JP2006206687A - Ink, ink set, recording method, ink tank and recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink exhibiting excellent jetting properties at the time of long-term storage, an ink set, a recording method, an ink tank and a recording apparatus. <P>SOLUTION: The ink comprises at least a coloring material, an ionic liquid and water. The ink is particularly suitably employed for an inkjet method. The ink set comprises at least the ink and/or a processing solution comprising at least a flocculant. The recording method and the recording apparatus using the ink set provide, on a recording medium, the ink and the processing solution so that they are brought into contact with each other to form an image. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink, an ink set, a recording method, an ink tank, and a recording device, and further, a recorded matter recorded using the ink, an ink discharging method, and an ink discharging device, and particularly used for an ink jet recording method. The present invention relates to a suitable ink, ink set, recording method, ink tank, and recording apparatus.

  In general, water-based inks whose main solvent component is water or oil-based inks whose main solvent component is an organic solvent are known as inks. Since water used as the water-based ink solvent has a high vapor pressure, it is known that the water evaporates with time and the color material in the ink is solidified.

  On the other hand, an ink jet system that ejects ink from an ink ejection port formed by a nozzle, a slit, a porous film, or the like is used in many printers because of its small size and low cost. Among these ink jet systems, the piezoelectric ink jet system that ejects ink using deformation of piezoelectric elements and the thermal ink jet system that ejects ink using the boiling phenomenon of ink due to thermal energy are excellent in high resolution and high speed printability. Has characteristics.

  In particular, in the case of ink for ink jet, the nozzle diameter for ejecting ink is small, and the change in the state of the ink tends to have a great influence on the ink ejection. For this reason, if the ink is filled in the head and left for a long period of time, the moisture evaporates from the tip of the nozzle, causing a problem of closing the nozzle. As a result, there are cases where image quality deterioration occurs such as non-ejection in which ink is not ejected or directionality failure in which the ink ejection direction is bent.

For these problems, a method is known in which a hydrophilic organic solvent or the like is added to the ink as a humectant to improve the stability of the coloring material when the water content is reduced. (Patent Document 1 etc.)
The hydrophilic solvent is classified into a high-boiling solvent having a high boiling point and a low-boiling solvent having a low boiling point using the boiling point as an index. First, the case where a high boiling point organic solvent is used as the hydrophilic solvent will be described. High boiling point organic solvents are less likely to volatilize and have high water retention, so that water evaporation in the ink can be suppressed, which is advantageous for jetting properties during long-term storage. However, since the high boiling point solvent has a high viscosity and tends to increase the ink viscosity, jetting may be a problem particularly when used in an ink jet method. Next, a case where a low boiling point solvent is used as the hydrophilic solvent will be described. The low boiling point solvent has a low viscosity and can also reduce the ink viscosity. Therefore, in particular, when printing is performed by an ink jet method or the like, there is a tendency that a problem does not occur with jetting properties. On the other hand, since the low boiling point solvent volatilizes itself, when it is left for a long period of time, not only water but also the low boiling point solvent volatilizes, and the coloring material may aggregate. In particular, in the ink jet system, since the nozzles are fine, color material aggregates block the nozzles, thereby causing image quality defects such as non-ejection and poor directivity.

  As described above, the conventional method has not been sufficiently satisfactory in terms of maintaining a long period of time with a low ink viscosity, and therefore, the initial ejection property and the ejection property during long-term storage are not obtained. At the same time, no satisfactory product was obtained.

Japanese Patent No. 3030369

  Therefore, the present invention provides an ink, an ink set, a recording method, an ink tank, and a recording apparatus that have stable ink characteristics even when held for a long period of time, and as a result, achieve both initial ejection properties and ejection properties during long-term storage. Furthermore, another object is to provide a recorded matter, an ink discharge method, and an ink discharge device recorded using the ink.

As a result of intensive studies to solve the problems related to the present invention, the ink characteristics are stable even when held for a long time by satisfying the configuration of the present invention. It came to the conclusion that it is satisfied simultaneously. That is,
The present invention relates to an ink containing at least a coloring material, an ionic liquid, water, an ink set including the ink and a treatment liquid, a recording method using the ink or an ink set including the ink, an ink tank, and a recording apparatus. Further, the present invention resides in a recorded matter recorded using the ink, an ink discharge method, and an ink discharge device.

  According to the present invention, due to the characteristics of the ionic liquid contained in the ink, there is no change in ink characteristics when held for a long period of time. Since the jetting property is excellent, the pattern or image obtained by this ink is stabilized.

Hereinafter, the present invention will be described in detail.
Generally, a salt is solid at room temperature, and is known to melt when heated to several hundred degrees. On the other hand, a so-called ionic liquid that is in a liquid state at room temperature has been found in a predetermined combination of organic cation and anion. The reason why this ionic liquid becomes liquid at a temperature near room temperature is presumed to be related to the size of ions and the electrostatic interaction between ions. Furthermore, the ionic liquid has a low vapor pressure, is non-volatile, and at the same time has the characteristics of being nonflammable and flame retardant. This is presumed to be because ions are restrained due to the electrostatic interaction between molecules.

The present inventor has found that the above problem can be solved by using an ionic liquid as an ink solvent, and has reached the present invention. The mechanism is not clear, but is presumed as follows.
First, characteristics required as ink characteristics will be described. The required ink characteristic includes lowering the ink viscosity. This is because it is necessary to form a uniform thin-layer image when ink is applied onto a recorded matter. In particular, in the case of use in an ink jet system, it is important to ensure ink ejection properties. This is mainly because two factors are envisaged, one of which is that energy corresponding to the ink viscosity is required for ejection from the nozzle, and the energy required for ejection is reduced by lowering the ink viscosity. It becomes possible to do. The second is the ink supply time when ink is supplied from the ink tank to the nozzle portion after ink ejection. In the ink jet method, the ink supply uses the penetrating power of the liquid into the capillary by the meniscus, and by reducing the ink viscosity, the ink supply time to the nozzle tip can be shortened, and the ink ejectability is improved. Is estimated to be possible.

  The ionic liquid used in the present invention can be adjusted to have a low viscosity by a combination of an organic cation and an anion. It is assumed that this can be realized by appropriately adjusting the size of the organic cation and anion molecules and the interaction between the molecules. As described above, particularly in the case of ink used in an ink jet system, the ink preferably has a low viscosity from the viewpoint of energy during ejection and from the viewpoint of ink supply. Therefore, it is considered that the ink according to the present invention that can keep the viscosity low is excellent in initial jetting properties.

On the other hand, when the ink is left in the atmosphere, the solvent volatilizes and the ink composition changes. In particular, in the case of water-based ink, the main component of the ink is water, and when this water evaporates, there is a problem that the ink viscosity increases or the color material in the ink aggregates. Increasing the ink viscosity causes problems in the formation of thin layer images. On the other hand, in the ink jet system, a problem occurs in the ink jetting property, and further, a problem that the color material aggregate blocks a fine nozzle. As described above, the ink composition during long-term storage and the change in the ink physical properties greatly affect the jetting properties. However, the ionic liquid used in the present invention has a low vapor pressure and is difficult to volatilize. is doing. Furthermore, by adjusting the combination of the organic cation and the anion, an ionic liquid having a high affinity with water can be provided. Accordingly, since the moisturizing agent does not volatilize, it is possible to suppress excessive water evaporation at the nozzle tip, and even when stored for a long period of time, it is possible to improve the jetability during long-term storage.
Thus, conventionally, it has become possible to simultaneously satisfy the conflicting characteristics of the initial injection property and the injection property during long-term storage.

Next, the present invention will be described in detail.
In the present invention, the ink contains at least a coloring material, an ionic liquid, and water.
Any coloring material may be used in the present invention as long as it has a function of forming an image by coloring, such as dyes, pigments, and colored fine particles.

As the dye used in the present invention, either a water-soluble dye or a disperse dye may be used.
Specific examples of water-soluble dyes include C.I. I. Direct Black-2, -4, -9, -11, -17, -19, -22, -32, -80, -151, -154, -168, -171, -194, -195, C.I. I. Direct Blue-1, -2, -6, -8, -22, -34, -70, -71, -76, -78, -86, -112, -142, -165, -199, -200, -201, -202, -203, -207, -218, -236, -287, -307, C.I. I. Direct Red-1, -2, -4, -8, -9, -11, -13, -15, -20, -28, 31, -33, -37, -39, -51, -59, -62, -63, -73, -75, -80, -81, -83, -87, -90, -94, -95, -99, -101, -110, -189, -227, C.I. I. Direct Yellow-1, −2, −4, −8, −11, −12, −26, −27, −28, −33, −34, −41, −44, −48, −58, −86, -87, -88, -132, -135, -142, -144, -173, C.I. I. Food Black-1, -2, C.I. I. Acid Black-1, -2, -7, -16, -24, -26, -28, 31-1, -48, -52, -63, -107, -112, -118, -119, -121, -156, -172, -194, -208, C.I. I. Acid Blue-1, −7, −9, −15, −22, −23, −27, −29, −40, −43, −55, −59, −62, −78, −80, −81, -83, -90, -102, -104, -111, -185, -249, -254, C.I. I. Acid Red-1, -4, -8, -13, -14, -15, -18, -21, -26, -35, -37, -52, -110, -144, -180, -249, -257, -289, C.I. I. Acid Yellow-1, −3, −4, −7, −11, −12, −13, −14, −18, −19, −23, −25, −34, −38, −41, −42 -44, -53, -55, -61, -71, -76, -78, -79, -122, and the like.

