⁺ , Al ³⁺ and Y ³⁺ are preferable, and Ca ²⁺ is more preferable.
Further, as the anion, NO ₃ ⁻ is particularly preferable from the viewpoint of solubility and the like.
The said polyvalent metal salt can be used individually by 1 type or in mixture of 2 or more types.

Content of the said polyvalent metal salt is 15 mass% or more with respect to the total mass of the said process liquid. By setting the content of the polyvalent metal salt to 15% by mass or more, the components in the ink composition can be more effectively fixed.
The content of the polyvalent metal salt is preferably 15% by mass to 35% by mass with respect to the total mass of the treatment liquid.

The amount of the polyvalent metal salt applied to the recording medium is not particularly limited as long as it is an amount sufficient to aggregate the ink composition, but 0.5 g / m ² from the viewpoint that the ink composition can be easily fixed. it is preferably to 4.0 g / ^{m 2,} more preferably ^{0.9g / m 2 ~3.75g / m 2} .

-Cationic polymer-
The cationic polymer is at least one cationic polymer selected from poly (vinyl pyridine) salt, polyalkylaminoethyl acrylate, polyalkylaminoethyl methacrylate, poly (vinyl imidazole), polyethyleneimine, polybiguanide, and polyguanide. is there.
A cationic polymer may be used individually by 1 type, and may use 2 or more types together.
Among the cationic polymers, polyguanides (preferably poly (hexamethyleneguanidine) acetate, polymonoguanide, polymeric biguanide), polyethyleneimine, and poly (vinylpyridine), which are advantageous from the viewpoint of aggregation rate, are preferable.

  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 inkjet method, a range of 500 to 500,000 is preferable, a range of 700 to 200,000 is more preferable, and a range of 1,000 to 100,000 is more preferable. . When the weight average molecular weight is 500 or more, it is advantageous from the viewpoint of aggregation speed, 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.

  The treatment liquid contains a cationic polymer, but the pH (25 ° C.) of the treatment liquid is preferably 1.0 to 10.0, more preferably 2.0 to 9.0. More preferably, it is 0-7.0.

The content of the cationic polymer is preferably 1% by mass to 35% by mass, and more preferably 5% by mass to 25% by mass with respect to the total mass of the treatment liquid.
The amount of the cationic polymer applied to the coated paper is not particularly limited as long as it is an amount sufficient to stabilize the ink composition, but 0.5 g / m from the viewpoint that the ink composition is easily fixed. it is preferably ^{2 ~4.0g} / ^{m 2,} more preferably ^{0.9g / m 2 ~3.75g / m 2} .

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

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

  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 and number average molecular weight were 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". The acid value was determined by the method described in JIS standard (JIS K0070: 1992).
The volume average particle diameter of the particles was measured with a nanotrack particle size distribution measuring apparatus UPA-EX150 (manufactured by Nikkiso Co., Ltd.). The measurement was performed by adding 10 ml of ion-exchanged water to 100 μl of a 20% by weight particle aqueous dispersion to prepare a sample solution for measurement, and adjusting the temperature to 25 ° C.

<Preparation of ink composition>
(Composition of cyan ink C1)
Cyan ink C1 was prepared so as to have the following composition.
Cyan pigment (Pigment Blue 15: 3): 4% by mass
Acrylic polymer dispersant (acid value 65.2 mgKOH / g, weight average molecular weight 44600): 2% by mass
Acrylic polymer particles (weight average molecular weight 66000): 4% by mass
・ Sanix GP250: 10% by mass
(Sanyo Chemical Industry Co., Ltd., water-soluble organic solvent)
Tripropylene glycol monoethyl ether: 10% by mass
(Water-soluble organic solvent, manufactured by Wako Pure Chemical Industries, Ltd.)
・ Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd., surfactant): 1% by mass
・ Microcrystalline wax: 2% by mass
(HI-MIC1090 manufactured by Nippon Seiwa Co., Ltd.)
Ion exchange water was added to the above components to adjust to 100% by mass.

The acrylic polymer dispersant was synthesized according to the following scheme.
That is, 88 g of methyl ethyl ketone was added to a 1000 ml three-necked flask equipped with a stirrer and a condenser, 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 benzyl methacrylate. A solution in which 60 g, 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 in which 0.42 g of dimethyl 2,2′-azobisisobutyrate was dissolved in 2 g of methyl ethyl ketone was added, heated to 78 ° C. and heated for 4 hours. The obtained reaction solution was reprecipitated twice in a large excess of hexane, and the precipitated resin was dried to obtain 96 g of an acrylic polymer dispersant.
The composition of the obtained resin was confirmed by ¹ H-NMR, and the weight average molecular weight (Mw) determined by GPC was 44600. Furthermore, when the acid value of this acrylic polymer dispersant was determined by the method described in JIS standard (JISK0070: 1992), it was 65.2 mgKOH / g.

