JP5573001B2 - INKJET INK, INK CARTRIDGE, INKJET RECORDING DEVICE, INKJET RECORDING METHOD, AND INK RECORDED MATERIAL - Google Patents

Description

  The present invention relates to an inkjet ink, an ink cartridge, an inkjet recording apparatus, an inkjet recording method, and an ink recorded matter.

  Conventionally, as ink-jet inks, dye inks have been mainly used from the standpoint of good color developability and high reliability. However, since the dye ink has the disadvantage of being inferior in water resistance and light resistance, attention has been focused on the pigment ink in recent years.

  With respect to this pigment ink, various methods are adopted in order to improve printing quality or achieve high-speed printing. One of the methods is to use a highly viscous ink having high permeability.

  For example, there has been proposed an ink using a specific fine fluorosurfactant using an aqueous dispersion of colored fine particles obtained by adding a coloring material to polymer fine particles as a colorant (see Patent Document 1 and Patent Document 2). These inks have higher viscosity than conventional inks but low surface tension, and are characterized in that in the printing on plain paper, the vehicle penetrates quickly and the color material component tends to remain on the surface. As a result, it is possible to obtain an image with high saturation and high color density and with little show-through.

  However, generally, when polymer fine particles are used, the cohesiveness is increased and the ejection stability is lowered. In addition, when a fluorosurfactant is used, the surface tension of the ink is lowered and foaming is likely to occur, and defoaming is difficult due to the increase in viscosity.

  In order to improve the defoaming property of ink, it has been proposed to use an antifoaming agent (see Patent Document 3). This ink includes a dispersion in which a colorant is included in a polymer so as to be dispersible in water, and an acetylene glycol surfactant as a surfactant and an ethyleneoxy-modified silicone compound having a specific structure are erased. Contains as a foaming agent. According to this ink, the problem of foaming is solved by using an antifoaming agent. However, this antifoaming agent is difficult to dissolve in water-based ink due to the defoaming mechanism, and there is a problem that the ejection stability is further lowered.

  As described above, high-viscosity and high-permeability inks have been proposed to form high-quality images by printing on plain paper at high speed. However, such inks tend to foam and have a problem in filling properties. is there. When an antifoaming agent is used to solve the problem of filling property, it is difficult to ensure the stability of the ink, so that it is difficult to use it.

JP 2006-316243 A JP 2006-83243 A Japanese Patent Laid-Open No. 2005-97597

  The present invention solves the above-mentioned problems in the prior art, enables formation of a high-quality image on plain paper, and has excellent storage stability and filling properties. Ink-jet ink and ink cartridge using the ink-jet ink It is an object to provide an ink jet recording apparatus, an ink jet recording method, and an ink recorded matter.

Means for solving the problems are as follows. That is, the inkjet ink of the present invention includes a water-dispersible colorant, a water-soluble organic solvent, a fluorosurfactant, a foam suppressor and water, wherein the foam suppressor is a compound represented by the general formula (I). der is, the fluorine-based surfactant, to contain the compound represented by the general formula (II), characterized in Rukoto.
Formula (I)
_{HOR 1 R 3 C- [CH 2} ] n -CR 2 R 4 OH
However, in the general formula (I), _{R 1} and _{R 2} are independently an alkyl group having 3-6 carbon atoms, _{R 3} and _{R 4} are alkyl radicals having 1-2 carbon atoms independently And n is an integer of 1-6.

  In this case, the compound represented by the general formula (I) is 2,4,7,9-tetramethyldecane-4,7-diol or 2,5,8,11-tetramethyldodecane-5,8- A diol is preferred.

In this case, the fluorosurfactant is preferably at least one selected from the compounds represented by the general formulas (II) to (V).
Formula (II)
_{C n F 2n + 1 -CH 2} CH (OH) CH 2 -O- (CH 2 CH 2 O) a -Y '
However, in the general formula (II), n is an integer from 2 to 6, a is an integer from 15 to 50, Y 'is _-C b _{H 2b +} 1 (b is an integer of 11 to 19) or - _{CH 2 CH (OH) CH 2} -C d F 2d + 1 (d is a is an integer from 2 to 6) represents a.
Formula (III)
_{CF 3 CF 2 (CF 2 CF} 2) j -CH 2 CH 2 O (CH 2 CH 2 O) k H
However, in general formula (III), j represents 0-10 and k represents the integer of 0-40.
Formula (IV)

ただし、一般式（ＩＶ）中、Ｒｆはパーフルオロアルキル基を表す。ｍは６〜２５の整数を表し、ｎ及びｐは１〜４の整数を表す。
一般式（Ｖ）

However, in general formula (IV), Rf represents a perfluoroalkyl group. m represents an integer of 6 to 25, and n and p represent an integer of 1 to 4.
General formula (V)

ただし、一般式（Ｖ）中、Ｒｆはパーフルオロアルキル基を表す。Ｘは第４級アンモニウム基；ナトリウム、カリウム等のアルカリ金属；トリエチルアミン、トリエタノールアミンを表し、Ｙは−ＣＯＯ⁻、−ＳＯ_３ ⁻、−ＳＯ_４ ⁻、−ＰＯ_４ ⁻を表す。ｑは１〜６の整数を表す。

However, in general formula (V), Rf represents a perfluoroalkyl group. X represents a quaternary ammonium group; an alkali metal such as sodium or potassium; triethylamine or triethanolamine; Y represents —COO ⁻ , —SO ₃ ^— , —SO ₄ ^— or —PO ₄ ^— . q represents the integer of 1-6.

In this case, the compound represented by the general formula (II) is C ₄ F ₉ —CH ₂ CH (OH) CH ₂ O— (CH ₂ CH ₂ O) ₂₁ —C ₁₂ H ₂₅ , C ₄ F ₉ —. _{CH 2 CH (OH) CH 2} O- (CH 2 CH 2 O) 25 -C 12 H 25, C 4 F 9 -CH 2 CH (OH) CH 2 O- (CH 2 CH 2 O) 23 -CH 2 _{CH (OH) CH 2 -C 4} F 9, C 4 F 9 -CH 2 CH (OH) CH 2 O- (CH 2 CH 2 O) 35 -CH 2 CH (OH) CH 2 -C 4 F 9, or it is preferably _{C 4 F 9 -CH 2 CH (} OH) CH 2 O- (CH 2 CH 2 O) 45 -CH 2 CH (OH) CH 2 -C 4 F 9.

  In this case, the water-dispersible colorant is preferably a pigment, and the pigment is preferably at least one selected from the group consisting of a self-dispersible pigment and a pigment coated with a resin.

In this case, the coating resin of the pigment coated with the resin is a water-insoluble vinyl polymer, and the water-insoluble vinyl polymer is (A) a monomer represented by the general formula (VI), (B) a salt-forming group-containing monomer. And (C) a monomer mixture containing a hydrophobic monomer is preferably polymerized.
Formula (VI)

ただし、一般式（ＶＩ）中、Ｒ_１は水素原子又はメチル基であり、Ｒ_２は炭素数２〜８のアルキレン基又は水素原子がフェニル基で置換された炭素数２〜４のアルキレン基であり、ｎは２〜３０の数であり、Ｒ_３は炭素数２〜３０の直鎖又は分岐鎖のアルキル基を表す。

However, in the general formula (VI), R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 4 carbon atoms which alkylene group or a hydrogen atom C2-8 substituted with a phenyl group Yes, n is a number of 2 to 30, and R ₃ represents a linear or branched alkyl group having 2 to 30 carbon atoms.

In this case, the hydrophobic monomer (C) is (C-1) a monomer represented by the general formula (VII), (C-2) a monomer represented by the general formula (VIII), and (C-3) It is preferable to contain at least one selected from macromers.
Formula (VII)

ただし、一般式（ＶＩＩ）中、Ｒ_４は水素原子又はメチル基であり、Ｒ_５は炭素数１〜２２のアルキル基、炭素数６〜２２のアリール基、アルキルアリール基、若しくはアリールアルキル基、又は炭素数３〜２２の環式炭化水素基を表す。
一般式（ＶＩＩＩ）

However, in the general formula (VII), _{R 4} is a hydrogen atom or a methyl group, _{R 5} is an alkyl group having 1 to 22 carbon atoms, an aryl group having 6 to 22 carbon atoms, alkylaryl group or arylalkyl group, Or it represents a C3-C22 cyclic hydrocarbon group.
Formula (VIII)

ただし、一般式（ＶＩＩＩ）中、Ｒ_６は水素原子又はメチル基であり、Ｒ_７は置換基を有しても良いフェニル基、ビフェニル基、又はナフタレン基を表す。

However, in general formula (VIII), R < ₆ > is a hydrogen atom or a methyl group, and R < ₇ > represents the phenyl group, biphenyl group, or naphthalene group which may have a substituent.

  In this case, the viscosity of the ink residue left until the mass change substantially disappears in an environment of temperature 25 ° C. and humidity 15% is 3000 mPa · s or less, and the viscosity of the ink preparation adjusted to pH 7 with acid is 500 mPa. -It is preferable that it is more than s.

  In this case, it is preferable to contain any of 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol as the penetrant.

  The ink cartridge of the present invention comprises the ink jet ink of the present invention contained in a container.

  The inkjet recording method of the present invention is characterized by including an ink flying step of applying an stimulus to the inkjet ink of the present invention and flying the inkjet ink to form an image.

  The ink jet recording apparatus of the present invention has ink flying means for applying a stimulus to the ink jet ink of the present invention and causing the ink jet ink to fly to form an image on a recording medium.

  The ink recorded matter of the present invention has an image formed by flying the ink for injection of the present invention on a recording medium.

  As is clear from the following detailed and specific description, according to the present invention, various problems in the prior art can be solved, high-quality images can be formed on plain paper, and storage stability and filling properties are excellent. Ink jet ink, an ink cartridge using the ink jet ink, an ink jet recording apparatus, an ink jet recording method, and an ink recorded matter can be provided.

It is the schematic which shows the ink cartridge of this embodiment. FIG. 7 is a schematic diagram illustrating a modification of the ink cartridge in FIG. 1. FIG. 3 is a perspective view of the ink jet recording apparatus of the present embodiment in a state where a cover of an ink cartridge loading unit is opened. It is sectional drawing explaining the whole structure of the inkjet recording device of FIG. It is a schematic enlarged view showing an ink jet head of the ink jet recording apparatus of the present embodiment. It is principal part plane explanatory drawing of the example of a subsystem containing the maintenance apparatus of the inkjet recording device of this embodiment. It is a figure which shows the foamability and defoaming property test result of the inkjet ink of this embodiment. It is a figure which shows the foamability and defoaming property test result of the inkjet ink of this embodiment.

  Hereinafter, the present invention will be described in more detail with reference to preferred embodiments.

<< Ink for inkjet >>
The ink-jet ink of the present embodiment includes a water-dispersible colorant, a water-soluble organic solvent, a fluorosurfactant, a foam inhibitor and water, and the foam inhibitor is a compound represented by the general formula (I) It is.

