JP5324738B2 - Water-based ink for inkjet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide water-based ink for inkjet recording exhibiting high printing density by one-pass printing on plain paper and suitable for high-speed printing, and also to provide an aqueous dispersion used in the water-based ink. <P>SOLUTION: The invention provides an aqueous dispersion for inkjet recording comprising water-insoluble polymer particles containing a colorant and fine particles containing fluorine. The water-based ink contains the aqueous dispersion. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to an aqueous ink for inkjet recording, and an aqueous dispersion used for the ink.

The ink jet recording method is a recording method in which characters and images are obtained by ejecting ink droplets directly from a very fine nozzle onto a recording member and attaching them. This method is easily spread at a full color and is inexpensive, and can be used as a recording member, and can be used as a recording member.
With regard to such an ink jet recording system, for example, Patent Document 1 discloses a water-based ink in which a pigment is contained in a vinyl polymer.
Patent Document 2 discloses an ink composition comprising water, a colorant, and resin fine particles, wherein the resin fine particles are fluororesin fine particles having a fluoroolefin unit.
U.S. Pat. No. 6,089,095 discloses an ink containing an improved aqueous carrier medium containing an effective amount of core shell or tetrafluoroethylene emulsion polymer that improves image integrity and an insoluble colorant. However, the water-based inks disclosed in the above-mentioned patent documents still do not have sufficient print density when printing on plain paper in one pass by the inkjet recording method.

International Publication No. 00/39226 Pamphlet Japanese Patent Laid-Open No. 10-17801 JP-A-10-195362

  An object of the present invention is to provide a water-based ink for inkjet recording, which has a high print density when printed on plain paper in one pass and is suitable for high-speed printing.

The present invention provides the following (1) to (2).
(1) An aqueous dispersion for ink jet recording comprising water-insoluble polymer particles containing a colorant and fluorine-containing fine particles.
(2) An aqueous ink containing the aqueous dispersion of (1).

  A high print density can be achieved even when printing is performed on plain paper in one pass by the aqueous dispersion for inkjet recording and the water-based ink of the present invention.

The present invention is an aqueous dispersion for inkjet recording containing water-insoluble polymer particles containing a colorant and fluorine-containing fine particles.
[Fluorine-containing fine particles]
By using fluorine-containing fine particles (hereinafter, also simply referred to as “fine particles”), the present inventors improve the light intake efficiency into the colorant on the printing paper and improve the print density even when high-speed printing is performed. I found that it was possible. The refractive index of the fine particles used in the present invention is preferably 1.2 to 1.6, more preferably 1.3 to 1.55, from the viewpoint of improving the print density even when high-speed printing is performed. The refractive index can be measured by an optical interference film thickness measuring device (product name: Lambda Ace VM-1000, manufactured by Dainippon Screen Co., Ltd.) described later. When the fine particles are powder, they are dispersed in a dispersion medium such as water or ethanol with about 0.01 parts by weight of polyacrylate (for example, Poise 530A, manufactured by Kao Corporation) with respect to 1 part by weight of the fine particles. A dispersion can be used for the said measuring method. Specifically, it depends on the measurement method described later.

The average particle size of the fine particles used in the present invention is preferably from 50 to 300 nm, more preferably from 55 to 250 nm, particularly preferably from 60 to 200 nm, from the viewpoint of improving the print density even when high-speed printing is performed. The average particle diameter of the fine particles depends on the measurement method described later.
The limitation of the refractive index and average particle size of the fine particles is that the inventors have reduced the light reflectance from the surface of the printing surface in order to achieve high printing density even when printing at high speed by the inkjet recording method. By finding out what to do.
In general, in order to reduce the reflectance of light from the surface of the printing surface, the surface scattering of light on the surface of the colorant is reduced to improve the efficiency of taking light into the colorant and to improve the light absorption rate. It is effective.
When water-based ink containing fine particles and a colorant is printed on a printing paper by an inkjet recording method, the aggregate of fine particles covers the colorant of the printed matter at the minute portion of the applied ink, and the printed matter It is considered that the print density can be improved by performing the same function as that of the antireflection film.

In general, when substances having different refractive indexes are present, the refractive index R of air is n ₀ , the refractive index of the colorant is n ₂ , and the refractive index of the substance present on the colorant is n _1. It is known that it is represented by the following formula.
Reflectivity R = [(n ₀ n ₂ −n ₁ n ₁ ) / (n ₀ n ₂ + n ₁ n ₁ )] ²
Here, if the refractive index n _{0 of} air is 1.00, the reflectance R may be minimized in order to improve the print density. Therefore, in order to minimize the value of the above equation, n ₁ = √n ₂ is preferable.
Considering that the refractive index of the quinacridone pigment (Y) is about 2, and the refractive index of the phthalocyanine pigment (C) and the azo pigment (M) is about 1.4, the particles used in the present invention It can be seen that the above range is appropriate for the refractive index n ₁ .
In addition, it is known that the intensity of reflected light is most weakened by reversing the phase of the light reflected on the surface of the colorant and the light reflected on the surface of the substance present on the colorant. The film thickness d of the substance (refractive index n ₁ ) present on the colorant is the film thickness d = λ / [(2 + 2√2) × n ₁ ] where λ is the wavelength of light.
It is preferable that
The film thickness d is a calculated value when the light incident angle is 45 ° and the light receiving angle is 0 ° (measurement condition of Macbeth densitometer).
The magenta measurement wavelength (λ) is 536 nm (half width ± 20 nm), the cyan measurement wavelength (λ) is 624 nm (half width ± 20 nm), and the yellow measurement wavelength (λ) is 432 nm (half width ± 20 nm). In view of n ₁ , it can be seen that the above range is appropriate for the average particle size of the particles used in the present invention.

Examples of the fluorine-containing fine particles include polymer particles having fluorine atoms or inorganic particles having fluorine atoms.
Examples of the polymer constituting the polymer particles having a fluorine atom include those obtained by polymerizing a fluorine-containing monomer. In the present specification, the “fluorine-containing monomer” is an unsaturated compound having a fluorine atom bonded to a carbon atom. The fluorine-containing monomer is not particularly limited as long as it can be polymerized. For example, tetrafluoroethylene [TFE], chlorotrifluoroethylene [CTFE], trifluoroethylene, hexafluoropropylene [HFP], perfluoro ( Alkyl vinyl ether) [PAVE], vinylidene fluoride [VdF], and perfluoroalkyl (meth) acrylate, pentadecafluorooctyl acrylate, tetrafluoro-3- (pentafluoroethoxy) propioacrylate, heptafluorobutyl acrylate, 2- (Heptafluorobutoxy) fluorinated acrylic ester or meta, such as ethyl acrylate, trifluoroisopropyl methacrylate, 2,2,2-trifluoro-1-methylethyl methacrylate Acrylic acid esters, and the like. The fluoropolymer may be obtained by polymerizing a fluorine-free vinyl monomer together with the fluorine-containing monomer. In the present specification, the “fluorine-free vinyl monomer” is a monomer having a carbon-carbon double bond and having no fluorine atom. 1 type may be used for the said fluorine-containing monomer and a fluorine-free vinyl monomer, respectively, and 2 or more types may be used for it.

The fluoropolymer is not particularly limited, and examples thereof include polytetrafluoroethylene [PTFE], tetrafluoroethylene copolymer [TFE copolymer], and fluororubber.
The “PTFE” is a homopolymer obtained by polymerizing only TFE, and the “TFE copolymer” is a copolymer obtained by polymerizing TFE and a monomer copolymerizable with TFE. . The monomer copolymerizable with the TFE is not particularly limited. For example, the fluorine-containing monomer other than TFE may be used, or the fluorine-free vinyl monomer may be used.
Examples of the TFE copolymer include tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymer [PFA], tetrafluoroethylene / hexafluoropropylene copolymer [FEP], tetrafluoroethylene / perfluoro (alkyl vinyl ether). ) / Hexafluoropropylene copolymer, ethylene / tetrafluoroethylene copolymer, tetrafluoroethylene / propylene copolymer, tetrafluoroethylene / vinylidene fluoride copolymer, tetrafluoroethylene / vinylidene fluoride / chlorotrifluoroethylene A copolymer is mentioned.

