JP2003313479A - Ink for inkjet and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink for inkjet which gives a printed image improved in gloss properties, resistance to image bleeding and resistance to image peeling in a high humidity environment, and an image forming method. <P>SOLUTION: The ink for inkjet comprises a colored fine particle comprising a resin A containing a coloring material or a colored fine particle obtained by further coating the surface of the resin A containing the coloring material with a resin B, an aqueous medium and water, and satisfies the relation: 0.50≤a/b≤0.95, where a is a light absorption coefficient when diluted with a poor solvent of the coloring material and b is a light absorption coefficient when diluted with a good solvent of the coloring material. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet ink and an image forming method, and more specifically, an inkjet ink and an image having improved glossiness, image blur resistance and image peeling resistance of a printed image in a high humidity environment. The present invention relates to a forming method.

[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 since scattered light or reflected light does not occur, it is possible to obtain an inkjet image with high transparency and clear hue, and from the high reliability against clogging in printers. , Most commonly used.

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. An ink jet recorded image using a dye ink has high image quality, but since it is an aqueous solution of a dye, it easily bleeds on a recording medium, and it is unavoidable that the use is limited and the recording quality is deteriorated. Further, as compared with an ink using a pigment described later, there is a problem that it is difficult to obtain a high density due to the penetration of the coloring material into the recording medium.

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 the pigment is present as pigment particles as compared with the dye, it is more susceptible to light scattering and gives an image with no sense of transparency, so there is a drawback that the dye does not match the color reproducibility.

As a measure for solving the problems of the water-based ink using the water-soluble dye as described above, an emulsion,
The addition of resin fine particles such as latex has been studied for a long time. Japanese Patent Application Laid-Open No. 55-18418 proposes a recording agent for ink jet recording to which a latex which is "a kind of colloidal solution in which components such as rubber and resin are dispersed in water in the form of fine particles by an emulsifier" is added. is there. In order to improve light fastness by adding latex as in the patent proposal or to have a bleeding prevention effect,
It is very difficult to secure dispersion stability and discharge stability because more latex than the amount of dye used is required, and to obtain an image comparable to a photographic image in terms of graininess and glossiness. The current situation is that it has not arrived.

A proposal for coloring a water-dispersible resin with an oil-soluble dye or a hydrophobic dye in order to solve the problems of low image density and light fastness of a water-based ink using the above-mentioned water-soluble dye is proposed as an ink jet recording ink. Has been done. For example, JP-A-55-139471, JP-A-58-58
45272, JP-A-3-250069, JP-A-8-
253720, JP-A-8-92513, JP-A-8-
An ink using emulsion-polymerized particles dyed with an oil-soluble dye or dispersed polymerized particles is proposed in 183920, JP 2001-11347 A, and the like. In a water-based ink using such colored fine particles, the effect is diminished when a dye is present on the surface of the particles or outside the particles, and especially when stored for a long period of time under high humidity, the image gloss decreases and image blurring occurs. And a new problem that the adhesiveness between the recording medium and the formed image is reduced.

Further, in the case of water-based ink, as a method of increasing the penetration speed of the ink into the ink jet recording medium and improving the blur resistance and glossiness of the image, the dynamic surface tension of the ink such as triethylene glycol monobutyl ether is lowered. Although a method of using a solvent having a function of making it known is used, in an aqueous ink containing colored fine particles in which the above coloring material is encapsulated by a resin, a solvent such as triethylene glycol monobutyl ether is used. , Because it penetrates into the resin that constitutes the colored fine particles and elutes the contained coloring material into the aqueous ink medium, the image density is reduced, the inkjet head is clogged, and fusion occurs on the recording medium surface. Causing a decrease in the permeation rate of the water-based ink into the recording medium, causing ink overflow and uneven printed images. , The amount of the solvent having a function of reducing the dynamic surface tension of the ink, such as triethylene glycol monobutyl ether, there is naturally limited.

As described above, the colored fine particle-containing aqueous ink using an oil-soluble dye or pigment overcomes the problems of the conventional aqueous ink using a water-soluble dye or pigment dispersion,
Although it has the potential to achieve high recording quality, there are still many problems and further 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 improve glossiness of a printed image, image blur resistance and image peeling resistance in a high humidity environment. Another object of the present invention is to provide an inkjet ink and an image forming method.

[0012]

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

1. An inkjet ink containing colored fine particles of a resin A containing a coloring material or colored fine particles obtained by further coating the surface of a resin A containing a coloring material with a resin B, an aqueous solvent and water, wherein a poor solvent for the coloring material is used. 0.50 ≦ a / b ≦ 0.9, where a is the extinction coefficient when diluted with 1, and b is the extinction coefficient when diluted with a good solvent for the coloring material.
5. An ink-jet ink, which is No. 5.

2. U when diluted with a poor solvent for the coloring material
When the absorbance at λmax of the V-Vis waveform is 1.0, the wavelength width at the absorbance of 0.8 is p (nm), and the λ of the UV-Vis waveform when diluted with a good solvent for the coloring material is used.
When the absorbance at max is 1.0 and the wavelength width at absorbance 0.8 is q (nm), the p (nm) and q
The inkjet ink according to item 1, wherein the difference from (nm) is 1 nm or more and 30 nm or less.

3. The absolute value of the difference between the solubility parameter of the resin A and the solubility parameter of the coloring material is 0.1 (J
/ Cm ³ ) ^1/2 or more and 3.0 (J / cm ³ ) ^1/2 or less, The inkjet ink according to the above 1 or 2, wherein

4. Item 4. The inkjet ink according to any one of Items 1 to 3, wherein the colored fine particles have a core-shell structure in which the surface of a resin A containing a coloring material is further covered with a resin B.

5. The volume average particle diameter of the colored fine particles is
The inkjet ink according to any one of items 1 to 4, wherein the inkjet ink has a thickness of 10 to 200 nm.

6. Surface tension is 25mN / m or more, 50
6. The inkjet ink according to any one of the items 1 to 5, which is mN / m or less.

7. pH is 6.0 or more and 11.0 or less, The ink-jet ink according to any one of items 1 to 6 above.

8. 8. The inkjet ink according to any one of items 1 to 7, wherein at least one kind of the aqueous solvent is a polyhydric alcohol ether or a polyhydric alcohol.

9. 9. The inkjet ink according to any one of items 1 to 8, wherein the content of the aqueous solvent is 10% by mass or more and 60% by mass or less.

10. An image forming method characterized in that the inkjet ink according to any one of the above items 1 to 9 is ejected as a droplet from an inkjet head based on a digital signal, and the droplet is attached to an inkjet recording medium.

The inventors of the present invention have found that the coloring fine particles of the resin A containing the coloring material or the coloring fine particles obtained by further coating the surface of the resin A containing the coloring material with the resin B, an aqueous solvent and water are used. Regarding the ink, as a result of earnestly studying the improvement of glossiness of a printed image in a high humidity environment, image bleeding resistance and image adhesion, the absorption coefficient when the inkjet ink was diluted with the poor solvent of the coloring material. Is a and the absorption coefficient when the inkjet ink is diluted with a good solvent for the coloring material is b, 0.50 ≦ a / b ≦
The inventors have found that it can be achieved by setting the condition to be 0.95, and further, the above-mentioned effect is obtained by diluting the inkjet ink with a poor solvent for the coloring material.
When the absorbance at λmax of the s waveform is 1.0, the wavelength width at an absorbance of 0.8 is p (nm), and UV-Vi when the inkjet ink is diluted with a good solvent for the coloring material
When the absorbance at λmax of the s waveform is 1.0 and the wavelength width at an absorbance of 0.8 is q (nm), p (n
The difference between m) and q (nm) is 1 nm or more and 30 nm or less, and the absolute value of the difference between the solubility parameter of the resin A and the solubility parameter of the coloring material is 0.1 (J / cm ³ ). ^1/2 or more and 3.0 (J / cm ³ ) ^1/2 or less, and a core-shell structure in which the surface of the resin A containing coloring material as the coloring fine particles is further covered with the resin B, etc. It has been found that the object of the present invention can be achieved by setting the relationship of 1 to a specific condition.

