JP2003147235A - Ink-jet pigment ink and ink-jet cartridge using the same, ink-jet image printing method and ink-jet printed image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink-jet pigment ink giving ink-jet printed images with high fretting resistance, glossiness and water resistance, to provide an ink-jet cartridge using the same, to provide an ink-jet image printing method, and to provide ink-jet printed images given by the method. SOLUTION: The ink-jet pigment ink is obtained by dispersing pigment particle in an aqueous medium, wherein the total content of fatty acids and their salts in this ink is <=0.5 mass%, and the surfaces of the pigment particles are coated with a water-insoluble and water-dispersible polymer layer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an inkjet pigment ink, an inkjet cartridge using the same, an inkjet image recording method, and an inkjet recorded image.

[0002]

2. Description of the Related Art Ink jet recording is a technique for ejecting minute droplets of ink by various operating principles and adhering them to a recording medium to record images, characters, etc. It has an advantage that it can be easily colored.

In addition, due to recent technological advances, ink jet printing using dye ink is accelerating its widespread use with the high image quality approaching that of silver halide photography and the cost reduction of the apparatus.

The dye is soluble in a solvent, and the dye molecule is colored in a molecular state or a cluster state. Therefore,
Since the environment of each molecule is similar, its absorption spectrum is sharp, and it exhibits high purity and vivid color. Furthermore, since there is no granular pattern due to particles and scattered light or reflected light does not occur, it is possible to obtain an inkjet image having high gloss and transparency and a clear hue. Further, since there are no coloring material particles on the surface, the abrasion resistance is excellent.

On the other hand, however, when the molecules are destroyed by a photochemical reaction or the like, the decrease in the number of molecules is reflected in the coloring density as it is, so that the light resistance is poor. Furthermore, it has a property of poor water resistance such as storage under high humidity. Although an ink jet recorded image using a dye ink has a high image quality, the image quality is largely deteriorated due to storage over time, and a technique that surpasses silver salt photography from the viewpoint of image storability has not yet appeared.

In contrast to dye inks, pigment inks using pigments having good light resistance as colorants are used as inks for applications requiring an image resistant to fading by light. However, since pigments are present as pigment particles as compared with dyes, they are more susceptible to light scattering, give an image without transparency, have poor scratch resistance, and have the drawbacks that dyes do not have in terms of color reproducibility. It was

As mentioned above, the dye ink has a scratch resistance,
Although it has excellent glossiness, it is inferior in light resistance and water resistance, and conversely, the pigment ink has conflicting characteristics that it is excellent in light resistance but inferior in scratch resistance and glossiness.

In order to overcome this drawback, it has been attempted to improve the color reproduction by preparing a pigment ink having a small dispersed particle size as a pigment particle by dispersing as a pigment particle. However, generally, the smaller the primary particles, the more difficult it is to secure the dispersion and stability of the pigment, and there is a bad influence such as an increase in viscosity. As a technique for avoiding this, for example, a polymer-coated pigment in which the surface of pigment particles is coated with a polymer compound having dispersibility is known.

The above-mentioned polymer-coated pigment is disclosed in, for example, Japanese Patent Laid-Open No.
No. 71405, a method of dispersing pigment particles with a polymer compound, dissolving the polymer compound in an organic solvent and then phase inversion emulsification in water, Coloring Materials Association, 70, 503 (199).
After adsorbing a monomer on the surface of the pigment particle according to 7),
Method of polymerizing, Journal of Coloring Materials, 69, 743 (199
6) and 72, 748 (1999), a method of introducing a polymerization initiator to the surface of the pigment particle and then polymerizing it with a monomer, etc., which forms a strong polymer film on the surface of the pigment particle. Since the free high molecular compound does not exist in the pigment ink, a pigment ink having high dispersion stability can be obtained.

However, although the pigment particles obtained by the method described above all have high dispersion stability, the ink jet formed image formed by the pigment particles is
The image quality is not satisfactory in terms of glossiness, scratch resistance, water resistance, etc., and further technical improvement is required.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide an ink jet pigment ink excellent in scratch resistance, glossiness and water resistance of an ink jet recorded image, and the ink jet pigment ink. It is to provide an inkjet cartridge, an inkjet image recording method, and an inkjet recorded image used.

[0012]

The above objects of the present invention have been achieved by the following constitutions.

1. In an inkjet pigment ink in which pigment particles are dispersed in an aqueous medium, the total content of fatty acids and fatty acid salts in the inkjet pigment ink is 0.5% by mass or less, and the surface of the pigment particles is water-insoluble. An inkjet pigment ink, which is coated with a water-dispersible polymer layer.

2. Item 2. The inkjet pigment ink according to Item 1, wherein the redispersion coefficient represented by the formula (1) is 0.5 to 5.

3. pH is 7.0 or more, The pigment ink for inkjets of said 1 or 2 characterized by the above-mentioned.

4. 4. The inkjet pigment ink according to any one of items 1 to 3, wherein the surface tension is 25 to 45 mN / m.

5. The secondary volume average particle diameter of the pigment particles is 10 to 150 nm,
Item 5. The inkjet pigment ink according to any one of items 4.

6. 6. The inkjet pigment ink according to any one of items 1 to 5, wherein the polyvalent metal ion content is 5 ppm or less.

7. Ink solvent content is 5-70% by mass
The inkjet pigment ink according to any one of items 1 to 6, wherein:

8. Item 8. The inkjet pigment ink according to any one of items 1 to 7, which contains an anionic surfactant.

9. Item 8. The inkjet pigment ink according to any one of items 1 to 7, which contains a nonionic surfactant.

10. Item 8. The inkjet pigment ink according to any one of items 1 to 7, which contains a cationic surfactant.

11. Item 8. The inkjet pigment ink according to any one of items 1 to 7, which contains an anionic surfactant and a nonionic surfactant.

12. Item 12. The inkjet pigment ink according to any one of items 1 to 11, which contains a water-soluble polymer or a water-insoluble polymer dispersion liquid.

13. An ink jet cartridge comprising an ink containing portion containing at least one ink jet pigment ink according to any one of items 1 to 12.

14. 13. An inkjet image recording method, wherein an image is formed using at least one of the inkjet pigment inks according to any one of 1 to 12 above.