The “fluororubber” is a copolymer having an elastomeric fluorine atom.
The fluororubber is not particularly limited. For example, among those obtained by polymerizing the above-described fluorine-containing monomer and a monomer copolymerizable with a fluorine-containing monomer such as a fluorine-free vinyl monomer, if desired, an elastomer The thing etc. which have property are mentioned. Examples of the fluororubber include vinylidene fluoride / hexafluoropropylene copolymer, tetrafluoroethylene / vinylidene fluoride / hexafluoropropylene copolymer, vinylidene fluoride / chlorotrifluoroethylene copolymer, and the like.
Examples of the inorganic particles having a fluorine atom include lithium fluoride, magnesium fluoride, and calcium fluoride.

In order to have a certain film thickness (d) on the colorant, it is desirable that the fine particles used in the present invention are present on the colorant in the form of particles rather than having a film-forming property that diffuses on the recording paper. .
The Tg of the polymer particles having fluorine atoms is preferably 20 ° C. or higher, more preferably 30 ° C. or higher, and no particular upper limit from the viewpoint of being present on the colorant in the form of particles. To 20 to 250 ° C. is preferable, and 30 to 250 ° C. is more preferable. Tg is measured by the method described in the examples.
When the Tg of the polymer particles is in the range of 20 ° C. or more, the polymer fine particles are hardly formed into a film by heat received in the drying process of the ink after printing, and can be present in the form of particles on the colorant.
Further, it was recognized that the fluorine-containing fine particles suppressed the sink of the colorant contained in the same water-based ink into plain paper after being ejected from the inkjet nozzle. It is considered that the suppression of sinking of the colorant into plain paper contributes to the improvement of the print density. Specifically, it can be confirmed by measuring the average penetration depth (pigment sinking) of the pigment in the water-based ink by a standard test method described later. From the viewpoint of printing density, the average penetration depth of the pigment is preferably 65 μm or less, more preferably 60 μm or less, and from the viewpoint of scratch resistance, it is preferably 10 μm or more, more preferably 20 μm or more. desirable.
From these viewpoints, the average penetration depth of the colorant is preferably 10 to 65 μm, and more preferably 20 to 60 μm. It is preferable to use fluorine-containing fine particles capable of suppressing the sinking of the pigment within this range.

[Colorant]
As the colorant, either a hydrophobic dye or a pigment can be used. Moreover, both can be used in combination at an arbitrary ratio. Among them, it is preferable to use a pigment for the development of high weather resistance, which has been demanded in recent years.
The pigment may be either an organic pigment or an inorganic pigment. If necessary, extender pigments can be used in combination.
Examples of the organic pigment include azo pigments, diazo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, perylene pigments, perinone pigments, thioindigo pigments, anthraquinone pigments, and quinophthalone pigments.
Specific examples of preferred organic pigments include CI Pigment Yellow 13, 17, 74, 83, 97, 109, 110, 120, 128, 139, 151, 154, 155, 174, 180; CI Pigment Red 48, 57 : 1, 122, 146, 176, 184, 185, 188, 202; CI Pigment Violet 19, 23; CI Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, 16, 60; CI pigment green 7, 36 etc. are mentioned.
Examples of the inorganic pigment include carbon black, metal oxide, metal sulfide, and metal chloride. Among these, carbon black is particularly preferable as the black water-based ink. Examples of carbon black include furnace black, thermal lamp black, acetylene black, and channel black.

As the dye, a hydrophobic dye is preferably used because it can be contained in a water-insoluble polymer. Examples of hydrophobic dyes include oily dyes and disperse dyes. The solubility of the hydrophobic dye in the organic solvent is 2 g / in the organic solvent used for dissolving the hydrophobic dye during the production of the aqueous dispersion from the viewpoint of efficiently incorporating the dye into the water-insoluble polymer. L or more is preferable, and 20 to 500 g / L (25 ° C.) is more preferable.
Examples of oil-based dyes include CI Solvent Black 3, 7, 27, 29, 34, 45; CI Solvent Yellow 14, 16, 29, 56, 82, 83: 1; CI Solvent Red 1, 3, 8 , 18, 24, 27, 43, 49, 51, 72, 73; CI Solvent Violet 3; CI Solvent Blue 2, 4, 11, 44, 64, 70; CI Solvent Green 3, 7; Orange 2 etc. are mentioned.
Commercially available oily dyes include, for example, Nubian Black PC-0850, Oil Black HBB, Oil Black 860, Oil Yellow 129, Oil Yellow 105, Oil Pink 312, Oil Red 5B, Oil Scarlet 308, Vali Fast Blue 2606 , Oil Blue BOS [above, Orient Chemical Co., Ltd., trade name], Neopen Yellow 075, Neopen Mazenta SE1378, Neopen Blue808, Neopen Blue 807, Neopen Blue FF4012, Neopen Cyan FF4238 (above, BASF Corporation, trade name) .

  Examples of the disperse dye include CI Disperse Yellow 5, 42, 54, 64, 79, 82, 83, 93, 99, 100, 119, 122, 124, 126, 160, 184: 1, 186, 198, 199, 204, 224, 237; CI Disperse Orange 13, 29, 31: 1, 33, 49, 54, 55, 66, 73, 118, 119, 163; CI Disperse Red 54, 60, 72, 73, 86, 88, 91, 93, 111, 126, 127, 134, 135, 143, 145, 152, 153, 154, 159, 164, 167: 1, 177, 181, 204, 206, 207, 221, 239, 240, 258, 277, 278, 283, 311, 323, 343, 348, 356, 362; CI Disperse Violet 33; CI Disperse Blue 56, 60, 73, 87, 113, 128, 143, 148, 154, 158, 165, 165: 1, 165: 2, 176, 183, 185, 197, 198, 201, 214, 224, 225, 257, 266, 267, 287, 354, 358, 365, 368; CI Disperse Green 6: 1, 9; Among these, CI solvent yellow 29 and 30 as yellow, CI solvent blue 70 as cyan, CI solvent red 18 and 49 as magenta, CI solvent black 3, 7 and black dye of nigrosine as black are preferable. .

In the aqueous dispersion of the present invention, the content of the colorant is preferably 1 to 20% by weight, and more preferably 3 to 10% by weight from the viewpoint of improving dispersion stability, printing density, and the like.
The weight ratio of the water-insoluble polymer to the colorant is preferably 50/50 to 90/10, more preferably 50/50 to a weight ratio of [colorant / water-insoluble polymer] from the viewpoint of increasing the printing density. 80/20, more preferably 55/45 to 78/22.

Water-insoluble polymer For the water dispersion and water-based ink of the present invention, an aqueous dispersion in which a colorant is contained in water-insoluble polymer particles is used from the viewpoint of excellent abrasion resistance, low viscosity and excellent dischargeability.
In the present invention, examples of the water-insoluble polymer constituting the water-insoluble polymer particles include a water-insoluble vinyl polymer, a water-insoluble ester polymer, and a water-insoluble urethane polymer. Among these, a water-insoluble vinyl polymer is preferable from the viewpoint of the stability of the aqueous dispersion. In the present invention, the water-insoluble polymer means that when it is dried at 105 ° C. for 2 hours and then dissolved in 100 g of water at 25 ° C., the dissolved amount is 10 g or less, preferably 5 g or less, more preferably 1 g or less. A polymer. When the water-insoluble polymer has a salt-forming group, the above-mentioned dissolution amount refers to the dissolution amount when the salt-forming group of the water-insoluble polymer is neutralized 100% with acetic acid or sodium hydroxide, depending on the type.
The water-insoluble vinyl polymer used in the present invention preferably has a structural unit represented by the following general formula (1) from the viewpoint of gloss of printed matter.

