Patent Description:
A variety of kinds of cleaning liquid are proposed as a cleaning liquid for a discharge nozzle (jetting nozzle) and an ink channel of an ink-jet recording apparatus. For example, as a cleaning liquid having an excellent wetting property and an excellent cleaning property, and even in a case that a pigment ink is used for printing, having an excellent mutual solubility with respect to the pigment ink, Patent Literature <NUM> describes a cleaning liquid containing a fluorine-based surfactant, and an acetylene glycol-based surfactant in which an average molar number of addition of ethylene oxide is in a range of <NUM> to <NUM>. <CIT> discloses a maintenance liquid for an ink jet recording apparatus which possesses excellent cleaning properties. In particular, a maintenance liquid, which exhibits excellent cleaning properties even in an ink jet printer using an ink having a high colorant density and containing a pigment, and a maintenance liquid for an ink jet recording apparatus, which does not attack members for a printer and possesses excellent antifoaming properties and preservative/antimold effect, are disclosed. The maintenance liquid for an ink jet recording apparatus according to the present invention comprises water and an alkylene glycol monoalkyl ether. <CIT> discloses an inkjet recording device capable of maintaining an ejection stability for a long period of time. The ink jet recording device includes a recording head having an ejection port configured to eject an aqueous ink and an ejection-port surface in which the ejection port is opened and a liquid supply mechanism configured to supply an ejection-port clogging prevention liquid into the ejection port, the aqueous ink contains at least one component selected from the group consisting of pigment particles and resin particles, and the clogging prevention liquid has a dielectric constant of <NUM> to <NUM> at <NUM>° C. <CIT> discloses a cleaning solution used for cleaning an ink that comprises water and a resin. <CIT> discloses a water-based ink for ink-jet recording including: a resin-dispersed pigment; an emulsion of a vinyl chloride-acrylic copolymer having a glass transition temperature of equal to or more than <NUM>° C. ; an anionic surfactant having only one anion group in a molecule thereof; and water. A ratio (S/E) of a blending amount (S) of the anionic surfactant to a solid content blending amount (E) of the emulsion of the vinyl chloride-acrylic copolymer in an entire amount of the water-based ink is equal to or more than <NUM>.

On the other hand, there is a demand for a water-based ink for ink-jet recording which has a satisfactory wetting property with respect to a recording medium having a low water-absorbing property or having a non-water absorbing property (hereinafter referred to as "hydrophobic" recording medium, in some cases), such as coated paper, film, etc. In order to provide such a water-based ink, it is conceivable to add a wetting agent in the water-based ink. However, in a case that maintenance (cleaning of a discharge nozzle, a wiper wiping the discharge nozzle, an ink channel, etc.) is performed in an ink-jet recording apparatus using the water-based ink (added with the wetting agent), the wetting agent in the water-based ink undergoes a phase separation, which in turn causes any blocking (stoppage, closing) and/or clogging of the channel, in some cases.

In view of the above situation, an object of the present invention is to provide a cleaning liquid capable of suppressing any closing of channel and clogging of nozzle(s) during the maintenance of an ink-jet recording apparatus using a water-based ink having a satisfactory wetting property to a hydrophobic recording medium.

The invention is defined in the appended independent claim. Further developments of the invention are specified in the dependent claims.

According to a first aspect of the present invention, there is provided a cleaning liquid usable for cleaning of an ink-jet recording apparatus, the cleaning liquid including:.

According to a second aspect of the present invention, there is provided a set including:.

According to a third aspect of the present invention, there is provided an ink-jet recording apparatus including:.

According to a fourth aspect of the present invention, there is provided a cleaning method of cleaning an ink-jet recording apparatus including: an ink storing part, an ink-jet head, an ink channel provided between the ink storing part and the ink-jet head, and a cleaning liquid-supplying mechanism,
the cleaning method including supplying the cleaning liquid of the first aspect to the ink-jet head and the ink channel, by using the cleaning liquid-supplying mechanism.

The cleaning liquid related to the present invention includes the first water-soluble organic solvent, the second water-soluble organic solvent and the nonionic surfactant such that the above-described conditions (<NUM>) to (<NUM>) are satisfied, thereby making it possible to suppress any closing of channel and clogging of nozzle during the maintenance of an ink-jet recording apparatus using a water-based ink having a satisfactory wetting property to a hydrophobic recording medium.

[<FIG> is a schematic view depicting the configuration of an example of an ink-jet recording apparatus in which a cleaning liquid related to the present invention is usable.

A cleaning liquid related to the present invention is suitably usable to perform maintenance of an ink-jet recording apparatus using a water-based ink for ink-jet recording (hereinafter also referred to as a "water-based ink" or an "ink", in some cases) having a satisfactory wetting property with respect to a recording medium having hydrophobicity such as, for example, coated paper, plastic, film, an OHP sheet, etc., but is not limited to or restricted by this usage. The cleaning liquid related to the present invention is usable to perform maintenance also, for example, of an ink-jet recording apparatus using a water-based ink for ink-jet recording suitable for a recoding medium which is different from the hydrophobic recording medium and which includes, for example, regular paper (plain paper), glossy paper, mat paper, etc. In the present invention, the term "coated paper" means, for example, paper obtained by coating, with a coating agent, regular paper made mainly from pulp, such as high-grade print paper and middle-grade print paper. The coating agent is applied to the regular paper to improve its smoothness, whiteness, brightness, etc. The coated paper is specifically exemplified by high-grade coated paper, middle-grade coated paper, etc..