15. 13. An inkjet recorded image formed by performing inkjet image recording using at least one pigment ink for inkjet according to any one of 1 to 12 above.

The inventors of the present invention have made extensive studies as to improvement of scratch resistance, glossiness and water resistance of an output image by using a pigment ink, and as a result, as a result, an ink jet pigment ink in which pigment particles are dispersed in an aqueous medium (hereinafter, simply (Also referred to as a pigment ink), the total content of fatty acids and fatty acid salts in the pigment ink is 0.5% by mass or less, and the surfaces of the pigment particles are covered with a water-insoluble and water-dispersible polymer layer. It has been found that this can be achieved by using the existing pigment ink for inkjet.

Although the detailed effects of the configuration of the present invention on the above problems are not clear, it is presumed as follows. That is, the pigment particles are gently bonded to other pigment particles on the recording medium by interaction such as hydrogen bond or van der Waals force, and form a stable image. However, when a large amount of a fatty acid or a fatty acid salt is present, the above-mentioned binding between pigment particles is hindered, and as a result, the pigment particles easily move on the surface of the recording medium after image printing, resulting in deterioration of scratch resistance. I'm guessing. At the same time, the hydrophilicity of the surface of the particles is increased, and it is considered that the water resistance is degraded. In the present invention, it has been found that both the scratch resistance and the water resistance are improved by controlling the content of the fatty acid or the fatty acid salt to the amount specified in the present invention or less. Further, although the reason why the glossiness is improved by the constitution of the present invention is not clear, by suppressing the amount of the fatty acid or the fatty acid salt to be not more than the amount specified in the present invention, the pigment particles are bonded to each other and a proper dispersion state is obtained. It is speculated that the surface roughness could be prevented by maintaining it, and the above-mentioned effect is particularly obtained by using a pigment particle in which the particle surface is coated with a water-insoluble and water-dispersible polymer layer. It was found that the present invention was remarkably exhibited, and the present invention was completed.

JP-A-10-140065 discloses an example of a microcapsule pigment in which the surface of the pigment particle is coated with a polymer layer. In the patent, printing stability is mentioned as the effect, but there is no description about glossiness, scratch resistance or water resistance. On the other hand, Japanese Patent Application Laid-Open No. 9-3374 describes an example in which the content of fatty acid is specified in a pigment ink dispersed by using a so-called polymer dispersant. In the patent, the effect is to improve the clogging of the inkjet nozzle due to the precipitation of fatty acid during long-term storage of the ink, but there is no description regarding glossiness. As a result of additional test confirmation by the present inventors according to the constitution of the patent, the gloss, scratch resistance, and water resistance are at a completely insufficient level, and the image quality level currently required is not satisfied. There was found.

The effect of the present invention is that the redispersibility of pigment ink, pH, surface tension, pigment particle size, polyvalent metal ion content, and ink solvent amount are set within specific ranges, and a surfactant is used. It has been found that the use of a water-soluble polymer or a water-insoluble polymer dispersion makes it possible to achieve the objects and effects of the present invention.

The details of the present invention will be described below. First, the inkjet pigment ink of the present invention will be described.

In the invention according to claim 1, in an ink jet pigment ink, wherein pigment particles are dispersed in an aqueous medium,
The total content of fatty acids and fatty acid salts in the inkjet pigment ink is 0.5% by mass or less, and the surface of the pigment particles is covered with a water-insoluble and water-dispersible polymer layer. is there.

The fatty acid referred to in the present invention refers to a saturated or unsaturated alkylcarboxylic acid having 8 to 22 carbon atoms, for example, lauric acid, myristic acid, palmitic acid, oleic acid, stearic acid, behenic acid, etc. Is mentioned. The fatty acid salt in the present invention is a salt of the above fatty acid with an inorganic or organic cation, and examples thereof include sodium stearate, potassium stearate, sodium oleate, sodium palmitate, and ammonium stearate. it can.

One feature of the present invention is that the total content of the above fatty acids and fatty acid salts is 0.5% by mass or less based on the total mass of the ink, preferably 0.01 to
It is 0.3% by mass, and more preferably 0.01 to 0.
It is in the range of 1% by mass.

According to the first aspect of the invention, in an ink jet pigment ink in which pigment particles are dispersed in an aqueous medium,
One of the features is that the surface of the pigment particles is covered with a water-insoluble and water-dispersible polymer layer.

As the pigment which can be used in the present invention,
Known colored organic or colored inorganic pigments can be used. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthaloni pigments, etc. Examples include polycyclic pigments, dye lakes such as basic dye type lakes and acid dye type lakes, organic pigments such as nitro pigments, nitroso pigments, aniline black and daylight fluorescent pigments, and inorganic pigments such as carbon black. However, the present invention is not limited to these.

Specific organic pigments are exemplified below. Examples of magenta or red pigments include C.I. I.
Pigment Red 2, C.I. I. Pigment Red 3,
C. I. Pigment Red 5, C.I. I. Pigment Red 6, C.I. I. Pigment Red 7, C.I. I. Pigment Red 15, C.I. I. Pigment Red 16, C.I.
I. Pigment Red 48: 1, C.I. I. Pigment Red 53: 1, C.I. I. Pigment Red 57: 1,
C. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 139, C.I.
I. Pigment Red 144, C.I. I. Pigment Red 149, C.I. I. Pigment Red 166, C.I. I.
Pigment Red 177, C.I. I. Pigment Red 1
78, C.I. I. Pigment Red 222 and the like.

Examples of pigments for orange or yellow include C.I. I. Pigment Orange 31, C.I.
I. Pigment Orange 43, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I.
Pigment Yellow 14, C.I. I. Pigment Yellow 15, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 74, C.I. I. Pigment Yellow 9
3, C.I. I. Pigment Yellow 94, C.I. I. Pigment Yellow 128, C.I. I. Pigment Yellow 13
8 etc. are mentioned.

As the pigment for green or cyan,
For example, C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 1
5: 3, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 60, C.I. I. Pigment Green 7 and the like.

As the pigment for black, for example, C.I. I. Pigment Black 1, C.I. I. Pigment Black 6, C.I. I. Pigment Black 7 and the like.

