JP2006199896A - Ink set for inkjet, ink tank for inkjet, method for inkjet recording, and inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink set for inkjet realizing improvement of image density and bleeding (feathering/ICB) by rapidly and sufficiently performing aggregation of coloring material, and to provide an ink tank for inkjet using the same, and to provide a method for inkjet recording and an inkjet recording device. <P>SOLUTION: The invention relates to the ink set for inkjet comprising at least the coloring material, ions containing amphoteric ion substance and a treating liquid which has a liquid character (pH) different from the liquid character (pH) of the ink, and in using a coloring material which manifests an anionic character, the liquid character of the ink is basic and the liquid character of the treating liquid is acidic (the first invention). On the other hand in using a coloring material which manifests a cationic character, the liquid character of the ink is acidic and the liquid character of the treating liquid is basic (the second invention). And the invention relates to the ink tank for inkjet using the same and the method for inkjet recording and the inkjet recording method using the same. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an inkjet ink set, an inkjet ink tank, an inkjet recording method, and an inkjet recording apparatus.

  A so-called inkjet recording apparatus that discharges liquid or molten solid ink from nozzles, slits, porous films, etc., and records on paper, cloth, film, etc. has various advantages such as small size, low cost, quietness, In recent years, not only black single-color printers that provide good print quality on so-called plain paper such as report paper and copy paper, but also many products that can perform full-color recording are on the market, which seems to occupy a large position in the field of recording equipment Became. Above all, the so-called piezo ink-jet method using a piezoelectric element, or the so-called thermal ink-jet method in which droplets are formed by applying thermal energy to perform recording, has many advantages such as high-speed printing and high resolution. Have.

  The ink used in the ink jet recording apparatus is mainly composed of a solvent, a color material, and an additive. For such inks, it is possible to obtain a uniform image with high resolution and high density without blurring on paper, fast drying of ink on paper, good image fastness, and long-term storage stability. There are required characteristics such as good things. In addition, office inkjet printers are required to be capable of high-speed printing as well as high image quality.

In recent years, for the purpose of both improving image density and improving bleeding (feathering / ICB), the ink coloring material is agglomerated on the paper using the second liquid (processing liquid), and the coloring material penetrates into the paper. A method for preventing this problem has been proposed. In order to cause such a color material aggregation action, the use of zwitterionic substances is proposed in, for example, Japanese Patent Application Laid-Open Nos. 9-151346 and 2004-155868.
Japanese Patent Laid-Open No. 9-151346 JP 2004-155868 A

  However, according to recent technical requirements, even in the above proposal, when the aggregation of the coloring material is caused by the zwitterionic substance, the image quality is improved due to the probability / time of encounter (contact) between the coloring material and the zwitterionic substance. There is a problem that the effect is insufficient, and the present situation is that there is a demand for aggregating the color materials more quickly and sufficiently.

  Accordingly, it is an object of the present invention to solve the conventional problems and achieve the following object. That is, an object of the present invention is to quickly and sufficiently agglomerate a color material, and to realize an ink jet ink set capable of improving image density and bleeding (feathering / ICB), and an ink jet ink tank using the same. An inkjet recording method and an inkjet recording apparatus are provided.

The above problem is solved by the following means. That is,
The ink set for inkjet according to the first aspect of the present invention is characterized by comprising a basic ink containing at least an anionic coloring material and an amphoteric ion substance, and an acidic treatment liquid.

  The ink-jet ink of the second aspect of the present invention comprises an acidic ink containing at least a cationic color material and an amphoteric ion substance, and a basic treatment liquid.

  In any of the ink jet inks of the present invention, the zwitterionic substance is preferably a zwitterionic polymer. The zwitterionic polymer is a styrene-acrylic acid-acrylic acid dialkylamino ester polymer, an allylamine-maleic acid copolymer, a vinylpyridine-acrylic acid copolymer, an aminoethyl methacrylate-methacrylic acid copolymer, 2- Vinylpyridine-maleic acid copolymer, 4-vinylpyridine-maleic acid copolymer, 2-vinylpyridine-itaconic acid copolymer, n-methylaminoethyl methacrylate-acrylic acid copolymer, 4-vinylpyridine-itacon It is preferably at least one selected from an acid copolymer, an n-methylallylamine-itaconic acid copolymer, and a 4-vinylpyridine-fumaric acid copolymer. The inkjet ink set according to claim 3.

  In any of the ink jet inks of the present invention, the color material is preferably a pigment. The pigment is preferably a self-dispersing pigment.

  In any of the ink jet inks of the present invention, it is preferable that the treatment liquid contains at least a polyvalent metal compound.

On the other hand, an ink tank for ink jet according to the present invention is characterized by containing the ink set for ink jet according to the present invention.
The ink jet recording method of the present invention uses the ink jet ink sets of the first and second aspects of the present invention to form an image by discharging the ink and the treatment liquid onto a recording medium so as to contact each other. It is characterized by that.
In the ink jet recording method of the present invention, it is preferable that the ink and the treatment liquid supplied from the ink jet ink tank housing the ink jet ink set are ejected onto a recording medium.

  In the ink jet recording method of the present invention, the ratio of the total amount of ink ejected onto the recording medium and the total amount of processing liquid (total amount of ink: total amount of processing liquid) is 1: 0.5 to 1: 0.05. Is preferred.

The ink jet recording apparatus of the present invention is characterized by including a recording head for discharging each liquid in the ink jet ink set of the first and second aspects of the present invention onto a recording medium.
In the ink jet recording apparatus of the present invention, it is preferable that the ink jet recording apparatus further includes an ink jet ink tank for supplying the ink and the treatment liquid from the ink jet ink tank storing the ink jet ink set to the recording head. .

  In the ink jet recording apparatus of the present invention, the ratio of the total amount of ink ejected onto the recording medium and the total amount of processing liquid (total amount of ink: total amount of processing liquid) is 1: 0.5 to 1: 0.05. Is preferred.

  According to the present invention, an ink set for an ink jet capable of aggregating color materials quickly and sufficiently and improving image density and bleeding (feathering / ICB), and an ink jet ink tank using the ink set, An ink jet recording method and an ink jet recording apparatus can be provided.

(Ink set)
The ink set of the present invention comprises ions containing at least a coloring material and an amphoteric ion substance, and a treatment liquid having a liquid property (pH) different from the liquid property (pH) of the ink. When an anionic colorant is used, the ink liquidity is made basic, and the treatment liquid is acidified (first invention). On the other hand, when a colorant exhibiting cationic properties is used, the liquidity of the ink is made acidic, and the liquidity of the treatment liquid is made basic (second invention).

