JP6686375B2 - Ink, ink cartridge, recording device and recorded matter - Google Patents

Description

  The present invention relates to ink, an ink cartridge, a recording device, and a recorded matter.

  Inkjet recording methods are becoming popular because they have the advantages that the process is simpler than other recording methods, full colorization is easy, and high-resolution images can be obtained even with a simple device. ing. In this inkjet recording method, a small amount of ink is ejected by bubbles generated by heat, pressure generated by using piezo or electrostatic force, and it is made to adhere to a recording medium such as paper and quickly dried (or recording It is a method of forming an image by making it penetrate into a medium), and its application is expanding to personal and industrial printers and printing.

In such an ink jet recording system, a water-based ink or a pigment ink using a water-soluble dye as a colorant is used, but from the viewpoint of weather resistance and water resistance, a pigment ink is usually used in recent years.
Further, in recent years, development of water-based pigment inks for high-speed continuous book machines has been in progress, and pigment inks capable of obtaining high-quality images even when printed at high speed have been demanded. In a high-speed continuous book machine, since the main target medium is offset coated paper (also called coated paper), unlike plain paper, the mechanism for obtaining high image quality is different.

  In plain paper, the image density is increased by fixing the pigment on the surface of the paper and increasing the pigment coverage of the paper surface. Therefore, when the plain paper is designed to be an ink that easily reacts with the chemicals on the paper, the ink reacts with and agglomerates with the chemicals on the surface of the paper to increase the image density. On the other hand, in the offset coated paper, the smoothness of the image surface of the printed material improves the glossiness and the image density. For coated paper, the smaller the pigment particle size, the smoother the surface of the image area, the higher the glossiness, and the higher the image density. Further, when the reactivity between the ink and the paper is lower, the ink film is leveled on the image, so that the glossiness and the image density are improved.

  According to the publicly known examples up to now, as disclosed in Patent Document 1, there is known an example in which the pigment is retained on the surface of paper by utilizing the reactivity of calcium in the paper and the ink to improve the image density of plain paper. Has been. However, when such an ink is printed on coated paper, when the ink lands on the paper, the pigment agglomerates quickly and the ink film does not level, so the surface does not become smooth and the image density There was a problem that was low.

  Further, in the pigment ink, a water-dispersible resin may be added to the ink for the purpose of imparting a glossy feeling. Acrylic silicone resin and polyurethane resin are often used as the resin. If the compatibility of the pigment and the copolymer (dispersion resin) that disperses it with the water-dispersible resin is improved, the affinity will be high and it will be easy to mix, the surface of the image area when printed will be smooth, and the glossiness will be improved. However, the image density is also improved.

  According to a known example up to now, in Patent Document 2, by using an ink containing resin particles and a wax, it is possible to prevent the pigment from penetrating into pores of the low-absorption coated paper. Known examples have been reported in which both the image density on paper and the fixability are compatible. However, in this known example, since the self-dispersion pigment is used and the droplets do not level on the coated paper, the image portion does not become smooth and the image density does not increase. In addition, since it contains wax, the storage stability is poor.

  Further, Patent Document 3 reports that the use of a copolymer having a methacrylate and a urethane bond improves the image density on plain paper due to the effect of the polar component. However, in the case of such a copolymer, there is a problem in that the adsorptivity to the pigment becomes low and the storage stability deteriorates.

  Further, Patent Document 4 describes that the image density on plain paper is improved by bringing a pigment having an acidic group and a basic resin having an amino group into contact with each other on the surface. It is not smooth enough and the image density is low. In addition, there is a problem that storage stability is poor due to aggregation of pigments in the ink.

  Therefore, an object of the present invention is to provide an ink that secures the dispersion stability of the ink, obtains good storage stability, and obtains good image density even with offset coated paper.

  In order to solve the above problems, the present invention is an ink containing water, a colorant and a copolymer, wherein the copolymer has a structural unit represented by the following general formula (1), The ink has a coating layer formed on a support containing cellulose pulp as a main component, and a solid image is formed at a deposition amount of 500 to 700 mg / A4 on a recording medium having a surface roughness of 30 nm or more and 35 nm or less. In addition, the surface roughness Ra is 25 nm or less.

(In the general formula (1), R2 represents a hydrogen atom or a methyl group, and L represents an alkylene group having 2 to 12 carbon atoms.)

  According to the present invention, it is possible to provide an ink that secures the dispersion stability of the ink, obtains good storage stability, and obtains good image density even with offset coated paper.

It is a perspective view which shows an example of the recording device which concerns on this invention typically. FIG. 3 is a perspective view schematically showing an example of an ink cartridge according to the present invention. It is a figure which shows an example of FT-IR spectrum of a styrene acrylic resin particle.

  Hereinafter, the ink, the ink cartridge, the recording apparatus, and the recorded matter according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments described below, and other embodiments, additions, modifications, deletions and the like can be modified within the scope that those skilled in the art can contemplate, and any mode Also in the above, as long as the action and effect of the present invention are exhibited, it is included in the scope of the present invention.

  The present invention is an ink containing water, a coloring material and a copolymer, wherein the copolymer has a structural unit represented by the following general formula (1), and the ink contains cellulose pulp as a main component. When a solid image is formed with a coating amount of 500 to 700 mg / A4 on a recording medium having a coating layer formed on a support having a surface roughness of 30 nm or more and 35 nm or less, the surface roughness Ra is 25 nm. It is characterized by the following.

(In the general formula (1), R2 represents a hydrogen atom or a methyl group, and L represents an alkylene group having 2 to 12 carbon atoms.)

  The L is an alkylene group having 2 to 18 carbon atoms, preferably an alkylene group having 2 to 16 carbon atoms, and more preferably an alkylene group having 2 to 12 carbon atoms. In the general formula (1), the naphthyl group present at the terminal via L has an excellent pigment adsorbing power due to π-π stacking with the pigment that is a coloring material in the aqueous ink (hereinafter, also referred to as ink). Have.

  Further, the ink of the present invention preferably has a structural unit represented by the following general formula (2).

(In the general formula (2), R1 represents a hydrogen atom or a methyl group, and X represents a hydrogen atom or a cation.)

In the above general formula (2), X is a hydrogen atom or a cation, and in the case of a cation, oxygen adjacent to the cation exists as O ⁻ . As the cation, sodium ion, potassium ion, lithium ion, tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, tetrapentylammonium ion, tetrahexylammonium ion, triethylmethylammonium ion, tributylmethyl ion Ammonium ion, trioctylmethylammonium ion, 2-hydroxyethyltrimethylammonium ion, tris (2-hydroxyethyl) methylammonium ion, propyltrimethylammonium ion, hexyltrimethylammonium ion, octyltrimethylammonium ion, nonyltrimethylammonium ion, decyltrimethylammonium ion Ammonium ion Dodecyl trimethyl ammonium ion, tetradecyl trimethyl ammonium ion, hexadecyl trimethyl ammonium ion, octadecyl trimethyl ammonium ion, didodecyl dimethyl ammonium ion, ditetradecyl dimethyl ammonium ion, dihexadecyl dimethyl ammonium ion, dioctadecyl dimethyl ammonium ion, ethyl hexadecyl Dimethyl ammonium ion, ammonium ion, dimethyl ammonium ion, trimethyl ammonium ion, monoethyl ammonium ion, diethyl ammonium ion, triethyl ammonium ion, monoethanol ammonium ion, diethanol ammonium ion, triethanol ammonium ion, methyl ethanol ammonium Ion, methyldiethanolammonium ion, dimethylethanolammonium ion, monopropanolammonium ion, dipropanolammonium ion, tripropanolammonium ion, isopropanolammonium ion, morpholinium ion, N-methylmorpholinium ion, N-methyl-2- Pyrrolidonium ion, 2-pyrrolidonium ion and the like can be mentioned.

  As can be understood from the description of the above general formulas (1) and (2), the structural unit represented by the above general formulas (1) and (2) is typically a terminal naphthyl group pendant via L. It may be the main chain of a copolymer having a pendant group such as a side chain carboxyl group. Needless to say, the case where a part is contained in the side chain is not excluded.

  The molar ratio of the structural unit represented by the general formula (1) to the structural unit represented by the general formula (2) is 1: 0.1 to 1:10 from the viewpoint of the ability to adsorb the pigment. It is preferably, more preferably 1: 0.3 to 1: 5, still more preferably 1: 0.5 to 1: 3. Within the preferred range, the image density and storage stability can be improved.

The number average molecular weight and the weight average molecular weight of the copolymer in the present invention are preferably 500 to 10,000 and 1,500 to 30,000, respectively, in terms of polystyrene.
The content of the copolymer in the ink is preferably 0.9% by mass or more and 1.8% by mass or less in terms of solid content ratio.

The copolymer of the present invention can have a repeating unit composed of other polymerizable monomer, in addition to the structural units represented by the general formulas (1) and (2).
The other polymerizable monomer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a polymerizable hydrophobic monomer, a polymerizable hydrophilic monomer, and a polymerizable surfactant. Can be mentioned.