  Next, specific examples of disperse dyes include C.I. I. Disperse Yellow-3, -5, -7, -8, -42, -54, -64, -79, -82, -83, -93, -100, -119, -122, -126, -160, -184: 1, -186, -198, -204, -224, C.I. I. Disperse Orange-13, -29, -31: 1, -33, -49, -54, -66, -73, -119, -163, C.I. I. Disperse Red-1, -4, -11, -17, -19, -54, -60, -72, -73, -86, -92, -93, -126, -127, -135, -145, -154, -164, -167: 1, -177, -181, -207, -239, -240, -258, -278, -283, -311, -343, -348, -356, -362, C. I. Disperse Violet-33, C.I. I. Disperse Blue-14, -26, -56, -60, -73, -87, -128, -143, -154, -165, -165: 1, -176, -183, -185, -201,- 214, -224, -257, -287, -354, -365, -368, C.I. I. Disperse Green-6: 1, -9 etc. are mentioned.

  As the pigment, any of organic pigments and inorganic pigments can be used. Examples of black pigments include carbon black pigments such as furnace black, lamp black, acetylene black, and channel black. In addition to the three primary color pigments of black, cyan, magenta, and yellow, specific color pigments such as red, green, blue, brown, and white, and metallic luster pigments such as gold and silver can also be used. Furthermore, a pigment newly synthesized for the present invention may be used.

Specific examples of the pigment in the present invention include Raven 7000, Raven 5750, Raven 5250, Raven 5000 ULTRA II, Raven 3500, Rav.
en2000, Raven1500, Raven1250, Raven1200, Raven1190 ULTRAII, Raven1170, Raven1255, Raven1
080, Raven 1060 (above Colombian Carbon Co., Ltd.), Regal 400R, Regal 330R, Regal 660R, Mogu L, Black Pearls L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1000, Monarch 1 (Cabot, Inc.), Color Black FW1, Color Black FW2, Color Black FW2V, Color Black 18, Color Black FW200, Color Black S150, Color Black S160, Color Black P35P tex V, Printex140U, Printex140V, Special Black 6, Special Black 5, Special (all manufactured by Degussa) Black 4A, Special Black4, No. 25, no. 33, no. 40, no. 47, no. 52, no. 900, no. 2300, MCF-88, MA600, MA7, MA8, MA100 (manufactured by Mitsubishi Chemical Co., Ltd.), and the like, but are not limited thereto.

  For cyan, C.I. I. Pigment Blue-1, -2, -3, -15, -15: 1, -15: 2, -15: 3, -15: 4, -16, -22, -60, and the like. It is not limited.

  The magenta color is C.I. I. Pigment Red-5, -7, -12, -48, -48: 1, -57, -112, -122, -123, -146, -168, -184, -202, C.I. I. Pigment Violet-19 and the like, but are not limited thereto.

  Yellow is C.I. I. Pigment Yellow-1, -2, -3, -12, -13, -14, -16, -17, -73, -74, -75, -83, -93, -95, -97, -98, -114, -128, -129, -138, -151, -154, -155, -180, and the like, but are not limited thereto.

  In the present invention, it is also possible to use a pigment that is self-dispersible in water. The pigment that can be self-dispersed in water refers to a pigment that has many water-solubilizing groups on the pigment surface and can be stably dispersed in water without the presence of a polymer dispersant. Specifically, it can be self-dispersed in water by subjecting ordinary so-called pigments to surface modification treatments such as acid / base treatment, coupling agent treatment, polymer graft treatment, plasma treatment, oxidation / reduction treatment, etc. Pigments are obtained.

  Examples of the pigment that can be self-dispersed in water include a pigment obtained by subjecting the above pigment to surface modification treatment, as well as Cab-o-jet-200, Cab-o-jet-250, Cab- Commercially available self-dispersing products such as o-jet-260, Cab-o-jet-270, Cab-o-jet-300, IJX-444, IJX-55, Microjet Black CW-1, CW-2 manufactured by Orient Chemical Co., Ltd. Pigments can also be used.

Furthermore, a pigment coated with a resin can be used as a color material. This is called a microcapsule pigment, and it is possible to use not only commercially available ichrocapsule pigments manufactured by Dainippon Ink and Chemicals, Toyo Ink, but also microcapsule pigments etc. that have been prototyped for the present invention. it can.
It is also possible to use so-called colored fine particles in which a resin colored with a dye or pigment is dispersed.

  The ionic liquid has a property of easily dissolving the salt and tends to dissolve the dye. On the other hand, when pigments or colored fine particles are used as the coloring material, the balance between the hydrophilicity / hydrophobicity balance of the pigment or the colored fine particles, the surface functional group type, the amount of surface functional groups and the ionic liquid is appropriately adjusted. It becomes possible to disperse. When a pigment is used as the color material, the pigment is preferably a self-dispersed pigment, a pigment dispersed using a polymer dispersant, a microcapsule pigment, or the like.

  The color material used in the present invention is 0.1% by mass or more and 50% by mass or less, preferably 1% by mass or more and 30% by mass or less, more preferably 1% by mass or more and 20% by mass or less with respect to the total mass of the ink. used. When the amount of the color material in the ink is less than 0.1% by mass, there is a case where a sufficient optical density cannot be obtained, and when the amount of the color material is more than 50% by mass, the ink ejectability is high. There was a case that became unstable.

In the present invention, a dispersant may be used to disperse the color material. As the dispersant, nonionic compounds, anionic compounds, cationic compounds, amphoteric compounds and the like can be used.
Examples thereof include a copolymer of monomers having an α, β-ethylenically unsaturated group. Examples of monomers having an α, β-ethylenically unsaturated group include ethylene, propylene, butene, pentene, hexene, vinyl acetate, allyl acetate, acrylic acid, methacrylic acid, crotonic acid, crotonic acid ester, itaconic acid, itacone Acid monoester, maleic acid, maleic acid monoester, maleic acid diester, fumaric acid, fumaric acid monoester, vinyl sulfonic acid, styrene sulfonic acid, sulfonated vinyl naphthalene, vinyl alcohol, acrylamide, methacryloxyethyl phosphate, bismethacryloxy Styrene derivatives such as ethyl phosphate, methacryloxyethyl phenyl acid phosphate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, styrene, α-methylstyrene, vinyltoluene , Vinylcyclohexane, vinylnaphthalene, vinylnaphthalene derivatives, alkyl acrylate ester, phenyl acrylate ester, alkyl methacrylate ester, phenyl methacrylate ester, cycloalkyl methacrylate ester, alkyl crotonate ester, dialkyl itaconate ester, dialkyl maleate Examples thereof include esters, vinyl alcohol, and derivatives of the above compounds.

  A copolymer obtained by copolymerizing a single monomer or a plurality of monomers having the α, β-ethylenically unsaturated group is used as a polymer dispersant. Specifically, styrene-styrene sulfonic acid copolymer, styrene-maleic acid copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, vinyl naphthalene- Methacrylic acid copolymer, vinyl naphthalene-acrylic acid copolymer, acrylic acid alkyl ester-acrylic acid copolymer, methacrylic acid alkyl ester-methacrylic acid copolymer, styrene-acrylic acid alkyl ester-acrylic acid copolymer, Examples include styrene-methacrylic acid phenyl ester-methacrylic acid, styrene-methacrylic acid cyclohexyl ester-methacrylic acid copolymer, polystyrene, polyester, and polyvinyl alcohol.

  The dispersant used in the ink in the present invention is preferably a weight average molecular weight of 2,000 to 50,000. When the molecular weight of the dispersant is less than 2,000, the colorant may not be stably dispersed. On the other hand, when the molecular weight exceeds 50,000, the viscosity of the ink is increased and the discharge property is deteriorated. Existed. A more preferred weight average molecular weight is 3,500 to 20,000.

  In the present invention, the dispersant added to the ink is used in an amount ratio of 1% to 100% by mass ratio with respect to the colorant. When the added amount ratio exceeds 100%, the ink viscosity becomes high, and there are cases where the ink ejection characteristics become unstable. On the other hand, when the addition amount was less than 1%, there was a case where the dispersion stability of the coloring material was lowered. The added amount of the dispersant is more preferably 2.5% or more and 75% or less, and further preferably 5% or more and 50% or less.

  In the present invention, the volume average particle diameter of the color material in the ink is preferably 30 nm or more and 250 nm or less. The volume average particle diameter of the color material particles refers to the particle diameter of the color material itself, or the particle diameter to which the additive has adhered when an additive such as a dispersant is adhered to the color material. In the present invention, a Microtrac UPA particle size analyzer 9340 (manufactured by Leeds & Northrup) was used as a volume average particle diameter measuring apparatus. The measurement was performed according to a predetermined measurement method with 4 ml of ink placed in a measurement cell. As parameters to be input immediately, the ink viscosity was used as the viscosity, and the density of the coloring material was used as the density of the dispersed particles. A more preferable volume average particle diameter is 60 nm or more and 250 nm or less, and further preferably 150 nm or more and 230 nm or less. When the volume average particle diameter of the particles in the ink is less than 30 nm, the optical density may be low. On the other hand, when it exceeds 250 nm, the dispersion stability of the coloring material may not be ensured. .

  Examples of the ionic liquid used in the present invention include imidazolium-based, pyridinium-based, piperidinium-based, quaternary ammonium-based, and phosphonium-based organic cations.

