JP2020111658A - Ink, ink container, recording device, and recording method - Google Patents

Abstract

To solve the problem in which a conventional ink comprising a dispersant being a copolymer having a structural unit with an anionic group and a structural unit with a terminal naphthyl group has difficulty in achieving both the storage stability of the ink and the inhibition of image density degradation that is caused by heating an image formed from the ink applied.SOLUTION: The ink comprises carbon black and a resin having a structural unit represented by a prescribed general formula. The average primary particle diameter of the carbon black is 15 nm or less. The glass transition temperature Tg of the ink exsiccated is from 50°C to 100°C inclusive.SELECTED DRAWING: None

Description

The present invention relates to an ink, an ink container, a recording device, and a recording method.

As an ink used in the inkjet recording system, a water-based ink using a dye or a pigment is known. In such an ink, a component such as a pigment that is difficult to dissolve in water needs to be stably dispersed in water for a long period of time, and therefore it is effective to use a dispersant together.

Patent Document 1 discloses a dispersant which is a copolymer having a structural unit having an anionic group and a structural unit having a naphthyl group at the terminal, and an ink containing these dispersants is discharged onto a recording medium by an inkjet method. It is disclosed that this can be done.

However, there is a problem that it is difficult to achieve both the storage stability of the ink and the suppression of the image density reduction that occurs when the image formed by the applied ink is heated.

The invention according to claim 1 is an ink containing a resin having a structural unit represented by the following general formula (1) and carbon black, wherein the average primary particle diameter of the carbon black is 15 nm or less. The glass transition temperature Tg of the dried solid of the ink is 50° C. or higher and 100° C. or lower.
(In the structural unit represented by the general formula (1), R is a hydrogen atom or a methyl group, and L is an alkylene group having 2 to 18 carbon atoms.)

INDUSTRIAL APPLICABILITY The present invention has an excellent effect in that both the storage stability of the ink and the suppression of the decrease in the image density that occurs when the image formed by the applied black ink is heated are compatible with each other.

FIG. 1 is a perspective explanatory view showing an example of a recording apparatus. FIG. 2 is a perspective explanatory view showing an example of the main tank.

Hereinafter, embodiments of the present invention will be described.

<<Ink>>
The ink of the present embodiment contains a resin having a structural unit represented by the general formula (1) and carbon black, and if necessary, other than a resin having a structural unit represented by the general formula (1). It contains components such as resin, organic solvent, water, and surfactant.

First, the reason why the ink of the present embodiment exerts an excellent effect will be described. In general, an ink containing a large amount of pigment can obtain a high image density in an image formed by the ink applied to a recording medium or the like. However, if the pigment content is increased, more dispersant used to disperse the pigment is required, but it cannot be said that general dispersants have high adsorptivity to the pigment and the storage stability of the ink decreases. To do. Further, when the ink applied to the recording medium is heated in a drying process or the like, the movement of molecules in the ink is activated, and the dispersant adsorbed to the pigment is separated, so that the pigment in the ink is aggregated. When the pigments agglomerate, the smoothness of the image surface decreases, and the image density decreases accordingly. Therefore, in the present embodiment, the storage stability is improved by using a resin having a naphthyl group in the side chain, which has a high adsorptivity to the pigment, as the dispersant. Further, the effect of improving the storage stability is effective even when the ink is heated in the drying step or the like, and it is possible to suppress the aggregation of the pigment, and as a result, the decrease in the image density is suppressed. ..

A black image formed by a black ink containing carbon black appears dark black because light incident on the image surface is absorbed with high efficiency and scattered light generated from the image surface is reduced. Therefore, when improving the image density of a black image, it is preferable to increase the smoothness of the image surface at the nanometer level. As a method for improving the smoothness of the image surface, the present inventors have stated that “a glass transition temperature Tg of a dry solid of an ink obtained by drying an ink and containing a resin such as a dispersant and a fixing resin, and carbon black. "Method for adjusting the average primary particle diameter of carbon black".

Resins in the ink, such as a dispersant and a fixing resin, are dissolved or dispersed in a liquid component (hereinafter, also referred to as “vehicle”) in the ink, such as water or an organic solvent. In the process of drying the ink containing the dissolved or dispersed resin to form an ink film, shrinkage of the resin or pigment occurs. At the time of this shrinkage, there is a difference in shrinkage ratio between the resin and the pigment, so that unevenness at the nanometer level occurs on the image surface, and the image density of the black image is reduced by the light scattered by the unevenness. In this embodiment, the glass transition temperature Tg of the dried solid of the ink is adjusted to 50° C. or higher and 100° C. or lower in order to prevent the decrease in the image density.

