JP2003313474A - Aqueous ink for inkjet recording and aqueous ink set for inkjet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous ink for inkjet recording which exhibits excellent gloss properties in combination with a void structure-containing medium and excellent ink permeability in an image region where a large amount of an ink is ejected and is improved in light resistance under a high humidity condition, and an aqueous ink set for inkjet recording. <P>SOLUTION: The aqueous ink for inkjet recording comprises a colored fine particle containing a coloring material and a resin, where ratio of the mass of the residue after drying to the mass of the ink is 3-12%, the colored fine particle has a volume-average particle size of at least 10 nm and less than 60 nm, and the initial elution ratio of the coloring material in the colored fine particle by a solvent of the coloring material and that after two minutes differ by at most 20%. <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 a water-based ink for ink jet recording and a water-based ink set for ink jet recording, and more particularly to a water base ink for ink jet recording and ink jet recording for which glossiness, ink penetration and light resistance are improved. The present invention relates to a water-based ink set.

[0002]

2. Description of the Related Art Inkjet recording is a technique for ejecting minute droplets of ink to adhere to a recording medium by various operating principles 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 because scattered light and reflected light do not occur, it is possible to obtain an inkjet image with high transparency and clear hue, and since there are no coloring material particles, scratch resistance It has excellent characteristics.

On the other hand, however, when a molecule is 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 it has the drawbacks of poor light resistance and fading. 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 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 described above, the dye ink has excellent glossiness, transparency and scratch resistance, but is inferior in light resistance, fading resistance and bleeding resistance. On the contrary, the pigment ink is Although they are excellent in light resistance, discoloration resistance, and image blur resistance, they are contradictory properties inferior in gloss, transparency, and scratch resistance.

In order to solve the problems of low water resistance and light fastness while maintaining the excellent color reproducibility and transparency of the water-based ink using the water-soluble dye, an oil-soluble dye, a hydrophobic dye or the like is used. A method for coloring a water-dispersible resin has been proposed as an inkjet recording ink.

For example, JP 2001-11347 A and JP 2001-19880 A propose an ink composed of colored fine particles containing a coordination compound of a dye and a metal ion, and realize excellent light resistance. ing. In addition, Japanese Patent Laid-Open Nos. 2001-240763 and 2001-31660.
5, 2001-335734, an ink composed of colored fine particles containing an oil-soluble dye having a specific structure is proposed, and good color reproducibility, image storability, and stable emission characteristics are realized.

Further, each of the above-mentioned published patent publications describes an ink containing coloring fine particles having a small particle diameter. By using these inks, the effect as described in the patent can be obtained and the gloss can be further improved.

However, the inventors of the present invention conducted additional tests in accordance with the contents described in the above patent, and when these inks were used, the above effects could be obtained, but blue, green, and It has been found that there is a drawback that ink overflow easily occurs in an image area of a so-called secondary color such as red. In addition, these inks have revealed a new problem that images are rapidly faded by light irradiation under high humidity conditions, and urgent improvement is required.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an ink in an image area having a high glossiness and a large ink ejection amount in combination with a void type medium. An object of the present invention is to provide a water-based inkjet recording ink and a water-based inkjet recording ink set that have excellent penetrability and improved light resistance under high humidity conditions.

[0013]

The above object of the present invention has been achieved by the following constitution.

1. In a water-based inkjet recording ink containing colored fine particles containing a colorant and a resin, the residual mass ratio after drying with respect to the ink mass is 3 to 12%, and the volume average particle diameter of the colored fine particles is 10 nm or more,
It is less than 60 nm, and the difference between the initial elution rate of the coloring material in the coloring material dissolving agent of the colored fine particles and the elution rate of the coloring material after 2 minutes is 2
A water-based ink for inkjet recording, which is 0% or less.

2. 2. The water-based ink for inkjet recording according to item 1, wherein the coloring material is an oil-soluble dye.

3. 3. The water-based ink jet recording ink according to the item 1 or 2, wherein the colored fine particles have a core-shell structure.

4. The aqueous ink for inkjet recording according to any one of items 1 to 3, wherein the coloring material dissolving agent is ethyl acetate.

5. In a water-based inkjet recording ink set composed of a yellow ink, a magenta ink, a cyan ink, and a black ink, at least one color ink contains colored fine particles containing a coloring material and a resin, and after drying with respect to the ink mass. The residual mass ratio is 3 to 12%, and the volume average particle diameter of the colored fine particles is 1
A water content for ink jet recording, which is 0 nm or more and less than 60 nm, and the difference between the initial elution ratio of the coloring material in the coloring material dissolving agent of the colored fine particles and the elution ratio of the coloring material after 2 minutes is 20% or less. Ink set.

6. 6. The water-based inkjet recording ink set according to the above item 5, wherein the coloring material is an oil-soluble dye.

7. 7. The water-based ink set for inkjet recording according to the item 5 or 6, wherein the colored fine particles have a core-shell structure.

8. 8. The aqueous ink set for inkjet recording according to any one of items 5 to 7, wherein the coloring material dissolving agent is ethyl acetate.

9. 9. The water-based inkjet recording ink set described in any one of the items 5 to 8, wherein at least the magenta ink and the cyan ink are composed of two kinds of inks having different densities.

10. The ink having at least a high dye concentration contains colored fine particles containing a coloring material and a resin, the residual mass ratio after drying with respect to the ink mass is 3 to 12%, and the volume average particle diameter of the colored fine particles is 10 nm or more, 60 nm
10. The inkjet recording according to the above 9, wherein the difference between the initial elution rate of the coloring material in the coloring material dissolving agent of the colored fine particles and the elution rate of the coloring material after 2 minutes is 20% or less. Water-based ink set.

