JP2006169325A - Recording liquid for inkjet, ink cartridge and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel recording liquid for inkjet. <P>SOLUTION: The recording liquid for inkjet contains a pigment, a water-soluble resin, a water-soluble organic solvent and water, wherein the water-soluble resin contains a polystyrene modified product obtained by sulfonating a polystyrene resin and a sodium polyacrylate, and the pigment is an organic pigment or a carbon black. The polystyrene modified product is a copolymer of a styrene unit or of a styrene unit and a unit other than styrene and contains 30-100 mol% styrene unit and 0.5-30 mol% sulfonated styrene unit against the total amount of monomer units. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording liquid suitable for use in an on-demand type ink jet printer in which recording is performed by ejecting a recording liquid (hereinafter also referred to as “ink”) from a nozzle of a recording head and flying it as droplets.

The present invention also relates to an ink cartridge that accommodates the inkjet recording liquid.
The present invention also relates to an ink jet recording method in which the ink jet recording liquid is discharged from a nozzle.

  The ink jet recording system has features such as low noise, low running cost, and easy colorization, and is rapidly spreading in the market. Color ink jet printers that can print on plain paper are also becoming popular. As a colorant for recording liquid used for ink jet recording, water-soluble dyes such as acid dyes and direct dyes are usually used, but it is not sufficient in terms of fastness such as light resistance and water resistance, and improved. Is being considered. In order to improve the light resistance and water resistance of water-soluble dyes, for example, as described in JP-A No. 64-62372, JP-A No. 64-48873, JP-A No. 64-16880, JP-A No. 63-289079, etc. Many proposals have been made but not enough. Furthermore, as a document application on plain paper, dyes tend to blur characters (feathering) more than pigments and tend to be inferior in terms of print density.

  Therefore, methods using pigments as colorants have also been studied for a long time. For example, JP-A-47-12104, JP-A-56-147859, JP-A-56-147863, JP-A-56-147869, JP-A-56-147 Many applications such as 157468, JP-A-57-21466 and JP-A-62-74973 have been filed, but when pigments are used as colorants, the light resistance and water resistance are significantly improved compared to dyes. Further, the ejection stability as a recording liquid and the scratch resistance after printing are inferior.

  For this reason, measures have been taken to improve dispersants such as JP-A-3-287676 and JP-A-4-39366. As the water-based resin having a role as a dispersant, there are those having both a site having an aromatic or unsaturated bond that interacts with a pigment as a colorant and a site that interacts with water or an aqueous solvent as a solvent. It is used. Examples of relatively good resins include styrene having affinity for pigments and copolymers such as acrylic acid and maleic acid having affinity for water.

  However, the resolution required for inkjet is higher, and the discharge nozzle diameter is becoming smaller.Therefore, the pigment in the recording liquid is made finer, for example, the average particle diameter of the pigment in the ink is 0.10 μm or less. Some are desired. In the black pigment ink, an ink having a small primary particle diameter and a high structure type (carbon particles are connected in a bead shape) is used in order to increase the printing density. As the pigment becomes finer or the average particle size in the recording liquid becomes smaller, it becomes difficult to disperse, and if the dispersion stability is insufficient, aggregation may occur and the ejection stability of the ink becomes unstable. . In terms of penetrating into photographic paper, dyes have good penetrability and excellent scratch resistance. However, the method using pigments does not sufficiently penetrate the paper base material compared to dyes, so that the pigment is used as a paper base. It is necessary to firmly adhere to the material. A single system of styrene, which has affinity for the pigments listed above as a good resin, and a copolymer of acrylic acid, maleic acid, etc., which has affinity for water, can maintain the dispersion stability of the pigment. The amount of addition is unavoidable until it is sufficiently fixed to the paper substrate. If this happens, the discharge stability will be adversely affected. There has been a strong demand for a technique that makes it possible to achieve both ink ejection stability and scratch resistance in ink having fine pigments.

Therefore, an ink jet recording liquid having a polystyrene resin containing a sulfonated styrene unit as a water-soluble resin having a role as a dispersant has been reported (see Patent Document 1).
However, this ink jet recording liquid has a problem that it is excellent in scratch resistance but has insufficient ejection stability.
JP2004-91656

  The present invention has been made in view of such problems, and is a novel ink jet recording liquid that has high light resistance and water resistance of recorded images, and is excellent in ejection stability and scratch resistance as a recording liquid. This object is based on the result that it can be achieved by using a specific dispersant in combination with a predetermined blend ratio.

  Another object of the present invention is to provide a novel ink cartridge that accommodates the inkjet recording liquid.

  Another object of the present invention is to provide a novel ink jet recording method in which the ink jet recording liquid is discharged from a nozzle.

  In order to solve the above-described problems and achieve the object of the present invention, the inkjet recording liquid of the present invention is an inkjet recording liquid containing a pigment, a water-soluble resin, a water-soluble organic solvent, and water. And a polystyrene-based modified product obtained by sulfonating a polystyrene-based resin, and sodium polyacrylate.

  According to the inkjet recording liquid of the present invention, the aromatic of the polystyrene-based modified product has an affinity for the pigment, and the sulfonic acid or sulfonate of the polystyrene-based modified product has an affinity for water or an aqueous solvent. The pigment dispersion is good and the stability is also good. Moreover, the dispersibility of a pigment improves by using sodium polyacrylate together with a polystyrene-type modified material.

  The ink cartridge of the present invention is an ink cartridge that contains an inkjet recording liquid containing a pigment, a water-soluble resin, a water-soluble organic solvent, and water. The water-soluble resin is a polystyrene-based resin obtained by sulfonating a polystyrene-based resin. It contains a modified product and sodium polyacrylate.

  According to the ink cartridge of the present invention, there is provided an ink cartridge that accommodates an inkjet recording liquid having good pigment dispersibility and good stability.

  The inkjet recording method of the present invention is an inkjet recording method in which an inkjet recording liquid containing a pigment, a water-soluble resin, a water-soluble organic solvent, and water is discharged from a nozzle. The water-soluble resin is a sulfonated polystyrene resin. It is characterized by containing a modified polystyrene based product and sodium polyacrylate.

  According to the ink jet recording method of the present invention, there is provided an ink jet recording method for discharging an ink jet recording liquid having good dispersibility of pigment and good stability.

The present invention has the following effects.
The present invention relates to an inkjet recording liquid containing a pigment, a water-soluble resin, a water-soluble organic solvent, and water. The water-soluble resin is a polystyrene-based modified product obtained by sulfonating a polystyrene-based resin, and sodium polyacrylate. Therefore, a novel ink jet recording liquid can be provided.

  The present invention relates to an ink cartridge containing an inkjet recording liquid containing a pigment, a water-soluble resin, a water-soluble organic solvent, and water, wherein the water-soluble resin is a polystyrene-based modified product obtained by sulfonating a polystyrene-based resin, In addition, since it contains sodium polyacrylate, a novel ink cartridge can be provided.