The imidazolium salt is represented by the following general formula (1).
General formula (1)

In general formula (1), R < ₁ > -R < ₃ > shows hydrogen, an alkyl group, or an alkoxy group, As an alkyl group or an alkoxy group, it is preferable that it is C1-C20, and 1-8 are especially preferable.
Specific examples include 1-ethyl-3-methylimidazolium salt, 1-butyl-3-methylimidazolium salt, 1-hexyl-3-methylimidazolium salt, 1-octyl-3-methylimidazolium salt, 1 -Decyl-3-methylimidazolium salt, 1-dodecyl-3-methylimidazolium salt, 1-tetradecyl-3-methylimidazolium salt, 1-hexadecyl-3-methylimidazolium salt, 1-octadecyl-3-methyl Examples include imidazolium salts, 1-ethyl-2,3-dimethylimidazolium salts, 1-butyl-2,3-dimethylimidazolium salts, 1-hexyl-2,3-dimethylimidazolium salts, and the like. Of these, 1-ethyl-3-methylimidazolium salt and 1-butyl-3-methylimidazolium salt are particularly preferable.

The pyridinium salt is represented by the following general formula (2).
General formula (2)

In general formula (2), R represents hydrogen, an alkyl group or an alkoxy group, and the alkyl group or alkoxy group preferably has 1 to 20 carbon atoms, and particularly preferably 1 to 8 carbon atoms.
Specific examples include 1-ethylpyridinium salt, 1-butylpyridinium salt, 1-hexylpyridinium salt and the like. Among these, 1-ethylpyridinium salt and 1-butylpyridinium salt are particularly preferable.

The quaternary ammonium salt is represented by the following general formula (3).
General formula (3)

In general formula (3), R < ₁ > -R < ₄ > shows hydrogen, an alkyl group, or an alkoxy group, As an alkyl group or an alkoxy group, it is preferable that it is C1-C20, and 1-8 are especially preferable.
Specific examples include aliphatic quaternary ammonium salts. Specific examples include trimethyl-hexylammonium salt, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium salt, trimethylhexylammonium salt, trimethyloctylammonium salt, and the like. In particular, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium salt is preferred.

It is also possible to use a piperidinium salt represented by the following general formula (4).
General formula (4)

In general formula (4), R < ₁ > -R < ₂ > shows hydrogen or an alkyl group, As a alkyl group, a C1-C20 alkyl group is preferable, and 1-8 are especially preferable.

  In the general formulas (1) to (4), it is also possible to use a Zwitterionic type ionic liquid having a carboxylic acid group or a sulfonic acid group as a part of the alkyl group.

  Further, pyrrolinium salt, phenylindolium salt, alkylindolium salt, alkylcarbazolium salt, pyrazolium salt, pyrrolidinium salt, and the like can also be used.

  Furthermore, since the melting point of the compound obtained by combination with an anion can be designed to be low, the organic cation is preferably an imidazolium type, a pyridinium type, or a piperidinium type, and an alkyl chain in a quaternary ammonium type. Longer compounds are preferred. Specifically, 1-ethyl-3-methylimidazolium salt, 1-butyl-3-methylimidazolium salt, 1-hexyl-3-methylimidazolium salt, 1-octyl-3-methylimidazolium salt, 1 -Decyl-3-methylimidazolium salt, 1-dodecyl-3-methylimidazolium salt, 1-tetradecyl-3-methylimidazolium salt, 1-hexadecyl-3-methylimidazolium salt, 1-octadecyl-3-methyl Imidazolium salt, 1-butyl-2,3-dimethylimidazolium salt, 1-hexyl-2,3-dimethylimidazolium salt, 1-butylpyridinium salt, 1-hexylpyridinium salt, trimethyloctylammonium salt, piperidinium salt, etc. Is preferred.

On the other hand, examples of the anion include lithium ion, bromine ion, chlorine ion, lactate ion, hexafluorophosphate, tetrafluoroborate, bis (trifluoromethanesulfonyl) imide, trifluoromethanesulfonate, and the like.
Furthermore, from the viewpoint of safety such as toxicity of the material and solubility in water, the anions include lithium ion, bromine ion, chlorine ion, lactate ion, hexafluorophosphate, bis (trifluoromethanesulfonyl) imide, Trifluoromethanesulfonate is preferable, and lithium ion, bromine ion, chlorine ion, and lactate ion are more preferable.

  Specific examples of ionic liquids include 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium lactate, 1-ethyl-3-methylimidazole 1-butyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide, 1-butyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide Butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium lactate, 1-hexyl-3-methylimidazolium bromide, 1- Hexyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium hex Safluorophosphate, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, 1-octyl-3-methylimidazolium chloride, 1-octyl-3- Methyl imidazolium hexafluorophosphate, 1-decyl-3-methyl imidazolium chloride, 1-dodecyl-3-methyl imidazolium chloride, 1-hexadecyl-3-methyl imidazolium chloride, 1-octadecyl-3-methyl imidazolium Chloride, 1-ethyl-2,3-dimethylimidazolium bromide, 1-ethyl-2,3-dimethylimidazolium chloride, 1-butyl-2,3-dimethylimidazolium chloride, 1-butyl-2,3-dimethyl Imidazolium bromide, 1-butyl-2,3-dimethylimidazolium tetrafluoroborate, 1 -Hexyl-2,3-dimethylimidazolium bromide, 1-hexyl-2,3-dimethylimidazolium chloride, 1-hexyl-2,3-dimethylimidazolium tetrafluoroborate, 1-hexyl-2,3-dimethylimidazole Lithium trifluoromethanesulfonate, 1-ethylpyridinium bromide, 1-ethylpyridinium chloride, 1-butylpyridinium bromide, 1-butylpyridinium chloride, 1-butylpyridinium hexafluorophosphate, 1-butylpyridinium trifluoromethanesulfonate, 1-hexylpyridinium bromide, 1-hexylpyridinium chloride, 1-hexylpyridinium hexafluorophosphate, 1-hexylpyridinium tetrafluoroborate, 1-hexylpyridinium trifluoromethanesulfonate, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) imide , Trimethylhexylammonium bis (trifluoromethanesulfonyl) imide, trimethyloctylammonium bis (trifluoromethanesulfonyl) imide, trimethylpropylammonium bis (trifluoromethanesulfonyl) imide, 2-methyl-1-pyrrolium hexafluoroborate, 1-ethyl- 2-phenylindolium hexafluoroborate, 1,2-dimethylindolium hexafluoroborate, 1-ethylcarbazolium hexafluoroborate, 1-methylpyrazolium hexafluoroborate, 1-methylpyrrolidinium hexafluoroborate Late And the like.

  Furthermore, from the viewpoint of material safety and solubility in water, the following compounds are preferable as the ionic liquid. In particular, when the ink jet method is used, since the ejectability affects the ink viscosity, there is an effect of ensuring the ink ejectability. Specific examples include 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium lactate, 1-ethyl-3-methylimidazolium hexafluorophos Fate, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium Lactate, 1-hexyl-3-methylimidazolium bromide, 1-hexyl-3-methylimidazolium chloride, 1-octyl-3-methylimidazolium chloride, 1-octyl-3-methylimidazolium hexafluorophosphate, 1 -Decyl-3-methylimidazolium chloride, 1-dodecyl-3-methylimidazolium chloride 1-hexadecyl-3-methylimidazolium chloride, 1-octadecyl-3-methylimidazolium chloride, 1-ethyl-2,3-dimethylimidazolium bromide, 1-ethyl-2,3-dimethylimidazolium chloride, 1-butyl-2,3-dimethylimidazolium chloride, 1-butyl-2,3-dimethylimidazolium bromide, 1-hexyl-2,3-dimethylimidazolium bromide, 1-hexyl-2,3-dimethylimidazolium Preferred are chloride, 1-ethylpyridinium bromide, 1-ethylpyridinium chloride, 1-butylpyridinium bromide, 1-butylpyridinium chloride, 1-hexylpyridinium bromide, 1-hexylpyridinium chloride and the like.

  In the present invention, the ionic liquid is preferably a compound composed of an organic cation and an anion, and the melting point of the compound is preferably 25 ° C. or lower. When the melting point of the ionic compound exceeds 25 ° C., the ink is solidified at a low temperature, so that the ink may not be normally applied to the recording medium. More preferably, the melting point of the ionic liquid is 20 ° C. or less, and more preferably 10 ° C. or less.

  In the present invention, the molecular weight of the ionic liquid is preferably less than 1000, more preferably less than 750, and still more preferably less than 500. When the molecular weight of the ionic liquid is 1000 or more, the ink viscosity becomes high. In particular, when ink is applied by an ink jet method, the ink may not be ejected normally.

  In the present invention, the addition amount of the ionic liquid is preferably 1% by mass or more and less than 75% by mass, more preferably 5% by mass or more and less than 60% by mass, and still more preferably, with respect to the whole ink. It is 10 mass% or more and less than 30 mass%. When the addition amount of the ionic liquid was less than 1% by mass, there was a case where the jetability during long-term storage was lowered. On the other hand, when the amount of the ionic liquid added exceeds 75% by mass, the drying property on the recording medium may be slow.

  As an ionic liquid used for this invention, it is preferable that the solubility with respect to 100 g of water is 5 g or more. More preferably, it is 7.5 g or more, More preferably, it is 10 g or more. When the solubility in 100 g of water was less than 5 g, there was a case where the ionic liquid and water were separated and the color material concentration in the ink was uneven. As a result, unevenness occurred particularly in the solid image portion.

In the present invention, the boiling point of the ionic liquid is preferably 400 ° C. or higher.
More preferably, it is 450 degreeC or more, More preferably, it is 500 degreeC or more. When the boiling point was less than 400 ° C., there was a case where jetability during long-term storage was lowered.

