JP2006150954A - Inkjet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to make high image quality and high reliability compatible, to remove a possibility of clogging of a nozzle with a foreign substance mixed from outside or a deposit or the like from an ink, to perform a stable feeding of the ink even when a high speed printing is performed, and to ensure a delivering stability during printing. <P>SOLUTION: In an inkjet recording apparatus wherein the ink comprising a coloring agent dispersed in water, a wetting agent, a surfactant and a penetrating agent is delivered from a head including a filter as a constituent, the inkjet recording apparatus is characterized by that the viscosity of the ink at 25°C is 6-13 mPa s, and a fluid resistance of the filter to the ink is in a range of 4.4×10<SP>9</SP>to 2.2×10<SP>10</SP>Pa s/m<SP>3</SP>. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  Inkjet printers have been rapidly spreading in recent years because they are capable of printing on plain paper, are easy to color, are small in size and inexpensive, and have low running costs. In general, ink-jet recording ink has the required properties such as color tone, image density, and bleeding to achieve high image quality, and the solubility or dispersion stability / storage stability of the colorant in the ink to achieve reliability.・ Water resistance and light resistance to ensure the storage stability of recorded images, such as ejection stability, and quick drying of ink to achieve high speed. Proposals have been made.

As a colorant for ink jet recording ink, dye ink was mainly used at the beginning because of its good color development and high reliability, but recently it has become light and water resistant on recorded images. Ink compositions using pigments such as carbon black are also attracting attention.
In addition, in order to achieve high image quality and high-speed printing, recently, there is a tendency to reduce the size of ink droplets. For this reason, the nozzle diameter tends to be reduced.
Therefore, it is quite difficult to use a pigment as a colorant and to ensure ejection stability in a printer with a reduced nozzle diameter, and many attempts have been made to achieve compatibility with other ink characteristics. The current situation is that no response has been made.

Up to now, in order to improve the reliability of the printer, improvement of long-term storage stability of the ink (preventing the formation of coarse particles due to pigment aggregation etc.) and ink when the water in the ink evaporates near the nozzle The formulation design etc. which suppress the increase in viscosity of as much as possible have been proposed. In addition, for the purpose of preventing dust and the like mixed from the outside, it has been proposed to provide a filter between the ink supply unit and the ink discharge unit.
Regarding the prescription design of the ink, for example, Patent Documents 1 to 3 describe that ejection stability is ensured by specifying the viscosity at the time of ink concentration, but with these inks, high image quality on plain paper is described. It was insufficient to ensure. Japanese Patent Application Laid-Open No. H10-228561 describes that a high-viscosity ink (5 to 15 mPa · s) is necessary to ensure high image quality. According to this, the initial evaporation rate is adjusted to ensure reliability, and a specific compound is preferably added as a viscosity adjusting agent for adjusting the viscosity. There is no description about the stability, and the ink formulation is inferior in reliability, for example, when it is left for a longer period depending on the configuration of the head to be ejected and the size of the nozzle diameter.
The filter provided between the ink supply system and the ink discharge system should prevent clogging of nozzles or ink flow paths due to dust from the outside, dust in the ink, deposits from the ink, and air bubbles. Various proposals have been made for the purpose.
For example, Patent Document 5 proposes a device for preventing an ink flow from being obstructed by trapping bubbles in a filter provided as a dust removing means. In Patent Document 6, a proposal for achieving both high definition and high speed has been made. According to this, it is necessary to reduce the nozzle diameter in order to improve the image quality, and accordingly, it is necessary to make the hole diameter of the filter for dust removal finer. The problem that the pressure difference before and after the filter increases and the response frequency decreases can be avoided by devising the configuration. In Patent Document 7, by making the inertance and flow path resistance of the filter to be used within a certain range, clogging due to foreign matter inflow is eliminated, and pressure generated when ink droplets are ejected is relaxed and absorbed, and stable. It is said that discharge can be secured. However, this patent proposes a filter composed of a plurality of grooves formed by etching on an anisotropic crystal substrate, lacking versatility, and the particle size and shape of the colorant of the ink used. There is no description about the relationship. Patent Document 8 suggests that dust once trapped by a filter may pass through the filter by using a head for a long time and repeatedly sucking and discharging ink, and two types of filters are provided. However, this is not very advantageous from the viewpoint of cost.

JP 2002-337449 A JP 2000-95983 A Japanese Patent Laid-Open No. 9-111166 JP 2001-262025 A Japanese Patent No. 3168122 Japanese Patent No. 3267457 Japanese Patent No. 3389732 JP 2002-238881 A

The present invention is an ink jet recording apparatus equipped with a head including a filter as a constituent element. The viscosity of ink used at 25 ° C. is adjusted to 6 to 13 mPa · s, and the fluid resistance of the filter to the ink is 4.4. By adjusting to be in the range of × 10 ^{9 to} 2.2 × 10 ¹⁰ Pa · s / m ³ , both high image quality and high reliability can be achieved. Accordingly, the nozzles are not clogged with foreign matters mixed from the outside or precipitates from the ink, and stable ink supply can be performed even during high-speed printing, thus ensuring ejection stability during printing.

The ink used in the ink jet recording apparatus of the present invention contains a colorant, a wetting agent, a surfactant, and a penetrating agent as basic constituent elements, and has a viscosity at 25 ° C. of 6 to 13 mPa · s depending on the combination and blending ratio. It is characterized by having been adjusted to. According to the present invention, the fluid resistance of the filter used as a component of the head is adjusted to be in the range of 4.4 × 10 ^{9 to} 2.2 × 10 ¹⁰ Pa · s / m ³ with respect to the ink. Therefore, it is possible to achieve both high image quality and high reliability.
In particular, the average particle diameter of the color material in the ink is not specified, but is preferably in the range of 5 to 200 nm. When the particle diameter is larger than 200 nm, the filter is likely to be clogged, and it is difficult to ensure ejection stability. If it becomes smaller, the manufacturability deteriorates, the cost increases, and the ink tends to aggregate, so that the storage stability as ink tends to become unstable.
The average particle diameter of the colorant here refers to a value of 50% cumulative volume percentage. In order to measure the value of 50% of the cumulative volume, for example, the laser beam is irradiated to the particle performing Brownian motion in the ink, and the frequency (light frequency) of the light returning from the particle (back scattered light) is measured. ) Can be used as a dynamic light scattering method (Doppler scattered light analysis) for obtaining the particle diameter from the change amount.
The fluid resistance R of the filter can be obtained by R = PT / V, where V is the amount of ink that flows for a certain time T under a certain pressure P condition.

