JP2015030788A - Inkjet ink, ink cartridge, and inkjet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet ink excellent in discharge stability and capable of reducing the curl amount of plain paper.SOLUTION: An inkjet ink contains a polyalcohol as a water-soluble organic solvent, and compounds represented by the general formula (I) and general formula (II) in the figure.

Description

  The present invention relates to an ink jet ink, an ink cartridge using the ink, and an ink jet recording apparatus.

The aqueous pigment ink-jet ink has advantages such as less bleeding, high image density, and less show-through in printing on plain paper. However, in the case of printing on plain paper, when the amount of ink attached is large, such as a photograph or a figure, the plain paper is back curled immediately after printing (back curl is a phenomenon in which the paper is warped on the side opposite to the printing surface. ) Easy to do. If the plain paper is back-curled immediately after printing, a paper conveyance failure occurs in the paper conveyance process in the inkjet printer. In particular, if the paper is back curled immediately after high-speed printing or double-sided printing, paper conveyance is very difficult.
Therefore, there is a demand for an ink jet ink that has as little back curl as possible even in the case where the ink adhesion amount is large. In particular, the need for a high-speed inkjet printer with a line head is higher than that of a serial printer.
As a known technique for suppressing the curling of paper, a method is proposed in which an alcohol liquid is applied to paper prior to recording with ink, the paper is substantially dried at the recording position, and then recording with ink is performed. (Patent Document 1). In this document, the hydroxyl group of the alcohol liquid is bonded to the hydroxyl group present at the bonding point due to hydrogen bonding between the cellulose fibers of the paper, and the water molecules in the ink are blocked at the hydrophobic group portion of the alcohol liquid. When a large amount of water-based ink is applied, there is no effect, and curling suppression immediately after printing cannot be achieved.

Also proposed is a recording method for ejecting ink and a reaction liquid that reacts with ink, and ejecting the reaction liquid onto a recording medium on the opposite side that is recorded with ink by the same data as the data recorded with ink. (Patent Document 2). However, since the configuration of the recording apparatus is complicated and curling cannot be suppressed unless an equal amount of a reaction liquid made with a composition almost equivalent to ink is ejected, it is economically difficult. Furthermore, when it is close to solid printing, since both sides of the paper contain a lot of moisture, the paper is not stiff and paper conveyance becomes severe.
On the other hand, Patent Document 3 discloses an ink-jet ink composition containing diglycerin or polyglycerin and polyethylene glycol monoalkyl ether in the ink, and Patent Document 4 contains polyethylene glycol monomethyl ether in the ink. An inkjet ink composition is disclosed. However, these proposals are also ineffective when a large amount of water-based ink is driven by high-speed printing, and curl suppression immediately after printing cannot be satisfied. In addition, since the equilibrium moisture content of the solvent is small, the discharge stability cannot be ensured.

  An object of the present invention is to provide an inkjet ink that can reduce the curl amount immediately after ink printing on plain paper and is excellent in ejection stability.

上記式中、Ｒ１は、炭素数４〜６のアルキル基を表す。

上記式中、Ｒ２は、炭素数８又は１２のアルキル基、炭素数６の環状アルキルのいずれかを表す。 The above problem is solved by the following invention 1).
1) In an inkjet ink containing at least water, a water-soluble organic solvent, a surfactant and a colorant, the water-soluble organic solvent has an equilibrium water content of 30% by weight or more at a temperature of 23 ° C. and a relative humidity of 80%. A compound containing a polyhydric alcohol and having at least one amide compound represented by the following general formula (I), an amide compound represented by the following formula (I), and a compound represented by the following general formula (II): An ink-jet ink comprising at least one kind.

In the above formula, R1 represents an alkyl group having 4 to 6 carbon atoms.

In the above formula, R2 represents either an alkyl group having 8 or 12 carbon atoms or a cyclic alkyl having 6 carbon atoms.

  According to the present invention, it is possible to reduce an amount of curling immediately after ink printing on plain paper and to provide an ink jet ink excellent in ejection stability. Further, it is possible to provide an ink-jet ink that is excellent in drying properties for general-purpose printing paper and has less beading (density unevenness) in printing gloss paper.

Schematic which shows an example of an ink cartridge. FIG. 6 is a schematic diagram illustrating a modification of the ink cartridge of FIG. 1. FIG. 3 is a perspective view of the ink jet recording apparatus in a state where a cover of the ink cartridge loading unit is opened. Sectional drawing explaining the whole structure of the inkjet recording device of FIG. FIG. 2 is a schematic enlarged view showing an ink jet head of the ink jet recording apparatus. The figure explaining the difference in action of the water-insoluble organic substance which has water and a hydroxyl group between cellulose molecules. (A) Schematic diagram of elementary fibrils, (b) Schematic diagram showing hydrogen bonds generated between two cellulose molecules, (c) Hydrogen bonds when water molecules exist between two cellulose molecules Pattern diagram. Schematic which shows the internal structure of the prototype line head printer used for evaluation of curl amount.

Hereinafter, the present invention 1) will be described in detail, but the embodiments of the present invention include the following inventions 2) to 5), which will be described together.
2) The water-soluble organic solvent contains at least one alkylalkanediol having an alkanediol having 3 to 6 carbon atoms as a main chain and an alkyl group having 1 to 2 carbon atoms in a branched chain. ) Inkjet ink as described in the above.
3) The alkylalkanediol is converted into 2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3- The inkjet ink according to 2), which is at least one selected from xylenediol.
4) An ink cartridge comprising the ink-jet ink according to any one of 1) to 3) contained in a container.
5) An ink jet recording apparatus comprising the ink cartridge according to 4) and having ink flying means for forming an image on a recording medium by applying a stimulus to the ink jet ink and causing the ink to fly.

The inkjet ink of the present invention (hereinafter sometimes referred to as ink) contains at least water, a water-soluble organic solvent, a surfactant, and a colorant, and further contains other components as necessary.
A feature of the present invention is that the water-soluble organic solvent is represented by at least one amide compound represented by the general formula (I), the amide compound represented by the formula (I), and the general formula (II). The ink contains at least one kind of compound, whereby an ink in which curling immediately after printing is suppressed can be obtained. The reason is that the amide compound represented by the general formulas (I) and (I) and the compound represented by the general formula (II) are difficult to break hydrogen bonds between cellulose molecules even if they penetrate between the cellulose molecules. This is presumed.

This reason will be described in more detail.
The amide compound represented by the general formula (I) and the formula (I) and the compound represented by the general formula (II) are both more hydrophilic than conventional water-soluble organic solvents (glycerin, butanediol, etc.). And the hydrophobic balance is on the hydrophobic side, and the proportion of hydrophilic groups capable of hydrogen bonding in the molecule is small. In particular, among the compounds represented by the general formula (II), for compounds in which R2 is either an alkyl group having 8 or 12 carbon atoms or a cyclic alkyl group having 6 carbon atoms, R2 that has been known so far is Compared with the compound represented by the general formula (II) which is a hydrogen atom or an alkyl group having 1 carbon atom, the solubility in water is small, and the balance as a water-soluble organic solvent is on the hydrophobic side. Therefore, it is presumed that the solvent hardly breaks hydrogen bonds between cellulose molecules even if it penetrates between cellulose molecules. In short, this model is “low aggressiveness against hydrogen bonds between cellulose molecules”.

Moreover, since the water-soluble organic solvent on the hydrophobic side with the balance as described above has a low surface tension, it penetrates between cellulose molecules in advance, as in hydrogen bonding with water molecules shown in FIG. In the amide compounds represented by the general formulas (I) and (I), the amide group hydrogen bonds to the hydroxyl group of the cellulose molecule and remains in the cellulose molecule part, and the hydrophobic group of the alkyl group part covers the hydrogen bond of the cellulose molecule. However, it is presumed that the contact with water, which is a volatile hydrophilic group-rich solvent, is inhibited, and it is difficult to break hydrogen bonds between cellulose molecules. In short, this model is called “the hydrogen bond coverage of cellulose molecules”.
Further, since the compound represented by the general formula (II) does not have a hydroxyl group or a carboxyl group, it does not participate in cellulose fiber hydrogen bonding, and therefore water molecules exist between the cellulose molecules shown in FIG. It is estimated that this is because it does not swell as it did.

  Further, the hydrogen bond of the cellulose molecule is covered and the contact with the aqueous continuous phase (alcohol, water, etc.) is inhibited, the amide compound represented by the general formula (I) and the formula (I), Since the water-soluble organic solvent which is a compound represented by the general formula (II) and has an auxiliary effect is an alkylalkanediol and a glycol ether compound, even if water volatilizes, precipitation, solidification, and flow of solid matter It is presumed that the ink discharge stability is not likely to occur, that is, the ink ejection stability is maintained.

Here, the difference in the action of water-soluble organic substances having water and hydroxyl groups between cellulose molecules will be described with reference to FIG.
FIG. 6A is a schematic diagram of an elementary fibril. Plant fibers have a filamentous structure called fibrils, fibrils are further composed of microfibrils having a diameter of several nm to 20 nm and lengths of 1 μm to several μm, and microfibrils are further composed of several to several tens of elementary fibrils.
FIG. 6B is a schematic view showing hydrogen bonds generated between two cellulose molecules. Elementary fibrils consist of dozens of cellulose molecules arranged in parallel. At this time, a strong hydrogen bond is formed between adjacent cellulose molecules, and a bundle having a diameter of about 3 to 4 nm is formed.
FIG.6 (c) is a schematic diagram which shows a hydrogen bond when a water molecule exists between two cellulose molecules. The dotted line represents a hydrogen bond.

FIG. 6B shows a normal hydrogen bond state between cellulose molecules, and FIG. 6C shows a state when water molecules are interposed in hydrogen bonds between cellulose molecules.
To further explain this phenomenon, when water infiltrates into paper and the bond between celluloses is cut as shown in FIG. 6C, the fibers loosen and extend (back curl phenomenon).
Here, when water disappears from the site by drying and movement, the fibers shrink and the broken hydrogen bonds recombine.
However, the pressure applied to the paper during papermaking is naturally not applied, and in this drying process the fibers are hydrogen bonded in a free and loose position, resulting in a different paper shape, i.e. face curl. (Face curl is a phenomenon in which paper is warped on the water-based ink print surface side.)

As described above, the amide compounds of the general formulas (I) and (I) and the compound represented by the general formula (II) have a hydrophilic group-hydrophobic group balance that is rich in hydrophobic groups, Since the ratio of hydroxyl groups, which are hydrophilic groups capable of hydrogen bonding, is small, it is estimated that hydrogen bonds between cellulose molecules are difficult to break even if they penetrate between cellulose molecules.
In addition, the amide compound of formula (I) has a boiling point as high as 216 ° C., a temperature of 23 ° C., a relative humidity of 80%, an equilibrium water content as high as 39.2% by weight, and a liquid viscosity of 25 ° C. It is very low at 1.48 mPa · s in the environment. Furthermore, since the amide compound of the general formula (I), the compound represented by the general formula (II), and other water-soluble organic solvents and water are very easily dissolved, the viscosity of the ink can be reduced. As the water-soluble organic solvent used in the above, it is very preferable. The ink containing the amide compound of the above formula (I) has a high equilibrium water content and can reduce the viscosity of the ink, so that the storage stability and the ejection stability are good and the ink ejection apparatus is maintained. The ink becomes gentle to the device.

The content of the amide compound of the formula (I) in the ink is preferably 1 to 50% by mass, and more preferably 2 to 40% by mass. When the content is less than 1% by mass, there is no effect in reducing the viscosity of the ink and the ejection stability is lowered. On the other hand, if it exceeds 50% by mass, the drying property on paper is inferior and the character quality on plain paper may be lowered.
1-50 mass% is preferable and, as for content of the amide compound of the said general formula (I) in an ink, 2-40 mass% is more preferable. When the content is less than 1% by mass, no curling suppression effect is obtained, no image quality improvement effect is seen, and further, the drying property improvement effect for general-purpose printing paper is lost. On the other hand, if it exceeds 50% by mass, the ink viscosity increases and the ejection stability becomes poor.

Moreover, 1-30 mass% is preferable and, as for content of the compound shown by the said general formula (II) in ink, 2-20 mass% is more preferable. When the content is less than 1% by mass, no curling suppressing effect is obtained, no image quality improving effect is seen, and further, no drying effect improving effect for general-purpose printing paper is lost. On the other hand, if it exceeds 30% by mass, the ink viscosity increases and the ejection stability becomes poor.
Examples of the compound represented by the general formula (II) include 1-n-octyl-2-pyrrolidone, 1-n-dodecyl-2-pyrrolidone, 1-cyclohexyl-2-pyrrolidone and the like.

