JP2006249300A - Inkjet ink composition, and inkjet recording method and image fixation method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet ink composition freed from problems such as poor ejection due to the adhesion of ink particles to an ejection head, offset to e.g., a roller during fixation, and blocking otherwise occurring when formed images are placed on each other and being capable of forming a high-quality image for a long time and to provide an inkjet recording method and an image fixation method using the same. <P>SOLUTION: The inkjet ink composition comprises a dispersion medium, charged particles containing at least a colorant, and at least either of a silicon-containing polymer and a fluoroalkyl-containing polymer. The inkjet recording method uses the composition and comprises allowing ink drops to fly by an electrostatic inkjet recording system. The image fixation method uses the composition and comprises forming an image on a substrate by an electrostatic recording system and fixing the image on the substrate by using at least either of a silicone rubber roller and a perfluororesin roller. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an inkjet ink composition, an inkjet recording method using the same, and an image fixing method.

  As an image recording method for forming an image on a recording medium such as paper based on an image data signal, there are an electrophotographic method, a sublimation type and a melt type thermal transfer method, an ink jet method and the like. The electrophotographic system requires a process of forming an electrostatic latent image on a photosensitive drum by charging and exposure, which complicates the system and becomes an expensive apparatus. The thermal transfer method is inexpensive, but uses an ink ribbon, so the running cost is high and waste material is generated. On the other hand, the ink jet system is an inexpensive apparatus and ejects ink only to a required image portion to form an image directly on a recording medium, so that ink can be used efficiently and running cost is low. Furthermore, there is little noise and it is excellent as an image recording method.

Inkjet recording methods include, for example, a method in which ink droplets are ejected by the pressure of steam generated by the heat of a heating element, a method in which ink droplets are ejected by mechanical pressure pulses generated by a piezoelectric element, and an electrostatic field. There is a method (see Patent Documents 1 and 2) that causes ink droplets containing charged particles to fly. The method of flying ink droplets with steam or mechanical pressure cannot control the flying direction of the ink droplets, and causes the ink droplets to land precisely on the desired position on the printing medium due to distortion of the ink nozzles or air convection. Is difficult.
On the other hand, the method using an electrostatic field controls the flying direction of the ink droplets by the electrostatic field, so that the ink droplets can be landed accurately at a desired position, and a high-quality image formation (printed material) is created. It is excellent.

  As an ink composition used for inkjet recording using an electrostatic field, an ink composition containing a dispersion medium and charged particles including at least a coloring material is used (see Patent Documents 3 and 4). By changing the color material, the ink composition containing the color material can create four color inks of yellow, magenta, cyan, and black, and can also create special color inks of gold and silver . Therefore, it is useful because a color image formed product (printed product) can be produced. However, conventional ink compositions can obtain high-quality images due to ejection failure due to adhesion of ink particles at the ejection head, offset to a roller during fixing, blocking when the formed images are superimposed, and the like. It was difficult.

Japanese Patent No. 3315334 US Pat. No. 6,158,844 JP-A-8-291267 US Pat. No. 5,952,2048

  The object of the present invention is to solve problems such as ejection failure due to ink particle adhesion at the ejection head, offset to a roller during fixing, blocking when the formed images are superimposed, and formation of a high-quality image An ink-jet ink composition that can be used for a long time, and an ink-jet recording method and an image fixing method using the same.

The present invention is as follows.
(1) An inkjet ink composition comprising a charged particle containing a coloring material, at least one of a silicon-containing polymer and a fluoroalkyl group-containing polymer, and a dispersion medium.
(2) An ink jet recording method, wherein ink droplets are ejected by an ink jet recording method using an electrostatic field, using the ink composition according to (1).
(3) After forming an image of the ink composition according to (1) on a recording medium by an ink jet recording method, the image is recorded on the recording medium using at least one of a silicon rubber roller and a perfluoro resin roller. An image fixing method characterized in that the image is fixed.
(4) The image fixing method according to (3), wherein the ink jet recording method is an ink jet recording method using an electrostatic field.

  According to the present invention, it is possible to solve problems such as ejection failure due to adhesion of ink particles at the ejection head portion, offset to a roller during fixing, blocking when the formed images are superimposed, and formation of a high-quality image. An ink-jet ink composition that can be used for a long time, an ink-jet recording method using the same, and an image fixing method are provided.

The present invention will be further described below.
[Dispersion medium]
The dispersion medium is preferably a dielectric liquid having a high electrical resistivity, specifically, 10 ¹⁰ Ωcm or more. If a dispersion medium having a low electrical resistivity is used, electrical continuity is generated between adjacent recording electrodes, which is not suitable for this embodiment. Further, the dielectric constant of the dielectric liquid is preferably 5 or less, more preferably 4 or less, and still more preferably 3.5 or less. By setting the relative dielectric constant in such a range, an electric field is effectively applied to charged particles in the dielectric liquid, which is preferable.

  Examples of the dispersion medium used in the present invention include linear or branched aliphatic hydrocarbons, alicyclic hydrocarbons, or aromatic hydrocarbons, halogen substitution products of these hydrocarbons, and silicone oil. For example, hexane, heptane, octane, isooctane, decane, isodecane, decalin, nonane, dodecane, isododecane, cyclohexane, cyclooctane, cyclodecane, toluene, xylene, mesitylene, Isopar C, Isopar E, Isopar G, Isopar H, Isopar L, Isopar M (Isopar: trade name of Exxon), Shellsol 70, Shellsol 71 (Shellsol: trade name of Shell Oil), Amsco OMS, Amsco 460 solvent (Amsco: Trade name of Spirits), KF-96L ( The trade name of Shin-Etsu Silicone Co., Ltd.) or the like can be used alone or in combination. The content of the dispersion medium with respect to the entire ink composition is preferably in the range of 20 to 99% by mass. In 20 mass% or more, the particle | grains containing a coloring material can be disperse | distributed to a dispersion medium favorably, and in 99 mass% or less, content of a coloring material can be satisfied.

[Color material]
As the coloring material used in the present invention, known dyes and pigments can be used, and can be selected according to applications and purposes. For example, it is preferable to use a pigment from the viewpoint of the color tone of the recorded image recorded matter (printed matter) (for example, “Distribution Stabilization and Surface Treatment Technology / Evaluation” issued by the Technical Information Association, December 25, 2001 1) (hereinafter also referred to as “Non-Patent Document 1”). By changing the color material, four color inks of yellow, magenta, cyan, and black can be created. In particular, the use of offset printing inks or pigments used for proofing is preferable because the same color tone as that of offset printed matter can be obtained.

  Examples of pigments for yellow ink include C.I. I. Pigment yellow 1, C.I. I. Monoazo pigments such as CI Pigment Yellow 74; I. Pigment yellow 12, C.I. I. Disazo pigments such as CI Pigment Yellow 17; I. Non-benzidine azo pigments such as CI Pigment Yellow 180; I. Azo lake pigments such as CI Pigment Yellow 100; I. Condensed azo pigments such as CI Pigment Yellow 95; I. Pigment Yellow 115, etc., acidic dye lake pigments, C.I. I. Basic dye lake pigments such as CI Pigment Yellow 18, anthraquinone pigments such as Flavantron Yellow, isoindolinone pigments such as isoindolinone yellow 3RLT, quinophthalone pigments such as quinophthalone yellow, isoindoline pigments such as isoindoline yellow, C . I. Nitroso pigments such as CI Pigment Yellow 153, C.I. I. Metal complex azomethine pigments such as CI Pigment Yellow 117; I. And isoindolinone pigments such as CI Pigment Yellow 139.

