JP2006160907A - Method for producing ink jet recording ink, ink jet recording method, ink cartridge and ink jet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recording ink which has a good extrusion performance and can stably record images having excellent fastness and excellent grade. <P>SOLUTION: This method for producing a color material dispersion type ink jet recording ink consisting mainly of a polymer dispersant comprising a block copolymer composed from an anionic hydrophilic group-having hydrophilic block and a hydrophobic block, a water-insoluble color material, a water-soluble organic solvent and water is characterized by having at least (1) the first process for thermally treating a color material dispersion consisting mainly of the polymer dispersant and a water-insoluble color material to lower pH, (2) the second process for mixing the color material dispersion obtained in the first process with the water and the water-soluble organic solvent to produce the ink, and (3) the third process for filtering the ink obtained in the second process. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing ink jet recording ink (hereinafter simply referred to as “ink”), an ink jet recording method, an ink cartridge, and an ink jet recording apparatus. More specifically, the present invention relates to an ink manufacturing method, an ink jet recording method, an ink cartridge, and an ink jet recording apparatus that have little fluctuation in pH value and high ejection stability even after long-term storage and good color development of a printed image.

  Conventionally, water-insoluble colorants such as pigments having excellent fastness such as water resistance and light resistance have been widely used as colorants for printing inks. In recent years, water-based inks using pigments have come to be used as inks from the viewpoint of image fastness also in inkjet recording applications. In order to use a pigment as a coloring material for water-based ink, it is required to stably disperse the pigment in an aqueous medium. Therefore, a color material dispersion type aqueous ink is used in which a dispersant such as a polymer dispersant or a surfactant is added to uniformly disperse the pigment in the aqueous medium. However, if these color material dispersed inks are stored, the long-term storage stability of the ink will be improved, such as changes in physical properties such as pH values, and aggregation of the color material particles, resulting in uneven density and sedimentation of the ink. There is a problem of being bad. When the pH value of the ink is lowered, there is a risk that the ink ejection stability is lowered, for example, the ink is clogged at the nozzle tip of the ink jet recording apparatus.

  In addition, the ink used for inkjet recording is desired to have good fixability and no bleeding when printed on paper as a recording material. However, in the case of ink using a pigment, since the pigment remains on the surface of paper or the like, there is a problem that the scratch resistance of the printed matter is deteriorated.

In order to solve the above problems, Patent Documents 1 and 2 propose inks that exhibit good storage stability by heat-treating a colorant dispersion or ink. However, in Patent Document 1, only dispersion stability is considered, and the resulting image is not sufficiently scratch resistant. Patent Document 2 proposes an ink manufacturing method in which a heat treatment is performed on a pigment dispersion or ink. However, line heads that take into account only the ink ejection properties when performing recovery cleaning frequently, such as serial machines, require continuous long-term ink ejection, high-speed printing, etc., and the frequency of recovery processing is low. In this machine, there is a problem that the ink adheres to the peripheral portion of the nozzle, and the ink ejection stability is not satisfactory.
JP 2000-345093 A Japanese Patent Laid-Open No. 8-73785

  The object of the present invention has been made in view of the above-mentioned problems, has a small pH value fluctuation, good storage stability, does not impair ejection stability even in continuous printing over a long period of time, and is firmly attached to paper. Inkjet recording method for producing an ink capable of providing an image having high fastness while maintaining the property, and further capable of stably recording an image having good ejection performance and excellent fastness and quality at any time Another object of the present invention is to provide an ink cartridge and an ink jet recording apparatus.

As a result of intensive studies to solve the above problems, the present inventors have found that the following problems can be solved by the present invention. That is, the present invention mainly comprises a polymer dispersant comprising a block copolymer composed of a hydrophilic block having an anionic hydrophilic group and a hydrophobic block, a water-insoluble colorant, a water-soluble organic solvent, and water. In the method for producing the color material dispersed ink,
(1) The first step of lowering the pH of the colorant dispersion mainly comprising the polymer dispersant, the water-insoluble colorant and water by heat treatment, and (2) the colorant dispersion obtained in the first step. A method of producing an ink, comprising: a second step of mixing water and a water-soluble organic solvent to form an ink; and (3) a third step of filtering the ink obtained in the second step. provide.

  In the present invention, a fourth step of increasing the pH of the colorant dispersion by adding an alkali agent between the first step and the second step is performed; Performing a fifth step of adding an alkali agent to raise the pH of the ink between the second step and the third step; and the alkali agent is an anion of the polymer dispersant. It is preferable to contain the same base as the neutralizing agent for the hydrophilic hydrophilic group.

  In the present invention, the neutralizing agent for the anionic hydrophilic group of the polymer dispersant is lithium or sodium; the pH of the colorant dispersion lowered by the heat treatment in the first step is It is preferable that the pH of the coloring material dispersion is 8.5 to 10.0 before being lowered by heat treatment in the first step.

  In the present invention, as the water-soluble organic solvent added in the second step, polyoxyethylene acetylenic glycol ethers having an average addition weight of ethylene oxide of 65 is used for the water-insoluble colorant in the ink. The glycerin is contained in an amount of 6.0 to 12.0% by mass with respect to the total mass of the ink; A block copolymer comprising a hydrophobic block composed of at least one vinyl ether and a hydrophilic block composed of at least one vinyl ether is preferable.

  In the present invention, the hydrophilic block of the polymer dispersant is composed of a vinyl ether having a nonionic hydrophilic group and a block composed of a vinyl ether having an anionic hydrophilic group. The polymer dispersant contains a block composed of a hydrophobic vinyl ether and a block composed of a hydrophilic vinyl ether having a nonionic hydrophilic group and a hydrophilic group having an anionic hydrophilic group. It is preferable that at least the block is composed of vinyl ethers; and the water-insoluble colorant is a pigment.

  Further, the present invention is an ink jet recording method performed by applying energy to an ink, causing the ink to fly and applying it to a recording material, wherein the ink is an ink produced by the method of the present invention. An ink jet recording method is provided. In this recording method, the energy is preferably thermal energy; and the recording material is preferably a recording material having a coating layer that receives ink on at least one surface.

  According to the present invention, there is provided an ink cartridge provided with an ink containing portion containing ink, wherein the ink contains an ink produced by the method of the invention; and an ink containing ink An ink jet recording apparatus comprising an ink cartridge provided with a section and a head section for ejecting the ink, wherein the ink contains the ink produced by the method of the present invention. To do.

  According to the present invention, the pH value fluctuation is small, the storage stability is good, the discharge stability is not impaired even in continuous printing over a long period of time, and the strong adhesion to the paper is maintained and the color fastness is high. INK JET RECORDING METHOD, INK CARTRIDGE, AND INK CARTRIDGE RECORDING, INDUSTRIAL APPLICABILITY An apparatus can be provided.

Next, the present invention will be described in more detail with reference to the best mode for carrying out the invention.
The ink production method of the present invention comprises a polymer dispersant comprising a block copolymer composed of a hydrophilic block having an anionic hydrophilic group and a hydrophobic block, a water-insoluble colorant, a water-soluble organic solvent, and water. In the method for producing a color material dispersed ink mainly comprising:
(1) The first step of lowering the pH of the colorant dispersion mainly comprising the polymer dispersant, the water-insoluble colorant and water by heat treatment, and (2) the colorant dispersion obtained in the first step. In addition, at least a second step of mixing water and a water-soluble organic solvent to form an ink and (3) a third step of filtering the ink obtained in the second step are stored with little fluctuation in pH value. Produces an ink that has good stability, does not impair ejection stability even in continuous printing over a long period of time, maintains strong adhesion to paper, and can provide an image with high robustness and high color development I found that I can do it.

