JP2007063454A - Water-based recording liquid and recording method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-based recording liquid for ink-jet recording, effective for reducing pH variation even in the case of using a coloring agent having large pH variation with time, unsusceptible to polyvalent metals existing in the recording liquid composition in an extremely small amount and having excellent ejection stability and provide a recording method to use the recording liquid. <P>SOLUTION: The water-based recording liquid at least comprises a coloring agent, water and a water-soluble organic solvent and further comprises a hypophosphorous acid salt. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an aqueous recording liquid (ink) suitable for ink jet recording to which an on-demand method such as a piezo method or a thermal method or a continuous ejection method such as a charge control method is applied, and particularly has excellent characteristics as a color ink for plain paper. The present invention relates to an aqueous recording liquid comprising an aqueous ink composition having the following properties and used also as an aqueous writing instrument, recorder, and pen plotter.

  Since the inkjet recording method is simpler than other recording methods, full colorization is easy, and there is an advantage that a high-resolution image can be obtained even with an apparatus having a simple configuration. As an ink-jet ink, a dye-based ink in which various water-soluble dyes are dissolved in water or a mixture of water and an organic solvent is used, but the dye-based ink has excellent color tone sharpness, There were drawbacks inferior in light resistance and water resistance. On the other hand, pigment-based inks in which carbon black and various organic pigments are dispersed are actively studied because they are superior in light resistance and water resistance compared to dye-based inks. However, pigment-based inks tend to clog nozzles more easily than dye-based inks. Usually, pigments in pigment-based inks are dispersed using a dispersing agent such as a polymer dispersing agent or a surfactant dispersing agent. However, in recent years, with the aim of improving the stability of the dispersing system and eliminating clogging of the inkjet head, Self-dispersing pigments have been developed in which ionic functional groups such as sulfone groups and carboxyl groups are added to the surface and can be dispersed by electrostatic repulsion without a dispersant. However, regardless of which colorant is used, the pH of the ink tends to change over time due to the structure of the dye molecule or the molecular structure of the dispersing group. When the pH of the ink changes, the ink container Alternatively, a reaction or the like occurs in the liquid contact portion with the supply member, and the stability of the ink physical properties is impaired. Further, when the pigment dispersion is used as a colorant for the ink, the dispersion stability is further impaired due to a change in pH, and the process proceeds to aggregation of the dispersed particles. If the stability of ink physical properties or dispersion stability is impaired, in an ink jet system in which ink droplets are ejected from fine ejection nozzles to form an image, there is a problem due to a decrease in landing accuracy due to physical property changes or nozzle clogging. Discharging occurs, which is not preferable for the recording method.

  In order to prevent these situations, the boric acid-potassium chloride-sodium hydroxide system, glycine-sodium chloride-sodium hydroxide system, phosphoric acid described in Patent Documents 1 and 2, etc. are used to prevent the pH change of the ink. Potassium dihydrogen-disodium hydrogen phosphate, sodium carbonate-sodium bicarbonate, potassium hydrogen phthalate-sodium hydroxide, sodium citrate-sodium hydroxide, potassium dihydrogen citrate-sodium tetraborate, acetic acid-acetic acid There is a method of adding a buffer such as sodium or sodium dihydrogen phosphate-citric acid. Further, Patent Document 3 attempts to improve the stability of ink physical properties by including phosphorous acid or phosphite in the ink composition. In addition, when a self-dispersing pigment is used as a colorant, the pH drop over time is large. To improve the pH drop, Patent Documents 4 to 6 each add a specific buffer to the ink composition. It is described to do. However, even when these pH buffering agents are used, the effect has not reached a practically problematic level, and the buffering agents are mainly inorganic acid salts, organic acid salts, and organic sulfonic acid salts, They are easily changed to polyvalent metal calcium or magnesium present in a minute amount as an impurity in the ink and a salt compound whose water solubility is lowered by salt exchange, and there is a possibility that non-ejection due to nozzle clogging or the like may occur.

JP-A 64-6074 Japanese Patent Laid-Open No. 4-189886 JP-A-7-1743418 JP 2003-201430 A JP 2003-206420 A JP 2003-313470 A

  The present invention has been made in view of the above situation, and even when a colorant having a large pH fluctuation with time is used, the pH fluctuation is reduced and contained in a trace amount in the recording liquid composition. An object of the present invention is to provide an aqueous recording liquid for inkjet that is not affected by a polyvalent metal and has excellent ejection stability, and a recording method using the recording liquid.

  As a result of intensive investigations on materials that are not affected by polyvalent metals contained in trace amounts in the recording liquid composition and that have an excellent pH buffering action, hypophosphite serves its purpose. The present invention was found out to be an optimal compound.