  Examples of pigments for magenta ink include C.I. I. Monoazo pigments such as CI Pigment Red 3; I. Disazo pigments such as CI Pigment Red 38; I. Pigment red 53: 1 etc. and C.I. I. Azo lake pigments such as CI Pigment Red 57: 1; I. Condensed azo pigments such as CI Pigment Red 144; I. Acidic dye lake pigments such as C.I. Pigment Red 174; I. Basic dye lake pigments such as CI Pigment Red 81; I. Anthraquinone pigments such as CI Pigment Red 177; I. Thioindigo pigments such as CI Pigment Red 88; I. Perinone pigments such as CI Pigment Red 194; I. Perylene pigments such as CI Pigment Red 149; I. Quinacridone pigments such as CI Pigment Red 122; I. Isoindolinone pigments such as CI Pigment Red 180; I. And alizarin lake pigments such as CI Pigment Red 83.

  Examples of the pigment for cyan ink include C.I. Disazo pigments such as CI Pigment Blue 25, C.I. I. Phthalocyanine pigments such as CI Pigment Blue 15; I. Pigment Blue 24, etc., acidic dye lake pigments, C.I. I. Basic dye lake pigments such as CI Pigment Blue 1; I. Anthraquinone pigments such as CI Pigment Blue 60; I. And alkaline blue pigments such as CI Pigment Blue 18.

Examples of the pigment for black ink include organic pigments such as aniline black pigments and iron oxide pigments, and carbon black pigments such as furnace black, lamp black, acetylene black, and channel black.
Furthermore, processed pigments typified by microlith pigments such as Microlith-A, -K, and -T can also be suitably used. Specific examples thereof include Microlith Yellow 4G-A, Micro Resled BP-K, Microlith Blue 4G-T, and Microlith Black CT.
Various pigments can be used as necessary, such as calcium carbonate and titanium oxide pigments for white ink, aluminum powder for silver ink, and copper alloy for gold ink.

Basically, it is preferable to use one kind of pigment for each color, from the viewpoint of simplicity of ink production. However, as a hue adjustment, for example, for black ink, phthalocyanine is mixed with carbon black. Are preferably used in combination of two or more. Alternatively, the pigment may be surface-treated by a known method such as rosin treatment (Non-Patent Document 1).
The pigment content relative to the entire ink composition is preferably in the range of 0.1 to 50% by mass. When the amount is 0.1% by mass or more, the pigment amount is sufficient, and a sufficiently good color is obtained in the printed matter. When the amount is 50% by mass or less, the particles containing the coloring material can be favorably dispersed in the dispersion medium. More preferably, it is 1-30 mass%.

[Coating agent]
In the present invention, it is preferable that the coloring material such as a pigment is dispersed (particulated) in a state of being coated with a coating agent, rather than directly dispersed (particulated) in a dispersion medium. By covering with a coating agent, it is possible to shield the charge of the color material and to impart desirable charge characteristics. In the present invention, after ink jet recording on a printing medium, fixing is performed by a heating means such as a heat roller. At this time, the coating material is melted by heat and can be fixed efficiently.

  Examples of the coating agent include rosins, rosin-modified phenolic resins, alkyd resins, (meth) acrylic polymers, polyurethane, polyester, polyamide, polyethylene, polybutadiene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl alcohol, acetal-modified products of polycarbonate, polycarbonate Etc. Among these, from the viewpoint of ease of particle formation, the mass average molecular weight is in the range of 2,000 to 1,000,000 and the polydispersity (mass average molecular weight / number average molecular weight) is 1.0 to 5 Polymers in the range of 0.0 are preferred. Further, from the viewpoint of ease of fixing, a polymer having any one of a softening point, a glass transition point, and a melting point within a range of 40 ° C. to 120 ° C. is preferable.

  In the present invention, the polymer particularly preferably used as the coating agent is a polymer containing at least one of the structural units represented by the following general formulas (1) to (4).

In the formula, X ₁₁ represents an oxygen atom or —N (R ₁₃ ) —. R ₁₁ represents a hydrogen atom or a methyl group, R ₁₂ represents a hydrocarbon group having 1 to 30 carbon atoms, and R ₁₃ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms. R ₂₁ represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. R ₃₁ , R ₃₂ and R ₄₁ each represent a divalent hydrocarbon group having 1 to 20 carbon atoms. The hydrocarbon group of R ₁₂ , R ₂₁ , R ₃₁ , R ₃₂ , and R ₄₁ may contain an ether bond, amino group, hydroxy group, or halogen substituent.

  The polymer containing the structural unit represented by the general formula (1) can be obtained by radical polymerization of a corresponding radical polymerizable monomer by a known method. Examples of the radical polymerizable monomer used include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, and (meth) acrylic. Octyl acid, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, (meth) (Meth) acrylic acid esters such as 2-hydroxyethyl acrylate, N-methyl (meth) acrylamide, N-propyl (meth) acrylamide, N-phenyl (meth) acrylamide, N, N-dimethyl (meth) Examples include (meth) acrylamides such as acrylamide.

  The polymer containing the structural unit represented by the general formula (2) can be obtained by radical polymerization of a corresponding radical polymerizable monomer by a known method. Examples of the radical polymerizable monomer used include ethylene, propylene, butadiene, styrene, and 4-methylstyrene.

The polymer containing the structural unit represented by the general formula (3) can be obtained by dehydrating condensation of a corresponding dicarboxylic acid or acid anhydride and a diol by a known method. Examples of the dicarboxylic acid used include succinic anhydride, adipic acid, sebacic acid, isophthalic acid, terephthalic acid, 1,4-phenylenediacetic acid, diglycolic acid and the like. Examples of the diol used include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol, and 2-butene- Examples include 1,4-diol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-benzenedimethanol, and diethylene glycol.

  The polymer containing the structural unit represented by the general formula (4) is prepared by dehydrating condensation of a carboxylic acid having a corresponding hydroxy group by a known method or a known cyclic ester of a carboxylic acid having a corresponding hydroxy group. It is obtained by ring-opening polymerization by a method. Examples of the carboxylic acid having a hydroxy group or a cyclic ester thereof include 6-hydroxyhexanoic acid, 11-hydroxyundecanoic acid, hydroxybenzoic acid, and ε-caprolactone.

  The polymer containing at least one of the structural units represented by the general formulas (1) to (4) may be a homopolymer of the structural units represented by the general formulas (1) to (4). It may be a copolymer (copolymer) with these constituent components. In addition, these polymers may be used alone as a coating agent, or may be used in combination of two or more.

  The content of the coating agent with respect to the entire ink composition is preferably in the range of 0.1 to 40% by mass. When the amount is 0.1% by mass or more, the amount of the coating agent is sufficient, and sufficient fixability is obtained. When the amount is 40% by mass or less, particles containing the coloring material and the coating agent can be favorably formed.

[Dispersant]
In the present invention, preferably, the mixture of the colorant and the coating agent is dispersed (particulated) in the dispersion medium, but it is more preferable to use a dispersant in order to control the particle diameter and suppress the sedimentation of the particles. .
Suitable dispersants include surfactants typified by sorbitan fatty acid esters such as sorbitan monooleate and polyethylene glycol fatty acid esters such as polyoxyethylene distearate. Further, for example, a copolymer of styrene and maleic acid, and an amine-modified product thereof, a copolymer of styrene and (meth) acrylic compound, a (meth) acrylic polymer, a copolymer of polyethylene and (meth) acrylic compound, rosin, BYK-160, 162, 164, 182 (polyurethane polymer manufactured by Big Chemie), EFKA-401, 402 (acrylic polymer manufactured by EFKA), Solsperse 17000, 24000 (polyester polymer manufactured by Geneca), and the like. In the present invention, from the viewpoint of long-term storage stability of the ink composition, the mass average molecular weight is in the range of 1,000 to 1,000,000 and the polydispersity (mass average molecular weight / number average molecular weight) is Polymers that are in the range of 1.0 to 7.0 are preferred. Furthermore, it is most preferable to use a graft polymer or a block polymer.

