JP2005187783A - Water-based ink, method and apparatus for ink jet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-based ink suitably used for recording heads discharging the ink by heat energy and containing pigments having good optical resistance as colorants in addition to good preservability for a long time. <P>SOLUTION: The water-based ink using a self dispersion type pigment having hydrophilic groups contains a compound expressed by general formula (I):B-X-A (I) (in general formula (I), A expresses one group selected from a group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group and their salts; B expresses an amide group; X expresses an alkylene group or a cyclic compound group). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a water-based ink for ink-jet recording, an ink-jet recording method using the same, and various devices and apparatuses for ink-jet recording, and is suitably used for a recording head having an electric heat exchanging portion for ink ejection. The present invention relates to an aqueous ink excellent in storage stability and reliability, an ink jet recording method using the same, and various devices and apparatuses for ink jet recording.

  Conventionally, inks for writing instruments (fountain pens, sign pens, water-based ballpoint pens) and inks for ink jet recording have been reported in various compositions. In particular, with regard to ink robustness, detailed research and development has been conducted on pigment inks from various aspects in order to respond to strong demand from the market. In particular, unlike a pigment dispersion method such as dispersion by adding a conventional resin or dispersion by adding a surfactant, a method for imparting a dispersing power to a pigment itself by introducing a hydrophilic group is a conventional pigment dispersion type. It has attracted a great deal of attention as an improvement in reliability such as storage stability and anti-sticking property, which has been a problem of such inks.

Further, regarding an ink using a self-dispersing pigment, Japanese Patent Application Laid-Open No. 8-3498 improves the storage stability by increasing the amount of surface active hydrogen to a certain level or more, and discloses US Pat. No. 5,571,311. JP-A-8-286938 describes that a hydrophilic group is imparted to a pigment by a diazotization reaction, and that a counter ion of the hydrophilic group is selected.
JP-A-8-3498 US Pat. No. 5,571,311 JP-A-8-286938

  However, conventional inks containing self-dispersing pigments may still be insufficient for various environmental changes and long-term storage. As a result of further investigations, the present inventors have confirmed that an improvement effect is observed in long-term storage, frequency response at the time of ink jet recording, and prevention of contamination of the recording head, etc. by improving the employed pigment and aqueous composition. I found.

  An object of the present invention is to provide a water-based ink that is suitable for use in a recording head that ejects ink by thermal energy in addition to long-term storage and contains a pigment as a colorant that is also excellent in light resistance. is there. Another object of the present invention is to provide an ink jet recording method using such an aqueous ink. Another object of the present invention is to provide a recording unit, an ink cartridge, and an ink jet recording apparatus using such water-based ink.

The present invention includes the following aspects.
(1) An ink that is in contact with a surface layer containing a metal of an electric heat exchanging portion that imparts thermal energy to the ink,
A pigment having self-dispersibility in water by having a hydrophilic group as a coloring material;
A liquid medium for dispersing the pigment;
Formula (I):
BX-A (I)
(In the above general formula (I), A represents one group selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, and salts thereof; B represents an amino group or an amide group; Represents an alkylene group or a cyclic compound group.)
A compound represented by
A water-based ink characterized by comprising:
(2) In an ink jet recording method in which ink is ejected from an ejection port of a recording head in accordance with a recording signal and recording is performed on a recording material, the surface layer in contact with the ink provided in the recording head is used for the above water-based ink An ink jet recording method comprising: discharging from the discharge port by heating from a metal electrothermal conversion section having a liquid crystal.
(3) In a recording unit including an ink containing portion that contains ink and a recording head that ejects ink, the ink is the water-based ink, and the recording head ejects ink from an ejection port. A recording unit comprising: an electrothermal conversion section for applying thermal energy, wherein the electrothermal conversion section includes a metal and has a surface layer in contact with ink.
(4) An ink cartridge comprising an ink containing portion containing ink, wherein the ink is the water-based ink described above.
(5) An ink jet recording apparatus provided with a recording unit, wherein the recording unit is a recording unit having the above configuration.
(6) In an inkjet recording apparatus including a recording head for ejecting ink, an ink cartridge having an ink storage portion for storing ink, and an ink supply portion for supplying ink from the ink cartridge to the recording head.
The ink cartridge is an ink cartridge having the above-described configuration, and the recording head includes an electrothermal conversion unit that applies thermal energy to the recording head to be ejected from an ejection port. An ink jet recording apparatus comprising a surface layer containing metal and in contact with ink.