  In the present invention, a polymer dispersant composed of a block copolymer composed of a hydrophilic block having an anionic hydrophilic group and a hydrophobic block is used. Since such a polymer dispersant has a hydrophilic portion and a hydrophobic portion separated from each other compared to a polymer dispersant synthesized by randomly polymerizing constituent monomers, the polymer dispersant and the colorant are separated from each other. It becomes easy to interact with the medium and the medium, and it becomes possible to maintain the good dispersion stability of the coloring material and the fixing property with the medium such as paper at a high level.

  In addition, because it has good affinity with ink media, it is possible to reduce the adhesion of ink around the nozzles of ink jet printers of color material dispersions, and good ejection without print shading or blurring even during long-term continuous printing Shows stability. However, as can be seen in general pigment inks, when the ink is stored for a long period of time, particularly at high temperatures, the pH value of the ink decreases, and as a result, the hydrophilic block having an anionic hydrophilic group is reduced. There has been a problem that the continuous printability deteriorates due to a decrease in hydrophilicity and a decrease in affinity with the ink medium.

  In particular, the polymer dispersant used in the present invention has the property that when the pH of the ink is lowered, the interaction force between the polymer dispersants is extremely increased and the ink is gelled. If it is lowered, ink adhesion and nozzle clogging around the nozzles of the ink jet printer occur more remarkably, and there is a problem that continuous printability is greatly deteriorated.

  In general, in a pigment dispersion used for pigment ink, a pigment and a polymer dispersant are stirred and mixed, and the polymer dispersant is adsorbed on the pigment surface to impart dispersibility to the pigment. The polymer dispersant present on the pigment surface is neutralized with a basic substance, so that the hydrophilic group of the polymer dispersant is dissociated as ions in water and can be stably dispersed in an aqueous medium. However, some of the functional groups acting as hydrophilic groups of the polymer dispersant are present on the pigment surface without being neutralized while adsorbing to the pigment, and such an adsorption state is unstable. . The reason why the pH value of the pigment ink is lowered is that the unneutralized functional groups adsorbed on these pigments are gradually oriented toward the aqueous medium side, neutralizing the basic substance in the aqueous medium, and the ink This is thought to be due to the shortage of basic substances.

  As in the present invention, when a colorant dispersion mainly composed of a polymer dispersant, a water-insoluble colorant, and water is heat-treated, the thermal movement of the polymer dispersant in the colorant dispersion becomes active, and the polymer dispersion By spreading the molecular chain of the agent, the non-neutralized anionic group adsorbed on the color material is directed to the aqueous medium side, and the color material dispersion is stabilized. The stabilization of the colorant dispersion is promoted by the heat treatment, so that even if the ink is stored for a long period of time, the fluctuation of the pH value is small, and the pH of the ink can be maintained in a range where the continuous printability is good. Therefore, even if continuous printing is performed with a line head machine that does not include a head cleaning mechanism after storage, it maintains the same level as before storage without sticking to the periphery of the nozzle, and excellent discharge stability Can be shown.

The manufacturing method of the present invention will be described with reference to the flowchart shown in FIG.
In the first step, a colorant dispersion mainly composed of a polymer dispersant composed of a block copolymer composed of a hydrophilic block having an anionic hydrophilic group and a hydrophobic block, a water-insoluble colorant, and water is prepared. The pH is lowered by heat treatment. In the second step, the colorant dispersion obtained in the first step is mixed with water and a water-soluble organic solvent to form an ink, and in the third step, the ink obtained in the second step is filtered. .

  In the first step, the color material dispersion may be heat-treated to lower the pH. The pH value after the heat treatment is preferably in the range of 8.3 to 9.5. If the pH value is less than 8.3, the heat treatment takes a lot of time and there is a problem that the dispersion of the colorant dispersion occurs. If the pH value is greater than 9.5, the heat treatment is insufficient. The pH value of the color material dispersion may not reach the stable region. As temperature of heat processing, it is preferable that it is the range of 40 to 90 degreeC, and it is more preferable that it is the range of 60 to 80 degreeC. The pH value of the colorant dispersion before the heat treatment is preferably in the range of 8.5 to 10.0. If the pH value is not within this range, a basic substance or the like may be added to adjust the pH value.

  In the second step, the colorant dispersion prepared in the first step is mixed with water and a water-soluble organic solvent to form an ink. As the water-soluble organic solvent to be added, glycerin is desirable, and glycerin is preferably contained in a range of 6.0 to 12.0% by mass with respect to the total mass of the ink. Furthermore, it is preferable that polyoxyethylene acetylenic glycol ethers are contained in the range of 0.02 to 0.2 times by mass ratio with respect to the water-insoluble colorant in the ink. As the polyoxyethylene acetylenic glycol ethers in the present invention, those having an average addition weight of ethylene oxide of 65 (average addition number 10) are particularly preferable. In addition to these water-soluble organic solvents, water-soluble organic solvents and various additives described later may be added. When mixing these ink components, it is preferable to add them so as not to cause density unevenness, and a method of adding the solution phase to be added while stirring can be used.

  In the third step, the ink prepared in the second step is filtered, and there is a purpose of removing solids such as dust and coarse particles in the ink. A filter having an effective diameter of 10 μm or less, preferably 3 μm may be used. Various materials can be used as the filter material, but it is preferable to use a filter prepared for an aqueous solvent. As a filtration method, either pressure filtration or vacuum filtration can be used.

  Furthermore, an alkali agent is added between the first step and the second step to perform a fourth step of raising the pH of the colorant dispersion; an alkali agent is added between the second step and the third step Thus, the fifth step of raising the pH of the ink can be performed. At this time, it is preferable to add a basic substance so that the pH value is in the range of 8.5 to 10.0. As the basic substance to be used, those containing the same base as the anionic hydrophilic group neutralizing agent of the polymer dispersant are more preferred.

  Further, it is more preferable to perform the first step after the fourth step because the pH drop during long-term storage at high temperature can be further reduced. The operation of performing the first step after the fourth step can be repeated a plurality of times.

Next, various materials used in the production method of the present invention will be described.
(Polymer dispersant)
As the polymer dispersant used in the production method of the present invention, a block copolymer composed of a hydrophilic block having an anionic hydrophilic group and a hydrophobic block is used. Among them, it is preferable that each block of the hydrophobic block and the hydrophilic block is a polymer dispersant composed of vinyl ethers because a more stable colorant dispersion is formed.

  In this case, the polymer dispersant has at least one kind of hydrophilic block having an anionic hydrophilic group and at least one kind of hydrophobic block, and each block is a block copolymer made of vinyl ethers. It can be used as long as it has two or more types of hydrophilic blocks or two or more types of hydrophobic blocks, and can be a single block copolymer or a mixture of two or more types of block copolymers. Can be used. Examples of the form of the copolymer include a linear type and a graft type, and a linear type block copolymer is preferable.

The polymer dispersant used in the present invention preferably has a repeating unit structure represented by the following general formula (1), for example.
^{_{- (CH 2 -CH (OR 1}} )) - (1)
In the general formula (1), R ¹ represents an aliphatic hydrocarbon such as an alkyl group, an alkenyl group, a cycloalkyl group, or a cycloalkenyl group, a phenyl group, a pyridyl group, a benzyl group, a toluyl group, a xylyl group, An aromatic hydrocarbon group in which a carbon atom may be substituted with a nitrogen atom, such as an alkylphenyl group, a phenylalkylene group, a biphenyl group, and a phenylpyridyl group. Moreover, the hydrogen atom on the aromatic ring may be substituted with a hydrocarbon group. R ¹ preferably has 1 to 18 carbon atoms.