  Examples of the polymerizable hydrophobic monomer include unsaturated ethylene monomers having an aromatic ring such as α-methylstyrene, 4-t-butylstyrene, and 4-chloromethylstyrene; methyl (meth) acrylate, (meth) ) Ethyl acrylate, n-butyl (meth) acrylate, dimethyl maleate, dimethyl itaconic acid, dimethyl fumarate, lauryl (meth) acrylate (C12), tridecyl (meth) acrylate (C13), (meth) Tetradecyl acrylate (C14), pentadecyl (meth) acrylate (C15), hexadecyl (meth) acrylate (C16), heptadecyl (meth) acrylate (C17), nonadecyl (meth) acrylate (C19), (meth) Eicosyl acrylate (C20), Henicosyl acrylate (C21), Alkyl (meth) acrylate such as docosyl (meth) acrylate (C22); 1-heptene, 3,3-dimethyl-1-pentene, 4,4-dimethyl-1-pentene, 3-methyl-1-hexene, 4 -Methyl-1-hexene, 5-methyl-1-hexene, 1-octene, 3,3-dimethyl-1-hexene, 3,4-dimethyl-1-hexene, 4,4-dimethyl-1-hexene, 1 -Nonene, 3,5,5-trimethyl-1-hexene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene , 1-nonadecene, 1-eicosene, 1-dococene, and other unsaturated ethylene monomers having an alkyl group. These may be used alone or in combination of two or more.

  Examples of the polymerizable hydrophilic monomer include maleic acid or a salt thereof, monomethyl maleate, itaconic acid, monomethyl itaconate, fumaric acid, 4-styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, or Anionic unsaturated ethylene monomers such as unsaturated ethylene monomers containing phosphoric acid, phosphonic acid, alendronic acid or etidronic acid; 2-hydroxyethyl (meth) acrylate, diethylene glycol mono (meth) acrylate, triethylene glycol mono (Meth) acrylate, tetraethylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, (meth) acrylamide, N-methylol (meth) acrylamide, N-vinylformamide, N-vinylacetate Toamido, N- vinylpyrrolidone, acrylamide, N, N- dimethylacrylamide, N-t-butylacrylamide, N- octyl acrylamide, such as a non-ionic ethylenically unsaturated monomer such as N-t-octyl acrylamide.

  Examples of the polymerizable surfactant include anionic or nonionic surfactants having at least one radically polymerizable unsaturated double bond group in the molecule.

Examples of the anionic surfactant, ammonium sulfate base _(-SO 3 _-NH ^{4 +)} hydrocarbon compound having a sulfate group and an allyl group such as _{(-CH 2 -CH = CH 2)} , ammonium sulfate base (-SO ₃ A hydrocarbon compound having a sulfate group such as —NH ₄ ⁺ ) and a methacrylic group [—CO—C (CH ₃ ) ═CH ₂ ], or a sulfate group such as an ammonium sulfate group (—SO ₃ —NH ₄ ⁺ ) and 1 - an aromatic hydrocarbon compound having a propenyl group (-CH = _CH 2 _{CH 3)} and the like. Specific examples thereof include Eleminol JS-20 and RS-300 manufactured by Sanyo Kasei Co., Ltd., Aqualon KH-10, Aqualon KH-1025, Aqualon KH-05, Aqualon HS-10 and Aqualon HS manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. -1025, Aqualon BC-0515, Aqualon BC-10, Aqualon BC-1025, Aqualon BC-20, and Aqualon BC-2020.

The non-ionic surfactant, 1-propenyl (-CH = _CH 2 _{CH 3)} and polyoxyethylene group _{[- (C 2 H 4 O)} n -H ] a hydrocarbon compound or an aromatic having Hydrocarbon compounds are mentioned. Specific examples thereof include Aqualon RN-20, Aqualon RN-2025, Aqualon RN-30, and Aqualon RN-50 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Latemur PD-104, Latemur PD-420, and Latemul PD manufactured by Kao Corporation. -430, Latemur PD-450 and the like.

  As shown in the following reaction formulas (1) to (3), the copolymer of the present invention is prepared by first mixing naphthalenecarbonyl chloride (A-1) and an excess amount of a diol compound with an acid acceptor such as amine or pyridine. A condensation reaction is performed in the presence to obtain a naphthalenecarboxylic acid hydroxyalkyl ester (A-2). Then, after reacting 2-methacryloyloxyethyl isocyanate (A-3) with the above (A-2) to obtain a monomer (A-4), a (meth) acrylic acid monomer in the presence of a radical polymerization initiator. By copolymerizing with (A-5), the copolymer (A-6) of the present invention can be obtained. Here, the weight average molecular weight of the monomer (A-4) is 357 to 596 since L in the general formula (2) is an alkylene group having 2 to 18 carbon atoms and R2 is a hydrogen atom or a methyl group. is there.

(In the above reaction formula, R1 represents a hydrogen atom or a methyl group, X represents a hydrogen atom or a cation, and L represents an alkylene group having 2 to 12 carbon atoms.)

The radical polymerization initiator is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxydicarbonate, peroxyester, cyano-based azobisisobutyronitrile, azobis (2-methylbutyronitrile), Examples thereof include azobis (2,2′-isovaleronitrile) and non-cyano dimethyl-2,2′-azobisisobutyrate. Among these, organic peroxides and azo compounds are preferable, and azo compounds are particularly preferable, because the molecular weight is easily controlled and the decomposition temperature is low.
The content of the radical polymerization initiator is not particularly limited and may be appropriately selected depending on the purpose, but is preferably 1 to 10 mass% with respect to the total amount of the polymerizable monomers.

An appropriate amount of a chain transfer agent may be added to adjust the molecular weight of the polymer.
Examples of the chain transfer agent include mercaptoacetic acid, mercaptopropionic acid, 2-propanethiol, 2-mercaptoethanol, thiophenol, dodecylmercaptan, 1-dodecanethiol, and thioglycerol.

  The polymerization temperature is appropriately selected depending on the intended purpose without any limitation, but it is preferably 50 ° C to 150 ° C, more preferably 60 ° C to 100 ° C. The polymerization time is not particularly limited and may be appropriately selected depending on the purpose, but is preferably 3 to 48 hours.

<Ink>
Hereinafter, the organic solvent, water, coloring material, resin, additive and the like used in the ink will be described.

  The type of resin particles contained in the ink can be appropriately changed, but styrene-acrylic resin particles are preferable, and those having a large ratio of styrene in the ratio (molar ratio) of styrene and acrylic are more preferable. As a method for synthesizing styrene acrylic, an emulsion polymerization method can be mentioned. Although the mechanism is not clear as to the reason why styrene-acrylic resin containing a large amount of styrene is good, when a styrene-acrylic resin containing a large amount of styrene is used, the compatibility with the copolymer and pigment in the present invention is excellent, and thus the printed image surface is smooth. It is estimated that this is because the image density becomes high.

For media such as offset coated paper, it is considered that the image density is improved by reducing the surface roughness Ra when the image area is observed by an AFM (atomic force microscope). It is considered that the ink in the highly compatible state has a smoother film when printed. It is considered that the structure having a benzene ring such as styrene has a structure similar to that of the copolymer of the present invention and has high affinity.
Examples of the offset coated paper include a recording medium having a coating layer formed on a support containing cellulose pulp as a main component and having a surface roughness of 30 nm or more and 35 nm or less.

  The ink of the present invention has a coating layer formed on a support containing cellulose pulp as a main component, and a solid image is formed on a recording medium having a surface roughness of 30 nm or more and 35 nm or less at an adhesion amount of 500 to 700 mg / A4. When formed, it has a surface roughness Ra of 25 nm or less. If the surface roughness Ra is larger than 25 nm, the dispersion stability of the ink and the good image density on the offset coated paper cannot both be achieved.

  Here, in the present invention, the measured values of the surface roughness of the printed image and the surface roughness of the recording medium are defined as the values measured using an AFM (atomic force microscope). The size of the visual field when quantifying the surface roughness is 1 μm square. Techniques / apparatuses such as an optical microscope, a confocal microscope, and an AFM are often used in the measurement of the surface roughness Ra, but when the surface roughness Ra is measured with a 1 μm square field of view using the AFM, The highest correlation with image density is obtained. The AFM measurement at this time is preferably performed in the tapping mode. When the measurement is performed in the contact mode, there is a problem that the image surface is destroyed. Further, since the measurement is performed in air, the measurement may be performed in the non-contact mode, but since the resolution at the atomic image level is not required, the measurement in the non-contact mode is not particularly required.

Further, when an image having a smooth surface is formed, glossiness is also improved. As a method of measuring the glossiness, for example, a glossiness meter PG-IIM may be used. The gloss meter may be able to specify the angle between the incident light and the specular reflection light, and in the present invention, the value of 60 degree gloss is recorded. Other values such as 20 degree gloss and 80 degree gloss may be measured. A gloss meter that can simultaneously measure glossiness at various angles is common.
In the present invention, the solid image preferably has a 60 degree gloss value of 35 or more.

When obtaining the ratio of styrene and acrylic of the resin particles, it is preferable to use FT-IR. The resin film in a state where the solvent is evaporated may be formed and the measurement may be performed by the ATR method. As the FT-IR device, for example, a FT-IR device manufactured by Thermo Scientific Co. may be used. The styrene-derived peak A appears near 698 cm ⁻¹ , and the acrylic-derived peak B appears near 1730 cm ⁻¹ . From the viewpoint of the effect of the compatibility on the image density and the storage stability, the peak area ratio of (A / B) is preferably 3 or more and 5 or less, and more preferably 4 or more and 5 or less. In the above preferable range, the image density and storage stability can be improved.

Here, the baseline for obtaining the peak area A ^is defined as a line connecting the minimum point of the minimum point and ^{685cm -1 ~695cm} -1 of 705cm ^-1 ~715cm -1, for obtaining the peak area B based line ^is defined as a line connecting the minimum point of the minimum point and ^{1695cm -1 ~1715cm} -1 of 1740cm ^-1 ~1760cm -1. The resolution at the time of measurement is not particularly limited, but it is usually set to 4 cm ⁻¹ in many cases. The smaller the resolution value, the better the ability to separate the peaks. The number of times of integration is not particularly specified, but it is usually set to 32 times or 64 times. The larger the number of times of integration, the better the S / N ratio of the spectrum. However, if the number of times of integration is too large, the S / N ratio will be saturated, and the effect will be less prominent.
An example of FT-IR spectrum of styrene acrylic resin particles is shown in FIG.