  The polymer used particularly preferably in the present invention comprises a polymer component composed of at least one of structural units represented by the following general formulas (5) and (6), and a structural unit represented by the following general formula (7). A graft polymer containing at least a polymer component contained as a graft chain.

In the formula, X ₅₁ represents an oxygen atom or —N (R ₅₃ ) —. R ₅₁ represents a hydrogen atom or a methyl group, R ₅₂ represents a hydrocarbon group having 1 to 10 carbon atoms, and R ₅₃ represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms. R ₆₁ represents a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen atom, a hydroxyl group, or an alkoxy group having 1 to 20 carbon atoms. X ₇₁ represents an oxygen atom or —N (R ₇₃ ) —. R ₇₁ represents a hydrogen atom or a methyl group, R ₇₂ represents a hydrocarbon group having 4 to 30 carbon atoms, and R ₇₃ represents a hydrogen atom or 1 to 3 carbon atoms.
0 hydrocarbon group is shown. The hydrocarbon group of R ₅₂ and R ₇₂ may contain an ether bond, an amino group, a hydroxy group, or a halogen substituent.

  The graft polymer is obtained by polymerizing a radical polymerizable monomer corresponding to the general formula (7), preferably in the presence of a chain transfer agent, introducing a polymerizable functional group at the terminal of the obtained polymer, It can be obtained by copolymerizing with a radically polymerizable monomer corresponding to 5) or (6).

  Examples of the radical polymerizable monomer corresponding to the general formula (5) include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylic acid. Hexyl (meth) acrylate cyclohexyl, phenyl (meth) acrylate, benzyl (meth) acrylate, (meth) acrylic acid esters of 2-hydroxyethyl (meth) acrylate, and N-methyl (meth) acrylamide And (meth) acrylamides such as N-propyl (meth) acrylamide, N-phenyl (meth) acrylamide, and N, N-dimethyl (meth) acrylamide.

Examples of the radical polymerizable monomer corresponding to the general formula (6) include styrene, 4-methylstyrene, chlorostyrene, methoxystyrene, and the like.
Examples of the radical polymerizable monomer corresponding to the general formula (6) include hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, ( (Meth) stearyl acrylate, and the like.
Specific examples of these graft polymers include polymers represented by the following structural formulas.

  Contains a polymer component containing at least one of the structural units represented by general formulas (5) and (6) and a polymerization component containing at least the structural unit represented by general formula (7) as a graft chain. The graft polymer to be processed may have only the structural unit represented by the general formula (5) and / or (6) and the general formula (7), or may contain other components. A preferred composition ratio between the polymer component containing the graft chain and the other polymer components is 10:90 to 90:10. Within this range, good particle formability is obtained, and a desired particle diameter is easily obtained, which is preferable. These polymers may be used alone as a dispersant, or may be used in combination of two or more.

  The content of the dispersant with respect to the entire ink composition is preferably in the range of 0.01 to 30% by mass. Within this range, good particle formability can be obtained, and a desired particle diameter can be obtained.

[Charge control agent]
In the present invention, the mixture of the colorant and the coating agent is preferably dispersed (particulated) in a dispersion medium using a dispersant, and a charge adjusting agent may be used in combination to control the charge amount of the particles. Further preferred.
Suitable charge control agents include metal salts of organic carboxylic acids such as zirconium naphthenate and zirconium octenoate, ammonium salts of organic carboxylic acids such as tetramethylammonium stearate, sodium dodecylbenzenesulfonate, dioctyl Metal salts of organic sulfonic acids such as magnesium sulfosuccinate, ammonium salts of organic sulfonic acids such as toluenebutyl tetrabutylammonium salt, polymers containing carboxylic acid groups modified with amines of copolymers of styrene and maleic anhydride, etc. Polymers having a carboxylic acid group in the side chain, polymers having a carboxylic acid anion group in the side chain such as a copolymer of stearyl methacrylate and tetramethylammonium methacrylate, side chains such as a copolymer of styrene and vinylpyridine Has a nitrogen atom Rimmer, butyl methacrylate and N- (2-methacryloyloxyethyl) -N, N, polymers having an ammonium group in the side chain of the copolymer of N- trimethylammonium tosylate. The charge applied to the particles may be positively charged or negatively charged. The content of the charge adjusting agent with respect to the entire ink composition is preferably in the range of 0.0001 to 10% by mass. Within this range, the electrical conductivity of the ink composition can be easily adjusted within the range of 10 nS / m to 300 nS / m. Furthermore, the electric conductivity of the charged particles can be easily adjusted to 50% or more of the electric conductivity of the ink composition.

[Other ingredients]
In the present invention, a preservative for preventing corruption, a surfactant for controlling surface tension, and the like can be further contained depending on the purpose.

[Create charged particles]
The ink composition containing the charged particles of the present invention can be prepared by dispersing (particulating) the colorant and preferably the coating agent using the above components. Examples of the method for dispersing (particulate) include the following methods.
(1) A colorant and a coating agent are mixed in advance, and then dispersed (granulated) using a dispersant and a dispersion medium, and a charge adjusting agent is added.
(2) Disperse (particulate) using a coloring material, a coating agent, a dispersant and a dispersion medium at the same time, and add a charge control agent.
(3) Disperse (particulate) using a colorant, a coating agent, a dispersant, a charge control agent and a dispersion medium at the same time.

  Examples of the apparatus used for mixing and dispersing include a kneader, a dissolver, a mixer, a high-speed disperser, a sand mill, a roll mill, a ball mill, an attritor, and a bead mill (the aforementioned Non-Patent Document 1).

[Release agent]
The ink composition in the present invention contains at least one of a silicon-containing polymer and a fluoroalkyl group-containing polymer as a release agent. By containing the polymer, the cohesive force between the contact medium typified by the discharge head portion and the fixing roller of the ink composition and the ink particles is reduced, and the adhesion of the ink particles to the contact medium can be reduced. That is, ejection failure due to ink particle adhesion can be reduced in the head portion, and in the fixing roller, ink offset from the recording medium can be suppressed, and further, blocking when the fixed recording medium is stacked can be suppressed. . Here, the polymer means a high molecular weight compound having a molecular weight of 500 or more. Specifically, dimethyl silicone oil, methylphenyl silicone oil, methyl hydrogen silicone oil, amino-modified silicone oil, epoxy-modified silicone oil, alkyl-modified silicone oil, fluorine-modified silicone oil, silicone wax, fluorine-containing wax, silicone grease, At least one of fluorine-containing grease, silicon-containing surfactant, fluorine-containing surfactant, silicon-containing monomer having a radical polymerizable group, or fluoroalkyl group-containing monomer and a known radical together with other monomer components as necessary Polymers radically polymerized using a polymerization initiator, and at least condensation groups such as hydroxyl, carboxyl, amino, isocyanate, (mono, di, tri) alkoxysilyl groups in the molecule Polymers obtained by condensing at least one of the silicon-containing compound or the fluoroalkyl group-containing compound with other condensing groups as necessary, polytetrafluoroethylene, perfluoroalkane, perfluoropolyalkyl ether, etc. Is mentioned.