  Providing a water-based ink suitable for use in a recording head that ejects ink by thermal energy in addition to long-term storage, and having good light resistance, an ink jet recording method using this water-based ink, and various devices and apparatuses It becomes possible to do.

  Hereinafter, the present invention will be described in detail with reference to embodiments of the present invention. The water-based ink of the present invention comprises a pigment having a hydrophilic group as a coloring material and capable of being dispersed in water with its own dispersion force, a liquid medium in which the pigment is dispersed, and the compound represented by the general formula (I) And at least. The inference will be described below with respect to the effect of the structure of the water-based ink. The alkylene group of the general formula (I) is CnH2n (n represents an integer of 1 to 3), and the cyclic compound is

A water-based ink is preferred.

  The pigment having a hydrophilic group particularly employed in the water-based ink of the present invention can be dispersed in water by a hydrophilic basic force in the same manner as the dye. However, unlike dyes, pigment particles vary in size, and the attractive force and attractive force between pigments become non-uniform, and as a result, they tend to aggregate. In the water-based ink of the present invention, by further forming a salt of the compound represented by the general formula (I) on the hydrophilic group of the pigment, for example, in the case of improving the dispersibility of the resin, the pigments are close to each other. It is possible to create a steric hindrance that is not too much. In other words, it is predicted that aggregation is prevented by creating a hydrophilic group-like steric hindrance-like film at the tip of the hydrophilic group.

  As the compound represented by the general formula (I), the hydrophilic group of the pigment particle may be anionic or cationic. In the case of anionic, by forming a salt with the cationic group portion of the compound of the general formula (I), the outside of the sterically hindered membrane-like one becomes anionic, and when the pigment particles are hydrophilic in the cationic group, A salt is formed with the anionic portion of the compound of the general formula (I) and the outside of the sterically hindered membrane-like substance becomes cationic, so that the polarity of the hydrophilic group of the pigment particle is not changed.

  As described above, the pH of the ink is preferably in the range of 4 to 10 so that the hydrophilic group of the pigment and the compound of the general formula (I) can easily form a salt. However, the pH may be adjusted depending on the type of hydrophilic group of the pigment.

  The self-dispersing pigment as the coloring material used in the water-based ink of the present invention means a pigment that can be dispersed in water only by the hydrophilicity of the hydrophilic group of the pigment. As such a hydrophilic group, at least one selected from the group consisting of a cationic group such as a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, salts thereof, and an amino group can be used. Among these, in consideration of the reliability of the ink, it is preferable to use a group selected from a sulfonic acid group, a carboxylic acid group and a salt thereof, and an amino group. Among these, in view of safety and the like, at least one selected from sulfonic acid groups, carboxylic acid groups, and salts thereof is preferable.

  Examples of the salt in the hydrophilic group include salts with metal ions such as potassium ion, sodium ion and lithium ion, ammonia and amine. Among these, it is particularly preferable in terms of reliability to have ammonia or amine as at least one of salt forms.

  Examples of a method for imparting water dispersibility by hydrophilizing the pigment include hypohalites such as sodium hypochlorite and sodium hypobromite as disclosed in JP-A-46-52950. It is preferable to carry out the reaction in a quantitative range using an oxidizing agent such as 10 to 30 ° C. for a time of about 6 to 24 hours and an effective halogen concentration of 10 to 30% by mass with respect to the mass of the pigment. . A product obtained by this reaction is formed into a cake or the like by a method such as sedimentation, centrifugation, or filter press, and then washed with an organic solvent to remove impurities. US Pat. No. 5,200,184 and US Pat. No. 5,554,739 As disclosed in the specification, a method using a diazotization reaction or the like can be used, but the method for producing the pigment used in the present invention is not limited to these methods.

  The pigment employed in the present invention may be organic or inorganic, but the average particle size is preferably 200 nm or less, and more preferably 100 nm or less from the viewpoint of dispersion stability. In consideration of the density of the recorded matter on the recording material, the average particle size is preferably 30 nm or more, particularly 50 nm or more. The average particle diameter in this case is a value obtained by determining the particle state by the light scattering method in an infinite dilution state. Specifically, it may be employed when using a laser light diffusion type particle size distribution analyzer.