That is, the above-described problem is (1) in the inkjet recording apparatus in which an ink comprising a colorant, a wetting agent, a surfactant, and a penetrating agent dispersed in water is ejected from a head including a filter as a component. The viscosity of the ink at 25 ° C. is 6 to 13 mPa · s, and the fluid resistance of the filter to the ink is in the range of 4.4 × 10 ^{9 to} 2.2 × 10 ¹⁰ Pa · s / m ^3. (2) “The ink contains 3 to 15 wt% of a colorant and 10 to 40 wt% of a wetting agent”. (3) “The colorant is separated into water without a dispersant by being treated so that at least one hydrophilic group is bonded to the surface thereof directly or through another atomic group. The ink jet recording apparatus according to item (1) or (2), wherein the colorant is a surfactant and / or a polymer dispersion, (5) “The colorant is water-insoluble in the polymer fine particles, or the ink-jet recording apparatus according to any one of the items (1) to (3)”, which is a pigment dispersed by an agent. The ink jet recording apparatus according to any one of (1) to (4) above, which is a polymer emulsion containing a hardly soluble coloring material, and (6) “as the wetting agent” Any one of (1) to (5) above, characterized in that it contains at least one polyhydric alcohol having an equilibrium water content of 25 wt% or more in an environment of 20 ° C. and 60% relative humidity. Ink cartridges described in (7) “One of the polyhydric alcohols is glycerin, and the content of glycerin is 20 wt% or more and 80 wt% or less of the whole wetting agent” (6 (8) "The penetrant contains at least one polyol having a solubility in water at 20 ° C of 0.2 wt% or more and less than 5.0 wt%" as the penetrant. The inkjet recording apparatus according to any one of Items (1) to (7), (9) “The polyol is 2-ethyl-1,3-hexanediol,” (8) Inkjet recording apparatus according to item (8), (10) “The polyol is 2,2,4-trimethyl-1,3-pentanediol,” (8) Inkjet recording apparatus ”, (11)“ The ink further contains 2-amino-2-ethyl-1,3-propanediol, ”in the above (1) to (10), This is solved by the “inkjet recording apparatus” described in any one of the above.
The above-described problem is a recording method using the inkjet recording apparatus according to any one of (12) and (1) to (11) of the present invention, in which the size of droplets ejected from the nozzles is increased. Inkjet recording method characterized by 3 to 40 pl, droplet speed of 6 to 20 m / s, frequency of 1 KHz or more, and resolution of 300 dpi or more ”, (13)“ Item (12) ” This is solved by an inkjet recording method, in which a plurality of ink droplets are continuously ejected and merged to form large droplets before landing on a recording medium.
In addition, the above-mentioned problem is (14) of the present invention “a head mounted in the recording apparatus discharges ink by using a plurality of pressurized liquid chambers, nozzles having a hole diameter of 35 μm or less communicating with the pressurized liquid chambers, ink supply paths, and ink. The inkjet according to any one of (1) to (11) above, wherein the inkjet head is a recording head comprising an electrical pressure conversion means or an electrothermal conversion means, a filter, and an ink tank that generates a negative pressure. Solved by "recording device".

According to the present invention, in an ink jet recording apparatus in which an ink composed of a colorant, a wetting agent, a surfactant, and a penetrating agent dispersed in water is ejected from a head including a filter as a component, the viscosity of the ink at 25 ° C. Adjusted to 6 to 13 mPa · s, and the fluid resistance of the filter to the ink is in the range of 4.4 × 10 ^{9 to} 2.2 × 10 ¹⁰ Pa · s / m ³ under conditions of 25 ° C. environment and water head pressure 150 mmaq. By adjusting as described above, it is possible to provide an extremely excellent effect that it is possible to provide an ink jet recording apparatus having both high reliability and high image quality.

Hereinafter, the components of the ink will be described in detail, but the present invention is not limited to these.
As for the colorant, a pigment is mainly used from the viewpoint of weather resistance. However, for the purpose of adjusting the color tone, a dye may be contained at the same time as long as the weather resistance is not deteriorated.
Regardless of whether the pigment is an inorganic pigment or an organic pigment, self-dispersed, dispersed with a surfactant and / or polymer dispersant, emulsion type, or self-dispersed pigment is coated with a resin. And may be dispersed.
The average particle diameter of the pigment is preferably in the range of 5 to 200 nm from the viewpoint of reliability. More preferably, it is the range of 10-150 nm. More preferably, it is the range of 10-100 nm.

  Inorganic pigments include titanium oxide and iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chrome yellow, as well as carbon produced by known methods such as the contact method, furnace method, and thermal method. Black can be used.

  Organic pigments include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments), polycyclic pigments (eg, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazines). Pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinofullerone pigments, etc.), dye chelates (for example, basic dye type chelates, acidic dye type chelates), nitro pigments, nitroso pigments, aniline black, and the like can be used. Of these pigments, those having good affinity with water are particularly preferably used.

Specific examples of pigments that are more preferably used in the above-mentioned pigments include black for carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, or copper, iron. (CI pigment black 11), metals such as titanium oxide, and organic pigments such as aniline black (CI pigment black 1).
Further, for color use, 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, 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.

  Among these pigments, a preferable form is one whose surface is modified so that at least one hydrophilic group is bonded directly or via another atomic group to the surface of the pigment. 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 wet oxidation is performed using hypohalous acid and / or a salt thereof. A method such as processing is used. Among these, a preferable form is a form in which carboxyl groups are bonded to the surface of the pigment and dispersed in water. 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. In addition, 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.

  It is also possible to use a polymer emulsion in which a pigment is contained in fine polymer particles in addition to the pigment in the above form. The polymer emulsion containing a pigment is one in which a pigment is encapsulated in polymer fine particles and / or a pigment adsorbed on the surface of the polymer fine particles. 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, and polyurethane polymers. Particularly preferred polymers are vinyl polymers and polyester polymers.

  Furthermore, in the present invention, a pigment obtained by dispersing in an aqueous medium with a dispersant can be used in combination. As a preferable dispersing agent, a known dispersing agent used for preparing a conventionally known pigment dispersion can be used, and examples thereof include the following.

  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 Polymer, styrene-acrylic acid-acrylic acid alkyl ester copolymer, styne-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic Acid copolymer-alkyl acrylate ester copolymer, styrene-maleic acid copolymer, vinyl naphthalene-maleic acid copolymer, vinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinyl ethylene copolymer, vinyl acetate -Maleic acid ester copolymer, vinyl acetate Rotonic acid copolymer, vinyl acetate-acrylic acid copolymer, etc.

  These copolymers preferably have a weight average molecular weight of 3,000 to 50,000, more preferably 5,000 to 30,000, and most preferably 7,000 to 15,000. The addition amount of the dispersant may be appropriately added as long as the pigment is stably dispersed and the other effects of the present invention are not lost. The dispersant is preferably in the range of 1: 0.06 to 1: 3, more preferably in the range of 1: 0.125 to 1: 3.

  More preferably, a carboxyl group is bonded to the dispersant in the ink. 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 above-described back-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. Can be 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. It is presumed that the solubility of the dispersant itself decreases due to interaction with ions and the like, and the dispersant itself and the pigment aggregate.

In the present invention, not only the pigment but also the following dyes can be used in combination.
For example, C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142
C. 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. Acid Blue 9, 29, 45, 92, 249
C. I. Acid Black 1, 2, 7, 24, 26, 94
C. I. Food Yellow 2, 3, 4
C. I. Food Red 7, 9, 14
C. I. Food Black 1, 2
As a direct dye, C.I. I. Direct yellow 1, 12, 24, 26, 33, 44, 50, 120, 132, 142, 144, 86
C. I. Direct Red 1, 4, 9, 13, 17, 20, 28, 31, 39, 80, 81, 83, 89, 225, 227
C. I. Direct Orange 26, 29, 62, 102
C. I. Direct Blue 1, 2, 6, 15, 22, 25, 71, 76, 79, 86, 87, 90, 98, 163, 165,
199, 202
C. I. Direct black 19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154, 168, 171
As a basic dye, 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, 465, 67 70, 73, 77, 87, 91
C. 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
C. 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
C. I. Basic Black 2, 8
As a reactive dye, C.I. I. Reactive Black 3, 4, 7, 11, 12, 17
C. I. Reactive Yellow 1, 5, 11, 13, 14, 20, 21, 22, 25, 40, 47, 51, 55, 65, 67
C. I. Reactive Red 1, 14, 17, 25, 26, 32, 37, 44, 46, 55, 60, 66, 74, 79, 96, 97
C. I. Reactive Blue 1, 2, 7, 14, 15, 23, 32, 35, 38, 41, 63, 80, 95
Etc. can be used. Of these, acid dyes and direct dyes are particularly preferable.

  The amount of the colorant added to the ink is preferably about 3 to 15% by weight, more preferably about 5 to 12% by weight. If the colorant is less than 3%, the ink density is thin, and it is difficult to secure a clear image with a small amount of adhesion (ink droplets). If it exceeds 15%, the colorant density is too high, and the colorant Aggregation tends to occur, which tends to cause ejection failure.

  As a wetting agent, it is easy to form a hydrogen bond, and it has a high viscosity by itself, and has a high equilibrium water content and a viscosity that decreases in the presence of water. Ink that can be obtained can be obtained.

