JP2007119574A - Recording ink, ink cartridge, inkjet recorder and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain recording ink that has excellent image quality and high-speed print response on plain paper, excellent storage stability and discharge stability and to provide an inkjet recorder and an inkjet recording method using the recording ink. <P>SOLUTION: The recording ink comprises at least water, a colorant, a wetting agent and a resin emulsion, has the change rate of specific viscosity represented by numerical expression 1: change rate of specific viscosity =ä[(η<SB>1</SB>-η<SB>0</SB>)/η<SB>0</SB>]×100}/T (η<SB>0</SB>is the initial viscosity (mPa s) of the recording ink before the evaporation test at 25°C at 50%RH environment; η<SB>1</SB>is the viscosity (mPa s) in course of time after T hour in the evaporation test; T is an elapsed time in the evaporation test) having points of ≤100 in <20 hours and >100 in 20-40 hours and the initial viscosity of ≥6.0 mPa s. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a recording ink excellent in image quality and high-speed printing on plain paper and having good storage stability and ejection stability, and an ink cartridge, an inkjet recording apparatus, and an inkjet recording method using the recording ink About.

  Inkjet printers have been rapidly spreading in recent years because they can print on plain paper, are easy to color, are small in size and inexpensive, and have low running costs. The characteristics required for the recording ink used in such an ink jet printer include (1) color tone and image density for achieving high image quality, no blur, and (2) achieving reliability. (3) Water resistance and light resistance to ensure storage stability of recorded images, and (4) High speed. The quick drying of the ink to achieve is mentioned, and various proposals have been made to satisfy these requirements.

As a colorant for the recording ink, dye ink was mainly used from the viewpoints of good color development and high reliability. However, recently, recorded images have light resistance and water resistance. For this reason, attention is also focused on pigment inks using pigments such as carbon black.
Further, in order to achieve high image quality and high-speed printing, recently, there is a tendency to make ink droplets smaller, and therefore, the nozzle diameter tends to be reduced. Furthermore, in order to ensure image fixability, many studies have been made to add a resin component to the ink. However, along with these, since the solid content concentration in the ink becomes high, it is very difficult to ensure reliability such as ejection stability in a printer with a reduced nozzle diameter.

In the past, in order to improve the reliability of the printer, the ink was designed in a direction to suppress the increase in viscosity as much as possible. For example, in Patent Document 1, the viscosity change when the ink is concentrated twice is within 10 times and the particle size change is within 3 times to prevent the aggregation of the pigment from suppressing the spread of the ink, Inks that can prevent omission are proposed. However, with this proposed ink, it is difficult to form a high-quality image on plain paper.
Patent Document 2 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 although its reliability is high, the image quality on plain paper is inferior.
Patent Document 3 proposes an ink having an ink viscosity of 600 times or less of the viscosity before evaporation when water is evaporated in an environment of 60 ° C. However, this proposed ink is also a dye ink, and by adding a water-soluble polymer, the ink reliability and the durability of the image quality are balanced, but there is a problem in water resistance.
Patent Document 4 requires a high-viscosity ink (5 to 15 mPa · s) to ensure high image quality, adjust the initial evaporation rate to ensure reliability, and adjust the viscosity. An ink having a specific compound added as a viscosity modifier for adjustment has been proposed. 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 the pigment has reliability after being left for 24 hours. Is an ink formulation with poor reliability when left untreated for a long time.

  In order to ensure high-speed and high-quality printing quality in this way, it is necessary to use ink with high viscosity. However, it is difficult to ensure reliability with such high-viscosity ink. Recording inks that are excellent in image quality and high-speed printing, and have good storage stability and ejection stability, and ink cartridges, ink-jet recording apparatuses, and ink-jet recording methods using the recording inks are still satisfactory. The current situation is that what can be done is not provided.

JP 2002-337449 A JP 2000-95983 A Japanese Patent Laid-Open No. 9-111166 JP 2001-262025 A

  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 is a recording ink excellent in image quality and high-speed printing on plain paper and having good storage stability and ejection stability, and an ink cartridge using the recording ink, and high ejection stability. Another object of the present invention is to provide an ink jet recording apparatus and an ink jet recording method capable of high-quality image recording.

Means for solving the problems are as follows. That is,
<1> A recording ink containing at least water, a colorant, a wetting agent, and a resin emulsion,
The recording ink has a specific viscosity change rate represented by the following formula 1 of 100 or less at less than 20 hours and more than 100 at 20 to 40 hours, and the initial viscosity of the recording ink. Is a recording ink characterized by being 6.0 mPa · s or more.
<Formula 1>
Specific viscosity change rate = {[(η ₁ −η ₀ ) / η ₀ ] × 100} / T
In Equation 1, η ₀ represents the initial viscosity (mPa · s) of the recording ink before performing the evaporation test in an environment of 25 ° C. and 50% RH. η ₁ represents the viscosity (mPa · s) after the elapse of T time when the evaporation test is performed. T represents the elapsed time in the evaporation test.
<2> The recording ink according to <1>, wherein the colorant is a water-dispersible colorant containing a pigment.
<3> The water dispersible colorant is a 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 the dispersant. Recording ink.
<4> The recording ink according to <2>, wherein the water-dispersible colorant is a polymer emulsion in which polymer fine particles contain a colorant that is insoluble or hardly soluble in water.
<5> The recording ink according to <2>, wherein the water-dispersible colorant is a pigment dispersed with any of a surfactant and a water-soluble polymer compound having a weight average molecular weight of 50,000 or less.
<6> The recording ink according to any one of <1> to <5>, wherein the resin emulsion is an acrylic silicone emulsion.
<7> The above <1>, wherein the water content in the recording ink is 35% by mass or more, and the total content of the colorant and the resin emulsion in the recording ink is 10 to 30% by mass in solid content. To <6>.
<8> The wetting agent contains at least one polyhydric alcohol, and at least one of the polyhydric alcohols has an equilibrium water content of 25% by mass or more in an environment of a temperature of 20 ° C. and 60% RH. The recording ink according to any one of <1> to <7>.
<9> The recording ink according to <8>, wherein one of the polyhydric alcohols is glycerin, and the content of the glycerin is 20 to 80% by mass of the whole wetting agent.
<10> The recording ink according to any one of <1> to <9>, wherein the total content of the wetting agent in the recording ink is 10 to 40% by mass.
<11> The recording ink according to any one of <1> to <10>, further including a surfactant and a penetrating agent.
<12> The recording ink according to <11>, wherein the surfactant is at least one selected from silicone surfactants and fluorine surfactants.
<13> The recording ink according to any one of <11> to <12>, wherein the penetrant is a polyol compound having a solubility in water of 20 ° C. of 0.2 to 5.0% by mass.
<14> The recording according to any one of <1> to <13>, further comprising an aminopropanediol compound, wherein the aminopropanediol compound is 2-amino-2-ethyl-1,3-propanediol. Ink.
<15> The recording ink according to any one of <1> to <14>, which is at least one selected from cyan ink, magenta ink, yellow ink, and black ink.
<16> An ink cartridge comprising the recording ink according to any one of <1> to <15> contained in a container.
<17> An ink jet having at least ink flying means for recording an image by applying a stimulus to the recording ink according to any one of <1> to <15> and causing the recording ink to fly. It is a recording device.
<18> The inkjet recording apparatus according to <17>, wherein the stimulus is at least one selected from heat, pressure, vibration, and light.
<19> The ink jet recording apparatus according to any one of <17> to <18>, wherein the ink flying unit includes a nozzle having a nozzle diameter of 35 μm or less and a printing speed is 8 ppm or more.
<20> A recording head having a plurality of pressurized liquid chambers, a nozzle and an ink supply path having a hole diameter of 35 μm or less communicating with the pressurized liquid chamber, a vibration plate, and an electromechanical conversion means for displacing the vibration plate. And an ink jet recording apparatus that forms a large ink droplet by merging before landing a plurality of ink droplets on a recording medium.
An ink jet recording apparatus, wherein the ink that forms the ink droplets is the recording ink according to any one of <1> to <15>.
<21> The ink discharge means for discharging the recording ink inside the nozzle hole before the specific viscosity change rate expressed by the following formula 1 exceeds 100 in the recording ink in the vicinity of the nozzle during printing < The inkjet recording apparatus according to any one of <17> to <20>.
<Formula 1>
Specific viscosity change rate = {[(η ₁ −η ₀ ) / η ₀ ] × 100} / T
In Equation 1, η ₀ represents the initial viscosity (mPa · s) of the recording ink before performing the evaporation test in an environment of 25 ° C. and 50% RH. η ₁ represents the viscosity (mPa · s) after the elapse of T time when the evaporation test is performed. T represents the elapsed time in the evaporation test.
<22> The inkjet recording apparatus according to <21>, wherein the ink discharging unit is a unit that discharges recording ink to a non-printing area.
<23> The inkjet recording apparatus according to any one of <21> to <22>, wherein the amount of discharged recording ink is 2,000 to 30,000 pl per minute per nozzle.
<24> The inkjet recording apparatus according to any one of <21> to <23>, wherein the amount of recording ink discharged is variable depending on a value of a temperature and humidity sensor.
<25> The inkjet recording apparatus according to any one of <21> to <23>, wherein the amount of discharged recording ink is variable depending on a specific viscosity change rate of the recording ink.
<26> An ink jet comprising 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 <15> and causing the recording ink to fly. It is a recording method.
<27> The inkjet recording method according to <26>, wherein the stimulus is at least one selected from heat, pressure, vibration, and light.
<28> An ink recorded matter comprising an image recorded on a recording medium using the recording ink according to any one of <1> to <15>.

