JP2008019287A - Recording liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make an improvement in fixing properties of a pigment compatible with the shortening of the drying time in relation to a recording liquid containing a water-soluble organic resin compound for improving the fixing properties of the pigment and a dihydric alcoholic solvent free of an ether bond for shortening the drying time. <P>SOLUTION: The recording liquid comprises a solvent containing at least water and a water-soluble organic solvent, a pigment and at least the one water-soluble organic resin compound selected from an organic amine salt of a styrene-maleic acid copolymer and an organic amine salt of a styrene-alkyl maleate copolymer. At least the dihydric alcoholic solvent free of the ether bond in an amount within the range of 5-20 wt.% is contained in the water-soluble organic solvent. Furthermore, the water-soluble organic resin compound is contained in an amount within the range of 0.3-2 times the content of the pigment expressed in terms of weight ratio. The liquid property is alkaline. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a recording liquid containing a water-soluble organic resin for improving the fixability of a pigment and a dihydric alcohol solvent having no ether bond for shortening the drying time.

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

  This ink jet type printer device is a method of displacing ink into fine droplets by various operating principles such as a deflection method, a cavity method, a thermo jet method, a thermal ink jet method, a slit jet method, and a spark jet method. The ink is ejected from the ejection port of the ink ejection head, so-called nozzle, and the ink is landed on the recording paper to print an image or a character.

  By the way, the ink used for such an ink jet type printer device includes those using a water-soluble dye as a coloring matter and those using a pigment. 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, characters, or the like may be deteriorated. In contrast to inks using such water-soluble dyes, inks using pigments as pigments are excellent in water resistance and light resistance, and can obtain images and characters that do not blur at a high concentration. It is very promising and many proposals have been made and put into practical use.

  Specifically, with regard to pigment-based inks, for example, Patent Document 1 below describes an ink containing an aqueous medium containing a pigment, a polymer dispersant, and a nonionic surfactant. 3 describes the use of AB or BAB block copolymer as a pigment dispersant, and Patent Document 4 describes the use of a specific pigment, a water-soluble organic resin, and a solvent.

  The pigment-based ink is required to have excellent storage stability and ejection stability when used in an ink jet printer. As a pigment-based ink with improved storage stability and ejection stability, for example, the following Patent Document 5 describes an ink containing a styrene-maleic acid copolymer and ε-caprolactam in addition to a pigment. Yes. Patent Document 6 describes one containing a styrene-maleic acid copolymer and a copper phthalocyanine pigment. Patent Document 7 describes one containing a styrene-maleic acid copolymer and a specific pigment.

  In addition, since pigment-based ink is ejected from a very small nozzle provided in the ink ejection head, it is necessary that the pigment-based ink does not cause pigment false collection or clogging. As an ink that prevents the occurrence of pigment false collection and clogging, for example, the following Patent Document 8 describes an ink containing a maleic acid monoester monomer, a styrene monomer, and vinylpyrrolidone. .

  In addition, the pigment-based ink needs to be excellent in frequency response when ejecting ink, quality of printed images and characters, and storage stability. An example of such an ink is an ink containing an ammonium salt described in Patent Document 9 below.

  The pigment-based ink as described above forms images, characters, and the like on the recording paper by fixing the pigment in a fine particle state on the recording paper. For this reason, when printing with pigment-based ink, rubbing on an image, characters, or the like may cause the pigment to be lost, resulting in blurring or the like, which may degrade the quality of the image, characters, or the like.

  In addition, the pigment-based ink is the time until the pigment is not lost from the recording paper even if it rubs an image or characters, in other words, the time until the ink dries and the pigment is fixed on the recording paper (drying time). ) Is long, and when another object is stacked on the printed recording paper, the pigment may be transferred to the other object or the pigment may fall off from the recording paper.

  The inks described in Patent Documents 5 to 9 have improved storage stability, ejection stability, pigment collection, etc., but the pigment fixing property, drying time is long, and quick drying property is improved. It is insufficient.

  Therefore, in the case of pigment-based ink, a resin is generally added to improve the fixability of the pigment to 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.

  However, with pigment-based inks, it is difficult to shorten the so-called drying time until the pigment is fixed to the recording paper even if the resin is added to improve the fixability of the pigment to the recording paper. Therefore, with pigment-based inks, the pigment is strongly fixed to the recording paper so that there is no loss of the pigment even if 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 Japanese Patent No. 2819741 Japanese Patent Laid-Open No. 3-79680 Japanese Patent Laid-Open No. 3-76768 Japanese Patent No. 3581456 JP 2005-272839 A

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

  The recording liquid according to the present invention is attached to an object for recording on the object, and includes a solvent containing at least water and a water-soluble organic solvent, a pigment dispersed in the solvent, and a styrene-maleic acid. At least one water-soluble organic resin compound selected from an organic amine salt of an acid copolymer and an organic amine salt of a styrene-maleic acid alkyl ester copolymer, and the water-soluble organic solvent includes at least an ether A dihydric alcohol solvent having no bond, the dihydric alcohol solvent is contained in the range of 5 to 20% by weight, and the water-soluble organic resin compound has a weight ratio of 0.3 to the pigment. It is contained in the range of 2 to 2 times, and the liquidity is alkaline.

  According to the present invention, at least one water-soluble organic resin compound selected from an organic amine salt of a styrene-maleic acid copolymer and an organic amine salt of a styrene-maleic acid alkyl ester copolymer is added to the pigment. By containing 0.3 to 2 times by weight with respect to the pigment, the fixability of the pigment can be enhanced, 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%. It is easy to permeate into the object, it is easy to dry, and the time until the pigment is fixed to the object, so-called drying time, can be shortened.

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

  Moreover, according to this invention, the transparency of the printed matter after penetrating the object can be maintained by using the non-volatile organic amine salt.

