JP2005205684A - Inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To lengthen the life of a heater in an inkjet recording method using a recording head capable of doing high-image-quality and high-speed printing. <P>SOLUTION: In this inkjet recording method, thermal energy is directly imparted to ink from a heater 34 by means of the recording head whose resolution is 1,600 dpi or more, wherein the number of nozzles is 1,600 or more and which is equipped with the heater 34 (heating resistor layer) composed of a Ta layer; and the ink is ejected from the nozzle so that an image can be recorded on a recording medium. In the used ink, water, a water-soluble organic solvent and a coloring material are contained, and a dynamic contact angle after 0.1 s with respect to the Ta layer as the heating resistor layer is in the range of 20-40°. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ink jet recording method applied to an ink jet printer using thermal energy.

  An ink jet method using thermal energy is capable of high-speed, high-density, high-definition and high-quality recording, and is suitable for colorization and compactness. In such an ink jet method, thermal energy is applied to the ink. There is a thermal method for recording an image on a recording medium.

  In such a thermal system, extending the life of the recording head is an important issue, and various proposals have been made.

  For example, JP-A-5-320550 discloses adding ammonium halide or ammonium sulfonate to the ink in an amount up to 0.2% by weight. Further, in Japanese Patent Laid-Open No. 7-102389, metal non-corrosiveness characterized by containing 0.1 wt% to 1.0 wt% of sulfate and / or 0.1 wt% to 1.0 wt of hydroxide. A liquid composition is disclosed. Japanese Patent Application Laid-Open No. 7-268665 discloses a liquid containing a phosphate in the range of 0.01 wt% to 1.0 wt% and a citrate in the range of 0.001 wt% to 1.0 wt%. .

Each of these proposals aims to extend the life of the recording head and improves the kogation / etching / metal corrosion of the heater with an additive in the ink.
JP-A-5-320550 JP-A-7-102389 JP-A-7-268665

  By the way, in the inkjet recording method, in order to enable high image quality and high-speed printing, it is required that the recording head be provided with a large number of nozzles with high resolution. For this reason, since it is necessary to arrange the heaters at a high density, it is necessary to make the heaters smaller than in the conventional case. If a conventional heater protective film is used, the thermal efficiency is lowered accordingly. Therefore, in order to increase the thermal conductivity, a heater composed of Ta without a protective film in the heat generating region is desirable.

  Further, the ink requires high color development with a smaller drop, and requires a high colorant density. Therefore, when a part of the color material is decomposed at the time of discharge, the heater is in a situation where higher cavitation is applied.

  As described above, in a system capable of high-quality printing and high-speed printing, the current situation is that the environment is severe with respect to the heater life, and improvement is desired.

  Accordingly, an object of the present invention is to extend the life of a heater in an inkjet recording method using a recording head capable of high image quality and high-speed printing.

The above problem is solved by the following means. That is,
The inkjet recording method of the present invention uses a recording head having a resolution of 1600 dpi or more, the number of nozzles of 1600 or more, and a heating resistor layer composed of a Ta layer. A method of recording an image on a recording medium by applying thermal energy and ejecting the ink from the nozzle;
The ink contains water, a water-soluble organic solvent, and a coloring material, and a dynamic contact angle after 0.1 s with respect to the Ta layer as the heating resistor layer is 20 to 40 degrees. Yes.

  In the ink jet recording method of the present invention, when a recording head provided with a heating resistor layer (heater) made of Ta that is high-definition long and has no protective film so as to enable high-quality and high-speed printing, By setting the ink wettability to Ta, which is the heating resistor layer material, to an appropriate range, the force caused by cavitation is not concentrated locally on the heating resistor layer, and the heating resistor layer is destroyed. Is prevented.

  In the inkjet recording method of the present invention, the content of the color material is preferably 5 wt% or more.

  In the ink jet recording method of the present invention, the colorant preferably has a decomposition temperature of less than 400 ° C. and a weight reduction rate of 8% or more due to thermal decomposition in a range of 300 ° C. to 400 ° C.

  According to the ink jet recording method of the present invention, the heater life can be further extended by using a recording head capable of high image quality and high speed printing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, what has the substantially same function is attached | subjected and demonstrated through the whole figure, and the description may be abbreviate | omitted depending on the case.

  FIG. 1 is an ink jet recording apparatus applied to an ink jet recording method according to an embodiment of the present invention. 2A and 2B are configuration diagrams showing an inkjet recording head applied to the inkjet recording method according to the embodiment of the present invention, in which FIG. 2A is a plan view and FIG. 2B is a cross-sectional view taken along line bb ′ of FIG. is there.

  As shown in FIG. 1, the ink jet recording apparatus 10 according to this embodiment includes a carriage 14 on which an ink jet recording head 12 is mounted. The carriage 14 moves in the main scanning direction (arrow M direction) along the shaft 16 provided in the inkjet recording apparatus 10.

  Further, the inkjet recording apparatus 10 is provided with a conveyance roller 20 for conveying the recording paper 18 (recording medium). The recording paper 18 is nipped and conveyed by the conveyance roller 20 and moves in the sub-scanning direction (arrow S direction).

  The ink jet recording head 12 is provided with an ink tank 22, and constitutes an ink jet cartridge 24 as a consumable item that can be attached to and detached from the ink jet recording apparatus main body by a user. The ink jet cartridge 24 has a structure including the ink jet recording head 12, an ink tank 22, and an ink supply path (not shown) that connects the two.

  An ink absorber may be built in the ink tank 22. Alternatively, only the ink jet recording head may be mounted on the carriage 14, the ink tank 22 may be disposed outside the carriage of the ink jet recording apparatus main body, and both may be connected by an ink supply path. The side of the ink tank 22 facing the recording paper 18 (the lower side in FIG. 1) is the ink jet recording head 12.

  1, the longitudinal direction of the inkjet recording head 12 coincides with the sub-operation direction, and the short side direction thereof coincides with the main scanning direction. Therefore, the longitudinal direction of the inkjet recording head 12 in FIG. The short direction is indicated by an arrow M.

  Next, the ink jet recording head 12 will be described. As shown in FIG. 2, the inkjet recording head 12 according to the present embodiment has a heater 34 (heating resistor layer), an electrode layer 36 (metal wiring), and a heat storage layer 32 formed on the substrate 30. An electrode protective layer 38 is sequentially formed.