<Foam suppressant>
In the present embodiment, the antifoaming agent is used to suppress foaming by adding a small amount to the ink jet ink. Here, foaming means that the liquid becomes a thin film and wraps air. The generation of bubbles involves characteristics such as surface tension and viscosity of the ink-jet ink. That is, a liquid having a high surface tension such as water is difficult to foam because a force that attempts to make the surface area of the liquid as small as possible works. On the other hand, high-viscosity and high-permeability ink-jet inks tend to foam because of their low surface tension, and bubbles generated by the viscosity of the solution are easily maintained and are difficult to defoam.

  Usually, the foam suppressor destroys the foam by locally lowering the surface tension of the foam film to destroy the foam or by interspersing the foam suppressor with a foam suppressor insoluble in the foam liquid. When an extremely strong fluorosurfactant that reduces surface tension is used as a surfactant in inkjet inks, the surface tension of the foam film is locally reduced even if the former foam suppressor is used. Because it cannot be used, it is not usually used. For this reason, an antifoaming agent that is insoluble in the latter foaming liquid is used. In this case, the stability of the ink jet ink is lowered by the antifoaming agent insoluble in the solution.

  On the other hand, the foam suppressor of the general formula (I) is not as strong as the fluorosurfactant in reducing the surface tension, but is highly compatible with the fluorosurfactant. For this reason, when the foam is efficiently incorporated into the foam film, the surface of the foam film is locally unbalanced due to the difference in surface tension between the fluorosurfactant and the foam suppressor, and the foam is destroyed. Conceivable.

In the present embodiment, as the antifoaming agent, a compound represented by the general formula (I) is used.
Formula (I)
_{HOR 1 R 3 C- [CH 2} ] n -CR 2 R 4 OH
However, in the general formula (I), _{R 1} and _{R 2} are independently an alkyl group having 3-6 carbon atoms, _{R 3} and _{R 4} are alkyl radicals having 1-2 carbon atoms independently And n is an integer of 1-6.

  Preferable examples of the compound represented by the general formula (I) include 2,4,7,9-tetramethyldecane-4,7-diol, 2,5,8,11-tetramethyldodecane-5,8. -Diols, and 2,5,8,11-tetramethyldodecane-5,8-diol is particularly preferred because of its high antifoaming effect and high ink compatibility.

  The content of the foam suppressor in the ink is preferably 0.01 to 10% by mass, and more preferably 0.1 to 5% by mass. When the content of the foam suppressor is less than 0.01% by mass, the effect of suppressing foam may not be obtained. When the content exceeds 10% by mass, the foam suppressive effect reaches its peak, and the viscosity, Ink physical properties such as particle size may be adversely affected.

<Fluorosurfactant>
As the fluorosurfactant, a fluorosurfactant having a perfluoroalkyl group is used, and at least one selected from compounds represented by general formulas (II) to (V) is particularly preferably used. It is done.

Formula (II)
_{C n F 2n + 1 -CH 2} CH (OH) CH 2 -O- (CH 2 CH 2 O) a -Y '
However, in the general formula (II), n is an integer from 2 to 6, a is an integer from 15 to 50, Y 'is _-C b _{H 2b +} 1 (b is an integer of 11 to 19) or - _{CH 2 CH (OH) CH 2} -C d F 2d + 1 (d is a is an integer from 2 to 6) represents a.

Formula (III)
_{CF 3 CF 2 (CF 2 CF} 2) j -CH 2 CH 2 O (CH 2 CH 2 O) k H
However, in general formula (III), j represents 0-10 and k represents the integer of 0-40.

  Formula (IV)

ただし、一般式（ＩＶ）中、Ｒｆはパーフルオロアルキル基を表す。ｍは６〜２５の整数を表し、ｎ及びｐは１〜４の整数を表す。

However, in general formula (IV), Rf represents a perfluoroalkyl group. m represents an integer of 6 to 25, and n and p represent an integer of 1 to 4.

  General formula (V)

However, in general formula (V), Rf represents a perfluoroalkyl group. X represents a quaternary ammonium group; an alkali metal such as sodium or potassium; triethylamine or triethanolamine; Y represents —COO ⁻ , —SO ₃ ^— , —SO ₄ ^— or —PO ₄ ^— . q represents the integer of 1-6.

  Preferable examples of the compound represented by the general formula (II) include compounds represented by the following formulas a) to u) for reasons such as high ability to lower surface tension and high permeability.

Among these, the compounds of the formulas e), f), s), t) or u) having good compatibility with the compound of the general formula (I) are particularly preferable.

In the compound represented by the general formula (II), the HLB value of griffin is preferably 10 to 16 for the reason of solubility in water-based ink. In the compound represented by the general formula (II), the molecular weight (MWEO) of the polyoxyethylene group [(CH ₂ CH ₂ O) _a portion] and the fluoroalkyl group (C _n F _{2n + 1} portion and C _m F _{2m + 1)} The molecular weight (MWF) of the (part) preferably satisfies the relationship of the formula: MWEO / MWF = 2.2 to 10 for reasons such as the function as a surfactant and the solubility in water.

  In the compound represented by the general formula (III), j is preferably 0 to 10 and k is preferably 0 to 40 for the reason of the water-soluble surfactant function. As the compound represented by the general formula (III), a commercially available fluorosurfactant can be used, for example, Surflon S-111, S-112, S-113, S-121, S-131. , S-132, S-141, 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, FC-4430 (both manufactured by Sumitomo 3M Co., Ltd.); Megafac F-470, F-1405, F-474 (both manufactured by Dainippon Ink & Chemicals, Inc.); Zonyl FS-300, FSN, FSN-100, FSO (all manufactured by DuPont); EF-top EF-351, EF-352, EF-801, EF-802 (all manufactured by Gemco) It is below. Among these, Zonyl FS-300, FSN, FSN-100, and FSO (all manufactured by DuPont), which are favorable in terms of reliability and color development, are particularly suitable. These commercial products are a mixture of compounds having several kinds of molecular weights, and j and k in the general formula (III) often have a distribution, but there is no problem in the effect of the present invention.

In the compound represented by the general formula (IV), Rf is particularly preferably a perfluoroalkyl group for the reason of a surfactant function. As this perfluoroalkyl group, a C1-C10 thing is preferable and a 1-3 thing is more preferable. Examples of such a perfluoroalkyl group include those represented by —C _n F _2n-1 (where n represents an integer of 1 to 10), such as —CF ₃ , —CF _{2. CF 3, -C 3 F 7,} -C 4 F 9, and the like. Among these, —CF ₃ and —CF ₂ CF ₃ are particularly preferable. m, n, and p represent an integer, n is preferably 1-4, m is preferably 6-25, and p is preferably 1-4.

In the compound represented by the general formula (V), Rf is preferably a perfluoroalkyl group similar to that in the general formula (IV). For example, -CF ₃ , -CF ₂ CF ₃ , -C ₃ F ₇ , etc. -C ₄ F ₉ is preferably used. In the compound represented by the general formula (V), X represents a cationic group, and examples thereof include quaternary ammonium groups; alkali metals such as sodium and potassium; triethylamine, triethanolamine, and the like. A quaternary ammonium group is particularly preferred. In the compound represented by the general formula (V), Y represents an anionic group, ^{_{e.g., -COO -, -SO 3 -,}} -SO 4 -, -PO 4 -, and the like. q represents an integer, and preferably 1 to 6, for example.

The at least one fluorosurfactant selected from the general formula (IV) and the general formula (V) is particularly a compound represented by the following general formulas (IV-I) and (VI). At least one selected is also suitable from the viewpoint of safety.
Formula (IV-I)

ただし、前記一般式（ＩＶ−Ｉ）中、Ｒｆは−ＣＦ_３、−ＣＦ_２ＣＦ_３を表す。ｎは１〜４、ｍは６〜２５、ｐは１〜４である。
一般式（Ｖ−Ｉ）

In the general formula (IV-I), Rf represents _{-CF 3, -CF} 2 CF 3. n is 1-4, m is 6-25, p is 1-4.
General formula (VI)

In the general formula (V-I), Rf represents _{-CF 3, -CF} 2 CF 3. q is 1-6.

  The content of the fluorosurfactant in the ink is preferably 0.01 to 10% by mass, and more preferably 0.03 to 5% by mass. When the content of the fluorosurfactant is less than 0.01% by mass, a color development improvement effect at a level that can be felt visually may not be obtained. When the content exceeds 10% by mass, a color development improvement effect may be obtained. In addition to peaking, ink physical properties such as viscosity and particle size may be adversely affected.

  In the inkjet ink of the present embodiment, at least one fluorine-based surfactant selected from the general formulas (II) to (V) may be used singly or in combination of two or more. May be used. Furthermore, other fluorine-based surfactants, nonionic surfactants, anionic surfactants, amphoteric surfactants, acetylene glycol surfactants and the like can be used in combination.

<Water dispersible colorant>
As the water dispersible colorant, a pigment is mainly used from the viewpoint of weather resistance. However, for the purpose of adjusting the color tone, a dye may be contained at the same time as long as the weather resistance is not deteriorated. The pigment is not particularly limited and may be appropriately selected depending on the purpose. A black or colored inorganic pigment or an organic pigment may be used alone or in combination of two or more. Also good.

  As the inorganic pigment, in addition to titanium oxide and iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, it was produced by a known method such as a contact method, a furnace method, a thermal method, or the like. Carbon black can be used.

  Examples of the organic pigment include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments), polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, Dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinofullerone pigments, etc.), dye chelates (for example, basic dye chelate, acid dye chelate, etc.), nitro pigments, nitroso pigments, aniline black, and the like can be used. Of these pigments, those having good affinity with water are particularly preferably used.

  Specific examples of pigments preferably used in the inkjet ink of the present embodiment include black for carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, and channel black, or Examples thereof include metals such as copper, iron (CI Pigment Black 11) and titanium oxide, and organic pigments such as aniline black (CI Pigment Black 1).

  For color, 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 , 408, 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, 15: 1, 15: 2, 15: 3 (phthalocyanine blue), 16, 17: 1, 56, 60, 63, C.I. I. Pigment green 1, 4, 7, 8, 10, 17, 18, 36, and the like.

The following first and second forms are particularly preferred when the water-dispersible colorant is a pigment.
1) In the first embodiment, the water-dispersible colorant has at least one hydrophilic group on the surface and can be self-dispersed in aqueous ink in the absence of the dispersant (hereinafter referred to as “self-dispersible pigment”). It may be referred to as “)”.
2) In the second embodiment, the water-dispersible colorant contains a polymer emulsion (an aqueous dispersion of a pigment coated with a resin) in which polymer fine particles contain a colorant that is insoluble or hardly soluble in water.