  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. It is. The line-type printer apparatus 1 performs printing for each column across the width direction of the recording paper P, so that the ink ejection head that ejects the ink i moves in the width direction of the recording paper P and moves for one column. The printing speed is faster than that of the serial type printer that performs the printing, and the discharge interval of the recording paper P is also shortened. The ink i to which the present invention is applied has a short drying time, and the pigment is fixed to the recording paper P in a short time. Therefore, even when the ink i is used in the line-type printer apparatus 1 having a short paper discharge interval. The image or characters printed on the recording paper P discharged earlier are transferred to the back side of the recording paper P discharged later, and the images or characters printed on the recording paper P discharged earlier. It is possible to prevent the occurrence of problems such as the deterioration of quality. In addition, since the ink i to which the present invention is applied has good fixability of the pigment, the pigment is not lost from the recording paper P, and color loss of images and characters can be prevented, and the quality of the images and characters is reduced. Can be prevented. First, the ink i to which the present invention is applied will be described.

  Ink i includes a pigment as a pigment, a solvent containing at least water and a water-soluble organic solvent in which the pigment is dispersed, an organic amine salt of a styrene-maleic acid copolymer, and an organic compound of a styrene-maleic acid alkyl ester copolymer. And at least one water-soluble organic resin compound selected from amine salts. The water-soluble organic solvent contains at least a dihydric alcohol solvent having no ether bond.

  As the pigment contained as the coloring matter, either an organic pigment or an inorganic pigment can be used. 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, colorless or light color extender pigments, and plastic pigments Etc. 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 a mixture of these may be used.

  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, and any one or a combination of these may 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, and any one or a combination of these may be used.

  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, and any one or a plurality of these may be used in combination.

  The pigment is 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 with respect to the total amount of the ink i. In the ink i, when the pigment is contained in an amount of 0.5% by weight or more based on the total amount of the ink i, a concentration sufficient to form an image, characters, and the like can be obtained. Further, in the ink i, by setting the pigment to 10% by weight or less with respect to the total amount of the ink i, a sufficient density can be obtained without deteriorating the fixing property of the pigment to the recording paper P. Therefore, in the ink i, by setting the pigment content to 0.5 wt% to 10 wt% with respect to the total amount of the ink i, it is possible to obtain a sufficient density of images, characters, etc. Fixability to P is also obtained.

  The pigment preferably has a particle size in the range of 30 nm to 200 nm. In the ink i, by setting the particle diameter of the pigment to 30 nm or more, it is possible to prevent the discharge characteristics from deteriorating without pseudo-collection of the pigment. In addition, in the ink i, by setting the particle diameter of the pigment to 200 nm or less, it is possible to prevent the glossiness of images and characters from being deteriorated. Therefore, in the ink i, by setting the pigment particle size to 30 nm to 200 nm, it is possible to form glossy images and characters without deteriorating the ejection characteristics.

  Ink i, the polydispersity index is preferably adjusted to 0.3 or less, and more preferably the polydispersity index is 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 the ink i. In the ink i, by setting the polydispersity index to 0.3 or less, the pseudo-collection of the pigment does not remain. Therefore, the nozzle 27a is not clogged due to the pseudo-collection of the pigment, and the discharge characteristics can be prevented from being deteriorated. It is also possible to prevent the glossiness of images and characters after printing from being lowered.

  The solvent in which the pigment is dispersed contains at least water and a water-soluble organic solvent. As the water, for example, pure water, ultrapure water, distilled water, ion exchange water or the like is used.

  The water-soluble organic solvent includes at least a dihydric alcohol solvent having no ether bond for the purpose of imparting desired physical properties to the ink i, improving dispersibility of the pigment in the solvent, and shortening the drying time. Contained. Here, the drying time means that after printing an image, characters, etc. on the recording paper P, when the image, characters, etc. are rubbed with a predetermined load applied, the pigment is fixed on the recording paper P and color fading occurs. This is the time until there is no transfer, that is, until there is no transfer of images or characters. 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 included. Of the dihydric alcohol solvents having no ether bond, those having a small number of carbon atoms are preferable because they have low viscosity and easily penetrate into recording paper.

  In the ink i, the dihydric alcohol solvent having no ether bond described above is 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 entire ink i instead of the dihydric alcohol solvent, the monohydric alcohol solvent is easily vaporized. Viscosity will increase. 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 trihydric alcohol solvent has high viscosity. The viscosity becomes too high. Therefore, a dihydric alcohol solvent having good pigment dispersibility, moderate drying properties, and low viscosity is used. Moreover, it is difficult to shorten the drying time with a dihydric alcohol having an ether bond.

  Ink i deteriorates during long-term storage, such as precipitation of a pigment when stored for a long period of time by setting the content of dihydric alcohol solvent not having an ether bond to 5% by weight or more with respect to the entire ink i. Or the tip of the nozzle 27a can be prevented from drying. In addition, in the ink i, by setting the content of the dihydric alcohol solvent having no ether bond to 20% by weight or less with respect to the entire ink i, the viscosity does not become too high, and the discharge characteristics can be prevented from being deteriorated. Further, it is possible to prevent the drying time from becoming long. Therefore, in the ink i, by setting the content of the dihydric alcohol solvent having no ether bond to 5 to 20% by weight, the physical properties of the ink i are stabilized, the viscosity is not excessively increased, and the ejection characteristics are increased. Is good and the drying time can be shortened.

  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, organic solvents that can be used as the solvent include polyhydric alcohols such as diethylene glycol, butylene glycol, triethylene glycol, tetraethylene glycol, 1,2,6-hexanetriol, 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 them may be contained.

  The water-soluble organic resin compound contained in the ink i in addition to the pigment can enhance 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-maleic acid copolymer and an organic amine salt of a styrene-maleic acid alkyl ester copolymer. The ink i contains one or more of an organic amine salt of a styrene-maleic acid copolymer and an organic amine salt of a styrene-maleic acid alkyl ester copolymer. Ink i lands on recording paper P by containing one or more of an organic amine salt of a styrene-maleic acid copolymer and an organic amine salt of a styrene-maleic acid alkyl ester copolymer. After drying, the pigment can be firmly fixed on the recording paper P without coming off from the recording paper P even when the water or the like comes into contact with the image or the text or rubs the image or the text.