  The compound represented by the general formula (I) used in the present invention is used in combination with a pigment or a liquid medium in which the pigment is dispersed, but is expected to exist in a state like a pigment and a salt in an aqueous ink. A powder in which the pigment and the compound of the general formula (I) coexist may be used as a color material and dispersed in a liquid medium in which the powder is dispersed. However, since the pigment is an aggregate and the amount of the hydrophilic group is different for each pigment particle, it is preferable to produce a water-based ink by coexistence.

  Specific examples of the compound represented by the general formula (I) used in the present invention include, but are not limited to, taurine, alanine, glycine and the like. Moreover, as a compound represented by general formula (I), you may exist in the state of a salt, As a salt, metal ions, such as Li ion and Na ion, ammonia, an organic amine, etc. are mentioned.

  In addition, if the hydrophilic group of the pigment is in a salt state, the cationic group of the compound represented by the general formula (I) is the pigment even if the compound represented by the general formula (I) is used in the acid state. There is no problem because the salt is made further with the ions released by making the salt, and even if the compound represented by the general formula (I) forms a pigment and a salt, even if it is partially salted No problem.

The compound of the general formula (I) may be any compound as long as desired effects such as storage stability, frequency responsiveness, ejection property, and burn-in resistance can be obtained in the ink. Specific examples include the following compounds: Can do.
(Compound 1) H ₂ N—C ₂ H ₄ —COOH
(Compound _{2) H 2 N-CH 2} -COOH
(Compound 3) H ₂ N—C ₂ H ₄ —SO ₃ H
(Compound _{4) H 2 N-C 2} H 4 -SO 3 - NH 4 +
(Compound 5) H ₂ N—C ₂ H ₄ —COO ^— N ⁺ (C ₂ H ₄ OH) ₃
(Compound 6) H ₂ N—C ₂ H ₄ —COO ^— NH ₄ ⁺
(Compound 7) H ₂ N—C ₂ H ₄ —COO ⁻ Na ⁺
(Compound _{8) H 2 N-C 2} H 4 -COO - N + C 2 H 4 OC 2 H 4 OH
(Compound _{9) H 2 N-C 2} H 4 -SO 3 - N + (C 2 H 4 OH) 3
(Compound _{10) H 2 N-C 2} H 4 -SO 3 - Li +
(Compound 11)

(Compound 12)

(Compound 13)

(Compound 14)

(Compound _{15) H 2 N-C 2} H 4 -SO 3 - Na +
(Compound _{16) H 2 N-C 2} H 4 -SO 3 - Na + (C 2 H 4 OH) 3
The liquid medium used in the present invention is preferably a mixture of water and a water-soluble organic solvent. Specific examples of water-soluble organic solvents include amides such as dimethylformamide and dimethylacetamide; ketones such as acetone; ethers such as tetrahydrofuran and dioxane; polyalkylenes such as polyethylene glycol and polypropylene glycol Glycols; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol, etc. alkylene glycol containing 2 to 6 carbon atoms Glycerin; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monomethyl (or methyl) A Lower alkyl ethers of polyhydric alcohols such as N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, triethanolamine, sulfolane, dimethyl sulfoxide, 2-pyrrolidone, ε-caprolactam And cyclic amide compounds such as succinimide and the like. These can be used alone or in combination of two or more as required. Among these, it is preferable to use sugar alcohol including glycerin as one kind of liquid medium. When a sugar alcohol is used, the dispersion stability of the water-based ink according to the present invention tends to be particularly good.

  In general, the content of the water-soluble organic solvent is preferably 1 to 40% by mass, more preferably 3 to 30% by mass with respect to the total weight of the water-based ink.

  When the water content in the water-based ink is in the range of 30 to 95% by mass with respect to the total mass of the ink, it is possible to suppress an increase in the viscosity of the ink due to a decrease in the solubility of the coloring material and the like. It is also possible to satisfy excellent anti-adhesion properties.

  The compound of the general formula (I) contained in the water-based ink of the present invention is included in the ink by adhering to the surface layer containing the metal in the portion where heat from the electrothermal converting portion of the ink jet recording head is transferred to the ink. This also has the effect of preventing the occurrence of kogation due to the ingredients. Due to this kogation prevention effect, the ejection stability of the recording head can be improved. The water-based ink of the present invention may further contain a kogation preventing agent as necessary. For example, if the inorganic ions in the ink are 1 ppm, preferably 0.5 ppm or less, it is often unnecessary to add a kogation inhibitor.

