JP2010037460A - Water-based ink, inkjet recording method, ink cartridge, recording unit, and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide water-based ink improving ink charging properties to an ink absorbing body while maintaining previously designed ink performance. <P>SOLUTION: In use, the water-based ink is charged in an ink cartridge, wherein all the ink stored in the ink cartridge is held by capillary force of the ink absorbing body composed of polyolefin fibers. The water-based ink comprises at least a surfactant with an HLB value of 11-18 determined by the Griffin method, and an 8-12C monohydric alcohol in amount of 20-500 ppm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  As an ink cartridge mounted on an ink jet recording apparatus, an ink absorber is provided inside the ink cartridge, and the ink is held by a negative pressure generated by the ink absorber, thereby forming a stable meniscus on the nozzle of the recording head. There is something. As such an ink absorber that generates a negative pressure inside the ink cartridge, a foam or a fiber is often used.

  However, in general, a material having high hydrophobicity is often used as such an ink absorber from the viewpoint of moldability. When an ink cartridge having such an ink absorber is filled with ink, it takes a long time for the water-based ink to wet the ink absorber, and the ink absorber can absorb per unit time at the initial stage of filling. The amount of ink is not large. For this reason, when an ink cartridge is manufactured, it takes a long time to fill the ink.

  Therefore, there is a proposal related to devising a filling method in order to shorten the time required for ink filling. For example, there is a proposal related to filling the ink by depressurizing the inside of the ink cartridge (see Patent Document 1). In addition, there is a proposal relating to giving vibration to an ink cartridge after increasing the number of filling needles and filling the ink cartridge with ink (see Patent Document 2). Furthermore, there is a proposal related to processing the ink absorber to improve ink wettability (see Patent Document 3).

In addition to these, there is a proposal for improving ink filling properties by devising ink constituents (see Patent Document 4). Specifically, by adding a nonionic surfactant to the ink to lower the surface tension of the ink, the wettability to the ink absorber is improved, and the amount of ink absorbed by the ink absorber per unit time is increased. It is disclosed to do more.
Japanese Patent Laid-Open No. 11-216876 JP 2006-159656 A JP 2001-162824 A Japanese Patent Laid-Open No. 06-040044

  However, as in the inventions described in Patent Documents 1 and 2, the method of devising ink filling can achieve a certain filling speed, but it is necessary to prepare a filling device. It needs to be complicated. Further, as in the invention described in Patent Document 3, although a certain filling speed can be achieved by processing the ink absorber, the process of processing the ink absorber becomes complicated, and there are sufficient countermeasures. It was not.

  Furthermore, as in the invention described in Patent Document 4, a certain filling speed can also be achieved by devising the constituent components of the ink. However, among various physical properties of ink, the surface tension particularly affects various properties such as ink ejection performance, spreading after ink is applied to the recording medium, and ink penetration speed into the recording medium. This is a very important property. For this reason, the preferable range of the surface tension is often set for the ink depending on the use of the ink and the performance required for the ink. That is, depending on the performance required for the ink, the surface tension may not be set so low that the wettability to the ink absorber can be improved. That is, in such a case, the required ink performance and ink filling properties cannot be achieved at the same time.

  Accordingly, an object of the present invention is to provide a water-based ink capable of improving the ink filling property to the ink absorber while maintaining the ink performance designed in advance. Another object of the present invention is to provide an ink jet recording method, an ink cartridge, a recording unit, and an ink jet recording method using the water-based ink.

  The above object is achieved by the present invention described below. That is, the water-based ink according to the present invention is a water-based ink that is used by being filled in an ink cartridge that is held by the capillary force of an ink absorber composed of polyolefin fibers in which all the ink stored in the ink cartridge is, The water-based ink contains at least a surfactant having an HLB value of 11 or more and 18 or less determined by the Griffin method, and a monohydric alcohol having a carbon number of 8 or more and 12 or less, and the 1 in the ink The content (ppm) of the monohydric alcohol is 20 ppm or more and 500 ppm or less.

  An ink jet recording method according to another embodiment of the present invention is an ink jet recording method in which ink is ejected by an ink jet method to perform recording on a recording medium, and the ink having the above-described configuration is used as the ink. Features.

  An ink cartridge according to another embodiment of the present invention is an ink cartridge in which all of the ink accommodated in the ink cartridge is held by the capillary force of an ink absorber composed of polyolefin fibers, the ink cartridge The water-based ink contained in the ink contains at least a surfactant having an HLB value of 11 or more and 18 or less obtained by the Griffin method, and a monohydric alcohol having 8 to 12 carbon atoms, and the ink The content (ppm) of the monohydric alcohol is 20 ppm or more and 500 ppm or less.

  A recording unit according to another embodiment of the present invention is a recording unit including an ink cartridge for containing ink and a recording head for discharging ink, and the ink has the above-described configuration. A water-based ink is used.

  An ink jet recording apparatus according to another embodiment of the present invention is an ink jet recording apparatus including an ink cartridge for containing ink and a recording head for ejecting ink. A water-based ink having a constitution is used.

  ADVANTAGE OF THE INVENTION According to this invention, the aqueous ink which can improve the filling property of the ink to an ink absorber can be provided, maintaining the ink performance designed beforehand. According to another embodiment of the present invention, an ink jet recording method, an ink cartridge, a recording unit, and an ink jet recording method using the water-based ink can be provided.

  Hereinafter, the present invention will be described in more detail with reference to the best mode for carrying out the invention. In the following description, water-based ink may be referred to as “ink”.

  First, the relationship between the characteristics of the surface tension of the ink required for satisfying the performance as an ink and the filling property of the ink into the ink absorber will be described. An ink having a surface tension of less than 30 mN / m designed based on the required ink performance originally has a good filling property to the ink absorber. However, since the surface tension of the ink is low, the capillary force generated in the ink absorber composed of polyolefin fibers is weak. For this reason, ink leakage from the ejection opening of the recording head may occur due to the influence of vibration during distribution or impact when the ink cartridge is mounted on the ink jet recording apparatus.

  On the other hand, an ink having a surface tension of 30 mN / m or more designed based on the required ink performance may be inferior in filling properties to the ink absorber. By using the ink of the present invention having the configuration described below as such an ink, the ink filling property can be improved while satisfying the performance as an ink. Furthermore, since the surface tension of the ink quickly returns to the designed surface tension, ink leakage due to the influence of vibration during distribution or impact when the ink cartridge is mounted on the ink jet recording apparatus is unlikely to occur.

  The ink of the present invention that can solve the above-mentioned problems is one in which all the ink contained in the ink cartridge is held by the capillary force of the ink absorber composed of polyolefin fibers. It has the following features. That is, the ink of the present invention contains a surfactant having an HLB value of 11 or more and 18 or less obtained by the Griffin method and a monohydric alcohol having 8 to 12 carbon atoms in a range of 20 ppm to 500 ppm. It is characterized by that. The reason why the above problems are solved by using the ink having such a configuration, and the ink filling property to the ink absorber can be improved while maintaining the ink performance designed in advance is as follows. I guess so.