Regarding the technical improvement mechanism by the constitution defined in the present invention, the details are not clear, but as a result of the dye being highly molecularly dispersed in the resin, the dye constituting this high concentration part is It is speculated that it acts as a filler in the resin and the apparent Tg of the resin rises, or that this high concentration part promotes volatilization of the residual solvent.

Further, the volume average particle diameter of the colored fine particles is 10
To 200 nm, at least one of the aqueous solvents is a polyhydric alcohol ether or a polyhydric alcohol, the surface tension of the inkjet ink (hereinafter, also referred to as the ink of the invention), pH, and the amount of the aqueous solvent. It has been found that the effect of the present invention can be further exerted by defining the above-mentioned value within a specific range, and the present invention has been achieved.

The details of the present invention will be described below. In the invention according to claim 1, an inkjet ink containing colored fine particles made of a resin A containing a coloring material or colored fine particles obtained by further coating the surface of a resin A containing a coloring material with a resin B, an aqueous solvent and water. In Table 1, when the extinction coefficient when the inkjet ink is diluted with the poor solvent of the color material is a and the extinction coefficient when the ink is diluted with the good solvent of the color material is b, 0.50 ≦ a / b ≦ The characteristic is 0.95, preferably 0.60 ≦ a / b ≦ 0.92, and more preferably 0.72 ≦ a / b ≦ 0.90.

In the present invention, the poor solvent for the coloring material refers to a solvent in which the coloring material is not substantially eluted from the coloring fine particles, and the good solvent for the coloring material is such that the coloring material is substantially eluted from the coloring fine particles in the solvent. Refers to a solvent that can be dissolved in. Therefore, whether the solvent is a poor solvent or a good solvent depends on the type and characteristics of the coloring material. For example, when a coloring material that is easily dissolved in ethyl acetate is used, the poor solvent is a solvent such as water, methanol and ethanol, and the good solvent is a solvent such as ethyl acetate and methyl ethyl ketone. In the case of a coloring material that is easily dissolved in methanol or the like, the poor solvent is a solvent such as ethyl acetate or methyl ethyl ketone, and the good solvent is a solvent such as water, methanol or ethanol.

The extinction coefficients a and b are dissolved in a poor solvent or a good solvent for an appropriate coloring material, for example, a good solvent such as methanol, ethyl acetate, methyl ethyl ketone, etc. as a poor solvent, and the solvent is 10 times the solvent. After the above dilution, a commercially available spectrophotometer, for example, a spectrophotometer UVIDFC-610 manufactured by Shimadzu Corporation, HI manufactured by Hitachi, Ltd.
It can be determined by measurement using a TACHI U-3000 / 3300 type self-spectrophotometer, a HITACHIU-4000 type self-spectrophotometer, or the like.

Further, in the invention according to claim 2, when the absorbance at λmax of the UV-Vis waveform when the ink is diluted with the poor solvent for the coloring material is 1.0, the absorbance is 0.8.
Is p (nm), and when the absorbance at λmax of the UV-Vis waveform when diluted with a good solvent for the coloring material is 1.0, the wavelength width at absorbance 0.8 is q (n
m), the difference between p (nm) and q (nm) is 1
The thickness is preferably 30 nm or more and 30 nm or less, more preferably 2 nm or more and 20 nm or less, and further preferably 3 nm or more and 15 nm or less. The wavelength widths p (nm) and q (nm) at the respective absorbances of 0.8 can also be determined by the method described above.

In the present invention, there are no particular restrictions on the method for achieving the characteristics specified in claim 1 or claim 2, but for example, the types of resins described below (type of monomer, weight average molecular weight, SP value, etc.) , Conditions for core shell formation,
It can be obtained by appropriately selecting the type of coloring material.

In the invention according to claim 3, the absolute value of the difference between the solubility parameter of the resin A and the solubility parameter of the coloring material is 0.1 (J / cm ³ ) ^1/2 or more and 3.0 ( J / c
m ³ ) ^1/2 or less, more preferably 0.1 (J / cm ³ ) ^1/2 or more, 2.0 (J / cm ³ ) ^1/2
It is the following.

The solubility parameter as referred to in the present invention is a value obtained by the solubility parameter of Hildebrand which is often used in evaluating the solubility of the non-electrolyte in the organic solvent. This solubility parameter is described, for example, in J. H. Hildebrand, J. et al. M.
Prausnitz. R. L. Scott's "Regu
lar and Related Solution
s ", Van Nostrand-Reinhold,
See Princeton (1970), "Polymer Data Handbook Basic Edition", The Polymer Society of Japan. The values of the solubility parameters of various solvents are A. F. M. Barton, "H
andbook of Solrbility Par
ameters and other cohesio
n Parameters ”, CRC Press, B
oca Raton / Florida (1983),
"Polymer Data Handbook Basic Edition" is described in The Polymer Society of Japan.

The solubility parameter of a substance is defined by SP = (δE / V) ^1/2 , where δE is the cohesive energy per mole and V is the molar volume.

The solubility parameter can be determined by several methods such as the method of determining from the solubility, the evaporation latent heat method, the vapor pressure method, the swelling method, the surface tension method, the thermal swelling coefficient method, and the refractive index method.

In the present invention, any of the solubility parameters obtained by the following method is used.
The unit is represented by (J / cm ³ ) ^1/2 in the present invention.

The solubility parameter can be determined from the solubility in a solvent of which various SP values are known. This method of obtaining the solubility parameter by the solubility in the solvent is effective when the structure of the dye or the like is unknown.

In the present invention, the SP value of the resin A or the coloring material used in the core of the present invention is, for example, ethanol, acetone, methyl ethyl ketone, ethyl acetate, toluene, etc. A dissolution method is used in which the solubility is determined and the SP value is plotted on the X-axis and the solubility of each compound in 1 mol of the solvent is plotted on the Y-axis to determine the SP value.

Next, the resin that can be used in the present invention (also referred to as the polymer of the present invention) will be described.

The resin A according to the present invention mainly contains a coloring material, and contributes to maintain its fastness and color tone. Further, the resin B increases the stability of the fine particles containing the coloring material in the ink dispersion, prevents the coloring material from aggregating on the ink jet recording medium, contributes to the improvement of the image quality, and further improves the robustness of the coloring material. It also contributes to maintaining the color tone.

In the present invention, the resin A according to the present invention can be appropriately selected and used from commonly known polymers, and particularly preferred polymers are
A polymer containing an acetal group as a main functional group, a polymer containing a carbonic acid ester group, a polymer containing a hydroxyl group, and a polymer having an ester group,
In particular, the polymer forming the outermost shell portion preferably has a hydroxyl group. The above-mentioned polymer may have a substituent, and the substituent may have a linear, branched or cyclic structure. Various polymers having the above-mentioned functional group are commercially available, but they can be synthesized by a conventional method. Further, these copolymers can also be obtained, for example, by introducing an epoxy group into one polymer molecule and then polycondensing it with another polymer or performing graft polymerization using light or radiation.

