JP2007197483A - Recording liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make an improvement in fixing properties of a pigment compatible with shortening of drying time. <P>SOLUTION: The recording liquid comprises the pigment, a water-soluble organic resin compound and a solvent containing water and a water-soluble organic solvent. At least one of an organic amine salt of a styrene-acrylic acid copolymer and an organic amine salt of a styrene-α-methylstyrene-acrylic acid copolymer is used as the water-soluble organic resin compound. Furthermore, the water-soluble organic resin compound is contained in an amount of 0.3-2.0 times the content of the pigment. At least a dihydric alcoholic solvent having no ether bond is used as the water-soluble organic solvent. In addition, the water-soluble organic solvent is contained in an amount of 5-20 wt.%. The liquidity of the recording liquid is alkaline. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a recording liquid attached to an object in order to perform recording on the object.

  As an apparatus for ejecting liquid, there is an ink jet type printer that records an image or characters by ejecting a recording liquid, so-called ink, from an ink ejection head onto a recording paper as an object. This ink jet printer has advantages such as low running cost, miniaturization of the apparatus, and easy colorization of printed images.

  Ink jet recording methods for ejecting ink from the ink ejection head include, for example, a deflection method, a cavity method, a thermo jet method, a thermal ink jet method, a slit jet method, a spark jet method, and various operations represented by these. According to the principle, the ink is made into fine droplets and ejected from the ejection port of the ink ejection head, so-called nozzle, and landed on the recording paper to record images, characters, and the like.

  Incidentally, inks used in such an ink jet recording system include those using water-soluble dyes as pigments and those using pigments. In general, an ink using a water-soluble dye as a coloring matter is excellent in long-term storage stability, but has a problem in water resistance and light resistance, and a printed image may be deteriorated. On the other hand, inks using pigments as pigments are very promising because they are excellent in water resistance and light resistance, and can obtain high image quality without bleeding, and many proposals have been made and put to practical use. ing.

  Specifically, as a pigment-based ink, for example, Patent Document 1 proposes an ink made of an aqueous medium containing a pigment, a polymer dispersant, and a nonionic surfactant, and Patent Document 2 and Patent Document 3 disclose. It is proposed to use AB or BAB block copolymer as a pigment dispersant, and Patent Document 4 proposes to use a specific pigment, a water-soluble organic resin, a solvent, or the like.

  By the way, in pigment-based inks, images and characters are formed on the recording paper by fixing the pigment in a fine particle state on the recording paper. As a result, the image quality and the quality of characters may deteriorate. In addition, in the case of pigment-based ink, the time until the pigment is not lost from the recording paper even when the image or characters are rubbed, in other words, the time until the ink is dried and the pigment is fixed, is printed. When another object is stacked on the recording paper, the pigment may be transferred to the other object, or the pigment may fall off from the recording paper.

  In such a pigment-based ink, a resin is generally added to fix the pigment on the recording paper. In addition to improving the fixability of the pigment, the resin to be added needs to be easily dissolved in the ink and do not hinder the ejection of the ink.

  In addition, in the case of pigment-based ink, even if resin is added to improve the fixability of the pigment to the recording paper, it is difficult to shorten the time until the pigment is fixed on the recording paper, so-called drying time.

  In other words, with pigment-based inks, the pigment is strongly fixed to the recording paper so that the pigment is not lost even when the image or characters are rubbed, and the time until the pigment is fixed on the recording paper is shortened (drying time). Is the biggest challenge.

Japanese Patent Laid-Open No. 56-147871 US Pat. No. 5,085,698 US Pat. No. 5,221,334 US Pat. No. 5,172,133

  The present invention provides a recording liquid capable of achieving both improvement in the fixability of a pigment to an object and reduction in the time required for fixing the pigment.

  A recording liquid according to the present invention includes a solvent that is attached to an object for recording on the object and includes at least water and a water-soluble organic solvent, a pigment dispersed in the solvent, and a styrene-acrylic acid copolymer. And at least one water-soluble organic resin compound selected from organic amine salts of styrene-α-methylstyrene-acrylic acid copolymer, and the water-soluble organic solvent has at least an ether bond Containing a dihydric alcohol solvent not containing water, and containing the dihydric alcohol solvent in the range of 5 wt% to 20 wt%, and the water-soluble organic resin compound is 0.3 times the weight ratio to the pigment. It is contained in a range of ˜2 times, and the liquidity is alkaline.

  According to the present invention, at least one water-soluble organic compound selected from an organic amine salt of a styrene-acrylic acid copolymer and an organic amine salt of a styrene-α-methylstyrene-acrylic acid copolymer with respect to the pigment. By containing the resin compound in a weight ratio of 0.3 to 2 times, the fixability of the pigment can be improved, and the loss of the pigment fixed on the object can be suppressed. Further, according to the present invention, as a solvent for dispersing the pigment and the water-soluble organic resin compound, at least a dihydric alcohol solvent having no ether bond is contained in the range of 5 wt% to 20 wt%. The time until the pigment is fixed to the object, that is, the so-called drying time can be shortened.

  That is, according to the present invention, a water-soluble organic resin compound that improves the fixability of the pigment and a dihydric alcohol solvent that does not have an ether bond that shortens the drying time are selected, and the content thereof is optimized. Therefore, both the fixability of the pigment and the shortening of the drying time can be achieved.

  Hereinafter, the recording liquid to which the present invention is applied will be described. The recording liquid to which the present invention is applied is, for example, the ink i of the ink jet printer apparatus 1 (hereinafter referred to as the printer apparatus 1) shown in FIG. The printer device 1 using the ink i is a line type printer device in which nozzles for ejecting the ink i are provided across the width direction of the recording paper P, and printing is performed for each column across the width direction of the recording paper P. The serial type in which the ink ejection head that ejects the ink i moves in the width direction of the recording paper P and performs printing for one row by performing printing for each row in the width direction of the recording paper P. The printing speed is faster than that of the printer apparatus, and the discharge interval of the recording paper P is also shorter. The ink i to which the present invention is applied shortens the drying time, so that even when it is used in the line-type printer apparatus 1 in which the discharge interval of the printed recording paper P is short, the discharged recording paper It is possible to prevent the occurrence of such a problem that the pigment of the recording paper P discharged first is transferred to P and the quality of images and characters is deteriorated. Further, in the printer device 1 using this ink i, since the fixability of the pigment is good, the pigment is not lost from the recording paper P, the color loss of the image and characters can be prevented, and the quality of the image and characters is reduced. Can be prevented. First, the ink i to which the present invention is applied will be described.

  The ink i contains a pigment as a pigment, a solvent containing at least water and a water-soluble organic solvent in which the pigment is dispersed, and a water-soluble organic resin compound. The water-soluble organic solvent contains at least a dihydric alcohol solvent having no ether bond.

  Specifically, any of organic pigments and inorganic pigments can be used as the pigment contained as the coloring matter. Examples of black pigments include carbon black pigments such as furnace black, lamp black, acetylene black, and channel black. In addition to black, three primary color pigments such as cyan, magenta and yellow, specific color pigments such as red, green, blue, brown and white, metallic luster pigments such as gold and silver, and colorless or light body pigments Also, plastic pigments can be used.

  Specific examples of black pigments include Raven7000, Raven5750, Raven5250, Raven5000 ULTRAII, Raven3500, Raven2000, Raven1250, Raven1055, Raven10, Raven10, Raven10, Raven10, Raven1550, Raven1190, Raven1190, Raven1190, Raven1190 and Raven1190. Regal 400R, Regal 330R, Regal 660R, Mogu L, Black Pearls L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monar ch 1400, Dekussa Co., Ltd. of Color Black FW1, Color Black FW2, Color Black FW2V, Color Black 18, Color Black FW200, Color Black S150, Color Black S160, Color BlackS170, Printex35, PrintexU, PrintexV, Printex140U, Printex140V, Special Black6 , Special Black 5, Special Black 4A, Special Black 4, No. manufactured by Mitsubishi Chemical Corporation. 25, no. 33, no. 40, no. 47, no. 52, no. 900, no. 2300, MCF-88, MA600, MA7, MA8, MA100, and the like, and any one or more of these may be used in combination.