  Of the organic amine salts, monoethanolamine and diethanolamine are preferable because they can appropriately enhance the fixability of the pigment to the recording paper P and can withstand practically the drying of the nozzle.

  In addition, the organic amine salt forming the organic amine salt of styrene-maleic acid copolymer and the organic amine salt of styrene-maleic acid alkyl ester copolymer has a boiling point of 150 ° C. or more and 300 ° C. or less under 1 atm. Is preferred. In ink i, when the boiling point of the organic amine is 150 ° C. or higher under 1 atm, the organic amine component does not volatilize from the tip of the nozzle 27a, which will be described later, and insolubilization of the water-soluble organic resin compound can be prevented. Can be prevented from clogging. Ink i has an organic amine boiling point of 300 ° C. or less under 1 atm. Therefore, an organic amine having a temperature of 300 ° C. or less has a low molecular weight, and has a viscosity when used for neutralizing an acid of a water-soluble resin compound. Increase is suppressed, and it is suitable as an ink for ink jet. Therefore, in ink i, the boiling point of the organic amine that forms the organic amine salt of the styrene-maleic acid copolymer and the organic amine salt of the styrene-maleic acid alkyl ester copolymer is 150 ° C. or higher and 300 ° C. at 1 atmosphere. By using the following organic amine, an optimal ink as an ink-jet ink without clogging of the nozzle 27a can be obtained.

  The fixing property of the pigment on the recording paper P described above can be appropriately increased, and the boiling point of monoethanolamine that can withstand the drying of the nozzle 27a practically is 171 ° C., and the boiling point of diethanolamine is 269 ° C. is there.

  In addition, when the sodium salt of a styrene-maleic acid copolymer or the sodium salt of a styrene-maleic acid alkyl ester copolymer is used, there is a possibility that images, characters, etc. may become cloudy when the ink i is dried. . In addition, when an ammonium salt of a styrene-maleic acid copolymer and an ammonium salt of a styrene-maleic acid alkyl ester copolymer are used, the ammonium salt is likely to volatilize, so that images and characters may become cloudy. There is. On the other hand, since the organic amine salt has a high boiling point, images and characters do not become cloudy, and high-quality images and characters having transparency can be maintained.

  The organic amine salt of the styrene-maleic acid copolymer and the organic amine salt of the styrene-maleic acid alkyl ester copolymer may be appropriately copolymerized with, for example, a monomer having a polyoxyethylene group or a hydroxyl group. Is possible. Furthermore, the organic amine salt of the styrene-maleic acid copolymer and the organic amine salt of the styrene-maleic acid alkyl ester copolymer have increased affinity with the pigment having an acidic functional group on the surface, In order to improve the dispersibility of the pigment, for example, a monomer having a cationic functional group, such as N, N-dimethylaminoethyl methacrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminomethacrylate Amide, 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 in the range of 0.3 to 2 times by weight with respect to the pigment, preferably 0.5 to 1.2 by weight with respect to the pigment. Double the range.

  In the ink i, the fixing property of the pigment to the recording paper P can be improved by making the content of the water-soluble organic resin compound 0.3 times or more by weight with respect to the pigment content. Further, in the ink i, by setting the content of the water-soluble organic resin compound to 2 times by weight or less with respect to the pigment content, the viscosity does not become excessively high, and the discharge characteristics are not deteriorated. Fixability to the recording paper P can be maintained. Therefore, in the ink i, the content of the water-soluble organic resin compound is set to a range of 0.3 to 2 times by weight with respect to the content of the pigment to be contained in the ink i. Accordingly, the amount of the water-soluble organic resin compound to be contained is appropriately determined, so that 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 improved.

  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 has a weight average molecular weight of 3000 to 8000. In the ink i, the fixing property of the pigment to the recording paper P can be maintained by setting the weight average molecular weight of the water-soluble organic resin compound to 2000 or more. In addition, in the ink i, by setting the weight average molecular weight of the water-soluble organic resin compound to 10,000 or less, the fixability of the pigment to the recording paper P can be maintained without deteriorating the ejection characteristics. Therefore, in the ink i, by setting the weight average molecular weight of the water-soluble organic resin compound to 2000 to 10000, the fixability of the pigment to the recording paper P can be maintained, and the ejection characteristics are also good.

  Further, the organic amine salt of styrene-maleic acid copolymer and the organic amine salt of styrene-maleic acid alkyl ester copolymer are the acids of the above-mentioned styrene-maleic acid copolymer and styrene-maleic acid alkyl ester copolymer. More preferably, it is neutralized with an organic amine of 50% or more with respect to the valence, and 80% or more with respect to the acid value of the styrene-maleic acid copolymer and the styrene-maleic acid alkyl ester copolymer. More preferably.

  Furthermore, as the water-soluble organic resin compound, it is preferable to use those in which the structure and composition ratio of the hydrophobic portion and the hydrophilic portion are preferable in combination with a pigment or a solvent.

  Furthermore, as the water-soluble organic resin compound, a styrene-maleic acid copolymer and a styrene-maleic acid alkyl ester copolymer are used to improve the balance between solubility in ink i and ensuring water resistance after printing. The acid value of is preferably in the range of 100 to 250.

  The ink i includes 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, and a nonionic surfactant, and one or more of these are 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. Are used as a mixture. 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, etc., and any one or more of these may 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 Are used as a mixture.

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

  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.

  Among the above-mentioned surfactants, polypropylene glycol / ethylene oxide adducts, acetylene glycol oxyethylene adducts, polyoxyethylene alkyl ethers and the like are particularly preferable because they have a 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. . In the ink i, by making the surfactant content less than 10% by weight, the action and effect of the surfactant such as improvement of wettability and defoaming can be obtained without saturation. In addition, in the ink i, when the surfactant content is 0.01% by weight or more, the effects of the surfactant such as improved wettability and defoaming can be obtained.

