JP4457892B2 - Ink jet recording ink and ink jet recording apparatus - Google Patents

Description

Background of the Invention

FIELD OF THE INVENTION The present invention relates to an ink jet recording ink that can provide high print quality and high reliability for various recording media, particularly plain paper, recycled paper, and special paper having an ink receiving layer on the surface thereof.

BACKGROUND ART Inkjet recording is a method of recording characters and figures on the surface of a recording medium by ejecting ink as small droplets from fine nozzles. As an ink jet recording method, an electric signal is converted into a mechanical signal using an electrostrictive element, and ink stored in the nozzle head is intermittently ejected to record characters and symbols on the surface of the recording medium, nozzle head A method of recording characters and symbols on the surface of a recording medium by rapidly heating a part of the ink stored in the part to generate a bubble by rapidly heating a part close to the discharge part and then intermittently discharging it by volume expansion due to the bubble. Etc. have been put to practical use.

  The ink used for such ink jet recording has good printing dryness, no blur of printing, can be printed uniformly on the surface of various recording media, and colors do not mix in the case of multiple colors. The characteristics are required.

  Here, a particular problem is that when paper is used as the recording medium, blurring occurs mainly due to a mixture of fibers having different permeability, and black ink and color ink are Color mixing at the boundary to lower the image quality, and ink on the recording medium to be peeled off when touched by a hand or the like.

  In order to overcome these disadvantages, various ink compositions have been proposed.

  For example, JP-B-2-2907 uses glycol ether as a wetting agent, JP-B-1-15542 uses a water-soluble organic solvent, and JP-B-2-3837 uses a dye dissolution accelerator. Has proposed.

  In addition, in US Pat. No. 5,156,675, diethylene glycol monobutyl ether is added to improve permeability, and in US Pat. No. 5,183,502, surfylene 465, which is an acetylene glycol surfactant, is added. Furthermore, US Pat. No. 5,196,056 proposes the addition of both diethylene glycol monobutyl ether and Surfynol 465. Here, diethylene glycol mono-n-butyl ether is also called butyl carbitol, and is described in, for example, US Pat. No. 3,291,580. Alternatively, US Pat. No. 2,083,372 discusses the use of ethers of diethylene glycol. Furthermore, Japanese Patent Application Laid-Open No. 56-147861 proposes the combined use of a pigment and triethylene glycol monomethyl ether.

  However, an ink composition that can realize an image with less blur is still desired.

  In addition, in order to reduce bleeding, it has been studied to heat the recording paper. However, if the recording paper is heated during recording, it takes time to start up the heating unit in the apparatus up to a predetermined temperature, the power consumption of the apparatus main body increases, or the recording paper and other recording media There is a problem of giving damage.

  In addition, in an ink composition using a pigment, an attempt has been made to suppress the penetrability, suppress the ink permeation on the surface of the recording medium, and ensure the print quality. However, if the ink composition does not penetrate into the recording medium to some extent, the pigment may remain on the surface of the recording medium and deteriorate the abrasion resistance. Further, recently, a recording medium having a gloss layer on its surface, giving a gloss to a recorded image, and giving added value to the image has been used. There is a demand for a pigment-based ink that can realize an image having good abrasion resistance on such a recording medium.

Summary of the Invention

  The present inventors have recently realized that an ink composition containing a combination of a specific pigment and an acetylene glycol-based surfactant can effectively suppress bleeding and realize a high-quality image with excellent abrasion resistance. I got the knowledge. The present invention is based on such knowledge.

  Accordingly, it is an object of the present invention to provide an ink composition capable of realizing a good image with less blur on various recording media, particularly plain paper, recycled paper, and even a recording medium having a gloss layer on the surface thereof. It is said.

  The ink composition according to the present invention comprises at least a pigment, a water-soluble organic solvent, a surfactant, and water, and the pigment can be dispersed and / or dissolved in water without a dispersant. And the surfactant is an acetylene glycol surfactant.

DETAILED DESCRIPTION OF THE INVENTION

Ink composition Used in a recording system using the ink composition according to the present invention. Examples of the recording method using the ink composition include an ink jet recording method, a recording method using a writing instrument such as a pen, and other various printing methods. In particular, the ink composition according to the present invention is preferably used in an ink jet recording method.

  The ink composition according to the present invention includes a pigment, a water-soluble organic solvent, a surfactant, and water, and the pigment is a pigment that can be dispersed and / or dissolved in water without a dispersant. In addition, the surfactant is an acetylene glycol surfactant. According to the ink composition of the present invention, it is possible to effectively suppress bleeding and realize a high quality image excellent in abrasion resistance. Furthermore, the ink composition according to the present invention has the advantages of excellent print drying and high color density. For example, the ink composition according to the present invention can be applied to a recording method in which printing is performed by dividing the ink amount into two or more times, and according to such a method, higher density printing is obtained. be able to.

  The pigment preferably used in the present invention is a surface treatment in which at least one kind of functional group of carbonyl group, carboxyl group, hydroxyl group, or sulfone group or a salt thereof is bonded to the surface without a dispersant. It can be dispersed and / or dissolved in water. Specifically, it can be obtained by grafting a functional group or a molecule containing a functional group onto the surface of carbon black by physical treatment such as vacuum plasma or chemical treatment. In the present invention, the functional group grafted on one carbon black particle may be single or plural. The type and degree of the functional group to be grafted may be appropriately determined in consideration of the dispersion stability in the ink, the color density, the drying property on the front surface of the inkjet head, and the like.

