JP2007191556A - Ink for recording, ink cartridge, method for inkjet recording and apparatus for inkjet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide ink, etc., for recording affording an image having excellent image density, saturation and image fastness and having excellent drying speed and responsiveness to high-speed printing and good jetting stability from a nozzle. <P>SOLUTION: The ink for recording comprises at least a water-dispersible colorant, a water-dispersible resin, a wetting agent and water. The water-dispersible colorant is a pigment dispersion containing a pigment, a pigment dispersing agent and a polymer dispersion stabilizer. Furthermore, the polymer dispersion stabilizer is either one of an α-olefin-maleic anhydride copolymer and a mixture of the α-olefin-maleic anhydride copolymer with at least any one kind selected from a styrene-acrylic copolymer, a water-soluble polyurethane resin and a water-soluble polyester resin. The content of the wetting agent is 20-35 mass% and the ratio (A/B) of the solid content (A) of the water-dispersible resin in the recording ink to the solid content (B) of the pigment in the water-dispersible colorant is 2-8. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a recording ink suitable for inkjet recording, an ink cartridge using the recording ink, an inkjet recording method, and an inkjet recording apparatus.

  Inkjet recording apparatuses are known as image forming apparatuses such as printers, facsimiles, and copying machines. Such an ink jet recording apparatus performs recording by ejecting ink onto a recording medium such as a recording head. Since the image forming process is simple, the apparatus is easy to simplify, and the heating process is not required. Gentle, high-definition images can be recorded at high speed, running costs are low, noise is low, and it is easy to record color images using multi-color inks. ing.

As an ink used for such ink jet recording, water is a main component, and a coloring agent, a wetting agent such as glycerin, a penetrating agent that controls permeability to recording paper, a surfactant, and other additives. A water-based ink containing is generally used for home and office applications.
Inkjet recording using the water-based ink is fixed when liquid ink penetrates into the recording medium, so an ink jet dedicated paper with improved absorption characteristics, a function of fixing colored components to the paper surface, and a function of protecting colored components has been developed. Has been. However, inkjet paper is expensive because it undergoes a multi-stage coating process after paper making, and recyclability is inferior to plain paper because it uses a lot of processing chemicals. Therefore, it is desired to obtain sufficient image quality on plain paper.
Plain paper is inferior in ink absorbability to inkjet special paper and does not assist ink performance like special paper, so (1) feathering, (2) bleeding, (3) density reduction, (4) Decrease in color developability, (5) Decrease in water resistance, (6) Decrease in light resistance, (7) Decrease in gas resistance, (8) Decrease in fixability, (9) Occurrence of ink breakthrough And the like, and solving these problems is an important issue for inkjet recording on plain paper.

  In recent years, pigment dispersibility has been improved and particle size has been reduced, and pigments are increasingly used in inkjet inks. To improve the dispersibility of pigments, not only pigment dispersion using surfactants and water-soluble resins as in the past, but also hydrophilicity is imparted by surface modifications such as oxidation treatment, sulfonation treatment, and graft polymerization treatment on the pigment surface. In order to improve the self-dispersion stability of the pigment. By using such a pigment, the above (5), (6), and (7) can be improved. However, the pigment is inferior in density and color developability compared to the dye, and the ejection stability. Also, it is inferior to dye ink in terms of reliability such as long-term storage and redispersibility. Therefore, when a pigment is used as a colorant, it is a problem to improve the ink density, color developability, and reliability. In order to cope with these problems, many inks for ink jet recording using colored polymer particles, in particular, emulsions of polyester-based or vinyl-based polymer particles have been reported (for example, see Patent Document 1 and Non-Patent Document 1). ). These include ink containing a colorant-encapsulating resin dispersion in which a colorant is insoluble in water and encapsulated in a dispersible resin. In addition, when a color organic pigment is used as a colorant, it is known that a conventionally known ink formulation is superior in image density and color reproducibility on plain paper to a pigment ink using a water-soluble dispersant.

Conventionally, techniques for controlling the penetration of ink into paper have been studied in order to reduce feathering and bleeding, increase print density and color developability, and suppress back-through. Among commercially available inkjet inks, there is a super-penetrating ink in which the surface tension of the ink is adjusted to be lower than 35 mN / m and the permeability to paper is enhanced. Such inks are highly effective in reducing bleeding and have good drying properties on plain paper printing, but have the disadvantages that feathering is likely to occur and the printing density is low and the character quality is likely to deteriorate. On the other hand, a slowly penetrating ink that keeps the ink on the surface of the print surface by adjusting the surface tension of the ink to be higher than 35 mN / m and slowing the penetration into the paper has been put on the market, lowering the feathering, improving the print density, Highly effective in improving color development and reducing back-through.
However, as a result of decreasing the permeability to paper, the drying property after printing on plain paper is remarkably deteriorated, resulting in deterioration of fixing property and bleeding between colors when multiple colors are used. In view of this, a technique has been developed and used that suppresses bleeding between colors by using an ink set in which a slow penetrating ink and a super penetrating ink are combined, thereby ensuring image quality. However, when double-sided printing is performed using a slowly penetrating ink, it is necessary to wait for the ink to dry after printing, resulting in a deterioration in productivity of double-sided printing. In addition, in order to improve the drying property of the ink, a printing device having a device that heats the paper surface with a heater before and after printing to accelerate the drying of the ink has been proposed and is on the market (for example, see Patent Document 2). . However, in these proposals, since the part to be heated is added, the apparatus is enlarged and complicated, and energy is wasted for heating, so the advantages of the ink jet recording method are lost. Yes.

In addition to the above, inkjet inks have been studied in a direction that combines reliability improvement and image quality improvement. Many inkjet inks are designed in such a way as to suppress the increase in viscosity as much as possible in order to prevent clogging of the nozzles of the head. For example, Patent Document 3 discloses that the aggregation of pigments is prevented from suppressing the spread of the ink by making the viscosity change when the ink is concentrated twice within 10 times and the particle size change within 3 times. It is said that it can prevent omission. However, it is difficult to form high quality on plain paper with this ink.
Patent Document 4 proposes an ink in which the residual amount after evaporation of volatile components in the ink is a liquid, and the viscosity is within 10 times the initial viscosity. However, this proposed ink is a dye ink and has high reliability, but still has poor image quality on plain paper.
Patent Document 5 proposes an ink having an ink viscosity of 600 times or less of the viscosity before evaporation when moisture is evaporated in an environment of 60 ° C. However, this proposed ink is also a dye ink, and adding a water-soluble polymer balances the reliability of the ink with the durability of the image quality, but there remains a problem with water resistance.
Patent Document 6 discloses that an ink having a viscosity of 5 to 15 mPa · s is necessary to ensure high image quality. In this proposal, it is described that a specific compound should be added as a viscosity adjusting agent for adjusting the initial evaporation rate for ensuring reliability and adjusting the viscosity. It can be said that it is a solution to 3) and (4). However, in this proposal, there is no description about the stability of the particle size of the pigment to be used, and it is said that there is reliability after being left for 24 hours. However, depending on the configuration of the ejected head and the size of the nozzle diameter, If left untreated for a long time, the ink formulation is inferior in reliability.

  As described above, in order to ensure high-speed and high-quality printing quality, it is necessary to use high-viscosity ink. However, it is difficult to ensure reliability of high-viscosity ink.

  For the purpose of improving image quality, Patent Documents 7 and 8 disclose a method of adding a water-insoluble resin to pigment ink. In Patent Document 9, the ratio of pigment to resin emulsion is in the range of 1: 0.1 to 1: 1, and the average particle size of the coloring component is 0.3 to 1.2 μm. A technique for improving the image quality is shown. Thus, in the ink to which the resin emulsion is added, bleeding can be suppressed and feathering can be suppressed, but the image density is insufficient and the reliability as an inkjet ink is not sufficient. Further, Patent Document 10 discloses an ink that has a minimum film forming temperature of 40 ° C. or higher for an ink to which a water-insoluble resin is added, and Patent Document 11 has an improvement on the reliability of an ink that has a particle size of an added emulsion of 50 nm or less. Although measures are disclosed, there is room for improvement in reliability, and the obtained image quality is not sufficient. Patent Document 12 discloses improvement in printing unevenness by using an ink containing a pigment, a saccharide or a derivative thereof, a polyol having 5 or more hydroxyl groups, and a resin emulsion. However, this ink has low penetrability with respect to plain paper and has problems such as occurrence of feathering and bleeding between colors, deterioration of fixability, and slow drying time. Patent Document 13 discloses an ink having a solid content of 1.0 to 16% by mass comprising a water-dispersible resin and a self-dispersing pigment, and describes an improvement in image quality on plain paper. . According to this proposal, the water resistance is improved as compared with the dye, but the image holding performance with respect to a marker pen often used in plain paper is not sufficient.

  Further, when the pigment dispersion and the resin emulsion are added to the ink, the solid content is increased and the ink viscosity is increased. For example, Patent Document 14 and Patent Document 15 propose an ink formulation in which a viscosity increase is small even when the solid content is increased by adding a resin that forms a micelle aggregate to the ink. However, these proposals have insufficient permeability on plain paper and have a problem in recording image quality. The permeability to paper is explained by capillary absorption represented by the Lucas-Washburn equation. However, the higher the viscosity, the lower the surface tension and the contact angle between the paper and the ink, the lower the sufficient permeability. Further, Patent Document 16 and Patent Document 17 propose that polyhydric alcohol alkyl ether is used for high solid content ink to improve the permeability, but the solid content increases and the viscosity is increased. When it rises, there is a problem that sufficient permeability cannot be obtained and the image quality is lowered.

  Silicone surfactants and fluorosurfactants are known to improve permeability even in trace amounts, and their use is being studied. For example, Patent Document 18 and Patent Document 19 propose an inkjet ink to which a fluorinated surfactant is added, and Patent Document 20 and Patent Document 21 propose an ink containing a pigment dispersion and a fluorinated surfactant, respectively. Yes. Further, Patent Document 22 proposes an improvement in image quality by using an ink having a viscosity of 5 mPa · s or more containing a polymer emulsion obtained by adding a water-insoluble or hardly soluble coloring material to a fluorosurfactant and polymer fine particles. However, in these proposals, it is known that the hue changes due to an increase in the solid content of the pigment in the ink, and it is difficult to obtain a preferable hue with a high-concentration pigment. There is a problem that it is difficult to say that the fixing property is sufficient.

JP 2000-191972 A JP 55-69464 A JP 2002-337449 A JP 2000-095983 A Japanese Patent Laid-Open No. 9-111166 JP 2001-262025 A JP 55-157668 A Japanese Examined Patent Publication No. 62-1426 JP-A-4-332774 Japanese Patent No. 2867491 JP-A-4-18462 Japanese Patent No. 3088588 JP 2004-35718 A JP 2004-99800 A Japanese Patent No. 3088588 JP 2004-155867 A JP 2004-203903 A Japanese Patent No. 2675001 Japanese Patent No. 2667401 JP-A-4-21478 JP 2003-277658 A JP 2003-226827 A "Technology and application development of functional pigments" issued by CMC Co., Ltd.

  This invention is made | formed in view of this present condition, and makes it a subject to solve the said various problems in the past and to achieve the following objectives. That is, the present invention improves the image quality for plain paper, in particular, the so-called white spot, and provides an image having excellent image density, saturation, and image fastness (water resistance, light resistance, etc.), and printing. Recording paper with excellent beading and drying characteristics, excellent drying speed, high-speed printing compatibility, good ejection stability from nozzles, ink cartridges using the recording ink, inkjet recording method, It is another object of the present invention to provide an ink jet recording apparatus.