  By using monohydric alcohol having high hydrophobicity as a component constituting the ink, the surface tension of the ink can be lowered, and the ink filling property is improved. Here, the monohydric alcohol having high hydrophobicity is slightly less soluble in an aqueous medium such as water constituting the ink. However, when a surfactant is further used as a component constituting the ink, the alcohol is taken into micelles formed in the aqueous medium by the surfactant. By such a mechanism, even a monohydric alcohol having high hydrophobicity can be dissolved in an aqueous medium such as water constituting the ink. Then, when an ink absorber composed of polyolefin fibers is filled with the ink having such a configuration, the monohydric alcohol taken in the micelles of the surfactant is transferred to the highly hydrophobic ink absorber, Adsorb to the ink absorber. The transfer of the monohydric alcohol from the micelle to the ink absorber is completed quickly, so that the surface tension of the ink designed based on the ink performance required for the surface tension of the ink that has been reduced by the addition of the monohydric alcohol is obtained. It will be in the state which has a characteristic. As a result, when ink is used, performance as a predesigned ink can be obtained.

  As a result of the study by the present inventors, in order to obtain the above characteristics, it is necessary to make the following constitution of the ink containing the monohydric alcohol having high hydrophobicity and the surfactant. The headline and the present invention were made. As the surfactant, it is necessary to use a surfactant having an HLB value of 11 or more and 18 or less determined by the Griffin method. Further, as the monohydric alcohol, those having 8 to 12 carbon atoms are used, and the content of the alcohol in the ink needs to be 20 ppm to 500 ppm.

  The ink whose surface tension is reduced by containing the above-mentioned alcohol has a difference from the surface tension of the ink designed before adding the alcohol at the time of using the ink of 2 mN / m or less, more preferably 1 mN / m. The following is preferable. When the surface tension of the ink satisfies such a configuration, the ink performance designed in advance can be sufficiently obtained.

  Further, it is preferable that the above-described alcohol transfer to the ink absorber is sufficiently performed from the production of the ink cartridge to the use of the ink cartridge. Considering the situation from the preparation of the ink cartridge to its use, it is preferable that the transfer of the alcohol to the ink absorber is completed within at least about 14 days, more preferably within about 3 days. .

<Ink>
The ink of the present invention is one in which all the ink contained in the ink cartridge is held by the capillary force of the ink absorber composed of polyolefin fibers, and has the following compositional characteristics. That is, the ink of the present invention contains a surfactant having an HLB value of 11 or more and 18 or less obtained by the Griffin method and a monohydric alcohol having 8 to 12 carbon atoms in a range of 20 ppm to 500 ppm. It is essential. Other than that, it can be set as the structure similar to a general water-based ink. Hereinafter, each component and physical property which comprise the ink of this invention are demonstrated.

(Surfactant whose HLB value calculated | required by the Griffin method is 11-18)
The ink of the present invention has an HLB value determined by the Griffin method in order to dissolve a monohydric alcohol having a high hydrophobicity because it has 8 to 12 carbon atoms in an aqueous medium such as water constituting the ink. However, it is necessary to use a surfactant of 11 to 18 inclusive. The content (% by mass) of the surfactant in the ink is 0.1% by mass or more and 5.0% by mass or less, and further 0.1% by mass or more and 4.0% by mass or less based on the total mass of the ink. Preferably there is.

  Here, the Griffin method will be described. The HLB value by the Griffin method can be obtained from the following formula (1) from the formula weight and molecular weight of the hydrophilic group of the surfactant. The HLB value by the Griffin method indicates the degree of hydrophilicity or lipophilicity of the surfactant, and takes a value of 0 to 20. The lower the HLB value, the higher the lipophilicity or hydrophobicity of the surfactant. Conversely, the higher the HLB value, the higher the hydrophilicity of the surfactant.

  If the HLB value of the surfactant is less than 11, the surfactant is highly hydrophobic, so that the surfactant is solubilized by incorporating the monohydric alcohol into micelles formed in the aqueous medium. The effect of the present invention cannot be obtained. On the other hand, when the HLB value of the surfactant exceeds 18, the hydrophilicity of the surfactant is high, so that a hydrophobic interaction becomes difficult to work between the monohydric alcohol used together and the surfactant. As a result, it becomes difficult for the surfactant to take in the monohydric alcohol into the micelle formed in the aqueous medium, the alcohol cannot be solubilized, and the effects of the present invention cannot be obtained.

  As the surfactant that can be used in the ink of the present invention, any surfactant may be used as long as the HLB value by the Griffin method is 11 or more and 18 or less, and it is nonionic, anionic, or cationic. And amphoteric surfactants.

  Examples of nonionic surfactants include the following. Polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, polyoxyethylene alkyl phenyl ether, fatty acid diethanolamide, polyoxyethylene / polyoxypropylene block copolymer, acetylene glycol surfactant, and the like. Examples of the anionic surfactant include the following. Polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl ether sulfonate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene alkyl phenyl ether sulfonate, and the like. Alpha sulfo fatty acid ester salts, alkyl benzene sulfonates, alkyl phenol sulfonates, alkyl naphthalene sulfonates, alkyl tetralin sulfonates, dialkyl sulfosuccinates and the like. Examples of the cationic surfactant include alkyltrimethylammonium salt and dialkyldimethylammonium chloride. Examples of amphoteric surfactants include alkylcarboxybetaines.

  In the present invention, among the above surfactants, polyoxyethylene alkyl ether is preferably used, and polyoxyethylene alkyl ether which is an ethylene oxide adduct of alcohol is particularly preferably used. Such a surfactant can effectively incorporate monohydric alcohol into micelles formed by the surfactant in an aqueous medium, and the ink of monohydric alcohol when the ink absorber is filled with ink. This is particularly suitable because it does not hinder the transition to the absorber.

  Moreover, it is particularly preferable that the alkyl group in the polyoxyethylene alkyl ether has 8 to 20 carbon atoms. The monohydric alcohol can be particularly effectively taken into the micelle formed by the surfactant in the aqueous medium, and the transition of the monohydric alcohol to the ink absorber when the ink is filled in the ink absorber is quick. It is because it can be made to do. On the other hand, when the number of carbon atoms is less than 8, the hydrophobicity of the surfactant is lowered, and thus it is difficult to cause a hydrophobic interaction with a highly hydrophobic monohydric alcohol. Therefore, in order to dissolve monohydric alcohol having high hydrophobicity, it is necessary to greatly increase the content of the surfactant, which may cause restrictions in ink design. Further, when the number of carbon atoms exceeds 20, the hydrophobicity of the surfactant increases, so that it becomes easy for the surfactant to incorporate monovalent alcohol having high hydrophobicity into the micelles formed in the aqueous medium. Easy to make. However, in this case, since the hydrophobic interaction between the monohydric alcohol and the surfactant works strongly, it may hinder the rapid transfer of the alcohol to the ink absorber. Therefore, it may take a long time for the monohydric alcohol to move to the ink absorber.

  Furthermore, it is particularly preferable that the monovalent alcohol and the alkyl group of the polyoxyethylene alkyl ether have the same carbon number. This is because, since these carbon numbers are the same, the affinity for each other is particularly high, so that the monovalent alcohol can be particularly efficiently incorporated into the micelles that the surfactant forms in the aqueous medium. It is because the effect | action which dissolves can be acquired notably.

(Monohydric alcohol having 8 to 12 carbon atoms)
The ink of the present invention contains a monohydric alcohol having 8 to 12 carbon atoms, and its content (ppm) needs to be 20 ppm to 500 ppm.

  When the alcohol has less than 8 carbon atoms, the monohydric alcohol has a low hydrophobicity, so that a hydrophobic interaction between the alcohol and the ink absorber is less likely to occur. For this reason, since it takes a long time for the monohydric alcohol to move to the ink absorber, the surface tension of the ink does not sufficiently return to the previously designed value, and the designed ink performance cannot be obtained. If the alcohol has more than 12 carbon atoms, the monohydric alcohol has high hydrophobicity, so that the solubility in the aqueous medium constituting the ink is remarkably reduced no matter what surfactant is used in combination. Therefore, it is difficult to obtain an ink having an alcohol content sufficient to reduce the surface tension of the ink to such an extent that the ink filling property is improved.