  Here, in order to agglomerate the color material as quickly as possible, the color material in the ink and the aggregating agent in the treatment liquid are mixed and reacted rather than reacting between the materials originally contained in the ink. Good. However, simply adding a material having a polarity opposite to that of the color material into the ink has a problem that the ink itself does not hold or storage stability cannot be ensured.

  Therefore, in the present invention, a zwitterionic substance having color material cohesiveness is added to the ink in a state where the cohesiveness is not exhibited, and the cohesiveness is exhibited when mixed with the processing liquid on the recording medium. To change.

  In other words, when the color material is anionic, the zwitterionic substance does not dissociate the cation group in the molecule, dissolves due to the dissociation of the anion group, and does not react with the color material, that is, the ink liquidity is made basic. deep. Then, the liquid property of the treatment liquid is made acidic, and the cationic group in the zwitterionic substance is dissociated only after the ink is mixed with the treatment liquid, and reacts with the anion group of the color material to cause the color material to aggregate.

  On the other hand, when the color material is cationic, the zwitterionic substance does not dissociate the anion group in the molecule but dissolves by dissociation of the cationic group, and does not react with the color material, that is, the ink liquidity is made acidic. . Then, the treatment liquid is made basic, and the anion group in the zwitterionic substance is not dissociated until the ink is mixed with the treatment liquid, and reacts with the cation group of the color material to cause the color material to aggregate.

  For this reason, in this invention, the reactivity accompanying aggregation of a coloring material has improved, and a coloring material can be aggregated rapidly and fully. Thereby, improvement in image density and improvement in bleeding (feathering / ICB) can be effectively realized.

  In the case of the two-component type, if the permeability of the ink and the treatment liquid to the paper is increased in order to shorten the drying time, the reaction is insufficient for the color material to sufficiently aggregate on the paper, and even a little reaction occurs. In order to increase the contact probability between the coloring material and the zwitterionic substance so as to cause the occurrence of color wrinkles, increasing the amount of the treatment liquid deposited on the paper results in amplifying paper wrinkles after printing.

  However, in the present invention, since the color material can be aggregated quickly and sufficiently, it is not necessary to increase the permeability of the ink and the processing liquid, and a small amount of the processing liquid is applied. Suppression can also be achieved.

  In the ink set of the present invention, when the combination of the basic ink and the acidic treatment liquid is used, the pH of the ink is preferably 8.5 or more, and more preferably 9 or more. Moreover, it is preferable that the pH of a process liquid is 5.5 or less, and it is more preferable that it is 5 or less.

  On the other hand, in the case of a combination of an acidic ink and a basic treatment liquid, the pH of the ink is preferably 5.5 or less, and more preferably 5 or less. Further, the pH of the treatment liquid is preferably 8.5 or more, and more preferably 9 or more.

  Here, the liquidity (pH) of the ink and the treatment liquid can be adjusted, for example, by adding a pH adjuster. Examples of pH adjusters include alkali metal compounds such as potassium hydroxide, sodium hydroxide, and lithium hydroxide that can adjust pH, ammonium hydroxide, triethanolamine, diethanolamine, ethanolamine, 2-amino-2- Biochemical pH such as nitrogen-containing compounds such as methyl-1-propanol, acids such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, acetic acid, citric acid, tartaric acid and lactic acid, strong acid and weak alkali salts such as ammonium sulfate, and good buffer Examples include regulators.

  As the pH, a value measured with a pH / conductivity meter (MPC227 manufactured by METTLER TOLEDO) under a temperature of 23 ± 0.5 ° C. and a humidity of 55 ± 5% RH is used.

  Such a pH adjusting agent is appropriately added so that each of the ink and the treatment liquid is adapted to the above-described liquid (pH) conditions. As will be described in detail below, depending on whether the color material contained in the ink is anionic or cationic, the pH of each of the ink and the treatment liquid is determined, and the type and amount added are selected accordingly. Is.

  Hereinafter, constituent materials of the ink and the treatment liquid will be described.

  The ink can contain at least a coloring material, a zwitterionic substance, a water-soluble solvent, and water.

The color material will be described. As the coloring material, an anionic coloring material and a cationic coloring material are appropriately used according to the purpose. An anionic coloring material is an anionic group (for example, —COOH group, SO ₃ H group, —SO ₄ H group, —SO ₂ group, —PO ₄ H ₂ group, or a salt thereof (alkali metal salt, ammonium salt). A coloring material having salt or the like)). The anionic coloring material may be, for example, a pigment dispersant adsorbed on the pigment having an anionic group. On the other hand, the cationic color material is a color material having a cationic group (for example, a primary to tertiary amino group or a quaternary ammonium base). The cationic coloring material may be, for example, a pigment dispersant adsorbed on the pigment having a cationic group.

  The coloring material may be either a dye or a pigment, but a pigment is particularly preferable. This is presumably because the pigment is more likely to aggregate when mixed with the treatment liquid than the dye. Among the pigments, a pigment dispersed by a polymer dispersant (a polymer material described later), a self-dispersible pigment, a pigment coated with a resin, and a polymer graft pigment are preferable, and a self-dispersible pigment is particularly preferable. Is preferred.

  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 black, cyan, magenta, and yellow primary pigments, specific color pigments such as red, green, blue, brown, and white, metallic luster pigments such as gold and silver, colorless or light color extender pigments, plastic pigments, etc. May be used. In addition, particles having silica or alumina, polymer beads, or the like as a core, and dyes or pigments fixed on the surface thereof, insoluble lakes of dyes, colored emulsions, colored latexes, and the like can also be used as pigments. Furthermore, a pigment newly synthesized for the present invention may be used.

  Specific examples of black pigments include Raven7000, Raven5750, Raven5250, Raven5000 ULTRAII, Raven3500, Raven2000, Raven1500, Raven1250, Raven1200, Raven1125, Raven10, Raven10, Raven10 Regal 330R, Regal 660R, Mogul L, Black Pearls L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 140 0 (manufactured by Cabot Corporation), Color Black FW1, Color Black FW2, Color Black FW2V, Color Black 18, Color Black FW200, Color Black S150, Color Black S160, Color Black P160, Color Black FW S, Color Black FW2V, Color Black FW2V, Color Black FW2V Printex 140V, Special Black 6, Special Black 5, Special Black 4A, Special Black 4 (manufactured by Degussa), No. 25, no. 33, no. 40, no. 47, no. 52, no. 900, no. 2300, MCF-88, MA600, MA7, MA8, MA100 (manufactured by Mitsubishi Chemical Corporation) and the like can be mentioned, but are not limited thereto.

  Examples of cyan pigments include 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.

  Examples of magenta pigments include C.I. I. Pigment Red-5, -7, -12, -48, -48: 1, -57, -112, -122, -123, -146, -168, -184, -202, and the like. It is not limited.