  The heater 34 is composed of a Ta layer. The electrode layer 36 is formed as an upper layer of the heater 34 and is formed so as to be in contact with the upper surfaces of both ends of the heater 34. The electrode protection layer 38 is configured to cover the electrode layer 36, and the heater 34 is exposed in the heat generation region. In this way, the heat generation area of the heater 34 is exposed to improve energy efficiency, and high-speed printing is possible.

  On the heater 34, an ink flow path forming body 44 provided with an ink flow path 40 and an ink discharge port 42 (nozzle) is formed. The outer wall of the ink flow path 40 is constituted by a part of the ink flow path forming body 44 and the electrode protection layer 38.

  A plurality of heaters 34 and ink discharge ports 42 formed on the substrate 30 are formed at both ends of the openings along the longitudinal direction of the ink supply ports 46 opened in the substrate 30, and in each row. A so-called staggered arrangement is adopted in which the positions of the heaters 34 and the ink discharge ports 42 are shifted by half and arranged so as to be equally spaced when viewed as a whole along the longitudinal direction. As a result, the recording resolution at the recording head is twice the resolution per column. In the present embodiment, the number of nozzles (ink discharge ports 42) is 1600 or more by providing 800 or more per row and forming two rows. That is, the resolution per column is set to 800 dpi or more, and when this becomes two columns, the resolution becomes 1600 dpi or more. Thus, in this embodiment, it is configured as a high-definition long recording head.

  As described above, the ink jet recording apparatus according to this embodiment includes a recording head capable of high image quality and high speed printing. The ink applied to such an ink jet recording apparatus will be described in detail below. In the following description, reference numerals are omitted.

  As the ink, one having a dynamic contact angle of 20 to 40 degrees after 0.1 s with respect to the Ta layer as the heating resistor layer (heater) is used. Thus, the wettability of the ink to Ta, which is the constituent material of the heating resistor layer, is set to an appropriate range, and the force caused by cavitation is suppressed from being concentrated locally on the heating resistor layer, thereby generating the heating resistor. Prevents damage to the layer over a long period of time and improves heater life.

  The dynamic contact angle is 20 to 40 degrees, preferably 22 to 38 degrees, and more preferably 25 to 35 degrees. When the dynamic contact angle is less than 20 degrees, when cavitation occurs, the force resulting from cavitation is concentrated locally on the heating resistor layer, and the heating resistor layer is easily broken. On the other hand, if the dynamic contact angle exceeds 40 degrees, when the bubble is generated, the ink wetting area with respect to the heating resistor layer is small. Since the force per area is larger than when it is small, the heat generating resistor layer becomes more distorted and easily damaged.

  Here, the dynamic contact angle is a contact angle after a predetermined time has elapsed since the ink was dropped on the Ta layer (after 0.1 s in the present invention), that is, the ink at the liquid contact portion between the ink droplet and the Ta layer. This is the angle between the drop surface and the Ta layer. The dynamic contact angle is, for example, the dynamic contact angle after a predetermined time (after 0.1 s in the present invention) after dropping 4 μl of ink on the Ta layer under the conditions of 23 ° C. and 55% RH. It is determined by measuring using a contact angle meter FIBRO1100DAT.

  The dynamic contact angle can be adjusted, for example, as follows. Adjust the amount of surfactants of the appropriate type and / or low gamma solvent such as glycol monoalkyl ether in the ink according to the other ink materials (for example, coloring materials, humectants, other additives). To do. Preferred examples of the surfactant include polyoxyethylene alkyl ether, polyethylene glycol polypropylene glycol block copolymer, acetylene glycol, polyoxyethylene adduct of acetylene glycol, polyoxyethylene / polyoxypropylene adduct of acetylene glycol, and the like. Low γ solvents include ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, diethylene glycol monohexyl ether, dipropylene glycol monobutyl ether, triethylene glycol monohexyl ether, diethylene glycol monocyclohexyl ether, triethylene glycol monobutyl ether. Etc. These may be used alone or in combination.

  The dynamic contact angle on Ta of the ink added with these changes somewhat depending on the type of ink vehicle material such as colorant / humectant / additive, even if the same surfactant and low γ solvent are used. So, if you want to adjust the dynamic contact angle in the direction of decreasing the dynamic contact angle according to the type of vehicle material, increase the addition amount of surfactant and / or low γ solvent and adjust the dynamic contact angle in the direction you want to increase In some cases, the amount of the surfactant and / or the low γ solvent added can be reduced. Thus, although the addition amount of the surfactant and / or the low γ solvent needs to be finely adjusted depending on the type of the vehicle material, in the case of the surfactant, about 0.3 wt. % In the range of about 4-15 wt. % Range is preferred.

  On the other hand, the ink composition includes water, a water-soluble organic solvent, and a coloring material as essential components. Further, the ink may contain an aggregating agent, a dispersing agent, a penetrating agent, urea and / or a urea derivative, a pH adjusting agent, and other additives as necessary. Hereinafter, each ink composition will be described.

-Color material-
Examples of the color material include pigments and dyes. As the color material, both dyes and pigments can be used, but dyes that are easy to obtain color images excellent in color development are preferably used.

  Examples of the pigment include carbon black and a color pigment.

  As carbon black, carbon black pigments such as furnace black, lamp black, acetylene black and channel black are preferable. Raven 1080 ULTRA, Raven 1060 ULTRA, Raven 790 ULTRA, Raven 780 ULTRA, Raven 760 ULTRA (manufactured by Columbian Carbon Co., Ltd.), Regal 400R, Regal 330R, Rega 660R, Mogul L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400 (manufactured by Cabot Corporation), Color Black FW1, Color Bla FW1, Color Bla , Color Black FW200, Color Black S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Printex 140V, SpecialBck No. 5, Special Black 4A, Special Black 4 (manufactured by Degussa), No. 5 25, no. 33, no. 40, no. 47, no. 52, no. 900, no. 2300, MCF-88, MA600, MA7, MA8, MA100 (manufactured by Mitsubishi Chemical Corporation) and the like can be used. In addition, a carbon black pigment newly synthesized for the present invention may be used.

  For these carbon black pigments, magnetic fine particles such as magnetite and ferrite, titanium black and the like may be used in combination. Cyan, magenta, and yellow primary color pigments, specific color pigments such as red, green, blue, brown, and white, metallic luster pigments such as gold and silver, colorless extender pigments, plastic pigments, and the like may be used in combination.

