JP2012188609A - Ink set and inkjet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink set excellent in rubbing resistance and discharge stability.SOLUTION: The ink set of black, cyan, magenta and yellow colors comprises at least water, a pigment, a water-soluble organic solvent and urethane resin. When the urethane resin included in the black ink is denoted by (A), and the urethane resin included in each of cyan, magenta and yellow inks is denoted by (B), the ink set satisfies both of 150 nm>(average particle diameter of the black ink)>(average particle diameter of the cyan, magenta and yellow ink)>70 nm and (weight average molecular weight of (A))>(weight average molecular weight of (B)).

Description

  The present invention relates to an ink set and an ink jet recording method.

  Ink-jet pigment inks are required to have high image density, scratch resistance (resistance to dirt when rubbed paper with ink attached), storage stability, ink ejection stability from the head, etc. It has already been known that storage stability and scratch resistance are improved by adding a resin emulsion to the pigment ink.

  However, the ink to which the resin emulsion is added is easily fixed by the ink path and nozzles of the head of the ink jet printer, and there is a problem that ejection failure due to the fixed ink occurs.

  Japanese Patent Application Laid-Open No. 2009-144174 of Patent Document 1 discloses that a self-dispersing pigment and a physical property of each other are provided for the purpose of providing an ink composition having a high OD value (Optical Density: optical density) and good fixability and excellent abrasion resistance. Ink having two types of resin fine particles having different from each other is disclosed. However, the technique described in Patent Document 1 contains two types of resin fine particles in one ink to improve the optical density of an image, and the balance between the member inks constituting the color ink set is particularly good. It is not a consideration. And the ink which added the resin emulsion becomes easy to adhere with the ink path | route and nozzle of the head of an inkjet printer, and there exists a problem that the discharge defect resulting from the adhered ink arises. The problem of ejection failure caused by the resin-added ink sticking to the ink path and nozzles of the head cannot be solved.

The present invention provides an ink set having excellent scratch resistance and ejection stability by changing the molecular weight of urethane resin added in black ink and color ink in an ink set composed of black, cyan, magenta, and yellow. With the goal.
In addition, by applying the present invention to a product, a urethane resin having a large molecular weight is added to a black ink having a large average particle diameter, and a molecular weight is applied to a color ink having a small average particle diameter compared to the black ink. By adding a small urethane resin, it is possible to provide an ink set having excellent scratch resistance and ejection stability.
Ink storage stability, reduction of bleed between black and color, and high OD value of black ink can also be achieved.

The said subject is solved by this invention containing following (1)-(7).
(1) “Black, cyan, magenta, yellow ink set consisting of at least water, pigment, water-soluble organic solvent, urethane resin, and urethane resin contained in black ink included in A, cyan, magenta, yellow ink respectively. An ink set that satisfies the following (1) and (2) simultaneously when the urethane resin to be used is B.
150 nm> Average particle diameter of black ink> Average particle diameter of cyan, magenta, yellow ink>
70 nm (1)
Weight average molecular weight of A> Weight average molecular weight of B (2) ".
(2) “The urethane resin A has a weight average molecular weight of 10,000 to 25,000, and the urethane resin B has a weight average molecular weight of 5,000 to 20,000. Ink set as described in item).
(3) “The ink set according to item (1) or (2), wherein the urethane resin is an emulsion resin of an anionic self-emulsifying ether polyurethane”.
(4) The ink according to any one of (1) to (3), wherein the pigment dispersion used in the ink set is a surfactant-dispersed pigment dispersion and / or a resin-coated pigment dispersion. set".
(5) “An ink jet recording method comprising at least an ink flying step of forming an image by applying a stimulus to the ink according to (1) and causing the ink to fly to form an image”.
(6) “Ink set cartridge, wherein the ink according to the item (1) is contained in a container”.
(7) “An ink recorded matter comprising an image formed using the ink set according to any one of (1) to (4) on a recording medium”.

  As will be understood from the following detailed and specific description, according to the present invention, a urethane resin having a particle diameter smaller than that of the black ink is sufficient for the color ink having a smaller average particle diameter of the pigment than the black ink. An ink set that is excellent in scratch resistance and ejection stability, can achieve high storage stability of ink, reduction of bleed between black and color, and high OD value of black ink can be obtained. The extremely excellent effect of being provided is exhibited. Further, when the average particle diameter of the urethane resin is reduced, the viscosity of the urethane resin emulsion itself is also reduced, and it is difficult to fix the ink when the water content of the ink is evaporated. In addition, on a recording medium with good water absorption, the viscosity of the ink immediately after landing is such that the viscosity of the black ink is greater than that of the color ink. It has an extremely excellent effect.

FIG. 4 is a perspective explanatory view showing a state where an ink cartridge loading unit cover of the ink jet recording apparatus is opened. It is a schematic block diagram explaining the whole structure of an inkjet recording device. It is a schematic enlarged view which shows an example of the inkjet head of this invention. It is the schematic which shows an example of the ink bag of the ink cartridge of this invention. FIG. 5 is a schematic diagram illustrating an ink cartridge in which the ink bag of FIG. 4 is accommodated in a cartridge case.

Hereinafter, the overall image of the present invention will be described.
As described above, the present invention is a black, cyan, magenta, yellow ink set comprising at least water, a pigment, a water-soluble organic solvent, and a urethane resin, and the urethane resin contained in the black ink is represented by A, cyan, magenta, An ink set that satisfies the following (1) and (2) simultaneously when the urethane resin contained in each yellow ink is B;
150 nm> black ink average particle diameter> cyan, magenta,
Yellow ink average particle size> 70 nm (1)
Since the weight average molecular weight of A> B weight average molecular weight (2) is included, the ink set will be described first.

[Ink composition]
The member ink of the ink set of the present invention preferably contains a pigment and a urethane resin as essential components, and preferably contains a dispersant, a wetting agent, a penetrating agent, and water, and further, if necessary, a dispersing agent and a wetting agent. Contains commonly used materials such as penetrants and water. Components such as pH adjusters, antiseptic / antifungal agents, and rust preventive agents may or may not be contained.

[Each ink component]
<Urethane resin>
(1) Role The main role of the urethane resin used in the present invention is to stabilize the dispersion state of the colorant particles in the ink and to improve the storage stability. Another object is to improve the scratch resistance of the ink by forming a film when the ink adheres to the recording medium.

  The addition amount is preferably 0.1% by mass to 20% by mass, and more preferably 0.2% by mass to 10% by mass as the resin solid content. When the content is less than 0.1% by mass, the amount of resin covering the pigment after landing on the recording medium is insufficient, and the scratch resistance is small. When the content is more than 20% by mass, the viscosity of the ink is high. This tends to make it difficult to print with an inkjet method.

The physical properties of the urethane resin will be described. As the particle size of the urethane resin, the average particle size of the primary particles is preferably 30 nm or less, and more preferably 25 nm or less. If the average particle diameter of the urethane resin exceeds 30 nm, the ink added with the urethane resin is likely to clog the nozzle, and the ejection becomes unstable. The average particle size was measured using a Microtrac UPA-150 manufactured by Nikkiso Co., Ltd., and the measurement sample was diluted twice with pure water. The average particle diameter here means a 50% average particle diameter (D50).
The acid value of the urethane resin is preferably in the range of 10 to 120 KOH mg / g, more preferably in the range of 30 to 100 KOH mg / g. Even if the acid value is smaller or larger than the above range, the pigment dispersibility becomes insufficient, and the storage stability and ejection stability are lost.
The viscosity of the urethane resin is preferably in the range of 10 to 1000 mPa · s, and more preferably in the range of 100 to 600 mPa · s. When the viscosity of the urethane resin is less than 10 mPa · s, the dispersibility of the pigment is insufficient when it is converted into an ink, and the storage stability is deteriorated. On the other hand, when the viscosity of the urethane resin is greater than 1000 mPa · s, the viscosity of the ink is high and the ejection stability is deteriorated.

[type]
Examples of the urethane resin include SF460, SF460S, SF420, SF110, SF300, SF361 (Nihon Unicar Co., Ltd.), Bondic series (DIC Corporation), Takerak W, WS series (Mitsui Chemical Polyurethane Co., Ltd.) and the like. It is done.
The resin is present as an O / W emulsion when used as an ink preparation raw material or after ink preparation. In polyurethane resin emulsions, ordinary hydrophilic polyurethane resins that are relatively hydrophilic are emulsified using an emulsifier externally, and functional groups that act as emulsifiers are introduced into the resin itself by means of a copolymerization building. There are self-emulsifying emulsions. Either of them can be used, but care must be taken because there are some differences in the dispersion stability of pigments and emulsions depending on the components of the ink. In various combinations with pigments and dispersants, an anionic self-emulsifying polyurethane emulsion resin is always excellent in dispersion stability. At that time, the polyurethane resin is preferably a polycarbonate type rather than a polyester type, and more preferably an ether type than a polyester or polycarbonate type, in terms of pigment fixation and dispersion stability. The reason is not clear, but the non-ether type is often weak in solvent resistance, and particles tend to aggregate when the ink is stored at high temperature. Although the reason is not clear, the processing time can be shortened by adding the resin emulsion to the aqueous pigment dispersion and the aqueous pigment ink, followed by heat treatment.