As a result of earnest studies in view of the above problems, the present inventors have found that the particle diameter of colored fine particles contained in a water-based ink for ink jet recording (hereinafter, also simply referred to as ink), the mass change rate before and after drying, and By using an ink that has a color material elution rate within a certain range with respect to the color material dissolving agent, it is possible to obtain an image that has sufficient glossiness, ink permeability, and excellent light resistance under high humidity conditions. I found it.

In recent years, recording media in which fine inorganic particles such as silica or alumina are formed into a fine void structure with a small amount of a water-soluble polymer binder, so-called void type media, have been widely used. .
This is characterized in that the fine void structure quickly absorbs the ink due to the capillary phenomenon and thus has excellent dryness. In addition, since the inorganic fine particles are extremely fine, the surface thereof is smooth and has excellent luster. By using such a recording medium, it becomes possible to obtain an ink-jet recorded image with high image quality comparable to that of a silver salt photograph.

However, when the above-mentioned colored fine particle-containing ink is printed on the above-mentioned void type media, since the colored fine particles are larger than the pore size of the void structure, they cannot penetrate into the interior and stick to the surface, and the gloss deteriorates. I will end up. This gloss can be improved to some extent by reducing the particle size of the colored fine particles. It can be interpreted that the reason is that the unevenness of the image surface formed from the colored fine particles becomes small.

However, if the ink contains a large amount of undissolved components such as colored fine particles, it tends to cause aggregation or solidification on the surface of the medium during recording, resulting in increased unevenness on the image surface and a small particle size. This results in deterioration of gloss. Further, when the amount of undissolved components such as colored fine particles is small, the coloring density is lowered, and therefore it is necessary to apply a large amount of ink onto the recording medium in order to obtain the required density. The permeation speed into the recording medium cannot catch up, and color turbidity occurs between different color images. Therefore, it is understood that there is an optimum range for the content of undissolved components such as colored fine particles.

Further, according to the study by the present inventors, the elution ratio of the coloring material when the coloring material dissolving agent acts on the colored fine particles is
It was found that the ink permeability and the light resistance under high humidity greatly affect the performance.

In the present invention, the initial elution rate of the coloring material and 2
The difference in the elution rate of the coloring material after the minute is important. The value obtained by subtracting the initial elution rate from the color material elution rate after 2 minutes represents the elution rate of the color material for convenience. The larger this value is, the easier the color material is to elute from the fine particles to the outside. Indicates that. For example, the elution rate is expected to increase when the coloring material is unevenly distributed on the surface of the coloring fine particles, or when the fine particles themselves are easily dissolved in the coloring material dissolving agent. In the case of an ink containing such colored fine particles, for example, the coloring material unevenly distributed on the surface acts as an adhesive, or the colored fine particles swell due to the action of a water-soluble organic solvent contained in the ink. As a result, the colored fine particles are likely to be fused to each other on the recording medium. In such a case, since the fine particles are fused to each other before the ink sufficiently penetrates on the recording medium, the unevenness of the image surface increases, and as a result, the gloss deteriorates. Guessed. In addition, in a color image portion formed by mixing a plurality of inks such as blue, green, and red, the penetration of the ink is hindered by the fusion of the colored fine particles, and the ink overflow easily occurs. This causes, for example, a defect that the region is blurred and blurred between images of different secondary colors that are in contact with each other.

Further, when an image composed of such colored fine particles is exposed to high humidity conditions, it is presumed that the colored fine particles swell due to humidity and the outside air easily penetrates into the particles. As a result, even if it shows good light resistance under normal humidity conditions, under high humidity conditions such as 80% RH, images are rapidly faded by light irradiation. It is speculated that such fading will become a problem in the summer and subtropical regions of Japan.

The inventors of the present invention have found that these drawbacks can be overcome by using an ink containing colored fine particles having a low color material elution rate, and have arrived at the present invention.

In the water base ink for ink jet recording or the water base ink set for ink jet recording according to claims 1 and 5, the residual mass ratio after drying with respect to the mass of the ink is 3 to 12%, and the volume average particles of the colored fine particles are The diameter is 10 nm or more and less than 60 nm, and the difference between the initial elution ratio of the coloring material in the coloring material dissolving agent of the colored fine particles and the elution ratio of the coloring material after 2 minutes is 20% or less.

In the present invention, the ratio of the residual mass after drying to the mass of the ink can be determined by the following method.

That is, 20 g (mass A) of the ink, which is a sample, is placed in a glass dish (75 mm in diameter) and 5
It is left for 1440 hours in an environment of 0 ° C. and 25% RH. Then, 20 g of a mixed solvent of water-methanol (1: 1) is added to the obtained ink residue, and this dispersion is separated into a liquid part and a solid part by a centrifugal separator. Then, the solid portion is dried again and the mass B is measured, whereby the mass after drying can be obtained. From the mass B and the amount of collected ink (mass A: 20 g), the residual mass ratio can be calculated by the following formula.

Residual mass ratio = mass B / mass A × 100 (%) Next, the coloring material dissolving agent and the elution rate in the present invention will be described.

The colorant dissolving agent referred to here is a solvent which dissolves 1 to 200 g / L of the colorant at 20 ° C.,
Various solvents can be used, from hydrophobic solvents to hydrophilic solvents. A solvent that dissolves the coloring material in an amount of 30 to 100 g / L is preferable. The preferred dissolving agent depends on the coloring material,
Generally, it is preferable that the compatibility parameter (Sp value) is close to that of the color material. Examples of the dye include ethyl acetate, dichloromethane, dichloroethane, chloroform, toluene, tetrahydrofuran, methanol, acetone, and the like. From the Sp value of the dye used, a hydrophobic solvent is preferable, and the dye according to claims 4 and 8 is used. In the invention,
It is preferably ethyl acetate.