  The anti-kogation agent is preferably selected from dicarboxylic acid compounds and tricarboxylic acid compounds. Tricarboxylic acids such as EDTA are not preferred because they are too chelate and easily damage the heater. It can be used in the range of 0.01 to 10% by weight, preferably 0.05 to 5% by weight, more preferably 0.1 to 3% by weight, based on the total weight of the water-based ink.

  The aqueous ink of the present invention preferably contains urea, thiourea and derivatives thereof in the ink. The content of these substances in the ink is 0.1 to 50% by mass, preferably 1 to 30% by mass, and more preferably 2 to 10% by mass with respect to the total mass of the water-based ink.

  Furthermore, a monohydric alcohol may be added to the water-based ink of the present invention as a fixing agent for the ink recording material. In addition, since a nonionic surfactant also functions as a fixing agent, it can be added. These are preferably used in order to prevent color mixing, blurring, and the like that occur at the boundaries when different color tones are printed. In that case, it is preferable to use a nonionic surfactant in consideration of the relationship between the amount added to the ink and the effect.

  Specific examples of the monohydric alcohol that can be added to the aqueous ink of the present invention as a fixing agent include ethanol, isopropyl alcohol, n-butanol and the like. Specific examples of the nonionic surfactant that can be similarly added include polyoxyethylene alkyl ether, polyoxyethylene phenyl ether, polyoxyethylene-polyoxypropylene glycol, polyoxyethylene-polyoxypropylene alkyl ether, and acetylene glycol. Examples include polyoxyethylene oxide adducts. These can be used alone or in combination of two or more as required. Furthermore, nonylphenyl ether EO adducts, ethylene oxide-propylene oxide copolymers (EO-PO copolymers), and acetylene glycol polyoxyethylene oxide adducts are preferred, and acetylene represented by the following general formula (17) is more preferred. It is a glycol polyoxyethylene oxide adduct (acetylene glycol EO adduct).

  The content of the monohydric alcohol or nonionic surfactant in the water-based ink is effective as a fixing agent, and balance of print quality, for example, balance between image density and fixability, and feathering that is a whisker-like blur. In consideration of the above, it is preferably 0.1 to 20% by mass, particularly 0.5 to 10% by mass with respect to the total amount of ink.

  The water-based ink of the present invention has an ink jet recording method in which ink by thermal energy is discharged from a discharge port, particularly, an electrothermal conversion portion that gives heat to the ink for discharge, and has a liquid contact surface layer with the ink, This surface layer is extremely effective when it contains a metal, and is characterized in that no satellite dots are generated. Note that the thermal property values (for example, specific heat, thermal expansion coefficient, thermal conductivity, etc.) of the water-based ink of the present invention may be appropriately adjusted. Examples of the surface layer containing metal include a Ta-based material containing tantalum, which is used in a recording head that uses thermal energy for ink ejection.

  Furthermore, the water-based ink of the present invention has a surface tension of 20 to 55 mN / m and a viscosity of 15 cP or less, preferably 10 cP or less, more preferably 10 cP or less, as physical properties of the ink itself from the viewpoint of good matching with the ink jet recording head. Is preferably adjusted to 5 cP or less, but is not limited to these because it depends on the performance of the inkjet recording head.

  The water content of the water-based ink of the present invention is preferably 50% by mass to 98% by mass, and preferably 60% by mass to 95% by mass. By adjusting it, the recording characteristics on plain paper are also improved.

  In the water-based ink of the present invention, in addition to the above components, if necessary, water-soluble organic solvents other than those listed above, surfactants, or preservatives, fungicides, antioxidants, evaporation accelerators Various additives such as chelating agents and water-soluble polymers may be added.

  As a method and apparatus suitable for recording using the ink of the present invention, thermal energy corresponding to the recording signal is applied to the ink in the liquid chamber of the recording head and discharged from the discharge port (nozzle) to the recording medium. And a method and an apparatus using an ink jet method for recording.