In the formula (1), R ¹ represents a hydrogen atom or a methyl group. R ² may have a substituent, which has 7 to 22 carbon atoms, preferably 7 to 18 carbon atoms, more preferably an arylalkyl group having 7 to 12 carbon atoms, or 6 to 22 carbon atoms, preferably Represents an aryl group having 6 to 18 carbon atoms, more preferably 6 to 12 carbon atoms. The substituent may contain a hetero atom. Examples of the hetero atom include a nitrogen atom, an oxygen atom, and a sulfur atom.
Specific examples of R ² include benzyl group, phenethyl group (phenylethyl group), phenoxyethyl group, diphenylmethyl group, and trityl group.
Specific examples of the substituent include preferably an alkyl group, an alkoxy group or an acyloxy group, a hydroxyl group, an ether group, an ester group or a nitro group having 1 to 9 carbon atoms.
As the structural unit represented by the formula (1), a structural unit derived from benzyl (meth) acrylate is particularly preferable from the viewpoint of developing high gloss.

The structural unit represented by the formula (1) is preferably obtained by polymerizing a monomer represented by the following general formula (1-1).
CH ₂ = CR ¹ COOR ² (1-1)
(Wherein R ¹ and R ² are the same as described above.)
Specifically, phenyl (meth) acrylate, benzyl (meth) acrylate, 2-phenylethyl (meth) acrylate, phenoxyethyl (meth) acrylate, 1-naphthyl acrylate, 2-naphthyl (meth) acrylate, phthalimidomethyl (meta ) Acrylate, p-nitrophenyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, 2-acryloyloxyethyl phthalate, etc. Thereby, the polymer which has a structural unit represented by Formula (1) is compoundable. Among these, benzyl (meth) acrylate is particularly preferable. These can be used alone or in admixture of two or more.
As used herein, “(meth) acrylate” means “acrylate”, “methacrylate”, or a mixture thereof.

  The water-insoluble vinyl polymer used in the present invention preferably further has a structural unit represented by the following general formula (2).

In formula (2), R ³ represents a hydrogen atom or a methyl group, and R ⁴ O represents an oxypropylene group. R ⁴ O may contain —CH (CH ₃ ) CH ₂ O— in addition to —CH ₂ CH (CH ₃ ) O—. R ⁵ O represents an oxyalkylene group having 2 or 4 carbon atoms, and represents an oxyethylene group or an oxytetramethylene group.
R ⁶ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a phenyl group that may have an alkyl group having 1 to 9 carbon atoms.
R ⁶ is preferably an alkyl group having 1 to 12 carbon atoms and more preferably an alkyl group having 1 to 8 carbon atoms from the viewpoint of high printing density and good storage stability. Moreover, the phenyl group which may have a C1-C8 alkyl group is preferable. Examples of the alkyl group having 1 to 8 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, butyl group, t-butyl group, hexyl group, octyl group, and 2-ethylhexyl group.
R ⁴ O and R ⁵ O are randomly added or block added. When R ⁴ O and R ⁵ O are added as a block, —COO— (R ⁴ O) _x — (R ⁵ O) _y —R ⁶ or —COO— (R ⁵ O) _y — (R ⁴ O) Any of _x -R ⁶ may be used.
x and y represent an average added mole number, x is a number of 1 to 30, 2 to 30 is preferable, 3 to 20 is more preferable, and 3 to 15 is particularly preferable. y is a number from 0 to 30, preferably 0 to 20, and more preferably 0 to 15. The y R ⁵ Os may be the same or different.

The structural unit represented by the formula (2) is preferably obtained by polymerizing a monomer represented by the following general formula (2-1).
^{_{CH 2 = CR 3 COO- (R}} 4 O) x - (R 5 O) y -R 6 (2-1)
(In the formula, R ³ , R ⁴ O, R ⁵ O, R ⁶ , x, and y are the same as described above.)
Among the formula (2), the structural unit represented by the following general formula (3) or (4) is preferable for giving a high printing density, and the water-insoluble vinyl polymer used in the present invention is represented by the following general formula (3). ) And the structural unit represented by the following general formula (4).

（式中、Ｒ³、ｘ、Ｒ⁶は、前記と同じである。）

(In the formula, R ³ , x and R ⁶ are the same as described above.)

Formula (3) is a case where y is 0 in Formula (2).
The structural unit represented by the formula (3) is preferably obtained by polymerizing a monomer represented by the following general formula (3-1).
^{_{CH 2 = CR 3 COO- (CH}} 2 CH (CH 3) O) x -R 6 (3-1)
(In the formula, R ³ , R ⁶ and x are the same as described above.)
Specifically, polypropylene glycol mono (meth) acrylate, methoxypolypropylene glycol mono (meth) acrylate, ethoxypolypropylene glycol mono (meth) acrylate, octoxypolypropylene glycol mono (meth) acrylate, stearoxy polypropylene glycol mono (meth) acrylate , Nonylphenoxy polypropylene glycol mono (meth) acrylate, phenoxy polypropylene glycol mono (meth) acrylate, and the like. Among these, polypropylene glycol mono (meth) acrylate is particularly preferable. These can be used alone or in admixture of two or more.

  On the other hand, the following general formula (4) is a case where y is 1 or more in the above general formula (2).

In formula (4), R ³ , R ⁶ and x are the same as described above. p is a number of 2 or 4, z represents the average number of added moles, is a number of 1 to 30, 2 to 20 is preferable, and 3 to 15 is more preferable. (CH ₂ CH (CH ₃ ) O) and ((CH ₂ ) _P O) are randomly added or block-added, and in the case of block addition, —COO— (CH ₂ CH (CH ₃ ) O) _X − _{((CH 2) P O)} Z -R 6 _{or, -COO - ((CH 2)} P O) Z - (CH 2 CH (CH 3) O) may be any of _X -R ^6.

The structural unit represented by the formula (4) is preferably obtained by polymerizing a monomer represented by the following general formula (4-1) or (4-2).
^{_{CH 2 = CR 3 COO- (CH}} 2 CH (CH 3) O) x - (CH 2 CH 2 O) z -R 6 (4-1)
^{_{CH 2 = CR 3 COO- (CH}} 2 CH (CH 3) O) x - ((CH 2) 4 O) z -R 6 (4-2)
In the formula, R ³ , R ⁶ , x and z are the same as described above. (CH ₂ CH (CH ₃ ) O) and (CH ₂ CH ₂ O), and (CH ₂ CH (CH ₃ ) O) and ((CH ₂ ) ₄ O) are randomly or block-added, for block ^{_{addition, CH 2 = CR 3 COO- (}} CH 2 CH (CH 3) O) x - (CH 2 CH 2 O) z -R 6 or ^{_{CH 2 = CR 3 COO- (CH}} 2 CH 2 O) _{z - (CH 2 CH (CH} 3) O) may be either _x -R ^6, or ^{_{CH 2 = CR 3 COO- (CH}} 2 CH (CH 3) O) x - ((CH 2) 4 O) _z -R ⁶ or ^{_{CH 2 = CR 3 COO - (}} (CH 2) 4 O) z - (CH 2 CH (CH 3) O) may be either _x -R ^6.