That is, the said subject is solved by the following this invention.
(1) An aqueous recording liquid comprising at least a colorant, water, a water-soluble organic solvent, and further containing a hypophosphite.
(2) The aqueous recording liquid according to item (1), wherein the pH of the recording liquid is 6.5 to 11.
(3) The aqueous recording liquid according to item (1) or (2), wherein the content of the hypophosphite is 0.01 to 3.0% by weight based on the whole recording liquid. .
(4) The aqueous recording liquid according to any one of (1) to (3), wherein the hypophosphite is a salt of sodium or potassium.
(5) The aqueous recording liquid according to any one of (1) to (3), wherein the hypophosphite is a salt of inorganic ammonia.
(6) The hypophosphite salt is an organic amine salt selected from monoethanolamine, diethanolamine, and triethanolamine, according to any one of (1) to (3) Aqueous recording solution.
(7) The aqueous recording according to any one of (1) to (3), wherein the hypophosphite is a salt of tetramethylammonium, tetraethylammonium and hydroxyethyltrimethylammonium organic ammonium. liquid.
(8) The water-soluble organic solvent of the recording liquid is glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-butanediol, 2,3-butanediol, 1, 4-butanediol, 1,5-pentanediol, tetraethylene glycol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, polyethylene glycol, 1,2,4-butanetriol, 1,2, At least one water-soluble selected from 6-hexanetriol, thiodiglycol, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone Characterized by containing an organic solvent (1) term to (7) an aqueous recording liquid according to any one of claim.
(9) The recording liquid further comprises 2-n-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2, The aqueous solution according to any one of (1) to (8), wherein the aqueous solution contains one or two diol compounds selected from 2,4-trimethyl-1,3-pentanediol. Recording liquid.
(10) Item (1) to Item (9), wherein the colorant is a pigment dispersed in a number average particle system of 20 to 150 nm with a polymer dispersant or a surfactant, and is used for inkjet recording. The aqueous recording liquid according to any one of the above.
(11) Any of (1) to (9), wherein the colorant is a self-dispersing pigment having a number average particle size of 20 to 150 nm having a hydrophilic group on the surface, and is used for inkjet recording. An aqueous recording liquid according to any one of the above.
(12) A recording method comprising forming an image on a recording medium by ejecting and flying the aqueous recording liquid according to (1) to (11) as droplets from a fine ejection port.

  As is clear from the following detailed and specific description, the aqueous recording liquid of the present invention has a small pH variation with time and excellent ejection stability, and can be suitably used for an ink jet printer. is there.

Hereinafter, the present invention will be described in more detail. The present invention is characterized in that it contains at least a colorant, water, a water-soluble organic solvent, and further contains hypophosphite. Hypophosphite used in the present invention, Specific examples of sodium and potassium salts include sodium hypophosphite, sodium hydrogen phosphite, disodium hydrogen hypophosphite, potassium hypophosphite, potassium hypophosphite, dipotassium hydrogen phosphite Specific examples of inorganic ammonia or organic amine salts include ammonium hypophosphite, ammonium hydrogen phosphite, diammonium hydrogen phosphite, monoethanolamine hypophosphite salt, diethanolamine hypophosphite Specific examples of salts, triethanolamine hypophosphite, and organic ammonium salts include tetramethylammonium hypophosphite and tetraethyl hypophosphite. Ammonium is preferably hypophosphorous acid hydroxyethyl trimethylammonium.
The hypophosphite is contained in the recording liquid in an amount of 0.01 to 3.0% by weight, preferably 0.05 to 2.0% by weight, based on the entire recording liquid. If it is less than 0.01%, the function as a pH buffering agent cannot be achieved. Conversely, if it exceeds 3.0% by weight, it will precipitate when moisture evaporates on the head surface due to drying during standby, etc. Make it stable.

The recording liquid of the present invention uses water as a liquid medium. However, in order to make the recording liquid have desired physical properties, to prevent the recording liquid from drying, and to improve dissolution stability, etc. The following water-soluble organic solvents are used. A plurality of these water-soluble organic solvents may be used in combination. Glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, Tetraethylene glycol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, polyethylene glycol, 1,2,4-butanetriol, 1,2,6-hexanetriol, thiodiglycol, 2-pyrrolidone N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, and the like.
The content of these water-soluble organic solvents is 1 to 60% by weight, more preferably 5 to 40% by weight, based on the entire recording liquid. If it is less than 1% by weight, there is no effect of preventing drying of the recording liquid, and if it exceeds 60% by weight, the viscosity of the recording liquid exceeds the ink jet recording suitability.

  The present invention further includes 2-n-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, One or two kinds of diol compounds selected from 2,2,4-trimethyl-1,3-pentanediol are contained. By containing these in the recording liquid, the wettability of the recording liquid to the inner wall of the head ink flow path is improved, and the ejection stability and frequency stability can be obtained even with a small addition amount. Although these diol compounds have low solubility in water, they have high penetrability. The content of these diol compounds is about 0.1 to 4.5% by weight, preferably about 0.5 to 3% by weight. When the content of the diol compound is less than 0.1% by weight, the effect on the penetrability or wettability of the recording liquid becomes insufficient. When the content exceeds 4.5% by weight, the undissolved part is separated into the recording liquid, and the pigment. It causes agglomeration.