1, 2 and 3 show an example of an apparatus applicable to such a method. In the figure, a head 13 is configured by bonding a substrate 15 having a heat generating portion n to a member such as glass, ceramic or plastic plate having a groove 14 through which ink passes. The substrate 15 includes a protective film 16 formed of silicon oxide or the like, aluminum electrodes 17-1 and 17-2, a heating resistor layer 18 formed of nichrome or the like, a heat storage layer 19, and a base 20 with good heat dissipation such as alumina. Have The ink 21 has a discharge port (orifice) 22 and forms a surface (meniscus) in contact with the atmosphere. When an electric signal is applied to the electrodes 17-1 and 17-2, the region indicated by n of the substrate 15 rapidly generates heat, film boiling occurs in the ink 21 in contact therewith, and the meniscus 23 protrudes due to the pressure. The ink 21 is ejected from the ejection port to form ink droplets 24 that are ejected toward the recording medium 25. FIG. 3 shows an external view of a multi-head in which a number of heads shown in FIG. 1 are arranged. This multi-head is manufactured by bonding a glass plate 27 having multi-grooves 26 and a substrate 28 having a heat generating portion having the configuration shown in FIG. 1 is a cross-sectional view of the head 13 along the ink flow path, and FIG. 2 is a cross-sectional view taken along the line AB of FIG. As an electrothermal conversion part having a surface layer containing a metal, the protective layer 16 in FIG. 2 can be shown. As this metal heat conversion part, Ta, SiN, SiO ₂ or the like is preferable.

  FIG. 4 shows an example of an ink jet recording apparatus incorporating such a head. In FIG. 4, reference numeral 61 denotes a blade as a wiping member, one end of which is held by a blade holding member, which becomes a fixed end and forms a cantilever. The blade 61 is disposed at a position adjacent to the recording area by the head, and in this example, is held in a form protruding in the moving path of the recording head. Reference numeral 62 denotes a cap, which is disposed at a home position adjacent to the blade 61 and has a configuration in which it moves in a direction perpendicular to the moving direction of the recording head and comes into contact with the ejection port surface to perform capping. Further, reference numeral 63 denotes an ink absorber provided adjacent to the blade 61 and, like the blade 61, is held in a form protruding in the moving path of the head.

  The blade 61, the cap 62, and the absorber 63 constitute a discharge recovery portion 64, and the blade 61 and the absorber 63 remove water, dust, and the like from the ink discharge port surface.

  Reference numeral 65 denotes a recording head that has discharge energy generating means and performs recording by discharging ink onto a recording material facing the discharge port surface on which the discharge ports are arranged. Reference numeral 66 denotes a recording head on which the recording head 65 is mounted. It is a carriage for performing 65 movements. The carriage 66 is slidably engaged with the guide shaft 67, and a part of the carriage 66 is connected to a belt 69 (not shown) driven by a motor 68. As a result, the carriage 66 can move along the guide 67, and the recording area and its adjacent area can be moved by the recording head 65. Reference numeral 51 denotes a paper feed unit for inserting a recording material, and 52 denotes a paper feed roller driven by a motor (not shown). With these configurations, the recording material is fed to a position facing the ejection port surface of the recording head, and is discharged to a paper discharge portion provided with a paper discharge roller 53 as recording progresses.

  In the above configuration, when the recording head 65 returns to the home position due to the end of recording or the like, the cap 62 of the head recovery unit 64 is retracted from the moving path of the recording head 65, but the blade 61 protrudes into the moving path. As a result, the ejection port surface of the recording head 65 is wiped. When the cap 62 is in contact with the ejection surface of the recording head 65 to perform capping, the cap 62 moves so as to protrude into the moving path of the recording head. When the recording head 65 moves from the home position to the recording start position, the cap 62 and the blade 61 are in the same position as the above-described wiping position. As a result, the ejection port surface of the recording head 65 is wiped during this movement.

  The above-mentioned movement of the recording head to the home position is not only at the end of recording or at the time of ejection recovery, but also to the home position adjacent to the recording area at a predetermined interval while the recording head moves the recording area for recording. Then, the wiping is performed with this movement.

  FIG. 5 is a diagram illustrating an example of an ink cartridge that stores ink supplied to the head via an ink supply member, for example, a tube. Here, reference numeral 40 denotes an ink container, for example, an ink bag, which contains ink for supply, and a rubber stopper 42 is provided at the tip thereof. By inserting a needle (not shown) into the stopper 42, the ink in the ink bag 40 can be supplied to the head. Reference numeral 44 denotes an absorber that receives waste ink. As the ink containing portion, it is preferable for the present invention that the liquid contact surface with the ink is formed of polyolefin, particularly polyethylene.