Specifically, ethylene glycol / propylene glycol (meth) acrylate, poly (ethylene glycol / propylene glycol) mono (meth) acrylate [ethylene glycol and propylene glycol are randomly bonded], octoxypolyethylene glycol / polypropylene glycol mono (Meth) acrylate [polyethylene glycol and polypropylene glycol are block-bonded. Including block bonding of polyethylene glycol and polypropylene glycol from the (meth) acryl group side and vice versa. same as below. ], Octoxy poly (ethylene glycol / propylene glycol) mono (meth) acrylate, stearoxy polyethylene glycol / polypropylene glycol mono (meth) acrylate, stearoxy poly (ethylene glycol / propylene glycol) mono (meth) acrylate, phenoxy polyethylene glycol / polypropylene Glycol mono (meth) acrylate, phenoxypoly (ethylene glycol / propylene glycol) mono (meth) acrylate, nonylphenoxy polyethylene glycol / polypropylene glycol mono (meth) acrylate, nonylphenoxy poly (ethylene glycol / propylene glycol) mono (meth) acrylate Poly (propylene glycol / tetramethylene glycol monomer) Among them, poly (ethylene glycol / propylene glycol) mono (meth) acrylate and poly (propylene glycol / tetramethylene glycol monomethacrylate) are particularly preferable, and these may be used alone or in combination of two or more. It can be used by mixing.
Specific examples of the monomer represented by the formula (2-1) that can be obtained commercially include Blemmer series, PP-500, 800, 1000, 50AOEP-800B, 43ANEP-500 from Nippon Oil & Fats Co., Ltd. 70ANEP-550, 50PEP-300, 50PPT-800, 50POEP-800B, and the like.

  The weight ratio of the structural units represented by the general formula (1) and the general formula (2) in the water-insoluble vinyl polymer used in the present invention [the structural unit represented by the formula (1) / the formula (2) The structural unit] is preferably from 1/2 to 10/1, more preferably from 1/2 to 8/1, and more preferably from 1/2 to 5 /, from the viewpoints of achieving both print density and glossiness and imparting fixability. 1 is more preferable, and 1/1 to 5/1 is most preferable.

The water-insoluble vinyl polymer preferably further contains a structural unit derived from the salt-forming group-containing monomer (a) from the viewpoint of improving the dispersibility. Examples of the salt-forming group include a carboxy group, a sulfonic acid group, a phosphoric acid group, an amino group, and an ammonium group.
The structural unit derived from the salt-forming group-containing monomer (a) can be obtained by polymerizing the salt-forming group-containing monomer, but after polymerization of the polymer, the salt-forming group (anionic group or cationic group) is added to the polymer chain. ) May be introduced.
As the salt-forming group-containing monomer (a), (a-1) an anionic monomer and (a-2) a cationic monomer are preferable.

[(A-1) anionic monomer]
(A-1) As an anionic monomer, 1 or more types chosen from the group which consists of an unsaturated carboxylic acid monomer, an unsaturated sulfonic acid monomer, and an unsaturated phosphoric acid monomer are mentioned.
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.
Examples of the unsaturated sulfonic acid monomer include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) acrylate, bis- (3-sulfopropyl) -itaconate, and the like.
Examples of unsaturated phosphoric acid monomers include vinylphosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acrylic acid. And leuoxyethyl phosphate.
Among the above anionic monomers, unsaturated carboxylic acid monomers are preferable, and acrylic acid and methacrylic acid are more preferable from the viewpoints of ink viscosity and dischargeability.

[(A-2) Cationic monomer]
(A-2) As a cationic monomer, 1 or more types chosen from the group which consists of an unsaturated tertiary amine containing vinyl monomer and an unsaturated ammonium salt containing vinyl monomer are mentioned.
Examples of the unsaturated tertiary amine-containing monomer include N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, and N, N. -Dimethylaminopropyl (meth) acrylamide, vinylpyrrolidone, 2-vinylpyridine, 4-vinylpyridine, 2-methyl-6-vinylpyridine, 5-ethyl-2-vinylpyridine and the like.
Examples of unsaturated ammonium salt-containing monomers include N, N-dimethylaminoethyl (meth) acrylate quaternized product, N, N-diethylaminoethyl (meth) acrylate quaternized product, N, N-dimethylaminopropyl (meth). Examples include acrylate quaternized products.
Among the above cationic monomers, N, N-dimethylaminoethyl (meth) acrylate, NN-dimethylaminopropyl (meth) acrylamide and vinylpyrrolidone are preferable.
Said (a) salt production | generation group containing monomer can be used individually or in mixture of 2 or more types.

The water-insoluble polymer is a polymer containing a structural unit derived from the general formula (1) and / or (2) and (a) a salt-forming group-containing monomer from the viewpoint of expressing a sufficient printing density and dispersion stability. A water-insoluble graft polymer having a main chain and a structural unit derived from the macromer (b) in the side chain is preferable.
As the macromer of the component (b), the following (b-1) styrene-based macromer, (b-2) alkyl (meth) acrylate-based macromer, (b-3) aromatic ring-containing (meth) acrylate-based macromer, (b- 4) Silicone macromers and the like can be mentioned.
The component (b) is used from the viewpoint of increasing the printing density and the dispersion stability of the water-insoluble polymer fine particles containing a colorant, and the number average molecular weight is 500 to 100,000, preferably 1,000 to 10,000. And a macromer which is a monomer having a polymerizable functional group such as an unsaturated group at one end.
The number average molecular weight of the component (b) can be measured by gel permeation chromatography using polystyrene as a standard substance and tetrahydrofuran containing 50 mmol / L acetic acid as a solvent.

[(B-1) Styrenic macromer]
The styrenic macromer means a macromer having a structural unit derived from a styrenic monomer such as styrene, α-methylstyrene, vinyltoluene and the like (referred to as (b-1) monomer).
Of the styrenic monomers, styrene is preferred.
Examples of the styrenic macromer include a styrene homopolymer having a polymerizable functional group at one end, and a copolymer of styrene and another monomer having a polymerizable functional group at one end.
The polymerizable functional group present at one end is preferably an acryloyloxy group or a methacryloyloxy group, and by copolymerizing these, a water-insoluble graft polymer having a structural unit derived from a styrenic macromer can be obtained.
In the side chain or the styrenic macromer, the content of the structural unit derived from the styrenic monomer is preferably 60% by weight or more, more preferably 70% by weight or more, and particularly preferably 90% by weight from the viewpoint of scratch resistance. That's it.
Examples of commercially available styrenic macromers include trade names of Toa Gosei Co., Ltd., AS-6, AS-6S, AN-6, AN-6S, HS-6, HS-6S, and the like.

[(B-2) alkyl (meth) acrylate macromer]
The alkyl (meth) acrylate-based macromer is a (meth) acrylic acid ester [(b-2) which may have a hydroxy group and has an alkyl group having 1 to 22 carbon atoms, preferably 1 to 18 carbon atoms. A macromer having a structural unit derived from.
Specific examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (iso or tertiary). Examples include butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) decyl (meth) acrylate, (iso) stearyl (meth) acrylate, and the like.
(B-2) A side chain containing a monomer-derived structural unit is obtained by copolymerizing an alkyl (meth) acrylate macromer having a polymerizable functional group at one end, such as methyl methacrylate macromer, butyl acrylate. System macromers, isobutyl methacrylate macromers, lauryl methacrylate macromers, and the like.
The alkyl (meth) acrylate-based macromer is composed of an alkyl (meth) acrylate homopolymer having a polymerizable functional group at one end, and an alkyl (meth) acrylate having another polymerizable functional group at one end and another monomer. A copolymer may be mentioned, and the polymerizable functional group is preferably an acryloyloxy group or a methacryloyloxy group. Other monomers include the above (1) styrene monomer ((b-1) monomer), (3) aromatic ring-containing (meth) acrylate monomer other than styrene ((b-3) monomer), etc. Can be mentioned.
In the side chain or in the alkyl (meth) acrylate macromer, the content of the structural unit derived from the (meth) acrylic ester is the largest, and from the viewpoint of scratch resistance, it is preferably 60% by weight or more, more preferably 70%. % By weight or more, particularly preferably 90% by weight or more.