R ¹ may be a group represented by — (CH (R ² ) —CH (R ³ ) —O) _p —R ⁴ or — (CH ₂ ) _m — (O) _n —R ⁴ . In this case, R ² and R ³ each independently represent a hydrogen atom or a methyl group, and R ⁴ represents an aliphatic hydrocarbon such as an alkyl group, an alkenyl group, a cycloalkyl group, or a cycloalkenyl group, a phenyl group, Aromatic hydrocarbon groups in which carbon atoms may be substituted with nitrogen atoms, such as pyridyl group, benzyl group, toluyl group, xylyl group, alkylphenyl group, phenylalkylene group, biphenyl group, phenylpyridyl group (aromatic The hydrogen atom on the ring may be substituted with a hydrocarbon group), —CHO, —CH ₂ CHO, —CO—CH═CH ₂ , —CO—C (CH ₃ ) ═CH ₂ , —CH ₂ —CH═CH ₂ , —CH ₂ —C (CH ₃ ) ═CH ₂ , —CH ₂ —COOR ^5, etc., and the hydrogen atom in these groups is fluorine, as long as it is chemically possible. salt , It may be substituted with a halogen atom such as bromine. The number of carbon atoms of R ⁴ is 1 to 18 is preferred. R ⁵ is hydrogen or an alkyl group. p is preferably 1 to 18, m is preferably 1 to 36, and n is preferably 0 or 1.

In R ¹ and R ⁴ , examples of the alkyl group or alkenyl group include methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, t-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl. , Tetradecyl, hexadecyl, octadecyl, oleyl, linoleyl and the like, and examples of the cycloalkyl group or cycloalkenyl group include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclooctyl, cyclohexenyl and the like.

  The structures of the vinyl ether monomers (Ia to Io) and the polymer dispersants (II-a to II-e) constituting the polymer dispersant used in the present invention are exemplified below. The polyvinyl ether structure of the polymer dispersant used is not limited to these.

  Further, in the number of repeating units of the polyvinyl ether (in the above (II-a) to (II-e)), m, n, and l (el) are each preferably preferably 1 to 10,000. In addition, in the above (II-a) to (II-e), m + n + 1 (el) is more preferably 10 to 20,000, and the number average molecular weight is 500 to 20,000,000. It is preferably 1,000 to 5,000,000, most preferably 2,000 to 2,000,000, and the proportion of these polymer dispersants in the colored dispersion is colored dispersion. Preferably it is 0.1-20 mass% with respect to the total mass, More preferably, it is 0.5-10 mass%.

  A method for synthesizing a copolymer (polymer dispersing agent) having a vinyl ether polymer block is not particularly limited, but cation living polymerization by Aoshima et al. (Japanese Patent Laid-Open Nos. 11-322942 and 11-322866) can be used. Preferably used. By using the cationic living polymerization method, homopolymers with exactly the same length (molecular weight), copolymers of two or more monomers, block polymers, graft copolymers, gradation copolymers, etc. Various polymers can be synthesized. Moreover, various functional groups can be introduced into the side chain of polyvinyl ether.

  The anionic hydrophilic group neutralizing agent of the polymer dispersant can be used as long as it can neutralize the anionic hydrophilic group of the polymer dispersing agent and dissolves in water. . Examples of such a neutralizing agent include alkali metals such as lithium, sodium, and potassium, amines such as monoethanolamine and triethanolamine, ammonia, and the like. Colorant obtained when lithium or sodium is used. It is preferable because the stability of the dispersion is further improved.

(Water-insoluble colorant)
As the water-insoluble color material used in the production method of the present invention, any color material that hardly dissolves in water can be used. Specifically, the colorant has a solubility in water of preferably 0.5% by mass or less, more preferably 0.1% by mass or less. As such a color material, an oil-soluble dye, a vat dye, a disperse dye, a pigment, and the like are preferable, and more preferable because the pigment forms a stable color material dispersion with the polymer dispersant.
Examples of water-insoluble colorants are shown below, but the present invention is not limited to these.

(Oil-soluble dye)
C. I. Solvent Yellow 1, 2, 3, 13, 14, 19, 21, 22, 29, 36, 37, 38, 39, 40, 42, 43, 44, 45, 47, 62, 63, 71, 76, 79, 81, 82, 83: 1, 85, 86, 88, 151; C.I. I. Solvent Red 8, 27, 35, 36, 37, 38, 39, 40, 49, 58, 60, 65, 69, 81, 83: 1, 86, 89, 91, 92, 97, 99, 100, 109, 118, 119, 122, 127, 218; I. Solvent Blue 14, 24, 25, 26, 34, 37, 38, 39, 42, 43, 44, 45, 48, 52, 53, 55, 59, 67, 70; C.I. I. Solvent Black 3, 5, 7, 8, 14, 17, 19, 20, 22, 24, 26, 27, 28, 29, 43, 45, etc .;

(Vat dyes)
C. I. Vat Yellow 2, 4, 10, 20, 33; I. Vat Orange 1, 2, 3, 5, 7, 9, 13, 15; I. Vat Red 1, 2, 10, 13, 15, 16, 61; I. Bat Blue 1, 3, 4, 5, 6, 8, 12, 14, 18, 19, 20, 29, 35, 41; C.I. I. Bat Black 1, 8, 9, 13, 14, 20, 25, 27, 29, 36, 56, 57, 59, 60, etc.

(Disperse dye)
C. I. Disperse Yellow 5, 42, 83, 93, 99, 198, 224; I. Disperse Orange 29, 49, 73; C.I. I. Disperse Red 92, 126, 145, 152, 159, 177, 181, 206, 283; I. Disperse Blue 60, 87, 128, 154, 201, 214, 224, 257, 287, 368, etc.

(Pigment)
Raven 760 Ultra, Raven 1060 Ultra, Raven 1080, Raven 1100 Ultra, Raven 1170, Raven 1200, Raven 1250, Raven 1255, Raven 1500, Raven 2000, Raven 2500 Ultra, Raven 3500, Raven 5250, Raven 5750, Raven 7000, Raven 5000 ULTRAII, Raven 1190 ULTRAII (above Colombian Carbon); Black Pearls L, MOGUL-L, Regal400R, Regal660R, Regal330R, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1300, Monarch 1400 (above Manufactured by Cabot Corporation);

Color Black FW1, Color Black FW2, Color Black FW200, Color Black 18, Color Black S160, Color Black S170, Special Black 4, Special Black 4A, Special Black 6, Special Black 550, Printex 35, Printex 45, Printex 55, Printex 85, Printex 95, Printex U, Printex 140U, Printex V, Printex 140V (above, manufactured by Degussa);

No. 25, no. 33, no. 40, no. 45, no. 47, no. 52, no. 900, no. 970, no. 2200B, no. 2300, no. 2400B, MCF-88, MA600, MA77, MA8, MA100, MA230, MA220 (above, manufactured by Mitsubishi Chemical Corporation);

C. I. Pigment Yellow 3, 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 95, 97, 109, 110, 117, 120, 125, 128, 137, 138, 147, 148, 150, 151, 153, 154, 166, 168, 175, 180, 183, 184, 185; I. Pigment orange 16, 36, 43, 51, 55, 59, 61, 71; C.I. I. Pigment Red 9, 12, 48, 49, 52, 53, 57, 97, 122, 123, 149, 168, 175, 176, 177, 180, 184, 192, 202, 215, 216, 217, 220, 223, 224, 226, 227, 228, 238, 240, 254, 255, 272; I. Pigment violet 19, 23, 29, 30, 32, 37, 40, 50; C.I. I. Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 22, 60, 64; C.I. I. Pigment green 7, 36; I. Pigment brown 23, 25, 26; I. Pigment Black 1, 10, 31, 32, etc.

  The content of the water-insoluble colorant in the ink is preferably in the range of 0.1 to 20% by mass, more preferably 1.0 to 10% by mass with respect to the total mass of the ink. If the amount of the water-insoluble color material is less than 0.1% by mass, it may be difficult to obtain a sufficient image density. If the amount exceeds 20% by mass, the ejection stability is likely to deteriorate due to clogging in the nozzle. In addition, the content ratio of the water-insoluble colorant and the polymer dispersant in the ink is preferably 100: 1 to 1: 2 in terms of solid content from the viewpoint of ink ejection stability and storage stability. . In addition, these water-insoluble coloring materials can be used in combination of two or more, in addition to being used alone.