In the present invention, the pigment particles whose surface is coated with a water-insoluble and water-dispersible polymer layer are, for example, a polymer compound (also referred to as a polymer) having a pigment particle as a core and the surface as a shell. Particles coated with, or
Examples thereof include particles in which a polymer compound particle containing a pigment particle is used as a core, and the surface thereof is used as a shell to be coated with a polymer compound.

The pigment particles whose surface is coated with the polymer compound according to the present invention can be prepared by various methods described below.

For example, a method in which pigment particles described in JP-A-8-71405 are dispersed with a polymer compound, the polymer compound is dissolved in an organic solvent, and then phase inversion emulsification is carried out in water. 503 (1997), the method of polymerizing after adsorbing a monomer on the surface of pigment particles, Journal of Coloring Materials, 69, 743 (1996) and 72, 748.
The method of introducing a polymerization initiator to the surface of the pigment particle described in (1999) and then polymerizing it with a monomer can be mentioned.

In each of the above-mentioned methods, the polymer compound which can be used in the method in which the polymer compound in which the pigment is dispersed is dissolved in an organic solvent and then phase-inversion emulsified in water is used. , -COOH, -SO ₃ H) has, is soluble in an organic solvent in the acid form, a polymer compound soluble neutralized hydrophilic increases with a basic substance such as an alkali or amine. Specific examples thereof include acrylic resin, styrene resin, polyester resin, epoxy resin, polyurethane resin, and the like, and acrylic resin and styrene resin are preferable.

As a method of polymerizing after adsorbing the monomer on the surface of the pigment particles, the pigment, the polar group-containing polymer and the hydrophobic monomer are added to the water-containing liquid, and after adsorbing the monomer for a certain period of time, the polymerization is started. It can be obtained by adding an agent and polymerizing for a certain period of time.

Examples of the polar group-containing monomer that can be used in the above method include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid,
Monobutyl itaconate, monobutyl maleate, acid phosphooxyethyl methacrylate, acid phosphooxypropyl methacrylate, 3-chloro-2-acid phosphooxypropyl methacrylate, 2-acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl methacrylate, etc. Can be mentioned.

As the hydrophobic monomer, for example, various styrene-based monomers (aromatic vinyl monomers) such as styrene, vinyltoluene, 2-methylstyrene, t-butylstyrene or chlorostyrene; methyl acrylate, Ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-acrylate
Various acrylates such as hexyl, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate or dodecyl acrylate; methyl methacrylate, propyl methacrylate, n-methacrylate
Various methacrylates such as butyl, isobutyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, decyl methacrylate or dodecyl methacrylate; hydroxy acrylate Various hydroxyl group-containing monomers such as ethyl or hydroxypropyl methacrylate; or N
Various types of N-, such as methylol (meth) acrylamide or N-butoxymethyl (meth) acrylamide
Substituted (meth) acrylic monomers are included.

Polymerization initiators that can be used include
There is no particular limitation, and for example, benzoyl peroxide, di-t-
Butyl peroxide, cumene hydroperoxide, t-
There may be mentioned various peroxides such as butyl peroxide or 2-ethylhexanoate; or various azo compounds such as azobisisobutyronitrile or azobisisovaleronitrile.

As a method of introducing a polymerization initiator to the surface of the pigment particles and then polymerizing it with the monomer, a functional group (for example, an amino group or a hydroxyl group) of the pigment is chemically reacted with a peroxide group such as a peroxycarbonyl group. And a method of introducing a group that initiates polymerization from the carboxyl group by generating a carboxyl group on the pigment surface with an oxidizing agent such as hypochlorous acid. A polymer-coated pigment can be obtained by polymerizing the above-mentioned hydrophobic monomer and polar group-containing monomer with the pigment having a polymerization initiation group on the surface obtained by these methods.

In the present invention, the coating amount of the polymer compound with respect to the pigment is 1% or more and 100% or less, preferably 5% or more and 50% or less.

According to the second aspect of the present invention, in an ink jet pigment ink in which pigment particles are dispersed in an aqueous medium,
One of the characteristics is that the redispersion coefficient represented by the above formula (1) of the pigment particles in an aqueous solvent is 0.5 to 5.

The redispersion coefficient referred to in the present invention is a measure of the dispersion stability and cohesiveness of the pigment particles, and as represented by the above formula (1), the volume average particles of the pigment particles before redispersion. It is represented by the ratio of the volume average particle size of the pigment particles after redispersion to the particle size. The volume average particle diameter in the present invention is a value measured by the secondary particle diameter.

Specifically, the volume average particle diameter of the pigment particles before redispersion represents the secondary particle diameter of the prepared pigment ink, and the volume average particle diameter of the pigment particles after redispersion means that the pigment ink was dried. The secondary particle size of the pigment particles after the dried pigment particles are added and deflocculated in a pigment ink medium such as water or an organic solvent, and the smaller the redispersion coefficient represented by the formula (1), the smaller Shows that the peptizing property and the dispersibility are excellent, and that the generation of aggregates is small, and the redispersion coefficient of 1 means that the secondary particle diameter does not change before and after the redispersion.

As a specific measuring method, 1 ml of the pigment ink is sampled, spread evenly on a washed petri dish, then left at room temperature and normal humidity for 1 week and dried. Then, 1 ml of water was added to the dried product, and the mixture was stirred and redispersed for 2 minutes using a glass rod, and the volume average particle diameter of the pigment particles in the pigment solution before and after drying was measured by the following method. To measure.

The volume average particle diameter can be measured by, for example, a commercially available particle size measuring device using a light scattering method, an electrophoresis method, a laser Doppler method, or the like. , Shimadzu laser diffraction particle size analyzer SLAD1100, particle size analyzer (HOR
IBA LA-920), Zetasizer 1000 manufactured by Malvern Instruments Ltd., and the like.

The present invention is characterized by a redispersion coefficient of 0.5 to 5, preferably 0.5 to 4, more preferably 0.5 to 3, and particularly preferably 0.5 to 2. Is.