[(B-3) Aromatic ring-containing (meth) acrylate-based macromer]
The aromatic ring-containing (meth) acrylate-based macromer means a macromer having a structural unit derived from an aromatic ring-containing (meth) acrylate [referred to as (b-3) monomer].
As the aromatic ring-containing (meth) acrylate, a monomer represented by the general formula (1-1) is preferable.
CH ₂ = CR ¹ COOR ² (1-1)
(Wherein R ¹ and R ² are the same as described above.)
Specifically, benzyl (meth) acrylate, phenyl (meth) acrylate, 2-phenylethyl (meth) acrylate, phenoxyethyl (meth) acrylate, 1-naphthyl acrylate, 2-naphthyl (meth) acrylate, phthalimidomethyl (meta ) Acrylate, p-nitrophenyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, 2-acryloyloxyethyl phthalate, and the like. Among these, benzyl (meth) acrylate is particularly preferable. These can be used alone or in admixture of two or more.

A side chain containing a structural unit derived from an aromatic ring-containing (meth) acrylate can be obtained by copolymerizing an aromatic ring-containing (meth) acrylate-based macromer having a polymerizable functional group at one end.
An aromatic ring-containing (meth) acrylate-based macromer is a homopolymer of an aromatic ring-containing (meth) acrylate having a polymerizable functional group at one end, and an aromatic ring-containing (meth) acrylate having a polymerizable functional group at one end And other monomers, and the polymerizable functional group is preferably an acryloyloxy group or a methacryloyloxy group. Examples of other monomers include the above-mentioned (1) styrene monomer [(b-1) monomer], (2) (meth) acrylic acid ester [(b-2) monomer] and the like.
In the side chain or the aromatic ring-containing (meth) acrylate-based macromer, the content of the structural unit derived from the aromatic ring-containing (meth) acrylate is the largest.

[(B-4) Silicone Macromer]
The water-insoluble graft polymer used in the present invention may have an organopolysiloxane chain as a side chain. This side chain can be obtained, for example, by copolymerizing a silicone macromer having a polymerizable functional group at one end, preferably represented by the following general formula (5).
_{CH 2 = C (CH 3)} -COOC 3 H 6 - [Si (CH _{3) 2} -O] _{t -Si (CH 3) 3 (} 5)
(In the formula, t represents a number of 8 to 40.)

When the polymer used in the present invention is a water-insoluble graft polymer, the weight ratio of the main chain to the side chain [main chain / side chain] is 1/1 to 20/1 in order to improve dispersion stability. Is preferable, 3/2 to 15/1 is more preferable, and 2/1 to 10/1 is particularly preferable. It is calculated that the polymerizable functional group is contained in the side chain.
Among the above, a styrenic macromer having a polymerizable functional group at one end is preferable from the viewpoint of high affinity with a colorant and improving dispersion stability.
In the present specification, “(iso or tertiary)” and “(iso)” are the case where the branched structure represented by “iso” or “tertiary” is present or not present (normal). Both are shown.

The water-insoluble polymer preferably further contains a structural unit derived from the hydrophobic monomer (c) from the viewpoint of improving dispersion stability, printing density and glossiness.
The structural unit derived from the hydrophobic monomer (c) can be obtained by polymerizing the hydrophobic monomer. However, after the polymerization of the polymer, the hydrophobic monomer may be introduced into the polymer chain.
As the hydrophobic monomer (c), (c-1) (meth) acrylate having an alkyl group having 1 to 22 carbon atoms or (c-2) a monomer represented by the following general formula (6) is preferable.
^{_{CH 2 = C (R 7)}} -R 8 (6)
(In the formula, R ⁷ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ⁸ represents an aromatic ring-containing hydrocarbon group having 6 to 22 carbon atoms.)
(C-1) As a (meth) acrylate having an alkyl group having 1 to 22 carbon atoms, methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, (iso or tertiary) butyl (Meth) acrylate, 2-ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) decyl (meth) acrylate, (iso) dodecyl (meth) acrylate, (iso) stearyl (meth) acrylate, Examples include heenyl (meth) acrylate.
(C-2) As the monomer represented by the formula (6), from the viewpoint of printing density, styrene, vinyl naphthalene, α-methylstyrene, vinyl toluene, ethyl vinyl benzene, 4-vinyl biphenyl, 1,1-diphenyl One or more selected from ethylene is preferred. Among these, from the viewpoint of printing density and storage stability, a styrene monomer that is one or more selected from the group consisting of styrene, α-methylstyrene, and vinyltoluene is more preferable.
The water-insoluble polymer may further contain other structural units.

  The water-insoluble polymer preferably has a structural unit represented by the formula (1), and further preferably has a structural unit represented by the formula (2). Further, the monomer represented by the formula (1-1) and (2-1) contains (a) a salt-forming group-containing monomer, (b) a macromer and / or (c) a hydrophobic monomer, if necessary. Those obtained by copolymerizing a monomer mixture (hereinafter referred to as “monomer mixture”) are preferred.

The monomer content represented by the formula (1-1) in the monomer mixture or the content of the structural unit represented by the formula (1) in the water-insoluble polymer is determined by the print density and glossiness when an aqueous ink is used. From the viewpoint of improvement in image quality, fixability and good dispersion stability, it is 10% by weight or more, preferably 10 to 80% by weight, more preferably 20 to 80% by weight, and particularly preferably 25 to 75% by weight.
The monomer content represented by the formula (2-1) in the monomer mixture or the content of the structural unit represented by the formula (2) in the water-insoluble polymer is determined by the print density and glossiness when an aqueous ink is used. From the viewpoint of improvement in image quality, fixing property and good dispersion stability, it is preferably 5 to 60% by weight, more preferably 8 to 55% by weight, and particularly preferably 10 to 50% by weight.

The content of the salt-forming group-containing monomer (a) in the monomer mixture (content as an unneutralized amount; the same applies hereinafter), or the content of the structural unit derived from the salt-forming group-containing monomer (a) in the water-insoluble polymer is From the viewpoint of improving the printing density and glossiness when using water-based ink and good dispersion stability, it is preferably 3 to 30% by weight, more preferably 5 to 25% by weight, and particularly preferably 5 to 20% by weight. is there.
The weight ratio of [the structural unit represented by the formula (1) / the structural unit derived from the salt-forming group-containing monomer (a)] is preferably 10/1 from the viewpoint of improving the dispersibility and gloss of the water-insoluble polymer. ˜1 / 1, more preferably 8/1 to 2/1.
The weight ratio of [the structural unit represented by the formula (2) / the structural unit derived from the salt-forming group-containing monomer (a)] is preferably 10/1 from the viewpoint of improving the dispersibility of the water-insoluble polymer and the print density. ~ 1/1, more preferably 5/1 to 1/1.
The content of the macromer (b) in the monomer mixture or the content of the structural unit derived from the macromer (b) in the water-insoluble polymer is preferably 0 to 40% by weight from the viewpoint of the print density when the aqueous ink is used. More preferably, it is 5-35 weight%, Most preferably, it is 5-30 weight%.
The content of the hydrophobic monomer (c) in the monomer mixture or the content of the structural unit derived from the hydrophobic monomer (c) in the water-insoluble polymer is determined from the viewpoint of printing density and dispersion stability when the water-based ink is used. Preferably it is 0 to 40 weight%, More preferably, it is 0 to 20 weight%.

When the water-insoluble polymer contains a structural unit derived from a salt-forming group-containing monomer, the salt-forming group is neutralized with a neutralizing agent described later. The degree of neutralization of the salt-forming group is preferably 10 to 200%, more preferably 20 to 150%, and particularly preferably 50 to 150%.
Here, the degree of neutralization can be determined by the following formula when the salt-forming group is an anionic group.
{[Weight of neutralizing agent (g) / equivalent of neutralizing agent] / [acid value of polymer (KOH mg / g) × polymer weight (g) / (56 × 1000)]} × 100
When the salt-forming group is a cationic group, the degree of neutralization can be determined by the following formula.
[[Weight of neutralizing agent (g) / equivalent of neutralizing agent] / [amine number of polymer (HCl mg / g) × polymer weight (g) / (36.5 × 1000)]] × 100
The acid value and amine value can be calculated from the structural unit of the water-insoluble polymer.
Alternatively, it can also be determined by a method in which a polymer is dissolved in an appropriate solvent (for example, methyl ethyl ketone) and titrated.