Means for solving the problems are as follows. That is,
<1> A recording ink containing at least a water-dispersible colorant, a water-dispersible resin, a wetting agent, and water,
The water dispersible colorant is a pigment dispersion containing a pigment, a pigment dispersant, and a polymer dispersion stabilizer,
The polymer dispersion stabilizer is an α-olefin-maleic anhydride copolymer represented by the following structural formula (1), the α-olefin-maleic anhydride copolymer, and a styrene-acrylic copolymer. Any one of at least one mixture selected from water-soluble polyurethane resins and water-soluble polyester resins,
The content of the wetting agent in the recording ink is 20 to 35% by mass,
Ratio (A / B) of solid content (A) of the water-dispersible resin in the recording ink and solid content (B) of the pigment in the water-dispersible colorant in the recording ink Is a recording ink characterized in that it is 2-8.
However, in said structural formula (1), R represents an alkyl group. n shows the number of 30-100.
<2> A recording ink containing at least a water-dispersible colorant, a water-dispersible resin, a wetting agent, and water,
The water dispersible colorant is a pigment dispersion containing a pigment and a polymer dispersion stabilizer,
The pigment is a self-dispersing pigment having at least one hydrophilic group on the surface and exhibiting at least one of water dispersibility and water solubility in the absence of a dispersant,
The polymer dispersion stabilizer is an α-olefin-maleic anhydride copolymer represented by the following structural formula (1), the α-olefin-maleic anhydride copolymer, and a styrene-acrylic copolymer. Any one of at least one mixture selected from water-soluble polyurethane resins and water-soluble polyester resins,
The content of the wetting agent in the recording ink is 20 to 35% by mass,
Ratio (A / B) of solid content (A) of the water-dispersible resin in the recording ink and solid content (B) of the pigment in the water-dispersible colorant in the recording ink Is a recording ink characterized in that it is 2-8.
However, in said structural formula (1), R represents an alkyl group. n shows the number of 30-100.
<3> The recording ink according to any one of <1> to <2>, wherein the total content of the water-dispersible colorant and the water-dispersible resin is 12 to 40% by mass with respect to the total amount of the recording ink. .
<4> The recording ink according to any one of <1> to <3>, wherein the α-olefin-maleic anhydride copolymer has a weight average molecular weight of 20,000 or less.
<5> The α-olefin-maleic anhydride copolymer has an acid value of 100 to 400 mgKOH / g, and is used by being dissolved in either an alkali solution or an aqueous alkali solution equal to or more than the acid value. The recording ink according to any one of <1> to <4>.
<6> For recording according to any one of <1> and <3> to <5>, wherein the pigment dispersant is any one of an anionic surfactant and a nonionic surfactant having an HLB value of 10 to 20 Ink.
<7> The nonionic surfactant having an HLB value of 10 to 20 is any one of polyoxyethylene-β-naphthyl ether, polyoxyethylene lauryl ether, and polyoxyethylene styrene phenyl ether. It is a recording ink.
<8> From the above <1>, wherein the water-dispersible resin is any one of a polyester resin, a polyurethane resin, an acrylic resin, and an acrylic silicone resin, and the minimum film-forming temperature of the water-dispersible resin is 30 ° C. or less. <7> The recording ink according to any one of the above.
<9> The above <1> to <8>, wherein the wetting agent is at least one selected from glycerin, diethylene glycol, triethylene glycol, 1,3-butanediol, and 3-methyl-1,3-butanediol. The recording ink according to any one of the above.
<10> The surfactant according to any one of <1> to <9>, which contains a surfactant and the surfactant contains at least one selected from silicone surfactants and fluorine surfactants. Recording ink.
<11> The recording ink according to any one of <1> to <10>, wherein the viscosity at 25 ° C is 5 to 20 mPa · s, and the static surface tension at 25 ° C is 35 mN / m or less. is there.
<12> An ink cartridge comprising the recording ink according to any one of <1> to <11> contained in a container.
<13> An inkjet including at least an ink flying step of recording an image by applying a stimulus to the recording ink according to any one of <1> to <11> and causing the recording ink to fly. It is a recording method.
<14> The inkjet recording method according to <13>, wherein the stimulus is at least one selected from heat, pressure, vibration, and light.
<15> Inkjet comprising at least ink flying means for recording an image by applying a stimulus to the recording ink according to any one of <1> to <11> and causing the recording ink to fly. It is a recording device.
<16> The inkjet recording apparatus according to <15>, wherein the stimulus is at least one selected from heat, pressure, vibration, and light.
<17> An ink recorded matter comprising an image formed using the recording ink according to any one of <1> to <11> on a recording medium.

In the first embodiment, the recording ink of the present invention comprises at least a water-dispersible colorant, a water-dispersible resin, a wetting agent, and water.
The water dispersible colorant is a pigment dispersion containing a pigment, a pigment dispersant, and a polymer dispersion stabilizer,
The polymer dispersion stabilizer is an α-olefin-maleic anhydride copolymer represented by the above structural formula (1), the α-olefin-maleic anhydride copolymer, and a styrene-acrylic copolymer. Any one of at least one mixture selected from water-soluble polyurethane resins and water-soluble polyester resins,
The content of the wetting agent in the recording ink is 20 to 35% by mass,
Ratio (A / B) of solid content (A) of the water-dispersible resin in the recording ink and solid content (B) of the pigment in the water-dispersible colorant in the recording ink Is 2-8.
In the second embodiment, the recording ink of the present invention comprises at least a water-dispersible colorant, a water-dispersible resin, a wetting agent, and water.
The water dispersible colorant is a pigment dispersion containing a pigment and a polymer dispersion stabilizer,
The pigment is a self-dispersing pigment having at least one hydrophilic group on the surface and exhibiting at least one of water dispersibility and water solubility in the absence of a dispersant,
The polymer dispersion stabilizer is an α-olefin-maleic anhydride copolymer represented by the above structural formula (1), the α-olefin-maleic anhydride copolymer, and a styrene-acrylic copolymer. Any one of at least one mixture selected from water-soluble polyurethane resins and water-soluble polyester resins,
The content of the wetting agent in the recording ink is 20 to 35% by mass,
Ratio (A / B) of solid content (A) of the water-dispersible resin in the recording ink and solid content (B) of the pigment in the water-dispersible colorant in the recording ink Is 2-8.
In the recording inks according to the first and second aspects of the present invention, the image quality with respect to plain paper, in particular, so-called white spots are improved, and the image density, saturation, and image fastness are excellent. In addition, the beading and drying properties of the gloss paper for printing are excellent, the drying speed and high-speed printing are excellent, the ejection stability from the nozzle is good, and a high-quality image can be obtained.

  The ink cartridge of the present invention comprises the recording ink of the present invention contained in a container. The ink cartridge is suitably used for a printer using an ink jet recording method. When recording is performed using the ink contained in the ink cartridge, when printing on plain paper, so-called white spots are improved, and an image excellent in image density, saturation, and image fastness is obtained. Excellent beading and drying of gloss paper, excellent drying speed and high-speed printing, good ejection stability from nozzles, and clear and close-to-print image recording.

  The ink jet recording apparatus of the present invention comprises at least ink flying means for recording an image by applying energy to the recording ink of the present invention and causing the recording ink to fly. In the ink jet recording apparatus, the ink flying means applies energy to the recording ink of the present invention and causes the recording ink to fly to record an image. As a result, when printing on plain paper, so-called white spots are improved, an image having excellent image density, saturation, and image fastness is obtained, and furthermore, the beading and drying properties of printing gloss paper are excellent, Excellent drying speed and high-speed printing capability, good ejection stability from the nozzle, and a clear and close-to-printed image can be obtained.

  The ink jet recording method of the present invention includes at least an ink flying step of recording an image by applying energy to the recording ink of the present invention and causing the recording ink to fly. In the ink jet recording method, in the ink flying process, energy is applied to the recording ink of the present invention, and the recording ink is ejected to record an image. As a result, when printing on plain paper, so-called white spots are improved, an image having excellent image density, saturation, and image fastness is obtained, and furthermore, the beading and drying properties of printing gloss paper are excellent, Excellent drying speed and high-speed printing capability, good ejection stability from the nozzle, and a clear and close-to-printed image can be obtained.

  The ink recorded matter of the present invention has an image formed on the recording medium using the recording ink of the present invention. In the ink recorded matter of the present invention, when printing on plain paper, so-called white spots are improved, and an image excellent in image density, saturation, and image fastness is obtained. Excellent drying properties, excellent drying speed and high-speed printing, good ejection stability from the nozzles, and a clear image close to the printed matter is held on the recording medium.

  According to the present invention, conventional problems can be solved, the image quality for plain paper, in particular, the so-called white spot is improved, and the image has excellent image density, saturation, and image fastness (water resistance, light resistance, etc.). In addition, the printing gloss paper has excellent beading and drying properties, is excellent in drying speed and high-speed printing, and has good ejection stability from the nozzle, and the recording ink is used. An ink cartridge, an ink jet recording method, and an ink jet recording apparatus can be provided.

(Ink for recording)
The recording ink of the present invention contains at least a water-dispersible colorant, a water-dispersible resin, a wetting agent, and water, and contains a surfactant, a penetrating agent, and other components as necessary. Become.
In the first aspect of the recording ink, the water-dispersible colorant is a pigment dispersion containing a pigment, a pigment dispersant, and a polymer dispersion stabilizer.
In the second embodiment, the water-dispersible colorant is a pigment dispersion containing a self-dispersing pigment and a polymer dispersion stabilizer.

  In the present invention, the ratio of the solid content (A) of the water-dispersible resin in the recording ink to the solid content (B) of the pigment in the water-dispersible colorant in the recording ink. When (A / B) is 2 to 8, improvement in fixability and improvement in color developability can be obtained. By increasing the solid content of the water-dispersible resin to 3 times or 4 times the solid content of the pigment, the color developability and the image density increase effect can be obtained, but the color developability and the image density increase effect are saturated from around 8 times. From the standpoint of economy and economy, a range of 2 to 8 times the amount is preferable. Further, the total content of the water-dispersible colorant and the water-dispersible resin is preferably 12 to 40% by mass, and more preferably 15 to 35% by mass with respect to the total amount of the recording ink. When the total content is less than 12% by mass, the drying property on paper is inferior and the character quality on plain paper may be reduced. When the total content exceeds 40% by mass, the ink is easily dried on the nozzle surface. Thus, ejection failure may occur.

  Here, the solid content of the colorant and the water-dispersible resin can be measured by, for example, a method of separating only the colorant and the water-dispersible resin from the ink. Moreover, when the pigment is used as the colorant, the ratio of the colorant to the water-dispersible resin can be measured by evaluating the mass reduction rate by thermal mass spectrometry. If the molecular structure of the colorant is clear, use NMR for pigments and dyes, and use fluorescent X-ray analysis for inorganic pigments, metal-containing organic pigments, and metal-containing dyes in heavy metal atoms and molecular skeletons. It is possible to quantify the solid content of the colorant.

<Water dispersible colorant>
In the first embodiment, the water-dispersible colorant is a pigment dispersion containing a pigment, a pigment dispersant, and a polymer dispersion stabilizer.
In the second embodiment, the water-dispersible colorant is a pigment dispersion containing a pigment and a polymer dispersion stabilizer, and the pigment has at least one hydrophilic group on the surface, and no dispersant is present. It is a self-dispersing pigment that exhibits at least one of water dispersibility and water solubility below.

-Polymer dispersion stabilizer-
Examples of the polymer dispersion stabilizer include an α-olefin-maleic anhydride copolymer represented by the following structural formula (1), the α-olefin-maleic anhydride copolymer, and a styrene-acrylic copolymer. Any of at least one mixture selected from a coalescence, a water-soluble polyurethane resin and a water-soluble polyester resin is used.

In the structural formula (1), R represents an alkyl group, preferably having 6 to 25 carbon atoms, and more preferably having 6 to 22 carbon atoms. n shows the number of 30-100.
As the α-olefin-maleic anhydride copolymer represented by the structural formula (1), an appropriately synthesized product or a commercially available product may be used. Examples of the commercially available products include T-YP112, T-YP115, T-YP114, T-YP116 (all manufactured by Seiko PMC).