  The present invention relates to an inkjet recording method in which an inkjet recording liquid containing a pigment, a water-soluble resin, a water-soluble organic solvent, and water is ejected from a nozzle, wherein the water-soluble resin is polystyrene obtained by sulfonating a polystyrene resin. Since the system modification product and sodium polyacrylate are contained, a novel ink jet recording method can be provided.

  The best mode for carrying out the invention relating to an inkjet recording liquid will be described below.

  The gist of the present invention is an inkjet recording liquid containing a pigment, a water-soluble resin, a water-soluble organic solvent, and water. The water-soluble resin is a polystyrene-based modified product obtained by sulfonating a polystyrene-based resin, and polyacrylic acid. It exists in the recording liquid for inkjets characterized by containing sodium.

The present invention is described in detail below.
The water-soluble resin used in the present invention contains a polystyrene-based modified product obtained by sulfonating a polystyrene-based resin. The polystyrene-based modified product is a copolymer of a styrene unit represented by Chemical formula 4, or a copolymer of a styrene unit represented by Chemical formula 4 and a unit other than styrene.

  Since the aromatic of the polystyrene-based modified product has an affinity for the pigment and the sulfonic acid or sulfonate of the sulfonated polystyrene has an affinity for water or an aqueous solvent, the dispersion of the pigment is good and the stability is good.

  The polystyrene-based modified product preferably contains a styrene unit in a range of 30 to 100 mol% with respect to all monomer units. If the styrene unit content is less than 30 mol%, even if the pigment is dispersed in an aqueous solution of a polystyrene-based modified product, the adsorptivity to the pigment will be poor, and the storage stability of the recording liquid may be reduced. There is.

  The polystyrene-based modified product preferably has a sulfonation rate, that is, a ratio of the sulfonated styrene unit to the total monomer units in the range of 0.5 to 30 mol%. When the sulfonation rate is less than 0.5 mol%, the solubility in a water-soluble solvent is poor, and the storage stability of the recording liquid may be lowered. When the sulfonation rate exceeds 30 mol%, the viscosity of the recording liquid tends to increase, and when it exceeds 50 mol%, a gelation phenomenon occurs. As a result, the storage stability of the recording liquid is deteriorated.

  The degree of polymerization of the polystyrene-based modified product is preferably in the range of 25 to 200. When the degree of polymerization is less than 25, even if the resin is adsorbed to the pigment, the adsorption layer is thin, so that the storage stability of the recording liquid may be lowered. If the degree of polymerization exceeds 200, the viscosity of the recording liquid increases and the ejection characteristics may deteriorate.

  As described above, the polystyrene-based modified material only needs to contain a styrene unit in the range of 30 to 100 mol% with respect to the total monomer units, and may be a polymer of only a styrene unit, or a monomer other than styrene. The copolymer may be used. Units other than styrene include butadiene, acrylonitrile, (meth) acrylic acid, (meth) acrylic acid esters (aliphatic hydrocarbons having 1 to 4 carbon atoms), maleic anhydride, itaconic anhydride, and α-methylstyrene. Can be mentioned. These units other than styrene may be contained in one kind or two or more kinds, but are preferably within two kinds. The content of units other than styrene is 40 mol% or less, preferably 30 mol% or less.

  By the way, the polystyrene-based modified product can be synthesized by reacting a polystyrene-based resin with a sulfonating agent in a solvent, further neutralizing with an alkali compound, and modifying to a sulfonated polystyrene. Below, the synthesis | combining method of a polystyrene-type modified material is demonstrated.

  Examples of the sulfonating agent include sulfuric anhydride, fuming sulfuric acid, chlorosulfonic acid, concentrated sulfuric acid and the like. These sulfonating agents may be used alone or in combination of two or more. Moreover, as addition amount, it is suitable to use using 0.1-200 mol% with respect to the styrene unit in a polystyrene-type resin, More preferably, it is the range of 1-100 mol%.

  Furthermore, the sulfonating agent may be used in combination with a Lewis base. Examples of the Lewis base include alkyl phosphate (triethyl phosphate, trimethyl phosphate), dioxane, acetic anhydride, ethyl acetate, ethyl palmitate, diethyl ether, thioxan and the like. The addition amount of these Lewis bases is 1 to 200 mol%, preferably 2 to 100 mol%, based on the styrene unit in the polystyrene resin.

  Examples of the reaction solvent include aliphatic halogenated hydrocarbons having 1 to 2 carbon atoms (preferably 1,2-dichloroethane, chloroform, dichloromethane, 1,1-dichloroethane), aliphatic cyclic hydrocarbons (preferably cyclohexane, methyl). Cyclohexane, cyclopentane), nitromethane, nitrobenzene.

  The polystyrene resin concentration in the sulfonation reaction system is 0.1 to 30% by mass, preferably 0.5 to 20% by mass. When the concentration is lower than this range, the production efficiency and the rate of introduction of the sulfone group into the polymer are lowered. On the other hand, when the concentration is high, a large amount of gelled products and unreacted products are generated.

  The temperature of the sulfonation reaction is 0 to 100 ° C, preferably 15 to 80 ° C. If the temperature is lower than this range, the sulfonation reaction does not proceed easily, and the yield decreases.

  The time of the sulfonation reaction (however, the dropping time of the sulfonating agent is not included) is 10 minutes to 10 hours, preferably 30 minutes to 5 hours.

  As described above, after the polystyrene resin is sulfonated, it may be used as a polystyrene-based modified product obtained by neutralizing with a basic compound to obtain a polystyrene sulfonate.

  Basic compounds include compounds such as oxides, hydroxides, carbonates, acetates, sulfates and phosphates of alkali metals (sodium, lithium, potassium, etc.) and alkaline earth metals (magnesium, calcium, etc.) Alternatively, ammonia or various (1-3 tertiary alkyl) amine compounds are gradually added to the reaction system as they are or in the form of an aqueous solution to complete the neutralization treatment.

  Although the amount of added water varies depending on the molecular weight, it is 0.5 to 100 parts by mass, preferably 1 to 50 parts by mass with respect to 1 part by mass of the polymer.

  When the sulfonated modified product is water-soluble after the above neutralization treatment, the solvent is removed by liquid separation and / or distillation, and the solution is taken out in the state of an aqueous solution. In order to reduce the residual amount of the solvent, it is preferable to distill after separation. Further, when the sulfonated modified product exhibits water insolubility, it may be heat dried as it is, or may be taken out in a powder state by a method such as reprecipitation treatment or flash evaporation. In addition, the reaction temperature at the time of the said neutralization reaction is 0-80 degreeC.