The weight average molecular weight of the water-insoluble polymer is preferably from 5,000 to 500,000, more preferably from 10,000 to 400,000, from the viewpoints of dispersion stability of the colorant, water resistance and dischargeability. 300,000 is particularly preferred.
The weight average molecular weight of the water-insoluble polymer was measured using polystyrene as a standard substance by gel permeation chromatography using dimethylformamide containing 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide as a solvent. Is done.

[Water-insoluble polymer particles containing colorant]
In the present invention, water-insoluble polymer particles containing a colorant are used. By using water-insoluble polymer particles containing the colorant, the colorant can be prevented from sinking into the paper, and the fluorine-containing fine particles can approach the colorant surface, and the surface scattering of light on the colorant surface It is considered that the efficiency of taking light into the colorant can be improved and the light absorption rate can be improved.
This is particularly effective when a dye is used.
The water-insoluble polymer particles containing the colorant are preferably obtained as an aqueous dispersion by the following steps (1) and (2).
Step (1): A step of dispersing a mixture containing a water-insoluble polymer, an organic solvent, a colorant, water and, if necessary, a neutralizing agent. Step (2): a step of removing the organic solvent. ) First, the water-insoluble polymer is dissolved in an organic solvent, and then a colorant, water, and, if necessary, a neutralizing agent, a surfactant and the like are added to the organic solvent and mixed to obtain an oil-in-water type. It is preferable to obtain a dispersion of In the mixture, the colorant is preferably 5 to 50% by weight, the organic solvent is preferably 10 to 70% by weight, the water-insoluble polymer is preferably 2 to 40% by weight, and the water is preferably 10 to 70% by weight. . When the water-insoluble polymer has a salt-forming group, it is preferable to use a neutralizing agent, but the degree of neutralization is not particularly limited. Usually, it is preferable that the liquid dispersion of the finally obtained water dispersion is neutral, for example, pH is 4.5 to 10. The pH can also be determined by the desired degree of neutralization of the water-insoluble vinyl polymer.

Preferred examples of the organic solvent include alcohol solvents, ketone solvents, and ether solvents, and those having a solubility in water of 50% by weight or less and 10% by weight or more at 20 ° C. are preferable.
Examples of alcohol solvents include ethanol, 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, isopropanol, acetone and methyl ethyl ketone are preferable, and methyl ethyl ketone is particularly preferable. These solvents can be used alone or in admixture of two or more.
As the neutralizing agent, an acid or a base can be used depending on the kind of the salt-forming group in the water-insoluble polymer.
Examples of neutralizers include hydrochloric acid, acetic acid, propionic acid, phosphoric acid, sulfuric acid, lactic acid, succinic acid, glycolic acid, gluconic acid, glyceric acid, and other acids, lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, methyl Examples include bases such as amine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, and triethanolamine.

There is no restriction | limiting in particular in the dispersion method of the mixture in the said process (1). It is preferable to carry out the main dispersion by applying a shear stress after preliminarily dispersing. In step (2), atomization is performed so that water-insoluble polymer particles having a desired average particle diameter are obtained.
When preliminarily dispersing the mixture, a commonly used mixing and stirring device such as an anchor blade can be used. Among the mixing and stirring apparatuses, Ultra Disper (Asada Steel Co., Ltd., trade name), Ebara Milder (Hagiwara Seisakusho Co., Ltd., trade name), TK Homomixer, TK Pipeline Mixer, TK Homojetter, TK Homomic Line Flow, High-speed agitating and mixing devices such as Philmix (special machine industry Co., Ltd., trade name), Clearmix (M Technique Co., trade name), and K-D Mill (Kinetic Dispersion Co., trade name) are preferred.
As means for giving the shear stress of this dispersion, for example, a kneader such as a roll mill, a bead mill, a kneader, an extruder, a high pressure homogenizer (Izumi Food Machinery Co., Ltd., trade name), a minilab 8.3H type (Rannie Co., trade name) Representative homo-valve type high-pressure homogenizer, Microfluidizer (Microfluidics, trade name), Nanomizer (Nanomizer, trade name), Ultimateizer (Sugino Machine, trade name), Genus PY (Shiramizu Chemical Co., Ltd.) Product name), DeBEE2000 (Nippon BEE Co., Ltd., trade name) and the like chamber type high pressure homogenizer. Among these, a high-pressure homogenizer is preferable from the viewpoint of reducing the particle size of the pigment contained in the mixture.

  In the step (2), water of the water-insoluble polymer particles containing a colorant having a desired average particle size is obtained by distilling the organic solvent from the dispersion obtained in the step (1) into an aqueous system. Obtain a dispersion. The organic solvent contained in the aqueous dispersion can be removed by a general method such as distillation under reduced pressure. The organic solvent in the aqueous dispersion containing the obtained water-insoluble polymer particles is substantially removed, and the amount of the organic solvent is preferably 0.1% by weight or less, more preferably 0.01% by weight or less. is there. It is preferable to remove coarse particles by filtering the obtained aqueous dispersion containing water-insoluble polymer particles. Coarse particles are not present, or even if they are present, the amount of the filter is preferably 1 to 10 μm, and more preferably 3 to 7 μm, in order to prevent clogging of the printer nozzles.

  The water dispersion of water-insoluble polymer particles containing a colorant is a dispersion in which a solid content of a water-insoluble polymer containing a colorant is dispersed in water as a main medium. Here, the form of the water-insoluble polymer particles containing the colorant is not particularly limited as long as the particles are formed of at least the colorant and the water-insoluble polymer. For example, a particle form in which a colorant is included in a water-insoluble polymer, a particle form in which a colorant is uniformly dispersed in a water-insoluble polymer, a particle form in which a colorant is exposed on the surface of a water-insoluble polymer particle, and the like are included.

The average particle size of the water-insoluble polymer particles containing the colorant is preferably 50 to 200 nm, more preferably 70 to 170 nm, and particularly preferably 90 to 150 nm from the viewpoints of dispersion stability and dischargeability. From the viewpoint of increasing the storage stability of the dispersion by reducing the coarse particles, D90 of the water-insoluble polymer particles containing the colorant (the cumulative 90% value calculated from the small particle side in the frequency distribution of scattering intensity). 350 nm or less is preferable, 300 nm or less is more preferable, and 270 nm or less is particularly preferable. The lower limit is preferably 100 nm or more from the viewpoint of ease of production. D10 of the water-insoluble polymer particles containing the colorant (cumulative value of 10% calculated from the small particle side in the frequency distribution of scattering intensity) is preferably 10 nm or more from the viewpoint of printing density and ease of production, 20 nm or more is further preferable, and 30 nm or more is particularly preferable.
In addition, average particle diameter, D90, D10 can be measured with the laser particle analysis system ELS-8000 (cumulant analysis) of the said Otsuka Electronics Co., Ltd. The measurement conditions are the same.