  In the present invention, a state where the pigment is stably present in water without a dispersant is expressed as “dispersion and / or dissolution”. In many cases, it is difficult to clearly distinguish whether a substance is dissolved or dispersed. In the present invention, as long as the pigment can be stably present in water without a dispersant, such a pigment can be used regardless of whether the state is dispersed or dissolved. Therefore, in this specification, a pigment that can exist stably in water without a dispersant is sometimes referred to as a water-soluble pigment, but it does not mean that even a pigment in a dispersed state is excluded.

  According to a preferred embodiment of the present invention, it is preferably used as a pigment dispersion having an average particle size of 50 to 200 nm and a dispersity of 10 or less.

  The pigment preferably used in the present invention can be obtained, for example, by the method described in JP-A-8-3498. Commercially available products can also be used as the pigment, and a preferred example is Microjet CW1 or 2 manufactured by Orient Chemical Industry Co., Ltd.

  The amount of the pigment added to the ink composition is preferably 2 to 10% by weight, more preferably about 4 to 8% by weight.

  Preferable examples of the acetylene glycol surfactant used in the present invention include compounds represented by the following formula (I).

（式中、０≦ｍ＋ｎ≦５０、Ｒ¹ 、Ｒ² 、Ｒ³ 、およびＲ⁴ は独立してアルキル基である）
上記式（Ｉ）で表される化合物の中で特に好ましくは２，４，７，９−テトラメチル−５−デシン−４，７−ジオール、３，６−ジメチル−４−オクチン−３，６−ジオール、３，５−ジメチル−１−ヘキシン−３オールなどが挙げられる。上記式（Ｉ）で表されるアセチレングリコール系界面活性剤として市販品を利用することも可能であり、その具体例としてはサーフィノール１０４、８２、４６５、４８５、またはＴＧ（いずれもAir Products and Chemicals.Inc.より入手可能）が挙げられる。

(In the formula, 0 ≦ m + n ≦ 50, R ¹ , R ² , R ³ , and R ⁴ are each independently an alkyl group)
Among the compounds represented by the above formula (I), 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6 is particularly preferable. -Diol, 3,5-dimethyl-1-hexyne-3ol and the like. Commercially available products can be used as the acetylene glycol surfactant represented by the above formula (I), and specific examples thereof include Surfynol 104, 82, 465, 485, or TG (both Air Products and Available from Chemicals. Inc.).

  According to a preferred embodiment of the present invention, the amount of acetylene glycol surfactant added is preferably in the range of 0.3 to 2% by weight, more preferably 0.5% to 1.5%, based on the total amount of ink. . When the addition amount of the acetylene glycol surfactant is within this range, an image with less blur can be realized.

  Some acetylene glycol surfactants such as Surfynol 104 and TG have low HLB and thus have low solubility in water. This solubility can be improved by adding components such as glycol ethers, glycols, and surfactants to the ink composition.

  The water-soluble organic solvent used in the present invention forms a main solvent together with water, has compatibility with water, and does not have undesirable interactions with other components in the ink composition. As long as there is no particular limitation.

  According to a preferred embodiment of the present invention, as a water-soluble organic solvent, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, diethylene glycol, diethylene glycol, triethylene glycol, diethylene glycol, diethylene glycol in order to suppress drying of the ink composition in front of the nozzle of the inkjet recording head. Propylene glycol, tripropylene glycol, polyethylene glycol having a molecular weight of 2000 or less, 1,3-propylene glycol, isopropylene glycol, isobutylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1 , 6-hexanediol, glycerin, thiodiglycol, mesoerythritol, pentaerythritol and the like can be added. In particular, glycerin, 1,5-pentanediol, diethylene glycol, or thiodiglycol, and a mixture thereof can appropriately control the viscosity of the ink composition, can effectively prevent nozzle clogging, This is preferable because the cloud point of the composition can be increased. Furthermore, the solubility of the above-described acetylene glycol surfactant (especially Surfinol 104, Surfinol TG) in the ink composition is improved, and phase separation does not occur even when the ink composition is placed at a high temperature. , And can also enjoy the benefits.

  The amount of these water-soluble organic solvents added may be appropriately determined, but is preferably less than 1 to 30% by weight, more preferably about 5 to 15% by weight with respect to the ink composition.

  According to another preferred embodiment of the present invention, water-soluble organic solvents that can be added to the ink composition according to the present invention include alkyl alcohols having 1 to 4 carbon atoms such as ethanol, methanol, butanol, propanol, and isopropanol. , Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol Mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol Mono-t-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether, diethylene glycol mono-t-butyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene Glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether, dipropylene Glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropy Glycol ethers such as glycol monomethyl -iso- propyl ether, formamide, acetamide, dimethyl sulfoxide, sorbitol, sorbitan, acetin, diacetin, triacetin, and sulfolane. The addition of these organic solvents improves the solubility of other components in the ink composition in the ink composition, further improves the permeability to the recording medium such as paper, and further effectively prevents clogging of the nozzles. Since it can prevent, it is preferable. The amount of these organic solvents to be added may be appropriately determined, but is preferably about 0.1 to 60% by weight, more preferably about 5 to 15% by weight with respect to the ink composition.