Furthermore, as a water-soluble organic solvent that shows the curl-suppressing effect as a supplement, there is an alkylalkanediol, in which an alkanediol having 3 to 6 carbon atoms is a main chain and an alkyl having 1 to 2 carbon atoms is a branched chain. If present, the balance between the hydrophilic group and the hydrophobic group becomes water-soluble and becomes rich in the hydrophobic group, and the above-mentioned “low attack against hydrogen bond between cellulose molecules” and “coverability of hydrogen bond between cellulose molecules” models are more It expresses well.
Among these, 2-methyl-1,3-propanediol (bp 214 ° C.), 3-methyl-1,3-butanediol (bp 203 ° C.), 3-methyl-1,5-pentanediol (bp 250 ° C.), 2-ethyl-1,3-hexanediol (bp 243.2 ° C.).
The content of the alkylalkanediol in the ink is preferably 2 to 40% by mass, and more preferably 5 to 30% by mass. If the content is less than 2% by mass, no curl suppressing effect is obtained and no image quality improving effect is seen, and further, the drying improvement effect for general-purpose printing paper is lost. On the other hand, if it exceeds 40% by mass, the ink viscosity increases and the ejection stability becomes poor.

Further, in the ink of the present invention, at least a polyhydric alcohol having an equilibrium water content of 30% by weight or more in an environment of 23 ° C. and 80% relative humidity is used as a water-soluble organic solvent for ensuring moisture retention and drying. One type is included.
The above-mentioned equilibrium water content was determined by using a saturated aqueous solution of potassium chloride / sodium chloride, keeping the temperature and humidity in the desiccator at 23 ± 1 ° C. and relative humidity of 80 ± 3%, and weighing 1 g of each water-soluble organic solvent in the desiccator. The petri dish was stored and the amount of water to be equilibrated was determined by the following formula.
Equilibrium water content = (water content absorbed by organic solvent / organic solvent + water content absorbed by organic solvent)
× 100 (%)

Examples of the polyhydric alcohol include 1,2,3-butanetriol (bp175 ° C./33 hPa, 38 wt%), 1,2,4-butanetriol (bp190-191 ° C./24 hPa, 41 wt%), glycerin (Bp 290 ° C., 49 wt%), diglycerin (bp 270 ° C./20 hPa, 38 wt%), triethylene glycol (bp 285 ° C., 39 wt%), tetraethylene glycol (bp 324-330 ° C., 37 wt%), diethylene glycol ( bp 245 ° C., 43% by weight), 1,3-butanediol (bp 203-204 ° C., 35% by weight) and the like.
Particularly preferred are glycerin and 1,3-butanediol.

The content of the polyhydric alcohol in the ink is preferably 5 to 50% by mass, and more preferably 10 to 40% by mass. If the content is less than 5% by mass, the moisture retention cannot be ensured and the discharge stability may deteriorate. On the other hand, if it exceeds 50% by mass, the drying property on the paper surface is inferior, and the character quality on plain paper may be lowered.
The mass ratio between the polyhydric alcohol and the colorant has a great influence on the stability of ink ejection from the head, and also has an effect on the prevention of sticking of waste ink in the maintenance device of the ink ejection apparatus.
If the blending ratio of the solid content of the colorant is high but the blending amount of the polyhydric alcohol is small, the evaporation of water near the ink meniscus of the nozzle may progress and cause discharge failure.

  The total amount of the amide compound of the general formula (I) and the formula (I), the compound represented by the general formula (II), the alkylalkanediol, and the polyhydric alcohol in the ink is preferably 20 to 80% by mass, 25-70 mass% is more preferable. When the total amount is less than 20% by mass, the curl suppressing effect is not observed, and the discharge stability is lowered and the waste ink is firmly fixed by the maintenance device. On the other hand, if it exceeds 80% by mass, the viscosity of the ink becomes very high and it may be difficult to eject the ink with the ink ejection device. In addition, the drying property on paper is inferior, and the character quality on plain paper may be lowered.

-Colorant-
The following first to third modes are particularly preferable when the colorant is a pigment.
(1) In the first embodiment, the colorant has at least one hydrophilic group on the surface and exhibits water dispersibility in the absence of a dispersant (hereinafter, sometimes referred to as “self-dispersible pigment”). ).

上記式中、Ｒ３は炭素数６〜３０、好ましくは１２〜２４、更に好ましくは１８〜２２のアルキル基を表し、ｎは２０〜１００の整数を表す。 (2) In the second embodiment, the colorant is a pigment dispersion containing a pigment, a pigment dispersant and a polymer dispersion stabilizer, and the polymer dispersion stabilizer is represented by the following general formula (III): Α-olefin-maleic anhydride copolymer, styrene- (meth) acrylic acid copolymer, water-soluble polyurethane resin and water-soluble polyester resin.

In the above formula, R 3 represents an alkyl group having 6 to 30 carbon atoms, preferably 12 to 24 carbon atoms, more preferably 18 to 22 carbon atoms, and n represents an integer of 20 to 100 carbon atoms.

(3) In the third embodiment, the colorant contains a polymer emulsion (an aqueous dispersion of polymer fine particles containing a colorant) in which a polymer fine particle contains a water-insoluble or poorly water-soluble colorant.

As the pigment, an organic pigment or an inorganic pigment can be used. In addition, although you may use together dye for the purpose of color tone adjustment, it is necessary to use within the range which does not deteriorate a weather resistance.
Examples of the inorganic pigment include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, and carbon black. Among these, carbon black is particularly preferable. In addition, as said carbon black, what was manufactured by well-known methods, such as a contact method, a furnace method, and a thermal method, is mentioned, for example.
Examples of the organic pigment include azo pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, and aniline black. Among these, azo pigments and polycyclic pigments are more preferable. Examples of the azo pigment include azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments. Examples of the polycyclic pigment include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinofullerone pigments. Examples of the dye chelates include basic dye chelates and acidic dye chelates.

There is no restriction | limiting in particular in the color of a coloring agent, According to the objective, it can select suitably, For example, the thing for black, the thing for color, etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together.
Examples of the black color include carbon blacks (CI pigment black 7) such as furnace black, lamp black, acetylene black and channel black, and metals such as copper and iron (CI pigment black 11). And metal oxides such as titanium oxide, organic pigments such as aniline black (CI Pigment Black 1), and the like.

  Examples of the color are C.I. I. Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104 , 108, 109, 110, 117, 120, 128, 138, 150, 151, 153, 183, C.I. I. Pigment orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48: 2, 48: 2 [Permanent Red 2B (Ca)], 48: 3, 48: 4, 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmine 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81, 83, 88, 101 (Bengara), 104, 105, 106, 108 ( Cadmium red), 112, 114, 122 (quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, 219, C.I. I. Pigment violet 1 (rhodamine lake), 3, 5: 1, 16, 19, 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue), 15: 1, 15: 2, 15: 3 (phthalocyanine blue), 16, 17: 1, 56, 60, 63; I. Pigment green 1, 4, 7, 8, 10, 17, 18, 36, and the like.

The self-dispersing pigment of the first form is surface-modified so that at least one hydrophilic group is bonded to the surface of the pigment directly or through another atomic group. The surface modification is performed by chemically bonding a specific functional group (a functional group such as a sulfone group or a carboxyl group) to the surface of the pigment, or by using at least one of hypohalous acid and a salt thereof. It is performed by a method such as oxidation treatment. Among these, a form in which a carboxyl group is bonded to the surface of the pigment and dispersed in water is particularly preferable. When the pigment is thus surface-modified and the carboxyl group is bonded, the dispersion stability is improved, high-quality printing quality is obtained, and the water resistance of the recording medium after printing is further improved.
In addition, since the ink containing the self-dispersing pigment of the first form is excellent in redispersibility after drying, printing is suspended for a long period of time, and clogging does not occur even when ink moisture near the inkjet head nozzle evaporates. Good printing can be easily performed with a simple cleaning operation.
The volume average particle diameter (D50) in the ink of the self-dispersing pigment is preferably 0.01 to 0.16 μm.

As the self-dispersing carbon black, those having ionic properties are preferable, and those having an anionic charge or those charged in a cationic manner are suitable.
Examples of the anionic hydrophilic group, for _{example, -COOM, -SO 3 M, -PO} 3 HM, -PO 3 M 2, -SO 2 NH 2, -SO 2 NHCOR ( although, M is a hydrogen atom, an alkali metal, R represents an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent. Among these, it is preferable to use those in which —COOM and —SO ₃ M are bonded to the surface of the color pigment.
Further, “M” in the hydrophilic group includes lithium, sodium, and potassium as alkali metals. Examples of the organic ammonium include mono to trimethyl ammonium, mono to triethyl ammonium, and mono to trimethanol ammonium.
Examples of a method for obtaining an anionically charged color pigment include, for example, a method in which a color pigment is oxidized with sodium hypochlorite and -COONa is introduced to the surface of the color pigment, a method by sulfonation, and a diazonium salt is reacted. A method is mentioned.

As the cationic hydrophilic group, for example, a quaternary ammonium group is preferable, and a quaternary ammonium group as shown in the following [Chemical Formula 5] is more preferable. In the present invention, any of these is bonded to the carbon black surface. Suitable pigments are preferred.

There is no restriction | limiting in particular as a method of manufacturing the cationic self-dispersion type carbon black which the said hydrophilic group couple | bonded, According to the objective, it can select suitably, For example, N-ethyl shown by following formula [Chemical formula 6] An example of a method for bonding a pyridyl group is a method of treating carbon black with 3-amino-N-ethylpyridinium bromide.

The hydrophilic group may be bonded to the surface of carbon black via another atomic group. Examples of other atomic groups include an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent.
Specific examples of the case where the above hydrophilic group is bonded to the surface of carbon black via another atomic group include, for example, —C ₂ H ₄ COOM (where M represents an alkali metal or quaternary ammonium). ), - PhSO ₃ M (however, Ph is a phenyl group .M represents an alkali metal or quaternary _{ammonium), - C 5 H 10 NH} 3 + , and the like.

In the second embodiment, the colorant is a pigment dispersion containing a pigment such as an inorganic pigment, an organic pigment, or a composite pigment, a pigment dispersant, and a polymer dispersion stabilizer. The agent is at least one selected from an α-olefin-maleic anhydride copolymer represented by the general formula (III), a styrene- (meth) acrylic acid copolymer, a water-soluble polyurethane resin, and a water-soluble polyester resin. It is a seed.
The copolymer represented by the general formula (III) can also be synthesized using a mixture of olefins having different carbon numbers as a raw material. In this case, R3 is a copolymer in which alkyl groups having different carbon numbers are randomly introduced into the polymer chain. In the present invention, it is possible to use not only a copolymer having a uniform carbon number of R3 but also a copolymer in which alkyl groups having different carbon numbers as described above are randomly introduced into a polymer chain.

The polymer dispersion stabilizer is an effective material for keeping the dispersion state of the pigment dispersion uniformly finely dispersed in water with the pigment dispersant stable. The molecular weight (weight average molecular weight) is preferably 5,000 to 20,000. The copolymer represented by the general formula (III), the styrene- (meth) acrylic acid copolymer, the water-soluble polyurethane resin and the water-soluble polyester resin are solid at room temperature and hardly soluble in cold water. However, an effect as a dispersion stabilizer when used in an alkali solution or an aqueous alkali solution equal to or more than the acid value of the copolymer and resin (preferably 1.0 to 1.5 times the acid value). Is expressed.
Moreover, in order to melt | dissolve the said copolymer and resin with an alkali solution or aqueous alkali solution, it can melt | dissolve easily, when heated and stirred. However, when the olefin chain in the copolymer represented by the general formula (III) is long, it is relatively difficult to dissolve and insoluble matter may remain. However, if the insoluble matter is removed with an appropriate filter, the dispersion stability The effect as an agent is not impaired.
Examples of the base used in the alkali solution or the aqueous alkali solution include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide; basic substances such as ammonia, triethylamine and morpholine; triethanolamine and diethanolamine. N-methyldiethanolamine, 2-amino-2-ethyl-1,3-propanediol, alcohol amines such as choline, and the like.

As the copolymer represented by the general formula (III), an appropriately synthesized product or a commercially available product may be used. Examples of the commercially available products include T-YP112, T-YP115, T-YP114, T-YP116 (all manufactured by Seiko PMC).
As said styrene- (meth) acrylic acid copolymer, what was synthesize | combined suitably may be used and a commercial item may be used. Examples of the commercially available products include JC-05 (manufactured by Seiko PMC), ARUFON UC-3900, ARUFON UC-3910, ARUFON UC-3920 (manufactured by Toagosei).
As said water-soluble polyurethane resin, what was synthesize | combined suitably may be used and a commercial item may be used. As this commercial item, Takerak W-5025, Takerak W-6010, Takerak W-5661 (made by Mitsui Takeda Chemical Co., Ltd.) etc. are mentioned, for example.
As said water-soluble polyester resin, what was synthesize | combined suitably may be used and a commercial item may be used. Examples of the commercially available products include Nichigo Polyester W-0030, Nichigo Polyester W-0005S30WO, Nichigo Polyester WR-961 (manufactured by Nippon Synthetic Chemical Industry), Pesresin A-210, Pesresin A-520 (Takamatsu Yushi Co., Ltd.) Manufactured).