The α-olefin maleic anhydride copolymer represented by the structural formula (1) is a solid at room temperature and hardly dissolves in cold water. However, the α-olefin maleic anhydride copolymer effective for maintaining the dispersion state of the pigment dispersion uniformly finely dispersed in water by the pigment dispersant is equal to or more than the acid value of the copolymer ( Preferably, when used in an alkaline solution or an alkaline aqueous solution having an acid value of 1.0 to 1.5 times, the effect as a dispersion stabilizer is manifested.
Further, in order to dissolve the α-olefin-maleic anhydride copolymer with an alkali solution or an aqueous alkali solution, it can be easily dissolved by heating and stirring. However, when the olefin chain in the α-olefin-maleic anhydride copolymer is long, it is relatively difficult to dissolve, and insoluble matter may remain. The effect as an agent is not impaired.
Examples of the base in the alkali solution or aqueous alkali solution include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide; basic substances such as ammonia, triethylamine and morpholine; triethanolamine, diethanolamine, Examples thereof include alcohol amines such as N-methyldiethanolamine, 2-amino-2-ethyl-1,3-propanediol, and choline.

The acid value of the α-olefin-maleic anhydride copolymer is preferably 100 to 400 mgKOH / g. When the acid value is less than 100 mgKOH / g, the solubility of the alkaline solution may be inferior. When the acid value exceeds 400 mgKOH / g, the viscosity of the pigment is increased, and the discharge tends to be deteriorated. Stability may be easily reduced.
The α-olefin-maleic anhydride copolymer preferably has a mass average molecular weight of 20,000 or less, more preferably 5,000 to 20,000. If the mass average molecular weight is less than 5,000, the dispersion stability of the pigment dispersion may be reduced, and if it exceeds 20,000, the solubility of the alkaline solution may be inferior or the viscosity may be increased. There is.

The styrene-acrylic copolymer is used after being dissolved in an alkali solution or an aqueous alkali solution, and commercially available products can be used. For example, JC-05, JC-502 (both manufactured by Seiko PMC), ARUFON UC- 3900, ARUFON UC-3910, ARUFON UC-3920 (all manufactured by Toagosei Co., Ltd.) and the like.
A commercial item can be used as said water-soluble polyurethane resin, for example, Takerak W-5025, Takerak W-6010, Takerak W-5661 (all are Mitsui Takeda Chemical Co., Ltd.) etc. are mentioned.
Commercially available products can be used as the water-soluble polyester resin, such as Nichigo Polyester W-0030, Nichigo Polyester W-0005S30WO, Nichigo Polyester WR-961 (all manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd.), PES resin. A-210, pesresin A-520 (both manufactured by Takamatsu Yushi Co., Ltd.) and the like.
When the α-olefin-maleic anhydride copolymer (A) is mixed with at least one (B) selected from a styrene-acrylic copolymer, a water-soluble polyurethane resin and a water-soluble polyester resin, mixing is performed. The mass ratio (A: B) is preferably 10:90 to 90:10.

  The content of the polymer dispersion stabilizer is preferably 1 to 100 parts by mass (in terms of solid content) and more preferably 5 to 50 parts by mass with respect to 100 parts by mass of the pigment. When the content is less than 1 part by mass, the effect of stabilizing the dispersion may be lost. When the content exceeds 100 parts by mass, the ink viscosity becomes high and the discharge performance from the nozzle tends to be deteriorated. May be inferior.

-Pigment-
As the pigment, an organic pigment or an inorganic pigment can be used. In addition, although you may contain dye simultaneously for the purpose of color tone adjustment, it is possible to use within the range which does not degrade a weather resistance.
Examples of the inorganic pigment include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, and carbon black. Among these, carbon black is preferable. In addition, as said carbon black, what was manufactured by well-known methods, such as a contact method, a furnace method, and a thermal method, is mentioned, for example.

  Examples of the organic pigment include azo pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, and aniline black. Among these, azo pigments and polycyclic pigments are more preferable. Examples of the azo pigment include azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments. Examples of the polycyclic pigment include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinofullerone pigments. Examples of the dye chelates include basic dye chelates and acidic dye chelates.

There is no restriction | limiting in particular as a color of the said coloring agent, According to the objective, it can select suitably, For example, the thing for black, the thing for color, etc. are mentioned. These may be used alone or in combination of two or more.
Examples of the black color include carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, copper, iron (CI pigment black 11), oxidation, and the like. Examples thereof include metals such as titanium, organic pigments such as aniline black (CI pigment black 1), and the like.

  Examples of the color are C.I. I. Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104 , 408, 109, 110, 117, 120, 128, 138, 150, 151, 153, 183, C.I. I. Pigment orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48: 2, 48: 2 (Permanent Red 2B (Ca)), 48: 3, 48: 4, 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmine 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81, 83, 88, 101 (Bengara), 104, 105, 106, 108 ( Cadmium red), 112, 114, 122 (quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, 219, C.I. I. Pigment violet 1 (rhodamine lake), 3, 5: 1, 16, 19, 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue), 15: 1, 15: 2, 15: 3 (phthalocyanine blue), 16, 17: 1, 56, 60, 63, C.I. I. Pigment green 1, 4, 7, 8, 10, 17, 18, 36, and the like.

The self-dispersing pigment of the second form is a surface modified so that at least one hydrophilic group is bonded to the surface of the pigment directly or via another atomic group. In the surface modification, a specific functional group (a functional group such as a sulfone group or a carboxyl group) is chemically bonded to the surface of the pigment, or at least one of hypohalous acid and a salt thereof is used. A method such as wet oxidation is used. Among these, a form in which a carboxyl group is bonded to the surface of the pigment and dispersed in water is particularly preferable. Since the pigment is thus surface-modified and the carboxyl group is bonded, not only the dispersion stability is improved, but also high-quality print quality is obtained and the water resistance of the recording medium after printing is further improved. To do.
In addition, since this form of ink has excellent redispersibility after drying, printing is suspended for a long period of time, and clogging does not occur even when the water content of the ink near the nozzles of the inkjet head evaporates. Good printing.
The volume average particle diameter of the self-dispersing pigment is preferably 0.01 to 0.16 μm in the ink.

For example, as the self-dispersing carbon black, those having ionicity are preferable, and those having an anionic charge or those charged in a cationic form are suitable.
Examples of the anionic hydrophilic group include —COOM, —SO ₃ M, —PO ₃ HM, —PO ₃ M ₂ , —SO ₂ NH ₂ , —SO ₂ NHCOR (where M is a hydrogen atom, an alkali metal) And R represents an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent. Among these, it is preferable to use those in which —COOM and —SO ₃ M are bonded to the surface of the color pigment.

  Further, “M” in the hydrophilic group includes, for example, lithium, sodium, potassium and the like as an alkali metal. Examples of the organic ammonium include mono to trimethyl ammonium, mono to triethyl ammonium, and mono to trimethanol ammonium. As a method of obtaining the anionically charged color pigment, as a method of introducing —COONa to the color pigment surface, for example, a method of oxidizing the color pigment with sodium hypochlorite, a method of sulfonation, a diazonium salt The method of making it react is mentioned.

  As the cationic hydrophilic group, for example, a quaternary ammonium group is preferable, and quaternary ammonium groups listed below are more preferable. In the present invention, any of these is bonded to the surface of carbon black. Suitable as a material.

  The method for producing the cationic self-dispersing carbon black to which the hydrophilic group is bonded is not particularly limited and may be appropriately selected depending on the intended purpose. For example, N-ethyl represented by the following structural formula An example of a method for bonding a pyridyl group is a method of treating carbon black with 3-amino-N-ethylpyridinium bromide.

The hydrophilic group may be bonded to the surface of carbon black via another atomic group. Examples of other atomic groups include an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent. Specific examples of the case where the above hydrophilic group is bonded to the surface of carbon black through another atomic group include, for example, —C ₂ H ₄ COOM (where M represents an alkali metal or quaternary ammonium). ), - PhSO ₃ M (however, Ph is a phenyl group .M represents an alkali metal or quaternary _{ammonium), - C 5 H 10 NH} 3 + , and the like.

Moreover, the composite pigment which coat | covered the general organic pigment or the inorganic pigment particle | grain with the organic pigment or carbon black can be used conveniently. The composite pigment can be produced by a method of depositing an organic pigment in the presence of inorganic pigment particles, a mechanochemical method of mechanically mixing and grinding an inorganic pigment and an organic pigment, or the like. Further, if necessary, an adhesive layer between the inorganic pigment and the organic pigment can be improved by providing a layer of an organosilane compound formed from polysiloxane and alkylsilane between the inorganic pigment and the organic pigment.
Examples of the organic pigment include aniline black as a black pigment, and examples of color pigments include anthraquinone, phthalocyanine blue, phthalocyanine green, diazo, monoazo, pyranthrone, perylene, heterocyclic yellow, quinacridone, and (thio) indigoid. Can be mentioned. Among these, carbon black, phthalocyanine pigments, quinacridone pigments, monoazo yellow pigments, disazo yellow pigments, and heterocyclic yellow pigments are particularly excellent in terms of color development.

  Representative examples of the phthalocyanine blue include copper phthalocyanine blue or a derivative thereof (Pigment Blue 15: 3, 15: 4), aluminum phthalocyanine, and the like. Representative examples of the quinacridone include Pigment Orange 48, Pigment Orange 49, Pigment Red 122, Pigment Red 192, Pigment Red 202, Pigment Red 206, Pigment Red 207, Pigment Red 209, Pigment Violet 19, Pigment Violet 42, and the like. Is mentioned. Representative examples of the monoazo yellow include Pigment Yellow 74, Pigment Yellow 109, Pigment Yellow 128, and Pigment Yellow 151. Representative examples of the disazo yellow include pigment yellow 14, pigment yellow 16, and pigment yellow 17. Representative examples of the heterocyclic yellow include pigment yellow 117 and pigment yellow 138. Other color pigments are described in The Color Index, Third Edition (The Society of Dyer's and Colorists, 1982).

Examples of the inorganic pigment include titanium dioxide, silica, alumina, iron oxide, iron hydroxide, and tin oxide. The particle shape preferably has a small aspect ratio, and most preferably spherical. In addition, the color of the inorganic pigment is preferably transparent or white when the color material is adsorbed on the surface, but when the black color material is adsorbed on the surface, a black inorganic pigment may be used. I do not care. The primary particle diameter of the inorganic pigment particles is preferably 100 nm or less, and more preferably 5 to 50 nm.
The mass ratio between the inorganic pigment particles and the organic pigment or carbon black as a colorant is preferably 3: 1 to 1: 3, and more preferably 3: 2 to 1: 2. If the amount of the color material is small, the color developability and coloring power may be lowered, and if the amount of the color material is large, the transparency and color tone may be deteriorated.
Examples of colorant particles obtained by coating such inorganic pigment particles with an organic pigment or carbon black include silica / carbon black composite material manufactured by Toda Kogyo Co., Ltd., silica / phthalocyanine PB15: 3 composite material, silica / disazo yellow composite material, Since silica / quinacridone PR122 composite material has a small primary average particle size, it can be suitably used.
Here, when inorganic pigment particles having a primary particle size of 20 nm are coated with an equal amount of organic pigment, the primary particle size of this pigment is about 25 nm. If the primary particles can be dispersed using a suitable dispersant for this, a very fine pigment-dispersed ink having a dispersed particle diameter of 25 nm can be produced. In the composite pigment, not only the organic pigment on the surface contributes to the dispersion, but also the properties of the inorganic pigment at the center appear through a thin layer of organic pigment with a thickness of about 2.5 nm. The selection of pigment dispersants that can be made is also important.