In the present invention, the means for adjusting the redispersion coefficient to the range defined above is not particularly limited, but, for example, the use of pigment particles having polar groups on the surface according to the present invention, the pigment according to the present invention Coating the surface with a polymer compound, optimizing the type and addition amount of surfactant, controlling the secondary particle size distribution of pigment particles,
A desired redispersion degree can be obtained by appropriately selecting or combining the pigment dispersing means and each means such as optimizing the dispersing conditions.

Examples of the dispersing device that can be used in the present invention include various dispersing devices such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill and a paint shaker. I can raise the opportunity.

In the invention according to claim 3, claim 1 or 2
The pH of the inkjet pigment ink specified in 7.
It is characterized by being 0 or more, but preferably 8.0 to
It is 10.0. Examples of the pH adjuster used in the aqueous medium used in the pigment ink of the present invention include various organic amines such as monoethanolamine, diethanolamine and triethanolamine, sodium hydroxide, lithium hydroxide, potassium hydroxide and the like. Examples thereof include inorganic alkali agents such as hydroxides of alkali metals, organic acids, and mineral acids.

Further, in the invention according to claim 4,
The surface tension of the inkjet pigment ink defined by 3 to 25 is 25 to 45 mN / m, and preferably 30 to 40 mN / m. As a means for adjusting the surface tension of the pigment ink of the present invention, it is preferable to appropriately adjust the type and amount of addition using various surfactants described later.

The invention according to claim 5 is characterized in that the secondary volume average particle diameter of the pigment particles is 10 to 150 nm, preferably 20 to 120 nm, particularly preferably 20 to 90 nm, The volume average particle diameter defined by the present invention is preferable because the effects of the present invention can be exhibited at all.

The secondary volume average particle diameter of the pigment particles can be determined by the same method as described above for the redispersion coefficient.

The invention according to claim 6 is characterized in that the polyvalent metal ion content of the pigment ink is 5 ppm or less, preferably 0.1 to 3 ppm, particularly preferably 0.1 to 1 ppm. Is. By setting the content of the polyvalent metal ion in the pigment ink to the amount defined above, a pigment ink having high dispersion stability can be obtained.

The polyvalent metal ion in the present invention means, for example, Fe ³⁺ , Sr ²⁺ , Mg ²⁺ , Ca ²⁺ , Zn ²⁺ , Z.
^Examples thereof include r ²⁺ , Ni ²⁺ and Al ³⁺ , which are contained as sulfates, chlorides, nitrates, acetates, organic ammonium salts, EDTA salts and the like.

The invention according to claim 7 is characterized in that the ink solvent content is 5 to 70% by mass, preferably 10 to 60% by mass, and particularly preferably 20 to 50% by mass.

The ink solvent used in the present invention is not particularly limited, but it is preferable to use a compound represented by the following general formula (1). General formula (1) AB In formula, A represents a group containing a hydrophilic substituent, and B represents a hydrophobic group.

The group represented by A is a group containing a hydrophilic substituent, and examples of the hydrophilic substituent include a hydroxy group, a carboxyl group, a sulfoxide group, a sulfone group, a sulfonic acid group and 2-keto-1. -Pyrrolidinyl group and the like.
Of these, a hydroxy group is preferable.

B represents a hydrophobic group, preferably an aliphatic or aromatic hydrocarbon group having 3 to 10 carbon atoms.
Further, B is preferably an aliphatic group having 4 to 8 carbon atoms.

The compound represented by the general formula (1) has a structure similar to that of a general surfactant. A general surfactant has a characteristic of forming micelles in an aqueous solution at a low concentration.

The compound represented by the general formula (1) preferably does not have such micelle forming ability. This is because, when it has a micelle forming ability, it has a drawback that the viscosity of the ink remarkably increases when the concentration exceeds 1% because the interaction between molecules is strong.

Among the compounds represented by the general formula (1), preferable examples include polyhydric alcohol ether derivatives and aliphatic 1,2-diols having 4 to 8 carbon atoms, and ethylene glycol monobutyl ether. (Butyl cellosolve), diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, ethylene glycol monophenyl ether, 1,
A compound selected from 2-hexanediol and 1,2-pentanediol is more preferable. More preferred is triethylene glycol monobutyl ether or 1,2-hexanediol.

As the other ink solvent that can be used in the present invention, a water-soluble organic solvent is preferable. Specifically, alcohols (eg, methanol, ethanol,
Propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol, etc., polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol) , Dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, etc.), polyhydric alcohol ethers (for example, ethylene glycol monomethyl ether,
Ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, tri Ethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, triethylene glycol dimethyl ether, dipropylene glycol monopropyl ether, tripropylene glycol dimethyl ether, etc.), amines For example, ethanolamine, diethanolamine, triethanolamine, N- methyldiethanolamine, N- ethyldiethanolamine, morpholine, N- ethylmorpholine, ethylenediamine,
Diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.), amides (eg, formamide, N, N-)
Dimethylformamide, N, N-dimethylacetamide, etc.), heterocycles (eg, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-). Examples thereof include imidazolidinone), sulfoxides (eg dimethyl sulfoxide), sulfones (eg sulfolane etc.), sulfonates (eg 1-butanesulfonic acid sodium salt etc.), urea, acetonitrile, acetone and the like.

In the pigment ink of the present invention, an anionic surfactant is used in the invention of claim 8, a nonionic surfactant is used in the invention of claim 9, and a cationic surfactant is used in the invention of claim 10. The invention according to claim 11 is characterized by containing an anionic surfactant and a nonionic surfactant.

The surfactants that can be used in the present invention are not particularly limited, but examples thereof include anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates and fatty acid salts, and polyoxyethylene alkyl ethers. , Nonionic surfactants such as polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene block copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. To be In particular, an anionic surfactant and a nonionic surfactant can be preferably used.

Further, in the present invention, a high molecular surfactant can be used, and for example, styrene-acrylic acid-acrylic acid alkyl ester copolymer, styrene-acrylic acid copolymer, styrene-maleic acid-acryl. Acid alkyl ester copolymer, styrene-maleic acid copolymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-methacrylic acid copolymer, styrene-maleic acid half ester copolymer, vinylnaphthalene-acrylic Examples thereof include acid copolymers and vinylnaphthalene-maleic acid copolymers.

The invention according to claim 12 is characterized in that the pigment ink contains a water-soluble polymer or a water-insoluble polymer dispersion.