The cleaning liquid related to the present invention will be explained. The cleaning liquid related to the present invention is a cleaning liquid usable for cleaning of an ink-jet recording apparatus and contains a first water-soluble organic solvent, a second water-soluble organic solvent, a nonionic surfactant, and water.

A vapor pressure at <NUM> of the first water-soluble organic solvent is not less than <NUM> Pa. The first water-soluble organic solvent is exemplified, for example, by: propylene glycol (hereinafter referred to as "PG", in some cases; vapor pressure at <NUM>: <NUM> Pa), <NUM>,<NUM>-butanediol (vapor pressure at <NUM>: <NUM> Pa), ethylene glycol (hereinafter referred to as "EG", in some cases; vapor pressure at <NUM>: <NUM> Pa), etc..

Only one kind of the first water-soluble organic solvent as described above may be used singly, or two or more kinds of the first water-soluble organic solvent as described above may be used in combination. A content amount (A) of the first water-soluble organic solvent in the entire amount of the cleaning liquid will be described later on.

A vapor pressure at <NUM> of the second water-soluble organic solvent is not more than <NUM> Pa. The second water-soluble organic solvent is exemplified, for example, by tripropylene glycol (hereinafter referred to as "TPG", in some cases; vapor pressure at <NUM>: <NUM> Pa), diethylene glycol (hereinafter referred to as "DEG", in some cases; vapor pressure at <NUM>: <NUM> Pa), glycerol (hereinafter referred to as "GLY", in some cases; vapor pressure at <NUM>: <NUM> Pa), <NUM>,<NUM>-pentanediol (vapor pressure at <NUM>: <NUM> Pa), triethylene glycol-n-butyl ether (hereinafter referred to as "BTG" in some cases; vapor pressure at <NUM>: <NUM> Pa), tripropylene glycol n-butyl ether (hereinafter referred to as "TPnB" in some cases; vapor pressure at <NUM>: <NUM> Pa), etc. The vapor pressures of DEG, GLY, <NUM>,<NUM>-pentanediol, BTG listed above indicate the vapor pressures thereof, respectively, at <NUM>. However, since the vapor pressures of these second water-soluble organic solvents at <NUM> are smaller than those at <NUM>, the vapor pressure of these second water-soluble organic solvents are not more than <NUM> Pa at <NUM>.

A content amount (B) of the second water-soluble organic solvent in the entire amount of the cleaning liquid will be described later on.

The water-soluble organic solvent contained in the cleaning liquid may be only the first water-soluble organic solvent and the second water-soluble organic solvent as described above. Alternatively, the cleaning liquid may further contain another water-soluble organic solvent, in addition to the first and second water-soluble organic solvents, which is different from the first and second water-soluble organic solvents. The mass ratio of the first water-soluble organic solvent and the second water-soluble organic solvent relative to the entire amount of the water-soluble organic solvent in the cleaning liquid is, for example, not less than <NUM>% by mass or <NUM>% by mass.

A commercially available product is exemplified, for example, by: "OLFINE (trade name) E1004", "OLFINE (trade name) E1008", "OLFINE (trade name) E1010", which are produced by NISSHIN CHEMICAL CO. ; "SURFYNOL (trade name) <NUM>", "SURFYNOL (trade name) <NUM>" and "SURFYNOL (trade name) <NUM>" which are produced by AIR PRODUCTS AND CHEMICALS, INC. ; "ACETYLENOL (trade name) E40" and "ACETYLENOL (trade name) E100" produced by KAWAKEN FINE CHEMICALS CO. ; "EMULGEN (trade name) MS100", "EMULGEN (trade name) 123P", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) 104P", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) 109P", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) 210P", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) 306P", "EMULGEN (trade name) 320P". "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) 409PV", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) MS1108", "EMULGEN (trade name) <NUM>-<NUM>", "EMULGEN (trade name) <NUM>-<NUM>", "EMULGEN (trade name) <NUM>-<NUM>", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) <NUM>-HA", "EMULGEN (trade name) <NUM>", "EMULGEN (trade name) LS-<NUM>", "EMULGEN (trade name) LS-<NUM>", "EMULGEN (trade name) LS-<NUM>", "EMULGEN (trade name) MS-<NUM>", "EMULGEN (trade name) A-<NUM>", "EMULGEN (trade name) A-<NUM>", "EMULGEN (trade name) A-<NUM>", "EMULGEN (trade name) B-<NUM>", "EMULGEN (trade name) PP-<NUM>", "RHEODOL (trade name) TW-P120", "RHEODOL (trade name) 460V, and "RHEODOL (trade name) TW-IS399C" produced by KAO CORPORATION; "NYMEEN (trade name) S-<NUM>" produced by NOF CORPORATION; "NOIGEN (trade name) XL" series, "NOIGEN (trade name) TDS" series, "NOIGEN (trade name) LF-80X), "NOIGEN (trade name) LF-100X", "NOIGEN (trade name) TDX" series, "NOIGEN (trade name) SD" series, "NOIGEN (trade name) LP" series, "DKS NL-Dash" series, "NOIGEN (trade name) CL-<NUM>", "ANTI-FROTH (trade name" M-<NUM>", "ANTI-FROTH (trade name) M-<NUM>, "NOIGEN (trade name) EA" series, "NOIGEN (trade name) EN" series, "PHE-<NUM>", "EPAN (trade name)" series, "DKS NL" series, "NOIGEN (trade name) ET" series, "NOIGEN (trade name) ES" series, "NOIGEN (trade name) DS-<NUM>" series, "NOIGEN (trade name) GIS" series, "NOIGEN (trade name) HC" series, "Amilazine (trade name) D", "SORGEN (trade name) TW-<NUM>", "SORGEN (trade name) TW-<NUM>", "SORGEN (trade name) TW-80V" and "SORGEN (trade name) TW-<NUM>" produced by DKS CO. (DAI-ICHI KOGYO SEIYAKU CO.