  As a dispersing agent, you may use together water-soluble resin used for pigment dispersion other than said polystyrene type modified material. The water-soluble resin that can be used in combination is preferably a resin having an acid value of 50 to 300, more preferably 70 to 250. Since the bond between the pigment and the water-soluble resin is a hydrophobic bond, if the acid value of the resin is large (that is, the hydrophilicity is too strong), the resin cannot be adsorbed to the pigment surface as expected, and the unadsorbed resin in the pigment solution There will be more minutes. On the other hand, if the acid value of the resin is small (that is, the hydrophilicity is low), the resin does not dissolve in water. The acid value of the resin referred to in the present invention is represented by the amount (mg) of KOH that neutralizes the resin.

  Any resin that is soluble in an aqueous solution can be used, and natural polymers such as lignin sulfonate and ceramic, styrene-acrylic acid copolymer, styrene-acrylic acid-acrylic can be used. Acid alkyl ester copolymer, styrene-maleic acid copolymer, styrene-maleic acid-acrylic acid alkyl ester copolymer, styrene-maleic acid-α-methylstyrene copolymer, styrene-methacrylic acid copolymer, styrene- Methacrylic acid-acrylic acid alkyl ester copolymer, styrene-α methyl styrene-acrylic acid alkyl ester copolymer, styrene-maleic acid half ester copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer Polymers or their salts, polyacrylic acid, poly Examples thereof include salts such as sodium crylate and the like, sodium salts of β-naphthalenesulfonic acid formalin condensate, and anionic polymers such as phosphate. It is also effective to use a relatively low molecular weight surfactant in combination with the polystyrene-based modified product of the present invention to help improve the dispersibility of the pigment.

  The water-soluble resin includes sodium polyacrylate. When a polystyrene-based modified material is used as a dispersant in a single system, the discharge speed is certainly high in the initial stage, but there is a problem that the discharge stability is reduced. It is most effective to use sodium polyacrylate in a blend system in order to prevent the speed reduction and maintain the speed stably. As a combination to be used in combination, it has been found that the use of sodium polyacrylate is the most effective combination of both discharge stability and scratch resistance.

  This sodium polyacrylate preferably has a weight average molecular weight Mw in the range of 6000 to 10,000. When the average molecular weight is less than 6000, the dispersibility of the pigment is hindered, causing the storage stability of the ink to deteriorate, resulting in an adverse effect on the ejection stability. When the average molecular weight exceeds 10,000, the viscosity of the ink increases and the ejection stability deteriorates. Furthermore, when only polyacrylic acid is used, the ink is biased to the acidic side, and the dispersion stability of the pigment is hindered. Depending on the amount added, a gelation phenomenon occurs, which makes the ink unsuitable. Therefore, it is important to neutralize and use, and it is desirable to neutralize with inorganic and organic alkaline substances. Of these, the Na salt type is the most effective.

  On the other hand, it is a blend ratio with the above-mentioned polystyrene-based modified product. First, at least the polystyrene-based modified product and sodium polyacrylate used in the present invention are blended, and the content of the water-soluble resin used in combination is the pigment and the water-soluble resin. Is preferably 10:20 to 10: 1 by weight, preferably 10:10 to 10: 1, more preferably 10: 5 to 10: 1. In that, when the content of the water-soluble resin is 100, the blend ratio of the polystyrene-based modified product and sodium polyacrylate is preferably in the range of 10:90 to 90:10. It is preferably 30:70 to 90:10, and more preferably in the range of 30:70 to 50:50. When the ratio of the polystyrene-based reformed product exceeds 90, the discharge stability tends to be deteriorated. Conversely, when the ratio is less than 10, the scratch resistance is deteriorated.

  In addition, one or two or more of these, such as commercially available anionic surfactants such as sulfonates and cationic surfactants such as amine salts, can be appropriately used.

  The pigment will be described. Here, the pigment includes an organic pigment or carbon black.

  In the inkjet recording liquid to which the present invention is applied, any conventionally known materials such as organic pigments and carbon black constituting the recording liquid can be used, and are not limited at all.

  For example, conventionally known organic pigments can be used as the organic pigment. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc. Examples thereof include cyclic pigments, dye lakes such as basic dye type lakes, and acid dye type lakes, and organic pigments such as nitro pigments, nitroso pigments, aniline blacks, and daylight fluorescent pigments. Any organic pigment not described in the color index can be used as long as it can be dispersed in water. Further, it may be used as a coloring material comprising a self-dispersing pigment in which at least one hydrophilic group is bonded to the surface of the pigment described in US Pat. No. 5,547,39, directly or via other atomic groups. The content of these organic pigments varies depending on the structure, but is generally 3 to 20% by mass, preferably 3 to 12% by mass with respect to the recording liquid.

  Conventionally known carbon black can be used as the carbon black. Examples thereof include commercially available carbon blacks such as furnace black, channel black, acetylene black, and lamp black. These can be used not only as a commercial product but also as a new prototype basically by the same manufacturing method as that of a commercial product. Any carbon black not described in the color index can be used as long as it can be dispersed in water. Further, the carbon black can be stably dispersed without using a dispersant by introducing a water-soluble group on the surface of the carbon as disclosed in, for example, JP-A-5-186704 and JP-A-8-3498. It may be used as self-dispersing carbon that can be used. The content of these carbon blacks varies depending on the structure, but is generally 3 to 20% by mass, preferably 3 to 12% by mass with respect to the recording liquid.

  The water-soluble organic solvent used in the present invention includes a polyhydric alcohol and / or an alkyl ether thereof and an aliphatic monohydric alcohol. Examples of the polyhydric alcohol and / or its alkyl ether include polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, Alkylene glycols in which an alkylene group contains 2 to 6 carbon atoms such as hexylene glycol and diethylene glycol; glycerin; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) And lower alkyl ethers of polyhydric alcohols such as ethers. The content of these polyhydric alcohols and / or alkyl ethers thereof is in the range of 10 to 50% by mass, more preferably 20 to 40% by mass. When the content is less than 10% by mass, clogging at the nozzle tip is prevented. However, if it exceeds 50% by mass, the print quality of the printed matter will deteriorate.

  Examples of the aliphatic monohydric alcohol include alkyl having 1 to 4 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, and isobutyl alcohol. Examples include alcohols.

  Other water-soluble organic solvents include amides such as dimethylformamide and dimethylacetamide; ketones or ketoalcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; N-methyl-2-pyrrolidone, 1, 3-dimethyl-2-imidazolidinone and the like.

  The main components constituting the recording liquid of the present invention are as described above, but other surfactants, pH adjusters, preservatives, antifoaming agents and the like may be used as necessary.