(Water-soluble organic solvent)
The water-soluble organic solvent used in the method for producing the ink of the present invention can be any water-soluble organic solvent, and can also be used as a mixed solvent of two or more water-soluble organic solvents.

  Specific examples of preferred water-soluble organic solvents include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol and other lower alcohols; ethylene glycol, diethylene glycol, Triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, thiodiglycol, 1,4-cyclohexanediol Diols such as: Triols such as glycerin, 1,2,4-butanetriol, 1,2,6-hexanetriol, 1,2,5-pentanetriol; trimethylolpro Hindered alcohols such as ethylene, trimethylolethane, neopentyl glycol, pentaerythritol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monoallyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether , Glycol ethers such as diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether; dimethyl sulfoxide, glycerin monoallyl ether, polyethylene glycol, N- Methyl-2- Loridone, 2-pyrrolidone, γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, sulfolane, β-dihydroxyethylurea, urea, acetonylacetone, dimethylformamide, dimethylacetamide, acetone, diacetone alcohol, etc. .

  Among these, it is preferable to use a water-soluble organic solvent having a boiling point of 120 ° C. or more because ink concentration at the nozzle tip is suppressed. The proportion of these water-soluble organic solvents in the ink is preferably 5 to 50% by mass and more preferably 10 to 30% by mass with respect to the total mass of the ink.

  The above are the essential components of the ink obtained by the production method of the present invention. In addition to these components, various additives such as surfactants, pH adjusters, antioxidants, and antifungal agents may be added. Good. Among these additives, aluminum or aluminum compounds such as aluminum hydroxide, aluminum oxide, tripropylaluminum, triisopropylaluminum, aluminum compounds of Ziegler-Natta catalyst, and metal aluminum powder are used as additives in the ink. Preferably, when aluminum hydroxide or aluminum oxide is contained, aluminum or aluminum compound acts on the hydrophobic block and hydrophilic block of the polymer dispersant, thereby improving the bond between the polymer dispersants. Colorant particle capsules are desirable because they are more stable. The amount of aluminum or aluminum compound added is preferably a molar ratio of the polymer dispersant (A) to aluminum and (B) in the ink, preferably A: B = 3,000: 1 to 1: 5. Is more preferably 300: 1 to 20: 1 because the stability of the capsule of the colorant particles made of the polymer dispersant is improved.

  A characteristic of the ink jet recording method of the present invention is that the ink manufactured by the manufacturing method of the present invention is used in an ink jet recording method performed by applying energy to the ink and causing the ink to fly. As the energy, thermal energy or mechanical energy can be used, but it is preferable to use thermal energy.

  In the ink jet recording method of the present invention, the recording material is not limited, but ink is received on at least one surface such as so-called ink jet exclusive paper, postcards and business card paper, label paper, cardboard paper, and ink jet film. A recording material having a coating layer is preferably used. As the recording material having a coating layer, a recording material having a coating layer for receiving ink on at least one surface containing at least a hydrophilic polymer and / or an inorganic porous material is desirable.

  As an inkjet recording apparatus that performs recording using the ink manufactured by the manufacturing method of the present invention, a general household printer mainly used for A4 size paper, a printer for printing business cards and cards, or a commercial printer An example of a suitable ink jet recording apparatus will be described below.

(Inkjet recording device using thermal energy)
FIG. 2 is a diagram illustrating an example of the ink cartridge 100 that stores ink supplied to the head via the ink supply tube 104. Reference numeral 101 denotes an ink bag containing supply ink, and a stopper 102 made of chlorinated butyl rubber is provided at the tip thereof. By inserting the needle 103 into the stopper 102, the ink in the ink bag 101 can be supplied to the recording heads (303 to 306). An ink absorber that receives waste ink may be provided in the ink cartridge. The ink jet recording apparatus used in the present invention is not limited to the one in which the recording head and the ink cartridge are separated as described above, and an apparatus in which they are integrated is also preferably used.

  FIG. 3 is a schematic diagram for explaining the structure of the ink jet recording head used in this embodiment. Each nozzle 202 is provided with a corresponding heating element 204 (heater), which is heated by applying a predetermined driving pulse from the recording head driving circuit to the heater 204 to generate air bubbles. Ink droplets are discharged from the discharge port 202. The heater 204 is formed on the silicon substrate 206 by the same method as in the semiconductor manufacturing process. Reference numeral 203 denotes a nozzle partition that constitutes each nozzle 202, 205 denotes a common liquid chamber for supplying ink to each nozzle 202, and 207 denotes a top plate.

  A partial perspective view of the recording apparatus according to the present embodiment is shown in FIG. The recording paper 302 of the recording apparatus 300 is supplied from, for example, a roll supply unit 301 and is continuously conveyed by a conveyance unit provided in the main body of the recording apparatus 300. The transport unit includes a transport motor 312 and a transport belt 313. For recording, when the image cutout position of the recording medium passes under the black recording head 303, the black ink starts to be ejected from the recording head. Similarly, the ink of each color is selected in the order of cyan 304, magenta 305, and yellow 306. The color image is formed.

  In addition, the recording apparatus 300 includes a cap mechanism 311 that caps each recording head during standby, ink cartridges 307 to 310 for supplying ink to the recording heads 303 to 306, and a pump for supplying and recovering ink. A unit (not shown), a control board (not shown) for controlling the entire recording apparatus, and the like are included.

  FIG. 5 is a schematic diagram of a recovery processing system in the ink jet recording apparatus used in this embodiment. When the recording heads 303 to 306 are lowered, a predetermined recovery operation can be performed when the ink discharge port forming surface comes close to the cap 400 formed of chlorinated butyl rubber in the cap mechanism 311.

  In the recovery processing system, the ink regeneration circuit unit stores between the ink cartridge 100 in which replenished ink is stored and accommodated in a polyethylene bag, a sub tank 401 connected via a suction pump 403, and the like, and between the cap 400 and the sub tank 401. A suction pump 403 that is disposed in an ink supply path 409 formed of vinyl chloride to be connected and collects ink from the cap mechanism 311 in the sub tank 401, a filter 405 that removes dust and the like in the ink collected from the cap, and an ink supply path 408 The main components are a pressurizing pump 402 that supplies ink to the common liquid chambers of the recording heads 303 to 306, an ink supply path 407 that supplies ink returned from the recording head to the sub tank 401, and valves 404a to 404d. It is configured.

  When the recording heads 303 to 306 are cleaned, the recovery valve 404b is closed and the pressurizing pump 402 is operated to pressurize and supply ink from the sub tank 401 to the recording head and forcibly discharge the ink from the nozzle 406. As a result, bubbles, ink, dust and the like in the nozzles of the recording head are discharged. The suction pump 403 collects the ink discharged from the recording head into the cap mechanism 311 in the sub tank 401.

(Inkjet recording device using mechanical energy)
Next, as a preferable example of an ink jet recording apparatus using mechanical energy, a nozzle forming substrate having a plurality of nozzles, a pressure generating element made of a piezoelectric material and a conductive material disposed opposite to the nozzles, and the pressure An on-demand ink jet recording head that includes ink that fills the periphery of the generating element, displaces the pressure generating element by an applied voltage, and discharges a small droplet of ink from a nozzle can be exemplified. An example of the configuration of a recording head, which is the main part of the recording apparatus, is shown in FIG.

  The head includes an ink flow path 80 communicating with an ink chamber (not shown), an orifice plate 81 for ejecting ink droplets of a desired volume, a vibration plate 82 that directly applies pressure to ink, and the vibration plate 82. And a substrate 84 for indicating and fixing the orifice plate 81, the vibration plate 82, and the like.