  Such polyhydric alcohols include glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 3-methyl-1,3-butanediol, 1,3-butanediol, 2 , 3-butanediol, 1,4-butanediol, 1,5-pentanediol, tetraethylene glycol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, polyethylene glycol, 1,2,4 -Butanetriol, 1,2,6-hexanetriol and the like are mentioned, but especially glycerin increases its viscosity rapidly with moisture evaporation, but prevents aggregation of the colorant and prevents the particle size from increasing. Because it is high, adding 20% or more of the total wetting agent It is a principal. Glycerin is also preferable from the standpoint of equilibrium water content and the like.

  As the wetting agent used in combination with glycerin, 1,3-butanediol or 3-methyl-1,3-butanediol is desirable. 1,3-butanediol and 3-methyl-1,3-butanediol have a high equilibrium moisture content and high reliability like glycerin, and make the spread of pixels uniform when the ink lands on the paper, Furthermore, the effect of keeping the color material on the paper surface is high. In particular, 3-methyl-1,3-butanediol is highly effective in making the spread of pixels more uniform, and can form a high-quality image. 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 deteriorate. It is important that the mixing ratio is preferably in the range of 1: 4 to 4: 1, more preferably 1: 3 to 3: 1, and even more preferably 1: 1 to 3: 1. The ratio of the wetting agent in the total ink is 10 to 40% within the range where the effects of the present invention can be obtained, and particularly preferably 25 to 35%. When the amount of the wetting agent is small, the storage stability and ejection stability of the ink are deteriorated, and the nozzles are easily clogged. On the other hand, if the amount of the wetting agent is too large, the drying property is deteriorated, bleeding of characters and bleeding of the color boundary occurs, and the image quality is deteriorated.

  The surfactant and penetrant added to the ink of the present invention are added for the purpose of imparting the properties described below. The surfactant used in the present invention has a purpose of lowering the static surface tension especially 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 used in the present invention has a purpose of lowering the more dynamic surface tension particularly in the vicinity of 10 to 100 msec and promoting the spread on the paper surface at the moment when the ink lands 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.

  There are no particular limitations on such surfactants, and any of amphoteric surfactants, nonionic surfactants, and anionic surfactants can be used, but the relationship between the dispersion stability of colorants and image quality From polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkyl amine, polyoxyethylene alkyl amide, polyoxyethylene propylene block polymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, ethylene oxide of acetylene alcohol Nonionic surfactants such as additives are desirably used. Depending on the formulation, it is possible to use (or use alone) a fluorine-based surfactant or a silicone-based surfactant. Of these, nonionic surfactants represented by the following general formula (1) are particularly desirable.

（Ｒは、炭素数６〜１４の分岐してもよいアルキル基を示し、ｍは正数を示す。）
画質の面から、Ｒは好ましくは炭素数１０以上のアルキル基であり、またｍは７〜９の範囲が好ましい。
インク組成物中でのこれら界面活性剤の添加量は、好ましくは０．０１重量％〜５．０重量％であり、より好ましくは０．５重量％〜３重量％である。０．０１重量％未満では添加した効果はなく、５．０重量％より多い添加では記録媒体への浸透性が必要以上に高くなり、画像濃度の低下や裏抜けの発生といった問題が発生することがある。
一般式（１）の具体例としては以下のものが挙げられるが、これらに限定されるものではない。

(R represents an alkyl group having 6 to 14 carbon atoms which may be branched, and m represents a positive number.)
From the viewpoint of image quality, R is preferably an alkyl group having 10 or more carbon atoms, and m is preferably in the range of 7-9.
The addition amount of these surfactants in the ink composition is preferably 0.01% by weight to 5.0% by weight, and more preferably 0.5% by weight to 3% by weight. If it is less than 0.01% by weight, there is no effect, and if it is more than 5.0% by weight, the permeability to the recording medium becomes higher than necessary, causing problems such as a decrease in image density and occurrence of show-through. There is.
Specific examples of the general formula (1) include the following, but are not limited thereto.

  Moreover, these may be used independently or may be used in mixture of multiple things. Even if it is not easily dissolved by itself in the recording liquid, it can be solubilized by mixing and exist stably. Commercially available surfactants containing this compound as a main component include BT series available from Nikko Chemicals, Softanol series available from Nippon Shokubai, and Nippon Oil & Fats. Possible dispanols.

The penetrant used in the present invention preferably contains at least one polyol having a solubility in water at 20 ° C. of 0.2 wt% or more and less than 5.0 wt%. Among such polyols, aliphatic diols include 2-ethyl-2-methyl-1,3-propanediol, 3,3-dimethyl-1,2-butanediol, and 2,2-diethyl-1,3. -Propanediol, 2-methyl-2-propyl-1,3-propanediol, 2,4-dimethyl-2,4-pentanediol, 2,5-dimethyl-2,5-hexanediol, 5-hexene-1 , 2-diol, 2-ethyl-1,3-hexanediol and the like.
Of these, 2-ethyl-1,3-hexanediol and / or 2,2,4-trimethyl-1,3-pentanediol are most desirable.

  Other penetrants that can be used in combination include polyethylene alcohols such as diethylene glycol monophenyl ether, ethylene glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, and tetraethylene glycol chlorophenyl ether. Examples thereof include alkyl and aryl ethers, lower alcohols such as ethanol, and the like, but are not limited thereto as long as they can be dissolved in ink and adjusted to desired physical properties. The amount of penetrant added is preferably in the range of 0.1 to 4.0%. If the addition amount is less than 0.1%, quick drying may not be obtained and a blurred image may be obtained. On the other hand, if the addition amount is more than 4.0%, the dispersion stability of the colorant is impaired, the nozzle is easily clogged, and the permeability to the recording medium is unnecessarily high, resulting in a decrease in image density. And problems such as the occurrence of strikethrough may occur.

  Examples of ink components other than the basic components include pH adjusters, antiseptic / antifungal agents, chelating reagents, and rust inhibitors.

  As a pH adjuster, any substance (for example, amines such as diethanolamine and triethanolamine, hydroxylation, etc.) can be used as long as the pH can be adjusted to a desired value without adversely affecting the recording liquid to be prepared. Alkali metal hydroxides such as lithium, sodium hydroxide and potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide, quaternary phosphonium hydroxide, alkali such as lithium carbonate, sodium carbonate and potassium carbonate Metal carbonates, etc.) can be used, but especially when an appropriate amount of 2-amino-2-ethyl-1,3-propanediol is used, the dispersion stability of the pigment is further improved and the discharge stability is improved. And the like are ensured. The amount added depends on the formulation system to be added and the desired pH value, but is preferably in the range of 0.01 to 2%, more preferably in the range of 0.1 to 1%. It has also been confirmed that the addition of 2-amino-2-ethyl-1,3-propanediol improves the reliability of contact with the member used in the ink flow path.

  As antiseptic / antifungal agents, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol and the like can be used in the present invention.

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

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

  The ink used in the present invention is characterized in that the viscosity at 25 ° C. is adjusted to 6 to 13 mPa · s by the combination and blending ratio of the constituent elements. This ensures high image quality even when high-speed printing is performed on plain paper.