  Surfactants for adjusting the surface tension and contact angle of the ink include anionic surfactants such as fatty acid salts, higher alcohol sulfates, liquid fatty oil sulfates, alkylallylsulfonates, polyoxyethylene, etc. There are nonionic surfactants such as alkyl ethers, polyoxyethylene alkyl esters, and polyoxyethylene rilbitane alkyl esters, and one or more of these can be appropriately selected and used. The amount used varies depending on the dispersant, but is preferably 0.01 to 5% by mass relative to the total amount of ink. At this time, it is preferable to determine the amount of the activator added so that the surface tension of the recording liquid is 35 dyne / cm or more. This is because it is not preferable that the surface tension of the recording liquid shows a value smaller than this, such as printing due to wetting of the nozzle tip (deviation of the landing point of the recording liquid droplet on the recording paper) in the recording system as in the present invention. It will cause a situation.

  Examples of the pH adjuster include various organic amines such as diethanolamine and triethanolamine, inorganic alkali agents such as alkali metal hydroxides such as sodium hydroxide, lithium hydroxide and potassium hydroxide, organic acids and minerals. Acid.

  As a method for preparing the recording liquid of the present invention, first, a pigment is added to an aqueous solution containing at least a water-soluble resin and water, stirred, and then dispersed using a dispersion means described later, and centrifuged if necessary. Processing is performed to obtain a desired dispersion. Next, the above-mentioned components are added to this dispersion and stirred to obtain a recording liquid.

  In addition, amine may be added to increase the solubility of the resin. The timing of addition is the same as that of the dispersion resin. As amines added to the dispersion, organic amines such as monoethanolamine, diethanolamine, triethanolamine, aminomethylpropanol, and ammonia are preferable.

  Premixing may be performed for 30 minutes or more before the aqueous solution containing the pigment is dispersed. This premixing operation improves the wettability of the pigment surface and promotes the adsorption of the resin to the pigment surface.

  On the other hand, the disperser used in the present invention may be any disperser that is generally used, and examples thereof include a ball mill, a roll mill, and a sand mill. Among them, high-speed sand mills are preferable, and examples include super mills, sand grinders, bead mills, agitator mills, glen mills, dyno mills, pearl mills, cobol mills, DCP mills, cosmo mills, and pico mills (all trade names). Further, in the dispersion using a medium, there is a concern that an impurity component resulting from abrasion is mixed into the dispersion liquid depending on the type of the medium. For this reason, there may be a need to shorten the dispersion time when using the high-speed mill. Therefore, a high-pressure homogenizer, an ultrasonic homogenizer, a nanomizer, a clear mix, or the like may be used in combination as a medialess disperser, or may be used as a single disperser.

  In the present invention, as a method for obtaining a pigment having a desired particle size distribution, the size of the pulverized media of the disperser is decreased, the filling rate of the pulverized media is increased, the processing time is increased, and the discharge speed is decreased. A method such as classification using a pulverizing filter or a centrifuge is used. Or the combination of those methods is mentioned.

  The recording liquid of the present invention is particularly preferably used for an ink jet recording method in which droplets are ejected by the action of thermal energy, but it goes without saying that it can also be used as a piezo recording method.

Next, the best mode for carrying out the invention relating to the ink cartridge will be described.
FIG. 1 shows an ink jet printer apparatus (hereinafter referred to as “printer apparatus”) 1 using an ink cartridge of the present invention. The printer device 1 is a line-type printer device capable of so-called high-speed ejection, which prints images and characters by ejecting ink or the like onto the recording paper P traveling in a predetermined direction.

  The printer apparatus 1 is equipped with an inkjet printer head cartridge (hereinafter referred to as “head cartridge”) 3. The head cartridge 3 has a cartridge main body 21, and an ink cartridge 5 (described later) is attached to the cartridge main body 21. The head cartridge 3 is mounted from the upper surface side of the printer body 4, that is, from the direction of arrow A in FIG.

  The head cartridge 3 is provided with ejection means for ejecting ink with fine particles and ejecting ink in a droplet state onto the main surface of an object such as recording paper P to record images, characters, and the like. In the head cartridge 3, ink ejection ports (nozzles) are arranged in a substantially straight line in the width direction of the recording paper P, that is, in the direction of the arrow W in FIG. Discharged.

  As shown in FIG. 2, ink cartridges 5 y, 5 m, 5 c, and 5 k that are ink cartridges that serve as ink supply sources and contain ink 2 are detachably attached to the head cartridge 3. That is, the yellow ink cartridge 5y, the magenta ink cartridge 5m, the cyan ink cartridge 5c, and the black ink cartridge 5k.

  The ink cartridge 5 has a cartridge container 11 as shown in FIG. The cartridge container 11 includes an ink storage unit 12 that stores the ink 2, an ink supply unit 13 that supplies the ink 2 from the ink storage unit 12 to the cartridge main body 21 of the head cartridge 3, and air from the outside into the ink storage unit 12. The external communication hole 14 for taking in the air, the air introduction path 15 for introducing the air taken in from the external communication hole 14 into the ink containing portion 12, and the ink 2 between the external communication hole 14 and the air introduction path 15 temporarily. And a storage unit 16 for storing the product.

  As described above, the ink cartridge is not limited to one that separates each ink separately. In addition, all kinds of commonly used ink cartridges such as one in which a plurality of ink storage portions are integrated can be employed.

  Next, the best mode for carrying out the invention relating to the ink jet recording method will be described.

  FIG. 4 schematically shows the head cartridge 3 used in the ink jet recording method of the present invention. The ink 2 contained in the ink cartridge 5 is supplied to the connection unit 26 through the ink supply unit 13. The ink 2 is supplied to the ink flow path 52 of the ink discharge head 27 through the ink reservoir 31, the filter 33, the valve mechanism 34, and the ink supply port 51 that constitute the connection portion 26. Further, the ink 2 is supplied from the ink flow path 52 to the nozzle 55a.

  A head chip 53 is disposed in the ink discharge head 27, and nozzles 55a are arranged in parallel on the head chip 53 so as to form a substantially straight line in the width direction of the recording paper P, that is, the arrow W direction in FIG. Has been.

  As shown in FIG. 5A, the head chip 53 includes a substrate 54 serving as a base, a nozzle sheet 55 formed with a plurality of nozzles 55a, and a film 56 that partitions the substrate 54 and the nozzle sheet 55 for each nozzle 55a. An ink liquid chamber 57 that pressurizes the ink 2 supplied through the ink flow path 52, and a heating resistor 58 that heats the ink 2 supplied to the ink liquid chamber 57. Discharging means for discharging.

  The heating resistor 58 is disposed on the substrate 54 facing the ink liquid chamber 57 and is electrically connected to the control circuit of the substrate 54. The nozzle 55a is a minute hole opened in a circular shape in the nozzle sheet 55, and is disposed so as to face the heating resistor 58.