Acrylic polymer particles were synthesized according to the following scheme.
That is, 360.0 g of methyl ethyl ketone was charged into a reaction vessel formed of a 2 liter three-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube, and the temperature was raised to 75 ° C.
Next, while maintaining the temperature in the reaction vessel at 75 ° C., 180.0 g of phenoxyethyl acrylate, 162.0 g of methyl methacrylate, 18.0 g of acrylic acid, 72 g of methyl ethyl ketone, and “V-601” (Wako Pure Chemical Industries, Ltd.) (Manufactured) A mixed solution consisting of 1.44 g was added dropwise at a constant speed so that the addition was completed in 2 hours.
After completion of the dropwise addition, a solution consisting of 0.72 g of “V-601” and 36.0 g of methyl ethyl ketone was added, stirred for 2 hours at 75 ° C., and then a solution consisting of 0.72 g of “V-601” and 36.0 g of isopropanol 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.
The weight average molecular weight (Mw) of the obtained copolymer was 66000, and the acid value was 38.9 (mgKOH / g). The weight average molecular weight (Mw) was calculated in terms of polystyrene by gel permeation chromatography (GPC). The columns used were TSKgel SuperHZM-H, TSKgel SuperHZ4000, and TSKgel SuperHZ200 (manufactured by Tosoh Corporation).
Next, 668.3 g of the copolymer solution was weighed, 388.3 g of isopropanol and 145.7 ml of 1 mol / L NaOH aqueous solution were added, and the temperature in the reaction vessel was raised to 80 ° C. Next, 720.1 g of distilled water was added dropwise at a rate of 20 ml / min to disperse in water. Thereafter, the temperature in the reaction vessel was maintained at 80 ° C. for 2 hours, 85 ° C. for 2 hours, and 90 ° C. for 2 hours under atmospheric pressure, and then the reaction vessel was depressurized, and isopropanol, methyl ethyl ketone, and distilled water totaled 913. 7 g was distilled off. As a result, an aqueous dispersion (emulsion) of acrylic polymer particles having a solid content concentration of 28.0% was obtained.

(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.

<Preparation of treatment solution>
Each component was mixed so that it might become the following composition, and the process liquid was prepared.
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

  The physical properties of the treatment liquid were a viscosity of 2.6 mPa · s, a surface tension of 37.3 mN / m, and a pH of 1.6. 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.

<Example 1>
(Preparation of polymer-containing composition A)
A flask equipped with a stirrer, a thermometer, a reflux condenser, and a dropping funnel is charged with 100 mL of ion exchange water and 0.1 g of potassium persulfate, and the temperature in the flask reaches 70 ° C. while stirring in a nitrogen atmosphere. Until heated. Separately, 100 mL of ion-exchanged water, 1.0 g of sodium dodecylbenzenesulfonate, 30 g of styrene, 70 g of 2-ethylhexyl acrylate, and 5 g of methacrylic acid were placed in a reaction vessel to prepare an emulsion by stirring for 3 hours. Then, the said emulsion was dripped little by little in the said flask using the dropping funnel, and the stock solution of the polymer containing composition A was prepared.
After the stock solution of the polymer-containing composition A is cooled to room temperature, the stock solution of the polymer-containing composition A is filtered through a 0.4 μm filter, and distilled water is added so that the concentration of the polymer is 4%. Thus, a polymer-containing composition A was obtained. The glass transition temperature Tg (measured according to JIS K6900) of the polymer of the polymer-containing composition A was −5 ° C.

(Preparation of particle-containing composition A)
・ Isopropyl alcohol 45.0% by mass
・ Water 24.0% by mass
・ PMMA particles (Made by Soken Chemical Co., Ltd., MX-3000, volume average particle size 30 μm, Tg> 140 ° C.) 30.0% by mass
・ Orphine E1010 (manufactured by Sanyo Chemical Co., Ltd.) 1.0% by mass
1 L of the liquid having the above composition was mixed with a Silverson emulsifier at 1000 rpm for 60 minutes to prepare a particle-containing composition A.

(Image recording and evaluation)
As shown below, an image was formed using the ink C1 / M1 / Y1 / K1 / particle-containing composition A / polymer-containing composition A, and the following evaluation was performed. The evaluation results are shown in the following table.