  Examples of cyan pigments include C.I. I. Pigment Blue-1, C.I. I. Pigment Blue-2, C.I. I. Pigment Blue-3, C.I. I. Pigment Blue-15, C.I. I. Pigment Blue-15: 1, C.I. I. Pigment Blue-15: 3, C.I. I. Pigment Blue-15: 34, C.I. I. Pigment Blue-16, C.I. I. Pigment Blue-22, C.I. I. Pigment Blue-60 and the like can be used, and any one or a combination of these can be used.

  Examples of magenta pigments include C.I. I. Pigment Red-5, C.I. I. Pigment Red-7, C.I. I. Pigment Red-12, C.I. I. Pigment Red-48, C.I. I. Pigment Red-48: 1, C.I. I. Pigment Red-57, C.I. I. Pigment Red-112, C.I. I. Pigment Red-122, C.I. I. Pigment Red-123, C.I. I. Pigment Red-146, C.I. I. Pigment Red-168, C.I. I. Pigment Red-184, C.I. I. Pigment Red-202 or the like can be used, and any one or more of these can be used in combination.

  Examples of yellow pigments include C.I. I. Pigment Yellow-1, C.I. I. Pigment Yellow-2, C.I. I. Pigment Yellow-3, C.I. I. Pigment Yellow-12, C.I. I. Pigment Yellow-13, C.I. I. Pigment Yellow-14, C.I. I. Pigment Yellow-16, C.I. I. Pigment Yellow-17, C.I. I. Pigment Yellow-73, C.I. I. Pigment Yellow-74, C.I. I. Pigment Yellow-75, C.I. I. Pigment Yellow-83, C.I. I. Pigment Yellow-93, C.I. I. Pigment Yellow-95, C.I. I. Pigment Yellow-97, C.I. I. Pigment Yellow-98, C.I. I. Pigment Yellow-114, C.I. I. Pigment Yellow-128, C.I. I. Pigment Yellow-129, C.I. I. Pigment Yellow-138, C.I. I. Pigment Yellow-151, C.I. I. Pigment Yellow-154, C.I. I. Pigment Yellow-202 or the like can be used, and any one or more of these can be used in combination.

  These pigments are preferably contained in the range of 0.5% by weight to 10% by weight, and more preferably in the range of 1% by weight to 5% by weight, based on the total amount of the ink i. When the pigment is less than 0.5% by weight with respect to the total amount of the ink i, a sufficient density cannot be obtained and the quality of images and characters is deteriorated. On the other hand, when the pigment exceeds 10% by weight with respect to the entire ink i, the fixability of the pigment may deteriorate. Therefore, when the pigment is contained in an amount of 0.5 wt% to 10 wt% with respect to the total amount of the ink i, a sufficient concentration can be obtained and deterioration of the fixability can be suppressed.

  The pigment has a particle size in the range of 30 nm to 200 nm. When the particle size of the pigment is less than 30 nm, the pigment aggregates and becomes a lump in the ink i, which may deteriorate the ejection characteristics. On the other hand, when the particle diameter of the pigment exceeds 200 nm, the primary particle size is large and the glossiness of images and characters after printing is lowered. Therefore, by setting the particle diameter of the pigment to be in the range of 30 nm to 200 nm, it is possible to prevent the false collection of the pigment and to prevent the discharge characteristics from deteriorating. Moreover, glossiness, such as an image and a character, becomes favorable by making the particle size of a pigment into the range of 30 nm-200 nm.

  Ink i, the polydispersity index is preferably adjusted to 0.3 or less, and more preferably adjusted to 0.1 or less. The polydispersity index here can be measured, for example, with a laser light scattering type particle size distribution meter manufactured by Otsuka Electronics Co., Ltd., and can be used as a measure of the dispersion state of the pigment in ink i. In the ink i, when the polydispersity index exceeds 0.3, the aggregation of the pigment remains. For example, the aggregate of the pigment clogs the nozzle 27a, and the discharge characteristics are deteriorated. And glossiness of letters and the like will be reduced.

  As described above, the ink 2 uses water as a solvent. Examples of water that can be used include pure water, ultrapure water, distilled water, and ion exchange water.

  Ink 2 is a dihydric alcohol solvent that does not have, for example, an ether bond in addition to water for the purpose of providing desired physical properties, improving dispersibility of the pigment in the solvent, and particularly reducing the drying time. Contains. Here, the drying time means that, after an image or character is formed on the recording paper P by printing, when the image or character is rubbed with a predetermined load applied, no color loss occurs, that is, transfer is performed. It is time until it disappears. The fast drying time means that the time until the transfer of images and characters after printing is eliminated is short.

  Specifically, as the dihydric alcohol solvent having no ether bond, for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 2,3-pentanediol, and the like. Any one or more are contained. Further, among the dihydric alcohol solvents having no ether bond, those having a small number of carbon atoms are preferable because they have a low viscosity and easily penetrate into the recording paper P. Since these dihydric alcohol solvents having no ether bond have a benzene ring in the same manner as the pigment, they have good dispersibility in the ink i and function as a dispersant.

  In the ink i, the dihydric alcohol solvent having no ether bond described above is preferably contained in the range of 5 wt% to 20 wt% with respect to the entire ink i. When the monohydric alcohol solvent is contained in an amount of 5% by weight to 20% by weight with respect to the whole ink i instead of the dihydric alcohol solvent, the monohydric alcohol solvent is easily vaporized, so that the viscosity of the ink i is low. It tends to be expensive. In addition, when the trihydric alcohol solvent is contained in an amount of 5% by weight to 20% by weight with respect to the entire ink i instead of the dihydric alcohol solvent, the viscosity of the ink i is high because the trihydric alcohol solvent is highly viscous. It gets too high. Therefore, a dihydric alcohol solvent having good pigment dispersibility, moderate drying properties, and low viscosity is used.

  If the content of the dihydric alcohol solvent not having an ether bond is less than 5% by weight based on the whole ink i, the pigment will precipitate when the ink i is stored for a long time. i may be deteriorated. On the other hand, when the content of the dihydric alcohol solvent not having an ether bond exceeds 20% by weight with respect to the entire ink i, the viscosity of the ink i is increased and the ejection characteristics are deteriorated, or the volatility is higher than that of water. Since the dihydric alcohol solvent having a low value is excessive, it may be difficult to shorten the drying time.

  In addition to the dihydric alcohol solvent having no water or ether bond, for example, a conventionally known organic solvent can be used in combination with the ink i.

  Specifically, examples of the organic solvent that can be used as the solvent include polyethylene alcohols such as diethylene glycol, butylene glycol, triethylene glycol, tetraethylene glycol, 1,2,6-hexanetriol, and glycerin, ethylene glycol monomethyl ether, ethylene Polyol alcohol derivatives such as glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, ethylene oxide adduct of diglycerin, pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, triethanol Nitrogen-containing solvents such as ethanol, alcohols such as ethanol, isopropyl alcohol, butyl alcohol, benzyl alcohol, sulfur-containing solvents such as thiodiethanol, thiodiglycerol, sulfolane, dimethyl sulfoxide, propylene carbonate, ethylene carbonate, etc. Any one or more of these can be included.

  The water-soluble organic resin compound that is dispersed or dissolved in these solvents can increase the dispersibility of the pigment in the solvent and can improve the fixability of the pigment to the recording paper P.

  Specifically, examples of the water-soluble organic resin compound include an organic amine salt of a styrene-acrylic acid copolymer and an organic amine salt of a styrene-α-methylstyrene-acrylic acid copolymer. The ink i contains one or more of an organic amine salt of a styrene-acrylic acid copolymer and an organic amine salt of a styrene-α-methylstyrene-acrylic acid copolymer. Ink i contains one or more of organic amine salt of styrene-acrylic acid copolymer and organic amine salt of styrene-α-methylstyrene-acrylic acid copolymer. After the ink has landed and dried, the pigment is fixed on the recording paper P without dropping off from the recording paper P even when water or the like comes into contact with the image or characters.

  As an organic amine for forming an organic amine salt of a styrene-acrylic acid copolymer or an organic amine salt of a styrene-α-methylstyrene-acrylic acid copolymer, the fixability of the pigment to the recording paper P is appropriately increased, and the nozzle Monoethanolamine and diethanolamine, which can withstand the practical use of drying, are preferred.