Further, in the present embodiment, by adjusting the primary particle size of carbon black in the ink to 15 nm or less, the unevenness generated on the image surface is reduced, and the decrease in image density is suppressed.

<Resin>
Examples of the resin include resins having the structural unit represented by the general formula (1) and resins other than the resin having the structural unit represented by the general formula (1). In addition, examples of these resins in the ink include, but are not limited to, a resin dissolved in a vehicle and a resin dispersed in the vehicle. The functions of these resins include, but are not particularly limited to, a dispersant used to disperse the pigment and a fixing resin used to fix the pigment on the recording medium.

-Resin having a structural unit represented by the general formula (1)-
The resin having the structural unit represented by the general formula (1) (hereinafter, also referred to as “first resin”) has the structural unit represented by the following general formula (1). It may be a copolymer further having a structural unit other than.
In the structural unit represented by the general formula (1), R is a hydrogen atom or a methyl group. Further, 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. The naphthyl group existing at the end via L has an excellent pigment adsorbing power to carbon black due to the π-π stacking with the carbon black in the ink, which results in high storage stability. An ink having is obtained.

The content of the structural unit represented by the general formula (1) in the resin having the structural unit represented by the general formula (1) is not particularly limited and can be appropriately selected according to the purpose. It is preferably 37.0 mass% or more and 98.0 mass% or less, more preferably 54.0 mass% or more and 95.0 mass% or less, and 66.0 mass% or more and 92.0 mass% with respect to the whole. The following are more preferable.
In addition, in the structural unit represented by the general formula (1), * represents a binding site to another structural unit, and in addition to the structure of the general formula (1), structural units derived from other polymerizable monomers (general formula (A structural unit other than (1)) can be included. The other polymerizable monomer is not particularly limited and may be appropriately selected depending on the purpose, and examples thereof include a polymerizable hydrophobic monomer, a polymerizable hydrophilic monomer, and a polymerizable surfactant.

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)acrylic Tetradecyl acid (C14), pentadecyl (meth)acrylate (C15), hexadecyl (meth)acrylate (C16), heptadecyl (meth)acrylate (C17), nonadecyl (meth)acrylate (C19), (meth)acrylic Alkyl (meth)acrylates such as eicosyl acid (C20), henicosyl (meth)acrylate (C21), and 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- Unsaturated ethylene monomers having an alkyl group such as tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicocene, 1-dococene and the like can be mentioned. These may be used alone or in combination of two or more.

Examples of the polymerizable hydrophilic monomer include (meth)acrylic acid or a salt thereof, maleic acid, monomethyl maleate, itaconic acid, monomethyl itaconic acid, fumaric acid, 4-styrenesulfonic acid, 2-acrylamido-2-methyl. Anionic unsaturated ethylene monomers such as propanesulfonic acid, or 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-vinylacetamide, Examples thereof include nonionic unsaturated ethylene monomers such as N-vinylpyrrolidone, acrylamide, N,N-dimethylacrylamide, Nt-butylacrylamide, N-octylacrylamide, and Nt-octylacrylamide. These may be used alone or in combination of two or more.

Examples of the structural unit derived from the polymerizable hydrophilic monomer include structural units represented by the following general formula (2).
In the structural unit represented by the general formula (2), R ₁ is a hydrogen atom or a methyl group. X is a hydrogen atom or a cation.
In the case of cations, the oxygen adjacent to the cation is present 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, decyltrimethyl Ammonium ion, dodecyltrimethylammonium ion, tetradecyltrimethylammonium ion, hexadecyltrimethylammonium ion, octadecyltrimethylammonium ion didodecyldimethylammonium ion, ditetradecyldimethylammonium ion, dihexadecyldimethylammonium ion, dioctadecyldimethylammonium 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-pyrrolidoni Examples thereof include um ion and 2-pyrrolidonium ion.
The content of the structural unit represented by the general formula (2) in the resin having the structural unit represented by the general formula (1) is not particularly limited and can be appropriately selected according to the purpose. It is preferably 10% by mass or more and 40% by mass or less with respect to the resin having the structural unit represented by the formula (1).