  Similarly to the diol compound, diethylene glycol or trialkylene monoalkyl ether can be contained for the purpose of improving the wettability to the inner wall of the head ink channel or the permeability to the medium. Specific examples include diethylene glycol mono-n-butyl ether, diethylene glycol mono-iso-butyl ether, triethylene glycol mono-n-butyl ether, diethylene glycol mono-n-hexyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol monoethyl ether, etc. is there.

  As the colorant of the present invention, a water-soluble dye or pigment is used. Specific examples of the water-soluble dye include acidic dyes, direct dyes, and reactive dyes according to the color index classification. As more specific examples, the acid dyes include CI Acid Yellow 17, CI Acid Yellow 23, CI Acid Yellow 42, CI Acid Yellow 44, CI Acid Yellow 79, CI Acid Yellow 142, CI Acid Red 35, CI Acid Red 42, CI Acid Red 52, CI Acid Red 82, CI Acid Red 87, CI Acid Red 92, CI Acid Red 134, CI Acid Red 249, CI Acid Red 254, CI Acid Red 289, CI Acid Blue 1, CI Acid Blue 9, CI Acid Blue 15, CI Acid Blue 59, CI Acid Blue 93, CI Acid Blue 249, CI Acid Black 2, and the like.

  As direct dyes, CI Direct Yellow 33, CI Direct Yellow 44, CI Direct Yellow 50, CI Direct Yellow 86, CI Direct Yellow 132, CI Direct Yellow 142, CI Direct Yellow 144, CI Direct Orange 26, CI Direct Red 9, CI Direct Red 17, CI Direct Red 28, CI Direct Red 81, CI Direct Red 83, CI Direct Red 89, CI Direct Red 225, CI Direct Red 227, CI Direct Blue 15, CI Direct Blue 76, CI Direct Blue 86, CI Direct Blue 199, CI Direct Blue 201, CI Direct Blue 202, CI Direct Black 19, CI Direct Black 22, CI Direct Black 32, CI Direct Black 38, CI Direct Black 51, CI Direct Black 154, CI Direct Black 168, and reactive dyes include CI Reactive Yellow 17, CI Reactive Red 6, and CI Reactive Red 180 and CI Reactive Blue 2 are preferred examples used in the present invention.

  The content of the dye in the recording liquid composition is preferably 2 to 10% by weight, more preferably about 3 to 8% by weight. If the content of the dye is less than 2% by weight, the printing or writing density is insufficient, and if it exceeds 10% by weight, the dye cannot be dissolved and precipitation occurs during long-term storage, and the ejection stability deteriorates.

The pigment used in the present invention is not particularly limited, and an inorganic pigment and an organic pigment can be used. As the inorganic pigment, in addition to titanium oxide and iron oxide, carbon black produced by a known method such as a contact method, a furnace method, or a thermal method can be used. Organic pigments include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments), polycyclic pigments (eg, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments). , Dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinofullerone pigments, etc.), dye chelates (for example, basic dye type chelates, acidic dye type chelates), nitro pigments, nitroso pigments, aniline black, and the like.
The type of carbon black used as a raw material is not particularly limited. Any of the above-mentioned acidic carbon black, neutral carbon black, and alkaline carbon black can be used.

  Specific examples of the pigment preferably used in the present invention include the following. For black, carbon black (CI Pigment Black 7) such as furnace black, lamp black, acetylene black, channel black, or metal such as copper, iron (CI Pigment Black 11), titanium oxide And organic pigments such as aniline black (CI Pigment Black 1).

  Specific examples of carbon black include # 10B, # 20B, # 30, # 33, # 40, # 44, # 45, # 45L, # 50, # 55, # 95, # 260, ## manufactured by Mitsubishi Chemical Corporation. 900, # 1000, # 2200B, # 2300, # 2350, # 2400B, # 2650, # 2700, # 4000B, CF9, MA8, MA11, MA77, MA100, MA220, MA230, MA600, MCF88, etc .; Monarch made by Cabot 120, Monarch 700, Monarch 800, Monarch 880, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, Mogal L, Legal 99R, Legal 250R, Legal 300R, Legal 330R, Legal 400R, Legal 500R and Legal 660R, etc .; Made of plastic Printex A, Printex G, Printex U, Printex V, Printex 55, Printex 140U, Printex 140V, Special Black 4, Special Black 4A, Special Black 5, Special Black 6, Special Black 100, Special Black 250 Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color Black S150, Color Black S160, Color Black S170, and the like.