-Pigment dispersant-
In the first embodiment, a pigment dispersant is contained. As the pigment dispersant, either an anionic surfactant or a nonionic surfactant having an HLB value of 10 to 20 is suitable.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetates, alkylbenzene sulfonates (eg, NH ₄ , Na, Ca, etc.), alkyl diphenyl ether disulfonates (eg, NH ₄ , Na, Ca, etc.), Dialkyl succinate sulfonic acid Na salt, naphthalene sulfonic acid formalin condensate Na salt, polyoxyethylene polycyclic phenyl ether sulfate ester salt (for example, NH ₄ , Na etc.), laurate, polyoxyethylene alkyl ether sulfate salt, oleic acid Examples include salt. Among these, dioctyl sulfosuccinic acid Na salt and polyoxyethylene styrene phenyl ether sulfonic acid NH ₄ salt are particularly preferable.

  Examples of the nonionic surfactant having an HLB value of 10 to 20 include polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, polyoxyethylene polycyclic phenyl ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene Examples include ethylene alkyl phenyl ether, polyoxyethylene alkyl amine, polyoxyethylene alkyl amide, and acetylene glycol. Among these, polyoxyethylene lauryl ether, polyoxyethylene-β-naphthyl ether, polyoxyethylene sorbitan monooleate, and polyoxyethylene styrene phenyl ether are particularly preferable.

  1-100 mass parts is preferable with respect to 100 mass parts of said pigments, and, as for content of the said dispersing agent, 10-50 mass parts is more preferable. If the content of the dispersant is small, the pigment cannot be sufficiently miniaturized. If the content is too large, excess components that are not adsorbed on the pigment affect the ink physical properties, causing image bleeding, water resistance, and abrasion resistance. It will cause deterioration of the sex.

  The pigment dispersion dissolves the pigment dispersant in an aqueous medium. Next, after adding the above pigments and thoroughly moistening, high-speed stirring by a homogenizer, a dispersing machine using balls such as a bead mill and a ball mill, a kneading dispersing machine using shearing force such as a roll mill, and ultrasonic dispersion It can be produced by a method using a machine or the like. However, after such a kneading and dispersing step, coarse particles are often contained, which may cause clogging of the ink jet nozzle and the supply path. Therefore, particles having a particle diameter of 1 μm or more using a filter or a centrifuge. Need to be removed.

The average particle diameter (D ₅₀ ) of the pigment dispersion is preferably 150 nm or less, more preferably 100 nm or less in the ink. When the average particle diameter (D ₅₀ ) exceeds 150 nm, the ejection stability is rapidly lowered, and nozzle clogging and ink bending are likely to occur. Further, when the average particle diameter (D ₅₀ ) is 100 nm or less, the ejection stability is improved and the chroma of the image is also improved.

  The pigment content in the pigment dispersion is preferably from 2 to 15% by mass, more preferably from 3 to 12% by mass, based on the total content of the recording ink. When the content is less than 2% by mass, the color developability and image density of the ink may be extremely low. When the content is more than 15% by mass, the ink is thickened and the discharge property is deteriorated. In addition, it is not preferable economically.

-Surfactant-
The surfactant is preferably selected from a silicone surfactant and a fluorosurfactant, which does not impair dispersion stability depending on the type of colorant or a combination of wetting agents, has a low surface tension, and has a high leveling property. At least one of these is preferred. Among these, a fluorine-based surfactant is particularly preferable.

The fluorine-based surfactant preferably has 2 to 16 carbon atoms substituted by fluorine, and more preferably 4 to 16 carbon atoms. When the fluorine-substituted carbon number is less than 2, the effect of fluorine may not be obtained, and when it exceeds 16, problems such as ink storage stability may occur.
Examples of the fluorosurfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic compound, a perfluoroalkyl phosphate compound, a perfluoroalkyl ethylene oxide adduct, and a perfluoroalkyl ether group in the side chain. And the polyoxyalkylene ether polymer compound. Among these, a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain is particularly preferable because of its low foaming property.

Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid, perfluoroalkyl sulfonate, and the like.
Examples of the perfluoroalkyl carboxylic compounds include perfluoroalkyl carboxylic acids and perfluoroalkyl carboxylic acid salts.
Examples of the perfluoroalkyl phosphate compound include perfluoroalkyl phosphate esters, perfluoroalkyl phosphate salts, and the like.
The polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain includes a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain, and a polyoxyalkylene ether having a perfluoroalkyl ether group in the side chain. Examples thereof include a sulfate salt of a polymer and a salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain.
As counter ions of salts in these fluorosurfactants, Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ , NH (CH ₂ CH ₂ OH) ₃ etc. are mentioned.

As said fluorosurfactant, what was synthesize | combined suitably may be used and a commercial item may be used.
Examples of the commercially available products include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by Asahi Glass Co., Ltd.), Fullrad FC. -93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M), MegaFuck F-470, F1405, F-474 (All manufactured by Dainippon Ink & Chemicals, Inc.), Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR (all manufactured by DuPont), FT-110, FT- 250, FT-251, FT-400S, FT-150, FT-400SW (all manufactured by Neos Co., Ltd.), PF-151N (manufactured by Omninova) Among these, FT-110, FT-250, FT-251, and FT-400S manufactured by Neos Co., Ltd. are particularly preferable because of their marked improvement in good print quality, particularly color development and leveling on paper. FT-150, FT-400SW, and OM-nova PF-151N are particularly preferable.
As specific examples of the fluorosurfactant, those represented by the following structural formula are suitable.

(1) Anionic fluorosurfactant
In the structural formula, Rf represents a mixture of fluorine-containing hydrophobic groups represented by the following structural formula. A is —SO ₃ X, —COOX, or —PO ₃ X (where X is a counter anion, specifically, a hydrogen atom, Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, , NH ₂ (CH ₂ CH ₂ OH) ₂ , or NH (CH ₂ CH ₂ OH) ₃ ).

In the structural formula, Rf ′ represents a fluorine-containing group represented by the following structural formula. X represents the same meaning as described above. n represents an integer of 1 or 2, and m represents 2-n.
However, in said structural formula, n represents the integer of 3-10.

In the structural formula, Rf ′ and X have the same meaning as described above.

In the structural formula, Rf ′ and X have the same meaning as described above.

(2) Nonionic fluorosurfactant
However, in the structural formula, Rf represents the same meaning as described above. n represents an integer of 5 to 20.

However, in the structural formula, Rf ′ represents the same meaning as described above. n represents an integer of 1 to 40.

(3) Amphoteric fluorosurfactant
However, in the structural formula, Rf represents the same meaning as described above.

(4) Oligomer type fluorosurfactant
In the structural formula, Rf ″ represents a fluorine-containing group represented by the following structural formula. L represents an integer of 0 to 10. X represents the same meaning as described above.
However, in said structural formula, n represents the integer of 1-4.

In the structural formula, Rf ″ represents the same meaning as described above. L represents an integer of 0 to 10, m represents an integer of 0 to 10, and n represents an integer of 0 to 10, respectively.

The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the purpose, and is preferably one that does not decompose even at a high pH. Examples include one-end-modified polydimethylsiloxane, side-chain both-end-modified polydimethylsiloxane, and the like. Particularly preferred.
As such a surfactant, an appropriately synthesized product or a commercially available product may be used.
Such commercially available products can be easily obtained from, for example, Big Chemie, Shin-Etsu Silicone, Toray Dow Corning Silicone.

The polyether-modified silicone surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the polyalkylene oxide structure represented by the following structural formula may be represented by the side chain of Si part of dimethylpolysiloxane. And the like, and the like.
However, m, n, a, and b represent an integer in the said structural formula. R and R ′ represent an alkyl group or an alkylene group.

  Commercially available products can be used as the polyether-modified silicone compound, and examples thereof include KF-618, KF-642, KF-643 (all manufactured by Shin-Etsu Chemical Co., Ltd.), and the like.

The content of the surfactant in the recording ink is preferably 0.01 to 3.0% by mass, and more preferably 0.5 to 2% by mass.
When the content is less than 0.01% by mass, the effect of adding a surfactant may be lost. When the content exceeds 3.0% by mass, the permeability to the recording medium becomes higher than necessary, and the image A decrease in density or breakthrough may occur.

-Water dispersible resin-
There is no restriction | limiting in particular as said water dispersible resin, Although it can select suitably according to the objective, For example, a condensation type synthetic resin, an addition type synthetic resin, a natural polymer compound, etc. are mentioned.
Examples of the condensed synthetic resin include polyester resins, polyurethane resins, polyepoxy resins, polyamide resins, polyether resins, and silicon resins. Examples of the addition type synthetic resin include polyolefin resins, polystyrene resins, polyvinyl alcohol resins, polyvinyl ester resins, polyacrylic acid resins, unsaturated carboxylic acid resins, and the like. Examples of the natural polymer compound include celluloses, rosins, and natural rubber.
The water-dispersible resin may be used as a homopolymer, may be used as a copolymer and used as a composite resin, and any of a single-phase structure type, a core-shell type, and a power feed type emulsion Can be used.

  As the water-dispersible resin, a resin itself having a hydrophilic group and having a self-dispersibility, and a resin itself having no dispersibility and imparted with a surfactant or a resin having a hydrophilic group can be used. . Among these, an emulsion of resin particles obtained by emulsion and suspension polymerization of an ionomer of a polyester resin or a polyurethane resin or an unsaturated monomer is optimal. In the case of emulsion polymerization of an unsaturated monomer, a resin emulsion is obtained by reacting with water to which an unsaturated monomer, a polymerization initiator, a surfactant, a chain transfer agent, a chelating agent, a pH adjusting agent and the like are added. Therefore, a water-dispersible resin can be easily obtained, and the resin properties can be easily changed, so that desired properties can be easily produced.

  Examples of the unsaturated monomer include unsaturated carboxylic acids, (meth) acrylic acid ester monomers, (meth) acrylic acid amide monomers, aromatic vinyl monomers, vinyl cyano compound monomer Isomers, vinyl monomers, allyl compound monomers, olefin monomers, diene monomers, oligomers having unsaturated carbon, and the like can be used alone or in combination. By combining these monomers, the properties can be flexibly modified, and the properties of the resin can be modified by performing a polymerization reaction or a graft reaction using an oligomer type polymerization initiator.

Examples of the unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid and the like.
Examples of the monofunctional (meth) acrylic acid esters include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, and 2-ethylhexyl methacrylate. Octyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, glycidyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, methacryloxyethyl trimethylammonium salt, 3 -Mekakuri Xylpropyltrimethoxysilane, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl acrylate, Examples include dodecyl acrylate, octadecyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, glycidyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, dimethylaminoethyl acrylate, and acryloxyethyl trimethyl ammonium salt.
Examples of the polyfunctional (meth) acrylic acid esters include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, and 1,4-butylene. Glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, polybutylene glycol dimethacrylate, 2,2'-bis (4-methacryloxydiethoxyphenyl) ) Propane, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, polyethyleneglycol Diacrylate, Triethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, 1,9-nonanediol di Acrylate, polypropylene glycol diacrylate, 2,2′-bis (4-acryloxypropyloxyphenyl) propane, 2,2′-bis (4-acryloxydiethoxyphenyl) propane trimethylolpropane triacrylate, trimethylolethanetri Acrylate, tetramethylol methane triacrylate, ditrimethylol tetraacrylate, tetramethylol methane tetraacrylate, pentaerythritol tetraacrylate, dipentaene Sri hexaacrylate, and the like.