  Although the lower limit value of the surface roughness Ra observed using the AFM is not particularly set, from the results of the examination so far, when the image observation was performed by the AFM in the visual field of 1 μm square, the surface roughness Ra was 9 nm. Since there are no cases where the value is lower than this, it is considered that about 9 nm is probably the lower limit that can be reached in principle.

  The content of the styrene acrylic resin particles in the ink is preferably 0.5% by mass or more and 8.0% by mass or less in terms of solid content. Even if the resin particles are not added, the surface roughness Ra of the image may become smooth, but it is considered that the above-mentioned region is a region compatible with the storage stability and glossiness of the ink.

  The mass ratio (S / K) of the content S of the styrene acrylic resin particles to the ink and the content K of the copolymer to the ink is 0.05 to 8.00 in terms of solid content. It is more preferably 0.40 or more and 7.00 or less.

The volume average particle diameter of the resin particles is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10 nm or more and 1,000 nm or less from the viewpoint of obtaining good fixability and high image hardness. It is more preferably 200 nm or less and more preferably 10 nm or more and 100 nm or less.
The volume average particle size can be measured using, for example, a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell KK).

<Organic solvent>
The organic solvent used in the present invention is not particularly limited, and a water-soluble organic solvent can be used. Examples thereof include polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds.
Specific examples of the water-soluble organic solvent include, for example, ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butane. Diol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol , 2,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, Glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3- Polyhydric alcohols such as sundiol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3-pentanediol and petriol, ethylene glycol mono Polyhydric alcohol alkyl ethers such as ethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monophenyl ether, ethylene glycol monoethyl ether Polyhydric alcohol aryl ethers such as benzyl ether, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl- -Pyrrolidone, 1,3-dimethyl-2-imidazolidinone, nitrogen-containing heterocyclic compounds such as ε-caprolactam, γ-butyrolactone, formamide, N-methylformamide, N, N-dimethylformamide, 3-methoxy-N, Amides such as N-dimethylpropionamide and 3-butoxy-N, N-dimethylpropionamide, amines such as monoethanolamine, diethanolamine and triethylamine, sulfur-containing compounds such as dimethylsulfoxide, sulfolane and thiodiethanol, propylene carbonate, Examples include ethylene carbonate.
It is preferable to use an organic solvent having a boiling point of 250 ° C. or less because it not only functions as a wetting agent but also obtains good drying properties.

A polyol compound having 8 or more carbon atoms and a glycol ether compound are also preferably used. Specific examples of the polyol compound having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol.
Specific examples of glycol ether compounds include polyhydric alcohol alkyls such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether. Ethers; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

  The polyol compound having 8 or more carbon atoms and the glycol ether compound can improve the ink permeability when paper is used as the recording medium.

  The content of the organic solvent in the ink is not particularly limited and may be appropriately selected depending on the purpose, but from the viewpoint of ink drying properties and ejection reliability, 10% by mass or more and 60% by mass or less is preferable, 20 mass% or more and 60 mass% or less are more preferable.

<Water>
The content of water in the ink is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10% by mass or more and 90% by mass or less and 20% by mass or less from the viewpoint of the drying property of the ink and the ejection reliability. % To 60% by mass is more preferable.

<Color material>
The color material is not particularly limited, and pigments and dyes can be used.
An inorganic pigment or an organic pigment can be used as the pigment. These may be used alone or in combination of two or more. Also, a mixed crystal may be used.
Examples of pigments that can be used include black pigments, yellow pigments, magenta pigments, cyan pigments, white pigments, green pigments, orange pigments, luster color pigments such as gold and silver, and metallic pigments.
As an inorganic pigment, in addition to titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, carbon black produced by a known method such as a contact method, a furnace method, or a thermal method. Can be used.
Further, as the organic pigment, an azo pigment, a polycyclic pigment (for example, a phthalocyanine pigment, a perylene pigment, a perinone pigment, an anthraquinone pigment, a quinacridone pigment, a dioxazine pigment, an indigo pigment, a thioindigo pigment, an isoindolinone pigment, a quinofuraron pigment, etc.) , Dye chelates (eg, basic dye chelates, acid dye chelates, etc.), nitro pigments, nitroso pigments, aniline black, etc. can be used. Among these pigments, those having a good affinity with the solvent are preferably used. In addition, hollow resin particles and hollow inorganic particles can also be used.
Specific examples of the pigment include carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, and channel black, or copper and iron (CI pigment black 11) for black. , Metal oxides such as titanium oxide, and organic pigments such as aniline black (CI Pigment Black 1).
Further, 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. , 108, 109, 110, 117, 120, 138, 150, 153, 155, 180, 185, 213, 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, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, C.I. I. Pigment Violet 1 (Rhodamine Lake), 3, 5: 1, 16, 19, 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue), 15: 1, 15: 2, 15: 3, 15: 4 (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 dye is not particularly limited, and an acid dye, a direct dye, a reactive dye, and a basic dye can be used, and one kind may be used alone, or two or more kinds may be used in combination.
Examples of the dye include C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Red 52, 80, 82, 249, 254, 289, C.I. I. Acid Blue 9,45,249, C.I. I. Acid Black 1, 2, 24, 94, C.I. I. Food Black 1, 2, C.I. I. Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, 173, C.I. I. Direct Red 1, 4, 9, 80, 81, 225, 227, C.I. I. Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, C.I. I. Dilectd Black 19, 38, 51, 71, 154, 168, 171, 195, C.I. I. Reactive Red 14, 32, 55, 79, 249, C.I. I. Reactive Black 3, 4, and 35 may be mentioned.

  The content of the coloring material in the ink is preferably 0.1% by mass or more and 15% by mass or less, and more preferably 1% by mass or more and 10% by mass, from the viewpoints of improving the image density, good fixing property and ejection stability. It is the following.

  The particle size of the solid content in the ink is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoint of enhancing image quality such as ejection stability and image density, the maximum frequency in terms of maximum number is converted. Is preferably 20 nm or more and 1000 nm or less, and more preferably 20 nm or more and 150 nm or less. The solid content includes resin particles, pigment particles, and the like. The particle size can be measured using a particle size analyzer (Nanotrack Wave-UT 151, manufactured by Microtrack Bell Co., Ltd.).

<Additives>
If necessary, a surfactant, a defoaming agent, an antiseptic / antifungal agent, an anticorrosive agent, a pH adjusting agent and the like may be added to the ink.

<Surfactant>
As the surfactant, any of a silicone-based surfactant, a fluorine-based surfactant, an amphoteric surfactant, a nonionic surfactant, and an anionic surfactant can be used.
The silicone surfactant is not particularly limited and can be appropriately selected according to the purpose. Among them, those that do not decompose even at high pH are preferable, and examples thereof include side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and side-chain both-end modified polydimethylsiloxane. Those having an oxyethylene group or a polyoxyethylene polyoxypropylene group are particularly preferable because they exhibit good properties as an aqueous surfactant. Further, as the silicone-based surfactant, a polyether-modified silicone-based surfactant can also be used, and examples thereof include a compound having a polyalkylene oxide structure introduced into the side chain of the Si moiety of dimethylsiloxane.
Examples of the fluorinated surfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic acid compound, a perfluoroalkyl phosphoric acid ester compound, a perfluoroalkyl ethylene oxide adduct and a perfluoroalkyl ether group in the side chain. A polyoxyalkylene ether polymer compound is particularly preferable because it has a low foaming property. Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid and perfluoroalkyl sulfonate. Examples of the perfluoroalkylcarboxylic acid compound include perfluoroalkylcarboxylic acid and perfluoroalkylcarboxylic acid salts. Examples of the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in its side chain include a sulfuric acid ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in its side chain and a perfluoroalkyl ether group in its side chain. Examples thereof include salts of polyoxyalkylene ether polymers. As counter ions of the salt in these fluorine-based surfactants, Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ , NH (CH ₂ CH ₂ OH) are used. _{3 and the} like.
Examples of the amphoteric surfactant include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.
Examples of the nonionic surfactant include polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkylamine, polyoxyethylene alkylamide, polyoxyethylene propylene block polymer, sorbitan fatty acid ester, polyoxyethylene sorbitan. Examples thereof include fatty acid esters and ethylene oxide adducts of acetylene alcohol.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, lauryl salt, and salt of polyoxyethylene alkyl ether sulfate.
These may be used alone or in combination of two or more.

The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and side-modified polydimethylsiloxane. Examples thereof include polydimethyl siloxane modified at both chain ends, and a polyether modified silicone surfactant having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group shows good properties as an aqueous surfactant. preferable.
As such a surfactant, those synthesized appropriately may be used, or commercially available products may be used. Commercially available products can be obtained from, for example, Big Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Toray Dow Corning Silicone Co., Ltd., Nippon Emulsion Co., Ltd., Kyoeisha Kagaku Co., Ltd., and the like.
The polyether-modified silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the polyalkylene oxide structure represented by the general formula (S-1) may be represented by dimethylpolyethylene. Examples thereof include those introduced into the side chain of the Si portion of siloxane.

(However, in the general formula (S-1), m, n, a, and b represent an integer. R and R'represent an alkyl group or an alkylene group.)
As the above polyether-modified silicone-based surfactant, commercially available products can be used, for example, KF-618, KF-642, KF-643 (Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5602, SS-. 1906EX (Japan Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (Toray Dow Corning Silicone Co., Ltd.), BYK-33, BYK-387 (Big Chemie Co., Ltd.), TSF4440, TSF4452, TSF4453 (Toshiba Silicon Co., Ltd.), etc. are mentioned.