The acid value of the polymer dispersion stabilizer is preferably 40 to 400 mgKOH / g, more preferably 60 to 350 mgKOH / g. If the acid value is less than 40 mgKOH / g, the solubility of the alkaline solution may be inferior, and if it exceeds 400 mgKOH / g, the viscosity of the pigment increases and the discharge tends to deteriorate, and the dispersion stability of the pigment dispersion decreases. May be easier to do.
The weight average molecular weight of the polymer dispersion stabilizer is preferably 20,000 or less, and more preferably 5,000 to 20,000. When the weight average molecular weight is less than 5,000, the dispersion stability of the pigment dispersion may be lowered, and when it exceeds 20,000, the solubility of the alkali solution may be inferior or the viscosity may be increased.
The content of the polymer dispersion stabilizer is preferably 1 to 100 parts by mass (solid content conversion) and more preferably 5 to 50 parts by mass with respect to 100 parts by mass of the pigment. When the content is less than 1 part by mass, the effect of stabilizing the dispersion may be lost. When the content exceeds 100 parts by mass, the ink viscosity becomes high, and the dischargeability from the nozzle tends to be deteriorated, or the economy is inferior. There is.

<Pigment dispersant>
In the second embodiment, the colorant preferably contains a pigment dispersant. As the pigment dispersant, either an anionic surfactant or a nonionic surfactant having an HLB value of 10 to 20 is suitable.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetates, alkylbenzene sulfonates (for example, NH ₄ , Na, Ca salts, etc.), alkyl diphenyl ether disulfonates (for example, NH ₄ , Na, Ca salts, etc.) ), Dialkyl succinate sulfonic acid Na salt, naphthalene sulfonic acid formalin condensate Na salt, polyoxyethylene polycyclic phenyl ether sulfate ester salt (for example, NH ₄ , Na salt etc.), laurate, polyoxyethylene alkyl ether sulfate salt Oleate and the like. Among these, dioctyl sulfosuccinic acid Na salt and polyoxyethylene styrene phenyl ether sulfonic acid NH ₄ salt are particularly preferable.

Examples of the nonionic surfactant having an HLB value of 10 to 20 include polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, polyoxyethylene polycyclic phenyl ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene Examples include ethylene alkyl phenyl ether, polyoxyethylene alkyl amine, polyoxyethylene alkyl amide, and acetylene glycol.
Among these, polyoxyethylene lauryl ether, polyoxyethylene-β-naphthyl ether, polyoxyethylene sorbitan monooleate, and polyoxyethylene styrene phenyl ether are particularly preferable.

1-100 mass parts is preferable with respect to 100 mass parts of pigments, and, as for content of the said pigment dispersant, 10-50 mass parts is more preferable. If the content of the pigment dispersant is small, the pigment cannot be sufficiently miniaturized. If the content is too large, excess components that are not adsorbed on the pigment affect the ink physical properties. It will cause deterioration of the sex.
The volume average particle diameter (D50) of the pigment dispersion is preferably 150 nm or less, more preferably 100 nm or less in the ink. When the volume average particle diameter (D50) exceeds 150 nm, the ejection stability rapidly decreases, and nozzle clogging and ink bending are likely to occur. Further, when the volume average particle diameter (D50) is 100 nm or less, the ejection stability is improved and the chroma of the image is also improved.

  A pigment dispersion uniformly finely dispersed in water with a pigment dispersant is prepared by dissolving the pigment dispersant in an aqueous medium, then adding the pigment and thoroughly moistening, and then stirring at high speed with a homogenizer, a bead mill, It can be produced by a method using a disperser using balls such as a ball mill, a kneading disperser using shearing force such as a roll mill, an ultrasonic disperser and the like. However, after such a kneading and dispersing step, coarse particles are often contained, which may cause clogging of the ink jet nozzle and the supply path. Therefore, particles having a particle diameter of 1 μm or more using a filter or a centrifuge. Need to be removed.

  Further, as the water-dispersible colorant of the third form, it is preferable to use a polymer emulsion in which a pigment is contained in polymer fine particles in addition to the pigment. The polymer emulsion in which the pigment is contained in the polymer fine particles is one in which the pigment is encapsulated in the polymer fine particles, or the pigment is adsorbed on the surface of the polymer fine particles. In this case, it is not necessary that all the pigments are encapsulated or adsorbed, and the pigments may be dispersed in the emulsion as long as the effects of the present invention are not impaired. Examples of the polymer forming the polymer emulsion (polymer in the polymer fine particles) include vinyl polymers, polyester polymers, polyurethane polymers, and the like. Particularly preferably used polymers are vinyl polymers and polyester polymers. Polymers disclosed in 2000-53897 and JP 2001-139849 can be used.

  In the third embodiment, a general organic pigment or a composite pigment obtained by coating inorganic pigment particles with an organic pigment or carbon black can be suitably used. The composite pigment can be produced by a method of depositing an organic pigment in the presence of inorganic pigment particles, a mechanochemical method of mechanically mixing and grinding an inorganic pigment and an organic pigment, or the like. Further, if necessary, an adhesive layer between the inorganic pigment and the organic pigment can be improved by providing a layer of an organosilane compound formed from polysiloxane and alkylsilane between the inorganic pigment and the organic pigment.

  Examples of the organic pigment include aniline black as a black pigment, and examples of color pigments include anthraquinone, phthalocyanine blue, phthalocyanine green, diazo, monoazo, pyranthrone, perylene, heterocyclic yellow, quinacridone, and (thio) indigoid. . Among these, carbon black, phthalocyanine pigments, quinacridone pigments, monoazo yellow pigments, disazo yellow pigments, and heterocyclic yellow pigments are particularly excellent in terms of color development.

Representative examples of the phthalocyanine blue include copper phthalocyanine blue or a derivative thereof (CI pigment blue 15: 3, 15: 4), aluminum phthalocyanine, and the like.
Examples of the quinacridone include C.I. I. Pigment orange 48, C.I. I. Pigment orange 49, C.I. I. Pigment red 122, C.I. I. Pigment red 192, C.I. I. Pigment red 202, C.I. I. Pigment red 206, C.I. I. Pigment red 207, C.I. I. Pigment red 209, C.I. I. Pigment violet 19, C.I. I. Pigment violet 42 and the like.
Representative examples of the monoazo yellow include C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 109, C.I. I. Pigment yellow 128, C.I. I. And CI Pigment Yellow 151.
Representative examples of the disazo yellow include C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 16, C.I. I. Pigment yellow 17 and the like.
Representative examples of the heterocyclic yellow include C.I. I. Pigment yellow 117, C.I. I. Pigment yellow 138, and the like.
Other suitable colored pigments are described in The Color Index, 3rd edition (The Society of Dyer's and Colorists, 1982).

Examples of the inorganic pigment include titanium dioxide, silica, alumina, iron oxide, iron hydroxide, and tin oxide. The particle shape preferably has a small aspect ratio, and is most preferably spherical. The color of the inorganic pigment is preferably transparent or white when the color material is adsorbed on the surface. However, when the black color material is adsorbed on the surface, a black inorganic pigment is used. It doesn't matter. The primary particle diameter of the inorganic pigment particles is preferably 100 nm or less, and more preferably 5 to 50 nm.
The mass ratio between the inorganic pigment particles and the organic pigment or carbon black as a colorant is preferably 3: 1 to 1: 3, and more preferably 3: 2 to 1: 2. If there are few color materials, color developability and coloring power may fall, and if there are many color materials, transparency and a color tone may worsen.
Color material particles obtained by coating such inorganic pigment particles with an organic pigment or carbon black include silica / carbon black composite material, silica / phthalocyanine PB15: 3 composite material, silica / disazo yellow composite material, silica, manufactured by Toda Kogyo Co., Ltd. / Quinacridone PR122 composite material and the like have a small primary average particle size and can be suitably used.

Here, when inorganic pigment particles having a primary particle size of 20 nm are coated with an equal amount of organic pigment, the primary particle size of this pigment is about 25 nm. If a primary dispersant can be dispersed using a suitable dispersant for this, a very fine pigment-dispersed ink having a dispersed particle diameter of 25 nm can be produced. In the composite pigment, not only the organic pigment on the surface contributes to the dispersion, but also the properties of the inorganic pigment at the center appear through a thin layer of organic pigment with a thickness of about 2.5 nm, so that both can be dispersed and stabilized simultaneously. The selection of the pigment dispersant is also important.
The content of the colorant in the ink is preferably 2 to 15% by mass and more preferably 3 to 12% by mass in terms of solid content. If the content is less than 2% by mass, the color developability and image density of the ink may be lowered. If the content exceeds 15% by mass, the ink may be thickened and the dischargeability may be deteriorated. It is not economically preferable.

-Surfactant-
As the surfactant, those which do not impair the dispersion stability depending on the type of the colorant or the combination of the wetting agent, have a low static surface tension, and have a high permeability and leveling property. At least one selected from an activator, a silicone-based surfactant and a fluorosurfactant is preferred. Among these, silicone surfactants and fluorine surfactants are particularly preferable.
These surfactants may be used alone or in combination of two or more.

上記式中、ｍは０〜１０の整数、ｎは１〜４０の整数を表す。 As the fluorine-based surfactant, those having 2 to 16 carbon atoms substituted with fluorine are preferable, and those having 4 to 16 carbon atoms substituted with fluorine are more preferable. If the number of fluorine-substituted carbons is less than 2, the effect of fluorine may not be obtained, and if it exceeds 16, problems such as ink storage stability may occur.
Examples of the fluorosurfactants include perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate compounds, perfluoroalkyl ethylene oxide adducts, and perfluoroalkyl ether groups. And polyoxyalkylene ether polymer compound. Among these, a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain is particularly preferable because of its low foaming property.
More preferred is a fluorosurfactant represented by the following general formula (IV).

In said formula, m represents the integer of 0-10, n represents the integer of 1-40.

Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid, perfluoroalkyl sulfonate, and the like.
Examples of the perfluoroalkyl carboxylic acid compound include perfluoroalkyl carboxylic acid and perfluoroalkyl carboxylate.
Examples of the perfluoroalkyl phosphate compound include perfluoroalkyl phosphate esters, perfluoroalkyl phosphate salts, and the like.
The polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain includes a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain, and a polyoxyalkylene ether having a perfluoroalkyl ether group in the side chain. Examples thereof include a sulfate salt of a polymer and a salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain.
As counter ions of salts in these fluorosurfactants, Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ , NH (CH ₂ CH ₂ OH) ₃ etc. are mentioned.

As said fluorosurfactant, what was synthesize | combined suitably may be used and a commercial item may be used.
Examples of the commercially available products include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by Asahi Glass Co., Ltd.); Fullrad FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M Limited); Megafac F-470, F -1405, F-474 (all manufactured by Dainippon Ink & Chemicals, Inc.); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR (all FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW (all ), Polyfox PF-151N (Omnova), etc. Among them, FS manufactured by DuPont, from which the good print quality, particularly the color development and the leveling property on paper are remarkably improved. -300, FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW made by Neos Co., Ltd. and Polyfox PF-151N made by Omninova are particularly preferred.

上記式中、Ｒｆは、下記構造式で表わされるフッ素含有疎水基の混合物を表わす。Ａは−ＳＯ_３Ｘ、−ＣＯＯＸ、又は−ＰＯ_３Ｘ〔但し、Ｘは対アニオンであり、具体的には、Ｈ、Ｌｉ、Ｎａ、Ｋ、ＮＨ_４、ＮＨ_３ＣＨ_２ＣＨ_２ＯＨ、ＮＨ_２（ＣＨ_２ＣＨ_２ＯＨ）_２、又はＮＨ（ＣＨ_２ＣＨ_２ＯＨ）_３が挙げられる〕を表わす。 As specific examples of the fluorosurfactant, compounds represented by the following general formulas (V) to (XIV) are preferably used.
(1) Anionic fluorosurfactant

In the above formula, Rf represents a mixture of fluorine-containing hydrophobic groups represented by the following structural formula. A is —SO ₃ X, —COOX, or —PO ₃ X (where X is a counter anion, specifically, H, Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ or NH (CH ₂ CH ₂ OH) ₃ .

上記式中、Ｒｆ′は下記構造式で表わされるフッ素含有基を表わす。Ｘは、前記一般式（Ｖ）のＸと同じ意味を表わす。ｎは１又は２の整数、ｍは２−ｎを表わす。

In the above formula, Rf ′ represents a fluorine-containing group represented by the following structural formula. X represents the same meaning as X in the general formula (V). n represents an integer of 1 or 2, and m represents 2-n.

上記式中、ｎは３〜１０の整数を表わす。

In the above formula, n represents an integer of 3 to 10.

上記式中、Ｒｆ′は、前記一般式（VI）のＲｆ′と、Ｘは、前記一般式（Ｖ）のＸと同じ意味を表わす。

In the above formula, Rf ′ represents the same meaning as Rf ′ in the general formula (VI), and X represents the same meaning as X in the general formula (V).

上記式中、Ｒｆ′は、前記一般式（VI）のＲｆ′と、Ｘは、前記一般式（Ｖ）のＸと同じ意味を表わす。

In the above formula, Rf ′ represents the same meaning as Rf ′ in the general formula (VI), and X represents the same meaning as X in the general formula (V).

上記式中、Ｒｆは、前記一般式（Ｖ）のＲｆと同じ意味を表わす。ｎは５〜２０の整数を表わす。 (2) Nonionic fluorosurfactant

In the above formula, Rf represents the same meaning as Rf in the general formula (V). n represents an integer of 5 to 20.