  In the head chip 53, the control circuit of the substrate 54 controls the heating resistor 58 and supplies a pulse current to the heating resistor 58. Thereby, the heating resistor 58 is rapidly heated. As a result, the ink 2 in contact with the surface of the heating resistor 58 is rapidly heated, and the temperature of the ink 2 rises beyond the normal boiling point and reaches a spontaneous nucleation temperature of about 330 ° C. This heating by the heating resistor 58 is a short time heating, so the temperature gradient in the ink liquid chamber 57 becomes extremely steep, and the ink 2 on the surface of the heating resistor 58 becomes a boiling state all at once, so-called film boiling. It becomes a state. Thereafter, active boiling continues inside the bubbles generated by boiling, and ink bubbles b grow as shown in FIG. 5B.

  Then, as shown in FIG. 5C, the ink 2 in the ink liquid chamber 57 jumps out of the nozzle 55a with the momentum of growth of the ink bubble b, and the ink bubble b is deprived of a large amount of heat of vaporization due to its expansion. Bubbles that drop in pressure rapidly contract. The ink 2 ejected from the nozzle 55a has its tail extended outside the nozzle 55a due to its inertia and the contraction of the ink bubbles b, and the ink droplet i is ejected from the nozzle 55a.

  Then, the same amount of ink 2 as that discharged from the nozzle 55a by the capillary force of the nozzle 55a trying to return to the original meniscus (the liquid level of the nozzle 55a) is supplied to the ink chamber 57 from the ink flow path 52. On the other hand, the ink bubbles b are further contracted by the inflow of the fresh ink 2 and eventually disappear.

  The above-described head chip 53 employs an electrothermal conversion method in which the ink 2 is ejected while being heated by the heating resistor 58, but is not limited to such a method, for example, an electromechanical conversion such as a piezoelectric element. An electromechanical conversion method in which droplets of ink 2 are electromechanically ejected by an element may be employed.

  From the above, according to the best mode for carrying out the present invention, in the inkjet recording liquid containing a pigment, a water-soluble resin, a water-soluble organic solvent, and water, the water-soluble resin is a polystyrene resin. Since it contains polystyrene-based modified product that is sulfonated and sodium polyacrylate, the aromatic of the polystyrene-based modified product has an affinity for the pigment, and the sulfonic acid or sulfonate of the polystyrene-based modified product is water or water-based By having an affinity for the solvent, the dispersion of the pigment is improved and the stability is also improved. Moreover, the dispersibility of a pigment improves by using sodium polyacrylate together with a polystyrene-type modified material. As a result, a novel inkjet recording liquid can be provided.

  Further, according to the best mode for carrying out the present invention, in an ink cartridge containing an inkjet recording liquid containing a pigment, a water-soluble resin, a water-soluble organic solvent, and water, the water-soluble resin is a polystyrene-based resin. Provided is an ink cartridge containing an inkjet recording liquid having good dispersibility of pigment and good stability since it contains a polystyrene-based modified product obtained by sulfonating a resin and sodium polyacrylate. As a result, a novel ink cartridge can be provided.

  Further, according to the best mode for carrying out the present invention, in the ink jet recording method for ejecting an ink jet recording liquid containing a pigment, a water soluble resin, a water soluble organic solvent, and water from a nozzle, the water soluble resin is used. Contains an polystyrene-modified product obtained by sulfonating a polystyrene-based resin and sodium polyacrylate, so that an ink jet recording method for discharging an ink jet recording liquid having good dispersibility of pigment and good stability is provided. provide. As a result, a novel ink jet recording method can be provided.

  The present invention is not limited to the best mode for carrying out the above-described invention, and various other configurations can be adopted without departing from the gist of the present invention.

  Next, specific examples of the present invention will be described. However, it goes without saying that the present invention is not limited to these examples.

  The polystyrene-based modified product used in this example is a copolymer of a styrene unit represented by Chemical Formula 5 or a copolymer of a styrene unit represented by Chemical Formula 5 and a unit other than styrene.

  The case where an organic pigment is used as the pigment will be described.

Comparative Example 1
The pigment ink was produced by dividing it into a process for producing a pigment dispersion and a process for producing a printable ink.
(Preparation of pigment dispersion)
Resin PS-1 (polystyrene-based modified product) described in Table 1 5 parts by mass Isopropyl alcohol 2 parts by mass Ion-exchanged water 79 parts by mass The above ingredients are mixed and heated to 70 ° C in a water bath to completely remove the resin. Dissolve in. To this solution, 14 parts by mass of quinacridone pigment No. 202 pigment (CROMOPHTAL RT355, manufactured by Ciba Specialty Chemicals) was added, premixed for 30 minutes, and then dispersed under the following conditions.
Dispersing machine: Cosmomill (manufactured by Eirich)
Dispersion media: Zirconium beads 0.3mm diameter Dispersion time: 3 hours

(Preparation of ink)
28 parts by mass of the above dispersion 10 parts by mass of glycerin 10 parts by mass of diethylene glycol 10 parts by mass Orphine E1010 (manufactured by Nissin Chemical) 1 part by mass 51 parts by mass of ion-exchanged water The above components are mixed and stirred for 1 hour, and subjected to a 3 μm filter treatment. Ink was obtained.

  Ejection stability is the on-demand type prototype multi-head that discharges the above ink by applying thermal energy to the ink in the recording head, and the ejection orifice diameter is 16μm, heater drive voltage is 11V, drive It was discharged under the condition of a frequency of 10 kHz. The delay of the driving signal of the driver was manipulated to move the ink droplet image on the monitor, and the ejection speed was calculated from the moving distance and the required delay time. As for the judgment of pass / fail, at the initial discharge speed and the speed after continuous discharge for 20 minutes, the initial 10 m / s or more and 20 minutes after 8 m / s or more (○), the initial 10 m / s or more and 20 minutes after 8 m / s or less (Δ), initial 10 m / s or less (×) was used. Here, it was assumed that “good” was satisfied.

  Scratch resistance after printing is evaluated by leaving the sample printed using the printer above at room temperature for 24 hours, and then visually observing the printing state when reciprocating 20 times with a JIS fastness tester with a load of 200 g. Judged. As the judgment of pass / fail, there were used no change after wiping (◎), almost no change (◯), slight deterioration / damaged (Δ), significant deterioration / damaged (×). Here, ◎, ○, and Δ were satisfied.

Comparative Example 2
An ink was prepared and evaluated in the same manner as in Comparative Example 1 except that the resin used in preparing the pigment dispersion was changed to PS-2 (polystyrene-based modified product) described in Table 1.

Comparative Example 3
An ink was prepared and evaluated in the same manner as in Comparative Example 1 except that the resin used in preparing the pigment dispersion was changed to PS-3 (polystyrene-based modified product) described in Table 1.

Comparative Example 4
An ink was prepared and evaluated in the same manner as in Comparative Example 1 except that the resin used for preparing the pigment dispersion was replaced with PS-4 (polystyrene-based modified product) described in Table 1.

Comparative Example 5
An ink was prepared and evaluated in the same manner as in Comparative Example 1 except that the resin used for preparing the pigment dispersion was changed to PS-5 (polystyrene-based modified product) described in Table 1.