The fluorine-based surfactant is preferably a fluorine-substituted compound having 2 to 16 carbon atoms, and more preferably a fluorine-substituted compound having 4 to 16 carbon atoms.
Examples of the fluorinated surfactant include perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain. Among these, polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain are preferable because they have a low foaming property, and the fluorine-based compounds represented by the general formula (F-1) and the general formula (F-2) are particularly preferable. Surfactants are preferred.

In the compound represented by the general formula (F-1), m is preferably an integer of 0 to 10 and n is preferably an integer of 0 to 40 in order to impart water solubility.
_{C n F 2n + 1- CH 2} CH (OH) CH 2 -O- (CH 2 CH 2 O) a -Y ··· Formula (F-2)
In the compound represented by the general formula (F-2), Y is H, or CnF _{2n + 1} and n is an integer of 1 to 6, or CH ₂ CH (OH) CH ₂ —CnF _{2n + 1} and n is 4 to 6 An integer, or CpH _{2p + 1} and p is an integer of 1 to 19. a is an integer of 4-14.
A commercially available product may be used as the above-mentioned fluorine-based surfactant. Examples of this commercially available product include 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 (all manufactured by Sumitomo 3M Limited); Megafac F-470, F -1405, F-474 (all manufactured by Dainippon Ink and Chemicals, Inc.); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR (all , DuPont); FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW (all are corporations. (Manufactured by Male Co., Ltd.), Polyfox PF-136A, PF-156A, PF-151N, PF-154, PF-159 (manufactured by OMNOVA), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.), and the like. Among them, FS-300 manufactured by Du Pont, FT-110 manufactured by Neos Co., Ltd., and FT-250 from the viewpoint that the excellent printing quality, particularly the color developability, the penetrability to paper, the wettability, and the leveling property are remarkably improved. , FT-251, FT-400S, FT-150, FT-400SW, Polyfox PF-151N manufactured by Omnova Co., Ltd. and Unidyne DSN-403N manufactured by Daikin Industries, Ltd. are particularly preferable.

  The content of the surfactant in the ink is appropriately selected depending on the intended purpose without any limitation, but it is 0.001 mass% from the viewpoint of excellent wettability and ejection stability and improving image quality. % Or more and 5 mass% or less is preferable, and 0.05 mass% or more and 5 mass% or less is more preferable.

<Antifoam>
The defoaming agent is not particularly limited, and examples thereof include a silicone defoaming agent, a polyether defoaming agent, and a fatty acid ester defoaming agent. These may be used alone or in combination of two or more. Among these, a silicone-based defoaming agent is preferable because of its excellent foam breaking effect.

<Antiseptic and fungicide>
The antiseptic / antifungal agent is not particularly limited, and examples thereof include 1,2-benzisothiazolin-3-one.

<Rust preventive>
The rust preventive agent is not particularly limited, and examples thereof include acid sulfite and sodium thiosulfate.

<PH adjuster>
The pH adjuster is not particularly limited as long as the pH can be adjusted to 7 or higher, and examples thereof include amines such as diethanolamine and triethanolamine.

The physical properties of the ink are not particularly limited and may be appropriately selected depending on the purpose. For example, the viscosity, surface tension, pH and the like are preferably in the following ranges.
The viscosity of the ink at 25 ° C. is preferably 5 mPa · s or more and 30 mPa · s or less, from the viewpoint that the printing density and character quality are improved, and that good ejection properties can be obtained, and 5 mPa · s or more and 25 mPa · s or less are preferable. More preferable. Here, as the viscosity, for example, a rotary viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.) can be used. The measurement conditions are 25 ° C., standard cone rotor (1 ° 34 ′ × R24), sample liquid volume 1.2 mL, rotation speed 50 rpm, and 3 minutes.
The surface tension of the ink is preferably 35 mN / m or less at 25 ° C., and more preferably 32 mN / m or less at 25 ° C., since the ink is preferably leveled on the recording medium and the drying time of the ink is shortened.
The pH of the ink is preferably 7 to 12, and more preferably 8 to 11 from the viewpoint of preventing the corrosion of the metal member with which the ink comes into contact.

<Pretreatment liquid>
The pretreatment liquid contains a coagulant, an organic solvent, and water, and may contain a surfactant, an antifoaming agent, a pH adjusting agent, an antiseptic / antifungal agent, an antirust agent, etc., if necessary.
As the organic solvent, the surfactant, the defoaming agent, the pH adjuster, the antiseptic / antifungal agent, and the rust preventive agent, the same materials as those used for the ink can be used, and other materials used for the known treatment liquid can be used. .
The type of aggregating agent is not particularly limited, and examples thereof include water-soluble cationic polymers, acids, polyvalent metal salts and the like.

<Post-treatment liquid>
The post-treatment liquid is not particularly limited as long as it can form a transparent layer. The post-treatment liquid can be obtained by selecting and mixing an organic solvent, water, a resin, a surfactant, an antifoaming agent, a pH adjusting agent, an antiseptic / antifungal agent, an anticorrosive agent, etc., if necessary. Further, the post-treatment liquid may be applied to the entire recording area formed on the recording medium, or may be applied only to the area where the ink image is formed.

<Recording medium>
The recording medium used for recording is not particularly limited, and examples thereof include plain paper, glossy paper, special paper, cloth, film, OHP sheet, and general-purpose printing paper.

<Recorded matter>
The recorded matter of the present invention is a recorded matter having an image formed on a recording medium, wherein the recording medium has a coating layer formed on a support containing cellulose pulp as a main component and has a surface roughness of It is 30 nm or more and 35 nm or less, and the image has a coloring material and a copolymer having the structural unit represented by the general formula (1), and has a surface roughness Ra of 25 nm or less. The recorded matter of the present invention can be recorded by an inkjet recording apparatus and an inkjet recording method, for example.

<Recording device, recording method>
The recording apparatus of the present invention has an ink ejecting unit that ejects (inks) the ink of the present invention from a recording head (ejection head) to record an image on a recording medium. Further, the recording method of the present invention has an ink jetting step of applying a stimulus to the ink of the present invention through an ink jetting means to jet the ink from the print head to print an image on a print medium.
The ink of the present invention can be suitably used for various recording apparatuses using an inkjet recording method, such as printers, facsimile machines, copying machines, printer / fax / copier composite machines, and three-dimensional modeling apparatuses.
In the present invention, the recording device and the recording method are a device capable of ejecting ink, various treatment liquids, and the like onto a recording medium, and a method of recording using the device. The recording medium means a medium to which ink or various treatment liquids can be attached even temporarily.
This recording device can include not only a head portion for ejecting ink, but also means for feeding, conveying, and discharging a recording medium, and other devices such as a pre-processing device and a post-processing device. .
The recording device and the recording method may have a heating means used in the heating step and a drying means used in the drying step. The heating means and the drying means include, for example, means for heating and drying the printing surface or the back surface of the recording medium. The heating means and the drying means are not particularly limited, but, for example, a warm air heater or an infrared heater can be used. Heating and drying can be performed before printing, during printing, after printing, and the like.
Further, the recording device and the recording method are not limited to those in which a significant image such as a character or a figure is visualized by ink. For example, the thing which forms patterns, such as a geometric pattern, and the thing which models a three-dimensional image are also included.
Further, the recording apparatus includes both a serial type apparatus that moves the ejection head and a line type apparatus that does not move the ejection head unless otherwise limited.
Further, this recording device is not limited to a desktop type, and can be used as a wide recording device capable of printing on an A0 size recording medium, or for example, a continuous paper wound in a roll as a recording medium. It also includes a continuous form printer.
An example of the recording device will be described with reference to FIGS. FIG. 1 is a perspective explanatory view of the device. FIG. 2 is a perspective view of the main tank. The image forming apparatus 400 as an example of the recording apparatus is a serial type image forming apparatus. A mechanism section 420 is provided in the exterior 401 of the image forming apparatus 400. Each ink storage portion 411 of the main tank 410 (410k, 410c, 410m, 410y) for each color of black (K), cyan (C), magenta (M), and yellow (Y) is packed with, for example, an aluminum laminate film. It is formed of a member. The ink container 411 is housed in a container case 414 made of plastics, for example. As a result, the main tank 410 is used as an ink cartridge for each color.
On the other hand, a cartridge holder 404 is provided on the inner side of the opening when the cover 401c of the apparatus body is opened. The main tank 410 is detachably attached to the cartridge holder 404. As a result, the ink discharge ports 413 of the main tank 410 communicate with the ejection heads 434 for each color via the supply tubes 436 for each color, and ink can be ejected from the ejection heads 434 to the recording medium.

This recording device may include not only a part for ejecting ink, but also a device called a pre-processing device or a post-processing device.
As one mode of the pretreatment device and the posttreatment device, as in the case of the inks of black (K), cyan (C), magenta (M), yellow (Y), etc., the pretreatment liquid and the posttreatment liquid are included. There is a mode in which a liquid storage section and a liquid ejection head are added and a pretreatment liquid and a posttreatment liquid are ejected by an inkjet recording method.
As another aspect of the pretreatment apparatus and the posttreatment apparatus, there is an aspect in which a pretreatment apparatus and a posttreatment apparatus other than the ink jet recording method, for example, a blade coating method, a roll coating method, and a spray coating method are provided.

  The method of using the ink is not limited to the ink jet recording method and can be widely used. In addition to the inkjet recording method, for example, a blade coating method, a gravure coating method, a bar coating method, a roll coating method, a dip coating method, a curtain coating method, a slide coating method, a die coating method, a spray coating method and the like can be mentioned.