The recording ink of the present invention contains at least water, a colorant, a wetting agent, and a resin emulsion,
The recording ink has a specific viscosity change rate represented by the following formula 1 of 100 or less at less than 20 hours and more than 100 at 20 to 40 hours, and the initial viscosity of the recording ink. Is 6.0 mPa · s or more.
<Formula 1>
Specific viscosity change rate = {[(η ₁ −η ₀ ) / η ₀ ] × 100} / T
In Equation 1, η ₀ represents the initial viscosity (mPa · s) of the recording ink before performing the evaporation test in an environment of 25 ° C. and 50% RH. η ₁ represents the viscosity (mPa · s) after the elapse of T time when the evaporation test is performed. T represents the elapsed time in the evaporation test.
According to the recording ink of the present invention, not only the viscosity increase and the particle size change with respect to the water evaporation amount of the ink are controlled as in the prior art, but also the specific viscosity change rate is controlled by taking the ink evaporation rate into consideration. The ink thickens before and after landing on the paper after the ink is ejected from the nozzle, and is excellent in image quality and high-speed printing on plain paper, and the rate of change in specific viscosity increases rapidly. Also, by suppressing the change in the volume average particle diameter of the ink to be small, the storage stability and ejection stability in the short term and the long term are improved.

  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 stored in the ink cartridge, the image quality on plain paper and high-speed printing are excellent, the storage stability and ejection stability are good, and image recording close to a clear printed matter can be performed. .

  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, it is excellent in image quality and high-speed printing on plain paper, has excellent storage stability and discharge stability, and enables high-quality image recording with high discharge stability.

  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, it is excellent in image quality and high-speed printing on plain paper, and has excellent storage stability and ejection stability, and an image close to a clear printed matter can be obtained.

  According to the present invention, it is possible to solve conventional problems, recording ink excellent in image quality and high-speed printing on plain paper, and excellent in storage stability and ejection stability, and ink using the recording ink It is possible to provide a cartridge, an inkjet recording apparatus capable of high-quality image recording with high ejection stability, and an inkjet recording method.

(Ink for recording)
The recording ink of the present invention contains at least water, a colorant, a wetting agent, and a resin emulsion, preferably contains a surfactant, a penetrating agent, an aminopropanediol compound, and, if necessary, other Contains ingredients.

The recording ink has a specific viscosity change rate represented by the following formula 1 by an evaporation test in an environment of 25 ° C. and 50% RH, which is 100 or less when less than 20 hours, and 100 when 20 to 40 hours. Has more points. By satisfying this requirement, the ink is thickened before and after landing on the recording medium after the ink is ejected from the nozzle, and high image quality can be formed even on plain paper. The ink having a rate of change in specific viscosity exceeding 100 that is faster than 20 hours may have poor ejection stability, and the ink having a rate of change in specific viscosity exceeding 100 after 40 hours has landed on the recording medium. Due to the low viscosity at the time, bleeding may occur easily.
<Formula 1>
Specific viscosity change rate = {[(η ₁ −η ₀ ) / η ₀ ] × 100} / T
In Equation 1, η ₀ represents the initial viscosity (mPa · s) of the recording ink before performing the evaporation test in an environment of 25 ° C. and 50% RH. η ₁ represents the viscosity (mPa · s) after the elapse of T time when the evaporation test is performed. T represents the elapsed time in the evaporation test.

The recording ink has an initial viscosity (η ₀ ) at 25 ° C. before the evaporation test of 6.0 mPa · s or more, preferably 7.5 to 10 mPa · s. In order to make the initial viscosity less than 6.0 mPa · s, it is necessary to suppress the pigment concentration to some extent, so it is difficult to ensure print quality with high image density. Also, depending on the ink, when the initial viscosity is less than 6.0 mPa · s, bleeding along the paper fibers may easily occur.

  Here, the specific viscosity change rate is determined by measuring a change in mass of the ink after leaving a certain amount of ink in an environment of 25 ° C. and 50% RH and leaving it for a certain period of time. 25 ° C.) and can be obtained from the above formula 1. As the viscosity, for example, a viscometer RL-500 manufactured by Toki Sangyo Co., Ltd. can be used.

As described above, the recording ink has at least water, a colorant, a wetting agent, and a resin emulsion as basic elements, and if necessary, contains a surfactant, a penetrating agent, and an aminopropanediol compound. These combinations and blending ratios are important. Among these, the influence of the equilibrium moisture content of the wetting agent is large, and the balance between the solid content concentration in the recording ink and the moisture amount, the balance between the wetting agent amount, and the like are important.
Hereinafter, although each component is demonstrated in detail, this invention is not necessarily limited to these.

-Colorant-
The colorant is preferably a water-dispersible colorant that is water-dispersible and contains a pigment.
Examples of the water dispersible colorant include (1) a 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 the dispersant, and (2) polymer fine particles. And a polymer emulsion containing a water-insoluble or poorly water-soluble coloring material, (3) a pigment dispersed with a surfactant and a water-soluble polymer having a weight average molecular weight of 50,000 or less, and the like. .

The water dispersible colorants (1) to (3) will be described as follows for the sake of convenience.
The above (1) is generally referred to as a self-dispersing pigment, and is mainly made hydrophilic by subjecting carbon black or the like to surface oxidation to disperse the pigment alone in water.
The above (2) is generally referred to as a capsule pigment, and the pigment is coated with a hydrophilic water-insoluble resin, and is made hydrophilic by a resin layer on the pigment surface to disperse the pigment in water. It is.
The above (3) is generally called a surfactant-dispersed pigment or a resin-dispersed pigment, and an interface between the pigment and water is obtained by a compound having a surface-active ability (here, a surfactant or a water-soluble polymer compound). In this way, the pigment is dispersed. The difference from the above (2) is whether or not the resin is dissolved in water, which affects the solvent resistance and color developability of the pigment dispersion.

  Such a water-dispersible colorant has water resistance, light resistance, and gas resistance because the colorant molecules are in an aggregated state (including a crystalline state) or coexist with resin molecules and do not exist as single molecules. When such a colorant is used, the image storage stability can be improved. In particular, a pigment that has been treated so that at least one hydrophilic group is bonded to the pigment surface directly or via another atomic group, and thus becomes dispersible in water without a dispersant, or water insoluble in fine resin particles. Alternatively, when a polymer emulsion containing a sparingly soluble color material is used, the ink viscosity relative to the colorant solid content can be kept low, so that a large amount of water-insoluble resin or wetting agent can be added.

In the above (1), the surface of the pigment is modified so that at least one hydrophilic group is bonded directly or via another atomic group. For this purpose, 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 a wet process using at least one of hypohalous acid and a salt thereof. A method such as oxidation treatment 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. In this case, since the pigment is surface-modified and the carboxyl group is bonded, not only the dispersion stability is improved, but also high-quality printing quality is obtained and the water resistance of the recording medium after printing is further improved. .
In addition, because this form of ink has excellent redispersibility after drying, printing is paused for a long period of time, and even when the moisture in the ink near the nozzles of the inkjet head evaporates, it does not cause clogging and can be easily cleaned. Good printing can be performed. Further, this self-dispersing pigment has a particularly large synergistic effect when combined with a surfactant and a penetrating agent, which will be described later, and it is possible to obtain a more reliable and high-quality image.
The volume average particle diameter of the self-dispersing pigment is preferably 0.01 to 0.16 μm in the ink.

Here, for example, as the self-dispersing type carbon black, those having ionicity are preferable, and those having an anionic charge or those having a cationic charge 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 (wherein M is a hydrogen atom) , 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). Can be mentioned. 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-described hydrophilic group is bonded to the surface of carbon black via another atomic group include, for example, —C ₂ H ₄ COOM (where M represents an alkali metal, quaternary ammonium), -PhSO ₃ M (however, Ph is an alkali metal .M representing a phenyl group, a quaternary ^{_{ammonium), - C 5 H 10 NH}} 3+ , and the like.

In the above (2), the polymer emulsion containing a coloring material is at least one of a polymer fine particle encapsulated with a pigment and a polymer fine particle surface adsorbed with a pigment. In this case, it is not necessary that all the pigments are encapsulated and / or adsorbed, and the pigments may be dispersed in the emulsion as long as the effects of the present invention are not impaired.
Examples of the polymer that forms the polymer emulsion include vinyl polymers, polyester polymers, polyurethane polymers, polymers disclosed in JP-A Nos. 2000-53897 and 2001-139849, and the like. Among these, vinyl polymers and polyester polymers are particularly preferable.
The volume average particle diameter of the polymer fine particles (colored fine particles) containing the colorant is preferably 0.01 to 0.16 μm in the ink.

  In said (3), it is preferable that the carboxyl group has couple | bonded with either the surfactant as a dispersing agent or a water-soluble polymer compound. When a carboxyl group is bonded to the dispersant, 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. Furthermore, the effect of preventing the show-through can be obtained. In particular, when a pigment dispersed with a dispersant having a carboxyl group bonded thereto and a penetrant are used in combination, a sufficient drying speed can be obtained even when printing on a relatively high-size recording medium such as plain paper. Is obtained, and the effect that there is little show-through is obtained. This is because the dissociation constant of carboxylic acid is small compared to other acid groups, so that after the pigment adheres to the recording medium, the pH value of the ink decreases, or the polyvalent metal such as calcium present near the surface of the recording medium. This is presumably because the solubility of the dispersant itself decreases due to the interaction with ions and the like, and the dispersant itself and the pigment aggregate.

Examples of the surfactant include an anionic surfactant such as polyoxyethylene alkyl ether acetate, polyoxyethylene alkyl ether phosphate, alkyl sulfonate, alkyl benzene sulfonate, oxalate sulfonate, and lauryl. And salts of acid salts and polyoxyethylene alkyl ether sulfates. Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene naphthyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene polyoxypropylene alkyl ester, polyoxyethylene sorbitan. Examples include fatty acid esters, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl amines, polyoxyethylene alkyl amides, and the like.
Commercially available products can be used as such surfactants. Examples of the commercially available products include Nippon Oil & Fats Co., Ltd., Nikko Chemicals Co., Ltd., Nippon Emulsion Co., Ltd., Nippon Shokubai Co., Ltd. It can be easily obtained from Ichi Kogyo Seiyaku Co., Ltd., Toho Chemical Co., Ltd., Kao Corp., Adeka Corp., Lion Corp., Aoki Oil Co., Ltd., Sanyo Chemical Industries Ltd., etc.