  Further, when the alcohol content is less than 20 ppm, even when the alcohol is contained in the ink, the change in the surface tension of the ink is small, and the ink filling property is not improved. On the other hand, when the content of the alcohol exceeds 500 ppm, the surface tension of the ink is lowered and the ink filling property is improved. However, in this case, since it takes a long time for the alcohol to move to the ink absorber, the surface tension of the ink does not sufficiently return to the previously designed value, and the designed ink performance cannot be obtained.

  Examples of the monohydric alcohol having 8 to 12 carbon atoms that can be used in the ink of the present invention include octanol, nonanol, decanol, undecanol, and dodecanol. In the present invention, an alcohol having a hydroxyl group at the end of the carbon chain is preferably used. In addition, if the carbon chain of the alcohol is branched, it is difficult for the surfactant to be incorporated into micelles formed in the aqueous medium due to the influence of steric hindrance. Is preferred.

(Aqueous medium)
The ink of the present invention preferably contains an aqueous medium containing water and a water-soluble organic solvent in addition to the specific surfactant and monovalent alcohol mentioned above. As water, it is preferable to use deionized water (ion exchange water). The content (% by mass) of water in the ink is preferably 30.0% by mass or more and 90.0% by mass or less based on the total mass of the ink. The content (% by mass) of the water-soluble organic solvent in the ink is preferably 3.0% by mass or more and less than 50.0% by mass based on the total mass of the ink. In addition, the range of suitable content of the said water-soluble organic solvent is a value containing the monohydric alcohol whose above-mentioned carbon number is 8-12. When these contents are in the above range, the ink has a viscosity suitable for stable ejection, and clogging at the ejection port of the recording head can be easily suppressed.

  Specific examples of the water-soluble organic solvent include those listed below. Alcohols having 1 to 6 carbon atoms such as ethanol, isopropanol, 2-propanol, n-butanol, isobutanol, butanol, pentanol and hexanol. Carboxylic acid amides such as N, N-dimethylformamide and N, N-dimethylacetamide. Ketones such as acetone, methyl ethyl ketone, and 2-methyl-2-hydroxypentan-4-one; Cyclic ethers such as keto alcohol, tetrahydrofuran and dioxane. Polyhydric alcohols such as glycerin, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2- or 1,3-propylene glycol, 1,2- or 1,4-butylene glycol, and polyethylene glycol. 1,3-butanediol, 1,2- or 1,5-pentanediol, 1,2- or 1,6-hexanediol, dithioglycol, 2-methyl-1,3-propanediol, 1,2,6 -Polyhydric alcohols such as hexanetriol. Alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monoethyl (or butyl) ether. Heterocycles such as 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-methylmorpholine. Sulfur-containing compounds such as dimethyl sulfoxide. Among these, it is particularly preferable to use glycerin, diethylene glycol, 2-pyrrolidone and the like.

(Coloring material)
The color material used in the ink of the present invention is not particularly limited as long as it can be used as a color material for water-based ink. For example, a pigment or a water-soluble dye can be used. The content (% by mass) of the color material in the ink is 0.1% by mass or more and 15.0% by mass or less, and further 1.0% by mass or more and 10.0% by mass or less based on the total mass of the ink. It is preferable.

[Pigment]
Examples of the pigment that can be used in the ink of the present invention include carbon black and organic pigments.

<Carbon black>
Examples of the pigment used for the color material of the black ink include carbon black. Examples of the carbon black include carbon black such as furnace black, lamp black, acetylene black, and channel black, magnetic fine particles such as magnetite and ferrite, and titanium black. Specifically, commercially available products such as those listed below can be used.

  Ray Van: 1170, 1190 ULTRA-II, 1200, 1255, 1250, 1500, 2000, 3500, 5000, 5250, 5750, 7000, etc. (made in Colombia). Black Pearls L, Legal: 330R, 400R, 660R, Mogul L, Monak: 700, 800, 880, 900, 1000, 1100, 1300, 1400, Vulcan XC-72R, etc. (manufactured by Cabot). Color Black: FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex: 35, U, V, 140U, 140V, Special Black: 4, 4A, 5, 6 etc. (manufactured by Degussa). No. 25, no. 33, no. 40, no. 47, no. 52, no. 900, no. 2300, MCF-88, MA7, MA8, MA100, MA600, etc. (manufactured by Mitsubishi Chemical).

[Organic pigments]
Examples of the pigment used for the color material of the color ink include organic pigments. As the organic pigment, specifically, the following can be used.

  Water-insoluble azo pigments such as Toluidine Red, Toluidine Maroon, Hansa Yellow, Benzidine Yellow, and Pyrazolone Red. Water-soluble azo pigments such as Ritolol Red, Helio Bordeaux, Pigment Scarlet, and Permanent Red 2B. Derivatives from vat dyes such as alizarin, indanthrone and thioindigo maroon. Phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green. Quinacridone pigments such as quinacridone red and quinacridone magenta. Perylene pigments such as perylene red and perylene scarlet. Isoindolinone pigments such as isoindolinone yellow and isoindolinone orange. Imidazolone pigments such as benzimidazolone yellow, benzimidazolone orange, and benzimidazolone red. Pilanthrone pigments such as pyranthrone red and pyranthrone orange. Indigo pigment. Condensed azo pigment. Thioindigo pigment. Flavanthrone yellow, acylamide yellow, quinophthalone yellow, nickel azo yellow, copper azomethine yellow, perinone orange, anthrone orange, dianthraquinonyl red, dioxazine violet, etc.

  Moreover, when an organic pigment is shown by a color index (CI) number, specifically, the following can be used.

  C. I. Pigment Yellow: 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 109, 110, 117, 120, 125, 128, 137, 138, 147, 148, 151, 153, 154, 166 168 etc. C. I. Pigment Orange: 16, 36, 43, 51, 55, 59, 61, etc. C. I. Pigment Red: 9, 48, 49, 52, 53, 57, 97, 122, 123, 149, 168, 175, 176, 177, 180, 192, 215, 216, 217, 220, 223, 224, 226, 227 228, 238, 240, etc. C. I. Pigment violet: 19, 23, 29, 30, 37, 40, 50, and the like. C. I. Pigment Blue: 15, 15: 3, 15: 1, 15: 4, 15: 6, 22, 60, 64, and the like. C. I. Pigment Green: 7, 36, etc. C. I. Pigment Brown: 23, 25, 26, etc.

(Pigment dispersion method)
The dispersion method for dispersing the pigment as mentioned above in the aqueous medium may be any method. For example, a resin-dispersed pigment that disperses the pigment using a resin dispersant or a pigment that disperses the pigment using a surfactant can be used. In addition, it is possible to use a pigment that enhances the dispersibility of the pigment itself and can be dispersed in an aqueous medium without using a dispersant or the like. For example, microcapsule-type pigments, self-dispersed pigments having hydrophilic groups introduced on the surface of pigment particles, polymer-bonded self-dispersing pigments in which organic groups containing polymers are chemically bonded to the surface of pigment particles, etc. Can be used. Of course, these pigments having different dispersion methods can also be used in combination.

(Self-dispersing pigment)
As the self-dispersing pigment, one in which at least one hydrophilic group is chemically bonded to the surface of the pigment particle directly or through another atomic group (-R-) can be used. By using such a self-dispersing pigment, it is not necessary to add a dispersant for dispersing the pigment in the ink, or the amount of the dispersant added can be reduced.