  According to a preferred embodiment of the present invention, the ink composition according to the present invention preferably comprises 2-pyrrolidone. Since the acetylene glycol surfactant contained in the ink composition according to the present invention is nonionic, it may give a low cloud point to the ink composition. The addition of 2-pyrrolidone has the effect of increasing the cloud point without an extreme increase in viscosity. The addition of 2-pyrrolidone may be appropriately determined within a range in which the above effect can be obtained, but is preferably 1% by weight or more and less than 20% by weight with respect to the ink composition.

  According to a preferred embodiment of the present invention, the ink composition according to the present invention preferably comprises triethanolamine. By adding this triethanolamine, the ink composition can be made to have a proper alkalinity, and a moisturizing effect can be provided to effectively prevent nozzle clogging. The amount of triethanolamino added may be appropriately determined, but is preferably about 0.5 to 3% by weight.

  The pH of the ink composition according to the present invention is preferably controlled in the range of 7 to 11, more preferably 8 to 10. By setting the pH within this range, it is preferable because the pigment and further the resin emulsion described later can be stably present in the ink composition. In addition to the above triethanolamino, the pH can be adjusted with a suitable alkali agent (for example, an organic alkali such as ammonia and an alkali metal salt). A preferred alkali agent is potassium hydroxide. In particular, it is preferable to adjust pH by combining triethanolamine and potassium hydroxide. When triethanolamino and potassium hydroxide are combined, the amount of potassium hydroxide added is preferably about 0.01 to 0.2% by weight.

  According to a preferred embodiment of the present invention, the ink composition according to the present invention preferably comprises a water-soluble emulsion. By adding this water-soluble emulsion, it is possible to improve the fixing property and abrasion resistance of the print. This water-soluble emulsion is preferably such that the continuous phase is water and the dispersed phase is an acrylic acid resin, methacrylic acid resin, styrene resin, urethane resin, acrylamide resin, epoxy resin, or a mixed form thereof. In particular, the dispersed phase is preferably made of a resin mainly composed of acrylic acid and / or methacrylic acid. These resins are not limited depending on the mode of copolymerization, and can be, for example, block copolymers, random copolymers, and the like. Furthermore, the water-soluble emulsion used in the ink composition according to the present invention preferably has a film-forming ability, and preferably has a minimum film-forming temperature of room temperature or lower, more preferably 0 ° C. or higher and 20 ° C. or lower. Temperature.

  According to a preferred embodiment of the present invention, the resin component of the water-soluble emulsion is preferably a resin particle having a core-shell structure comprising a core portion and a shell portion surrounding the core portion. For example, it is possible to adopt a configuration in which a resin component capable of improving the finger touch and fixability of the ink is introduced into the core portion, and a resin component that causes the resin particles to stably exist in the ink composition is introduced into the shell portion. . According to a preferred embodiment of the present invention, the core part is preferably made of a resin having a crosslinked structure.

  Examples of the material forming the core include styrene, tetrahydrofurfuryl acrylate, butyl methacrylate, (α, 2, 3 or 4) -alkyl styrene, (α, 2, 3 or 4) -alkoxy styrene, 3,4-dimethyl. Styrene, α-phenylstyrene, divinylbenzene, vinylnaphthalene, dimethylamino (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropylacrylamide, N, N-dimethylaminoethyl acrylate, acrylomorpholine, N, N -Dimethylacrylamide, N-isopropylacrylamide, N, N-diethylacrylamide, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, ethylhexyl (meth) acrylate, Other alkyl (meth) acrylates, methoxydiethylene glycol (meth) acrylate, ethyl ester of diethylene glycol or polyethylene glycol, (meth) acrylate of propyl ester or butyl ester, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl ( Examples include meth) acrylate, isobornyl (meth) acrylate, hydroxyalkyl (meth) acrylate, fluorine-containing, chlorine-containing, silicon-containing (meth) acrylate, (meth) acrylamide, and maleic amide.

  In addition to the above (meth) acrylic acid, when a crosslinked structure is introduced, (mono, di, tri, tetra, poly) ethylene glycol di (meth) acrylate, 1,4-butanediol, 1,5-pentanediol , 1,6-hexanediol, 1,8-octanediol and 1,10-decanediol, etc. (meth) acrylate, trimethylolpropane tri (meth) acrylate, glycerin (di, tri) (meth) acrylate, bisphenol A Alternatively, di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, or the like of ethylene oxide adduct of F can be used.

  In the formation of the shell portion, the above-mentioned substance forming the core portion can be used.

  As the emulsifier used for forming such polymer fine particles, conventionally used sodium lauryl sulfate, potassium lauryl sulfate, an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant can be used.

  As polymerization initiators, potassium persulfate, ammonium persulfate, hydrogen persulfate, azobisisobutyronitrile, benzoyl peroxide, dibutyl peroxide, peracetic acid, cumene hydroperoxide, t-butylhydroxyperoxide, paramentanehydroxy Peroxide can be used.

  Examples of chain transfer agents for polymerization include t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, xanthogens dimethylxanthogen disulfide, diisobutylxanthogen disulfide, dipentene, indene, 1,4-cyclohexadiene, dihydrofuran. , Xanthene and the like can be used.

  According to a preferred embodiment of the present invention, the core portion is made of an epoxy resin or a urethane resin, preferably a resin having a crosslinked structure. Furthermore, according to another preferable aspect of the present invention, the core portion is made of an acrylic acid resin and / or a methacrylic acid resin, preferably a resin having a crosslinked structure. The shell part preferably has a structure having a surface having a carboxyl group of an acryloyl group and / or a methacryloyl group. Furthermore, the functional group on the surface of the shell part is preferably treated with an organic alkali such as an ammonium salt, an amine and / or an amide salt in order to make the resin particles stably present in the ink composition.