A polyvinyl butyral resin is preferably used as the polymer containing an acetal as a main functional group. For example, Denki Kagaku Kogyo Co., Ltd. # 2000-L, # 3000-1, # 3000-2,
# 3000-4, # 3000-K, # 4000-1, #
4000-2, # 5000-A, # 6000-C, # 6
000-EP or BL-1, B manufactured by Sekisui Chemical Co., Ltd.
L-1H, BL-2, BL-2H, BL-5, BL-1
0, BL-S, BL-SH, BX-10, BX-L, B
M-1, BM-2, BM-5, BM-S, BM-SH,
BH-3, BH-6, BH-S, BX-1, BX-3,
BX-5, KS-10, KS-1, KS-3, KS-5
and so on.

Polyvinyl butyral resin is obtained as a derivative of PVA (polyvinyl alcohol), but the acetalization of the hydroxyl group of the original PVA is 80 mol at maximum.
%, Usually from 50 mol% to 80 mol%
It is a degree. It should be noted that the acetal referred to here is 1 in a narrow sense.
It does not refer to the 1-diethoxyethane group, but refers to compounds in general with orthoaldehyde. The hydroxyl group is not particularly defined, but in the polymer constituting the outermost shell portion, the hydroxyl group-containing monomer is preferably 5 to 50 mol%, more preferably 10 to 30 mol%.
Is. The content of acetyl groups is not particularly limited, but is preferably 10 mol% or less. A polymer containing acetal as a main functional group means at least 30 mol% of oxygen atoms contained in the polymer.
The above means that an acetal group is formed.

In addition, as a polymer containing acetal as a main functional group, Iupital series manufactured by Mitsubishi Engineering Plastics Co., Ltd. can be used.

Examples of the polymer containing carbonic acid ester as a main functional group include polycarbonate resins. For example, there are Iupilon series and Novarex series manufactured by Mitsubishi Engineering Plastics Co., Ltd. The Iupilon series is made from bisphenol A as a raw material, and various molecular weights can be used although the value varies depending on the measuring method. The Novarex series has a molecular weight of 20,000 and a glass transition point of 150.
A material having a temperature in the vicinity of ° C can be used, but the material is not limited to these.

The polymer containing a carbonic acid ester group as a main functional group means that at least 30 mol% or more of oxygen atoms contained in the polymer contribute to the formation of a carbonic acid ester group.

Examples of the polymer having a hydroxyl group as a main functional group include PVA. Although the solubility of PVA in organic solvents is low in many cases, the solubility of PVA in organic solvents increases if the saponification value is low. Highly water-soluble PVA can also be used by adding it to the aqueous phase, removing the organic solvent, and adsorbing it to the polymer suspension.

Commercially available PVA can be used, for example, Kuraray's Poval PVA-102 and PVA.
VA-117, PVA-CSA, PVA-617, PV
In addition to A-505, special grade PVA for sizing agents,
As PVA for hot melt molding and other functional polymers, K
L-506, C-118, R-1130, M-205,
MP-203, HL-12E, SK-5102, etc. can be used. The degree of saponification is generally 50 mol% or more, but it is 40 mol as in LM-10HD.
Even if it is about 1%, it is possible to use it.
Other than PVA, those having a hydroxyl group as a main functional group can be used, but those having at least 20 mol% or more of oxygen atoms contained in the polymer forming a hydroxyl group can be used.

Examples of the polymer containing an ester group as a main functional group include methacrylic resin. Asahi Kasei Delpet series 560F, 60N,
80N, LP-1, SR8500, SR6500, etc. can be used. The polymer containing an ester group as a main functional group means that at least 30 mol% or more of oxygen atoms contained in the polymer form an ester group.

In the present invention, styrene resin and acrylic resin can also be preferably used. Examples of the resin that can be used include styrene, acrylic acid,
Methacrylic acid, methyl acrylate, ethyl acrylate,
Butyl acrylate, isobutyl acrylate, hexyl acrylate, 2-hydroxyethyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, hexyl methacrylate, 2-hydroxy methacrylate A monomer such as ethyl or 2-ethylhexyl methacrylate can be polymerized and used by an existing method such as radical polymerization, cationic polymerization or anionic polymerization.

One of these polymers is used or two of them are used.
You may mix and use 1 or more types. Further, other polymers and inorganic fillers may be contained as long as these polymers are contained in a mass ratio of 50% or more.

Although it is preferable to use a copolymer of these polymers, for example, a polymer containing a hydroxyl group,
As a method of copolymerizing various polymers, it can be obtained by reacting a hydroxyl group with a monomer having an epoxy group such as glycidyl methacrylate and then copolymerizing it with a methacrylic acid ester monomer by suspension polymerization.

As the resin B according to the present invention, a polymer having a hydrophobic portion and a hydrophilic portion can be used.
Specifically, a monomer selected from hydrophobic monomers such as ethylene, propylene, butadiene, vinyl chloride, vinylidene chloride, vinyl acetate, styrene, (meth) acrylic acid alkyl ester and (meth) acrylic acid aryl ester, and (meth ) Hydroxyethyl acrylate, monomers having a hydroxyl group such as (meth) acrylic acid polyethylene glycol monoester, monomers having a carboxylic acid such as (meth) acrylic acid, itaconic acid, maleic acid, styrenesulfonic acid, (meth) A combination with a monomer selected from hydrophilic monomers such as a monomer having a sulfonic acid such as sulfobutyl acrylate and a monomer having an amide group such as acrylamide is preferable.

More preferably, from the viewpoint of easy production, a styrene- (meth) acrylic hydrophobic monomer such as (meth) acrylic acid alkyl ester and (meth) acrylic acid aryl ester, and (meth) With a monomer selected from styrene- (meth) acrylic hydrophilic monomers such as hydroxyethyl acrylate, (meth) acrylic acid polyethylene glycol monoester, (meth) acrylic acid, sulfobutyl (meth) acrylate, and acrylamide Combinations are preferred.

In the ink-jet ink of the present invention, the polymer used for the colored fine particles is preferably contained in the ink in an amount of 0.5 to 50% by mass,
It is more preferable that the content is ˜30% by mass. If the blending amount of the above polymer is less than 0.5% by mass, the ability to protect the coloring material is insufficient, and if it exceeds 50% by mass, the storage stability of the suspension as an ink is lowered, or the nozzle tip portion is deteriorated. Since there is a case where clogging of the printer head may occur due to thickening of the ink and aggregation of the suspension due to the evaporation of the ink, it is preferably within the above range.

Next, the aqueous solvent according to the present invention will be described. In the invention according to claim 9, the content of the aqueous solvent is preferably 10% by mass or more and 60% by mass or less, and more preferably 20 to 50% by mass.

The aqueous solvent that can be used in the present invention is not particularly limited, but it is preferable to use the compound represented by the following general formula [I].

General Formula [I] AB In the 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 [I] 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 [I] 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.

As the aqueous solvent that can be used in the present invention, a water-soluble organic solvent is preferable, and specifically, alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tert-butanol) can be used. Libutanol, 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 (eg 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, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, triethylene glycol dimethyl ether, dipropylene glycol monopropyl ether, tripropylene glycol dime Ether, etc.), amines (e.g., 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-). Imidazolidinone etc.), sulfoxides (eg dimethyl sulfoxide etc.), sulfones (eg sulfolane etc.), sulfonates (eg 1-butanesulfonic acid sodium salt etc.), urea, acetonitrile, acetone and the like. However, in the invention according to claim 8, at least one of the aqueous solvents is preferably a polyhydric alcohol ether or a polyhydric alcohol,
More preferably, as the polyhydric alcohol ethers,
Ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, ethylene glycol monophenyl ether, and polyhydric alcohols are 1,2-hexanediol, or 1,2-hexanediol.
-Pentanediol, particularly preferably triethylene glycol monobutyl ether or 1,2-hexanediol.