  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. It can also be added.

  Furthermore, for the purpose of stabilizing the physical properties and the ejection characteristics of the ink i, in addition to those described above, for example, celluloses such as polyethyleneimine, polyamines, polyvinylpyrrolidone, polyethylene glycol, ethylcellulose, carboxymethylcellulose, etc. Derivatives, polysaccharides and their derivatives, other water-soluble polymers, polymer emulsions such as acrylic polymer emulsions, polyurethane emulsions, cyclodextrins, macrocyclic amines, dendrimers, crown ethers, urea and its derivatives, acetamide, etc. are 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, and after sufficiently stirring, dispersed using a disperser and coarse particles are removed by centrifugation or the like. Further, it is prepared by adding a predetermined solvent such as a dihydric alcohol having no ether bond, a water-soluble organic resin compound, a surfactant and the like, stirring, mixing, and filtering. 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 using 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 a 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 to be contained does not precipitate, the physical properties of the ink i are stabilized, and the ink discharge head 23 formed of a metal thin film such as nickel plating described later is used. Corrosion of the nozzle sheet 27 and the like can also be prevented.

  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. In the ink i, by setting the pH to 7 or more, the water-soluble organic resin compound can be dissolved, the water-soluble organic resin compound can be prevented from being precipitated, and the discharge characteristics can be prevented from deteriorating. Further, in the ink i, by setting the pH to 11 or less, the nozzle sheet 27 formed of a metal thin film such as nickel plating provided with a nozzle 27a to be described later is provided that the physical properties are stable without becoming too strong alkali. Etc. can be prevented from corroding. Therefore, in the ink i, by making the liquid property alkaline, the water-soluble organic resin compound is dissolved, and corrosion of members constituting the ink discharge head 23 such as the nozzle sheet 27 can be suppressed. Furthermore, in the ink i, by setting the pH to 9 or less, the ink i becomes closer to neutrality, and corrosion of members constituting the ink discharge head 23 can be further suppressed.

  In the ink i having the above-described configuration, at least one selected from an organic amine salt of a styrene-maleic acid copolymer and an organic amine salt of a styrene-maleic acid alkyl ester copolymer having high affinity with a pigment. By containing two water-soluble organic resin compounds in a weight ratio of 0.3 to 2 times the pigment content, the fixability of the pigment to the recording paper P can be improved, and printing on the recording paper P is possible. Even if the printed image or characters are rubbed or water is attached, the loss of the pigment can be prevented.

  In this ink i, the water-soluble resin contained for enhancing the fixability of the pigment is an organic amine salt of a styrene-maleic acid copolymer or an organic amine salt of a styrene-maleic acid alkyl ester copolymer. Even if the printed image or character is dried, the image or character is not whitened, and the transparency of the image or character can be maintained.

  Further, in this ink i, at least one water-soluble organic resin compound selected from a pigment, an organic amine salt of a styrene-maleic acid copolymer, and an organic amine salt of a styrene-maleic acid alkyl ester copolymer is used. In addition to water, the solvent to be dispersed contains a dihydric alcohol solvent having a good dispersibility of the pigment, low viscosity, and having an appropriate drying property and having no ether bond in the range of 5 to 20% by weight. Therefore, the time until the pigment is fixed on the recording paper P and is not transferred, that is, the 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 can be suppressed.

  Accordingly, in this ink i, at least one water-soluble organic resin compound selected from an organic amine salt of a styrene-maleic acid copolymer and an organic amine salt of a styrene-maleic acid alkyl ester copolymer, and a solvent 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, images, characters, and the like formed using this ink i are immediately dried, the pigment is immediately fixed on the recording paper P, and the loss of the fixed pigment is suppressed. High quality can be maintained. In addition, even if another object is superimposed on an image or character formed using this 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 a device main body 3 to which is attached. 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 supply unit 12 is a substantially protruding nozzle, and the tip of the nozzle is fitted into a connection unit 25 of the head cartridge 2 described later, whereby the ink tank 11 and the cartridge main body 21 of the head cartridge 2 are connected. Connect so that ink i can be supplied. 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 ink cartridge 11 may be formed integrally with the head cartridge 2.

  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 for each color in a substantially line shape in the width direction of the recording paper P, that is, the arrow W direction in FIG. It is installed. 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. Further, the ink discharge head 23 discharges ink i droplets, and then supplies the ink i from the ink cartridge 11 through the connection portion 25 through the ink flow path 29 to the ink liquid chamber 30 before being discharged again. Return to the state. 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 to the entire surface side of the apparatus main body 3 as shown in FIGS. 2 and 5, and the ejection surface 23a of the ink ejection head 23 is exposed to the outside. Expose. 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 that conveys the recording paper P and a cap opening / closing mechanism 47 that opens and closes the head cap 24 that protects the ejection surface 23 a of the head cartridge 23. .

  With the above-described configuration, the printer apparatus 1 supplies 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.

  In the printer apparatus 1, the head cap opening / closing mechanism 47 moves the head cap 24 to the front side of the apparatus main body 3 in which the paper feed tray 43 and the paper discharge tray 45 are provided with respect to the head cartridge 2. 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 recording paper P is output by the pair of separation rollers 52a and 52b rotating in the same direction. 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 device 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 23a.

  Next, the printer apparatus 1 supplies a driving current to the heating resistor 26a selected by the control signal based on the print data among the plurality of heating resistors 26a provided in the ink discharge head 23, and the selected heating is performed. The resistor 26a is heated. 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. After printing, the head cap 24 waiting on the entire surface side of the apparatus main body 3 is moved to the bottom surface of the cartridge 2 by the head cap opening / closing mechanism 47, and the ejection surface 23a of the ink ejection head 23 is closed and protected. At this time, the discharge surface 23a may be cleaned by the cleaning roller 24a.