  Moreover, the boiling point of the organic amine used as a counter ion to the styrene-acrylic acid copolymer and the styrene-α-methylstyrene-acrylic acid copolymer is preferably 150 ° C. or higher and 300 ° C. or lower. When the boiling point of the organic amine is less than 150 ° C., the organic amine component is easily volatilized from the ink i on the nozzle surface, and the water-soluble organic resin compound compound is insolubilized by the volatilization of the amine, which may cause clogging of the nozzle. On the other hand, when the boiling point of the organic amine is 300 ° C. or higher, the molecular weight of the organic amine is large, and the viscosity increases remarkably when used for neutralizing the acid of the water-soluble organic resin compound compound. Absent. Monoethanolamine has a boiling point of 171 ° C. and diethanolamine has a boiling point of 269 ° C., which can appropriately enhance the fixability of the pigment to the recording paper P described above and can practically withstand drying of the nozzle.

  In addition, when the sodium salt of a styrene-acrylic acid copolymer and a styrene-α-methylstyrene-acrylic acid copolymer is used, there is a possibility that images, characters, and the like may become cloudy when the ink i is dried. . On the other hand, since organic amine salts have a high boiling point, images and characters are not clouded, and high-quality images and characters can be maintained.

  Further, in the water-soluble organic resin compound, for example, the above-described styrene-acrylic acid copolymer or styrene-α-methylstyrene-acrylic acid copolymer is appropriately copolymerized with, for example, a monomer having a polyoxyethylene group or a hydroxyl group. It is also possible. Furthermore, the above-described styrene-acrylic acid copolymer and styrene-α-methylstyrene-acrylic acid copolymer have increased affinity with pigments having acidic functional groups on the surface, and the dispersion of pigments in ink i For example, a monomer having a cationic functional group, such as N, N-dimethylaminoethyl methacrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminomethacrylamide, N, , N-dimethylaminoacrylamide, N-vinyl pyrrole, N-vinyl pyridine, N-vinyl pyrrolidone, N-vinyl imidazole and the like can be appropriately copolymerized.

  The content of the water-soluble organic resin compound in the ink i is preferably in the range of 0.3 to 2 times by weight with respect to the pigment, and 0.5 to 1 to 1 by weight with respect to the pigment. More preferably, it is in the range of 2 times.

  When the content of the water-soluble organic resin compound is less than 0.3 times by weight with respect to the pigment, it is difficult to improve the fixability of the pigment to the recording paper P. On the other hand, when the content of the water-soluble organic resin compound exceeds twice the weight ratio with respect to the pigment, in addition to saturation of the effect of enhancing the fixability of the pigment to the recording paper P, the ink i There is a possibility that the viscosity is increased and the ejection characteristics are deteriorated. Therefore, by defining the content of the water-soluble organic resin compound as 0.3 to 2 times by weight with respect to the pigment, the water-soluble organic resin compound contained according to the amount of the pigment adhering to the recording paper P Therefore, the water-soluble organic resin compound can appropriately act on the pigment, and the fixability of the pigment to the recording paper P can be appropriately enhanced.

  In addition, the water-soluble organic resin compound described above preferably has a weight average molecular weight of 2000 to 10,000, and more preferably a weight average molecular weight of 3000 to 8000. When the weight average molecular weight of the water-soluble organic resin compound is less than 2000, it is difficult to maintain the fixability of the pigment. When the weight average molecular weight of the water-soluble organic resin compound exceeds 10,000, it becomes difficult to discharge from the nozzle 27a.

  Furthermore, the water-soluble organic resin compound is more preferably neutralized by 50% or more with respect to the acid value of the styrene-acrylic acid copolymer and the styrene-α-methylstyrene-acrylic acid copolymer described above, More preferably, the acid value of the styrene-acrylic acid copolymer and the styrene-α-methylstyrene-acrylic acid copolymer is neutralized by 80% or more.

  Furthermore, as the water-soluble organic resin compound, those having a structure and a composition ratio of the hydrophobic portion and the hydrophilic portion that are preferable from among combinations of pigments and solvents are used.

  Furthermore, the water-soluble organic resin compound contains a styrene-acrylic acid copolymer and a styrene-α-methylstyrene-acrylic acid in order to improve the balance of ensuring solubility in ink i and water resistance after printing. The acid value of the copolymer is preferably in the range of 100 to 250.

  In addition, in ink i, in addition to the above-described pigment, a solvent containing at least a divalent alcohol solvent having no ether bond, a water-soluble organic resin compound, a dihydric alcohol solvent having no ether bond and a water-soluble organic solvent. A conventionally known surfactant or the like that can be expected to improve wettability with respect to the recording paper P, an antifoaming effect, or the like can be added as long as the effect of the resin compound is not impaired.

  Examples of the surfactant that can be added to the ink i include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and the like, and one or more of these can be used. .

  Specifically, as an anionic surfactant, for example, alkylbenzene sulfonate, alkylphenyl sulfonate, alkyl naphthalene sulfonate, higher fatty acid salt, higher fatty acid ester sulfate ester salt, higher fatty acid ester sulfonate salt, Examples thereof include sulfate esters and sulfonates of higher alcohol ethers, higher alkyl sulfosuccinates, higher alkyl phosphate esters, phosphate esters of higher alcohol ethylene oxide adducts, and any one or more of these. Can be mixed and used. In particular, anionic surfactants include, for example, dodecyl benzene sulfonate, keryl benzene sulfonate, isopropyl naphthalene sulfonate, monobutyl phenyl phenol monosulfonate, monobutyl biphenyl sulfonate, monobutyl biphenyl sulfone. It is preferable to use acid salts, dibutylphenylphenol disulfonate, and the like.

  Examples of the cationic surfactant include tetraalkylammonium salts, alkylamine salts, benzalkonium salts, alkylpyridium salts, imidazolium salts, and the like. Examples thereof include dihydroxyethyl stearylamine, 2-heptadecenyl-hydroxyethylimidazoline. , Lauryldimethylbenzylammonium chloride, cetylpyridinium chloride, stearamide methylpyridium chloride, and the like, and any one or more of them can be used in combination.

  Nonionic surfactants include, for example, polypropylene glycol ethylene oxide adducts, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan Fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid alkylolamide, acetylene glycol, oxyethylene adduct of acetylene glycol, aliphatic alkanolamide, glycerin ester, sorbitan ester, etc., any one or more of these Can be mixed and used.

  Examples of amphoteric surfactants include (alanine, imidazolium betaine, amidopropyl beadine, aminodipropionate), and any one or more of these can be used in combination. It is.

  As the surfactant, in addition to the above-mentioned anionic surfactant, cationic surfactant, and nonionic surfactant, for example, a silicone-based surfactant such as polysiloxane oxyethylene adduct, and perfluoroalkylcarboxylic acid Fluorine surfactants such as salts, perfluoroalkyl sulfonates, and oxyethylene perfluoroalkyl ethers, and biosurfactants such as splicrisporic acid, rhamnolipid, and lysolecithin can also be used.

  Of the above-mentioned surfactants, polypropylene glycol / ethylene oxide adducts, acetylene glycol oxyethylene adducts, polyoxyethylene alkyl ethers and the like are particularly preferably used for the reason of the surface active effect (reduction in surface tension).

  The content of the surfactant in the ink i is preferably less than 10% by weight relative to the total amount of the ink i, and more preferably in the range of 0.01% by weight to 5% by weight. .

  When the surfactant is not contained in the ink i or the content thereof is less than 0.01% by weight, it is difficult to obtain the effect of the surfactant such as improvement of wettability and defoaming. Become. On the other hand, when the surfactant content exceeds 10% by weight, the effect of the surfactant is saturated.

  In addition, the ink i has, for the purpose of adjusting conductivity and pH, for example, compounds of alkali metals such as potassium hydroxide, sodium hydroxide, lithium hydroxide, ammonium hydroxide, triethanolamine, diethanolamine, ethanolamine, Nitrogenous compounds such as 2-amino-2-methyl-1-propanol, alkaline earth metal compounds such as calcium hydroxide, acids such as sulfuric acid, hydrochloric acid and nitric acid, strong acid and weak alkali salts such as ammonium sulfate, etc. Can be added.