-Image formation-
Prepare GELJET GX5000 printer head (Ricoh's full line head) and refill the storage tank connected to it with cyan ink C1, magenta ink M1, yellow ink Y1, black ink K1 and polymer-containing composition A obtained above. It was. A silver diamond (trade name, manufactured by Nippon Paper Industries Co., Ltd.) as a recording medium is fixed on a stage that can move in a predetermined linear direction at 500 mm / second, and the treatment liquid obtained above is fixed to about this with a wire bar coater. The film was applied to a thickness of 1.5 μm (corresponding to 0.34 g / m ^{2 of} malonic acid), and dried at 50 ° C. for 2 seconds immediately after the application.
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 system under ejection conditions of an ink droplet amount of 8.0 pL, an ejection frequency of 24 kHz, and a resolution of 1200 dpi × 600 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 70 ° C. for 7 seconds. Next, the particle-containing composition A was sprayed on the entire surface by spraying so that the particle-containing composition A would be 0.2 g / m ² .
The recording medium provided with the ink composition, the polymer-containing composition, and the particle-containing composition is passed between a pair of rollers heated to 60 ° C. (heating roller and pressure roller), and a nip pressure of 0.25 MPa. Then, a fixing treatment was performed with a nip width of 4 mm, and the polymer in the polymer-containing composition was converted into a film to obtain an evaluation sample. The heating roller (fixing roller) used was a SUS cylindrical core whose surface was covered with a silicone resin and a halogen lamp inside.

-Blocking evaluation-
Create two prints obtained, put the images together, press them for 1 minute under conditions of 100 N and 35 ° C. in an area of 0.5 cm × 3 cm, and then peel off the combined images to show the appearance of the images. It observed visually and evaluated according to the following 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: Strong sticking, high color transfer to each other's paper, and practically problematic level.

-Gloss evaluation-
The image portion of the obtained printed matter was visually observed, and the gloss was evaluated according to the following evaluation criteria before and after each particle dispersion was sprayed.
A: A big gloss change is not seen before and after particle dispersion liquid application.
B: A slight gloss change is observed before and after the application of the particle dispersion, but there is no practical problem.
C: Gloss change was observed before and after applying the particle dispersion, and there was a problem in practical use.

-Bleeding evaluation-
The obtained printed matter was magnified 50 times with a microscope to observe image bleeding and evaluated according to the following evaluation criteria.
A: The blur of the image on the printing surface was not visible at all.
B: Slight blurring of the image on the printed surface was visually recognized, but at a level where there was no practical problem.
C: A level where there is a problem in practical use because bleeding of the image on the printed surface can be visually recognized.

-Rubbing resistance evaluation-
Prepare a paperweight of 3 cm x 1 cm x 5 cm and 200 g for the printed matter obtained, wrap a matte paper silver diamond, and place it on the image so that the 1 cm x 5 cm part of the paperweight comes in contact with it. After rubbing 5 times, the appearance of the image was visually observed and evaluated according to the following evaluation criteria.
A: Image scraping on the printed surface was not visible at all.
B: Although the image on the printing surface was slightly scraped, it was at a level where there was no practical problem.
C: A level where there is a problem in practical use because the image on the printed surface can be visually confirmed.

<Example 2>
It implemented like Example 1 except using the following polymer containing composition B instead of the polymer containing composition A of Example 1. FIG. The glass transition temperature Tg (measured according to JIS K6900) of the polymer of the polymer-containing composition B was 85 ° C.
(Preparation of polymer-containing composition B)
・ Polyvinyl alcohol (“PVA117”, manufactured by Kuraray Co., Ltd.) 2.0 mass parts ・ Olfin E1010 (manufactured by Sanyo Chemical Co., Ltd.) 1.0 mass parts ・ Glycerin 5.0 mass parts ・ Triethylene glycol monobutyl ether 4.0 mass parts ・ Ion 88.0 parts by mass of exchange water Prepared by mixing so as to have the above composition.

<Example 3>
It implemented like Example 1 except using the following polymer containing composition C instead of the polymer containing composition A of Example 1. FIG. The glass transition temperature Tg (measured according to JIS K6900) of the polymer of the polymer-containing composition C was −44 ° C.
(Preparation of polymer-containing composition C)
Witcobond W-290H (manufactured by Witco Chemical, Tg-44 ° C.) 5.0 parts by mass Olfin E1010 (manufactured by Sanyo Chemical Co., Ltd.) 1.0 part by mass Glycerol 5.0 parts by mass Triethylene glycol monobutyl ether 4.0 Part by mass / ion exchange water 85.0 parts by mass Prepared by mixing so as to have the above composition.