  The water used in the ink of the present invention can be any of tap water, distilled water, ion-exchanged water, pure water, ultrapure water, etc., but in terms of storage stability with ink and prevention of clogging, distilled water, Ion exchange water, pure water, and ultrapure water are preferred, and ion exchange water, pure water, and ultrapure water are particularly preferred.

  The ink of the present invention is preferably used as an inkjet ink having a mechanism for applying ink by an inkjet method. In the ink jet system, when the ink viscosity becomes high, there is a case where the ink cannot be ejected normally. The ink of the present invention can be set to a viscosity that can be ejected by an inkjet method by adjusting the ionic liquid and the color material. The viscosity suitable as an inkjet ink is preferably 1 mPa · s or more and less than 50 mPa · s, more preferably 1.2 mPa · s or more and 50 mPa · s or less, and still more preferably 1.5 mPa · s or more. 30 mPa · s or less. When the viscosity exceeds 50 mPa · s, the ink may not be ejected normally.

It is also possible to add an organic solvent to the ink and the ink set in the present invention. For example, organic solvents such as glycols, glycol derivatives, nitrogen-containing solvents, alcohols, sulfur-containing solvents, aliphatic hydrocarbons, aromatic hydrocarbons, alcohols and the like are used.
Next, specific examples of the solvent will be described.
Specific examples of glycols include ethylene glycol, diethylene glycol, propylene glycol, propanediol, butylene glycol, triethylene glycol, 1,5-pentanediol, hexanediol, 1,2,6-hexanetriol, glycerin and the like. .
Specific examples of glycol derivatives include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, diglycerin. And ethylene oxide adducts.
Specific examples of the nitrogen-containing solvent include pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, triethanolamine and the like.
Examples of alcohols include methanol, ethanol, propanol, butanol, hexanol, and benzyl alcohol.
Examples of the sulfur-containing solvent include thiodiethanol, thiodiglycerol, sulfolane, dimethyl sulfoxide and the like.
In addition, propylene carbonate, ethylene carbonate, or the like can be used.
Among the above-mentioned solvents, alcohols such as propanol, butanol and hexanol, glycols such as ethylene glycol, diethylene glycol, propylene glycol, propanediol, butylene glycol, triethylene glycol, 1,5-pentanediol and hexanediol, and Glycol derivatives such as ethylene glycol ethyl ether, diethylene glycol ethyl ether, and diethylene glycol butyl ether are preferably used.

  The organic solvent used in the ink in the present invention may be used alone or in combination of two or more. The content of the water-soluble organic solvent is 25% by mass or less, preferably 20% by mass or less, and more preferably 15% by mass or less. When the amount is more than 25% by mass, the viscosity of the ink is increased, and the ink ejection characteristics sometimes become unstable.

In the present invention, it is also possible to add a surfactant. The surfactant needs to be appropriately selected in consideration of solubility in the ionic liquid. Although the specific example of surfactant is shown below, it is not limited to these.
In the present invention, the ink contains a nonionic surfactant, an anionic surfactant, an amphoteric surfactant, or the like. In addition, any of an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant can be used, and further, the above-described dispersant can also be used.

  Examples of the nonionic surfactant include a polyethylene glycol type and a polyhydric alcohol type. Polyethylene glycol type includes higher alcohol alkylene oxide adduct, alkylphenol alkylene oxide adduct, fatty acid alkylene oxide adduct, polyhydric alcohol fatty acid ester alkylene oxide adduct, fatty acid amide alkylene oxide adduct, polyalkylene glycol alkylene oxide adduct, etc. Is mentioned. On the other hand, examples of the polyhydric alcohol type include glycerol fatty acid esters, polyhydric alcohol alkyl ethers, and alkanolamine fatty acid amides.

  For example, polypropylene glycol ethylene oxide adduct, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan Examples include fatty acid esters, fatty acid alkylol amides, acetylene glycols, oxyethylene adducts of acetylene glycols, aliphatic alkanol amides, glycerin esters, sorbitan esters, and the like.

  Examples of the anionic surfactant include carboxylate, sulfate ester salt, sulfonate salt, and phosphate ester salt. Specifically, alkylbenzene sulfonate, alkylphenyl sulfonate, alkyl naphthalene sulfonate, higher fatty acid salt, sulfate of higher fatty acid ester, sulfonate of higher fatty acid ester, sulfate of higher alcohol ether and sulfone Acid salts, higher alkyl sulfosuccinates, higher alkyl phosphate esters, phosphate esters of higher alcohol ethylene oxide adducts, such as dialkyl sulfosuccinates, alkyl sulfates, dodecylbenzene sulfonates, Benzenesulfonate, isopropylnaphthalenesulfonate, monobutylphenylphenol monosulfonate, monobutylbiphenylsulfonate, monobutylbiphenylsulfonate, dibutylphenylphenol disulfone Acid salts are also effectively used.

  Examples of amphoteric surfactants include carboxylate types such as amino acid type and betaine type, sulfate ester type, sulfonic acid type, and phosphate ester type. There are also alanine type, amidopropyl betaine type, sulfobetaine type, amidoamine oxide type, imidazoline type, etc., specifically, alkyl betaine, sulfobetaine, sulfate betaine, imidazolidone betaine, amidopropyl betaine, aminodipropion. Acid salts and the like can be used.

Examples of the cationic surfactant include tetraalkylammonium salts, alkylamine salts, benzalkonium salts, alkylpyridium salts, imidazolium salts, and the like, such as dihydroxyethyl stearylamine, 2-heptadecenyl-hydroxyethylimidazoline, Examples include lauryl dimethyl benzyl ammonium chloride, cetyl pyridinium chloride, stearamide methyl pyridium chloride, and the like.
In addition, biosurfactants such as spicrispolic acid, rhamnolipid, and lysolecithin can also be used.

  In the present invention, the surfactant may be used alone or in combination of two or more. The amount of the surfactant added to the ink in the present invention is preferably 10% by mass or less, more preferably 0.01 to 5% by mass, and still more preferably 0.1 to 3% by mass with respect to the total mass of the ink. Used in the range of When the addition amount was 5% by mass or more, there were cases where the optical density and the storage stability of the ink deteriorated.

  Next, the treatment liquid will be described. In the present invention, a treatment liquid used in combination with the above ink can also be used. The treatment liquid has a function of aggregating at least the components in the ink, and as the aggregating agent, for example, an organic acid, an inorganic electrolyte, an organic amine salt, or the like having a pKa of 4.5 or less is used.

The organic acid having a pKa of 4.5 or less used in the present invention is specifically arginic acid, citric acid, glycine, glutamic acid, succinic acid, tartaric acid, cysteine, oxalic acid, fumaric acid, phthalic acid, maleic acid , Malonic acid, lysine, malic acid, compounds represented by general formula (5), derivatives of these compounds, and the like.
General formula (5)

In the general formula (5), R ₁ represents an alkyl group, X represents O, CO, NH, NR ₂ (R ₂ represents an alkyl group), S, or SO ₂ , and M represents a hydrogen atom, an alkali Represents a metal or an amine. l is an integer of 1 to 5, n is an integer of 3 to 7, and m is 1 or 2.

Here, in the general formula (5), X is preferably CO, NH, NR, O, and more preferably CO, NH, O. M is preferably H, Li, Na, K, monoethanolamine, diethanolamine, triethanolamine or the like, more preferably H, Na, or K, and still more preferably a hydrogen atom. n is preferably a case where the heterocyclic ring is a 6-membered ring or a 5-membered ring, and more preferably a 5-membered ring. The compound represented by the general formula (5) may be a saturated ring or an unsaturated ring as long as it is a heterocyclic ring. R ₁ is preferably CH ₃ , C ₂ H ₅ , or C ₂ H ₄ OH.

  Specifically, the compound represented by the general formula (5) has a furan, pyrrole, pyrroline, pyrrolidone, pyrone, pyrrole, thiophene, indole, pyridine, quinoline structure, and further has a carboxyl group as a functional group. Compounds. Specifically, 2-pyrrolidone-5-carboxylic acid, 4-methyl-4-pentanolide-3-carboxylic acid, furan carboxylic acid, 2-benzofuran carboxylic acid, 5-methyl-2-furan carboxylic acid, 2,5 -Dimethyl-3-furancarboxylic acid, 2,5-furandicarboxylic acid, 4-butanolide-3-carboxylic acid, 3-hydroxy-4-pyrone-2,6-dicarboxylic acid, 2-pyrone-6-carboxylic acid, 4-pyrone-2-carboxylic acid, 5-hydroxy-4-pyrone-5-carboxylic acid, 4-pyrone-2,6-dicarboxylic acid, 3-hydroxy-4-pyrone-2,6-dicarboxylic acid, thiophenecarboxylic Acid, 2-pyrrolecarboxylic acid, 2,3-dimethylpyrrole-4-carboxylic acid, 2,4,5-trimethylpyrrole-3-propionic acid, 3-hydroxy-2-yne Carboxylic acid, 2,5-dioxo-4-methyl-3-pyrroline-3-propionic acid, 2-pyrrolidinecarboxylic acid, 4-hydroxyproline, 1-methylpyrrolidine-2-carboxylic acid, 5-carboxy-1-methyl Pyrrolidine-2-acetic acid, 2-pyridinecarboxylic acid, 3-pyridinecarboxylic acid, 4-pyridinecarboxylic acid, pyridinedicarboxylic acid, pyridinetricarboxylic acid, pyridinepentacarboxylic acid, 1,2,5,6-tetrahydro-1-methyl Examples include nicotinic acid, 2-quinolinecarboxylic acid, 4-quinolinecarboxylic acid, 2-phenyl-4-quinolinecarboxylic acid, 4-hydroxy-2-quinolinecarboxylic acid, and 6-methoxy-4-quinolinecarboxylic acid. .

