JP2011212937A - Image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method suppressing the fixing offset of an image part while achieving excellent glossiness of an image when the image is formed on a recording medium by an ink jet method.SOLUTION: The image forming method includes an ink feeding step for feeding an ink composition on the recording medium by the ink jet method, and a dispersion liquid feeding step for feeding a particulate dispersion liquid on the recording medium with the ink composition. The particulate dispersion liquid includes fine particles with the size of 1 μm or more and 30 μm or less, and an nonvolatile organic solvent. A solubility parameter (an SP value) of the nonvolatile organic solvent falls within the range of 13-24 (MPa).

Description

  The present invention relates to an image forming method using an inkjet method.

  Inkjet technology has been applied as an image forming method for forming color images in the fields of office printers, home printers, and the like. In the image forming method using the ink jet method, a fixing process using a fixing roller or the like may be performed for improving the abrasion resistance of the image, but the image portion on the recording medium is transferred to the fixing roller or the like. May occur (referred to as “fixing offset”).

  In addition, when the recording media after image formation are stacked, a phenomenon may occur in which the recording media adhere to each other and the ink in the image portion adheres to the back surface of the recording medium. As a technique for suppressing this phenomenon, Patent Document 1 discloses that a liquid containing fine powder particles is deposited on a paper surface, and Patent Document 2 discloses a method in which a resin liquid containing resin particles is applied to a recording surface. Forming a resin film is disclosed.

JP-A-62-246730 JP 2004-50751 A

  However, in each technique disclosed in Patent Documents 1 and 2, no consideration has been given to reducing the fixing offset that occurs when an image is fixed. Furthermore, in each of the above technologies, no consideration has been given to improving the glossiness of the formed image. In particular, the technology for forming a resin film on the recording surface described in Patent Document 2 is extremely inconspicuous from the viewpoint of glossiness. Only enough can be obtained.

  The present invention has been made in view of the above, and when forming an image on a recording medium by an inkjet method, an image forming method capable of suppressing the fixing offset of the image portion with good glossiness of the image. It is an object to provide this and to achieve the object.

Specific means for achieving the above object are as follows.
<1> An ink application step of applying an ink composition onto a recording medium by an inkjet method, and a dispersion applying step of applying a fine particle dispersion onto the recording medium applied with the ink composition, the fine particle dispersion The liquid has fine particles of 1 μm or more and 30 μm or less and a non-volatile organic solvent, and the solubility parameter (SP value) of the non-volatile organic solvent is in the range of 13 to 24 (MPa) ^1/2. It is a forming method.
<2> The image forming method according to <1>, wherein the solubility parameter (SP value) of the fine particles and the nonvolatile organic solvent is in the range of 13 to 24 (MPa) ^1/2 .
<3> The image forming method according to <1> or <2>, wherein the solubility parameter (SP value) is in a range of 18 to 23 (MPa) ^1/2 .

<4> The image forming method according to any one of <1> to <3>, wherein the nonvolatile organic solvent has a boiling point of 150 ° C. or higher at 1 atmosphere.
<5> The nonvolatile organic solvent includes at least one selected from a silicone-based organic solvent, a halogen-based organic solvent, and a polyether-based organic solvent, and any one of <1> to <4> The image forming method described in 1. above.
<6> The image forming method according to any one of <1> to <5>, wherein the fine particles are contained in the fine particle dispersion in an amount of 5% by mass to 50% by mass.

<7> The image forming method according to any one of <1> to <6>, wherein the fine particles include a structure represented by the following general formula (1).

In the general formula (1), n represents an integer of 10 ≦ n ≦ 1000, R ¹ represents a hydrogen atom or a methyl group, and R ² represents —COOX or an aromatic ring. X represents a C1-C8 alkyl group.

<8> The image forming method according to <7>, wherein the fine particles are polymethyl (meth) acrylate.

  According to the present invention, when an image is formed on a recording medium by an inkjet method, it is possible to provide an image forming method in which the glossiness of the image is good and the fixing offset of the image portion can be suppressed. .

The image forming method of the present invention includes an ink application step of applying an ink composition onto a recording medium by an inkjet method, and a dispersion application step of applying a fine particle dispersion onto the recording medium applied with the ink composition. And the fine particle dispersion has fine particles of 1 μm or more and 30 μm or less and a non-volatile organic solvent, and the solubility parameter (SP value) of the non-volatile organic solvent is in the range of 13 to 24 (MPa) ^1/2. It is characterized by.
By adopting such a configuration, the image forming method of the present invention has good glossiness of the image and can suppress the fixing offset of the image portion.

In the image forming method of the present invention, a fine particle dispersion is applied in a dispersion applying step described later. First, the fine particle dispersion used in the present invention will be described.
<Fine particle dispersion>
The fine particle dispersion contains at least one kind of fine particles having a volume average particle diameter of 1 μm or more and 30 μm or less and at least one kind of nonvolatile organic solvent, and may contain other components as necessary. it can. The nonvolatile organic solvent in the present invention refers to an organic solvent having a boiling point of 150 ° C. or higher at 1 atmosphere.