Examples of the (meth) acrylic acid amide monomers include acrylamide, methacrylamide, N, N-dimethylacrylamide, methylenebisacrylamide, 2-acrylamido-2-methylpropanesulfonic acid, and the like.
Examples of the aromatic vinyl monomers include styrene, α-methylstyrene, vinyltoluene, 4-t-butylstyrene, chlorostyrene, vinylanisole, vinylnaphthalene, divinylbenzene and the like.
Examples of the vinyl cyano compound monomers include acrylonitrile and methacrylonitrile.
Examples of the allyl compound monomers include allyl sulfonic acid salt thereof, allylamine, allyl chloride, diallylamine, diallyldimethylammonium salt and the like.
Examples of the olefin monomers include ethylene and propylene.
Examples of the diene monomers include butadiene and chloroprene.
Examples of the vinyl monomers include vinyl acetate, vinylidene chloride, vinyl chloride, vinyl ether, vinyl ketone, vinyl pyrrolidone, vinyl sulfonic acid or salts thereof, vinyl trimethoxysilane, vinyl triethoxysilane, and the like.
Examples of the oligomers having unsaturated carbon include styrene oligomers having methacryloyl groups, styrene-acrylonitrile oligomers having methacryloyl groups, methyl methacrylate oligomers having methacryloyl groups, dimethylsiloxane oligomers having methacryloyl groups, and polyesters having acryloyl groups. An oligomer etc. are mentioned.

The water-dispersible resin has a strong alkalinity and strong acidity, and causes molecular breakage such as dispersion breakage and hydrolysis. Therefore, the pH is preferably 4 to 12, particularly from the viewpoint of miscibility with a water-dispersible colorant. As for pH, 6-11 are more preferable, and 7-9 are still more preferable.
The average particle size (D ₅₀ ) of the water-dispersible resin is related to the viscosity of the dispersion. When the composition is the same, the viscosity at the same solid content increases as the particle size decreases. The average particle diameter (D ₅₀ ) of the water-dispersible resin is preferably 50 nm or more so that the viscosity does not become excessively high when converted into an ink. In addition, when the particle size is several tens of microns, it becomes larger than the nozzle opening of the ink jet head and cannot be used. If particles having a large particle diameter are present in the ink even if they are smaller than the nozzle opening, the discharge property is deteriorated. Accordingly, the average particle diameter (D ₅₀ ) is more preferably 200 nm or less, and even more preferably 150 nm or less, in order not to inhibit the ink ejection properties.

The water-dispersible resin has a function of fixing the water-dispersed colorant on the paper surface, and is preferably formed into a film at room temperature to improve the fixability of the color material. Therefore, the minimum film-forming temperature (MFT) of the water dispersible resin is preferably 30 ° C. or less, and more preferably 20 ° C. or less.
Further, when the glass transition temperature of the water-dispersible resin is -40 ° C. or lower, the resin film becomes more viscous and the printed matter is tacky. Therefore, the water-dispersible resin has a glass transition temperature of −30 ° C. or higher. It is preferable.

  The content of the water-dispersible resin in the recording ink is preferably 4 to 30% by mass, more preferably 6 to 24% by mass in terms of solid content.

-Wetting agent-
The recording ink of the present invention uses water as a liquid medium, but the following wetting agents are used for the purpose of preventing the ink from drying and improving the dispersion stability. . These have excellent effects on solubility and prevention of jetting property defects due to water evaporation.

  The wetting agent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides. , Amines, sulfur-containing compounds, propylene carbonate, ethylene carbonate, other wetting agents, and the like. These may be used individually by 1 type and may use 2 or more types together.

Examples of the polyhydric alcohols include glycerin, diethylene glycol, 1,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, propylene glycol, dipropylene glycol, trimethylolpropane, and trimethylolethane. , Ethylene glycol, tripropylene glycol, tetraethylene glycol, hexylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,6-hexanediol, glycerol, 1,2,6-hexanetriol, 1,2 , 4-butanetriol, 1,2,3-butanetriol, petriol and the like.
Examples of the polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether, and the like. Can be mentioned.
Examples of the polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.
Examples of the nitrogen-containing heterocyclic compound include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam, γ-butyrolactone, Etc.
Examples of the amides include formamide, N-methylformamide, N, N-dimethylformamide, and the like.
Examples of the amines include monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, triethylamine, and the like.
Examples of the sulfur-containing compounds include dimethyl sulfoxide, sulfolane, thiodiethanol, and the like.
The other wetting agent preferably contains sugar. Examples of the saccharide include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides), polysaccharides, and the like. Specific examples include glucose, mannose, fructose, ribose, xylose, arabinose, galactose, maltose, cellobiose, lactose, sucrose, trehalose, maltotriose, and the like. Here, the polysaccharide means a saccharide in a broad sense, and is used to include a substance that exists widely in nature such as α-cyclodextrin and cellulose. The derivatives of these saccharides are represented by the reducing sugars of the saccharides described above (for example, sugar alcohol (general formula: HOCH ₂ (CHOH) nCH ₂ OH (where n represents an integer of 2 to 5)). ), Oxidized sugars (for example, aldonic acid, uronic acid, etc.), amino acids, thioic acids, etc. Among these, sugar alcohols are preferred, and specific examples include maltitol, sorbit and the like.
Among these wetting agents, glycerin, diethylene glycol, triethylene glycol, 1,3-butanediol and 3-methyl-1,3-butanediol are particularly preferable from the viewpoint of storage stability and ejection stability.
The mass ratio of the pigment and the wetting agent has a great influence on the stability of ink ejection from the head. If the blending amount of the wetting agent is small even though the pigment solid content is high, water evaporation near the ink meniscus of the nozzle may progress and cause ejection failure.

  The content of the wetting agent in the recording ink is preferably 20 to 35% by mass, and more preferably 22.5 to 32.5% by mass. Ink within this range has very good drying, storage and reliability tests. When the content is less than 20% by mass, the ink is liable to dry on the nozzle surface and discharge failure may occur. When the content exceeds 35% by mass, the drying property on the paper surface is inferior, and further on plain paper. Character quality may be degraded.

-Penetration agent-
The penetrant preferably contains at least one polyol compound having a solubility in water at 20 ° C. of 0.2 to 5.0 mass%. Examples of such an aliphatic diol as the polyol compound include 2-ethyl-2-methyl-1,3-propanediol, 3,3-dimethyl-1,2-butanediol, and 2,2-diethyl-1. , 3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2,4-dimethyl-2,4-pentanediol, 2,5-dimethyl-2,5-hexanediol, 5-hexene -1,2-diol, 2-ethyl-1,3-hexanediol and the like.
Among these, 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol are particularly preferable.
Other penetrants that can be used in combination are not particularly limited as long as they can be dissolved in ink and adjusted to desired physical properties, and can be appropriately selected according to the purpose. Examples thereof include diethylene glycol monophenyl ether and ethylene. Glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, alkyl and aryl ethers of polyhydric alcohols such as tetraethylene glycol chlorophenyl ether, lower alcohols such as ethanol, etc. Is mentioned.
The content of the penetrant in the recording ink is preferably 0.1 to 4.0% by mass. When the content is less than 0.1% by mass, quick-drying may not be obtained and a blurred image may be obtained. When the content exceeds 4.0% by mass, the dispersion stability of the colorant is impaired, and the nozzle In some cases, clogging is likely to occur, and the permeability to the recording medium is increased more than necessary, resulting in a decrease in image density and back-through.

  The other components are not particularly limited and may be appropriately selected as necessary. For example, a pH adjuster, antiseptic / antifungal agent, chelating reagent, rust inhibitor, antioxidant, ultraviolet absorber, oxygen An absorber, a light stabilizer, etc. are mentioned.

The pH adjuster is not particularly limited as long as the pH can be adjusted to 7 to 11 without adversely affecting the recording ink to be prepared, and can be appropriately selected according to the purpose. Examples include alcohol amines, alkali metal hydroxides, ammonium hydroxides, phosphonium hydroxides, and alkali metal carbonates. If the pH is less than 7 or more than 11, the amount of the ink jet head or ink supply unit that melts out is large, and problems such as ink deterioration, leakage, and ejection failure may occur.
Examples of the alcohol amines include diethanolamine, triethanolamine, 2-amino-2-ethyl-1,3-propanediol, and the like.
Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide.
Examples of the ammonium hydroxide include ammonium hydroxide, quaternary ammonium hydroxide, quaternary phosphonium hydroxide, and the like.
Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, and potassium carbonate.

  Examples of the antiseptic / antifungal agent include sodium dehydroacetate, sodium sorbate, 2-pyridinethiol-1-oxide sodium, sodium benzoate, sodium pentachlorophenol, and the like.

  Examples of the chelating reagent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uramil diacetate, and the like.

  Examples of the rust inhibitor include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

  Examples of the rust preventive include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite, and the like.

Examples of the antioxidant include phenol-based antioxidants (including hindered phenol-based antioxidants), amine-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like.
Examples of the phenolic antioxidants (including hindered phenolic antioxidants) include butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, stearyl-β- (3,5 -Di-tert-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4,4′-Butylidenebis (3-methyl-6-tert-butylphenol), 3,9-bis [1,1-dimethyl-2- [β- (3-tert-butyl-4-hydroxy-5-methylphenyl) ) Propionyloxy] ethyl] 2,4,8,10-tetrixaspiro [5,5] undecane, 1,1,3-tris (2-methyl-4- Hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane, and the like.
Examples of the amine-based antioxidant include phenyl-β-naphthylamine, α-naphthylamine, N, N′-di-sec-butyl-p-phenylenediamine, phenothiazine, N, N′-diphenyl-p-phenylenediamine. 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butyl-phenol, butylhydroxyanisole, 2,2′-methylenebis ( 4-methyl-6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 4,4′-thiobis (3-methyl-6-tert-butylphenol), tetrakis [methylene -3 (3,5-di-tert-butyl-4-dihydroxyphenyl) propionate] methane, 1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane and the like.
Examples of the sulfur-based antioxidant include dilauryl 3,3′-thiodipropionate, distearyl thiodipropionate, lauryl stearyl thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl β. , β′-thiodipropionate, 2-mercaptobenzimidazole, dilauryl sulfide and the like.
Examples of the phosphorus antioxidant include triphenyl phosphite, octadecyl phosphite, triisodecyl phosphite, trilauryl trithiophosphite, trinonylphenyl phosphite, and the like.

Examples of the ultraviolet absorber include benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers, salicylate ultraviolet absorbers, cyanoacrylate ultraviolet absorbers, and nickel complex salt ultraviolet absorbers.
Examples of the benzophenone-based ultraviolet absorber include 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2,4-dihydroxybenzophenone, and 2-hydroxy-4-methoxybenzophenone. 2,2 ′, 4,4′-tetrahydroxybenzophenone, and the like.
Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-4′-octoxyphenyl) benzotriazole, 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, and the like.
Examples of the salicylate-based ultraviolet absorber include phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate, and the like.
Examples of the cyanoacrylate ultraviolet absorber include ethyl-2-cyano-3,3′-diphenyl acrylate, methyl-2-cyano-3-methyl-3- (p-methoxyphenyl) acrylate, and butyl-2- And cyano-3-methyl-3- (p-methoxyphenyl) acrylate.
Examples of the nickel complex ultraviolet absorber include nickel bis (octylphenyl) sulfide, 2,2′-thiobis (4-tert-octylferrate) -n-butylamine nickel (II), 2,2′-thiobis. (4-tert-octyl ferrate) -2-ethylhexylamine nickel (II), 2,2′-thiobis (4-tert-octyl ferrate) triethanolamine nickel (II), and the like.

  The recording ink of the present invention comprises a water-dispersible colorant, a water-dispersible resin, a wetting agent, a surfactant, and water, and other components dispersed or dissolved in an aqueous medium as necessary. According to this, the mixture is mixed by stirring. The dispersion can be performed by, for example, a sand mill, a homogenizer, a ball mill, a paint shaker, an ultrasonic disperser, etc., and stirring and mixing are performed by a stirrer using a normal stirring blade, a magnetic stirrer, a high-speed disperser, or the like. be able to.

  The physical properties of the recording ink of the present invention are not particularly limited and may be appropriately selected depending on the intended purpose. For example, the viscosity, surface tension and the like are preferably in the following ranges.