Next, the colored fine particles according to the present invention will be described in detail below. Colored fine particles according to the present invention,
It can be prepared by various methods. For example, a method of dissolving an oil-soluble coloring material in a monomer, emulsifying it in water, and then encapsulating the coloring material in a polymer by polymerization, dissolving the polymer and the coloring material in an organic solvent, and then emulsifying in water and then using an organic solvent. How to remove, add porous polymer particles to the colorant solution,
Examples thereof include a method of adsorbing and impregnating fine particles with a coloring material, and a shelling method of coating these colored fine particles with a polymer can also be used.

The polymer shell may be provided by adding a water-soluble polymer dispersant to the aqueous suspension of the core and adsorbing it, by gradually dropping the monomer and depositing it on the surface of the core simultaneously with polymerization, or by using an organic solvent. There is a method in which the polymer dissolved in is gradually dropped and adsorbed on the core surface simultaneously with precipitation. A method of forming the core shell in one step is also conceivable. For example, a method in which a core polymer and a dye together with a shell polymer are heated and dissolved, and then suspended and polymerized in water, or emulsion polymerization is performed while gradually dropping the liquid into water containing an active agent micelle. There are ways. Alternatively, there is a method in which a dye is dissolved or dispersed in a monomer that can be a core and a monomer that can be a shell after polymerization, and suspension polymerization or emulsion polymerization is performed.

The colored fine particles according to the present invention are not particularly limited to shelled ones and shelled ones, but in view of the effect of the invention, in the invention according to claim 4, the colored fine particles are It is preferable that the surface of the resin A containing the coloring material is further covered with the resin B to have a core-shell structure. In that case, the amount of polymer used in the shell is preferably 5% by mass or more and 95% by mass or less of the total amount of polymer. When the amount is less than 5% by mass, the thickness of the shell is insufficient and a part of the core containing a large amount of coloring material is likely to appear on the particle surface. On the other hand, if the shell polymer is too much, the amount of the core polymer is relatively decreased, and the function of protecting the color material is likely to be deteriorated. More preferably, it is 10% by mass or more and 90% by mass or less.

The coloring material is 20% by mass based on the total amount of polymer.
It is preferably not less than 1000% by mass. When the amount of the coloring material is too small compared to the polymer, the image density after ejection does not increase, and when the ratio of the coloring material is high, the polymer protecting ability cannot be sufficiently obtained.

(Evaluation of core-shell formation) In the present invention, it is important to evaluate whether or not a core-shell structure is actually formed. In the present invention, the particle size of each particle is very small, 150 nm or less, so the analysis method is limited from the viewpoint of resolution. A transmission electron microscope (TEM), a time-of-flight secondary ion mass spectrometer (TOF-SIMS), or the like can be applied as an analysis method that meets such a purpose. TE
When observing the colored fine particles core-shelled by M,
The dispersion can be coated on a carbon support film, dried, and observed. Since the TEM observation image is usually monochrome, it is necessary to dye the colored fine particles in order to evaluate whether or not it is core-shelled. The colored fine particles of only the core are dyed, and the TEM observation is performed, and comparison is made with the one provided with the shell. Further, the fine particles provided with the shell and the fine particles not provided with the shell are mixed and dyed, and it is confirmed whether or not the ratio of the fine particles having different degrees of dyeing coincides with the presence or absence of the shell. In TOF-SIMS, it is confirmed that the dye in the vicinity of the surface is reduced by providing the shell on the particle surface as compared with the case where only the core is used. When the coloring material has an element that is not contained in the polymer of the core shell, it is possible to confirm whether or not a shell having a small coloring material content is provided by using the element as a probe. In the absence of such elements, the colorant content in the shell can be compared with that without the shell using an appropriate dye. By embedding core-shell particles in an epoxy resin, making an ultrathin section with a microtome, and dyeing, core-shell formation can be observed more clearly. When the polymer or dye has an element that can serve as a probe, the composition of the core-shell and the amount of the dye distributed to the core and the shell can be estimated by TEM.

In the invention according to claim 5, the volume average particle diameter of the colored fine particles is preferably 10 to 200 nm, preferably 20 to 120 nm, and particularly preferably 20.
It is preferable that the volume-average particle diameter defined by the present invention can exert the effects of the present invention at all.

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

Next, the color material according to the present invention will be described. In the present invention, various dyes or pigments known in the ink jet can be used as the coloring material encapsulated by the polymer, but in the present invention, it is preferable to use a dye as the coloring material. The dye that can be used is not particularly limited, and examples thereof include oily dyes, disperse dyes, direct dyes, acid dyes, and basic dyes. In the present invention, it is preferable to use oily dyes.

As the hue, yellow, magenta, cyan, black, blue, green and red are preferably used, and yellow, magenta, cyan and black dyes are particularly preferable. The oil-soluble dyes also include dyes that exhibit oil-solubility by forming a salt of a water-soluble dye with a long-chain base. The oily dye is not limited to the following, but a particularly preferable specific example thereof is, for example, V2alifas manufactured by Orient Chemical Industry Co., Ltd.
t Yellow 4120, Valifast Ye
low 3150, Valifast Yellow
3108, Valifast Yellow 231
0N, Valifast Yellow 1101, V
alifast Red 3320, Valifast
Red 3304, Valifast Red 13
06, Valifast Blue 2610, Val
ifast Blue 2606, Valifast
Blue 1603, Oil Yellow GG-
S, Oil Yellow 3G, Oil Yellow
w 129, Oil Yellow 107, Oil
Yellow 105, Oil Scarlet 30
8, Oil Red RR, Oil Red OG, O
il Red 5B, Oil Pink 312, Oi
l Blue BOS, Oil Blue 613, O
il Blue 2N, Oil Black BY, O
il BlackBS, Oil Black 860,
Oil Black 5970, Oil Black 5
906, Oil Black 5905, Kayaset Yellow SF-G, K manufactured by Nippon Kayaku Co., Ltd.
ayaset Yellow K-CL, Kayase
t Yellow GN, Kayaset Yellow
w A-G, Kayaset Yellow 2G, K
Ayaset Red SF-4G, Kayaset
Red K-BL, Kayaset Red AB
R, Kayase Magenta 312, Kayas
et Blue K-FL, manufactured by Arimoto Chemical Industry Co., Ltd.
FS Yellow 1015, FS Magenta
1404, FS Cyan 1522, FS Blu
e 1504, C.I. I. Solvent Yellow
88, Solvent Yellow 83, Sol
Vent Yellow 82, Solvent Ye
low 79, Solvent Yellow 5
6, Solvent Yellow 29, Solve
nt Yellow 19, Solvent Yell
ow 16, Solvent Yellow 14, S
solvent Yellow 04, Solvent
Yellow 03, Solvent Yellow
02, Solvent Yellow 01, C.I. I.
Solvent Red 84: 1, C.I. I. Solve
nt Red 84, C.I. I. SolventRed
218, C.I. I. Solvent Red 132,
C. I. Solvent Red 73, C.I. I. So
lvent Red 72, C.I. I. Solvent
Red 51, C.I. I. Solvent Red 4
3, C.I. I. Solvent Red 27, C.I. I.
Solvent Red 24, Solvent Re
d 18, Solvent Red 01, Solve
ntBlue 70, Solvent Blue 6
7, Solvent Blue 44, Solvent
Blue 40, Solvent Blue 35, S
solvent Blue 11, Solvent B
lue 02, Solvent Blue 01, So
lvent Black 43, C.I. I. Solven
t Black 70, C.I. I. Solvent Bl
ack 34, C.I. I. Solvent Black
29, C.I. I. Solvent Black 27,
C. I. Solvent Black 22, C.I. I.
Solvent Black 7, C.I. I. Solve
nt Black 3, C.I. I. Solvent Vi
olet 3, C.I. I. Solvent Green
3 and 7 and the like.