  As the above-mentioned silicone-containing monomer and fluoroalkyl group-containing monomer, LSF-230, LSF-240, LSF-250 (terminal methacryloyloxy group silicone oil manufactured by Shin-Etsu Chemical), 1H, 1H-perfluorooctyl (meth) Acrylate, 1H, 1H-pentafluoropropyl (meth) acrylate, 1H, 1H trifluoroethyl (meth) acrylate, 1H, 1H-perfluorohexyl (meth) acrylate, 1H, 1H-perfluorododecyl (meth) acrylate, 1H , 1H, 2H, 2H-perfluorooctyl (meth) acrylate, 1H, 1H, 2H, 2H-perfluorohexyl (meth) acrylate, 1H, 1H, 2H, 2H-perfluorododecyl (meth) acrylate, 1H, 1H , 2H-perfluoro-1-oct Ten, 1H, 1H, 2H-perfluoro-1-hexene, 1H, 1H, 2H-perfluoro-1-decene and the like.

  As the above-mentioned silicon-containing compound having at least a condensation group such as hydroxyl group, carboxyl group, amino group, isocyanate group, (mono, di, tri) alkoxysilyl group in the molecule, or fluoroalkyl group-containing compound, LSF-100 , LSF-110, LSF-120, LSF-130 (manufactured by Shin-Etsu Chemical Co., Ltd., both terminal alcohol silicone oil), LSF-140, LSF-150, LSF-160, LSF-170 (manufactured by Shin-Etsu Chemical Co., both terminal amino groups) Silicone oil), LSF-180 (manufactured by Shin-Etsu Chemical Co., Ltd., both terminal carboxyl group silicone oil), LSF-190 (manufactured by Shin-Etsu Chemical Co., Ltd., both terminal epoxy group silicone oil), perfluorononandic acid, 1H, 1H, 10H , 10H-perfluorodecane-1,10-diol, Furuoro 1,10 decanedicarboxylic acid and the like.

  The molecular weight of the silicon-containing polymer and the fluoroalkyl group-containing polymer is not particularly limited, but the mass average molecular weight Mw is preferably in the range of 500 to 100,000, more preferably in the range of 1,000 to 500,000. . Especially preferably, it exists in the range of 2,000-500,000.

  The volatile content of the silicon-containing polymer and the fluoroalkyl group-containing polymer under conditions of 150 ° C./24 hours is preferably 50% by mass or less. More preferably, it is 30 mass% or less, Most preferably, it is 10 mass% or less. As a release agent, the volatilization of the silicon-containing polymer or fluoroalkyl group-containing polymer can be suppressed at 50% by mass or less at the gas-liquid interface in the discharge head or the like or during the conveyance of the image-formed recording medium to the fixing device. The function of can be demonstrated.

  The silicon-containing polymer and the fluoroalkyl group-containing polymer may be liquid at room temperature, and may be paste or solid.

The solubility of the silicon-containing polymer and fluoroalkyl group-containing polymer used in the present invention in the dispersion medium is preferably higher. Preferably, the polymer has a solubility N represented by the following formula (1) of 20 to 100%, more preferably 60 to 100%, and particularly preferably 80 to 100%.
Formula (1): Solubility N = [Solid content concentration of polymer dispersion medium solution excluding sediment components by applying centrifugal force to 5 g of 1% by weight polymer dispersion medium solution at room temperature] × 100 (%)
Centrifugal force application method: Centrifugal force is applied at a gravity acceleration of 20000 G (m / s ² ) for 10 minutes with a centrifugal separator SRX-201 (manufactured by Tommy Seiko Co., Ltd.).

  In the formula (1), the solid content concentration of the polymer dispersion medium solution is [the weight of the polymer dispersion medium solution after heating the polymer dispersion medium solution to the boiling point of the dispersion medium and leaving it for 2 hours / of the polymer dispersion medium solution before heating. Mass] × 100 (%).

  The silicon-containing polymer and the fluoroalkyl group-containing polymer are preferably transparent or uniformly clouded when dissolved in the dispersion medium. By presenting it uniformly in the solution, the effect as a stable release agent can be exhibited at long running time.

In the silicon-containing polymer and the fluoroalkyl group-containing polymer, the proportion of the silicon and the fluoroalkyl group structural unit is preferably 80% by mass or more based on the total mass of the polymer. More preferably, it is 90 mass% or more, Most preferably, it is 95 mass% or more. When the content is 80% by mass or more, the effect of releasability inherent to silicon and fluoroalkyl groups can be exerted strongly.
In addition, the silicon-containing polymer and the fluoroalkyl group-containing polymer are preferably polymers having no polar group in order to exhibit the effect as a release agent.

  In addition, the silicon-containing polymer and fluoroalkyl group-containing polymer used in the present invention are linear polymers having side chains with a total atom number of 90 or less, or macromonomers containing silicon or fluoroalkyl groups. A polymer obtained by copolymerizing at least one of them without containing other copolymerization components is preferable. When such a polymer is used, a high effect as a release agent can be obtained.

  In the present invention, the content of the release agent in the ink composition is preferably 0.001 to 50% by mass. More preferably, it is 0.01-30 mass%, Most preferably, it is 0.01-10 mass%. When it is 0.001% by mass or more, the function as a release agent can be exhibited, and when it is 50% by mass or less, the adhesion between the ink particles and the image portion and the quick drying property of the image drawn on the recording medium can be maintained. .

  In the present invention, the release agent may be added before, during or after the creation of the charged particles. Preferred is after creation of charged particles.

The ink composition of the present invention is preferably an ink composition that satisfies all of the following conditions (A) to (D). By using such an ink composition, ink droplets can be more stably ejected in long-time inkjet recording.
(A) The electrical conductivity of the ink composition is in the range of 10 nS / m to 300 nS / m, preferably 30 nS / m to 200 nS / m.
(B) The electric conductivity of the charged particles is 50% or more, preferably 60% or more of the electric conductivity of the ink composition.
(C) The volume average diameter of the charged particles is in the range of 0.2 to 5.0 μm, preferably 0.3 to 3.0 μm.
(D) The viscosity of the ink composition is in the range of 0.5 to 5 mPa · s, preferably 0.8 to 4 mPa · s.

  The electric conductivity of the charged particles is a value obtained by centrifuging the ink composition, measuring the electric conductivity of the supernatant liquid on which the charged particles are precipitated, and subtracting the electric conductivity of the ink composition. The volume average diameter of the charged particles can be measured by a centrifugal sedimentation method using an apparatus such as an ultracentrifugal automatic particle size distribution analyzer CAPA-700 (manufactured by Horiba, Ltd.). The particle size distribution of the ink particles is preferably narrow and uniform. The surface tension of the ink composition is preferably in the range of 10 to 70 mN / m. More preferably, it exists in the range of 15-50 mN / m.

The electrical conductivity of the ink composition and the charged particles can be adjusted by the type and amount of the dispersion medium and charge control agent used. Since the charge adjusting agent generates charge by the action of ion dissociation and adsorption to particles, it greatly contributes to the electric conductivity of the charged particles. Therefore, the conditions (A) and (B) can be achieved by using a liquid having a low electrical conductivity or a high electrical resistivity as a dispersion medium and imparting electrical conductivity to the particles with a charge control agent. Some color materials used in the present invention have electrical conductivity. However, the electrical conductivity can be concealed by coating the color material with a coating agent. Can be easily controlled. The volume average diameter of the charged particles can be adjusted by the type and amount of the dispersant used and the apparatus used for dispersion (particulation). Since the dispersant adsorbs to the charged particles and disperses in the dispersion medium, the volume average diameter can be controlled by appropriately adjusting the adsorptive power of the dispersant to the charged particles and the affinity to the dispersion medium. ) Can be achieved. The viscosity of the ink composition can be adjusted by the type and amount of the polymer component such as the dispersion medium used and the dispersant dissolved in the dispersion medium. Further, the viscosity can be adjusted by further using a surfactant. Condition (D) can be achieved by adjusting these appropriately.