上記式中、Ｒｆ′は、前記一般式（VI）のＲｆ′と同じ意味を表す。ｎは１〜４０の整数を表す。

In the above formula, Rf ′ represents the same meaning as Rf ′ in the general formula (VI). n represents an integer of 1 to 40.

上記式中、Ｒｆは、前記一般式（Ｖ）のＲｆと同じ意味を表わす。 (3) Amphoteric fluorosurfactant

In the above formula, Rf represents the same meaning as Rf in the general formula (V).

上記式中、Ｒｆ″は、下記構造式で表わされるフッ素含有基を表わす。ｎは０〜１０の整数を表わす。Ｘは、前記一般式（Ｖ）のＸと同じ意味を表わす。 (4) Oligomer type fluorosurfactant

In the above formula, Rf ″ represents a fluorine-containing group represented by the following structural formula. N represents an integer of 0 to 10. X represents the same meaning as X in the general formula (V).

上記式中、ｎは１〜４の整数を表わす。

In the above formula, n represents an integer of 1 to 4.

上記式中、Ｒｆ″は、前記一般式（XII）のＲｆ″と同じ意味を表わす。ｌは０〜１０の整数、ｍは０〜１０の整数、ｎは０〜１０の整数を表わす。

In the above formula, Rf ″ represents the same meaning as Rf ″ in the general formula (XII). l represents an integer of 0 to 10, m represents an integer of 0 to 10, and n represents an integer of 0 to 10.

The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably one that does not decompose even at a high pH. Examples thereof include one-end-modified polydimethylsiloxane, side-chain both-end-modified polydimethylsiloxane, and the like. Is particularly preferable since it exhibits good properties.
As such a surfactant, an appropriately synthesized product or a commercially available product may be used. Commercially available products can be easily obtained from, for example, Big Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Toray Dow Corning Silicone Co., Ltd., Nippon Emulsion Co., Ltd., Kyoeisha Chemical Co., Ltd.

上記式中、ｍ、ｎ、ａ、及びｂは整数を表わす。Ｒ及びＲ′はアルキル基、アルキレン基を表わす。 The polyether-modified silicone surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the polyalkylene oxide structure represented by the following general formula (XIV) is represented by the Si part of dimethylpolysiloxane. And compounds introduced into the side chain.

In the above formula, m, n, a, and b represent integers. R and R ′ represent an alkyl group or an alkylene group.

A commercial item can be used as said polyether modified silicone type surfactant, For example, KF-618, KF-642, KF-643 (Shin-Etsu Chemical Co., Ltd.) etc. are mentioned.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, laurate, polyoxyethylene alkyl ether sulfate salt, and the like.
Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxypropylene polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, and polyoxyethylene alkyl. And amines and polyoxyethylene alkylamides.

  The content of these surfactants in the ink is preferably 0.01 to 3.0% by mass, and more preferably 0.5 to 2% by mass. If the content is less than 0.01% by mass, the effect of adding the surfactant may be lost. If the content exceeds 3.0% by mass, the permeability to the recording medium becomes unnecessarily high, and the image density decreases. There may be a show-through.

―Penetration agent―
The ink preferably contains at least one polyol compound or glycol ether compound having 8 to 11 carbon atoms as a penetrant. These preferably have a solubility of between 0.2 and 5.0% by weight in water at 25 ° C., in particular 2-ethyl-1,3-hexanediol [solubility: 4.2% (25 ° C.) ], 2,2,4-trimethyl-1,3-pentanediol [solubility: 2.0% (25 ° C.)].

Examples of other polyol compounds include 2-ethyl-2-methyl-1,3-propanediol, 3,3-dimethyl-1,2-butanediol, 2,2-diethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2,4-dimethyl-2,4-pentanediol, 2,5-dimethyl-2,5-hexanediol, 5-hexene-1,2-diol And aliphatic diols such as
Other penetrants that can be used in combination are not particularly limited as long as they can be dissolved in the ink and adjusted to the desired physical properties, and can be appropriately selected according to the purpose. For example, diethylene glycol monophenyl ether, ethylene Glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, alkyl and aryl ethers of polyhydric alcohols such as tetraethylene glycol chlorophenyl ether, lower alcohols such as ethanol, etc. Is mentioned.

  The content of the penetrant in the ink is preferably 0.1 to 4.0% by mass. If the content is less than 0.1% by mass, a fast-drying property cannot be obtained and a blurred image may be obtained. If the content exceeds 4.0% by mass, the dispersion stability of the colorant is impaired and the nozzle is clogged. In some cases, the recording medium becomes more permeable and the permeability to the recording medium becomes higher than necessary, resulting in a decrease in image density and through-through.

-Water dispersible resin-
As the water-dispersible resin, those having excellent film-forming properties (image forming properties) and having high water repellency, high water resistance, and high weather resistance have high water resistance and high image density (high color developability). Useful for image recording. Examples thereof include condensation-type synthetic resins, addition-type synthetic resins, natural polymer compounds, and the like.
Examples of the condensed synthetic resin include polyester resin, polyurethane resin, polyepoxy resin, polyamide resin, polyether resin, poly (meth) acrylic resin, acrylic-silicone resin, and fluorine-based resin.
Examples of the addition type synthetic resin include polyolefin resins, polystyrene resins, polyvinyl alcohol resins, polyvinyl ester resins, polyacrylic acid resins, unsaturated carboxylic acid resins, and the like.
Examples of the natural polymer compound include celluloses, rosins, and natural rubber.
Among these, polyurethane resin fine particles, acrylic-silicone resin fine particles, and fluorine-based resin fine particles are particularly preferable.
Moreover, it is not a problem to use two or more kinds of the water-dispersible resins in combination.

As the fluorine resin fine particles, fluorine resin fine particles having a fluoroolefin unit are preferable, and among these, fluorine-containing vinyl ether resin fine particles composed of a fluoroolefin unit and a vinyl ether unit are particularly preferable.
Wherein particularly limited fluoroolefin unit is not, can be appropriately selected depending on the intended purpose, for example, _{-CF 2 CF 2 -, - CF} 2 CF (CF 3) -, - CF 2 CFCl- and the like .
The vinyl ether unit is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include groups shown in Table 1 below.

As the fluorine-containing vinyl ether resin fine particles composed of the fluoroolefin unit and the vinyl ether unit, an alternating copolymer in which the fluoroolefin unit and the vinyl ether unit are alternately copolymerized is preferable.
As such fluorine-based resin fine particles, those appropriately synthesized may be used, or commercially available products may be used. Commercially available products include, for example, Fluonate FEM-500, FEM-600, Dickguard F-52S, F-90, F-90M, F-90N, Aquafranc TE-5A manufactured by Dainippon Ink & Chemicals, Inc .; Asahi Glass Co., Ltd. Examples include Lumiflon FE4300, FE4500, FE4400, Asahi Guard AG-7105, AG-950, AG-7600, AG-7000, AG-1100, and the like.
The water-dispersible resin may be used as a homopolymer, a copolymer, or a composite resin. Moreover, any of a single phase structure type, a core shell type, and a power feed type emulsion can be used.

As the water-dispersible resin, a resin itself having a hydrophilic group and having a self-dispersibility, or a resin itself having no dispersibility and imparted with a surfactant or a resin having a hydrophilic group can be used. . Among these, an emulsion of resin particles obtained by emulsion polymerization or suspension polymerization of an ionomer of a polyester resin or polyurethane resin or an unsaturated monomer is optimal.
In the case of emulsion polymerization of an unsaturated monomer, the resin emulsion is reacted by reacting in water to which an unsaturated monomer, a polymerization initiator, a surfactant, a chain transfer agent, a chelating agent, and a pH adjusting agent are added. Therefore, a water-dispersible resin can be easily obtained, and the resin properties can be easily changed, so that desired properties can be easily produced.

Examples of the unsaturated monomer include unsaturated carboxylic acids, monofunctional or polyfunctional (meth) acrylic acid ester monomers, (meth) acrylic acid amide monomers, and aromatic vinyl monomers. , Vinyl cyano compound monomers, vinyl monomers, allyl compound monomers, olefin monomers, diene monomers, oligomers having unsaturated carbon, etc., alone or in combination Can do. It is possible to modify the properties flexibly by combining these monomers, and it is also possible to modify the properties of the resin by performing a polymerization reaction and a graft reaction using an oligomer type polymerization initiator. .
Examples of the unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid and the like.

  Examples of the monofunctional (meth) acrylic acid ester monomers include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2 -Ethylhexyl methacrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, glycidyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, methacryloxyethyltrimethylammonium Salt, 3-me Acryloxypropyltrimethoxysilane, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl acrylate , Dodecyl acrylate, octadecyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, glycidyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, dimethylaminoethyl acrylate, acryloxyethyl trimethyl ammonium salt, and the like.

  Examples of the polyfunctional (meth) acrylic acid ester monomers include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1, 4-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, polybutylene glycol dimethacrylate, 2,2'-bis (4-methacryloxy) Diethoxyphenyl) propane, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, polyethylene Glycol diacrylate, triethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, 1,9-nonanediol di Acrylate, polypropylene glycol diacrylate, 2,2'-bis (4-acryloxypropyloxyphenyl) propane, 2,2'-bis (4-acryloxydiethoxyphenyl) propane, trimethylolpropane triacrylate, trimethylolethane Triacrylate, tetramethylol methane triacrylate, ditrimethylol tetraacrylate, tetramethylol methane tetraacrylate, pentaerythritol tetraacrylate Dipentaerythritol hexaacrylate, and the like.

Examples of the (meth) acrylic acid amide monomers include acrylamide, methacrylamide, N, N-dimethylacrylamide, methylenebisacrylamide, 2-acrylamido-2-methylpropanesulfonic acid, and the like.
Examples of the aromatic vinyl monomers include styrene, α-methyl styrene, vinyl toluene, 4-t-butyl styrene, chlorostyrene, vinyl anisole, vinyl naphthalene, and divinyl benzene.
Examples of the vinyl cyano compound monomers include acrylonitrile and methacrylonitrile.

Examples of the vinyl monomers include vinyl acetate, vinylidene chloride, vinyl chloride, vinyl ether, vinyl ketone, vinyl pyrrolidone, vinyl sulfonic acid or salts thereof, vinyl trimethoxysilane, vinyl triethoxysilane, and the like.
Examples of the allyl compound monomers include allyl sulfonic acid salt thereof, allylamine, allyl chloride, diallylamine, diallyldimethylammonium salt and the like.
Examples of the olefin monomers include ethylene and propylene.
Examples of the diene monomers include butadiene and chloroprene.
Examples of the oligomers having unsaturated carbon include styrene oligomers having methacryloyl groups, styrene-acrylonitrile oligomers having methacryloyl groups, methyl methacrylate oligomers having methacryloyl groups, dimethylsiloxane oligomers having methacryloyl groups, and polyesters having acryloyl groups. An oligomer etc. are mentioned.

The water-dispersible resin has a strong alkalinity and strong acidity, and thus causes chain breakage such as dispersion breakage and hydrolysis. Therefore, the pH is preferably 4 to 12, and particularly miscible with water-dispersible colorants. Therefore, the pH is more preferably 6 to 11, and further preferably 7 to 9.
The volume average particle diameter (D50) of the water-dispersible resin is related to the viscosity of the dispersion, and for the same composition, the viscosity at the same solid content increases as the particle diameter decreases. The volume average particle diameter (D50) of the water-dispersible resin is preferably 50 nm or more so that the viscosity does not become excessively high when converted into an ink. Further, when the particle size is several tens of μm, it becomes larger than the nozzle opening of the ink jet head and cannot be used. Even if it is smaller than the nozzle opening, if particles having a large particle diameter are present in the ink, the ejection property is deteriorated. Therefore, in order not to inhibit the ink ejection properties, the volume average particle diameter (D50) is more preferably 200 nm or less, and further preferably 150 nm or less.

The water-dispersible resin has a function of fixing the colorant to the paper surface, and is preferably formed into a film at room temperature to improve the fixability of the color material. Therefore, the minimum film-forming temperature (MFT) of the water-dispersible resin is preferably 30 ° C. or lower. Further, when the glass transition temperature of the water-dispersible resin is less than −40 ° C., the viscosity of the resin film becomes strong and the printed matter is tacked. Therefore, the glass transition temperature is preferably −40 ° C. or higher.
The content of the water-dispersible resin in the ink is preferably 2 to 30% by mass and more preferably 5 to 25% by mass in terms of solid content.

  Here, the solid content of the colorant, the pigment in the colorant, and the water-dispersible resin can be measured by, for example, a method of separating only the colorant and the water-dispersible resin from the ink. . Moreover, when the pigment is used as the colorant, the ratio of the colorant to the water-dispersible resin can be measured by evaluating the mass reduction rate by thermal mass spectrometry. In addition, when the molecular structure of the colorant is clear, the solid content of the colorant can be quantified using NMR for pigments and dyes. Inorganic pigments contained in heavy metal atoms, molecular skeletons, and metal-containing organics For pigments and metal-containing dyes, the solid content of the colorant can be quantified by using fluorescent X-ray analysis.

-Other ingredients-
Other components are not particularly limited and can be appropriately selected as necessary. For example, a pH adjuster, antiseptic / antifungal agent, chelating reagent, rust inhibitor, antioxidant, ultraviolet absorber, oxygen absorber, And light stabilizers.