  The organic acid is preferably citric acid, glycine, glutamic acid, succinic acid, tartaric acid, phthalic 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. More preferred are pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, or derivatives of these compounds, or salts thereof. More preferred are pyrrolidone carboxylic acid, pyrone carboxylic acid, furan carboxylic acid, coumaric acid, or a compound derivative thereof, or a salt thereof.

  Inorganic electrolytes include alkali metal ions such as lithium ion, sodium ion, potassium ion, aluminum ion, barium ion, calcium ion, copper ion, iron ion, magnesium ion, manganese ion, nickel ion, tin ion, titanium ion, zinc Polyvalent metal ions such as ions, hydrochloric acid, odorous acid, hydroiodic acid, sulfuric acid, nitric acid, phosphoric acid, thiocyanic acid, and acetic acid, succinic acid, lactic acid, fumaric acid, fumaric acid, citric acid, salicylic acid, benzoic acid And the like, and organic carboxylic acids such as salts of organic sulfonic acids.

Specific examples include lithium chloride, sodium chloride, potassium chloride, sodium bromide, potassium bromide, sodium iodide, potassium iodide, sodium sulfate, potassium nitrate, sodium acetate, potassium oxalate, sodium citrate, potassium benzoate and the like. Alkali metal salts and aluminum chloride, aluminum bromide, aluminum sulfate, aluminum nitrate, sodium aluminum sulfate, potassium aluminum sulfate, aluminum acetate, barium chloride, barium bromide, barium iodide, barium oxide, barium nitrate, thiocyanate Barium acid, calcium chloride, calcium bromide, calcium iodide, calcium nitrite, calcium nitrate, calcium dihydrogen phosphate, calcium thiocyanate, calcium benzoate, calcium acetate, salicylic acid Lucium, calcium tartrate, calcium lactate, calcium fumarate, calcium citrate, copper chloride, copper bromide, copper sulfate, copper nitrate, copper acetate, iron chloride, iron bromide, iron iodide, iron sulfate, iron nitrate, oxalic acid Iron, iron lactate, iron fumarate, iron citrate, magnesium chloride, magnesium bromide, magnesium iodide, magnesium sulfate, magnesium nitrate, magnesium acetate, magnesium lactate, manganese chloride, manganese sulfate, manganese nitrate, manganese dihydrogen phosphate , Manganese acetate, manganese salicylate, manganese benzoate, manganese lactate, nickel chloride, nickel bromide, nickel sulfate, nickel nitrate, nickel acetate, tin sulfate, titanium chloride, zinc chloride, zinc bromide, zinc sulfate, zinc nitrate, thiocyanate Examples thereof include salts of polyvalent metals such as zinc acid and zinc acetate.
More preferably, a polyvalent metal salt is used. This is because the polyvalent metal salt is considered to have a larger aggregating ability of the color material in the ink.

  The organic amine compound may be any of primary, secondary, tertiary and quaternary amines and salts thereof. Specific examples include tetraalkylammonium, alkylamine, benzalkonium, alkylpyridium, imidazolium, polyamine, and derivatives or salts thereof. Specifically, amylamine, butylamine, propanolamine, propylamine, ethanolamine, ethylethanolamine, 2-ethylhexylamine, ethylmethylamine, ethylbenzylamine, ethylenediamine, octylamine, oleylamine, cyclooctylamine, cyclobutylamine, cyclohexane Propylamine, cyclohexylamine, diisopropanolamine, diethanolamine, diethylamine, di-2-ethylhexylamine, diethylenetriamine, diphenylamine, dibutylamine, dipropylamine, dihexylamine, dipentylamine, 3- (dimethylamino) propylamine, dimethylethylamine, dimethyl Ethylenediamine, dimethyloctylamine, 1,3-dimethylbutylamine, dimethyl 1,3-propanediamine, dimethylhexylamine, amino-butanol, amino-propanol, amino-propanediol, N-acetylaminoethanol, 2- (2-aminoethylamino) -ethanol, 2-amino-2- Ethyl-1,3-propanediol, 2- (2-aminoethoxy) ethanol, 2- (3,4-dimethoxyphenyl) ethylamine, cetylamine, triisopropanolamine, triisopentylamine, triethanolamine, trioctylamine, Tritylamine, bis (2-aminoethyl) 1,3-propanediamine, bis (3-aminopropyl) ethylenediamine, bis (3-aminopropyl) 1,3-propanediamine, bis (3-aminopropyl) methylamine, Bis (2-ethylhexyl ) Amine, bis (trimethylsilyl) amine, butylamine, butylisopropylamine, propanediamine, propyldiamine, hexylamine, pentylamine, 2-methyl-cyclohexylamine, methyl-propylamine, methylbenzylamine, monoethanolamine, laurylamine, Nonylamine, trimethylamine, triethylamine, dimethylpropylamine, propylenediamine, hexamethylediamine, tetraethylenepentamine, diethylethanolamine, tetramethylammonium chloride, tetraethylammonium bromide, dihydroxyethylstearylamine, 2-heptadecenyl-hydroxyethylimidazoline, lauryl Dimethylbenzylammonium chloride, cetylpyridinium mouth Ride, stearamide methylbiridium chloride, diallyldimethylammonium chloride polymer, diallylamine polymer, monoallylamine polymer and the like can be mentioned.

  As the amine compound, cetylpyridinium chloride, stearamide methylbilidium chloride, diallyldimethylammonium chloride polymer, diallylamine polymer, monoallylamine polymer and the like are preferable. An amine compound having a molecular weight of 500 or more can also be used effectively.

  Flocculants such as organic acids, inorganic electrolytes, and organic amine compounds having a pKa of 4.5 or less may be used alone or in admixture of two or more. Moreover, as addition amount of the organic acid of the coagulant | flocculant in this invention liquid, 0.1-30 mass% with respect to process liquid whole quantity, Preferably it is 0.1-20 mass%, More preferably, it is 0.1-15. Used in mass%. When the addition amount of the flocculant in the treatment liquid is less than 0.01% by mass, the aggregation of the pigment becomes insufficient at the time of ink contact, and the optical density, bleeding, and intercolor bleeding may not be improved. When the amount added exceeds 30% by mass, the jetability during long-term storage sometimes deteriorated.

  In the present invention, by using an ink set using the above-described ink and a treatment liquid containing at least a flocculant, it is possible to improve image quality such as optical density and bleeding. This is considered to be because the color material in the ink is aggregated by mixing the ink and the treatment liquid on the recording medium. That is, it is estimated that by increasing the color material density on the recording medium, the optical density can be increased, and the color material does not diffuse with the ink, so that bleeding can be improved.

  As the treatment liquid, an ionic liquid, an organic solvent, water, or the like can be used in the same manner as the ink. The total content of the ionic liquid, organic solvent, and water in the treatment liquid is 1% by mass to 95% by mass, preferably 1% by mass to 60% by mass, and more preferably 5% by mass to 40% by mass. % Used. When the amount of the water-soluble organic solvent in the liquid is less than 1% by mass, there is a case where a sufficient optical density cannot be obtained, and conversely, when the amount is more than 95% by mass, In some cases, the jetability after long-term storage becomes unstable.

  As the treatment liquid, the same surfactant as that of the ink can be used. The addition amount of the surfactant is preferably less than 10% by mass with respect to the total mass of the ink, more preferably 0.01 to 5% by mass, and still more preferably 0.01 to 3% by mass. . When the addition amount was 10% by mass or more, there were cases where the optical density and the storage stability of the treatment liquid deteriorated.

  It is also possible to include a coloring material in the treatment liquid. As the coloring material contained in the treatment liquid, a dye, a pigment having a sulfonic acid or a sulfonate on the surface, and a self-dispersing pigment are preferable. These color materials are considered to be because the color materials hardly aggregate even when coexisting with the flocculant. By using such a coloring material, the storage stability of the treatment liquid does not deteriorate. As the dye, the pigment having sulfonic acid or sulfonate on the surface, and the self-dispersing pigment, the same pigments as those described as the ink pigment can be used.

  When a pigment is used in the treatment liquid, the volume average particle diameter of the pigment particles is preferably 30 nm or more and 250 nm or less. More preferably, they are 50 nm or more and 200 nm or less, More preferably, they are 75 nm or more and 175 nm or less. When the volume average particle diameter of the particles in the liquid is less than 30 nm, the optical density may be low. On the other hand, when the volume average particle diameter exceeds 250 nm, the dispersion stability of the pigment may not be ensured.

  Here, the number of coarse particles of 5 μm or more in the mixed liquid of the inkjet ink and the treatment liquid is preferably 1,000 / μL or more and 5,000,000 / μL or less. More preferably, it is 2,500 / μL or more and 1,000,000 / μL or less, and further preferably 5,000 / μL or more and 500,000 / μL or less. When the number of coarse particles of 5 μm or more in the mixed liquid of the inkjet ink and the treatment liquid is less than 1,000 particles / μL, the optical density sometimes decreases. When the number of coarse particles exceeds 5 μm and exceeds 5,000,000 particles / μL, the cohesive force is too strong and the ink spread is suppressed, so that white streaks occur and the optical density may be reduced. Turned out to be.

  For the coarse particle number of 5 μm or more in the mixed liquid of ink and processing liquid, the ink and the processing liquid are mixed at a mass ratio of 1: 1, and 2 μL is sampled while stirring, and the Accumizer TM770 Optical Particle Sizer (Particle) is mixed. Measurement was performed using Sizing Systems). In addition, as the parameter at the time of measurement, the density of the pigment was input as the density of the dispersed particles. The density of the pigment can be determined by measuring a powder obtained by heating and drying the pigment dispersion using a hydrometer or a specific gravity bottle.