  Examples of yellow pigments include 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, -180, and the like, but are not limited thereto.

A pigment that is self-dispersible in water refers to a pigment that has many water-solubilizing groups on the pigment surface and that can be stably dispersed in water without using a polymer dispersant. Specifically, by applying surface modification treatment such as acid / base treatment, coupling agent treatment, polymer graft treatment, plasma treatment, oxidation / reduction treatment, etc. to ordinary so-called pigments, self-dispersion in water Possible 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.

  In addition, a pigment coated with a resin or the like can be used as the color material. This is called a microcapsule pigment, and not only commercially available ichrocapsule pigments manufactured by Dainippon Ink and Chemicals, Inc. or Toyo Ink, but also microcapsule pigments produced for the present invention may be used. it can.

  Furthermore, it is also possible to use a polymer graft pigment for the pigment as the color material. The polymer graft pigment refers to one in which an organic compound such as a polymer is chemically bonded to the pigment surface.

On the other hand, the dye may be either a water-soluble dye or a disperse dye.
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.

  Specific examples of the disperse dye 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.

The volume average particle diameter of the color material particles is preferably 10 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 in a state where the additive is attached when an additive such as a dispersant is attached to the color material. In the present invention, a Microtrac UPA particle size analyzer (Leeds & Northrup) was used as a volume average particle diameter measuring apparatus. Specifically, the measurement was performed according to a predetermined method with 4 ml of ink placed in a measurement cell. As parameters to be input at the time of instant determination, the viscosity is the viscosity of the ink, and the density of the dispersed particles is the pigment density (color material density).
A more preferable volume average particle size is 20 nm or more and 200 nm or less, and further preferably 30 nm or more and 175 nm or less. When the volume average particle diameter of the color material particles in the ink is less than 10 nm, the optical density may be low. On the other hand, when it exceeds 250 nm, the storage stability may not be ensured.

  The color material is preferably used in the range of 0.1% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 10% by mass or less, based on the total mass of the ink. When the amount of the color material in the ink is less than 0.1% by mass, a sufficient optical density may not be obtained, and when the amount of the color material is more than 20% by mass, the ink is ejected. The characteristics may become unstable.

The color material can be used in combination with a polymer substance in order to disperse the color material or as an aggregation accelerator for the color material. A polymer substance used for dispersing a color material (pigment) is referred to as a polymer dispersant.
As the polymer material used here, any of water-soluble polymer materials and water-insoluble polymer materials such as emulsions and self-dispersing fine particles can be used. Nonionic compounds, anionic compounds, cationic compounds, amphoteric compounds Any compound may be used.

The polymer material has the effect of thickening or aggregating with the flocculant contained in the treatment liquid, and the color material is taken in when the polymer material is agglomerated. I guess. That is, the size and density of the structure when the polymer substance aggregates, the ease of incorporating the color material into the polymer substance, and the like are important in the aggregation rate. The optical density, bleeding, and intercolor bleeding are improved by selecting a colorant, a polymer substance, and an aggregating agent in the processing liquid so as to optimize these combinations.
In the present invention, a compound containing a carboxylic acid group is preferably used as the polymer substance. This is presumed to be because the dissociation degree of the carboxylic acid group is small and the aggregation by the aggregating agent is promoted.

  Specific examples of the polymer substance will be described. Specific examples of the polymer substance include a copolymer of monomers having an α, β-ethylenically unsaturated group. Examples of monomers having an α, β-ethylenically unsaturated group include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid monoester, fumaric acid, fumaric acid monoester, Vinyl sulfonic acid, styrene sulfonic acid, sulfonated vinyl naphthalene, vinyl alcohol, acrylamide, methacryloxyethyl phosphate, bismethacryloxyethyl phosphate, methacryloxyethyl phenyl acid phosphate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, styrene, α-methyl Styrene derivatives such as styrene and vinyltoluene, vinylcyclohexane, vinylnaphthalene, vinylnaphthalene derivatives, alkyl acrylates, phenyl acrylates Ether, alkyl methacrylate, phenyl methacrylate, methacrylic acid cycloalkyl ester, crotonic acid alkyl ester, itaconic acid dialkyl esters, maleic acid dialkyl ester and the like.

  A copolymer obtained by copolymerizing a single monomer or a plurality of monomers having the α, β-ethylenically unsaturated group is suitably used as the polymer substance in the present invention. Specific examples of the copolymer include styrene-styrenesulfonic acid copolymer, styrene-maleic acid copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid copolymer, vinylnaphthalene-maleic acid copolymer. Polymer, vinyl naphthalene-methacrylic acid copolymer, vinyl naphthalene-acrylic acid copolymer, alkyl acrylate ester-acrylic acid copolymer, alkyl methacrylate-methacrylic acid, styrene-alkyl methacrylate-methacrylic acid copolymer Examples thereof include a polymer, a styrene-alkyl acrylate ester-acrylic acid copolymer, a styrene-methacrylic acid phenyl ester-methacrylic acid copolymer, and a styrene-methacrylic acid cyclohexyl ester-methacrylic acid copolymer.

These polymer materials are preferably selected in consideration of the affinity with the colorant (pigment), the cohesiveness of the polymer material itself, and the like based on the acid value and the like. Specifically, the polymer substance has an acid value of 30 KOH mg / g or more and less than 150 KOH mg / g, or an acid value of 150 KOH mg / g or more and a neutralization degree of 80% or less. It is preferable to use it.
When the acid value of the polymer compound is 30 KOH mg / g or more and less than 150 KOH mg / g, the acid value is more preferably 50 to 120 KOH mg / g, and still more preferably 70 to 120 KOH mg / g. When the acid value is less than 30 KOHmg / g, ink ejection (ejection) stability may be lowered.
On the other hand, when the acid value of the polymer compound is 150 KOHmg / g or more and the degree of neutralization is 80% or less, the acid value is more preferably 200 to 400 KOHmg / g and the degree of neutralization is 50 to 80%. More preferably, the acid value is 200 to 300 KOH mg / g, and the degree of neutralization is 60 to 80%. When the acid value exceeds 400 KOHmg / g and the degree of neutralization exceeds 80%, the viscosity of the ink may increase and ejection may not be performed normally.

  In this way, it is possible to reduce the amount of water-soluble groups in the polymer material by using a polymer material having a low acid value or using a polymer material having a high acid value with a low degree of neutralization. It is considered that a sufficiently large cohesive force can be obtained even when a coagulant having a weak cohesive force is used in the treatment liquid.