  Carbon black may be a self-dispersing pigment. The self-dispersing pigment refers to a pigment that can be dispersed in a solvent by itself without containing a so-called dispersant such as a surfactant or a polymer dispersant. Generally, a self-dispersing pigment has a hydrophilic functional group on the surface.

  Here, whether or not the carbon black (pigment) is “self-dispersing” is confirmed by the following self-dispersing test.

  Self-dispersibility test: Add pigment to be measured in water and disperse without dispersing agent using ultrasonic homogenizer, nanomizer, microfluidizer, ball mill, etc., so that the initial pigment concentration is about 5% Dilute with water to prepare a dispersion. The initial pigment concentration and 100 g of the dispersion are placed in a 40 mm diameter glass bottle and allowed to stand for 1 day, and then the pigment concentration in the upper layer portion is measured. When the ratio of the pigment concentration after standing for 1 day with respect to the initial pigment concentration (hereinafter referred to as “self-dispersing index”) is 98% or more, it is evaluated as “self-dispersing”.

  At this time, the measuring method of the carbon black (pigment) concentration is not particularly limited, and any method such as a method of measuring the solid content by drying the sample or a method of obtaining the transmittance by diluting to an appropriate concentration may be used. If there is a method for accurately obtaining the pigment concentration, it is of course possible to use that method.

  As a method for introducing a hydrophilic functional group into carbon black (pigment), a known method or any newly invented method can be used. For example, oxidation treatment with an oxidizing agent (eg nitric acid, permanganate, dichromate, hypochlorite, ammonium persulfate, hydrogen peroxide, ozone, ozone water, etc.), sulfonating agent treatment, silane compound, etc. In addition to known methods such as treatment with a coupling agent, polymer grafting treatment, plasma treatment, treatment with a diazonium salt compound having a hydrophilic group, newly developed methods can be used, and these methods can be combined. Good. The amount of the hydrophilic functional group can be adjusted by controlling the treatment concentration and time, and the surface functional group of a commercially available self-dispersing pigment can be adjusted by modification such as esterification.

  Examples of commercially available self-dispersing pigments that can be suitably used as carbon black (pigment) include MICROJET (BONJET) BLACK CW-1 (manufactured by Orient Chemical Co., Ltd.), BONJET BLACK CW-2 (manufactured by Orient Chemical Industries, Ltd.), and BONJET. Examples include BLACK CW-3 (manufactured by Orient Chemical Co., Ltd.), CAB-O-JET200 (manufactured by Cabot Corporation), CAB-O-JET300 (manufactured by Cabot Corporation), IJX-157 (manufactured by Cabot Corporation), and the like. All of these commercially available self-dispersing pigments have a self-dispersing index of 100%.

The following are mentioned as a color pigment.
Examples of cyan pigments include C.I. I. Pigment Blue 1, C.I. I. Pigment Blue 2, C.I. I. Pigment Blue 3, C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 15: 4, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 22, C.I. I. Pigment Blue 60 and the like, but are not limited thereto.

  Examples of magenta pigments include C.I. I. Pigment Red 5, C.I. I. Pigment Red 7, C.I. I. Pigment Red 12, C.I. I. Pigment Red 48, C.I. I. Pigment Red 48: 1, C.I. I. Pigment Red 57, C.I. I. Pigment Red 112, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 146, C.I. I. Pigment Red 168, C.I. I. Pigment Red 184, C.I. I. Pigment Red 202, C.I. I. Pigment Violet 1960 and the like, but are not limited thereto.

  Examples of yellow pigments include C.I. I. Pigment Yellow 1, C.I. I. Pigment Yellow 2, C.I. I. Pigment Yellow 3, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 16, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 55, C.I. I. Pigment Yellow 73, C.I. I. Pigment Yellow 74, C.I. I. Pigment Yellow 75, C.I. I. Pigment Yellow 83, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 95, C.I. I. Pigment Yellow 97, C.I. I. Pigment Yellow 98, C.I. I. Pigment Yellow 114, C.I. I. Pigment Yellow 128, C.I. I. Pigment Yellow 129, C.I. I. Pigment Yellow 150, C.I. I. Pigment Yellow 151, C.I. I. Pigment Yellow 154, C.I. I. Pigment Yellow 180, C.I. I. Pigment Yellow 185 and the like, but are not limited thereto.

  In addition to the three primary color pigments of cyan, magenta and yellow, specific color pigments such as red, green, blue, brown and white, metallic luster pigments such as gold and silver, colorless extender pigments, plastic pigments, etc. Good. In addition, a pigment newly synthesized for the present invention may be used.

  Self-dispersing pigments having hydrophilic functional groups introduced on the surface of these pigments can also be used and are preferred in the present invention. As a method for introducing a hydrophilic functional group, a known method or any newly invented method can be used. For example, oxidation treatment with an oxidizing agent (eg nitric acid, permanganate, dichromate, hypochlorite, ammonium persulfate, hydrogen peroxide, ozone, ozone water, etc.), sulfonating agent treatment, silane compound, etc. In addition to known methods such as treatment with a coupling agent, polymer grafting treatment, plasma treatment, treatment with a diazonium salt compound having a hydrophilic group, newly developed methods can be used, and these methods can be combined. Good. The amount of the hydrophilic functional group can be adjusted by controlling the treatment concentration, time and the like, and the surface functional group of a commercially available self-dispersing pigment can also be adjusted by modification such as esterification. The meaning of the term “self-dispersing type” is as described in the section of carbon black.

  The dye is not particularly limited but is preferably a water-soluble dye. The water-soluble dye may be any of an acid dye, a direct dye, a basic dye, a reactive dye, and the like, more preferably an acid dye and a direct dye.