  In the ink of the present invention, the urethane resin emulsion may be used alone, or other acrylic resin, styrene-acrylic resin, acrylic silicon resin, and fluororesin emulsion may be used in combination. These resin emulsions can be appropriately selected from commercially available ones as required. Appropriate combinations of resin emulsions can improve image quality and image durability while ensuring ink storage stability.

  Examples of the resin emulsion include J-450, J-734, J-7600, J-352, J-390, J-7100, J-741, J74J, J-511, J-840, and J-775. , HRC-1645, HPD-71 (styrene-acrylic resin emulsion, all manufactured by Johnson Polymer), UVA383MA (acrylic-silicone resin emulsion, manufactured by BASF), AP4710 (acrylic-silicone resin emulsion, Showa High) Molecules), FE4300, FE4500, FE4400 (fluorine resin emulsion, all manufactured by Asahi Glass).

[Pigment]
A pigment is used as the colorant in the present invention. Although there is no limitation in particular as a pigment, For example, the pigments listed below are used suitably. Moreover, you may use these pigments in mixture of multiple types.
Examples of organic pigments include azo, phthalocyanine, anthraquinone, quinacridone, dioxazine, indigo, thioindigo, perylene, isoindolenone, aniline black, azomethine, rhodamine B lake pigment, and carbon black. It is done.
Examples of inorganic pigments include iron oxide, titanium oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chrome yellow, and metal powder.
The carbon black used in the black pigment ink is carbon black produced by the furnace method or the channel method, the primary particle size is 15 to 40 nm, the specific surface area by the BET method is 50 to 300 m ² / g, DBP oil absorption Those having an amount of 40 to 150 ml / 100 g, a volatile content of 0.5 to 10% and a pH value of 2 to 9 are preferred. As such a thing, for example, no. 2300, no. 900, MCF-88, no. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. 2200B (Mitsubishi Chemical Co., Ltd.), Raven700, 5750, 5250, 5000, 3500, 1255 (Made in Colombia), Regal400R, 330R, 660R, MoguL, Monarch700, 800, 880, 900, 1000, 1100, 1300, Monarch1400 (Above, manufactured by Cabot), Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex 35, U, V, 140U, 140V, Special Black 6, 5, 4A, 4 (above, Degussa However, it is not limited to these.

Specific examples of color pigments are listed below.
Examples of pigments that can be used for yellow ink include C.I. I. Pigment Yellow 1 (Fast Yellow G), 2, 3, 12 (Disazo Yellow AAA), 13, 14, 16, 17, 20, 23, 24, 34, 35, 37, 42 (Yellow Iron Oxide), 53, 55 73, 74, 75, 81, 83 (disazo yellow HR), 86, 93, 95, 97, 98, 100, 101, 104, 108, 109, 110, 114, 117, 120, 125, 128, 129, 137, 138, 139, 147, 148, 150, 151, 153, 154, 155, 166, 168, 180, 185, and the like, but are not limited thereto.

Examples of pigments that can be used in magenta ink include C.I. I. Pigment Red 1, 2, 3, 5, 7, 9, 12, 17, 22 (Brilliant First Scarlet), 23, 31, 38, 48: 1 (Permanent Red 2B (Ba)), 48: 2 (Permanent Red 2B) (Ca)), 48: 3 (permanent red 2B (Sr)), 48: 4 (
Permanent Red 2B (Mn)), 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmine 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81 (Rhodamine 6G Lake) ), 83, 88, 92, 97, 101 (Bengara), 104, 105, 106, 108 (Cadmium Red), 112, 114, 122 (Dimethylquinacridone), 123, 146, 149, 166, 168, 170, 172 175, 176, 178, 179, 180, 184, 185, 190, 192, 193, 202, 209, 215, 216, 217, 219, 220, 223, 226, 227, 228, 238, 240, 254, 255 272 and the like, but is not limited thereto.

  Examples of pigments that can be used for cyan ink include C.I. I. Pigment Blue 1, 2, 3, 15 (copper phthalocyanine blue R), 15: 1, 15: 2, 15: 3 (phthalocyanine blue G), 15: 4, 15: 6 (phthalocyanine blue E), 16, 17: 1, 2, 56, 60, 63, 64, bat blue 4, bat blue 60, and the like, but are not limited thereto.

  For neutral colors, red, green and blue are C.I. I. Pigment red 177, 194, 224, C.I. I. Pigment orange 16, 36, 43, 51, 55, 59, 61, 71, C.I. I. Pigment violet 3, 19, 23, 29, 30, 37, 40, 50, C.I. I. Pigment green 7, 36, and the like.

  There is no restriction | limiting in particular in the average particle diameter of the said pigment, According to the objective, it can select suitably, 10 nm-150 nm are preferable, 20 nm-100 nm are more preferable, 30 nm-80 nm are still more preferable. When the average particle diameter exceeds 150 nm, not only the saturation of the printed image is lowered, but also thickening aggregation during ink storage and clogging of the nozzle during printing are likely to occur. On the other hand, when the average particle size of the pigment is less than 10 nm, not only the light resistance is lowered but also the storage stability tends to be deteriorated.

The average particle diameter of the pigment is, for example, a micro-track UPA-150 manufactured by Nikkiso Co., Ltd., and a sample diluted with pure water so that the pigment concentration (mass concentration) in the measurement sample is 0.01% by mass. , Particle refractive index 1.51, particle density 1.4 g / cm ³ , solvent parameter means 50% average particle diameter (D50) measured at 23 ° C. using pure water parameters.

[Dispersant]
The pigments listed above can be made into an inkjet recording liquid by dispersing them in an aqueous medium using a polymer dispersant or a surfactant. As a dispersant for dispersing such a pigment, a normal water-soluble resin or a water-soluble surfactant can be used.
Specific examples of water-soluble resins include styrene, styrene derivatives, vinyl naphthalene derivatives, aliphatic alcohol esters of α, β-ethylenically unsaturated carboxylic acids, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itacon. Examples thereof include block copolymers consisting of at least two monomers selected from acids, itaconic acid derivatives, fumaric acid, fumaric acid derivatives, etc., random copolymers, or salts thereof. These water-soluble resins are alkali-soluble resins that are soluble in an aqueous solution in which a base is dissolved. Among them, a resin having a weight average molecular weight of 3000 to 20000 is used as a dispersion when used in an inkjet recording liquid. It is particularly preferred because of the advantages that it can be reduced in viscosity and can be easily dispersed.

  The simultaneous use of the polymer dispersant and the self-dispersing pigment is a preferable combination because an appropriate dot diameter can be obtained. The reason is not clear, but it is thought as follows.

By containing the polymer dispersant, the penetration into the recording paper is suppressed. On the other hand, since the aggregation of the self-dispersing pigment is suppressed by containing the polymer dispersant, the self-dispersing pigment can smoothly spread in the lateral direction. Therefore, it is considered that the dots spread widely and thinly and ideal dots can be formed.
In addition, specific examples of the water-soluble surfactant that can be used as a dispersant in the present invention are generally classified into nonionic, anionic, and amphoteric, and are appropriately selected and used according to the pigment type or ink formulation.

  Nonionic surfactants include polyoxyethylene lauryl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene alkyl ether such as polyoxyethylene oleyl ether, and polyoxyethylene octylphenyl ether. Polyoxyethylene alkylphenyl ethers such as polyoxyethylene nonylphenyl ether, polyoxyethylene-α-naphthyl ether, polyoxyethylene-β-naphthyl ether, polyoxyethylene monostyryl phenyl ether, polyoxyethylene distyryl phenyl ether, Polyoxyethylene alkyl naphthyl ether, polyoxyethylene monostyryl naphthyl ether, polyoxyethylene And distyryl naphthyl ether. In addition, surfactants such as polyoxyethylene polyoxypropylene block copolymers in which a part of polyoxyethylene of these surfactants is replaced with polyoxypropylene, and aromatic rings such as polyoxyethylene alkylphenyl ether A surfactant obtained by condensing a compound with formalin or the like can also be used.

  The nonionic surfactant has an HLB of preferably 12 to 19.5, more preferably 13 to 19. If the HLB is less than 12, there is a tendency for the dispersion stability to deteriorate due to poor conformity of the surfactant to the dispersion medium. If the HLB exceeds 19.5, the surfactant becomes difficult to adsorb to the pigment, so that the dispersion stability is also reduced. There is a tendency to deteriorate.

  Anionic surfactants include polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene monostyryl phenyl ether sulfate, polyoxyethylene distyryl phenyl ether sulfate, polyoxyethylene alkyl ether phosphorus Acid salt, polyoxyethylene alkyl phenyl ether phosphate, polyoxyethylene monostyryl phenyl ether phosphate, polyoxyethylene distyryl phenyl ether phosphate, polyoxyethylene alkyl ether carboxylate, polyoxyethylene alkyl phenyl ether Carboxylate, polyoxyethylene monostyryl phenyl ether carboxylate, polyoxyethylene distyryl phenyl ether carboxylate, naphthalene Phosphonate formalin condensate, melanin sulfonate formalin condensate, dialkyl sulfosuccinate ester salt, sulfosuccinic acid alkyl disalt, polyoxyethylene alkyl sulfosuccinic acid disalt, alkyl sulfoacetate, α-olefin sulphonate, alkylbenzene sulfone Acid salts, alkylnaphthalene sulfonates, alkyl sulfonates, N-acyl amino acid salts, acylated peptides, soaps and the like can be mentioned.