[Fine particles]
The fine particles used in the present invention have a volume average particle diameter of 1 μm or more and 30 μm or less. By setting the volume average particle size in the above range, fixing offset of the image portion can be suppressed. The volume average particle diameter is preferably 2 μm or more and 15 μm or less, and more preferably 4 μm or more and 12 μm or less from the viewpoint of further reducing the fixing offset.
In the present invention, the volume average particle diameter of the fine particles is a value measured by a nanotrack particle size distribution measuring apparatus UPA-EX150 (manufactured by Nikkiso Co., Ltd.). The measurement is performed by adding 10 ml of ion-exchanged water to 100 μl of a 20% by mass powder particle aqueous dispersion to prepare a sample solution for measurement, and adjusting the temperature to 25 ° C.

In the present invention, the fine particles are used in a state of being dispersed in a liquid containing the nonvolatile organic solvent (fine particle dispersion).
The fine particles may be either poorly water-soluble or water-insoluble, but in the present invention it is preferably water-insoluble. Thereby, it is possible to effectively prevent the deterioration of the image quality caused by the dissolution or penetration of the fine particles inside the image when the fine particles are applied on the recorded image. In the present invention, the term “insoluble in water” means that the amount dissolved in 100 parts by mass (25 ° C.) of water is less than 0.5 parts by mass.

As the fine particles, either inorganic fine particles or organic fine particles can be used.
Examples of the inorganic fine particles include calcium carbonate, titanium oxide, silica (silicon dioxide), lithium fluoride, calcium fluoride, barium sulfate, alumina (aluminum oxide), zirconia (zirconium oxide), calcium phosphate, and magnesium oxide. From the viewpoint of improving the gloss of the image, silica, calcium carbonate, alumina, zirconia, and titanium oxide are more preferable.

  Examples of the organic fine particles include, but are not limited to, vinyl polymers, ester polymers, and the like. From the viewpoint of further reducing the fixing offset of the image area and maintaining the glossiness of the image, the vinyl-based polymer. Polymers are preferred. Moreover, as a vinyl polymer, it is more preferable from said viewpoint that the structure represented by following General formula (1) is included.

In the general formula (1), R ¹ represents a hydrogen atom or a methyl group, and R ² represents —COOX or an aromatic ring. X represents a C1-C8 alkyl group. n represents an integer of 10 or more and 1000 or less.
The aromatic ring of R ^2, but not limited to, a phenyl group, a naphthyl group are preferred, the phenyl group is particularly preferred.
As X, a C1-C6 alkyl group is more preferable, and a C1-C4 alkyl group is more preferable. More specifically, X is preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a 2-ethylhexyl group, or the like, preferably a methyl group, an ethyl group, A propyl group, an isopropyl group, a butyl group, a pentyl group, and a hexyl group are more preferable, and a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group are particularly preferable.
n is preferably 20 ≦ n ≦ 800, and more preferably 20 ≦ n ≦ 600.

  Specific examples of the vinyl polymer having the structure represented by the general formula (1) include polymethyl methacrylate (PMMA: SP value 19.50, Tg: 105 ° C.), polymethyl acrylate (SP value 19. 71, Tg: 32 ° C., polybutyl methacrylate (SP value 18.33, Tg: 15 ° C.), polystyrene (SP value 18.54, Tg: 110 ° C.) and the like. Among the above, polymethyl methacrylate, polymethyl acrylate, and polystyrene are preferable, and polymethyl methacrylate is particularly preferable. Hereinafter, polymethyl methacrylate (PMMA) and polymethyl acrylate are collectively referred to as polymethyl (meth) acrylate.

As the fine particles, any of the above-mentioned inorganic fine particles and organic fine particles can be used, but organic fine particles are preferable, and in particular, the solubility parameter (SP value) is in the range of 13 to 24 (MPa) ^1/2 . Certain organic fine particles are preferable, and organic fine particles having a solubility parameter (SP value) in the range of 18 to 23 (MPa) ^1/2 are more preferable.
By setting the solubility parameter (SP value) of the fine particles within the above range, the adhesion of the fine particles to the image area is controlled to an appropriate range, and the fixing offset of the image area is further reduced, and the glossiness of the image area is improved. It can be kept better.
The solubility parameter (SP value) in the present invention is a value represented by the square root of the molecular cohesive energy. The theoretical formula of the SP value can be found in the Journal of the Adhesion Society of Japan Vol. 29, no. 6 (1993) p. 249-259, and the calculated value is the SP value in the present invention. Moreover, a unit is (MPa) ^1/2 and points out the value in 25 degreeC.

Furthermore, the glass transition temperature (Tg) of the fine particles is preferably 80 ° C. or higher and 300 ° C. or lower, and more preferably 100 ° C. or higher and 300 ° C. or lower. By setting the glass transition temperature (Tg) within this range, fine particles having an appropriate hardness can be obtained, and the effects of the present invention can be further improved.
In the present invention, the measurement Tg obtained by actual measurement is applied as the glass transition temperature (Tg) of the fine particles. Specifically, the measurement Tg means a value measured under normal measurement conditions using a differential scanning calorimeter (DSC) EXSTAR 6220 manufactured by SII Nanotechnology. Here, the measurement is performed by raising the temperature from 0 ° C. to 300 ° C. at 5 ° C./5 minutes.
However, when measurement is difficult due to polymer decomposition or the like, calculation Tg calculated by the following calculation formula is applied. Calculation Tg is calculated by the following formula (S).
1 / Tg = Σ (X _i / Tg _i ) Equation (S)
Here, it is assumed that n types of monomer components from i = 1 to n are copolymerized in the polymer to be calculated. 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 monomer. However, Σ is the sum from i = 1 to n. The homopolymer glass transition temperature (Tg _i ) of each monomer is the value of Polymer Handbook (3rd Edition) (by J. Brandrup, EH Immergut (Wiley-Interscience, 1989)).