Examples of the dye include the following.
For example, C.I. I. Direct Blue-1, -2, -6, -8, -15, -22, -25, -34, -41, -70, -71, -76, -77, -78, -80, -86, -87, -90, -98, -106, -108, -112, -120, -142, -158, -163, -165, -168, -199, -200, -201, -202, -203 , -207, -218, -236, -287, -307,
C. I. Direct Red-1, -2, -4, -8, -9, -11, -13, -15, -20, -23, -24, -28, 31, -33, -37, -39, -46, -51, -59, -62, -63, -73, -75, -79, -80, -81, -83, -87, -89, -90, -94, -95, -99 , -101, -110, -189, -197, -201, -218, -220, -224, -225, -226, -227, -228, -229, -230,
C. I. Direct violet-107,
C. I. Direct yellow-1, -2, -4, -8, -11, -12, -26, -27, -28, 333, -34, -39, -41, -44, -48, -50, -58, -85, -86, -87, -88, -89, -98, -100, -110, -132, -135, -142, -144, -173,
C. I. Acid Blue-1, −7, −9, −15, −22, −23, −25, −27, −29, −40, −43, −55, −59, −62, −74, −78, −80, −81, −83, −90, −100, −102, −104, −111, −117, −127, −138, −158, −161, −185, −249, −254,
C. I. Acid Red-1, -4, -6, -8, -9, -13, -14, -15, -18-21, -26, -27, -32, -35, -37, -42,- 51, -52, -80, -83, -87, -89, -92, -106, -110, -114, -115, -133, -134, -144. −145, −158, −180, −198, −249, −257, −265, −289,
C. I. Acid Yellow-1, -3, -4, -7, -11, -12, -13, -14, -17, -18, -19, -23, -25, -29, 34, -36 −38, −40, −41, −42, −44, −53, −55, −61, −71, −76, −78, −79, −98, −99, −122,
C. I. Reactive Blue-4, -5, -7, -13, -14, -15, -18, -19, -21, -26, -27, -29, -32, -38, -40, -44 , -100,
C. I. Reactive Red-7, -12, -13, -15, -17, -20, -23, -24, -29, 31, -42, -445, -46, -59,
C. I. Food Red -87, -92, -94,
M-377 manufactured by ILFORD,
C. I. Reactive Yellow-2, -3, -17, -25, -37, -42,
C. I. Food yellow-3,
Y-104, Y-1189 manufactured by ILFORD,
C. I. Direct Black-2, -4, -9, -11, -17, -19, -22, -32, -80, -151, -154, -168, -171, -194, -195 C.I. I. Food Black-1, -2, C.I. I. Acid Black-1, -2, -7, -16, -24, -26, -28, -31, -48, -52, -63, -107, -112, -118, -119, -121, -156, -172, -194, -208,
Etc.

  The color materials listed above can be used alone, but two or more color materials may be mixed, or may be adjusted to custom colors such as red, blue, and green in addition to the three primary colors of cyan, magenta, and yellow.

  The color material preferably has a decomposition temperature of less than 400 ° C. and a weight reduction rate of 8% or more due to thermal decomposition in the range of 300 ° C. to 400 ° C., more preferably 8.5 to 25%. Preferably it is 9 to 20%. When an ink containing a colorant having a weight reduction rate in the above range is used, it is easily decomposed when heat energy is applied from the heating resistor layer, and the force caused by cavitation is concentrated locally on the heating resistor layer. However, by setting the ink dynamic contact angle in the above range, even if the color material is decomposed, local concentration of cavitation on the heating resistor layer can be suppressed, and the heater life is improved.

  Preferred examples of the color material having a weight reduction rate within the above range include the following. For example, C.I. I. Acid Blue-9 (weight loss rate: 17.5%), C.I. I. Acid Yellow-23 (weight reduction rate: 13.6%), C.I. I. Acid Red-52 (weight reduction rate: 15.4%), C.I. I. Direct Yellow-132 (weight reduction rate: 9.6%), C.I. I. Direct Yellow-144 (weight reduction rate: 9.8%), C.I. I. Direct Black-19 (weight reduction rate: 16.3%), C.I. I. Direct Black-154 (weight reduction rate: 12.4%), C.I. I. Direct black-168 (weight reduction rate: 11.5%) and the like.

  Here, the weight reduction rate is obtained as follows. The dried color material is subjected to thermogravimetric analysis (TG) measurement, heated from the initial temperature (15-35 ° C.) to 400 ° C. or higher, and from the weight at the time of 300 ° C. to 400 ° C. relative to the color material weight at the initial temperature. It is determined by the percentage of the difference minus the current weight.

  The content of the color material is preferably 5 wt% or more, more preferably 5 to 10 wt%, and further preferably 5 to 8 wt%. By blending a colorant with a concentration in the above range in a good ink, it is possible to achieve high-density image quality even with a small amount of droplets, but it decomposes when heat energy is applied from the heating resistor layer as described above. The amount to do will increase. However, by setting the dynamic contact angle of the ink within the above range, even if the amount of decomposition of the color material increases, local concentration of cavitation on the heating resistor layer can be suppressed, and the heater life is improved.

  It is desirable that the colorant be purified by removing impurities mixed in the manufacturing process, for example, residual oxidant, impurities such as treatment agents and by-products, other inorganic impurities and organic impurities. In particular, it is desirable that calcium, iron, and silicon in the ink be 10 ppm or less, preferably 5 ppm or less, respectively. The content of these inorganic impurities can be measured by, for example, a high frequency inductively coupled plasma atomic emission spectrometry.

  These removals can be carried out, for example, by water washing, reverse osmosis membrane, ultrafiltration membrane, ion exchange method, adsorption method using activated carbon, zeolite or the like alone or in combination.

  When a pigment is used as the color material, a dispersant can be used to disperse the pigment.

-Water-soluble organic solvent-
Water-soluble organic solvents include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, triethylene glycol, 1,5-pentanediol, 1,2,6-hexanetriol, trimethylolpropane, glycerin, polyethylene glycol Polyhydric alcohols such as ethanol, isopropyl alcohol, lower alcohols such as 1-propanol, nitrogen-containing solvents such as pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, triethanolamine, or thiodiethanol, thiodi Sulfur-containing solvents such as glycerol, sulfolane and dimethyl sulfoxide, and sugars such as propylene carbonate, ethylene carbonate, glucose, fructose, galactose, mannose, and xylose Beauty derivatives thereof or sugar alcohols or the like can be used.

  These water-soluble organic solvents may be used alone or in combination of two or more. The water-soluble organic solvent is used in an amount of 1 to 60% by weight, preferably 5 to 40% by weight of the ink.

-Water-
It is preferable to use ion-exchanged water, ultrapure water, distilled water, or ultrafiltered water in order to prevent impurities from being mixed.

-Flocculant-
As the flocculant, a polyvalent metal salt is preferable from the viewpoint of the stability of the color ink.

  A polyvalent metal salt is a salt that generates a bivalent or higher cation derived from a metal element when dissolved in water. Examples of the polyvalent metal ion include aluminum ions, barium ions, calcium ions, copper ions, iron ions, Multivalent metal ions such as magnesium ion, manganese ion, nickel ion, tin ion, titanium ion and zinc ion can be mentioned.