  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. In the surface modification, a specific functional group (a functional group such as a sulfone group or a carboxyl group) is chemically bonded to the surface of the pigment, or at least one of hypohalous acid and a salt thereof is used. A method such as wet oxidation is used.

For example, as the self-dispersing carbon black, those having ionicity are preferable, and those having an anionic charge or those charged in a cationic form are suitable. Examples of the anionic hydrophilic group include —COOM, —SO ₃ M, —PO ₃ HM, —PO ₃ M ₂ , —SO ₂ NH ₂ , —SO ₂ NHCOR (where M is a hydrogen atom, an alkali metal) And 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. Among these, the self-dispersing pigment in which —COOM is bonded to the surface of the pigment and dispersed in water not only improves the dispersion stability, but also provides high-quality printing quality and recording after printing. The water resistance of media is improved.

  Further, “M” in the hydrophilic group includes, for example, lithium, sodium, potassium and the like as an alkali metal. Examples of the organic ammonium include mono to trimethyl ammonium, mono to triethyl ammonium, and mono to trimethanol ammonium. As a method of obtaining the anionically charged color pigment, as a method of introducing —COONa to the color pigment surface, for example, a method of oxidizing the color pigment with sodium hypochlorite, a method of sulfonation, a diazonium salt The method of making it react is mentioned.

  As the cationic hydrophilic group, for example, a quaternary ammonium group is preferable, and those bonded to the carbon black surface are preferable.

The volume average particle size (D ₅₀ ) of the self-dispersing pigment is preferably 0.01 to 0.16 μm in the ink.

  As the pigment coated with the resin of the second 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, and polyurethane polymers. The polymer that is preferably used is a water-insoluble vinyl polymer described later.

  The content of the water-dispersible colorant in the inkjet ink is preferably 2 to 15% by mass, more preferably 3 to 10% by mass, and still more preferably 4 to 8% 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, and if it exceeds 15% by mass, the ink may be thickened and the ejection stability may be reduced. .

<Water-insoluble vinyl polymer>
Next, the water-insoluble vinyl polymer will be described in detail. The water-insoluble vinyl polymer includes (A) a monomer represented by the general formula (I) [monomer (A)], (B) a salt-forming group-containing monomer [monomer (B)], (C) a hydrophobic monomer [monomer ( It is obtained by polymerizing a monomer mixture containing C)]. These monomers may be mixed with the required amount of each monomer, if necessary, and other than the monomers (A), (B), and (C) within the scope of solving the problems of the present invention. These monomers can be additionally used.

  The monomer (A) is represented by the general formula (I). By using the monomer (A), there is an advantage that a water-based ink having a high printing density and excellent storage stability can be obtained. The terminal alkyl group of the monomer (A) has an effect of facilitating the retention of the colorant on the paper surface and imparts excellent dispersion stability to the water-based ink.

In addition, since the monomer (A) is highly compatible with a specific water-soluble organic solvent, when the specific water-soluble organic solvent is contained in the ink, the water evaporates and reaches an equilibrium state. Even in the remaining ink, dispersion stability can be imparted to the polymer particles.
Formula (VI)

In general formula (VI), R ₁ is preferably a hydrogen atom or a methyl group from the viewpoint of polymerizability. R ₂ is an alkylene group having 2 to 8 carbon atoms or an alkylene group having 2 to 4 carbon atoms in which a hydrogen atom is substituted with a phenyl group, and an ethylene group, propylene group or butylene group having 2 to 4 carbon atoms is preferable. n is an average added mole number, and is a number of 2 to 30, but from the viewpoint of printing density and storage stability, a number of 2 to 25 is preferable, a number of 2 to 15 is more preferable, and 2 to 10 is preferable. Numbers are particularly preferred. The n R _{2 s} may be the same or different, and when they are different, either block addition or random addition may be used. R ₃ is a linear or branched alkyl group having 2 to 30 carbon atoms, but an alkyl group having 2 to 22 carbon atoms is preferred from the viewpoint of high printing density and good storage stability, and has 8 to 18 carbon atoms. An alkyl group is more preferable, and an octyl group, a 2-ethylhexyl group, a decyl group, a dodecyl (lauryl) group, a tetradodecyl (myristyl) group, a hexadecyl (cetyl) group, and an octadecyl (stearyl) group are particularly preferable.

  As the monomer (A), octoxypolyethylene glycol mono (meth) acrylate, octoxypoly (ethylene glycol / propylene glycol) mono (meth) acrylate, octoxypoly (ethylene glycol / butylene glycol) mono (meth) acrylate, lauroxypolyethylene glycol ( And (meth) acrylate, lauroxy poly (ethylene glycol / propylene glycol) mono (meth) acrylate, stearoxy polyethylene glycol mono (meth) acrylate, stearoxy poly (ethylene glycol / propylene glycol) mono (meth) acrylate, and the like. These can be used alone or in admixture of two or more.

  The monomer (A) is obtained by a method in which an aliphatic alcohol terminal (—OH) is polymerized with an alkylene oxide and the polymerized terminal group (—OH) is etherified. Specific examples of the monomer (A) that can be obtained commercially include Light Acrylate EA-C manufactured by Kyoeisha Chemical Co., Ltd., 50POEP-800B, PLE200, and PSE-400 manufactured by NOF Corporation.

  The content of the monomer (A) in the monomer mixture used for polymerizing the water-insoluble vinyl polymer is 3 to 25% by mass, preferably 5 to 20% by mass, from the viewpoint of printing density and ink viscosity.

  As the monomer (B), a salt-forming group-containing monomer is used. In this embodiment, the salt-forming group monomer refers to a monomer having a salt-forming group that forms a salt by a neutralization reaction. Examples of the salt-forming group-containing monomer suitably used in the present embodiment include an anionic monomer having an anion-generating group. This anion-generating group generates anions in water and imparts dispersion stability to the polymer dispersion by electrostatic repulsion, and when the ink lands on the recording medium, it loses electrostatic repulsive force due to pH change, Promotes pigment fixation. An anionic monomer can be used individually or in mixture of 2 or more types.

  Examples of the anionic monomer include one or more selected from an unsaturated carboxylic acid monomer, an unsaturated sulfonic acid monomer, and an unsaturated phosphoric acid monomer.

  Examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, and 2-methacryloyloxymethyl succinic acid. These can be used alone or in admixture of two or more.

  Examples of the unsaturated sulfonic acid monomer include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) acrylic acid ester, bis- (3-sulfopropyl) -itaconic acid ester, and the like. . These can be used alone or in admixture of two or more.

  Examples of unsaturated phosphoric acid monomers include vinylphosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxy Examples thereof include ethyl phosphate. These can be used alone or in admixture of two or more.

  Among the anionic monomers, unsaturated carboxylic acid monomers are preferable, and acrylic acid and methacrylic acid are more preferable from the viewpoint of printing density and storage stability.

  The content of the monomer (B) in the monomer mixture used for polymerizing the water-insoluble vinyl polymer is 3 to 25% by mass, preferably 5 to 20% by mass, more preferably from the viewpoint of printing density and storage stability. Is 12-14% by mass. When the content of the monomer (B) is less than 3% by mass, there is a problem that it is difficult to dissolve in the basic substance and it is difficult to coat the pigment.

As the monomer (C), a hydrophobic monomer is used in order to impart water resistance to the recorded matter. As the monomer (C) suitably used in the present embodiment, (C-1) a monomer represented by the general formula (VII), (C-2) a monomer represented by the general formula (VIII), (C -3) Macromers are mentioned.
Formula (VII)

（式中、Ｒ_４は水素原子又はメチル基、Ｒ_５は炭素数１〜２２のアルキル基、炭素数６〜２２のアリール基、アルキルアリール基若しくはアリールアルキル基又は炭素数３〜２２の環式炭化水素基を示す。）
一般式（ＶＩＩＩ）

Wherein R ₄ is a hydrogen atom or a methyl group, R ₅ is an alkyl group having 1 to 22 carbon atoms, an aryl group having 6 to 22 carbon atoms, an alkylaryl group or an arylalkyl group, or a cyclic group having 3 to 22 carbon atoms. Indicates a hydrocarbon group.)
Formula (VIII)

（式中、Ｒ_６は水素原子又はメチル基、Ｒ_７は置換基を有しても良いフェニル基、ビフェニル基、又はナフタレン基を示す。）

(In the formula, R ₆ represents a hydrogen atom or a methyl group, and R ₇ represents an optionally substituted phenyl group, biphenyl group, or naphthalene group.)

  These can be used alone or in admixture of two or more. The monomer (C) preferably contains at least one selected from (C-2) an aromatic ring-containing monomer and (C-3) a macromer from the viewpoint of printing density and scratch resistance.

As the monomer having an alkyl group of (C-1), a monomer in which R ₄ is a methyl group is preferable, and methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, (iso or tertiary) ) Butyl (meth) acrylate, (iso) amyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) decyl (meth) acrylate, (iso) dodecyl (meth) acrylate , (Iso) stearyl (meth) acrylate, behenyl (meth) acrylate and the like (meth) acrylate in which the ester moiety is an alkyl group having 1 to 22 carbon atoms. These can be used in combination of two or more. In addition, said (iso or tertiary) and (iso) mean both the case where these groups exist, and the case where it is not so, and when these groups do not exist, it shows normal. (Meth) acrylate means both methacrylate and acrylate. The same applies to the following. Examples of the monomer (C-1) having an aryl group include benzyl (meth) acrylate and phenoxyethyl (meth) acrylate. These can be used alone or in admixture of two or more.

  The monomer having a cyclic hydrocarbon group (C-1) is a monocyclic, bicyclic or tricyclic or higher polycyclic (meth) acrylate having 3 or more carbon atoms. Specifically, as monocyclic (meth) acrylate having 3 or more carbon atoms, cyclopropyl (meth) acrylate, cyclobutyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) Examples include acrylate, cyclooctyl (meth) acrylate, cyclononyl (meth) acrylate, and cyclodecyl (meth) acrylate, and examples of bicyclic (meth) acrylate include isobornyl (meth) acrylate and norbornyl (meth) acrylate. Examples of the tricyclic (meth) acrylate include adamantyl (meth) acrylate. Among these, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, and adamantyl (meth) acrylate are preferable from the viewpoint of storage stability. These can be used in combination of two or more.

As the aromatic ring-containing monomer of (C-2), a monomer in which R ₆ is hydrogen or a methyl group is preferable. From the viewpoint of water resistance, styrene, vinyl naphthalene, α-methylstyrene, vinyl toluene, ethyl vinyl benzene, 4- One or more selected from vinylbiphenyl is preferred. Among these, one or more selected from styrene, α-methylstyrene, vinyltoluene, and vinylnaphthalene are more preferable from the viewpoint of print density and scratch resistance.

  As the macromer of (C-3), a macromer having a polymerizable functional group at one end and preferably having a number average molecular weight of 400 to 500,000, more preferably 600 to 12,000.