Further, the pigment can be provided with dispersibility by coating with a resin having a hydrophilic group and encapsulating the pigment.
As a method for microencapsulating a water-insoluble pigment with an organic polymer, all conventionally known methods can be used. Conventionally known methods include chemical production methods, physical production methods, physicochemical methods, mechanical production methods, and the like. In particular,
Interfacial polymerization method (a method in which two types of monomers or two types of reactants are separately dissolved in a dispersed phase and a continuous phase, and both substances are reacted at the interface between them to form a wall film);
In-situ polymerization method (method of supplying a liquid or gas monomer and catalyst, or two reactive substances from either one of the continuous phase core particles to cause a reaction to form a wall film);
・ Liquid-cured coating method (method of forming a wall film by insolubilizing droplets of a polymer solution containing core material particles in a liquid with a curing agent);
-Coacervation (phase separation) method (a method in which a polymer dispersion in which core material particles are dispersed is separated into a coacervate (concentrated phase) and a dilute phase having a high polymer concentration to form a wall film);
・ Liquid drying method (preparing a liquid in which a core material is dispersed in a solution of a wall membrane material, placing the dispersion in a liquid in which the continuous phase of this dispersion is not miscible, and forming a composite emulsion to dissolve the wall membrane material. A method of forming a wall film by gradually removing the medium in the medium);
Melt dispersion cooling method (using a wall film material that melts into a liquid state when heated and solidifies at room temperature, this material is heated and liquefied, the core material particles are dispersed in it, cooled to fine particles, and cooled to the wall. A method of forming a film);
・ Air suspension coating method (Method of forming a wall membrane by suspending powder core material particles in the air with a fluidized bed and suspending them in an air stream while spraying and mixing the coating solution of the wall membrane material) ;
-Spray drying method (a method in which the encapsulated stock solution is sprayed and contacted with hot air to evaporate and dry the volatile components to form a wall film);
-Acid precipitation method (at least a part of anionic groups of organic polymer compounds containing anionic groups is neutralized with a basic compound to give solubility in water and kneaded in an aqueous medium with a colorant. Then, neutralize or acidify with an acidic compound, deposit organic compounds and fix them on the colorant, and then neutralize and disperse))
-Phase inversion emulsification method (a mixture containing an anionic organic polymer having dispersibility in water and a colorant is used as an organic solvent phase, and water is added to the organic solvent phase or And the like).

  Examples of organic polymers (resins) used as the material constituting the microcapsule wall membrane material include polyamide, polyurethane, polyester, polyurea, epoxy resin, polycarbonate, urea resin, melamine resin, phenol resin, and polysaccharide. , Gelatin, gum arabic, dextran, casein, protein, natural rubber, carboxypolymethylene, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, cellulose, ethyl cellulose, methyl cellulose, nitrocellulose, hydroxyethyl cellulose, acetic acid Cellulose, polyethylene, polystyrene, (meth) acrylic acid polymer or copolymer, (meth) acrylic acid ester polymer or copolymer, (meth) acrylic acid (Meth) acrylic acid ester copolymer, styrene- (meth) acrylic acid copolymer, styrene-maleic acid copolymer, sodium alginate, fatty acid, paraffin, beeswax, water wax, hardened beef tallow, carnauba wax, albumin, etc. .

  Among these, organic polymers having an anionic group such as a carboxylic acid group or a sulfonic acid group can be used. Nonionic organic polymers include, for example, polyvinyl alcohol, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, methoxypolyethylene glycol monomethacrylate or their (co) polymers, and 2-oxazoline cationic ring-opening polymers. Is mentioned. In particular, a completely saponified product of polyvinyl alcohol is particularly preferable because it has low water solubility and is easily dissolved in hot water but difficult to dissolve in cold water.

  Further, the amount of the organic polymer constituting the wall membrane material of the microcapsule is 1% by weight or more and 20% by weight or less based on the water-insoluble colorant such as an organic pigment or carbon black. By setting the amount of the organic polymer within the above range, the content of the organic polymer in the capsule is relatively low so that the pigment develops due to the organic polymer covering the pigment surface. Can be suppressed. If the amount of the organic polymer is less than 1% by weight, it is difficult to exert the effect of encapsulation. Conversely, if the amount exceeds 20% by weight, the color developability of the pigment is significantly reduced. In consideration of other characteristics, the amount of the organic polymer is preferably in the range of 5 to 10% by weight based on the water-insoluble colorant.

  That is, since a part of the color material is exposed without being substantially covered, it is possible to suppress a decrease in color developability, and conversely, a part of the color material is not substantially exposed without being exposed. Since it is coated, it is possible to simultaneously exhibit the effect that the pigment is coated. The number average molecular weight of the organic polymers used in the present invention is preferably 2000 or more from the viewpoint of capsule production. Here, “substantially exposed” means not the partial exposure associated with defects such as pinholes and cracks, but a state where it is intentionally exposed.

  It is preferable to select an organic polymer suitable for the microencapsulation method. For example, in the case of interfacial polymerization, polyester, polyamide, polyurethane, polyvinyl pyrrolidone, epoxy resin and the like are suitable. In the case of using the in-situ polymerization method, a polymer or copolymer of (meth) acrylic acid ester, (meth) acrylic acid- (meth) acrylic acid ester copolymer, styrene- (meth) acrylic acid copolymer, Polyvinyl chloride, polyvinylidene chloride, polyamide and the like are suitable. In the case of the liquid curing method, sodium alginate, polyvinyl alcohol, gelatin, albumin, epoxy resin and the like are suitable. In the case of the coacervation method, gelatin, celluloses, casein and the like are suitable. In addition, in order to obtain a fine and uniform microencapsulated pigment, it is possible to use all conventionally known encapsulation methods other than those described above.

  When the phase inversion method or the acid precipitation method is selected as the microencapsulation method, anionic organic polymers are used as the organic polymers constituting the wall membrane material of the microcapsules. The phase inversion method is a composite or composite of an anionic organic polymer having self-dispersibility or solubility in water and a colorant such as a self-dispersion organic pigment or self-dispersion carbon black, or a self-dispersion method. A mixture of a colorant such as a dispersible organic pigment or self-dispersing carbon black, a curing agent, and an anionic organic polymer is used as an organic solvent phase, and water is added to the organic solvent phase, or the organic solvent is submerged in water. In this method, a solvent phase is introduced and microencapsulation is performed while self-dispersion (phase inversion emulsification) is performed. In the above phase inversion method, there is no problem even if the organic solvent phase is mixed with a recording liquid vehicle or additives. In particular, it is more preferable to mix a liquid medium of a recording liquid because a dispersion liquid for recording liquid can be directly produced.

  On the other hand, in the acid precipitation method, a part or all of the anionic group of the anionic group-containing organic polymer is neutralized with a basic compound, and a colorant such as a self-dispersing organic pigment or self-dispersing carbon black, A water-containing cake obtained by a production method comprising a step of kneading in an aqueous medium and a step of neutralizing and acidifying an acidic compound to precipitate an anionic group-containing organic polymer and fixing it to a pigment, This is a method of microencapsulation by neutralizing a part or all of an anionic group using a compound. By doing in this way, the aqueous dispersion containing the anionic microencapsulated pigment which is fine and contains many pigments can be manufactured.

  Examples of the solvent used for microencapsulation as described above include alkyl alcohols such as methanol, ethanol, propanol and butanol; aromatic hydrocarbons such as benzol, toluol and xylol; methyl acetate Esters such as ethyl acetate and butyl acetate; Chlorinated hydrocarbons such as chloroform and ethylene dichloride; Ketones such as acetone and methyl isobutyl ketone; Ethers such as tetrahydrofuran and dioxane; Cellosolves such as methyl cellosolve and butyl cellosolve Etc. The microcapsules prepared by the above method are once separated from these solvents by centrifugation or filtration, and then stirred and redispersed with water and the necessary solvent, and used for the intended present invention. To obtain a recording liquid capable of The average particle diameter of the encapsulated pigment obtained by the above method is preferably 50 nm to 180 nm.

[Water-soluble organic solvent (wetting agent)]
The ink of the present invention contains at least one polyhydric alcohol having an equilibrium water content of 40 wt% or more in an environment of a temperature of 23 ° C. and a relative humidity of 80%. And wetting agent B, which has a relatively low boiling point and viscosity.
In the polyhydric alcohol, the wetting agent A having a boiling point exceeding 250 ° C. at normal pressure includes 1,2,3-butanetriol, 1,2,4-butanetriol (bp190-191 ° C / 24 hPa), glycerin (bp290 ° C), diglycerin (bp 270 ° C./20 hPa), triethylene glycol (bp 285 ° C.), tetraethylene glycol (bp 324-330 ° C.) and the like, and the wetting agent B having a boiling point of 140-250 ° C. is diethylene glycol (bp 245 ° C.). ), 1,3-butanediol (bp 203-204 ° C.) and the like.