Further, JP-A-9-277693 and 10
Metal complex dyes as shown in Nos. -20559 and 10-30061 are also preferably used, and a preferable structure is represented by the following general formula [II].

In the general formula [II] M (Dye) ₁ (A) _m , M represents a metal ion, and Dye represents a dye capable of forming a coordinate bond with a metal. A represents a ligand other than the dye, 1 represents 1 to 3 and m represents 0, 1, 2, 3. When m is 0, 1 represents 2 or 3, and in that case, Dye may be the same or different. Examples of the metal ion represented by M include Al, Co, Cr, Cu, Fe, Mn, Mo and N.
Examples include ions of i, Sn, Ti, Pt, Pd, Zr, and Zn. Ni, Cu, Cr, from the color tone and various durability,
Ions of Co, Zn and Fe are particularly preferable. More preferably, it is Ni ion.

Various dye structures are conceivable as the dye represented by Dye and capable of forming a coordinate bond with the metal, but a conjugated methine dye, an azomethine dye, and a dye having a coordination group in the azo dye skeleton are preferable.

The disperse dye is not limited to the following, but a particularly preferred specific example is C.I. I. Disperse Yellow 5, 42, 54, 64, 79, 8
2, 83, 93, 99, 100, 119, 122, 12
4, 126, 160, 184: 1, 186, 198, 1
99, 204, 224 and 237; C.I. I. Disperse Orange 13, 29, 31: 1, 33, 49, 54,
55, 66, 73, 118, 119 and 163;
I. Disperse Red 54, 60, 72, 73, 8
6, 88, 91, 92, 93, 111, 126, 12
7, 134, 135, 143, 145, 152, 15
3, 154, 159, 164, 167: 1, 177, 1
81, 204, 206, 207, 221, 239, 24
0, 258, 277, 278, 283, 311, 32
3, 343, 348, 356 and 362; I. Disperse Violet 33; C.I. I. Disperse Blue 56, 60, 73, 87, 113, 128, 143,
148, 154, 158, 165, 165: 1, 16
5: 2, 176, 183, 185, 197, 198, 2
01, 214, 224, 225, 257, 266, 26
7, 287, 354, 358, 365 and 368; and C.I. I. Examples include Disperse Green 6: 1 and 9.

Further, as the dye, the following general formula (1)
The dye represented by (3) can also be preferably used.

[0077]

[Chemical 1]

In the above general formulas (1) to (3), X ₁
Represents a coupler residue used in a silver halide color photographic light-sensitive material, and preferably acetanilide, 5-pyrazolone, imidazole, pyrazolopyrrole, pyrazoloimidazole, pyrazolotriazole, pyrazolotetrazole, pyrazolopyrimidine-7- On, barbituric acid, thiobarbituric acid, rhodanine, hydantoin,
Thiohydantoin, oxazolone, isoxazolone,
Examples thereof include indandione, pyrazolidinedione, oxazolidinedione, hydroxypyridone, pyrazolopyridone, cyclohexadienone, phenol, and naphthol derivatives. n represents 0, 1 or 2.

Y represents a 5- or 6-membered aromatic carbocyclic group or a heterocyclic group, preferably a derivative of benzene, pyridine, pyrrole, thiazole, oxazole, furan or thiophene.

R ₁ , R ₂ and R ₃ each represent a hydrogen atom, a halogen atom or a monovalent substituent, and the monovalent substituent represented by R ₁ , R ₂ and ₃ is, for example, an alkyl group, Cycloalkyl group, aralkyl group, aryl group, alkoxy group, aryloxy group, acylamino group, sulfonamide group, ureido group, alkoxycarbonylamino group, alkylthio group, arylthio group, alkoxycarbonyl group, carbamoyl group, sulfamoyl group, sulfonyl group And amino groups and the like.

Among the above general formulas, the dye represented by the general formula (1) is preferable, and the dye in which n is 0 is more preferable.

The coloring material contained in the colored fine particles according to the present invention is preferably blended in the ink in an amount of 1 to 30% by mass, more preferably 1.5 to 25% by mass. If the blending amount of the coloring material is less than 1% by mass, the printing density is insufficient, and if it exceeds 30% by mass, the stability of the suspension with time is deteriorated and the particle size tends to increase due to aggregation or the like. It is preferably within the range.

The ink-jet ink of the present invention comprises a suspension of a polymer in which water is used as a medium and in which the above-mentioned coloring material is encapsulated. In addition to the above-mentioned aqueous solvent, the suspension includes various conventionally known additives such as A dispersant, a silicone-based antifoaming agent, a chloromethylphenol-based antifungal agent and / or a chelating agent such as EDTA, and an oxygen absorbent such as sulfite may be contained.

The dispersant is not particularly limited, but when the HLB value is 8 to 18, the effect as the dispersant is exhibited and the effect of suppressing the increase in the particle size of the suspension is obtained. preferable.

Commercially available products can also be used as the dispersant. Examples of such a commercially available product include dispersants DEMOL SNB, MS, N, SSL, ST, P manufactured by Kao Corporation.
(Product name).

The amount of the dispersant blended is not particularly limited, but 0.01 to 10% by mass is preferably blended in the ink jet ink of the present invention. The compounding amount of the compound is 0.
If the amount is less than 01% by mass, it is difficult to reduce the particle size of the suspension. If the amount is more than 10% by mass, the particle size of the suspension may be increased or the suspension stability may be deteriorated to cause gelation. It is preferable that

The antifoaming agent is not particularly limited, and commercially available products can be used. Examples of such commercially available products include KF96, 6 manufactured by Shin-Etsu Silicone Co., Ltd.
6, 69, KS68, 604, 607A, 602, 60
3, KM73, 73A, 73E, 72, 72A, 72
C, 72F, 82F, 70, 71, 75, 80, 83
A, 85, 89, 90, 68-1F, 68-2F (brand name) etc. are mentioned. The compounding amount of these compounds is not particularly limited, but it is 0.
It is preferable that 001 to 2 mass% is blended. If the compounding amount of the compound is less than 0.001% by mass, bubbles are likely to be generated during ink preparation, and it is difficult to remove small bubbles in the ink, and if it exceeds 2% by mass, the generation of bubbles is suppressed. ,
At the time of printing, repellency may occur in the ink and the print quality may deteriorate, so the range is preferably within the above range.

Next, the method for producing the ink-jet ink of the present invention will be described. The inkjet ink of the present invention can be manufactured by various emulsification methods.

As described above, in the invention according to claim 5, the volume average particle diameter of the colored fine particles is preferably 10 to 200 nm, but the method for achieving the average particle diameter defined above is not particularly limited. However, it can be achieved, for example, by appropriately selecting or combining the types and amounts of the dispersants described above, or the emulsification methods shown below.

Various methods can be used as the emulsification method. Examples of these are summarized, for example, in the description on page 86 of “Progress of Functional Emulsifiers / Emulsification Technologies and Their Application and Development”. In the present invention, it is particularly preferable to use an emulsifying / dispersing device using ultrasonic waves, high-speed rotary shearing, and high pressure.

Two types of so-called batch type and continuous type can be used for ultrasonic dispersion. The batch type is
It is suitable for preparing a relatively small amount of sample, and the continuous method is suitable for preparing a large amount of sample. In the continuous system, for example, UH-60
It is possible to use a device such as 0SR (manufactured by SMT Co., Ltd.). In the case of such a continuous system, the irradiation time of ultrasonic waves can be obtained by the formula: volume of dispersion chamber / flow velocity × number of circulations. When there are a plurality of ultrasonic irradiation devices, the total irradiation time can be calculated. The ultrasonic wave irradiation time is actually required to be 3 seconds or longer, and if the emulsification is completed within that time, the ultrasonic wave emulsification dispersion device is not required. Further, if it is necessary for 10000 seconds or more, the load of the process is heavy, and it is necessary to shorten the emulsification / dispersion time by reselection of the emulsifier in practice. Therefore, 10,000 seconds or more is not necessary. More preferably, 10 seconds or more, 20
It is within 00 seconds.