The elution rate of the coloring material with respect to the coloring material dissolving agent means that the value when any one of the solvents satisfying the coloring material dissolving agent is used is within the range specified in the present invention. For example, the present invention. The elution rate of the color material is measured by mixing the ink and the color material dissolving agent in the range of 1: 1 to 1:39. Preferably,
It is preferable to perform the measurement at 1:19 for the convenience of the spectral absorption measurement. The elution rate of the coloring material is determined by measuring the absorbance at a certain time from the time of mixing and measuring the spectral absorption, and plotting the ratio at each time with the concentration when all the dyes are dissolved in the dissolving agent as 100%. . In this measurement, the measurement liquid should not be strongly stirred and shaken, and when stirring is performed, it is performed at a rotation speed of 100 rpm or less by a magnetic stirrer.

The initial elution rate of the color material with respect to the color material dissolving agent is the value of the elution rate obtained by extrapolating to the time 0 based on the slope of the elution rate data up to 1 minute. On the other hand, the elution rate of the coloring material after 2 minutes may be obtained by interpolation. The present invention is characterized in that the difference between the initial elution rate of the coloring material and the elution rate of the coloring material after 2 minutes with respect to the coloring material dissolving agent of the colored fine particles is 20% or less, preferably 1 to 10%. is there.

In the present invention, the volume average particle size of the colored fine particles is 10 nm or more and less than 60 nm.
There are two characteristics. 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 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.

Hereinafter, the details of the water-based ink for ink-jet recording and the water-based ink set for ink-jet recording of the present invention will be described.

Resins that can be used in the present invention (hereinafter,
(Also referred to as a polymer), it is possible to appropriately select and use from generally known polymers, but a particularly preferable polymer contains a polymer containing an acetal group as a main functional group, or a carbonate ester group. The polymer, the polymer having a hydroxyl group, and the polymer having an ester group, and particularly, the polymer constituting 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 by performing graft polymerization using light or radiation.

As the polymer containing acetal as a main functional group, polyvinyl butyral resin can be preferably mentioned. 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 groups of the original PVA is at most 80 mol.
%, 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.

Further, in the present invention, a vinyl resin which can be prepared by polymerizing a monomer having an ethylenically unsaturated bond can be preferably used, and a styrene resin and an 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, and acrylic acid 2
-Radical polymerization, cationic polymerization, anion polymerization, etc. of monomers such as ethylhexyl, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, hexyl methacrylate, 2-hydroxyethyl methacrylate and 2-ethylhexyl methacrylate. It can be used by polymerizing by the existing method.

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.

In the ink of the present invention, the polymer used for the colored fine particles is preferably blended in the ink in an amount of 0.5 to 50% by mass, more preferably 0.5 to 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 colored fine particles according to the present invention will be described. The colored fine particles according to the present invention 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. Examples of the method include a method of removing, a method of adding porous polymer fine particles to a coloring material solution, adsorbing and impregnating the coloring material on the fine particles, and a shelling method of coating the colored fine particles with a polymer. However, in the invention according to claims 3 and 7, it is preferable that the colored fine particles have a core-shell structure.

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 core surface simultaneously with the 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, the colored fine particles are made of a resin containing a coloring material. A core-shell structure in which the surface is further covered with a resin is preferable. In that case, the amount of polymer used for the shell is 5% by mass or more and 95% by mass or more of the total amount of polymer.
The following is preferable. 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 10% by mass
It is 90 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.

In the present invention, the colored fine particles can be formed in the core portion by using the hydrophobic high boiling point organic solvent alone or in combination with the polymer. When used alone, it can be achieved by substituting the polymer of the core portion in the above-mentioned method for preparing colored fine particles and providing the polymer shell. When used in combination with a polymer, the colored fine particles can be prepared by using it together with the core polymer.

(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.

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 dyes that can be used are not particularly limited, and examples thereof include oil dyes, disperse dyes, direct dyes, acid dyes and basic dyes. In the inventions according to claims 2 and 6,
It is preferable to use an oil-soluble dye.