The use of the ink of the present invention is not particularly limited and can be appropriately selected according to the purpose. For example, it can be applied to printed matter, paints, coating materials, bases and the like. Furthermore, it can be used not only as a two-dimensional character or image by using as ink, but also as a three-dimensional modeling material for forming a three-dimensional three-dimensional image (three-dimensional model).
As a three-dimensional modeling device for modeling a three-dimensional molded object, a known one can be used and is not particularly limited, but for example, one provided with an ink containing means, a supplying means, a discharging means, a drying means, etc. is used. be able to. The three-dimensional molded item includes a three-dimensional molded item obtained by overcoating with ink. Further, it also includes a molded product obtained by processing a structure to which ink is applied on a substrate such as a recording medium. The molded product is, for example, a recording product or a structure formed in a sheet shape or a film shape, which is subjected to a molding process such as heat drawing or punching process, and is, for example, an automobile, an OA device, or an electric machine. -Suitable for applications such as electronic devices, meters for cameras, panels for operation parts, etc., after molding the surface after molding.

  Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples. In the following, “parts” and “%” represent “parts by mass” and “mass%” unless otherwise specified.

<Measurement of molecular weight of copolymer>
It measured on GPC (Gel Permeation Chromatography) on the following conditions.
・ Device: GPC-8020 (manufactured by Tosoh Corporation)
・ Column: TSK G2000HXL and G4000HXL (manufactured by Tosoh Corporation)
・ Temperature: 40 ℃
・ Solvent: THF (tetrahydrofuran)
Flow rate: 1.0 mL / min 1 mL of a copolymer having a concentration of 0.5% by mass was injected, and a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample was used from the molecular weight distribution of the copolymer measured under the above conditions. Then, the number average molecular weight Mn and the weight average molecular weight Mw of the copolymer were calculated.

(Example 1)
<Synthesis of Copolymer (1)>
62.0 g (525 mmol) of 1,6-hexanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in 700 mL of methylene chloride, and 20.7 g (262 mmol) of pyridine was added. A solution prepared by dissolving 50.0 g (262 mmol) of 2-naphthalenecarbonyl chloride (manufactured by Tokyo Kasei Co., Ltd.) in 100 mL of methylene chloride was added dropwise to this solution while stirring over 2 hours, and then stirred at room temperature for 6 hours. . After the obtained reaction solution was washed with water, the organic phase was isolated, dried over magnesium sulfate, and the solvent was distilled off. The residue was purified by silica gel column chromatography using a mixed solvent of methylene chloride / methanol (volume ratio 98/2) as an eluent to obtain 52.5 g of 2-naphthoic acid-2-hydroxyhexyl ester.

  Next, 42.1 g (155 mmol) of 2-naphthoic acid-2-hydroxyethyl ester was dissolved in 80 mL of dry methyl ethyl ketone and heated to 60 ° C. A solution of 24.0 g (155 mmol) of 2-methacryloyloxyethyl isocyanate (Showa Denko KK, Karenz MOI) dissolved in 20 mL of dry methyl ethyl ketone was added dropwise to this solution while stirring for 1 hour, and then 70 ° C. It was stirred for 12 hours. After cooling to room temperature, the solvent was distilled off. The residue was purified by silica gel column chromatography using methylene chloride / methanol (volume ratio 99/1) mixed solvent as an eluent, and 57.0 g of the following monomer (1 having the structure represented by the following structural formula: ) Got.

Then, 1.20 g (16.7 mmol) of acrylic acid (manufactured by Aldrich) and 4.45 g (10.4 mmol) of the above monomer (1) were dissolved in 40 mL of dry methyl ethyl ketone to prepare a monomer solution (above). The molar ratio of monomer (1) and acrylic acid is 1: 1.6). After heating 10% of the monomer solution to 75 ° C. under an argon stream, 0.273 g (1.67 mmol) of 2,2′-azoiso (butyronitrile) (manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in the remaining monomer solution. Was added dropwise over 1.5 hours, and the mixture was stirred at 75 ° C for 6 hours. After cooling to room temperature, the obtained reaction solution was dropped into hexane. The precipitated copolymer was filtered and dried under reduced pressure to obtain 8.13 g of copolymer (1) (weight average molecular weight (Mw): 19400, number average molecular weight (Mn): 8200).
Then, the obtained 2.00 g of the copolymer was dissolved in a tetraethylammonium hydroxide aqueous solution so that the concentration of the copolymer was 2.38% and the pH was 8.0, and the copolymer ( An aqueous solution for pigment dispersion of 1) was prepared.

<Preparation of Pigment Dispersion (1)>
To the prepared 84.0 g of the copolymer (1) aqueous solution, 16.0 g of carbon black (NIPEX150, manufactured by Degussa) was added and stirred for 12 hours. The obtained mixture was circulated and dispersed for 1 hour at a peripheral speed of 10 m / s using a disk type bead mill (KDL type, manufactured by Shinmaru Enterprises Co., Ltd., media: a zirconia ball having a diameter of 0.1 mm) was used, and then the pore size was 1 The mixture was filtered through a 0.2 μm membrane filter, and a prepared amount of ion-exchanged water was added to obtain 95.0 g of pigment dispersion (1) (pigment solid content concentration: 16%).

<Preparation of water-dispersible styrene acrylic resin (1)>
In a separable flask equipped with a stirrer, a reflux condenser and a thermometer, 250 g of deionized water and an addition-cleavage type chain transfer agent (RAFT agent) as a compound having a living radical polymerization property [1- (O-ethylzantyl)] Ethyl] benzene (1.04 g) and ethyl acrylate (1.69 g) were charged, and nitrogen bubbling was performed for 1 hour and 30 minutes to remove dissolved oxygen in the liquid. After completion of bubbling, the temperature was raised to 70 ° C. while stirring with a stirrer. When the internal temperature reached 70 ° C., 5 g of a 10% sodium persulfate aqueous solution was added as a water-soluble radical initiator. After 20 minutes, a mixed solution of 32.06 g of ethyl acrylate and 11.25 g of methacrylic acid was added dropwise so that the addition was completed in 3 hours. After completion of the dropping, the mixture was aged at 70 ° C. for 4 hours to complete the polymerization of the aqueous polymer (1).

  A separable flask equipped with a stirrer, a reflux condenser and a thermometer was charged with 203.4 g of deionized water and 14.8 g of the aqueous polymer (1) and stirred until the whole became uniform. With stirring, 25% aqueous ammonia (0.65 g) was added to obtain a colorless and transparent aqueous resin aqueous solution. To this, 25 g of Chemipearl W400 (low molecular weight polyolefin emulsion, solid content 40%, manufactured by Mitsui Chemicals, Inc.) was added and stirred until the whole became uniform. Furthermore, 22.5 g of styrene was added with stirring, and nitrogen bubbling was carried out for 1 hour and 30 minutes in order to remove dissolved oxygen in the system while stirring. After completion of bubbling, the temperature was raised to 70 ° C. When the internal temperature reached 70 ° C., 0.32 g of a 10% aqueous solution of 4,4′-azobis (4-cyanopentanoic acid) was added as a water-soluble radical initiator, and the polymerization was completed after 6 hours. The obtained water-dispersible styrene acrylic resin (1) had a Tg of 45 ° C. and an average particle diameter (volume average particle diameter, the same applies hereinafter) of 82 nm.

<Preparation of ink (1)>
Using the prepared pigment dispersion (1) and the water-dispersible styrene acrylic resin (1), the pigment solid content concentration is 6% in the ink, and the water-dispersible resin solid content concentration is 3. Ink (1) was prepared with the following formulation so as to be 5%.
・ 2-Ethyl-1,3-hexanediol: 2.0%
・ 2-Ethylhexyl oxetane: 41.0%
・ TEGO WET-270: 1.0%
-N-cyclohexyl-2-aminoethanesulfonic acid: 0.1%
-2-amino-2-ethyl-1,3-propanediol: 0.1%
・ 1,2,3-Benzotriazole: 0.1%
・ High pure water: Remaining amount

(Example 2)
<Synthesis of Copolymer (2)>
In the synthesis of the copolymer (1), the copolymerization was performed in the same manner as in Example 1 except that the molar ratio of the monomer (1) to acrylic acid was changed to monomer (1): acrylic acid = 1: 0.5. Polymer (2) (weight average molecular weight (Mw): 19100, number average molecular weight (Mn): 7100) was obtained, and an aqueous solution for dispersing the pigment of the copolymer (2) was prepared in the same manner as in Example 1.

<Preparation of pigment dispersion (2)>
A pigment dispersion (2) having a pigment solid content concentration of 16% was prepared in the same manner as in Example 1 except that the copolymer (2) was used.

<Preparation of ink (2)>
Using the prepared pigment dispersion (2) and the water-dispersible styrene acrylic resin (1), the pigment solid content concentration is 6% in the ink, and the water-dispersible resin solid content concentration is 3. Ink (2) was prepared with the same formulation as in Example 1 so as to be 5%.

(Example 3)
<Synthesis of Copolymer (3)>
In the synthesis of the copolymer (1), the copolymer (in the same manner as in Example 1 except that the molar ratio of the monomer (1) to acrylic acid was changed to monomer (1): acrylic acid = 1: 3 ( 3) (weight average molecular weight (Mw): 18700, number average molecular weight (Mn): 7900) was obtained, and an aqueous solution for dispersing the pigment of the copolymer (3) was prepared in the same manner as in Example 1.

<Preparation of Pigment Dispersion (3)>
A pigment dispersion (3) having a pigment solid content concentration of 16% was prepared in the same manner as in Example 1 except that the copolymer (3) was used.

<Preparation of ink (3)>
2. Using the prepared pigment dispersion (3) and the water-dispersible styrene acrylic resin (1), the pigment solid content concentration is 6% in the ink, and the water-dispersible resin solid content concentration is 3. Ink (3) was prepared according to the same formulation as in Example 1 so that the concentration was 5%.