[Aqueous dispersion for inkjet recording and water-based ink]
The water-based ink of the present invention is an ink containing water as a main medium, and may contain additives such as a wetting agent, a dispersant, an antifoaming agent, an antifungal agent, and a chelating agent as necessary. There is no restriction | limiting in particular in the mixing method of each of these components.
In the aqueous dispersion of the present invention and in the aqueous ink, the content of fluorine-containing fine particles is preferably 0.1% by weight or more, more preferably 1% by weight or more, particularly preferably 3% by weight or more, and 5% by weight or more. The upper limit is preferably 25% by weight or less, more preferably 20% by weight or less, and particularly preferably 15% by weight or less. From these viewpoints, 0.1 to 25% by weight is preferable, 1 to 20% by weight is more preferable, and 3 to 15% by weight is particularly preferable.
The content (solid content) of the water-insoluble polymer particles containing the colorant in the aqueous dispersion of the present invention and in the water-based ink is usually preferably from 0.5 to 20 from the viewpoint of printing density and ejection stability. It is desirable to adjust so that it may become weight%, More preferably, it will be 1-15 weight%.

The weight ratio of the fluorine-containing fine particles to the colorant (colorant amount / fine particle amount) is preferably 1/10 to 10/1, more preferably 1/5 to 2/1, from the viewpoint of reducing the reflected light from the fine particles. 1/3 to 1/1 is particularly preferable.
The water content in the aqueous dispersion and the water-based ink of the present invention is preferably 30 to 90% by weight, more preferably 40 to 80% by weight.

[Inkjet recording method]
The aqueous ink for inkjet recording of the present invention is preferably used in an inkjet printing method for printing in one pass by an inkjet recording method. One-pass printing means that in the case of a line head, an image is formed by a single scan with the scanning direction of the inkjet head and the feeding direction of the printing object being the same direction. In the case of a serial head, the inkjet head Is scanned in both directions, and an image is formed while feeding the printing object in a direction perpendicular to the scanning direction of the inkjet head and without substantially re-landing (overlapping) the ink on the landed ink. That means.
When printing in one pass, the number of droplets ejected from the inkjet nozzle per unit area is reduced. Therefore, each drop is larger than printing in several passes, and one large drop has a small amount of ink per unit area compared to a few small dots. In the portion, there is a portion where the amount of ink is large and the ink easily penetrates. The water-based ink of the present invention is suitable for a one-pass printing method because it can promote surface wetting and spreading of the water-based ink on the printing paper and suppress the penetration of the water-based ink into the paper.

In the following production examples, examples and comparative examples, “parts” and “%” are “parts by weight” and “% by weight” unless otherwise specified.
Production Example 1 (Production of polymer)
In a reaction vessel, 20 parts of methyl ethyl ketone, 0.03 part of a polymerization chain transfer agent (2-mercaptoethanol), and 10% of 200 parts of each monomer shown in Table 1 were mixed and thoroughly replaced with nitrogen gas. A mixed solution was obtained.
On the other hand, the remaining 90% of the monomers shown in Table 1 were charged into the dropping funnel, and 0.27 part of the polymerization chain transfer agent, 60 parts of methyl ethyl ketone and a radical polymerization initiator [2,2′-azobis (2,4-dimethyl). Valeronitrile)] 1.2 parts were added and mixed, followed by sufficient nitrogen gas substitution to obtain a mixed solution.
Under a nitrogen atmosphere, the mixed solution in the reaction vessel was heated to 65 ° C. while stirring, and the mixed solution in the dropping funnel was gradually dropped over 3 hours. After 2 hours at 65 ° C. from the end of dropping, a solution obtained by dissolving 0.3 part of the radical polymerization initiator in 5 parts of methyl ethyl ketone was added, and further aged at 65 ° C. for 2 hours and 70 ° C. for 2 hours to obtain a polymer solution. It was.
The weight average molecular weight of the obtained polymer was measured by the above method. The results are shown in Table 1.

The details of the compounds shown in Table 1 are as follows.
Styrene macromer: (number average molecular weight: 6,000, polymerizable functional group: methacryloyloxy group): manufactured by Toa Gosei Co., Ltd., trade name: AS-6 (S)
PP-800: Polypropylene glycol monomethacrylate (propylene oxide average added mole number = 12, terminal: hydroxy group): manufactured by NOF Corporation, trade name: BLEMMER PP-800
43PAPE-600B: Polyethylene glycol polypropylene glycol monomethacrylate (ethylene oxide average addition mole number = 6, propylene oxide average addition mole number = 6, terminal: phenyl group): manufactured by NOF Corporation, trade name: BLEMMER 43PAPE-600B

Production Example 2 (Production of magnesium fluoride dispersion)
100 parts of magnesium fluoride (manufactured by Wako Pure Chemical Industries, Ltd., refractive index: 1.38, average particle size 135 nm), 104 parts of John Crill 61J (manufactured by Johnson Polymer Co., Ltd., solid content: 32.2%), and ion exchange 330 parts of water was added and mixed for 1 hour at 20 ° C. using a disper blade.
The obtained mixture was subjected to 10-pass dispersion treatment at a pressure of 200 MPa with a microfluidizer (trade name: M-140K, manufactured by Microfluidics).
The obtained dispersion was filtered with a 25 mL needleless syringe (Terumo Corporation) equipped with a 5 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.), and coarse particles Was removed to obtain an aqueous dispersion of magnesium fluoride having a solid concentration of 25%.

Example 2, Reference Example 1 and Reference Example 3
19 parts of the polymer obtained by drying the polymer solution obtained in Production Example 1 under reduced pressure was dissolved in 67 parts of methyl ethyl ketone, and 3.4 parts of neutralizing agent (5N aqueous sodium hydroxide solution) (degree of neutralization 60%) and ions were contained therein. 195 parts of exchanged water was added to neutralize the salt-forming group, and 75 parts of quinacridone pigment (CI Pigment Violet 19, Clariant Japan Co., Ltd., trade name: Hostaperm Red E5B02, refractive index: 2.0) was added. The mixture was mixed for 1 hour at 20 ° C. using a blade.
The obtained mixture was subjected to 10-pass dispersion treatment with a microfluidizer at a pressure of 200 MPa. After adding 250 parts of ion-exchanged water to the obtained dispersion and stirring, methyl ethyl ketone was removed at 60 ° C. under reduced pressure, a part of water was further removed, and 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.), and by removing coarse particles, pigment-containing polymer particles having a solid content concentration of 20% An aqueous dispersion was obtained (average particle size 117 nm).
In 35 parts of an aqueous dispersion of the obtained pigment-containing polymer particles, 40 parts of an aqueous dispersion of magnesium fluoride obtained in Production Example 2, 10 parts of glycerin, 7 parts of triethylene glycol monobutyl ether (TEGMBE), nonionic series Mixing 1 part of wetting agent (Nissin Chemical Industry Co., Ltd., trade name: Surfinol 465), 0.3 part of antifungal agent (trade name: Proxel XL2), and 6.7 parts of ion-exchanged water Then, the obtained mixed solution is filtered with a 25 mL needleless syringe equipped with a 1.2 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.) to remove coarse particles. As a result, water-based inks shown in Table 2 were obtained.

In Reference Example 1, instead of an aqueous dispersion of magnesium fluoride, a fluorine-containing polymer emulsion (manufactured by Nissin Chemical Industry Co., Ltd., product name: VINYBRAN FJ-311, refractive index: 1.51, average particle size 180 nm, Tg35 ° C.), or PTFE emulsion (manufactured by Asahi Glass Co., Ltd., product name: AD911, refractive index: 1.35, mean particle size 200 nm, except for using the drawings) for Tg measurement not in the same manner as in reference example 1, respectively The aqueous inks shown in Table 2 as Example 2 and Reference Example 3 were obtained.
Comparative Example 1
In Reference Example 1, a water-based ink shown in Table 2 was obtained in the same manner as in Reference Example 1 except that the aqueous dispersion of magnesium fluoride was not mixed and 46.7 parts of ion-exchanged water was mixed.
The average particle diameter of the aqueous dispersion was in the range of 0.05 to 0.2 μm in all of Example 2, Reference Example 1, Reference Example 3, and Comparative Example 1.