The pH adjuster is not particularly limited as long as it can adjust the pH to 7 to 11 without adversely affecting the ink to be prepared, and can be appropriately selected according to the purpose. And alkali metal element hydroxides, ammonium hydroxides, phosphonium hydroxides, alkali metal carbonates, and the like.
If the pH is less than 7 or more than 11, the amount of the ink jet head or ink supply unit that melts out is large, and problems such as ink deterioration, leakage, and ejection failure may occur.
Examples of the alcohol amines include diethanolamine, triethanolamine, 2-amino-2-ethyl-1,3-propanediol, and the like.
Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide.
Examples of the ammonium hydroxide include ammonium hydroxide and quaternary ammonium hydroxide.
Examples of the phosphonium hydroxide include quaternary phosphonium hydroxide.
Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, and potassium carbonate.

Examples of the antiseptic / antifungal agent include sodium dehydroacetate, sodium sorbate, 2-pyridinethiol-1-oxide sodium, sodium benzoate, sodium pentachlorophenol, and the like.
Examples of the chelating reagent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uramil diacetate, and the like.
Examples of the rust inhibitor include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

Examples of the antioxidant include phenolic antioxidants (including hindered phenolic antioxidants), amine-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like.
Examples of the phenolic antioxidant (including hindered phenolic antioxidant) include butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, stearyl-β- (3,5 -Di-tert-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis (3-methyl-6-tert-butylphenol), 3,9-bis {1,1-dimethyl-2- [β- (3-tert-butyl-4-hydroxy-5-methylphenyl) ) Propionyloxy] ethyl} -2,4,8,10-tetraoxaspiro [5,5] undecane, 1,1,3 Tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl ) Benzene, tetrakis [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane, and the like.

  Examples of the amine-based antioxidant include phenyl-β-naphthylamine, α-naphthylamine, N, N′-di-sec-butyl-p-phenylenediamine, phenothiazine, N, N′-diphenyl-p-phenylenediamine. 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butyl-phenol, butylhydroxyanisole, 2,2'-methylenebis ( 4-methyl-6-tert-butylphenol), 4,4'-butylidenebis (3-methyl-6-tert-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), tetrakis [methylene -3- (3,5-di-tert-butyl-4-dihydroxyphenyl) propi Onate] methane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, and the like.

Examples of the sulfur-based antioxidant include dilauryl-3,3′-thiodipropionate, distearyl thiodipropionate, lauryl stearyl thiodipropionate, dimyristyl-3,3′-thiodipropionate, Examples include stearyl-β, β′-thiodipropionate, 2-mercaptobenzimidazole, dilauryl sulfide, and the like.
Examples of the phosphorus antioxidant include triphenyl phosphite, octadecyl phosphite, triisodecyl phosphite, trilauryl trithiophosphite, trinonylphenyl phosphite, and the like.

Examples of the ultraviolet absorber include a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, a salicylate ultraviolet absorber, a cyanoacrylate ultraviolet absorber, and a nickel complex ultraviolet absorber.
Examples of the benzophenone-based ultraviolet absorber include 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2,4-dihydroxybenzophenone, and 2-hydroxy-4-methoxybenzophenone. 2,2 ', 4,4'-tetrahydroxybenzophenone, and the like.
Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2'-hydroxy-4'-octoxyphenyl) benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, and the like.

Examples of the salicylate-based ultraviolet absorber include phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate, and the like.
Examples of the cyanoacrylate ultraviolet absorber include ethyl-2-cyano-3,3′-diphenyl acrylate, methyl-2-cyano-3-methyl-3- (p-methoxyphenyl) acrylate, and butyl-2- And cyano-3-methyl-3- (p-methoxyphenyl) acrylate.
Examples of the nickel complex ultraviolet absorber include nickel bis (octylphenyl) sulfide, 2,2'-thiobis (4-tert-octylferrate) -n-butylamine nickel (II), 2,2'-thiobis. (4-tert-octyl ferrate) -2-ethylhexylamine nickel (II), 2,2'-thiobis (4-tert-octyl ferrate) triethanolamine nickel (II), and the like.

  The ink of the present invention comprises a colorant, a water-soluble organic solvent (wetting agent), a surfactant and water, and if necessary, other components such as a penetrant and a water-dispersible resin dispersed or dissolved in an aqueous medium. Further, it is produced by stirring and mixing as necessary. This stirring and mixing can be performed by, for example, a sand mill, a homogenizer, a ball mill, a paint shaker, an ultrasonic disperser, and the like. The stirring and mixing is performed by a stirrer using a normal stirring blade, a magnetic stirrer, a high-speed disperser, or the like. be able to.

The physical properties of the ink of the present invention are not particularly limited and may be appropriately selected depending on the intended purpose. For example, the viscosity and static surface tension are preferably in the following ranges.
The viscosity of the ink at 25 ° C. is preferably 5 to 25 mPa · s, more preferably 7.0 to 20 mPa · s. By setting the ink viscosity to 5 mPa · s or more, the effect of improving the printing density and the character quality can be obtained. Moreover, discharge property is securable by restraining to 25 mPa * s or less. The viscosity can be measured at 25 ° C. using, for example, a viscometer (RE-550L, manufactured by Toki Sangyo Co., Ltd.).
The static surface tension of the ink is preferably 35 mN / m or less at 25 ° C., more preferably 32 mN / m or less. When the static surface tension exceeds 35 mN / m, leveling of the ink on the recording medium is difficult to occur, and the drying time may be prolonged (drying property is deteriorated).

  There is no restriction | limiting in particular in the color of an ink, According to the objective, it can select suitably, Yellow, magenta, cyan, black etc. are mentioned. When recording is performed using an ink set in which two or more of these colors are used in combination, a multicolor image can be formed, and when recording is performed using an ink set in which all colors are used in combination, a full color image is formed. be able to.

  In the ink of the present invention, a piezoelectric element is used as a pressure generating means for pressurizing the ink in the ink flow path, and the vibration plate forming the wall surface of the ink flow path is deformed to change the volume in the ink flow path to thereby drop ink droplets. A so-called piezo-type device that discharges (refer to Japanese Patent Laid-Open No. 2-51734) or a so-called thermal-type device that generates bubbles by heating ink in an ink flow path using a heating resistor (Japanese Patent Laid-Open No. Sho 61). No. -59911), the diaphragm and the electrode forming the wall surface of the ink flow path are arranged opposite to each other, and the diaphragm is deformed by an electrostatic force generated between the vibration plate and the electrode, whereby the volume of the ink flow path is increased. It can be satisfactorily used in a printer equipped with any ink jet head such as an electrostatic type (see Japanese Patent Laid-Open No. 6-71882) that discharges ink droplets by changing the above.

The ink of the present invention can be suitably used in an inkjet recording type image forming apparatus (printer or the like). For example, recording paper and ink are heated at 50 to 200 ° C. at the time of printing or before and after printing to promote print fixing. It can also be used for a printer having a function.
Further, it can be suitably used for the following ink media set, ink cartridge, ink jet recording method, ink jet recording apparatus, and ink recorded matter.

(Ink media set)
The ink of the present invention and a recording medium can be combined to form an ink media set.

<Recording medium>
The recording medium is not particularly limited and can be appropriately selected depending on the purpose. For example, plain paper, glossy paper, special paper, cloth, film, OHP sheet, and general-purpose printing paper can be suitably used.
Among these, in order to obtain a very beautiful ink record such as a printed image, the support has a coating layer coated on at least one surface of the support and is dynamic. The transfer amount of pure water to the recording medium at a contact time of 100 ms measured with a scanning absorption meter is ² to 35 mL / m ² , and the transfer amount of pure water to the recording medium at a contact time of 400 ms is 3 to 40 mL. A recording medium of / m ² is used. The amount of pure water transferred to the recording medium at a contact time of 100 ms measured with the dynamic scanning absorption meter is preferably ² to 5 mL / m ^{2, and the} amount of pure water transferred to the recording medium at a contact time of 400 ms is 3 10 mL / m ² is preferred. If the transfer amount of ink and pure water at a contact time of 100 ms is too small, beading (density unevenness) is likely to occur. If it is too large, the ink dot diameter after recording becomes smaller than the desired diameter. It may be too much. Further, if the transfer amount of ink and pure water at a contact time of 400 ms is too small, the drying property is insufficient, and thus spur marks may be easily generated. May become low.

  The dynamic scanning absorptiometer (DSA, Papa, Japan, 48, May 1994, pp. 88-92, Kuju Shigenori) accurately measures the amount of liquid absorption in a very short time. It is a device that can measure. This device (i) reads the liquid absorption speed directly from the movement of the meniscus in the capillary, (ii) scans the liquid absorption head spirally on the sample, and scans according to a preset pattern The measurement is automated by a method in which the speed is automatically changed and the measurement is performed by the number of points required for one sample. A liquid supply head for a paper sample is connected to a capillary via a Teflon (registered trademark) tube, and the position of the meniscus in the capillary is automatically read by an optical sensor. Specifically, the transfer amount of pure water was measured using a dynamic scanning absorption meter (K350 series D type, manufactured by Kyowa Seiko Co., Ltd.). The transfer amount at the contact time of 100 ms and the contact time of 400 ms can be obtained by interpolation from the measured values of the transfer amount at the contact time adjacent to the contact time.

-Support-
There is no restriction | limiting in particular as said support body, According to the objective, it can select suitably, For example, sheet-like substances, such as a nonwoven fabric mainly composed of wood fiber and wood fiber, and synthetic fiber, etc. are mentioned.
There is no restriction | limiting in particular as said paper, According to the objective, it can select suitably according to the objective, For example, a wood pulp, a used paper pulp, etc. are used.
Examples of the wood pulp include hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), NBSP, LBSP, GP, and TMP.

  As the raw material of waste paper pulp, the white paper, ruled white, cream white, card, special white, medium white, imitation, fair white, Kent, white art, as shown in the used paper standard quality standard table of the Waste Paper Recycling Promotion Center , Special upper deadline, separate upper deadline, newspaper, magazine and so on. Specifically, printer paper such as non-coating computer paper, thermal paper, and pressure-sensitive paper as information-related paper; OA waste paper such as PPC paper; coating of art paper, coated paper, finely coated paper, matte paper, etc. Paper: High quality paper, color quality, notebook, notepaper, wrapping paper, fancy paper, medium quality paper, newsprint, reprint paper, super paper, imitation paper, pure white roll paper, uncoated paper such as milk carton, etc. Examples of used paper and paperboard include chemical pulp paper and high-yield pulp-containing paper. These may be used individually by 1 type and may use 2 or more types together.

Waste paper pulp is generally produced by a combination of the following four steps.
(1) In disaggregation, waste paper is treated with a mechanical force and chemicals using a pulper to loosen it into a fiber, and the printing ink is peeled off from the fiber.
(2) Dust removal removes foreign matter (such as plastic) and dust contained in waste paper with a screen, cleaner, or the like.
(3) Deinking removes the printing ink peeled from the fiber by using a surfactant from the system by a flotation method or a cleaning method.
(4) Bleaching increases the whiteness of the fiber using an oxidizing action or a reducing action.
When used paper pulp is mixed, the mixing ratio of the used paper pulp in the total pulp is preferably 40% or less from the viewpoint of curling after recording.

  As the internal filler used for the support, for example, a conventionally known pigment is used as a white pigment. Examples of the white pigment include light calcium carbonate, heavy calcium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, White inorganic pigments such as calcium silicate, magnesium silicate, synthetic silica, aluminum hydroxide, alumina, lithopone, zeolite, magnesium carbonate, magnesium hydroxide; styrene plastic pigment, acrylic plastic pigment, polyethylene, microcapsule, urea resin And organic pigments such as melamine resin. These may be used individually by 1 type and may use 2 or more types together.

Examples of the internally added sizing agent used for making the support include, for example, neutral rosin sizing agents used for neutral papermaking, alkenyl succinic anhydride (ASA), alkyl ketene dimer (AKD), and petroleum resin. System sizing agents and the like. Among these, a neutral rosin sizing agent or alkenyl succinic anhydride is particularly preferable. The above-described alkyl ketene dimer requires a small amount of addition because of its high size effect, but the friction coefficient on the surface of the recording medium is low and slippery, which may be undesirable from the viewpoint of transportability during ink jet recording. .
There is no restriction | limiting in particular in the thickness of the said support body, Although it can select suitably according to the objective, 50-300 micrometers is preferable. The basis weight of the support, 45~290g / ^{m 2} is preferred.

-Coating layer-
The coating layer contains a pigment and a binder (binder), and if necessary, contains a surfactant and other components. As the pigment, an inorganic pigment or a combination of an inorganic pigment and an organic pigment can be used.

Examples of the inorganic pigment include kaolin, talc, heavy calcium carbonate, light calcium carbonate, calcium sulfite, amorphous silica, titanium white, magnesium carbonate, titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, Examples thereof include zinc hydroxide and chlorite. Among these, kaolin is particularly preferable because it has excellent glossiness and can be made close to a paper for offset printing. This kaolin includes delaminated kaolin, calcined kaolin, engineered kaolin by surface modification, etc. In consideration of gloss development, the particle size distribution with a particle size of 2 μm or less is 80% by mass or more. It is preferable that the kaolin which has occupies 50 mass% or more of the whole.
The amount of kaolin added is preferably 50 parts by mass or more with respect to 100 parts by mass of the binder. When the addition amount is less than 50 parts by mass, a sufficient effect may not be obtained in glossiness. There is no particular upper limit to the amount added, but considering the fluidity of kaolin, particularly thickening under high shear force, 90 parts by mass or less is preferable from the viewpoint of coating suitability.