(Example 4)
<Synthesis of Copolymer (4)>
In the synthesis of the copolymer (1), the copolymer (in the same manner as in Example 1 except that the molar ratio of the monomer (1) to acrylic acid was changed to monomer (1): acrylic acid = 1: 4 ( 4) (weight average molecular weight (Mw): 19300, number average molecular weight (Mn): 8200) was obtained, and an aqueous solution for dispersing the pigment of the copolymer (4) was prepared in the same manner as in Example 1.

<Preparation of Pigment Dispersion (4)>
A pigment dispersion (4) having a pigment solid content concentration of 16% was prepared in the same manner as in Example 1 except that the copolymer (4) was used.

<Preparation of ink (4)>
2. Using the prepared pigment dispersion (4) and the water-dispersible styrene acrylic resin (1), the pigment solid content concentration is 6% in the ink, and the water-dispersible resin solid content concentration is 3. Ink (4) was prepared according to the same formulation as in Example 1 so that the concentration was 5%.

(Example 5)
<Synthesis of Copolymer (5)>
In the synthesis of the copolymer (1), the copolymerization was performed in the same manner as in Example 1 except that the molar ratio of the monomer (1) and acrylic acid was changed to monomer (1): acrylic acid = 1: 0.4. Polymer (5) (weight average molecular weight (Mw): 18500, number average molecular weight (Mn): 6800) was obtained, and an aqueous solution for dispersing the pigment of the copolymer (5) was prepared in the same manner as in Example 1.

<Preparation of pigment dispersion (5)>
A pigment dispersion (5) having a pigment solid content concentration of 16% was prepared in the same manner as in Example 1 except that the copolymer (5) was used.

<Preparation of ink (5)>
2. Using the prepared pigment dispersion (5) and the water-dispersible styrene acrylic resin (1), the pigment solid content concentration is 6% in the ink, and the water-dispersible resin solid content concentration is 3. Ink (5) was prepared according to the same formulation as in Example 1 so as to be 5%.

(Example 6)
<Synthesis of Copolymer (6) Using Bisphosphonic Acid>
30 g of monomer (1) and 6 g of N- [3- (dimethylamino) propyl] acrylamide (manufactured by Tokyo Kasei Kogyo KK, DMAPAA) were placed in a reaction vessel equipped with a gas inlet tube, a thermometer and a reflux condenser. It was dissolved in 500 g of N, N-dimethylformamide (DMF). An aqueous solution prepared by dissolving 24 g of methacrylamide methylenediphosphonic acid ditetraethylammonium salt monomer in 100 g of ion-exchanged water was added thereto, and heated to 75 ° C. under an argon atmosphere. Then, a DMF solution prepared by dissolving 1.7 g of 2,2′-azobisisobutyronitrile (manufactured by Tokyo Kasei Co., Ltd.) in 30 g of DMF was added dropwise with a dropping funnel. Stirring was continued at 75 ° C. for 6 hours and then cooled to terminate the polymerization.

The insoluble material in the reaction solution was removed, and the reaction solution was washed three times with a mixed solution of tetrahydrofuran and hexane (volume ratio 40: 100). Next, the solvent was removed by an evaporator and then vacuum dried at 60 ° C. to obtain 53 g of resin.
When 1 g of this resin was dissolved in 100 g of ion-exchanged water and titrated with 0.1 NKOH methanol solution using thymolphthalein as an indicator, the acid value was determined to be 43 mg KOH.
A 10% by mass resin aqueous solution was prepared while neutralizing with an aqueous tetraethylammonium hydroxide solution. When the viscosity of this solution was measured at 25 ° C., it was 2.4 mPa · s. The 10% by mass resin aqueous solution thus obtained was used for preparing a pigment dispersion. In the same manner as in Example 1, an aqueous solution for dispersing the pigment of the copolymer (6) was prepared.

<Preparation of Pigment Dispersion (6)>
A pigment dispersion (6) having a pigment solid content concentration of 16% was prepared in the same manner as in Example 1 except that the copolymer (6) was used.

<Preparation of ink (6)>
Using the prepared pigment dispersion (6) and the water-dispersible styrene acrylic resin (1), the pigment solid content concentration is 6% in the ink, and the water-dispersible resin solid content concentration is 3. Ink (6) was prepared according to the same formulation as in Example 1 so that the concentration was 5%.

(Example 7)
<Synthesis of Copolymer (7)>
A monomer (2) having a structure represented by the following structural formula was prepared in the same manner as in Example 1 except that ethylene glycol (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 6-hexanediol. Obtained.

  Next, using acrylic acid and the monomer (2) obtained above, a copolymer (weight average molecular weight (Mw): 18700, number average molecular weight (Mn): 6100) was obtained in the same manner as in Example 1. Then, an aqueous solution for dispersing the pigment of the copolymer (7) was prepared in the same manner as in Example 1.

<Preparation of pigment dispersion (7)>
A pigment dispersion (7) having a pigment solid content concentration of 16% was prepared in the same manner as in Example 1 except that the copolymer (7) was used.

<Preparation of ink (7)>
Using the prepared pigment dispersion (7) and the water-dispersible styrene acrylic resin (1), the pigment solid content concentration is 6% in the ink, and the water-dispersible resin solid content concentration is 3. Ink (7) was prepared according to the same formulation as in Example 1 so that the concentration was 5%.

(Example 8)
<Synthesis of Copolymer (8)>
In the synthesis of the copolymer (1), it is represented by the following structural formula in the same manner as in Example 1 except that 1,12-dodecanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 6-hexanediol. A monomer (3) having a structure having

  Next, using acrylic acid and the obtained monomer (3), a copolymer (8) was prepared in the same manner as in Example 1 (weight average molecular weight (Mw): 18700, number average molecular weight (Mn): 6700). Then, an aqueous solution for dispersing the pigment of the copolymer (8) was prepared in the same manner as in Example 1.

<Preparation of pigment dispersion (8)>
A pigment dispersion (8) having a pigment solid content concentration of 16% was prepared in the same manner as in Example 1 except that the copolymer (8) was used.

<Preparation of ink (8)>
Using the prepared pigment dispersion (8) and the water-dispersible styrene acrylic resin (1), the pigment solid content concentration is 6% in the ink, and the water-dispersible resin solid content concentration is 3. Ink (8) was prepared according to the same formulation as in Example 1 so that the concentration was 5%.

(Example 9)
<Synthesis of Water-Dispersible Styrene Acrylic Resin (2)>
As the olefin polymer (1), 1000 g of propylene-butene-ethylene terpolymer (Bestplast 750, manufactured by Degussa Japan), 100 g of maleic anhydride-modified polypropylene wax (high wax NP0555A, manufactured by Mitsui Chemicals, Inc.) and olein. 40 g of potassium acidate (KS soap, manufactured by Kao Corporation) was mixed and supplied at a rate of 3000 g / hour from a hopper of a twin-screw extruder (made by Ikegai Tekko Co., Ltd., PCM-300, L / D = 40). A 17% aqueous solution of potassium hydroxide was continuously supplied at a rate of 120 g / hour (4% based on the whole) from a supply port provided in the vent portion of the extruder, and continuously extruded at a superheating temperature of 200 ° C. The extruded resin mixture was cooled to 90 ° C with a jacketed static mixer installed in the same extruder, and further put into warm water at 80 ° C to obtain 99% yield, 40% solid content, and pH 12 olefin-based polymer. A combined aqueous dispersion (1) was obtained.

  A separable flask equipped with a stirrer, a reflux condenser and a thermometer was charged with 203.4 g of deionized water and 14.8 g of the aqueous polymer (1) obtained in Example 1, and stirred until the whole became uniform, With stirring, 0.65 g of 25% aqueous ammonia was added to obtain a colorless transparent aqueous resin aqueous solution. To this, 25 g of the aqueous dispersion (1) of the olefin polymer was added and stirred until the whole became uniform. Further, a mixed solution of 28.1 g of styrene and 12.4 g of butyl acrylate was added under stirring, and nitrogen bubbling was carried out for 1 hour and 30 minutes in order to remove dissolved oxygen in the system while stirring. After completion of bubbling, the temperature was raised to 70 ° C. When the internal temperature reached 70 ° C., 0.32 g of a 4,4′-azobis (4-cyanopentanoic acid) 10% aqueous solution was added as a water-soluble radical initiator, and after 6 hours, the polymerization was completed and water was added. A dispersible styrene acrylic resin (2) was obtained. The water-dispersible styrene acrylic resin (2) thus obtained had a Tg of 25 ° C. and an average particle diameter of 72 nm.

<Preparation of ink (9)>
Using the pigment dispersion (1) prepared in Example 1 and the water-dispersible styrene acrylic resin (2), the pigment solid content concentration was 6% in the ink, and the solid content of the water-dispersible resin was Ink (9) was prepared according to the same formulation as in Example 1 so that the concentration was 3.5%.

(Example 10)
<Synthesis of Water-Dispersible Styrene Acrylic Resin (3)>
A separable flask equipped with a stirrer, a reflux condenser and a thermometer was charged with 250 g of deionized water, and nitrogen bubbling was carried out for 1 hour and 30 minutes to remove dissolved oxygen in the solution. After completion of bubbling, the temperature was raised to 70 ° C. while stirring with a stirrer. When the internal temperature reached 70 ° C., 5 g of a 10% sodium persulfate aqueous solution was added as a water-soluble radical initiator. After 20 minutes, a mixed solution of 33.75 g of ethyl acrylate and 11.25 g of methacrylic acid was added dropwise over 3 hours so as to cover the mixture. After the dropwise addition was completed, aging was carried out at 70 ° C. for 4 hours to complete the polymerization of the aqueous polymer (2). The solid content of the obtained aqueous dispersion was 14.3%.