  Further, for color use, C.I. I. Pigment Yellow 1 (Fast Yellow G), 3, 12 (Disazo Yellow AAA), 13, 14, 17, 24, 34, 35, 37, 42 (Yellow Iron Oxide), 53, 55, 81, 83 (Disazo Yellow HR) ), 95, 97, 98, 100, 101, 104, 408, 109, 110, 117, 120, 138, 153, C.I. I. Pigment orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22 (Brilliant First Scarlet), 23, 31, 38, 48: 2 (Permanent Red 2B (Ba)), 48: 2 (Permanent Red 2B (Ca)), 48: 3 (Permanent Red 2B (Sr)), 48: 4 (Permanent Red 2B (Mn)), 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmine 6B), 60: 1, 63 : 1, 63: 2, 64: 1, 81 (Rhodamine 6G rake), 83, 88, 101 (Bengara), 104, 105, 106, 108 (Cadmium red), 112, 114, 122 (Quinacridone magenta), 123 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, 219, CI. Pigment violet 1 (rhodamine lake), 3, 5: 1, 16, 19, 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue R), 15: 1, 15: 2, 15: 3 (phthalocyanine blue E), 16, 17: 1, 56, 60, 63, C.I. I. Pigment green 1, 4, 7, 8, 10, 17, 18, 36, and the like.

  The dispersant for using these pigments as a colorant for the aqueous recording liquid composition is a normal anionic surfactant or a polymer dispersant. Polyoxyethylene alkyl ether sulfate salts, polyoxyethylene alkyl phenyl ether sulfate salts, polyoxyethylene allyl ether sulfate salts, and polymer dispersants described in JP-A-199100 include natural proteins such as gelatin and casein, and gum arabic. Glucoxides such as rubber and saponin, cellulose derivatives such as methylcellulose, carboxymethylcellulose, and hydroxymethylcellulose, lignin sulfonates, natural polymers such as ceramics, polyacrylates, styrene-acrylic acid copolymer salts, vinylnaphthalene- Crylic acid copolymer salt, styrene-maleic acid copolymer salt, vinyl naphthalene-maleic acid copolymer salt, sodium salt of β-naphthalenesulfonic acid formalin condensate, anionic polymer such as polyphosphoric acid, polyvinyl alcohol , Non-ionic polymers such as polyvinyl pyrrolidone and polyethylene glycol, and one or a mixture of two or more of these can be used. The addition amount is preferably 0.1 to 20% by weight, more preferably 1 to 10% by weight, based on the total weight of the recording liquid.

  The self-dispersible pigment having at least one hydrophilic group on the surface of the present invention has a hydrophilic functional group on the surface, does not contain a so-called polymer dispersant or surfactant, and is itself dispersed in a solvent. Possible pigments are used. As the hydrophilic functional group possessed by the pigment, any nonionic, anionic or cationic hydrophilic functional group can be used, and in particular, a carboxyl group, a hydroxyl group, a sulfonic acid group, or a phosphoric acid group alone or in combination of two or more. A combination is preferable, and among these, a carboxyl group alone or two or more combinations including a carboxyl group are more preferable. When it has a carboxyl group, a sulfonic acid group, or a phosphoric acid group, it can be used as it is in a free acid state, but it is more advantageous in terms of dispersibility that a part or all of it forms a salt, which is preferable. As the substance forming the salt, various basic substances can be used, but an alkali metal, ammonium, or an organic ammonium compound alone or a combination of two or more kinds is preferable. As a pigment into which a hydrophilic functional group is introduced, both inorganic and organic pigments can be used.

  It is also possible to use a commercially available product as a self-dispersible pigment having the hydrophilic group on the surface preferably used in the present invention. As a preferred example, a black self-dispersing pigment is a carboxyl group modified by Cabot Corporation. Type CAB-O-JET300, sulfone group-modified CAB-O-JET200, BONJETBLACK CW-1, CW-2, etc. manufactured by Orient Chemical Industries, Ltd. -O-JET250C (cyan), CAB-O-JET260M (magenta), CAB-O-JET270Y (yellow) pigment dispersion, and the like.

  The number average particle diameter of the pigment dispersed particles in the recording liquid is adjusted to a range of 20 to 150 nm, preferably 40 to 110 nm. If the number average particle diameter is less than 20 nm, the recorded material has a sense of transparency, and a sufficient optical density cannot be obtained. On the other hand, if it exceeds 150 nm, the particles are likely to settle, and the storage stability of the recording liquid tends to be lowered.

  The content of the pigment in the recording liquid composition is preferably 2 to 10% by weight, more preferably about 3 to 8% by weight. If the pigment content is less than 2% by weight, the printing or writing density is insufficient, and if it exceeds 10% by weight, the pigment is likely to aggregate, causing precipitation during long-term storage, and the ejection stability being poor.