Examples of the water-soluble polymer compound having a weight average molecular weight of 50,000 or less include polyacrylic acid, polymethacrylic acid, acrylic acid-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid-acrylic acid. Alkyl ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid-alkyl acrylate copolymer, styne-methacrylic acid-alkyl acrylate copolymer, styrene- α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic acid copolymer-acrylic acid alkyl ester copolymer, styrene-maleic acid copolymer, vinylnaphthalene-maleic acid copolymer, acetic acid Vinyl-ethylene copolymer, vinyl acetate-fatty acid vinyl Examples thereof include ethylene copolymers, vinyl acetate-maleic acid ester copolymers, vinyl acetate-crotonic acid copolymers, vinyl acetate-acrylic acid copolymers, and the like.
These water-soluble polymer compounds preferably have a weight average molecular weight of 3,000 to 50,000, more preferably 5,000 to 30,000, and still more preferably 7,000 to 15,000.

As such a water-soluble polymer compound, an appropriately synthesized product or a commercially available product may be used.
Examples of the commercially available products include Johnson Polymer Co., Ltd., Nagase Chemtex Co., Ltd., Toagosei Co., Ltd., Mitsubishi Rayon Co., Ltd., Sumitomo Seika Co., Ltd., JSR Co., Ltd., Showa Polymer Co., Ltd. ), Arakawa Chemical Industries, Ltd., Nippon Shokubai Co., Ltd., Nippon Synthetic Chemical Co., Ltd., Kuraray Co., Ltd., etc.
The amount of the dispersant added can be appropriately added within a range in which the pigment is stably dispersed and the other effects of the present invention are not lost, and the mixing mass ratio (pigment: dispersant) of the two is 1: The range of 0.06 to 1: 3 is preferable, and the range of 1: 0.125 to 1: 3 is more preferable.

  The colorant is not particularly limited and may be appropriately selected depending on the purpose. A pigment is mainly used, but a dye may be contained within a range that does not deteriorate the weather resistance for the purpose of color tone adjustment. Absent.

There is no restriction | limiting in particular as said pigment, According to the objective, it can select suitably, For example, any of an inorganic pigment and an organic pigment may be sufficient.
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 pigments 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 black pigment is preferably carbon black. As a black ink, carbon black is excellent in color tone, excellent in water resistance, light repellency, dispersion stability, and inexpensive.
Other pigment (for example, carbon) surface is treated with resin, etc. to make it dispersible in water, and pigment (for example, carbon) surface is added with a functional group such as sulfone group or carboxyl group and dispersed in water Processed pigments made possible can be used.
Further, the pigment may be included in the microcapsule so that the pigment can be dispersed in water.

As described above, a pigment is mainly used for the colorant, but a dye may be contained within a range that does not deteriorate the light resistance for the purpose of adjusting the color tone. There is no restriction | limiting in particular as said dye, According to the objective, it can select suitably, For example, an acidic dye, a direct dye, a basic dye, a reactive dye etc. are mentioned.
There is no restriction | limiting in particular as said acidic dye, According to the objective, it can select suitably, What is known as a food dye, etc. are mentioned, for example, C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142; C.I. I. Acid Red 1, 8, 13, 14, 18, 26, 27, 35, 37, 42, 52, 82, 87, 89, 92, 97, 106, 111, 114, 115, 134, 186, 249, 254 289; C.I. I. Acid Blue 9, 29, 45, 92, 249; I. Acid Black 1, 2, 7, 24, 26, 94; I. Food Yellow 2, 3, 4; C.I. I. Food Red 7, 9, 14; C.I. I. Food black 1, 2, etc. are mentioned.

  Examples of the direct dye include C.I. I. Direct yellow 1, 12, 24, 26, 33, 44, 50, 86, 120, 132, 142, 144; I. Direct red 1, 4, 9, 13, 17, 20, 28, 31, 39, 80, 81, 83, 89, 225, 227; I. Direct orange 26, 29, 62, 102; I. Direct Blue 1, 2, 6, 15, 22, 25, 71, 76, 79, 86, 87, 90, 98, 163, 165, 199, 202; C.I. I. Direct black 19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154, 168, 171 and the like.

  Examples of the basic dye include C.I. I. Basic Yellow 1, 2, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29, 32, 36, 40, 41, 45, 49, 51, 53, 63, 65, 67 70, 73, 77, 87, 91; C.I. I. Basic Red 2, 12, 13, 14, 15, 18, 22, 23, 24, 27, 29, 35, 36, 38, 39, 46, 49, 51, 52, 54, 59, 68, 69, 70 73, 78, 82, 102, 104, 109, 112; I. Basic Blue 1, 3, 5, 7, 9, 21, 22, 26, 35, 41, 45, 47, 54, 62, 65, 66, 67, 69, 75, 77, 78, 89, 92, 93 105, 117, 120, 122, 124, 129, 137, 141, 147, 155; I. Basic black 2, 8, etc. are mentioned.

Examples of the reactive dye include C.I. I. Reactive Black 3, 4, 7, 11, 12, 17; C.I. I. Reactive Yellow 1, 5, 11, 13, 14, 20, 21, 22, 25, 40, 47, 51, 55, 65, 67; C.I. I. Reactive Red 1, 14, 17, 25, 26, 32, 37, 44, 46, 55, 60, 66, 74, 79, 96, 97; C.I. I. Reactive blue 1, 2, 7, 14, 15, 23, 32, 35, 38, 41, 63, 80, 95, and the like.
Among these dyes, acid dyes and direct dyes are particularly preferable.

  The content of the colorant in the recording ink is not particularly limited and may be appropriately selected depending on the purpose. The content is preferably 3 to 15% by mass and more preferably 5 to 12% by mass. When the content is less than 3% by mass, the image density may be thin and there may be an image having no contrast. When the content exceeds 15% by mass, it is difficult to ensure the dispersion stability of the colorant. Such clogging is likely to occur, and reliability may deteriorate.

-Resin emulsion-
A resin emulsion is added to the recording ink in order to improve image fixability. Here, the resin emulsion is obtained by dispersing resin fine particles in water as a continuous phase, and may contain a dispersant such as a surfactant as necessary. The content of resin fine particles as the dispersed phase component (content of resin fine particles in the resin emulsion) is generally preferably about 10 to 70% by mass.
Considering the use of the resin fine particles in an ink jet recording apparatus, the volume average particle size is preferably 10 to 1,000 nm, and more preferably 20 to 300 nm.
The resin fine particle component of the dispersed phase is not particularly limited and may be appropriately selected depending on the intended purpose. For example, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, styrene-butadiene system Examples thereof include resins, vinyl chloride resins, acrylic-styrene resins, acrylic silicone resins, and among these, acrylic silicone resins are particularly preferable from the viewpoint of good fixability.

As said resin emulsion, what was synthesize | combined suitably may be used and a commercial item may be used.
Examples of the commercially available products include, for example, Microgel E-100, E-2002, E-5002 (styrene-acrylic resin emulsion, manufactured by Nippon Paint Co., Ltd.), Boncoat 5454 (styrene-acrylic resin emulsion, Dainippon Ink). Chemical Industry Co., Ltd.), John Crill 775 (styrene-acrylic resin emulsion, manufactured by Johnson Polymer Co., Ltd.), SAE1014 (styrene-acrylic resin emulsion, manufactured by Nippon Zeon Co., Ltd.), Cybinol SK-200 (acrylic resin emulsion, Seiden Chemical) ), Primal AC-22, AC-61 (acrylic resin emulsion, manufactured by Rohm and Haas), Nanoacryl SBCX-2821, 3689 (acrylic-silicone resin emulsion, manufactured by Toyo Ink Manufacturing Co., Ltd.), # 3 70 (methyl methacrylate polymer resin emulsion manufactured by Mikuni Color Ltd.), PESRESIN A210 (polyester resin emulsion, Takamatsu Yushi Co., Ltd.), and the like.

  The content of the resin emulsion is preferably 0.1 to 30% by mass, more preferably 1 to 20% by mass, and still more preferably 5 to 15% by mass as an active ingredient (solid content).

The water content in the recording ink is preferably 35% by mass or more, and more preferably 45% by mass or more. In this case, the upper limit value is not particularly limited and can be appropriately selected according to the purpose, but is preferably 70% by mass. When the water content is less than 35% by mass, the increase in viscosity at the time of evaporation becomes too large, and the discharge stability may be deteriorated.
Further, the total content of the colorant and the resin emulsion in the recording ink is preferably 10 to 30% by mass, more preferably 12 to 18% by mass in terms of solid content. When the total content is less than 10% by mass, the image density is lowered and the fixability may be insufficient. When the total content exceeds 30% by mass, the increase in viscosity at the time of evaporation becomes too large. It may become clogged easily.

-Wetting agent-
The wetting agent is not particularly limited and may be appropriately selected depending on the purpose as long as it is easy to hydrogen bond, has a high viscosity by itself, has a high equilibrium moisture content, and decreases in the presence of moisture. For example, polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, sulfur-containing compounds, propylene carbonate, ethylene carbonate, etc. Is mentioned. These may be used alone or in combination of two or more.

Examples of the polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,3-propanediol, 1,3-butanediol, 2,3-butanediol, 1,4 butanediol, 3-methyl-1,3-butanediol, 1,5 pentanediol, 1,6 hexanediol, 2-methyl-2,4-pentanediol, tetraethylene glycol Polyethylene glycol, glycerin, 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, and propylene glycol monoethyl ether. It is done.
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 N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, and ε-caprolactam.
Examples of the amides include formamide, N-methylformamide, formamide, N, N-dimethylformamide and the like.
Examples of the amines include monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, and triethylamine.
Examples of the sulfur-containing compounds include dimethyl sulfoxide, sulfolane, thiodiethanol, thiodiglycol, and the like.