A preferred example of the water-soluble polymer is a natural polymer, and specific examples thereof include glue,
Proteins such as gelatin, casein, or albumin, natural gums such as gum arabic, or gum tragacanth, glucosides such as savonine, alginic acid and propylene glycol alginate, triethanolamine alginate, or alginate derivatives such as ammonium alginate, methylcellulose, Examples thereof include cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, or ethyl hydroxyl cellulose.

Further, preferred examples of the water-soluble polymer include synthetic polymers, such as polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, acrylic acid-acrylonitrile copolymer, potassium acrylate-acrylonitrile copolymer. Acrylic resins such as vinyl acetate-acrylic acid ester copolymers or acrylic acid-acrylic acid ester copolymers, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid Ester copolymer, styrene-
Styrene acrylic acid resin such as α-methylstyrene-acrylic acid copolymer or styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer Copolymer, vinylnaphthalene-acrylic acid copolymer, vinylnaphthalene-maleic acid copolymer, and vinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinylethylene copolymer, vinyl acetate-maleic acid ester copolymer, acetic acid Examples thereof include vinyl acetate-based copolymers such as vinyl-crotonic acid copolymers and vinyl acetate-acrylic acid copolymers and salts thereof. Among these, polyvinylpyrrolidones are particularly preferable.

The molecular weight of the water-soluble polymer is preferably 1,000 or more and 200,000 or less. Furthermore, 3,000 or more and 20,000 or less are more preferable. When it is less than 1,000, the effect of suppressing the growth and aggregation of pigment particles is reduced, and when it exceeds 200,000, problems such as viscosity increase and poor dissolution tend to occur.

The amount of the water-soluble polymer added is 1 with respect to the pigment.
It is preferably 0% by mass or more and 1,000% by mass or less. Furthermore, 50 mass% or more and 200 mass% or less are more preferable.
If it is less than 10% by mass, the effect of suppressing the growth and aggregation of the pigment particles is reduced, and if it exceeds 1000% by mass, problems such as viscosity increase and poor dissolution tend to occur.

Further, as a water-insoluble polymer dispersion (hereinafter also referred to as latex) which can be used in the present invention,
Although not particularly limited, for example, styrene-butadiene copolymer, polystyrene, acrylonitrile-butadiene copolymer, acrylic ester copolymer, polyurethane,
Examples thereof include silicone-acrylic copolymers and latices such as acrylic modified fluorinated grease. Latex, even if the polymer particles are dispersed using an emulsifier,
It may also be dispersed without using an emulsifier. A surfactant is often used as an emulsifier, but a polymer having a water-soluble group such as a sulfonic acid group or a carboxylic acid group (for example, a polymer having a solubilizing group graft-bonded thereto or a monomer having a solubilizing group It is also preferable to use a polymer obtained from a monomer and a monomer having an insoluble portion.

In the pigment ink of the present invention, it is particularly preferable to use soap-free latex. Soap-free latex is a latex that does not use an emulsifier, and a polymer having a water-soluble group such as a sulfonic acid group and a carboxylic acid group (for example, a polymer having a solubilizing group graft-bonded thereto, a solubilizing group Polymer obtained from a monomer having an insoluble portion and a monomer having an insoluble portion) is used as an emulsifier.

In recent years, as latex polymer particles, in addition to a latex in which polymer particles having a uniform particle size are dispersed, a core having a different composition at the central portion and the outer edge portion
Although there is a latex in which shell-type polymer particles are dispersed, this type of latex can also be preferably used.

In the pigment ink of the present invention, the average particle size of the polymer particles in the latex is 10 nm or more and 300 n.
m or less, and more preferably 10 nm or more and 100 nm or less. Latex average particle size is 300nm
If it is more than 10 nm, the glossiness of the image is deteriorated, and if it is less than 10 nm, the water resistance and scratch resistance are insufficient. The average particle size of the polymer particles in the latex can be determined by a commercially available particle size measuring device using a light scattering method, an electrophoresis method, or a laser Doppler method.

In the pigment ink of the present invention, the latex is added so that the solid content is 0.1% by mass or more and 20% by mass or less based on the total mass of the ink.
It is particularly preferable that the solid content of the latex is 0.5% by mass or more and 10% by mass or less. If the solid content of the latex is less than 0.1% by mass, it is difficult to exert a sufficient effect on water resistance, and if it exceeds 20% by mass, the viscosity of the ink increases with time and the particle size of the pigment dispersion is increased. In many cases, problems occur in terms of ink storability, such as an increase in ink liquor.

In addition to the above description, the pigment ink of the present invention may be used in accordance with the purpose of improving emission stability, compatibility with print heads and ink cartridges, storage stability, image storability, and other properties, as necessary. , Various known additives,
For example, a viscosity modifier, a specific resistance modifier, a film-forming agent, an ultraviolet absorber, an antioxidant, an anti-fading agent, a fungicide, an anticorrosive agent, etc. can be appropriately selected and used, for example, liquid paraffin, Oil droplet fine particles such as dioctyl phthalate, tricresyl phosphate, and silicone oil, JP-A-57-7
No. 4193, No. 57-87988 and No. 62-261.
UV absorbers described in JP-A-57-7419.
No. 2, No. 57-87989, No. 60-72785,
No. 61-146591, JP-A-1-95091 and JP-A-3-13376, and anti-fading agents, JP-A-59-42993, JP-A-59-52689, and JP-A-59-52689.
2-280069, 61-242871, JP-A-4-219266, and the like can be cited as a brightening agent.

The recording medium used in the present invention includes plain paper, coated paper, swelling ink jet recording paper provided with an ink receiving layer which absorbs and swells an ink liquid, and voids having a porous ink receiving layer. Type inkjet recording paper,
Further, a substrate using a resin support such as a polyethylene terephthalate film can be used instead of the base paper, but it is preferable to use a porous inkjet recording medium as the recording medium, and this combination provides the best effect of the present invention. Can be demonstrated.

As the porous ink jet recording medium,
Specifically, mention may be made of void-type inkjet recording paper or void-type inkjet film, which are recording media provided with a void layer having an ink absorbing ability, and the void layer is mainly hydrophilic. It is formed by soft agglomeration of the binder and the inorganic fine particles.