Further, the ink is used in a recording method in which the size of droplets ejected from the nozzle is 3 to 40 pl, the velocity of the droplets is 6 to 20 m / s, the frequency is 1 KHz or more, and the resolution is 300 dpi or more. Furthermore, it is used in a recording method in which a plurality of ink droplets are continuously ejected and merged before landing on a recording medium to form a large droplet, thereby exhibiting a greater effect.
The ink of the color material such as a pigment having the average particle diameter in the present invention has, for example, the adoption of a preliminary dispersion process of the color material such as the pigment, the selection of the dispersion medium, and the mixing ratio of the dispersant type and the color material (pigment). A desired product can be obtained by adjustment and / or adjustment of stirring time and stirring conditions (stirring speed and the like) and further adjustment of conditions for subsequent centrifugation.
In addition, regarding the adjustment of the ink within the viscosity in the present invention, in order to form a high-definition image at high speed, it is required that a high-density image can be formed with fine droplets, and for that purpose, the pigment concentration is considerably increased. Accordingly, it is necessary to add a wetting agent corresponding to the pigment concentration in order to ensure ejection stability. In order to adjust the viscosity, usually (but not limited to) the constant wetting agent type and amount can be adjusted. A merit of high viscosity is that image quality can be improved. Disadvantages include a requirement for ejection force and difficulty in ensuring reliability. In fact, a high-viscosity ink as in the present invention using a small particle size colorant as in the present invention has not been reported so far.

The recording apparatus of the present invention will be described below.
The ink jet recording apparatus of the present invention has at least an ink discharge means (= head), and uses an electric pressure conversion means or an electrothermal conversion means as the discharge means.
This head is provided with a filter between the ink supply unit and the ink discharge unit, and the fluid resistance of the filter is 4.4 × 10 ^{9 to} 2.2 × 10 with respect to the ink used. ^The discharge stability is ensured by adjusting to a range of ¹⁰ Pa · s / m ³ .
The head also includes a plurality of pressurized liquid chambers, a nozzle having a hole diameter of 35 μm or less communicating with the pressurized liquid chambers, an ink supply path, an ink discharge unit including an electric pressure conversion unit or an electrothermal conversion unit for discharging ink, and an ink discharge unit. A filter is provided between the ink supply unit including an ink tank that generates a negative pressure in the unit.
The diameter of the hole communicating with the pressurized liquid chamber (= nozzle diameter) is 35 μm or less, more preferably 30 μm or less, and still more preferably 25 μm or less.

FIG. 1 and FIG. 2 show an example of the configuration of the ink ejection unit using the electric pressure conversion means.
FIG. 3 is an element enlarged view of the ejection part of the ink jet head to which the present invention is applied, and FIG.
The ink jet head discharge section includes a frame (1) formed with a notch that is not shown and a common liquid chamber (1-2), a fluid resistance section (2-1), and a pressurized liquid chamber (2). -2) and the flow path plate (2) formed with the communication port (2-3) communicating with the nozzle (3-1), the nozzle plate forming the nozzle (3-1), and the convex portion ( 6-1), a diaphragm (6) having a diaphragm part (6-2) and an ink inlet (6-3), and a laminated piezoelectric element (5) joined to the diaphragm via an adhesive layer (7) And a base (4) to which the laminated piezoelectric element (5) is fixed. The base (4) is made of a barium titanate ceramic, and the laminated piezoelectric elements (5) are arranged in two rows and joined.
The laminated piezoelectric element (5) is composed of a lead zirconate titanate (PZT) piezoelectric layer (not shown) having a thickness of 10 to 50 μm / layer and a silver / palladium (AgPd) having a thickness of several μm / layer. The internal electrode layers (not shown) are alternately stacked. An internal electrode layer (not shown) is connected to an external electrode (not shown) at both ends.
The laminated piezoelectric element (5) is divided on comb teeth by half-cut dicing, and each one is used as a drive part (5-6) and a support part (5-7) (non-drive part).
The outside of the external electrode (not shown) is limited by machining such as notches so as to be divided by half-cut dicing, and these become a plurality of individual electrodes (not shown). The other is conductive without being divided by dicing, and becomes a common electrode (5-5).
An FPC (8) is soldered to an individual electrode (not shown) of the drive unit. Further, the common electrode (5-5) is provided with an electrode layer at the end of the laminated piezoelectric element and is wound around to join the Gnd electrode of the FPC (8). A driver IC (not shown) is mounted on the FPC (8), thereby controlling application of drive voltage to the drive unit (5-6).

The diaphragm (6) is joined to a thin film diaphragm portion (6-2) and a laminated piezoelectric element (5) which is a drive portion (5-6) formed at the center portion of the diaphragm portion (6-2). An island-shaped convex portion (island portion) (6-1), a thick film portion including a beam joined to a support portion (not shown), and an opening serving as an ink inflow port (6-3) are plated with Ni by electroforming. Two layers of films are formed. The diaphragm portion has a thickness of 3 μm and a width of 35 μm (one side).
The coupling between the island-shaped convex part (6-1) of the diaphragm (6) and the movable part (5-6) of the laminated piezoelectric element (5) and the diaphragm (5) and the frame (1) includes a gap material. The adhesive layer (7) is bonded by patterning.

The flow path plate (2) uses a silicon single crystal substrate, the engraving that becomes the fluid resistance portion (2-1), the pressurized liquid chamber (2-2), and the communication port ( The through hole to be 2-3) was patterned by an etching method.
The portion left by etching becomes the partition wall (2-4) of the pressurized liquid chamber (2-2). Further, in this head, a portion for narrowing the etching width was provided, and this was used as the fluid resistance portion (2-1).

The nozzle plate (3) is formed of a metal material, for example, an Ni plating film by an electroforming method, and has a large number of nozzles (3-1) which are fine discharge ports for flying ink droplets. . The internal shape (inner side shape) of the nozzle (3-1) is formed in a horn shape (may be a substantially cylindrical shape or a substantially frustum shape). The diameter of the nozzle (3-1) is approximately 20 to 35 μm on the ink droplet outlet side. The nozzle pitch of each row was 150 dpi.
The ink ejection surface (nozzle surface side) of the nozzle plate (3) is provided with a water repellent treatment layer (not shown) subjected to a water repellent surface treatment (not shown). Ink physical properties such as PTFE-Ni eutectoid plating, electrodeposition coating of fluororesin, vapor-deposited fluororesin (for example, fluorinated pitch), baking after solvent application of silicon resin / fluorine resin, etc. A water-repellent treatment film selected according to the above is provided to stabilize the ink droplet shape and flight characteristics so that high-quality image quality can be obtained.
The frame (1) that forms the engraving that becomes the ink supply port and the common liquid chamber (1-2) (not shown) is made by resin molding.

In the ink jet head configured as described above, a drive waveform (pulse voltage of 10 to 50 V) is applied to the drive unit (5-6) in accordance with the recording signal, so that the drive unit (5-6) in the stacking direction is applied. Displacement occurs, the pressurized liquid chamber (2-2) is pressurized through the diaphragm (3), the pressure rises, and ink droplets are ejected from the nozzle (3-1).
Thereafter, the ink pressure in the pressurizing liquid chamber (2-2) decreases with the end of the ink droplet ejection, and the pressure in the pressurizing liquid chamber (2-2) depends on the inertia of the ink flow and the discharge process of the drive pulse. Negative pressure is generated and the process proceeds to the ink filling process. At this time, the ink supplied from the ink tank flows into the common liquid chamber (1-2), and flows from the common liquid chamber (1-2) through the ink inlet (6-3) to the fluid resistance portion (2-1). And the pressurized liquid chamber (2-2) is filled.
The fluid resistance portion (2-1) has an effect on the attenuation of the residual pressure vibration after ejection, but becomes resistant to refilling (refill) due to surface tension. By appropriately selecting the fluid resistance portion, 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.

  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 ink discharge portion of the ink jet head is formed of a material containing at least one of silicon and nickel.

3 and 4 show an example of the ink supply unit (= sub tank).
FIG. 3 is an exploded perspective view for explaining an example of the structure around the inkjet head portion in the inkjet printer, in which (10) is a lever, (13) is a drive device for the lever (10), 20) is a carriage for mounting an ink jet head, (21) is an air release pin, (22) is a negative pressure pin, (23) is an elastic member, (30) is a sub tank for stocking ink in the carriage, (31 ) Is an air opening for adjusting the inside of the sub tank case to atmospheric pressure, (32) is a negative pressure lever, (40) is an inkjet head (hereinafter simply referred to as a head), and (50) is an ink cartridge. , (51) are connecting tubes for connecting the ink cartridge (50) and the sub tank (30) to supply ink to the sub tank (30).