The nonionic surfactant contains an acetylene glycol-based surfactant having an ethylene oxide skeleton (ethylene oxide chain). Among the above-described commercially available products of the nonionic surfactant, "OLFINE (trade name) E1004", "OLFINE (trade name) E1008", "OLFINE (trade name) E1010", which are produced by NISSHIN CHEMICAL CO. ; "SURFYNOL (trade name) <NUM>", "SURFYNOL (trade name) <NUM>" and "SURFYNOL (trade name) <NUM>" which are produced by AIR PRODUCTS AND CHEMICALS, INC. ; "ACETYLENOL (trade name) E40" and "ACETYLENOL (trade name) E100" produced by KAWAKEN FINE CHEMICALS CO. , correspond to the acetylene glycol-based surfactant having the ethylene oxide skeleton.

Only one kind of the nonionic surfactant as described above may be used singly, or two or more kinds of the nonionic surfactant as described above may be used in combination. A content amount (C) of the nonionic surfactant in the entire amount of the cleaning liquid will be described later on.

The surfactant contained in the cleaning is only the acetylene glycol-based surfactant having the ethylene oxide skeleton.

The water is preferably ion-exchanged water or pure water (purified water). The content amount of the water in the entire amount of the cleaning liquid is, for example, in a range of <NUM>% by mass to <NUM>% by mass. The content amount of the water may be, for example, a balance of the other components.

Although it is preferred that the cleaning liquid does not contain any colorant, the cleaning liquid may contain a colorant. In a case that the cleaning liquid contains a colorant, it is preferred that a content amount of the colorant in the cleaning liquid is an amount to such an extent which does not affect a recorded image. The content amount of the colorant in the entire amount of the cleaning liquid is, for example, not more than <NUM>% by mass, or <NUM>% by mass.

The cleaning liquid ink may further include a conventionally known additive, as necessary. The additive is exemplified, for example, by pH-adjusting agents, viscosity-adjusting agents, surface tension-adjusting agents, fungicides, etc. The viscosity-adjusting agents are exemplified, for example, by polyvinyl alcohol, cellulose, water-soluble resin, etc. In view of further suppressing any closing of channel and clogging of nozzle(s), the cleaning liquid ink may not include water-insoluble particles which are similar to those included in a water-based ink described later. The water-insoluble particles may be exemplified, for example, by a pigment, a resin for dispersing pigment (resin dispersant), resin minutes particles (resin fine particles), etc..

The cleaning liquid can be prepared, for example, by uniformly mixing the first water-soluble organic solvent, the second water-soluble organic solvent, the nonionic surfactant and the water by a conventionally known method.

The cleaning liquid satisfies the following conditions (<NUM>) to (<NUM>). The cleaning liquid contains the first water-soluble organic solvent, the second water-soluble organic solvent and the nonionic surfactant such that the above-described conditions (<NUM>) to (<NUM>) are satisfied, thereby making it possible to suppress any closing of channel and/or clogging of nozzle during the maintenance of an ink-jet recording apparatus using a water-based ink having a satisfactory wetting property to a hydrophobic recording medium. <MAT> <MAT> <MAT> in the conditions (<NUM>) to (<NUM>),.

The cleaning liquid may further satisfy the following condition (<NUM>) and/or condition (<NUM>). <MAT> <MAT> wherein in the conditions (<NUM>) and (<NUM>),.

It is allowable to appropriately adjust each of the content amount (A) of the first water-soluble organic solvent, the content amount (B) of the second water-soluble organic solvent and the content amount (C) of the nonionic surfactant so as to satisfy the above-described conditions (<NUM>) to (<NUM>), for example, as follows.

The content amount (A) of the first water-soluble organic solvent is, for example, in a range of <NUM>% by mass to <NUM>% by mass.

The content amount (B) of the second water-soluble organic solvent is, for example, in a range of <NUM>% by mass to <NUM>% by mass, or in a range of <NUM>% by mass to <NUM>% by mass.

The content amount (C) of the nonionic surfactant is, for example, not less than <NUM>% by mass. , or not less than <NUM>% by mass. The upper limit value of the content amount (C) of the nonionic surfactant is not particularly limited, and is, for example, not more than <NUM>% by mass or not more than <NUM>% by mass.

The cleaning liquid may be usable together with a water-based ink including water-insoluble particles and water.

The water-insoluble particles may be exemplified, for example, by a pigment, a resin for dispersing pigment (resin dispersant), resin minutes particles (resin fine particles), etc..