The polymerizable surfactant is an anionic or nonionic surfactant 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 +)} sulfate group and an allyl group such as _{(-CH 2} -CH = CH 2) and the hydrocarbon compound having an ammonium sulfate base (-SO ₃ ^- NH ₄ ⁺⁾ sulfate group and methacrylic group _{[-CO-C (CH 3) =} CH 2 ], such as a hydrocarbon compound having, or ammonium sulfate base ^_(-SO 3 - _NH ^{4 +)} and sulfate groups, such as 1- aromatic hydrocarbon compounds having a propenyl group (-CH = _CH 2 _{CH 3)} and the like. Specific examples thereof include Elminol JS-20 and RS-300 manufactured by Sanyo Kasei Co., Ltd., Aqualon KH-10, Aqualon KH-1025, Aqualon KH-05, Aqualon HS-10, Aqualon HS-10 manufactured by Daiichi Kogyo Seiyaku Co., Ltd. -1025, Aqualon BC-0515, Aqualon BC-10, Aqualon BC-1025, Aqualon BC-20, Aqualon BC-2020 and the like.
The nonionic surfactant, a 1-propenyl group (-CH = _CH 2 _{CH 3)} polyoxyethylene group _- a hydrocarbon compound having a _{[(C 2 H 4 O) n} -H ] a, or an aromatic hydrocarbon Hydrogen compounds may be 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 Latemur PD manufactured by Kao Corporation. -430, Latemur PD-450 and the like.
The polymerizable surfactant is preferably used in an amount of 0.1 to 10% by mass with respect to the monomer forming the structural unit represented by the general formula (1) by mixing one kind or two or more kinds.

The resin having a structural unit represented by the general formula (1) of the present embodiment, as shown in the following reaction formulas (1) and (2), first comprises naphthalene carbonyl chloride (A-1) and an excess amount of diol. The compound is subjected to a condensation reaction in the presence of an acid acceptor such as amine or pyridine to obtain naphthalenecarboxylic acid hydroxyalkyl ester (A-2). Then, 2-methacryloyloxyethyl isocyanate (A-3) is reacted with (A-2) to obtain a monomer (A-4). In order to obtain a resin, it may be further polymerized in the presence of a radical polymerization initiator. Here, the weight average molecular weight of the monomer (A-4) is 357 to 596 because L in the general formula (1) is an alkylene group having 2 to 18 carbon atoms and R is a hydrogen atom or a methyl group. ..

The radical polymerization initiator is not particularly limited and can 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 resin having the structural unit represented by the general formula (1). Examples of chain transfer agents include mercaptoacetic acid, mercaptopropionic acid, 2-propanethiol, 2-mercaptoethanol, thiophenol, dodecyl mercaptan, 1-dodecanethiol, 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 also not particularly limited and may be appropriately selected depending on the purpose, but is preferably 3 to 48 hours.

The content of the resin having the structural unit represented by the general formula (1) in the ink is preferably 1.0% by mass or more and 3.5% by mass or less with respect to the total amount of the ink from the viewpoint of enhancing the effect. It is more preferably 1.5% by mass or more and 3.0% by mass or less.

-Resin other than the resin having the structural unit represented by the general formula (1)-
The ink of the present embodiment includes a resin (hereinafter, referred to as “second resin”) other than the resin having the structural unit represented by the general formula (1), in addition to the resin having the structural unit represented by the general formula (1). "Also referred to as"). The type of resin is not particularly limited as long as it does not have the structural unit represented by the general formula (1), and can be appropriately selected according to the purpose. The resin is preferably in the form of resin particles. Here, the resin particles are fine resin particles dispersed in water or ink and are also referred to as a resin emulsion.

The resin particles used in the present embodiment preferably have an average volume particle diameter (D50) of 500 nm or less, more preferably 50 nm or more and 250 nm or less, and further preferably 50 nm or more and 200 nm or less. Here, the volume average particle diameter (D50) of the resin particles is measured by a dynamic light scattering method with Microtrack UPA manufactured by Nikkiso Co., Ltd. under the environment of 23° C. and 55% RH.

Specific examples of the resin particles include condensation type synthetic resins, addition type synthetic resins, and natural polymer compounds. Examples of the condensed synthetic resin include polyester resin, polyurethane resin, polyepoxy resin, polyamide resin, polyether resin, poly(meth)acrylic resin, acrylic-silicone resin, acrylic-styrene resin, and fluorine-based resin. Examples of the addition synthetic resin include a polyolefin resin, a polystyrene resin, a polyvinyl alcohol resin, a polyvinyl ester resin, a polyacrylic acid resin, and an unsaturated carboxylic acid resin. Examples of the natural polymer compound include celluloses, rosins, and natural rubber. Among these, poly(meth)acrylic resin, (meth)acrylic-silicone resin, and (meth)acrylic-styrene resin are preferably used.