  In addition, polyethyleneimine, polyamines, polyvinylpyrrolidone, polyethylene glycol, cellulose derivatives such as ethyl cellulose, carboxymethyl cellulose, polysaccharides and derivatives thereof, other water-soluble polymers, acrylic polymer emulsions, polyurethane emulsions, polymer emulsions such as hydrophilic latex , Hydrophilic polymer gels, cyclodextrins, macrocyclic amines, dendrimers, crown ethers, urea and its derivatives, acetamide, silicone surfactants, fluorosurfactants, water, potassium hydroxide, sodium hydroxide, water Alkali metal compounds such as lithium oxide, ammonium hydroxide, triethanolamine, diethanolamine, ethanolamine, 2-amino-2-methyl-1-propano Nitrogen-containing compounds such as calcium hydroxide, alkaline earth metal compounds such as calcium hydroxide, acids such as sulfuric acid, hydrochloric acid and nitric acid, strong acid and weak alkali salts such as ammonium sulfate, pH buffering agents, antioxidants, fungicides, A viscosity modifier, a conductive agent, an ultraviolet absorber, and the like can also be added.

(Inkjet recording)
An image created using the ink, ink tank, recording method, and recording apparatus according to the present invention has few image defects due to clogging, and can provide good image quality.

(Inkjet ink tank)
The ink-jet ink tank according to the present invention can be applied to, for example, the ink tank described in JP-A-2001-138541. In this case, even when ink is filled in the ink tank 20 and ink is ejected from the recording head 18, changes in ink characteristics during long-term storage in the ink tank 20 are suppressed, and in particular, ejectability from the recording head 18 during long-term storage. Is sufficiently satisfactory.

(Inkjet recording method, inkjet recording apparatus)
The ink jet recording method of the present invention uses the ink jet ink set of the present invention to perform printing so that the ink jet ink and the treatment liquid are brought into contact with each other. The ink jet recording apparatus of the present invention comprises a recording head for discharging each liquid of the ink jet ink set of the present invention to a recording medium. These are not only ordinary inkjet recording apparatuses, but also recording apparatuses equipped with heaters for controlling the drying of ink, or intermediate transfer mechanisms, and after printing a recording material on the intermediate, A recording apparatus or the like that transfers to a recording medium can be applied.

  The ink jet recording method (apparatus) of the present invention preferably adopts a thermal ink jet recording method or a piezo ink jet recording method from the viewpoint of the effect of improving bleeding and intercolor bleeding. The cause of this is not clear, but in the case of the thermal ink jet recording method, the ink is heated at the time of ejection and has a low viscosity, but since the temperature of the ink is lowered on the recording medium, the viscosity rapidly increases. Become. For this reason, it is considered that bleeding and intercolor bleeding have an improving effect. On the other hand, in the case of the piezo ink jet method, it is possible to discharge a high-viscosity liquid, and the high-viscosity liquid can suppress spreading in the paper surface direction on the recording medium. It is estimated that there is an improvement effect on intercolor bleeding.

  In the ink jet recording method (apparatus) of the present invention, the mass ratio between the ink application amount and the treatment liquid application amount required for forming one pixel is preferably 1:20 to 20: 1. More preferably, it is 1: 10-10: 1, More preferably, it is 1: 5-5: 1. When the amount of ink applied for inkjet was too small or too large with respect to the amount of treatment liquid applied, there was a case where aggregation was insufficient, resulting in a decrease in optical density, deterioration in bleeding, and deterioration in intercolor bleeding. . Here, the pixel is a grid point formed when a desired image is divided by the minimum distance that can be applied with ink in the main scanning direction and the sub-scanning direction, and is appropriate for each pixel. By applying an appropriate ink set, the color and image density are adjusted, and an image is formed.

  The ink jet ink and the treatment liquid are applied onto the recording medium so that they come into contact with each other. However, when the ink jet ink and the treatment liquid come into contact with each other, the ink aggregates due to the action of the flocculant, and the color develops. This is because the recording method has excellent properties, solid portion unevenness, optical density, bleeding, intercolor bleeding, and drying time. As long as they are in contact with each other, they may be given so as to be adjacent to each other or may be given so as to cover them.

  The order of application to the recording medium is to apply the inkjet ink after applying the treatment liquid. This is because the constituent components of the inkjet ink can be effectively aggregated by applying the treatment liquid first. Any ink jet ink may be applied at any time after the treatment liquid is applied. Preferably, it is 0.5 seconds or less after the treatment liquid is applied.

In the inkjet recording method (apparatus) of the present invention, the liquid mass per drop is preferably 0.01 ng or more and 25 ng or less for both the inkjet ink and the treatment liquid. More preferably, they are 0.5 ng or more and 20 ng or less, More preferably, they are 0.5 ng or more and 15 ng or less. When the liquid mass per drop exceeded 25 ng, there was a case where bleeding deteriorated. This is because the contact angles of the first liquid and the second liquid with respect to the recording medium change depending on the drop amount, and the drop tends to spread toward the paper surface as the drop amount increases. ing. When the liquid mass per drop was less than 0.01 ng, there was a case where the jetting stability deteriorated.
However, in an ink jet apparatus capable of ejecting a plurality of drops from a single nozzle, the drop amount refers to the minimum drop amount that can be printed.

  In the present invention, a recording apparatus provided with a mechanism for heating at least a part of the ink tank and / or the ink application mechanism may be used. This method is effective when an ink using an ionic liquid having a melting point of 25 ° C. or higher is heated to a melting point or higher and applied to a recording medium. In particular, when an ink jet system is used as the ink application mechanism, there is a case where the jetting property is lowered when the ink viscosity is increased. Therefore, a method is known in which the ink viscosity is lowered by heating and applied to the recording medium. However, general ink solvents tend to volatilize by heating and cause problems in ejection properties such as clogging. Existed. When an ionic liquid is used as an ink solvent as in the present invention, since the ionic liquid has a low vapor pressure, it does not volatilize even when heated to a high temperature, and there is no problem with long-term ejection properties. Have.

  In the present invention, a recording apparatus in which a potential difference is provided between the ink application mechanism and the recording medium can also be used. This is because by providing a potential difference between the ink application mechanism and the recording medium, the flying speed and directionality of the ink are improved by the action of the electric field. When an ionic liquid is used as an ink solvent as in the present invention, it is easily affected by an electric field and tends to have a large improvement effect in both flight speed and directionality.

In the present invention, a recording apparatus having a function of removing at least a part of the ink applied on the recording medium from the recording medium can be used. In a normal ink, the ink solvent volatilizes in the atmosphere, so that drying and fixing proceed. As in the present invention, when an ionic liquid is used as the ink solvent, the ionic liquid is difficult to volatilize, and therefore, it remains in the recording medium and is difficult to dry and fix. Therefore, by having a function of removing at least part of the ink from the recording medium, the drying property and the fixing property are improved. As this removal method, a method in which an electric field is applied to the recording medium to remove ink, a method in which water or an organic solvent is brought into contact with the recording medium, and an ink solvent is removed can be considered.
It should be noted that a substance that decomposes the ionic liquid applied to the recording medium may be further applied and solidified or fixed, or the ionic liquid on the recording medium may be sucked and collected.

Hereinafter, preferred embodiments of the ink jet recording apparatus of the present invention will be described in detail with reference to the drawings. In the drawings, members having substantially the same functions are denoted by the same reference numerals, and redundant description is omitted.
FIG. 1 is a perspective view showing an external configuration of a preferred embodiment of an ink jet recording apparatus of the present invention. FIG. 2 is a perspective view showing an internal basic configuration of the ink jet recording apparatus (hereinafter referred to as an image forming apparatus) of FIG. The image forming apparatus 100 of this embodiment has a configuration that operates based on the above-described inkjet recording method of the present invention to form an image. That is, as shown in FIGS. 1 and 2, an image forming apparatus 100 mainly includes an external cover 6, a tray 7 on which a predetermined amount of recording medium 1 such as plain paper can be placed, and the recording medium 1 as an image forming apparatus. A transport roller (transport means) 2 for transporting the paper 100 inside one by one, and an image forming section 8 (image forming means) for forming an image by ejecting ink and liquid composition onto the surface of the recording medium 1, respectively. The main ink tank 4 supplies ink and processing liquid to the sub ink tank 5.

  The conveyance roller 2 is a paper feed mechanism constituted by a pair of rollers rotatably disposed in the image forming apparatus 100, sandwiches the recording medium 1 set on the tray 7, and has a predetermined amount of recording medium 1. Are conveyed into the apparatus 100 one by one at a predetermined timing.

  The image forming unit 8 forms an image with ink on the surface of the recording medium 1. The image forming unit 8 mainly includes a recording head 3, an ink tank 5, a power supply signal cable 9, a carriage 10, a guide rod 11, a timing belt 12, a driving pulley 13, and a maintenance unit 14. Yes.

  The ink tank 5 has ink tanks 51, 52, 53, 54, and 55 in which different color inks or liquid compositions are stored so as to be ejected. These include, for example, black ink (K), yellow ink (Y), magenta ink (M), cyan ink (C), and processing liquid as ink-jet ink. Of course, when the processing liquid is not used or when the processing liquid contains a color material, it is not necessary to provide an ink tank for the processing liquid.