The pigment is not particularly limited, and may be exemplified, for example, by carbon black, an inorganic pigment, an organic pigment, etc. The carbon black is exemplified, for example, by furnace black, lamp black, acetylene black, channel black, etc. The inorganic pigment is exemplified, for example, by titanium oxide, iron oxide-based inorganic pigments, carbon black-based inorganic pigments, etc. The organic pigment is exemplified, for example, by azo-pigments such as azo lake, insoluble azo-pigment, condensed azo-pigment, chelate azo-pigment, etc.; polycyclic pigments such as phthalocyanine pigment, perylene and perynon pigments, anthraquinone pigment, quinacridone pigment, dioxadine pigment, thioindigo pigment, isoindolinone pigment, quinophthalone pigment, etc.; dye lake pigments such as basic dye type lake pigment, acid dye type lake pigment, etc.; nitro pigments; nitroso pigments; aniline black daylight fluorescent pigment; etc. Further, it is also allowable to use, as the pigment, any pigment different from those listed above and dispersible in water phase. Specific examples of these pigments include, for example, C. Pigment Blacks <NUM>, <NUM>, and <NUM>; C. Pigment Yellows <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>; C. Pigment Oranges <NUM> and <NUM>; C. Pigment Reds <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>:<NUM>, <NUM>:<NUM>, <NUM>, <NUM>:<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>; C. Pigment Violets <NUM> and <NUM>; C. Pigment Blues <NUM>, <NUM>, <NUM>, <NUM>, <NUM>:<NUM>, <NUM>:<NUM>, <NUM>:<NUM>, <NUM>:<NUM>, <NUM>, <NUM>, and <NUM>; C. Pigment Greens <NUM> and <NUM>; solid solutions of the above-listed pigments; etc. The water-based ink may be an ink in which the pigment is dispersed in water with a dispersant. As the dispersant, it is allowable to use, for example, a general polymeric dispersant (resin for dispersing pigment or resin dispersant), etc., and may be prepared in-house. Alternatively, in the water-based ink, the pigment may be subjected to polymer capsulation.

The pigment may be a self-dispersible pigment. The self-dispersible pigment is dispersible in water without using any dispersant, for example, owing to the fact that at least one of a hydrophilic functional group and the salt thereof including, for example, carbonyl group, hydroxyl group, carboxylic acid group, sulfonic acid group (sulfonate group), phosphoric acid group (phosphate group), etc., is introduced into the surfaces of the particles of the pigment by the chemical bond directly or with any group intervening therebetween. It is possible to use self-dispersible pigments wherein the pigment is subjected to the surface treatment by any one of methods described, for example, in <CIT> (corresponding to <CIT>), Published <CIT>(corresponding to <CIT>), Published <CIT>corresponding to United States Patent Application Publication No. <CIT>, Published <CIT> corresponding to United States Patent Application Publications No. <CIT> and No. <CIT>, Published <CIT>corresponding to United States Patent Application Publications No. <CIT>, etc. It is possible to use, as a material for the self-dispersible pigment, either one of the inorganic pigment and the organic pigment. Further, a pigment which is suitable for the above-described treatment includes, for example, carbon black such as "MA8" and "MA100" produced by MITSUBISHI CHEMICAL CORPORATION, etc. As the self-dispersible pigment, it is possible, for example, to use a commercially available product. The commercially available product includes, for example, "CAB-O-JET (trade name) <NUM>", "CAB-O-JET (trade name) 250C", "CAB-O-JET (trade name) <NUM>", "CAB-O-JET (trade name) 270Y", "CAB-O-JET (trade name) <NUM>", "CAB-O-JET (trade name) <NUM>", "CAB-O-JET (trade name) 450C", "CAB-O-JET (trade name) <NUM>" and "CAB-O-JET (trade name) 470Y" produced by CABOT SPECIALTY CHEMICALS; "BONJET (trade name) BLACK CW-<NUM>" and "BONJET (trade name) BLACK CW-<NUM>" produced by ORIENT CHEMICAL INDUSTRIES, LTD. ; "LIOJET (trade name) WD BLACK 002C" produced by TOYO INK MFG.

The solid content amount of the pigment (pigment solid content amount) in the entire amount of the water-based ink is not particularly limited, and may be appropriately determined based on, for example, a desired optical density, chromaticness, etc. The pigment solid content amount is, for example, in a range of <NUM>% by mass to <NUM>% by mass, in a range of <NUM>% by mass to <NUM>% by mass, or in a range of <NUM>% by mass to <NUM>% by mass.

The pigment may function, for example, as a colorant.

The water-base ink may contain, as the colorant, a dye instead of, or in addition to, the pigment.