Comparative Example 6
An ink was prepared and evaluated in the same manner as in Comparative Example 1 except that the resin used in preparing the pigment dispersion was changed to PS-6 (polystyrene-based modified product) described in Table 1.

Example 1
PS-1 and sodium polyacrylate described in Table 1 with a resin amount of 5 parts by mass used in the preparation of the pigment dispersion described in Comparative Example 1 as 100 (molecular weight of about 6000, trade name Julimer AC- 103 manufactured by Nippon Pure Chemical Co., Ltd.) was blended at a ratio of 90:10, and an ink was prepared and evaluated in the same manner as in Comparative Example 1 except that the two-component system was used.

Example 2
PS-1 and sodium polyacrylate described in Table 1 with a resin amount of 5 parts by mass used in the preparation of the pigment dispersion described in Comparative Example 1 as 100 (molecular weight of about 6000, trade name Julimer AC- 103 manufactured by Nippon Pure Chemical Co., Ltd.) was blended at a ratio of 70:30, and an ink was prepared and evaluated in the same manner as in Comparative Example 1 except that the two-component system was used.

Example 3
PS-1 and sodium polyacrylate described in Table 1 with a resin amount of 5 parts by mass used in the preparation of the pigment dispersion described in Comparative Example 1 as 100 (molecular weight of about 6000, trade name Julimer AC- 103 manufactured by Nippon Pure Chemical Co., Ltd.) was blended at a ratio of 50:50, and an ink was prepared and evaluated in the same manner as in Comparative Example 1 except that the two-component system was used.

Example 4
PS-1 and sodium polyacrylate described in Table 1 with a resin amount of 5 parts by mass used in the preparation of the pigment dispersion described in Comparative Example 1 as 100 (molecular weight of about 6000, trade name Julimer AC- Ink was prepared and evaluated in the same manner as in Comparative Example 1 except that Nippon Pure Chemical Co., Ltd.) was blended at a ratio of 30:70 and replaced with a two-component system.

Example 5
PS-1 and sodium polyacrylate described in Table 1 with a resin amount of 5 parts by mass used in the preparation of the pigment dispersion described in Comparative Example 1 as 100 (molecular weight of about 6000, trade name Julimer AC- Ink was prepared and evaluated in the same manner as in Comparative Example 1 except that Nippon Pure Chemical Co., Ltd.) was blended at a ratio of 10:90 and replaced with a two-component system.

Comparative Example 7
Similar to Comparative Example 1. Reprinted for comparison with blend system (Examples 1-5).

Comparative Example 8
An ink was prepared in the same manner as in Comparative Example 1 except that the resin used for preparing the pigment dispersion was replaced with sodium polyacrylate (molecular weight: about 6000, trade name: Jurimer AC-103, Nippon Pure Chemicals Co., Ltd.) Evaluation was performed.

Comparative Example 9
Low molecular weight type PS-1 and sodium polyacrylate described in Table 1 with 5 parts by mass of resin used in the preparation of the pigment dispersion described in Comparative Example 1 as 100 (molecular weight about 3000, commercial product) Ink was prepared and evaluated in the same manner as Comparative Example 1 except that the name Jurimer AC-107 manufactured by Nippon Pure Chemical Co., Ltd.) was blended at a ratio of 70:30 and replaced with a two-component system.

Comparative Example 10
Low molecular weight type PS-1 and sodium polyacrylate described in Table 1 with 5 parts by mass of resin used in the preparation of the pigment dispersion described in Comparative Example 1 as 100 (molecular weight about 3000, commercial product) Ink was prepared and evaluated in the same manner as in Comparative Example 1 except that the name Jurimer AC-107 manufactured by Nippon Pure Chemical Co., Ltd.) was blended at a ratio of 50:50 and replaced with a two-component system.

Comparative Example 11
The same as Comparative Example 1 except that the resin used for preparing the pigment dispersion was replaced with non-neutralized polyacrylic acid (molecular weight of about 5000, trade name: Jurimer AC-10S manufactured by Nippon Pure Chemical Co., Ltd.) An ink was prepared and evaluated.

 The above evaluation results are summarized in Table 2.

The results show the following.
In a recording liquid containing an organic pigment, a water-soluble resin, a water-soluble organic solvent, and water, at least one of the water-soluble resins contains a polystyrene-based modified product represented by Chemical Formula 5 obtained by sulfonated polystyrene-based resin. In addition, it can be seen that by containing and using sodium polyacrylate together, the ejection stability of the ink and the scratch resistance after printing are improved.

  Furthermore, in order to achieve the present invention at a higher level, the polystyrene-based modified product contains a styrene unit in a range of 30 to 100 mol% based on the total monomer units, or the polystyrene-based product. It can be seen that the modified product has a sulfonation rate in the range of 0.5 to 30 mol%, and the polymerization degree of the polystyrene-based modified product is more preferably in the range of 25 to 200.

  Furthermore, the blend ratio in which the polystyrene modified product and sodium polyacrylate are used in combination is preferably in the range of 10:90 to 90:10, preferably 30:70 to 90:10, when the amount of water-soluble resin added is 100. From the results of ejection stability and scratch resistance shown in Table 2, it can be seen that the range of 30:70 to 50:50 is more preferable.

  It can also be seen from the results of Examples 2 and 3 and Comparative Examples 9 and 10 that the molecular weight of sodium polyacrylate is preferably 6000 or more. Further, in Comparative Example 8 and Comparative Example 11, it can be seen that the neutralized type of polyacrylic acid and the non-neutralized type are clearly neutralized and have superior ejection stability.

  The case where carbon black is used as the pigment will be described.

Comparative Example 12
The pigment ink was produced by dividing it into a process for producing a pigment dispersion and a process for producing a printable ink.
(Preparation of pigment dispersion)
Resin PS-1 (polystyrene-based modified product) described in Table 1 6 parts by mass Isopropyl alcohol 2 parts by mass Ion-exchanged water 77 parts by mass The above components are mixed and heated to 70 ° C in a water bath to completely remove the resin. Dissolve in. To this solution, 15 parts by mass of carbon black (BLACK PEARLS 800, manufactured by Cabot) was added, premixed for 30 minutes, and then subjected to a dispersion treatment under the following conditions.
Dispersing machine: Cosmomill (manufactured by Eirich)
Dispersion media: Zirconium beads 0.3 mm diameter Dispersion time: 5 hours

(Preparation of ink)
34 parts by mass of the above dispersion 10 parts by mass of glycerin 10 parts by mass of diethylene glycol 10 parts by mass of Olphine E1010 (manufactured by Nissin Chemical) 0.5 parts by mass of ion-exchanged water 47.5 parts by mass Ink was obtained.