  The weight average molecular weight of the polymer substance is more preferably in the range of 2,000 to 100,000, and still more preferably in the range of 3,500 to 50,000. When the weight average molecular weight of the high molecular weight material is less than 2,000, there are cases where the pigment is not stably dispersed. On the other hand, when the molecular weight exceeds 100,000, the viscosity of the ink is increased, and the discharge property is deteriorated. There is a case.

  The polymer substance is preferably added in a range of 0.01% by mass to 10% by mass with respect to the total mass of the ink, more preferably in a range of 0.05% by mass to 7.5% by mass. Preferably, it is the range of 0.1 mass% or more and 5 mass% or less. When the addition amount exceeds 10% by mass, the liquid viscosity increases, and the ink ejection characteristics may become unstable. On the other hand, when the addition amount is less than 0.01% by mass, the dispersion stability of the pigment may be lowered.

  The zwitterionic substance will be described. The zwitterionic substance is a substance having both a cationic group and an anionic group. Further, the zwitterionic substance may have a nonionic group.

  As the zwitterionic substance, either a low molecular weight substance or a high molecular weight substance can be used. From the viewpoint of effectively exhibiting the aggregation action of the coloring material, a high molecular weight substance (zwitterionic polymer) is used. Is preferred.

  The zwitterionic polymer has, for example, a monomer containing an aliphatic amino group or an aromatic amino group as a cationic group, a monomer having a heteroaromatic ring containing a nitrogen atom, and a carboxylic acid group or a sulfonic acid group as an anionic group. And a polymer including at least a monomer as a polymerization component and a nonionic monomer as a polymerization component.

Specifically, styrene-acrylic acid-acrylic acid dialkylamino ester polymer, allylamine-maleic acid copolymer, vinylpyridine-acrylic acid copolymer, aminoethyl methacrylate-methacrylic acid copolymer, 2-vinylpyridine- Maleic acid copolymer, 4-vinylpyridine-maleic acid copolymer, 2-vinylpyridine-itaconic acid copolymer, n-methylaminoethyl methacrylate-acrylic acid copolymer, 4-vinylpyridine-itaconic acid copolymer Preferred examples include a coalescence, n-methylallylamine-itaconic acid copolymer, and 4-vinylpyridine-fumaric acid copolymer.
These zwitterionic polymers may be used alone or in combination of two or more.

  The weight average molecular weight of the zwitterionic polymer is preferably 600 or more, more preferably 800 or more and less than 50000, and still more preferably 1000 or more and less than 30000. If the molecular weight is too large, for example, the ink ejection characteristics are deteriorated such as nozzle clogging, and if it is too small, the aggregating action on the color material may be weakened.

  The content of the zwitterionic substance is 0.05% by mass or more and 20% by mass or less, preferably 0.1% by mass or more and 10% by mass or less with respect to the total mass of the ink. When the zwitterionic substance in the liquid is less than 0.05% by mass, the aggregation effect of the coloring material is weak and there is a case where the image quality improvement is insufficient, and conversely, when it is more than 20% by mass. In some cases, problems relating to ejection properties of the head, such as nozzle clogging and poor directionality, are likely to occur.

  The water-soluble solvent will be described. The water-soluble solvent can be appropriately used as long as it dissolves in water by 0.1% or more. Specifically, polyhydric alcohols, polyhydric alcohol derivatives, nitrogen-containing solvents, alcohols, sulfur-containing solvents are used. Etc. are used.

Specific examples include polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,5-pentanediol, 1,2,6-hexanetriol, glycerin, tetraethylene glycol, dipropylene. Examples include glycol, 1,2-hexanediol, and polyethylene glycol.
Polyhydric alcohol 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 of glycerin and the like.

Examples of the nitrogen-containing solvent include pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, triethanolamine, diethanolamine and the like.
Examples of alcohols include alcohols such as ethanol, isopropyl alcohol, butyl alcohol, 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.

A water-soluble solvent may be used independently or may be used in mixture of 2 or more types.
The content of the water-soluble solvent is 1% by mass to 60% by mass, preferably 5% by mass to 40% by mass with respect to the total mass of the ink. When the amount of the water-soluble solvent in the liquid is less than 1% by mass, there is a case where a sufficient optical density cannot be obtained. Conversely, when the amount is more than 60% by mass, the viscosity of the ink increases. Ink ejection characteristics may become unstable.

  Explain about water. Water is added in a range that provides the surface tension and viscosity of the ink. The amount of water added is not particularly limited, but is preferably 10% by mass to 99% by mass, and more preferably 30% by mass to 85% by mass with respect to the total mass of the ink.

  The preferred physical properties of the ink will be described. The surface tension of the ink is preferably 20 mN / m or more and 60 mN / m or less. More preferably, it is 20 mN or more and 45 mN / m or less, More preferably, it is 25 mN / m or more and 35 mN / m or less. If the surface tension is less than 20 mN / m, the liquid may overflow on the nozzle surface and printing may not be performed normally. On the other hand, if it exceeds 60 mN / m, the permeability may be slow and the drying time may be slow.

  The viscosity of the ink is preferably 1.2 mPa · s or more and 8.0 mPa · s or less, more preferably 1.5 mPa · s or more and less than 6.0 mPa · s, and still more preferably 1.8 mPa · s or more. Less than 4.5 mPa · s. When the viscosity of the ink is greater than 8.0 mPa · s, the dischargeability may be reduced. On the other hand, when it is smaller than 1.2 mPa · s, the long-term jetting property may deteriorate.

  Next, the processing liquid will be described. The treatment liquid can contain at least a water-soluble solvent and water. Further, in order to promote more effective aggregation of the color material, a flocculant may be included.

  The flocculant will be described. The aggregating agent refers to a substance having an effect of causing thickening or aggregation by reacting with or interacting with components in the ink. Specifically, inorganic electrolytes, organic amine compounds, organic acids and the like are effectively used.

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

Specific examples of alkali metal salts (alkali metal compounds) include lithium chloride, sodium chloride, potassium chloride, sodium bromide, potassium bromide, sodium iodide, potassium iodide, sodium sulfate, potassium nitrate, sodium acetate, and oxalic acid. Examples include potassium, sodium citrate, and potassium benzoate.
On the other hand, specific examples of polyvalent metal salts (polyvalent metal compounds) include aluminum chloride, aluminum bromide, aluminum sulfate, aluminum nitrate, sodium sulfate aluminum, potassium aluminum sulfate, aluminum acetate, barium chloride, barium bromide, iodine. Barium iodide, barium oxide, barium nitrate, barium thiocyanate, calcium chloride, calcium bromide, calcium iodide, calcium nitrite, calcium nitrate, calcium dihydrogen phosphate, calcium thiocyanate, calcium benzoate, calcium acetate, calcium salicylate , 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, iron oxalate , Iron lactate, iron fumarate, Iron phosphate, 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, benzoic acid Manganese, manganese lactate, nickel chloride, nickel bromide, nickel sulfate, nickel nitrate, nickel acetate, tin sulfate, titanium chloride, zinc chloride, zinc bromide, zinc sulfate, zinc nitrate, zinc thiocyanate, zinc acetate, etc. .