<Example 4>
It implemented like Example 1 except using the following polymer containing composition D instead of the polymer containing composition A of Example 1. FIG. The polymer Tm (measured according to JIS K6900) of the polymer-containing composition D was 57 ° C.
(Preparation of polymer-containing composition D)
・ New Pole PE-108 (manufactured by Sanyo Kasei Co., Ltd.) (PEO-PPO-PEO) 2.0 mass parts ・ Olfin E1010 (manufactured by Sanyo Kasei Co., Ltd.) 1.0 mass parts ・ IPA 10.0 mass parts ・ Triethylene glycol mono 4.0 parts by mass of butyl ether and 83.0 parts by mass of ion-exchange water Prepared by mixing so as to have the above composition.
PEO means polyethylene oxide and PPO means polypropylene oxide.

<Example 5>
Instead of using PGP instead of PMMA in the particle-containing composition A of Example 3, SGP-70C (manufactured by Soken Chemical Co., Ltd., polystyrene, volume average particle size 20 μm, Tg> 140 ° C.) is used, except that the particle-containing composition B is used. The same operation as in Example 3 was performed.

<Example 6>
It implemented similarly to Example 3 except using the particle | grain containing composition C using SUNIL-150H-SC (SUNJIN CHEM., A silica, volume average particle diameter of 15 micrometers) instead of PMMA of Example 3. FIG.

<Example 7>
It implemented like Example 3 except using the particle-containing composition D which used YK-30 (Toyobo, volume average particle diameter 33 micrometers, polyacrylonitrile, Tg> 140 degreeC) instead of PMMA of Example 3. .

<Example 8>
Example 3 and Example 3 were used except that AR650MX (manufacturer: manufactured by Toyobo Co., Ltd., volume average particle size: 40 μm, component: PMMA, Tg> 140 ° C.) was used instead of PMMA in Example 3. It carried out similarly.

<Example 9>
Implementation was performed except that the particle-containing composition F using SGP-150C (manufacturer: manufactured by Soken Chemical Co., Ltd., volume average particle size: 55 μm, component: polystyrene, Tg> 140 ° C.) was used instead of PMMA in Example 3. Performed as in Example 3.

<Example 10>
Implementation was performed except that instead of PMMA in Example 3, MR-60G (manufacturer: manufactured by Soken Chemical Co., Ltd., volume average particle size: 60 μm, component: PMMA, Tg> 140 ° C.) was used. Performed as in Example 3.

<Example 11>
Example 3 was carried out in the same manner as Example 3 except that the application of the particle-containing composition on the image was performed as follows instead of spraying.
The web A was prepared by impregnating the particle-containing composition C into a non-woven fabric so as to be 30 g / m ² .
The web A is placed in contact with the heating roller, the recording medium is passed between a pair of rollers heated to 60 ° C. (heating roller and pressure roller), and fixed at a nip pressure of 0.25 MPa and a nip width of 4 mm. The process was implemented and the evaluation sample was obtained.
The heating roller (fixing roller) used was a SUS cylindrical core whose surface was covered with a silicone resin and a halogen lamp inside.

<Example 12>
In Example 3, the application of the polymer-containing composition was performed in the same manner as in Example 3 except that the application of the polymer-containing composition was performed after the application of the particle-containing composition.

<Comparative Example 1>
In Example 3, it implemented like Example 3 except not using the polymer containing composition C.

<Comparative example 2>
In Example 3, it carried out like Example 3 except not using particle-containing composition A.

  From the above, it has been found that according to the present invention, blocking can be improved while suppressing blurring of images and changes in gloss. Furthermore, since the present invention uses a water-soluble ink composition and a particle-containing composition, it has become possible to reduce the burden on the environment. In addition, by applying the particle-containing composition on the image with a heating roller in the present invention, it is possible to simultaneously perform the particle applying step and the film forming step, further preventing blocking, blurring of the image, and gloss change. I found that it can be improved.

Claims (6)

An image recording step of recording an image on a recording medium by an ink jet method using an ink composition containing water and a pigment;
A particle applying step of applying a particle-containing composition containing water and a crosslinked organic particle or inorganic particle having a volume average particle diameter of 15 μm to 60 μm on the image;
A polymer application step of applying a polymer-containing composition containing a polymer on the image;
An image forming method including a film forming step of forming the polymer into a film.   The image forming method according to claim 1, wherein the crosslinked organic particles in the particle-containing composition are particles containing poly (meth) acrylate, polystyrene, polyacrylonitrile, or polyethylene.   The image forming method according to claim 1, wherein the inorganic particles in the particle-containing composition are silica particles.   The image forming method according to claim 1, wherein the volume average particle diameter of the crosslinked organic particles or inorganic particles in the particle-containing composition is 20 μm to 40 μm.   The image forming method according to any one of claims 1 to 4, wherein a lower glass transition temperature Tg or melting point Tm of the polymer is -50 ° C to 90 ° C.   The image formation according to any one of claims 1 to 5, wherein the particle applying step is a step of supplying the particle-containing composition to a surface of a heating roller and pressing the heating roller against the recording medium. Method.