The dye is not specifically limited, and is exemplified, for example, by a direct dye, an acidic dye, a basic dye, a reactive dye, a food dye, etc. Specific examples of the dye include, for example, C. Direct Black, C. Direct Blue, C. Direct Red, C. Direct Yellow, C. Direct Orange, C. Direct Violet, C. Direct Brown, C. Direct Green; C. Acid Black, C. Acid Blue, C. Acid Red, C. Acid Yellow, C. Acid Orange, C. Acid Violet; C. Basic Black, C. Basic Blue, C. Basic Red, C. Basic Violet; C. Reactive Blue, C. Reactive Red, C. Reactive Yellow; C. Food Black, C. Food Red, C. Food Yellow; etc. C. Direct Black described above is exemplified, for example, by C. Direct Blacks <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. C. Direct Blue described above is exemplified, for example, by C. Direct Blues <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. C. Direct Red described above is exemplified, for example, by C. Direct Reds <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. C. Direct Yellow described above is exemplified, for example, by C. Direct Yellows <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. C. Direct Orange described above is exemplified, for example, by C. Direct Oranges <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. C. Direct Violet described above is exemplified, for example, by C. Direct Violets <NUM>, <NUM>, etc. C. Direct Brown described above is exemplified, for example, by C. Direct Brown <NUM>, etc. C. Direct Green described above is exemplified, for example, by C. Direct Green <NUM>, etc. C. Acid Black described above is exemplified, for example, by C. Acid Blacks <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. C. Acid Blue described above is exemplified, for example, by C. Acid Blues <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. C. Acid Red described above is exemplified, for example, by C. Acid Reds <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. C. Acid Yellow described above is exemplified, for example, by C. Acid Yellows <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. C. Acid Orange described above is exemplified, for example, by C. Acid Oranges <NUM>, <NUM>, etc. C. Acid Violet described above is exemplified, for example, by C. Acid Violet <NUM>, etc. The C. Basic Black is exemplified, for example, by C. Basic Black <NUM>, etc. The C. Basic Blue is exemplified, for example, by C. Basic Blues <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. The C. Basic Red is exemplified, for example, by C. Basic Reds <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. The C. Basic Violet is exemplified, for example, by C. Basic Violets <NUM>, <NUM>, <NUM>, etc. C. Reactive Blue described above is exemplified, for example, by C. Reactive Blues <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. C. Reactive Red described above is exemplified, for example, by C. Reactive Reds <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. C. Reactive Yellow described above is exemplified, for example, by C. Reactive Yellows <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. C. Food Black described above is exemplified, for example, by C. Food Blacks <NUM>, <NUM>, etc. C. Food Red described above is exemplified, for example, by C. Food Reds <NUM>, <NUM>, <NUM>, etc. C. Food Yellow described above is exemplified, for example, by C. Food Yellow <NUM>, etc..

It is allowable that one kind of the dye as described above is used singly, or two or more kinds of the dye are used in combination. The content amount of the dye in the entire amount of the water-based ink is, for example, in a range of <NUM>% by mass to <NUM>% by mass, in a range of <NUM>% by mass to <NUM>% by mass, or in a range of <NUM>% by mass to <NUM>% by mass.

The water-based ink may be a color ink (chromatic ink) including the colorant, or may be a colorless or achromatic ink (clear ink) not including any colorant.

The glass-transition temperature (Tg) of the resin minute particles is, for example, in a range of -<NUM> to <NUM>, in a range of <NUM> to <NUM>, or is not more than <NUM>. The resin minute particles may be, for example, resin minute particles contained in a resin emulsion. The term "resin emulsion" means a resin emulsion composed of, for example, the resin minute particle and a disperse medium (for example, water, etc.); in the resin emulsion, the resin minute particles are dispersed with a specific particle diameter (particle size) in the disperse medium, rather than in a dissolved state in the disperse medium. In the present specification, the resin particles included in the resin emulsion are defined as "emulsion particles". The resin minute particles may be exemplified, for example, by acrylic acid-based resin, maleate ester-based resin, vinyl acetate-based resin, carbonate-based resin, styrene-based resin, ethylene-based resin, propylene-based resin, urethane-based resin, and copolymer resin thereof. Only one kind of the resin minute particles as described above may be used singly, or two or more kinds of the resin minute particles as described above may be used in combination.

As the resin emulsion, it is allowable to use, for example, a commercially available product. The commercially available product is exemplified, for example, by "MOWINYL (trade name) 6969D" (acrylic resin emulsion) (Tg: <NUM>), "MOWINYL (trade name) <NUM>" (Tg: <NUM>) and "MOWINYL (trade name) DM772" (Tg: <NUM>) produced by JAPAN COATING RESIN CO. ; "POLYSOL (trade name) AP-<NUM> (styrene-acrylic resin emulsion) produced by SHOWA DENKO K. ; "SUPERFLEX (trade name) <NUM>" (urethane resin emulsion) (Tg: <NUM>) produced by DKS CO. (DAI-ICHI KOGYO SEIYAKU CO.

The mean particle diameter of the resin minute particles is, for example, in a range of <NUM> to <NUM>, in a range of <NUM> to <NUM> or in a range of <NUM> to <NUM>. The mean particle diameter can be measured, for example, by using a dynamic light scattering particle diameter distribution measuring apparatus "LB-<NUM>" (product name) produced by HORIBA, LTD. , as the arithmetic mean diameter. The mean particle diameter may be a mean particle diameter (intensity mean particle diameter) calculated based on an intensity-based particle size distribution (light scattering intensity-based particle size distribution).

The content amount of the resin minute particles in the entire amount of the water-based ink is, for example, in a range of <NUM>% by mass to <NUM>% by mass, in a range of <NUM>% by mass to <NUM>% by mass, or in a range of <NUM>% by mass to <NUM>% by mass. One kind of the resin minute particles described above may be used singly, or two or more kinds of the resin minute particles as described above may be used in combination.

The water in the above-described water-based ink is preferably ion-exchanged water or pure water (purified water). The content amount of the water in the entire amount of the water-based ink is, for example, in a range of <NUM>% by mass to <NUM>% by mass, or in a range of <NUM>% by mass to <NUM>% by mass. The content amount of the water may be, for example, a balance of the other components.

The water-based ink may further contain a water-soluble organic solvent and a surfactant which are similar to those in the cleaning liquid, as described above.

The water-based ink may further include a conventionally known additive, as necessary. The additive is exemplified, for example, by pH-adjusting agents, viscosity-adjusting agents, surface tension-adjusting agents, fungicides, etc. The viscosity-adjusting agents are exemplified, for example, by polyvinyl alcohol, cellulose, water-soluble resin, etc..