[Inkjet recording apparatus]
In the present invention, the ink composition described above is recorded on a recording medium by an ink jet recording method. In the present invention, it is preferable to use an ink jet recording system using an electrostatic field. Ink jet recording methods that use an electrostatic field concentrate the charged particles of the ink composition at the discharge position by electrostatic force by applying a voltage between the control electrode and the back electrode on the back of the recording medium, and record from the discharge position. This is a method of flying to a medium. For example, when the charged particles are positive, the voltage applied between the control electrode and the back electrode is such that the control electrode is a positive electrode and the back electrode is a negative electrode. The same effect can be obtained by charging the recording medium instead of applying a voltage to the back electrode.

 As a method of flying ink, for example, there is a method of flying ink from a needle-like tip such as an injection needle, and recording can be performed using the ink composition of the present invention. However, it is difficult to replenish charged particles after the charged particles are concentrated and discharged, and it is difficult to perform stable long-term recording. When the ink is circulated in order to forcibly supply charged particles, the ink overflows from the tip of the injection needle, so the meniscus shape at the tip of the injection needle, which is the discharge position, is not stable, and stable recording is performed. It is difficult to do and is suitable for short-term recording.

  On the other hand, a method of circulating the ink composition without overflowing the ink composition from the ejection opening is preferably used. For example, ink is circulated in an ink chamber having a discharge opening, and a voltage is applied to a control electrode formed at the periphery of the discharge opening, whereby the tip exists in the discharge opening and the leading end faces the recording medium side. In the method in which the concentrated ink droplets fly from the tip of the ink guide, the replenishment of charged particles by the circulation of the ink and the meniscus stability at the ejection position can be compatible, so that stable recording can be performed for a long time. it can. Further, in this method, since the portion where the ink is in contact with the outside air is very small with only the discharge opening, the evaporation of the solvent is suppressed and the ink physical properties are stabilized, so that it can be suitably used in the present invention.

A configuration example of an ink jet recording apparatus suitable for applying the ink composition of the present invention is shown below.
First, an outline of an apparatus that performs single-sided four-color printing on a recording medium shown in FIG. 1 will be described.
An ink jet recording apparatus 1 shown in FIG. 1 supplies ink to an ejection head 2 composed of ejection heads 2C, 2M, 2Y, and 2K for four colors for forming a full color image. A head driver 4 for driving the ejection head 2 by an output from an external device such as a computer (not shown) or a RIP, and a position control means 5. Further, the ink jet recording apparatus 1 includes a transport belt 7 stretched around three rollers 6A, 6B, and 6C, a transport belt position detection unit 8 including an optical sensor that can detect the position of the transport belt 7 in the width direction, An electrostatic attraction unit 9 for holding the recording medium P on the conveyance belt, a static elimination unit 10 and a mechanical unit 11 for peeling the recording medium P from the conveyance belt 7 after completion of image formation are provided. Upstream and downstream of the conveying belt 7, the feed roller 12 and the guide 13 that supply the recording medium P from the stocker (not shown) to the conveying belt 7, the ink is fixed to the recording medium P after peeling, and the discharge stocker (not shown). A fixing unit 14 and a guide 15 are arranged to be conveyed. In addition, the inkjet printing apparatus 1 has a recording medium position detecting means 16 at a position facing the ejection head 2 with the conveyance belt 7 interposed therebetween, and further collects the solvent vapor generated from the ink composition. A solvent recovery unit comprising the exhaust fan 17 and the solvent vapor adsorbent 18 is disposed, and the vapor inside the apparatus is discharged outside the apparatus through the recovery unit.

  A known roller can be used as the feed roller 12, and the feed roller 12 is arranged so as to increase the feeding ability to the recording medium. Further, since dirt, paper powder, or the like may adhere on the recording medium P, it is desirable to remove them. The recording medium P supplied by the feed roller is transported to the transport belt 7 through the guide 13. The back surface (preferably metal back surface) of the conveyor belt 7 is installed via a roller 6A. The recording medium transported is electrostatically attracted onto the transport belt by the electrostatic attracting means 9. In FIG. 1, electrostatic adsorption is performed by a scorotron charger connected to a negative high voltage power source. The recording medium P is electrostatically adsorbed without floating on the transport belt 7 by the electrostatic adsorption means 9 and the surface of the recording medium is uniformly charged. Here, the electrostatic attraction means is also used as a charging means for the recording medium, but may be provided separately. The charged recording medium P is transported to the ejection head portion by the transport belt 7, and electrostatic ink jet image formation is performed by superimposing the recording signal voltage with the charging potential as a bias. The recording medium P on which the image has been formed is discharged by the discharging unit 10, peeled off by the transfer belt 7 by the mechanical unit 11, and transferred to the fixing unit. The peeled recording medium P is sent to the image fixing means 14 and fixed. The fixed recording medium P is discharged through a guide 15 to a discharge stocker (not shown). The apparatus also has a means for recovering the solvent vapor generated from the ink composition. The recovery means is composed of the solvent vapor absorbing material 18, and a gas containing solvent vapor in the apparatus is introduced into the adsorbent by the exhaust fan 17, and after the vapor is adsorbed and recovered, it is exhausted outside the apparatus. The apparatus is not limited to the above example, and the number, shape, relative arrangement, charging polarity, and the like of constituent devices such as rollers and chargers can be arbitrarily selected. In the above system, four-color drawing is described. However, a multicolor system may be combined with light color ink or special color ink.

  The ink jet recording apparatus used in the above ink jet printing method includes an ejection head 2 and an ink circulation system 3. The ink circulation system 3 further includes an ink tank, an ink circulation device, an ink concentration control device, an ink temperature management device, and the like. In addition, the ink tank may include a stirring device.

As the ejection head 2, a single channel head, a multi-channel head, or a full line head can be used, and main scanning is performed by the rotation of the transport belt 7.
An ink jet head suitably used in the present invention is an ink jet method in which charged particles in an ink flow path are electrophoresed to increase the ink density near the opening and discharge, and is mainly a recording medium or a recording target. Ink droplets are ejected by electrostatic attraction caused by the counter electrode disposed on the back surface of the medium. Therefore, if the recording medium or the counter electrode does not face the head, or if no voltage is applied to the recording medium or the counter electrode even at the position facing the head, the voltage is accidentally applied to the ejection electrode. Ink droplets are not ejected even when a pressure is applied or vibration is applied, and the inside of the apparatus is not soiled.

An ejection head suitably used for the ink jet apparatus is shown in FIGS. As shown in FIGS. 2 and 3, the inkjet head 70 includes an electrically insulating substrate 74 that forms the upper wall of the ink flow path 72 where the ink flow Q in one direction is formed, and the ink to the recording medium P. And a plurality of discharge portions 76 that discharge toward the surface. Each of the ejection portions 76 is provided with an ink guide portion 78 that guides the ink droplet G flying from the ink flow path 72 toward the recording medium P, and the substrate 74 has an opening through which the ink guide portion 78 is inserted. 75 is formed, and the ink meniscus 42 is formed between the ink guide portion 78 and the inner wall surface of the opening 75. The gap d between the ink guide portion 78 and the recording medium P is preferably about 200 μm to 1000 μm. Further, the ink guide part 78 is fixed to the support bar part 40 on the lower end side.