  These wetting agent A and wetting agent B are both hygroscopic materials having an equilibrium moisture content of 40 wt% or more in an environment at a temperature of 23 ° C. and a relative humidity of 80%. Evaporation is relatively high. Particularly preferred are those selected from the group consisting of glycerin and 1,3-butanediol. When the combination of the wetting agent A and the wetting agent B is used, the amount ratio B / A (mass ratio) of the wetting agent A and the wetting agent B is the other amount of the wetting agent C and other penetrants described later. Since it depends not a little on the kind and amount of the additive, it cannot be generally stated, but a range of, for example, 10/90 to 90/10 is preferable.

The equilibrium moisture content in the present invention is a petri dish in which a saturated aqueous potassium chloride solution is used and the temperature and humidity in the desiccator is maintained at 23 ± 1 ° C. and relative humidity 80 ± 3%, and 1 g of each water-soluble organic solvent is weighed in the desiccator. Is stored, and the amount of saturated water is determined.
Saturated water content (%) = (water content absorbed in organic solvent / organic solvent) x 100

  In the recording ink of the present invention, in addition to the wetting agents A and B, the remaining wetting agent C may be used instead of or in addition to the wetting agents A and B as necessary. Can be used in combination. Examples of the wetting agent C include polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, sulfur-containing compounds, propylene carbonate, and ethylene carbonate. And other wetting agents.

  Examples of the polyhydric alcohols include dipropylene glycol (bp 232 ° C.), 1,5-pentanediol (bp 242 ° C.), 3-methyl-1,3-butanediol (bp 203 ° C.), propylene glycol (bp 187 ° C.). 2-methyl-2,4-pentanediol (bp 197 ° C.), ethylene glycol (bp 196-198 ° C.), tripropylene glycol (bp 267 ° C.), hexylene glycol (bp 197 ° C.), polyethylene glycol (viscous liquid to solid) , Polypropylene glycol (bp 187 ° C), 1,6-hexanediol (bp253-260 ° C), 1,2,6-hexanetriol (bp178 ° C), trimethylolethane (solid, mp 199-201 ° C), trimethylolpropane ( Solid, mp 61 ° C.).

  Examples of the polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether (bp 135 ° C.), ethylene glycol monobutyl ether (bp 171 ° C.), diethylene glycol monomethyl ether (bp 194 ° C.), diethylene glycol monobutyl ether (bp 231 ° C.), ethylene glycol mono -2-ethylhexyl ether (bp 229 ° C.), propylene glycol monoethyl ether (bp 132 ° C.), and the like.

  Examples of the polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether (bp 237 ° C.) and ethylene glycol monobenzyl ether.

  Examples of the nitrogen-containing heterocyclic compound include N-methyl-2-pyrrolidone (bp 202 ° C.), 1,3-dimethyl-2-imidazolidinone (bp 226 ° C.), ε-caprolactam (bp 270 ° C.), γ-butyrolactone. (Bp 204-205 ° C.) and the like.

  Examples of the amides include formamide (bp 210 ° C.), N-methylformamide (bp 199-201 ° C.), N, N-dimethylformamide (bp 153 ° C.), N, N-diethylformamide (bp 176-177 ° C.) and the like. Can be mentioned.

  Examples of the amines include monoethanolamine (bp 170 ° C), diethanolamine (bp268 ° C), triethanolamine (bp360 ° C), N, N-dimethylmonoethanolamine (139 ° C), N-methyldiethanolamine (bp243 ° C). ), N-methylethanolamine (bp159 ° C.), N-phenylethanolamine (bp282-287 ° C), 3-aminopropyldiethylamine (bp169 ° C), and the like.

  Examples of the sulfur-containing compounds include dimethyl sulfoxide (bp 139 ° C.), sulfolane (bp 285 ° C.), thiodiglycol (bp 282 ° C.), and the like.

Other solid wetting agents are preferably sugars. Examples of the saccharide include monosaccharide, disaccharide, oligosaccharide (including trisaccharide and tetrasaccharide), polysaccharide and the like. Specifically, glucose, mannose, fructose, ribose, xylose, arabinose, galactose, maltose, cellobiose, lactose, sucrose, trehalose, maltotriose and the like can be mentioned. Here, the polysaccharide means a saccharide in a broad sense and is used to include substances widely existing in nature such as α-cyclodextrin and cellulose. The derivatives of these saccharides are represented by the reducing sugars of the saccharides described above (for example, sugar alcohol (general formula: HOCH ₂ (CHOH) nCH ₂ OH (where n represents an integer of 2 to 5)). ), Oxidized sugars (for example, aldonic acid, uronic acid, etc.), amino acids, thioic acids, etc. Among these, sugar alcohols are preferred, and specific examples include maltitol, sorbit and the like.

[Penetration agent]
By adding a penetrant to the ink, the surface tension is reduced, and the penetration of the ink droplets onto the recording medium such as paper increases after the ink droplets have landed, thereby reducing feathering and color bleeding. it can. Surfactants are mainly used as penetrants, and are classified into nonionic, anionic and amphoteric depending on the polarity of the hydrophilic group. Further, it is classified into fluorine type, silicone type, acetylene type, etc. according to the structure of the hydrophobic group.

The appropriate surface tension range in the present invention is 20 to 35 mN / m.
Nonionic surfactants include, for example, polyols, glycol ethers, polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkylphenyl ethers, Examples include polyoxyethylene alkylamine, polyoxyethylene alkylamide, acetylene glycol and the like.

  Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, laurate, polyoxyethylene alkyl ether sulfate, and the like.

  Fluorosurfactants include perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl phosphates, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl betaines, perfluoroalkylamine oxide compounds, etc. Can be mentioned. Generally speaking, commercially available fluorine compounds include Surflon S-111, S-112, S-113, S121, S131, S132, S-141, S-144, S-145 (manufactured by Asahi Glass Co., Ltd.), Fullrad FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431, FC-4430 (manufactured by Sumitomo 3M), MegaFuck F-470, F -1405, F474 (manufactured by DIC), Zonyl FS-300, FSN, FSN-100, FSO, FSO-100 (manufactured by DuPont), F-top EF-351, 352, 801, 802 (manufactured by Gemco), FT -250, 251 (manufactured by Neos), PF-151N, PF-136A, PF-156A (manufactured by OMNOVA), and the like. Among these, FSO, FSO-100, FSN, FSN-100, and FS-300 manufactured by Dupont are preferable because they can provide good print quality and storage stability.

  Examples of the silicone surfactant include polyether-modified silicone compounds. Polyether-modified silicone compounds are side-chain type (pendant type) with a polyether group introduced into the side chain of polysiloxy acid, one-end type with a polyether group introduced into one end of polysiloxane, and both-end type introduced into both ends (ABA type), polysiloxane side-chain end-type with polysiloxane introduced on both side chain and both ends, polysiloxane (A) with polyether group introduced and unintroduced polysiloxane (B) repeated It can be classified into a bonded ABn type, a branched type in which a polyether group is introduced at the end of a branched polysiloxane, and the like. Although there is no particular limitation in the present invention, a side chain type (pendant type) having a structure in which a polyether group is introduced into the side chain of polysiloxane is preferred.

  As commercially available products, KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-618, KF-6011, KF-6015, KF- 6004 (manufactured by Shin-Etsu Chemical Co., Ltd.), SF-3771, SF-8427, SF-8428, SH-3749, SH-8400, FZ-2101, FZ-2104, FZ-2118, FZ-2203, FZ-2207, L -7604 (manufactured by Dow Corning Toray), BYK-345, BYK-346, BYK-348 (manufactured by Big Chemie Japan), and the like.

  As acetylene glycol surfactants, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3,5 -Acetylene glycol type | system | groups, such as a dimethyl- 1-hexyn-3-ol, etc. are mentioned. For example, Surfynol 104, 82, 465, 485, TG (manufactured by Air Products) can be used.

When the surfactant is added as a penetrating agent to the ink, the addition amount is preferably 0.05 to 5% by weight, more preferably 0.1 to 3% by weight.
In the ink of the present invention, two or more surfactants may be used in combination. In order to improve the permeability, a polyol having 8 to 11 carbon atoms such as 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol may be used in combination.

  The other components are not particularly limited and may be appropriately selected as necessary. For example, antifoaming agents, pH adjusters, antiseptic / antifungal agents, rust preventives, antioxidants, ultraviolet absorbers, oxygen An absorber, a light stabilizer, etc. are mentioned.

  There is no restriction | limiting in particular as said antifoamer, According to the objective, it can select suitably, For example, a silicone type antifoamer, a polyether type antifoamer, a fatty-acid ester type | system | group antifoamer etc. are mentioned suitably. These may be used individually by 1 type and may use 2 or more types together. Among these, a silicone type antifoaming agent is preferable at the point which is excellent in the bubble-breaking effect.