As the hue, yellow, magenta, cyan, black, blue, green and red are preferably used, and particularly yellow oil-soluble dye, magenta oil-soluble dye, cyan oil-soluble dye and black oil-soluble dye are used respectively. 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 preferred specific example is, for example, Valifast Yell manufactured by Orient Chemical Industry Co., Ltd.
ow 4120, Valifast Yellow 3
150, Valifast Yellow 3108,
Valifast Yellow 2310N, Val
ifast Yellow 1101, Valifas
t Red 3320, Valifast Red 3
304, Valifast Red 1306, Val
ifast Blue 2610, Valifast
Blue 2606, Valifast Blue 1
603, Oil Yellow GG-S, OilYe
low 3G, Oil Yellow 129, Oi
l Yellow107, Oil Yellow 10
5, Oil Scarlet 308, Oil Red
RR, Oil Red OG, Oil Red 5
B, Oil Pink 312, Oil Blue BO
S, Oil Blue 613, Oil Blue 2
N, Oil Black BY, Oil Black
BS, Oil Black 860, Oil Blac
k 5970, Oil Black 5906, Oil
Black 5905, Kay manufactured by Nippon Kayaku Co., Ltd.
aset Yellow SF-G, Kayaset
Yellow K-CL, Kayaset Yellow
w GN, Kayaset Yellow AG, K
ayaset Yellow 2G, Kayaset
Red SF-4G, Kayaset Red KB
L, Kayaset Red A-BR, Kayase
tMagenta312, Kayaset Blue
K-FL, FS Yellow manufactured by Arimoto Chemical Industry Co., Ltd.
w 1015, FS Magenta 1404, FS
Cyan 1522, FS Blue 1504,
C. I. Solvent Yellow 88, Sol
Vent Yellow 83, Solvent Ye
low 82, Solvent Yellow 7
9, Solvent Yellow 56, Solve
nt Yellow 29, Solvent Yell
ow 19, Solvent Yellow 16, S
solvent Yellow 14, Solvent
Yellow 04, Solvent Yellow
03, Solvent Yellow 02, Solv
ent Yellow 01, C.I. I. Solvent
Red 84: 1, C.I. I. Solvent Red
84, C.I. I. SolventRed 218, C.I.
I. Solvent Red 132, C.I. I. Sol
Vent Red 73, C.I. I. Solvent R
ed 72, C.I. I. Solvent Red 51,
C. I. Solvent Red 43, C.I. I. So
lvent Red 27, C.I. I. Solvent
Red 24, Solvent Red 18, Sol
Vent Red 01, Solvent Blue 7
0, Solvent Blue 67, Solvent
Blue44, Solvent Blue 40, S
solvent Blue 35, Solvent Bl
ue 11, Solvent Blue 02, So
lvent Blue 01, Solvent Bla
ck 43, C.I. I. Solvent Black 7
0, C.I. I. Solvent Black 34, C.I.
I. Solvent Black 29, C.I. I. So
lvent Black 27, C.I. I. Solven
t Black 22, C.I. I. Solvent Bl
ack 7, C.I. I. Solvent Black
3, C.I. I. Solvent Violet 3, C.I.
I. Solvent Green 3 and 7, etc. are mentioned.

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 thereof is represented by the following general formula [I].

In the general formula [I] 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.

As the ligand other than the dye represented by A,
Represents a monovalent or divalent ligand, for example, a halide ion or a carboxylic acid derivative, or the following general formula [A]
Can be mentioned.

[0066]

[Chemical 1]

In the general formula [A], R _A is a cyano group,
Acyl group, alkyloxycarbonyl group, cycloalkyloxycarbonyl group, aryloxycarbonyl group,
Alternatively, it represents a heterocyclic group. R _B is an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group,
Represents an aralkyl group or a heterocyclic group. X represents a cyano group, an alkyloxycarbonyl group, a cycloalkyloxycarbonyl group, or an aryloxycarbonyl group.

Although various dye structures are conceivable as the dye represented by Dye and capable of forming a coordination bond with the metal, 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 0368; 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.

[0071]

[Chemical 2]

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) or (3) is preferable, and the dye represented by the general formula (3) is more preferable. Further, n is preferably a dye having 0.

Examples of dyes preferably used in the present invention are shown below, but the present invention is not limited thereto.

[0077]

[Chemical 3]

[0078]

[Chemical 4]

[0079]

[Chemical 5]

[0080]

[Chemical 6]

[0081]

[Chemical 7]

[0082]

[Chemical 8]

The pigment is not limited to the following, but as a preferred specific example, the carbon black pigment is No. Mitsubishi Kasei Co. 2300, No. 900, M
CF-88, No. 33, No. 40, No. 45, N
o. 52, MA7, MA8, MA100, No. 52. 220
OB, Columbia Raven 700, Raven
5750, Raven 5250, Raven 50
00, Raven 3500, Raven 1255,
Cabot Co. Regal 400R, Regal 3
30R, Regal 660R, Mogul L, Mo
narch 700, Monarch 800, Mon
arch 880, Monarch 900, Mona
rch 1000, Monarch 1100, Mon
arch1300, Monarch 1400, Degussa's Color BlackFW1, Color Bl
ack FW2, Color Black FW2V,
Color Black FW18, Color Bl
ack FW200, Color Black S15
0, Color Black S160, Color
Black S170, Printex 35, Pri
ntex U, Printex V, Printex
140U, Printex 140V, Special
Black 6, Special Black 5,
Special Black 4A, Special
It is possible to use Black 4, Maxsorb G-40, Maxsorb G-15, Maxsorb G-08, etc. manufactured by Kansai Thermochemical Co., Inc.

As the yellow pigment, C.I. I. Pigm
ent Yellow 1, C.I. I. Pigment
Yellow 2, C.I. I. Pigment Yell
ow3, C.I. I. Pigment Yellow 1
2, C.I. I. Pigment Yellow 13, C.I.
I. Pigment Yellow 14, C.I. I. P
igment Yellow 16, C.I. I. Pigm
ent Yellow 17, C.I. I. Pigment
Yellow 73, C.I. I. Pigment Ye
low 74, C.I. I. Pigment Yellow
w 75, C.I. I. Pigment Yellow 8
3, C.I. I. Pigment Yellow 93,
C. I. Pigment Yellow 95, C.I.
I. Pigment Yellow 97, C.I. I. P
igment Yellow 98, C.I. I. Pigm
ent Yellow 114, C.I. I. Pigmen
tYellow 128, C.I. I. Pigment Y
ellow 129, C.I. I. Pigment Yel
low 151, C.I. I. Pigment Yellow
w 154, magenta pigments include C.I. I. Pigm
ent Red 5, C.I. I. Pigment Red
7, C.I. I. Pigment Red 12, C.I.
I. Pigment Red 48 (Ca), C.I. I.
Pigment Red 48 (Mn), C.I. I. Pi
gment Red 57 (Ca), C.I. I. Pigm
ent Red 57: 1, C.I. I. Pigment
Red 112, C.I. I. Pigment Red 1
23, C.I. I. Pigment Red 168, C.I.
I. Pigment Red 184, C.I. I. Pig
ment Red 202, and cyan pigments include C.I.
I. Pigment Blue 1, C.I. I. Pigm
ent Blue 2, C.I. I. Pigment Bl
ue 3, C.I. I. Pigment Blue 15:
3, C.I. I. Pigment Blue 15:34,
C. I. Pigment Blue 16, C.I. I. P
igmentBlue 22, C.I. I. Pigment
Blue 60, C.I. I. VatBlue 4, C.I.
I. The colored fine particles according to the present invention such as Vat Blue 60 and the like have a solid content of 3 to 20 in the ink.
It is preferably blended by mass%, more preferably 3-15 mass%. If the blending amount of the colored fine particles is less than 3% by mass, the printing density is insufficient, and if it exceeds 20% by mass, the stability of the suspension with time decreases,
Since there is a tendency for the particle size to increase due to agglomeration and the like, it is preferably within the above range.