  The ink jet recording apparatus used in the present invention is not limited to the one in which the head and the ink cartridge are separated as described above, and an apparatus in which they are integrated as shown in FIG. 6 is also preferably used. .

In FIG. 6, reference numeral 70 denotes a recording unit, in which an ink storage portion storing ink, for example, an ink absorber (ink holding body) made of a porous or fiber aggregate is stored. The ink in the ink absorber is ejected as ink droplets from a head portion 71 having a plurality of orifices. As the material of the ink absorber, it is preferable for the present invention to use one or more materials selected from polyolefins such as polyurethane, cellulose, polyvinyl acetal, polyethylene and polypropylene. Reference numeral 72 denotes an atmosphere communication port for communicating the inside of the recording unit with the atmosphere. The recording unit 70 is used in place of the recording head shown in FIG. 4 and is detachable from the carriage 66.
In addition, it is preferable that the above-described ink storage portion has an ink holding body inside and has a sparsely packed inside. This is because if the inside of the ink containing portion is improved in density, ink movement in the ink containing portion is improved. Specifically, for example, Japanese Patent Publication No. 2998065, Japanese Patent Application Laid-Open No. 2003-103799, Japanese Patent Application Laid-Open No. 11-342626 can be presented.

  The ink of the present invention is a recording unit in which the ink tank and the head are integrated, a recording unit in which the ink tank and the head are detachable, and these recording units are detachably mounted for recording. The present invention can also be suitably used for a recording apparatus to be performed, a recording apparatus in which an ink tank and a head are separately provided and these are connected by an ink supply system.

Next, the present invention will be described more specifically with reference to examples and comparative examples. Unless otherwise specified, “part” and “%” in the text are based on mass.
(1) Preparation method of water-based ink:
The components shown in the following examples and comparative examples were mixed and sufficiently stirred, and then pressure filtered with a fluoropore filter (trade name: manufactured by Sumitomo Electric Co., Ltd.) having a pore size of 0.4 μm. Thus, each water-based ink was prepared.
Example 1
As a commercially available pigment having a hydrophilic group, CABOjet 200 (trade name: manufactured by Cabot Corporation) was made into an H type using an ion exchange resin, and then water was evaporated to obtain an H type CABOJET 200.
Example 2
Ink composition:
Pigment obtained in Example 1: 5%
Compound 7: 1.0%
Glycerin: 10%
Ethylene glycol: 10%
Pure water: 74%
Example 3
Ink composition:
Pigment obtained in Example 1: 5%
Compound 15: 0.5%
Polyglycerin: 7.5%
Xylitol: 7.5%
Ethylene glycol: 7.5%
Pure water: 72%
Example 4
Ink composition:
CABOjet200 (trade name: manufactured by Cabot): 5%
Compound 3: 0.2%
Glycerin: 10%
Ethylene glycol: 10%
Pure water: 74.8%
Example 5
Using a commercially available CABOJET300 (trade name: manufactured by Cabot Corporation) as a pigment having a hydrophilic group, a pigment having an average particle diameter of 100 nm or less is taken out using a centrifuge, and water is evaporated to obtain a pigment powder. Obtained.
Example 6
Ink composition:
CABOJET300 (trade name: manufactured by Cabot): 5%
Compound 7: 3%
Glycerin: 10%
Xylitol: 10%
Pure water: 72%
Example 7
Ink composition:
Pigment of Example 6: 5%
Compound 5: 3%
Glycerin: 10%
Ethylene glycol: 10%
Pure water: 72%
Example 8
After the pigment of Example 6 was dispersed in 20 times pure water, it was made H-type using an ion exchange resin, and water was evaporated to obtain H-type CABOJET 300.
Example 9
Ink composition:
Pigment obtained in Example 8: 3%
Compound 7: 0.5%
Glycerin: 10%
Ethylene glycol: 10%
Isopropyl alcohol: 2%
Pure water: 74.5%
Example 10
After adding 1000 ml of pure water to 300 g of commercially available carbon black Fw200 (trade name: Degussa) and mixing well, 450 g of sodium hypochlorite was added dropwise and stirred at 100 to 105 ° C. for 10 to 15 hours. Thereafter, 100 g of sodium hypochlorite was added, and a dispersion process was performed for 5 hours with a horizontal disperser using zirconia beads. The obtained dispersion was diluted 20 times with pure water and purified using a reverse osmosis membrane to obtain a pigment having a carboxylic acid group of Na ⁺ ions. Then, moisture was evaporated to obtain a pigment powder.