  Furthermore, in addition to the materials described above, the ink i has, for example, polyethyleneimine, polyamines, polyvinylpyrrolidone, polyethylene glycol, ethylcellulose, carboxymethylcellulose and the like for the purpose of stabilizing physical properties and stabilizing ejection characteristics. Cellulose derivatives, polysaccharides and their derivatives, other water-soluble polymers, acrylic polymer emulsions, polymer emulsions such as polyurethane emulsions, cyclodextrins, macrocyclic amines, dendrimers, crown ethers, urea and its derivatives, acetamide, etc. added You can also

  Furthermore, the ink i includes, for example, a pH buffer, an antioxidant, an antifungal agent, a viscosity modifier, a conductive agent, an ultraviolet absorber, a chelating agent, a water-soluble dye, a disperse dye, an oil-soluble dye, and the like. Can also be added.

  The ink i having the above configuration is prepared by a conventionally known ink preparation method. Specifically, for ink i, for example, a predetermined amount of pigment is added to an aqueous solution containing a predetermined amount of a polymer dispersant, sufficiently stirred, and then dispersed using a disperser to remove coarse particles by centrifugation or the like. Further, a predetermined solvent such as a dihydric alcohol solvent having no ether bond, a water-soluble organic resin compound, a surfactant and the like are added, and the mixture is stirred, mixed and filtered. Further, a pulverization step of finely pulverizing the pigment particles may be provided before the dispersion step of dispersing the pigment. Alternatively, after mixing a predetermined solvent such as a dihydric alcohol having no ether bond, a water-soluble organic resin compound, etc., a pigment may be added and dispersed using a disperser.

  Dispersers include, for example, colloid mill, flow jet mill, thrasher mill, high speed disperser, ball mill, attritor, sand mill, sand grinder, ultra fine mill, Eiger motor mill, dyno mill, pearl mill, agitator mill, coball mill, 3 Examples thereof include a roll, two rolls, an extruder, a kneader, a microfluidizer, a laboratory homogenizer, and an ultrasonic homogenizer, and these may be used alone or in combination. Further, in order to prevent inorganic impurities from being mixed into the ink i, it is preferable to carry out the dispersion step with a microfluidizer or an ultrasonic homogenizer that does not use a dispersion medium, rather than a ball mill that uses alumina balls or the like as the dispersion medium.

  The ink i prepared as described above is rendered alkaline by adding, for example, the pH adjusting agent described above. In the ink i, by making the liquid property alkaline, the water-soluble organic resin compound does not precipitate, the physical properties of the ink i are stabilized, the nozzle sheet 27 of the ink discharge head 23 formed of a metal thin film such as nickel plating, etc. It can also prevent corrosion.

  In such an ink i, among alkalis, a pH of 7 to 11 is preferable, and a pH close to neutral is more preferably 7 to 9. When the pH of the ink i is less than 7, it becomes difficult to dissolve the water-soluble organic resin compound in the ink i, and the water-soluble organic resin compound is precipitated in the ink i to deteriorate the discharge characteristics. There is a fear. On the other hand, when the pH of the ink i exceeds 11, the ink i becomes too strong and the physical properties of the ink i are not stable, or a nozzle 27a described later is provided, and is formed of a metal thin film such as nickel plating. There is a risk of causing problems such as corrosion of the nozzle sheet 27 and the like.

  In the ink i obtained as described above, either an organic amine salt of a styrene-acrylic acid copolymer or an organic amine salt of a styrene-α-methylstyrene-acrylic acid copolymer having high affinity with the pigment is used. When one or a plurality of water-soluble organic resin compounds are contained 0.3 to 2 times by weight with respect to the pigment content, the fixability of the pigment to the recording paper P can be improved, It is possible to suppress missing of the pigment that occurs when the pigment adhering to the recording paper P is rubbed.

  Further, in this ink i, one or more water-soluble organic resin compounds of a pigment and an organic amine salt of a styrene-acrylic acid copolymer or an organic amine salt of a styrene-α-methylstyrene-acrylic acid copolymer In addition to water, a dihydric alcohol solvent having an appropriate drying property and not having an ether bond is contained in the range of 5% by weight to 20% by weight, so that the pigment is added to the recording paper P. Time until fixing, that is, drying time can be shortened.

  Further, in this ink i, since the liquid property is alkaline, the physical properties are stable, and the deterioration of the ejection characteristics is suppressed.

  Therefore, in this ink i, the organic amine salt of styrene-acrylic acid copolymer, the organic amine salt of styrene-α-methylstyrene-acrylic acid copolymer, or one or more water-soluble organic resin compounds and solvents By selecting a dihydric alcohol solvent having no ether bond and optimizing the content thereof, it is possible to achieve both the fixability of the pigment to the recording paper P and the shortening of the drying time. As a result, the image, characters, and the like formed using this ink i are fixed on the recording paper P immediately, and the loss of the fixed pigment is suppressed, so that the color does not fade and is in a high quality state. Can be maintained. In addition, even if another object overlaps the image or character formed using the ink i, the pigment can be prevented from being transferred to the other object.

  An ink jet printer apparatus (hereinafter referred to as a printer apparatus) 1 using the ink i will be specifically described. As shown in FIG. 1, the printer apparatus 1 includes an inkjet printer head cartridge (hereinafter referred to as a head cartridge) 2 that ejects the ink i described above onto a recording paper P that is an object, and the head cartridge 2. And an apparatus main body 3 to be mounted. The printer apparatus 1 is a so-called line type printer apparatus in which one or more nozzles are arranged in a line in the width direction of the recording paper P, that is, the arrow W direction in FIG. In the printer apparatus 1, the head cartridge 2 can be attached to and detached from the apparatus main body 3.

  First, the head cartridge 2 constituting the printer apparatus 1 will be described. The head cartridge 2 ejects the ink i described above using, for example, a heating resistor using an electrothermal conversion type as a pressure generating element, and causes the ink i to land on the main surface of the recording paper P. As shown in FIGS. 2 and 3, the head cartridge 2 is mounted with an ink cartridge 11 containing ink i. The ink cartridge 11 includes an ink cartridge 11y for yellow ink i, an ink cartridge 11m for magenta ink i, an ink cartridge 11c for cyan ink i, and an ink cartridge 11k for black ink i for each color. The ink cartridge 11 is formed in a substantially rectangular shape having substantially the same dimension as the dimension in the width direction of the recording paper P. As shown in FIGS. 2 and 3, the ink cartridge 11 includes an ink supply unit 12 for supplying ink i to the cartridge main body 21 of the head cartridge 2.

  The ink supply unit 12 is provided at a substantially central portion on the lower side of the ink storage unit 12. The ink i supply unit 12 is a substantially protruding nozzle that communicates with the ink storage unit 12, and the tip of the nozzle is fitted into a connection unit 25 of the head cartridge 2 to be described later. The accommodating portion 12 and the cartridge main body 21 of the head cartridge 2 are connected. The ink supply unit 12 includes a valve mechanism, and the supply of ink i to the cartridge body 21 is adjusted by the valve mechanism.

  The head cartridge 2 to which the ink cartridge 11 is attached has a cartridge body 21 as shown in FIGS. The cartridge body 21 includes a mounting portion 22 to which the ink cartridge 11 is mounted, an ink discharge head 23 that discharges ink i, and a head cap 24 that protects the ink discharge head 23.

  A connection part 25 connected to the ink supply part 12 of the ink cartridge 11 attached to the attachment part 22 is provided at substantially the center in the longitudinal direction of the attachment part 22. The connection unit 25 includes an ink supply path that supplies the ink i to the ink discharge head 23 that discharges the ink i provided on the bottom surface of the cartridge body 21 from the ink supply unit 12 of the ink cartridge 11 mounted on the mounting unit 22. Become. The connection unit 25 adjusts the supply of the ink i from the ink cartridge 11 to the ink discharge head 23 with a valve mechanism.

  The ink discharge head 23 to which the ink i is supplied from the connection portion 25 is disposed along the bottom surface of the cartridge main body 21. In the ink discharge head 23, nozzles 27a, which will be described later, which are discharge ports for discharging the ink i supplied from the connecting portion 25 are arranged in a line substantially in the width direction of the recording paper P, that is, in the direction of arrow W in FIG. Yes. The ink ejection head 23 ejects the ink i for each nozzle line without moving in the width direction of the recording paper P when ejecting the ink i.