The sub ink tank 5 is provided with an exhaust hole 56 and a supply hole 57, respectively. When the recording head 3 moves to the standby position (or replenishment position), the exhaust pin 151 and the replenishment pin 152 of the replenishing device 15 are inserted into the exhaust hole 56 and the replenishment hole 57, respectively. 5 and the replenishing device 15 can be connected. The replenishing device 15 is connected to the main ink tank 4 via the replenishing pipe 16, and the replenishing device 15 replenishes ink or processing liquid from the main ink tank 4 to the sub ink tank 5 through the replenishing hole 57.
Here, the main ink tank 4 also has main ink tanks 41, 42, 43, 44, 45 in which inks of different colors and processing liquids are respectively stored. These are filled with, for example, black ink (K), yellow ink (Y), magenta ink (M), and cyan ink (C) as the first liquid, and the processing liquid as the second liquid, Each is stored in the image forming apparatus 100 in a detachable manner.

  Further, as shown in FIG. 2, a power feeding signal cable 9 and an ink tank 5 are connected to the recording head 3, and when external image recording information is input to the recording head 3 from the power feeding signal cable 9, the recording head 3 sucks a predetermined amount of ink from each ink tank based on the image recording information and discharges the ink onto the surface of the recording medium. The power supply signal cable 9 also has a role of supplying power necessary for driving the recording head 3 to the recording head 3 in addition to the image recording information.

  The recording head 3 is arranged and held on a carriage 10, and the carriage 10 is connected to a guide rod 11 and a timing belt 12 connected to a driving pulley 13. With such a configuration, the recording head 3 extends along the guide rod 11 and is parallel to the surface of the recording medium 1 and perpendicular to the conveyance direction X (sub-scanning direction) of the recording medium 1 (main scanning direction). It can also be moved in the scanning direction.

  The image forming apparatus 100 includes control means (not shown) that adjusts the drive timing of the recording head 3 and the drive timing of the carriage 10 based on the image recording information. Thereby, an image based on the image recording information can be continuously formed in a predetermined region of the surface of the recording medium 1 that is transported at a predetermined speed along the transport direction X.

  The maintenance unit 14 is connected to a decompression device (not shown) via a tube. Further, the maintenance unit 14 is connected to the nozzle portion of the recording head 3 and has a function of sucking ink from the nozzles of the recording head 3 by reducing the pressure in the nozzles of the recording head 3. By providing the maintenance unit 14, if necessary, excess ink adhering to the nozzles during operation of the image forming apparatus 100 is removed, or evaporation of ink from the nozzles is suppressed when the operation is stopped. be able to.

  FIG. 3 is a perspective view showing an external configuration of another preferred embodiment of the ink jet recording apparatus of the present invention. FIG. 4 is a perspective view showing an internal basic configuration of the ink jet recording apparatus (hereinafter referred to as an image forming apparatus) of FIG. The image forming apparatus 101 of the present embodiment has a configuration that operates based on the above-described inkjet recording method of the present invention to form an image.

  In the image forming apparatus 101 shown in FIGS. 3 and 4, the width of the recording head 3 is equal to or larger than the width of the recording medium 1 and does not have a carriage mechanism, and the sub-scanning direction (conveying direction of the recording medium 1: arrow X). Direction) paper feed mechanism (the transport roller 2 is shown in the present embodiment, but a belt-type paper feed mechanism may be used, for example).

Further, although not shown, the nozzle group for discharging each color (including the processing liquid) is also arranged in the same manner as the ink tanks 51 to 55 are sequentially arranged in the sub scanning direction (conveyance direction of the recording medium 1: arrow X direction). They are arranged in the scanning direction. Other configurations are the same as those of the image forming apparatus 100 shown in FIGS. In the drawing, since the recording head 3 does not move, the sub ink tank 5 is always connected to the replenishing device 15. However, the sub ink tank 5 may be connected to the replenishing device 15 at the time of ink replenishment.

  In the image forming apparatus 101 shown in FIGS. 3 and 4, since the printing in the width direction (main scanning direction) of the recording medium 1 is performed collectively by the recording head 3, the configuration of the apparatus is simpler than the system having the carriage mechanism. Yes, printing speed will be faster.

  The ink, ink set, ink tank, recorded matter, recording method, and recording apparatus according to the present invention are not only on penetrating paper such as plain paper but also on non-permeable media such as art paper, film, and metal. It is possible to apply to what forms an image. Therefore, it can be used in the fields of printed materials, electrical wiring board creation technology, color filter, display device creation technology such as liquid crystal display or organic EL display, medical film recording, DNA information recording, building materials such as wallpaper or decorative plate. Is possible.

  The ink according to the present invention is most effective for the ink jet recording method, but can be applied to offset printing, gravure printing, flexographic printing, screen printing, and the like in addition to the ink jet recording method.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the present invention.

<Ink creation method 1>
500 g of ion exchange water was added to 100 g of the pigment, and an ultrasonic homogenizer was applied. Centrifugation was performed with a centrifugal separator, and the supernatant was removed. After repeating this operation three times, the resulting pigment was dried under reduced pressure.
Ion exchange water and a pigment dispersant were added so that the pigment concentration in the initial pigment dispersion was 15% by mass, and the pH was adjusted to 7.5 using an aqueous sodium hydroxide solution. This pigment dispersion was subjected to an ultrasonic homogenizer to disperse the pigment. The dispersion was subjected to centrifugal separation (8000 rpm × 30 minutes) with a centrifugal separator, and the residue (20% with respect to the total amount) was removed to obtain a pigment dispersion. A solvent, a pigment dispersion, and other additives are added and stirred so as to obtain a predetermined ink composition. The obtained liquid was passed through a 5 μm filter to obtain a desired liquid.

<Ink creation method 2>
500 g of ion exchange water was added to 100 g of the pigment, and an ultrasonic homogenizer was applied. Centrifugation was performed with a centrifugal separator, and the supernatant was removed. After repeating this operation three times, the resulting pigment was dried under reduced pressure.
The aqueous sulfanilic acid solution was heated, and 100 g of the pigment obtained by the above formulation was added with stirring. The mixture was cooled to room temperature with stirring, and 14 g of concentrated nitric acid was added dropwise. To this solution, 10 g of an aqueous NaNO ₂ solution was added and stirred until the reaction was completed. The pigment was desalted. The obtained surface-treated pigment was added with ion-exchanged water so that the pigment concentration was 12% by mass, adjusted to pH 7.5, and then dispersed using an ultrasonic homogenizer. The dispersion was subjected to centrifugal separation (8000 rpm × 30 minutes) with a centrifugal separator, and the residue (20% with respect to the total amount) was removed to obtain a pigment dispersion. A solvent, a pigment dispersion, and other additives are added and stirred so as to obtain a predetermined ink composition. The obtained liquid was passed through a 5 μm filter to obtain a desired liquid.

<Ink creation method 3>
A coloring material and other additives are added to a predetermined solvent and stirred. The obtained liquid was passed through a 5 μm filter to obtain a desired liquid.

(Ink A)
Ink was prepared according to Ink Preparation Method 1.
-composition-
・ Mogu L (Cabot): 4% by mass
・ Styrene-acrylic acid-sodium acrylate copolymer: 1% by mass
1-ethyl-3-methylimidazolium bromide (molecular weight 191 / melting point 25 ° C. or lower)
: 25% by mass
-Acetylene glycol ethylene oxide adduct: 1% by mass
・ Ion-exchanged water: 69% by mass

(Ink B)
Ink was prepared according to Ink Preparation Method 2.
-composition-
・ CI Pigment Blue -15: 3: 4% by mass
1-hexylpyridinium chloride (molecular weight 199 / melting point 25 ° C. or lower): 72% by mass
-Acetylene glycol ethylene oxide adduct: 1% by mass
・ Ion-exchanged water: 23% by mass

(Ink C)
Ink was prepared according to Ink Preparation Method 1.
-composition-
CI Pigment Red-122: 5% by mass
・ Styrene-acrylic acid-sodium acrylate copolymer: 1% by mass
・ 1-ethyl-2,3-dimethylimidazolium chloride (molecular weight 161 / melting point 25 ° C or less)
: 10% by mass
・ Glycerin: 10% by mass
-Acetylene glycol ethylene oxide adduct: 1% by mass
・ Water: 73% by mass

(Ink D)
Ink was prepared according to Ink Preparation Method 1.
-composition-
CI Pigment Yellow -128: 4% by mass
・ Styrene-acrylic acid-sodium acrylate copolymer: 1% by mass
・ N, N-diethyl-N-methyl-N- (2-methoxyethyl) tetrafluoroborate (molecular weight 233 / melting point 25 ° C. or less): 10% by mass
・ Diethylene glycol: 10% by mass
-Acetylene glycol ethylene oxide adduct: 1% by mass
・ Water: 74% by mass

(Ink E)
Ink was prepared according to Ink Preparation Method 1.
-composition-
CI Pigment Yellow -74: 4% by mass
・ Styrene-acrylic acid-sodium acrylate copolymer: 1% by mass
MP-200 (manufactured by TREKSTAR) (molecular weight 422 / melting point 11 ° C.): 6% by mass
・ 1,2-Hexanediol: 18% by mass
・ Polyoxyethylene 2-ethylhexyl ether: 1% by mass
・ Ion exchange water: 70% by mass

(Ink F)
Ink was prepared according to Ink Preparation Method 3.
-composition-
・ CI Direct Blue 199: 4% by mass
・ 1-Butylpyridinium chloride (Molecular weight 172 / Melting point 25 ℃ or less)
: 77.5% by mass
・ Polyoxyethylene stearyl ether: 1% by mass
-N, N'-bis (2-hydroxyethyl) -2-aminoethanesulfonic acid: 1.2% by mass
・ Sodium hydroxide: 0.6% by mass
-Ion exchange water: 15.7% by mass