As the fine particles, a vinyl polymer having a structure represented by the general formula (1) and having a solubility parameter (SP value) in the range of 13 to 24 (MPa) ^1/2 is preferable. A vinyl polymer having a temperature (Tg) in the range of 80 ° C. or higher and 300 ° C. or lower is more preferable.

  The content of the fine particles in the fine particle dispersion is not limited, but is preferably 5% by mass to 50% by mass, more preferably 10% by mass to 40% by mass with respect to the total mass of the fine particle dispersion. Mass% to 35 mass% is particularly preferable. The effect of this invention can be improved more by making content of the said fine particle into this range.

[Non-volatile organic solvent]
The fine particle dispersion in the present invention contains at least one nonvolatile organic solvent having a solubility parameter (SP value) in the range of 13 (MPa) ^1/2 or more and 24 (MPa) ^1/2 or less. By selecting an organic solvent having a solubility parameter (SP value) in this range, the dispersibility of the fine particles is enhanced, and the adhesion of the fine particles to the recording medium is controlled to an appropriate range, so that the fixing offset of the image portion is reduced. To suppress the glossiness of the image area.
The solubility parameter (SP value) of the non-volatile organic solvent is set to 18 to 23 (MPa) ^1/2 from the viewpoint of further reducing the fixing offset of the image portion and keeping the glossiness of the image better. Is preferred. The definition of the solubility parameter (SP value) is synonymous with the solubility parameter (SP value) of the fine particles described above.

  The non-volatile organic solvent in the present invention has a boiling point of 150 ° C. or more at 1 atmosphere. The non-volatile organic solvent is preferably an organic solvent having a boiling point of 200 ° C. or more, particularly preferably a boiling point from the viewpoint of further reducing the fixing offset of the image area and maintaining the glossiness of the image better. Is an organic solvent at 300 ° C. or higher.

  The non-volatile organic solvent preferably has a viscosity of 50 cp to 100,000 cp. More preferably, they are 100 cp or more and 100,000 cp or less, Most preferably, they are 100 cP or more and 10000 cP or less. The viscosity of the non-volatile organic solvent can be measured at 25 ° C. using a Brookfield digital viscometer (LVDV-I +, manufactured by Brookfield).

The nonvolatile organic solvent is not particularly limited as long as the solubility parameter (SP value) satisfies the range of 13 to 24 (MPa) ^1/2 and the fine particles can be dispersed. However, the solvent itself is polymerizable. It is preferably selected from those having no group and no film-forming property.
As the non-volatile organic solvent, it is preferable to use at least one selected from a silicone-based organic solvent, a halogen-based organic solvent, and a polyether-based organic solvent from the above viewpoints. More preferably, the organic solvent is at least one selected from organic solvents.

  As a preferable example of a silicone type organic solvent, what contains a siloxane structure is preferable, and can specifically illustrate the copolymer containing the structure represented by the following general formula (2-1).

In the general formula (2-1), A represents the following general formula (A-1) or general formula (A-2). In the following general formula (A-1) and general formula (A-2), the wavy line represents the bonding position with the Si atom.
k, l, m, and n represent integers, and 20 ≦ k + 1 + m + n ≦ 1000.

  In the general formula (2-1), k, l, m, and n are 20 ≦ k + 1 + m + n ≦ 1000, and preferably 50 ≦ k + 1 + m + n ≦ 1000.

  Specific examples of the copolymer including the structure represented by the general formula (2-1) include KF-352A (SP value 16.27 to 20.62, viscosity 1553 cP), KF-353 (SP value 16. 27 to 20.62, viscosity 414 cP), KF-354L (SP value 16.27 to 20.62, viscosity 182 cP), KF-355A (SP value 16.27 to 20.62, viscosity 140 cP), KF-615A ( SP value 16.27 to 20.62, viscosity 876 cP), KF-945 (SP value 16.27 to 20.62, viscosity 130 cP), X-22-4515 (SP value 16.27 to 20.62, viscosity 3884 cP) ) And the like. All of the above specific examples are manufactured by Shin-Etsu Chemical Co., Ltd.

Preferable examples of the halogen-based organic solvent include organic solvents having a structure represented by the following general formula (2-2).
_{C x H (2x + 2-} y) B y ··· formula (2-2)

In the general formula (2-2), x represents an integer of 10 to 15, y represents an integer of 1 to 20, and B represents a fluorine atom or a chlorine atom.
The structure represented by the general formula (2-2) is preferably a structure in which B is a chlorine atom, x is an integer of 10 to 15, and y is an integer of 1 to 10.