  Specific examples of the polyvalent metal salt include the above polyvalent metal ions, hydrochloric acid, odorous acid, hydroiodic acid, sulfuric acid, nitric acid, phosphoric acid, thiocyanic acid, and acetic acid, oxalic acid, lactic acid, fumaric acid, and phthalic acid. It is used in the form of salts with organic carboxylic acids such as citric acid, salicylic acid, benzoic acid, and organic sulfonic acids.

  More specifically, for example, aluminum chloride, aluminum bromide, aluminum sulfate, aluminum nitrate, sodium aluminum sulfate, potassium aluminum sulfate, aluminum acetate, barium chloride, barium bromide, barium iodide, barium oxide, barium nitrate, thioan Barium acid, calcium chloride, calcium bromide, calcium iodide, calcium nitrite, calcium nitrate, calcium dihydrogen phosphate, calcium thiocyanate, calcium benzoate, calcium acetate, calcium salicylate, calcium tartrate, calcium lactate, calcium fumarate , Calcium citrate, copper chloride, copper bromide, copper sulfate, copper nitrate, copper acetate, iron chloride, iron bromide, iron iodide, iron sulfate, iron nitrate, iron oxalate, iron lactate, iron fumarate, citric acid Iron, magnesium chloride, odor Magnesium, magnesium iodide, magnesium sulfate, magnesium nitrate, magnesium acetate, magnesium lactate, manganese chloride, manganese sulfate, manganese nitrate, manganese dihydrogen phosphate, manganese acetate, manganese salicylate, manganese benzoate, manganese lactate, nickel chloride, odor Examples thereof include nickel fluoride, nickel sulfate, nickel nitrate, nickel acetate, tin sulfate, titanium chloride, zinc chloride, zinc bromide, zinc sulfate, zinc nitrate, zinc thiocyanate, and zinc acetate.

  The polyvalent metal salt is preferably aluminum sulfate, calcium chloride, calcium nitrate, calcium acetate, magnesium chloride, magnesium nitrate, magnesium sulfate, magnesium acetate, tin sulfate, zinc chloride, zinc nitrate, zinc sulfate, zinc acetate, nitric acid. Aluminum or the like is used.

  As the flocculant, in addition to the above polyvalent metal salt, a monovalent electrolyte, a hydrophobic nonionic surfactant, an anionic surfactant, a hydrophobic water-soluble solvent, etc. are sufficient to inhibit the dispersion of carbon black. Adding more than the amount is also effective and can be used. Examples of the monovalent electrolyte include inorganic salts such as sodium chloride, sodium sulfate, sodium sulfite, and sodium nitrate, and salts of organic acids such as acetic acid, lactic acid, benzoic acid, and citric acid with alkaline substances. Examples of the surfactant having high hydrophobicity include surfactants having an HLB of 10 or less, preferably 5 or less. Examples of the hydrophobic water-soluble solvent include those having an SP value of 12 or less, preferably 10 or less.

In particular, as the aggregating agent, when the black ink pigment (this dispersing agent or a functional group for self-dispersing) or the water-soluble polymer contained in the black ink is cationic, inorganic and bivalent anions are generated. Organic salts, polymers having an anionic group, and the like can also be used. Examples of inorganic and organic salts that generate divalent or higher anions include sulfuric acid, sulfurous acid, phosphoric acid, phosphonic acid, etc., organic carboxylic acids such as oxalic acid, fumaric acid, phthalic acid, citric acid, tartaric acid, and organic sulfonic acid, etc. And a compound containing a salt thereof.
In addition, the above-described electrolytes described when the black ink pigment (this dispersant or functional group for self-dispersing) or the water-soluble polymer contained in the black ink is anionic can also be used.

-Dispersant-
As the dispersant, a surfactant or a water-soluble resin can be used, and it is preferable to use a water-soluble resin for dispersion.

  As a water-soluble resin used as a dispersant, a known water-soluble resin such as a polymer obtained by a polymerization reaction or a naturally-derived resin can be used, and a (co) polymer is preferably used. The copolymer includes a monomer having at least one α, β-ethylenically unsaturated group constituting the hydrophilic portion and at least one α, β-ethylenically unsaturated group constituting the hydrophobic portion. Those obtained by copolymerization with a monomer having a hydrogen atom are preferably used. In addition, a homopolymer of a monomer having an α, β-ethylenically unsaturated group having a hydrophilic group can also be used.

  As the monomer having an α, β-ethylenically unsaturated group constituting the hydrophilic part, a monomer having a carboxyl group, a sulfonic acid group, a hydroxyl group, polyoxyethylene or the like can be used, and preferably a carboxyl group, a sulfone group is used. Acid group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid monoester, fumaric acid, fumaric acid monoester, vinyl sulfonic acid, styrene sulfonic acid, sulfonated vinyl Naphthalene or the like is used. Among these, carboxyl group-containing monomers are particularly preferable, and examples thereof include acrylic acid, methacrylic acid, maleic acid, crotonic acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid monoester, fumaric acid, and fumaric acid monoester. It is not limited to these.

  Examples of the monomer having an α, β-ethylenically unsaturated group constituting the hydrophobic portion include styrene derivatives such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, vinylnaphthalene derivatives, alkyl acrylate esters, methacrylic esters. Examples include, but are not limited to, acid alkyl esters, crotonic acid alkyl esters, itaconic acid dialkyl esters, maleic acid dialkyl esters, and the like.

  Although the weight average molecular weight of the said polymer used as water-soluble resin does not have a restriction | limiting, Preferably it is 3000-15000, More preferably, it is the range of 4000-7000. If the molecular weight is lower than this range, the dispersion stability is inferior, and if it exceeds 15000, the viscosity of the ink becomes high, and the problem that the ink discharge property deteriorates tends to occur. Various methods are known for measuring the average molecular weight of the copolymer. In the present invention, the average molecular weight is defined as a value measured by a GPC (gel permeation chromatography) method.

The dispersant is preferably used as a copolymer or a neutralized salt thereof. Neutralization is neutralized with various basic substances, but preferably with a basic substance containing at least one alkali metal hydroxide. As the alkali metal hydroxide, NaOH, KOH, or LiOH can be used, but NaOH is preferable.
-Water-soluble polymer having an anionic group-
A water-soluble polymer having an anionic group can interact with an aggregating agent (preferably a polyvalent metal salt) contained in another ink to aggregate the ink, and is dispersed when a pigment dispersant is used. It may be the same as the agent.