  Specific examples of the macromer include a styrene macromer having a polymerizable functional group at one end, a silicone macromer having a polymerizable functional group at one end, a methyl methacrylate macromer having a polymerizable functional group at one end, Examples thereof include a styrene / acrylonitrile macromer having a polymerizable functional group, a butyl acrylate macromer having a polymerizable functional group at one end, and an isobutyl methacrylate macromer having a polymerizable functional group at one end. In these, since formation of the water-insoluble vinyl polymer particle containing a coloring agent is easy, the styrenic macromer which has a polymerizable functional group in one terminal is preferable.

  Examples of the styrenic macromer having a polymerizable functional group at one end include styrene homopolymers having a polymerizable functional group at one end, and copolymers of styrene having a polymerizable functional group at one end and other monomers. Can be mentioned. Among the styrenic macromers having a polymerizable functional group at one end, a styrenic macromer having an acryloyloxy group or a methacryloyloxy group as a polymerizable functional group at one end is preferable from the viewpoint of dispersibility.

  Examples of commercially available styrenic macromers include AS-6 (S), AN-6 (S), HS-6 (S) manufactured by Toa Gosei Co., Ltd., and the like. The number average molecular weight of the macromer is measured using polystyrene as a standard substance by gel chromatography using 1 mmol / L dodecyldimethylamine-containing chloroform as a solvent.

  The content of the monomer (C) in the monomer mixture used for polymerizing the water-insoluble vinyl polymer is 50 to 95% by mass, preferably 60 to 85% by mass, from the viewpoint of storage stability and water resistance.

  When the aromatic ring-containing monomer (C-2) is used as the monomer (C), the content of the aromatic ring-containing monomer in the monomer (C) is the same as that in the monomer mixture used for polymerizing the water-insoluble vinyl polymer. The content of the aromatic ring-containing monomer is preferably 30 to 80% by mass, more preferably 35 to 75% by mass, from the viewpoint of scratch resistance and ink viscosity.

  When the macromer of (C-3) is used as the monomer (C), the content of the macromer in the monomer (C) is preferably 3 to 40% by mass, more preferably from the viewpoint of water resistance and scratch resistance. Is 5 to 25% by mass.

  The weight average molecular weight of the water-insoluble vinyl polymer (measured by the method described in the production example described later) is preferably 3,000 to 300,000, more preferably 5,000 to 200, from the viewpoints of print density and ejection stability. , 000.

  The water-insoluble vinyl polymer is produced by polymerizing the monomers (A), (B), and (C) by a known polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method. . Among these polymerization methods, the solution polymerization method is preferable. The solvent used in the solution polymerization method is preferably a polar organic solvent. When the polar organic solvent is miscible with water, it can be used by mixing with water. Examples of the polar organic solvent include aliphatic alcohols having 1 to 3 carbon atoms such as methanol, ethanol and propanol; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate and the like. Among these, methanol, ethanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, or a mixed solution of these with water is preferable. If necessary, toluene may be used.

  In the polymerization, a radical polymerization initiator can be used. As radical polymerization initiators, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl-2,2′-azobisbutyrate, 2,2 An azo compound such as' -azobis (2-methylbutyronitrile) and 1,1'-azobis (1-cyclohexanecarbonitrile) is preferred. Moreover, organic peroxides, such as t-butyl peroxy octoate, di-t-butyl peroxide, dibenzoyl oxide, can also be used. The amount of the polymerization initiator is preferably 0.001 to 5 mol, more preferably 0.01 to 2 mol, per mol of the monomer mixture.

  In the polymerization, a polymerization chain transfer agent may be further added. Specific examples of the polymerization chain transfer agent include mercaptans such as octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-tetradecyl mercaptan and 2-mercaptoethanol; xanthogen disulfides such as dimethylxanthogen disulfide and diisopropylxanthogen disulfide. ; Thiuram disulfides such as tetramethylthiuram disulfide and tetrabutylthiuram disulfide; halogenated hydrocarbons such as carbon tetrachloride and ethylene bromide; hydrocarbons such as pentaphenylethane; acrolein, methacrolein, allyl alcohol, 2- Ethylhexyl thioglycolate, terbinolene, α-terpinene, γ-terpinene, dipentene, α-methylstyrene dimer, 9,10-dihydroanthracene, 4-dihydronaphthalene, indene, 1,4-cyclohexadiene unsaturated cyclic hydrocarbon compounds of a diene and the like; 2,5-unsaturated heterocyclic compounds dihydrofuran like, and the like. These polymerization chain transfer agents can be used alone or in admixture of two or more.

  Since the polymerization conditions of the monomer vary depending on the radical polymerization initiator, the monomer, the type of the solvent, and the like, it cannot be determined unconditionally. Usually, the polymerization temperature is preferably 30 to 100 ° C., more preferably 50 to 85 ° C., and the polymerization time is preferably 2 to 24 hours. The polymerization atmosphere is preferably an inert gas atmosphere such as nitrogen gas.

  After completion of the polymerization reaction, the produced water-insoluble vinyl polymer can be isolated from the reaction solution by a known method such as reprecipitation or solvent distillation. The obtained water-insoluble vinyl polymer can be purified by repeating reprecipitation or removing unreacted monomers by membrane separation, chromatographic methods, extraction methods, and the like.

<Aqueous dispersion of pigment coated with water-insoluble vinyl polymer>
As a method of obtaining an aqueous dispersion of a pigment coated with the water-insoluble vinyl polymer as the water-dispersible colorant, the water-insoluble vinyl polymer is dissolved in an organic solvent, and the pigment, water, neutralizing agent, and necessary According to the method, after adding a surfactant and kneading, it is preferable to dilute with water if necessary and distill off the organic solvent to make an aqueous system.

  The amount of the pigment is preferably 20 to 1200 parts by weight, more preferably 50 to 900 parts by weight with respect to 100 parts by weight of the water-insoluble vinyl polymer, from the viewpoint of printing density and ease of inclusion in the water-insoluble vinyl polymer particles. Parts, more preferably 65 to 600 parts by mass.

  As the organic solvent, alcohol solvents, ketone solvents and ether solvents are preferable, and hydrophilic organic solvents among these are more preferable. Examples of the alcohol solvent include isopropanol, n-butanol, tertiary butanol, isobutanol, diacetone alcohol and the like. Examples of the ketone solvent include acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone. Examples of the ether solvent include dibutyl ether, tetrahydrofuran, dioxane and the like. Among these solvents, acetone, methyl ethyl ketone, and methyl isobutyl ketone are preferable, and toluene may be used in combination as necessary.

  A base is used as the neutralizing agent, and specific examples include tertiary amines such as trimethylamine and triethylamine, ammonia, sodium hydroxide, potassium hydroxide and the like. There is no particular limitation on the degree of neutralization. Usually, it is preferable that the obtained aqueous dispersion has neutral liquidity, for example, pH of 4 to 10.

  Depending on the type of the salt-forming group, the solubility of the water-insoluble vinyl polymer in water at 25 ° C. after neutralizing the salt-forming group with sodium hydroxide or acetic acid to 100% is the low viscosity of the water-based ink. 10 mass% or less is preferable from a viewpoint, 5 mass% or less is more preferable, and it is still more preferable that it is 1 mass% or less.

  The average particle size of the water-insoluble vinyl polymer particles containing the colorant in the aqueous dispersion and the water-based ink of the present embodiment is preferably 0.01 to 0.00 from the viewpoint of prevention of nozzle clogging and storage stability. The thickness is 50 μm, more preferably 0.02 to 0.30 μm, still more preferably 0.04 to 0.20 μm.

<Water-soluble organic solvent>
Examples of the water-soluble organic solvent used in this embodiment include polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds. , Propylene carbonate, and ethylene carbonate.

  The water-soluble organic solvent of the present embodiment is compatible with water-dispersible colorants, in particular, water-insoluble vinyl polymer particles containing a pigment, so that even when the ink moisture is evaporated for a long period of time, the pigment Prevents aggregation and imparts excellent storage stability. Further, the water-soluble organic solvent of the present embodiment imparts fluidity of the ink by the water-soluble organic solvent retaining a large amount of moisture even when the ink is left open.

  In this embodiment, it is desirable that the viscosity of the ink residue left until the mass change substantially disappears in an environment of temperature 25 ° C. and humidity 15% is 3000 mPa · s or less, using a water-soluble organic solvent, An example of a method for prescribing ink having such characteristics will be described. First, by using a water-soluble organic solvent with a high equilibrium moisture content, even when the ink moisture evaporates and reaches an equilibrium state, the water-soluble organic solvent retains a large amount of moisture, causing an extreme increase in ink viscosity. Can be suppressed.

In the present embodiment, the water-soluble organic solvent having a high equilibrium water content refers to a water-soluble organic solvent having an equilibrium water content in an environment of a temperature of 23 ° C. and a humidity of 80% of 30 wt% or more, preferably 40 wt% or more ( Hereinafter referred to as water-soluble organic solvent A). By using such a water-soluble organic solvent A, the water-soluble organic solvent A can retain a large amount of water and prevent an increase in viscosity even when the water content of the ink evaporates and reaches a water balance. Equilibrium water content means that a mixture of water-soluble organic solvent and water is opened to air at a constant temperature and humidity, and the evaporation of water in the solution and the absorption of water in the ink into the ink are in an equilibrium state. Says the amount of water when it becomes. Specifically, the equilibrium water content is determined by using a saturated aqueous solution of potassium chloride, keeping the temperature and humidity in the desiccator at 23 ± 1 ° C. and 80 ± 3%, and weighing 1 g of each water-soluble organic solvent in the desiccator. The petri dish can be stored for a period until the mass change disappears, and can be obtained by the following formula.
Equilibrium water content (%) = {water content absorbed in water-soluble organic solvent / (water-soluble organic solvent amount + water content absorbed in water-soluble organic solvent)} × 100

  The boiling point of the water-soluble organic solvent A is preferably 140 ° C. or higher, more preferably 250 ° C. or higher. If the boiling point of the water-soluble organic solvent A is 140 ° C. or higher, vaporization does not occur in a normal ink use environment, so that it is possible to prevent a decrease in water that can be retained by vaporization of the water-soluble organic solvent.

  In addition, in the ink of this embodiment, in order to formulate the viscosity of the ink residue left until the mass change substantially disappears in a temperature of 25 ° C. and a humidity of 15% environment to be 3000 mPa · s or less, a pigment is used. It is also necessary to consider the affinity between the water-insoluble vinyl polymer particles contained and the water-soluble organic solvent. In general, an ink containing an aqueous dispersion of polymer particles loses dispersion stability and aggregates due to evaporation of water. However, when there is a water-soluble organic solvent that has a high affinity for water-insoluble vinyl polymer particle dispersions containing pigments, the dispersion maintains dispersibility even in a solution in which moisture has evaporated, and has an abrupt viscosity. The rise can be prevented. More specifically, when a vinyl polymer containing the monomers (A), (B), and (C) is used as the polymer particles, the polymer particles become polyhydric alcohols when polyhydric alcohols are used as the water-soluble organic solvent. It is possible to suppress an increase in the viscosity of the ink that is compatible with the water and has evaporated water.