  The inkjet recording liquid of the present invention contains a surfactant. The surfactant used here is not used as a so-called pigment dispersant, but has the effect of assisting the dispersion stability of the dispersed pigment, the effect of allowing the recording liquid to penetrate into the paper as the recording medium, and the like. It is for planning. Examples of the surfactant that can be used in the recording liquid for ink jet recording of the present invention include various anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, etc. , Anionic surfactants and nonionic surfactants.

  The anionic surfactant preferably contains a polyoxyalkylene alkyl ether carboxylate surfactant, a polyoxyalkylene alkyl ether sulfonate salt, or a polyoxyalkylene aryl ether sulfonate surfactant. Examples of the polyoxyalkylene alkyl ether carboxylate surfactant include ECT-3NEX, ECTD-3NEX, ECTD-6NEX, ECT-3, ECT-7, AKYPORLM 45NV (CHEM-Y), AKYPO manufactured by Nikko Chemicals. RLM45 (CHEM-Y), AKYPO RLM100NV (CHEM-Y), AKYPO RLM100 (CHEM-Y), etc. can be used, and polyoxyalkylene alkyl ether sulfonate or polyoxyalkylene aryl ether sulfonate surfactants can be used. Examples include NICOLL SBL-44 manufactured by Nikko Chemicals, Hightenol N-07, Hightenol N-08, Hightenol N-17, Hightenol NE-05, and Hightenol NE-15 manufactured by Daiichi Kogyo Seiyaku. , Itenoru NF-13, Hitenol 08E, Hitenol 12, or the like can be used Hitenol 18E. In particular, when ECTD-3NEX, ECTD-6NEX, or Haitenol 18E is used, good recording quality is exhibited.

  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, Ethers such as polyoxyethylene alkyl ether and polyoxyalkylene alkyl ether, polyoxyethylene oleic acid, polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, Esters such as sorbitan sesquioleate, polyoxyethylene monooleate, polyoxyethylene stearate, Fluoroalkyl ester, and the like fluorine-containing surfactants such as perfluoroalkyl carboxylates.

  The amount of these surfactants added is preferably about 0.01 to 2.0% by weight of the recording liquid composition, more preferably about 0.1 to 1.5% by weight. An addition amount in this range improves the dispersion stability and has the effect of allowing the recording liquid to penetrate into the paper as the recording medium. If it exceeds 2.0% by weight, bleeding increases.

  The recording liquid of the present invention uses the water-soluble dye or the pigment dispersion as a colorant, and the water-soluble dye is an anionic, and the dispersant for the pigment dispersion is an anionic. Therefore, the pH of the aqueous solution is weakly alkaline and stable, and the pH as the recording liquid is 6.5 to 11 and maintains a stable state including the initial time and lapse of time. Examples of pH adjusters include amines such as diethanolamine, triethanolamine, propanolamine, morpholine and their modified products, inorganic salts such as potassium hydroxide, sodium hydroxide, lithium hydroxide, ammonium hydroxide, quaternary Ammonium hydroxide (tetramethylammonium etc.), potassium carbonate, sodium carbonate, lithium carbonate etc. are mentioned.

  Further, the recording liquid composition according to the present invention may contain a preservative, a fungicide, a dye dissolution aid, an antioxidant and the like in order to improve various properties. Preferred examples of antiseptics and fungicides include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-benzisothiazoline-3-one (Proxel CRL, Proxel BDN, Proxel GXL, Proxel XL-2, Proxel LV of ICI) and the like.

  Further, as dye dissolution aids, urea, N-methyl-2-pyrrolidone, allophanates such as allophanate and methyl allophanate, burettes such as burette, dimethyl burette and tetramethyl burette, and L- as an antioxidant. Examples include ascorbic acid and its salts.

  The recording liquid composition according to the present invention can contain an ultraviolet absorber. Examples of such commercially available products include Tinuvin 328, 900, 1130, 384, 292, 123, 144, 622, 770, 292, Irgacor 252, 153, Irganox 1010, 1076, 1035, MD1024 manufactured by Ciba Geigy.

  The recording liquid composition according to the present invention can contain a viscosity modifier. Specific examples thereof include rosins, alginic acids, polyvinyl alcohol, hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, polyacrylate, polyvinyl pyrrolidone, gum arabic starch and the like.

  The aqueous recording liquid according to the present invention can be used for writing instrument inks and ink jet recording inks. As the ink jet recording method, there are a recording method in which mechanical energy is applied to ink to eject droplets, and a recording method in which thermal energy is applied to ink and ink droplets are ejected by foaming of the ink. The recording ink of the present invention can be suitably used. When used for ink jet recording, the ink preferably has a characteristic that it can be ejected from an ink jet head. From the viewpoint of ejection from an inkjet head, the surface tension is preferably 20 to 60 mN / m, more preferably 25 to 50 mN / m, as a characteristic of the ink. The viscosity is preferably 1.5 to 10.0 mPa · s, more preferably 2.0 to 8.0 mPa · s.