  Examples of the antiseptic / antifungal agent include 1,2-benzisothiazolin-3-one, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol, and the like. Can be mentioned.

  The pH adjuster is not particularly limited as long as it can adjust the pH to 7 or more without adversely affecting the ink to be prepared, and any substance can be used according to the purpose. Examples of the pH adjuster include amines such as diethanolamine and triethanolamine, hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide and potassium hydroxide; ammonium hydroxide and quaternary ammonium hydroxide. Quaternary phosphonium hydroxide, alkali metal carbonates such as lithium carbonate, sodium carbonate, potassium carbonate, and the like.

  Examples of the rust inhibitor include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

  Examples of the antioxidant include phenol-based antioxidants (including hindered phenol-based antioxidants), amine-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like.

There is no restriction | limiting in particular as a physical property of the inkjet ink of this invention, According to the objective, it can select suitably, For example, it is preferable that a viscosity, surface tension, pH, etc. are the following ranges.
The viscosity at 25 ° C. is preferably 5 mPa · s to 20 mPa · s, and more preferably 6 mPa · s to 15 mPa · s. If the viscosity exceeds 20 mPa · s, it may be difficult to ensure ejection stability.
The surface tension is preferably 20 mN / m to 40 mN / m at 25 ° C. If the surface tension is less than 20 mN / m, bleeding on the recording medium becomes remarkable and stable jetting may not be obtained. If the surface tension exceeds 40 mN / m, ink penetration into the recording medium is sufficient. However, the drying time may be prolonged.
As said pH, 7-10 are preferable, for example.

[Inkjet recording apparatus]
The ink of the present invention can be suitably used for various recording apparatuses using an ink jet recording system, such as an ink jet recording printer, a facsimile apparatus, a copying apparatus, a printer / fax / copier multifunction machine, and the like. In addition, it has an excellent characteristic that the head does not adhere to a recording apparatus including an ink jet head having an ink repellent layer containing a fluorine-based silane coupling agent or an ink repellent layer containing a silicone resin.

The outline of the ink jet recording apparatus will be described below.
The ink jet recording apparatus shown in FIG. 1 has an apparatus main body (101), a paper feed tray (102) for loading paper mounted on the apparatus main body (101), and an image mounted on the apparatus main body (101). A paper discharge tray (103) for stocking the formed paper and an ink cartridge loading section (104) are provided. On the upper surface of the ink cartridge loading section (104), an operation section (105) such as operation keys and a display is arranged. The ink cartridge loading unit (104) has an openable / closable front cover (115) for attaching and detaching the ink cartridge (200). (111) is the upper cover, and (112) is the front surface of the front cover.
In the apparatus main body (101), as shown in FIGS. 2 and 3, a guide rod (131), which is a guide member horizontally mounted on left and right side plates (not shown), and a stay (132), a carriage (133) ) Is slidably held in the main scanning direction, and is moved and scanned in the direction indicated by the arrow in FIG. 3 by a main scanning motor (not shown).

  The carriage (133) includes a plurality of recording heads (134) including four inkjet recording heads that discharge ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). Are arranged in a direction crossing the main scanning direction, and the ink droplet ejection direction is directed downward.

  As an inkjet recording head constituting the recording head (134), a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change caused by liquid film boiling using an electrothermal transducer such as a heating resistor, and a temperature change A shape memory alloy actuator using a metal phase change, an electrostatic actuator using an electrostatic force, or the like provided as energy generating means for discharging ink can be used.

  The carriage (133) is equipped with a sub tank (135) for each color for supplying ink of each color to the recording head (134). The sub tank (135) is supplied with ink according to the ink set of the present invention from the ink cartridge (200) of the present invention loaded in the ink cartridge loading section (104) via an ink supply tube (not shown). To be replenished.

  On the other hand, as a paper feeding unit for feeding the paper (142) stacked on the paper stacking unit (pressure plate) (141) of the paper feed tray (103), 1 sheet (142) is fed from the paper stacking unit (141). Opposed to the half-moon roller [sheet feeding roller (143)] that separates and feeds the sheet one by one, and the separation pad (144) made of a material having a large friction coefficient, this separation pad (144) It is biased toward the paper feed roller (143).

  A conveying belt (151) for electrostatically adsorbing and conveying the paper (142) as a conveying unit for conveying the paper (142) fed from the paper feeding unit below the recording head (134). A counter roller (152) for conveying the paper (142) sent from the paper supply unit via the guide (145) between the conveying belt (151) and a paper (substantially vertically upward) ( 142) and a leading guide roller 153 urged toward the conveying belt (151) by the holding member (154). (155) and a charging roller (156) which is a charging means for charging the surface of the conveyor belt (151).

  The conveyance belt (151) is an endless belt, is stretched between the conveyance roller (157) and the tension roller (158), and can circulate in the belt conveyance direction. The transport belt (151) includes, for example, a surface layer serving as a sheet adsorbing surface formed of a resin material having a thickness of about 40 μm without resistance control, for example, a copolymer of tetrafluoroethylene and ethylene (ETFE), It has the same material as the surface layer and a back layer (medium resistance layer, earth layer) that has been subjected to resistance control by carbon. On the back side of the conveyance belt (151), a guide member (161) is arranged corresponding to the printing area by the recording head (134). As a paper discharge unit for discharging the paper (142) recorded by the recording head (134), a separation claw (171) for separating the paper (142) from the transport belt (151), and paper discharge A roller (172) and a paper discharge roller (173) are provided, and a paper discharge tray (103) is arranged below the paper discharge roller (172).

  A double-sided paper feeding unit (181) is detachably attached to the back surface of the apparatus main body (101). The double-sided paper feeding unit (181) takes in the paper (142) returned by the reverse rotation of the transport belt (151), reverses it, and feeds the paper again between the counter roller (152) and the transport belt (151). To do. A manual paper feed unit (182) is provided on the upper surface of the double-sided paper feed unit (181).

  In this ink jet recording apparatus, the sheet (142) is separated and fed one by one from the sheet feeding unit, and the sheet (142) fed substantially vertically upward is guided by the guide (145) and the transport belt (151). ) And the counter roller (152). Further, the leading end is guided by the conveying guide (153) and pressed against the conveying belt (151) by the leading end pressure roller (155), and the conveying direction is changed by about 90 °.

  At this time, the conveyance belt (157) is charged by the charging roller (156), and the paper (142) is electrostatically adsorbed to the conveyance belt (151) and conveyed. Therefore, by driving the recording head (134) according to the image signal while moving the carriage (133), ink droplets are ejected onto the stopped sheet (142) to record one line, and the sheet ( 142), the next line is recorded after a predetermined amount is conveyed. Upon receiving a recording end signal or a signal that the rear end of the paper (142) has reached the recording area, the recording operation is finished and the paper (142) is discharged to the paper discharge tray (103).

  When a near-end ink remaining amount in the sub tank (135) is detected, a required amount of ink is supplied from the ink cartridge (200) to the sub tank (135).

  In this ink jet recording apparatus, when the ink in the ink cartridge (200) of the present invention is used up, the casing of the ink cartridge (200) can be disassembled and only the ink bag inside can be replaced. Further, the ink cartridge (200) can supply ink stably even when the ink cartridge (200) is vertically placed and has a front loading configuration. Therefore, even when the upper part of the apparatus main body (101) is closed and installed, for example, even when it is stored in a rack or an object is placed on the upper surface of the apparatus main body (101), the ink The cartridge (200) can be easily replaced.

  Here, an example is described in which the present invention is applied to a serial (shuttle type) ink jet recording apparatus that is scanned by a carriage, but the present invention can be similarly applied to a line type ink jet recording apparatus having a line type head.

  Next, the ink cartridge shown in FIGS. 4 and 5 will be described. After the ink cartridge (200) is filled into the ink bag (241) from the ink inlet (242) and exhausted, the ink inlet (242) is closed by fusion. In use, the needle of the apparatus main body is pierced into the ink discharge port (243) made of a rubber member and supplied to the apparatus.