The hydrophilic group bonded to the surface of the pigment particle, specifically, for _{example, -COOM, -SO 3 M, -PO} 3 HM 2, -PO 3 M 2, - mentioned _{(COOM) n} and It is done. In the formula, M is a hydrogen atom, alkali metal, ammonium, or organic ammonium, and n is an integer of 2 or more. Examples of the other atomic group (—R—) include an alkylene group having 1 to 12 carbon atoms, a substituted or unsubstituted phenylene group, and a substituted or unsubstituted naphthylene group. In addition, the form of the hydrophilic group in the ink may be any form of a partly dissociated state or a completely dissociated state. In the present invention, it is particularly preferable to use a self-dispersing pigment obtained by a diazo coupling method in which a compound having a structure of the above-mentioned —R— (COOM ₁ ) _n group in part is bonded to the surface. it can.

  In addition, it can be obtained by a method of oxidizing with sodium hypochlorite, a method of oxidizing with ozone treatment in water, a method of modifying the surface of pigment particles by wet oxidation with an oxidizing agent after ozone treatment, A self-dispersing pigment of the surface oxidation treatment type can also be used.

[Polymer-bonded self-dispersing pigment]
In the present invention, it is possible to use a polymer-bonded self-dispersing pigment that enhances the dispersibility of the pigment itself and is dispersible in an aqueous medium without using a dispersant or the like. This polymer-bonded self-dispersing pigment is a copolymer having a functional group chemically bonded to the surface of pigment particles directly or via another atomic group, and an ionic monomer and a hydrophobic monomer. It is preferable that it contains a reaction product with a coalescence. Since the pigment having such a structure can appropriately change the copolymerization ratio of the ionic unit and the hydrophobic unit constituting the copolymer used for modifying the surface of the pigment particle, the hydrophilicity of the pigment The sex can be adjusted arbitrarily. Furthermore, since the kind of the ionic unit and the hydrophobic unit constituting the copolymer and the combination of these units can be arbitrarily selected, various characteristics can be imparted to the surface of the pigment particle.

(Resin dispersion type pigment)
As the resin-dispersed pigment, a pigment in which a pigment is dispersed using a resin dispersant capable of dispersing the pigment by the action of an ionic group such as an anionic group can be used. The weight average molecular weight of the resin used as the dispersant is preferably 1,000 or more and 30,000 or less, more preferably 3,000 or more and 15,000 or less. Examples of the dispersant include the following.

  Styrene-acrylic acid copolymer, styrene-acrylic acid-alkyl acrylate copolymer, styrene-maleic acid copolymer, styrene-maleic acid-alkyl acrylate copolymer, and the like. Styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer and the like. Styrene-maleic acid half ester copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, styrene-maleic anhydride-maleic acid half ester copolymer, and the like. Benzyl methacrylate-methacrylic acid copolymer and the like. Or the salt of these copolymers.

(Water-soluble dye)
As the water-soluble dye, a water-soluble dye such as a direct dye, an acid dye, a reactive dye, and a basic dye can be used. Examples of such water-soluble dyes include dyes described in the color index. Moreover, even if it is a dye which is not described in a color index, if it has water solubility, it can be used. Specific examples of water-soluble dyes that can be used in the ink of the present invention are shown below by color index (CI) numbers.

[Yellow dye]
C. I. Direct yellow: 8, 11, 12, 27, 28, 33, 39, 44, 50, 58, 85, 86, 87, 88, 89, 98, 100, 110, 132, etc. C. I. Acid Yellow: 1, 3, 7, 11, 17, 23, 25, 29, 36, 38, 40, 42, 44, 76, 98, 99, etc. C. I. Reactive yellow: 2, 3, 17, 25, 37, 4 etc. C. I. Food yellow: 3 etc.

[Magenta dye]
C. I. Direct Red: 2, 4, 9, 11, 20, 23, 24, 31, 39, 46, 62, 75, 79, 80, 83, 89, 95, 197, 201, 218, 220, 224, 225, 226 227, 228, 229, 230, etc. C. I. Acid Red: 6, 8, 9, 13, 14, 18, 26, 27, 32, 35, 42, 51, 52, 80, 83, 87, 89, 92, 106, 114, 115, 133, 134, 145 158, 198, 249, 265, 289, etc. C. I. Food Red: 87, 92, 94, etc. C. I. Direct violet 107 and the like.

[Cyan dye]
C. I. Direct blue: 1, 15, 22, 25, 41, 76, 77, 80, 86, 90, 98, 106, 108, 120, 158, 163, 168, 199, 226, 307, etc. C. I. Acid Blue: 1, 7, 9, 15, 22, 23, 25, 29, 40, 43, 59, 62, 74, 78, 80, 90, 100, 102, 104, 112, 117, 127, 138, 158 161, 203, 204, 221, 244, etc.

[Black dye]
C. I. Direct black: 17, 19, 22, 31, 32, 51, 62, 71, 74, 112, 113, 154, 168, 195, etc. C. I. Acid Black: 2, 48, 51, 52, 110, 115, 156, etc. C. I. Food black: 1, 2, etc.

(Other ingredients)
In addition to the above-described components, the ink of the present invention includes water-soluble organic compounds that are solid at room temperature, such as polyhydric alcohols such as trimethylolpropane and trimethylolethane, and urea derivatives such as urea and ethyleneurea, as necessary. A compound may be contained. Furthermore, the ink of the present invention may contain various additives as necessary as long as the effects of the present invention are not impaired. Examples of such additives include pH adjusters, rust inhibitors, antiseptics, antifungal agents, antioxidants, reduction inhibitors, evaporation accelerators, chelating agents, and water-soluble polymers.

(Ink physical properties)
The ink of the present invention preferably has a surface tension at room temperature (25 ° C.) of 25 mN / m or more. If the surface tension is less than 25 mN / m, ink wettability to the ink absorber composed of polyolefin fibers increases, so the ink actively moves against vibrations and reduced pressure during distribution, etc. Etc. may occur. The upper limit of the surface tension of the ink at normal temperature (25 ° C.) is preferably 50 mN / m or less.

<Inkjet recording method>
The ink of the present invention is used in the ink jet recording method of the present invention including a step of recording on a recording medium by ejecting the ink by an ink jet method. Ink jet recording methods include a method of ejecting ink by applying mechanical energy to the ink and a method of ejecting ink by applying thermal energy to the ink. In particular, in the present invention, an ink jet recording method using thermal energy can be preferably used.

<Ink cartridge, recording unit>
Next, an ink cartridge and a recording unit that contain the ink of the present invention will be described. In the ink of the present invention, the effect of the present invention can be obtained by bringing the ink into contact with an ink absorber composed of polyolefin fibers and transferring the monohydric alcohol in the ink to the ink absorber. Therefore, it is a precondition for obtaining the effect of the present invention to use an ink cartridge in a form in which all the ink contained in the ink cartridge is held by the capillary force of the ink absorber composed of polyolefin fibers. . That is, the ink cartridge for containing the ink of the present invention needs to be in a state in which the ink is not held by the ink absorber, that is, the ink cartridge does not have an ink containing chamber for containing ink as a liquid state. It is. Specifically, an ink cartridge having the following form is preferable.