The content of the resin other than the resin having the structural unit represented by the general formula (1) in the ink is preferably 1.0% by mass or more and 10% by mass or less, and 2.0% by mass or more with respect to the total amount of the ink. It is more preferably 8.0% by mass or less.

<Carbon black>
The ink of this embodiment contains carbon black as a black pigment, and the average primary particle diameter of carbon black is 15 nm or less. By adjusting the primary particle size of carbon black in the ink to 15 nm or less, the unevenness generated on the image surface can be reduced and the decrease in image density can be suppressed. The average primary particle diameter of carbon black is preferably 1 nm or more.
The average primary particle diameter of carbon black can be measured by processing an image photographed using a transmission electron microscope TEM (JEM-2100, manufactured by JEOL). Specifically, the ink is diluted with tetrahydrofuran to a solid content of 0.1%, and subjected to an ultrasonic disperser for 5 minutes×3 set dispersion treatment. Next, the dispersion liquid was dropped onto a collodion film-attached mesh (manufactured by Nisshin EM Co., Ltd.) using a Pasteur pipette, the solvent was evaporated by a dryer, and a transmission electron microscope was used to magnify 40,000 times and accelerating voltage 200 kV Take an image under the observation conditions of. The particle size distribution can be calculated using image analysis software (Image-Pro Plus, manufactured by Media Cybernetics). The diameter of a circle (equivalent circle diameter) equal to the projected area of a single carbon black particle obtained from an observed image is defined as a particle diameter, and 100 or more carbon blacks dispersed up to primary particles are randomly selected. By obtaining the average of, the equivalent circle diameter of the particles can be calculated as the average primary particle diameter.
Carbon black is preferably produced by a furnace method or a channel method, and has a specific surface area of 200 to 800 m ² /g by BET method, a DBP oil absorption of 40 to 150 mL/100 g, and a volatile content of 0.5 to It is preferably 10% by mass and has a pH of 2-9.
Note that the problem of the present application, "a decrease in image density that occurs when an image formed by an applied ink is heated", is not regarded as a problem with a color ink containing a color pigment, and is unique to a black ink containing carbon black. Is the subject of. The reason why the above problem becomes noticeable with the black ink is the difference in the mechanism of color development between the color ink and the black ink. Hue/saturation/brightness are factors that determine the image density of each color. In the color ink, the hue and saturation strongly affect the image density, and in the black ink, the lightness strongly affects the image density. That is, in the color ink, the light of a specific color of the light incident on the color pigment is absorbed and the light of the other color is reflected, so that it is recognized as a dark color image by the human eye, but the black ink Then, there is a difference in that the light incident on the black pigment is absorbed and the extra reflected light (scattered light) is small, so that it is recognized as a dark black image by human eyes. Here, as described above, a phenomenon that occurs when an image is heated as in the present application is a decrease in smoothness on the image surface. The decrease in smoothness on the image surface causes an increase in extra reflected light (scattered light), which causes a problem of decrease in image density particularly with black ink. Therefore, the ink configuration according to the present embodiment is effective.

A commercial item can be used as carbon black. Examples of commercially available products include No. 2650, No. 2600, No. 2350, No. 2300 (manufactured by Mitsubishi Chemical Co., Ltd.), COLOR BLACK FW 171, COLOUR BLACK FW 285, COLOR BLACK FW 255, COLOR BLACK FW 1, COLOUR BLACK FW 2, COLOR BLACK FW 200, NIPEXR 90, PREXU90, PRINUX 90, PRINUXR, COIPUR 90, PRINUXR, COINUR 90, PRINUXR. BLACK FW 182, NIPex 180 IQ, PRINTEX 95 (manufactured by Orion Engineered Carbons Co., Ltd.), SUNBLACK900, SUNBLACK905, SUNBLACK910, SUNBLACK915, SUNBLACK935, SUNBLACK960, and SUNBLACK805 (manufactured by Asahi Carbon Co., Ltd.).

The content of carbon black is preferably 1.0% by mass or more and 8.0% by mass or less with respect to the ink. When the content is 1.0% by mass or more, the pigment in the ink coating film efficiently absorbs light to increase the concentration, which is preferable. When the content is 8.0% by mass or less, the storage stability of the ink is improved. It is preferable because

<Organic solvent>
The organic solvent that can be used in this embodiment 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 polyhydric alcohols 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-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl- Examples include 1,3-pentanediol and petriol.
Examples of the polyhydric alcohol alkyl ethers include 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.
Examples of polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.
Examples of the nitrogen-containing heterocyclic compound include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam and γ-butyrolactone. Can be mentioned.
Examples of the amides include formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide and the like.
Examples of amines include monoethanolamine, diethanolamine, triethylamine and the like.
Examples of the sulfur-containing compounds include dimethyl sulfoxide, sulfolane, thiodiethanol and the like.
Examples of other organic solvents include propylene carbonate and 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.