  From the above points, examples of the water-soluble organic solvent A preferably used in the present embodiment include polyhydric alcohols having an equilibrium water content in an environment of a temperature of 23 ° C. and a humidity of 80% of 30 wt% or more. Specific examples of such water-soluble organic solvent A 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 wt%), 1,3-butanediol (bp 203-204 ° C, 35 wt%) and the like. Among these, glycerin and 1,3-butanediol are particularly preferably used for reasons such as lowering the viscosity when water is contained, and keeping the pigment dispersion stable without aggregation. When the water-soluble organic solvent A is used in an amount of 50 wt% or more of the total amount of the water-soluble organic solvent agent, it is preferable because it is excellent in securing ejection stability and preventing waste ink sticking in a maintenance device of the ink ejection device.

  In addition to the water-soluble organic solvent A, the ink-jet ink of the present embodiment is replaced with a part of the water-soluble organic solvent A or in addition to the water-soluble organic solvent A as necessary. A water-soluble organic solvent (hereinafter referred to as water-soluble organic solvent B) having an equilibrium water content at 80% of less than 30 wt% can be used in combination. Examples of such water-soluble organic solvents B include polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, sulfur-containing compounds, propylene. And carbonate, ethylene carbonate, other wetting agents, and the like.

  Specific examples of the polyhydric alcohols of the water-soluble organic solvent B include, for example, dipropylene glycol (bp 232 ° C), 1,5-pentanediol (bp 242 ° C), 3-methyl-1,3-butanediol (bp 203 ° C). ), Propylene glycol (bp 187 ° C.), 2-methyl-2,4-pentanediol (bp 197 ° C.), ethylene glycol (bp 196-198 ° C.), tripropylene glycol (bp 267 ° C.), hexylene glycol (bp 197 ° C.), polyethylene Glycol (viscous liquid to solid), polypropylene glycol (bp 187 ° C), 1,6-hexanediol (bp253-260 ° C), 1,2,6-hexanetriol (bp178 ° C), trimethylolethane (solid, mp199- 201 ° C), trimethylolpropane Solid, MP61 ° C.), and the like.

  Examples of the polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether (bp 135 ° C.), ethylene glycol monobutyl ether (bp 171 ° C.), diethylene glycol monomethyl ether (bp 194 ° C.), diethylene glycol monoethyl ether (bp 197 ° C.), and diethylene glycol monoethyl ether. Examples include butyl ether (bp 231 ° C.), ethylene glycol mono-2-ethylhexyl ether (bp 229 ° C.), propylene glycol monoethyl ether (bp 132 ° C.), and the like. Examples of the polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether (bp 237 ° C.) and ethylene glycol monobenzyl ether.

  Examples of the nitrogen-containing heterocyclic compound include 2-pyrrolidone (bp 250 ° C., mp 25.5 ° C., 47-48 wt%), N-methyl-2-pyrrolidone (bp 202 ° C.), 1,3-dimethyl-2-imidazo Lydinone (bp 226 ° C.), ε-caprolactam (bp 270 ° C.), γ-butyrolactone (bp 204-205 ° C.) and the like can be mentioned. Examples of the amides include formamide (bp 210 ° C.), N-methylformamide (bp 199-201 ° C.), N, N-dimethylformamide (bp 153 ° C.), N, N-diethylformamide (bp 176-177 ° C.), and the like. Can be mentioned. Examples of the amines include monoethanolamine (bp 170 ° C), diethanolamine (bp268 ° C), triethanolamine (bp360 ° C), N, N-dimethylmonoethanolamine (bp139 ° C), N-methyldiethanolamine (bp243 ° C). ), N-methylethanolamine (bp159 ° C.), N-phenylethanolamine (bp282-287 ° C), 3-aminopropyldiethylamine (bp169 ° C), and the like. Examples of the sulfur-containing compounds include dimethyl sulfoxide (bp 139 ° C.), sulfolane (bp 285 ° C.), thiodiglycol (bp 282 ° C.), and the like. Other solid wetting agents are preferably sugars.

Examples of the saccharide include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides), polysaccharides, and the like. Specific examples include glucose, mannose, fructose, ribose, xylose, arabinose, galactose, maltose, cellobiose, lactose, sucrose, trehalose, maltotriose, and the like. Here, the polysaccharide means a saccharide in a broad sense, and is used to include a substance that exists widely in nature such as α-cyclodextrin and cellulose. The derivatives of these saccharides are represented by the reducing sugars of the saccharides described above (for example, sugar alcohol (general formula: HOCH ₂ (CHOH) _n CH ₂ OH (where n represents an integer of 2 to 5)). ), Oxidized sugars (for example, aldonic acid, uronic acid, etc.), amino acids, thioic acids, etc. Among these, sugar alcohols are preferable, and specific examples include maltitol, sorbit, and the like.

  The mass ratio between the water-insoluble vinyl polymer particles containing the pigment and the water-soluble organic solvent A has a great influence on the stability of ink ejection from the head, and further prevents waste ink sticking in the maintenance device of the inkjet recording apparatus. Also has an effect. If the water-insoluble vinyl polymer particles containing the pigment have a high solid content and the blending amount of the water-soluble organic solvent A is small, water evaporation near the ink meniscus of the nozzle may progress and cause ejection failure. The mass ratio of the water-insoluble vinyl polymer particles containing the pigment and the water-soluble organic solvent A is preferably 1: 2 to 1:10, more preferably 1: 3 to 1: 8. Here, the ratio of the mass of the water-insoluble vinyl polymer particles containing the pigment to the mass of water that the water-soluble organic solvent A can maintain at equilibrium (temperature 25 ° C., humidity 80%) is preferably 1: 0. 2 to 1: 7, and more preferably 1: 0.6 to 1: 4.

  The content of the water-soluble organic solvent in the inkjet ink is preferably 20 to 50% by mass, and more preferably 25 to 45% by mass. When the content is less than 25% by mass, the ejection stability is lowered, and the waste ink may be fixed by the maintenance device. 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.

<Penetration agent>
The inkjet ink of the present embodiment preferably contains at least one kind of a polyol compound having 8 to 11 carbon atoms or a glycol ether compound having 8 to 11 carbon atoms as a penetrant. The penetrating agent is different from the water-soluble organic solvent and is not free from wettability at all. However, since it is relatively less than the water-soluble organic solvent, it can be said to be non-wetting agent. Here, the non-wetting agent property means having a solubility of between 0.2 and 5.0% by mass in water at 25 ° C. Among these penetrants, 2-ethyl-1,3-hexanediol [solubility: 4.2% (25 ° C.)], 2,2,4-trimethyl-1,3-pentanediol [solubility: 2.0 % (25 ° C.)] is particularly preferably used. These penetrants are preferable in that they have good compatibility with the water-insoluble vinyl polymer obtained by polymerizing the monomers (A), (B), and (C) and do not cause an increase in the viscosity of the ink residue from which water has evaporated.

  As other polyol compounds, as aliphatic diols, for example, 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 the like can be mentioned.

  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 Examples thereof include alkyl and aryl ethers of polyhydric alcohols such as glycol monoallyl ether, propylene glycol monobutyl ether and tetraethylene glycol chlorophenyl ether, and lower alcohols such as ethanol.

  The content of the penetrant in the ink-jet ink is preferably 0.1 to 4.0% by mass. When the content is less than 0.1% by mass, quick-drying may not be obtained and a blurred image may be obtained. When the content exceeds 4.0% by mass, the dispersion stability of the colorant is impaired, and the nozzle In some cases, clogging is likely to occur, and the permeability to the recording medium is unnecessarily high, resulting in a decrease in image density and through-through.

<PH adjuster>
The pH adjuster is not particularly limited as long as the pH can be adjusted to 8 to 11 without adversely affecting the ink-jet ink to be prepared, and can be appropriately selected according to the purpose. Examples include alcohol amines, alkali metal hydroxides, ammonium hydroxides, phosphonium hydroxides, alkali metal carbonates, and the like. When the pH is less than 8 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, quaternary ammonium hydroxide, quaternary phosphonium hydroxide, and the like. Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, and potassium carbonate.

  Since the ink of this embodiment has a high pH dependency of the viscosity, a pH adjuster is added as a pigment aggregation preventing agent, and is adjusted so that the ink pH is not lowered and the pigment is not aggregated or thickened during ink storage. Thus, a highly reliable ink can be obtained.

<Other ingredients>
The other components are not particularly limited and can be appropriately selected as necessary.For example, water-dispersible resins, antiseptic / antifungal agents, chelating reagents, rust preventives, antioxidants, ultraviolet absorbers, Examples include oxygen absorbers and light stabilizers.

  The water-dispersible resin has excellent film-forming properties (image formability), high water repellency, high water resistance, and high weather resistance, and has high water resistance and high image density (high color development). Useful for. Specific examples of the water dispersibility include condensed synthetic resins, addition 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.

  The average particle size (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 size decreases. The average particle diameter (D50) of the water-dispersible resin is preferably 50 nm or more so that the ink does not have an excessively high viscosity. 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. If particles having a large particle diameter are present in the ink even though they are smaller than the nozzle opening, the ejection stability is deteriorated. Therefore, the average particle diameter (D50) is more preferably 200 nm or less, and even more preferably 150 nm or less, in order not to inhibit the ink ejection stability.

  The water-dispersible resin has a function of fixing the water-dispersed colorant on the paper surface, and is preferably formed into a film at room temperature to improve the fixability of the color material. Therefore, it is preferable that the minimum film-forming temperature (MFT) of the water-dispersible resin is 30 ° C. or less. Further, when the glass transition temperature of the water-dispersible resin is -40 ° C. or lower, the resin film becomes more viscous and the printed matter is tacky. Therefore, the water-dispersible resin has a glass transition temperature of −30 ° C. or higher. It is preferable.

  The content of the water-dispersible resin in the inkjet ink is preferably 1 to 15% by mass, more preferably 2 to 7% by mass in terms of solid content. Here, the solid content of the colorant, the pigment in the colorant, and the water-dispersible resin is measured by, for example, a method of separating only the water-dispersible colorant and the water-dispersible resin component from the ink. be able to. When a pigment is used as the water-dispersible colorant, the ratio of the water-dispersible colorant to the water-dispersible resin can be measured by evaluating the mass reduction rate by thermal mass spectrometry. If the molecular structure of the water-dispersible colorant is clear, the solid content of the water-dispersible colorant can be quantified using NMR for pigments and dyes, and it is contained in heavy metal atoms and molecular skeletons. For inorganic pigments, metal-containing organic pigments, and metal-containing dyes, the solid content of the water-dispersible colorant can be quantified by using fluorescent X-ray analysis.