  Next, the aqueous recording liquid of the present invention is stored in a recording liquid cartridge (ink cartridge), and the ink cartridge is mounted on an ink jet printer, and ejected and ejected as droplets from a fine ejection port to form an image on a recording medium. Although the method to do is demonstrated with reference to an accompanying drawing, the following is only one of the structural examples, Comprising: This invention is not limited at all.

FIG. 1 is a schematic front view of a mechanism part of a serial type ink jet recording apparatus equipped with an ink cartridge equipped with a recording liquid storage part storing an aqueous recording liquid of the present invention.
The mechanism part of this ink jet recording apparatus lays a main support guide rod (3) and a sub support guide rod (4) between the side plates (1), (2) on both sides in a substantially horizontal positional relationship, The carriage unit (5) is slidably supported in the main scanning direction by the support guide rod (3) and the secondary support guide rod (4).

The carriage unit (5) has four heads (6) for ejecting yellow (Y) ink, magenta (M) ink, cyan (C) ink and black (Bk) ink, respectively, and their ejection surfaces (nozzles). The surface (6a) is mounted facing downward, and on the upper side of the head (6) of the carriage unit (5) is an ink supply body of each color for supplying ink to each of the four heads (6). Four ink cartridges (7y), (7m), (7c), and (7k) are mounted interchangeably.
The carriage unit (5) is a timing belt (11) stretched between a drive pulley (drive timing pulley) (9) and a driven pulley (idler pulley) (10) rotated by the main scanning motor (8). The carriage (5), that is, the four heads (6) are moved in the main scanning direction by driving and controlling the main scanning motor (8).

  Further, subframes (13) and (14) are erected on the bottom plate (12) connecting the side plates (1) and (2), and the paper (16) is mainly placed between the subframes (13) and (14). A conveyance roller (15) for feeding in the sub-scanning direction orthogonal to the scanning direction is rotatably held. A sub-scanning motor (17) is disposed on the side of the sub-frame (14), and the rotation of the sub-scanning motor (17) is transmitted to transmit the rotation of the sub-scanning motor (17) to the transport roller (15). A gear (18) fixed to the shaft and a gear (19) fixed to the shaft of the conveying roller (15) are provided.

  Further, between the side plate (1) and the subframe (13), a reliability maintenance / recovery mechanism (hereinafter referred to as “subsystem”) (21) of the head (6) is disposed. The sub-system (21) holds four cap means (22) for capping the ejection surface of each head (6) by a holder (23), and the holder (23) can be swung by a link member (24). The carriage unit (5) is brought into contact with the engaging portion (25) provided in the holder (23) by the movement of the carriage unit (5) in the main scanning direction, so that the carriage unit (5) moves according to the movement of the carriage unit (5). The holder (23) is lifted up, the cap means (22) is used to capping the ejection surface (6a) of the ink jet head (6), and the carriage unit (5) is moved to the printing area side, whereby the carriage unit (5 ), The holder (23) is lifted down so that the cap means (22) is separated from the ejection surface (6a) of the inkjet head (6).

The cap means (22) is connected to the suction pump (27) via the suction tube (26), and forms an atmosphere opening, and communicates with the atmosphere via the atmosphere opening tube and the atmosphere opening valve. ing. The suction pump (27) discharges the sucked waste liquid to a waste liquid storage tank (not shown) via a drain tube or the like.
Further, on the side of the holder (23), there is a wiper blade (28) which is a wiping means made of an elastic member such as a fiber member, a foaming member or rubber for wiping the discharge surface (6a) of the inkjet head (6). The blade arm (29) is attached to an arm (29) and is pivotally supported so as to be swung by rotation of a cam that is turned by a driving means (not shown).

  Next, the ink cartridge (7) will be described with reference to FIGS. Here, FIG. 2 shows an external perspective view of the ink cartridge before loading into the recording apparatus of FIG. 1, and FIG. 3 shows a front sectional view of the ink cartridge.

  As shown in FIG. 3, the ink cartridge (7) includes an ink absorber (42) that absorbs ink of a required color in a cartridge body (41). The cartridge body (41) is formed by adhering or welding an upper lid member (44) to an upper opening of a case (43) having a wide opening at the upper portion, and is made of, for example, a resin molded product. The ink absorber (42) is made of a porous material such as a urethane foam, and after being compressed and inserted into the cartridge body (41), the ink is absorbed.

  An ink supply port (45) for supplying ink to the recording head (6) is formed at the bottom of the case (43) of the cartridge body (41), and a seal ring (45) is formed on the inner peripheral surface of the ink supply port (45). 46). The upper lid member (44) has an air opening (47). Then, the cartridge body (41) is closed with the ink supply port (45) in a state before being loaded, and at the same time the case ( A cap member (50) is attached to prevent the ink 43 from being compressed and deformed due to the compression deformation of 43).