As the organic solvent, 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, ethylene glycol monobenzyl ether and the like.

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 can 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. However, from the viewpoint of ink drying properties and ejection reliability, it is preferably 10% by mass or more and 90% by mass or less, and 20% by mass or less. % Or more and 60 mass% or less is more preferable.

<Surfactant>
As the surfactant, any of silicone-based surfactants, fluorine-based surfactants, amphoteric surfactants, nonionic surfactants, and anionic surfactants can be used.
The silicone-based 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. Examples of the silicone-based surfactant include side chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and side-chain both-end modified polydimethylsiloxane. Those having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying 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 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 perfluoroalkylcarboxylic acid compounds include perfluoroalkylcarboxylic acids and perfluoroalkylcarboxylic acid salts. Examples of the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain include a sulfuric acid ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain and a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain. Examples thereof include salts of oxyalkylene ether polymers. As counter ions of salts 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 nonionic surfactants 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 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-chain. Examples thereof include both-end modified polydimethylsiloxane and the like, and a polyether modified silicone surfactant having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group is particularly preferable because it shows good properties as an aqueous surfactant. ..
As such a surfactant, an appropriately synthesized product may be used, or a commercially available product 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, etc.
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) is 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 each independently represent an integer, R represents an alkylene group, and R′ represents an alkyl group.)
As the above polyether-modified silicone-based surfactant, commercially available products can be used, and for example, KF-618, KF-642, KF-643 (Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5602, SS-. 1906EX (Nippon 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.

As the fluorine-based surfactant, a fluorine-substituted compound having 2 to 16 carbon atoms is preferable, and a fluorine-substituted compound having 4 to 16 carbon atoms is more preferable.
Examples of the fluorine-based surfactant include a perfluoroalkyl phosphate ester compound, a perfluoroalkylethylene oxide adduct, and a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in its 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.
In the compound represented by the general formula (F-2), Y is H, or CmF _2m+1 and m is an integer of 1 to 6, or CH ₂ CH(OH)CH ₂ -CmF _2m+1 and m is 4 to 6. An integer, or CpH _2p+1 and p is an integer of 1 to 19. n is an integer of 1-6. a is an integer of 4-14.
A commercial item 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, Capstone FS-30, FS-31, FS-3100, FS-34, FS-35 (all manufactured by Chemours); FT-110, FT-250, FT-251, FT-400S, FT-150, FT-. 400SW (all manufactured by Neos Co., Ltd.), Polyfox PF-136A, PF-156A, PF-151N, PF-154, PF-159 (manufactured by Omnova), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.) Among them, good printing quality, especially color developability, penetrability to paper, wettability, even dyeability, from the point of being significantly improved, FS-3100, FS-34, FS-34 manufactured by Chemours. 300, FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW manufactured by Neos Co., Ltd., Polyfox PF-151N manufactured by Omnova Co., Ltd. and Unidyne DSN-manufactured by Daikin Industries, Ltd. 403N is particularly preferred.

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.

<<Ink dry matter>>
The dried product of the ink obtained by drying the ink of the present embodiment is a resin (first resin) having a structural unit represented by the general formula (1), which is a component contained in the ink, a general formula A resin (second resin) other than the resin having the structural unit represented by (1), carbon black, various additives, and the like are included. The glass transition temperature Tg of the dried product of the ink is 50° C. or higher and 100° C. or lower, and preferably 60° C. or higher and 90° C. or lower. When the glass transition temperature Tg of the dry solid is 50° C. or higher, the shrinkage of the resin contained in the ink during or after drying can be suppressed, so that the image density of the black image is improved. When the glass transition temperature Tg of the dry solid is 100° C. or lower, resin fusion occurs and the surface is smoothed, so that the image density of the black image is improved. As a method of adjusting the glass transition temperature Tg of the dry solid to 50° C. or higher and 100° C. or lower, for example, a resin (first resin) having a structural unit represented by the general formula (1) contained in the ink and a general resin are used. Examples include adjusting the type, content, and compounding ratio of the resin (second resin) other than the resin having the structural unit represented by formula (1). The glass transition temperature Tg of the dry solid of the ink can be measured using a differential scanning calorimeter such as DSC system Q-2000 (manufactured by TA Instruments). Specifically, first, the ink is put into an aluminum cup, dried in an oven at 80° C. for 12 hours, and then dried in a vacuum oven at 80° C. for 6 hours to obtain a dried solid matter of the ink. Next, 5.0 mg of the dried solid product of the obtained ink is placed in a sample container made of aluminum, and measurement is performed in a nitrogen atmosphere. The DSC curve at the time of the second temperature increase of (1) to (4) below is selected, and Tg is determined by the midpoint method.
(1) Hold for 5 minutes after cooling to −80 (2) Raise to 160° C. at 10° C./min (3) Hold for 5 minutes after cooling to −80 (4) Raise to 160° C. at 10° C./min