  First, an ink cartridge having no recording head will be described with reference to FIG. FIG. 1 is a cross-sectional view showing an example of the structure of an ink cartridge. The ink cartridge 21 has a housing 22, a lid member 23 that covers the housing 22 and has the atmosphere communication port 25, and an atmosphere opening port 38 at a position different from the atmosphere communication port 25. In addition, a first space 36 is provided which is attached to the upper part of the lid member 23 and functions as a buffer chamber for preventing ink from the atmosphere communication port 25 from leaking outside the ink cartridge 21. Further, the ink cartridge 21 is provided with an upper member 24, which includes a recording head, and is attached to and detached from a head cartridge (not shown) mounted on the carriage 102 of the ink jet recording apparatus (see FIG. 7). A knob 24a used at the time is provided.

  At the bottom of the ink cartridge 21, a supply port 28 into which a lead-out tube (not shown) of the head cartridge is inserted, a rib 35 provided so as to protrude from the periphery thereof, an inclined portion 34a that connects the supply port 28 and the rib 35, and 34b is provided. The rib 32 is used as a guide when the ink cartridge 21 is mounted on a head cartridge (not shown).

  An ink absorber 26 is accommodated inside the ink cartridge 21, and an ink outlet member 27 is provided between the ink absorber 26 and the supply port 28. A support portion 29 for supporting the ink lead-out member 27 inside the ink cartridge 21 is provided corresponding to the supply port 28. A slit (not shown) that connects the inside and the outside of the ink cartridge 21 is provided on a part of the inner surface of the support portion 29.

  The lid member 23 is provided with ribs 33 so as to form a plurality of second spaces 37 between the ink absorber 26 and the lid member 23, and a belt-like convex portion 23 a is provided on the front side of the lid member 23. Is provided. The belt-like convex portion 23a engages with a member (not shown) provided on the head cartridge, and applies a force in a direction from the upper side to the lower side of the ink cartridge 21 to thereby reduce the head cartridge ( (Not shown) can be stably mounted. A combination of an ink cartridge having no recording head and a head cartridge can be used as a recording unit. Further, a plurality of ribs 31 that are continuous in the vertical direction are provided on the inner side surface of the ink cartridge 21, and a space (not shown) is formed between the side surface of the ink cartridge 21 and the ink absorber 26.

  Next, an ink cartridge (recording unit) in which the recording head is integrated will be described with reference to FIGS. FIG. 2 is an exploded perspective view showing an example of the structure of the first ink cartridge in which the recording head is integrated, and FIG. 3 is a first recording element provided in the first ink cartridge shown in FIG. It is a perspective view shown in the state where a substrate was partially fractured. FIG. 4 is a perspective view showing an example of the structure of the second ink cartridge in which the recording head is integrated, and FIG. 5 is an exploded perspective view showing an example of the structure of the second ink cartridge in FIG. . Further, FIG. 6 is a perspective view showing the second recording element substrate provided in the second ink cartridge shown in FIGS. 4 and 5 in a partially broken state.

  The first ink cartridge H1000 in FIG. 2 contains black ink, and the second ink cartridge H1001 in FIGS. 4 and 5 contains color inks (cyan, magenta, and yellow inks), respectively. The types of these inks are not limited to the above-described hues, and can be appropriately set to inks of other hues, so-called dark inks, and light inks. The ink cartridges H1000 and H1001 are supported and fixed by positioning means and electrical contacts of a carriage mounted on the ink jet recording apparatus, and are detachable from the carriage. When the inks stored in the ink cartridges H1000 and H1001 are consumed, the ink cartridges H1000 and H1001 can be replaced independently. Hereinafter, each element constituting the ink cartridge of these forms will be described in more detail.

  The first ink cartridge H1000 and the second ink cartridge H1001 are integrated with a thermal recording head using an electrothermal transducer that generates thermal energy for causing ink to cause film boiling according to an electric signal. It is configured. As such a recording head, it is particularly preferable to use a so-called side shooter type recording head in which the electrothermal transducer and the discharge port are arranged to face each other.

(1) First ink cartridge The first ink cartridge H1000 is used as an ink cartridge for storing black ink. As shown in FIG. 2, the first ink cartridge H1000 includes a first recording element substrate H1100, an electric wiring tape H1300, an ink supply holding member H1500, a filter H1700, an ink absorber H1600, a lid member H1900, and a seal member H1800. Have.

(1-1) First Recording Element Substrate As shown in FIG. 3, the first recording element substrate H1100 is a Si crystal in which an ink supply port H1102 that is a long groove-like through-hole is formed in the Si substrate H1110 as an ink channel. It is formed by a method such as anisotropic etching or sandblasting using orientation. The thickness of the Si substrate H1110 is preferably 0.5 to 1 mm, for example.

  On both sides of the ink supply port H1102, electrothermal conversion elements H1103 are arranged in a line, and electric wiring (not shown) made of Al or the like for supplying electric power to these electrothermal conversion elements H1103. ) And are formed. The electrothermal conversion element H1103 and electric wiring (not shown) are formed by a film forming technique. The electrothermal conversion elements H1103 in each row are arranged in a staggered manner, that is, slightly shifted so that the positions of the ejection ports H1107 in each row are not aligned in the direction orthogonal to the row direction. Furthermore, electrode portions H1104 for supplying electric power to an electric wiring (not shown) or supplying an electric signal for driving the electrothermal conversion element H1103 are provided on both sides of the electrothermal conversion element H1103. Are arranged along. A bump H1105 made of Au or the like is formed on the electrode portion H1104. A plate formed of a cured product of epoxy resin or the like is formed with a group of ejection ports H1108 in which a large number of ejection ports H1107 are opened, and each ejection port H1107 has an ink channel partitioned by a channel wall H1106. Ink is supplied from.

(1-2) Electric Wiring Tape The first electric wiring tape H1300 forms an electric signal path for applying an electric signal for ejecting ink to the first recording element substrate H1100. An opening for incorporating the first recording element substrate H1100 is formed in the first electrical wiring tape H1300, and connected to the electrode portion H1104 of the first recording element substrate H1100 near the edge of the opening. An electrode terminal H1304 is formed. The first electric wiring tape H1300 has an external signal input terminal H1302 for receiving an electric signal from the ink jet recording apparatus. The electrode terminal H1304 and the external signal input terminal H1302 are made of a continuous copper foil. Connected with wiring pattern.

  The electrical connection between the first electrical wiring tape H1300 and the first recording element substrate H1100 is, for example, as follows. That is, the bump H1105 formed on the electrode portion H1104 of the first recording element substrate H1100 and the electrode terminal H1304 of the first electric wiring tape H1300 corresponding to the electrode portion H1104 of the first recording element substrate H1100 are electrically joined. Is done. The electrical bonding between the bump H1105 and the electrode terminal H1304 can be performed by a thermal ultrasonic pressure bonding method or the like.

(1-3) Ink Supply Holding Member The ink supply holding member H1500 is formed of a resin or the like, and it is preferable to use a material mixed with about 5 to 40% glass filler in order to improve rigidity. As shown in FIG. 2, the ink supply holding member H1500 has an ink absorber H1600 that generates a negative pressure for holding the ink therein, thereby containing ink. Further, by using a compressed polyolefin fiber, preferably polypropylene fiber, as the ink absorber H1600, the ink is held by the negative pressure generated by the capillary force of the ink. Further, the ink supply holding member H1500 has an ink flow path for guiding the ink contained in the ink absorber H1600 to the first recording element substrate H1100, thereby supplying the ink to the first recording element substrate H1100. To do. A filter H1700 (see FIG. 2) for preventing dust from entering the inside of the first recording element substrate H1100 is joined to the boundary with the ink absorber H1600 upstream of the ink flow path by welding. The filter H1700 may be a SUS metal mesh type, but is preferably a SUS metal fiber sintered type.