  According to a preferred embodiment of the present invention, the molecular weight of the water-soluble emulsion is preferably 1000 or more, more preferably about 10,000 to 100,000.

  Commercially available products can also be used as the water-soluble emulsion used in the present invention, and examples thereof include Z116 manufactured by Mitsui Toatsu.

  Although the addition amount of this water-soluble emulsion may be determined appropriately, for example, it is preferably about 0.5 to 10% by weight, more preferably about 3 to 5% by weight.

  The ink composition according to the present invention may contain other components in addition to the above components. For example, the nozzle clogging preventive agent, preservative, antioxidant, conductivity adjusting agent, pH adjusting agent, viscosity adjusting agent, A surface tension adjusting agent, an oxygen absorbent and the like can be added.

  In the ink composition according to the present invention, saccharides can be added in order to prevent the ink from drying on the front surface of the nozzle. Such saccharides include monosaccharides and polysaccharides, such as glucose, mannose, fructose, ribose, xylose, arabinose, lactose, galactose, aldonic acid, glucitol, maltose, cellobiose, sucrose, trehalose, maltotriose, etc. Examples thereof include alginic acid and salts thereof, cyclodextrins, and celluloses. The addition amount is preferably about 0.05 to 30% by weight. In particular, more preferable addition amount of glucose, mannose, fructose, ribose, xylose, arabinose, lactose, galactose, aldonic acid, glucitol, maltose, cellobiose, sucrose, trehalose, maltotriose, etc. is 3 to 20% by weight. . Depending on the addition amount of alginic acid and its salt, cyclodextrins, and celluloses, the viscosity tends to increase, so it is preferable to reduce the addition amount.

  Further, in order to further control the permeability, it is possible to add another surfactant to the ink according to the present invention. The surfactant to be added is preferably a surfactant having good compatibility with other components in the ink composition, and among the surfactants, those having high permeability and stability are preferred. Examples thereof include amphoteric surfactants and nonionic surfactants. Amphoteric surfactants include lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, polyoctylpolyaminoethylglycine and other imidazoline derivatives. is there. Nonionic surfactants include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene Ethers such as ethylene alkyl ether and polyoxyalkylene alkyl ether, polyoxyethylene oleic acid, polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquis Esters such as oleate, polyoxyethylene monooleate, polyoxyethylene stearate, etc. Alkyl esters, and the like fluorine-containing surfactants such as perfluoroalkyl carboxylates.

  Examples of the antiseptic and fungicide include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-dibenzisothiazoline-3- ON (Proxel CRL, Proxel BDN, Proxel GXL, Proxel XL-2, Proxel TN from ICI) and the like.

  In addition, as pH adjusters, dissolution aids, and antioxidants, amines such as diethanolamine, triethanolamine, propanolamine, morpholine and their modified products, inorganic substances such as potassium hydroxide, sodium hydroxide, lithium hydroxide, etc. Salts, ammonium hydroxide, quaternary ammonium hydroxide (such as tetramethylammonium), carbonates such as potassium carbonate, sodium carbonate, lithium carbonate, and other phosphates, or N-methyl-2-pyrrolidone, urea, thiourea, Examples include ureas such as tetramethylurea, allophanates such as allophanate and methyl allophanate, biurets such as biuret, dimethylbiuret and tetramethylbiuret, and L-ascorbic acid and salts thereof. Commercially available antioxidants, ultraviolet absorbers and the like can also be used. Examples include Ciba Geigy's Tinuvin 328, 900, 1130, 384, 292, 123, 144, 622, 770, 292, Irgacor 252, 153, Irganox 1010, 1076, 1035, MD1024 and the like. It is also possible to use an oxide of lanthanide.

  Furthermore, examples of the viscosity modifier include rosins, alginic acids, polyvinyl alcohol, hydroxypropylcellulose, carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, polyacrylate, polyvinylpyrrolidone, gum arabic starch and the like.

Recording Method and Apparatus The ink composition according to the present invention may preferably form an image by an inkjet recording method.

  FIG. 1 is a view showing an example of an ink jet recording apparatus in which the ink composition according to the present invention is preferably used. The apparatus in the figure has a carriage 2 that reciprocates in the direction of arrow B on a guide shaft 2a along a platen 1 that is a recording paper transport means that rotates in the direction of arrow A to transport the recording paper. The carriage 2 is mounted with a recording head 3 a that discharges a black ink composition in the vicinity of the platen 1 and a recording head 3 b that discharges a color ink composition. A black ink composition tank 7a is provided above the recording head 3a, and a color ink composition tank is provided above the recording head 3b, and the ink composition is supplied from each tank to the recording head 3a or 3b.

  A signal is supplied from the signal cable 18 to the recording heads 3a and 3b, and droplets of an ink composition are ejected from the nozzles (not shown) from the recording heads 3a and 3b in accordance with this signal. The ejected ink composition droplets adhere to the recording medium 20 (for example, paper) wound around the platen 1 to form an image.

  Further, when the recording head is clogged, the nozzle surface of the recording head is sealed with the cap member 13, and the ink composition is sucked with the pump 15 connected to the cap member 13 through the conduit 14. To eliminate clogging. The sucked ink composition is guided to the waste liquid tank 17 through the conduit 16.