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 [II].

General formula [II] 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 [II] 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 [II] preferably does not have such a 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) are used. Libutanol, pentanol, hexanol, cyclohexanol, benzyl alcohol, etc., polyhydric alcohols (eg 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. But at least one of the aqueous solvents is
Polyhydric alcohol ethers or polyhydric alcohols are preferable, and more preferable polyhydric alcohol ethers are ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, ethylene glycol monophenyl. It is an ether, and the polyhydric alcohol is 1,2-hexanediol or 1,2-pentanediol, and particularly preferably triethylene glycol monobutyl ether or 1,2-hexanediol.

In the present invention, the content of the aqueous solvent is preferably 10% by mass or more and 60% by mass or less, more preferably 20 to 50% by mass with respect to the total mass of the ink.

The ink according to the present invention comprises a suspension of a polymer containing water as a medium and encapsulating the above coloring material,
In the suspension, in addition to the above-mentioned aqueous solvent, various conventionally known additives, for example, dispersants, defoaming agents such as silicone, antifungal agents such as chloromethylphenol, and / or chelating agents such as EDTA. Further, 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 diameter of the suspension is obtained. preferable.

Commercially available products can also be used as the dispersant. Examples of such commercially available products 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 exceeds 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 according to the present invention will be described. The ink according to the present invention can be manufactured by various emulsification methods.

In the present invention, the volume average particle size of the colored fine particles is preferably 5 to 100 nm, but the method for achieving the average particle size defined above is not particularly limited, but is described, for example, in the above. This can be achieved by appropriately selecting or combining the type and amount of the dispersant, or the following emulsification methods.

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 apparatus using high-speed rotary shearing include a disper mixer as described on pages 255-256 of “Advancement of functional emulsifier / emulsification technology and its application development” and a 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 under 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, or 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. .

The ink of the present invention can be produced by so-called phase inversion emulsification in addition to using the above-mentioned 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 remove the colored fine particles of the present invention having a desired concentration. An ink containing is obtained.

In the ink according to the present invention, the surface tension of the inkjet ink is 25 mN / m or more,
It is preferably 50 mN / m or less, 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 the ink according to the present invention, the pH of the ink is preferably 6.0 or more and 11.0 or less, and more preferably 8.0 or more and 10.0 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,
Examples thereof include inorganic alkali agents such as hydroxides of alkali metals such as sodium hydroxide, lithium hydroxide and potassium hydroxide, organic acids, and mineral acids.

In the ink according to the present invention, it is possible to use one kind or two or more kinds of anionic surfactant, nonionic surfactant and cationic surfactant. 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.

A natural polymer is a preferable example of the water-soluble polymer. 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, as a preferable example of the water-soluble polymer, a synthetic polymer can be mentioned. Polyvinyl alcohols, polyvinyl pyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymers, potassium acrylate-acrylonitrile copolymers. 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
It is more preferably 0 or more and 20,000 or less. 1,000
If it is less than 200, 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 (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 according to 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.

Recently, as latex polymer particles,
In addition to the latex in which the polymer particles are uniformly dispersed throughout the particle, there is also a latex in which core / shell type polymer particles having different compositions in the central portion and the outer edge portion of the particle are dispersed, but this type of latex is also preferable. Can be 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 or 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.

In the invention according to claim 9, it is preferable that at least the magenta ink and the cyan ink are independent inks of two or more kinds having different color material densities, that is, so-called dark and light inks. This can reduce the graininess by using a low-concentration water-based ink and form a high-quality image without so-called "roughness".

The density ratio of the water-based ink sets having different densities may be set to any value, but in order to perform smooth gradation reproduction, the ratio of the high density ink and the low density ink [(density of low density ink) / (Density of high density ink)] is 0.1
It is preferably between 1.0, more preferably between 0.2 and 0.5, particularly preferably between 0.25 and 0.4.

Next, a recording medium that can be used in the present invention will be described. The recording medium used in the present invention includes plain paper, coated paper, swelling inkjet recording paper provided with an ink receiving layer that swells by absorbing an ink liquid, and void type inkjet recording paper having a porous ink receiving layer. A recording paper, or one using a resin support such as a polyethylene terephthalate film in place of the base paper, can be used, but in the present invention, it is preferable to use a void-type porous inkjet recording medium, and a combination thereof is used. The effect of the present invention can be exerted most.

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. In the case of using the ink of the present invention, any of the methods provides good results, but for adapting to continuous high-speed printing, a faster ink absorption speed of the recording medium is suitable. From this point, the void type can be particularly preferably used in the present invention.