Examples of the organic amine compound include primary, secondary, tertiary and quaternary amines and salts thereof.
Specific examples include tetraalkylammonium salts, alkylamine salts, benzalkonium salts, alkylpyridium salts, imidazolium salts, polyamines, etc., for example, isopropylamine, isobutylamine, t-butylamine, 2-ethylhexylamine. , Nonylamine, dipropylamine, diethylamine, trimethylamine, triethylamine, dimethylpropylamine, ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, tetraethylenepentamine, diethanolamine, diethylethanolamine, triethanolamine, tetramethylammonium chloride, tetraethylammonium Bromide, dihydroxyethyl stearylamine, 2-heptadecenyl-hydroxyethyl Imidazoline, lauryldimethylbenzylammonium chloride, cetylpyridinium chloride, stearamide methylpyridium chloride, diallyldimethylammonium chloride polymer, diallylamine polymer, monoallylamine polymer, and onium salts such as sulfonium salts and phosphonium salts of these compounds, Or phosphoric acid ester etc. are mentioned.

  Specific examples of the organic acid include 2-pyrrolidone-5-carboxylic acid, 4-methyl-4-pentanolide-3-carboxylic acid, furan carboxylic acid, 2-benzofuran carboxylic acid, and 5-methyl-2-furan carboxylic acid. 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-hydride Xyl-2-indolecarboxylic acid, 2,5-dioxo-4-methyl-3-pyrroline-3-propionic acid, 2-pyrrolidinecarboxylic acid, 4-hydroxyproline, 1-methylpyrrolidine-2-carboxylic acid, 5- Carboxy-1-methylpyrrolidine-2-acetic acid, 2-pyridinecarboxylic acid, 3-pyridinecarboxylic acid, 4-pyridinecarboxylic acid, pyridinedicarboxylic acid, pyridinetricarboxylic acid, pyridinepentacarboxylic acid, 1,2,5,6- Tetrahydro-1-methylnicotinic acid, 2-quinolinecarboxylic acid, 4-quinolinecarboxylic acid, 2-phenyl-4-quinolinecarboxylic acid, 4-hydroxy-2-quinolinecarboxylic acid, 6-methoxy-4-quinolinecarboxylic acid, Potassium hydrogen phthalate, potassium dihydrogen phosphate, boric acid, sodium citrate, Potassium phosphate, four sodium borohydride, tartaric acid, lactic acid, ammonium chloride, sodium hydroxide, potassium hydroxide, hydrochloric acid, derivatives of these compounds, or compounds such as salts thereof.

  Among these, preferably magnesium chloride, magnesium bromide, magnesium iodide, magnesium sulfate, magnesium nitrate, magnesium acetate, calcium chloride, calcium bromide, calcium nitrate, calcium dihydrogen phosphate, calcium benzoate, calcium acetate, Calcium tartrate, calcium lactate, calcium fumarate, calcium citrate, diallyldimethylammonium chloride polymer, diallylamine polymer, monoallylamine polymer, pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, Coumaric acid, thiophenecarboxylic acid, nicotinic acid, potassium dihydrogen citrate, succinic acid, tartaric acid, lactic acid, potassium hydrogen phthalate, or derivatives of these compounds, or this Which is a salt. More preferred are magnesium chloride, magnesium nitrate, calcium nitrate, diallylamine polymer, pyrrolidone carboxylic acid, pyrone carboxylic acid, furan carboxylic acid, coumaric acid, or a compound derivative thereof, or a salt thereof.

  Furthermore, among these, polyvalent metal salts (polyvalent metal compounds) are particularly suitable. The flocculant may be used alone or in combination of two or more.

  The addition amount of the flocculant is preferably 0.01% by mass or more and 30% by mass or less with respect to the total mass of the treatment liquid. More preferably, it is 0.1 mass% or more and 15 mass% or less, More preferably, it is 0.25 mass% or more and 10 mass% or less. When the addition amount of the flocculant in the treatment liquid is less than 0.01% by mass, there is a case where the aggregation of the coloring material becomes insufficient at the time of ink contact, and the optical density, bleeding, and intercolor bleeding deteriorate. On the other hand, when the addition amount exceeds 30% by mass, the ejection characteristics may be deteriorated and the liquid may not be ejected normally.

  The water-soluble solvent will be described. As the water-soluble solvent, the same water-soluble solvent as that of the ink can be used.

  The content of the water-soluble solvent is 1% by mass or more and 60% by mass or less, preferably 5% by mass or more and 40% by mass or less with respect to the total mass of the treatment liquid. When the amount of the water-soluble solvent in the treatment liquid is less than 1% by mass, there is a case where sufficient optical density cannot be obtained, and conversely, when the amount is more than 60% by mass, the viscosity of the treatment liquid is low. In some cases, the injection characteristic of the processing liquid becomes unstable.

  Explain about water. Water is added in a range that provides surface tension and viscosity. Although there is no restriction | limiting in particular in the addition amount of water, Preferably, they are 10 mass% or more and 99 mass% or less with respect to the total mass of a process liquid, More preferably, they are 30 mass% or more and 80 mass% or less.

  The preferred physical properties of the treatment liquid will be described. The surface tension of the treatment liquid is preferably 20 mN / m or more and 45 mN / m or less. More preferably, it is 20 mN / m or more and 39 mN / m or less, More preferably, it is 25 mN / m or more and 35 mN / m or less. If the surface tension is less than 20 mN / m, the liquid may overflow on the nozzle surface and printing may not be performed normally. On the other hand, if it exceeds 45 mN / m, the permeability may be slow and the drying time may be slow.

  The viscosity of the treatment liquid is preferably 1.2 mPa · s or more and 8.0 mPa · s or less, more preferably 1.5 mPa · s or more and less than 6.0 mPa · s, and still more preferably 1.8 mPa · s. Or more and less than 4.5 mPa · s. When the viscosity of the treatment liquid is greater than 8.0 mPa · s, the dischargeability may be reduced. On the other hand, when it is smaller than 1.2 mPa · s, the long-term jetting property may deteriorate.

  Next, additives that can be appropriately used for the ink and the treatment liquid will be described.

  A surfactant can also be used for the ink and the treatment liquid. As the surfactant, a compound having a structure having both a hydrophilic part and a hydrophobic part in the molecule can be used effectively. Anionic surfactant, cationic surfactant, amphoteric surfactant, nonionic surfactant Any of the surfactants can be used. Furthermore, the above-mentioned polymer substance (polymer dispersing agent) can also be used as a surfactant.