  The filter of the present invention is provided at a portion connecting the sub tank (30) and the head (40) of FIG. For example, in an ink jet printer having a large amount of ink in a cartridge or an ink jet printer aiming at high image quality, when an ink cartridge is mounted in a carriage on which a head is mounted, the carriage (20) is Since image displacement may occur due to the influence of weight, for example, as shown in FIG. 3, an ink cartridge (50) is installed outside the carriage (20), and ink is temporarily put into the carriage (20). Some have a configuration with a sub-tank (30) for stocking.

  If the internal pressure of the sub tank (30) is positive, the ink leaks from the head (40) due to the weight of the ink in the sub tank (30), so the internal pressure of the sub tank (30) is negative. Must be set to Such pressure setting is important for the characteristics of ejecting ink from the head, but air may be mixed in from the ink cartridge (50) or the connecting tube (51), and the amount of air inside the sub tank (30). As the time increases with time, the internal pressure of the sub-tank (30) also changes, causing a problem that the quality of the image formed by ink deteriorates. For this reason, control is performed to periodically restore the air ratio and pressure setting inside the ink cartridge (50).

FIG. 4 is a perspective exploded configuration diagram for explaining the configuration example of the sub tank (30) shown in FIG. 3 in more detail.
The sub-tank (30) includes a case (33) which is constituted by a substantially rectangular top wall (39a), a bottom wall (39b) and three side walls (39c), and the other side wall is open, and the case A film (34) that covers the opening of (33), an elastic member (36) that presses the film (34) from the inside through a plate (35), and a film (34) that is pushed back from the outside. It is comprised from the negative pressure lever (32) which is a plate-shaped elastic member to urge. The elastic member (36) that presses the film (34) from the inside is set so as to press the film (34) with a stronger pressure than the negative pressure lever (32) that presses the film (34) from the outside. In the initial state, the film (34) is pushed outward. At this time, the balance of the pressing force between the negative pressure lever (32) and the inner elastic member (36) changes according to the fluctuation of the internal pressure of the sub tank (30), and the amount of ink in the sub tank (30) decreases. The film (34) is pushed back inward as the internal pressure changes.

  An air release port (31) provided in one of the side walls (39c) and an ink filling port (37) provided in the upper wall (39a) of the case (33) are elastic members (311), Sealed in a normal state by the close contact between the balls (312) and (372) pressed by (371), the elastic members (313) and (373) such as rubber, and the caps (314) and (374). ing. The ink filling port (37) is opened by the ink pressure flowing through the connecting tube (51) shown in FIG. 3, and the ink that flows in is supplied into the sub tank (30). Further, the air release port (31) is opened when the air release pin (21) provided on the carriage (20) shown in FIG. 3 is pressed and pushed in, and the internal pressure of the sub tank (30) can be adjusted.

  Further, the carriage (20) is provided with a negative pressure pin (22) for pushing the negative pressure lever (32) of the sub tank (30) from the outside, and the negative pressure lever (32) is provided inside the sub tank (30). The internal capacity of the sub tank (30) can be reduced by pushing the negative pressure pin (22) so as to be displaced. The elastic member (23) is provided so as to urge the negative pressure lever (32) and the negative pressure pin (22) in a direction away from each other, and normally the negative pressure lever (32) is caused by the action of the elastic member (23). ) And the negative pressure pin (22) are not touched.

  In the operation of the ink jet head configured as described above, the air release pin (21) is first operated to open the air release port (31), and the negative pressure pin (22) is operated to make negative. Ink is filled through the ink filling port (37) in a state where the internal volume of the sub tank (30) is reduced by pushing the pressure lever (32). The filled ink is detected at the upper part of the sub tank (30) by the full detection sensor (38), and the ink supply is controlled according to the detection result, thereby determining the air amount and the ink amount in the sub tank (30). Is done. Thereafter, the air release port (31) is closed and sealed, and then the pressure on the negative pressure lever (32) held in the pressed state is released. By such an operation, the inside of the sub tank (30) is controlled with a constant negative pressure, and stable ink ejection characteristics in the head (40) can be obtained.

Further, an example of 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. 5 has an apparatus main body (101), a paper feed tray (102) for loading paper mounted on the apparatus main body (101), and an image mounted on the apparatus main body (101). A paper discharge tray (103) for stocking the formed paper and an ink cartridge loading section (104) are provided.
On the upper surface of the ink cartridge loading section (104), an operation section (105) such as operation keys and a display is arranged. The ink cartridge loading section (104) has an openable / closable front cover (115) for attaching and detaching the ink cartridge (1 ′).

  In the apparatus main body (101), as shown in FIGS. 6 and 7, a guide rod (131), which is a guide member horizontally mounted on left and right side plates (not shown), and a stay (132) include a carriage ( 133) is slidably held in the main scanning direction, and is moved and scanned in the direction of the arrow in FIG. 7 by a main scanning motor (not shown).

The carriage (133) includes a recording head (134) including four inkjet recording heads that eject recording ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). Are arranged in a direction crossing the main scanning direction and the ink droplet discharge direction is directed downward.
As an inkjet recording head constituting the recording head (134), a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change caused by liquid film boiling using an electrothermal transducer such as a heating resistor, and a temperature change A shape memory alloy actuator using a metal phase change, an electrostatic actuator using an electrostatic force, or the like provided as an energy generating means for discharging recording ink can be used.
The carriage (133) is equipped with a sub tank (135) for each color for supplying ink of each color to the recording head (134). The sub-tank (135) is supplied with the recording ink of the present invention from the ink cartridge (1 ′) of the present invention loaded in the ink cartridge loading section (105) via a recording ink supply tube (not shown). To be replenished.

  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 feed tray (103), 1 sheet (142) is fed from the paper stacking unit (141). A half-moon roller (sheet feeding roller 143) that separates and feeds the sheets one by one and a separation pad (144) made of a material having a large friction coefficient are provided opposite to the sheet feeding roller (143). The roller (143) is urged.

  A conveying belt (151) for electrostatically adsorbing and conveying the paper (142) as a conveying unit for conveying the paper (142) fed from the paper feeding unit below the recording head (134). A counter roller (152) for conveying the paper (142) sent from the paper supply unit via the guide (145) between the conveying belt (151) and a paper (substantially vertically upward) ( 142) and a leading guide roller 153 urged toward the conveying belt (151) by the holding member (154). (155) and a charging roller (156) which is a charging means for charging the surface of the conveyor belt (151).

  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. On the back side of the conveyance belt (151), a guide member (161) is arranged corresponding to the 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), and paper discharge A roller (172) and a paper discharge roller (173) are provided, and a paper discharge tray (103) is arranged below the paper discharge roller (172).

  A double-sided paper feeding unit (181) is detachably attached to 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 double-sided paper feed unit (181).

In this ink jet recording apparatus, the sheet (142) is separated and fed one by one from the sheet feeding unit, and the sheet (142) fed substantially vertically upward is guided by the guide (145) and the transport belt (151). ) And the counter roller (152). Further, the leading end is guided by the conveying guide (153) and pressed against the conveying belt (151) by the leading end pressure roller (155), and the conveying direction is changed by about 90 °.
At this time, the conveyance belt (157) is charged by the charging roller (156), and the paper (142) is electrostatically adsorbed to the conveyance belt (151) and conveyed. Therefore, by driving the recording head (134) according to the image signal while moving the carriage (133), ink droplets are ejected onto the stopped sheet (142) to record one line, and the sheet ( 142), the next line is recorded after a predetermined amount is conveyed. Upon receiving a recording end signal or a signal that the rear end of the paper (142) has reached the recording area, the recording operation is finished and the paper (142) is discharged to the paper 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 to the sub tank (135) from the ink cartridge (1 ').