Various methods for forming a void layer are known as a method for forming voids in a film. For example, a uniform coating solution containing two or more kinds of polymers is coated on a support and dried in a drying process. A method of phase-separating these polymers with each other to form voids, a coating liquid containing solid fine particles and a hydrophilic or hydrophobic binder is applied on a support, and after drying,
A method of immersing an inkjet recording paper in water or a liquid containing a suitable organic solvent to dissolve solid fine particles to form voids, a coating liquid containing a compound having a property of foaming during film formation, and a drying process. A method of foaming this compound to form voids in the film, a method of applying a coating liquid containing porous solid fine particles and a hydrophilic binder onto a support to form voids in the porous fine particles or between the fine particles. ,
A method of forming voids between solid fine particles by applying a coating liquid containing solid fine particles and / or fine particle oil droplets and a hydrophilic binder having a volume equal to or more than the hydrophilic binder to a solid fine particle. However, when using the ink of the present invention, good results are obtained even if they are provided by any method.

The ink jet head which can be used in the ink jet image recording method of the present invention may be either an on-demand type or a continuous type.
In addition, as a discharge method, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type,
Bender type, piston type, shear mode type, shared wall type, etc., electric-heat conversion method (for example, thermal inkjet type, bubble jet (registered trademark) type, etc.), electrostatic attraction method (for example, electric field control type, slit) Specific examples include a jet type) and a discharge method (for example, a spark jet type).
Either ejection method may be used.

[0092]

The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

Example 1 << Preparation of Pigment Particles Coated with Polymer Layer >> (Preparation of Pigment Particle Dispersion Liquid 101: Pigment Dispersion Method A) Fastgen Super Magenta RTS (manufactured by Dainippon Ink and Chemicals, Inc.) was used as a pigment. JP-A-10-1200
According to Production Example 3 described in Japanese Patent Publication No. 65-65, magenta pigment particle dispersion liquid 10 in which pigment particle surfaces are coated with a polymer compound.
1 was prepared.

(Preparation of Pigment Particle Dispersion Liquid 102: Pigment Dispersion Method B) Fastgen Super Magenta RTS (manufactured by Dainippon Ink and Chemicals, Inc.) was used as a pigment, and the method described in JP-A-HEI-1
According to Production Example 4 described in JP-A-0-120065, a magenta pigment particle dispersion liquid 102 in which the surfaces of the pigment particles are coated with a polymer compound was prepared.

(Preparation of Pigment Particle Dispersion Liquid 103: Pigment Dispersion Method C) C.I. I. Pigment Red 122 (PV Fa
stPink EB-Trans, manufactured by Clariant) 15 g, pyridine 10 ml, and adipic acid dichloride 1
0 ml was dispersed in 500 ml of tetrahydrofuran and reacted at 60 ° C. for 2 hours under a nitrogen stream. After the reaction was completed, the pigment reaction product was filtered off, washed with tetrahydrofuran, and then dispersed in 100 ml of an aqueous t-butyl hydroperoxide solution (70% by mass),
Further, 2 g of sodium hydroxide was added, and the mixture was reacted at room temperature for 24 hours under a nitrogen stream. Then, the reaction product was filtered and washed with tetrahydrofuran, and then the reaction product was dispersed in 150 ml of tetrahydrofuran. 7.5 g of the following monomer mixture 1 was added to this dispersion, and the mixture was reacted at 80 ° C. for 6 hours. After the reaction was completed, an appropriate amount of ion-exchanged water was added to the polymerization reaction product, the pH was adjusted to 7.0 with diethanolamine, and concentration and water addition by ultrafiltration were repeated, and then centrifugation was performed to obtain the target magenta product. A pigment particle dispersion liquid 103 was obtained.

<Monomer mixture 1> Composition ratio: styrene / 2-ethylhexyl acrylate /
n-butyl acrylate / acrylic acid / sodium styrenesulfonate = 64/15/15/15/1 (Preparation of pigment particle dispersion liquid 104: pigment dispersion method D) PV dispersed using dioctyl sodium sulfosuccinate
FastPink EB-Trans (Clariant)
100 g of a 10% by mass aqueous dispersion of the above was taken, and 20 g of the monomer mixture 2 having the following composition, 50 g of ethanol and 0.1 g of potassium persulfate were added thereto, and a polymerization reaction was carried out at 80 ° C. for 6 hours. After the polymerization reaction, concentration by ultrafiltration and water addition were repeated, and then centrifugal separation was performed to prepare a magenta pigment particle dispersion liquid 104.

<Monomer mixture 2> Composition ratio: Styrene / 2-ethylhexyl acrylate /
Methacrylic acid = 64/16/15 (Preparation of Pigment Particle Dispersion Liquid 105) In the preparation of Pigment Particle Dispersion Liquid 101 (Pigment Dispersion Method A) described above, instead of Fastgen Super Magenta RTS as the pigment, Pigment particle dispersion liquid 105 was prepared in the same manner except that carbon black (CB) was used.

(Preparation of Pigment Particle Dispersion Liquid 106) In the preparation of Pigment Particle Dispersion Liquid 104 described above (Pigment Dispersion Method D), PV FastPink EB-T was used as the pigment.
A pigment particle dispersion liquid 106 was prepared in the same manner except that carbon black (CB) was used instead of rans.

(Preparation of Pigment Particle Dispersion Liquid 107) Carbon black (CB) was used as a pigment, and it was described in JP-A-9-3.
A pigment particle dispersion liquid 107 was prepared by dispersing the pigment particles according to the materials and methods described in the examples of Japanese Patent No. 374.

The characteristics of each pigment particle obtained as described above are shown in Table 1. The secondary volume average particle diameter (average particle diameter) of the pigment particles shown in Table 1 was measured by the following method.

<Measurement of Average Particle Size of Pigment Particles> Each pigment particle dispersion liquid is 0.1% of SA-2 (Perex OT-P).
After diluting 1000 times with the aqueous solution, measurement was performed using Malvern Zetasizer 1000.