The water-based ink can be prepared, for example, by uniformly mixing the water-insoluble particles, the water and an optionally other additive(s) as necessary, by a conventionally known method, and then removing any non-dissolved matter, with a filter, etc..

According to the present invention, a set of the above-described cleaning liquid and the above-described water-based ink can also be provided.

For example, the cleaning liquid is usable for cleaning the ink-jet head, the ink channel, and a wiper which makes contact with the nozzle-formation surface of the ink-jet head having nozzles formed therein so as to wipe the ink off from the nozzle-formation surface, etc., in the ink-jet recording apparatus.

Next, an ink-jet recording apparatus and a cleaning method of the ink-jet recording apparatus related to the present invention will be explained.

The ink-jet recording apparatus related to the present invention is an ink-jet recording apparatus characterized by including: an ink storing part, an ink-jet head, and an ink channel provided between the ink storing part and the ink-jet head, and being configured to discharge an ink stored in the ink storing part by the ink-jet head; the ink-jet recording apparatus further including a cleaning liquid-supplying mechanism, wherein the cleaning liquid-supplying mechanism is capable of supplying, to the ink-jet head and the ink channel, the cleaning liquid related to the present invention. The ink-jet recording apparatus related to the present invention may further include a wiper configured to make contact with a nozzle-formation surface, of the ink-jet head, and the cleaning liquid-supplying mechanism may be capable of supplying the cleaning liquid to the wiper. Further, as will be described later on, the ink-jet recording apparatus related to the present invention may further include a drying mechanism configured to dry a recording part or recording portion recorded with the ink.

The cleaning method of cleaning an ink-jet recording apparatus related to the present invention is a cleaning method of cleaning an ink-jet recording apparatus including: an ink storing part, an ink-jet head, and an ink channel provided between the ink storing part and the ink-jet head, the method being characterized by supplying the cleaning liquid related to the present invention by a cleaning liquid-supplying mechanism to thereby clean the ink-jet head and the ink channel. In the cleaning method related to the present invention, the ink-jet recording apparatus further includes a wiper configured to make contact with a nozzle-formation surface, of the ink-jet head; the cleaning method may clean the wiper by supplying the cleaning liquid, to the wiper, by the cleaning liquid-supplying mechanism.

<FIG> schematically depicts an exemplary configuration of the ink-jet recording apparatus related to the present invention. As depicted in <FIG>, an ink-jet recording apparatus <NUM> includes a feed tray <NUM>, a conveyance mechanism (not depicted) such as a roller, recording mechanisms 102A and 102B, a platen <NUM>, a drying mechanism <NUM>, a discharge tray <NUM>, and an ink storing part <NUM> such as ink cartridges or ink tanks. The feed tray <NUM> can support a plurality of pieces of a recording medium P (e.g., a plurality of pieces of coated paper sheet) stacked thereon.

The recording mechanism includes a carriage 102A and an ink-jet head (ink discharging mechanism) 102B. The carriage 102A is supported by two guide rails (not depicted) extending orthogonally with respect to a conveyance direction of the recording medium P. The two guide rails are supported by a casing (not depicted) of the ink-jet recording apparatus <NUM>. The carriage 102A is connected to a well-known belt mechanism (not depicted) provided in the two guide rails. The belt mechanism is driven by a carriage motor (not depicted). The carriage motor is driven to thereby cause the carriage 102A connected to the belt mechanism to reciprocate (move reciprocatingly) in an orthogonal direction which is orthogonal with respect to the conveyance direction of the recording medium P.

Further, four ink tubes (ink channels) 107a to 107d connecting the ink storing part <NUM> and the ink-jet head 102B, and a flexible flat cable (not depicted) electrically connecting a control board (not depicted) and the ink-jet head 102B extend from the carriage 102A. Water-based inks of four colors (yellow, magenta, cyan, and black) stored in the ink storing part <NUM> are supplied to the ink-jet head 102B via the four ink tubes 107a to 107d. For example, at least one of the four color water-based inks is the water-based ink for ink-jet recording which constructs the set related to the present invention, together with the cleaning liquid related to the present invention. A control signal outputted from the control board is transmitted to the ink-jet head 102B via the flexible flat cable.

As depicted in <FIG>, the carriage 102A has the ink-jet head 102B mounted or installed therein. Nozzles 102C are formed in a lower surface of the ink-jet head 102B. A front end of each of the nozzles 102C is exposed from the carriage 102A and the lower surface of the ink-jet head 102B. The ink-jet head 102B includes an actuator (not depicted) which applies force for jetting or discharging the water-based ink(s) which is (are) supplied from the ink storing part <NUM> to the ink-jet head 102B via the ink tube(s) 107a to 107d. The actuator may be an actuator of any system, such as a piezoelectric element system, a thermal ink-jet system, an electrostatic attraction system, etc. The ink-jet head 102B jets or discharges the water-based ink, as fine or minute ink droplets of the water-based ink, from the nozzles 102C during a process in which the carriage 102A reciprocates in the orthogonal direction with respect to the conveyance direction of the recording medium P. With this, an image is recorded on the recording medium P. The ink-jet recording apparatus <NUM> may be provided with a wiper <NUM> configured to perform wiping of a surface, having the plurality of nozzles 102C formed therein, of the ink-jet head 102B which is returned to a reset position in a case that recording is finished. The platen <NUM> is arranged so as to face the recording mechanism, and supports the recording medium P conveyed from the feed tray <NUM>.