  Specific examples of the halogen-based organic solvent containing the structure represented by the general formula (2-2) include 1-fluorodecane (SP value 15.6), lauryl fluoride (SP value 15.7), octyl chloride. (SP value 17.5), 1-chlorodecane (SP value 17.3), lauryl chloride (SP value 17.2), chlorinated paraffin (SP value 22.9) and the like, more preferably octyl chloride ( SP value 17.5), 1-chlorodecane (SP value 17.3), lauryl chloride (SP value 17.2), chlorinated paraffin (SP value 22.9) and the like.

  Preferable examples of the polyether-based organic solvent include organic solvents containing at least one of the structures represented by the following general formula (2-3) and general formula (2-4).

  In the general formulas (2-3) and (2-4), q and r each independently represent an integer of 10 to 400.

In the organic solvent including at least one of the structures represented by the general formula (2-3) and the general formula (2-4), q and r are preferably integers of 10 to 400, and are integers of 30 to 300. It is more preferable that Specific examples include polyethylene glycol (SP value 20.6), polypropylene glycol (SP value 17.9), polyethylene glycol / polypropylene glycol diblock polymer (SP value 17.9 to 20.6), polyethylene glycol / Polypropylene glycol / polyethylene glycol triblock copolymer (SP value 17.9 to 20.6, for example, New Pole PE-62 (manufactured by Sanyo Chemical Industries, Ltd., SP value 18.6)), polypropylene glycol / polyethylene Examples thereof include a glycol / polypropylene glycol triblock copolymer (SP value: 17.9 to 20.6) and dipropylene glycol (SP value: 23.0).
Among the above specific examples, polyethylene glycol, polypropylene glycol, polyethylene glycol / polypropylene glycol diblock polymer, polyethylene glycol / polypropylene glycol / polyethylene glycol triblock copolymer (for example, New Pole PE-62), polypropylene glycol / Polyethylene glycol / polypropylene glycol triblock copolymer and the like are preferable, and a polyethylene glycol / polypropylene glycol diblock polymer and a polyethylene glycol / polypropylene glycol / polyethylene glycol triblock copolymer ( For example, New Pole PE-62).

In the fine particle dispersion in the present invention, the solubility parameter (SP value) of the fine particles and the nonvolatile organic solvent is preferably 13 to 24 (MPa) ^1/2, and both are 18 to 23 (MPa) ^{1/2. 2} is more preferable. Thereby, the dispersibility of the fine particles is suitably maintained, and the adhesion of the fine particles to the image area and the adhesion of the fine particle dispersion itself to the recording medium are controlled within an appropriate range, thereby fixing the image area. The offset property can be further reduced, and the glossiness of the image portion can be kept better.

  The content of the nonvolatile organic solvent in the fine particle dispersion is preferably 50% by mass to 95% by mass, more preferably 60% by mass to 90% by mass, and particularly preferably 65% by mass to 87% by mass. preferable. By making content of the said non-volatile organic solvent into this range, the effect of this invention can be improved more.

[Other additives]
The fine particle dispersion in the present invention can be constituted using other additives in addition to the fine particles and the nonvolatile organic solvent. Other additives include, for example, dispersants, emulsifiers, drying inhibitors (wetting agents), antifading agents, emulsion stabilizers, ultraviolet absorbers, preservatives, antifungal agents, pH adjusters, surface tension adjusters, Well-known additives, such as an antifoamer, a viscosity modifier, a dispersion stabilizer, a rust preventive agent, and a chelating agent, are mentioned.

  The fine particle dispersion in the present invention can be obtained by mixing the above-described components and appropriately selecting and dispersing a known method such as a Silverson mixer, a ball mill, a bead mill, or an ultrasonic wave. The order of addition of each component is not particularly limited, but it is preferable to add the fine particles and other additives to the nonvolatile organic solvent.

Next, details of each step included in the image forming method of the present invention will be described.
≪Ink application process≫
The ink application process in the present invention is a process for recording an image by applying an ink composition onto a recording medium by an ink jet method.

  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 method in which a signal is converted into an acoustic beam and ink is ejected by using the radiation pressure, and ink is ejected, and thermal ink jet (Bubble Jet (registered trademark)) that uses the pressure generated by heating the ink to form bubbles. )) Any method 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 of the present invention can be applied to any of these, but in general, when applied to a line system that does not use a dummy jet, the ejection accuracy and image scratch resistance are good.

  The amount of ink droplets 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. .

<Recording medium>
The recording medium used in the present invention is not particularly limited, but general printing paper mainly composed of cellulose, such as so-called high-quality paper, coated paper, art paper, matte paper, etc., used for general offset printing or the like is used. Can do.

  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. N) Silver diamond made by Nippon Paper Industries Co., Ltd. It is. 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 (also referred to as “ink”) used in the present invention is not limited as long as it contains a coloring material and water, and a known or commercially available one can be used.

[Color 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, quinophthaloni pigments, basic Examples include dye lakes such as dye-type lakes and acid dye-type lakes, organic pigments such as nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments, and inorganic pigments such as titanium oxide, iron oxide, and carbon black. Any pigment not described in the color index can be used as long as it can be dispersed in the aqueous phase. Further, it is of course possible to use a pigment whose surface is treated with a surfactant, a polymer dispersing agent or the like, or graft carbon. Among the pigments, it is particularly preferable to use an azo pigment, a phthalocyanine pigment, an anthraquinone pigment, a quinacridone pigment, or a carbon black pigment.