  Among these, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 3-methyl -1,3-butanediol, 1,5-pentanediol, tetraethylene glycol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, polyethylene glycol, 1,2,4-butanetriol, 1 2,6-hexanetriol is particularly preferred.

The wetting agent contains at least one polyhydric alcohol from the viewpoint that the effect of relaxing the water evaporation rate of the ink and improving the ejection reliability of the ink is obtained, and at least one of the polyhydric alcohols has a temperature. In an environment of 20 ° C. and a relative humidity of 60%, the equilibrium water content is preferably 25% by mass or more. Among the polyhydric alcohols, glycerin is particularly preferable because of its high effect of suppressing the aggregation of the colorant and preventing the particle size from increasing, although the viscosity rapidly increases with moisture evaporation.
The content of glycerin as the wetting agent is preferably 20 to 80% by mass of the entire wetting agent.
As the wetting agent used in combination with the glycerin, 1,3-butanediol and 3-methyl-1,3-butanediol are particularly preferable. The 1,3-butanediol and 3-methyl-1,3-butanediol, like glycerin, have a high equilibrium moisture content, high reliability, and uniform pixel spreading when the ink lands on the paper. Furthermore, the effect of keeping the colorant on the paper surface is also high. Glycerin has a high reliability improvement effect, but when added in a large amount, the image quality deteriorates, and the viscosity increase after evaporation of water becomes too large, and the discharge stability may be deteriorated. Butanediol: glycerin) is preferably 1: 4 to 4: 1, more preferably 1: 3 to 3: 1, and still more preferably 1: 1 to 3: 1.

  The content of the wetting agent in the recording ink is preferably 10 to 40% by mass, and more preferably 25 to 35% by mass. When the content is less than 10% by mass, the storage stability and ejection stability of the ink are deteriorated, and nozzle clogging is likely to occur. Bleeding and blurring of the color boundary occur, and the image quality deteriorates.

  The recording ink contains a surfactant and a penetrating agent. The surfactant has a purpose of lowering a static surface tension particularly in the vicinity of 1000 msec and promoting penetration into the paper when the ink lands on the paper. On the other hand, the penetrant has the purpose of lowering the more dynamic surface tension particularly in the vicinity of 10 to 100 msecc and promoting the spread on the paper surface at the moment when the ink has landed on the paper. By using these surfactants and penetrants together, it is possible to obtain an ink with more appropriate pixel spread and high penetrability into the paper (and hence quick-drying), resulting in a higher quality image. Is obtained at high speed.

-Surfactant-
Examples of the surfactant include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant. These may be used alone or in combination of two or more.

  Examples of the anionic surfactant include alkyl allyl, alkyl naphthalene sulfonate, alkyl phosphate, alkyl sulfate, alkyl sulfonate, alkyl ether sulfate, alkyl sulfosuccinate, alkyl ester sulfate, alkyl benzene sulfone. Acid salt, alkyl diphenyl ether disulfonate, alkyl aryl ether phosphate, alkyl aryl ether sulfate, alkyl aryl ether ester sulfate, olefin sulfonate, alkane olefin sulfonate, polyoxyethylene alkyl ether phosphate, poly Oxyethylene alkyl ether sulfate, ether carboxylate, sulfosuccinate, α-sulfo fatty acid ester, fatty acid salt, higher fatty acid and amino acid condensate, naphthenic acid And the like. Among these, polyoxyethylene alkyl ether acetate and dialkyl sulfosuccinate are particularly preferable.

Examples of the nonionic surfactant include acetylene glycol surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, and the like.
Examples of the acetylene glycol surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, An acetylene glycol surfactant such as 1,5-dimethyl-1-hexyn-3-ol is preferred. Examples of commercially available acetylene glycol surfactants include Surfynol 104, 82, 465, 485, and TG manufactured by Air Products (USA).

Examples of the cationic surfactant include alkylamine salts, dialkylamine salts, aliphatic amine salts, benzalkonium salts, quaternary ammonium salts, alkylpyridinium salts, imidazolinium salts, sulfonium salts, phosphonium salts, and the like. Can be mentioned.
Examples of the amphoteric surfactant include imidazoline derivatives such as imidazolinium betaine, dimethylalkyl lauryl betaine, alkyl glycine, and alkyldi (aminoethyl) glycine.

In order to further improve the image quality, it is more preferable to use either a fluorosurfactant or a silicone surfactant having high penetrating properties. Among these, a fluorosurfactant is particularly preferable. preferable.
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 polyoxyalkylene ether polymer compounds. Among these, the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain has a low foaming property, a low bioaccumulation property of a fluorine compound that has been regarded as a problem in recent years, and a high safety. Particularly preferred.

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.
Among these, compounds represented by at least one of the following structural formulas (1) to (2) are preferably exemplified.

However, in said structural formula (1), j represents the integer of 0-10. k represents an integer of 1 to 40.

In the structural formula (2), Rf represents a fluorine-containing group, and a perfluoroalkyl group is particularly preferable.
Examples of the perfluoroalkyl group preferably has a carbon number of 1 to 10, more preferably those of 1 to 3, for _example, -C _{n F 2n-1} (where, n is an integer of 1 to 10) Etc. Examples of the perfluoroalkyl group include —CF ₃ , —CF ₂ CF ₃ , —C ₃ F ₇ , —C ₄ F ₉ , etc. Among these, —CF ₃ , —CF ₂ CF ₃ Is particularly preferred.
m, n, and p represent an integer, n is preferably 1-4, m is preferably 6-25, and p is preferably 1-4.

As said fluorosurfactant, what was synthesize | combined suitably may be used and a commercial item may be used.
As this commercial item, for example, Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, 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), and the like. Among these, Zonyl FS-300, FSN, FSN-100, and FSO (all manufactured by DuPont) are particularly preferable from the viewpoint of improving reliability and color development.

The silicone surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, side chain modified polydimethylsiloxane, both terminal modified polydimethylsiloxane, one terminal modified polydimethylsiloxane, side Examples thereof include polydimethylsiloxane modified at both chain ends, and those having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group are particularly preferable because they exhibit good properties as an aqueous surfactant.
There is no restriction | limiting in particular as such surfactant, What was synthesize | combined suitably may be used and a commercial item may be used.
Such commercially available products can be easily obtained from, for example, Big Chemie, Shin-Etsu Silicone, Toray Dow Corning Silicone.

  The content of the surfactant in the recording ink is preferably 0.01 to 5.0% by mass, and more preferably 0.5 to 3% by mass. When the content is less than 0.01% by mass, there is no effect of addition. When the content exceeds 5.0% by mass, the permeability to the recording medium is unnecessarily high, and the image density is lowered or the image is not exposed. Problems such as occurrence may occur.

-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 polyol compounds 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- Examples thereof include diol and 2-ethyl-1,3-hexanediol.
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 the ink and adjusted to the desired physical properties, and can be appropriately selected according to the purpose. For example, diethylene glycol monophenyl ether, ethylene Alkyl and aryl ethers of polyhydric alcohols such as glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, 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.

-Aminopropanediol compound-
The aminopropanediol compound is a water-soluble organic basic compound, which also functions as a pH adjuster, improves the dispersion stability of the pigment, and ensures reliability such as ejection stability. Aminopropanediol derivatives are preferred.
There is no restriction | limiting in particular as said aminopropanediol derivative, According to the objective, it can select suitably, For example, 1-amino-2,3-propanediol, 1-methylamino-2,3-propanediol, 2 -Amino-2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol, and the like. Among these, the liquid contact with the member used in the ink flow path In view of high reliability, 2-amino-2-ethyl-1,3-propanediol is particularly preferable.

  The addition amount of the aminopropanediol compound in the recording ink is preferably 0.01 to 2% by mass, more preferably 0.1 to 2% by mass, and still more preferably 0.1 to 1.0% by mass. If the amount added is too large, disadvantages such as an increase in pH and an increase in viscosity may occur.

  There is no restriction | limiting in particular as said other component, It can select suitably as needed, For example, an antifoamer, antiseptic | preservative, a rust inhibitor, a pH adjuster, a chelating reagent, antioxidant, ultraviolet rays Examples thereof include an absorbent, an oxygen absorbent, a light stabilizer, and a viscosity modifier.

  There is no restriction | limiting in particular as said antifoamer, According to the objective, it can select suitably, For example, a silicone type antifoamer, a polyether type | system | group antifoamer, a fatty acid ester type | system | group antifoamer etc. are mentioned suitably. . These may be used individually by 1 type and may use 2 or more types together. Among these, a silicone type antifoaming agent is preferable at the point which is excellent in the bubble-breaking effect.

  Examples of the silicone-based antifoaming agent include oil-type silicone antifoaming agents, compound-type silicone antifoaming agents, self-emulsifying silicone antifoaming agents, emulsion-type silicone antifoaming agents, and modified silicone antifoaming agents. . Examples of the modified silicone-based antifoaming agent include amino-modified silicone antifoaming agents, carbinol-modified silicone antifoaming agents, methacrylic-modified silicone antifoaming agents, polyether-modified silicone antifoaming agents, alkyl-modified silicone antifoaming agents, and higher grades. Examples include fatty acid ester-modified silicone antifoaming agents and alkylene oxide-modified silicone antifoaming agents. Among these, the self-emulsifying type silicone antifoaming agent and the emulsion type silicone antifoaming agent are preferable in consideration of use in the recording ink which is an aqueous medium.

  Commercially available products may be used as the antifoaming agent, such as silicone antifoaming agents (KS508, KS531, KM72, KM85, etc.) manufactured by Shin-Etsu Chemical Co., Ltd., Toray Dow Corning Co., Ltd. Company-made silicone antifoaming agents (Q2-3183A, SH5510, etc.), Nihon Unicar Corporation silicone antifoaming agents (SAG30 etc.), Asahi Denka Kogyo Co., Ltd. antifoaming agents (Adecanate series, etc.), etc. Can be mentioned.

  There is no restriction | limiting in particular as content in the said recording ink of the said antifoamer, According to the objective, it can select suitably, For example, 0.001-3 mass% is preferable, 0.05-0.5 The mass% is more preferable.