  A separable flask equipped with a stirrer, a reflux condenser and a thermometer was charged with 207.8 g of deionized water and 15.7 g of the aqueous polymer (2), and stirred until the whole became homogeneous. Under stirring, 25% ammonia water 0.65 g was added to obtain a colorless transparent aqueous resin aqueous solution. To this, 25 g of the aqueous dispersion (1) of the olefin polymer obtained in Example 9 was added and stirred until the whole became uniform. Further, a mixed solution of 14.1 g of styrene and 12.4 g of butyl acrylate was added with stirring, and nitrogen bubbling was carried out for 1 hour and 30 minutes to remove dissolved oxygen in the system while stirring. After completion of bubbling, the temperature was raised to 70 ° C. When the internal temperature reached 70 ° C., 0.32 g of a 4,4′-azobis (4-cyanopentanoic acid) 10% aqueous solution was added as a water-soluble radical initiator, and after 6 hours, the polymerization was completed and water was added. A dispersible styrene acrylic resin (3) was obtained. The water-dispersible styrene acrylic resin (3) thus obtained had a Tg of 25 ° C. and an average particle diameter of 77 nm.

<Preparation of ink (10)>
Using the pigment dispersion (1) prepared in Example 1 and the water-dispersible styrene acrylic resin (3), the pigment solid content concentration was 6% in the ink, and the solid content of the water-dispersible resin was Ink (10) was prepared according to the same formulation as in Example 1 so that the concentration was 3.5%.

(Example 11)
<Synthesis of Water-Dispersible Styrene Acrylic Resin (4)>
A separable flask equipped with a stirrer, a reflux condenser and a thermometer was charged with 207.8 g of deionized water and 15.7 g of the aqueous polymer (2) obtained in Example 10 and stirred until the whole became uniform. With stirring, 25% aqueous ammonia (0.65 g) was added to obtain a colorless and transparent aqueous resin aqueous solution. To this, 25 g of Chemipearl W400 (low molecular weight polyolefin emulsion, solid content 40%, manufactured by Mitsui Chemicals, Inc.) was added and stirred until the whole became uniform. Furthermore, 31.5 g of styrene was added with stirring, and nitrogen bubbling was carried out for 1 hour and 30 minutes while stirring to remove dissolved oxygen in the system. After completion of bubbling, the temperature was raised to 70 ° C. When the internal temperature reached 70 ° C., 0.32 g of a 4,4′-azobis (4-cyanopentanoic acid) 10% aqueous solution was added as a water-soluble radical initiator, and after 6 hours, the polymerization was completed and water was added. A dispersible styrene acrylic resin (4) was obtained. The water-dispersible styrene acrylic resin (4) thus obtained had a Tg of 55 ° C. and an average particle diameter of 80 nm.

<Preparation of Ink (11)>
Using the pigment dispersion (1) prepared in Example 1 and the water-dispersible styrene acrylic resin (4), the pigment solid content concentration was 6% in the ink, and the solid content of the water-dispersible resin was Ink (11) was prepared according to the same formulation as in Example 1 so that the concentration was 3.5%.

(Example 12)
<Synthesis of Water-Dispersible Styrene Acrylic Resin (5)>
A separable flask equipped with a stirrer, a reflux condenser and a thermometer was charged with 217.3 g of deionized water and 2.3 g of sodium dodecylsulfonate as an anionic dispersant and stirred until the whole became uniform. Under stirring, 0.65 g of 25% aqueous ammonia was added, and 25 g of the aqueous dispersion (1) of the olefin polymer obtained in Example 9 was added and stirred until the whole became uniform. Further, a mixed solution of 8.1 g of styrene and 12.4 g of butyl acrylate was added under stirring, and nitrogen bubbling was carried out for 1 hour and 30 minutes in order to remove dissolved oxygen in the system while stirring. After completion of bubbling, the temperature was raised to 70 ° C. When the internal temperature reached 70 ° C., 0.32 g of a 4,4′-azobis (4-cyanopentanoic acid) 10% aqueous solution was added as a water-soluble radical initiator, and after 6 hours, the polymerization was completed and water was added. A dispersible styrene acrylic resin (5) was obtained. The water-dispersible styrene acrylic resin (5) thus obtained had a Tg of 4 ° C. and an average particle diameter of 92 nm.

<Preparation of ink (12)>
Using the pigment dispersion (1) prepared in Example 1 and the water-dispersible styrene acrylic resin (5), the pigment solid content concentration was 6% in the ink, and the solid content of the water-dispersible resin was Ink (12) was prepared according to the same formulation as in Example 1 so that the concentration was 3.5%.

(Example 13)
<Preparation of Ink (13)>
Using the pigment dispersion (1) prepared in Example 1 and the water-dispersible styrene acrylic resin (1), the pigment solid content concentration was 6% in the ink, and the solid content of the water-dispersible resin was Ink (13) was prepared according to the same formulation as in Example 1 so that the concentration was 0.5%.

(Example 14)
<Preparation of Ink (14)>
Using the pigment dispersion (1) prepared in Example 1 and the water-dispersible styrene acrylic resin (1), the pigment solid content concentration was 6% in the ink, and the solid content of the water-dispersible resin was Ink (14) was prepared according to the same formulation as in Example 1 so that the concentration was 8.0%.

(Example 15)
<Preparation of ink (15)>
Using the pigment dispersion (1) prepared in Example 1 and the water-dispersible styrene acrylic resin (1), the pigment solid content concentration was 6% in the ink, and the solid content of the water-dispersible resin was Ink (15) was prepared with the same formulation as in Example 1 so that the concentration was 0.1%.

(Example 16)
<Preparation of ink (16)>
Using the pigment dispersion (1) prepared in Example 1 and the water-dispersible styrene acrylic resin (1), the pigment solid content concentration was 6% in the ink, and the solid content of the water-dispersible resin was Ink (16) was prepared according to the same formulation as in Example 1 so that the concentration was 9.0%.

(Comparative Example 1)
<Synthesis of Copolymer (9) Using Benzyl Methacrylate>
182 g of N, N-dimethylformamide (DMF, manufactured by Kanto Chemical Co., Inc.) was placed in a reaction vessel equipped with a gas introduction tube, a thermometer, and a reflux condenser under an argon atmosphere, and heated to 75 ° C. There, 223 g of an aqueous solution prepared by dissolving 30 g of acrylic acid (manufactured by Aldrich) in 193 g of water, 24 g of benzyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) and N- [3- (dimethylamino) propyl] acrylamide (Tokyo Chemical Industry Co., Ltd. (Manufactured by the company / hereinafter abbreviated as DMAPAA) 212 g of DMF solution prepared by dissolving 6 g in 182 g of DMF and 2,2′-azobisisobutyronitrile (manufactured by Tokyo Chemical Industry Co., Ltd./hereinafter abbreviated as AIBN) 5.4 g of 182 g. 187.4 g of a DMF solution dissolved in DMF was added in 12 batches every 30 minutes. After all the ingredients were added, stirring was continued at 75 ° C. for 4 hours, followed by cooling to terminate the polymerization. In the same manner as in Example 1, an aqueous solution for dispersing the pigment of the copolymer (9) was prepared.

<Preparation of pigment dispersion (9)>
A pigment dispersion (9) having a pigment solid content concentration of 16% was prepared in the same manner as in Example 1 except that the copolymer (9) containing benzyl methacrylate was used.
<Preparation of Ink (17)>
Using the prepared pigment dispersion (9) and the water-dispersible styrene acrylic resin (1), the pigment solid content concentration is 6% in the ink, and the water-dispersible resin solid content concentration is 3. Ink (17) was prepared according to the same formulation as in Example 1 so that the concentration was 5%.

(Comparative example 2)
<Synthesis of water-dispersible acrylic silicone resin (1)>
1.2 parts of acrylic acid as the monomer (A), 6 g of Sila Ace 210 (vinyltrimethoxysilane, manufactured by Chisso Corporation) as the monomer (B), 40.5 g of methyl methacrylate as the monomer (3), and 2-ethylhexyl acrylate 51 .3 g, 1.0 g of acrylamide, 1.5 g of Aqualon KH-20 (a reactive emulsifier manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as an emulsifier, and 53.1 g of ion-exchanged water were emulsified with a batch homomixer to prepare a monomer prepolymer. An emulsion was prepared and placed in the dropping tank.

  A four-necked flask having a volume of 2 L equipped with a reflux condenser, a stirrer, a thermometer, a nitrogen introduction tube, and a raw material introduction port was used as a reaction vessel, and 89.4 g of ion-exchanged water was put into the reaction vessel and stirred while introducing nitrogen. Meanwhile, the liquid temperature was raised to 60 ° C. Next, 0.5 g of Aqualon KH-20 as an alkylphenol ether-based reactive emulsifier was added to the reaction vessel, and at the same time, 6 g of a 5% ammonium persulfate (hereinafter, abbreviated as "APS") aqueous solution (as ammonium persulfate, 0. 3 g) was added.

Ten minutes after adding the 5% APS aqueous solution to the reaction vessel, the monomer pre-emulsion was continuously added dropwise from the dropping tank over 5 hours, and 6 g of the 5% APS aqueous solution (as ammonium persulfate, was added from another dropping tank). 0.3 g) was added dropwise intermittently over 5 hours. During this period, the inside of the reaction vessel was kept at 70 ° C.
After completion of dropping, the mixture was kept at 70 ° C. for 3 hours for aging. Thereafter, cooling was started, the temperature was cooled to 50 ° C., ammonia water was added, and the mixture was filtered through a 180-mesh polyester filter cloth. The water-dispersible acrylic silicone resin (1) had a Tg of 0 ° C. and an average particle diameter of 150 nm.