  In FIG. 6, an ink flow path 80 is formed of a photosensitive resin or the like, an orifice plate 81 is formed with a discharge port 85 by drilling a metal such as stainless steel or nickel by electroforming or pressing, and the diaphragm 82 is The piezoelectric element 83 is formed of a dielectric material such as barium titanate or PZT. The piezoelectric element 83 is formed of a metal film such as stainless steel, nickel, or titanium and a highly elastic resin film. The recording head configured as described above applies a pulsed voltage to the piezoelectric element 83 to generate strain stress, and the energy deforms the vibration plate 82 bonded to the piezoelectric element 83, so that the inside of the ink flow path 80. An operation is performed so as to perform recording by pressurizing the ink vertically and ejecting ink droplets (not shown) from the ejection port 85 of the orifice plate 81.

  Hereinafter, the present invention will be described in detail based on examples. The present invention is not limited to these examples. In the text, “part” and “%” are based on mass unless otherwise specified.

[Example 1]
(Preparation of polymer dispersant A)
Synthesis of AB type diblock copolymer comprising hydrophobic block and hydrophilic block:
After the inside of the glass container fitted with the three-way cock was replaced with nitrogen, the adsorbed water was removed by heating at 250 ° C. in a nitrogen gas atmosphere. After returning the system to room temperature, 12 mmol of 2-decanoxyethyl vinyl ether, 16 mmol of ethyl acetate, 0.1 mmol of 1-isobutoxyethyl acetate, and 11 cm ³ of toluene were added, and the system temperature reached 0 ° C. By the way, 0.2 mmol of ethylaluminum sesquichloride was added to initiate polymerization, and the A component of the AB type diblock copolymer was synthesized.

The molecular weight was monitored in a time-sharing manner using molecular sieve column chromatography (GPC), and after the polymerization of component A was completed, the carboxylic acid part of 4- (2-vinyloxyethoxy) benzoic acid (component B) was Synthesis was carried out by adding 12 mmol of vinyl monomer esterified with an ethyl group. The polymerization reaction was stopped by adding a 0.3% ammonia / methanol solution to the system, and the esterified carboxyl group was hydrolyzed with a sodium hydroxide / methanol solution to change to a carboxylic acid type. Diluted by adding dichloromethane to the mixed solution after the reaction, washed 3 times with 0.6N hydrochloric acid solution, then 3 times with distilled water, concentrated and dried with an evaporator, vacuum dried, AB type di- A block copolymer (polymer dispersant A) was obtained. The compound was identified by NMR and GPC (Mn = 3.5 × 10 ⁴ , Mw / Mn = 1.2 Mn; number average molecular weight, Mw; weight average molecular weight).

(Preparation of colorant dispersion A)
10.0 parts of carbon black (MA100 manufactured by Mitsubishi Chemical Corporation), which is a commercially available pigment as a water-insoluble colorant, and 90.0 parts of tetrahydrofuran as a water-soluble organic solvent are mixed. 10.0 parts of molecular dispersant A was added, and the mixture was heated to 40 ° C. and stirred well so as to dissolve uniformly, thereby obtaining a tetrahydrofuran solution containing a water-insoluble colorant and a polymer dispersant. Next, 100 parts of an aqueous potassium hydroxide solution containing potassium corresponding to the equivalent of the unneutralized anionic hydrophilic group of the polymer dispersant used was added to the tetrahydrofuran solution. Thereafter, tetrahydrofuran was removed by a rotary evaporator, and a colorant dispersion A was obtained. The tetrahydrofuran concentration in the solution at this time was analyzed by gas chromatography, but it was not detected, and the result was judged not to remain in the solution. The obtained colorant dispersion A had a pH value of 9.08.

(Preparation of ink 1)
The above-mentioned colorant dispersion liquid A was left in a thermostatic bath at 70 ° C. in a sealed state for 7 days, and was subjected to heat treatment. The pH value after the heat treatment was measured and found to be 8.21. ... 1st process Subsequently, 48.0 parts of coloring material dispersion A obtained at the 1st process, 6.0 parts of glycerol, 6.0 parts of triethylene glycol, 6.0 parts of dipropylene glycol, 0.001% An aqueous aluminum hydroxide solution (0.1 part) and ion-exchanged water (33.9 parts) were mixed, and stirred well with a magnetic stirrer to effect ink formation. The resulting ink had a pH value of 8.25. ... 2nd process Then, it pressure-filtered with the filter of 3 micrometers, and was set as the target ink 1. ... Third process

[Example 2]
(Preparation of colorant dispersion B)
C. is a commercially available pigment as a water-insoluble colorant. I. 10.0 parts of Pigment Yellow 128 and 90.0 parts of tetrahydrofuran as a water-soluble organic solvent were mixed, and 10.0 parts of the polymer dispersant A used in Example 1 was added as a polymer dispersant to the mixed solution. Then, the mixture was heated to 40 ° C. and stirred well so as to be dissolved uniformly to obtain a tetrahydrofuran solution containing a water-insoluble colorant and a polymer dispersant.

  Next, 100 parts of an aqueous sodium hydroxide solution containing sodium corresponding to the equivalent of the unneutralized anionic hydrophilic group of the polymer dispersant used was added to the tetrahydrofuran solution. Thereafter, tetrahydrofuran was removed with a rotary evaporator, and a colorant dispersion B was obtained. The tetrahydrofuran concentration in the solution at this time was analyzed by gas chromatography, but it was not detected, and the result was judged not to remain in the solution. The resulting colorant dispersion B had a pH value of 8.82.

(Preparation of ink 2)
The colorant dispersion B was sealed and kept in a constant temperature bath at 80 ° C. for 3 days, followed by heat treatment. It was 8.43 when the pH value after heat processing was measured. ... 1st process Subsequently, 48.0 parts of coloring material dispersion B obtained at the 1st process, 6.0 parts of glycerol, 6.0 parts of triethylene glycol, 6.0 parts of dipropylene glycol, polyoxyethylene ( 10) 0.1 part of acetylenic glycol ether (average addition weight of ethylene oxide 65, average addition number 10 or less), 0.1 part of 0.001% aluminum hydroxide aqueous solution, and 33.8 parts of ion-exchanged water were mixed. Then, the mixture was stirred well with a magnetic stirrer to make an ink. ... 2nd process Sodium hydroxide aqueous solution was added to the ink obtained at the 2nd process, and pH adjustment was performed. The pH value was adjusted to 8.80. Thereafter, the target ink 2 was obtained by pressure filtration with a 3 μm filter. ... Third process

[Example 3]
(Preparation of colorant dispersion C)
C. is a commercially available pigment as a water-insoluble colorant. I. 10.0 parts of Pigment Red 122 and 90.0 parts of tetrahydrofuran as a water-soluble organic solvent were mixed, and 10.0 parts of the polymer dispersant A used in Example 1 was added as a polymer dispersant to the mixed solution. Then, the solution was heated to 40 ° C. and stirred well so as to be dissolved uniformly to obtain a tetrahydrofuran solution containing a water-insoluble colorant and a polymer dispersant.

  Next, 100 parts of an aqueous sodium hydroxide solution containing sodium corresponding to the equivalent of the unneutralized anionic hydrophilic group of the polymer dispersant used was added to the tetrahydrofuran solution. Thereafter, tetrahydrofuran was removed by a rotary evaporator, and a colorant dispersion C was obtained. The tetrahydrofuran concentration in the solution at this time was analyzed by gas chromatography, but it was not detected, and the result was judged not to remain in the solution. The obtained colorant dispersion C had a pH value of 8.90.