  The substrate 74 includes an insulating layer 44 that electrically isolates two discharge electrodes at a predetermined interval, a first discharge electrode 46 formed above the insulating layer 44, and an insulation that covers the first discharge electrode 46. It has a layer 48, a guard electrode 50 formed on the insulating layer 48, and an insulating layer 52 that covers the guard electrode 50. The substrate 74 includes a second ejection electrode 56 formed below the insulating layer 44 and an insulating layer 58 that covers the second ejection electrode 56. The guard electrode 50 is provided to prevent an electric field from being affected by the voltage applied to the first ejection electrode 46 and the second ejection electrode 56 in an adjacent ejection section.

Further, the ink jet head 70 constitutes the bottom surface of the ink flow path 72, and the ink flow is generated by the induced voltage that is constantly generated by the pulsed discharge voltage applied to the first discharge electrode 46 and the second discharge electrode 56. A floating conductive plate 62 that moves positively charged ink particles (charged particles) R in the path 72 upward (that is, toward the recording medium side) is provided in an electrically floating state. In addition, a coating film 64 that is electrically insulating is formed on the surface of the floating conductive plate 62 to prevent the physical properties and components of the ink from becoming unstable due to charge injection into the ink. The electric resistance of the insulating coating film is preferably 10 ¹² Ω · cm or more, and more preferably 10 ¹³ Ω · cm or more. In addition, the insulating coating film is desirably resistant to corrosion with respect to ink, and this prevents the floating conductive plate 62 from being corroded by ink. Further, the floating conductive plate 62 is covered with the insulating member 66 from below, and the floating conductive plate 62 is completely electrically insulated by such a configuration.

  There are one or more floating conductive plates 62 per head unit (for example, when there are four heads C, M, Y, and K, the number of floating conductive plates is at least one each, and C and M The floating conductive plate is not shared between the head units.

  As shown in FIG. 3, in order to cause ink to fly from the inkjet head 70 and record on the recording medium P, the ink in the ink flow path 72 is circulated to generate an ink flow Q, and the guard electrode A predetermined voltage (for example, +100 V) is applied to 50. Further, a flying electric field that attracts the positive charged particles R in the ink droplet G that has been guided by the ink guide portion 78 and flew from the opening 75 to the recording medium P is generated by the first ejection electrode 46 and the second ejection electrode. A positive voltage is applied to the first ejection electrode 46, the second ejection electrode 56, and the recording medium P so as to be formed between the recording medium P and the recording medium P (1 kV when the gap d is 500 μm). A potential difference of about ~ 3.0 kV is taken as a guide).

In this state, when a pulse voltage is applied to the first ejection electrode 46 and the second ejection electrode 56 in accordance with the image signal, the ink droplet G having an increased charged particle concentration is ejected from the opening 75 (for example, initial charged particles). When the concentration is 3 to 15%, the charged particle concentration of the ink droplet G is 30% or more).
At that time, the ink droplet G is applied to the first ejection electrode 46 and the second ejection electrode 56 so that the ink droplet G is ejected only when the pulse voltage is applied to both the first ejection electrode 46 and the second ejection electrode 56. Adjust the voltage value.

In this way, when a pulsed positive voltage is applied, the ink droplet G is guided by the ink guide portion 78 from the opening 75 and flies to adhere to the recording medium P, and the first ejection is applied to the floating conductive plate 62. A positive induced voltage is generated by the positive voltage applied to the electrode 46 and the second ejection electrode 56. Even if the voltage applied to the first ejection electrode 46 and the second ejection electrode 56 is pulsed, the induced voltage is a substantially steady voltage. Therefore, the charged particles R that are positively charged in the ink flow path 72 are subjected to the upward movement force by the electric field formed between the floating conductive plate 62 and the guard electrode 50 and the recording medium P, and The concentration of charged particles R increases near the substrate 74. As shown in FIG. 3, when the number of ejection units (that is, channels for ejecting ink droplets) to be used is large, the number of charged particles necessary for ejection increases, but the first ejection electrode 46 and the second ejection electrode to be used are used. Since the number of 56 increases, the induced voltage induced in the floating conductive plate 62 increases, and the number of charged particles R moving to the recording medium side also increases.

  In the above, an example in which the colored particles are positively charged has been described. However, the colored particles may be negatively charged. In that case, all the above-mentioned charging polarities are reversed.

  In the present invention, it is preferable that the ink is ejected onto the recording medium and then fixed by contacting with a roller or the like. As a material of the roller used for fixing, it is preferable to use a silicone rubber roller, a perfluoro resin roller, or the like. The silicone rubber roller and the perfluoro resin roller mentioned here do not need to be a silicone rubber or a perfluoro resin roller, and at least the surface thereof may be made of the material. Such fixing rollers are known and commercially available ones can be used. When a roller using the material and the ink composition of the present invention are used in combination, the adhesion between the image area formed on the recording medium is reduced, fixing with excellent offset resistance can be achieved, and thus a good image Can be formed.

  In fixing, it is preferable to use a heating unit in combination. As the heating means to be used, a contact-type heating device such as a heat roller, a heat block, or a belt heating, and a non-contact type heating device such as a dryer, an infrared lamp, a visible light lamp, an ultraviolet lamp, or a hot air oven may be used. it can. The roller itself used for the fixing may be a heating unit. The temperature of the recording medium at the time of fixing is preferably in the range of 40 ° C. to 200 ° C. for ease of fixing. The fixing time is preferably in the range of 1 microsecond to 20 seconds.

  The fixing device including the fixing roller and the heating device is preferably continuous with and integrated with the ink jet recording apparatus.

[Replenishment of ink composition]
In the ink jet recording method using an electrostatic field, charged particles in the ink composition are concentrated and discharged. Accordingly, when the ink composition is discharged for a long time, the charged particles in the ink composition are reduced, and the electrical conductivity of the ink composition is lowered. Further, the ratio between the electric conductivity of the charged particles and the electric conductivity of the ink composition changes. Further, when discharging, charged particles having a larger diameter tend to be discharged preferentially than charged particles having a smaller diameter, so that the average diameter of the charged particles is reduced. Further, since the solid content in the ink composition changes, the viscosity also changes.
Due to these changes in physical property values, as a result, ejection failure occurs, the optical density of recorded images decreases, and ink bleeding occurs. For this reason, by reducing the amount of charged particles by replenishing the ink composition having a higher concentration (higher solid content concentration) than the ink composition initially charged in the ink tank, the electrical conductivity of the ink composition The ratio between the electric conductivity of the charged particles and the electric conductivity of the ink composition can be kept within a certain range. Further, the average particle diameter and viscosity can be maintained. Further, by maintaining the physical property value of the ink composition within a certain range, the ink discharge is stably and uniformly performed for a long time. The replenishment at this time is preferably performed mechanically or manually, for example, by detecting a physical property value such as the electrical conductivity or optical density of the ink liquid used and calculating the shortage. Further, the amount of the ink composition to be used may be calculated based on the image data, and may be formed mechanically or manually.

[Recording medium]
In the present invention, various recording media can be used depending on the application. For example, if paper, plastic film, metal, and paper on which plastic or metal is laminated or vapor-deposited, a plastic film on which metal is laminated or vapor-deposited, etc., printed matter can be directly obtained by ink jet recording. Further, an offset printing plate can be obtained by using a roughened support such as aluminum. Furthermore, if a plastic support is used, a flexographic printing plate or a color filter for a liquid crystal screen can be obtained. The shape of the recording medium may be planar such as a sheet shape or three-dimensional such as a cylindrical shape. Further, if a silicon wafer or a wiring board is used as a recording medium, it can be applied to manufacture of a semiconductor or a printed wiring board.