Details of the abbreviations of the compounds shown in Table 1 are as follows. Pigment a: Fastgen Super Magenta RTS
(Manufactured by Dainippon Ink and Chemicals Inc.) Pigment b: PV FastPink EB-Trans
(Made by Clariant) C.I. B. : Carbon black (MA-made by Mitsubishi Chemical Corporation)
7) P-1: n-butyl methacrylate / n-butyl acrylate / 2-hydroxyethyl methacrylate / methacrylic acid = 175 / 10.7 / 37.5 / 26.8 P-2: n-butyl methacrylate / n-butyl Acrylate / 2-hydroxyethyl methacrylate / acrylic acid = 171.4 / 6.3 / 37.5 / 34.8 P-3: Styrene / 2-hydroxyethyl methacrylate / n-butyl acrylate / acrylic acid / sodium styrene sulfonate = 64/15/15/15/1 P-4: Styrene / 2-hydroxyethyl methacrylate / methacrylic acid = 64/16/15

[0103]

[Table 1]

<< Preparation of Ink >> Magenta and Black Inks 1 to 2 were prepared using the dispersion liquid of the pigment particles prepared above.
7 was prepared. In the preparation of each magenta and black ink, pure water and a fatty acid / fatty acid salt shown in Tables 2 and 3, an ink solvent, a polyvalent metal ion aqueous solution, a surfactant, a polymer compound are added to the dispersion liquid of each pigment particle. Tables 2 and 3
Was prepared by adding to the concentration described in. When the colorant concentration in the dispersion is insufficient and the colorant concentration in the ink cannot be adjusted to the target value, the pigment particle dispersion is depressurized to remove water and concentrate to a desired concentration. Readjusted.

When iron ions, aluminum ions and calcium ions are used as the polyvalent metal ion aqueous solution, 0.1% aqueous solutions of ferric chloride, aluminum chloride and calcium chloride are added respectively, and Table 2 The polyvalent metal ion concentration shown in Table 3 was adjusted. Further, the pH was adjusted to a value described in Table 4 below by using a 0.1 mol / L nitric acid aqueous solution and a sodium hydroxide aqueous solution.

Details of the compound abbreviations shown in Tables 2 and 3 are as follows. EG: ethylene glycol gly: glycerin TEGBE: triethylene glycol monobutyl ether DEG: diethylene glycol HDO: 1,2-hexanediol TEG: tetraethylene glycol PG: propylene glycol PYR: 2-pyrrolidinone SA-1: Olphin E1010 (manufactured by Nisshin Chemical Co., Ltd.) , Nonionic surfactant) SA-2: Perex OT-P (manufactured by Kao, anionic surfactant) SA-3: Olphin E1004 (manufactured by Nisshin Chemical, nonionic surfactant) SA-4: Rebenol WX (manufactured by Kao, Anion surfactant) SA-5: Emulgen LS-110 (manufactured by Kao, nonionic surfactant) SA-6: Emulgen 920 (manufactured by Kao, anion surfactant) P-5: Takelac W-605 (manufactured by Takeda Pharmaceutical Co., Ltd., Urethane soap free latte Box) P-6: Nipol LX844B (Nippon Zeon, acrylic latex) P-7: Nipol SX1105 (Nippon Zeon, styrene - butadiene soap-free latex) P-8: PVA203 (manufactured by Kuraray Co., polyvinyl alcohol)

[0107]

[Table 2]

[0108]

[Table 3]

<< Measurement of Characteristic Value of Each Ink >> For each magenta and black ink prepared as described above,
Each characteristic of magenta and black ink and each pigment particle in the ink was measured according to the method described below.

<Measurement of Redispersion Coefficient> 1 ml of each ink was sampled and spread evenly on a washed petri dish.
Leave at room temperature and humidity for 1 week to dry. Next, 1 ml of water was added to the dried product, and the mixture was stirred for 2 minutes with a glass rod to be redispersed. Was measured by the method.

The volume average particle diameter was measured by diluting each ink before and after drying 1000 times and then using Zetasizer 1000 manufactured by Malvern Co., and the redispersion coefficient was obtained according to the above formula (1).

<Measurement of pH and Surface Tension> The pH and surface tension were measured by a conventional method.

Table 4 shows the results obtained as described above. << Formation and Evaluation of Magenta and Black Images >> (Image Formation) After storing the magenta and black inks prepared above in an ink jet cartridge, a color ink jet printer PM820C (manufactured by Epson)
The image was output using. As the output image, a wedge image obtained by dividing the output density from 0% to 100% in 16 steps (outputted in a patch shape of 3 cm × 3 cm for each density) was used.

(Evaluation of scratch resistance) With respect to scratch resistance,
Using each wedge image created above, the patch image with the highest image density (output density 100%) was rubbed back and forth five times with an office eraser (MONO Tombow Pencil Co., Ltd.), and 20 people The remaining concentration was visually evaluated by a general evaluator of, and judged according to the following criteria.

A: 16 or more people evaluated that the density of almost the original image remained. B: 1 person evaluated that the density of the original image remained.
2 to 15 people c: 8 people evaluated that the density of the original image almost remained
~ 11 people d: 7 people evaluated that the density of the original image remained almost
Person or less (evaluation of glossiness) Glossiness is visually evaluated by 20 general evaluators for the wedge image created above,
The judgment was made according to the following criteria.

4: 16 or more evaluated as good gloss 3: 12 to 15 evaluated as good gloss 2: 8 to 11 evaluated as good gloss 1: good gloss Seven or less people were evaluated (evaluation of water resistance) Water resistance was determined by the patch image with the highest image density of each wedge image created above (output density of 100).
%), Drop 0.1 ml of pure water with a pipette, leave it for 30 seconds, wipe the image surface with pure water dropped using Kimwipe (made by Crecia), and check the residual concentration by 20 general evaluators. Was visually evaluated and judged according to the following criteria.

A: 16 or more people evaluated that the density of the original image almost remained. B: 1 person evaluated that the density of the original image remained.
2 to 15 people C: 8 people evaluated that the density of the original image almost remained.
~ 11 people D: 7 people evaluated that the density of the original image remained almost
Table 4 shows each evaluation result obtained by the number of persons or less.

[0118]

[Table 4]

As is clear from Table 4, in the comparative example, it was not possible to obtain a sample satisfying all of abrasion resistance, glossiness and water resistance.