  As shown in FIG. 4, the ink discharge head 23 is provided with a circuit board 26 provided with an electrothermal change type heating resistor 26a and a nozzle 27a, and a nozzle sheet formed of a metal thin film such as nickel plating. 27 and a film 28 provided between the circuit board 26 and the nozzle sheet 27 form an ink flow path 29 for supplying the ink i supplied from the connecting portion 25 to each nozzle 27a. The ink flow path 29 is formed long in the direction in which the nozzles 27a are arranged in parallel, that is, in the direction of the arrow W in FIG. Thereby, in the ink discharge head 23, the ink i flows from the ink cartridge 11 through the connection portion 25 of the head cartridge 2 into the ink flow path 29, and the ink i is supplied from the ink flow path 29 to each nozzle 27a. Become.

  Further, the ink discharge head 23 is formed with an ink liquid chamber 30 surrounded by a circuit board 26, a nozzle sheet 27, and a film 28, and the heating resistor 26 a pressurizes the ink i.

  In the ink discharge head 23 configured as described above, a pulse current is supplied to the heating resistor 26a selected based on the print data for about 1 to 3 microseconds, for example. Thereby, in the ink discharge head 23, the heating resistor 26a is driven and rapidly heated. In the ink discharge head 23, when the heating resistor 26a is heated, bubbles b are generated in the ink i in contact with the heating resistor 26a, as shown in FIG. In the ink discharge head 23, as shown in FIG. 4B, the ink i is pressurized while the bubbles b expand, and the pushed ink i is discharged from the nozzle 27a in a droplet state. The ink discharge head 23 returns to the state before discharge again by discharging the ink i droplets and then supplying the ink i to the ink liquid chamber 30 through the ink flow path 29. The ink discharge head 23 discharges and prints ink i on the recording paper P by repeating the above-described operation based on the print data.

  As shown in FIG. 2, the head cap 24 for protecting the discharge surface 23a of the ink discharge head 23 closes the discharge surface 23a of the ink discharge head 23 while not discharging ink i and printing. 27a is protected from drying and the like. When performing printing, the head cap 24 moves from the bottom surface of the head cartridge 2 as shown in FIGS. 2 and 5 to expose the ejection surface 23a of the ink ejection head 23 to the outside. The head cap 24 is provided with a cleaning roller 24a for wiping off excess ink i adhering to the ejection surface 23a. The head cap 24 cleans the ejection surface 23a with the cleaning roller 24a when opening the ejection surface 23a.

  As shown in FIG. 1, the head cartridge 2 is attached to the head cartridge attachment portion 41 in the apparatus main body 3 to which the head cartridge 2 is attached. In addition, the apparatus main body 3 is attached with a paper feed tray 43 in which recording paper P before printing is stacked and stored in a paper feed port 42 provided on the lower front side. A paper discharge toilet 45 for storing the recording paper P after printing is attached to the paper port 44.

  As shown in FIG. 5, the apparatus main body 3 is provided with a paper supply / discharge mechanism 46 for transporting the recording paper P and a cap opening / closing mechanism 47 for opening / closing the head cap 24 provided on the ejection surface 23 a of the head cartridge 23. Yes.

  With the above-described configuration, the printer apparatus 1 supplies a current to be supplied to the paper supply / discharge mechanism 46, the head cap opening / closing mechanism 47, and the ink discharge head 23 based on print data input from an information processing apparatus provided outside. It is controlled by a control unit provided in a control circuit for controlling.

  Specifically, in the printer apparatus 1, first, when an instruction to start printing is given to the control unit by operating the operation button 3 a provided on the apparatus main body 3, the paper supply / discharge mechanism 46 and the head are controlled by a control signal from the control unit. The cap opening / closing mechanism 47 is driven, and printing is possible as shown in FIG.

  The printer apparatus 1 moves the head cap 24 to the front side where the paper feed tray 43 and the paper discharge tray 44 are provided with respect to the head cartridge 2 by the head cap opening / closing mechanism 47. As a result, the printer 1 is configured such that the nozzles 27 a provided on the ejection surface 23 a of the ink ejection head 23 are exposed to the outside, and the ink i can be ejected.

  Further, the printer 1 pulls out the recording paper P from the paper supply tray 43 by the paper supply roller 51 by the paper supply / discharge mechanism 46 and only one sheet of recording paper P by the pair of separation rollers 52a and 52b rotating in opposite directions. Pull out. Then, the printer apparatus 1 conveys the drawn recording paper P to a reversing roller 53 provided on the back side of the apparatus main body 3, and the reversing roller 53 reverses the recording paper P to the front side of the apparatus main body 3 to discharge ink. The recording paper P is transported to a transport belt 54 provided at a position facing the ejection surface 23 a of the head 23. In the printer apparatus 1, the recording paper P conveyed to the conveying belt 54 is supported at a predetermined position by the platen plate 55, so that the recording paper P faces the ejection surface 23 a.

  Next, the printer apparatus 1 supplies a driving current to the plurality of heating resistors 26a provided in the ink discharge head 23 based on the print data control signal to heat the heating resistors 26a. As shown in FIG. 4, the printer device 1 heats the heating resistor 26a to apply the ink i described above from the nozzle 27a to the recording paper P conveyed to a position facing the ejection surface 23a. The ink is discharged in a state, and images, characters, etc. are printed.

  When the ink droplets of ink i are ejected from the nozzles 27 a, the printer device 1 supplies the same amount of ink i as the amount of ejected ink i from the ink cartridge 11 to the ink ejection head 23 via the connection unit 25.

  Next, the printer 1 faces the conveyance belt 54 that rotates the recording paper P on which images, characters, and the like have been printed in the direction of the discharge port 44, and the conveyance belt 54. The recording paper P is sent to the paper discharge port 44 by the paper discharge roller 56 provided on the side, and the printed recording paper P is discharged to the paper discharge tray 45. In this way, the printer apparatus 1 performs printing on the recording paper P.

  As described above, since the printer 1 performs printing for each row in the width direction of the recording paper P, the printing time of one recording paper is short, and a plurality of recording papers P are discharged within a short time. The paper is discharged to the tray 44 and stacked. The ink i used in the printer apparatus 1 contains a dihydric alcohol solvent having an appropriate drying property and not having an ether bond in a range of 5 wt% to 20 wt%. The time until fixing to P (drying time) is shortened. Thus, in the printer apparatus 1, even if the recording paper P after printing is discharged to the plurality of paper discharge trays 44 in a short time, the pigment is immediately fixed on the recording paper P. It is possible to prevent the ink i of the recording paper P discharged earlier from being transferred to the paper P and prevent the quality of the image and characters of the recording paper P discharged first from deteriorating, and high quality after printing. Can be maintained.

  Further, in the printer apparatus 1, in addition to the pigment in the ink i, an organic amine salt of a styrene-acrylic acid copolymer having a high affinity with the pigment, an organic amine salt of a styrene-α-methylstyrene-acrylic acid copolymer Any one or more water-soluble organic resin compounds are contained in a weight ratio of 0.3 to 2 times the pigment, and the fixability of the pigment in the ink i to the recording paper P is improved. Even if the obtained image or character is rubbed or water is attached to the image or character, the loss of the pigment is suppressed. Thereby, in the printer apparatus 1, an image and a character are not discolored and a high quality state can be maintained.

  Further, in this printer apparatus 1, since the liquid property of the ink i is alkaline, the physical properties of the ink i are stabilized, and the water-soluble organic resin compound or the like is not precipitated, so that the discharge characteristics can be prevented from being deteriorated. Further, in the printer apparatus 1, since the liquid property of the ink i is alkaline, the nozzle sheet 27, the film 28, etc. constituting the ink discharge head 23 are not corroded.

  The ink i is not limited to use in the line-type printer apparatus 1 as described above, and a serial-type printer apparatus that performs printing for one column by moving the ink ejection head in the width direction of the recording paper P. Can also be used. Even when the ink i is used in a serial type printer, the drying time of the ink i is shortened. Therefore, the pigment of the ink i of the recording paper P that has been discharged first is transferred to the discharged recording paper P. Transfer can be prevented, and the image and characters after printing can be maintained in a high quality state. Also, the serial type printer device has good fixability of the pigment of the ink i, so that color loss due to missing of the pigment can be suppressed, and high-quality state of images and characters can be maintained.

  Hereinafter, a sample in which an ink to which the present invention is applied is actually prepared will be described.