  The discharge stability is an on-demand type prototype multi-head that discharges the ink by applying thermal energy to the ink in the recording head to generate droplets. The discharge orifice diameter is 16 microns, the heater drive voltage is 11V, It was discharged under the condition of a driving frequency of 10 kHz. The delay of the driving signal of the driver was manipulated to move the ink droplet image on the monitor, and the ejection speed was calculated from the moving distance and the required delay time. As for the judgment of pass / fail, at the initial discharge speed and the speed after continuous discharge for 20 minutes, the initial 10 m / s or more and 20 minutes after 8 m / s or more (○), the initial 10 m / s or more and 20 minutes after 8 m / s or less (Δ), initial 10 m / s or less (×) was used. Here, it was assumed that “good” was satisfied.

  After printing, the scratch resistance was evaluated by leaving a sample printed on plain paper (Xerox P paper) using the above printer at room temperature for 24 hours, and then using a JIS fastness tester to wipe 10 times with a load of 500 g. The printing state at the time of reciprocation was judged visually. As the judgment of pass / fail, there were used no change after wiping (）), almost no change (◯), slight deterioration / powder fall (Δ), and significant deterioration / powder drop (x). Here, ◎, ○, and Δ were satisfied.

Comparative Example 13
An ink was prepared and evaluated in the same manner as in Comparative Example 12 except that the resin used in preparing the pigment dispersion was replaced with PS-2 (polystyrene-based modified product) described in Table 1.

Comparative Example 14
An ink was prepared and evaluated in the same manner as in Comparative Example 12 except that the resin used for preparing the pigment dispersion was changed to PS-3 (polystyrene modified product) described in Table 1.

Comparative Example 15
An ink was prepared and evaluated in the same manner as in Comparative Example 12 except that the resin used for preparing the pigment dispersion was replaced with PS-4 (polystyrene-based modified product) described in Table 1.

Comparative Example 16
An ink was prepared and evaluated in the same manner as in Comparative Example 12 except that the resin used in preparing the pigment dispersion was replaced with PS-5 (polystyrene-based modified product) described in Table 1.
Comparative Example 17
An ink was prepared and evaluated in the same manner as in Comparative Example 12, except that the resin used in preparing the pigment dispersion was replaced with PS-6 (polystyrene-based modified product) described in Table 1.

Example 6
PS-1 and sodium polyacrylate described in Table 1 with a resin amount of 6 parts by mass used in the preparation of the pigment dispersion described in Comparative Example 12 as 100 (molecular weight of about 6000, trade name Julimer AC- 103 manufactured by Nippon Pure Chemical Co., Ltd.) was blended at a ratio of 90:10, and an ink was prepared and evaluated in the same manner as in Comparative Example 12 except that the two-component system was used.

Example 7
PS-1 and sodium polyacrylate described in Table 1 with a resin amount of 6 parts by mass used in the preparation of the pigment dispersion described in Comparative Example 12 as 100 (molecular weight of about 6000, trade name Julimer AC- Ink was produced and evaluated in the same manner as in Comparative Example 12 except that Nippon Pure Chemical Co., Ltd.) was blended at a ratio of 70:30 and replaced with a two-component system.

Example 8
PS-1 and sodium polyacrylate described in Table 1 with a resin amount of 6 parts by mass used in the preparation of the pigment dispersion described in Comparative Example 12 as 100 (molecular weight of about 6000, trade name Julimer AC- 103 manufactured by Nippon Pure Chemical Co., Ltd.) was blended at a ratio of 50:50, and an ink was prepared and evaluated in the same manner as in Comparative Example 12 except that the two-component system was used.

Example 9
PS-1 and sodium polyacrylate described in Table 1 with a resin amount of 6 parts by mass used in the preparation of the pigment dispersion described in Comparative Example 12 as 100 (molecular weight of about 6000, trade name Julimer AC- Ink was produced and evaluated in the same manner as in Comparative Example 12 except that Nippon Pure Chemical Co., Ltd.) was blended at a ratio of 30:70 and replaced with a two-component system.

Example 10
PS-1 and sodium polyacrylate described in Table 1 with a resin amount of 6 parts by mass used in the preparation of the pigment dispersion described in Comparative Example 12 as 100 (molecular weight of about 6000, trade name Julimer AC- Ink was produced and evaluated in the same manner as in Comparative Example 12, except that Nippon Pure Chemical Co., Ltd.) was blended at a ratio of 10:90 and replaced with a two-component system.

Example 11
PS-1 and sodium polyacrylate described in Table 1 with a resin amount of 6 parts by mass used in the preparation of the pigment dispersion described in Comparative Example 12 as 100 (molecular weight of about 6000, trade name Julimer AC- 103 Nippon Pure Chemical Co., Ltd.) was blended at a ratio of 50:50, and the pigment dispersion was changed from the dispersion described in Comparative Example 12 to a commercially available self-dispersing carbon dispersion (CABOJET). -300: An ink was prepared and evaluated in the same manner as in Comparative Example 12, except that an equal amount of the pigment was replaced with a dispersion of 15 wt% pigment concentration manufactured by CABOT.

Comparative Example 18
According to Comparative Example 12. Reprinted for comparison with blend system (Examples 6-11).

Comparative Example 19
An ink was prepared in the same manner as in Comparative Example 12, except that the resin used for preparing the pigment dispersion was replaced with sodium polyacrylate (molecular weight: about 6000, trade name: Jurimer AC-103 manufactured by Nippon Pure Chemical Co., Ltd.) Evaluation was performed.

Comparative Example 20
PS-1 and sodium polyacrylate low molecular weight types described in Table 1 with a resin amount of 6 parts by mass used in the preparation of the pigment dispersion described in Comparative Example 12 as 100 (molecular weight of about 3000, commercial product) Ink was produced and evaluated in the same manner as in Comparative Example 12 except that the name Jurimer AC-107 manufactured by Nippon Pure Chemical Co., Ltd.) was blended at a ratio of 70:30 and replaced with a two-component system.

Comparative Example 21
PS-1 and sodium polyacrylate low molecular weight types described in Table 1 with a resin amount of 6 parts by mass used in the preparation of the pigment dispersion described in Comparative Example 12 as 100 (molecular weight about 3000, product Ink was prepared and evaluated in the same manner as Comparative Example 12, except that the name Jurimer AC-107 manufactured by Nippon Pure Chemical Co., Ltd.) was blended at a ratio of 50:50 and replaced with a two-component system.

Comparative Example 22
The same as Comparative Example 12 except that the resin used for preparing the pigment dispersion was replaced with a non-neutralized type of polyacrylic acid (molecular weight: about 5000, trade name: Jurimer AC-10S manufactured by Nippon Pure Chemical Co., Ltd.) An ink was prepared and evaluated.
The above evaluation results are summarized in Table-3.