  As described above, since the printer 1 performs printing for each row in the width direction of the recording paper P, the printing time for one recording paper is short, and a plurality of recording papers P can be discharged within a short time. The paper is discharged onto the paper tray 45 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. As a result, in the printer apparatus 1, even if the recording paper P after printing is discharged and stacked on a plurality of sheets in a short time, the pigment is immediately fixed on the recording paper P, so that the discharged recording paper P It is possible to prevent deterioration of the quality of the image and characters of the recording paper P that has been discharged first, and the quality of the image and characters of the recording paper P that has been discharged first can be prevented from being deteriorated. A state of quality 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-maleic acid copolymer or an organic amine salt of a styrene-maleic acid alkyl ester copolymer having high affinity with the pigment is used. By containing at least one selected water-soluble organic resin compound in a weight ratio of 0.3 to 2 times with respect to the pigment, the fixability of the pigment in the ink i to the recording paper P is improved. Even if the printed 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 the printer apparatus 1, since the ink i contains an organic amine salt of a styrene-maleic acid copolymer and an organic amine salt of a styrene-maleic acid alkyl ester copolymer, images, characters, and the like are dried. However, the transparency of images, characters, etc. can be maintained without being dull like sodium salts or ammonium salts.

  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, and the like constituting the ink discharge head 23 are not corroded, so that the ink discharge head 23 can be prevented from malfunctioning.

  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 images 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. Further, even when used in a serial type printer device, it is possible to prevent the occurrence of white spots such as images and characters and problems with the ink ejection head.

  In addition to the electrothermal conversion method in which the ink i is heated by the heating resistor 26a and ejected in the form of droplets from the nozzle 27a as in the printer device 1 described above, for example, vibration of a piezoelectric element is used. Thus, the present invention can be applied to a recording method such as a so-called piezo method in which minute droplets fly, and the same effect as described above can be obtained.

  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. Diethanolamine salt (denoted as DEA in Table 1) of a styrene-maleic acid copolymer (denoted as A in Table 1) having 4% by weight of Pigment Red-122 and an average weight molecular weight of 10,000 as a water-soluble organic resin compound. ) Is 1.2% by weight, Olfin E1010 manufactured by Air Products is 1% by weight as a surfactant, and propylene glycol (1.2-propanediol), which is a dihydric alcohol solvent having no ether bond, is used as a solvent. These materials, an appropriate amount of triethanolamine as a pH adjuster so as to be 20% by weight, and the remaining amount as ion exchange water so that the total amount becomes 100% by weight, and this predetermined amount of ion exchange water, Were mixed and stirred, and filtered through a filter having a pore size of 1 μm to prepare an ink. The content of the diethanolamine salt of the styrene-acrylic acid copolymer is 0.3 times by weight with respect to the pigment content. The physical properties of the obtained ink are as shown in Table 1. The boiling point of diethanolamine forming the diethanolamine salt of the styrene-maleic acid copolymer is 171 ° C.

<Sample 2>
In Sample 2, the average particle diameter of the pigment is 120 nm, the diethanolamine salt of the styrene-maleic acid copolymer is 8% by weight, and the content of the diethanolamine salt of the styrene-maleic acid copolymer is based on the pigment content. The ink was adjusted in the same manner as Sample 1 except that the weight ratio was doubled.

<Sample 3>
In Sample 3, a monoethanolamine salt of a styrene-maleic acid copolymer (shown as MEA in Table 1) having an average particle diameter of 135 nm and an average weight molecular weight of 10,000 was used as a water-soluble resin. Except for the above, ink was adjusted in the same manner as in Sample 1. The boiling point of monoethanolamine forming the monoethanolamine salt of the styrene-maleic acid copolymer is 269 ° C.

<Sample 4>
In Sample 4, a diethanolamine salt of a styrene-maleic acid alkyl ester copolymer (shown as B in Table 1) having an average particle size of pigment of 92 nm and an average weight molecular weight of 10,000 was used as a water-soluble resin. Except for the above, ink was adjusted in the same manner as in Sample 1.

<Sample 5>
In sample 5, the ink was prepared in the same manner as in sample 4, except that the average particle diameter of the pigment was 115 nm and the average weight molecular weight of the styrene-maleic acid alkyl ester copolymer was 2000.

<Sample 6>
In Sample 6, the ink was prepared in the same manner as Sample 1, except that the average particle size of the pigment was 140 nm and propylene glycol was 5% by weight.

<Sample 7>
In Sample 7, the average particle diameter of the pigment was 120 nm, and the same procedure as in Sample 1 was used except that ethylene glycol (shown as EG in Table 1) was used as the dihydric alcohol solvent having no ether bond. Adjusted the ink.

<Sample 8>
In Sample 8, 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 adjusted as in 1.

<Sample 9>
In Sample 9, the average particle diameter of the pigment was 60 nm, and 1.5-pentanediol (shown as Pen in Table 1) was used as a dihydric alcohol solvent having no ether bond. The ink was adjusted as in 1.

<Sample 10>
In Sample 10, the average particle diameter of the pigment was 135 nm, and the ink was used 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. Adjusted.

<Sample 11>
In Sample 11, the average particle diameter of the pigment was 125 nm, the diethanolamine salt of the styrene-maleic acid copolymer was 8% by weight, and the weight ratio was doubled with respect to the pigment content. An ink was prepared in the same manner as in Sample 1, except that the content was 5% by weight.

<Sample 12>
In sample 12, the ink was prepared in the same manner as in sample 4, except that the average particle size of the pigment was 122 nm and the propylene glycol content was 5% by weight.

<Sample 13>
In Sample 13, the average particle diameter of the pigment was 130 nm, and the content of the diethanolamine salt of the styrene-maleic acid alkyl ester copolymer was 2% by weight, except that it was twice the pigment content. Ink was prepared in the same manner as Sample 12.