(Ink G)
Ink was prepared according to Ink Preparation Method 2.
-composition-
CI Pigment Red-122: 4% by mass
1-butylpyridinium trifluoromethanesulfonate (molecular weight 285 / melting point 25 ° C. or lower): 10% by mass
Diglycerin ethylene oxide adduct: 15% by mass
・ Polyoxyethylene stearyl ether: 1% by mass
・ Ion exchange water: 70% by mass

(Ink H)
Ink was prepared according to Ink Preparation Method 2.
-composition-
CI Pigment Red-122: 4% by mass
1-ethyl-3-methylimidazolium bromide (molecular weight 190 / melting point 25 ° C. or less)
: 15% by mass
Diglycerin ethylene oxide adduct: 10% by mass
・ Polyoxyethylene stearyl ether: 1% by mass
・ Ion exchange water: 70% by mass

(Ink I)
Ink was prepared according to Ink Preparation Method 3.
-composition-
・ Cabojet-300: 4% by mass
・ Ethylene glycol: 30% by mass
-Acetylene glycol ethylene oxide adduct: 1% by mass
・ Ion-exchanged water: 65% by mass

(Ink J)
Ink was prepared according to Ink Preparation Method 3.
-composition-
・ CI Direct Blue 199: 4% by mass
・ Isopropyl alcohol: 75% by mass
-Acetylene glycol ethylene oxide adduct: 1% by mass
-N, N'-bis (2-hydroxyethyl) -2-aminoethanesulfonic acid: 1.2% by mass
・ Sodium hydroxide: 0.6% by mass
・ Ion-exchanged water: 18.2% by mass

(Ink K)
Ink was prepared according to Ink Preparation Method 3.
-composition-
・ CI Direct Blue 199: 4% by mass
Polyallylamine acetate (average molecular weight 5000): 75% by mass
-Acetylene glycol ethylene oxide adduct: 1% by mass
-N, N'-bis (2-hydroxyethyl) -2-aminoethanesulfonic acid: 1.2% by mass
・ Sodium hydroxide: 0.6% by mass
・ Ion-exchanged water: 18.2% by mass

(Processing liquid A)
-composition-
・ Diethylene glycol: 10% by mass
-2-furancarboxylic acid (pKa = 2.4): 8% by mass
・ Sodium hydroxide: 0.8% by mass
Diglycerin ethylene oxide adduct: 8% by mass
-Acetylene glycol ethylene oxide adduct: 1% by mass
・ Ion-exchanged water: remaining

(Processing liquid B)
-composition-
・ Diethylene glycol: 15% by mass
Magnesium nitrate hexahydrate: 10% by mass
-Acetylene glycol ethylene oxide adduct: 1% by mass
・ Ion-exchanged water: remaining

(Processing liquid C)
-composition-
・ Diethylene glycol: 10% by mass
・ Polyallylamine: 12% by mass
-Acetylene glycol ethylene oxide adduct: 1% by mass
・ Ion-exchanged water: remaining

As for the solubility of the ionic liquid in water, 100 g of water and 5 g of ionic liquid were mixed and stirred in an environment of 23 ± 0.5 ° C. and left for 1 hour. After standing, the mixed state of water and ionic liquid was confirmed, and it was judged that the solubility of the dissolved one was 5 g or more.
Regarding the melting point of the ionic liquid, the property at the time of storage at 25 ° C. was examined, and it was judged that the liquid state had a melting point of 25 ° C. or less. Furthermore, the value of the melting point in the material physical property table is described.

(Examples 1-11, Comparative Examples 1-3)
The ink set according to Table 1 and Table 2 was printed on FX-C ² paper (Fuji Xerox Co., Ltd.) using a 600 dpi, 1024 nozzle prototype print head (14 ng drop amount). In Examples 1 to 8 and Comparative Examples 1 to 3, only ink was applied to the recording medium. On the other hand, in Examples 9 to 11, printing was performed so that the ink and the treatment liquid were in contact with each other on the recording medium. Printing was performed in a general environment (temperature 23 ± 0.5 ° C., humidity 55 ± 5% RH). When ejecting ink and processing liquid, the mass ratio of the applied amount of ink and processing liquid for forming one pixel was set to 1: 0.2.

<Initial sprayability>
Regarding the initial ejection performance, ink was filled in the ink jet recording apparatus, a nozzle check pattern was printed, and the number of ejection nozzles was observed.
-Evaluation criteria-
◎… All nozzle discharge ○… 90% or more of all nozzles are discharged △… 80% or more of all nozzles discharge less than 90% ×… Less than 80% of all nozzles discharge

<Ejectability after long-term storage>
With respect to jetting properties after long-term storage, the ink jet recording apparatus was filled with ink, and left for 15 days in a general environment without a cap. Thereafter, a nozzle check pattern was printed, and the number of ejection nozzles was observed.
-Evaluation criteria-
◎… All nozzle discharge ○… 90% or more of all nozzles are discharged △… 80% or more of all nozzles discharge less than 90% ×… Less than 80% of all nozzles discharge

<Summary of evaluation results>
The evaluation results are summarized in Tables 1-2.

  As shown in Tables 1 and 2, in Examples 1 to 11 using the ink containing the coloring material and the ionic liquid, the jetting property during long-term storage was excellent.

1 is a perspective view showing a configuration of an appearance of a preferred embodiment of an ink jet recording apparatus of the present invention. FIG. 2 is a perspective view showing an internal basic configuration of the ink jet recording apparatus of FIG. 1. The perspective view which shows the external appearance structure of another suitable one Embodiment of the inkjet recording device of this invention. FIG. 4 is a perspective view showing an internal basic configuration of the ink jet recording apparatus of FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording medium 2 Conveyance roller 3 Recording head 4 Main ink tank 5 Sub ink tank 6 External cover 7 Tray 8 Image formation part 9 Power supply signal cable 10 Carriage 11 Guide rod 12 Timing belt 13 Drive pulley 14 Maintenance unit 15 Replenishment apparatus 16 Replenishment pipe 100 Image forming apparatus

Claims (26)

  An ink containing at least a coloring material, an ionic liquid, and water.   The ink according to claim 1, comprising an ionic liquid having a solubility in 100 g of water of 5 g or more.   The ink according to claim 1, wherein the ink is an inkjet ink used in an inkjet system.   The ink according to any one of claims 1 to 3, wherein the ionic liquid is a compound composed of an organic cation and an anion, and the melting point of the compound is 25 ° C or lower.   The ink according to any one of claims 1 to 4, wherein the molecular weight of the ionic liquid is less than 1000.   The ink according to any one of claims 1 to 5, wherein the addition amount of the ionic liquid is 1% by mass or more and less than 75% by mass with respect to the whole ink.   The ink according to claim 4, wherein the organic cation of the ionic liquid is at least one selected from the group consisting of imidazolium-based, ammonium-based, pyridinium-based, and piperidinium-based.   The anion of the ionic liquid is selected from the group consisting of lithium ion, bromine ion, chlorine ion, lactate ion, hexafluorophosphate, tetrafluoroborate, bis (trifluoromethanesulfonyl) imide, or trifluoromethanesulfonate. The ink according to claim 4, wherein the ink is at least one kind.   The ink according to any one of claims 1 to 8, wherein the color material is at least one selected from the group consisting of dyes, pigments, or colored fine particles.   The ink according to claim 9, wherein the pigment is at least one selected from a self-dispersing pigment, a pigment dispersed using a polymer dispersant, or a microcapsule pigment.   An ink set comprising at least the treatment liquid containing the ink according to claim 1 and at least a flocculant.   The ink set according to claim 11, wherein the aggregating agent is at least selected from the group consisting of an organic acid having an pKa of 4.5 or less, an inorganic electrolyte, and an organic amine compound.   A recorded matter in which an image is formed on a recording medium using the ink according to any one of claims 1 to 10 or the ink set according to claim 11 or 12.   An ink ejection method for ejecting ink using the ink according to any one of claims 1 to 10.   A recording method for applying the ink according to any one of claims 1 to 10 to a recording medium using an inkjet method.   13. A recording method using the ink set according to claim 11 or 12, wherein the ink and the treatment liquid are applied on a recording medium so as to contact each other to form a pattern or an image.   The recording method according to claim 16, wherein the ink and the treatment liquid are applied to the recording medium from the ink set using an inkjet method.   The recording method according to claim 16 or 17, wherein an application amount of the ink forming one pixel and the treatment liquid to the recording medium is in a range of 1:20 to 20: 1 in terms of mass ratio.   An ink tank for storing the ink according to any one of claims 1 to 10 or the ink set according to claim 11 or 12.   An ink ejection apparatus comprising: an ink ejection unit that ejects the ink according to any one of claims 1 to 10.   A recording apparatus comprising: the ink tank according to claim 19; and an ink applying mechanism that applies ink supplied from the ink tank to a recording medium.   20. A recording apparatus comprising the ink tank according to claim 19 and an ink application mechanism that applies ink supplied from the ink tank to a recording medium, wherein at least a part of the pattern or image includes the ink and the processing A recording apparatus that forms a pattern or an image using a liquid.   The recording apparatus according to claim 21 or 22, wherein the ink application mechanism is an ink jet system.   The recording apparatus according to claim 23, wherein the ink is applied to the recording medium at a rate of 0.01 ng to 25 ng per drop.   The recording apparatus according to claim 22, wherein the amount of the ink applied to form one pixel and the amount of the treatment liquid applied is 1:20 to 20: 1 by mass ratio.   The recording apparatus according to claim 21, further comprising a mechanism for heating at least a part of the ink tank or the ink application mechanism.

Images