  As shown in FIG. 2, an ink supply opening H1200 for supplying ink to the first recording element substrate H1100 is formed downstream of the ink flow path. The first recording element substrate H1100 is connected to the ink supply holding member H1500 so that the ink supply port H1102 (see FIG. 3) of the first recording element substrate H1100 communicates with the ink supply opening H1200 of the ink supply holding member H1500. Bonded and fixed with high positional accuracy.

  On the plane around the ink supply opening H1200 of the first recording element substrate H1100, the surface facing the ink supply holding member H1500 of the electric wiring tape H1300 is bonded and fixed. The electrical connection portion between the first recording element substrate H1100 and the electrical wiring tape H1300 is sealed with a first sealant H1307 and a second sealant H1308 (see FIG. 4), and the electrical connection portion is corroded by ink. And protects against external impacts. The first sealant H1307 mainly includes a back side of a connection portion between the electrode terminal H1302 of the electric wiring tape H1300 and the bump H1105 of the first recording element substrate H1100, and an outer peripheral portion H1303 of the first recording element substrate H1100. And are sealed. The 2nd sealing agent H1308 seals the front side of the above-mentioned connection part. The non-bonded portion of the electric wiring tape H1300 is bent and fixed to the side surface of the ink supply holding member H1500 that is substantially orthogonal to the surface having the ink supply opening H1200 by heat caulking or bonding.

(1-4) Lid Member The lid member H1900 seals the inside of the ink supply holding member H1500 by being welded to the upper opening of the ink supply holding member H1500. However, the lid member H1900 has a narrow opening H1910 for releasing pressure fluctuations in the space inside the ink supply holding member H1500 and a fine groove H1920 communicating with the narrow opening H1910. Most of the narrow opening H1910 and the fine groove H1920 are covered with a seal member H1800, and an end of the fine groove H1920 is opened to form an air communication opening. The lid member H1900 has an engaging portion H1930 for fixing the first ink cartridge H1000 to the ink jet recording apparatus.

(2) Second Ink Cartridge The second ink cartridge H1001 is used as an ink cartridge that contains three types of ink, cyan, magenta, and yellow. As shown in FIG. 5, the second ink cartridge H1001 includes a second recording element substrate H1101, an electric wiring tape H1301, an ink supply holding member H1501, filters H1701, H1702, and H1703. The second ink cartridge H1001 further includes ink absorbers H1601, H1602, and H1603, a lid member H1901, and a seal member H1801. Hereinafter, the configuration of the second ink cartridge will be described focusing on the configuration different from the first ink cartridge described above.

(2-1) Second Recording Element Substrate As shown in FIG. 6, the second recording element substrate H1101 is formed in parallel with three ink supply ports H1102 for cyan, magenta, and yellow on the Si substrate H1110. Has been. On both sides of each ink supply port H1102, the electrothermal conversion elements H1103 and the ejection ports H1107 are arranged in a staggered pattern one by one. Similar to the first recording element substrate H1100, the second recording element substrate H1101 has electrical wiring (not shown), electrode portions H1104, and the like, and bumps H1105 are formed on the electrode portions H1104. Yes. Further, a discharge port group H1108 in which a large number of discharge ports H1107 are opened is formed on the plate, and ink is supplied to each discharge port H1107 from an ink flow path partitioned by a flow path wall H1106.

(2-2) Electric Wiring Tape The second electric wiring tape H1301 forms an electric signal path for applying an electric signal for discharging each ink to the second recording element substrate H1101. An opening for incorporating the second recording element substrate H1101 is formed in the second electric wiring tape H1301, and connected to the electrode portion H1104 of the second recording element substrate H1101 near the edge of the opening. An electrode terminal H1304 is formed. The second electrical wiring tape H1301 is formed with an external signal input terminal H1302 for receiving an electrical signal from the ink jet recording apparatus. The electrode terminal H1304 and the external signal input terminal H1302 are made of a continuous copper foil. Connected with wiring pattern.

  For example, the electrical connection between the second electrical wiring tape H1301 and the second recording element substrate H1101 is made as follows. That is, the bump H1105 formed on the electrode portion H1104 of the second recording element substrate H1101 and the electrode terminal H1304 of the second electric wiring tape H1301 corresponding to the electrode portion H1104 of the second recording element substrate H1101 are electrically joined. Is done.

(2-3) Ink Supply Holding Member The ink supply holding member H1501 is formed of resin or the like, like the first ink cartridge H1000. As shown in FIG. 5, the ink supply holding member H1501 includes ink absorbers H1601, H1602, and H1603 that generate negative pressures for holding cyan, magenta, and yellow inks, respectively. Ink is accommodated by having. Ink absorbers H1601, H1602, and H1603 are made by compressing polyolefin fibers, preferably polypropylene fibers, so that the ink is held by the negative pressure generated by the capillary force of the ink. Further, the ink supply holding member H1501 has independent ink flow paths for guiding the inks stored in the ink absorbers H1601, H1602, and H1603 to the second recording element substrate H1101, respectively. Is supplied to the recording element substrate H1101. Filters H1701, H1702, and H1703 for preventing dust from entering the inside of the second recording element substrate H1101 at the boundaries with the ink absorbers H1601, H1602, and H1603 upstream of each ink flow path (FIG. 5) are joined by welding. Each of the filters H1701, H1702, and H1703 may be a SUS metal mesh type, but is more preferably a SUS metal fiber sintered type.

  As shown in FIG. 5, an ink supply opening H1201 for supplying cyan, magenta, and yellow ink to the second recording element substrate H1101 is formed downstream of the ink flow path. The second recording element substrate H1101 is connected to the ink supply holding member H1501 so that each ink supply port H1102 (see FIG. 6) of the second recording element substrate H1101 communicates with each ink supply opening H1201 of the ink supply holding member H1501. On the other hand, it is bonded and fixed with high positional accuracy.

  The surface facing the ink supply holding member H1501 of the electric wiring tape H1301 is bonded and fixed to the plane around the ink supply opening H1201 of the second recording element substrate H1101. The electrical connection portion between the second recording element substrate H1101 and the electrical wiring tape H1301 is sealed with a first sealant H1307 and a second sealant H1308 (see FIG. 4), and the electrical connection portion is corroded by ink. And protects against external impacts. The first sealant H1307 mainly includes the back side of the connection portion between the electrode terminal H1302 of the electric wiring tape H1300 and the bump H1105 of the second recording element substrate H1101, and the outer peripheral portion H1303 of the second recording element substrate H1101. And are sealed. The 2nd sealing agent H1308 seals the front side of the above-mentioned connection part. The non-bonded portion of the electric wiring tape H1301 is bent and fixed to the side surface of the ink supply holding member H1501 that is substantially orthogonal to the surface having the ink supply opening H1201 by heat caulking or bonding.

(2-4) Lid Member The lid member H1901 is welded to the upper opening of the ink supply holding member H1501, thereby sealing each independent space inside the ink supply holding member H1501. However, the lid member H1901 has narrow openings H1911, H1912, and H1913 for releasing pressure fluctuations in the spaces inside the ink supply holding member H1501, and fine grooves H1921, H1922, and H1923 that communicate with these narrow holes. The other ends of the fine grooves H1921 and H1922 join in the middle of the fine groove H1923. The narrow holes H1911, H1912, and H1913 and the fine grooves H1921, H1922, and H1923 are almost covered with a seal member H1801, and the other end of the fine groove H1923 is opened to form an air communication port. The lid member H1901 has an engaging portion H1930 for fixing the second ink cartridge H1001 to the ink jet recording apparatus.