The viscosity of the recording ink at 25 ° C. is 5 to 20 mPa · s, and preferably 10 to 20 mPa · s. By setting the ink viscosity to 5 mPa · s or more, the effect of improving the printing density and the character quality can be obtained. On the other hand, by suppressing the ink viscosity to 20 mPa · s or less, it is possible to ensure dischargeability.
Here, the said viscosity can be measured at 25 degreeC, for example using a viscometer (RL-500, the Toki Sangyo Co., Ltd. make).
The surface tension of the recording ink is preferably 35 mN / m or less, more preferably 30 mN / m or less at 25 ° C. When the surface tension exceeds 35 mN / m, leveling of the ink on the recording medium hardly occurs and the drying time may be prolonged.

  There is no restriction | limiting in particular as coloring of the recording ink of this invention, According to the objective, it can select suitably, Yellow, magenta, cyan, black etc. are mentioned. When recording is performed using an ink set in which two or more of these colorings are used in combination, a multicolor image can be formed. When recording is performed using an ink set in which all colors are combined, a full color image is formed. be able to.

  The recording ink of the present invention uses an piezoelectric head as a pressure generating means for pressurizing ink in an ink flow path as an ink jet head, and deforms a diaphragm that forms the wall surface of the ink flow path to increase the volume in the ink flow path. A so-called piezo type that discharges ink droplets by changing (refer to Japanese Patent Laid-Open No. 2-51734), or a so-called thermal type that generates bubbles by heating ink in an ink flow path using a heating resistor. (Refer to Japanese Patent Application Laid-Open No. 61-59911), a diaphragm that forms the wall surface of an ink flow path and an electrode are arranged opposite to each other, and the diaphragm is deformed by an electrostatic force generated between the diaphragm and the electrode. Thus, a pre-printer equipped with any ink jet head such as an electrostatic type (see Japanese Patent Laid-Open No. 6-71882) that discharges ink droplets by changing the volume in the ink flow path. Can also be used well for printers.

  The recording ink of the present invention can be suitably used in various fields such as an ink jet recording ink, a fountain pen, a ballpoint pen, a magic pen, and a sign pen, but is particularly suitable for an image forming apparatus (printer or the like) using an ink jet recording method. For example, the recording paper and the recording ink can be heated at 50 to 200 ° C. before or after printing or printing, and can be used for a printer or the like having a function of promoting print fixing. The ink cartridge, ink recording material, ink jet recording apparatus, and ink jet recording method of the present invention can be used particularly preferably.

(ink cartridge)
The ink cartridge of the present invention contains the recording ink of the present invention in a container, and further includes other members and the like appropriately selected as necessary.
The container is not particularly limited, and its shape, structure, size, material and the like can be appropriately selected according to the purpose. Preferred examples include those possessed.
Next, the ink cartridge will be described with reference to FIGS. Here, FIG. 1 is a view showing an example of the ink cartridge of the present invention, and FIG. 2 is a view including a case (exterior) of the ink cartridge of FIG.
As shown in FIG. 1, the ink cartridge 200 is filled into the ink bag 241 from the ink inlet 242 and exhausted, and then the ink inlet 242 is closed by fusion. In use, the needle of the apparatus main body is pierced into the ink discharge port 243 made of a rubber member and supplied to the apparatus.
The ink bag 241 is formed of a packaging member such as a non-permeable aluminum laminate film. As shown in FIG. 2, the ink bag 241 is usually housed in a plastic cartridge case 244 and is detachably mounted on various ink jet recording apparatuses.
The ink cartridge of the present invention contains the recording ink (ink set) of the present invention and can be used by being detachably mounted on various ink jet recording apparatuses. It is particularly preferable to use it by mounting it.

(Inkjet recording apparatus and inkjet recording method)
The ink jet recording apparatus of the present invention includes at least ink flying means, and further includes other means appropriately selected as necessary, for example, stimulus generation means and control means.
The ink jet recording method of the present invention includes at least an ink flying process, and further includes other processes appropriately selected as necessary, for example, a stimulus generation process, a control process, and the like.
The ink jet recording method of the present invention can be preferably carried out by the ink jet recording apparatus of the present invention, and the ink flying step can be suitably carried out by the ink flying means. Moreover, the said other process can be suitably performed by the said other means.

-Ink flying process and ink flying means-
The ink flying step is a step of forming an image by applying a stimulus to the recording ink of the present invention and causing the recording ink to fly.
The ink flying means is means for forming an image by applying a stimulus to the recording ink of the present invention and causing the recording ink to fly. The ink flying means is not particularly limited, and examples thereof include various nozzles for ejecting ink.

  The stimulus can be generated, for example, by the stimulus generating means, and the stimulus is not particularly limited and can be appropriately selected according to the purpose, such as heat (temperature), pressure, vibration, light, etc. Is mentioned. These may be used individually by 1 type and may use 2 or more types together. Among these, heat and pressure are preferable.

  Examples of the stimulus generating means include a heating device, a pressurizing device, a piezoelectric element, a vibration generating device, an ultrasonic oscillator, a light, and the like. Specifically, for example, a piezoelectric actuator such as a piezoelectric element, Examples include thermal actuators that use phase change due to liquid film boiling using electrothermal transducers such as heating resistors, shape memory alloy actuators that use metal phase changes due to temperature changes, electrostatic actuators that use electrostatic force, etc. It is done.

  There are no particular restrictions on the manner in which the recording ink flies, and it varies depending on the type of the stimulus. For example, when the stimulus is “heat”, a recording signal is output to the recording ink in the recording head. Corresponding thermal energy is applied using, for example, a thermal head, bubbles are generated in the recording ink by the thermal energy, and the recording ink is formed into droplets from the nozzle holes of the recording head by the pressure of the bubbles. And a method of discharging and jetting. Further, when the stimulus is “pressure”, for example, by applying a voltage to a piezoelectric element bonded to a position called a pressure chamber in an ink flow path in the recording head, the piezoelectric element bends and the volume of the pressure chamber is increased. And the recording ink is ejected and ejected as droplets from the nozzle holes of the recording head.

The size of the recording ink droplets to be ejected is preferably 3 to 40 pl, for example, and the ejection jet speed is preferably 5 to 20 m / s, and the driving thereof. The frequency is preferably 1 kHz or more, and the resolution is preferably 300 dpi or more.
The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as sequencers and computers.

  Here, one aspect of carrying out the ink jet recording method of the present invention by the ink jet recording apparatus of the present invention will be described with reference to the drawings. FIG. 3 is a schematic view showing an example of the serial type ink jet recording apparatus of the present invention. The ink jet recording apparatus shown in FIG. 3 stocks an apparatus main body 101, a paper feed tray 102 for loading paper mounted on the apparatus main body 101, and paper on which an image is recorded (formed) mounted on the apparatus main body 101. A paper discharge tray 103 and an ink cartridge loading unit 104. On the upper surface of the ink cartridge loading unit 104, an operation unit 105 such as operation keys and a display is arranged. The ink cartridge loading unit 104 has a front cover 115 that can be opened and closed for attaching and detaching the ink cartridge 201.

In the apparatus main body 101, as shown in FIGS. 4 and 5, a carriage 133 is slid in the main scanning direction by a guide rod 131 and a stay 132, which are guide members horizontally mounted on left and right side plates (not shown). The main scanning motor (not shown) moves and scans in the direction of the arrow in FIG.
The carriage 133 includes a plurality of ink jet recording heads 134 including four ink jet recording heads that eject recording ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). The ejection ports are arranged in a direction crossing the main scanning direction, and are mounted with the ink droplet ejection direction facing downward.
As the ink jet recording head constituting the recording head 134, a piezoelectric actuator such as a piezoelectric element, a thermal actuator using phase change due to liquid film boiling using an electrothermal transducer such as a heating resistor, a metal phase due to temperature change, and the like. A shape memory alloy actuator using change, an electrostatic actuator using electrostatic force, or the like provided as energy generating means for discharging ink can be used.

In addition, the carriage 133 is equipped with a sub tank 135 for each color for supplying ink of each color to the recording head 134. The sub tank 135 is supplied with the recording ink of the present invention from the ink cartridge 1 of the present invention loaded in the ink cartridge loading section 105 via a recording ink supply tube (not shown).
On the other hand, as a paper feeding unit for feeding the paper 142 stacked on the paper stacking unit (pressure plate) 141 of the paper feeding tray 103, a half-moon roller (feeding) that separates and feeds the paper 142 one by one from the paper stacking unit 141. A separation pad 144 made of a material having a large coefficient of friction is provided facing the paper roller 143) and the paper feed roller 143, and the separation pad 144 is urged toward the paper feed roller 143 side.
As a transport unit for transporting the paper 142 fed from the paper feed unit below the recording head 134, a transport belt 151 for transporting the paper 142 by electrostatic adsorption and a guide 145 from the paper feed unit. The counter roller 152 for transporting the paper 142 fed via the transport belt 151 with the transport belt 151 and the paper 142 fed substantially vertically upward are changed by approximately 90 ° so as to follow the transport belt 151. For this purpose, a conveyance guide 153 and a tip pressure roller 155 urged toward the conveyance belt 151 by a pressing member 154 are provided. In addition, a charging roller 156 that is a charging unit for charging the surface of the conveyance belt 151 is provided.
The conveyance belt 151 is an endless belt, is stretched between the conveyance roller 157 and the tension roller 158, and can circulate in the belt conveyance direction. The transport belt 151 includes, for example, a surface layer serving as a sheet adsorbing surface formed of a resin material having a thickness of about 40 μm that is not subjected to resistance control, for example, a copolymer of tetrafluoroethylene and ethylene (ETFE), and the surface layer. It has a back layer (medium resistance layer, earth layer) that is made of the same material and has resistance controlled by carbon. On the back side of the conveyance belt 151, a guide member 161 is arranged corresponding to a printing area by the recording head 134. Note that, as a paper discharge unit for discharging the paper 142 recorded by the recording head 134, a separation claw 171 for separating the paper 142 from the conveyance belt 151, a paper discharge roller 172, and a paper discharge roller 173 are provided. The paper discharge tray 103 is disposed below the paper discharge roller 172.

A double-sided paper feeding unit 181 is detachably mounted on the back surface of the apparatus main body 101. The double-sided paper feeding unit 181 takes in the paper 142 returned by the reverse rotation of the transport belt 151, reverses it, and feeds it again between the counter roller 152 and the transport belt 151. A manual paper feed unit 182 is provided on the upper surface of the duplex paper feed unit 181.
In this ink jet recording apparatus, the paper 142 is separated and fed one by one from the paper feed unit, and the paper 142 fed substantially vertically upward is guided by the guide 145 and between the transport belt 151 and the counter roller 152. It is sandwiched and conveyed. Further, the leading end is guided by the conveying guide 153 and pressed against the conveying belt 151 by the leading end pressure roller 155, and the conveying direction is changed by approximately 90 °.
At this time, the conveyance belt 157 is charged by the charging roller 156, and the sheet 142 is conveyed by being electrostatically attracted to the conveyance belt 151. Therefore, by driving the recording head 134 according to the image signal while moving the carriage 133, ink droplets are ejected onto the stopped paper 142 to record one line, and after the paper 142 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the sheet 142 has reached the recording area, the recording operation is terminated and the sheet 142 is discharged onto the discharge tray 103.
When the recording ink remaining amount near end in the sub tank 135 is detected, a required amount of recording ink is supplied from the ink cartridge 201 to the sub tank 135.

  In this ink jet recording apparatus, when the recording ink in the ink cartridge 201 of the present invention is used up, the casing of the ink cartridge 201 can be disassembled and only the ink bag inside can be replaced. Further, the ink cartridge 201 can supply recording ink stably even when the ink cartridge 201 is placed vertically and has a front loading configuration. Therefore, even when the upper portion of the apparatus main body 101 is closed and installed, for example, when stored in a rack or when an object is placed on the upper surface of the apparatus main body 101, the ink cartridge 201 is used. Can be easily exchanged.