  Although only one cap member is provided in the drawing, a plurality of cap members may be provided so as to correspond to each of the recording heads 3a and 3b.

  Next, the tank for black ink composition according to the present invention will be described in detail. FIG. 2 is a cross-sectional view of the ink jet recording apparatus of FIG. 1, and FIG. 3 is an exploded perspective view of the tank 7a.

  Above the recording head 3a, there is provided a tank 7a having a tank reservoir 6 in which a foam 6a made of a porous member such as polyurethane foam is accommodated. In the tank 7a, a communication hole 9 communicating with the outside is provided in the lid 8, and a trapezoidal protrusion 10 in close contact with the foam 6a is formed on the bottom surface. There is a communicating portion that communicates with the recording head 3a from the center of the projection 10 downward. The communicating portion is formed by an ink chamber 11 for taking out and holding the ink composition in the foam 6a, and a blind plug 12 made of an elastic member such as rubber at the end of the ink chamber 11.

  A hollow needle 5 which is a communicating member communicating with the recording head 3a provided on the carriage via the filter chamber 4 is inserted into the blind plug 12, so that the ink composition impregnated in the ink tank 7a is supplied to the recording head 3a. Is done.

  Further, at least one of the communication holes 9 is sealed under reduced pressure until immediately before use by a non-breathable sealing member 21 that can be opened. And it opens just before use and the tank 7a and the exterior communicate with each other through the vent hole 9a. As shown in FIG. 3, the sealing member 21 preferably has a sufficiently long portion and is configured to be easily opened by picking up an end thereof. During printing, the air holes 9a serve to replenish air into the tank 7a as much as the tank is consumed.

  According to the ink composition of the present invention, a good image can be formed even on a recording medium such as plain paper and recycled paper, which has conventionally been relatively easy to cause bleeding. Furthermore, the ink composition according to the present invention can realize an image having excellent abrasion resistance even on a recording medium having a so-called glossy layer on its surface.

  According to a preferred embodiment of the present invention, the front surface of the nozzle opening of the recording head is preferably made of eutectoid plating of tetrafluoroethylene and metal. By combining the recording head having such a nozzle surface and the ink composition according to the present invention, it is possible to reduce the occurrence of deposits on the nozzle surface. Even if deposits are generated, these deposits can be easily removed by a cleaning operation in which rubber or felt is brought into contact.

  The ink composition according to the present invention forms good quality prints on various recording media, especially on plain paper, recycled paper, and special paper having an ink-receiving layer on its surface, especially recording media having a glossy layer. I can do it. In the present invention, the recording medium having a glossy layer means, for example, a recording medium in which a white pigment is fixed on a substrate using a binder. Specific examples include colloidal silica, amorphous silica, colloidal alumina, boehmite, pseudoboehmite, alumina, aluminum hydroxide, light calcium carbonate, calcium bicarbonate, calcium sulfate, kaolin, talc, barium sulfate, rutile, zinc oxide, zinc sulfide. , Zinc carbonate, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, zeolite, halloysite, magnesium carbonate, magnesium hydroxide, etc. Type recording medium. Further, starch derivatives, carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), casein, gelatin, polyvinyl alcohol, polyvinyl pyrrolidone, melamine resin, urea resin, urethane resin, unsaturated polyester resin, maleic anhydride resin, styrene butadiene resin, Examples thereof include a recording medium formed by applying a resin layer made of a polymer such as an acrylic acid derivative or a methacrylic acid derivative, a copolymer, or the like on a substrate, and is swollen by ink. Examples of methods for producing gloss include calendering, casting, pressure drying with a heated mirror surface in a wet oil state, and applying a glossy resin. In a recording medium having these gloss layers, the fixability of the pigment may be deteriorated depending on the size of the voids on the surface. According to the ink composition of the present invention, an image excellent in abrasion resistance can be realized regardless of the state of the surface of the recording medium.

  The ink composition according to the present invention may be used in combination with other ink compositions to form a color image. According to a preferred embodiment of the present invention, a combination in which the ink composition according to the present invention is a black ink and the other ink composition is a color ink (for example, yellow ink, magenta ink, cyan ink) is preferable. In particular, by adding the same water-soluble emulsion as described above to other ink compositions, an image excellent in abrasion resistance can be realized. Further, it is possible to form a black image by superimposing yellow ink, magenta ink, and cyan ink, and to print in combination with the black ink according to the present invention. As the printing method at that time, a method of superimposing the two (especially preferable for a recording medium having a glossy layer), a method of alternately forming both images (a method of alternately arranging both image areas of a certain width, Including any method of forming a line with an ink composition and arranging the line).

  In an ink having a relatively large amount of solid matter such as a pigment such as the ink composition according to the present invention, a nozzle that does not discharge for a long time tends to be thickened due to drying of the ink on the front surface of the nozzle, and the phenomenon that printing is disturbed easily occurs. Therefore, by finely moving the ink so as not to be ejected from the front surface of the nozzle, the ink is stirred and the ink can be ejected stably. The fine movement method can be generated by controlling the pressurizing means for ejecting ink so as not to eject ink. When performing such control, it is preferable to use an electrostrictive element as the pressurizing means because of the ease of control. Also, by using this mechanism, the pigment concentration in the ink can be increased, so that the color density of the pigment ink is high and the ink can be ejected stably.