Example 11
Ink composition:
Pigment obtained in Example 10: 5%
Compound 8: 5%
Glycerin: 10%
Glycitol: 10%
Pure water: 70%
Example 12
After the pigment obtained in Example 10 was dispersed in pure water, it was made H type using an ion exchange resin, and water was evaporated to obtain a pigment powder.

Example 13
Ink composition:
Pigment obtained in Example 12: 4%
Compound 16: 4%
Glycerin: 10%
Ethylene glycol: 10%
2-pyrrolidone: 5%
Pure water: 67%
Comparative Example 1
Ink composition:
CABOjet200 (trade name: manufactured by Cabot): 5%
Diethylene glycol: 10%
Glycerin: 10%
Pure water: 75%
Comparative Example 2
Ink composition:
CABOjet300 (trade name: manufactured by Cabot): 5%
Diethylene glycol: 10%
Glycerin: 10%
Pure water: 75%
Comparative Example 3
Ink composition:
Pigment obtained in Example 10: 5%
Diethylene glycol: 10%
2-pyrrolidone: 2%
Thiodiglycol: 10%
Pure water: 73%
(2) Evaluation method Evaluation of storage stability 1:
100 g of the water-based ink obtained in Examples and Comparative Examples was placed in a polypropylene container, allowed to stand in a room temperature environment for one month, and then the wetness of the ink on the container wall was visually observed and evaluated according to the following criteria.
○: When the container is inclined, the ink is repelled neatly.
Δ: When the container is slanted, the ink is repelled neatly, but it takes time, or the ink is attached to the wall surface. A state that can be taken.
X: The ink is adhered even when the container is inclined, and the ink is adhered even after a long time.

Evaluation of preservability 2:
100 g of the water-based ink obtained in Examples and Comparative Examples was put in a glass sealed container and allowed to stand at 60 ° C. for one month. Then, the occurrence of precipitates and the state thereof were visually observed, and evaluated according to the following criteria. did.
(Double-circle): The deposit was not seen.
○: No precipitate was observed, but a slight precipitate was observed when the ink was filtered through a filter.
Δ: No precipitate was observed, but when the ink was filtered with a filter, a large amount of precipitate was observed.
X: Precipitate was deposited there.

Evaluation of frequency response:
The aqueous inks obtained in the examples and comparative examples are continuously printed with alphanumeric characters at a printing speed of about 10 kHz using an inkjet printer BJC5500 (trade name: manufactured by Canon Inc.) under a normal temperature and normal pressure environment. The printed matter obtained was visually observed and evaluated according to the following criteria.
A: No dot missing was found in the alphanumeric characters of the printed matter. Further, there is no stain due to dripping of ink droplets such as satellites and splashes.
○: No dots were found in the alphanumeric characters of the printed matter, but slight stains due to ink drops such as satellite and splash were observed.
Δ: Although dots of alphanumeric characters in the printed matter were observed, it could be read from a distance of 30 cm without any problem.
X: It was difficult to read even from a distance of 30 cm from the alphanumeric characters of the printed matter, which caused frequent dot skipping.

Reliability assessment 1:
Using water-based inks obtained in Examples and Comparative Examples, an inkjet printer BJC5500 (trade name: manufactured by Canon Inc.) was used to print a solid pattern of 50% Duty, each nozzle ejecting 10 ⁸ ink droplets, and printing After that, the heater surface of the recording head and the printed matter were enlarged as necessary and visually observed, and evaluated according to the following criteria.
○: No burnt deposit such as coloring material was found on the heater surface.
Δ: Deposits were observed on the heater surface, but the printing was clean.
X: Many deposits were seen on the heater surface.

Reliability evaluation 2
The aqueous inks obtained in the examples and comparative examples were left in a 50 ° C. environment for one month using an inkjet printer BJC430J (trade name: manufactured by Canon Inc.), and after one recovery operation, alphanumeric characters Was printed and evaluated according to the following criteria observed visually.
○: Printing was not disturbed.
Δ: Slightly disturbed printing and missing dots were observed, but alphanumeric characters could be read.
X: Printing was disturbed, dots were frequently generated, or ink was dropped, and printing could not be performed.
(3) Evaluation results Table 1 shows the evaluation results.