  Examples of the antiseptic / antifungal agent include 1,2-benzisothiazolin-3-one, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, and sodium pentachlorophenol. Can be mentioned.

  The pH adjuster is not particularly limited as long as it can adjust the pH to 7 or more without adversely affecting the ink to be prepared, and any substance can be used according to the purpose. Examples of the pH adjuster include amines such as diethanolamine and triethanolamine, hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide and potassium hydroxide; ammonium hydroxide and quaternary ammonium hydroxide. Quaternary phosphonium hydroxide, alkali metal carbonates such as lithium carbonate, sodium carbonate, potassium carbonate, and the like.

Examples of the rust preventive agent include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite, 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 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 can be mentioned.
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, and trinonylphenyl phosphite.

Examples of the ultraviolet absorber include a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, a salicylate ultraviolet absorber, a cyanoacrylate ultraviolet absorber, and a nickel complex ultraviolet absorber.
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 UV 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 is obtained by dispersing or dissolving water, a colorant, a wetting agent, a resin emulsion, preferably a surfactant, a penetrating agent, an aminopropanediol compound, and, if necessary, other components in an aqueous medium. If necessary, it is stirred and mixed. 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, pH and the like are preferably in the following ranges.

The viscosity of the recording ink is preferably 20 mPa · s or less, more preferably 15 mPa · s or less at 25 ° C. If the viscosity exceeds 20 mPa · s, it may be difficult to ensure ejection stability.
The dynamic surface tension of the recording ink at 25 ° C. and 10 to 100 msec is preferably 20 to 35 mN / m, and more preferably 25 to 33 mN / m.
In the recording ink, the static surface tension around 25 mC and 1000 msec is preferably 20 to 35 mN / m, and more preferably 22 to 28 mN / m.
The pH of the recording ink is preferably 7 to 10, for example.

  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 recorded. When recording is performed using an ink set in which all colors are combined, a full color image is recorded. 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. Therefore, a printer equipped with any inkjet head such as an electrostatic type (see Japanese Patent Application Laid-Open No. 6-71882) that discharges ink droplets by changing the volume in the ink flow path. Can also be used well.

  The recording ink of the present invention can be suitably used in various fields, and can be suitably used in an image recording apparatus (printer or the like) based on an ink jet recording method. The recording ink is heated at 50 to 200 ° C., and can be used for a printer or the like having a function of promoting print fixing, and is particularly suitable for the following ink cartridge, ink jet recording apparatus, and ink jet recording method of the present invention. Can be used for

(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 attached to various ink jet recording apparatuses.

  The ink cartridge of the present invention contains the recording ink (or ink set) of the present invention and can be used by being detachably attached to various ink jet recording apparatuses, and can also be used in the ink jet recording apparatus of the present invention described later. It is particularly preferable to use it detachably.

(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, control means, and the like.
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 recording 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 recording 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.
In the present invention, it is preferable that at least a part of the liquid chamber portion, the fluid resistance portion, the vibration plate, and the nozzle member of the inkjet head is formed of a material containing at least one of silicon and nickel.
The head preferably has a nozzle plate having a water repellent treatment applied to the ink discharge surface, and the water repellent finish is selected from PTFE-Ni eutectoid processing, fluororesin processing, and silicone resin processing. Either is preferred.
The nozzle diameter of the inkjet nozzle is preferably 35 μm or less, more preferably 30 μm or less, and still more preferably 15 to 25 μm. The printing speed is preferably 8 ppm or more. Thereby, more stable and high-quality image recording can be performed.
Preferably, the ink jet head has a sub tank for supplying ink, and the sub tank is supplemented with ink from an ink cartridge through a supply tube.

  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 changes 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, and electrostatic actuators that use electrostatic forces. .

  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 liquidated from the nozzle holes of the recording head by the pressure of the bubbles. For example, a method of discharging and ejecting droplets can be used. 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 is bent, and the pressure chamber For example, a method in which the volume is reduced 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 2 to 40 pl, for example, and the ejection jet speed is preferably 5 to 20 m / second, and the driving thereof. The frequency is preferably 1 kHz or more, and the resolution is preferably 300 dpi or more.

The ink jet recording apparatus of the present invention preferably has a reversing unit that can perform double-sided printing by reversing the recording surface of the recording medium. Examples of the reversing means include a conveying belt having electrostatic force, a means for holding a recording medium by air suction, and a combination of a conveying roller and a spur.
It is preferable to have an endless transport belt and transport means for transporting the surface of the transport belt while charging and holding the recording medium. In this case, it is particularly preferable to charge the conveyor belt by applying an AC bias of ± 1.2 kV to ± 2.6 kV to the charging roller.

  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.

  The inkjet recording apparatus of the present invention includes a plurality of pressurized liquid chambers, nozzles and ink supply passages having a hole diameter of 35 μm or less communicating with the pressurized liquid chambers, a vibration plate, and electromechanical conversion means for displacing the vibration plate. The ink for forming the ink droplets is formed by merging before a plurality of ink droplets are continuously ejected and landed on the recording medium. Ink is preferred. As a result, it is possible to ensure ejection stability even with high viscosity ink.

In this case, the recording ink in the vicinity of the nozzle during printing may have an ink discharging means for discharging the recording ink inside the nozzle hole before the specific viscosity change rate expressed by the following formula 1 exceeds 100. preferable.
<Formula 1>
Specific viscosity change rate = {[(η ₁ −η ₀ ) / η ₀ ] × 100} / T
In Equation 1, η ₀ represents the initial viscosity (mPa · s) of the recording ink before performing the evaporation test in an environment of 25 ° C. and 50% RH. η ₁ represents the viscosity (mPa · s) after the elapse of T time when the evaporation test is performed. T represents the elapsed time in the evaporation test.

  The recording ink of the present invention has an ink discharging means for discharging the ink inside the nozzle hole before it because the viscosity suddenly increases after a certain period of time depending on the printing environment. preferable. As the ink discharging means, a method of ejecting ink to a non-printing area is preferable, and the number of scans of a carriage on which the head is mounted is counted, and when the value exceeds a certain threshold (or every predetermined time), A method is employed in which the head is driven to eject a certain amount of ink so that the ink is ejected to the non-printing area. The amount of ink to be discharged to the non-printing area can be set arbitrarily by changing the number of times the head is driven when ejecting the ink and controlling the threshold value. It is preferable to set so that the minimum amount of ink is ejected within a range in which the property can be maintained. With respect to the recording ink of the present invention, it has been confirmed that reliability is ensured when 2,000 to 30,000 pl of ink is discharged per minute per nozzle.

Since the evaporation speed of the recording ink is affected by the temperature and humidity environment, and there is a slight difference between colors, the ink jet recording apparatus of the present invention is provided with a temperature and humidity meter sensor. The amount of ink discharged from the ink can be changed.
In the ink jet recording apparatus of the present invention, it is preferable that the amount of recording ink to be discharged is variable depending on the rate of change in the specific viscosity of the recording ink. The amount of ink discharged from the inside of the nozzle hole can be changed by changing the interval of ink discharge and the number of droplets discharged once.
Further, as an example of providing an ink receiver that receives the discharged recording ink, the ink receiver can be provided outside the belt that conveys the recording medium, as long as the structure of the recording apparatus allows. In this way, when a certain number of scans is exceeded (or every certain time), a certain amount of ink is discharged to the ink receiver provided in the non-printing area, thereby ensuring more stable ejection. In addition, an inkjet recording apparatus can be provided.

  One mode for 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. The ink jet recording apparatus shown in FIG. 3 stocks an apparatus main body 101, a paper feed tray 102 for loading paper loaded 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, the carriage 133 is slid in the main scanning direction by guide rods 131 and stays 132 which are horizontally mounted on left and right side plates (not shown). It is held movably and moved and scanned in the direction of the arrow in FIG. 5 by a main scanning motor (not shown).

The carriage 133 includes a plurality of recording heads 134 including four inkjet recording heads that discharge recording ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). The ink discharge ports are arranged in a direction crossing the main scanning direction, and are mounted with the ink droplet discharge 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 a change, an electrostatic actuator using an electrostatic force, or the like as an energy generating means for discharging recording 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 and supplemented with the recording ink of the present invention from the ink cartridge 201 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 102, a half-moon roller (feeding) that separates and feeds the paper 142 from the paper stacking unit 141 one by one. 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. A conveying guide 153 and a tip pressure roller 155 urged toward the conveying belt 151 by a pressing member 154, and a charging roller 156 as a charging means for charging the surface of the conveying belt 151. It has been.

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 adsorption surface formed of a resin 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 same material as the surface layer. And a back layer (medium resistance layer, earth layer) subjected to resistance control 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. 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 transport 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 tip pressing 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, when the upper portion of the apparatus main body 101 is closed and installed, for example, even when the apparatus main body 101 is stored in a rack or an object is placed on the upper surface of the apparatus main body 101, the ink cartridge 201 is replaced. It can be done easily.

  Here, an example is described in which the present invention is applied to a serial (shuttle type) ink jet recording apparatus that is scanned by a carriage, but the present invention can be similarly applied to a line type ink jet recording apparatus having a line type head.

  Further, 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. For example, the ink jet recording apparatus, the facsimile apparatus, the copying apparatus, the printer / fax / copier multifunction machine, etc. It can be particularly preferably applied.

The ink jet head of the ink jet recording apparatus of the present invention will be described below.
FIG. 6 is an enlarged view of elements of an ink jet head according to an embodiment of the present invention, and FIG. 7 is an enlarged cross-sectional view of the main part in the channel-to-channel direction of the head.
This ink jet head has an ink supply port (not shown), a frame 10 formed with a carving serving as a common liquid chamber 1b, a fluid resistance portion 2a, a carving serving as a pressurized liquid chamber 2b, and a communication communicating with the nozzle 3a. The flow path plate 20 having the opening 2c, the nozzle plate forming the nozzle 3a, the vibration plate 60 having the convex portion 6a, the diaphragm portion 6b, and the ink inlet 6c, and the vibration plate 60 via the adhesive layer 70 A laminated piezoelectric element 50 bonded to each other and a base 40 to which the laminated piezoelectric element 50 is fixed are provided.