  Further, when the fine movement is performed on the nozzle surface in the ink jet recording apparatus, it is effective for an ink composition having a pigment content of about 5% to 15% by weight, more preferably about 7% to 10% by weight. Ink composition.

  In addition, the ink composition according to the present invention may be used by being filled in an ink tank filled with polyurethane foam and having a structure in which the ink and urethane foam are in contact with each other. In this case, glycol ethers and acetylene glycol surfactants that are preferably used in the present invention are adsorbed to the urethane foam. Therefore, it is preferable to add excessively in consideration of the adsorbed amount. In addition, the urethane foam can secure a negative pressure by using the ink composition according to the present invention, and further, the urethane foam is decomposed by each component of the ink used in the present invention and causes foreign matters to cause clogging. Less is. The urethane foam curing catalyst does not use metal salts or cationic ones, but includes polyfunctional isocyanates such as tolylene diisocyanate and metaxylylene diisocyanate and glycols such as polypropylene glycol and polyethylene glycol having an average molecular weight of about 300 to 3000. A urethane foam comprising a substance having a plurality of hydroxy groups, such as glycerin, pentaerythritol, dipentaerythritol, neopentyl glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol. It is preferable to use it from the viewpoint of securing a negative pressure due to the stability of the foam shape and chemical stability.

  Hereinafter, the present invention will be described in detail with reference to the following examples, but the present invention is not limited thereto.

  An ink composition having the following composition was prepared.

  Hereinafter, the modified product means a water-soluble pigment obtained by applying the method described in JP-A-8-34981 to a commercially available pigment described above.

  Moreover, the average particle diameter of the water-soluble pigment is shown in parentheses in nm units.

  Furthermore, emulsions A to D used in the following examples were prepared as follows.

Emulsion A : 100 parts of ion-exchanged water was put into a reaction vessel equipped with a dropping device, a thermometer, a water-cooled reflux condenser, and a stirrer, and 0.2% of potassium persulfate as a polymerization initiator was added at 70 ° C. with stirring. Parts were added. Obtained by mixing 7 parts of ion-exchanged water with 0.05 part of sodium lauryl sulfate, 4 parts of glycidoxy acrylate, 5 parts of styrene, 6 parts of tetrahydrofurfuryl acrylate, 5 parts of butyl acrylate and 0.02 of t-dodecyl mercaptan The monomer solution was dropped into a container at 70 ° C. and reacted to prepare a primary substance. To this primary material was added 2 parts ammonium persulfate 10% solution and stirred. Further, 30 parts of ion exchange water, 0.2 part of potassium lauryl sulfate, 30 parts of styrene, 15 parts of butyl methacrylate, 16 parts of butyl acrylate, 2 parts of acrylic acid, 1 part of 1,6-hexanediol dimethacrylate, 0 t-dodecyl mercaptan A reaction solution consisting of .5 parts was added to a reaction vessel while stirring at 70 ° C. to cause a polymerization reaction. Thereafter, the reaction solution was neutralized with ammonia to pH 8 to 8.5, and filtered through a 0.3 μm filter to obtain an aqueous solution of polymer fine particles.

Emulsion B : 100 parts of ion-exchanged water was put into a reaction vessel equipped with a dropping device, a thermometer, a water-cooled reflux condenser, and a stirrer, and 0.2 per cent of polymerization initiator potassium persulfate was added at 70 ° C. in a nitrogen atmosphere while stirring. Parts were added. A monomer solution obtained by mixing 7 parts of ion-exchanged water with 0.05 part of sodium lauryl sulfate, 10 parts of styrene, 5 parts of glycidoxy methacrylate, 5 parts of butyl methacrylate and 0.02 of t-dodecyl mercaptan at 70 ° C. A primary substance was prepared by dropping it into a container to react. To this primary material was added 2 parts ammonium persulfate 10% solution and stirred. Furthermore, a reaction solution composed of 30 parts of ion exchange water, 0.2 part of potassium lauryl sulfate, 35 parts of styrene, 25 parts of butyl acrylate, 10 parts of acrylic acid, 1 part of acrylamide and 0.5 part of t-dodecyl mercaptan is stirred at 70 ° C. While being added to the reaction vessel, the polymerization reaction was carried out. Thereafter, the reaction solution was neutralized with ammonia to a pH of 8 to 8.5, and filtered through a 0.3 μm filter to obtain an aqueous solution of polymer fine particles.

Emulsion C : 100 parts of ion-exchanged water was put into a reaction vessel equipped with a dropping device, a thermometer, a water-cooled reflux condenser, and a stirrer, and 0.2% of potassium persulfate as a polymerization initiator was added at 70 ° C. with stirring. Parts were added. Monomer solution obtained by mixing 0.05 part of sodium lauryl sulfate, 5 parts of styrene, 2 parts of glycidoxy methacrylate, 6 parts of benzyl methacrylate, 10 parts of butyl methacrylate and 0.02 of t-dodecyl mercaptan in 7 parts of ion-exchanged water Was dropped into a container at 70 ° C. and reacted to prepare a primary substance. To this primary material was added 2 parts ammonium persulfate 10% solution and stirred. Further, 30 parts of ion exchange water, 0.2 part of potassium lauryl sulfate, 30 parts of styrene, 15 parts of butyl methacrylate, 10 parts of acrylic acid, 1 part of triethanolpropane trimethacrylate, 1 part of 1,6-hexanediol dimethacrylate, t- A reaction solution consisting of 0.5 part of dodecyl mercaptan was added to a reaction vessel while stirring at 70 ° C. to cause a polymerization reaction. Thereafter, the reaction solution was neutralized with ammonia to a pH of 8 to 8.5 and filtered through a 0.3 μm filter to obtain an aqueous solution of polymer fine particles.