<Sample 1>
In sample 1, C.I. having an average particle size of 110 nm as a pigment was used. I. Pigment Red-122 4 wt%, and a monoethanolamine salt (MEA in Table 1) of a styrene-acrylic acid copolymer (shown as A in Table 1) having an average weight molecular weight of 10,000 as a water-soluble organic resin compound. 1.2 wt%, 1 wt% of Orphine E1010 manufactured by Air Products as a surfactant, and ethylene glycol which is a dihydric alcohol solvent having no ether bond as a solvent (in Table 1) And 20% by weight of EG), an appropriate amount of triethanolamine as a pH adjusting agent, and a predetermined amount of ion-exchanged water as a solvent so that the total amount becomes 100% by weight, and stirred, and the pore size is 1 μm. The ink was prepared by filtration through a filtration filter. In the obtained ink, the content of the monoethanolamine salt of the styrene-acrylic acid copolymer is 0.3 times the weight ratio of the pigment content, and the polydispersity index is 0.15. The viscosity is 2.8 Pa · s, and the pH is 7.5. Moreover, although the monoethanolamine salt of a styrene-acrylic acid copolymer is formed, the boiling point of ethanolamine is 171 ° C.

<Sample 2>
In sample 2, the average particle diameter of the pigment is 120 nm, the monoethanolamine salt of the styrene-acrylic acid copolymer is 8% by weight, and the content of the monoethanolamine salt of the styrene-acrylic acid copolymer is the content of the pigment. The ink was prepared in the same manner as in Sample 1, except that the weight ratio was doubled with respect to the amount, the polydispersity index was 0.22, the viscosity was 4.5 Pa · s, and the pH was 7. 8 inks were obtained.

<Sample 3>
In Sample 3, the average particle diameter of the pigment was 135 nm, and a diethanolamine salt of a styrene-acrylic acid copolymer (denoted as DEA in Table 1) having an average weight molecular weight of 10,000 as a water-soluble organic resin compound was used. Ink was prepared in the same manner as Sample 1, and an ink having a polydispersity index of 0.28, a viscosity of 2.9 Pa · s, and a pH of 8.2 was obtained. The boiling point of diethanolamine forming the diethanolamine salt of the styrene-acrylic acid copolymer is 269 ° C.

<Sample 4>
In Sample 4, monoethanol of a styrene-α-methylstyrene-acrylic acid copolymer (shown as B in Table 1) having an average pigment particle size of 92 nm and an average weight molecular weight of 10,000 as a water-soluble organic resin compound. An ink was prepared in the same manner as in Sample 1 except that an amine salt was used, and an ink having a polydispersity index of 0.18, a viscosity of 3.2 Pa · s, and a pH of 8.5 was obtained. .

<Sample 5>
In sample 5, the ink was prepared in the same manner as in sample 4 except that the average particle size of the pigment was 115 nm, and the average weight molecular weight of the styrene-α-methylstyrene-acrylic acid copolymer was 2000. An ink having an index of 0.15, a viscosity of 2.3 Pa · s, and a pH of 8.2 was obtained.

<Sample 6>
In sample 6, the ink was prepared in the same manner as in sample 1, except that the average particle size of the pigment was 140 nm and 5 wt% of ethylene glycol, the polydispersity index was 0.21, the viscosity was 2. An ink having 0 Pa · s and a pH of 7.5 was obtained.

<Sample 7>
In Sample 7, the average particle diameter of the pigment was 120 nm, and propylene glycol (1.2-propanediol) (shown as PG in Table 1) was used as the dihydric alcohol solvent having no ether bond. Prepared an ink in the same manner as in Sample 1 to obtain an ink having a polydispersity index of 0.15, a viscosity of 3.2 Pa · s, and a pH of 8.0.

<Sample 8>
In Sample 8, Sample 1 was used except that the average particle diameter of the pigment was 150 nm and 1.3-butanediol (shown as Bu in Table 1) was used as the dihydric alcohol solvent having no ether bond. The ink was prepared in the same manner as described above to obtain an ink having a polydispersity index of 0.16, a viscosity of 2.9 Pa · s, and a pH of 8.2.

<Sample 9>
In Sample 9, Sample 1 was used except that the average particle diameter of the pigment was 60 nm and 1.5-pentanediol (indicated as Pen in Table 1) was used as the dihydric alcohol solvent having no ether bond. The ink was prepared in the same manner as described above to obtain an ink having a polydispersity index of 0.13, a viscosity of 3.0 Pa · s, and a pH of 7.9.

<Sample 10>
In Sample 10, an ink was prepared in the same manner as in Sample 1 except that a dihydric alcohol solvent having no ether bond was mixed with ethylene glycol and propylene glycol, and the polydispersity index was 0.00. An ink having a viscosity of 3.2 Pa · s and a pH of 8.5 was obtained.

<Sample 11>
In Sample 11, the ink was prepared in the same manner as Sample 1 except that the average particle diameter of the pigment was 125 nm and the diethanolamine salt of a styrene-acrylic acid copolymer was used, and the polydispersity index was 0.15. An ink having a viscosity of 2.9 Pa · s and a pH of 7.8 was obtained.

<Sample 12>
In sample 12, the ink was prepared in the same manner as in sample 1 except that the average particle diameter of the pigment was 136 nm and the average weight molecular weight of the monoethanolamine salt of the styrene-acrylic acid copolymer was 11000, and the polydispersity index was adjusted. Was 0.19, the viscosity was 4.6 Pa · s, and the pH was 7.6.

<Sample 13>
In Sample 13, the ink was prepared in the same manner as in Sample 1, except that the average particle diameter of the pigment was 132 nm, and the average weight molecular weight of the monoethanolamine salt of the styrene-acrylic acid copolymer was 1,900. Of 0.13, a viscosity of 2.3 Pa · s, and a pH of 7.8.

<Sample 14>
In sample 14, the ink was prepared in the same manner as in sample 1 except that the average particle diameter of the pigment was 145 nm and the diethylamine salt of the styrene-acrylic acid copolymer (denoted as DeA in Table 1) was used. An ink having a dispersion index of 0.15, a viscosity of 3.6 Pa · s, and a pH of 8.2 was obtained. The boiling point of diethylamine forming the diethylamine salt of the styrene-acrylic acid copolymer is 55.4 ° C.

<Sample 15>
In Sample 15, the ink was prepared in the same manner as in Sample 1 except that the average particle diameter of the pigment was 190 nm and the monoethanolamine salt of the styrene-acrylic acid copolymer was 1.1% by weight. The content of the monoethanolamine salt of the acrylic acid copolymer is 0.275 times by weight with respect to the pigment content, the polydispersity index is 0.25, and the viscosity is 3.5 Pa · s. An ink having a pH of 8.5 was obtained.

<Sample 16>
In sample 16, the average particle diameter of the pigment was 182 nm, the monoethanolamine salt of the styrene-acrylic acid copolymer was 9% by weight, and the content of the monoethanolamine salt of the styrene-acrylic acid copolymer was the content of the pigment. The ink was prepared in the same manner as in Sample 1, except that the weight ratio was 2.25 times the amount, the polydispersity index was 0.19, the viscosity was 4.3 Pa · s, and the PH was An ink of 8.5 was obtained.

<Sample 17>
In Sample 17, the average particle size of the pigment was 144 nm, and the same procedure as Sample 1 was used except that a monoethanolamine salt of polyacrylic acid (shown as C in Table 1) was used as the water-soluble organic resin compound. The ink was prepared so that the content of the monoethanolamine salt of polyacrylic acid was 0.3 times by weight with respect to the pigment content, the polydispersity index was 0.22, and the viscosity was 2.5 Pa · An ink having a pH of 7.6 was obtained.

<Sample 18>
In Sample 18, the ink was prepared in the same manner as in Sample 1 except that the average particle diameter of the pigment was 151 nm and hydroxyethyl cellulose (denoted as D in Table 1) was used as the water-soluble organic resin compound. The hydroxyethyl cellulose content is 0.3 times the weight ratio of the pigment, the polydispersity index is 0.15, the viscosity is 2.8 Pa · s, and the pH is 8. 8 inks were obtained.

<Sample 19>
In sample 19, the ink was prepared in the same manner as in sample 1 except that the average particle diameter of the pigment was 92 nm and polyvinyl acetal (shown as E in Table 1) was used as the water-soluble organic resin compound. An ink having an acetal content of 0.3 times by weight with respect to a pigment content, a polydispersity index of 0.13, a viscosity of 3.6 Pa · s, and a pH of 8.7. Obtained.