In the present invention, it is preferable that the resin constituting the colored fine particles contained in the ink set is melted and compressed to form a film by heating and / or pressurizing treatment after image recording. The heat treatment is carried out for the purpose of improving light resistance and gloss by melting and forming a film of a resin forming the colored fine particles contained in the ink set. In the heat treatment, it is desirable to apply the amount of heat or pressure necessary to almost completely melt and form a film of the resin forming the colored fine particles contained in the ink set, or heat and pressure at the same time. It is desirable to heat and pressurize for a short time in order to shorten the length of the ink, and as long as there is no substantial difference in the image quality, melting of the resin that constitutes the colored fine particles contained in the ink set, film The chemical treatment need not be completed.

In order to give a necessary amount of heat in a short time,
It is desirable to heat using a heat source as high as possible, but if the temperature is excessively high, the support may be damaged, severe curling may occur, or the image surface may be roughened, and roller contamination may occur. Preferably 100
The range of up to 150 ° C is more preferable. Further, the pressure to be applied is preferably in the range of 9.8 × 10 ^{4 to} 4.9 × 10 ⁶ Pa.

The heating method may be carried out by a heater built in the printer or by another heater. As the heating means, using a heating roller or a heating belt,
It is suitable for continuous processing in a small space, preventing unevenness. In addition, it is cost-effective to use a heat fixing device for electrophotography. For example, a method of heating and pressurizing by passing a recording medium between a heating roller having a built-in heating element and a pressure roller, a method of heat treatment by sandwiching the recording medium between two heating rollers, or a pair of heating rollers. There is a method of providing a fixing belt between them and performing heat treatment.

The heating roller is a hollow roller and is rotated by the driving means. As a heat source, for example, a heating element made of a halogen lamp heater, a ceramic heater, a nichrome wire or the like is built in the roller. The roller is preferably made of a material having high heat conductivity, and particularly preferably a metal roller. The roller surface is preferably coated with a fluororesin to prevent contamination. In addition, a silicon rubber roller coated with heat resistant silicon can be used.

When the heating roller is used, the conveying speed of the recording medium is preferably in the range of 1 to 15 mm / sec. this is,
It was found that it is preferable not only from the viewpoint of high-speed processing but also from the viewpoint of image quality improvement. Furthermore, in order to obtain high texture and gloss, it is preferable to apply pressure simultaneously with or immediately after heating. The pressure to be applied is 9.8 × 10 ^{4 to} 4.9.
The range of × 10 ⁶ Pa is preferable. This is because pressurization promotes film formation.

FIG. 1 shows an example of an ink jet recording apparatus having a heating roller which can be used in the present invention. Further, FIG. 2 shows another example of an ink jet recording apparatus having a heating belt which can be used in the present invention.

[0133]

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

Example 1 << Synthesis of Polymer >> [Synthesis Example 1: Synthesis of Polymer P-1] 15.0 g of n-
Butyl acrylate, 10.0 g reaction product monomer of glycidyl methacrylate and soybean oil fatty acid, 25.0 g
Of styrene and 150 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 completely dissolve the above monomers. 0.5 for this
AIBN (azobisisobutyronitrile) (g) was added, and the mixture was heated under reflux with a heater for 4 hours to obtain an ethyl acetate solution of the target polymer P-1.

Other polymers were also synthesized with the monomer composition shown in Table 1 according to the above synthesis example. The details of the compound abbreviations shown in Table 1 are as follows.

BA: n-butyl acrylate GFA: reaction product monomer of glycidyl methacrylate and soybean oil fatty acid (Blenmer G-FA manufactured by NOF CORPORATION) St: styrene SMA: stearyl methacrylate AAEM: 2-acetoacetoxyethyl methacrylate (Nippon Synthetic Chemistry) HEMA: 2-hydroxyethyl methacrylate AN-6: styrene macromer (manufactured by Toagosei) EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate GMA: glycidyl methacrylate LMA: lauryl methacrylate BMA: n-butyl methacrylate PFDA: 1H, 1H, 2H, 2H-perfluorodecyl acrylate AA: acrylic acid PEGMA: polyethylene glycol methacrylate MAA: methacrylic acid FM-0711: silyl Macronmer (manufactured by Chisso) EtSH: Ethyl mercaptan MLAA: Maleic acid AS-6: Styrene macromer (manufactured by Toagosei) DMH: Dodecyl mercaptan Polymers P-5, 7 and 8 are in the patent publications listed in the remarks column. It was synthesized according to the description of.

[0137]

[Table 1]

<< Preparation of Colored Fine Particle Dispersion >> [Preparation Example 1: Preparation of Colored Fine Particle Dispersion 6] 40.0 g of the polymer P-1 solution synthesized in Synthesis Example 1 above, 10.0
g of magenta dye (exemplary compound DM-4), and 120
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 magenta dye. Then, after adding 230 g of an aqueous solution containing 1.5 g of sodium lauryl sulfate dropwise and stirring,
The mixture was emulsified for 300 seconds using Clearmix W Motion CLM-0.8W (manufactured by M Technique). afterwards,
Ethyl acetate was removed under reduced pressure to prepare a core type colored fine particle dispersion impregnated with a magenta dye. Furthermore, 0.5 g of potassium persulfate was added and dissolved, and a heater was attached to 70
After warming to ℃, 7.5g of styrene and 2.5g of 2
The reaction mixture was allowed to react for 5 hours while adding a mixed solution of -hydroxyethyl methacrylate to obtain a core-shell type colored fine particle dispersion 6. The average particle diameter of the colored fine particles in the obtained colored fine particle dispersion was 46 nm. The average particle diameter is a volume average particle diameter measured by using a laser particle size analysis system manufactured by Otsuka Electronics.

Other colored fine particle dispersions were also prepared according to the above Preparation Example 1 with the compositions shown in Table 2. The details of the compound abbreviations shown in Table 2 are as follows.