Examples of the organic pigment include water-soluble dispersions such as styrene-acrylic copolymer particles, styrene-butadiene copolymer particles, polystyrene particles, and polyethylene particles. These organic pigments may be used in combination of two or more.
The addition amount of the organic pigment is preferably 2 to 20 parts by mass with respect to 100 parts by mass of the total pigment in the coating layer. Since organic pigments are excellent in glossiness and their specific gravity is smaller than that of inorganic pigments, it is possible to obtain a coating layer that is bulky, high glossy, and has good surface coverage. If the addition amount is less than 2 parts by mass, there is no effect of addition, and if it exceeds 20 parts by mass, the fluidity of the coating liquid deteriorates, leading to a decrease in coating operability, and it is not economical from the viewpoint of cost.
The organic pigment has a solid type, a hollow type, a donut type, and the like as its form. However, in consideration of the balance of gloss development, surface coverage, and fluidity of the coating liquid, the volume average particle size (D50) is 0.2 to 3.0 μm is preferable, and a hollow mold having a porosity of 40% or more is more preferable.

The binder is preferably an aqueous resin. As the aqueous resin, either a water-soluble resin or a water-dispersible resin is suitable.
2-100 mass parts is preferable with respect to 100 mass parts of pigments, and, as for the addition amount of these aqueous resins, 3-50 mass parts is more preferable. The amount of the aqueous resin added is determined so that the liquid absorption characteristics of the recording medium fall within a desired range.

  There is no restriction | limiting in particular as said water-soluble resin, According to the objective, it can select suitably, For example, modified products of polyvinyl alcohol, such as polyvinyl alcohol, anion modified polyvinyl alcohol, cation modified polyvinyl alcohol, acetal modified polyvinyl alcohol; Polyurethane Polyvinylpyrrolidone and polyvinylpyrrolidone and vinyl acetate copolymer, vinylpyrrolidone and dimethylaminoethyl / methacrylic acid copolymer, quaternized vinylpyrrolidone / dimethylaminoethyl / methacrylic acid copolymer, vinylpyrrolidone and methacrylic acid Modified products of polyvinylpyrrolidone such as a copolymer of amidopropyl trimethylammonium chloride; Cellulo such as carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose Modified products of cellulose such as cationized hydroxyethyl cellulose; Synthetic resins such as polyester, polyacrylic acid (ester), melamine resin, or modified products thereof, polyester and polyurethane copolymer; poly (meth) acrylic acid, Examples include poly (meth) acrylamide, oxidized starch, phosphate esterified starch, self-modified starch, cationized starch, or various modified starches, polyethylene oxide, sodium polyacrylate, and sodium alginate. These may be used individually by 1 type and may use 2 or more types together. Among these, polyvinyl alcohol, cation-modified polyvinyl alcohol, acetal-modified polyvinyl alcohol, polyester, polyurethane, a copolymer of polyester and polyurethane, and the like are particularly preferable from the viewpoint of ink absorbability.

  There is no restriction | limiting in particular as said water dispersible resin, According to the objective, it can select suitably, For example, a polyvinyl acetate, ethylene-vinyl acetate copolymer, polystyrene, styrene- (meth) acrylic acid ester copolymer , (Meth) acrylic acid ester polymer, vinyl acetate- (meth) acrylic acid (ester) copolymer, styrene-butadiene copolymer, ethylene-propylene copolymer, polyvinyl ether, silicone-acrylic copolymer , Etc. Further, it may contain a crosslinking agent such as methylolated melamine, methylolated urea, methylolated hydroxypropylene urea, or isocyanate, or may be a copolymer containing units such as N-methylolacrylamide and having a self-crosslinking property. A plurality of these water-based resins can be used simultaneously.

There is no restriction | limiting in particular in the cationic organic compound mix | blended with a coating layer, According to the objective, it can select suitably. Examples include monomers of primary to tertiary amines and quaternary ammonium salts that react with sulfonic acid groups, carboxyl groups, amino groups, etc. in direct dyes and acidic dyes in water-soluble inks to form insoluble salts. , Oligomers, polymers, etc., among these, oligomers or polymers are preferred.
When a water dispersible colorant is used as the colorant, it is not always necessary to add a cationic organic compound to the coating layer.

Examples of the cationic organic compound include dimethylamine / epichlorohydrin polycondensate, dimethylamine / ammonia / epichlorohydrin condensate, poly (trimethylaminoethyl methacrylate / methyl sulfate), diallylamine hydrochloride / acrylamide copolymer, (Diallylamine hydrochloride / sulfur dioxide), polyallylamine hydrochloride, poly (allylamine hydrochloride / diallylamine hydrochloride), acrylamide / diallylamine copolymer, polyvinylamine copolymer, dicyandiamide, dicyandiamide / ammonium chloride / urea / formaldehyde condensate , Polyalkylene polyamine dicyandiamide ammonium salt condensate, dimethyldiallylammonium chloride, polydiallylmethylamine hydrochloride, poly (diallyldimethyl) Ruammonium chloride), poly (diallyldimethylammonium chloride / sulfur dioxide), poly (diallyldimethylammonium chloride / diallylamine hydrochloride derivative), acrylamide / diallyldimethylammonium chloride copolymer, acrylate / acrylamide / diallylamine hydrochloride copolymer Products, ethyleneimine derivatives such as polyethyleneimine and acrylicamine polymer, and polyethyleneimine alkylene oxide modified products. These may be used individually by 1 type and may use 2 or more types together.
Among these, low molecular weight cationic organic compounds such as dimethylamine / epichlorohydrin polycondensate and polyallylamine hydrochloride and other relatively high molecular weight cationic organic compounds such as poly (diallyldimethylammonium chloride) It is preferable to use in combination. The combined use improves the image density and further reduces feathering compared to the single use.

The cation equivalent of a cationic organic compound by colloid titration method (using polyvinyl potassium sulfate and toluidine blue) is preferably 3 to 8 meq / g. If the cation equivalent is within this range, good results can be obtained within the above dry adhesion range. Here, in the measurement of the cation equivalent by the colloid titration method, the cationic organic compound is diluted with distilled water so as to have a solid content of 0.1% by mass, and pH adjustment is not performed.
The dry adhesion amount of the cationic organic compound is preferably 0.3 to 2.0 g / m ² . When the dry adhesion amount is less than 0.3 g / m ² , sufficient image density improvement and feathering reduction effects may not be obtained.

  The surfactant contained in the coating layer as needed is not particularly limited and may be appropriately selected depending on the intended purpose. However, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant Any of these can be used. Among these, nonionic active agents are particularly preferable. By adding these surfactants, the water resistance of the image is improved, the image density is increased, and bleeding is improved.

  Examples of the nonionic activator include higher alcohol ethylene oxide adducts, alkylphenol ethylene oxide adducts, fatty acid ethylene oxide adducts, polyhydric alcohol fatty acid ester ethylene oxide adducts, higher aliphatic amine ethylene oxide adducts, and fatty acid amides. Ethylene oxide adduct, fat ethylene oxide adduct, polypropylene glycol ethylene oxide adduct, fatty acid ester of glycerol, fatty acid ester of pentaerythritol, fatty acid ester of sorbitol and sorbitan, fatty acid ester of sucrose, alkyl ether of polyhydric alcohol, And fatty acid amides of alkanolamines. These may be used individually by 1 type and may use 2 or more types together.

The polyhydric alcohol is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include glycerol, trimethylolpropane, pentaerythritol, sorbitol, and sucrose. Moreover, about the said ethylene oxide adduct, what substituted some alkylene oxides, such as propylene oxide or butylene oxide, in the range which can maintain water solubility is also effective. The substitution rate is preferably 50% or less.
4-15 are preferable and, as for HLB (hydrophilic / lipophilic ratio) of the said nonionic activator, 7-13 are more preferable.
The addition amount of the surfactant is preferably 0 to 10 parts by mass, and more preferably 0.1 to 1.0 part by mass with respect to 100 parts by mass of the cationic organic compound.

  Other components can be added to the coating layer as needed, as long as the object and effect of the present invention are not impaired. Examples of other components include additives such as alumina powder, pH adjuster, preservative, and antioxidant.

There is no restriction | limiting in particular as a formation method of the said coating layer, According to the objective, it can select suitably, It can carry out by the method of impregnating or apply | coating a coating layer liquid on the said support body.
The impregnation or coating method of the coating layer liquid is not particularly limited and can be appropriately selected according to the purpose. For example, conventional size press, gate roll size press, film transfer size press, blade coater, rod coater, air It can also be applied with various coating machines such as knife coaters and curtain coaters, but from the viewpoint of cost, it is impregnated or adhered with a conventional size press, gate roll size press, film transfer size press, etc. installed in the paper machine. You can finish it on-machine.
There is no restriction | limiting in particular in the adhesion amount of a coating layer liquid, According to the objective, it can select suitably, 0.5-20 g / m < ² > is preferable at solid content, and 1-15 g / m < ² > is more preferable.
Moreover, after impregnation or application | coating, you may make it dry as needed, and there is no restriction | limiting in particular as the temperature of drying in this case, Although it can select suitably according to the objective, About 100-250 degreeC is preferable. .

  In the recording medium, a back layer may be further provided on the back surface of the support, and other layers may be formed between the support and the coating layer or between the support and the back layer. Furthermore, a protective layer can be provided on the coating layer. Each of these layers may be a single layer or a plurality of layers.

As the recording medium, commercially available general-purpose printing paper, offset printing coated paper, gravure printing coated paper, and the like can be used in addition to the inkjet recording medium.
Commercially available coated coated paper refers to cast coated paper, so-called art paper (A0 size, A1 size), A2 size coated paper, A3 size coated paper, B2 size coated paper, lightweight coated paper, and fine coated paper. It is a coated paper used for printing / publishing printing, and is used for offset printing, gravure printing, and the like.
Specifically, aurora coat (made by Nippon Paper Industries Co., Ltd.), POD gloss coat (made by Oji Paper Co., Ltd.), etc. are mentioned.

(ink cartridge)
The ink cartridge of the present invention includes a container that contains the ink of the present invention, and other members that are appropriately selected as necessary.
The container is not particularly limited, and the shape, structure, size, material, and the like can be appropriately selected according to the purpose. For example, at least an ink bag formed of an aluminum laminate film, a resin film, or the like Preferred examples include those possessed.

Next, the ink cartridge will be described with reference to FIGS. FIG. 1 is a schematic diagram illustrating an example of an ink cartridge, and FIG. 2 is a schematic diagram illustrating a modification of the ink cartridge of FIG.
As shown in FIG. 1, after ink is filled into the ink bag (241) from the ink inlet (242) and exhausted, the ink inlet (242) is closed by fusion. In use, a needle of an ink jet recording apparatus main body (101) described later with reference to FIG. 3 is pierced into an ink discharge port (243) made of a rubber member, and ink is supplied to the apparatus main body (101).
The ink bag (241) is formed of a packaging member such as a non-permeable aluminum laminate film. As shown in FIG. 2, the ink bag (241) is usually housed in a plastic cartridge case (244) and is detachably mounted on various ink jet recording apparatuses.
The ink cartridge (201) contains ink (ink set) and can be used by being detachably attached to various ink jet recording apparatuses, and is particularly preferably used by being detachably attached to an ink jet recording apparatus described later. preferable.

(Inkjet recording method and inkjet recording apparatus)
The ink jet recording method includes at least an ink flying process, and further includes other processes appropriately selected as necessary, for example, a stimulus generation process, a control process, and the like.
The ink jet recording apparatus has at least ink flying means, and further has other means appropriately selected as necessary, for example, stimulus generation means, control means, and the like.
The ink jet recording method can be preferably carried out by the ink jet recording apparatus, and the ink flying step can be suitably carried out by the ink flying means. Moreover, the said other process can be suitably performed by the said other means.

-Ink flying process and ink flying means-
The ink flying process is a process of forming an image on a recording medium by applying a stimulus (energy) to the ink and causing it to fly.
The ink flying means is a means for forming an image on a recording medium by applying a stimulus (energy) to the ink and causing it to fly. The ink flying means is not particularly limited, and examples thereof include various nozzles for ejecting ink.
The stimulus (energy) can be generated by, for example, the stimulus generating means, and the stimulus is not particularly limited and can be appropriately selected according to the purpose, and includes heat (temperature), pressure, vibration and For example, light. These may be used individually by 1 type and may use 2 or more types together. Of these, heat and pressure are preferred.
Examples of the stimulus generating means include a heating device, a pressurizing device, a piezoelectric element, a vibration generating device, an ultrasonic oscillator, a light, and the like. Specifically, for example, a piezoelectric actuator such as a piezoelectric element, Examples include thermal actuators that use phase change due to liquid film boiling using electrothermal transducers such as heating resistors, shape memory alloy actuators that use metal phase changes due to temperature changes, electrostatic actuators that use electrostatic force, etc. It is done.