<<Ink manufacturing method>>
As a method for producing the ink, after the resin is produced according to the method for synthesizing the resin having the structural unit represented by the general formula (1), for example, water, carbon black, or the general formula (1) is used. Examples include a method of dispersing or dissolving a resin having a structural unit and a resin other than the resin having a structural unit represented by the general formula (1) in an aqueous medium, and stirring and mixing the components. The resin having the structural unit represented by the general formula (1) may be used as a pigment-dispersed resin used when preparing a carbon black dispersion.
The dispersion can be performed by, for example, a sand mill, a homogenizer, a ball mill, a paint shaker, ultrasonic dispersion, or the like. Stirring and mixing can be performed by, for example, a stirrer using a normal stirring blade, a magnetic stirrer, a high speed disperser, or the like.

<<Recording medium>>
The ink of this embodiment is most effective when a low-absorptive base material or a non-absorptive base material is used as a recording medium to be applied, but should also be used for a base material having ink absorbability. You can The non-absorbent base material refers to a base material having a surface with low water permeability, water absorbability and/or water adsorbability, and does not open to the outside even if there are many cavities inside. Material is also included. More quantitatively, it refers to a substrate having a water absorption amount of 10 mL/m ² or less from the start of contact to 30 msec ^1/2 in the Bristow method. Examples of low-absorption equipment include glossy paper, coated paper, synthetic paper, and the like. As the non-permeable substrate, for example, plastic films and sheets (vinyl chloride, polyethylene terephthalate, nylon) and the like can be preferably used.

<<Recorded matter>>
The recorded matter has a recording medium and a print layer formed by the ink of the present embodiment applied on the recording medium. The print layer is a layer formed by applying the ink of the present embodiment and drying, and therefore contains the resin having the structural unit represented by the general formula (1) and carbon black.

<< ink container >>
The ink storage container includes an ink storage portion that stores the ink of the present embodiment, and may further include other members appropriately selected as necessary.
The shape, structure, size, material, etc. of the ink container can be appropriately selected according to the purpose. For example, a container having an ink container formed of an aluminum laminate film, a resin film, or the like, having a large capacity An ink tank or the like is suitable.

<<Recording device, recording method>>
The ink according to the present embodiment can be suitably used for various recording apparatuses using an inkjet recording method, such as a printer, a facsimile apparatus, a copying apparatus, a printer/fax/copier composite machine, and a three-dimensional modeling apparatus.
In the present embodiment, 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 apparatus 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 apparatus may have a heating unit used in a heating step of heating and drying the applied ink after the ink applying step of landing the ink on the recording medium. The heating means includes, for example, a means for heating and drying the printing surface and the back surface of the recording medium. The heating means is not particularly limited, but, for example, a warm air heater or an infrared heater can be used. The heating can be performed before printing, during printing, after printing, and the like. The heating is preferably performed to the extent that the recording surface does not feel sticky. The heating temperature in the heating step using the heating means is preferably 60° C. or higher and 90° C. or lower. When the temperature is 60° C. or higher and 90° C. or lower, the vehicle contained in the ink can be quickly evaporated, and the reduction in image density due to beading or bleeding can be suppressed. However, when the ink applied to the recording medium is heated and dried, as described above, there is a problem that the image density of the image formed by the ink decreases. Therefore, when the ink is used in the heating unit, the recording apparatus having the heating step, and the recording method, it is preferable to use the ink of this embodiment. The difference between the glass transition temperature Tg of the dry solid and the heating temperature of the heating means and the heating step (glass transition temperature Tg-heating temperature) is preferably -30°C or higher and 30°C or lower, and -25°C or higher. It is more preferably 15° C. or lower.
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, it also includes one that forms a pattern such as a geometric pattern and one that models a three-dimensional image.
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, the recording device is not limited to a desktop type, but can be used as a wide recording device capable of printing on an A0 size recording medium, or 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 mechanical 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 main 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 the respective colors via the supply tubes 436 for the respective colors, and ink can be ejected from the ejection heads 434 to the recording medium.