DA: FSY1015 and OY129 1:
1 mixture Solv-1: S-1 and S-2 3: 4 mixture Solv-2: S-1 and S-2 4: 7 mixture P-A: St / HEMA = 50/50 P- B: St / HEMA = 75/25 PC: MMA / HEMA = 75/28 PD: St / EHA / HEMA = 50/20/30 OT-P: Perex OT-P (manufactured by Kao) SDS: Lauryl Sulfuric acid sulfonic acid sodium salt BL-S, BL-10: Polyvinyl butyral resin (manufactured by Sekisui Chemical Co., Ltd.) FSY1015: FS Yellow 1015 (manufactured by Arimoto Chemical Co., Ltd.) OY-129: Oil Yellow 129 (manufactured by Orient Chemical Co.) K-FL: Kayaset K -FL (manufactured by Nippon Kayaku) FSB1504: FS Blue 1540 (manufactured by Arimoto Kagaku) OB860: Oil Black 860 (manufactured by Orient Kagaku) And, with respect to the coloring material 2-4 in Table 2 were prepared according to the method described in published patent in publications described in the remarks column.

[0141]

[Table 2]

[0142]

[Chemical 9]

<< Preparation of Ink >> Inks 101 to 118 were prepared using the colored fine particle dispersions prepared above. Pure water, the ink solvent shown in Table 3 and the surfactant were added to each of the colored fine particle dispersions so that the concentrations thereof were shown in Table 3. The amount of each colored fine particle dispersion was adjusted so that the coloring material concentration in the ink was the dye content shown in Table 3. When the colorant concentration in the dispersion was insufficient and the colorant concentration in the ink could not be adjusted to a predetermined value, water was removed from the colored fine particle dispersion under reduced pressure and concentrated to prepare.

The dry residue mass ratio (%) and dye elution rate ratio (%) shown in Table 3 were measured according to the method described above, and the obtained results are shown in Table 3.

The details of the compound abbreviations shown in Table 3 are as follows. DEG: diethylene glycol gly: glycerin TEGBE: triethylene glycol monobutyl ether EG: ethylene glycol PG: propylene glycol TriPG: tripropylene glycol HDO: 1,2-hexanediol IPA: 2-propanol E20C: emal 20C (manufactured by Kao) E1010: olphin E1010 (manufactured by Nissin Chemical)

[0146]

[Table 3]

<< Preparation of Image and Evaluation >> (Preparation of Evaluation Image) Among the prepared inks, the inks shown in Table 4 were put into genuine black ink cartridges for the color inkjet printer CL-700 (manufactured by Epson). As a refilling and recording medium, inkjet paper Photolike QP manufactured by Konica Corporation
(Hereinafter, abbreviated as photo-like QP), a wedge image in which output density is divided into 16 steps from 0% to 100% (outputs in a patch shape of 3 cm x 3 cm for each density)
Was output and used for each of the following evaluations.

In the image formation, the driver was set to use only the black ink cartridge so as not to mix other colors, and the image was output.

(Evaluation of Glossiness) With respect to a wedge image having an output of 80% of each image sample formed on Photolike QP, the gloss feeling was visually evaluated by 20 test subjects and classified according to the following criteria.

⊚: 16 or more people judged to have sufficient glossiness ○: 12 to 15 people judged to have sufficient glossiness Δ: 8 people judged to have sufficient glossiness ~ 11 people x: 7 or less people were judged to have a sufficient glossy feeling. In the above evaluation rank, ⊚ and ○ were judged to be practically preferable ranks.

(Evaluation of light fastness) <Light fastness-1> As for the light fastness of each printed image, a wedge image having a reflection density of about 1.0 was used in an environment of 23 ° C. and 50% RH with a xenon fade meter. Using 70,000
After irradiating with IX for 168 hours, the reflection density residual rate was measured according to the following formula.

Reflection density residual ratio = (reflection density after irradiation of xenon / fade meter / reflection density before irradiation of xenon / fade meter) × 100 (%) For light resistance-1, the reflection density residual ratio is a criterion shown below. It evaluated according to.

A: Remaining reflection density is 85% or more B: Remaining reflection density is 70 to less than 85% C: Remaining reflection density is 50 to less than 70% D: Remaining reflection density is less than 50% Evaluation rank above In A, it was judged that A and B were practically preferable ranks.

<Light resistance-2> In the evaluation of the above light resistance-1, the irradiation environment by the xenon fade meter was changed to
The light resistance-2 was evaluated in the same manner except that the temperature was changed to 40 ° C. and 80% RH.

Table 4 shows the evaluation results obtained as described above.

[0156]

[Table 4]

As is clear from Table 4, all the inks of the present invention have sufficient gloss and light resistance. Especially, light resistance under high temperature and high humidity environment-2
In, the remarkable result was shown. On the other hand, in the comparative ink, the light resistance under the environment of 23 ° C. and 50% RH-
Although 1 was sufficient, with respect to glossiness or light resistance-2 under high temperature and high humidity, insufficient performance was obtained.

Example 2 << Preparation of Ink Set >> From the inks prepared in Example 1 above, ink sets 202 to 204 were prepared by combining the inks shown in Table 5.

The ink set 201 shown in Table 5 was used.
Is a genuine ink consisting of a water-soluble dye for PM890C (manufactured by Epson) [Y1: genuine ink Y, M1: genuine ink M (dark ink), M2: genuine ink LM (light ink),
C1: genuine ink C (dark ink), C2: genuine ink L
C (light ink)] was used as it was.