There is no particular limitation on the mode of the ink flight, and it varies depending on the type of the stimulus. For example, when the stimulus is “heat”, the heat corresponding to the recording signal is applied to the ink in the inkjet recording head. Examples include a method in which energy is applied using, for example, a thermal head, bubbles are generated in the ink by the thermal energy, and ink is ejected and ejected as droplets from the nozzle holes of the recording head by the pressure of the bubbles. . Further, when the stimulus is “pressure”, for example, by applying a voltage to a piezoelectric element bonded to a position called a pressure chamber in an ink flow path in the recording head, the piezoelectric element is bent, and the pressure chamber For example, a method in which the volume is reduced and ink is ejected and ejected as droplets from the nozzle holes of the recording head.
In the present invention, it is preferable that at least a part of the liquid chamber portion, the fluid resistance portion, the diaphragm, and the nozzle member of the recording head is formed of a material containing at least one of silicon and nickel.
The diameter of the nozzle of the recording head is preferably 30 μm or less, and more preferably 1 to 20 μm.

The size of the ink droplets to be ejected is preferably, for example, 3 × 10 ⁻¹⁵ to 40 × 10 ⁻¹⁵ m ³ ( ³ to 40 pL), and the ejection jet speed is 5 to 20 m / s. The drive frequency is preferably 1 kHz or more, and the resolution is preferably 300 dpi or more.
The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as sequencers and computers.

Here, an aspect of performing ink jet recording with a serial ink jet recording apparatus will be described with reference to the drawings.
3 is an apparatus main body (101), a paper feed tray (102) for loading paper into the apparatus main body (101), and an image formed (recorded) on the apparatus main body (101). A paper discharge tray (103) for stocking the used paper and an ink cartridge loading section (104). On the upper surface of the ink cartridge loading section (104), an operation section (105) such as operation keys and a display is arranged. The ink cartridge loading unit (104) has an openable / closable front cover (115) for attaching and detaching the ink cartridge (201).

As shown in FIGS. 4 and 5, a guide rod (131), which is a guide member horizontally mounted on left and right side plates (not shown), and a stay (132) are provided in the apparatus main body (101). 133) is slidably held in the main scanning direction, and is moved and scanned in the direction of the arrow in FIG. 5 by a main scanning motor (not shown).
The carriage (133) includes a plurality of recording heads (134) including four inkjet recording heads that eject ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). Are arranged in a direction crossing the main scanning direction, and the ink droplet ejection direction is directed downward.
Examples of the ink jet recording head constituting the recording head (134) include a piezoelectric actuator such as a piezoelectric element, a thermal actuator that uses a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, and a metal due to a temperature change. A shape memory alloy actuator using phase change, an electrostatic actuator using electrostatic force, or the like provided as energy generating means for ejecting ink can be used.
The carriage (133) is equipped with a sub tank (135) for each color for supplying ink of each color to the recording head (134). Ink is supplied to the sub tank (135) from an ink cartridge (201) loaded in the ink cartridge loading section (104) via an ink supply tube (not shown).

On the other hand, as a paper feeding unit for feeding the paper (142) stacked on the paper stacking unit (pressure plate) (141) of the paper feed tray (102), 1 sheet (142) is fed from the paper stacking unit (141). A half-moon roller (sheet feeding roller (143)) that separates and feeds sheets one by one, and a separation pad 144 that is made of a material having a large friction coefficient are provided opposite to the sheet feeding roller (143). The roller (143) is urged.
A conveying belt (151) for electrostatically adsorbing and conveying the paper (142) as a conveying unit for conveying the paper (142) fed from the paper feeding unit below the recording head (134). A counter roller (152) for conveying the paper (142) sent from the paper supply unit via the guide (145) between the conveying belt (151) and a paper (substantially vertically upward) ( 142) and a leading guide roller 153 urged toward the conveying belt (151) by the holding member (154). (155). Further, a charging roller (156) is provided as a charging means for charging the surface of the transport belt (151).

  The conveyance belt (151) is an endless belt, is stretched between the conveyance roller (157) and the tension roller (158), and can circulate in the belt conveyance direction. The transport belt (151) has, for example, a surface layer serving as a sheet adsorbing surface formed of a resin material having a thickness (40) μm that is not subjected to resistance control, for example, a copolymer of tetrafluoroethylene and ethylene (ETFE). And a back layer (medium resistance layer, earth layer) which is made of the same material as the surface layer and is subjected to resistance control by carbon. On the back side of the conveyance belt (151), a guide member (161) is arranged corresponding to the printing area by the recording head (134). As a paper discharge unit for discharging the paper (142) recorded by the recording head (134), a separation claw (171) for separating the paper (142) from the transport belt (151), and paper discharge A roller (172) and a paper discharge roller (173) are provided, and a paper discharge tray (103) is arranged below the paper discharge roller (172).

A double-sided paper feeding unit (181) is detachably attached to the back surface of the apparatus main body (101). The double-sided paper feeding unit (181) takes in the paper (142) returned by the reverse rotation of the transport belt (151), reverses it, and feeds it again between the counter roller (152) and the transport belt (151). . A manual paper feed unit (182) is provided on the upper surface of the double-sided paper feed unit (181).
In this ink jet recording apparatus, the sheet (142) is separated and fed one by one from the sheet feeding unit, and the sheet (142) fed substantially vertically upward is guided by the guide (145) and the transport belt (151). ) And the counter roller (152). Further, the leading end is guided by the conveying guide (153) and pressed against the conveying belt (151) by the leading end pressure roller (155), and the conveying direction is changed by about 90 °.
At this time, the conveyance belt (157) is charged by the charging roller (156), and the paper (142) is electrostatically adsorbed to the conveyance belt (151) and conveyed. Therefore, by driving the recording head (134) according to the image signal while moving the carriage (133), ink droplets are ejected onto the stopped sheet (142) to record one line, and the sheet ( 142), the next line is recorded after a predetermined amount is conveyed. Upon receiving a recording end signal or a signal that the rear end of the paper (142) has reached the recording area, the recording operation is finished and the paper (142) is discharged to the paper discharge tray (103).
When the near end of the ink remaining in the sub tank (135) is detected, a required amount of ink is supplied from the ink cartridge (201) to the sub tank (135).

In this ink jet recording apparatus, when the ink in the ink cartridge (201) is used up, the housing of the ink cartridge (201) can be disassembled and only the internal ink bag (241) can be replaced. Further, the ink cartridge (201) can supply ink stably even when the ink cartridge (201) is vertically placed and has a front loading configuration. Therefore, even when the upper part of the apparatus main body (101) is closed and installed, for example, when stored in a rack or when an object is placed on the upper surface of the apparatus main body (101), the ink The cartridge (201) can be easily replaced.
In addition, although it demonstrated in the example applied to the serial type (shuttle type) inkjet recording device which a carriage scans, it can apply similarly to the line type inkjet recording device provided with the line type head.

FIG. 7 shows a schematic diagram of the internal structure of the prototype line head printing apparatus (image recording apparatus A) used for the evaluation of the curl amount.
The image recording apparatus A has a configuration in which a sheet feeding tray (1), a pressure plate (2), and a sheet feeding rotating body (4) for feeding a recording sheet (3) are attached to a base (5).
The pressure plate (2) is rotatable about a rotation shaft (a) attached to the base (5), and is urged by the pressure plate spring (6) to the sheet feeding rotating body (4). In order to prevent double feeding of the recording paper (3), a separation pad (not shown) made of a material having a large coefficient of friction such as an artificial skin is provided at a portion of the pressure plate (2) facing the paper feeding rotating body (4). ) Is provided.
Further, a release cam (not shown) for releasing the contact between the pressure plate (2) and the sheet feeding rotating body (4) is provided.
In the above configuration, the release cam pushes the pressure plate (2) down to a predetermined position in the standby state. As a result, the contact between the pressure plate (2) and the sheet feeding rotator (4) is released.

  In this state, when the driving force from the conveying roller (7) is transmitted to the sheet feeding rotating body (4) and the release cam by a gear or the like, the release cam moves away from the pressure plate (2) and the pressure plate (2) rises. The sheet feeding rotator (4) contacts the recording sheet (3). The recording paper (3) is picked up and started to be fed along with the rotation of the paper feed rotating body (4), and separated one by one by a separation claw (not shown). The sheet feeding rotator (4) rotates to feed the recording sheet 3 into the platen (10) via the conveyance guides (8) and (9). The recording paper (3) passes between the conveyance guides (8) and (9) and is guided to the conveyance roller (7), and is conveyed to the platen (10) by the conveyance roller (7) and the pinch roller (11). Is done. Thereafter, the drive state from the conveying roller (7) is cut off again in the standby state in which the contact between the recording sheet (3) and the sheet feeding rotator (4) is released. The paper feed rotating body (12) for manual paper feed feeds the recording paper (3) mounted on the manual feed tray (13) in accordance with the recording command signal of the computer and transports it to the transport roller (7). It is. The recording paper (3) conveyed to the platen (10) passes under the line head (14). Here, the recording paper conveyance speed and the droplet discharge timing are adjusted based on a signal controlled by an electric circuit (not shown), thereby forming a desired image.

  The ink jet recording apparatus of the present invention can be applied to various types of recording by the ink jet recording method, and is particularly preferably applied to, for example, an ink jet recording printer, a facsimile apparatus, a copying apparatus, a printer / fax / copier multifunction machine, and the like. Can do.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated further more concretely, this invention is not limited at all by these Examples. In the examples, “part” is “part by mass”.

<Average molecular weight measurement>
The average molecular weight of the α-olefin-maleic anhydride copolymer represented by the general formula (III) used in the present invention was measured as follows using a GPC (gel permeation chromatographic analysis) system.
First, the copolymer was dissolved in the same tetrahydrofuran as the eluent, and KF-806L (for THF) was used as the GPC column. As a molecular weight standard substance, three types of polystyrenes (molecular weights 1000, 2400, 8500) with known molecular weights were used, and a calibration curve was prepared.
Then, the copolymer was subjected to GPC measurement, and the weight average molecular weight was calculated from the obtained SEC chromatogram, differential molecular weight distribution curve, and a graph reflecting the calibration curve obtained with the molecular weight standard substance.

[Production Example 1]
In a 300 mL separable flask equipped with a stirrer, a thermocouple, and a nitrogen gas inlet tube, 19.828 g of N, N-dimethylacrylamide and 14.824 g of 1-butanol were added and stirred while introducing nitrogen gas. Next, 0.338 g of sodium-t-butoxide was added, and the reaction was performed at 35 ° C. for 4 hours. After completion of heating, 150 mg of phosphoric acid was added to make the solution uniform, and the mixture was allowed to stand for 3 hours. The solution was filtered to remove precipitates, and unreacted substances were removed with an evaporator. The yield was 30.5 g (88% yield). When ¹ H-NMR of the obtained substance was measured, it was 0.95 ppm (3H), 1.3 to 1.5 ppm (4H), 2.4 ppm (2H), 2.9 ppm (6H), 3.4 ppm ( 2H) and 3.7 ppm (2H) were observed. As a result, the following structure was found.

(Preparation Example 1)
-Preparation of aqueous solution of water-soluble polymer compound α-

-Α-olefin-maleic anhydride copolymer represented by the above general formula (III) [manufactured by Seiko PMC, T-YP112, carbon number 20-24 of olefin chain (R): R ₁ in general formula (III) Is a copolymer corresponding to an alkyl group having 18 to 22 carbon atoms], acid value 190 mgKOH / g, weight average molecular weight = 10,000)... 10.0 parts ・ 1N LiOH aqueous solution [the above general formula (III ) 1.2 times the acid value of the copolymer]
... 17.34 parts ・ Ion-exchanged water ... 72.66 parts

The above material mixture is heated and stirred with a stirrer to dissolve the α-olefin-maleic anhydride copolymer represented by the general formula (III), and a small amount of insoluble matter is filtered through a filter having an average pore diameter of 5 μm. Aqueous polymer compound aqueous solution α was prepared.

(Preparation Example 2)
-Preparation of surface-treated black pigment dispersion-
90 g of carbon black having a CTAB specific surface area of 150 m ² / g and DBP oil absorption of 100 mL / 100 g is added to 3,000 mL of 2.5 N sodium sulfate solution, stirred at a temperature of 60 ° C. and a speed of 300 rpm, and allowed to react for 10 hours. Oxidation treatment was performed. The reaction solution was filtered, and the carbon black separated by filtration was neutralized with a sodium hydroxide solution and subjected to ultrafiltration.
The obtained carbon black was washed with water, dried, dispersed in pure water so as to have a solid content of 30% by mass, and sufficiently stirred to obtain a black pigment dispersion. The volume average particle size (D50) of the pigment dispersion in this dispersion was measured with a particle size distribution analyzer (Nikkiso Co., Ltd., Nanotrac UPA-EX150), and found to be 103 nm.