Further, as shown in FIG. 2, the air opening (47) is sealed by attaching a film-like sealing member (55) having an oxygen permeability of 100 ml / m ² or more to the upper lid member (44). In this way, the air opening (47) is sealed with the sealing member (55) having an oxygen permeability of 100 ml / m ² or more, so that the ink cartridge (7) is made of a packaging member such as a non-permeable aluminum laminate film. By wrapping in a reduced pressure state, gas is contained in the ink due to the atmosphere in the space (A) (see FIG. 3) that is formed between the ink absorber (42) and the cartridge body (41) when the ink is filled. Even when dissolved, the air in the ink is discharged to the space between the packaging member outside the cartridge body (41) having a high degree of vacuum through the seal member (55), and the degree of deaeration of the ink is improved.

  FIG. 4 shows an example of the configuration of a recording cartridge (recording unit) provided with a recording liquid storage unit storing the recording liquid of the present invention and a head unit for discharging recording droplets. The recording unit will be described below.

  The recording unit (30) is of a serial type, and includes a head (6), an ink tank (33) containing an aqueous recording liquid (ink) supplied to the head (6), and the ink tank (33). ) And a lid member (34) for sealing the inside of the main part.

  The head (6) of the recording unit (30) is formed with a number of nozzles (32) for discharging an aqueous recording liquid. The recording liquid is guided from the ink tank (33) to a common liquid chamber (not shown) via an ink supply pipe (not shown), and the nozzle is set according to an electric signal from the recording apparatus main body input from the electrode (31). (32). This type of recording unit (30) has a structure suitable for a head of a type that can be manufactured at low cost, a head called a thermal method or a bubble method, which uses thermal energy as a driving power source. The recording liquid of the present invention improves the wettability to a thermal element in a recording method such as bubble or thermal method, so that even when added in a small amount, ejection stability and frequency stability can be obtained, and safety is also high. Is very suitable.

  Here, the serial type ink jet recording apparatus as described above has been described, but the aqueous recording liquid of the present invention has a density equal to or about a fraction of the target image resolution in an arbitrary arrangement such as a staggered nozzle. It is also possible to apply the present invention to a recording apparatus having a so-called line head, which is integrated in an array and arranged more than the width of the recording medium. In addition, the recording apparatus here may be an apparatus having a complex function in combination with a fax machine, a scanner, a telephone, or the like as well as a PC or a digital camera output printer.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to a present Example. In addition, the number of parts in an Example represents a weight part. Inks were prepared according to the formulations of Examples 1 to 6 in Table 1 below, stirred for 2 hours, adjusted to the pH indicated with lithium hydroxide, filtered through a membrane filter having a pore size of 1.2 μm, and inks (a) to ( f) was obtained. Moreover, the prescription which remove | excluded only hypophosphite from Examples 1-6 was made into Comparative Examples 1-6, and the ink (g)-(l) prepared by the same operation was obtained.

Pigment dispersion (A-1)
First, a pigment dispersion was prepared and mixed according to the following formulation, this mixture was placed in a 1 liter vessel, 900 g of zirconia beads having a diameter of 0.7 mm were added, and the mixture was dispersed for 20 hours in a batch tabletop sand mill manufactured by Campe. Obtained.
Pigment Red 122 30 parts (FASTOGEN SUPER MAGENTA RG manufactured by Dainippon Ink, Inc.)
30 parts of styrene-acrylic acid copolymer aqueous ammonium solution (20%) (John Crill 679 manufactured by Johnson Polymer Co., Ltd.)
Glycerin 10 parts Ion-exchanged water 130 parts

Pigment dispersion (A-2)
The pigment dispersion (A-2) was obtained in the same manner as in the pigment dispersion (A-1).
Pigment Blue 15: 3 30 parts (LIONOL BLUE FG-7351 manufactured by Toyo Ink Co., Ltd.)
6 parts of polyoxyethylene lauryl ether sulfate triethanolammonium (NICOLL SBL-4T manufactured by Nikko Chemicals)
Glycerin 10 parts Ion-exchanged water 154 parts

Pigment dispersion (A-3)
CAB-0-JET300 manufactured by Cabot Corporation (self-dispersing black pigment, solid content 15%, average particle size 106 nm)

Pigment dispersion (A-4)
IJX-266 (self-dispersing magenta pigment, solid content 10%, average particle size 109.5 nm) manufactured by Cabot Corporation

Dye aqueous solution (A-5)
Durasyn Brilliant Red F3B-SF Liquid (reactive monoazo dye) manufactured by Clariant Japan

Water-soluble organic solvent species (B-1) Diethylene glycol (B-2) 1,3-butanediol (B-3) Triethylene glycol (B-4) Tetraethylene glycol and propylene glycol (1: 1)
(B-5) Dipropylene glycol and thiodiglycol (1: 1)
(B-6) Ethylene glycol and 1,5-pentanediol (1: 1)

Diol compound (C-1) 2-n-butyl-2-ethyl-1,3-propanediol (C-2) 2,4-diethyl-1,5-pentanediol (C-3) 2-ethyl-1 , 3-Hexanediol (C-4) 2,2,4-trimethyl-1,3-pentanediol

Hypophosphorous acid compound (D-1) Sodium hypophosphite (D-2) Potassium hypophosphite (D-3) Ammonium hypophosphite (D-4) Hypophosphorous acid aqueous solution 8 g of diethanolamine was added and stirred well.
(D-5) 55 g of an aqueous choline solution (choline content 15%) neutralized with carbonic acid was added to 100 g of a 5% aqueous solution of hypophosphorous acid and stirred well.