It is sectional drawing of the inkjet head along the ink flow path of an inkjet recording device. FIG. 2 is a cross-sectional view taken along line AB in FIG. 1. FIG. 2 is an external view of a multi-head in which a number of inkjet heads illustrated in FIG. 1 are arranged. It is an external view which shows an example of the inkjet recording device incorporating the inkjet head. FIG. 3 is a cross-sectional view illustrating an example of an ink cartridge that contains ink supplied to an inkjet head via a tube. FIG. 3 is an external view of an ink jet head and an ink cartridge that are integrated.

Explanation of symbols

13 Head 14 Groove 15 Substrate 16 Protective Film 17-1, 17-2 Aluminum Electrode 18 Heating Resistor Layer 19 Heat Storage Layer 20 Substrate 21 Ink 22 Orifice 23 Meniscus 24 Ink Droplet 25 Recording Medium 26 Multi-Groove 27 Glass Plate 28 Substrate 40 Ink storage section 42 Plug 44 Absorber 51 Paper feed section 52 Paper feed roller 53 Paper discharge roller 61 Blade 62 Cap 63 Ink absorber 64 Discharge recovery section 65 Head 66 Carriage 67 Guide shaft 68 Motor 69 Belt 70 Recording unit 71 Head section 72 Air communication port

Claims (19)

An ink that is in contact with a surface layer containing a metal of an electric heat exchanging portion that imparts thermal energy to the ink,
A pigment having self-dispersibility in water by having a hydrophilic group as a coloring material;
A liquid medium for dispersing the pigment;
Formula (I):
BX-A (I)
(In the above general formula (I), A represents one group selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, and salts thereof; B represents an amino group or an amide group; Represents an alkylene group or a cyclic compound group.)
A compound represented by
A water-based ink characterized by comprising: The alkylene group is CnH2n (n represents an integer of 1 to 3), and the cyclic compound is

The water-based ink according to claim 1, wherein   The water-based ink according to claim 1, wherein the hydrophilic group of the pigment is an anionic group.   The water-based ink according to claim 3, wherein the hydrophilic group is at least one selected from the group consisting of a carboxylic acid group, a sulfonic acid group, and a salt thereof.   The water-based ink according to claim 4, wherein the hydrophilic group is a salt of a carboxylic acid group and / or a salt of a sulfonic acid group.   The water-based ink according to claim 1, wherein the average particle diameter of the pigment is 200 nm or less.   The water-based ink according to claim 6, wherein the pigment has an average particle size of 100 nm or less.   The water-based ink according to claim 1, wherein the pigment is a derivative of an inorganic compound.   The water-based ink according to claim 8, wherein the inorganic compound is carbon black.   The aqueous ink according to claim 1, wherein the liquid medium contains at least one sugar alcohol.   The water-based ink according to claim 10, wherein the sugar alcohol is solid at room temperature.   In an ink jet recording method for recording on a recording material by discharging ink from an ejection port of a recording head according to a recording signal, the water-based ink according to any one of claims 1 to 11 is provided in the recording head. An ink jet recording method comprising discharging from the discharge port by heating from a metal electrothermal converter having a surface layer in contact with ink.   A recording unit comprising: an ink storage unit that stores ink; and a recording head that discharges ink. The ink is the water-based ink according to any one of claims 1 to 11, and the recording head A recording unit comprising an electrothermal conversion section for applying thermal energy for ejection from an ejection port, the electrothermal conversion section comprising a metal and having a surface layer in contact with ink.   The recording unit according to claim 13, wherein the ink container has an ink holding member therein.   The recording unit according to claim 14, wherein the ink storage portion has a sparse / dense state therein.   12. An ink cartridge comprising an ink containing portion containing ink, wherein the ink is water-based ink according to any one of claims 1 to 11.   The ink cartridge according to claim 16, wherein the ink containing portion has a liquid contact surface formed of polyolefin.   An inkjet recording apparatus comprising a recording unit, wherein the recording unit is the recording unit according to any one of claims 13 to 15. In an ink jet recording apparatus comprising a recording head for discharging ink, an ink cartridge having an ink containing portion containing ink, and an ink supply portion for supplying ink from the ink cartridge to the recording head,
The ink cartridge according to claim 16 or 17, wherein the recording head includes an electrothermal conversion unit that applies heat energy to the recording head to be ejected from an ejection port. An ink jet recording apparatus, wherein the electrothermal converting portion includes a metal and has a surface layer in contact with ink.

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