Specific examples of the organic pigment used in the present invention are shown below. 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 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.

  When the color material in the present invention is a pigment, it 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 or less mgKOH / g or less from the viewpoint of good cohesiveness when the treatment liquid described later contacts. Furthermore, the acid value is more preferably 25 to 100 mgKOH / g, and further preferably 30 to 90 mgKOH / g.

  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 in terms of volume average particle diameter. 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 average particle diameter of the color material particles is determined by measuring the volume average particle diameter by a dynamic light scattering method using a nanotrack particle size distribution measuring apparatus UPA-EX150 (manufactured by Nikkiso Co., Ltd.). 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 content of the color material in the ink is preferably 1 to 25% by mass and more preferably 2 to 20% by mass with respect to the ink from the viewpoint of image density.

[Polymer particles]
The ink used 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 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, ethacrylic acid, propylacrylic acid, isopropylacrylic acid, itaconic acid, fumaric acid and the like), and acrylic acid or methacrylic acid is particularly preferred. 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 is preferably 1 to 30% by mass and more preferably 3 to 20% by mass with respect to the total mass of the ink from the viewpoint of glossiness of the image and the like. .

[water]
The ink 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.

[Organic solvent]
The ink may contain a water-soluble organic solvent in addition to the water as necessary. As such a water-soluble organic solvent, alkyleneoxy alcohol is preferable from the viewpoint of dischargeability. Furthermore, it is particularly preferable to contain two or more hydrophilic organic solvents 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.
In addition to the above hydrophilic organic solvent, other organic solvents may be contained as necessary for the purpose of preventing drying, promoting penetration, adjusting viscosity, and the like.

[Other additives]
In addition to the above components, the ink may 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 is prepared, or may be added when the ink is prepared.

≪Dispersion application process≫
The dispersion applying step in the present invention is a step of applying the fine particle dispersion described above on the recording medium provided with the ink composition described above. In the dispersion applying step, the fine particle dispersion described above is applied on the image recorded in the ink applying step. The fine particle dispersion may be applied to at least the image recorded by the ink application process, and the fine particle dispersion may be applied to the entire image forming surface of the recording medium.

The method for applying the fine particle dispersion onto the image is not particularly limited. For example, a method of applying the fine particle dispersion by spraying or a method of applying through a member such as a roller supplied with the fine particle dispersion can be employed.
The fine particle dispersion may be supplied to a member such as a roller by attaching the fine particle dispersion directly or indirectly to a member such as a roller. For example, a method of bringing the cloth material (web member) impregnated with the fine particle dispersion into contact with the roller surface, a method of spraying the fine particle dispersion onto the roller surface, and a method of applying the fine particle dispersion to the roller surface with a roll coater Etc.

  The dispersion applying step in the present invention may be performed integrally with a fixing step described later. That is, the dispersion applying step and the fixing step are simultaneously performed by supplying the fine particle dispersion to the pressure-bonding member to be pressed onto the image in the fixing step and pressing the pressure-sensitive member supplied with the fine particle dispersion onto the image. It is possible to implement. Details of this embodiment will be described later.

The amount of the fine particle dispersion applied is not limited, but the amount of the fine particles described above contained in the fine particle dispersion is preferably 0.1 to 1000 / m ² , preferably 1 to 500. / M ² is more preferable. The amount of the fine particles applied can be appropriately adjusted depending on the amount of the fine particles to be dispersed in the fine particle dispersion, the supply amount of the fine particle dispersion to the roller, and the like. In the method in which the cloth material impregnated with the fine particle dispersion is brought into contact with the roller surface, it can be adjusted by the amount of the fine particle dispersion impregnated into the cloth material, the feed amount of the cloth material, and the like.

  In the image forming method of the present invention, the drying step may be performed by providing an apparatus such as an ink drying zone between the ink applying step and the dispersion applying step or after the dispersion applying step.

≪Fixing process≫
The image forming method of the present invention may include a fixing step of fixing an image by pressing a pressure-bonding member onto the image recorded by the ink applying step. In this step, a pressure-bonding member having pressure applying means for applying pressure to the image portion is fixed (fixing process) by pressing the image portion while being pressed against the image portion. Examples of the pressure applying means include a pair of rolls and a pressure plate that are in pressure contact with each other.

  The fixing step in the present invention is preferably a step in which the image portion is pressurized and heated at the same time. In this case, the fixing step is a step of fixing the pressure member by combining the pressure applying unit and the heating unit that heats the image portion by pressing the image portion and pressurizing and heating the image portion. Can do. Examples of the heating means include a heating roller and a hot plate. Specifically, the surface of the recording medium can be pressed with a heating roller or a hot plate.

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 surface temperature (heating temperature) of the heating roller is preferably set to a temperature at which the polymer particles in the ink composition can be formed into a film, for example, about 30 to 120 ° C., preferably about 50 to 90 ° C. Thereby, the film | membrane intensity | strength of an image can be improved.