(3) Mounting of ink cartridge to ink jet recording apparatus As shown in FIGS. 2 and 4, the first ink cartridge H1000 and the second ink cartridge H1001 are mounted on the carriage 102 (see FIG. 7) of the ink jet recording apparatus. A mounting guide H1560 for guiding the position is provided. Furthermore, each of the first and second ink cartridges H1000 and H1001 includes an engaging portion H1930 for mounting and fixing to the carriage 102 by a head set lever (not shown) of the ink jet recording apparatus. As shown in FIG. 4, each of the first and second ink cartridges H1000 and H1001 has an X-direction abutting portion H1570, a Y-direction abutting portion H1580, Z for positioning the carriage 102 at a predetermined mounting position. A direction abutting portion H1590 is provided. The X direction corresponds to the scanning direction (main scanning direction) of the carriage 102, the Y direction corresponds to the conveyance direction of the recording medium (sub scanning direction), and the Z direction corresponds to the direction in which ink is ejected. By positioning by these abutting portions, the external signal input terminals H1302 on the electrical wiring tapes H1300 and H1301 accurately come into contact with contact pins (not shown) of electrical connection portions provided on the carriage 102, and electrical Connection.

<Inkjet recording apparatus and inkjet recording method>
Next, an ink jet recording apparatus capable of mounting the ink cartridge as described above and an ink jet recording method that can be performed using the ink jet recording apparatus will be described with reference to FIG. FIG. 7 is a schematic diagram for explaining an example of the structure of the ink jet recording apparatus.

  In the ink jet recording apparatus, the head cartridge having the ink cartridge shown in FIG. 1 and the first and second ink cartridges H1000 and H1001 shown in FIGS. 2 and 4 are positioned on the carriage 102 and can be replaced. Installed. Hereinafter, the ink cartridge having the form shown in FIGS. 2 and 4 will be described as an example. The carriage 102 is provided with an electrical connection portion (not shown) for transmitting a drive signal and the like to the recording element substrates H1100 and H1101 via the external signal input terminals H1302 of the first and second ink cartridges H1000 and H1001. It has been.

  The carriage 102 is guided and supported so as to be able to reciprocate along a guide shaft 103 installed in the inkjet recording apparatus so as to extend in the main scanning direction. The carriage 102 is driven by a main scanning motor 104 via a driving mechanism such as a motor pulley 105, a driven pulley 106, and a timing belt 107, and its position and movement are controlled. Further, the position of the shielding plate 136 can be known when the home position sensor 130 provided on the carriage 102 passes the home position sensor 130 on the carriage 102.

  A recording medium 108 such as a printing paper or a plastic thin plate is separated and fed one by one from the auto sheet feeder 132 by rotating a pickup roller 131 from a paper feed motor 135 via a gear. Thereafter, the recording medium 108 is conveyed in the sub-scanning direction through the position (recording unit) facing the surfaces of the first and second ink cartridges H1000 and H1001 having the discharge ports by the rotation of the conveying roller 109. The conveyance of the recording medium 108 by the conveyance roller 109 is performed via a gear by the rotation of the LF motor 134. At this time, determination as to whether or not the recording medium 108 has been fed and determination of the cueing position of the recording medium 108 at the time of feeding is performed when the recording medium 108 passes through the paper end sensor 133. Further, the paper end sensor 133 is used to determine the current recording position from the rear end where the rear end of the recording medium 108 is located.

  The back surface of the recording medium 108 is supported by a platen (not shown) so as to form a flat recording surface in the recording unit. In this case, the first and second ink cartridges H1000 and H1001 mounted on the carriage 102 have their discharge ports projecting downward from the carriage 102 and parallel to the recording medium 108 between the pair of conveyance rollers. Is held to be. The first and second ink cartridges H1000 and H1001 are arranged so that the arrangement direction of the ejection port groups H1108 on the first and second recording element substrates is a direction intersecting the scanning direction of the carriage 102. 102. Then, ink is ejected from the ejection port groups H1108 of the first and second ink cartridges H1000 and H1001, and recording is performed on the recording medium.

  EXAMPLES Next, although an Example, a comparative example, and a reference example are given and this invention is demonstrated further more concretely, unless the summary is exceeded, this invention is not limited by the following Example. In the following description, “parts” and “%” are based on mass unless otherwise specified.

<Structure of surfactant>
Table 1 summarizes the properties of the surfactants used in preparing the ink. As the surfactants A to I, those synthesized by a conventional method were used. Table 1 shows the HLB value and structure of each surfactant, and when the surfactant is polyoxyethylene alkyl ether, the number of added moles of ethylene oxide group, the number of carbon atoms of the alkyl group, and the alkyl The name of the group is also shown.

<Preparation of pigment dispersion>
To a solution prepared by dissolving 5 g of concentrated hydrochloric acid in 5.5 g of water, 1.55 g of p-aminobenzoic acid was added while being cooled to 5 ° C. Next, the container containing the solution was placed in an ice bath and the solution was stirred to keep the solution constantly at 10 ° C. or lower, and 1.8 g of sodium nitrite was dissolved in 9 g of water at 5 ° C. The solution was added. After stirring this solution for another 15 minutes, 6 g of carbon black having a specific surface area of 220 m ² / g and a DBP oil absorption of 105 mL / 100 g was added with stirring. Thereafter, the mixture was further stirred for 15 minutes. The obtained slurry was filtered with a filter paper (trade name: Standard filter paper No. 2; manufactured by Advantech), and then the particles were sufficiently washed with water and dried in an oven at 110 ° C. to prepare self-dispersing carbon black. Furthermore, water was added to the self-dispersing carbon black obtained above to disperse the pigment concentration to 10% by mass, thereby preparing a dispersion. By the above method, the self-dispersing carbon black is -C ₆ H ₄ -COONa groups to the carbon black particle surface has been introduced (Pigment) was obtained a pigment dispersion in a state of being dispersed in water.

The ionic group density of the self-dispersing carbon black obtained above was 2.6 μmol / m ² . The ionic group density is determined by measuring the sodium ion concentration in the pigment dispersion prepared above using an ion meter (manufactured by DKK), and converting that value to the ionic group density of self-dispersing carbon black. Asked.

<Preparation of ink>
Each component shown to Table 2-1 to 2-3 was mixed and fully stirred. Thereafter, the ink containing the pigment is subjected to pressure filtration with a micro filter (manufactured by Fuji Film) having a pore size of 3.0 μm, and the ink containing the dye is subjected to pressure filtration with a micro filter having a pore size of 0.2 μm (manufactured by Fuji Film). An ink was prepared.

<Evaluation>
(surface tension)
The surface tension of each ink obtained above was measured using a surface tension meter CBVP-A3 (manufactured by Kyowa Interface Science) equipped with a 10 mm × 24 mm platinum plate under the condition of a temperature of 25.0 ° C. ± 0.5 ° C. It was measured. This surface tension value is used as the initial surface tension value of the ink. The evaluation results are shown in Table 4.

(Ink fillability of ink absorber)
After 0.03 g of each ink obtained above is dropped on the surface of a fiber absorber laminated and compressed with polypropylene fibers, ink droplets are absorbed by the fiber absorber and there are no ink droplets on the surface. The time until was measured. The fiber absorber used was the same as that of the FIN cartridge BC-70 black ink absorber for the ink jet recording apparatus PIXUS iP2200 (manufactured by Canon Inc.), and was not filled with ink. From the time required for the ink droplets to disappear from the surface of the fiber absorber measured in this way, the ink filling property into the ink absorber was evaluated. The evaluation criteria for the ink filling properties of the ink absorber are as follows. The evaluation results are shown in Table 4. In the following evaluation criteria, B or higher was an acceptable level for ink filling into the ink absorber, A was an excellent level, and AA was a particularly excellent level.
AA: Time required for ink droplets to disappear from the surface of the fiber absorber was less than 20 seconds A: Time required for ink droplets to disappear from the surface of the fiber absorber was 20 seconds or more and less than 30 seconds B: Time required for ink droplets to disappear from the surface of the fiber absorber was 30 seconds or more and less than 40 seconds C: Time required for ink droplets to disappear from the surface of the fiber absorber It was over 40 seconds.