The drying mechanism <NUM> heats and dries a recording part of the recording medium P. The drying temperature during the drying can be adjusted as appropriate by changing the setting of the drying mechanism <NUM>. Specifically, the drying temperature may be, for example, in a range of <NUM> to <NUM> or in a range of <NUM> to <NUM>. The drying time may be also adjusted as appropriate by changing the setting of the drying mechanism <NUM>. For example, the drying time may be in a range of a second(s) exceeding <NUM> (zero) seconds to not more than <NUM> seconds, in a range of <NUM> seconds to <NUM> seconds, or in a range of <NUM> seconds to <NUM> seconds. Any drying mechanism which is capable of drying the recording part may be used as the drying mechanism <NUM>. Examples of the drying mechanism <NUM> include, for example, commercially available dryers, IR heaters, ovens, belt conveyer ovens, irons, hot presses, etc. A non-contact drying mechanism, such as the drier, IR heater, the oven, the belt conveyer oven, etc., which dries the recording part of the recording medium P without contacting with the recording part is preferably used.

The recording medium P after recording and drying is conveyed to the discharge tray <NUM>.

The cleaning liquid-supplying mechanism supplies the cleaning liquid to the ink-jet head 102B, the ink tube(s) 107a to 107d, the wiper <NUM>, etc., and performs the cleaning of the ink-jet head 102B, the ink tube(s) 107a to 107d, the wiper <NUM>, etc., with the cleaning liquid. The cleaning liquid-supplying mechanism may be any mechanism provided that the mechanism is capable of supplying the cleaning liquid to the ink-jet head 102B, the ink tube(s) 107a to 107d, the wiper <NUM>, etc. For example, it is allowable to use, as the cleaning liquid-supplying mechanism, a cleaning liquid-storing part <NUM> configure to store the cleaning liquid therein. It is allowable that the ink tubes (ink channels) 107a to 107d are connected to the cleaning liquid-storing part <NUM>, instead of being connected to the ink storing part <NUM> as depicted in <FIG>, and to supply the cleaning liquid, rather than the ink, to the ink-jet head 102B, the ink tubes 107a to 107d and the wiper <NUM> to thereby clean the ink-jet head 102B, the ink tubes 107a to 107d and the wiper <NUM>.

Next, Examples of the present invention are explained together with Comparative Examples. Note that the present invention is not limited to and restricted by Examples and Comparative Examples described below.

<NUM> of Terathane (trade name) <NUM> (polyether diol produced by INVISTA (Wichita, KS), <NUM> of <NUM>,<NUM>'-dimethylolpropionic acid (DMPA), <NUM> of sulfolane and <NUM> of dibutyltin dilaurate (DBTDL) were added to a flask provided with a dropping funnel, a condenser and an agitator (stirring device) under an atmosphere of nitrogen, then were heated up to <NUM> while being mixed, and then were mixed sufficiently; thus, a mixture was obtained. To the obtained mixture, <NUM> of m-tetramethylene xylylenediisocyanate (TMXDI) was added with the dropping funnel, and remaining TMXDI in the dropping funnel was rinsed with <NUM> of sulfolane into the flask. The temperature was raised up to <NUM>, and was maintained at <NUM> until the content rate of isocyanate reached to be not more than <NUM>% by mass. Next, the temperature was lowered up to <NUM>, then <NUM> of diethanolamine (DEA) was added to the mixture over <NUM> (five) minutes with the dropping funnel, and the temperature was maintained at <NUM> until remaining DEA in the dropping funnel was rinsed with <NUM> of sulfolane into the flask. Furthermore, the temperature was maintained at <NUM> for one hour, then <NUM> of a <NUM>% by mass aqueous solution of potassium hydroxide was added to the mixture over <NUM> (ten) minutes with the dropping funnel, then <NUM> of deionized water was further added to the mixture. Then, the temperature was maintained at <NUM> for one hour, and cooling to the room temperature was performed. Thus, a resin dispersant with <NUM>% by mass of solid content was obtained.

The resin dispersant was neutralized with either one of potassium hydroxide and amine in order to increase the solubility in water and to make the resin dispersant to easily dissolve to water. Then, a microfluidizer of high-pressure compressed air system (Model name: M-110Y, produced by MICROFLUIDICS (Newton, Massachusetts)) was used so as to produce a mixture in which content amount of carbon black was approximately <NUM>% by mass and the mass ratio (P/D) of the content amount (P) of the carbon black to the content amount (D) of the resin dispersant was P/D = <NUM>. Then, deionized water was added to the mixture so that the content amount of the carbon black was made to be approximately <NUM>% by mass for the suitable medium mill grinding condition; and the mixture was milled (pulverized) for <NUM> (four) hours. After the milling, the deionized water was added, and the mixture was mixed sufficiently. Then, after any impurity was filtered and removed, dilution with deionized water was performed; thus, a pigment dispersion liquid A was obtained.

A pigment dispersion Liquid B was obtained similarly to the above-described preparation of the pigment dispersion liquid A, except that an Eiger Minimill (Model name: M250, produced by VSE EXP, EIGER MACHINERY INC. (Chicago, Illinois) was used, instead of using the microfluidizer of high-pressure compressed air system, and that a phthalocyanine pigment was used instead of using the carbon black.