(Preparation of ink 3)
A sodium hydroxide aqueous solution was added to the colorant dispersion C, and the mixture was well stirred with a magnetic stirrer. The pH value was measured and found to be 9.95. This colorant dispersion C was left to stand in a thermostatic bath at 60 ° C. for 3 days in a sealed state, and heat treatment was performed. The pH value after the heat treatment was measured and found to be 9.45. ... First step

Next, 36.0 parts of colorant dispersion C obtained in the first step, 8.0 parts of glycerin, 6.0 parts of triethylene glycol, 6.0 parts of dipropylene glycol, polyoxyethylene (10) acetylenic glycol 0.1 part of ether, 0.1 part of 0.001% aluminum hydroxide aqueous solution and 43.8 parts of ion-exchanged water were mixed, and stirred well with a magnetic stirrer to make an ink. The obtained ink had a pH value of 9.48. ... 2nd process Then, it pressure-filtered with a 3 micrometers filter, and was set as the target ink 3. ... Third process

[Example 4]
(Preparation of colorant dispersion D)
C. is a commercially available pigment as a water-insoluble colorant. I. 10.0 parts of Pigment Blue 15: 3 and 90.0 parts of tetrahydrofuran as a water-soluble organic solvent were mixed, and 10.0 parts of the polymer dispersant A used in Example 1 was added as a polymer dispersant to the mixed solution. Then, the mixture was heated to 40 ° C. and stirred well so as to be dissolved uniformly to obtain a tetrahydrofuran solution containing a water-insoluble colorant and a polymer dispersant.

  Subsequently, 100 parts of lithium hydroxide aqueous solution containing lithium corresponding to the equivalent of the unneutralized anionic hydrophilic group of the used polymer dispersant was added to the tetrahydrofuran solution. Thereafter, tetrahydrofuran was removed by a rotary evaporator, and a colorant dispersion D was obtained. The tetrahydrofuran concentration in the solution at this time was analyzed by gas chromatography, but it was not detected, and the result was judged not to remain in the solution. The pH value of the obtained color material dispersion D was 8.68.

(Preparation of ink 4)
A lithium hydroxide aqueous solution was added to the colorant dispersion D, and the mixture was well stirred with a magnetic stirrer. The pH value was measured and found to be 9.50. The coloring material dispersion D was left in a thermostatic bath at 80 ° C. in a sealed state for 7 days, and heat treatment was performed. It was 8.38 when pH value after heat processing was measured. ... First step

Next, an aqueous lithium hydroxide solution was added to the colorant dispersion D obtained in the first step, and the mixture was well stirred with a magnetic stirrer. The pH value was measured and found to be 9.50. ... 4th process 30.0 parts of this colorant dispersion D, 8.0 parts of glycerin, 6.0 parts of diethylene glycol, 6.0 parts of trimethylolpropane, 0.5 polyoxyethylene (10) acetylenic glycol ether Part, 0.001% aluminum hydroxide aqueous solution 0.1 part and ion-exchanged water 49.4 parts were mixed and stirred well with a magnetic stirrer to make an ink. The obtained ink had a pH value of 9.50. ... 2nd process Then, it pressure-filtered with a 3 micrometers filter, and was set as the target ink 4. ... Third process

[Example 5]
(Preparation of polymer dispersant B)
Synthesis of ABC type triblock copolymer composed of hydrophobic block and two hydrophilic blocks:
After the inside of the glass container fitted with the three-way cock was replaced with nitrogen, the adsorbed water was removed by heating at 250 ° C. in a nitrogen gas atmosphere. After returning the system to room temperature, 12 mmol of n-octadecyl vinyl ether, 16 mmol of ethyl acetate, 0.1 mmol of 1-isobutoxyethyl acetate, and 11 cm ³ of toluene were added, and when the system temperature reached 0 ° C., ethyl aluminum Polymerization was started by adding 0.2 mmol of sesquichloride, and the A component of the ABC type triblock copolymer was synthesized.

The molecular weight was monitored in a time-sharing manner using molecular sieve column chromatography (GPC), and after the polymerization of component A was completed, 2- (2- (2- (2-methoxyethoxy) ethoxy) ethoxy) ethoxyvinyl ether ( Polymerization was continued by adding 24 mmol of component B). Similarly, the molecular weight was monitored by GPC, and after the polymerization of the B component was completed, 12 mmol of vinyl monomer obtained by esterifying the carboxylic acid part of 6- (2-vinyloxyethoxy) hexanoic acid (C component) with an ethyl group The synthesis was performed by adding The polymerization reaction was stopped by adding a 0.3% ammonia / methanol solution to the system, and the esterified carboxyl group was hydrolyzed with a sodium hydroxide / methanol solution to change to a carboxylic acid type. Thereafter, an ABC type triblock copolymer (polymer dispersing agent B) was obtained in the same manner as in Example 1. The compound was identified using NMR and GPC (Mn = 3.7 × 10 ⁴ , Mw / Mn = 1.2 Mn; number average molecular weight, Mw; weight average molecular weight).

(Preparation of colorant dispersion E)
10.0 parts of carbon black (Printex 85 manufactured by Degussa), which is a commercially available pigment as a water-insoluble colorant, and 90.0 parts of tetrahydrofuran as a water-soluble organic solvent are mixed, and this mixture solution is mixed with the above as a polymer dispersant. 4.0 parts of Polymer Dispersant B was added and stirred well so that it was heated to 40 ° C. and dissolved uniformly to obtain a tetrahydrofuran solution containing a water-insoluble colorant and a polymer dispersant.

  Subsequently, 100 parts of lithium hydroxide aqueous solution containing lithium corresponding to the equivalent of the unneutralized anionic hydrophilic group of the used polymer dispersant was added to the tetrahydrofuran solution. Thereafter, tetrahydrofuran was removed by a rotary evaporator, and a colorant dispersion E was obtained. The tetrahydrofuran concentration in the solution at this time was analyzed by gas chromatography, but it was not detected, and the result was judged not to remain in the solution. The pH value of the obtained colorant dispersion E was 8.55.

(Preparation of ink 5)
The above-mentioned color material dispersion E was kept in a thermostatic bath at 70 ° C. for 1 day in a sealed state and subjected to heat treatment. It was 8.30 when pH value after a heat processing was measured. ... 1st process Next, after adding lithium hydroxide aqueous solution to the coloring material dispersion liquid obtained at the 1st process and adjusting pH value to 8.55, it left still in a 70 degreeC thermostat for 1 day again. The operation of performing the heat treatment (pH adjustment-heat treatment) was repeated twice. ... First step, fourth step

  Subsequently, 57.0 parts of this colorant dispersion E, 12.0 parts of glycerin, 6.0 parts of diethylene glycol, 6.0 parts of trimethylolpropane, 0.1 part of polyoxyethylene (10) acetylenic glycol ether, 0.02 part of a 001% aluminum hydroxide aqueous solution and 18.88 parts of ion-exchanged water were mixed and stirred well with a magnetic stirrer to make an ink. ... Second process

A lithium hydroxide aqueous solution was added to the ink obtained in the second step to adjust the pH. The pH value was adjusted to 8.90. ... 5th process Then, it pressure-filtered with a 3 micrometers filter, and was set as the target ink 5. ... Third process

[Example 6]
(Preparation of colored dispersion F)
10.0 parts of carbon black (Printex 85 manufactured by Degussa), which is a commercially available pigment as a water-insoluble colorant, and 90.0 parts of tetrahydrofuran as a water-soluble organic solvent are mixed, and this mixture solution is used as a polymer dispersant. 10.0 parts of the polymer dispersant B used in Example 5 was added, and the mixture was heated to 40 ° C. and stirred well so as to dissolve uniformly. A tetrahydrofuran solution containing the water-insoluble colorant and the polymer dispersant was then added. Obtained.

  Next, 100 parts of an aqueous sodium hydroxide solution containing sodium corresponding to the equivalent of the unneutralized anionic hydrophilic group of the polymer dispersant used was added to the tetrahydrofuran solution. Thereafter, tetrahydrofuran was removed with a rotary evaporator, and a colorant dispersion F was obtained. The tetrahydrofuran concentration in the solution at this time was analyzed by gas chromatography, but it was not detected, and the result was judged not to remain in the solution. The pH value of the obtained colorant dispersion F was 9.44.