  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 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.

<Inkjet ink manufacturing method>
The ink-jet ink of this embodiment comprises a water-dispersible colorant, a water-soluble organic solvent, a fluorosurfactant, a foam suppressor of general formula (I), water, and other components in an aqueous medium as necessary. In this case, it is dispersed or dissolved, and if necessary, stirred and mixed. The dispersion can be performed by, for example, a sand mill, a homogenizer, a ball mill, a paint shaker, an ultrasonic disperser, etc., and stirring and mixing are performed by a stirrer using a normal stirring blade, a magnetic stirrer, a high-speed disperser, or the like. be able to.

<Inkjet ink properties>
There is no restriction | limiting in particular as a physical property of the inkjet ink of this embodiment, According to the objective, it can select suitably, For example, it is preferable that a viscosity, surface tension, pH, etc. are the following ranges.

  The viscosity of the inkjet ink at 25 ° C. is preferably 5 to 20 mPa · s. By setting the viscosity of the inkjet ink to 5 mPa · s or more, an effect of improving the printing density and the character quality can be obtained. On the other hand, by suppressing the viscosity of the inkjet ink to 20 mPa · s or less, ejection stability can be ensured. In the present embodiment, the viscosity of the inkjet ink is a viscosity measured by a conical plate type rotational viscometer according to JIS K7117-2. The viscosity can be measured at 25 ° C. using, for example, a viscometer (RE-80L, RE-550L, manufactured by Toki Sangyo Co., Ltd.).

  The ink for ink jet of this embodiment usually has a water content of more than 50 wt%, and the total amount of resin and pigment is usually more than 3 wt%. Therefore, the solvent evaporation rate is usually 50 to 97 wt%.

  Further, the viscosity of the ink residue that is allowed to stand until the mass of the ink-jet ink remains substantially unchanged at a temperature of 25 ° C. and a humidity of 15% is preferably 3000 mPa · s or less, more preferably 2500 mPa · s or less. . When the viscosity of the ink residue is larger than 3000 mPa · s, there is a possibility that the ink residue from which moisture has evaporated adheres to the maintenance mechanism of the ink jet recording apparatus.

  In the present invention, the method for leaving the ink-jet ink under a temperature of 25 ° C. and a humidity of 15% until the mass change is substantially eliminated is as follows. Using a commercially available thermo-hygrostat capable of controlling temperature and humidity, the volatile components of the ink-jet ink are volatilized at a temperature of 25 ° C. and a humidity of 15%, and the mass of the ink-jet ink every hour. The sample is left until the mass change is substantially eliminated. Here, the fact that there is substantially no change in mass means that the change in the evaporation rate of volatile components per hour reaches 1% or less.

  The viscosity of an ink preparation prepared by adjusting the pH of the inkjet ink to 7 with an acid is preferably 500 mPa · s or more, more preferably 1000 mPa · s or more. When the viscosity of the ink preparation is less than 500 Pa · s, the pigment hardly stays on the paper surface, and the image density and saturation may be lowered. The average particle diameter (D50) of the ink preparation obtained by adjusting the pH of the inkjet ink to 7 with an acid is 5 times or more, more preferably 10 times or more than the average ink particle diameter (D50) before adjustment. More preferably, it is 30 times or more. When the average particle diameter (D50) of the ink adjustment product is smaller than 5 times the average particle diameter (D50) of the ink before adjustment, the pigment hardly stays on the paper surface and the color development improvement effect may be reduced.

  Here, the adjustment of the ink with the acid is performed by dropping 1N hydrochloric acid while measuring the pH of the inkjet ink with a pH meter. By setting the viscosity of the ink preparation adjusted to pH 7 to 500 mPa or more, when the ink adheres to the surface of a recording medium having a pH of 7 or less, such as plain paper, the viscosity rapidly increases and the pigment remains on the paper surface. be able to. Here, the plain paper is different from a recording medium having an ink receiving layer on a base material such as an inkjet dedicated paper, and is a copy paper used in an office or the like that does not have the ink receiving layer. Say the paper. The paper surface pH of plain paper is usually 4-7.

  The pH of the inkjet ink is greater than 7, preferably 8 or more, more preferably 9 or more at 25 ° C. In order to improve the color development on plain paper, the water-insoluble vinyl polymer particles containing the pigment are agglomerated at a pH of 7 or less as a method of causing aggregation and thickening at the pH of plain paper and leaving the colorant component on the paper surface.・ Invented to increase viscosity. Therefore, the pH of the inkjet ink needs to be higher than 7. However, when the pH of the inkjet ink is increased to 11 or more, there is a side effect that the safety to the human body (skin irritation) and the deterioration of components used in the inkjet recording apparatus and the like are increased.

  The static surface tension of the ink-jet ink is preferably 30 mN / m or less at 25 ° C. When the static surface tension exceeds 30 mN / m, it is difficult for ink to permeate and level on the recording medium having low absorbability, and the drying time may be prolonged.

  There is no restriction | limiting in particular as coloring of the inkjet ink of this embodiment, 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 colorings are used in combination, a multicolor image can be formed. When recording is performed using an ink set in which all colors are combined, a full color image is formed. be able to.

  The ink-jet ink of the present embodiment is not only used in an ink-jet recording apparatus that performs recording and drying at room temperature, but also, for example, the recording paper and the ink are heated at 50 to 200 ° C. before and after printing or printing to fix the printing. It can also be used for an ink jet recording apparatus having a function of promoting the above. Furthermore, the ink-jet ink of the present embodiment can be particularly suitably used for the following ink cartridge, ink-jet recording method, ink-jet recording apparatus, and ink recorded matter of the present embodiment.

<Ink cartridge>
The ink cartridge of the present embodiment contains the ink-jet ink of the present invention in a container, and further includes other members and the like appropriately selected as necessary. The container is not particularly limited, and its shape, structure, size, material and the like can be appropriately selected according to the purpose. Preferred examples include those possessed.

  Next, the ink cartridge will be described with reference to FIGS. Here, FIG. 1 is a schematic diagram showing an ink cartridge of the present embodiment, and FIG. 2 is a schematic diagram showing a modification of the ink cartridge of FIG. As shown in FIG. 1, after the ink jet ink of the present invention is filled into the ink bag (241) from the ink injection port (242) and exhausted, the ink injection port (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 stabbed into an ink discharge port (243) made of a rubber member, and the 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) of the present embodiment contains the ink-jet ink of the present invention and can be used by being detachably attached to various ink-jet recording apparatuses, and is also detachably attached to an ink-jet recording apparatus described later. It is particularly preferable to use them.

<Inkjet recording method and inkjet recording apparatus>
The ink jet recording method of this embodiment 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 of this embodiment includes at least ink flying means, and further includes other means appropriately selected as necessary, for example, stimulus generation means, control means, and the like. The ink jet recording method of this embodiment can be preferably carried out by the ink jet recording apparatus of this embodiment, 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 step is a step of forming an image on a recording medium by applying a stimulus (energy) to the ink jet ink of the present invention and causing the ink jet ink to fly. The ink flying means is means for applying an stimulus (energy) to the inkjet ink of the present invention and causing the inkjet ink to fly to form an image on a recording medium. The ink flying means is not particularly limited, and examples thereof include various nozzles for ejecting ink.

  In this embodiment, it is preferable that at least a part of the liquid chamber portion, the fluid resistance portion, the vibration plate, and the nozzle member of the inkjet head is formed of a material containing at least one of silicone and nickel. The nozzle diameter of the inkjet nozzle is preferably 30 μm or less, and more preferably 1 to 20 μm.

  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. Heat (temperature), pressure, vibration and For example, light. These may be used individually by 1 type and may use 2 or more types together. Among these, heat and pressure are preferable.

  Here, an aspect of the serial type ink jet recording apparatus of the present embodiment will be described with reference to the drawings. The ink jet recording apparatus shown in FIG. 3 has an apparatus main body (101), a paper feed tray (102) for loading paper into the apparatus main body (101), and an image formed on the apparatus main body (101) ( A paper discharge tray (103) for stocking recorded paper and an ink cartridge loading unit (104) are provided. On the top surface of the ink cartridge loading unit (104), an operation unit (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 recording head (134) including four inkjet recording heads that eject recording 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 discharge direction is directed downward.

  As an inkjet recording head constituting the recording head (134), a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change caused by liquid film boiling using an electrothermal transducer such as a heating resistor, and a temperature change A shape memory alloy actuator using a metal phase change, an electrostatic actuator using an electrostatic force, or the like provided as energy generating means for discharging ink can be used.

  Here, a configuration example of the subsystem (91) including the maintenance device for the discharge device according to the present embodiment will be described with reference to FIG. FIG. 6 is an explanatory plan view of the main part of the system. A frame (maintenance device frame) (111) of this subsystem has two cap holders (112A) and (112B) as a cap holding mechanism and a wiper blade (a wiping member including an elastic body as a cleaning means). 93) and the carriage lock (115) are held so as to be movable up and down (movable up and down). An empty discharge receiver (94) is disposed between the wiper blade (93) and the cap holder (112A). In order to clean the wiper blade (93), the wiper blade ( A wiper cleaner, which is a cleaner means, includes a cleaner roller (96) that is a cleaning member for pressing 93) against the wiper cleaner side that is a cleaning member of the idle discharge receiver (94).

  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.

<Ink record>
The recorded matter recorded by the ink jet recording apparatus and the ink jet recording method of the present embodiment is the ink recorded matter of the present embodiment. The ink recorded matter of this embodiment has an image formed on the recording medium using the ink jet ink of this embodiment. The recording medium is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include plain paper, glossy paper, special paper, cloth, film, OHP sheet, and general-purpose printing paper. Particularly, it is suitably used for plain paper having a pH of 7 or less. These may be used individually by 1 type and may use 2 or more types together. The ink recorded matter has high image quality, no bleeding, excellent temporal stability, and can be suitably used for various purposes as a material on which various prints or images are recorded.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

<< Production Examples 1-6 >>
In a reaction vessel, 20 parts by mass of methyl ethyl ketone, 0.03 part by mass of a polymerization chain transfer agent (2-mercaptoethanol), and 10% by mass of each monomer (indicated by mass) shown in Table 1 are added and mixed. Then, nitrogen gas replacement was sufficiently performed to obtain a mixed solution.

  On the other hand, the remaining 90% by mass of each monomer (indicated by mass) shown in Table 1 was charged into a dropping funnel, then 0.27 parts by mass of a polymerization chain transfer agent (2-mercaptoethanol), and 60% by mass of methyl ethyl ketone. And 1.2 parts by mass of 2,2′-azobis (2,4-dimethylvaleronitrile) were mixed and mixed, and nitrogen gas substitution was sufficiently performed to obtain a mixed solution.