  By combining the ink composition, the ink jet recording apparatus, and the replenishment of the ink composition described above, it is possible to stably obtain a high-quality image recorded matter with no ink bleeding and high image density over a long period of time. Can do.

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

[Example 1]
<Materials used>
In Example 1, the following materials were used.

Cyan pigment (coloring material) phthalocyanine pigment C.I. I. Pigment Blue (15: 3) (Toyo Ink Manufacturing Co., Ltd., LIONOL BLUE FG-7350)
・ Coating agent [AP-1]
-Release agent Silicone oil KF96-20cs (manufactured by Shin-Etsu Chemical Co., Ltd.), [RP-1], [RP-2], [RP-3], [RP-4], [RP-5]
・ Dispersant [BZ-2]
-Charge control agent [CT-1]
・ Dispersion medium Isopar G (manufactured by Exxon Corporation)

  Coating agent [AP-1], dispersant [BZ-2], charge control agent [CT-1], release agent [RP-1], [RP-2], [RP-3], [RP-4 ] And [RP-5] are shown below.

The coating agent [AP-1] is obtained by radical polymerization of methyl methacrylate, styrene and 2- (N, N-dimethylamino) ethyl methacrylate using a known polymerization initiator, and further reacting with methyl tosylate. Obtained. The mass average molecular weight was 15,000, and the polydispersity (mass average molecular weight / number average molecular weight) was 2.7. The glass transition point (mid point) was 51 ° C., and the softening point by the strain gauge method was 46 ° C.
Dispersant [BZ-2] is a polymer of stearyl methacrylate having a methacryloyl group at its terminal (mass average molecular weight) by radical polymerization of stearyl methacrylate in the presence of 2-mercaptoethanol and further reacting with methacrylic anhydride. Was obtained by radical polymerization with styrene. The mass average molecular weight was 110,000.
The charge control agent [CT-1] was obtained by reacting 1-octadecene and maleic anhydride copolymer with 1-hexadecylamine. The weight average molecular weight was 17,000.

The release agent [RP-1] was obtained by radical polymerization of silicon oil LSF230 (manufactured by Shin-Etsu Chemical Co., Ltd.) having a methacryloyloxy group at the terminal. The weight average average molecular weight was 150,000.
The release agent [RP-2] was obtained by radical polymerization of 1H, 1H-perfluorooctyl methacrylate. The weight average average molecular weight was 150,000.
The release agent [RP-3] was obtained by subjecting silicone oil LSF180 (manufactured by Shin-Etsu Chemical Co., Ltd.) having carboxyl groups at both ends to 1,4-butanediol through a dehydration condensation reaction. The weight average average molecular weight was 87,000.
The release agent [RP-4] was obtained by subjecting perfluorononandioic acid and 1,4-butanediol to a dehydration condensation reaction. The weight average average molecular weight was 17,000.
The release agent [RP-5] was obtained by radical polymerization of silicon oil LSF230 (manufactured by Shin-Etsu Chemical Co., Ltd.) having a methacryloyloxy group at the end and 1H, 1H-perfluorooctyl methacrylate. The weight average average molecular weight was 180,000.

<Preparation of ink composition [EC-1]>
10 g of cyan pigment and 16 g of the coating agent [AP-1] were placed in a table type kneader PBV-0.1 manufactured by Irie Shokai Co., Ltd., the heater temperature was set to 100 ° C., and the mixture was heated and mixed for 2 hours. 30 g of the obtained mixture was coarsely pulverized with a trio-brender manufactured by Trio Science Co., Ltd., and further finely pulverized with a SK-M10 type sample mill manufactured by Kyoritsu Riko Co., Ltd. 30 g of the obtained finely pulverized product was predispersed in a paint shaker manufactured by Toyo Seiki Seisakusho together with 7.5 g of the dispersant [BZ-2], 75 g of Isopar G, and glass beads having a diameter of about 3.0 mm. After removing the glass beads, together with the zirconia ceramic beads having a diameter of about 0.6 mm, the type KDL dynomill manufactured by Shinmaru Enterprises Co., Ltd. was used for 5 hours while maintaining the internal temperature at 25 ° C., followed by 45 ° C. for 5 hours. Dispersion (particle formation) was performed at a rotational speed of 000 rpm. The zirconia ceramic beads are removed from the obtained dispersion, and 316 g of Isopar G, 0.6 g of the charge control agent [CT-1] and 8.0 g of the release agent [RP-1] are added, and the ink composition [EC-1]. Got.

<Inkjet recording>
The ink composition [EC-1] of Example 1 was filled in the ink tank in the ink jet recording apparatus shown in FIGS. Here, a 150 dpi (three-row staggered arrangement with a channel density of 50 dpi) and 833 channel head of the type shown in FIG. 2 was used as the ejection head, and a silicon rubber heat roller incorporating a 1 kW heater was used as the fixing means. As the ink temperature control means, a throw-in heater and a stirring blade were provided in the ink tank, the ink temperature was set to 30 ° C., and the temperature was controlled with a thermostat while rotating the stirring blade at 30 rpm. Here, the stirring blade was also used as a stirring means for preventing precipitation and aggregation. In addition, the ink flow path is partially transparent, and the LED light emitting element and the light detecting element are arranged between them, and the ink dilution liquid (Isopar G) or concentrated ink (the solid content concentration of the ink composition is determined by the output signal). The concentration was controlled by charging. A fine coated paper for offset printing was used as a recording medium. After removing dust on the surface of the recording medium by air pump suction, the ejection head is brought close to the recording medium to the image forming position, image data to be recorded is transmitted to the image data calculation control unit, and the recording medium is rotated by the rotation of the conveyor belt. The ink composition was discharged while sequentially moving the discharge head while transporting the recording medium, and an image was formed with a drawing resolution of 2400 dpi. As the conveyor belt, a metal belt and polyimide film bonded together are used, and a line-shaped marker is placed in the vicinity of one end of the belt along the conveyor direction, and this is optically read by the conveyor belt position detection means. An image was formed by driving the control means. At this time, the distance between the ejection head and the recording medium was kept at 0.5 mm by the output from the optical gap detector. Further, the surface potential of the recording medium was set to −1.5 kV at the time of ejection, and a pulse voltage of +500 V was applied (pulse width 50 μsec) at the time of ejection, and image formation was performed at a driving frequency of 15 kHz. For image recording, an image area ratio of 15%, recording of 10 sheets of A4 size per day was performed, and it was examined whether particles were attached to the ejection openings of the inkjet head. The results are shown in Table 1. The obtained gray scale image recorded matter (printed matter) was a very clear image without streak unevenness and ink bleeding. No image formation failure or the like was observed, and no image deterioration due to dot diameter change or the like was observed even when the outside air temperature changed or the recording time increased, and good image formation was possible.

<Fixing evaluation>
An ink jet recording test is performed, the last recorded image is immediately fixed using a fluoro rubber heat roller, and the coated paper temperature during fixing is changed from 5 to 60 ° C. in steps of 5 ° C. The temperature at which the agent flows (flow start temperature) and the upper limit temperature at which no offset to the heat roller occurs (upper limit anti-offset temperature) were used as the evaluation criteria for fixability.
That is, an ink that maintains the flow start temperature and does not generate an offset up to a high temperature is desirable. Here, “flow” refers to a state in which the coating agent is melted and fluidized and then formed into a film.
The results are shown in Table 1.