  As the water-soluble polymer, a known water-soluble resin such as a polymer obtained by a polymerization reaction or a naturally derived resin can be used, and a (co) polymer is preferably used. The copolymer includes a monomer having at least one α, β-ethylenically unsaturated group constituting the hydrophilic portion and at least one α, β-ethylenically unsaturated group constituting the hydrophobic portion. Those obtained by copolymerization with a monomer having a hydrogen atom are preferably used. In addition, a homopolymer of a monomer having an α, β-ethylenically unsaturated group having an anionic hydrophilic group can also be used.

  As the monomer having an α, β-ethylenically unsaturated group constituting the anionic hydrophilic portion, a monomer having a carboxyl group or a sulfonic acid group can be used, for example, acrylic acid, methacrylic acid, crotonic acid, Itaconic acid, itaconic acid monoester, maleic acid, maleic acid monoester, fumaric acid, fumaric acid monoester, vinyl sulfonic acid, styrene sulfonic acid, sulfonated vinyl naphthalene and the like are used. Among these, carboxyl group-containing monomers are particularly preferable, and examples thereof include acrylic acid, methacrylic acid, maleic acid, crotonic acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid monoester, fumaric acid, and fumaric acid monoester. It is not limited to these.

  Examples of the monomer having an α, β-ethylenically unsaturated group constituting the hydrophobic portion include styrene derivatives such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, vinylnaphthalene derivatives, alkyl acrylate esters, methacrylic esters. Examples include, but are not limited to, acid alkyl esters, crotonic acid alkyl esters, itaconic acid dialkyl esters, maleic acid dialkyl esters, and the like.

  The acid value of the water-soluble polymer is preferably 100 to 300, and more preferably 130 to 200. If the acid value is lower than this range, the stability of the ink tends to deteriorate, whereas if it is too high, the image density tends to be low.

  The weight average molecular weight of the water-soluble polymer is preferably 3000 to 10000, more preferably 4000 to 7000. If the molecular weight is lower than this range, the image density tends to be low, and if it exceeds 10,000, the viscosity of the ink becomes high, and the problem of deterioration of the ink ejection property tends to occur. Various methods are known for measuring the average molecular weight of the copolymer. In the present invention, the average molecular weight is defined as a value measured by a GPC (gel permeation chromatography) method.

  The water-soluble polymer is preferably used as a copolymer or a neutralized salt thereof. Neutralization is neutralized with various basic substances, but preferably with a basic substance containing at least one alkali metal hydroxide. As the alkali metal hydroxide, NaOH, KOH, or LiOH can be used, but NaOH is preferable.

-Other additives-
For the ink, for example, various penetrants are used in order to adjust the drying time. As the penetrant, a surfactant or a penetrating solvent is preferable.

  Examples of these surfactants include various anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, and the like. Preferably, anionic surfactants and nonionic surfactants are used. An activator is used.

Specific examples of the surfactant are listed below.
Examples of anionic surfactants include alkylbenzene sulfonate, alkylphenyl sulfonate, alkylnaphthalene sulfonate, higher fatty acid salt, sulfate of higher fatty acid ester, sulfonate of higher fatty acid ester, sulfuric acid of higher alcohol ether. Ester salts and sulfonates, higher alkyl sulfosuccinates, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, etc. can be used, preferably , Dodecylbenzenesulfonate, isopropylnaphthalenesulfonate, monobutylphenylphenol monosulfonate, monobutylbiphenylsulfonate, monobutylbiphenylsulfonate, dibutylphenylsulfonate Nord disulfonic acid salts and the like are used.

  Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, poly Oxyethylene glycerin fatty acid ester, polyglycerin fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene fatty acid amide, alkyl alkanolamide, polyethylene glycol polypropylene glycol block copolymer, acetylene glycol, polyoxyethylene adduct of acetylene glycol Preferably, polyoxyethylene nonyl pheny Ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid alkylolamide, polyethylene glycol polypropylene glycol block copolymer Acetylene glycol and polyoxyethylene adducts of acetylene glycol are used.

  In addition, silicone surfactants such as polysiloxane oxyethylene adducts, fluorine surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and oxyethylene perfluoroalkyl ethers, spicrispolic acid and rhamnolipids Biosurfactants such as lysolecithin can also be used.

  These surfactants may be used alone or in combination. Further, the HLB of the surfactant is preferably in the range of 3 to 20 in view of dissolution stability and the like.

  0.001 to 5 weight% is preferable and, as for the addition amount of these surfactant, 0.01 to 3 weight% is especially preferable.

Further, as a penetrant, formula (1): R-O- XnH ( wherein, R: alkyl having 4-8 carbon atoms (C ₄ -C _8), 4-8 carbon atoms (C ₄ -C ₈₎ Functional group selected from alkenyl, alkynyl having 4 to 8 carbon atoms (C ₄ -C ₈ ), phenyl, alkylphenyl, alkenylphenyl, and cycloalkyl group, X: oxyethylene group or oxypropylene group, n: 1-4 Or an integer thereof may be used.

  Examples of the compound represented by the above formula (1) as the penetrant include ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, diethylene glycol monohexyl ether, dipropylene glycol monobutyl ether, triethylene glycol monobutyl ether, and triethylene glycol. Examples thereof include monohexyl ether, diethylene glycol monocyclohexyl ether, triethylene glycol monophenyl ethyl ether, dioxypropyleneoxyethylene monopentyl ether, and diethylene glycol monobutyl ether is preferably used.

  The compound represented by the above formula (1) as a penetrating agent can be preferably contained in the range of 1 to 20% by weight, more preferably 1 to 10% by weight based on the total ink amount. The If the content of this compound exceeds 20% by weight, the bleeding may be worsened and the ejection may become unstable. On the other hand, if the amount is less than 1% by weight, the effect of addition may be difficult to obtain.

  In addition, urea and urea derivatives can be added to the ink. Examples of urea and urea derivatives include urea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1-diethylurea, 1,3-diethylurea, and urea is preferably used. The content of urea and urea derivatives is 1 to 10% by weight, preferably 3 to 8% by weight of the ink. When the content is 1% by weight or less, the effect of preventing nozzle clogging is low, and when it exceeds 10% by weight, image bleeding increases and the density tends to decrease.