  In this ink jet recording apparatus, when the recording ink in the ink cartridge (1 ′) of the present invention is used up, the casing (3 ′) of the ink cartridge (1 ′) is disassembled to disassemble the ink bag (2 ′ inside). ) Can only be exchanged. Further, the ink cartridge (1 ') can be stably supplied with the recording ink even when the ink cartridge (1') is vertically placed and has a front loading configuration. Therefore, even when the upper part of the apparatus main body (101) is closed and installed, for example, even when it is stored in a rack or an object is placed on the upper surface of the apparatus main body (101), the ink The cartridge (1 ′) can be easily replaced.

  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.

Hereinafter, although an Example is shown, this invention is not limited to these.
Example 1 Ink Black Ink:
KM-9036 (Toyo Ink, self-dispersing pigment) 50% by weight
Glycerin 10% by weight
1,3-butanediol 15% by weight
2-ethyl-1,3-hexanediol 2% by weight
2-pyrrolidone 2% by weight
Surfactant (1-9) 1% by weight
Silicone defoamer KS508 (Shin-Etsu Chemical) 0.1% by weight
Residual amount of ion-exchanged water An ink composition having the above formulation was prepared and sufficiently stirred at room temperature, and then filtered through a membrane filter having an average pore size of 1.2 μm to obtain Example 1 ink. The viscosity (25 ° C.) of the ink was 7.6 mPa · s, and the average particle size of the colorant in the ink was 102 nm.

Example 2 Preparation of Ink Polymer Solution A A 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube and dropping funnel was sufficiently substituted with nitrogen gas, and then 11.2 g of styrene and acrylic acid 2 0.8 g, 12.0 g of lauryl methacrylate, 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, azobismethylvaleronitrile A mixed solution of 2.4 g and methyl ethyl ketone 18 g was dropped into the flask over 2.5 hours. After dropping, 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.
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 having a concentration of 50%.

Preparation of pigment-containing polymer fine particle aqueous dispersion Polymer solution A 28 g and C.I. I. 26 g of Pigment Yellow 97, 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 having an average particle size of 80 nm.
The particle size was measured by using a particle size distribution measuring device UPA150 manufactured by Microtrac Co., Ltd., diluted to a pigment concentration of 0.01%.

Yellow ink:
Yellow polymer fine particle dispersion 40% by weight
Glycerin 8% by weight
1,3-butanediol 20% by weight
2,2,4-Trimethyl-1,3-pentanediol 2% by weight
Surfactant (1-8) 1.5% by weight
Silicone defoamer KS508 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.1% by weight
Residual amount of ion-exchanged water An ink composition having the above formulation was prepared and sufficiently stirred at room temperature, followed by filtration through a membrane filter having an average pore size of 1.2 μm to obtain Example 2 ink. The viscosity (25 ° C.) of the ink was 7.8 mPa · s.

Example 3 Preparation of Ink Pigment-Containing Polymer Fine Particle Water Dispersion I. An aqueous dispersion of magenta polymer fine particles having an average particle diameter of 140 nm was obtained in the same manner except that the pigment red 122 was used.
Magenta ink:
Dispersion of magenta polymer fine particles 50% by weight
Glycerin 10% by weight
1,3-butanediol 18% by weight
2,2,4-Trimethyl-1,3-pentanediol 2% by weight
Surfactant (1-8) 1.5% by weight
Silicone defoamer KS508 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.1% by weight
Residual amount of ion-exchanged water An ink composition having the above formulation was prepared and sufficiently stirred at room temperature, and then filtered through a membrane filter having an average pore size of 1.2 μm to obtain Example 3 ink. The viscosity (25 ° C.) of the ink was 8.1 mPa · s.

Example 4 Preparation of Ink Pigment-Containing Polymer Fine Particle Water Dispersion I. An aqueous dispersion of cyan polymer fine particles having an average particle diameter of 110 nm was obtained in the same manner except that the pigment blue was changed to 15: 3.
Cyan ink:
Cyan polymer fine particle dispersion 40% by weight
Glycerin 8% by weight
1,3-butanediol 20% by weight
2,2,4-Trimethyl-1,3-pentanediol 2% by weight
Surfactant (1-8) 1.5% by weight
Silicone defoamer KS508 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.1% by weight
Residual amount of ion-exchanged water An ink composition having the above formulation was prepared and sufficiently stirred at room temperature, and then filtered through a membrane filter having an average pore size of 1.2 μm to obtain Example 4 ink. The viscosity (25 ° C.) of the ink was 7.9 mPa · s.

Next, the filter will be described.
The material of the filter is preferably stainless steel, and SUS 304 is generally used, but SUS 316 with higher corrosion resistance can also be used. As an example of producing a filter from these materials, a process of producing a mesh filter or the like from these stainless fibers through web production → vacuum sintering → rolling can be mentioned. These filters can manage the permeation performance by the item of bubble point pressure.

  Four types of filters were used for evaluation. Using these filters, the fluid resistance at 25 ° C. of the filters for each ink was measured under the conditions of 25 ° C. environment and water head pressure of 150 mmaq using the inks of Examples 1 to 4. The fluid resistance was calculated by flowing ink from each filter at a height of 150 mm and measuring the outflow time per ink weight (g). The bubble point pressure and fluid resistance of each filter are as shown below.

  Next, IPSiO G707 equipped with a head using filter A was used as printer A, IPSiO G707 equipped with a head using filter B was used as printer B, IPSiO G707 equipped with a head using filter C, and filter D was used. The IPSiO G707 equipped with the head was used as the printer D, and each of the inks of Examples 1 to 4 was filled, and the following evaluation (1) was performed.

Evaluation (1): Continuous printability evaluation 1
Continuous printability evaluation was performed in an environment of 23 ° C. and 45%. The first 1000 print patterns were printed in black and white as text patterns, and then 400 images including color graphic patterns were printed. No nozzle recovery operation (cleaning, etc.) was performed during that time, and a nozzle check pattern was printed before and after the evaluation to evaluate the number of nozzle down occurrences.
A nozzle down occurrence number of 0 was evaluated as ◎, a value of 5 or less as ◯, a value of 5 to less than 15 as Δ, and a value of 15 or more as x.
The evaluation results are shown below.

流体抵抗が大きいと、インク供給が追いつかず、ノズルダウン発生数が多くなる。また流体抵抗が小さくなりすぎると逆に異物の混入によりノズルダウンが発生することがわかった。

If the fluid resistance is large, the ink supply cannot catch up and the number of nozzle down occurrences increases. In addition, it was found that if the fluid resistance becomes too small, nozzle down occurs due to contamination of foreign matters.

Evaluation (2): Continuous printability evaluation 2
Continuous printability evaluation was performed in an environment of 10 ° C. and 15%. The first 1000 print patterns were printed in black and white as text patterns, and then 400 images including color graphic patterns were printed. During this period, a cleaning check sequence was used for every 150 sheets printed, and a nozzle check pattern was printed before and after the evaluation to evaluate the number of nozzle down occurrences.
A nozzle down occurrence number of 0 was evaluated as ◎, a value of 5 or less as ◯, a value of 5 to less than 15 as Δ, and a value of 15 or more as x.
The evaluation results are shown below.

低温環境下ではインクの粘度上昇に伴い、流体抵抗が大きくなるため、クリーニングを入れるシーケンスを用いても、評価（１）に比較してプリンタＡの結果は悪くなった。

In a low temperature environment, the fluid resistance increases as the viscosity of the ink increases, so that the result of the printer A was worse than that in the evaluation (1) even when the cleaning sequence was used.

Example 5 Ink Example 5 ink was prepared with the same ink formulation using a finer dispersion of the pigment of Example 3 and using an aqueous dispersion of magenta polymer fine particles having an average particle size of 90 nm. The viscosity (25 ° C.) of the ink was 8.1 mPa · s.

  Example 3 The ink of Example 5 was used instead of the ink, and the evaluations (1) and (2) were performed using the filters B and C (printers B and C). The results are shown in Table 5.