  In addition, although it demonstrated in the example applied to the serial type (shuttle type) inkjet recording device which a carriage scans, it can apply similarly to the line type inkjet recording device provided with the line type head.

  Further, the ink jet recording apparatus and the ink jet recording method of the present invention can be applied to various kinds of recording by the ink jet recording method. It can be particularly preferably applied.

(Ink record)
The recorded matter recorded by the ink jet recording apparatus and ink jet recording method of the present invention is the ink recorded matter of the present invention. The ink recorded matter of the present invention has an image formed on the recording medium using the recording ink of the present invention.
There is no restriction | limiting in particular as said recording medium, According to the objective, it can select suitably, For example, a plain paper, glossy paper, special paper, cloth, a film, an OHP sheet etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together.
The ink recorded matter has high image quality, no bleeding, excellent temporal stability, and can be suitably used for various purposes as a material on which various prints or images are recorded.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Preparation Example 1)
-Preparation of water-soluble polymer compound aqueous solution A-
-Α-olefin-maleic anhydride copolymer [I] represented by the above structural formula (1) 10.0 parts by mass (manufactured by Seiko PMC, T-YP112, olefin chain: carbon number 20-24 Acid value 190 mgKOH / g, weight average molecular weight 10,000]
-1N LiOH aqueous solution (1.2 times the acid value) ... 17.34 parts by mass-Ion exchange water ... 72.66 parts by mass The above mixture is heated and stirred with a stirrer, and the above structural formula (1 The α-olefin-maleic anhydride copolymer [I] represented by) was dissolved, and a small amount of insoluble matter was filtered through a 5 μm filter to prepare a water-soluble polymer compound aqueous solution A.

(Preparation Example 2)
-Preparation of surface-treated black pigment dispersion-
90 g of carbon black having a CTAB specific surface area of 150 m ² / g and DBP oil absorption of 100 ml / 100 g is added to 3000 ml of 2.5 N sodium sulfate solution, stirred at a temperature of 60 ° C. and a speed of 300 rpm, and reacted for 10 hours to oxidize. Processed. The reaction solution was filtered, and the carbon black separated by filtration was neutralized with a sodium hydroxide solution and subjected to ultrafiltration. The obtained carbon black was washed with water, dried, and dispersed in pure water to a solid content of 30% by mass.
Next, with respect to 100 parts by mass of the carbon black dispersion, the water-soluble polymer compound aqueous solution B represented by the above structural formula (1) [manufactured by Starlight PMC, T-YP115, olefin chain: carbon number 16 to 18, An acid value of 221 mg KOH / g, a weight average molecular weight of 11,000, counter ion: ammonium ion, active ingredient 23 mass%] 6.52 parts by mass were added and stirred sufficiently to obtain a black pigment dispersion. The average particle diameter _{(D 50)} of the pigment dispersion was 106nm was measured. The average particle diameter (D ₅₀ ) was measured using UPA-EX150 manufactured by Microtrack.

(Preparation Example 3)
-Preparation of yellow pigment surfactant dispersion-
Monoazo yellow pigment (CI Pigment Yellow 74, manufactured by Dainichi Seika Kogyo Co., Ltd.) 30.0 parts by mass Polyoxyethylene styrene phenyl ether <Neugen EA-177> ... 10.0 parts by mass ( Nonionic surfactant, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., HLB value: 15.7)
・ Ion-exchanged water: 60.0 parts by mass First, when the surfactant is dissolved in ion-exchanged water and the pigment is mixed and wetted sufficiently, a wet disperser (Dynomill KDL A type, manufactured by WAB Co., Ltd.) ) Was filled with zirconia beads having a diameter of 0.5 mm and dispersed at 2000 rpm for 4 hours to obtain a primary pigment dispersion.
Next, as a water-soluble polymer compound aqueous solution in the primary pigment dispersion, 2.13 parts by mass of water-soluble polyurethane (Takelac W-5661, manufactured by Mitsui Takeda Chemical Co., Ltd., active ingredient 35.2% by mass) and the above structural formula ( 1) Water-soluble polymer compound aqueous solution C represented by 1) [manufactured by Starlight PMC, T-YP114, olefin chain: carbon number 12 to 14, acid value 385 mgKOH / g, molecular weight 9,000, counter ion: ammonium ion, effective Component 25.6% by mass] 2.93 parts by mass were added and stirred sufficiently to obtain a yellow pigment surfactant dispersion. The average particle diameter of the obtained pigment dispersion (D ₅₀₎ was 49nm was measured. The average particle diameter (D ₅₀ ) was measured using UPA-EX150 manufactured by Microtrack.

(Preparation Example 4)
-Preparation of a magenta pigment surfactant dispersion-
・ Quinacridone pigment (CI Pigment Red 122, manufactured by Dainichi Seika Kogyo Co., Ltd.) 30.0 parts by mass Polyoxyethylene-β-naphthyl ether <RT-100> 10.0 parts by mass ( Nonionic surfactant, manufactured by Takemoto Yushi Co., Ltd., HLB value: 18.5)
・ Ion-exchanged water: 60.0 parts by mass First, when the surfactant is dissolved in ion-exchanged water and the pigment is mixed and wetted sufficiently, a wet disperser (Dynomill KDL A type, manufactured by WAB Co., Ltd.) ) Was filled with zirconia beads having a diameter of 0.5 mm and dispersed at 2000 rpm for 2 hours to obtain a primary pigment dispersion. Next, 3.57 parts by mass of a water-soluble styrene-acrylic copolymer (JC-05, manufactured by Seiko PMC Co., Ltd., 21% by mass of active ingredient) is added to the primary pigment dispersion, and the water-soluble compound represented by the above structural formula (1). Water-soluble polymer compound aqueous solution D [manufactured by Seiko PMC, T-YP116, olefin chain: carbon number 8, carbon number 16-18, acid value 280-310 mgKOH / g, weight average molecular weight 11,400, counter ion: ammonium ion, Active component 25.3% by mass] 2.97 parts by mass were added and stirred sufficiently to obtain a magenta pigment surfactant dispersion. The average particle diameter of the obtained pigment dispersion (D ₅₀₎ was 81nm was measured. The average particle diameter (D ₅₀ ) was measured using UPA-EX150 manufactured by Microtrack.

(Preparation Example 5)
-Preparation of Cyan Pigment Surfactant Dispersion A-
-Phthalocyanine pigment (CI Pigment Blue 15: 3, manufactured by Dainichi Seika Kogyo Co., Ltd.) 30.0 parts by mass-Polyoxyethylene lauryl ether <DKS NL-450> ... 10.0 parts by mass ( Nonionic surfactant, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., HLB value: 18.3)
・ Ion-exchanged water: 60.0 parts by mass First, when the surfactant is dissolved in ion-exchanged water and the pigment is mixed and wetted sufficiently, a wet disperser (Dynomill KDL A type, manufactured by WAB Co., Ltd.) ) Was filled with zirconia beads having a diameter of 0.5 mm and dispersed at 2000 rpm for 2 hours to obtain a primary pigment dispersion.
Next, 2.51 parts by mass of a water-soluble polyester (Nichigo Polyester W-0030, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., active ingredient 29.9% by mass) as a water-soluble polymer compound aqueous solution in the primary pigment dispersion, Water-soluble polymer compound aqueous solution B represented by structural formula (1) [manufactured by Starlight PMC, T-YP115, olefin chain: carbon number 16 to 18, acid value 221 mgKOH / g, weight average molecular weight 11,000, counter ion : Ammonium ion, active ingredient 23% by mass] 3.26 parts by mass was added and stirred sufficiently to obtain a cyan pigment surfactant dispersion A. The average particle diameter _{(D 50)} of the pigment dispersion was 75nm was measured. The average particle diameter (D ₅₀ ) was measured using UPA-EX150 manufactured by Microtrack.

(Preparation Example 6)
-Preparation of Cyan Pigment Surfactant Dispersion B-
-Phthalocyanine pigment (CI Pigment Blue 15: 3, manufactured by Dainichi Seika Kogyo Co., Ltd.) 30.0 parts by mass-Polyoxyethylene styrene phenyl ether <Neugen EA-177> ... 10.0 parts by mass (Nonionic surfactant, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., HLB value: 15.7)
・ Ion-exchanged water: 60.0 parts by mass First, when the surfactant is dissolved in ion-exchanged water and the pigment is mixed and sufficiently wetted, a wet disperser dyno mill (KDL A type, manufactured by WAB Co., Ltd.) ) Was filled with zirconia beads having a diameter of 0.5 mm and dispersed at 2000 rpm for 2 hours to obtain a primary pigment dispersion.
Next, 15.0 parts by mass of the water-soluble polymer compound aqueous solution A of Preparation Example 1 was added to the primary pigment dispersion, and the mixture was sufficiently stirred to obtain a cyan pigment surfactant dispersion B. The average particle diameter _{(D 50)} of the pigment dispersion was 83nm was measured. The average particle diameter (D ₅₀ ) was measured using UPA-EX150 manufactured by Microtrack.

(Preparation Example 7)
-Preparation of Cyan Pigment Surfactant Dispersion C-
-Phthalocyanine pigment (CI Pigment Blue 15: 3, manufactured by Dainichi Seika Kogyo Co., Ltd.) 30.0 parts by mass-Polyoxyethylene lauryl ether <DKS NL-450> ... 10.0 parts by mass ( Nonionic surfactant, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., HLB value: 18.3)
・ Ion-exchanged water: 60.0 parts by mass First, when the surfactant is dissolved in ion-exchanged water and the pigment is mixed and wetted sufficiently, a wet disperser (Dynomill KDL A type, manufactured by WAB Co., Ltd.) ) Was filled with zirconia beads having a diameter of 0.5 mm and dispersed at 2000 rpm for 2 hours to obtain a cyan pigment surfactant dispersion C. The average particle diameter of the obtained pigment dispersion (D ₅₀₎ was 75nm was measured. The average particle diameter (D ₅₀ ) was measured using UPA-EX150 manufactured by Microtrack.

(Examples 1-11 and Comparative Examples 1-6)
-Preparation of recording ink-
Each ink was manufactured according to the following procedure, but the present invention is not limited to this. First, a wetting agent, a penetrating agent, a surfactant, and water shown in the following Table 1, Table 2, and Table 3 are mixed, and stirred for 1 hour to mix uniformly. The resin dispersion is added to this mixed solution and stirred for 1 hour, and the pigment dispersion and antifoaming agent are added and stirred for 1 hour. This dispersion was subjected to pressure filtration through a cellulose acetate membrane filter having an average pore diameter of 0.8 μm to remove coarse particles and dust, thereby producing a recording ink used for evaluation.

The abbreviations in Tables 1 to 3 represent the following meanings.
* Acrylic silicone emulsion: manufactured by Toyo Ink Manufacturing Co., Ltd., solid content: 40% by mass, average particle size: 130 nm, MFT = 0 ° C. or less * Acrylic emulsion: John Clear 7600, manufactured by Johnson Polymer Co., Ltd., solid content: 47% by mass, average particle size 90 nm, MFT = 10 ° C. or less * Polyurethane emulsion: Hydran HW930, manufactured by DIC, solid content 50% by mass, average particle size 200 nm or less, MFT = 0 ° C. or less * Polyester emulsion: Pesresin A-520, manufactured by Takamatsu Oil & Fats, solid 30% by mass, average particle size 100 nm, MFT = 30 ° C. or less * Polyfox PF-151N: oligomer type nonionic fluorosurfactant (manufactured by OMNOVA, component 50% by mass)
* Zonyl FS-300: polyoxyethylene perfluoroalkyl ether (manufactured by Dupont, 40 mass% component)
* Softanol EP-5035: polyoxyethylene polyoxypropylene branched alkyl ether (manufactured by Nippon Shokubai Co., Ltd., 100 mass% component)
* Proxel GXL: 1,2-benzisothiazolin-3-one as the main component, fungicide, manufactured by Avicia, 20% by mass, containing dipropylene glycol)
* KM-72F: Self-emulsifying silicone defoamer (manufactured by Shin-Etsu Silicone Co., Ltd., 100% by mass)

  Next, the recording inks of Examples 1 to 11 and Comparative Examples 1 to 6 were evaluated by the following evaluation method. The results are shown in Tables 4 and 5.