  In addition, a pH adjuster is used in the ink as needed to adjust the pH, but hydrochloric acid, sulfuric acid, nitric acid, acetic acid, citric acid, oxalic acid, malonic acid, boric acid, phosphoric acid, phosphorous acid Acid such as lactic acid, potassium hydroxide, sodium hydroxide, lithium hydroxide, ammonium hydroxide, triethanolamine, diethanolamine, ethanolamine, 2-amino-2-methyl-1-propanol, ammonia and other bases, and phosphorus PH buffering agents such as acid salts, oxalates, amine salts and good buffers are preferred.

  For ink control, poly N vinyl acetamide, polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol, cellulose derivatives such as ethyl cellulose, carboxymethyl cellulose, polysaccharides and derivatives thereof, other water-soluble polymers, acrylic polymer emulsions, polyurethane emulsions for property control Polymer emulsions such as, cross-linked polymers such as cross-linked poly N vinylacetamide and acrylic polymers, cyclodextrins, macrocyclic amines, dendrimers, crown ethers, and the like can be used.

  It should be noted that the ink contains other known antifungal agents such as benzoic acid, 1,2-benzisothiazolin-3-one, and dehydroacetic acid, antiseptics and antioxidants, viscosity modifiers, conductive agents, and ultraviolet rays as necessary. Absorbers, chelating agents and the like can also be added.

-Ink physical properties-
The drying time of the ink is 5 s or more in the case of black ink, preferably 5 to 15 s, more preferably 5 to 10 s. On the other hand, in the case of color ink, it is 5 s or less, more preferably 0.1 to 5 s, and further preferably 0.5 to 3 s.

  Here, the ink drying time means the drying time of the ink on the recording medium. When a solid image of each color of ink is printed on the surface of plain paper by a general ink jet recording apparatus, the printing image is printed after printing. This is the time until the image is not transferred by overlapping paper. Here, plain paper refers to paper that is generally used as plain paper, such as copy paper, high-quality paper, report paper, and notebook, such as FX-L paper (manufactured by Fuji Xerox), 4024 paper (manufactured by Xerox), and the like. Is mentioned.

  In order to speed up the drying time of the ink on the plain paper surface, the viscosity and surface tension of the ink may be reduced, or a penetrant (for example, a surfactant) may be added to the ink as described above.

  The surface tension of the ink is preferably 45 mN / m or less, preferably 40 mN / m or less, and more preferably in the range of 25 to 38 mN / m. Even more preferable combinations as the surface tension of the ink are 30 to 45 mN / m (preferably 25 to 35 mN / m) for the black ink and 28 to 38 mN / m for the color ink. When the surface tension of the ink exceeds 45 mN / m, problems such as long drying time of the ink and deterioration of the fixing strength of the black image tend to occur.

  The viscosity of the ink is preferably adjusted to a range of 1.5 to 5.0 mPa · s, and more preferably adjusted to a range of 1.5 to 3.5 mPa · s. When the viscosity of the ink is less than 1.5 mPa · s, the ink ejection stability is lowered. On the other hand, when the viscosity of the ink is greater than 10 mPa · s, the ejection force is reduced, and problems such as difficulty in recovery when clogging easily occur.

  The conductivity of the ink varies depending on the substance added to the ink and cannot be generally specified. However, the black ink generally has a range of 0.05 to 0.4 S / m, preferably 0.07 to 0.3 S / m. In general, the color ink is adjusted to a range of 0.05 to 2 S / m, preferably 0.07 to 1.5 S / m. If the conductivity deviates from these, the storage stability of the ink tends to deteriorate.

  The pH of the ink is preferably 5.0 to 11.0, and more preferably 7.5 to 9.0. If the pH is less than 5.0, clogging is likely to occur at the nozzle tip, and if it exceeds 11.0, the head component is easily corroded or dissolved.

-Preparation method of ink-
The ink is prepared by mixing the ink components. In particular, when the coloring material is a pigment (including carbon black), add a predetermined amount of pigment to an aqueous solution containing a predetermined amount of a dispersant, and after sufficient stirring, disperse using a disperser and coarsen by centrifugation, etc. After removing the particles, each component such as a predetermined solvent and additives can be added, mixed with stirring, and further filtered. At this time, it is also possible to use a method in which a concentrated dispersion of pigment is prepared and diluted at the time of ink preparation. Or after mixing a predetermined solvent, water, and a dispersing agent, after adding a pigment, you may make it disperse | distribute using a disperser.

  As the disperser, any commercially available one may be used. For example, colloid mill, flow jet mill, slasher mill, high speed disperser, ball mill, attritor, sand mill, sand grinder, ultra fine mill, Eiger motor mill, dyno mill, pearl mill, agitator mill, cobol mill, 3 rolls, 2 rolls Examples thereof include a roll, an extruder, a kneader, a microfluidizer, a laboratory homogenizer, an ultrasonic homogenizer, and a high-pressure homogenizer, and these may be used alone or in combination.

  In the step of dispersing the pigment, various agitation and dispersion devices can be used as described above, but if a disperser using a so-called dispersion medium such as a ball or bead of glass, ceramic, metal, or the like is used, In many cases, inorganic impurities are mixed in a large amount in the pigment dispersion or ink due to abrasion of the dispersion medium and the dispersion container in the dispersion process. Therefore, it is desirable to use a distributed device that does not use distributed media. In particular, it is preferable to disperse with an ultrasonic homogenizer and / or a high-pressure homogenizer. When dispersing with an ultrasonic homogenizer, it is desirable to disperse after defoaming and degassing with a vacuum, heating, a commercially available defoaming / degassing apparatus or the like. When a dispersion apparatus using a dispersion medium is used, the mixed inorganic impurities are removed as necessary.

  After dispersion, it is preferable to remove coarse particles by centrifugation. If necessary, coarse particles are removed by filtration or the like, and then a predetermined solvent, additive, and the like are added, and after stirring and mixing, filtration is performed to obtain an ink. Or you may add the aqueous dispersion of the pigment which carried out the dispersion process, a predetermined solvent, an additive, etc., and after stirring and mixing, a coarse particle may be removed by dispersion processing, centrifugation, filtration, etc.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the present invention.