On the other hand, it was confirmed that each of the samples of the present invention showed excellent scratch resistance, glossiness and water resistance, and had good image characteristics.

Example 2 << Preparation and Evaluation of Color Image >> (Preparation of Colored Fine Particles for Each Color and Pigment Particle Dispersion) Example 1
A dispersion liquid of pigment particles of each color of yellow, cyan and black was prepared according to the method for preparing the pigment particle dispersion liquid 104 described in (Pigment dispersion method D). Here, Pigment Yellow 128 was used as the yellow pigment, Pigment Blue 15: 3 was used as the cyan pigment, and carbon black was used as the black pigment. As the magenta pigment particles, the magenta pigment particle dispersion liquid 104 described in Table 1 above was used.

(Preparation of Ink of Each Color) Using the dispersion liquid of each pigment particle obtained as described above, an ink of each color was prepared according to the composition of Ink 15 shown in Table 3. here,
The concentration of the coloring material is adjusted appropriately so that it is the same as the genuine absorbance for the large format inkjet printer Iguazu 1044SD (manufactured by Konica), and ink of two shades is prepared for each color. Stored in.

Each of the obtained ink jet cartridges of each color was placed on a Konica ink jet paper Photolike QP using an ink jet tester equipped with eight piezo type ink jet heads having 512 ejection nozzles, a nozzle diameter of 25 μm and an ejection frequency of 30 kHz. , 1440 × 720 dpi (dpi is 2.54 cm
The image data was output at a pixel density of (representing the number of dots per hit).

By changing the driving voltage of the nozzle,
The droplet velocity was adjusted to be 8 m / sec. At this time, when the amount of the ejected ink droplet was measured, it was 7p.
It was l. Further, the driving conditions were appropriately set so that the low-concentration inkjet image recording liquid was output mainly in the low-to-medium density region, and the high-concentration inkjet image recording liquid was output mainly in the high-density region.

The structure of the head of the piezo type inkjet tester is as shown in FIG. 1 (a).
A cross-sectional view of the head 1 taken along the line AA is shown in FIG.

In FIG. 1A, the head 1 having five ejection nozzles is illustrated for the sake of explanation, but in Example 2, a head having 128 nozzles was used. A piezo element 2 for ejecting ink droplets by displacement of the piezo element is provided on the head corresponding to each ejection nozzle. In addition, the driver IC 3 that supplies a driving signal and a heating signal to the piezo element has an ink flow path (ink pool).
It is placed on top.

Further, the thermistor 4 is provided on the discharge nozzle near the piezo element and has a temperature measuring means.

As the output image data, the wedge image used in the first embodiment and the high-definition color digital standard image data "N5 / bicycle" issued by the Japan Standards Association
(Issued in December 1995) was used.

Further, the same image data was output on Konica Color QA Paper Type A7 using Digital Minilab QD-21 PLUS (manufactured by Konica) and developed to obtain a color silver salt photographic image for comparison.

Each of the images obtained as described above was evaluated for scratch resistance, glossiness and water resistance by the method described in Example 1. With respect to scratch resistance and water resistance, similar to the results of Example 1, good results were shown for each color. As for the glossiness, the result was as good as that of the comparative color silver salt photographic image.

[0131]

According to the present invention, it is possible to provide an ink jet pigment ink having excellent scratch resistance, glossiness and water resistance of an ink jet recorded image, an ink jet cartridge using the ink, an ink jet image recording method and an ink jet recorded image. did it.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a head of a piezo system inkjet tester used in the present invention.

[Explanation of symbols]

1 head 2 Piezo element 3 driver IC 4 thermistor

Continued front page    F-term (reference) 2C056 EA13 FA03 FA04 FA05 FA07                       FB02 FC02 KC01                 2H086 BA52 BA53 BA55 BA59 BA60                       BA62                 4J037 AA02 CC13 CC16 CC17                 4J039 AB01 AB02 AB07 AD01 AD03                       AD08 AD09 AD10 AD11 AD12                       AD13 AD14 AD22 AE04 AE11                       BC01 BC07 BC09 BC13 BC19                       BC34 BC36 BE01 BE12 BE22                       BE28 BE30 CA06 EA33 EA36                       EA38 GA24

Claims (15)

[Claims] 1. In an inkjet pigment ink in which pigment particles are dispersed in an aqueous medium, the total content of fatty acids and fatty acid salts in the inkjet pigment ink is 0.5% by mass or less, and the surface of the pigment particles. Is coated with a water-insoluble and water-dispersible polymer layer. 2. The inkjet pigment ink according to claim 1, wherein a redispersion coefficient represented by the following formula (1) is 0.5 to 5. Formula (1) Redispersion coefficient = secondary volume average particle diameter of pigment particles after redispersion / secondary volume average particle diameter of pigment particles before redispersion 3. The inkjet pigment ink according to claim 1, which has a pH of 7.0 or more. 4. The inkjet pigment ink according to claim 1, wherein the surface tension is 25 to 45 mN / m. 5. The secondary volume average particle diameter of the pigment particles is
It is 10-150 nm, It is characterized by the above-mentioned.
The inkjet pigment ink according to claim 1. 6. The inkjet pigment ink according to claim 1, wherein the polyvalent metal ion content is 5 ppm or less. 7. The ink jet pigment ink according to claim 1, wherein the ink solvent content is 5 to 70 mass%. 8. The inkjet pigment ink according to claim 1, further comprising an anionic surfactant. 9. The inkjet pigment ink according to claim 1, further comprising a nonionic surfactant. 10. The inkjet pigment ink according to claim 1, further comprising a cationic surfactant. 11. The inkjet pigment ink according to claim 1, further comprising an anionic surfactant and a nonionic surfactant. 12. The ink jet pigment ink according to claim 1, which contains a water-soluble polymer or a water-insoluble polymer dispersion liquid. 13. An ink jet cartridge comprising an ink containing portion containing at least one of the inkjet pigment inks according to any one of claims 1 to 12. 14. An inkjet image recording method, which comprises forming an image using at least one pigment ink for inkjet according to any one of claims 1 to 12. 15. An inkjet-recorded image formed by performing inkjet-image recording using at least one pigment ink for inkjet according to claim 1.