<Sample 20>
In sample 20, the ink was prepared in the same manner as in sample 1, except that the average particle diameter of the pigment was 151 nm and ethylene glycol was 4% by weight, the polydispersity index was 0.14, and the viscosity was 2. An ink having 2 Pa · s and a pH of 7.5 was obtained.

<Sample 21>
In sample 21, the ink was prepared in the same manner as in sample 1, except that the average particle size of the pigment was 126 nm and ethylene glycol was 21 wt%, the polydispersity index was 0.11, the viscosity was 2. An ink having 0 Pa · s and a pH of 7.6 was obtained.

<Sample 22>
Sample 22 was the same as Sample 1 except that the average particle diameter of the pigment was 141 nm and triethylene glycol (shown as TriEG in Table 1) was used as the dihydric alcohol solvent having no ether bond. Thus, an ink having a polydispersity index of 0.14, a viscosity of 2.5 Pa · s, and a pH of 7.9 was obtained.

<Sample 23>
In Sample 23, Sample 1 was used except that the average particle diameter of the pigment was 149 nm and 1.6-hexanediol (shown as Hex in Table 1) was used as the dihydric alcohol solvent having no ether bond. The ink was prepared in the same manner as described above to obtain an ink having a polydispersity index of 0.17, a viscosity of 3.5 Pa · s, and a pH of 7.7.

<Sample 24>
In sample 24, the pH was adjusted using acetic acid instead of triethanolamine, and the ink was adjusted in the same manner as in Example 1 except that the liquid property was acidic, and the pH was 6.9. Ink was obtained. A precipitate was formed, and it was impossible to measure the polydispersity index and the viscosity.

<Sample 25>
In sample 25, the ink was prepared in the same manner as in sample 1 except that the average particle diameter of the pigment was 142 nm and the triethanolamine salt of a styrene-acrylic acid copolymer was used, and the polydispersity index was 0.22. An ink having a viscosity of 7.2 Pa · s and a pH of 8.7 was obtained. The boiling point of triethanolamine forming the triethanolamine salt of the styrene-acrylic acid copolymer is 361 ° C.

  Next, the ink of Sample 1 to Sample 25 obtained as described above is filled in an ink cartridge, and the ink is ejected by a line-type ink jet printer device mounted on the head cartridge. So-called solid printing, in which a predetermined range was painted on paper (photo paper (glossy)) at a resolution of 600 dpi, was performed.

  The images printed with the ink of each sample were evaluated for scratching after 10 minutes of printing, scratching after 60 minutes of printing, and water resistance. In addition, the ink in the nozzles on the nozzle surface of the printer device was tested for dryness and continuous discharge.

Specifically, the scratching property was evaluated as follows. After measuring the density of an image after 10 minutes and 60 minutes from printing with a Macbeth densitometer (model: TR924), the printed image was dyed friction fastness tester (model: Daiei Science Co., Ltd.). RT-200) and rubbed 5 times at a rate of 30 reciprocations / min while applying a load of 100 g / cm ² with a cellulosic nonwoven fabric (trade name: Bencot M-3) manufactured by Ozu Sangyo Co., Ltd. Measured with a densitometer. As for the scratching property, the remaining state of the color with respect to the initial density, that is, the remaining rate of 80% or more is indicated by ◯, and the less than 80% is indicated by X.

  The water resistance was evaluated as follows. After printing, after measuring the density of the image after 24 hours with a densitometer, the printed image was immersed in pure water for 10 minutes together with the recording paper, taken out from the water, and then wiped off the moisture with a cellulose nonwoven fabric. The degree of drop was again measured with a densitometer. And as for water resistance, those with a residual rate of 80% or more are indicated by ◯, and those with less than 80% are indicated by X.

  The ink drying in the nozzle was evaluated as follows. After the nozzle surface of the ink discharge head is exposed to the atmosphere for 120 seconds, solid printing is performed, and a case where printing can be performed without any problem is indicated by a circle. Deterioration of discharge characteristics such as variations in ink landing positions and ink non-discharge The case where there existed was shown by x mark.

  The continuous discharge property was evaluated as follows. The pressure generating element was driven at a frequency of 10 kHz, and 200 million inks were continuously discharged to perform a continuous discharge test. A case where the rate of decrease in the ink ejection speed from the initial speed is within 20% is indicated by a circle, and a case where a speed decrease of 20% or more is indicated by a mark. Moreover, although there was no speed change of 20%, it was set as Δ when the initial speed was 8 m / s or less.

  Table 1 below summarizes the compositions of the water-soluble organic resin compound, the water-soluble organic solvent, and the pigment of each sample. Table 2 shows the evaluation results for each sample of scratching after printing 10, scratching after 60 minutes of printing, water resistance, ink drying in the nozzles, and continuous ejection.

  From the evaluation results shown in Table 2, Sample 1 to Sample 11 containing the water-soluble organic resin compound of the present invention having an average weight molecular weight of 2000 and 10,000 are Sample 12 containing a water-soluble organic resin compound having an average weight molecular weight of 11000. Compared with Sample 13 containing a water-soluble organic resin compound having an average weight molecular weight of 1900, it has excellent rubability after 10 minutes.

  In Sample 12, since the average weight molecular weight of the water-soluble organic resin compound exceeded 10,000, it was difficult to be discharged from the nozzle, the discharge speed was reduced, and the continuous discharge characteristics were deteriorated.

  In sample 13, since the average weight molecular weight of the water-soluble organic resin compound is less than 2000, the fixability of the pigment to the recording paper cannot be maintained, and the color residue becomes less than 80% when rubbed after 10 minutes after printing. The later evaluation of scratching properties deteriorated.

  On the other hand, Sample 1 to Sample 11 contain water-soluble organic resin compounds having an average weight molecular weight of 2000 and 10,000, so that the physical properties of the ink are stable and ink can be ejected continuously. Since the fixing property of the pigment to the recording paper is also obtained, the continuous ejection property and the scratching property after 10 minutes are excellent.

  Samples 1 to 11 containing a water-soluble organic resin compound composed of monoethanolamine salt (MEA) or diethanolamine salt (DEA) are more nozzles than sample 14 containing a water-soluble organic resin compound composed of diethylamine salt. Excellent drying evaluation.

  Since sample 14 contains a water-soluble organic resin compound composed of diethylamine salt (DeA), when the nozzle surface is exposed to the atmosphere without discharging ink, diethylamine having a boiling point of 55.4 ° C. is volatilized. Then, the water-soluble organic resin compound becomes insoluble in the ink and the water-soluble organic resin compound is precipitated. As a result, in sample 14, when ink was left without being ejected, the insoluble or solidified water-soluble organic resin compound caused problems such as non-ejection, resulting in poor evaluation of nozzle drying.

  In contrast, Sample 1 to Sample 11 contain a water-soluble organic resin compound composed of a high-boiling organic amine salt, so that the ink in the nozzle is difficult to dry and the nozzle is exposed to the atmosphere. Excellent discharge characteristics and excellent nozzle drying evaluation.

  Sample 1 in which the water-soluble organic resin compound contained in the ink is in the range of 1.2 wt% to 8 wt%, that is, 0.3 to 2 times the pigment content. -Sample 11 is superior in scratching property to Sample 15 containing 1.1% by weight of the water-soluble organic resin compound in the ink, that is, 0.275 times the pigment content. Samples 1 to 11 are excellent in scratching and continuous discharge compared to Sample 16 containing 9% by weight of a water-soluble organic resin compound, that is, 2.25 times the pigment content. .

  In Sample 15, the content of the water-soluble organic resin compound is less than 0.3 times the content of the pigment, and the content of the water-soluble organic resin compound is too small. Since it is difficult to improve the fixing property to the recording paper, the fixing property of the pigment to the recording paper cannot be improved, and the pigment is lost when the printed image is rubbed. As a result, in the sample 15, the evaluation of scratching property was deteriorated.

  Sample 16 has a water-soluble organic resin compound content more than twice that of the pigment, so that the viscosity of the ink becomes too high and the nozzle is clogged, resulting in non-ejection. Became worse. In addition, since the sample 16 contains a large amount of water-soluble organic resin compounds that easily absorb moisture, the penetration of ink into the recording paper is hindered by the water-soluble organic resin compounds, making it difficult to dry. When rubbed, the pigment was lost and the rubability after 10 minutes deteriorated.