Ingredients or components, except for CAB-O-JET (trade name) <NUM> and the pigment dispersion liquid A or B, which were included in Water-based ink composition (TABLE <NUM>) were mixed uniformly or homogeneously; and thus an ink solvent was obtained. Subsequently, the ink solvent was added to CAB-O-JET (trade name) <NUM> and the pigment dispersion liquid A or B, followed by being mixed uniformly, and thus a mixture was obtained. After that, the obtained mixture was filtrated through a cellulose acetate membrane filter (pore size <NUM>) produced by TOYO ROSHI KAISHA, LTD. , and thus water-based inks <NUM> to <NUM> for ink-jet recording as indicated in TABLE <NUM> was obtained.

Ingredients or components in Water-based ink composition (TABLE <NUM>) were mixed uniformly or homogeneously; and thus a mixture was obtained. After that, the obtained mixture was filtrated through a polytetrafluoroethylene (PTFE) membrane filter (pore size <NUM>) produced by TOYO ROSHI KAISHA, LTD. , and thus the water-based ink <NUM> for ink-jet recording as indicated in TABLE <NUM> was obtained. The water-based ink <NUM> is a colorless or achromatic ink (clear ink) not including any colorant.

Components which were included in Cleaning Liquid Composition (TABLE <NUM>) as indicated below were mixed uniformly or homogeneously; and thus a cleaning liquid in each of Examples <NUM> to <NUM> and Comparative Examples <NUM> to <NUM> as indicated in TABLE <NUM> were obtained.

With respect to the cleaning liquids of Examples <NUM> to <NUM> and Comparative examples <NUM> to <NUM>, evaluation of clogging of nozzle was conducted by the following methods.

The cleaning liquid of each of Examples <NUM> to <NUM> and Comparative Examples <NUM> to <NUM> and one of the water-based inks <NUM> to <NUM> were mixed at a ratio of <NUM>:<NUM> and thus a mixed liquid was obtained. A cartridge filled with the mixed liquid was inserted into a digital multifunctional peripheral DCP-385C equipped with an ink-jet printer produced by BROTHER KOGYO KABUSHIKI KAISHA, and a nozzle discharge pattern was recorded thereby. Afterwards, the digital multifunctional peripheral DCP-385C equipped with the ink-jet printer was left to stand for <NUM> (twenty four) hours in an environment wherein the temperature was <NUM> and the relative humidity was <NUM>%. After the digital multifunctional peripheral DCP-385C equipped with the ink-jet printer was left to stand for <NUM> (twenty four) hours as described above, another cartridge filled with the mixed liquid was inserted into the digital multifunctional peripheral DCP-385C equipped with the ink-jet printer in an environment of the room temperature (<NUM>), a predetermined maintenance operation for introducing ink was performed, then the nozzle discharge pattern was recorded again. The number of non-discharge nozzle(s) were counted before and after the digital multifunctional peripheral DCP-385C equipped with the ink-jet printer was left to stand as described above, and the clogging of nozzle was evaluated based on the following evaluation criterion. Note that the number of non-discharge nozzle(s) before the digital multifunctional peripheral DCP-385C equipped with the ink-jet printer was left to stand was <NUM> (zero).

The cleaning liquid compositions and the evaluation results of the above-described evaluation in Examples <NUM> to <NUM> and Comparative Examples <NUM> to <NUM> are indicated in TABLE <NUM> as follows.

As indicated in TABLE <NUM>, in Examples <NUM> to <NUM>, the evaluation result was satisfactory in relation to the clogging of nozzle in all of the water-based inks <NUM> to <NUM>.

On the other hand, Comparative Example <NUM> in which (A+B) / C < <NUM> and which did not satisfy the above-described condition (<NUM>), Comparative Examples <NUM> and <NUM> in which A+B > <NUM> and which did not satisfy the above-described condition (<NUM>), and Comparative Examples <NUM>, <NUM> and <NUM> in which A / B < <NUM> and which did not satisfy the above-described condition (<NUM>) had unsatisfactory results in relation to the clogging of nozzle in any one or all of the water-based inks <NUM> to <NUM>.

Claim 1:
A cleaning liquid usable for cleaning of an ink-jet recording apparatus, the cleaning liquid comprising:
a first water-soluble organic solvent, a vapor pressure at <NUM> of the first water-soluble organic solvent being not less than <NUM> Pa;
a second water-soluble organic solvent, a vapor pressure at <NUM> of the second water-soluble organic solvent being not more than <NUM> Pa;
a nonionic surfactant; and
water,
wherein the cleaning liquid satisfies the following conditions (<NUM>) to (<NUM>): <MAT> <MAT> <MAT> in the conditions (<NUM>) to (<NUM>),
A: a content amount (% by mass) of the first water-soluble organic solvent in an entire amount of the cleaning liquid,
B: a content amount (% by mass) of the second water-soluble organic solvent in the entire amount of the cleaning liquid, and
C: a content amount (% by mass) of the nonionic surfactant in the entire amount of the cleaning liquid,
wherein the first water-soluble organic solvent includes at least one selected from the group consisting of: propylene glycol, ethylene glycol and <NUM>,<NUM>-butanediol, and
wherein the second water-soluble organic solvent includes at least one selected from the group consisting of: glycerol, diethylene glycol, tripropylene glycol, <NUM>,<NUM>-pentanediol, triethylene glycol-n-butyl ether and tripropylene glycol-n-butyl ether, and
wherein the nonionic surfactant includes an acetylene glycol-based surfactant having an ethylene oxide skeleton and wherein the acetylene glycol-based surfactant having the ethylene oxide skeleton is the only surfactant contained in the cleaning liquid.