The base 40 is made of, for example, a barium titanate ceramic, and the laminated piezoelectric elements 50 are arranged in two rows and joined.
The laminated piezoelectric element 50 is composed of a lead zirconate titanate (PZT) piezoelectric layer having a thickness of 10 to 50 μm / layer and an internal electrode layer made of silver / palladium (AgPd) having a thickness of several μm / layer alternately. Laminated. This internal electrode layer is connected to the external electrode at both ends.
The laminated piezoelectric element 50 is divided onto comb teeth by half-cut dicing, and is used as a drive unit 5f and a support unit 5g (non-drive unit) one by one. The length of the outer electrode is limited by cutting or the like so as to be divided by half-cut dicing, and these become a plurality of individual electrodes. The other is not divided by dicing but is conductive and becomes a common electrode.
The FPC 8 is soldered to the individual electrodes of the drive unit. The common electrode is joined to the Gnd electrode of the FPC 8 by providing an electrode layer at the end of the laminated piezoelectric element 50 and turning it around. A driver IC (not shown) is mounted on the FPC 8. Thereby, the drive voltage application to the drive part 5f is controlled.

The diaphragm 60 is joined to a support portion and an island-shaped convex portion (island portion) 6a that joins the thin film diaphragm portion 6b, the laminated piezoelectric element 50 that is the driving portion 5f formed at the center portion of the diaphragm portion 6b. A thick film portion including a beam and an opening serving as an ink inflow port 6c are formed by stacking two layers of Ni plating films by electroforming. The diaphragm portion has a thickness of 3 μm and a width of 35 μm (one side).
The island-shaped convex portion 6a of the diaphragm 60, the driving unit 5f of the laminated piezoelectric element 50, the diaphragm 50, and the frame 10 are bonded by patterning the adhesive layer 70 containing a gap material. .

The flow path plate 20 uses a silicon single crystal substrate, and the engraving that becomes the fluid resistance portion 2a and the pressurized liquid chamber 2b and the through-hole that becomes the communication port 2c at the position with respect to the nozzle 3a are patterned by an etching method.
The portion left by etching becomes the partition wall 2d of the pressurized liquid chamber 2b. Further, in this head, a portion for narrowing the etching width is provided, and this is used as the fluid resistance portion 2a.
The nozzle plate 30 is formed of a metal material, for example, an Ni plating film formed by an electroforming method, and has a large number of nozzles 3a that are fine discharge ports for causing ink droplets to fly. The internal shape (inner shape) of the nozzle 3a is formed in a horn shape (may be a substantially cylindrical shape or a substantially frustum shape). The diameter of the nozzle 3a is approximately 20 to 35 μm as the diameter on the ink droplet outlet side. The nozzle pitch in each row was 150 dpi.
On the ink ejection surface (nozzle surface side) of the nozzle plate 30, a water repellent treatment layer 3b subjected to a water repellent surface treatment (not shown) is provided. Ink, such as PTFE-Ni eutectoid plating, electrodeposition coating of fluororesin, vapor-deposited fluororesin (for example, fluorinated pitch, etc.), baking after solvent application of silicone resin and fluororesin A water-repellent film selected according to physical properties is provided to stabilize the ink droplet shape and flight characteristics so that high-quality image quality can be obtained. Among these, for example, various materials are known as the fluororesin, but a modified perfluoropolyoxetane (manufactured by Daikin Industries, Ltd., trade name: OPTOOL DSX) has a thickness of 30 to 100 mm. Thus, good water repellency can be obtained by vapor deposition.
The frame 10 that forms the engraving that becomes the ink supply port and the common liquid chamber 1b is manufactured by resin molding.

In the ink jet head configured as described above, a driving waveform (pulse voltage of 10 to 50 V) is applied to the driving unit 5f in accordance with the recording signal, whereby the driving unit 5f is displaced in the stacking direction, and the diaphragm 30 The pressurized liquid chamber 2b is pressurized via the pressure to increase the pressure, and ink droplets are ejected from the nozzle 3a.
Thereafter, the ink pressure in the pressurizing liquid chamber 2b is reduced with the completion of ink droplet ejection, and negative pressure is generated in the pressurizing liquid chamber 2b due to the inertia of the ink flow and the discharge process of the driving pulse, and the ink is filled. Move to the process. At this time, the ink supplied from the ink tank flows into the common liquid chamber 1b, passes from the common liquid chamber 1b through the ink inlet 6c, passes through the fluid resistance portion 2a, and is filled into the pressurized liquid chamber 2b.
The fluid resistance portion 2a is effective in damping the residual pressure vibration after ejection, but becomes resistant to the maximum filling (refill) due to surface tension. By appropriately selecting the fluid resistance portion 2a, it is possible to balance the attenuation of the residual pressure and the refill time, and to shorten the time (drive cycle) until the transition to the next ink droplet ejection operation.

<Ink record>
The ink recorded matter recorded by the ink jet recording apparatus and the ink jet recording method 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 alone or in combination of two or more.
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.

Example 1
-Preparation of black ink-
An ink composition having the following formulation was prepared and sufficiently stirred at room temperature, followed by filtration through a membrane filter having an average pore size of 1.5 μm to produce the black ink of Example 1.
<Ink composition>
KM-9036 (manufactured by Toyo Ink Manufacturing Co., Ltd., self-dispersing carbon black): 40% by mass
・ Glycerin as a wetting agent: 10% by mass
・ 3-Methyl-1,3-butanediol as a wetting agent: 15% by mass
・ 2-Pyrrolidone as a wetting agent: 2% by mass
・ 2-Ethyl-1,3-hexanediol as penetrant 2 mass%
-Fluorosurfactant represented by the following structural formula: 1% by mass
However, in said structural formula, j represents 2 and k represents 8.
・ Acrylic silicone resin emulsion (manufactured by Toyo Ink Manufacturing Co., Ltd., NANOCRYL SBCX-2821) ... 15% by mass
・ Silicone antifoaming agent (manufactured by Shin-Etsu Chemical Co., Ltd., KS508) ... 0.1% by mass
・ Ion exchange water

(Example 2)
<Preparation of yellow ink>
-Preparation of polymer solution A-
After sufficiently replacing the inside of a 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube, and dropping funnel, 11.2 g of styrene, 2.8 g of acrylic acid, 12.0 g of lauryl methacrylate Then, 4.0 g of polyethylene glycol methacrylate, 4.0 g of styrene macromer, and 0.4 g of mercaptoethanol were mixed and heated to 65 ° C. Next, 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g of lauryl methacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0 g of hydroxylethyl methacrylate, 36.0 g of styrene macromer, 3.6 g of mercaptoethanol, azobismethylvalero A mixed solution of 2.4 g of nitrile and 18 g of methyl ethyl ketone was dropped into the flask over 2.5 hours. After completion of the dropwise addition, a mixed solution of 0.8 g of azobismethylvaleronitrile and 18 g of methyl ethyl ketone was dropped into the flask over 0.5 hours. Next, after aging at 65 ° C. for 1 hour, 0.8 g of azobismethylvaleronitrile was added, and further aging was performed for 1 hour. After completion of the reaction, 364 g of methyl ethyl ketone was added to the flask to obtain 800 g of a polymer solution A having a concentration of 50% by mass.

-Preparation of pigment-containing polymer fine particle water dispersion-
28 g of the obtained polymer solution A, C.I. I. 26 g of Pigment Yellow 74, 13.6 g of a 1 mol / L potassium hydroxide aqueous solution, 20 g of methyl ethyl ketone, and 13.6 g of ion-exchanged water were sufficiently stirred, and then kneaded using a roll mill. The obtained paste was put into 200 g of ion-exchanged water and stirred sufficiently, and then methyl ethyl ketone and water were distilled off using an evaporator to obtain an aqueous dispersion of yellow polymer fine particles.

-Preparation of yellow ink-
An ink composition having the following formulation was prepared and sufficiently stirred at room temperature, followed by filtration through a membrane filter having an average pore size of 1.5 μm to produce the yellow ink of Example 2.
-Yellow polymer fine particle dispersion prepared above: 40% by mass
・ Glycerin as wetting agent: 8% by mass
・ 1,3-butanediol as a wetting agent: 20% by mass
・ 2,2,4-Trimethyl-1,3-pentanediol as penetrant 2 mass%
-Fluorosurfactant represented by the following structural formula: 1% by mass
However, in said structural formula, j represents 2 and k represents 8.
・ Acrylic silicone resin emulsion (Toyo Ink Mfg. Co., Ltd., NANOCRYL SBCX-2821) ... 10% by mass
・ Silicone antifoaming agent (manufactured by Shin-Etsu Chemical Co., Ltd., KS508) ... 0.1% by mass
・ Ion exchange water

(Example 3)
<Preparation of magenta ink>
-Preparation of pigment-containing polymer fine particle water dispersion-
In Example 2, C.I. I. Pigment Yellow 74, C.I. I. An aqueous dispersion of magenta polymer fine particles was prepared in the same manner as in Example 1 except that the pigment red 122 was used.

-Magenta ink production-
An ink composition having the following formulation was prepared and sufficiently stirred at room temperature, and then filtered through a membrane filter having an average pore size of 1.5 μm to prepare a magenta ink of Example 3.
・ Dispersion of magenta polymer fine particles prepared as above: 50% by mass
・ Glycerin as a wetting agent: 10% by mass
・ 1,3-butanediol as a wetting agent: 18% by mass
・ 2,2,4-Trimethyl-1,3-pentanediol as penetrant 2 mass%
-Fluorosurfactant represented by the following structural formula: 1% by mass
However, in said structural formula, j represents 2 and k represents 8.
・ Acrylic silicone resin emulsion (Toyo Ink Mfg. Co., Ltd., NANOCRYL SBCX-2821) ... 10% by mass
・ Silicone antifoaming agent (KS508, manufactured by Shin-Etsu Chemical Co., Ltd.) ... 0.1% by mass
・ Ion exchange water

Example 4
<Preparation of cyan ink>
-Preparation of pigment-containing polymer fine particle water dispersion-
In Example 2, C.I. I. Pigment Yellow 74, C.I. I. An aqueous dispersion of cyan polymer fine particles was prepared in the same manner as in Example 1 except that the pigment blue was changed to 15: 3.