  The ink bag (241) is formed of a packaging member such as a non-permeable aluminum laminate film. The ink bag (241) is usually housed in a plastic cartridge case (244) and is detachably mounted on various ink jet recording apparatuses.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Synthesis Example 1)
<Preparation of Cyan Pigment Dispersion 1>
With reference to Synthesis Example 1 and Preparation Example 5 described in JP-A-2009-155425, a supplementary test was prepared as described below.
First, as the preparation of the polymer solution, the inside of a 1 liter flask equipped with a mechanical stirrer, thermometer, nitrogen gas introduction tube, reflux tube and dropping funnel was sufficiently replaced with nitrogen gas, and then 11.2 g of styrene, acrylic acid 2.8 g, 12.0 g of lauryl methacrylate, 4.0 g of polyethylene glycol methacrylate, 4.0 g of styrene macromer (manufactured by Toa Gosei Co., Ltd., trade name: AS-6) and 0.4 g of mercaptoethanol were added and the temperature was raised to 65 ° C. Warm up. Next, 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g of lauryl methacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0 g of hydroxyethyl methacrylate, 36.0 g of styrene macromer, 3.6 g of mercaptoethanol, azobisdimethylvaleronitrile A mixed solution of 2.4 g and 18 g of methyl ethyl ketone was dropped into the flask over 2.5 hours.
After completion of dropping, a mixed solution of 0.8 g of azobisdimethylvaleronitrile and 18 g of methyl ethyl ketone was dropped into the flask over 0.5 hours. After aging at 65 ° C. for 1 hour, 0.8 g of azobisdimethylvaleronitrile was added, and further aged for 1 hour. After completion of the reaction, 364 g of methyl ethyl ketone was added to the flask to obtain 800 g of a polymer solution having a concentration of 50% by mass. Next, a part of the polymer solution was dried and measured by gel permeation chromatography (standard: polystyrene, solvent: tetrahydrofuran). The weight average molecular weight was 15000.
28 g of the obtained polymer solution, 26 g of copper phthalocyanine pigment (CI Pigment Cyan 15: 3), 13.6 g of 1 mol / L potassium hydroxide solution, 20 g of methyl ethyl ketone, and 30 g of ion-exchanged water were sufficiently stirred. Thereafter, the mixture was kneaded 20 times using a three-roll mill (manufactured by Noritake Company, trade name: NR-84A). The obtained paste was put into 200 g of ion-exchanged water and sufficiently stirred, and then methyl ethyl ketone and water were distilled off using an evaporator to obtain 160 g of a blue polymer fine particle dispersion having a solid content of 20.0% by mass. It was.

(Measurement method of average particle size)
The average particle size was measured using a sample diluted with pure water so that the pigment concentration (mass concentration) in the measurement sample was 0.01% by mass using Microtrac UPA-150 manufactured by Nikkiso Co., Ltd. did. The average particle size here means a 50% average particle size (D50).
The average particle size (D50%) measured by a particle size distribution measuring device (Microtrac UPA, manufactured by Nikkiso Co., Ltd.) of the obtained polymer fine particles was 93 nm.

(Synthesis Example 2)
<Preparation of magenta pigment dispersion 1>
In Synthesis Example 1, the copper phthalocyanine pigment was changed to C.I. I. A reddish purple polymer fine particle dispersion was obtained in the same manner as in Preparation Example 1, except that the pigment red 122 was used.
The average particle size (D50%) measured by a particle size distribution measuring device (Microtrac UPA, manufactured by Nikkiso Co., Ltd.) of the obtained polymer fine particles was 127 nm.

(Synthesis Example 3)
<Preparation of Yellow Pigment Dispersion 1>
In Synthesis Example 1, the copper phthalocyanine pigment was changed to C.I. I. A yellow polymer fine particle dispersion was obtained in the same manner as in Synthesis Example 1 except that the pigment yellow 74 was used.
The average particle size (D50%) measured with a particle size distribution measuring device (Microtrac UPA, manufactured by Nikkiso Co., Ltd.) of the obtained polymer fine particles was 76 nm.

(Synthesis Example 4)
<Preparation of Cyan Pigment Dispersion 2>
In Synthesis Example 1, a blue polymer fine particle dispersion was obtained in the same manner as in Synthesis Example 1 except that the number of kneading of the three-roll mill was changed from 20 times to 30 times.
The average particle size (D50%) measured by a particle size distribution measuring device (Microtrac UPA, manufactured by Nikkiso Co., Ltd.) of the obtained polymer fine particles was 87 nm.

(Synthesis Example 5)
<Preparation of magenta pigment dispersion 2>
In Synthesis Example 1, the copper phthalocyanine pigment was changed to C.I. I. Pigment Red 122 was used, and a red-purple polymer fine particle dispersion was obtained in the same manner as in Synthesis Example 1 except that the number of kneadings of the three-roll mill was changed from 20 to 30.
The average particle size (D50%) measured by a particle size distribution measuring device (Microtrac UPA, manufactured by Nikkiso Co., Ltd.) of the obtained polymer fine particles was 101 nm.

(Synthesis Example 6)
<Preparation of Yellow Pigment Dispersion 2>
In Synthesis Example 1, the copper phthalocyanine pigment was changed to C.I. I. A yellow polymer fine particle dispersion was obtained in the same manner as in Synthesis Example 1 except that the pigment was changed to Pigment Yellow 74 and the number of kneadings of the three-roll mill was changed from 20 to 30.
The average particle size (D50%) measured by a particle size distribution measuring device (Microtrac UPA, manufactured by Nikkiso Co., Ltd.) of the obtained polymer fine particles was 71 nm.

(Synthesis Example 7)
<Preparation of Cyan Pigment Dispersion 3>
In Synthesis Example 1, a blue polymer fine particle dispersion was obtained in the same manner as in Synthesis Example 1 except that the number of kneading of the three-roll mill was changed from 20 times to 30 times.
The average particle size (D50%) measured by a particle size distribution measuring device (Microtrac UPA, manufactured by Nikkiso Co., Ltd.) of the obtained polymer fine particles was 46 nm.

(Synthesis Example 8)
<Preparation of magenta pigment dispersion 3>
In Synthesis Example 1, the copper phthalocyanine pigment was changed to C.I. I. Pigment Red 122 was used, and a red-purple polymer fine particle dispersion was obtained in the same manner as in Synthesis Example 1 except that the number of kneadings of the three-roll mill was changed from 20 to 30.
The average particle size (D50%) measured by a particle size distribution measuring device (Microtrac UPA, manufactured by Nikkiso Co., Ltd.) of the obtained polymer fine particles was 65 nm.

(Synthesis Example 9)
<Preparation of Yellow Pigment Dispersion 3>
In Synthesis Example 1, the copper phthalocyanine pigment was changed to C.I. I. A yellow polymer fine particle dispersion was obtained in the same manner as in Synthesis Example 1 except that the pigment was changed to Pigment Yellow 74 and the number of kneadings of the three-roll mill was changed from 20 to 30.
The average particle size (D50%) measured by a particle size distribution measuring device (Microtrac UPA, manufactured by Nikkiso Co., Ltd.) of the obtained polymer fine particles was 40 nm.

(Synthesis Example 10)
<Preparation of Black Pigment Dispersion 1>
With reference to Example 2 of JP 2009-114286 A, a test preparation was made as described below.
・ Carbon black (NIPEX150, manufactured by degussa, BET specific surface area 110 m ² / g,
(Average primary particle size 29 nm, pH 4.0, DBP oil absorption 400 g / 100 g)
200 parts by mass of sodium naphthalene sulfonate formalin condensate (Pionine A-45-PN manufactured by Takemoto Yushi Co., Ltd., Naphthalene sulfonic acid dimer, trimer, and tetramer total content = 30% by mass) 5 parts by mass / distilled water 788 parts by mass The above mixture was premixed to prepare a mixed slurry. This was circulated and dispersed in a disk-type media mill (MSC type, manufactured by Mitsui Mining Co., Ltd.) using 0.015 mm zirconia beads and a filling rate of 70% at a peripheral speed of 8 m / s and a liquid temperature of 10 ° C. for 3 minutes, and then centrifuged. Coarse particles were centrifuged with a machine (Model 7700, manufactured by Kubota Corporation) to obtain a black pigment dispersion 1. The average particle size (D50%) of the obtained black pigment dispersion measured with a particle size distribution measuring device (Microtrac UPA, manufactured by Nikkiso Co., Ltd.) was 125 nm.

(Synthesis Example 11)
<Preparation of Black Pigment Dispersion 2>
With reference to Example 1 of JP 2009-114286 A, a test preparation was made as described below.
Carbon black (NIPEX160, manufactured by degussa, BET specific surface area 150 m ² / g,
(Average primary particle size 20 nm, pH 4.0, DBP oil absorption 620 g / 100 g)
175 parts by mass-Naphthalenesulfonic acid sodium formalin condensate (Pionine A-45-PN, Naphthalenesulfonic acid dimer, trimer, and tetramer total content = 50% by mass) manufactured by Takemoto Yushi Co., Ltd. Part / distilled water 650 parts by mass The above mixture was premixed to prepare a mixed slurry. This was circulated and dispersed in a disk type media mill (manufactured by Ashizawa Finetech Co., Ltd., DMR type) using 0.05 mm zirconia beads and a filling rate of 55% at a peripheral speed of 10 m / s and a liquid temperature of 10 ° C. for 3 minutes. Coarse particles were centrifuged with a centrifugal separator (Model 7700, manufactured by Kubota Corporation) to obtain a black pigment dispersion 2. The average particle diameter (D50%) measured with a particle size distribution measuring device (Microtrac UPA, manufactured by Nikkiso Co., Ltd.) of the obtained black pigment dispersion was 100 nm.