Emulsion D : 100 parts of ion-exchanged water was put into a reaction vessel equipped with a dropping device, a thermometer, a water-cooled reflux condenser, and a stirrer, and 0.2% of potassium persulfate as a polymerization initiator was added at 70 ° C. with stirring. Parts were added. 7 parts of ion-exchanged water, 0.05 part of sodium lauryl sulfate, 15 parts of styrene, 1 part of urethane prepolymer composed of tolylene diisocyanate 1,5-pentanediol, 15 parts of butyl methacrylate and 0.02 of t-dodecyl mercaptan The monomer solution obtained by mixing was dropped into a container at 70 ° C. and reacted to prepare a primary substance. To this primary material was added 2 parts ammonium persulfate 10% solution and stirred. Further, a reaction solution consisting of 30 parts of ion-exchanged water, 0.2 part of potassium lauryl sulfate, 30 parts of styrene, 1 part of acrylamide, 15 parts of butyl methacrylate, 1 part of dipentaerythritol hexamethacrylate, and 0.6 part of t-dodecyl mercaptan was prepared. The mixture was added to the reaction vessel with stirring at 0 ° C. to cause a polymerization reaction. Thereafter, the reaction solution was neutralized with ammonia to a pH of 8 to 8.5, and filtered through a 0.3 μm filter to obtain an aqueous solution of polymer fine particles.

  Emulsions A to D obtained as described above are the following water-soluble emulsions. That is, Emulsion A has a core-shell structure, and the core portion has a crosslinked structure made of a polymer using acrylic acid containing glycidoxide, and the shell portion is polymerized with acrylic acid to form carboxylate of acrylic acid on the surface. It consists of resin which has group. Emulsion B has a core-shell structure, the core part has a cross-linked structure made of a copolymer of acrylic acid and methacrylic acid containing glycidoxide, and the shell part polymerizes acrylic acid to form acrylic acid on the surface. It consists of a resin having a carboxyl group and an amide group of acrylamide. In addition, Emulsion C has a core-shell type structure, the core part is made of a polymer made of methacrylic acid containing glycidoxide and is crosslinked, and the shell part is polymerized with acrylic acid and methacrylic acid to form acrylic on the surface. It consists of a resin having a carboxyl group of acid and methacrylic acid and an amide group of methacrylamide. Emulsion D has a core-shell structure, and the core part is made of a mixture of a resin containing a urethane bond and a copolymer of styrene and acrylic acid. These resins have a crosslinked structure, and the shell part has It consists of a resin having a carboxyl group of methacrylic acid and an amide group of acrylamide on the surface by polymerizing methacrylate and acrylamide.

  In the remaining amount of water, 0.1 to 1% of Proxel XL-2 is used to prevent ink corrosion, and 0.001 to 0.05% of benzotriazole is used to prevent corrosion of ink jet recording head members. Added.

Example 1 addition amount (% by weight)
MA100 (Mitsubishi Chemical Corporation) modified product 6.0
Surfinol 465 1.2
Emulsion A 3.0
Glycerin 15.0
Diethylene glycol 5.0
2-pyrrolidone 5.0
Thiodiglycol 3.0
Triethanolamine 0.8
Potassium hydroxide 0.1
Ion exchange water

Example 2
MA600 (Mitsubishi Chemical Co., Ltd.) Modified product (135) 7.5
Surfinol 104 0.1
Surfinol 465 1.9
Emulsion B 5.0
Glycerin 12.0
2-pyrrolidone 20.0
Thiodiglycol 4.0
Triethanolamine 3.0
Potassium hydroxide 0.1
Ion exchange water

Example 3
Color Black FW18 (manufactured by Tegusa) modified product (120) 15.0
Surfinol TG 0.2
Surfinol 465 1.0
Emulsion C 3.0
Glycerin 7.0
Diethylene glycol 3.0
2-pyrrolidone 1.0
1,5-pentanediol 5.0
Triethanolamine 0.5
Potassium hydroxide 0.2
Ion exchange water

Example 4
Microjet CW1 (50) 7.0
Surfinol 104 0.2
Surfinol 465 1.2
Emulsion D 2.5
1,5-pentanediol 5.0
Glycerin 15.0
Diethylene glycol 5.0
Thiodiglycol 5.0
2-pyrrolidone 1.0
Triethanolamine 2.5
Potassium hydroxide 0.01
Ion exchange water

Example 5
# 55RCF (Mitsubishi Chemical Corp.) Modified (200) 5.0
Surfinol 465 1.2
Emulsion A 2.5
Emulsion D 0.5
Glycerin 1.0
Trimethylolpropane 3.0
2-pyrrolidone 15.0
Triethanolamine 0.9
Potassium hydroxide 0.05
Ion exchange water

Example 6
MONARCH880 (Cabot Corporation) Denatured product (60) 5.0
Surfinol 465 0.3
Emulsion B 10.0
Glycerin 15.0
2-pyrrolidone 10.0
Triethanolamine 0.5
Ammonia 2.0
Potassium hydroxide 0.1
Remaining amount of ion-exchanged water The average particle size of carbon black used in the following comparative examples was as shown in parentheses.