-Preparation of cyan ink-
An ink composition having the following formulation was prepared and sufficiently stirred at room temperature, followed by filtration through a membrane filter having an average pore size of 1.5 μm to prepare the cyan ink of Example 4.
・ Cyan polymer fine particle dispersion: 40% by mass
・ Glycerin as wetting agent: 8% by mass
・ 1,3-butanediol as a wetting agent: 20% by mass
・ 2,2,4-Trimethyl-1,3-pentanediol as penetrant 2 mass%
-Fluorosurfactant represented by the following structural formula: 1% by mass
However, in said structural formula, j represents 2 and k represents 8.
・ Acrylic silicone resin emulsion (Toyo Ink Mfg. Co., Ltd., NANOCRYL SBCX-2821) ... 10% by mass
・ Silicone antifoaming agent (KS508, manufactured by Shin-Etsu Chemical Co., Ltd.) ... 0.1% by mass
・ Ion exchange water

(Comparative Example 1)
The ink extracted from the yellow ink cartridge of a commercial product (PX ink) manufactured by Epson was used as the yellow ink of Comparative Example 1. The initial viscosity of this ink at 25 ° C. was 3.1 mPa · s.

(Comparative Example 2)
The ink extracted from the commercially available Epson magenta ink cartridge (PX ink) was used as the magenta ink of Comparative Example 2. The initial viscosity of this ink at 25 ° C. was 3.5 mPa · s.

(Comparative Example 3)
The ink extracted from the cyan ink cartridge of a commercial product (PX ink) manufactured by Epson was used as the cyan ink of Comparative Example 3. The initial viscosity of this ink at 25 ° C. was 3.3 mPa · s or less.

(Comparative Example 4)
The ink extracted from the black ink cartridge of a commercial product (PX ink) manufactured by Epson was used as the black ink of Comparative Example 4. The initial viscosity of this ink at 25 ° C. was 3.4 mPa · s or less.

Next, each ink of Examples 1 to 4 and each ink of Comparative Examples 1 to 4 were evaluated (1) as follows.
<Evaluation (1): Measurement of specific viscosity change rate with evaporation time>
A certain amount of each of the inks of Examples 1 to 4 and Comparative Examples 1 to 4 was allowed to stand in an environment of 25 ° C. and 50% RH, and the ink mass change after being left for a certain period of time was measured. The viscosity (25 ° C.) of the ink was measured. And the specific viscosity change rate was calculated | required from following Numerical formula 1.
<Formula 1>
Specific viscosity change rate = {[(η ₁ −η ₀ ) / η ₀ ] × 100} / T
In Equation 1, η ₀ represents the initial viscosity (mPa · s) of the recording ink before performing the evaporation test in an environment of 25 ° C. and 50% RH. η ₁ represents the viscosity (mPa · s) after the elapse of T time when the evaporation test is performed. T represents the elapsed time in the evaporation test.
The viscosity of the ink was measured using a viscometer RL-500 manufactured by Toki Sangyo Co., Ltd. FIG. 8 shows the relationship between the elapsed time and the specific viscosity change rate (25 ° C.).

From the results of FIG. 8, each of the inks of Examples 1 to 4 has a point that the rate of change in specific viscosity exceeds 100 during 20 to 40 hours. In contrast, each of the inks of Comparative Examples 1 to 4 had a specific viscosity change rate exceeding 100 at a place longer than 40 hours.
The initial viscosity of the ink of Example 1 is 8.3 mPa · s at 25 ° C., and the initial viscosity of the ink of Example 2 is 8.0 mPa · s at 25 ° C., and the initial viscosity of the ink of Example 3 is 25 ° C. Was 8.2 mPa · s at 25 ° C., and the initial viscosity of the ink of Example 4 was 8.1 mPa · s at 25 ° C., both of which exceeded 6 mPa · s.

(Example 5 and Comparative Example 5)
-Preparation and evaluation of ink set-
Next, the ink set of Example 5 was prepared by combining the inks of Examples 1 to 4. Further, an ink set of Comparative Example 5 was prepared by combining the inks of Comparative Examples 1 to 4. The ink sets of Example 5 and Comparative Example 5 were evaluated (2) as follows. The results are shown in Table 1.

<Evaluation (2): Print quality>
For the ink set of Example 5, an ink jet printer (IPRIC G707, manufactured by Ricoh Co., Ltd.) was used. For the ink set of Comparative Example 5, an ink jet printer (PM-4000PX, manufactured by Epson) was used to print a color image in a mode in which the printing speed was the same. The evaluation paper was plain paper.
The printed images were visually observed for character bleeding and color boundary bleeding and evaluated according to the following criteria.
〔Evaluation criteria〕
◎: No bleeding ○: Little bleeding △: Slight bleeding (Actual usable level)
X: There is clear bleeding (actually unusable level)

From the results shown in Table 1, the ink set of Example 5 has a greater ink viscosity than the ink set of Comparative Example 5 due to the evaporation of water before and after the ink lands on the paper. It was found that a clear image with no image could be obtained.

(Comparative Example 6)
−Preparation of ink set−
Fluorine-based surfactant and penetrant (2,2,4-trimethyl-1,3-pentanediol or 2-ethyl-1,3-hexanediol) were removed from each ink in the ink set of Example 5. Except for this, an ink set of Comparative Example 6 was produced in the same manner as the ink set of Example 5.

(Example 6)
−Preparation of ink set−
Example 5 except that the penetrant (2,2,4-trimethyl-1,3-pentanediol or 2-ethyl-1,3-hexanediol) was removed from each ink in the ink set of Example 5. The ink set of Example 6 was produced in the same manner as the ink set of No. 6.

(Example 7)
−Preparation of ink set−
An ink set of Example 7 was produced in the same manner as the ink set of Example 5 except that the fluorosurfactant was removed from each ink in the ink set of Example 5.

<Evaluation>
Next, the dynamic surface tension of each black ink in the ink sets of Comparative Example 6, Example 6, and Example 7 and the black ink (Example 1) in the ink set of Example 5 was measured.
Here, the dynamic surface tension was measured at 25 ° C. using a dynamic surface tension measuring device BP-2 manufactured by Cruz.
In the black ink of Example 6 to which no penetrant was added, the dynamic surface tension at 10 to 100 msec was 38 mN / m and did not decrease. The static surface tension around 1,000 msec was 25 mN / m.
In addition, the black ink of Example 7 to which no fluorosurfactant was added had a dynamic surface tension of 40 mN / m at 10 to 100 msec and a static surface tension of about 37 mN / m in the vicinity of 1,000 msec. m, and the overall surface tension remained high.
In addition, the black ink of Example 5 had a dynamic surface tension of 33 mN / m at 10 to 100 msec, and a static surface tension near 1,000 msec of 25 mN / m.
The black ink of Comparative Example 6 had a dynamic surface tension of 47 mN / m at 10 to 100 msec, and a static surface tension of about 46.5 mN / m near 1,000 msec.

Further, when the above evaluation (1) was performed on the inks of the ink sets of Comparative Example 6, Example 6, and Example 7, the specific viscosity change rate of each ink of the ink set of Comparative Example 6 exceeded 100. The score was after 40 hours. In addition, each ink of the ink sets of Examples 6 and 7 had a point of change in specific viscosity exceeding 100 for 20 to 40 hours.
The initial viscosity of each ink of Comparative Example 6 is 25 ° C. and around 6.5 mPa · s, and the initial viscosity of each ink of Example 6 is 7.0 mPa · s at 25 ° C. The initial viscosity of each ink in Example 7 was 25 ° C. and was around 7.5 mPa · s.
In addition, the above evaluation (2) was performed on each ink set of the ink sets of Comparative Example 6, Example 6, and Example 7. The results are shown in Table 2.

From the results of Table 2, it was recognized that the ink set of Comparative Example 6 to which no surfactant and penetrant were added was larger in both character blur and color boundary blur compared to Examples 6 and 7. The ink sets of Examples 6 and 7 were slightly inferior in character bleeding and color boundary bleeding as compared with the ink set of Example 5, but were practically usable.

(Comparative Example 7)
-Production of cyan ink-
A cyan ink of Comparative Example 7 was prepared in the same manner as in Example 4, except that the glycerin as a wetting agent was 5 mass% and 1,3-butanediol was 23 mass% in the cyan ink of Example 4. did.

(Comparative Example 8)
-Production of cyan ink-
A cyan ink of Comparative Example 8 was produced in the same manner as in Example 4 except that the cyan ink of Example 4 was changed to 23% by mass of glycerin as a wetting agent and 5% by mass of 1,3-butanediol. did.

Next, when the above evaluation (1) was performed for each of the cyan inks of Example 4 and Comparative Examples 7 to 8, the cyan ink of Comparative Example 7 was considerably more than 20 hours in that the rate of change in specific viscosity exceeded 100. In contrast, the cyan ink of Comparative Example 8 had a viscosity increase rate exceeding 100 after 40 hours. The ink of Comparative Example 7 had an initial viscosity of 8.3 mPa · s at 25 ° C., and the ink of Comparative Example 8 had an initial viscosity of 6.9 mPa · s at 25 ° C.
Further, with respect to these cyan inks, evaluation of character bleeding in the above evaluation (2) and evaluation of continuous printability in the following evaluation (3) were performed. The results are shown in Table 3.
<Evaluation (3): Evaluation of continuous printability>
Using the printer used in the evaluation (2), 30 single-color solid charts were continuously printed, and the number of printed sheets when an ejection failure occurred was counted. Note that if no ejection failure occurred even after printing 50 sheets, the number of sheets was set to 50 or more.