<Sample 14>
In Sample 14, the ink was prepared in the same manner as Sample 13, except that the average particle size of the pigment was 125 nm and the content of propylene glycol was 20% by weight.

<Sample 15>
In Sample 15, the average particle diameter of the pigment was 125 nm, and the same procedure as in Sample 1 was used except that ethylene glycol (shown as EG in Table 1) was used as the dihydric alcohol solvent having no ether bond. Adjusted the ink.

<Sample 16>
In sample 16, an ink was prepared in the same manner as in sample 7, except that the monoethanolamine salt of a styrene-maleic acid copolymer having an average pigment particle size of 136 nm and an average weight molecular weight of 11000 was used.

<Sample 17>
In Sample 17, an ink was prepared in the same manner as Sample 16, except that the monoethanolamine salt of a styrene-maleic acid copolymer having an average particle diameter of 132 nm and an average weight molecular weight of 1900 was used.

<Sample 18>
In Sample 18, the average particle size of the pigment was 145 nm, and an ink was prepared in the same manner as in Sample 7, except that the diethylamine salt of a styrene-maleic acid copolymer (denoted as DeA in Table 1) was used. The boiling point of diethylamine forming the diethylamine salt of the styrene-maleic acid copolymer is 269 ° C.

<Sample 19>
In sample 19, the average particle diameter of the pigment was 190 nm, the monoethanolamine salt of the styrene-maleic acid copolymer was 1.1% by weight, and the weight ratio was 0.275 times the pigment content. Except that, the ink was adjusted in the same manner as in Sample 7.

<Sample 20>
In Sample 20, the average particle diameter of the pigment was 182 nm, the monoethanolamine salt of the styrene-maleic acid copolymer was 9% by weight, and the weight ratio was 2.25 times the pigment content. Adjusted the ink in the same manner as Sample 19.

<Sample 21>
In Sample 21, the average particle diameter of the pigment was 144 nm, and the same procedure as in Sample 7 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. Adjusted the ink.

<Sample 22>
In Sample 22, the average particle diameter of the pigment was 151 nm, and the ink was prepared in the same manner as in Sample 7, except that hydroxyethyl cellulose (indicated as D in Table 1) was used as the water-soluble organic resin compound. did.

<Sample 23>
In Sample 23, the average particle size of the pigment was 92 nm, and an ink was prepared in the same manner as in Sample 7, except that polyvinyl acetal (shown as E in Table 1) was used as the water-soluble resin.

<Sample 24>
In Sample 24, the average particle diameter of the pigment was 151 nm, ethylene glycol was used as the water-soluble organic solvent, and the ink was prepared in the same manner as in Sample 3 except that the ethylene glycol content was 4% by weight. .

<Sample 25>
In Sample 25, the ink was prepared in the same manner as Sample 24 except that the average particle size of the pigment was 126 nm and that ethylene glycol was 21 wt%.

<Sample 26>
In sample 26, the average particle diameter of the pigment was 141 nm, and the ink was prepared in the same manner as in sample 3, except that triethylene glycol (shown as TriEG in Table 1) was used as the water-soluble organic solvent. .

<Sample 27>
In sample 27, sample 3 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 adjusted in the same manner as described above.

<Sample 28>
In sample 28, the ink was adjusted in the same manner as in sample 3, except that ethylene glycol was 20% by weight and the pH was adjusted with acetic acid so that the liquid property showed pH 6.9. In Sample 28, precipitates were formed, and it was impossible to measure the particle size, polydispersity index, and viscosity of the pigment.

<Sample 29>
In sample 29, the average particle size of the pigment was 142 nm, and an ink was prepared in the same manner as in sample 7, except that the triethanolamine salt of a styrene-maleic acid copolymer was used. The boiling point of triethanolamine forming the triethanolamine salt of the styrene-acrylic acid copolymer is 361 ° C.

  Printing was performed using the inks of Sample 1 to Sample 29 obtained as described above. Each ink cartridge filled with the ink of Sample 1 to Sample 29 is mounted on the head cartridge, and predetermined ink-jet glossy paper (photo paper (glossy)) made by Epson at a resolution of 600 dpi using a line-type ink jet printer device. So-called solid printing was performed to fill the area.

  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 Scientific Co., Ltd.). RT-200) and rubbed 5 times at a rate of 30 reciprocations per minute while applying a load of 100 g / cm ² with a cellular roll nonwoven fabric (trade name: Bencott M-3) manufactured by Ozu Sangyo Co., Ltd. Measured with a densitometer. As for the scratching property, the remaining color condition with respect to the initial density, that is, the remaining rate is 80% or more and the image quality is good is indicated by ○ in Table 2, and the image quality is less than 80%. Those that have decreased are indicated by crosses.

  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. The water resistance is indicated by ◯ when the residual rate is 80% or more and the image quality is good, and indicated by X when the image quality is lower than 80%.

  The ink drying in the nozzle was evaluated as follows. When the nozzle surface of the ink ejection head is exposed to the atmosphere for 120 seconds, solid printing is performed, and if printing can be performed without any problem, it is indicated by a circle, and the ejection characteristics such as variations in ink landing positions and non-ejection of ink are deteriorated. When there was, it was indicated by a cross.

  The continuous discharge property was evaluated as follows. The pressure generating element of the printer device was driven at a frequency of 10 kHz, and 200 million inks were continuously discharged to perform a continuous discharge test. Regarding the ink ejection speed, a circle indicates that the rate of decrease in speed from the initial speed is within 20%, and a mark indicates that there is a decrease in speed of 20% or more. Moreover, although there was no speed reduction rate 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, water-soluble organic solvent, and 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, in samples 1 to 15, an organic amine salt of a styrene-maleic acid copolymer or an organic amine salt of a styrene-maleic acid alkyl ester copolymer is used as a water-soluble organic resin compound with respect to the pigment. A dihydric alcohol solvent containing at least an ether bond as a water-soluble organic solvent is contained in a range of 5% by weight to 20% by weight. Due to the alkaline nature of the liquid, all evaluations of scratch resistance after 10 minutes and 60 minutes, water resistance, nozzle dry state, and continuous dischargeability were good.