(Preparation Example 3)
-Preparation of polymer fine particle dispersion containing magenta pigment-
<Preparation of polymer solution A>
After sufficiently replacing nitrogen gas in the 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube and dropping funnel, 11.2 g of styrene, 2.8 g of acrylic acid, 12.0 g of lauryl methacrylate, Polyethylene glycol methacrylate 4.0 g, styrene macromer 4.0 g, and mercaptoethanol 0.4 g were mixed and heated to 65 ° C.
Next, 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g of lauryl methacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0 g of hydroxylethyl methacrylate, 36.0 g of styrene macromer, 3.6 g of mercaptoethanol, azobismethylvalero A mixed solution of 2.4 g of nitrile and 18 g of methyl ethyl ketone was dropped into the flask over 2.5 hours. After dropping, a mixed solution of 0.8 g of azobismethylvaleronitrile and 18 g of methyl ethyl ketone was dropped into the flask over 0.5 hours. After aging at 65 ° C. for 1 hour, 0.8 g of azobismethylvaleronitrile was added, and further aged for 1 hour. After completion of the reaction, 364 g of methyl ethyl ketone was added to the flask to obtain 800 g of a polymer solution A having a concentration of 50% by mass.

<Preparation of pigment-containing polymer fine particle dispersion>
28 g of polymer solution A, C.I. I. 42 g of Pigment Red 122, 13.6 g of 1 mol / L potassium hydroxide aqueous solution, 20 g of methyl ethyl ketone and 13.6 g of ion-exchanged water were sufficiently stirred, and then kneaded using a roll mill. The obtained paste was put into 200 g of pure water and stirred sufficiently, and then methyl ethyl ketone and water were distilled off using an evaporator, and this dispersion was removed from the polyvinylidene fluoride having an average pore size of 5.0 μm to remove coarse particles. The mixture was filtered under pressure with a membrane filter to obtain a magenta pigment-containing polymer fine particle dispersion containing 15% by mass of pigment and 20% by mass of solids. The volume average particle size (D50) of the polymer fine particles in this dispersion was measured with a particle size distribution measuring device (Nikkiso Co., Ltd., Nanotrac UPA-EX150) and found to be 127 nm.

(Preparation Example 4)
-Preparation of Cyan Pigment-Containing Polymer Fine Particle Dispersion-
Pigment C.I. I. A cyan pigment-containing polymer fine particle dispersion was prepared in the same manner as in Preparation Example 3, except that Pigment Red 122 was changed to a phthalocyanine pigment (CI Pigment Blue 15: 3). The volume average particle size (D50) of the polymer fine particles in this dispersion was measured with a particle size distribution measuring device (Nikkiso Co., Ltd., Nanotrac UPA-EX150), and found to be 93 nm.

(Preparation Example 5)
-Preparation of yellow pigment-containing polymer fine particle dispersion-
Pigment C.I. I. A yellow pigment-containing polymer fine particle dispersion was prepared in the same manner as in Preparation Example 3, except that Pigment Red 122 was changed to a monoazo yellow pigment (CI Pigment Yellow 74). It was 76 nm when the volume average particle diameter (D50) of the polymer fine particles in this dispersion liquid was measured with a particle size distribution measuring device (Nikkiso Co., Ltd., Nanotrac UPA-EX150).

(Preparation Example 6)
-Preparation of carbon black pigment-containing polymer fine particle dispersion-
Pigment C.I. I. A carbon black pigment-containing polymer fine particle dispersion was prepared in the same manner as in Preparation Example 3 except that the pigment red 122 was changed to carbon black (FW 100 manufactured by Degussa). The volume average particle size (D50) of the polymer fine particles in this dispersion was measured with a particle size distribution measuring device (Nikkiso Co., Ltd., Nanotrac UPA-EX150), and was 104 nm.

-Preparation of ink-
[Example 1]
Inks were prepared using the materials shown in the column of Example 1 in Table 2.
10.00 parts of C6 amide compound of general formula (I) (R1 has 6 carbon atoms), 5.00 parts of amide compound of formula (I), compound of general formula (II) (1-n-octyl-2- Pyrrolidone) 5.00 parts, glycerin 10.00 parts, 1,3-butanediol 10.00 parts, 2-ethyl-1,3-hexanediol 2.00 parts, Sonyl FS-3001.25 parts, and silicone 0.10 parts of antifoaming agent KM-72F was mixed and stirred for 1 hour to mix uniformly.
To this mixture, 0.05 part of Proxel GXL, 0.30 part of 2-amino-2-ethyl-1,3-propanediol, and pure water in an amount necessary to make the whole ink 100 parts are added. After stirring for 1 hour, 50.00 parts of the black pigment-containing polymer dispersion of Preparation Example 6 were added and mixed, and stirred for 1 hour.
This mixed liquid was subjected to pressure filtration with a polyvinylidene fluoride membrane filter having an average pore diameter of 0.8 μm to remove coarse particles and dust, whereby the ink of Example 1 was obtained.

[Examples 2 to 8] [Comparative Examples 1 to 5]
In the same manner as in Example 1, inks were prepared using the materials shown in the columns of Examples 2 to 8 and Comparative Examples 1 to 5 in Table 2.

Abbreviations in Table 2 represent the following meanings.
Acrylic-silicone resin emulsion: Showa Polymer Co., Ltd., Polysol ROY6312, solid content 37.2% by mass, average particle diameter 171 nm, minimum film-forming temperature (MFT) = 20 ° C.
-Polyurethane emulsion: manufactured by DIC, Hydran APX-101H, solid content 45% by mass, average particle diameter 160 nm, minimum film-forming temperature (MFT) = 20 ° C.
KF-643: polyether-modified silicone compound (manufactured by Shin-Etsu Chemical Co., Ltd., component 100% by mass)
・ Zonyl FS-300: polyoxyethylene perfluoroalkyl ether (manufactured by Dupont, component 40 mass%)
Softanol EP-7025: polyoxyalkylene alkyl ether (manufactured by Nippon Shokubai Co., Ltd., 100 mass% component)
Proxel GXL: Antifungal agent mainly composed of 1,2-benzisothiazolin-3-one (manufactured by Avicia, component 20% by mass, containing dipropylene glycol)
KM-72F: self-emulsifying silicone defoaming agent (manufactured by Shin-Etsu Silicone Co., Ltd., 100% by mass)

The inks of Examples 1 to 8 and Comparative Examples 1 to 5 were evaluated by the evaluation methods shown below. The results are summarized in Tables 3 and 4.
<Ink viscosity>
The viscosity of the ink was measured at 25 ° C. using a viscometer (RE-550L, manufactured by Toki Sangyo Co., Ltd.).
<Ink surface tension>
The surface tension of the ink was measured at 25 ° C. using a fully automatic surface tension meter (CBVP-Z, manufactured by Kyowa Interface Science Co., Ltd.).

−Preparation for print evaluation−
Piezo elements using an ink jet printer (IPSiO GXe-5500, manufactured by Ricoh) under an environmental condition adjusted to a temperature of 23 ± 0.5 ° C. and a relative humidity of 50 ± 5% RH so that the amount of ink discharged is uniform. Was set so that the same amount of ink was applied to the recording medium.

<Image density>
Using an ink of each color of black, yellow, magenta, and cyan, a chart in which a general symbol of 64 points JIS X 0208 (1997), 2223 created by Microsoft Word 2000 is written on MyPaper (manufactured by Ricoh) The symbol was color-measured with X-Rite 939 (manufactured by X-Rite) to evaluate the image density. The evaluation criteria are as follows. The print mode is a driver attached to the printer, and a mode in which the “plain paper-standard fast” mode is changed to “no color correction” from the user setting of plain paper is used. Note that JIS X 0208 (1997), 2223 is a symbol whose outer shape is a regular square and the entire symbol surface is filled with ink.
〔Evaluation criteria〕
A: Black: 1.20 or more
Yellow: 0.80 or more
Magenta: 1.00 or more
Cyan: 1.00 or more ○: Black: 1.10 or more, less than 1.20
Yellow: 0.70 or more, less than 0.80
Magenta: 0.90 or more and less than 1.00
Cyan: 0.90 or more, less than 1.00 ×: Black: less than 1.10
Yellow: less than 0.70
Magenta: Less than 0.90
Cyan: Less than 0.90

<Evaluation of curl amount>
Using the prototype line head printing device shown in FIG. 7, solid printing was performed under the following printing conditions, and the back curl (within 10 seconds after discharging from the printing device) was placed on the flat desk with the printing surface on the lower side. Curl height), and the curl height after leaving the printing surface face down on a flat desk for 1 day was evaluated.
(1) Evaluation printer: Prototype line head printer (see Fig. 7)
(2) Evaluation recording medium: MyPaper (PPC paper: A4 size) manufactured by Ricoh Company (3) Printing conditions: recording density 300 × 600 dpi, printing area 526.3 cm ² / A4,
Ink discharge adhesion amount 5.6 g / m ²
(4) Evaluation environment: 23 ± 0.5 ° C., 50 ± 5% RH
(5) Curl measurement: Immediately after printing (within 10 seconds after ejection from the printing device) and after leaving it for 1 day, place the recording medium gently on a flat desk with the curled surface facing up, at the four corners of the recording medium. The curl height was measured on a JIS_1 grade, and the average value of 4 points was calculated. Also,
When the curl was too large and became a cylinder, “x” was assigned.
〔Evaluation criteria〕
◎: Less than 10 mm ○: 10 mm or more, less than 40 mm Δ: 40 mm or more ×: Tubular

<Discharge stability>
A chart that fills an area of 5% of A4 size paper per color created with Microsoft Word 2000 with a solid image is ejected to 200 continuous MyPaper (manufactured by Ricoh). Evaluated by criteria. The printing mode used was a driver attached to the printer, in which the "plain paper-standard fast" mode was changed to "no color correction" from the user setting for plain paper.
〔Evaluation criteria〕
○: Discharge turbulence △: Discharge turbulence slightly ×: Discharge turbulence or non-discharge portion

<Storage stability>
The storage stability of each ink was determined according to the following formula from the viscosity before storage measured using the viscometer and the viscosity measured after storage for 7 days in a sealed container at 70 ° C., and evaluated according to the following criteria: did.
Storage stability (%) = (viscosity after storage / viscosity before storage) × 100

〔Evaluation criteria〕
○: Within 100 ± 10% △: Over 100 ± 10 and less than 100 ± 20% ×: 100 ± 20% or more

From the evaluation results, it was confirmed that the ink of the present invention is excellent in image quality and image density in addition to exhibiting an effect of suppressing curling after printing on plain paper.
In addition, the ink of the present invention provides an image with excellent image fastness such as water resistance and light resistance, excellent drying speed and high-speed printing, good ejection stability from the nozzle, and high-quality image. Formation is possible.
The ink jet recording apparatus of the present invention can be applied to various types of recording by the ink jet recording method, and is particularly preferably applied to, for example, an ink jet recording printer, a facsimile apparatus, a copying apparatus, a printer / fax / copier multifunction machine, and the like. Can do.

a Rotating shaft 1 Paper feed tray 2 Pressure plate 3 Recording paper 4 Paper feed rotator 5 Base 6 Pressure plate spring 7 Transport roller 8 Transport guide 9 Transport guide 10 Platen 11 Pinch roller 12 Paper feed rotator for manual feed 13 Manual tray 14 Line head 101 Main body 102 Paper feed tray 103 Paper discharge tray 104 Ink cartridge loading section 105 Operation section 111 Upper cover 112 Front face 115 Front cover 131 Guide rod 132 Stay 133 Carriage 134 Recording head 135 Sub tank 141 Paper stacking section 142 Paper 143 Paper feed Roller 144 Separation pad 145 Guide 151 Conveying belt 152 Counter roller 153 Conveying guide 154 Pressing member 155 Tip pressure roller 156 Charging roller 157 Conveying roller 158 Tension roller 161 Guide member 171 min Pawl 172 paper discharge roller 173 discharge feed roller 181 duplex paper feed unit 182 hand paper feed unit 201 ink cartridge 241 ink bag 242 ink inlet 243 ink discharge port 244 cartridge case

JP 2004-136458 A JP 2008-018711 A JP 2009-052018 A JP 2009-287014 A

Claims (5)

In an inkjet ink containing at least water, a water-soluble organic solvent, a surfactant, and a colorant, the water-soluble organic solvent has an equilibrium water content of 30% by weight or more at a temperature of 23 ° C. and a relative humidity of 80%. At least one amide compound represented by the following general formula (I), an amide compound represented by the following formula (I), and at least one compound represented by the following general formula (II). An ink-jet ink comprising a seed.

In the above formula, R1 represents an alkyl group having 4 to 6 carbon atoms.

In the above formula, R2 represents either an alkyl group having 8 or 12 carbon atoms or a cyclic alkyl having 6 carbon atoms.   The water-soluble organic solvent contains at least one alkylalkanediol having a main chain of an alkanediol having 3 to 6 carbon atoms and a branched chain having an alkyl group having 1 to 2 carbon atoms. The ink for inkjet described in 2.   The alkylalkanediol is 2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol. The inkjet ink according to claim 2, wherein the inkjet ink is at least one selected from the group consisting of:   An ink cartridge comprising the ink-jet ink according to claim 1 contained in a container.   5. An ink jet recording apparatus comprising: the ink cartridge according to claim 4; and ink flying means for forming an image on a recording medium by applying a stimulus to the ink jet ink and causing the ink to fly.

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