In the image forming method of the present invention, the fine particle dispersion is supplied to the pressure-bonding member to be pressed onto the image in the fixing step, and the pressure-sensitive member supplied with the fine particle dispersion is pressure-contacted onto the image to thereby apply the dispersion. The process and the fixing process may be performed simultaneously.
For example, the fine particle dispersion can be supplied to the surface of the heating roller, and the heating roller can be pressed against the image portion to simultaneously perform the dispersion applying step and the fixing step. In this case, since the heating roller can serve as a roller for applying the fine particle dispersion and a roller for performing a fixing process, separate rollers are required for the dispersion applying step and the fixing step. Instead, the image forming speed can be increased and the equipment can be downsized.

  In the dispersion applying step, for example, the fine particles adhering to the roller surface can be applied to the surface of the printed material by pressing a heating roller against a recording medium (printed material) on which the image is recorded. 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 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 (Iv) a combination of these methods, and the like.

  The fine particle dispersion may be supplied to the heating roller by adhering the fine particle dispersion directly or indirectly to the heating roller. For example, a method of bringing the cloth material (web member) impregnated with the fine particle dispersion into contact with the surface of the heating roller, a method of spraying the fine particle dispersion onto the surface of the heating roller, and the fine particle dispersion on the surface of the heating roller with a roll coater. The method of apply | coating etc. are mentioned. In the embodiment using the cloth material (web member), the material of the web member may be any of a woven fabric, a non-woven fabric, etc., and a commercially available or known material may be used. Vinylidene chloride, polyethylene, aramid, polyester, etc.). The details and preferred embodiments of the heating roller used above are as described above.

  The fine particles contained in the fine particle dispersion preferably do not form a film on an image, and preferably have a particulate shape. In the fixing step, the pressure when contacting the pressure-bonding member is not limited, but it is preferably performed under a pressure that does not destroy the fine particles. As such a pressure, for example, a range of 0.1 MPa to 3.0 MPa is preferable, a range of 0.1 MPa to 1.0 MPa is more preferable, and a range of 0.1 MPa to 0.5 MPa is further preferable. .

  A preferable nip time when the recording medium passes through a fixing roll (preferably a heating roll) is 1 millisecond to 10 seconds, more preferably 2 milliseconds to 1 second, and further preferably 4 milliseconds. ~ 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 to 700 mm / second, more preferably 300 to 650 mm / second, and still more preferably 400 to 600 mm / second.

≪Processing liquid application process≫
The image forming method of the present invention may include a treatment liquid application step for applying the treatment liquid to the recording medium. 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 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.

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

The 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, it is preferable in terms of gloss.

<Processing liquid>
The treatment liquid used in the treatment liquid application step 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).

  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 may further comprise an aqueous solvent (for example, water) in addition to the acidic compound.
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%, Most preferably, it is 18-30 mass%.

  Moreover, the process liquid which added polyvalent metal salt or polyallylamine is mentioned, and a 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), salts of lanthanides (for example, neodymium), polyallylamine, and polyallylamine derivatives. 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. When the weight average molecular weight is 1000 or more, it is advantageous from the viewpoint of the aggregation rate, and when it is 500,000 or less, it is advantageous from the viewpoint of ejection reliability. However, this is not the case when the treatment liquid is applied to the recording medium by a method other than inkjet.

Furthermore, as the cationic organic compound, for example, a primary, secondary, or tertiary amine salt type compound is preferable. Examples of the amine salt type compounds include compounds such as hydrochloride or acetate (for example, laurylamine, cocoamine, stearylamine, rosinamine), quaternary ammonium salt type compounds (for example, lauryltrimethylammonium chloride, cetyltrimethyl). Ammonium chloride, lauryldimethylbenzylammonium chloride, benzyltributylammonium chloride, benzalkonium chloride, etc.), pyridinium salt type compounds (eg, cetylpyridinium chloride, cetylpyridinium bromide, etc.), imidazoline type cationic compounds (eg, 2-heptadecenyl- Hydroxyethyl imidazoline etc.), ethylene oxide adducts of higher alkylamines (eg dihydroxyethyl stearylamine etc.), etc. 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.

  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.).

  The treatment liquid 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 additive include an anti-drying agent (wetting agent), an anti-fading agent, an emulsion stabilizer, a penetration enhancer, an ultraviolet absorber, an antiseptic, an antifungal agent, a pH adjuster, a surface tension adjuster, and an antifoaming agent. Known additives such as additives, viscosity modifiers, dispersants, dispersion stabilizers, rust inhibitors, chelating agents and the like, and specific examples of other additives contained in the ink composition described above Things can be applied.

  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, “%” and “part” are 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". The acid value was determined by the method described in JIS standard (JIS K0070: 1992).
The volume average particle diameter 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 exchange water to 100 μl of a 20% by mass powder particle aqueous dispersion to prepare a sample solution for measurement, and adjusting the temperature to 25 ° C.

<Preparation of ink composition>
(Preparation of cyan ink C1)
Cyan ink C1 was prepared by mixing the components so as to have the following composition.
・ Cyan pigment (Pigment Blue 15: 3) ... 4%
・ Acrylic polymer dispersant: 2%
(Acid value 65.2 mgKOH / g, weight average molecular weight 44600)
・ Aqueous dispersion of acrylic polymer particles (solid content) 4%
(Weight average molecular weight 66000)
・ Sanix GP250 (water-soluble organic solvent, manufactured by Sanyo Chemical Industries) ... 10%
・ Tripropylene glycol monoethyl ether: 10%
(Water-soluble organic solvent, manufactured by Wako Pure Chemical Industries, Ltd.)
・ Orphine E1010 (surfactant, manufactured by Nissin Chemical Industry Co., Ltd.) ... 1%
・ Microcrystalline wax (HI-MIC1090 manufactured by Nippon Seiwa Co., Ltd.) 2%
・ Ion-exchanged water: Amount that is 100% in total

(Preparation of magenta ink M1)
Magenta ink M1 was prepared in the same manner as 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. did.