The results show the following.
In a recording liquid containing carbon black, a water-soluble resin, a water-soluble organic solvent, and water, at least one of the water-soluble resins contains a polystyrene-based modified product represented by Chemical Formula 5 in which a polystyrene-based resin is sulfonated. In addition, it can be seen that by containing and using sodium polyacrylate together, the ejection stability of the ink and the scratch resistance after printing are improved.

  Furthermore, in order to achieve the present invention at a higher level, the polystyrene-based modified product contains a styrene unit in a range of 30 to 100 mol% based on the total monomer units, or the polystyrene-based product. It can be seen that the modified product has a sulfonation rate in the range of 0.5 to 30 mol%, and the polymerization degree of the polystyrene-based modified product is more preferably in the range of 25 to 200.

  Furthermore, the blend ratio in which the polystyrene modified product and sodium polyacrylate are used in combination is preferably in the range of 10:90 to 90:10, preferably 30:70 to 90:10, when the amount of water-soluble resin added is 100. From the results of ejection stability and scratch resistance shown in Table 3, it can be seen that the range of 30:70 to 50:50 is more preferable.

  Moreover, it can be seen from the results of Examples 7 and 8 and Comparative Examples 20 and 21 that the molecular weight of sodium polyacrylate is preferably 6000 or more. Further, in Comparative Examples 19 and 22, it can be seen that the neutralized type of polyacrylic acid and the non-neutralized type are clearly neutralized and have superior discharge stability.

  Even if the carbon black is changed from the polymer dispersion type as in Comparative Example 12 to the self-dispersion type carbon, the effect does not change as seen from the results of Example 8 and Example 11, and it is also effective for the self-dispersion type carbon. It can be seen that it can be used.

FIG. 2 is a schematic perspective view illustrating an example of an ink cartridge that stores ink according to the present invention and a configuration of a printer apparatus including the ink cartridge. It is a schematic perspective view which shows an example of the ink cartridge which accommodates the ink by this invention. It is a schematic sectional drawing which shows the structure of an example of the ink cartridge by this invention. FIG. 2 is a schematic diagram for explaining an ink jet recording method according to the present invention. 5A to 5C are schematic views illustrating the principle of an example of the ink jet recording method according to the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Printer apparatus, 2 ... Ink, 3 ... Head cartridge, 4 ... Printer main body, 5 ... Ink cartridge, 5y, 5m, 5c, 5k ... Ink cartridge, 11 ... Cartridge container, 12 ... ink container, 13 ... ink supply unit, 14 ... external communication hole, 15 ... air introduction path, 16 ... reservoir, 21 ... cartridge body, 26: Connection unit, 27: Ink ejection head, 31 ... Ink reservoir, 33 ... Filter, 34 ... Valve mechanism, 51 ... Ink supply port, 52 ... Ink flow Path, 53 ... Head chip, 54 ... Substrate, 55 ... Nozzle sheet, 55a ... Nozzle, 56 ... Film, 57 ... Ink liquid chamber, 58 ... Heating resistor

Claims (24)

In an inkjet recording liquid containing a pigment, a water-soluble resin, a water-soluble organic solvent, and water,
The water-soluble resin contains a polystyrene-based modified product obtained by sulfonating a polystyrene-based resin, and sodium polyacrylate. The inkjet recording liquid according to claim 1, wherein the pigment is an organic pigment or carbon black. 2. The inkjet recording according to claim 1, wherein the polystyrene-based modified product is a copolymer of a styrene unit represented by Chemical Formula 1 or a copolymer of a styrene unit represented by Chemical Formula 1 and a unit other than styrene. liquid.

The inkjet recording liquid according to claim 3, wherein the polystyrene-based modified product contains styrene units in a range of 30 to 100 mol% with respect to all monomer units. The inkjet recording liquid according to claim 3, wherein the polystyrene-based modified product contains sulfonated styrene units in a range of 0.5 to 30 mol% with respect to all monomer units. 4. The inkjet recording liquid according to claim 3, wherein the polystyrene-based modified product has a degree of polymerization in the range of 25 to 200. 2. The ink jet recording liquid according to claim 1, wherein the blend ratio of the polystyrene-based modified product and sodium polyacrylate is in the range of 10:90 to 90:10. 2. The ink jet recording liquid according to claim 1, wherein the weight average molecular weight Mw of the sodium polyacrylate is in the range of 600 to 10,000. In an ink cartridge containing an inkjet recording liquid containing a pigment, a water-soluble resin, a water-soluble organic solvent, and water,
The water-soluble resin contains a polystyrene-based modified product obtained by sulfonating a polystyrene-based resin, and sodium polyacrylate. The ink cartridge according to claim 9, wherein the pigment is an organic pigment or carbon black. The ink cartridge according to claim 9, wherein the polystyrene-based modified product is a copolymer of a styrene unit represented by Chemical Formula 2 or a copolymer of a styrene unit represented by Chemical Formula 2 and a unit other than styrene.

The ink cartridge according to claim 11, wherein the polystyrene-based modified product contains styrene units in a range of 30 to 100 mol% with respect to all monomer units. The ink cartridge according to claim 11, wherein the polystyrene-based modified product contains a sulfonated styrene unit in a range of 0.5 to 30 mol% with respect to all monomer units. The ink cartridge according to claim 11, wherein the polystyrene-based modified product has a polymerization degree in a range of 25 to 200. The ink cartridge according to claim 9, wherein a blend ratio of the polystyrene-based modified product and sodium polyacrylate is in the range of 10:90 to 90:10. The ink cartridge according to claim 9, wherein the weight average molecular weight Mw of the sodium polyacrylate is in the range of 6000 to 10,000. In an inkjet recording method for ejecting an inkjet recording liquid containing a pigment, a water-soluble resin, a water-soluble organic solvent, and water from a nozzle,
The water-soluble resin contains a polystyrene-based modified product obtained by sulfonating a polystyrene-based resin, and sodium polyacrylate. The inkjet recording method according to claim 17, wherein the pigment is an organic pigment or carbon black. 18. The inkjet recording method according to claim 17, wherein the polystyrene-based modified product is a copolymer of a styrene unit represented by Chemical Formula 3 or a copolymer of a styrene unit represented by Chemical Formula 3 and a unit other than styrene. .

The inkjet recording method according to claim 19, wherein the polystyrene-based modified product contains styrene units in a range of 30 to 100 mol% with respect to all monomer units. The inkjet recording method according to claim 19, wherein the polystyrene-based modified product contains a sulfonated styrene unit in a range of 0.5 to 30 mol% with respect to all monomer units. The inkjet recording method according to claim 19, wherein the polystyrene-based modified product has a degree of polymerization in a range of 25 to 200. The inkjet recording method according to claim 17, wherein a blend ratio of the polystyrene-based modified product and sodium polyacrylate is in the range of 10:90 to 90:10. The inkjet recording method according to claim 17, wherein the weight average molecular weight Mw of the sodium polyacrylate is in the range of 6000 to 10,000.

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