  Examples of the anionic surfactant include alkylbenzene sulfonate, alkylphenyl sulfonate, alkylnaphthalene sulfonate, higher fatty acid salt, sulfate of higher fatty acid ester, sulfonate of higher fatty acid ester, sulfuric acid of higher alcohol ether. Ester salts and sulfonates, higher alkyl sulfosuccinates, higher alkyl phosphate esters, phosphate esters of higher alcohol ethylene oxide adducts, etc. can be used. Specific examples include dodecylbenzene sulfonate, Benzene sulfonate, isopropyl naphthalene sulfonate, monobutylphenylphenol monosulfonate, monobutylbiphenyl sulfonate, monobutylbiphenyl sulfonate, dibutylphenylphenol disulfonate, etc. They are used to.

  Nonionic surfactants include, 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, Examples include sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid alkylolamide, acetylene glycol, oxyethylene adduct of acetylene glycol, aliphatic alkanolamide, glycerin ester, sorbitan ester and the like.

Examples of the cationic surfactant include tetraalkylammonium salts, alkylamine salts, benzalkonium salts, alkylpyridium salts, imidazolium salts, and the like. Specific examples thereof include dihydroxyethyl stearylamine and 2-heptadecenyl. -Hydroxyethyl imidazoline, 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.

  The amount of the surfactant is preferably less than 10% by mass, more preferably 0.01 to 5% by mass, and still more preferably 0.01 to 3% by mass. When the addition amount is 10% by mass or more, the optical density and the storage stability of the pigment ink may be deteriorated.

In addition, inks and processing liquids are for the purpose of controlling properties such as improved ejection properties, cellulose derivatives such as polyethyleneimine, polyamines, polyvinylpyrrolidone, polyethylene glycol, ethylcellulose, carboxymethylcellulose, polysaccharides and their derivatives, and other water-soluble substances. Polymer emulsion such as polymer, acrylic polymer emulsion, polyurethane emulsion, hydrophilic latex, hydrophilic polymer gel, cyclodextrin, macrocyclic amines, dendrimer, crown ethers, urea and its derivatives, acetamide, silicone surfactant Fluorine surfactants and the like can be added.
In order to adjust conductivity and pH, compounds of alkali metals such as potassium hydroxide, sodium hydroxide, lithium hydroxide, ammonium hydroxide, triethanolamine, diethanolamine, ethanolamine, 2-amino-2-methyl Nitrogen-containing compounds such as -1-propanol, 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, and the like can be added.
In addition, a pH buffer, an antioxidant, a fungicide, a viscosity modifier, a conductive agent, an ultraviolet absorber, and the like can be added as necessary.

(Inkjet recording method, inkjet recording apparatus)
The ink jet recording method of the present invention is a method for forming an image by using the ink jet ink set of the present invention and ejecting the ink and the treatment liquid onto a recording medium so as to contact 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 equipped with a recording device equipped with a heater or the like for controlling ink drying as well as a normal ink jet recording device, or an intermediate transfer mechanism, and eject (print) ink and processing liquid onto the intermediate. Thereafter, a recording apparatus or the like that transfers to a recording medium such as paper can be applied.

In the ink jet recording method (apparatus) of the present invention, the liquid mass per drop is preferably 25 ng or less for both the ink and the treatment liquid. More preferably, they are 0.5 ng or more and 20 ng or less, More preferably, they are 1 ng or more and 8 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 ink and the treatment 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.
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.

  Further, the ink and the treatment liquid are applied on the recording medium so as to be in contact with each other. However, as long as they are in contact with each other, they may be applied so as to be adjacent to each other or to be covered. .

  The order of application to the recording medium is to apply ink after applying the treatment liquid. This is because the colorant in the ink can be effectively aggregated by applying the treatment liquid first. As long as the treatment liquid is applied, the ink may be applied at any time. Preferably, it is 1 second or less, more preferably 0.5 seconds or less after the treatment liquid is applied.

  In the ink jet recording method (apparatus) of the present invention, the ratio of the total amount of ink ejected onto the recording medium and the total amount of processing liquid (total amount of ink: total amount of processing liquid) is 1: 0.5 to 1: 0.05. preferable. When the total amount of the ink is too small or too large with respect to the total amount of the processing liquid, there is a case where the aggregation of the coloring material becomes insufficient, resulting in a decrease in optical density, deterioration of bleeding, and deterioration of bleeding between colors.

  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, replenishment (supply) of ink and processing liquid to the recording head is performed from an ink tank (including a processing liquid tank) filled with each liquid of ink and processing liquid. Is good. The ink tank is preferably a cartridge system that can be attached to and detached from the apparatus, and ink and processing liquid can be easily replenished by replacing the ink tank of this cartridge system.

  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. An image forming unit 8 (image forming unit) for forming an image by ejecting ink and processing liquid onto the surface of the recording medium 1; The main ink tank 4 is configured to supply ink and processing liquid to the sub ink tanks 5 of the forming unit 8.

  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, a sub 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. ing.

  The sub ink tank 5 has sub ink tanks 51, 52, 53, 54, and 55 in which different colors of ink and processing liquid are stored so as to be ejected from the recording head. These include, for example, black ink (K), yellow ink (Y), magenta ink (M), and cyan ink (C) as the first liquid, and processing liquid from the main ink tank 4 as the second liquid. Replenished and paid.

  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 different colors of ink and processing liquid are 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.

  Furthermore, the power supply signal cable 9 and the sub ink tank 5 are connected to the recording head 3, and when external image recording information is input from the power supply signal cable 9 to the recording head 3, the recording head 3 detects the image recording information. Based on the above, a predetermined amount of ink is sucked from each ink tank and discharged 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 the 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).

  Although not shown, the nozzle group for discharging each color (including the treatment liquid) is also provided in the same manner as the sub 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 sub-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, the printing speed is also increased.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example, this invention is not limited by the following Example.

Example 1
-Treatment liquid-
Citric acid: 5 wt. %
Diethylene glycol: 10 wt. %
2-pyrrolidone: 5 wt. %
-Tetramethyldecindiol oxyethylene adduct: 0.5 wt. %
The above composition was mixed, pure water and sodium hydroxide were added, and 100 wt. % Was adjusted. Moreover, pH of this liquid was 3.5.

-Bk ink-
Cabojet-300: 5 wt. %
-Styrene-acrylic acid-acrylic acid dimethylaminoethyl ester copolymer (weight average molecular weight 3000): 5 wt. %
-Glycerin: 20 wt. %
BCBT (diethylene glycol monobutyl ether): 8 wt. %
Oxyethylene oleyl ether: 0.5 wt. %
The above composition was mixed, and pure water and NaOH were further added to add 100 wt. %, And an ink was obtained by filtration using a membrane filter having a pore size of 2 μm. The pH of this ink was 10.9.