Examples of the emulsification / dispersion device using high-speed rotary shearing include a disper mixer as described on pages 255-256 of “Advancement of functional emulsifier / emulsification technology and application development,” and a description on page 251. A homomixer as described above, an ultramixer as described on page 256, or the like can be used. These types can be used properly depending on the liquid viscosity at the time of emulsion dispersion. In these emulsifying dispersers using high-speed rotary shearing, the rotation speed of the stirring blade is important. Since the clearance with the stator is usually about 0.5 mm and cannot be extremely narrowed, the shearing force mainly depends on the peripheral speed of the stirring blade. When the peripheral speed is 5 m / sec or more and 150 m / sec or less, it can be used in the emulsification / dispersion of the present invention. This is because when the peripheral speed is slow, it is often impossible to reduce the particle size even if the emulsification time is extended, and it is necessary to extremely improve the performance of the motor in order to achieve 150 m / sec. More preferably, it is 20 to 100 m / sec.

For emulsification and dispersion by high pressure, LAB2000
(Made by SMT) can be used, but the emulsification /
Dispersion capacity depends on the pressure applied to the sample. The pressure is preferably 10 MPa or more and 500 MPa or less. In addition, the desired particle size can be obtained by emulsifying and dispersing several times as necessary. If the pressure is too low, the desired particle size cannot be achieved in many cases, no matter how many times emulsification and dispersion are performed, and in order to set the pressure to 500 MPa, a large load is applied to the device, which is not practical. More preferably, it is 50 MPa or more and 200 MPa or less.

These emulsifying / dispersing devices may be used alone, but may be used in combination as required. A colloid mill, a flow jet mixer, etc., alone cannot achieve the object of the present invention, but by combining with the above-mentioned device, the effect of the present invention can be enhanced by enabling emulsification / dispersion in a single time. .

Further, the ink of the present invention can be produced by so-called phase inversion emulsification, in addition to using the above apparatus. Here, the phase inversion emulsification is to dissolve the above polymer together with the above dye in an organic solvent such as ester or ketone,
If necessary, a neutralizing agent is added to ionize the carboxyl groups in the polymer, and then an aqueous phase is added, and then the organic solvent is distilled off to invert the phase into an aqueous system.

After completion of the phase inversion, the system is heated under reduced pressure to remove the ester and ketone solvents and a predetermined amount of water to obtain the colored fine particles of the present invention having a desired concentration. An ink containing is obtained.

Next, another preferred embodiment of the ink jet ink of the present invention will be described.

In the invention according to claim 6, the surface tension of the ink jet ink is 25 mN / m or more and 50 mN / m.
It is a preferred embodiment that the value is m or less, and more preferably 30 to 40 mN / m. As a means for adjusting the surface tension of the inkjet ink of the present invention, it is preferable to use various surfactants and to appropriately adjust the type and the addition amount thereof.

In a seventh aspect of the present invention, the pH of the inkjet ink is preferably 6.0 or more and 11.0 or less, and more preferably 8.0 or more and 1 or less.
It is 0.0 or less. Examples of the pH adjuster used in the inkjet ink of the present invention include various organic amines such as monoethanolamine, diethanolamine and triethanolamine, and alkali metal hydroxides such as sodium hydroxide, lithium hydroxide and potassium hydroxide. Examples thereof include inorganic alkaline agents such as substances, organic acids, and mineral acids.

In the ink-jet ink of the present invention, one kind or two or more kinds of anionic surfactant, nonionic surfactant, and cationic surfactant can be used. Each surfactant that can be used in the present invention is not particularly limited, but examples thereof include anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates, fatty acid salts, polyoxyethylene alkyl ethers, and polyoxyethylene alkyl ethers. Examples thereof include nonionic surfactants such as oxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene block copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. In particular, an anionic surfactant and a nonionic surfactant can be preferably used.

In the present invention, a polymeric surfactant can also be used, and examples thereof include styrene-acrylic acid-alkyl acrylate copolymer, styrene-acrylic acid copolymer, styrene-maleic acid-acrylic. 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 ink-jet ink of the present invention may contain a water-soluble polymer or water-insoluble polymer dispersion liquid.

A natural polymer is a preferred example of the water-soluble polymer, and specific examples thereof include glue and
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, a synthetic polymer is mentioned as a preferred example of the water-soluble polymer, and polyvinyl alcohols, polyvinyl pyrrolidones, 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. If it is less than 1,000, the effect of suppressing the growth and aggregation of the colored fine particles is reduced, and if it exceeds 200,000, problems such as an increase in viscosity and poor dissolution tend to occur.

The amount of the water-soluble polymer added is 1 with respect to the dye.
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 colored fine 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 liquid (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 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 the 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 ink of the present invention, the average particle size of the polymer particles in the latex is 10 nm or more and 300 nm or less, and more preferably 10 nm or more and 100 nm or less. If the average particle size of the latex exceeds 300 nm, the glossiness of the image deteriorates, and if it is less than 10 nm, the water resistance and scratch resistance become 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 ink of the present invention, the latex is 0.1% by mass based on the total mass of the ink as a solid content.
As described above, it is added so as to be 20% by mass or less, but 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 the passage of time and the dispersion of colored fine particles occurs. In many cases, problems occur in terms of ink storability such that the particle size tends to increase.

In addition to the above description, the 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 performances, if necessary. , Various known additives, for example, viscosity modifier, resistivity modifier, film-forming agent, ultraviolet absorber, antioxidant, anti-fading agent, anti-rust agent, rust inhibitor, etc. may be appropriately selected and used. For example, liquid paraffin, dioctyl phthalate, tricresyl phosphate, oil droplet fine particles such as silicone oil, and JP-A-57-74.
193, 57-87988 and 62-2614.
UV absorbers described in JP-A-76-74192.
No. 57-87989, No. 60-72785, No. 61-146591, No. 1-95091 and No. 3-13376, and anti-fading agents, JP-A-59-42993, 59-52689, 62
Examples thereof include fluorescent whitening agents described in JP-A-280069, JP-A-61-242871 and JP-A-4-219266.

The recording medium used in the present invention includes plain paper, coated paper, swelling type inkjet recording paper provided with an ink receiving layer which absorbs an ink liquid and swells, 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 in the present invention, it is preferable to use a void type porous ink jet recording medium, and by this combination, the present invention can be used. Most effective.

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 of forming a void layer are known as a method of 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 solution 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.

In a tenth aspect of the present invention, it is a preferable aspect that the ink of the present invention is ejected as a droplet from the ink jet head based on the digital signal and is attached to the ink jet recording medium.

The ink jet head that can be used in the image forming 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, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electric-heat conversion method (for example, a thermal type Specific examples include an inkjet type, a bubble jet (R) type, an electrostatic suction type (for example, an electric field control type, a slit jet type, etc.), and a discharge type (for example, a spark jet type). However, any ejection method may be used.

[0118]

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

<< Preparation of Colored Fine Particle Dispersion >> Colored fine particle dispersions 1 to 14 shown in Table 1 were prepared. An example of the preparation is shown below.