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.

<<Application>>
The use of the ink of this embodiment is not particularly limited and can be appropriately selected according to the purpose. For example, the ink 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. For example, a device 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 object includes a three-dimensional molded object 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 sheet-shaped or film-shaped recorded material or structure that has been subjected to a molding process such as heat drawing or punching process. It is preferably used for applications such as electronic devices, meters for cameras, panels for operation parts, etc., where the surface is shaped after decoration.

Examples of the present invention will be described below, but the present invention is not limited to these examples. In addition, "parts" and "%" in the examples are "parts by mass" and "% by mass" unless otherwise specified.

The average molecular weight of the copolymers used in Examples and Comparative Examples was determined as follows.
<Measurement of average molecular weight of copolymer>
It measured on the following conditions by GPC(Gel Permeation Chromatography).
-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 by 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.

<Copolymer 1: Synthesis of CP-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 of 50.0 g (262 mmol) of 2-naphthalenecarbonyl chloride (manufactured by Tokyo Chemical Industry 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-hydroxyethyl 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 over 1 hour, and then 12 at 70°C. Stir for hours. After cooling to room temperature, the solvent was distilled off. The residue was purified by silica gel column chromatography using a mixed solvent of methylene chloride/methanol (volume ratio 99/1) as an eluent to obtain a monomer M-1 having a structure represented by the following structural formula (1). 57.0 g was obtained.

Then, 1.20 g (16.7 mmol) of acrylic acid (Aldrich) and 7.12 g (16.7 mmol) of the monomer M-1 were dissolved in 40 mL of dry methyl ethyl ketone to prepare a monomer solution. After heating 10% of the monomer solution to 75° C. under an argon stream, a solution in which 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. The mixture was added dropwise over 1.5 hours and 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 off and dried under reduced pressure to obtain 8.13 g of copolymer CP-1 (weight average molecular weight (Mw): 9200, number average molecular weight (Mn): 3100).

Next, 2.00 g of the obtained copolymer was dissolved in a tetraethylammonium (TEA) hydroxide aqueous solution so that the concentration of the copolymer was 11.9% and the pH was 8.0. A combined CP-1 aqueous solution was prepared.

<Copolymer 2: Synthesis of CP-2>
In the synthesis of copolymer CP-1, represented by the following structural formula (2) in the same manner as in Example 1 except that ethylene glycol (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 1,6-hexanediol. The monomer M-2 having the structure Next, using acrylic acid and the obtained monomer M-2, a copolymer CP-2 (weight average molecular weight (Mw): 8700, number average molecular weight (Mn): 3000) was obtained in the same manner as CP-1. Then, a copolymer CP-2 aqueous solution was prepared in the same manner as CP-1.

<Synthesis of Copolymer 3: CP-3>
In the synthesis of copolymer CP-1, 1,12-dodecanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 1,6-hexanediol in the same manner as in Example 1 except that the following structural formula ( A monomer M-3 having a structure represented by 3) was obtained. Next, using acrylic acid and the obtained monomer M-3, a copolymer CP-3 (weight average molecular weight (Mw): 9000, number average molecular weight (Mn): 2800) was prepared in the same manner as CP-1. Then, a copolymer CP-3 aqueous solution was prepared in the same manner as CP-1.

<Preparation of Pigment Dispersion: DP-1>
21.0 parts of NIPex 90 (manufactured by Orion Engineered Carbons Co., Ltd.) as a pigment and 34.0 parts of ion-exchanged water were added to 44.1 parts of the prepared aqueous solution of the copolymer CP-1 and stirred for 12 hours. The obtained mixture was circulated and dispersed at a peripheral speed of 10 m/s for 24 hours using a disk type bead mill (KDL type, manufactured by Shinmaru Enterprises Co., Ltd., media: zirconia balls 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 an adjusted amount of ion-exchanged water was added to obtain 100.0 parts of pigment dispersion DP-1 (pigment solid content concentration: 21%).