  In samples 1 to 15, the organic amine salt of styrene-maleic acid copolymer or the organic amine salt of styrene-maleic acid alkyl ester copolymer is 0.3 times the weight ratio of the pigment as the water-soluble organic resin compound. Compared to Sample 19 in which the content of the water-soluble organic resin compound is 0.275 times that of the pigment, the content of the water-soluble organic resin compound is superior to that of the pigment. Compared to the sample 20 containing 2.25 times, the rubbing property and the continuous ejection property are excellent.

  In sample 19, the content of the water-soluble organic resin compound is 0.275 times the content of the pigment and less than 0.3 times the content of the pigment. Since the amount of the pigment is too small to improve the fixability of the pigment to the recording paper by the water-soluble organic resin compound, the fixability of the pigment to the recording paper is not improved, and the pigment is missing when the printed image is rubbed. did. Thereby, in the sample 19, evaluation of abrasion property worsened.

  In Sample 20, the content of the water-soluble organic resin compound is 2.25 times the pigment content and more than twice the pigment content, so the viscosity of the ink becomes too high. The nozzle was clogged and non-ejection occurred, resulting in poor continuous ejection. In addition, since the sample 20 contains a large amount of water-soluble organic resin compound that easily absorbs moisture, the penetration of the ink into the recording paper is hindered by the water-soluble organic resin compound, making it difficult to dry. When rubbed, the pigment was lost and the rubability after 10 minutes deteriorated.

  Compared to Sample 19 and Sample 20, in Sample 1 to Sample 15, the content of the water-soluble organic resin compound is in the range of 0.3 to 2 times the content of the pigment, so that the pigment recording paper Since the fixability to the ink was improved and the viscosity of the ink was not excessively high, excellent scratching properties and continuous dischargeability were obtained.

  In Samples 1 to 15, the water solubility of the organic amine salt of a styrene-maleic acid copolymer and the organic amine salt of a styrene-maleic acid alkyl ester copolymer capable of enhancing the fixability of the pigment to the recording paper. It contains at least one organic resin compound, and is excellent in scratch resistance, water resistance, and continuous discharge properties as compared with Samples 21 to 23 not containing these water-soluble organic resin compounds.

  Samples 21 and 22 contain a monoethanolamine salt of polyacrylic acid and hydroxyethyl cellulose as water-soluble organic resin compounds, and can improve the fixability of the pigment to the recording paper. Since the water-soluble organic resin compound of the organic amine salt of the polymer or the organic amine salt of the styrene-maleic acid alkyl ester copolymer is not contained, the fixability of the pigment to the recording paper is low, and the image is printed 10 minutes after printing. The pigment was missing when it was rubbed or in contact with water. Thereby, in the sample 21 and the sample 22, the abrasion property and water resistance after 10 minutes deteriorated.

  In Sample 21 and Sample 22, the affinity of the monoacrylic amine salt of polyacrylic acid or hydroxyethyl cellulose used as the water-soluble organic resin compound with the pigment is low, so that when the pigment comes into contact with water, The water resistance decreased.

  In Sample 23, polyvinyl acetal is contained as a water-soluble organic resin compound, and an organic amine salt of a styrene-maleic acid copolymer or a styrene-maleic acid alkyl ester copolymer capable of improving the fixability of a pigment to recording paper. Since the water-soluble organic resin compound of the organic amine salt of the polymer is not contained, the pigment is lost when it comes into contact with water, resulting in poor water resistance. Moreover, in the sample 23, the continuous discharge property deteriorated due to the poor inkjet suitability of polyvinyl acetal.

  In contrast to these samples 21 to 23, in samples 1 to 15, the organic amine salt of a styrene-maleic acid copolymer and the organic amine salt of a styrene-maleic acid alkyl ester copolymer are used as the water-soluble organic resin compound. Since the water-soluble organic resin compound is contained, the fixability of the pigment to the recording paper is improved, so that it has excellent scratch resistance and water resistance. Samples 1 to 15 contain a water-soluble organic resin compound of an organic amine salt of a styrene-maleic acid copolymer and an organic amine salt of a styrene-maleic acid alkyl ester copolymer as the water-soluble organic resin compound. Therefore, the physical properties were stable and excellent continuous discharge properties were obtained.

  In Samples 1 to 15, the content of the dihydric alcohol solvent having no ether bond is 5% by weight or 20% by weight of the whole ink, and the content of ethylene glycol is 4% by weight. Compared to 24, the nozzle drying property is excellent, and compared to the sample 25 having a content of 21% by weight, the rubability after 10 minutes is excellent.

  In sample 24, the content of ethylene glycol in the dihydric alcohol solvent is 4% by weight and less than 5% by weight with respect to the whole ink, so that the pigment is precipitated and the physical properties are deteriorated, or the ink is ejected from the nozzle. When the nozzle was exposed to the atmosphere in a state where the ink was not discharged, the ink was dried and thickened, resulting in non-ejection and problems, and the evaluation of nozzle drying deteriorated.

  In sample 25, the content of ethylene glycol in the dihydric alcohol solvent is 21% by weight, more than 20% by weight with respect to the entire ink, and ethylene glycol is less volatile than water. On the other hand, it took time until the pigment was fixed, making it difficult to shorten the drying time, and the evaluation of scratching properties after 10 minutes was poor.

  Compared to these samples 24 and 25, in samples 1 to 15, 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. Problems such as deterioration of the physical properties of the ink and an increase in the drying time of the ink could be suppressed, and excellent nozzle drying evaluation and scratching properties after 10 minutes were obtained.

  Moreover, in samples 1 to 15, the liquidity was alkaline, and each evaluation could be performed as compared to sample 28 in which the liquidity was acidic.