(Synthesis Example 12)
<Preparation of Black Pigment Dispersion 3>
With reference to Example 2 of JP 2009-114286 A, a test preparation was made as described below.
・ Carbon black (NIPEX180, manufactured by degussa, BET specific surface area 260 m ² / g,
(Average primary particle size 15 nm, pH 4.5, DBP oil absorption 840 g / 100 g)
150 parts by mass of sodium naphthalene sulfonate formalin condensate (Pionine A-45-PN manufactured by Takemoto Yushi Co., Ltd., Naphthalene sulfonic acid dimer, trimer, and tetramer total content = 50% by mass) 250 mass Part / distilled water 600 parts by mass The above mixture was premixed to prepare a mixed slurry (c). This was circulated and dispersed in a disk type media mill (manufactured by Ashizawa Finetech Co., Ltd., LMZ type) using 0.20 mm zirconia beads and a filling rate of 85% at a peripheral speed of 10 m / s and a liquid temperature of 10 ° C. for 5 minutes. Coarse particles were centrifuged with a centrifugal separator (Model 7700, manufactured by Kubota Corporation) to obtain a black pigment dispersion 3. The average particle size (D50%) of the obtained black pigment dispersion measured with a particle size distribution measuring device (Microtrac UPA, manufactured by Nikkiso Co., Ltd.) was 155 nm.

(Synthesis Example 13)
<Preparation of Black Pigment Dispersion 4>
Synthesis Example 11 except that the carbon black of Synthesis Example 11 was changed to Color Black FW200 (manufactured by Degussa, BET specific surface area 460 m ² / g, average primary particle size 13 nm, pH 2.5, DBP oil absorption 620 g / 100 g). In the same manner as above, a black pigment dispersion 4 was obtained. The average particle size (D50%) of the obtained black pigment dispersion measured with a particle size distribution measuring device (Microtrac UPA, manufactured by Nikkiso Co., Ltd.) was 175 nm.

(Synthesis Example 14)
<Preparation of urethane resin emulsion A>
Urethane A: Weight average molecular weight-medium With reference to Synthesis Example 1 of Japanese Patent No. 4449043, a supplementary test was prepared as described below.
In a four-necked flask equipped with a stirrer, a Dimroth cooler, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, 119.70 g of 3-isocyanatomethy-3,5,5-trimethylcyclohexylisocyanate was activated as a polyisocyanate component. As hydrogen components, 60.90 g of dimethylolpropionic acid, 60.04 g of bisphenoxyethanol fluorene (manufactured by Osaka Gas Chemical Co., Ltd.), 13.37 g of polytetramethylene glycol having a number average molecular weight of 2,000, and 300.00 g of methyl ethyl ketone as a solvent. Each was added, heated to 80 ° C. under a nitrogen atmosphere, and stirred for 12 hours.
After confirming the disappearance of the isocyanate absorber by infrared absorption spectrum, the temperature was lowered to 40 ° C. and neutralized by adding 45.99 g of triethylamine, and then 700.00 g of water was added and dispersed using a homodisper. I let you. Thereafter, methyl ethyl ketone was distilled off under reduced pressure at 50 ° C. and 6.66 kPa, so that the solvent was substantially free, the fluorene skeleton content was 20% by weight, the acid value was 85 KOH mg / g, the solid content concentration was 30% by weight, and the viscosity. A urethane resin emulsion A having 211 mPa · s and an average particle diameter of 20 nm was obtained. The polystyrene equivalent weight average molecular weight of the obtained urethane resin emulsion measured by gel permeation chromatography (GPC) was 19,835. The average particle diameter was measured by using Microtrac UPA-150 manufactured by Nikkiso Co., Ltd. and diluting the urethane resin emulsion twice with pure water. The average particle diameter here means a 50% average particle diameter (D50).

(Synthesis Example 15)
<Preparation of urethane resin emulsion B>
Urethane B: weight average molecular weight-large Under the nitrogen atmosphere of Synthesis Example 14, the acid value is 80 KOH mg / g, the solid content concentration is the same as Synthesis Example 14 except that the stirring time at 80 ° C. is changed from 12 hours to 18 hours. A urethane resin emulsion B having a weight of 30% by weight, a viscosity of 362 mPa · s, and an average particle size of 24 nm was obtained. The polystyrene-reduced weight average molecular weight of the obtained urethane resin emulsion measured by gel permeation chromatography (GPC) was 26,135. The average particle diameter was measured by diluting the measurement sample with pure water twice using Microtrac UPA-150 manufactured by Nikkiso Co., Ltd. The average particle diameter here means a 50% average particle diameter (D50).

(Synthesis Example 16)
<Preparation of urethane resin emulsion C>
Urethane C: weight average molecular weight-small With reference to Synthesis Example 2 in Japanese Patent No. 4449043, a supplementary test was prepared as described below.
In a four-necked flask equipped with a stirrer, a Dimroth cooler, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, as a polyisocyanate component, 118.01 g of 3-isocyanatomethy-3,5,5-trimethylcyclohexyl isocyanate was activated. As hydrogen components, 60.91 g of dimethylolpropionic acid and 75.09 g of bisphenoxyethanol fluorene (manufactured by Osaka Gas Chemical Company) were added, and 300.00 g of methyl ethyl ketone was added as a solvent, respectively, and the temperature was raised to 80 ° C. in a nitrogen atmosphere. Stir for 12 hours.
After confirming the disappearance of the isocyanate absorber by infrared absorption spectrum, the temperature was lowered to 40 ° C. and neutralized by adding 45.99 g of triethylamine, and then 700.00 g of water was added and dispersed using a homodisper. I let you. Thereafter, methyl ethyl ketone was distilled off under reduced pressure at 50 ° C. and 6.66 kPa, so that the solvent was not substantially contained, the fluorene skeleton content was 25% by weight, the acid value was 85 KOH mg / g, the viscosity was 195 mPa · s, and the average particle diameter. An 18 nm urethane resin emulsion C was obtained. The polystyrene equivalent weight average molecular weight of the obtained urethane resin measured by gel permeation chromatography (GPC) was 12,640. The average particle diameter was measured by diluting the measurement sample with pure water twice using Microtrac UPA-150 manufactured by Nikkiso Co., Ltd. The average particle diameter here means a 50% average particle diameter (D50).

  The materials having the formulations shown in Tables 1 to 4 were mixed and prepared with a 10% by weight aqueous solution of sodium hydroxide so as to have a pH of 9. Thereafter, the mixture was filtered through a membrane filter having an average pore diameter of 0.8 μm to prepare an ink. The numerical value in the raw material column in the table is% by mass.

<Preparation of recording ink>
Each recording ink was manufactured according to the following procedure. First, a water-soluble organic solvent (wetting agent), a penetrating agent, a surfactant, an antifungal agent, and water shown in Tables 1 to 4 below are mixed and stirred uniformly for 1 hour. Then, resin fine particles are added and stirred for 1 hour, and a pigment dispersion and a pH adjuster are added and stirred for 1 hour. This dispersion was subjected to pressure filtration with a polyvinylidene fluoride membrane filter having an average pore size of 5.0 μm to remove coarse particles and dust, thereby producing recording inks of Preparation Examples 1 to 22.
Table 1 shows a black ink preparation example, Table 2 shows a cyan ink preparation example, Table 3 shows a magenta ink preparation example, and Table 4 shows a yellow ink preparation example.

表１中の略号などは下記の意味を表す。
※ Proxel GXL：1,2-benzisothiazolin-3-oneを主成分とした防黴剤(アビシア社製、成分２０％質量、ジプロピレングリコール含有)
※ ゾニールFS-300：ポリオキシエチレンパーフロロアルキルエーテル(Dupon社製、成分４０ｗｔ％)
※ ウレタン樹脂エマルジョン SF650：第一工業製薬社製、カチオン性自己乳化型ポリカーボネート系ポリウレタン樹脂。酸価８０ＫＯＨｍｇ／ｇ、粘度１８７ｍＰａ・ｓ、平均粒径１０ｎｍ。ゲルパーミエーションクロマトグラフィー（ＧＰＣ）で測定したポリスチレン換算重量平均分子量は１５，０３６であった。平均粒径は、日機装（株）製のマイクロトラックＵＰＡ−１５０を用い、測定サンプルを純水で２倍に希釈して測定した。ここでいう平均粒径とは、５０％平均粒径（Ｄ５０）を意味する。

Abbreviations in Table 1 represent the following meanings.
* Proxel GXL: Antifungal agent with 1,2-benzisothiazolin-3-one as the main component (manufactured by Avicia, 20% by mass, containing dipropylene glycol)
* Zonyl FS-300: Polyoxyethylene perfluoroalkyl ether (Dupon, 40wt% component)
* Urethane resin emulsion SF650: Cationic self-emulsifying polycarbonate polyurethane resin manufactured by Daiichi Kogyo Seiyaku. Acid value 80 KOH mg / g, viscosity 187 mPa · s, average particle size 10 nm. The weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) was 15,036. The average particle diameter was measured by diluting the measurement sample with pure water twice using Microtrac UPA-150 manufactured by Nikkiso Co., Ltd. The average particle diameter here means a 50% average particle diameter (D50).

◆ Evaluation of each ink alone The initial average particle diameter and storage stability of each of the black, cyan, magenta and yellow inks prepared in Adjustment Examples 1 to 26 were evaluated. The results are shown in Table 5.

<Measurement of ink viscosity>
To measure the viscosity of the ink, a viscometer RE80L manufactured by Toki Sangyo Co., Ltd. was used, and the viscosity at 25 ° C. was measured at 50 revolutions or 100 revolutions.