  Under a nitrogen atmosphere, the mixed solution in the reaction vessel was heated to 75 ° C. while stirring, and the mixed solution in the dropping funnel was gradually dropped into the reaction vessel over 3 hours. After completion of the dropwise addition, the liquid temperature of the mixed solution was maintained at 75 ° C. for 2 hours, and then a solution in which 0.3 part by mass of 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved in 5 parts by mass of methyl ethyl ketone was prepared. In addition to the mixed solution, the mixture was further aged at 75 ° C. for 2 hours and 85 ° C. for 2 hours to obtain a polymer solution.

  A portion of the resulting polymer solution was isolated by drying at 105 ° C. under reduced pressure for 2 hours and removing the solvent. The weight average molecular weight was measured by gel permeation chromatography using polystyrene as a standard substance and 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide-containing dimethylformamide as a solvent.

The details of each compound shown in Table 1 are as follows.
* Ethoxypolyethylene glycol monomethacrylate: a monomer in which n is 9, R ₁ is a methyl group, R ₂ is an ethylene group, and R ₃ is an ethyl group in general formula (I) * Octoxypolyethylene glycol monomethacrylate: general formula (I ) In which n is 6, R ₁ is a methyl group, R ₂ is an ethylene group, and R ₃ is an octyl group * Octoxypolyethylene glycol / polypropylene glycol monomethacrylate: In general formula (I), n is 6 (polyethylene) The average added mole number of glycol is 4, the average added mole number of polypropylene glycol is 2), R ₁ is methyl group, R ₂ is ethylene group and propylene group, R ₃ is octyl group, oxyethylene group and oxyethylene propylene Monomer randomly added to the group * Lauroxypolyethylene Glycol monomethacrylate: a monomer in which n is 4, R ₁ is a methyl group, R ₂ is an ethylene group, and R ₃ is a dodecyl group in general formula (I) * stearoxy polyethylene glycol monomethacrylate: in general formula (I) , N is 9, R ₁ is a methyl group, R ₂ is an ethylene group, and R ₃ is an octadecyl group * polyethylene glycol monomethacrylate: in general formula (I), n is 15, R ₁ is a methyl group, R ₂ Is a monomer in which R ₃ is a hydrogen atom * Methacrylic acid: manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name: GE-110 (MAA)
* 2-ethylhexyl methacrylate: manufactured by Mitsubishi Rayon Co., Ltd., trade name: acrylate EH
* Styrene monomer: manufactured by Nippon Steel Chemical Co., Ltd., trade name: styrene monomer * Styrene macromer: manufactured by Toa Gosei Co., Ltd., trade name: AS-6S (styrene macromer), number average molecular weight 6000

<< Adjustment Examples 1 to 7 >>
90 parts of methyl ethyl ketone and a neutralizing agent (5N aqueous sodium hydroxide solution) were added in a predetermined amount to 77 parts of a solution obtained by adjusting the polymers obtained in Production Examples 1 to 6 to 50% with methyl ethyl ketone to neutralize (neutralize) methacrylic acid. Then, 370 parts of ion-exchanged water and 90 parts of the pigment shown in Table 2 as a colorant were added, mixed with a disperser, and further treated with a disperser (Microfluidizer M-140K, 150 MPa) for 20 passes. In the case of using carbon black Nipex 150, the pass processing of the disperser was set to 5 passes.

  After adding 100 parts of ion-exchanged water to the obtained aqueous dispersion and stirring, methyl ethyl ketone was removed at 60 ° C. under reduced pressure, and a part of the water was further removed, and then a 5 μm filter [acetylcellulose membrane, outer Diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.] and filtered with a 25 mL needleless syringe (manufactured by Terumo Co., Ltd.) to remove coarse particles to obtain an aqueous dispersion (25% as solid content) ).

(Examples 1-5, 9 , Reference Examples 6-8 and Comparative Examples 1-12)
−Preparation of inkjet ink−
Each inkjet ink was manufactured according to the following procedure. First, in Table 3 and Table 4, a water-soluble organic solvent, penetrating agent, surfactant, fungicide, foam inhibitors, mixed a pH adjusting agent and water, were mixed uniformly for 1 hour. To this mixture, the pigment dispersion was added suds suppressors, and stirred for 1 hour. This dispersion was subjected to pressure filtration with a polyvinylidene fluoride membrane filter having an average pore diameter of 5.0 μm to remove coarse particles and dust, and Examples 1 to 5, 9 , Reference Examples 6 to 8 and Comparative Examples 1 to Twelve inkjet inks were prepared.

In addition, the unit in Table 3 and Table 4 is a mass part. Abbreviations in Table 3 and Table 4 represent the following meanings.
* Self-dispersed pigment dispersion 1: Cabot, CaboJet # 300, solid content 15% by mass * Self-dispersing pigment dispersion 2: Cabot, CaboJet # 260m, solid content 15% by mass
* Compound of general formula (III): Zonyl FS-300 polyoxyethylene perfluoroalkyl ether, wherein j is 6 to 8, and k is 26 or more (manufactured by Dupont, 40% by mass of active ingredient)
* Compound of general formula (IV) -I: wherein n = 4, m = 21, p = 4 and Rf = CF ₂ CF ₃ * Compound of general formula (V) -I: q = 6 And Rf = CF ₂ CF ₃ * Orphine EXP4001: Acetylene glycol surfactant, manufactured by Nissin Chemical Industry Co., Ltd., 80% by mass of active ingredient
* Softanol EP-7025: polyoxyalkylene alkyl ether (manufactured by Nippon Shokubai Co., Ltd., 100 mass% component)
* Proxel GXL: Antifungal agent based on 1,2-benzisothiazolin-3-one (Avicia, 20% by mass, containing dipropylene glycol)
* ANTIFORM 1266: Silicone-based antifoaming agent (manufactured by Toray Dow Corning Co., Ltd., 100 mass% component)
* BYK-1615: Silicone-based antifoaming agent (by Big Chemie Japan Co., Ltd., component 100% by mass)
* KM-72F: Self-emulsifying silicone defoaming agent (manufactured by Shin-Etsu Silicone Co., Ltd., 100% by mass)

Next, each ink-jet ink of Examples 1 to 5, 9 , Reference Examples 6 to 8 and Comparative Examples 1 to 12 was evaluated by the following evaluation method. The results are shown in Tables 5 to 7.

<Concentration of solid content>
The total content (mass%) of the pigment and the resin (coating resin or water-dispersible resin) in the ink was calculated.

<Viscosity>
The viscosity of the ink was measured at 25 ° C. using a viscometer (RE-550L, manufactured by Toki Sangyo Co., Ltd., cone rotor 1 ° 34 ′ × R24). Further, while measuring the pH of the ink with a pH meter HM-30R (manufactured by TOA-DKK), 1N hydrochloric acid was dropped onto the ink to prepare an ink neutralized product adjusted to pH 7, and the viscometer Was used to measure the viscosity at 25 ° C. Further, by the following method, the ink was left in a temperature of 25 ° C. and humidity of 15% environment until there was substantially no change in mass to obtain an ink residue. About this ink residue, the viscosity in 25 degreeC was measured with the said viscometer RE-550L.

[Ink residue]
The recording inks of Examples and Comparative Examples were weighed and collected in a glass dish having a diameter of 33 mm using a precision top electronic balance capable of measuring up to 4 decimal places. Next, it is stored at normal pressure in a constant temperature and humidity chamber made by ESPEC (ModelPL-3KP) set at a temperature of 25 ± 0.5 ° C and a humidity of 15 ± 5%. Each sample is taken out every hour and the mass is measured. The storage was continued until the mass change per hour became 1% or less of the total ink mass. The obtained ink residue was weighed with a precision top electronic balance. Next, the viscosity of the ink residue was measured at 25 ° C. using a RE-550L viscometer (manufactured by Toki Sangyo Co., Ltd.) cone rotor 3 ° × R14.

<Average particle size>
The average particle diameter (D50%) of the ink was measured with a particle size distribution measuring device (Nikki Co., Ltd., Nanotrac UPA-EX150).

<Surface tension>
The static 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.).

<PH>
The pH of the ink was measured at 25 ° C. using a pH meter HM-30R (TOA-DKK).

<Foaming / Defoaming>
The foaming and defoaming tests are conducted as a substitute test for the initial filling and maintenance of the printer.

1) Foaming property 10 ml of the evaluation ink was placed in a 100 ml measuring cylinder, and this measuring cylinder was immersed in a 10 ° C. constant temperature water bath for 30 minutes or more to stabilize the liquid temperature of the evaluation ink. Next, an air injection tube having an inner diameter of 1 mm is attached to the graduated cylinder, and the tip of the air injection tube is attached so as to be 5 mm from the bottom of the ink. Furthermore, the air pressure of the pressurizing device was set to 20 gf / cm ² , the valve of the pressurizing device was opened, and at the same time the time measurement was started with a stopwatch, and the memory bubble height of the graduated cylinder after 30 seconds was measured. Evaluation was based on criteria.
[Example: When the scale is 100 ml => 100-10 (sample amount) = height 90 ml]
* If the scale reaches 100 ml within 30 seconds, stop the foaming test.
〔Evaluation criteria〕
○: Bubble height less than 50 ml, △: Bubble height in the range of 50 ml to 90 ml, ×: When the scale reaches 100 ml within 30 seconds

2) Defoaming property In the foaming property test, after blowing air for 30 seconds, the valve of the pressurizing device was immediately closed, and the bubble disappeared spontaneously, and the bubble height after 300 seconds was measured.
〔Evaluation criteria〕
○: Bubble height less than 50 ml immediately after air blowing stopped, △: Bubble height less than 50 ml after 300 seconds, ×: Bubble height of 50 ml or more after 300 seconds

The results of the foaming / antifoaming test are shown in FIGS. 7 and 8, the description of the results of Examples 3 to 5, 9, Reference Example 8, and Comparative Examples 5, 6, 9, and 10, which had a bubble height of 0 ml at 0 to 300 seconds, was omitted.

−Preparation for evaluation of printing I−
In an environment adjusted to a temperature of 25 ± 0.5 ° C. and 15 ± 5% RH, an inkjet printer (IPSiO GX-5000, manufactured by Ricoh Co., Ltd.) is used to drive the piezo element so that the amount of ink discharged is uniform. The voltage was varied so that the same amount of ink was applied to the recording medium.