-Cyan ink-
Pigment (pigment obtained by surface-treating CI Pigment Blue 15 and introducing a sulfonic acid group): 4 wt. %
N-methylaminoethyl methacrylate-acrylic acid copolymer (weight average molecular weight 5800): 5 wt. %
Diethylene glycol: 20 wt. %
-Tetramethyldecindiol oxyethylene adduct: 3 wt. %
The above composition was mixed, and pure water and NaOH were added to add 100 wt. %, And an ink was obtained by filtration using a membrane filter having a pore size of 2 μm. The pH of this ink was 11.5.

-Magenta ink-
Pigment (pigment obtained by surface-treating CI Pigment Red 122 and introducing a sulfonic acid group): 7 wt. %
Allylamine-maleic acid copolymer (weight average molecular weight 19000): 4 wt. %
-Ethylene glycol: 10 wt. %
-Glycerin: 5 wt. %
Propylene glycol: 5 wt. %
-BCBT: 3 wt. %
-Tetramethyldecindiol oxyethylene adduct: 2.5 wt. %
The above composition was mixed, and pure water and NaOH were further added to add 100 wt. %, And an ink was obtained by filtering using a membrane filter having a pore size of 2 μm. The pH of this ink was 10.8.

-Yellow ink-
Pigment (pigment in which CI Pigment Yellow 128 was surface-treated and a sulfonic acid group was introduced): 6 wt. %
Styrene-methacrylic acid-methacrylic acid dimethylaminoethyl ester copolymer (weight average molecular weight 6200): 5 wt. %
Diethylene glycol: 5 wt. %
1,3-butanediol: 4 wt. %
Triethylene glycol monobutyl ether: 8 wt. %
1,2-hexanediol: 1 wt. %
Oxyethylene lauryl ether: 0.5 wt. %
The above composition was mixed, and pure water and NaOH were added to add 100 wt. %, And an ink was obtained by filtration using a membrane filter having a pore size of 2 μm. The pH of this ink was 11.3.

―Evaluation―
Printing was performed using the obtained ink set. Printing is performed by using a trial print head of 1200 dpi and 256 nozzles (drop amount of 6 ng), ejecting treatment liquid onto FX-P paper (manufactured by Fuji Xerox Co., Ltd.), and then ejecting ink from the top to perform overprinting I went there. Printing was performed in a general environment (temperature 23 ± 0.5 ° C., humidity 55 ± 5% RH). Further, printing was performed so that the mass ratio of the applied amount of the ink and the treatment liquid was 1: 0.2. The evaluation was performed on samples left in a general environment for 24 hours after printing (except for drying time and long-term storage stability). The results are shown in Table 1.

<< O. D (Image density) >>
Four colors of ink were ejected onto the treatment liquid for overprinting, and the optical density of each color was measured using X-Rite 404 (manufactured by X-Rite Co., Ltd.).

《ICB (Blending between colors)》
Intercolor bleeding is evaluated by ejecting four colors of ink adjacent to each other on the processing liquid, printing, and comparing the degree of bleeding at the boundary of each color with a predetermined limit sample to perform sensory evaluation. It was.
-Evaluation criteria-
◎… No or almost no bleeding ○… Slightly oozing △… Breaking has occurred, but acceptable level ×… Severe bleed and out of acceptable range

《Feathering》
A thin line pattern of each ink was printed, and the degree of bleeding of the printed portion was checked against a limit sample to perform sensory evaluation.
-Evaluation criteria-
◎… Small bleed ○: Slightly bleed △… Breaking has occurred, but acceptable level ×… Breaking violently, out of acceptable range

"Drying time"
After printing a 100% coverage pattern for each ink, another FX-P paper is pressed onto the print pattern with a load of 1.9 × 10 ⁴ N / m ² after a predetermined time has elapsed. At this time, the time during which the liquid was not transferred to the pressed FX-P paper side was defined as the drying time.

<Ink storage stability>
Each ink was placed in a thermostatic bath at 80 ° C. for 14 days, and then the particle size distribution was measured with Microtruc UPA. The evaluation criteria are as follows.
A: No change in particle size distribution and average particle size.
○: There are subtle changes in particle size distribution and average particle size.
Δ: Although there is a change in particle size distribution and average particle size, aggregation and / or sedimentation has not occurred x: Aggregation and / or sedimentation has been confirmed visually.

(Example 2)
For the cyan ink in the ink set of Example 1, an ink in which the amount of NaOH was adjusted and the pH was adjusted to 8.8 was prepared, and the other components were evaluated in the same manner as in Example 1 with the same composition.

(Example 3)
Regarding the Yellow ink in the ink set of Example 1, ink having an adjusted amount of NaOH and a pH of 8.1 was prepared, and the same evaluation was performed with the same composition as in Example 1 except for that.

Example 4
Regarding the treatment liquid in the ink set of Example 1, a treatment liquid in which the amount of NaOH was adjusted and the pH was adjusted to 5.1 was prepared, and the same evaluation was performed with the same composition as in Example 1.

(Example 5)
Regarding the treatment liquid in the ink set of Example 1, a treatment liquid in which the amount of NaOH was adjusted and the pH was adjusted to 5.9 was prepared, and the same evaluation was performed with the same composition as in Example 1.

(Example 6)
Regarding the treatment liquid in the ink set of Example 1, 3 wt. %, And a treatment liquid having a pH adjusted to 3.9 was prepared, and the other components were evaluated in the same manner as in Example 1 with the same composition.

(Example 7)
-Treatment liquid-
・ CHES (N-Cyclohexyl-2-aminoethanesulfonic
acid): 5 wt. %
-Glycerin: 10 wt. %
Diethylene glycol: 5 wt. %
Tetramethyldecindiol oxyethylene adduct: 0.8 wt. %
The above composition was mixed, pure water and NaOH were further added, and 100 wt. % To obtain a treatment liquid. The pH of this liquid was 9.8.

-Bk ink composition-
IJX-212C (cationized surface-treated carbon black): 5 wt. %
4-vinylpyridine-itaconic acid copolymer (weight average molecular weight 8400): 2.5 wt. %
Diethylene glycol: 7 wt. %
-Glycerin: 10 wt. %
Tetramethyldecindiol oxyethylene adduct: 1.7 wt. %
The above composition was mixed, and pure water and NaOH were added to add 100 wt. %, And an ink was obtained by filtration using a membrane filter having a pore size of 2 μm. The pH of this ink was 3.9.