顔料の粒径が小さいインクを併用することで、より吐出安定性の高い記録装置が提供可能となった。

By using an ink having a small pigment particle size in combination, a recording apparatus with higher ejection stability can be provided.

Example 1 Ink Set Examples 1 to 4 were designated as Example 1 ink sets.

Comparative Example 1 Ink Set A Comparative Example 1 ink set was prepared in the same manner as in Example 1 except that the surfactant and penetrant were removed from the ink set.

Comparative Example 2 Ink Set A Comparative Example 2 ink set was prepared in the same manner as in Example 1 except that the penetrant was removed from the ink set.

Comparative Example 3 Ink Set A Comparative Example 3 ink set was prepared in the same manner as in Example 1 except that the surfactant was removed from the ink set.
The viscosity of the ink sets of Comparative Examples 1 to 3 is shown below.

Evaluation (4): Evaluation of printing quality Using the inks of Examples 1 to 4 as an example ink set and using the printer B, color images were printed in a mode in which the printing speed was the same level. The printed image was visually evaluated for character bleeding and color boundary bleeding. The evaluation paper was plain paper.
In the evaluation, ◎ indicates no bleeding, ○ indicates that there is almost no bleeding, Δ indicates that there is slight bleeding, and × indicates that bleeding is clear.

界面活性剤及び浸透剤を添加していないインクは文字滲み・色境界滲みともに大きい。
実施例１インクセットによれば、高画質の確保が容易に可能となる。

Ink to which surfactants and penetrants are not added is large in both character bleeding and color boundary bleeding.
According to the ink set of Example 1, it is possible to easily ensure high image quality.

Reference Example 1 ink Reference Example 1 ink was prepared in the same manner as in Example 4 except that the amount of glycerin was changed to 5% by weight and the amount of 1,3-butanediol was changed to 23% by weight. The viscosity (25 ° C.) of the ink was 8.2 mPa · s.

Reference Example 2 Ink was prepared in the same manner as in Example 4 except that the amount of glycerin was changed to 23% by weight and the amount of 1,3-butanediol was changed to 5% by weight. The viscosity (25 ° C.) of the ink was 6.8 mPa · s.

  Evaluation (4) was performed on the ink of Example 4 and Reference Examples 1 and 2, and the following results were obtained.

Comparative Example 4 Ink Black Ink:
KM-9036 (Toyo Ink, self-dispersing pigment) 30% by weight
Glycerin 5% by weight
Diethylene glycol 15% by weight
2-ethyl-1,3-hexanediol 2% by weight
2-pyrrolidone 2% by weight
Surfactant (1-9) 1% by weight
Silicone defoamer KS508 (Shin-Etsu Chemical) 0.1% by weight
Residual amount of ion-exchanged water An ink composition having the above formulation was prepared and sufficiently stirred at room temperature, followed by filtration through a membrane filter having an average pore size of 1.2 μm to obtain a comparative example 4 ink. The viscosity of the ink was 5.1 mPa · s. (Average particle size is 100 nm)

Comparative Example 5 Ink Black ink:
KM-9036 (Toyo Ink, self-dispersing pigment) 50% by weight
Glycerin 12% by weight
1,3 butanediol 30% by weight
2-ethyl-1,3-hexanediol 2% by weight
2-pyrrolidone 2% by weight
Surfactant (1-9) 1% by weight
Silicone defoamer KS508 (Shin-Etsu Chemical) 0.1% by weight
Residual amount of ion-exchanged water An ink composition having the above formulation was prepared and sufficiently stirred at room temperature, and then filtered through a membrane filter having an average pore size of 1.2 μm to obtain a comparative example 5 ink. The viscosity of the ink was 15.3 mPa · s. (Average particle size is 108 nm)
The results of evaluations (1) and (2) for these inks are shown.

これらのインクについて評価（４）を行なったところ、以下のようになった。

When these inks were evaluated (4), they were as follows.

Example 6 Ink Example 6 ink was prepared in the same manner as in Example 2 except that 0.5% of 2-amino-2-ethyl-1,3-propanediol was added. The viscosity (25 ° C.) of the ink was 8.2 mPa · s.

Example 7 Ink Example 7 ink was prepared in the same manner as in Example 4 except that 0.5% of 2-amino-2-ethyl-1,3-propanediol was added. The viscosity (25 ° C.) of the ink was 8.4 mPa · s.

  When the ink bleeding of the evaluation (4) was evaluated for the inks of Examples 6 to 7, all were at the same level as the ink to which no ink was added.

The following evaluation (5) was performed on the inks of Examples 2, 4, 6, and 7 and Reference Examples 1 and 2.
Evaluation (5): Intermittent printing test As an evaluation machine, an IJ printer IPSiO Jet 300 (nozzle diameter 31 μm) manufactured by Ricoh was used, and the carriage was scanned (empty scan) for 30 seconds without discharging for a certain period of time. The evaluation of printing 20 drops of all nozzles on a gloss film for IJ and then performing a recovery operation (50 drops of purge) was repeated 10 times.
The evaluation was made by taking an enlarged photograph of the dot ejection direction of the first drop during printing of 20 drops, and judging it visually. Judgment criteria were as shown below.
A: There is no disturbance in the ejection direction, and the dot size is normal, and the dots are aligned in a row. O: There is no disturbance in the ejection direction, and the dots are arranged in a row, but the dot size is slightly smaller. Disturbed, but the disturbance does not reach the second line ×: The first dot exceeds the line of the second dot XX: Not discharged

湿潤剤中のグリセリンの量が２０％未満だと、信頼性が悪くなり、また８０％を越えると文字滲みが発生する。また２−アミノ−２−エチル−１、３−プロパンジオールを添加することにより、更に吐出安定性が向上している。

If the amount of glycerin in the wetting agent is less than 20%, the reliability is deteriorated, and if it exceeds 80%, character bleeding occurs. Further, by adding 2-amino-2-ethyl-1,3-propanediol, the discharge stability is further improved.

Example 8 Ink First, a pigment dispersion was prepared by the method described below.
Yellow pigment dispersion C.I. I. Pigment Yellow 97 30% by weight
Polyoxyethylene oleyl ether ammonium sulfate 15% by weight
Ethylene glycol 30% by weight
Pure water remaining amount After mixing the above-mentioned components, dispersion was performed in a wet sand mill, and centrifugal treatment was performed to remove coarse particles to obtain a yellow pigment dispersion.

Yellow ink Yellow pigment dispersion 20% by weight
Glycerin 8% by weight
3-methyl-1,3-butanediol 25% by weight
2-ethyl-1,3-hexanediol 2% by weight
Surfactant (1-7) 2% by weight
Silicone defoamer KS531 (Shin-Etsu Chemical) 0.1% by weight
Residual amount of ion-exchanged water An ink composition having the above formulation was prepared and sufficiently stirred at room temperature, and then filtered through a membrane filter having an average pore diameter of 1.2 μm to obtain Example 8 ink. The ink viscosity (25 ° C.) was 6.6 mPa · s.

Example 9 Ink First, a pigment dispersion was prepared by the method described below.
Magenta pigment dispersion C.I. I. Pigment Red 122 30% by weight
Polyoxyethylene oleyl ether ammonium sulfate 15% by weight
Glycerin 30% by weight
Pure water remaining amount After mixing the above components, the mixture was dispersed by a three-roll mill and centrifuged to remove coarse particles to obtain a magenta pigment dispersion.

Magenta ink Magenta pigment dispersion 25% by weight
Glycerin 7% by weight
3-methyl-1,3-butanediol 23% by weight
2-ethyl-1,3-hexanediol 2% by weight
Surfactant (1-7) 1% by weight
Silicone defoamer KS531 (Shin-Etsu Chemical) 0.1% by weight
Residual amount of ion-exchanged water An ink composition having the above formulation was prepared and sufficiently stirred at room temperature, and then filtered through a membrane filter having an average pore diameter of 1.2 μm to obtain Example 9 ink. The viscosity (25 ° C.) of the ink was 6.8 mPa · s.