(Example 1)
[Preparation of ink]
After sufficiently stirring and mixing the following composition components, pressure filtration was performed using a 0.45 μm filter to prepare an ink. The dynamic contact angle after 0.1 s with respect to Ta of the obtained ink was 36 °.

―Composition component―
・ Dye ・ ・ ・ 6wt%
(Product name: CI Direct Yellow 132, weight loss: 9.6%)
・ Glycerin ... 15wt%
・ Sulfolane: 5 wt%
-Acetylene glycol EO adduct ... 2 wt%
・ Water ... 72wt%

[Image recording]
A recording head having the same configuration as in FIG. 2 is mounted on the ink jet recording apparatus having the same configuration as in FIG. 1 (Ta is the heater constituent material, the heater surface is exposed in the heat generation area, the resolution is 1600 dpi, and the number of nozzles is 1632). did. And then. The adjusted ink was set in the ink jet recording apparatus, and the ink was continuously ejected onto the recording paper (2 × 10 ⁸ drops were ejected at all nozzles) to record an image. As a result, good image quality was obtained at high speed, and the heater life was improved with little damage to the heater.

(Example 2)
Image recording was performed in the same manner as in Example 1 except that the following inks were used. As a result, good image quality was obtained at high speed, and the heater life was improved with little damage to the heater.

[Preparation of ink]
After sufficiently stirring and mixing the following composition components, pressure filtration was performed using a 0.45 μm filter to prepare an ink. The dynamic contact angle after 0.1 s with respect to Ta of the obtained ink was 22 degrees.

―Composition component―
・ Dye: 7.5wt%
(Product name CI Acid Yellow 23, weight loss: 13.6%)
・ N-methyl-2-pyrrolidone ... 5wt%
・ Diethylene glycol: 5 wt%
・ Propylene glycol ・ ・ ・ 5wt%
・ Diethylene glycol monohexyl ether ... 0.5wt%
・ Triethylene glycol monobutyl ether ・ ・ ・ 7wt%
・ Dinol 604 ... 0.1wt%
・ Surfinol 440 ... 0.4wt%
・ Water: 69.5 wt%

(Example 3)
Image recording was performed in the same manner as in Example 1 except that the following inks were used. As a result, good image quality was obtained at high speed, and the heater life was improved with little damage to the heater.

[Preparation of ink]
After sufficiently stirring and mixing the following composition components, pressure filtration was performed using a 0.45 μm filter to prepare an ink. The dynamic contact angle after 0.1 s with respect to Ta of the obtained ink was 39 degrees.

―Composition component―
・ Dye: 7.5wt%
(Product name CI Acid Red 52, weight loss: 15.4%)
・ Diethylene glycol ... 20wt%
・ Diethylene glycol monobutyl ether ・ ・ ・ 5wt%
・ Polyoxyethylene polyoxypropylene block polymer
... 0.3 wt%
(Average molecular weight approximately 2900 oxyethylene ratio approximately 40%)
・ Urea ・ ・ ・ 5wt%
・ Water: 62.2 wt%

(Comparative Example 1)
Image recording was performed in the same manner as in Example 1 except that the following inks were used. As a result, the first failure of the heater occurred at 3 × 10 ⁷ drops, and about one third of the heaters failed at the drop of 2 × 10 ⁸ drops.

[Preparation of ink]
After sufficiently stirring and mixing the following composition components, pressure filtration was performed using a 0.45 μm filter to prepare an ink. The dynamic contact angle after 0.1 s with respect to Ta of the obtained ink was 18 degrees.

―Composition component―
・ Dye: 5.0 wt%
(Product name CI Direct black 168, weight loss: 11.5%)
・ Glycerin ... 15wt%
・ Sulfolane ・ ・ ・ 10wt%
・ Fluoroalkyl alcohol oxyethylene adduct
... 0.1 wt%
・ Polysiloxaneoxyethylene adduct ... 0.3wt%
・ Urea ・ ・ ・ 5wt%
・ Water: 64.6 wt%

(Comparative Example 2)
Image recording was performed in the same manner as in Example 1 except that the following inks were used. As a result, the first failure of the heater occurred at 5 × 10 ⁷ drops, and about 1/5 of the heaters failed at the drop of 2 × 10 ⁸ drops.

[Preparation of ink]
After sufficiently stirring and mixing the following composition components, pressure filtration was performed using a 0.45 μm filter to prepare an ink. The dynamic contact angle after 0.1 s with respect to Ta of the obtained ink was 45 degrees.

―Composition component―
・ Dye ・ ・ ・ 6.5wt%
(Product name CI Direct Yellow 144, weight loss: 9.8%)
・ Ethylene glycol: 10wt%
・ Glycerin ... 10wt%
・ Diethylene glycol monobutyl ether ... 3.5wt%
・ Water: 70wt%

  As described above, as shown in the examples, it can be seen that the ink jet recording method of the present invention can provide good image quality at a high speed, and the heater life is improved with little damage to the heater.

It is a schematic perspective view which shows an example of the inkjet recording device applied to the inkjet recording method which concerns on embodiment of this invention. FIG. 2 is a configuration diagram illustrating an example of an ink jet recording head applied to an ink jet recording method according to an embodiment of the present invention, in which (A) is a plan view and (B) is a b-b ′ cross-sectional view of (A).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inkjet recording device 12 Inkjet recording head 14 Carriage 16 Shaft 18 Recording paper 20 Carrying roller 22 Ink tank 24 Inkjet cartridge 30 Substrate 32 Heat storage layer 34 Heater 36 Electrode layer 38 Electrode protective layer 40 Ink channel 42 Ink ejection port 44 Ink channel Forming body 46 Ink supply port

Claims (3)

Using a recording head having a resolution of 1600 dpi or more, the number of nozzles of 1600 or more, and a heating resistor layer composed of a Ta layer, thermal energy is directly applied to the ink from the heating resistor layer, An ink jet recording method for recording an image on a recording medium by discharging the ink from the nozzle,
The ink contains water, a water-soluble organic solvent, and a coloring material, and has a dynamic contact angle after 20 seconds of 20 to 40 degrees with respect to the Ta layer as the heating resistor layer. Inkjet recording method.   2. The ink jet recording method according to claim 1, wherein the content of the color material is 5 wt% or more.   2. The ink jet recording method according to claim 1, wherein the color material has a decomposition temperature of less than 400 ° C. and a weight reduction rate by thermal decomposition in a range of 300 ° C. to 400 ° C. of 8% or more.

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