<Amount of resin relative to pigment>
The ratio of the resin solid content in the water-dispersible resin (emulsion) to the pigment solid content contained in the ink (ratio = resin solid content / pigment solid content) was calculated.

<Ink solid content>
The total content of pigment and resin (emulsion + water-soluble resin) in the ink was calculated.

<Measurement of ink viscosity>
The viscosity was measured at 25 ° C. using a viscometer (RL-500, manufactured by Toki Sangyo Co., Ltd.).

<Measurement of ink surface tension>
The surface tension was measured at 25 ° C. using a fully automatic surface tension meter (CBVP-Z, manufactured by Kyowa Interface Science Co., Ltd.).

−Preparation for printing evaluation−
Using an inkjet printer (IPSIO G707, manufactured by Ricoh Co., Ltd.) in an environment adjusted to a temperature of 23 ° C. and 50% RH, the drive voltage of the piezo element is varied so that the amount of ink discharged is uniform, and the recording medium Was set so that the same amount of ink was attached to the.

<Discharge stability>
A chart in which an area of 5% of A4 size paper per color created with Microsoft Word 2000 was filled with a solid image was ejected on 200 Type 6200 papers (manufactured by NBS Ricoh Co., Ltd.) and evaluated from ejection disturbance of each nozzle after launch. . The printing mode used was a driver attached to the printer, in which the “plain paper-standard faster” mode was changed to “no color correction” than the user setting for plain paper.
〔Evaluation criteria〕
○: Discharge turbulence △: Discharge turbulence slightly ×: Discharge turbulence or non-discharge portion

<Image density>
A chart with 64 point characters “■” created by Microsoft Word 2000 is printed on Xerox 4024 paper (manufactured by Fuji Xerox Co., Ltd.), and the “■” part of the printed surface is measured with X-Rite 938, and judged according to the following evaluation criteria. did. The print mode used was a driver attached to the printer, in which the "plain paper-standard fast" mode was changed to "no color correction" than the user setting for plain paper.
〔Evaluation criteria〕
◎: Black 1.3 or more, Yellow 0.85 or more, Magenta 0.95 or more, Cyan 1.1 or more ○: Black 1.2 or more and less than 1.3, Yellow 0.8 or more and less than 0.85, Magenta 0.9 More than 0.95, Cyan 1.0 or more and less than 1.1 Δ: Black 1.1 or more and less than 1.1, Yellow 0.7 or more and less than 0.8, Magenta 0.8 or more and less than 0.90, cyan 0. 9 or more and less than 1.0 X: Black 1.1 or less, Yellow 0.7 or less, Magenta 0.8 or less, Cyan 0.9 or less

<Color development>
In the same manner as the image density, the chart was punched out on Xerox 4024 paper (manufactured by Fuji Xerox), the “■” part of the printed surface was measured with X-Rite 938, and judged according to the following evaluation criteria. The printing mode used was a driver attached to the printer, in which the “plain paper-standard faster” mode was changed to “no color correction” than the user setting for plain paper. Calculate the ratio of the saturation value of the standard color (Japan color ver. 2) (yellow 91.34, magenta: 74.55, cyan 62.82) and according to the following evaluation criteria Judged.
〔Evaluation criteria〕
○: 0.8 or more ×: Less than 0.8

<Water resistance>
Similar to the print density, the chart was printed on Type 6200 paper (manufactured by NBS Ricoh Co., Ltd.), and the “■” portion of the printed surface was dried at a temperature of 23 ° C. and 50% RH for 24 hours. After being immersed for 1 minute, it was gently lifted and allowed to stand still and judged according to the following evaluation criteria.
〔Evaluation criteria〕
○: No color exudation ×: Color exudation

<Abrasion resistance>
A chart with a solid color image of 3 cm x 3 cm created by Microsoft Word 2000 was punched onto a glossy glossy paper dedicated to the ricochet jet printer (manufactured by NBS Ricoh Co., Ltd.) and dried at a temperature of 23 ° C and 50% RH for 24 hours. After reciprocating 10 times so that JIS L0803 cotton 3 attached to the CM-1 type clock meter with double-sided tape hits the printed part, the ink adhesion stain on the cotton cloth was measured with X-Rite 938, and the cotton cloth ground The skin color was subtracted and the density of the soiled part was determined according to the following evaluation criteria.
〔Evaluation criteria〕
○: Less than 0.1 ×: 0.1 or more

<Light resistance>
Like the image density, the chart was punched onto Type 6200 paper (manufactured by NBS Ricoh Co., Ltd.), and the “■” part of the printed surface was dried at a temperature of 23 ° C. and 50% RH for 24 hours. Using a weatherometer Ci35AW, irradiate for 24 hours with an xenon irradiance of 0.35 W / m ² (340 nm) that approximates outdoor sunlight in an environment of 70 ° C., 50% RH, and a black panel temperature of 89 ° C. The color change was determined according to the following evaluation criteria.
〔Evaluation criteria〕
○: Almost no change △: Change is recognized but acceptable

<Drying>
The chart was punched out in the same manner as the print density, and the “■” portion of the print surface printed on Type 6200 paper (manufactured by NBS Ricoh Co., Ltd.) was pressed against the filter paper immediately after printing, and the presence or absence of transfer was determined.
〔Evaluation criteria〕
○: No transfer stain △: Slight transfer stain ×: Transfer stain

* In Comparative Example 2, the ink viscosity was high and the image could not be printed normally, so the image evaluation result could not be measured. * Comparative Example 3 could not be printed normally due to the small amount of ink wetting agent. Therefore, the result of the image evaluation is not measurable. “-” In Table 5 indicates that no measurement is performed.

The recording ink of the present invention provides an image with excellent image quality, particularly image density, saturation, and image fastness (water resistance, light resistance, etc.) on plain paper, and is excellent in drying speed and high-speed printing. In addition, the ejection stability from the nozzles is good, high-quality image formation is possible, and it can be suitably used for an ink cartridge, an ink recorded material, an ink jet recording apparatus, and an ink jet recording method.
The ink jet recording apparatus and the ink jet recording method of the present invention can be applied to various types of recording by the ink jet recording method, and are particularly suitable for, for example, an ink jet recording printer, a facsimile apparatus, a copying apparatus, and a printer / fax / copier multifunction machine. Can be applied to.

FIG. 1 is a schematic view showing an example of the ink cartridge of the present invention. FIG. 2 is a schematic view including the case of the ink cartridge of FIG. FIG. 3 is an explanatory perspective view of the ink jet recording apparatus in a state where the cover of the ink cartridge loading unit is opened. FIG. 4 is a schematic diagram illustrating the overall configuration of the inkjet recording apparatus. FIG. 5 is a schematic enlarged view showing an example of the inkjet head of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Main body 102 Paper feed tray 103 Paper discharge tray 104 Ink cartridge loading part 111 Upper cover 112 Front surface 115 Front cover 131 Guide rod 132 Stay 133 Carriage 134 Recording head 135 Sub tank 141 Paper mounting part 142 Paper 144 Separation pad 151 Conveying belt 152 Counter roller 156 Charging roller 157 Conveyance roller 158 Densation roller 171 Separation claw 172 Paper discharge roller 173 Paper discharge roller 181 Double-sided paper supply unit 201 Ink cartridge 241 Ink bag 242 Ink inlet 243 Ink outlet 244 Cartridge exterior

Claims (17)

A recording ink containing at least a water-dispersible colorant, a water-dispersible resin, a wetting agent, and water,
The water dispersible colorant is a pigment dispersion containing a pigment, a pigment dispersant, and a polymer dispersion stabilizer,
The polymer dispersion stabilizer is an α-olefin-maleic anhydride copolymer represented by the following structural formula (1), the α-olefin-maleic anhydride copolymer, and a styrene-acrylic copolymer. Any one of at least one mixture selected from water-soluble polyurethane resins and water-soluble polyester resins,
The content of the wetting agent in the recording ink is 20 to 35% by mass,
Ratio (A / B) of solid content (A) of the water-dispersible resin in the recording ink and solid content (B) of the pigment in the water-dispersible colorant in the recording ink Is a recording ink, characterized in that it is 2-8.
However, in said structural formula (1), R represents an alkyl group. n shows the number of 30-100. A recording ink containing at least a water-dispersible colorant, a water-dispersible resin, a wetting agent, and water,
The water dispersible colorant is a pigment dispersion containing a pigment and a polymer dispersion stabilizer,
The pigment is a self-dispersing pigment having at least one hydrophilic group on the surface and exhibiting at least one of water dispersibility and water solubility in the absence of a dispersant,
The polymer dispersion stabilizer is an α-olefin-maleic anhydride copolymer represented by the following structural formula (1), the α-olefin-maleic anhydride copolymer, and a styrene-acrylic copolymer. Any one of at least one mixture selected from water-soluble polyurethane resins and water-soluble polyester resins,
The content of the wetting agent in the recording ink is 20 to 35% by mass,
Ratio (A / B) of solid content (A) of the water-dispersible resin in the recording ink and solid content (B) of the pigment in the water-dispersible colorant in the recording ink Is a recording ink, characterized in that it is 2-8.
However, in said structural formula (1), R represents an alkyl group. n shows the number of 30-100.   The recording ink according to claim 1, wherein the total content of the water-dispersible colorant and the water-dispersible resin is 12 to 40% by mass based on the total amount of the recording ink.   The recording ink according to any one of claims 1 to 3, wherein the α-olefin-maleic anhydride copolymer has a weight average molecular weight of 20,000 or less.   The α-olefin-maleic anhydride copolymer has an acid value of 100 to 400 mgKOH / g, and is used by being dissolved in either an alkali solution or an aqueous alkali solution equal to or more than the acid value. The recording ink according to any one of the above.   6. The recording ink according to claim 1, wherein the pigment dispersant is an anionic surfactant or a nonionic surfactant having an HLB value of 10 to 20.   The recording ink according to claim 6, wherein the nonionic surfactant having an HLB value of 10 to 20 is any one of polyoxyethylene-β-naphthyl ether, polyoxyethylene lauryl ether, and polyoxyethylene styrene phenyl ether.   The water dispersible resin is any one of a polyester resin, a polyurethane resin, an acrylic resin, and an acrylic silicone resin, and the minimum film forming temperature of the water dispersible resin is 30 ° C or lower. The recording ink described.   The recording according to any one of claims 1 to 8, wherein the wetting agent is at least one selected from glycerin, diethylene glycol, triethylene glycol, 1,3-butanediol and 3-methyl-1,3-butanediol. For ink.   The recording ink according to claim 1, comprising a surfactant, and the surfactant contains at least one selected from silicone surfactants and fluorine surfactants.   11. The recording ink according to claim 1, having a viscosity at 25 ° C. of 5 to 20 mPa · s and a static surface tension at 25 ° C. of 35 mN / m or less.   An ink cartridge comprising the recording ink according to claim 1 contained in a container.   12. An ink jet recording method comprising at least an ink flying step of recording an image by applying a stimulus to the recording ink according to claim 1 and causing the recording ink to fly.   The inkjet recording method according to claim 13, wherein the stimulus is at least one selected from heat, pressure, vibration, and light.   12. An ink jet recording apparatus comprising at least ink flying means for recording an image by applying a stimulus to the recording ink according to claim 1 and causing the recording ink to fly.   The inkjet recording apparatus according to claim 15, wherein the stimulus is at least one selected from heat, pressure, vibration, and light. An ink recorded matter comprising an image formed using the recording ink according to any one of claims 1 to 11 on a recording medium.