<< Creation and Evaluation of Image >> (Creation of Evaluation Image) Each color ink of each ink set prepared above was used in a color inkjet printer PM890.
A gray wedge image (each of which has an output density of 0% to 100% divided into 16 steps by using each ink set, is packed in a C (manufactured by Epson) genuine color ink cartridge, and is used as a recording medium on Photolike QP. Concentration 3c
Output in the form of a patch of m × 3 cm), and the printed image thus prepared is evaluated for glossiness and light resistance according to the method described in Example 1, and is also evaluated for color turbidity resistance according to the following method. went.

(Evaluation of color turbidity resistance) <Color turbidity resistance-1> Each of the prepared inks was packed in a genuine color ink cartridge for a color ink jet printer PM890C (manufactured by Epson), and yellow, magenta and After printing a solid image of cyan, a black thin line was printed thereon, and the presence or absence of bleeding between colors and color turbidity due to contact of two colors was visually observed, and evaluation was performed according to the following criteria. .

4: Almost no color turbidity was observed in all colors 3: 1, 2 and slightly color turbidity were observed at the boundary 2: several colors were observed at the boundary 1: Quite intense boundary color turbidity was confirmed in all colors <Color turbidity resistance-2> Each of the inks prepared above was packed in a genuine color ink cartridge for a color inkjet printer PM890C (manufactured by Epson) and printed on Photolike QP. A belt-shaped test chart of yellow, magenta, cyan, blue, green, red, and black was printed on. Here, the output density of the chart of each color is changed from 60% to 10
Charts with different densities up to 100% were made by increasing the same at the same time. The presence or absence of color turbidity at the boundary of each chart was visually observed and evaluated according to the following criteria.

IV: Almost no color turbidity was observed at the boundary in all charts III: Slight color turbidity was observed at the boundary between 1 and 2 colors II: Color turbidity at the boundary was observed in several colors Observed I: In almost all the charts, IV and III were judged to be practically preferable ranks in the above evaluation ranks in which color turbidity at the boundary was confirmed.

Table 5 shows the evaluation results obtained as described above.

[0165]

[Table 5]

As is clear from Table 5, all the samples of the present invention have sufficient glossiness, light resistance and color turbidity resistance. On the other hand, none of the comparative samples could meet the target.

[0167]

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a water-based inkjet recording ink and a water-based inkjet recording ink set which are excellent in glossiness, ink penetration (color turbidity resistance) and light resistance under high humidity. .

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of an inkjet recording apparatus having a heating roller used in the present invention.

FIG. 2 is a schematic configuration diagram showing another example of an inkjet recording apparatus having a heating belt used in the present invention.

[Explanation of symbols]

1 recording medium 1a slack section 2 Transporting means for recording medium 21 Transport roller pair 3 recording head 34 recording medium holding unit 4 heating and pressurizing means 41 heating roller 42 Crimping roller 43 heating element 44 heating belt 45 Lower belt 46 Driven roller 5 Temperature sensor 6 Recording medium cutting means 61, 62 cutter 7 Slack forming means 71 First Roller Pair 72 Second Roller Pair

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2C056 EA13 FC02 HA45 HA46                 2H086 BA01 BA52 BA53 BA56 BA60                       BA62                 4J039 AD06 AD07 AD09 AE06 BC22                       BD04 BE01 BE02 BE07 BE12                       CA03 EA15 EA16 EA17 EA19                       EA33 EA35 GA24

Claims (10)

[Claims] 1. A water-based ink for inkjet recording containing colored fine particles containing a coloring material and a resin, wherein the residual mass ratio after drying with respect to the ink mass is 3 to 12%, and the volume average particle diameter of the colored fine particles. Is 10 nm or more, 6
It is less than 0 nm, and the difference between the initial elution rate of the coloring material in the coloring material dissolving agent of the colored fine particles and the elution rate of the coloring material after 2 minutes is 20
% Or less, a water-based ink for inkjet recording. 2. The water-based ink for inkjet recording according to claim 1, wherein the coloring material is an oil-soluble dye. 3. The aqueous ink for inkjet recording according to claim 1, wherein the colored fine particles have a core-shell structure. 4. The water-based inkjet recording ink according to claim 1, wherein the coloring material dissolving agent is ethyl acetate. 5. A water-based ink set for inkjet recording comprising at least 1 of a yellow ink, a magenta ink, a cyan ink, and a black ink.
The color ink contains colored fine particles containing a coloring material and a resin, and the residual mass ratio after drying with respect to the mass of the ink is 3
˜12%, and the volume average particle diameter of the colored fine particles is 10
nm or more and less than 60 nm, and the difference between the initial elution ratio of the coloring material in the coloring material dissolving agent of the colored fine particles and the elution ratio of the coloring material after 2 minutes is 20% or less. Ink set. 6. The water-based ink set for ink jet recording according to claim 5, wherein the coloring material is an oil-soluble dye. 7. The water-based ink set for inkjet recording according to claim 5, wherein the colored fine particles have a core-shell structure. 8. The water-based inkjet recording ink set according to claim 5, wherein the coloring material dissolving agent is ethyl acetate. 9. The water-based inkjet recording ink set according to claim 5, wherein at least the magenta ink and the cyan ink are composed of two types of ink having different densities. . 10. An ink having at least a high dye concentration contains colored fine particles containing a coloring material and a resin, and the residual mass ratio after drying with respect to the ink mass is 3 to 12%, and the volume average particles of the colored fine particles. The diameter is 10 nm or more and less than 60 nm, and the difference between the initial elution rate of the coloring material and the elution rate of the coloring material after 2 minutes in the coloring material dissolving agent of the colored fine particles is 20% or less. 9. A water-based ink set for inkjet recording according to item 9.