(Preparation of ink 6)
The above-mentioned color material dispersion F was left to stand in a thermostatic bath at 60 ° C. for 30 days in a sealed state and subjected to heat treatment. It was 8.39 when the pH value after heat processing was measured. ... 1st process Next, sodium hydroxide aqueous solution was added to the color material dispersion obtained at the 1st process, and pH value was adjusted to 9.45. ... Fourth process

Subsequently, 24.0 parts of this colorant dispersion F, 6.0 parts of glycerin, 6.0 parts of diethylene glycol, 6.0 parts of trimethylolpropane, 0.1 part of polyoxyethylene (10) acetylenic glycol ether, 0.2 parts of a 001% aluminum hydroxide aqueous solution and 57.7 parts of ion-exchanged water were mixed and stirred well with a magnetic stirrer to effect ink formation. The obtained ink had a pH value of 9.49. ... 2nd process Then, it pressure-filtered with the filter of 3 micrometers, and was set as the target ink 6. ... Third process

[Example 7]
(Preparation of colorant dispersion G)
C. is a commercially available pigment as a water-insoluble colorant. I. 10.0 parts of Pigment Blue 15: 3 and 90.0 parts of tetrahydrofuran as a water-soluble organic solvent were mixed, and 15.0 parts of the polymer dispersant B used in Example 5 was added to this mixed solution, The mixture was stirred well so as to dissolve uniformly, and a tetrahydrofuran solution containing a water-insoluble colorant and a polymer dispersant was obtained.

  Next, 100 parts of an aqueous sodium hydroxide solution containing sodium corresponding to the equivalent of the unneutralized anionic hydrophilic group of the polymer dispersant used was added to the tetrahydrofuran solution. Thereafter, tetrahydrofuran was removed by a rotary evaporator, and a colorant dispersion G was obtained. The tetrahydrofuran concentration in the solution at this time was analyzed by gas chromatography, but it was not detected, and the result was judged not to remain in the solution. The pH value of the obtained color material dispersion G was 9.77.

(Preparation of ink 7)
The above-mentioned colorant dispersion liquid G was allowed to stand in a thermostatic bath at 60 ° C. for 10 days in a sealed state and subjected to heat treatment. It was 8.99 when the pH value after heat processing was measured. ... 1st process Next, after adding sodium hydroxide aqueous solution to the coloring material dispersion liquid obtained at the 1st process and adjusting pH value to 9.77, it left still in a 60 degreeC thermostat for 10 days again. The operation of performing the heat treatment (pH adjustment-heat treatment) was repeated twice. ... First step, fourth step

Next, 37.5 parts of this colorant dispersion G, 8.0 parts of glycerin, 6.0 parts of triethylene glycol, 6.0 parts of dipropylene glycol, 0.2 part of polyoxyethylene (10) acetylenic glycol ether, 0.1 part of 0.001% aluminum hydroxide aqueous solution and 42.2 parts of ion-exchanged water were mixed and stirred well with a magnetic stirrer to make an ink. The obtained ink had a pH value of 9.02. ... 2nd process Then, it pressure-filtered with a 3 micrometers filter, and was set as the target ink 7. ... Third process

[Example 8]
(Preparation of colorant dispersion H)
C. is a commercially available pigment as a water-insoluble colorant. I. 10.0 parts of Pigment Blue 15: 3 and 90.0 parts of tetrahydrofuran as a water-soluble organic solvent were mixed, and 10.0 parts of the polymer dispersant B used in Example 5 was added to this mixed solution, The mixture was stirred well so as to dissolve uniformly, and a tetrahydrofuran solution containing a water-insoluble colorant and a polymer dispersant was obtained.

  Subsequently, 100 parts of lithium hydroxide aqueous solution containing lithium corresponding to the equivalent of the unneutralized anionic hydrophilic group of the used polymer dispersant was added to the tetrahydrofuran solution. Thereafter, tetrahydrofuran was removed by a rotary evaporator, and a colorant dispersion H was obtained. The tetrahydrofuran concentration in the solution at this time was analyzed by gas chromatography, but it was not detected, and the result was judged not to remain in the solution. The obtained colorant dispersion H had a pH value of 9.15.

(Preparation of ink 8)
The pH value was adjusted to 9.70 by adding a lithium hydroxide aqueous solution to the colorant dispersion H. Then, this coloring material dispersion was left to stand in a thermostatic bath at 60 ° C. for 10 days in a sealed state and subjected to a heat treatment. It was 8.90 when pH value after a heat processing was measured. ... First step

Next, an operation in which an aqueous lithium hydroxide solution is added to the colorant dispersion obtained in the first step to adjust the pH value to 9.70, and then left in a constant temperature bath at 60 ° C. for 10 days to perform a heat treatment. (PH adjustment-heat treatment) was repeated twice. ... 1st process, 4th process Next, this coloring material dispersion H42.0 part, 10.0 parts of glycerol, 6.0 parts of diethylene glycol, 6.0 parts of trimethylol propane, polyoxyethylene (10) acetylene 0.1 parts of nick glycol ether, 0.1 part of 0.001% aluminum hydroxide aqueous solution and 35.8 parts of ion-exchanged water were mixed and stirred well with a magnetic stirrer to effect ink formation. The resulting ink had a pH value of 9.15. ... 2nd process Then, it pressure-filtered with the filter of 3 micrometers, and was set as the target ink 8. ... Third process

[Comparative Example 1]
(Preparation of ink 9)
Color material dispersion B 48.0 parts, glycerin 6.0 parts, triethylene glycol 6.0 parts, dipropylene glycol 6.0 parts, polyoxyethylene (10) acetylenic glycol ether used in Example 2 1 part, 0.1 part of 0.001% aluminum hydroxide aqueous solution and 33.8 parts of ion-exchanged water were mixed, and stirred well with a magnetic stirrer to make an ink. The resulting ink had a pH value of 8.89. Thereafter, the mixture was filtered under pressure with a 3 μm filter to obtain ink 9.

[Comparative Example 2]
(Preparation of colorant dispersion I)
A colorant dispersion I was obtained in the same manner as in Example 2 except that a styrene-maleic acid random copolymer (number average molecular weight 10,000) was used as the polymer dispersant.

(Preparation of ink 10)
48.0 parts of the above colorant dispersion I, 6.0 parts of glycerin, 6.0 parts of triethylene glycol, 6.0 parts of dipropylene glycol, 0.1 part of polyoxyethylene (10) acetylenic glycol ether, ion exchange 33.9 parts of water was mixed and stirred well with a magnetic stirrer to effect ink formation. The obtained ink had a pH value of 9.50. Thereafter, the ink was pressure filtered through a 3 μm filter to obtain ink 10.

[Comparative Example 3]
(Preparation of colorant dispersion J)
Carbon black (MA100 manufactured by Mitsubishi Chemical), a commercially available pigment as a water-insoluble colorant, styrene-maleic acid random copolymer (number average molecular weight 10,000) as a polymer dispersant, and anionic property of the polymer dispersant A colorant dispersion J was obtained in the same manner as in Example 2 except that potassium hydroxide was used as the neutralizing agent for the hydrophilic group.

(Preparation of ink 11)
48.0 parts of the above colorant dispersion J, 6.0 parts of glycerin, 6.0 parts of triethylene glycol, 6.0 parts of dipropylene glycol, 0.1 part of polyoxyethylene (10) acetylenic glycol ether, ion exchange 33.9 parts of water was mixed and stirred well with a magnetic stirrer to effect ink formation. The obtained ink had a pH value of 9.81. Thereafter, the ink was filtered under pressure with a 3 μm filter to obtain ink 11.

[Comparative Example 4]
(Preparation of ink 12)
The colorant dispersion J used in Comparative Example 3 was allowed to stand in a thermostatic bath at 70 ° C. for 10 days in a sealed state and subjected to heat treatment. It was 9.89 and 8.20 when the pH value before heat processing and after heat processing was measured, respectively.