<Initial fillability>
Immediately after filling the ink into an ink jet printer (IPSiO GX-5000, manufactured by Ricoh Co., Ltd.) that has not been filled with ink, a nozzle check pattern is printed out during print setting maintenance, and nozzle missing and ink color mixing are confirmed. Evaluation was performed based on the following evaluation criteria.
〔Evaluation criteria〕
○: No nozzle omission and color mixing △: No nozzle omission, color mixing, ×: Nozzle omission occurred

<Discharge stability>
First, a chart was created in which 5% area of A4 size paper per color was filled with a solid image using Microsoft Word 2000. Next, the created chart was continuously ejected on a recording medium Type 6200 (manufactured by NBS Ricoh Co., Ltd.), and 200 sets × 5 sets were ejected, and the ejection was evaluated from each nozzle after ejection. The printing mode used was a driver attached to the printer, in which the “plain paper-standard faster” mode was changed to “no color correction” than the user setting for plain paper.
〔Evaluation criteria〕
○: Discharge turbulence △: Discharge turbulence slightly ×: Discharge turbulence or non-discharge portion

-Preparation for printing evaluation II-
Using an inkjet printer (IPSiO GX-5000, manufactured by Ricoh Co., Ltd.) in an environment adjusted to a temperature of 23 ± 0.5 ° C. and 50 ± 5% RH, the piezo element is driven so that the amount of ink discharged is uniform. The voltage was varied so that the same amount of ink was applied to the recording medium.

<Image density>
A chart with 64 point characters “■” created with Microsoft Word 2000 was printed on Type 6200 (manufactured by NBS Ricoh Co., Ltd.), and the “■” portion of the printed surface was measured with X-Rite 938. Judged by. The printing mode used was a driver attached to the printer, in which the “plain paper-standard faster” mode was changed to “no color correction” than the user setting for plain paper.
〔Evaluation criteria〕
○: Black: 1.2 or more,
Yellow: 0.8 or more
Magenta: 1.0 or more,
Cyan: 1.0 or more Δ: Black: 1.15 or more and less than 1.2
Yellow: 0.75 or more and less than 0.8,
Magenta: 0.95 or more and less than 1.0,
Cyan: 0.95 or more and less than 1.0 ×: Black: less than 1.15
Yellow: less than 0.75,
Magenta: less than 0.95,
Cyan: Less than 0.95

<Water resistance>
As with the image density test, the chart was punched onto Type 6200, the “■” portion of the printed surface was dried at 23 ° C. and 50% RH for 24 hours, the chart was immersed in 30 ° C. water for 1 minute, and then gently pulled up Drying was carried out and judged according to the following evaluation criteria.
〔Evaluation criteria〕
○: No color exudation ×: Color exudation

<Light resistance>
Similar to the image density test, a chart was punched into Type 6200, and the “■” portion of the printed surface was dried at a temperature of 23 ° C. and 50% RH for 24 hours. This image portion was irradiated for 24 hours with an xenon irradiance of 0.35 W / m ² (340 nm) that approximated outdoor sunlight in an environment of 70 ° C., 50% RH, black panel temperature 89 ° C. using a weatherometer Ci35AW manufactured by Atlas. Then, front and rear fading and color change were determined according to the following evaluation criteria.
〔Evaluation criteria〕
○: Almost no change △: Change is recognized but acceptable ×: Large color fading and color change

<Drying>
Similar to the image density test, a chart was shot on Type 6200, and immediately after printing, a filter paper was pressed against the “■” portion of the printing surface, and the presence or absence of transfer was determined.
〔Evaluation criteria〕
○: No transfer stain △: Slight transfer stain ×: Transfer stain

<Stickness>
Using an inkjet printer (IPSiO GX-5000, manufactured by Ricoh Co., Ltd.) in an environment adjusted to a temperature of 28 ± 0.5 ° C. and a humidity of 15 ± 5%, the piezo element is driven so that the amount of ink discharged is uniform. After changing the voltage, the head cleaning operation was performed 10 times every hour, and this operation was repeated for 10 hours. After performing the total head cleaning 100 times, after leaving for 12 hours, the wiper section and the wiper cleaner section of the maintenance device The ink fixing property was judged visually.
〔Evaluation criteria〕
○: No ink fixation △: Slight ink fixation ×: Ink fixation

<Storage stability>
Using the viscometer, the storage stability was determined according to the following formula from the viscosity before storage and the viscosity measured after storage at 70 ° C. for 14 days in a sealed container, and evaluated based on the following evaluation criteria.

〔Evaluation criteria〕
○: Within 100 ± 10%.
Δ: More than 100 ± 10 to less than 20%.
X: 100 ± 20% or more.

  As a result of each evaluation, Comparative Examples 1-4, 11, and 12 using a surfactant without using a foam suppressant had high foaming properties and low defoaming properties. In particular, when a fluorosurfactant was used as the surfactant (Comparative Examples 2 and 3), the tendency was strong. Comparative Examples 7 to 9 using a fluorine-based surfactant and a silicone-based antifoaming agent had poor foam stability but poor discharge stability. Comparative Examples 5, 6, and 10 using the foam suppressor of formula (I) without using a fluorosurfactant had poor foam stability but poor storage stability. Examples in which the fluorosurfactant and the foam suppressor (I) were used in combination resulted in high image density, ejection stability and storage stability, and low foaming properties.

  The ink-jet ink of the present invention can be suitably applied to a printer, a facsimile machine, a copying machine, a printer / fax / copier multifunction machine, etc. that perform recording by an ink-jet recording method.

[FIGS. 1 to 5]
DESCRIPTION OF SYMBOLS 101 Apparatus main body 102 Paper feed tray 103 Paper discharge tray 104 Ink cartridge loading part 105 Operation part 111 Upper cover 112 Front surface 115 Front cover 131 Guide rod 132 Stay 133 Carriage 134 Recording head 135 Sub tank 141 Paper stacking part 142 Paper 143 Paper feed roller 144 Separation pad 145 Guide 151 Conveying belt 152 Counter roller 153 Conveying guide 154 Holding member 155 Tip pressure roller 156 Charging roller 157 Conveying roller 158 Tension roller 161 Guide member 171 Separating claw 172 Discharging roller 173 Discharging roller 181 Double-sided paper feeding unit 182 Manual paper feed unit 201 Ink cartridge 241 Ink bag 242 Ink inlet 243 Ink outlet 244 Cartridge case [Fig. Please]
91 Subsystem 92 Cap 92a Suction Cap 92b Cap 92c Cap 92d Cap 93 Wiper Blade 94 Empty Discharge Receiver 96 Cleaner Roller 111 Frame 112 Cap Holder 112A Cap Holder 112B Cap Holder 115 Carriage Lock 119 Flexible Tube

Claims (12)

An ink-jet ink comprising a water-dispersible colorant, a water-soluble organic solvent, a fluorosurfactant, a foam inhibitor and water,
Wherein Ri compound der the foam inhibitor is represented by the general formula (I),
The fluorinated surfactant has the general formula (II) inkjet ink characterized that you containing a compound represented by.
Formula (I)
_{HOR 1 R 3 C- [CH 2} ] n -CR 2 R 4 OH
However, in the general formula (I), _{R 1} and _{R 2} are independently an alkyl group having 3-6 carbon atoms, _{R 3} and _{R 4} are alkyl radicals having 1-2 carbon atoms independently And n is an integer of 1-6.
Formula (II)
_{C n F 2n + 1 -CH 2} CH (OH) CH 2 -O- (CH 2 CH 2 O) a -Y '
However, in the general formula (II), n is an integer from 2 to 6, a is an integer from 15 to 50, Y 'is _-C b _{H 2b +} 1 (b is an integer of 11 to 19) or - _{CH 2 CH (OH) CH 2} -C d F 2d + 1 (d is a is an integer from 2 to 6) represents a.   The compound represented by the general formula (I) is 2,4,7,9-tetramethyldecane-4,7-diol or 2,5,8,11-tetramethyldodecane-5,8-diol. The inkjet ink according to claim 1. The compound represented by the general formula (II) is:
_{C 4 F 9 -CH 2 CH (} OH) CH 2 O- (CH 2 CH 2 O) 21 -C 12 H 25,
_{C 4 F 9 -CH 2 CH (} OH) CH 2 O- (CH 2 CH 2 O) 25 -C 12 H 25,
_{C 4 F 9 -CH 2 CH (} OH) CH 2 O- (CH 2 CH 2 O) 23 -CH 2 CH (OH) CH 2 -C 4 F 9,
_{C 4 F 9 -CH 2 CH (} OH) CH 2 O- (CH 2 CH 2 O) 35 -CH 2 CH (OH) CH 2 -C 4 F 9, or _{C 4 F 9 -CH 2 CH (} OH) _{CH 2 O- (CH 2 CH 2} O) 45 -CH 2 CH (OH) CH 2 -C 4 F 9
The inkjet ink according to claim 1 , wherein the inkjet ink is an inkjet ink. A the water-dispersible colorant is a pigment, according to claim 1 to 3, characterized in that at least one pigment is selected from the group consisting of pigments coated with a self-dispersible pigment and a polymer The inkjet ink as described in any one of these. The coating resin of the pigment coated with the resin is a water-insoluble vinyl polymer, and the water-insoluble vinyl polymer is
(A) a monomer represented by the general formula (VI),
(B) a salt-forming group-containing monomer, and (C) The inkjet ink according to 請 Motomeko 4 you wherein a is obtained by polymerizing a monomer mixture containing the hydrophobic monomer.
Formula (VI)

However, in the general formula (VI), R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 4 carbon atoms which alkylene group or a hydrogen atom C2-8 substituted with a phenyl group Yes, n is a number of 2 to 30, and R ₃ represents a linear or branched alkyl group having 2 to 30 carbon atoms. The (C) hydrophobic monomer is
(C-1) a monomer represented by the general formula (VII),
(C-2) a monomer represented by the general formula (VIII), and
(C-3) Macromer,
The inkjet ink according to claim 5 , comprising at least one selected from the group consisting of:
Formula (VII)

However, in the general formula (VII), _{R 4} is a hydrogen atom or a methyl group, _{R 5} is an alkyl group having 1 to 22 carbon atoms, an aryl group having 6 to 22 carbon atoms, alkylaryl group or arylalkyl group, Or it represents a C3-C22 cyclic hydrocarbon group.
Formula (VIII)

However, in general formula (VIII), R < ₆ > is a hydrogen atom or a methyl group, and R < ₇ > represents the phenyl group, biphenyl group, or naphthalene group which may have a substituent. The viscosity of the ink residue left until the mass change substantially disappears in an environment of a temperature of 25 ° C. and a humidity of 15% is 3000 mPa · s or less,
The ink for ink-jet recording according to any one of claims 1 to 6 , wherein the viscosity of the ink preparation whose pH is adjusted to 7 with an acid is 500 mPa · s or more. As a penetrant, any one of claims 1 to 7, characterized in that it contains one of the 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol The ink for inkjet described in 2. Ink cartridge formed by accommodating the ink jet ink according to the vessel in any one of claims 1 to 8. Ink jet recording method of stimulating in the inkjet ink is applied according, characterized in that it comprises an ink jetting step of forming an image by ejecting the inkjet ink in any one of claims 1 to 8. A stimulus to the inkjet ink according to any one of claims 1 to 8 is applied, an ink jet recording apparatus having an ink jetting unit for forming an image on a recording medium by ejecting the inkjet ink. An ink recorded matter comprising an image formed by flying the ink for ink jet according to any one of claims 1 to 8 on a recording medium.

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