<Measurement of average particle diameter of ink>
The average particle size was measured using a sample diluted with pure water so that the pigment concentration (mass concentration) in the measurement sample was 0.01% by mass using Microtrac UPA-150 manufactured by Nikkiso Co., Ltd. did. The average particle diameter here means a 50% average particle diameter (D50).

  For storage stability, after measuring the initial viscosity and average particle diameter, the ink was put in a polyethylene container, sealed, and stored at 70 ° C. for 2 weeks to measure the viscosity and average particle diameter. Evaluation was performed based on the following criteria based on the rate of change from the particle size.

(viscosity)
○: The change rate of the viscosity after storage based on the initial viscosity is less than 5% Δ: The change rate of the viscosity after storage based on the initial viscosity is 5% or more and less than 50% ×: The viscosity after storage based on the initial viscosity More than 50% change rate

(Average particle size)
○: Change rate of the average particle size after storage based on the initial average particle size is less than 5% Δ: Change rate of the average particle size after storage based on the initial average particle size is 5% or more and less than 50% ×: Initial Change rate of average particle size after storage based on average particle size is 50% or more

[Print evaluation]
<Abrasion resistance, ejection stability, OD value (Bk, C, M, Y), color bleed of each ink set>
Printing evaluation of the ink sets of Examples 1 to 6 and Comparative Examples 1 to 8 shown in Table 6 was performed. The print evaluation was performed using an ink jet printer (IPSiO GX3000 manufactured by Ricoh Co., Ltd.) in an environment adjusted to a temperature of 24 ± 0.5 ° C. and 50 ± 5% RH. The driving voltage was varied, and the setting was made so that the same amount of ink adhered to the recording material. Each evaluation item and its evaluation method are shown below.

(Abrasion resistance)
Each ink of Examples 1 to 5 and Comparative Examples 1 to 7 is filled in an inkjet printer, and black, cyan, magenta, and yellow single-color solid printing portions are printed on TyPe6200 paper (manufactured by NBS Ricoh Co., Ltd.) at a resolution of 600 dpi. A chart was printed. After the printing was dried, the printed portion was rubbed 10 times with a cotton cloth, and the transfer of the pigment onto the cotton cloth was visually observed and evaluated according to the following evaluation criteria.
* Type6200: Ricoh (quality paper) basis weight 71.7 g / m2, sizing 20.0 seconds, air permeability 22.5 seconds

〔Evaluation criteria〕
(Double-circle): The transfer of the pigment to cotton cloth is hardly seen about all colors of black, cyan, magenta, and yellow.
○: Transfer of pigment to cotton cloth is not observed for black, but transfer of pigment to cotton cloth is observed for one or more of cyan, magenta, and yellow.
Δ: Pigment transfer to cotton cloth is not observed for all colors of cyan, magenta, and yellow, but transfer of pigment to cotton cloth is observed for black.
X: The transfer of the pigment to the cotton cloth is observed for black, and the transfer of the pigment to the cotton cloth is also observed for any one or more of cyan, magenta, and yellow.

(Discharge stability)
A chart including solid and line patterns having the same area and shape of black, cyan, magenta, and yellow is filled in each of the inks of Examples 1 to 5 and Comparative Examples 1 to 7 in an ink jet printer. Printed continuously. During printing, when there were missing ink dots or flying curves on the chart, the printer nozzle was cleaned as a return to normal printing, and the total number of times was evaluated. From the total number of times obtained, the ejection stability of each ink set was evaluated according to the following evaluation criteria.
* My paper: Ricoh (quality paper) Basis weight 69.6 g / m2, Size 23.2 seconds, Air permeability 21.0 seconds

〔Evaluation criteria〕
A: One cleaning.
○: Cleaning is performed 2 times or more and less than 5 times.
X: Cleaning 5 times or more.

(OD value)
<Image density>
A chart with a 64-point character “■” created by Microsoft Word (2003) was printed on my paper, and the “■” portion of the printed surface was measured with X-Rite 938, and judged according to the following evaluation criteria. The printing mode was “plain paper – standard fast” mode printing with the driver attached to the printer.

(Evaluation criteria)
A: OD value Black 1.30 or more Yellow 0.85 or more Magenta 1.00 or more Cyan 1.10 or more.
○: OD value Black 1.20 or more and less than 1.30 Yellow 0.75 or more and less than 0.85 Magenta 0.90 or more and less than 1.00 Cyan 1.00 or more and less than 1.10.
Δ: OD value Black 1.10 or more and less than 1.20 Yellow 0.70 or more and less than 0.75 Magenta 0.80 or more and less than 0.9 Cyan 0.90 or more and less than 1.00.
X: Value Black Less than 1.10 Yellow Less than 0.70 Magenta Less than 0.80 Cyan Less than 0.90.

(Color bleed)
A black line image of 0.5 mm was formed in a cyan solid image on the recording medium, and the occurrence of blurring in the color boundary that occurs when recording liquids of different colors adjoin each other was visually observed. Similarly, when the black 0.5 mm line image is formed in the magenta solid image and the black 0.5 mm line image is formed in the yellow solid image, the occurrence of blurring in the color boundary is observed. did.

(Evaluation criteria)
A: No problem at all.
○: Slightly generated but no problem.
X: There is an occurrence problem.

◆ Printing evaluation results Table 7 shows the results.

From the above results, it can be determined as follows.
Comparative Example 1: The molecular weight of the urethane resin added to the color is larger, the color bleed reduction effect cannot be obtained, and the color ejection stability becomes insufficient.
Comparative Example 2: Since the pigment particle size of black is small, the OD value of black is low.
Comparative Example 3: Since the pigment particle size of black is large, the scratch resistance by the urethane resin cannot be sufficiently obtained. Further, the dispersion stability is insufficient, and it becomes easy to fix.
Comparative Example 4: For black, the same reason as in Comparative Example 2. For color, the pigment particle size is too small, and sufficient image density is not obtained.
Comparative Example 5: Since the molecular weights of black and colored urethane resins are the same, there is no bleed reduction effect.
Comparative Example 6: The molecular weight of the urethane resin is small relative to the black pigment particle size, and the scratch resistance due to the urethane resin cannot be sufficiently obtained. Also, the dispersion stability is insufficient and the storage stability is poor. In addition, the molecular weight of urethane resin added to black is smaller than that of color, and there is no bleed reduction effect.
Comparative Example 7: The same reason as in Comparative Example 6. The reason why the OD value of the color is slightly better than that of Comparative Example 6 is that the molecular weight of the urethane resin relative to the color pigment particle size is not too large, and the film thickness of the urethane on the paper surface is reduced. The molecular weight of the urethane resin added in black and in color is equal, and there is no bleed reduction effect.
Comparative Example 8: Scratch resistance and pigment dispersion stability cannot be obtained unless a urethane resin is added. If the dispersion is unstable, it becomes easy to fix. Breeding is exacerbated because there is no urethane interaction.

DESCRIPTION OF SYMBOLS 101 Main body 102 Paper feed tray 103 Paper discharge tray 104 Ink cartridge loading part 105 Operation part 111 Upper cover 112 Front cover front 115 Front cover 131 Guide rod 132 Stay 133 Carriage 134 Recording head 135 Sub tank 141 Paper placement part 142 Paper 143 Feed roller 144 Separator pad 145 Guide 151 Transport belt 152 Counter roller 153 Transport guide 154 Pressing member 155 Pressure roller 156 Charging roller 157 Transport roller 158 Tension roller 161 Guide member 171 Separating claw 172 Paper discharge roller 173 Paper discharge roller 181 Double-sided feeding Paper unit 182 Manual paper feed unit 200 Cartridge 241 Storage bag 242 Inlet 243 Outlet 244 Cartridge case

JP 2009-144174 A

Claims (7)

It is a black, cyan, magenta, yellow ink set consisting of at least water, pigment, water-soluble organic solvent, and urethane resin. The urethane resin contained in black ink is the urethane resin contained in each of A, cyan, magenta, and yellow ink. An ink set that satisfies the following (1) and (2) when B is satisfied.
150 nm> black ink average particle diameter> cyan, magenta,
Yellow ink average particle size> 70nm (1)
Weight average molecular weight of A> B weight average molecular weight (2) 2. The ink according to claim 1, wherein the urethane resin A has a weight average molecular weight of 10,000 to 25,000 and the urethane resin B has a weight average molecular weight of 5,000 to 20,000. set. The ink set according to claim 1, wherein the urethane resin is an emulsion resin of an anionic self-emulsifying ether polyurethane. The ink set according to any one of claims 1 to 3, wherein the pigment dispersion used in the ink set is a surfactant-dispersed pigment dispersion and / or a resin-coated pigment dispersion. An ink jet recording method comprising at least an ink flying step of forming an image by applying a stimulus to the ink according to claim 1 and causing the ink to fly. An ink set cartridge, wherein the ink according to claim 1 is contained in a container. An ink recorded matter comprising an image formed using the ink set according to any one of claims 1 to 4 on a recording medium.

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