Comparative Example 1
MA100 (Mitsubishi Chemical Corporation) (90) 5.0
Triethyleneethylene monomethyl ether 10.0
Ethylene glycol 8.0
Dispersant 3.0
Diethylene glycol monomethyl ether 7.0
Ion exchange water

Comparative Example 2
Color Black FW18 (Degussa) (120) 5.5
Glycerin 10.0
Diethylene glycol 10.0
2-pyrrolidone 5.0
Dispersant 3.5
Ion exchange water

Comparative Example 3
MONARK880 (manufactured by Cabot) (110) 5.5
Diethylene glycol 10.0
Surfinol 465 1.0
Dispersant 2.5
Ion exchange water

Printing Evaluation Test The ink composition described above was filled in an inkjet printer-MJ-930C manufactured by Seiko Epson Corporation, and an image was formed on a recording medium. The recording media used were Conqueror paper, Favorit paper, Modo Copy paper, Rapid Copy paper, EPSON EPP paper, Xerox 4024 paper, Xerox 10 paper, Neenha Bond paper, Rcopyy 6200 paper, Yamayuri paper, Xerox R paper, Xerox R paper Pectoric recording medium coated with silica sol on polyester jet, coated with polyester resin as glossy paper B, swollen recording medium for swelling ink, colloidal with glossy paper C having an average particle diameter of 500 nm on paper Silica is applied using latex as a binder.

  The print quality, finger touch, and water resistance of the obtained image were evaluated as follows.

Print quality The bleeding of the dried printed matter was judged according to the following evaluation criteria.
Evaluation A: There is almost no blur.
Evaluation B: Slight blur is observed, but in a practically acceptable range.
Evaluation C: Smudge is observed and the image is deteriorated.
Evaluation D: Image is extremely inferior due to bleeding.

The printed matter that had been dried to the touch was rubbed with a yellow aqueous fluorescent pen (Zebra PEN2 manufactured by Zebra Co., Ltd.), and the degree of contamination of the printed matter was examined.

The result was determined according to the following evaluation criteria.
Evaluation A: Color does not fade even when rubbed multiple times.
Evaluation B: Color does not fade even after rubbing once.
Evaluation C: Color is slightly lost when rubbed once.
Evaluation D: Color is lost when rubbed once.

Dropped pure water to printed matter was water-resistant dry, were examined water drops traces of printed product after 1 minute.
The result was determined according to the following evaluation criteria.
Evaluation A: No trace is left.
Evaluation B: Almost no trace is left.
Evaluation C: A trace remains.
Evaluation D: A trace remains.

  The above results were as described in the following table.

1 is a perspective view of a main part of an ink jet recording apparatus in which an ink composition according to the present invention is preferably used. FIG. 2 is a main cross-sectional view for explaining an embodiment of the ink jet recording apparatus of FIG. 1. FIG. 2 is an exploded perspective view of a main part of an ink tank used in the ink jet recording apparatus of FIG. 1.

Explanation of symbols

3 Recording Head 6 Reaction Liquid Pool 6a Form 7 Ink Tank 9 Communication Hole 9a Vent 20 Recording Medium 21 Sealing Member

Claims (14)

Carbon black comprising at least a pigment, a water-soluble organic solvent, a surfactant, water, and further a water-soluble emulsion, wherein the pigment can be dispersed and / or dissolved in water without a dispersant. An ink composition for ink jet recording, wherein the surfactant is a acetylene glycol-based surfactant represented by the following formula (I).

(In the formula, m and n satisfy 0 ≦ m + n ≦ 50, and R ¹ , R ² , R ³ , and R ⁴ each independently represent an alkyl group.) The pigment can be dispersed and / or dissolved in water without a dispersant by surface treatment so that at least one functional group of carbonyl group, carboxyl group, hydroxyl group, or sulfone group or a salt thereof is bonded to the surface of the pigment. The ink composition according to claim 1, wherein   The ink composition according to claim 1, wherein the pigment has an average particle diameter of 50 to 200 nm.   The ink composition according to any one of claims 1 to 3, comprising 2 to 10% by weight of the pigment.   The ink composition according to any one of claims 1 to 4, comprising 0.3 to 2.0% by weight of the acetylene glycol surfactant.   The ink composition according to any one of Claims 1 to 5, wherein the water-soluble emulsion comprises a resin mainly composed of acrylic acid and / or methacrylic acid.   The ink composition according to any one of claims 1 to 6, wherein the water-soluble emulsion comprises a core-shell type resin particle comprising a core part and a shell part surrounding the core part.   The core part is made of an epoxy resin, a urethane resin, an acrylic resin, and / or a methacrylic acid resin, and the shell part is made of a resin having a surface having a carboxyl group of acrylic acid and / or methacrylic acid. The ink composition as described.   The ink composition according to claim 7 or 8, wherein the resin of the core part has a crosslinked structure.   10. The water-soluble organic solvent according to claim 1, wherein the water-soluble organic solvent is one or more selected from the group consisting of glycerin, diethylene glycol, 1,5-pentanediol, and thiodiglycol. Ink composition.   The ink composition according to any one of claims 1 to 10, further comprising 2-pyrrolidone.   The ink composition according to any one of claims 1 to 11, further comprising triethanolamine.   The ink composition according to any one of claims 1 to 12, which has a pH of 7 to 11.   The ink composition according to any one of claims 1 to 13, further comprising potassium hydroxide.

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