Example 10 Ink First, a pigment dispersion was prepared by the method described below.
Cyan pigment dispersion C.I. I. Pigment Blue 15: 3 30% by weight
Polyoxyethylene oleyl ether ammonium sulfate 15% by weight
Ethylene glycol 30% by weight
Pure water remaining amount After the above components were mixed, dispersion was performed with a wet sand mill, and centrifugal treatment was performed to remove coarse particles to obtain a cyan pigment dispersion.

Cyan ink Cyan pigment dispersion 15% by weight
Glycerin 10% by weight
3-methyl-1,3-butanediol 20% by weight
2-ethyl-1,3-hexanediol 2% by weight
Surfactant (1-7) 1% by weight
Silicone defoamer KS531 (Shin-Etsu Chemical) 0.1% by weight
Residual amount of ion-exchanged water An ink composition having the above formulation was prepared and sufficiently stirred at room temperature, and then filtered through a membrane filter having an average pore diameter of 1.2 μm to obtain Example 10 ink. The ink viscosity (25 ° C.) was 6.5 mPa · s.

Example 11 Ink First, a pigment dispersion was prepared by the method described below.
Self-dispersing cyan pigment dispersion C.I. I. 70 parts of sulfolane was added to 20 parts of Pigment Blue 15: 3, and the mixture was brought to 120 ° C. in an oil bath, and then 10 parts of sulfamic acid was added thereto for sulfonation for 5 hours. Thereafter, the mixture was cooled and centrifuged to remove coarse particles to obtain a self-dispersed cyan pigment dispersion.

Cyan ink 50% by weight of self-dispersing cyan pigment dispersion
Glycerin 8% by weight
1,3-butanediol 20% by weight
2,2,4-Trimethyl-1,3-pentanediol 2% by weight
Surfactant (1-7) 1% by weight
Silicone defoamer KS531 (Shin-Etsu Chemical) 0.1% by weight
Residual amount of ion-exchanged water An ink composition having the above formulation was prepared and sufficiently stirred at room temperature, and then filtered through a membrane filter having an average pore size of 1.2 μm to obtain Example 11 ink. The viscosity (25 ° C.) of the ink was 7.3 mPa · s.
When the evaluation (5) was performed on the inks of Examples 8 to 11, the following results were obtained.

自己分散型の顔料インクを用いることでより信頼性の高いインクを得ることが可能となった。

By using a self-dispersion type pigment ink, it becomes possible to obtain a more reliable ink.

It is an element enlarged view of an ink jet head to which the present invention is applied. It is a principal part expanded sectional view of the direction between channels of the inkjet head to which this invention is applied. It is a perspective exploded block diagram which shows an inkjet head part periphery structure. It is a perspective exploded view which shows the structural example of a subtank. It is a schematic explanatory drawing which shows an example of the inkjet recording device of this invention. It is a schematic explanatory drawing which shows an example of the internal structure of the inkjet recording device of FIG. It is a schematic plan view which shows the internal structure of the inkjet recording device of FIG.

Explanation of symbols

1 'ink cartridge 101 apparatus main body 102 paper supply tray 103 paper discharge tray 104 ink cartridge loading unit 111 upper cover 112 front surface 115 front cover 131 guide rod 132 stay 133 carriage 134 recording head 135 sub tank 141 paper placement unit 142 paper 143 paper supply Roller 144 Separation pad 145 Guide 151 Conveying belt 152 Counter roller 153 Conveying guide 154 Pressing member 155 Tip pressure roller 156 Charging roller 157 Conveying roller 158 Tension roller 161 Guide member 171 Separating claw 172 Discharging roller 173 Discharging roller 181 Double-sided sheet feeding Unit 182 Manual paper feed unit 1 Frame 1-2 Common liquid chamber 2 Flow path plate 2-1 Fluid resistance unit 2-2 Pressurized liquid chamber 2-3 Communication port 2-4 Bulkhead 3 Nozzle plate (vibration plate)
3-1 Nozzle 4 Base 5 Multilayer Piezoelectric Element 5-5 Common Electrode 5-6 Drive Unit (Moving Part)
5-7 Supporting part 6 Diaphragm 6-1 Island-like convex part 6-2 Diaphragm part 6-3 Ink inlet 7 Adhesive layer 8 FPC
DESCRIPTION OF SYMBOLS 10 Lever 13 Drive apparatus 20 Carriage 21 Atmospheric release pin 22 Negative pressure pin 23 Elastic member 30 Sub tank 31 Atmospheric release port 32 Negative pressure lever 33 Case 34 Film 35 Plate 36 Elastic member 37 Ink filling port 38 Full detection sensor 39a Top wall 39b Bottom Wall 39c Side wall 40 Inkjet head 50 Ink cartridge 51 Connecting tube 301, 302 Sub tank unit 311, 371 Elastic member 312, 372 Ball 313, 373 Elastic member 314, 374 Cap

Claims (14)

In an ink jet recording apparatus in which an ink composed of a colorant, a wetting agent, a surfactant, and a penetrating agent dispersed in water is ejected from a head including a filter as a constituent element, the viscosity of the ink at 25 ° C. is 6 to 13 mPa · s. An ink jet recording apparatus, wherein the fluid resistance of the filter to the ink is in a range of 4.4 × 10 ^{9 to} 2.2 × 10 ¹⁰ Pa · s / m ³ .   2. The ink jet recording apparatus according to claim 1, wherein the ink contains 3 to 15 wt% of a colorant and 10 to 40 wt% of a wetting agent.   The colorant is a pigment that is dispersible in water without a dispersant because the surface of the colorant is treated so that at least one hydrophilic group is bonded directly or via another atomic group. The ink jet recording apparatus according to claim 1, wherein:   4. The ink jet recording apparatus according to claim 1, wherein the colorant is a pigment dispersed with a surfactant and / or a polymer dispersant.   The ink jet recording apparatus according to any one of claims 1 to 4, wherein the colorant is a polymer emulsion in which polymer fine particles contain a water-insoluble or hardly soluble colorant.   The said wetting agent contains at least 1 sort (s) of the polyhydric alcohol whose equilibrium water content in temperature 20 degreeC and a relative humidity 60% environment is 25 wt% or more. Inkjet recording device.   The inkjet recording apparatus according to claim 6, wherein one of the polyhydric alcohols is glycerin, and a content of glycerin is 20 wt% or more and 80 wt% or less of the whole wetting agent.   The inkjet recording apparatus according to any one of claims 1 to 7, wherein the penetrant contains at least one polyol having a solubility in water at 20 ° C of 0.2 wt% or more and less than 5.0 wt%. .   The ink jet recording apparatus according to claim 8, wherein the polyol is 2-ethyl-1,3-hexanediol.   9. The ink jet recording apparatus according to claim 8, wherein the polyol is 2,2,4-trimethyl-1,3-pentanediol.   The ink jet recording apparatus according to any one of claims 1 to 10, wherein the ink further contains 2-amino-2-ethyl-1,3-propanediol.   12. A recording method using the ink jet recording apparatus according to claim 1, wherein a droplet discharged from a nozzle has a size of 3 to 40 pl, a droplet speed of 6 to 20 m / s, and a frequency of 1 KHz or more. An ink jet recording method, wherein the resolution is 300 dpi or more.   13. The ink jet recording method according to claim 12, wherein a plurality of ink droplets are continuously ejected and merged before landing on a recording medium to form large droplets. A head mounted on the recording apparatus includes a plurality of pressurized liquid chambers, nozzles having a hole diameter of 35 μm or less communicating with the pressurized liquid chambers and an ink supply path, electrical pressure converting means or electrothermal converting means for discharging ink, a filter, 12. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is a recording head including an ink tank that generates a negative pressure.

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