  The pH was measured after the inks (a) to (l) were stored in a sealed state at 70 ° C. for 3 weeks. Also, inks (a) to (l) are filled in a black cartridge of an EPSON ink jet printer EM-900C, vacuum degassed, printed by an EPSON ink jet printer EM-900C, and 1 at room temperature with the cartridge attached. After standing for a week, reprinting was performed, and then a clogging pattern built in the printer driver was printed to evaluate the ejection stability. Table 2 summarizes the results.

FIG. 2 is a schematic front view showing an example of the structure of a mechanical part of a serial type ink jet recording apparatus equipped with an ink cartridge containing the aqueous recording liquid of the present invention. FIG. 2 is an external perspective view of an ink cartridge before being loaded into the recording apparatus illustrated in FIG. 1. FIG. 3 is a front sectional view of the ink cartridge shown in FIG. 2. FIG. 2 is an external perspective view of a recording unit (an ink cartridge integrated with a head) before being loaded into the recording apparatus illustrated in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Side plate 2 Side plate 3 Main support guide rod 4 Sub support guide rod 5 Carriage unit 6 Head 6a Discharge surface (nozzle surface)
7 Ink Cartridge 7y Ink Cartridge 7m Ink Cartridge 7c Ink Cartridge 7k Ink Cartridge 8 Main Scanning Motor 9 Drive Pulley (Drive Timing Pulley)
10 Driven pulley (idler pulley)
11 Timing belt 12 Bottom plate 13 Sub frame 14 Sub frame 15 Transport roller 16 Paper 17 Sub scanning motor 18 Gear 19 Gear 21 Sub system 22 Cap means 23 Holder 24 Link member 25 Engaging portion 26 Suction tube 27 Suction pump 28 Wiper blade 29 Blade Arm 30 Recording unit 31 Electrode 32 Nozzle 33 Ink tank 34 Lid member 41 Cartridge body 42 Ink absorber 43 Case 44 Upper lid member 45 Ink supply port 46 Seal ring 47 Atmospheric opening 50 Cap member 55 Seal member A Space

Claims (12)

An aqueous recording liquid comprising at least a colorant, water, a water-soluble organic solvent, and further containing hypophosphite. The aqueous recording liquid according to claim 1, wherein the pH of the recording liquid is 6.5 to 11. 3. The aqueous recording liquid according to claim 1, wherein the content of the hypophosphite is 0.01 to 3.0% by weight with respect to the entire recording liquid. The aqueous recording liquid according to any one of claims 1 to 3, wherein the hypophosphite is a sodium or potassium salt. The aqueous recording liquid according to any one of claims 1 to 3, wherein the hypophosphite is a salt of inorganic ammonia. The aqueous recording liquid according to any one of claims 1 to 3, wherein the hypophosphite is a salt of an organic amine selected from monoethanolamine, diethanolamine, and triethanolamine. The aqueous recording liquid according to any one of claims 1 to 3, wherein the hypophosphite is a salt of tetramethylammonium, tetraethylammonium and hydroxyethyltrimethylammonium organic ammonium. The water-soluble organic solvent of the recording liquid is glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-butanediol, 2,3-butanediol, 1,4-butane Diol, 1,5-pentanediol, tetraethylene glycol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, polyethylene glycol, 1,2,4-butanetriol, 1,2,6-hexane At least one water-soluble organic solvent selected from triol, thiodiglycol, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone It is characterized by containing The aqueous recording liquid according to any one of claims 1 to 7. The recording liquid is further 2-n-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2,2,4 9. The aqueous recording liquid according to claim 1, wherein the aqueous recording liquid contains one or two diol compounds selected from trimethyl-1,3-pentanediol. The aqueous composition according to any one of claims 1 to 9, wherein the colorant is a pigment dispersed in a number average particle system of 20 to 150 nm with a polymer dispersant or a surfactant, and is used for inkjet recording. Recording liquid. 10. The aqueous recording liquid according to claim 1, wherein the colorant is a self-dispersing pigment having a number average particle size of 20 to 150 nm having a hydrophilic group on the surface, and is used for ink jet recording. . 12. A recording method comprising forming an image on a recording medium by discharging and flying the aqueous recording liquid according to claim 1 as droplets from a fine discharge port.

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