―Evaluation―
Evaluation was performed in the same manner as in Example 1 using the obtained ink set. However, ICB is excluded.

(Example 8)
-Treatment liquid-
-BES (good buffer): 4 wt. %
-Glycerin: 7 wt. %
-Ethylene glycol: 8 wt. %
1.2-hexanediol: 4 wt. %
-Tetramethyldecindiol oxyethylene adduct: 0.6 wt. %
The above composition was mixed, pure water and NaOH were further added, and 100 wt. % To obtain a treatment liquid. The pH of this liquid was 7.6.

-Evaluation-
Evaluation was performed in the same manner as in Example 1 using an ink set of the obtained treatment liquid and the same Bk ink as in Example 7. However, ICB is excluded.

Example 9
-Bk ink-
IJX-212C (cationized surface-treated carbon black): 5 wt. %
N-methylaminoethyl methacrylate-acrylic acid copolymer (weight average molecular weight 1500): 3.5 wt. %
Polyethylene glycol (weight average molecular weight 400): 5 wt. %
-Glycerin: 4 wt. %
Propylene glycol: 5 wt. %
1,3-butanediol: 4 wt. %
-Oxyethyleneoxypropylene block polymer: 1 wt. %
The above composition was mixed, pure water and potassium dihydrogen phosphate / NaOH were added, and 100 wt. %, And an ink was obtained by filtration using a membrane filter having a pore size of 2 μm. The pH of this ink was 6.2.

-Evaluation-
Evaluation was conducted in the same manner as in Example 1 using an ink set of the same treatment liquid as in Example 7 and the obtained Bk ink. However, ICB is excluded.

(Comparative Example 1)
In Example 1, when each ink composition was added with hydrochloric acid instead of NaOH, the ink coloring material aggregated and could not function as an ink. The pH of the liquid after aggregation was 2.4.

(Comparative Example 2)
The same ink as in Example 1 is used, and the treatment liquid is the composition of Example 1, except that citric acid is removed, trishydroxymethylaminomethane is added instead, HCl and water are added, and the pH is 8.9. It was.

  Evaluation was performed in the same manner as in Example 1 using the obtained ink set.

(Comparative Example 3)
-Treatment liquid-
EPPS (3- [4- (2-hydroxyethyl) -1-piperazinyl] propanesulphonic acid): 3 wt. %
4-vinylpyridine-itaconic acid copolymer (weight average molecular weight 8400): 2.5 wt. %
-Glycerinoxyethylene adduct: 4 wt. %
Diethylene glycol: 5 wt. %
Diethylene glycol monobutyl ether: 5.5 wt. %
The above composition was mixed, pure water and NaOH were further added, and 100 wt. % To obtain a treatment liquid. The pH of this liquid was 7.9.

-Bk ink composition-
IJX-212C (cationized surface-treated carbon black): 5 wt. %
-Ethylene glycol: 4 wt. %
Diglycerin: 5 wt. %
-Polyethylene glycol 400: 3 wt. %
-Tetramethyldecindiol oxyethylene adduct: 1.5 wt. %
The above composition was mixed, and pure water and NaOH were added to add 100 wt. %, And an ink was obtained by filtration using a membrane filter having a pore size of 2 μm. The pH of this ink was 4.2.

  From these results, it can be seen that, by using the ink set of this example, the color materials are quickly and sufficiently aggregated, and it is possible to effectively improve the image density and the bleeding (feathering / ICB). Also, by printing a small amount of 10% coverage of the processing liquid with respect to the ink, the image density can be improved and bleeding (feathering / ICB) can be improved, so that the drying time can be shortened and paper wrinkles can be suppressed. Recognize.

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 of FIG. 1. It is a perspective view which shows the external appearance structure of other 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 100, 101 Image forming apparatus 1 Recording medium 2 Conveying roller 3 Recording head 4 Main ink tank 5 Sub ink tank 6 External cover 7 Tray 8 Image forming part 9 Power supply signal cable 10 Carriage 11 Guide rod 12 Timing belt 13 Drive pulley 14 Maintenance unit 15 Replenisher

Claims (14)

  An ink-jet ink set comprising: a basic ink containing at least an anionic coloring material and an amphoteric ionic substance; and an acidic treatment liquid.   An ink-jet ink set comprising: an acidic ink containing at least a cationic coloring material and a zwitterionic substance; and a basic treatment liquid.   The inkjet ink set according to claim 1, wherein the zwitterionic substance is a zwitterionic polymer.   The zwitterionic polymer is styrene-acrylic acid-acrylic acid dialkylamino ester polymer, allylamine-maleic acid copolymer, vinylpyridine-acrylic acid copolymer, aminoethyl methacrylate-methacrylic acid copolymer, 2-vinylpyridine. -Maleic acid copolymer, 4-vinylpyridine-maleic acid copolymer, 2-vinylpyridine-itaconic acid copolymer, n-methylaminoethyl methacrylate-acrylic acid copolymer, 4-vinylpyridine-itaconic acid copolymer The inkjet ink set according to claim 3, wherein the ink set is at least one selected from a polymer, an n-methylallylamine-itaconic acid copolymer, and a 4-vinylpyridine-fumaric acid copolymer.   The ink set for inkjet according to claim 1 or 2, wherein the color material is a pigment.   The ink set for inkjet according to claim 1, wherein the color material is a self-dispersing pigment.   The inkjet ink set according to claim 1, wherein the treatment liquid contains at least a polyvalent metal compound.   An ink-jet ink tank comprising the ink-jet ink set according to any one of claims 1 to 7. An inkjet recording method using an inkjet ink set,
The inkjet ink set is the inkjet ink set according to any one of claims 1 to 7,
An ink jet recording method, wherein the ink and the treatment liquid are ejected onto a recording medium so as to contact each other to form an image.   The ink jet recording method according to claim 9, wherein the ink and the treatment liquid supplied from an ink jet ink tank containing the ink jet ink set are ejected onto a recording medium.   10. The ratio of the total amount of ink ejected onto the recording medium and the total amount of processing liquid (total amount of ink: total amount of processing liquid) is 1: 0.5 to 1: 0.05. 11. Inkjet recording method. An inkjet recording apparatus including a recording head for discharging each liquid in an inkjet ink set to a recording medium,
The inkjet ink set is the inkjet ink set according to any one of claims 1 to 7.
An ink jet recording apparatus.   The ink jet recording apparatus according to claim 12, further comprising an ink jet ink tank for supplying the ink and the processing liquid from the ink jet ink tank storing the ink jet ink set to the recording head. .   13. The ratio of the total amount of ink ejected onto the recording medium and the total amount of processing liquid (total amount of ink: total amount of processing liquid) is 1: 0.5 to 1: 0.05. Inkjet recording apparatus.

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