<Preparation Example 1: Preparation of colored fine particle dispersion 1>
5.0 g of polyvinyl butyral (Sekisui Chemical Co., Ltd. B
M-5, average degree of polymerization 850 SP value 20.0 (J / cm
³ ) ^1/2 ), 5.0 g of dye A (chelate dye) and 50
g of ethyl acetate was placed in a separable flask, the inside of the flask was replaced with nitrogen gas, and the mixture was stirred to completely dissolve the polyvinyl butyral and the dye A. Then, 100 g of an aqueous solution containing 2.0 g of sodium dodecyl sulfonate
Was added dropwise and stirred, and then emulsified for 300 seconds using an ultrasonic disperser (UH-150 type manufactured by SMT Co., Ltd.). Then, ethyl acetate was removed under reduced pressure to obtain a colored fine particle dispersion containing core type colored fine particles impregnated with the dye.

Then, in the shell forming step, the inside of the flask containing the above dispersion liquid was replaced with nitrogen gas, and then 0.15 g of potassium persulfate was added to the dispersion liquid to dissolve it.
After heating with a heater to 70 ℃, styrene /
2 g of a mixed solution of 2-hydroxyethyl methacrylate (molar ratio 4/1) was added dropwise over 2 hours and reacted for 6 hours to form a shell, which was then purified by an ultrafiltration device to obtain dye A.
A core-shell type colored fine particle dispersion liquid 1 containing was obtained.

<Preparation Example 2: Preparation of colored fine particle dispersion 5>
In the preparation of the above colored fine particle dispersion liquid 1, instead of polyvinyl butyral BM-5, a copolymer of styrene / butyl methacrylate (P-1 monomer molar ratio = 70/2).
5 Weight average molecular weight 83,000 SP value 20.6 (J / c
A core-shell type colored fine particle dispersion liquid 5 containing the dye A was obtained in the same manner except that m ³ ) ^1/2 ) was used.

<Preparation Example 3: Preparation of Colored Fine Particle Dispersion Liquid 6>
In the preparation of the colored fine particle dispersion 1, 5.0 g of polyvinyl butyral (BL-1, manufactured by Sekisui Chemical Co., Ltd., average degree of polymerization: 350 SP value: 20.0) was used as the core portion forming condition.
(J / cm ³ ) ^1/2 ), 5.0 g of Dye A (chelate dye), 40 g of ethyl acetate and 10 g of n-butanol, except that the core-shell type was prepared in the same manner. A colored fine particle dispersion liquid 6 of was obtained.

<Preparation Example 4: Preparation of Colored Fine Particle Dispersion Liquid 8>
In the preparation of the colored fine particle dispersion 1, 5.0 g of polyvinyl butyral (BL-1, manufactured by Sekisui Chemical Co., Ltd., average degree of polymerization: 350 SP value: 20.0) was used as the core portion forming condition.
(J / cm ³ ) ^1/2 ), except that 5.0 g of dye A (chelate dye) and 50 g of ethyl acetate were used for dissolution.
In the same manner, core-shell type colored fine particle dispersion liquid 8 containing dye A was obtained.

<Preparation Example 5: Preparation of colored fine particle dispersion 9>
5.0 g of polyvinyl butyral (Sekisui Chemical Co., Ltd. B
M-5, average degree of polymerization 850 SP value 20.0 (J / cm
³ ) ^1/2 ), 5.0 g of dye A (chelate dye) and 50
g of ethyl acetate was placed in a separable flask, the inside of the flask was replaced with nitrogen gas, and the mixture was stirred to completely dissolve the polyvinyl butyral and the dye A. Then, 100 g of an aqueous solution containing 2.0 g of sodium dodecyl sulfonate
Was added dropwise and stirred, and then emulsified for 300 seconds using an ultrasonic disperser (UH-150 type manufactured by SMT Co., Ltd.). Then, ethyl acetate was removed under reduced pressure to obtain a colored fine particle dispersion liquid 9 containing core type colored fine particles impregnated with the dye.

<Preparation Example 6: Preparation of colored fine particle dispersion liquid 10> 5.0 g of polyvinyl butyral (Sekisui Chemical Co., Ltd.)
BL-1 manufactured, average polymerization degree 350 SP value 20.0 (J /
cm ³ ) ^1/2 ), 5.0 g of Dye A (chelate dye) and 50 g of ethyl acetate were placed in a separable flask, the inside of the flask was replaced with nitrogen gas, and the mixture was stirred to obtain the above polyvinyl butyral and Dye A. It was completely dissolved. Then, an aqueous solution 10 containing 2.0 g of sodium dodecyl sulfonate.
After dropping 0 g and stirring, an ultrasonic disperser (UH-15
It was emulsified for 300 seconds using 0 type (manufactured by SMT Co., Ltd.). Then, ethyl acetate is removed under reduced pressure, and a colored particle dispersion liquid 1 containing core type colored particles impregnated with a dye
I got 0.

<Preparation of Other Colored Fine Particle Dispersion Liquids> Colored fine particle dispersion liquids other than those described above were also prepared by using the coloring materials shown in Table 1 and the respective polymers at the time of core formation according to the above-mentioned preparation example. .

<< Measurement of Characteristic Value of Colored Fine Particle Dispersion >> (Measurement of Solubility Parameter (SP Value) and Calculation of SP Value Difference) Solubility Parameter (SP Value) of Each Polymer Used in Core and Dyes A and B ) For SP, ethanol, acetone, methyl ethyl ketone, ethyl acetate, toluene
Used as a solvent with a known value, the solubilities for 1 mol volume of each of these solvents were determined, and the solubilities were determined from the graph in which the SP value was plotted on the X axis and the solubility was plotted on the Y axis. The value was calculated.

Table 1 shows the constitution of each colored fine particle dispersion liquid obtained as described above.

[0130]

[Table 1]

[0131]

[Chemical 2]

Details of the compound abbreviations shown in Table 1 are as follows. Dye B: FS Yellow 1015 (manufactured by Arimoto Chemical Co., Ltd.) BM-5: Polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd.) BL-1: Polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd.) P-1: Styrene / Copolymer of butyl methacrylate (monomer molar ratio: 70/25, weight average molecular weight: 8.
30,000, SP value: 20.6 (J / cm ³ ) ^1/2 ) P-2: Styrene / butyl methacrylate / 2-hydroxyethyl methacrylate copolymer (monomer molar ratio: 75/20/5, weight average molecular weight) : 83,000, SP
Value: 21.8 (J / cm ³ ) ^1/2 ) P-3: Styrene / butyl methacrylate / methyl methacrylate copolymer (monomer molar ratio: 75/10 /
15, weight average molecular weight: 88,000, SP value: 23.6
(J / cm ³ ) ^1/2 ) P-4: Styrene / butyl methacrylate copolymer (monomer molar ratio: 70/25, weight average molecular weight: 0.
50,000, SP value: 20.6 (J / cm ³ ) ^1/2 ) P-5: Styrene / 2-hydroxyethyl methacrylate copolymer (monomer molar ratio 4/1) P-6: Styrene / methacrylic acid Copolymer (monomer ratio 3/1) << Preparation of ink >> Inks 1 to 19 were prepared using the colored fine particle dispersions prepared above. In the preparation of each ink, pure water and Solvent 1 or Solvent 2 shown in Table 2 were added to each colored fine particle dispersion liquid so that the dye concentration in the ink was 2
The content was adjusted appropriately so as to be mass%. The pH used is an aqueous solution of sodium hydroxide or an aqueous solution of acetic acid, and the surface tension is the value shown in Table 2 by adjusting the addition amount of Surfynol 465 (manufactured by Nisshin Chemical Industry Co., Ltd.) as a surfactant. I did it. Each of the inks prepared as described above was filtered through a 2 μm membrane filter to remove dust and coarse particles, and thus inks 1 to 19 shown in Table 2 were prepared.