  On the other hand, since Sample 1 to Sample 11 have a water-soluble organic resin compound content in the range of 0.3 to 2 times the pigment content, the fixability of the pigment to the recording paper is low. This improves the viscosity of the ink and does not become too high.

  In addition, an organic amine salt of a styrene-acrylic acid copolymer and a water-soluble organic resin compound of an organic amine salt of a styrene-α-methylstyrene-acrylic acid copolymer capable of improving the fixability of a pigment to a recording paper. Sample 1 to Sample 11 containing at least one kind are excellent in scratch resistance, water resistance, and continuous ejection properties as compared with Sample 17 to Sample 19 not containing these water-soluble organic resin compounds.

  In Samples 17 to 19, water-soluble organic amine salt of styrene-acrylic acid copolymer and organic amine salt of styrene-α-methylstyrene-acrylic acid copolymer capable of enhancing the fixability of the pigment to the recording paper. Since at least one organic organic resin compound is not contained, the fixability of the pigment to the recording paper is low, and the pigment is lost when the image is rubbed or immersed in water 10 minutes after printing. As a result, in Samples 17 to 19, the rubability, water resistance, and continuous discharge properties after 10 minutes deteriorated.

  In Samples 17 and 18, the monoethanolamine salt of polyacrylic acid or hydroxyethyl cellulose used as the water-soluble organic resin compound has low affinity with the pigment. The water resistance decreased. In sample 17, since the affinity between the monoethanolamine salt of polyacrylic acid and the pigment was low, the image was rubbed immediately after printing, and the pigment was lost, resulting in poor scratchability after 10 minutes. .

  In sample 19, the continuous dischargeability was worse than the poor inkjet suitability of the water-soluble organic resin compound polyvinyl acetal.

  On the other hand, in samples 1 to 11, water-soluble organic organic salt of styrene-acrylic acid copolymer and organic amine salt of styrene-α-methylstyrene-acrylic acid copolymer as water-soluble organic resin compounds. Since the resin compound is contained, the fixability of the pigment to the recording paper is improved, so that it is excellent in scratching and water resistance. In Samples 1 to 11, the water-soluble organic resin compound includes an organic amine salt of a styrene-acrylic acid copolymer and an organic amine salt of a styrene-α-methylstyrene-acrylic acid copolymer. Since it is contained, the physical properties are stable and the continuous discharge property is excellent.

  Samples 1 to 11 in which the content of ethylene glycol, which is a dihydric alcohol solvent, is 5% by weight or 20% by weight of the total ink are compared with sample 20 in which the content of ethylene glycol is 4% by weight. In addition, the nozzle drying property is excellent, and the scratching property after 10 minutes is excellent as compared with the sample 21 having a content of 21% by weight.

  In sample 20, the content of ethylene glycol is as small as 4% by weight with respect to the whole ink, so that the pigment is precipitated and the physical properties deteriorate, or the nozzle is exposed to the atmosphere without discharging the ink from the nozzle. The ink was dried and thickened, resulting in non-ejection or problems, and the evaluation of nozzle drying deteriorated.

  In sample 21, the content of ethylene glycol, which is a dihydric alcohol solvent, is 21% by weight in excess of the total ink, and ethylene glycol is less volatile than water, so it is difficult to shorten the drying time. As a result, the evaluation of scratchability after 10 minutes deteriorated.

  On the other hand, in samples 1 to 11, since the content of ethylene glycol, which is a dihydric alcohol solvent, is 5% by weight or 20% by weight with respect to the entire ink, the physical properties of the ink deteriorate. In addition, problems such as long ink drying time can be suppressed, and the nozzle drying evaluation and 10-minute scratch resistance are excellent.

  Samples 1 to 11 containing a dihydric alcohol solvent not having an ether bond are 10 minutes in comparison with Samples 22 and 23 not containing a dihydric alcohol solvent not having an ether bond. Excellent scratch resistance.

  Sample 22 contains triethylene glycol, and does not contain a dihydric alcohol solvent that does not have an ether bond that can shorten the drying time. It was.

  In sample 23, 1.6-hexanediol was used as the dihydric alcohol solvent having no ether bond, so the viscosity was high and the drying time could not be shortened. It got worse.

  On the other hand, Sample 1 to Sample 11 contain a dihydric alcohol solvent that does not have an ether bond that can shorten the drying time. Therefore, the drying time of the ink can be shortened, and the scratch resistance after 10 minutes is excellent.

  Since the sample 24 is acidic at pH 6.9, the contained water-soluble organic resin compound is precipitated and precipitated in the ink, making it difficult to eject the ink from the nozzle. Therefore, each evaluation could not be performed.

  Samples 1 to 11 using monoethanolamine or diethanolamine for neutralization of the water-soluble organic resin compound are 10 minutes compared to Sample 25 using triethanolamine for neutralization of the water-soluble organic resin compound. The subsequent rubbing property and continuous discharge property are excellent.

  Since the sample 25 used triethanolamine for neutralization of the water-soluble organic resin compound, the viscosity of the ink increased. As a result, in sample 25, it was difficult to dry the ink, the drying time was delayed, and the evaluation of scratching properties after 10 minutes was deteriorated. In Sample 25, the speed of continuous ejection was inferior due to an increase in ink viscosity.

  Compared to Sample 25, Samples 1 to 11 use monoethanolamine or diethanolamine for neutralization of the water-soluble organic resin compound, so that the viscosity of the ink does not increase and the rub and continuous discharge after 10 minutes. Excellent in properties.

  From the above, when preparing the ink, at least one or more water-soluble organic compounds are selected from the organic amine salt of styrene-acrylic acid copolymer and the organic amine salt of styrene-α-methylstyrene-acrylic acid copolymer. Select resin compounds, dihydric alcohol solvents that do not have ether bonds, and optimize the content and weight average molecular weight of water-soluble organic resin compounds, the content of dihydric alcohol solvents that do not have ether bonds, etc. It can be seen that making the ink alkaline is very important in preparing an excellent ink capable of achieving both the fixability of the pigment to the recording paper and the shortening of the drying time.

1 is a perspective view showing an ink jet printer apparatus to which the present invention is applied. It is a perspective view which shows the head cartridge with which the same inkjet printer apparatus is equipped. It is sectional drawing which shows the head cartridge. 2 is a cross-sectional view of an ink discharge head provided in the head cartridge, FIG. 1A is a cross-sectional view schematically showing a state where bubbles are generated in a heating resistor, and FIG. It is sectional drawing which shows the state which discharged | emitted. It is a see-through | perspective side view which shows the structure of the inkjet printer apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Inkjet printer apparatus, 2 Head cartridge, 3 Apparatus main body, 11 Ink cartridge, 12 Ink supply part, 21 Cartridge main body, 23 Ink discharge head, 24 Head cap, 24a Cleaning roller, 26 Circuit board, 27 Nozzle sheet, 27a Nozzle, 28 Film, 29 Ink supply path, 30 Ink chamber

Claims (5)

In the recording liquid attached to the object in order to perform recording on the object,
A solvent comprising at least water and a water-soluble organic solvent;
At least one water-soluble organic resin selected from a pigment dispersed in the solvent, an organic amine salt of a styrene-acrylic acid copolymer, and an organic amine salt of a styrene-α-methylstyrene-acrylic acid copolymer Containing a compound,
The water-soluble organic solvent includes at least a dihydric alcohol solvent having no ether bond, and the dihydric alcohol solvent is contained in a range of 5 wt% to 20 wt%.
The water-soluble organic resin compound is contained in a range of 0.3 to 2 times by weight with respect to the pigment,
A recording liquid characterized in that the liquid is alkaline.   2. The recording liquid according to claim 1, wherein the boiling point of the organic amine forming the organic amine salt is in the range of 150 to 300 [deg.] C. under 1 atmosphere.   2. The recording liquid according to claim 1, wherein the organic amine forming the organic amine salt is monoethanolamine or diethanolamine.   The recording liquid according to claim 1, wherein the water-soluble organic resin compound has a weight average molecular weight in the range of 2000 to 10,000.   The dihydric alcohol solvent having no ether bond is ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butane. It contains at least one selected from diol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, and 2,3-pentanediol. The recording liquid according to claim 1.

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