(Change in ink surface tension)
Three pieces of each of the inks obtained by laminating and compressing polypropylene fibers and filled with 10 g of each of the inks obtained above were prepared for each ink, and the fiber absorbers were placed in a sealed container for 3 to 14 days. And for 2 months. The fiber absorber used was the same as that of the FIN cartridge BC-70 black ink absorber for the ink jet recording apparatus PIXUS iP2200 (manufactured by Canon Inc.), and was not filled with ink. After a predetermined period (3 days, 14 days, or 2 months) had elapsed, the fiber absorber was taken out from the sealed container, and the ink filled in the fiber absorber was collected. A surface tension meter CBVP-A3 (manufactured by Kyowa Interface Science) equipped with a 10 mm × 24 mm platinum plate under the conditions of a temperature of 25.0 ° C. ± 0.5 ° C. was used for the surface tension of each ink thus obtained. And measured. The surface tension values were taken as the surface tension values of the ink after 3 days, 14 days, and 2 months, respectively. From these values, the values of Δγ _{3 days} and Δγ _{14 days} were determined based on the following formulas, The change in the surface tension of the ink was evaluated. The evaluation criteria for the change in the surface tension of the ink are as follows. The evaluation results are shown in Table 4. The smaller the Δγ _{3 day} or Δγ _{14 day} , the faster the monohydric alcohol is transferred to the ink absorber, and the surface tension characteristic is designed based on the ink performance that requires the ink surface tension. . In the following evaluation criteria, B or higher was an acceptable level for the performance of the change in the surface tension of the ink. Table 4 also shows the value of the surface tension after 2 months.
Δγ _{3 days} = (Ink surface tension after 2 months) − (Ink surface tension after 3 days)
Δγ _{14 days} = (surface tension of ink after 2 months) − (surface tension of ink after 14 days).
AA: Δγ _{3 days} was 1 mN / m or less A: Δγ _{3 days} exceeded ₁ mN / m, Δγ _{14 days} was 1 mN / m or less B: Δγ _{3 days} exceeded ₁ mN / m However, Δγ _{14 days} exceeded 1 mN / m and was 2 mN / m or less. C: Δγ _{3 days} exceeded ₁ mN / m, and Δγ _{14 days} exceeded 2 mN / m.

  As in Reference Example 1, depending on the performance required for the ink, there may be a case where both the required ink performance and the ink filling property can be achieved without applying the present invention. However, even in such a case, as is apparent from Example 11, the ink filling property can be further improved by adding a small amount of alcohol to the ink. In the ink of Comparative Example 7, the surfactant was not dissolved but separated from the surface of the ink, so that the surface tension of the ink was lowered, but the ink filling property was inferior. .

It is sectional drawing which shows an example of the structure of an ink cartridge. FIG. 3 is an exploded perspective view illustrating an example of a structure of a first ink cartridge in a form in which a recording head is integrated. FIG. 3 is a perspective view showing the first recording element substrate provided in the first ink cartridge shown in FIG. 2 in a partially broken state. It is a perspective view showing an example of the structure of the 2nd ink cartridge of the form with which the recording head was united. FIG. 5 is an exploded perspective view illustrating an example of a structure of a second ink cartridge in FIG. 4. FIG. 6 is a perspective view showing the second recording element substrate provided in the second ink cartridge shown in FIGS. 4 and 5 in a partially broken state. It is the schematic for demonstrating an example of the structure of an inkjet recording device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 21 Ink cartridge 22 Housing 23 Lid member 23a Band-shaped convex part 24 Upper member 24a Knob part 25 Atmospheric communication port 26 Ink absorber 27 Ink outlet member 28 Supply port 29 Support part 31 Rib 32 Rib 33 Rib 34a, 34b Inclined part 35 Rib 36 First space 37 Second space 38 Air release port H1000 First ink cartridge H1001 Second ink cartridge H1100 First recording element substrate H1101 Second recording element substrate H1102 Ink supply port H1103 Electrothermal conversion element H1104 Electrode Portion H1105 Bump H1106 Flow path wall H1107 Discharge port H1108 Discharge port group H1110 Si substrate H1200 Ink supply opening H1201 Ink supply opening H1300 First electric wiring tape H1301 Electric wiring tape H130 2 External signal input terminal H1303 Outer peripheral part H1304 Electrode terminal H1307 First sealant H1308 Second sealant H1500 Ink supply holding member H1501 Ink supply holding member H1560 Mounting guide H1570 X-direction abutment H1580 Y-direction thrust Abutting portion H1590 Abutting portion in the Z direction H1600 Ink absorber H1601, H1602, H1603 Ink absorber H1700 Filter H1701, H1702, H1703 Filter H1800 Seal member H1801 Seal member H1900 Lid member H1901 Lid member H1910 Narrow mouth H1911, H1912, H1913 Narrow H19 Fine groove H1921, H1922, H1923 Fine groove H1930 Engagement part 102 Carriage 103 Guide shaft 104 Main scan Over motor 105 Motaburi 106 driven Buri 107 timing belt 108 recording medium 109 transport rollers 130 home position sensor 131 pickup roller 132 auto sheet feeder 133 paper end sensor 134 LF motor 135 feed motor 136 shield

Claims (8)

A water-based ink that is used by being filled in an ink cartridge in which all the ink contained in the ink cartridge is held by the capillary force of an ink absorber composed of polyolefin fibers,
The water-based ink contains at least a surfactant having an HLB value of 11 or more and 18 or less determined by the Griffin method, and a monohydric alcohol having 8 to 12 carbon atoms,
The water-based ink, wherein a content (ppm) of the monohydric alcohol in the ink is 20 ppm or more and 500 ppm or less.   The water-based ink according to claim 1, wherein the surfactant is polyoxyethylene alkyl ether.   The water-based ink according to claim 2, wherein the alkyl group of the polyoxyethylene alkyl ether has 8 to 20 carbon atoms.   The water-based ink according to claim 2 or 3, wherein the carbon number of the alcohol is the same as the carbon number of the alkyl group of the polyoxyethylene alkyl ether.   An ink jet recording method for performing recording on a recording medium by ejecting ink by an ink jet method, wherein the water-based ink according to claim 1 is used as the ink. . An ink cartridge in which all ink contained in the ink cartridge is held by the capillary force of an ink absorber composed of polyolefin fibers,
The aqueous ink contained in the ink cartridge contains at least a surfactant having an HLB value of 11 or more and 18 or less determined by the Griffin method, and a monohydric alcohol having 8 to 12 carbon atoms, The ink cartridge is characterized in that the content (ppm) of the monohydric alcohol in the ink is 20 ppm or more and 500 ppm or less.   A recording unit comprising an ink cartridge for containing ink and a recording head for discharging ink, wherein the water-based ink according to any one of claims 1 to 4 is used as the ink. A recording unit characterized by.   An ink jet recording apparatus comprising an ink cartridge for containing ink and a recording head for ejecting ink, wherein the water-based ink according to any one of claims 1 to 4 is used as the ink. An ink jet recording apparatus.

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