Next, Example 2, Reference Example 1, fine particles had use in Reference Example 3 and Comparative Example 1 were measured according to performance the following methods of the physical properties of the water-insoluble polymer particles containing a colorant, and the resulting ink. The results are shown in Table 2.
The average particle diameter of water-insoluble polymer particles containing fine particles and a colorant, the measurement method of D10 and D90, the average particle size of water-insoluble polymer particles containing fine particles and a colorant are determined by the laser particle analysis system ELS- from Otsuka Electronics Co., Ltd. Measured with 8000 (cumulant analysis). The measurement conditions are a temperature of 25 ° C., an angle between incident light and a detector of 90 °, and an integration count of 100. The refractive index of water (1.333) is input as the refractive index of the dispersion solvent. The measurement concentration was usually about 5 × 10 ⁻³ wt%.

Refractive Index Measurement Method A thin film (about 100 μm) is prepared by spin-coating a liquid in which fine particles are dispersed, and then the dispersion medium is removed with a vacuum dryer (105 ° C., −8000 Pa, 10 hours drying) to produce optical interference. Measurement (measurement wavelength: 589 nm) was performed with JIS K7142-1996 (Method B) using a formula film thickness measuring device (product name: Lambda Ace VM-1000, manufactured by Dainippon Screen Co., Ltd.).

Method for Measuring Tg In the present invention, the glass transition temperature (Tg) of a polymer refers to a value measured using a differential scanning calorimeter (DSC6200, manufactured by Seiko Instruments Inc.). Specifically, the measurement was performed under the conditions of the following continuous temperature programs 1 to 4, and the value measured by the temperature program 3 was defined as Tg. The reason for performing the measurement in the temperature program for temperature rise and cooling and using the measured value of the temperature program 3 is to ensure the reproducibility of the measured value.
Temperature program:
1.30 to 250 ° C .: Temperature rising rate 30 ° C./min, holding time 1 min
2.250 to -100 ° C .: cooling rate 30 ° C./min, holding time 30 min
3. −100 to 250 ° C .: Temperature rising rate 5 ° C./min, holding time 1 min
4.250 to 30 ° C .: cooling rate 30 ° C./min, holding time 2 min
Measurement of printing density Solid printing (printing condition = paper type: plain paper, mode setting) on commercially available plain paper (product name: Xerox 4024) using a Seiko Epson printer (model number: EM-930C, piezo method) : Fine, number of printing passes: once), left at 25 ° C. for 24 hours, and the printing density was measured 5 times with a Macbeth densitometer (product number: RD914, manufactured by Gretag Macbeth Co.) to obtain an average value. The higher the value, the higher the print density.

From the results shown in Table 2, it can be seen that all of the inks obtained in Example 2, Reference Example 1 and Reference Example 3 can impart high printing density to plain paper. Since the print density is a value printed in one pass, the print density is lower than usual.

Next, a standard ink was prepared, and the average penetration depth of the pigment was measured.
Standard test and measurement method of average penetration depth Printer manufactured by Seiko Epson Corporation [trade name: EM-930C (nozzle diameter φ38 μm, resolution 360 dpi, discharge frequency 14.4 kHz, fine mode, printing speed 9.2 ppm, liquid (Printing amount = paper type: plain paper, mode setting: fine (1 pass)) on plain paper (XEROX, product name: 4024) . After leaving at 25 ° C. for 24 hours, the solid printed part is cut with a cutter, and the penetration depth of the pigment is measured by observation with an ultra-deep shape measuring microscope (VK-8500, manufactured by Keyence Corporation) at any 10 points on the cut surface. The average value was taken as the average penetration depth.

Preparation of standard ink In the same manner as in Production Example 1, a polymer solution was obtained using the monomers shown in Table 3.
The details of the compounds shown in Table 3 are as follows.
Styrene macromer: manufactured by Toagosei Co., Ltd., trade name: AS-6S, number average molecular weight: 6000, polymerizable functional group: methacryloyloxy group / polyethylene glycol monomethacrylate (ethylene oxide average added mole number = 9): Shin-Nakamura Chemical Product name: NK ester M-90G
Polypropylene glycol monomethacrylate (average number of moles of propylene oxide added = 9): manufactured by NOF Corporation, trade name: BLEMER PP-500

25 parts of the polymer obtained by drying the polymer solution obtained above under reduced pressure was dissolved in 70 parts of methyl ethyl ketone, and 4.1 parts (5N aqueous sodium hydroxide solution) of 4.1 parts (neutralization degree 75%) and Add 230 parts of ion-exchanged water to neutralize the salt-forming group, and add 75 parts of quinacridone pigment (CI Pigment Violet 19, Clariant Japan Co., Ltd., trade name: Hostaperm Red E5B02). Mixed for hours. The obtained mixture was subjected to 10-pass dispersion treatment at a pressure of 200 MPa with a microfluidizer (trade name, manufactured by Microfluidics).
After adding 250 parts of ion-exchanged water to the obtained dispersion and stirring, methyl ethyl ketone was removed at 60 ° C. under reduced pressure, a part of water was further removed, and a 5 μm filter (acetylcellulose membrane, outer diameter: Pigment-containing vinyl polymer particles having a solid content concentration of 20% by filtering with a 25 mL needleless syringe (made by Terumo Co., Ltd.) attached with 2.5 cm, manufactured by Fuji Photo Film Co., Ltd., and removing coarse particles An aqueous dispersion was obtained. The average particle diameter of the pigment-containing vinyl polymer particles measured by the above-described measuring method is 110 nm, D10 [particle diameter from which the integrated particle size distribution (number basis) from the small particle diameter side becomes 10%] is 70 nm, D90 [small particle The particle size at which the cumulative particle size distribution (number basis) from the diameter side becomes 90%] was 171 nm.
To 37.35 parts (pure 7.47 parts) of an aqueous dispersion of the obtained pigment-containing vinyl polymer particles, 10 parts by weight of 2-pyrrolidone, 1 part by weight of Surfynol 465 (manufactured by Nissin Chemical Industry Co., Ltd.), fluorine 10 parts by weight (solid content) of the contained fine particles are mixed, and glycerin and water are added so that the viscosity becomes 4 mPa · s with an E-type viscometer (viscosity meter: RE80, manufactured by Toki Sangyo Co., Ltd.) to total 100 weight And filter with a 25 mL needleless syringe equipped with a 1.2 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.) to remove coarse particles and remove the standard ink. Produced. The E-type viscosity was measured under the conditions of a measurement temperature of 20 ° C., a measurement time of 1 minute, a rotation speed of 100 rpm, and a rotor standard (1 ° 34 ′ × R24).

(Measurement result of average penetration depth)
As the fluorine-containing fine particles, the fluorine-containing polymer emulsion used in Example 2 (manufactured by Nissin Chemical Industry Co., Ltd., trade name: Vinibrand FJ-311) and the PTFE emulsion used in Reference Example 3 (manufactured by Asahi Glass Co., Ltd., product name) : AD911), the average penetration depth of the pigment was 56 μm and 53 μm, respectively.
On the other hand, the average penetration depth of the pigment was 77 μm in the control ink that was replaced with ion-exchanged water correspondingly without using the fluorine-containing fine particles.

Claims (4)

Glass of polymer particles containing water-insoluble polymer particles containing a colorant and polymer particles having fluorine atoms, the polymer particles having fluorine atoms having a refractive index of 1.51 to 1.55 , and having fluorine atoms An aqueous dispersion for inkjet recording having a transition temperature (Tg) of 30 to 250 ° C. The weight ratio of polymer particles having a colorant and a fluorine atom [polymer particles having a colorant / fluorine atom] is 1 / 10-10 / 1, claim 1 water dispersion for ink-jet printing according. The aqueous dispersion for ink jet recording according to claim 1 or 2, wherein the polymer particles having fluorine atoms have an average particle diameter of 50 to 300 nm.   An aqueous ink for inkjet recording, comprising the aqueous dispersion for inkjet recording according to any one of claims 1 to 3.