48.0 parts of this colorant dispersion J, 6.0 parts of glycerin, 6.0 parts of triethylene glycol, 6.0 parts of dipropylene glycol, 0.1 part of polyoxyethylene (10) acetylenic glycol ether, ion exchange 33.9 parts of water was mixed and stirred well with a magnetic stirrer to effect ink formation. The resulting ink had a pH value of 8.23.
Thereafter, the ink 12 was pressure filtered through a 3 μm filter to obtain ink 12.

(Evaluation)
Tests were performed on the dispersion stability of the inks of Examples 1 to 8 and the inks of Comparative Examples 1 to 4 and the ejection stability of these inks. As for ejection stability, an inkjet recording apparatus P-660CII (Canon Finetech Co., Ltd.) having an on-demand type multi-recording head that ejects ink by applying thermal energy corresponding to the recording signal to each ink. And printed on glossy paper SP101 (manufactured by Canon Inc.) for evaluation. As a result, as shown in Table 1, the inks of any of the examples showed results showing better dispersion stability and ejection stability than the inks of the comparative examples. In addition, all of the inks of the examples had good results for the scratch resistance of the printed image.

* 1: Dispersion stability After each ink was stored in a sealed state at 80 ° C for 2 weeks, a thermal stability test was further performed in an open state at 100 ° C for 4 hours, and the particle size before and after the test was measured. The particle diameter increase rate (%) was determined and used as a measure of dispersion stability. A dynamic light scattering method (trade name: Laser particle size analysis system PARIII; manufactured by Otsuka Electronics Co., Ltd.) was used for the measurement of the particle size. The evaluation criteria were as follows.

◎：粒子径増加率（％）が５％未満である。
○：粒子径増加率（％）が５％以上１０％未満である。
△：粒子径増加率（％）が１０％以上３０％未満である。
×：粒子径増加率（％）が３０％以上である。

A: The particle diameter increase rate (%) is less than 5%.
○: The particle diameter increase rate (%) is 5% or more and less than 10%.
Δ: Particle diameter increase rate (%) is 10% or more and less than 30%.
X: The particle diameter increase rate (%) is 30% or more.

* 2: Ejection stability After each ink is stored at 60 ° C for 2 months, 1,000 postcard-size gradation patterns are printed continuously. Evaluation based on the criteria.
A: Printed normally without twisting or non-discharge.
○: No discharge occurred, but some irregularities were observed.
Δ: Some undischarge occurred, and a twist was observed in the entire image.
X: Many undischarge occurred, and twist is seen in the whole image.

  The present invention is to produce an ink that can provide an image that has little fluctuation in pH value, does not impair ejection stability even in continuous printing over a long period of time, and has good fastness and color development of a printed image. Furthermore, it is possible to provide an ink jet recording method, an ink cartridge, and an ink jet recording apparatus capable of stably recording an image having good ejection performance and fastness and quality at any time.

It is a flowchart figure of the manufacturing method of an ink. It is a schematic diagram for demonstrating the structure of an ink cartridge. It is a schematic diagram for demonstrating the structure of an inkjet recording head. It is a perspective view of an inkjet recording device. It is the schematic of the recovery processing system in an inkjet recording device. It is a schematic sectional drawing which shows another structural example of an inkjet recording head.

Explanation of symbols

100: ink cartridge 101: ink bag 102: rubber stopper 103: needle 104: tube 201: base plate 202: ink nozzle (discharge port)
203: Partition 204 Nozzle heater 205: Common liquid chamber 206: Substrate 207: Top plate 300: Recording device 301: Roll supply unit 302: Recording medium (roll paper)
303: Recording head (black)
304: Recording head (cyan)
305: Recording head (magenta)
306: Recording head (yellow)
307: Ink cartridge (black)
308: Ink cartridge (cyan)
309: Ink cartridge (magenta)
310: Ink cartridge (yellow)
311: Cap mechanism 312: Conveying motor 313: Conveying belt 400: Cap 401: Sub tank 402: Pressurizing pump 403: Suction pump 404 a: Supply valve 404 b: Recovery valve 404 c: Atmospheric release valve 404 d: Recycling valve 405: Filter 406: Face (Nozzle) surface 80: ink flow path 81: orifice plate 82: diaphragm 83: piezoelectric element 84: substrate 85: discharge port

Claims (19)

A colorant-dispersed ink jet mainly composed of a polymer dispersant comprising a block copolymer composed of a hydrophilic block having an anionic hydrophilic group and a hydrophobic block, a water-insoluble colorant, a water-soluble organic solvent, and water. In a method for producing a recording ink,
(1) The first step of lowering the pH of the colorant dispersion mainly comprising the polymer dispersant, the water-insoluble colorant and water by heat treatment, and (2) the colorant dispersion obtained in the first step. An ink for inkjet recording, comprising at least a second step of mixing water and a water-soluble organic solvent to form an ink, and (3) a third step of filtering the ink obtained in the second step. Production method.   The method for producing an ink for ink jet recording according to claim 1, wherein a fourth step of adding an alkali agent to raise the pH of the colorant dispersion is performed between the first step and the second step.   The manufacturing method of the ink for inkjet recording of Claim 2 which performs a 1st process further after the said 4th process.   The method for producing an ink for inkjet recording according to claim 1, wherein a fifth step of increasing the pH of the ink by adding an alkali agent is performed between the second step and the third step.   The method for producing an ink for inkjet recording according to claim 2 or 4, wherein the alkali agent contains the same base as the neutralizing agent for the anionic hydrophilic group of the polymer dispersant.   The method for producing an ink for inkjet recording according to claim 1, wherein the anionic hydrophilic group neutralizing agent of the polymer dispersant is lithium or sodium.   The method for producing an ink for inkjet recording according to claim 1, wherein the pH of the colorant dispersion lowered by the heat treatment in the first step is 8.3 to 9.5.   2. The method for producing an ink for ink jet recording according to claim 1, wherein the pH of the colorant dispersion before being lowered by the heat treatment in the first step is 8.5 to 10.0. 3.   As a water-soluble organic solvent to be added in the second step, polyoxyethylene acetylenic glycol ethers having an average addition weight of ethylene oxide of 65 are 0.02 times in mass ratio with respect to the water-insoluble colorant in the ink. The method for producing an ink for ink jet recording according to claim 1, wherein the ink is added in a range of up to 0.2 times.   The manufacturing method of the ink for inkjet recording of any one of Claims 1-9 which contains 6.0-12.0 mass% of glycerol with respect to the ink total mass.   2. The ink jet recording according to claim 1, wherein the polymer dispersant is a block copolymer comprising a hydrophobic block composed of at least one vinyl ether and a hydrophilic block composed of at least one vinyl ether. For producing ink for use.   12. The hydrophilic block of the polymer dispersant includes at least a block composed of vinyl ethers having a nonionic hydrophilic group and a block composed of vinyl ethers having an anionic hydrophilic group. The manufacturing method of the ink for inkjet recording as described in any one of.   The polymer dispersant is composed of a block composed of a hydrophobic vinyl ether and a block composed of a hydrophilic vinyl ether having a nonionic hydrophilic group and a hydrophilic vinyl ether having an anionic hydrophilic group. The method for producing an ink for inkjet recording according to claim 12, wherein the ink is configured at least in the order of blocks.   The method for producing an inkjet recording ink according to claim 1, wherein the water-insoluble colorant is a pigment.   In the ink jet recording method performed by applying energy to the ink and causing the ink to fly to be applied to a recording material, the ink is an ink produced by the manufacturing method according to any one of claims 1 to 14. An ink jet recording method, comprising:   The inkjet recording method according to claim 15, wherein the energy is thermal energy.   16. The ink jet recording method according to claim 15, wherein the recording material is a recording material having a coating layer for receiving ink on at least one surface.   An ink cartridge comprising an ink containing portion containing ink, wherein the ink contains the ink produced by the manufacturing method according to claim 1.   15. An ink jet recording apparatus comprising an ink cartridge comprising an ink containing part containing ink and a head part for ejecting the ink, wherein the ink is produced by the manufacturing method according to claim 1. An ink jet recording apparatus comprising the produced ink.

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