(Preparation of yellow ink Y1)
The yellow ink Y1 was prepared in the same manner as 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. did.

(Composition of black ink K1)
A black ink K1 was prepared in the same manner as 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%
・ Diethylene glycol monomethyl ether (Wako Pure Chemical Industries, Ltd.)… 20.0%
・ N-oleoyl-N-methyl taurine sodium (surfactant) 1.0%
・ Ion-exchanged water: 64.0%

  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.

<Preparation of fine particle dispersion>
(Fine particle dispersion 1)
1 L of the liquid having the following composition was mixed at 1000 rpm for 60 minutes using a Silverson emulsifier to prepare a fine particle dispersion 1.
・ Chlorinated paraffin (chlorination rate 40%) ... 87.0%
(Non-volatile organic solvent, manufactured by Wako Pure Chemical Industries, Ltd.)
・ Polymethyl methacrylate (PMMA) particles (average particle size 8 μm) 13.0%
(MX-801 manufactured by Soken Chemical Co., Ltd.)

(Fine particle dispersion 2)
In the fine particle dispersion 1, fine particle dispersion was performed in the same manner as the fine particle dispersion 1, except that the paraffin chloride was changed to polyoxyethylene-polyoxypropylene-block polymer (PE-62 manufactured by Sanyo Chemical Industries). Liquid 2 was prepared.

(Fine particle dispersion 3)
A fine particle dispersion 3 was prepared in the same manner as in the fine particle dispersion 1, except that in the fine particle dispersion 1, the chlorinated paraffin was changed to polypropylene glycol (number average molecular weight 2700, manufactured by Sigma-Aldrich Japan).

(Fine particle dispersion 4)
A fine particle dispersion 4 was prepared in the same manner as the fine particle dispersion 1, except that the paraffin chloride was changed to polyethylene glycol (number average molecular weight 300, manufactured by Wako Pure Chemical Industries, Ltd.) in the fine particle dispersion 1. .

(Fine particle dispersion 5)
A fine particle dispersion 5 was prepared in the same manner as the fine particle dispersion 1, except that in the fine particle dispersion 1, polymethyl methacrylate (PMMA) particles were changed to silica particles (SUNSIL 130sc manufactured by SUNJIN CHEMICAL).

(Fine particle dispersion 6)
In the fine particle dispersion 1, the same procedure as in the preparation of the fine particle dispersion 1, except that the amount of polymethyl methacrylate (PMMA) particles was changed to 6.0% by mass and the amount of chlorinated paraffin was changed to 94.0% by mass. Thus, a fine particle dispersion 6 was prepared.

(Fine particle dispersion 7)
In the fine particle dispersion 1, the same procedure as in the preparation of the fine particle dispersion 1, except that the amount of polymethyl methacrylate (PMMA) particles was changed to 20.0% by mass and the amount of chlorinated paraffin was changed to 80.0% by mass. Thus, a fine particle dispersion 7 was prepared.

(Fine particle dispersion 8)
In the fine particle dispersion 1, the polymethyl methacrylate (PMMA) particles were changed to Micropearl AUH (manufactured by Sekisui Chemical Co., Ltd., main component divinylbenzene polymer, average particle size 6 μm), and chlorinated paraffin was converted to polypropylene glycol (number average molecular weight). A fine particle dispersion 8 was prepared in the same manner as in the fine particle dispersion 1, except that it was changed to 2700, manufactured by Sigma-Aldrich Japan Co., Ltd.

(Fine particle dispersion 9)
A fine particle dispersion 9 was prepared in the same manner as the fine particle dispersion 1, except that the paraffin chloride 1 was changed to 1,5-hexanediol (manufactured by Wako Pure Chemical Industries, Ltd.).

(Fine particle dispersion 10) -Comparison dispersion-
1 L of the liquid having the following composition was mixed at 1000 rpm for 60 minutes using a Silverson emulsifier to prepare a fine particle dispersion 10.
・ Isopropyl alcohol: 95.0%
・ Polymethylmethacrylate (PMMA) particles (average particle size 8 μm): 5.0%
(MX-801 manufactured by Soken Chemical Co., Ltd.)

(Fine particle dispersion 11) -Comparison dispersion-
1 L of the liquid having the following composition was mixed at 1000 rpm for 60 minutes using a Silverson emulsifier to prepare a fine particle dispersion 11.
・ Glycerin: 85.0%
・ Polymethyl methacrylate (PMMA) particles (average particle size 8 μm) 15.0%
(MX-801 manufactured by Soken Chemical Co., Ltd.)

(Fine particle dispersion 12) -Comparison dispersion-
1 L of the liquid having the following composition was mixed at 1000 rpm for 60 minutes using a Silverson emulsifier to prepare a fine particle dispersion 12.
・ Octane (Wako Pure Chemical Industries, Ltd.) ... 85.0%
・ Polymethyl methacrylate (PMMA) particles (average particle size 8 μm) 15.0%
(MX-801 manufactured by Soken Chemical Co., Ltd.)