Flow start temperature: Visual evaluation was performed by observing an SEM photograph of the image surface after fixing.
Anti-offset upper limit temperature: The occurrence of offset on the heat roller was evaluated by visually re-transferring the offset image from the heat roller to the paper.
Regarding the blocking property of the printed image, the same paper as the printing paper was layered on the fixed image at a temperature sufficiently satisfying the fixing property, a mass of about 50 g / cm ² was applied, and the sheet was left at 50 ° C. for 24 hours, and stacked. The degree of transfer of the image area onto the paper was visually evaluated.
Even when the solvent remained on the recording medium (coated paper), the flow start temperature and the upper limit offset temperature were measured in the same manner as described above, and the fixability was evaluated.

[Example 2]
Except that the release agent [RP-1] was changed to [RP-2] as the material used, an ink composition [EC-2] was prepared using the same material and the same method as in Example 1, and inkjet Drawing, fixing evaluation, and blocking resistance evaluation were performed. The results are shown in Table 1.

[Example 3]
The ink composition [EC-3] was prepared in exactly the same manner as in Example 1, except that the release agent [RP-1] was changed to the release agent [RP-3] as the material used. Then, ink jet drawing, evaluation of fixability, and evaluation of blocking resistance were performed. The results are shown in Table 1.

[Example 4]
The ink composition [EC-4] was prepared in exactly the same manner as in Example 1, except that the release agent [RP-1] was changed to the release agent [RP-4] as the material used. Then, ink jet drawing, evaluation of fixability, and evaluation of blocking resistance were performed. The results are shown in Table 1.
[Example 5]
Ink composition [EC-5] was prepared in exactly the same manner as in Example 1, except that the release agent [RP-1] was changed to the release agent [RP-5] as the material used. Then, ink jet drawing, evaluation of fixability, and evaluation of blocking resistance were performed. The results are shown in Table 1.

[Example 6]
The ink composition [EC-6] was used in exactly the same manner as in Example 1, except that the release agent [RP-1] was changed to silicone oil KF96-20cs (manufactured by Shin-Etsu Chemical Co., Ltd.) as the material used. And ink jet drawing, evaluation of fixability, and evaluation of blocking resistance. The results are shown in Table 1.

[Example 7]
Ink composition [EC-7] using the same material and the same method as in Example 1 except that the amount of release agent [RP-1] added is 1.0 g (1/8 of Example 1). Were prepared, and ink jet drawing, fixability evaluation, and blocking resistance evaluation were performed. The results are shown in Table 1.

[Comparative Example 1]
An ink composition [RC-1] was prepared in the same manner and in the same manner as the ink composition [EC-1] of Example 1 except that the release agent [RP-1] was not added. Inkjet drawing, evaluation of fixability, and evaluation of blocking resistance were performed. The results are shown in Table 1.

[Comparative Example 2]
The ink composition [EC] of Example 1 was used except that the release agent [RP-1] was not added and the addition amount of the dispersant [BZ-2] was 15.0 g (twice that of Example 1). -1] was prepared using the same material and in the same manner as above, and an ink composition [RC-2] was prepared, and ink jet drawing, fixability evaluation, and blocking resistance evaluation were performed. The results are shown in Table 1.

The evaluation of each performance is as follows.
(Head adhesion)
◯: No adhesion is seen at all. Δ: No adhesion, but adhesion ×: The opening is clogged, that is, it is difficult to discharge.
(Fixability)
○: Flow start temperature 70 ° C. or lower and offset resistant upper limit temperature 80 ° C. or higher Δ: Flow start temperature 75 ° C. to less than 80 ° C. and offset resistant upper limit temperature 80 ° C. or higher ×: Flow start temperature 80 ° C. or higher or offset resistant upper limit temperature 80 ° C. Less The evaluation of blocking resistance is as follows.
(Blocking resistance)
○: No transcript △: Some transcripts ×: Pretty transcripts

  As shown in Examples 1 to 7, when ink containing a silicon-containing polymer or a fluoroalkyl group-containing polymer was used as a release agent, good results were obtained in head adhesion, fixing properties, and blocking resistance. It was. On the other hand, in Comparative Examples 1 and 2 in which no silicon-containing polymer or fluoroalkyl group-containing polymer was added as a release agent, the performance of Examples 1 to 7 was achieved in all of the head adhesion, fixability, and blocking resistance. Below. The effect of adding a silicon-containing polymer or a fluoroalkyl group-containing polymer as a release agent was shown.

[Example 8]
Inkjet drawing, evaluation of fixability, and evaluation of blocking resistance were performed in the same manner as in Example 1 except that the fluororubber roller used for evaluation of fixability was a silicon rubber roller. The results are shown in Table 2.

[Example 9]
Inkjet drawing, evaluation of fixability, and evaluation of blocking resistance were performed in the same manner as in Example 1 except that the fluororubber roller used for evaluation of fixability was a perfluoro resin roller. The results are shown in Table 2.

  From Table 2, it was confirmed that in Example 8 using a silicon rubber roller and Example 9 using a perfluoro resin roller, the fixability was improved as compared with Example 1 using a fluoro rubber roller.

  As described above, when the ink composition to which the silicon polymer or the fluoroalkyl group-containing polymer was added as a release agent was used as a result of Examples 1 to 9, adhesion resistance at the head, blocking resistance, and offset resistance at the time of fixing It was confirmed that the effect of improving the offset resistance can be obtained by using a silicon rubber roller or a perfluoro resin roller as the fixing roller.

It is a whole lineblock diagram showing typically an example of an ink jet printer used for the present invention. It is a perspective view which shows the structure of the inkjet head of the inkjet recording device of this invention (In order to make it intelligible, the edge of the guard electrode in each discharge part is not drawn). FIG. 3 is a side sectional view showing a distribution state of charged particles when the number of ejection units of the inkjet head shown in FIG. 2 is large (corresponding to an arrow XX in FIG. 2).

Explanation of symbols

G Injected ink droplet P Recording medium Q Ink flow R Charged particle 1 Inkjet recording apparatus 2 Discharge head 3 Ink circulation system 4 Head driver 5 Position control means 6A to 6C Conveying belt stretching roller 7 Conveying belt 8 Conveying belt position detecting means DESCRIPTION OF SYMBOLS 9 Electrostatic adsorption means 10 Static elimination means 11 Mechanical means 12 Feed roller 13 Guide 14 Image fixing means 15 Guide 16 Recording medium position detection means 17 Exhaust fan 18 Solvent vapor adsorption material 38 Ink guide 40 Support bar part 42 Ink meniscus 44 Insulation Layer 46 First discharge electrode 48 Insulating layer 50 Guard electrode 52 Insulating layer 56 Second discharge electrode 62 Floating conductive plate 64 Coating film 66 Insulating member 70 Inkjet head 74 Substrate 76 Discharge unit 78 Discharge unit

Claims (4)

  An inkjet ink composition comprising a charged particle containing a coloring material, at least one of a silicon-containing polymer and a fluoroalkyl group-containing polymer, and a dispersion medium.   An ink jet recording method, wherein an ink droplet is ejected by an ink jet recording method using an electrostatic field, using the ink composition according to claim 1.   An image is formed on a recording medium by the ink jet recording method according to claim 1 and then the image is fixed on the recording medium using at least one of a silicon rubber roller and a perfluoro resin roller. An image fixing method characterized by the above. The image fixing method according to claim 3, wherein the ink jet recording method is an ink jet recording method using an electrostatic field.

Images