From the results of Table 3, it was confirmed that the ink of Comparative Example 7 was inferior in continuous ejection stability as compared with the ink of Example 4. Further, the ink of Comparative Example 8 was slightly worse in character bleeding and the continuous ejection stability was slightly inferior to the ink of Example 4.

(Example 8)
-Preparation of yellow ink-
A yellow ink of Example 8 was produced in the same manner as in Example 2 except that 0.5% by mass of 2-amino-2-ethyl-1,3-propanediol was further added to the yellow ink of Example 2. did.

Example 9
-Production of cyan ink-
A cyan ink of Example 9 was produced in the same manner as in Example 4 except that 0.5 mass% of 2-amino-2-ethyl-1,3-propanediol was further added to the cyan ink of Example 4. did.

<Evaluation>
Next, when each of the inks of Examples 8 to 9 was evaluated (1), the specific viscosity change rate exceeded 100 during 20 to 40 hours. The initial viscosity of the ink of Example 8 was 8.3 mPa · s at 25 ° C., and the initial viscosity of the ink of Example 9 was 8.5 mPa · s at 25 ° C.
Further, for each ink of Example 2, Example 4, Example 8, and Example 9, the evaluation of character bleeding in the evaluation (2) and the continuous printability evaluation in the evaluation (3) were performed. The results are shown in Table 4.

From the results in Table 4, the inks of Examples 8 and 9 gave good results at the same level as the inks of Examples 2 and 4 to which 2-amino-2-ethyl-1,3-propanediol was not added. It was.

(Example 10)
-Preparation of black ink-
The black ink of Example 10 was the same as Example 1 except that 3-methyl-1,3-butanediol as a wetting agent was changed to 1,3-butanediol in the black ink of Example 1. Was made.
When the above evaluation (1) was performed on the ink of Example 10 obtained, the rate of change in specific viscosity exceeded 100 during 20 to 40 hours, which was later than Example 1. . The initial viscosity of the ink of Example 10 was 7.6 mPa · s at 25 ° C.

(Example 11)
-Production of cyan ink-
In the cyan ink of Example 4, the cyan ink of Example 11 was changed in the same manner as in Example 4 except that 1,3-butanediol as a wetting agent was changed to 3-methyl-1,3-butanediol. Was made.
The ink of Example 11 obtained was subjected to the above evaluation (1). As a result, the rate of change in specific viscosity exceeded 100 during 20 to 40 hours, which was later than Example 4. . The initial viscosity of the ink of Example 11 was 8.6 mPa · s at 25 ° C.

  Next, each ink of Example 1, Example 4, Example 10, and Example 11 was evaluated (4) as follows. The results are shown in Table 5.

<Evaluation (4): Ejection sequence evaluation>
As an evaluation machine, an ink jet printer (Ricoh Co., Ltd., IPSiO G707, nozzle diameter: 26 μm) was used, and a chart with the same amount and timing of ink to be ejected for each color was continuously printed. At that time, the ejection bend after printing 500 sheets continuously was evaluated by changing the interval (seconds) for idle ejection in the non-printing area and the number of idle ejection droplets. The printing environment was 30% RH at 15 ° C and 65% RH at 25 ° C.
About the jet bending after continuous printing, the enlarged photograph was taken about what printed 20 drops of all the nozzles on the glossy film for inkjets, and it judged visually and evaluated by the following reference | standard.
〔Evaluation criteria〕
A: There is no disturbance in the ejection direction, the dot size is normal, and the dots are aligned in a row. ○: There is no disturbance in the ejection direction, and the dots are arranged in a row, but the dot size is slightly small. However, the disturbance does not reach the second row. ×: The first dot exceeds the line of the second dot. XX: The second droplet is not ejected.

From the results shown in Table 5, a high-quality image can be printed without reducing the printing speed by optimizing the discharge interval and the number of ink droplets according to the printing environment temperature and humidity and the specific viscosity change rate of the ink. Was found to be possible.

(Comparative Example 9)
-Preparation of black ink-
A black ink of Comparative Example 9 was produced in the same manner as in Example 1, except that the acrylic silicone resin emulsion was omitted.

(Example 12)
-Preparation of black ink-
A black ink of Example 12 was produced in the same manner as in Example 1 except that the acrylic silicone resin emulsion was changed to a polyester resin emulsion (Pesresin A210, manufactured by Takamatsu Yushi Co., Ltd.).

Next, when the above evaluation (1) was performed on the inks of Comparative Example 9 and Example 12, both had a specific viscosity change rate exceeding 100 during 20 to 40 hours. The initial viscosity of the ink was 7.6 mPa · s at 25 ° C., and the initial viscosity of the ink of Example 12 was 8.4 mPa · s at 25 ° C.
In addition, the inks of Example 1, Comparative Example 9, and Example 12 were evaluated (5) and fixed as follows. The results are shown in Table 6.
<Evaluation (5): Fixability evaluation>
Using the printer used in the evaluation (2), printing was performed on Type 6200 paper (manufactured by NBS Ricoh Co., Ltd.) at a resolution of 600 dpi. After drying at room temperature for 1 day, the printed part was rubbed 10 times with a cotton cloth at a constant pressure, and the amount of ink transferred to the cotton cloth was visually observed and evaluated according to the following criteria.
〔Evaluation criteria〕
○: Almost no transfer of ink onto cotton cloth Δ: Some transfer of ink onto cotton cloth is observed ×: Obviously a considerable amount of ink is transferred onto the cotton cloth

From the results in Table 6, it was found that the fixability was improved by adding a resin emulsion. From the results of Example 1 and Example 12, it is recognized that the fixability is further improved by using the acrylic silicone resin emulsion.

The recording ink of the present invention is suitable for ink cartridges, ink jet recording apparatuses, and ink jet recording methods because it is excellent in image quality and high-speed printing on plain paper and has good storage stability and ejection stability. Can do.
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 configuration diagram illustrating the overall configuration of the ink jet recording apparatus. FIG. 5 is a schematic enlarged view showing an example of the inkjet head of the present invention. FIG. 6 is an element schematic enlarged view showing another example of the ink jet head of the present invention. FIG. 7 is an enlarged schematic cross-sectional view of a main part of the inkjet head of FIG. FIG. 8 is a graph showing the relationship between the evaporation time and the specific viscosity change rate in each of the inks of Examples 1 to 4 and Comparative Examples 1 to 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Frame 20 Flow path plate 30 Nozzle plate 40 Base 50 Laminated piezoelectric element 60 Vibrating plate 70 Adhesive layer 101 Apparatus 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 Subtank 141 Paper Placement Unit 142 Paper 144 Separation Pad 151 Conveying Belt 152 Again 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 Feed Unit 201 Ink cartridge 241 Ink bag 242 Ink inlet 243 Ink outlet 244 Cartridge exterior

Claims (16)

A recording ink containing at least water, a colorant, a wetting agent, and a resin emulsion,
The recording ink has a specific viscosity change rate represented by the following mathematical formula 1 of 100 or less at less than 20 hours and more than 100 at 20 to 40 hours, and the initial viscosity of the recording ink. Is 6.0 mPa · s or more.
<Formula 1>
Specific viscosity change rate = {[(η ₁ −η ₀ ) / η ₀ ] × 100} / T
In Equation 1, η ₀ represents the initial viscosity (mPa · s) of the recording ink before performing the evaporation test in an environment of 25 ° C. and 50% RH. η ₁ represents the viscosity (mPa · s) after the elapse of T time when the evaporation test is performed. T represents the elapsed time in the evaporation test.   2. The recording according to claim 1, wherein the water content in the recording ink is 35% by mass or more, and the total content of the colorant and the resin emulsion in the recording ink is 10 to 30% by mass in solid content. For ink.   The recording ink according to claim 1, wherein the resin emulsion is an acrylic silicone emulsion.   The wetting agent contains at least one polyhydric alcohol, and at least one polyhydric alcohol has an equilibrium water content of 25% by mass or more in an environment of a temperature of 20 ° C. and 60% RH. 4. The recording ink according to any one of items 1 to 3.   The recording ink according to claim 4, wherein one of the polyhydric alcohols is glycerin, and the content of the glycerin is 20 to 80% by mass of the whole wetting agent.   The recording ink according to claim 1, further comprising a surfactant and a penetrating agent.   The recording ink according to claim 6, wherein the surfactant is at least one selected from a silicone-based surfactant and a fluorine-based surfactant.   An ink cartridge comprising the recording ink according to claim 1 contained in a container.   8. 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 ink jet recording apparatus according to claim 9, wherein the ink flying means has a nozzle having a nozzle diameter of 35 μm or less and a printing speed is 8 ppm or more. The ink discharge means for recording inside the nozzle hole before the specific viscosity change rate expressed by the following formula 1 exceeds 100 in the recording ink in the vicinity of the nozzle during printing. The ink jet recording apparatus according to claim 9, wherein the ink is discharged.
<Formula 1>
Specific viscosity change rate = {[(η ₁ −η ₀ ) / η ₀ ] × 100} / T
In Equation 1, η ₀ represents the initial viscosity (mPa · s) of the recording ink before performing the evaporation test in an environment of 25 ° C. and 50% RH. η ₁ represents the viscosity (mPa · s) after the elapse of T time when the evaporation test is performed. T represents the elapsed time in the evaporation test.   The ink jet recording apparatus according to claim 11, wherein the ink discharging means is means for discharging recording ink to a non-printing area.   The ink jet recording apparatus according to any one of claims 11 to 12, wherein the amount of recording ink discharged from the ink discharging means is 2,000 to 30,000 pl per minute per nozzle.   14. The ink jet recording apparatus according to claim 11, wherein the recording ink amount discharged from the ink discharging means is variable depending on the value of the temperature / humidity sensor.   The ink jet recording apparatus according to any one of claims 11 to 13, wherein the amount of recording ink discharged from the ink discharging means is variable depending on a rate of change in specific viscosity of the recording ink. 8. 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.