Details of each compound shown in Table 2 are as follows. Solvent 1: ethylene glycol / glycerin / triethylene glycol monobutyl ether = 10/5/5 (numerical values represent mass% relative to the total mass of the ink) Solvent 2: ethylene glycol / glycerin / 1,2-hexanediol = 11/6 / 5 (numerical value represents mass% with respect to the total mass of the ink) << Measurement of each ink characteristic value >> (Measurement of wavelength range at each extinction coefficient and absorbance of 0.8) <Measurement of ink absorption characteristics a and p> After diluting 1 g of ink with methanol, which is a poor solvent for the coloring material, a spectrophotometer UVIDFC-made by Shimadzu Corporation as a spectrophotometer.
610, the spectral absorption curve of the UV-Vis waveform is measured, a, which is the absorption coefficient per 1 g of ink, is calculated, and when the absorbance at λmax of the spectral absorption curve is corrected to 1.0, the absorbance of 0. The wavelength width p (nm) in 8 was obtained.

<Measurement of Absorption Properties b and q of Coloring Material> 1 g of ink liquid was sampled, ethyl acetate which was a good solvent for the coloring material was added and dissolved in an ultrasonic disperser, and then this solution was prepared. Was diluted with methanol, and b, which is the absorption coefficient per 1 g of ink, was calculated in the same manner as described above, and the absorbance at 0.8 when the absorbance at λmax of the spectral absorption curve was corrected to 1.0 The wavelength width q (nm) was determined.

A / b was calculated from a and b obtained above, and each value of pq was calculated from p and q.

(Measurement of Average Particle Size of Colored Fine Particles) Each ink was diluted with a 0.1% aqueous solution of Perex OT-P to 1,000 times.
After doubling the dilution, the average particle size (volume average particle size) of colored fine particles was measured using a laser particle size analysis system manufactured by Otsuka Electronics.
Was measured.

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

<< Formation and Evaluation of Inkjet Image >> (Image formation) After storing each ink prepared above in an ink jet cartridge, a color ink jet printer PM-800 (manufactured by Epson Corporation) was used to make a Konica Photo Jet Paper Photolike QP glossy paper (Konica). (Manufactured by the company) to make an image. As the image, a wedge image (3 cm × 3 cm patch image) obtained by dividing the output density from 0% to 100% in 16 steps and a solid image having a density of 1.0 are output, and then each printed image is printed at 60 ° C. After being left for 3 days in an atmosphere with a relative humidity of 55%, the following evaluations were performed.

(Glossiness after high-humidity treatment) The printed image after the high-humidity treatment and the untreated print image were visually compared, and the glossiness was evaluated according to the following criteria.

⊚: No decrease in gloss in the high-humidity-processed image was observed with respect to the unprocessed image. O: No decrease in gloss in the high-humidity-processed image was observed with respect to the unprocessed image Δ: A slight decrease in gloss in the high-humidity-processed image is observed with respect to the unprocessed image, but it is in a practically acceptable range. X: A decrease in gloss in the high-humidity-processed image is remarkable compared to the unprocessed image. Not practically usable (evaluation of bleeding resistance after high-humidity treatment) The printed image after the high-humidity treatment and the untreated printed image were visually compared, and the bleeding resistance was evaluated according to the criteria described below.

⊚: No bleeding change is observed in the high-humidity-processed image with respect to the unprocessed image ◯: No bleeding change is observed in the high-humidity-processed image with respect to the unprocessed image Δ: Unprocessed The image is slightly distorted in the high-humidity-processed image, but is in the practically acceptable range. ×: Distorted image in the unprocessed image is indistinguishable from the high-humidity-processed image. Therefore, after storing only the ink solvent in the inkjet cartridge, it cannot be used for practical purposes (evaluation of image peeling resistance after high humidity treatment).
Konica Photojet Paper Pho with Color Inkjet Printer PM-800 (manufactured by Epson)
Tolique QP glossy paper (manufactured by Konica Corporation) was printed, and then a solid image was printed by the same method using the ink in the above method, and 5 printing images created by repeating this operation 5 times were laminated. Then, a load of 0.05 N / cm ² was applied to the surface and left at 60 ° C. in an atmosphere of 55% relative humidity for 3 days. After the completion of standing, the superimposed images were peeled off, the degree of peeling of the printed image was visually observed, and the image peeling resistance was evaluated according to the following evaluation criteria.

⊚: No image peeling was observed at all ◯: Almost no image peeling was observed Δ: A slight peeling of the image area was observed, but in a practically acceptable range ×: Image was spread over the entire surface Table 2 shows the evaluation results obtained by the above-mentioned peeling, which is not practical.

[0143]

[Table 2]

As is clear from Table 2, in the comparative example, the results were that the glossiness of the printed image after the high humidity treatment was decreased, the image bleeding was increased, or the image peeling resistance was decreased. The relationship between the extinction coefficient a and the extinction coefficient b is 0.5.
It should be confirmed that the ink having 0 ≦ a / b ≦ 0.95 has less deterioration in glossiness and less increase in image bleeding and has excellent image peeling resistance even after storage under high humidity. I was able to.

[0145]

According to the present invention, it is an object of the present invention to provide an ink jet ink and an image forming method in which the glossiness of a printed image in a high humidity environment, the image blur resistance and the image peeling resistance are improved.

Continued front page    F-term (reference) 2C056 EA05 EA13 FC02                 2H086 BA52 BA59 BA60 BA62                 4J039 AD01 AD03 AD04 AD06 AD07                       AD09 AD10 AD17 AE06 BC07                       BC13 BE01 BE02 BE12 BE22                       CA06 EA33 EA36 EA47 GA24

Claims (10)

[Claims] 1. An inkjet ink containing colored fine particles of a resin A containing a coloring material or colored fine particles obtained by further coating the surface of a resin A containing a coloring material with a resin B, an aqueous solvent and water. When the extinction coefficient of the coloring material diluted with a poor solvent is a and the extinction coefficient of the coloring material diluted with a good solvent is b, 0.50 ≦ a / b ≦ 0.95
An inkjet ink characterized in that 2. UV when diluted with a poor solvent for the coloring material
When the absorbance at -max of the -Vis waveform is 1.0,
The wavelength width at absorbance 0.8 is p (nm), and λma of the UV-Vis waveform when diluted with a good solvent for the coloring material
When the absorbance at x is 1.0 and the wavelength width at absorbance 0.8 is q (nm), the p (nm) and q (n
The inkjet ink according to claim 1, wherein the difference from m) is 1 nm or more and 30 nm or less. 3. The absolute value of the difference between the solubility parameter of the resin A and the solubility parameter of the coloring material is 0.1 (J /
^3. The inkjet ink according to claim 1, which has a content of cm ³ ) ^1/2 or more and 3.0 (J / cm ³ ) ^1/2 or less. 4. The inkjet according to any one of claims 1 to 3, wherein the colored fine particles have a core-shell structure in which the surface of a resin A containing a coloring material is further coated with a resin B. ink. 5. The volume average particle diameter of the colored fine particles is 1
It is 0-200 nm, The inkjet ink of any one of Claims 1-4 characterized by the above-mentioned. 6. The surface tension is 25 mN / m or more, 50 m
It is N / m or less, The inkjet ink of any one of Claims 1-5 characterized by the above-mentioned. 7. The inkjet ink according to any one of claims 1 to 6, which has a pH of 6.0 or more and 11.0 or less. 8. The inkjet ink according to claim 1, wherein at least one kind of the aqueous solvent is a polyhydric alcohol ether or a polyhydric alcohol. 9. The ink jet ink according to claim 1, wherein the content of the aqueous solvent is 10% by mass or more and 60% by mass or less. 10. An image forming method, wherein the inkjet ink according to any one of claims 1 to 9 is ejected as a droplet from an inkjet head based on a digital signal, and the droplet is attached to an inkjet recording medium. .