(Comparative solution 13)
A comparative solution 13 was prepared in the same manner as in the fine particle dispersion 1, except that the polymethyl methacrylate (PMMA) particles were removed from the fine particle dispersion 1.

<Image recording and evaluation>
As shown below, images were recorded and evaluated using the ink composition, the treatment liquid, and the fine particle dispersion obtained above. The evaluation results are shown in Table 1 below.

(Preparation of evaluation sample)
An inkjet head (full line head manufactured by Ricoh) of a GELJET GX5000 printer is prepared, and cyan, yellow, magenta, and black storage tanks connected to the inkjet head are cyan ink C1, magenta ink M1, yellow ink Y1, and black ink K1. Each was refilled. As a recording medium, N) silver diamond (manufactured by Nippon Paper Industries Co., Ltd.) is fixed on a stage that can move in a predetermined linear direction at 500 mm / second, and the processing liquid is about 1.5 μm (about 1.5 μm) with a wire bar coater. It was applied to a thickness of malonic acid (corresponding to 0.34 g / m ² ) and dried at 50 ° C. for 2 seconds immediately after the application.
Thereafter, the inkjet head is fixedly arranged so that the direction of the line head in which the nozzles are aligned (main scanning direction) is inclined by 75.7 ° with respect to the direction orthogonal to the moving direction (sub-scanning direction) of the stage, While moving the recording medium at a constant speed in the sub-scanning direction, a solid image was printed by ejecting in a line system under an ejection condition of an ink droplet amount of 8.0 pL, an ejection frequency of 24 kHz, and a resolution of 1200 dpi × 600 dpi. Immediately after printing, it was dried at 70 ° C. for 7 seconds.
Next, the fine particle dispersions 1 to 12 and the comparative liquid 13 were sprayed on the entire image forming surface of the recording medium so as to be 0.2 g / m ² , thereby providing the fine particle dispersion.

  Next, the recording medium was passed between a pair of fixing rollers heated to 60 ° C. at a rate of 300 mm / second, and a fixing process was performed at a nip pressure of 0.25 MPa and a nip width of 4 mm. The fixing roller is composed of a heating roll in which the surface of a SUS (stainless steel) cored bar with a halogen lamp inside is covered with a silicone resin, and an opposing roll that is in pressure contact with the heating roller. It has been done.

(Gloss evaluation)
Before and after each fine particle dispersion was sprayed, the image part of the evaluation sample was visually observed, and the change in gloss was evaluated according to the following evaluation criteria.
~Evaluation criteria~
A: There is no change in gloss.
B: A slight gloss change is observed, but there is no practical problem.
C: Level at which gloss change can be confirmed and there is a practical problem.

(Fixing offset evaluation)
The peeling of the image portion of the evaluation sample subjected to the fixing treatment was visually observed, and the image transfer (fixing offset) to the fixing roller was evaluated according to the following evaluation criteria.

~Evaluation criteria~
A: The peeling of the image part cannot be visually recognized at all.
AB: Peeling of the image part cannot be visually recognized by visual observation, and there is peeling that can be confirmed slightly by observation with a magnifying glass, but there is no practical problem.
B: Peeling of the image part was visually recognized, but there was no practical problem.
C: Level at which peeling of the image portion can be visually recognized and has a practical problem.

  As shown in Table 1, in the present invention, the glossiness of the image was good, and the fixing offset of the image portion was suppressed.

Claims (8)

An ink application step of applying an ink composition onto a recording medium by an inkjet method;
A dispersion applying step for applying a fine particle dispersion on the recording medium to which the ink composition has been applied,
The fine particle dispersion has fine particles of 1 μm or more and 30 μm or less and a non-volatile organic solvent;
An image forming method, wherein a solubility parameter (SP value) of the nonvolatile organic solvent is in a range of 13 to 24 (MPa) ^1/2 . 2. The image forming method according to claim 1, wherein the solubility parameter (SP value) of each of the fine particles and the nonvolatile organic solvent is in the range of 13 to 24 (MPa) ^1/2 . The image forming method according to claim 1, wherein the solubility parameter (SP value) is in a range of 18 to 23 (MPa) ^1/2 .   The image forming method according to claim 1, wherein the non-volatile organic solvent has a boiling point of 150 ° C. or higher at 1 atmosphere.   The non-volatile organic solvent includes at least one selected from a silicone-based organic solvent, a halogen-based organic solvent, and a polyether-based organic solvent, according to any one of claims 1 to 4. Image forming method.   6. The image forming method according to claim 1, wherein the fine particle is contained in the fine particle dispersion in an amount of 5% by mass to 50% by mass. The image forming method according to claim 1, wherein the fine particles include a structure represented by the following general formula (1).


(In General Formula (1), n represents an integer of 10 ≦ n ≦ 1000, R ¹ represents a hydrogen atom or a methyl group, R ² represents —COOX, or an aromatic ring. Represents an alkyl group having 1 to 8 carbon atoms.)   The image forming method according to claim 7, wherein the fine particles are polymethyl (meth) acrylate.