<Preparation of ink (18)>
Using the pigment dispersion (1) prepared in Example 1 and the water-dispersible acrylic silicone resin (1), the pigment solid content concentration was 6% in the ink, and the solid content of the water-dispersible resin was Ink (18) was prepared according to the same formulation as in Example 1 so that the concentration was 3.5%.

(Evaluation)
The following evaluation was performed on the obtained ink.

<Image density>
64 point character JIS X 0208 (1997), 2223, prepared by filling the ink prepared in an ink jet printer (manufactured by Ricoh Co., Ltd., IPSiO GX5000) with a Microsoft Word 2000 (manufactured by Microsoft Corporation) under an environment of 23 ° C. and 50% RH. The chart with the general symbol is printed on offset coated paper (Lumi Art Gloss), and the general symbol portion of JIS X 0208 (1997), 2223 on the printed surface is measured with X-Rite 938 (manufactured by X-Rite). Then, it was judged according to the following evaluation criteria.
As the print mode, a mode in which “glossy paper-standard clean” mode is changed to “no color correction” from the user setting of plain paper using a driver attached to the printer was used. The amount of adhesion during printing was adjusted to be 500 to 700 mg / A4. As a criterion for determining whether the image density is good or bad, those having a density of 1.93 or more were regarded as good products, and those having a density of less than 1.93 were regarded as defective products.

<Glossiness>
The glossiness was measured by measuring the image printed on the offset coated paper (Lumi Art Gloss) in the above chart with a gloss meter PG-IIM, and recording the value of 60 degree glossiness.

<AFM measurement>
The image projected on a coated paper (Lumi Art Gloss, manufactured by Stra Enso) was measured by AFM, and Ra when observed in a 1 μm square visual field was calculated. The AFM measurement conditions were as follows. When the surface roughness Ra of the coated paper (Lumi Art Gloss) alone was measured under these conditions, it was within the range of 30 nm to 35 nm.
・ Tapping mode ・ Cantilever: Olympus AC240TS (resonance frequency 70 kHz, spring constant 2 N / m)
・ Scan Rate: 1Hz
・ Samples / Line: 256
・ Lines: 256
・ Amplitude Setpoint: 250 mV
・ Tilt correction: Primary

<Ink storage stability>
Each ink was filled in an ink cartridge and stored at 70 ° C. for 1 week. The rate of change in viscosity after storage with respect to the viscosity before storage was obtained from the following formula, and evaluated according to the following criteria.
Change rate of viscosity (%) = (viscosity of ink after storage−viscosity of ink before storage) / viscosity of ink before storage × 100
A viscosity meter (RE80L, manufactured by Toki Sangyo Co., Ltd.) was used to measure the viscosity, and the viscosity at 25 ° C. was measured at 50 rotations. It should be noted that D and above were passed.
〔Evaluation criteria〕
A: Viscosity change rate within ± 5% B: Viscosity change rate over ± 5%, within ± 8% C: Viscosity change rate over ± 8%, within ± 10% D: Viscosity change The rate exceeds ± 10% and within ± 30% E: The rate of change in viscosity exceeds ± 30% (cannot be evaluated due to gelation)

<FT-IR measurement>
A resin film of resin particles alone was prepared, and the ratio of styrene to acrylic in the styrene-acrylic resin particles was calculated by ATR measurement. The peak A derived from styrene used the peak of 698 cm ⁻¹ , and the peak B derived from acrylic used the peak of 1730 cm ⁻¹ . Baseline for obtaining the peak area A in this case ^is defined as a line connecting the minimum point of the minimum point and ^{685cm -1 ~695cm} -1 of 705cm ^-1 ~715cm -1, based upon determining the peak area B line ^is defined as a line connecting the minimum point of the minimum point and ^{1695cm -1 ~1715cm} -1 of 1740cm ^-1 ~1760cm -1. The measurement conditions of FT-IR were as follows.
-Device manufacturer: Thermo Scientific-Device name: Nicolet IS50 FT-IR Spectrometer
・ Measurement mode: ATR method ・ Crystal: Silicon ・ Resolution: 4 cm ^-1
・ Total number of times: 64 times

<Evaluation result>
In the inks described in Examples 1 to 16 and Comparative Examples 1 and 2, the image density, 60 degree glossiness, Ra of AFM, and storage stability were evaluated. The results were FT-IR styrene-derived peak A: 698 cm ^−1. Table 1 together with the peak area ratio A / B at the peak B of 1,730 cm ⁻¹ derived from and acrylic.
In the table, "St / Ac" represents a styrene acrylic resin, and "Ac / Si" represents an acrylic silicon resin. Further, “BzMA” in Comparative Example 1 represents benzyl methacrylate.

While higher image density is larger peak area ratio of ^{698cm -1} / ^1730cm -1 in the spectrum of FT-IR is a tendency to be higher, in comparison of Examples 1-5, the same FT-IR peak area be the same By reducing the hydrophilic groups of the copolymer and increasing the amount of hydrophobic groups, the image density is increased.
However, when the amount of the hydrophobic group is less than 0.5 with respect to 1 (Example 5) and the amount of the hydrophilic group is more than 3.5 (Example 4), The image density decreases as the number of hydrophilic groups increases, and the storage stability tends to significantly deteriorate if the number of hydrophobic groups and hydrophilic groups is too large. Therefore, the ratio of hydrophobic group: hydrophilic group is preferably about 1: 0.5 to 3.

In Comparative Example 1, when the hydrophobic group of the dispersion resin was replaced with benzyl methacrylate, the image density was lowered and the storage stability was poor. In Example 6, the storage stability is deteriorated even when the hydrophilic group of the dispersion resin is replaced with bisphosphonic acid.
In Examples 7 and 8, even if the length L of the structure represented by the general formula (1) of the dispersed resin is changed, the image density and the storage stability are not significantly adversely affected. Therefore, the length L is 2 There is no particular problem with -12.

Further, when the copolymer was fixed to the one described in Example 1, the types of resin emulsions were changed to Examples 1, 9 to 12 and Comparative Example 2. Looking at the peak area ratio of FT-IR, the larger the peak ratio of 698 cm −1 derived from styrene, the higher the image density, and for the image density, the area ratio needs to be 3 or more.
However, if the area ratio is increased to about 6, the storage stability deteriorates, so the upper limit of the area ratio is considered to be about 5. Moreover, what investigated the dependency of the addition amount of the water-dispersible resin is described in Examples 13 to 16. However, if the addition amount of the water-dispersible resin is too large, the storage stability deteriorates and the addition amount is increased. If it is too small, there is a problem that the glossiness does not sufficiently increase, so the optimum range of the resin addition amount is considered to be 0.5 to 8%.

400 image forming apparatus 401 exterior of image forming apparatus 401c cover of apparatus body 404 cartridge holder 410 main tanks 410k, 410c, 410m, 410y for each color of black (K), cyan (C), magenta (M), and yellow (Y) Main tank 411 Ink storage unit 413 Ink discharge port 414 Storage container case 420 Mechanism unit 434 Discharge head 436 Supply tube

JP, 2005-108114, A JP, 2014-172987, A JP, 2012-46595, A JP, 2011-202004, A

Claims (11)

An ink containing water, a colorant and a copolymer, wherein the copolymer has a structural unit represented by the following general formula (1), and the ink is a support containing cellulose pulp as a main component. When a solid image is formed with a coating amount of 500 to 700 mg / A4 on a recording medium having a coating layer formed thereon and a surface roughness of 30 nm to 35 nm, a surface roughness Ra of 25 nm or less. Ink characterized by.

(In the general formula (1), R2 represents a hydrogen atom or a methyl group, and L represents an alkylene group having 2 to 12 carbon atoms.)   The ink according to claim 1, wherein the solid image has a 60 degree gloss value of 35 or more. The ink according to claim 1 or 2, wherein the copolymer has a structural unit represented by the following general formula (2).

(In the general formula (2), R1 represents a hydrogen atom or a methyl group, and X represents a hydrogen atom or a cation.)   The molar ratio of the structural unit represented by the general formula (1) to the structural unit represented by the general formula (2) is 1: 0.5 to 1: 3. Ink described.   The ink according to any one of claims 1 to 4, wherein the ink further contains styrene acrylic resin particles. The styrene-acrylic resin particles, upon acquiring the FT-IR spectrum, a peak area A in 698cm ^-1, the ratio of the peak area B of 1730 cm ^-1 (A / B) is 3 to 5 The ink according to claim 5, which is characterized.   The ink according to claim 5 or 6, wherein the content of the styrene acrylic resin particles in the ink is 0.5% by mass or more and 8.0% by mass or less in terms of solid content.   The mass ratio (S / K) of the content S of the styrene acrylic resin particles to the ink and the content K of the copolymer to the ink is 0.40 or more and 7.00 or less in terms of solid content. The ink according to any one of claims 5 to 7, wherein:   An ink cartridge comprising a container containing the ink according to claim 1.   A recording apparatus comprising: an ink ejecting unit that ejects the ink according to any one of claims 1 to 8 from a recording head to record an image on a recording medium. A recorded matter having an image formed on a recording medium,
In the recording medium, a coating layer is formed on a support containing cellulose pulp as a main component, and the surface roughness is 30 nm or more and 35 nm or less,
The image has a coloring material and a copolymer having a structural unit represented by the following general formula (1), and has a surface roughness Ra of 25 nm or less.

(In the general formula (1), R2 represents a hydrogen atom or a methyl group, and L represents an alkylene group having 2 to 12 carbon atoms. )

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