  In sample 28, since the pH was 6.9 and acidic, the contained water-soluble organic resin compound precipitated and precipitated in the ink, making it difficult to eject the ink from the nozzle. Therefore, each evaluation could not be performed.

  In contrast to Sample 28, Samples 1 to 15 have a pH in the range of 7 to 11, the ink physical properties are stable, the water-soluble organic resin compound does not precipitate, and the ink can be ejected. Therefore, each evaluation could be performed.

  Further, in Samples 1 to 11, the boiling point of the organic amine forming the organic amine salt of the styrene-maleic acid copolymer or the organic amine salt of the styrene-maleic acid alkyl ester copolymer is 171 ° C. Yes, the boiling point of monoethanolamine is 269 ° C. under 1 atm, 150 ° C. or more and 300 ° C. or less under 1 atm, and sample 29 using triethanolamine having a boiling point of 361 ° C. under 1 atm. Compared to the above, the rubbing property after 10 minutes and the continuous discharge property are excellent.

  In sample 29, triethanolamine was used to neutralize the water-soluble organic resin compound, so that the viscosity of the ink increased. As a result, in sample 29, the ink became difficult to dry, the drying time became longer, and the evaluation of scratching properties after 10 minutes deteriorated. In sample 29, the initial discharge speed decreased due to an increase in the viscosity of the ink.

  In contrast to Sample 29, Samples 1 to 15 use monoethanolamine or diethanolamine whose organic amine has a boiling point in the range of 150 ° C. or higher and 300 ° C. or lower under 1 atm. The initial discharge speed could be maintained, and excellent continuous discharge properties and scratchability after 10 minutes were obtained.

  Furthermore, in Samples 1 to 15, the organic amine forming the organic amine salt of the styrene-maleic acid copolymer or the organic amine salt of the styrene-maleic acid alkyl ester copolymer is a monoethanolamine or diethanolamine having a high boiling point. In comparison with Sample 18 containing a water-soluble organic resin compound comprising a diethylamine salt, the nozzle drying evaluation is superior.

  Since sample 18 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 became insoluble in the ink, and the water-soluble organic resin compound was precipitated. As a result, in sample 18, 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 to such a sample 18, in the samples 1 to 15, since the high boiling point monoethanolamine or diethanolamine is used as the amine forming the organic amine salt, the ink in the nozzle is difficult to dry, and the nozzle The ejection characteristics after exposure to the atmosphere were excellent, and excellent nozzle drying evaluation was obtained.

  Further, in Samples 1 to 15, the average weight molecular weight of the organic amine salt of the styrene-maleic acid copolymer or the organic amine salt of the styrene-maleic acid alkyl ester copolymer is 2000 and 10,000, and the average weight molecular weight is 11000. Compared to Sample 16 containing a water-soluble resin, the continuous discharge property is excellent, and compared to Sample 17 containing a water-soluble resin having an average weight molecular weight of 1900, the rubbing property after 10 minutes is excellent.

  Compared to these samples 1 to 15, in sample 16, the average weight molecular weight of the water-soluble organic resin compound is 11000 and exceeds 10,000, so that it is difficult to be discharged from the nozzle, and the discharge speed is reduced. Continuous discharge characteristics deteriorated.

  In Sample 17, since the average weight molecular weight of the water-soluble organic resin compound is 1900 and less than 2000, the fixability of the pigment to the recording paper cannot be maintained in a good state, and rubs after 10 minutes after printing. The color residue was less than 80%, and the evaluation of scratching properties after 10 minutes deteriorated.

  In contrast to Sample 16 and Sample 17, in Samples 1 to 15, the weight average molecular weight of the water-soluble organic resin compound is 2000 to 10,000, so that the physical properties of the ink are stabilized and the ink is ejected continuously. In addition, since the fixing property of the pigment to the recording paper can be obtained, excellent scratching property and continuous discharge property were obtained.

  Furthermore, in Sample 1 to Sample 15, a dihydric alcohol solvent that does not have an ether bond, propylene glycol, ethylene glycol, 1.3-butanediol, 1.5-pentanediol, ethylene glycol and propylene glycol were mixed. 1,6-hexane having a large carbon number among the sample 26 containing triethylene glycol, which is not a dihydric alcohol solvent having no ether bond, and a dihydric alcohol solvent having no ether bond Compared to the sample 27 containing diol, the rubability after 10 minutes is excellent.

  Sample 26 contains triethylene glycol, which is not a dihydric alcohol solvent without an ether bond, and contains a dihydric alcohol solvent without an ether bond that can shorten the drying time. As a result, the rubability after 10 minutes deteriorated.

  In sample 27, among the dihydric alcohol solvents having no ether bond, 1.6-hexanediol having a large number of carbon atoms is contained, so that the viscosity becomes high and the drying time cannot be shortened. The rubability after 10 minutes deteriorated.

  Compared to these samples 26 and 27, samples 1 to 15 contain too low a carbon number among dihydric alcohol solvents that do not have an ether bond, so that the viscosity becomes too high. In addition, since it has an appropriate drying property, the drying time of the ink can be shortened, and an excellent rubbing property after 10 minutes was obtained.

  From the above, when preparing an ink, at least one water-soluble organic resin compound selected from an organic amine salt of a styrene-maleic acid copolymer and an organic amine salt of a styrene-maleic acid alkyl ester copolymer Select a dihydric alcohol solvent that does not have an ether bond, optimize the content of the water-soluble organic resin compound, the weight average molecular weight, the content of the dihydric alcohol solvent that does not have an ether bond, etc., and make the liquid alkaline This is very important in preparing an excellent ink that can achieve both the fixing property 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 typically the state which discharged. 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;
A pigment dispersed in the solvent;
Containing at least one water-soluble organic resin compound selected from an organic amine salt of a styrene-maleic acid copolymer and an organic amine salt of a styrene-maleic acid alkyl ester copolymer,
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.   2. 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.

Images