<Preparation of Pigment Dispersion: DP-2>
In the preparation of the pigment dispersion DP-1, 100.0 parts of the pigment dispersion DP-2 pigment (concentration of solid content of pigment: 21%) was used in the same manner except that the NIPex 90 of the pigment was SUNBLACK935 (manufactured by Asahi Carbon Co., Ltd.). Got

<Preparation of Pigment Dispersion: DP-3>
In the preparation of the pigment dispersion DP-1, dispersion was performed in the same manner except that the color of the pigment NIPex 90 was COLOR BLACK FW 255 (manufactured by Orion Engineered Carbons Co., Ltd.), and a centrifugal separator (manufactured by Kubota Shoji Co., Ltd.) was added. Model-7700) at a rotation speed of 15,000 rpm for 20 minutes, 60.0 parts of the container is gently extracted and filtered through a filter having a pore size of 0.8 μm to obtain a pigment dispersion DP- 3 (Pigment solid content concentration: 18%) (50.0 parts) was obtained.

<Preparation of Pigment Dispersion: DP-4>
In the preparation of the pigment dispersion DP-1, a pigment dispersion DP-4 pigment (pigment solid content concentration: 21% is used in the same manner as in the copolymer CP-1 except that the aqueous solution of the copolymer CP-2 is used. ) 100.0 parts were obtained.

<Preparation of Pigment Dispersion: DP-5>
In the preparation of the pigment dispersion DP-1, a pigment dispersion DP-5 pigment (concentration of pigment solid content: 21% was prepared in the same manner except that the aqueous solution of the copolymer CP-1 was changed to the aqueous solution of the copolymer CP-3. ) 100.0 parts were obtained.

<Preparation of Pigment Dispersion: DP-6>
The pigment dispersion DP-1 was prepared in the same manner as in the preparation of the pigment dispersion DP-1, except that the aqueous solution of the copolymer CP-1 was 7.3 parts, the pigment was 3.5 parts, and the ion-exchanged water was 51.5 parts. -6 pigment (concentration of pigment solid content: 3.5%) (100.0 parts) was obtained.

<Preparation of Pigment Dispersion: DP-7>
Pigment Dispersion DP-1 was prepared in the same manner as in Preparation of Pigment Dispersion DP-1, except that the aqueous solution of Copolymer CP-1 was changed to 63.0 parts, Pigment 31.0 parts, and Ion-exchanged water 6.0 parts. -6 pigment (pigment solid content concentration: 31%) (100.0 parts) was obtained.

<Preparation of Pigment Dispersion: DP-8>
In the preparation of the pigment dispersion DP-1, the pigment dispersion DP-8 pigment (concentration of solid content of pigment: Pigment solid content concentration: DISPERBYK-2015 (manufactured by BYK-Chemie)) was used in the same manner as in the preparation of the pigment dispersion DP-1. 21%) 100.0 parts.

<Preparation of Pigment Dispersion: DP-9>
In the preparation of the pigment dispersion DP-1, the pigment dispersion DP-9 pigment (pigment solid content concentration: 21%) was similarly used except that the aqueous solution of the copolymer CP-1 was SOLSPERSE 43000 (manufactured by Lubrizol). 100.0 parts were obtained.

<Preparation of Pigment Dispersion: DP-10>
Pigment Dispersion DP-10 (Pigment Solid Content Concentration: 21%) 100 was prepared in the same manner as in Preparation of Pigment Dispersion DP-1, except that the pigment NIPex 90 was changed to PRINTEX L6 (manufactured by Orion Engineered Carbons). 0.0 part was obtained.

<Preparation of resin emulsion: EM-1>
Into a 1 L flask (A) equipped with a stirrer, a thermometer, a nitrogen gas introducing tube, and a reflux tube, 89.0 parts of ion-exchanged water was charged, and the temperature was raised to 70° C. while introducing nitrogen. Furthermore, 3.0 parts of 10% aqualon HS-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) aqueous solution and 2.6 parts of 5% ammonium persulfate aqueous solution were added.
In addition, in the flask (B), 20.0 parts of methyl methacrylate, 16.0 parts of 2-ethylhexyl acrylate, 64.0 parts of styrene, 1.5 parts of Aqualon HS-10, and 42.9 of ion-exchanged water. The parts were mixed with a homomixer to obtain an emulsion.
The emulsion in the flask (B) was continuously added dropwise over 4 hours while stirring the solution in the flask (A). In addition, a total of 1.6 parts of a 5% ammonium persulfate aqueous solution was added every hour for 3 hours after the start of dropping. After completion of the dropping, the mixture was aged at 70° C. for 2 hours and then cooled, and the pH was adjusted to 7 to 8 with 28% aqueous ammonia to obtain a resin emulsion EM-1.

<Preparation of resin emulsion: EM-2>
A resin emulsion EM-2 was obtained in the same manner as in the synthesis of the resin emulsion EM-1, except that 20.0 parts of methyl methacrylate, 0 parts of 2-ethylhexyl acrylate and 80.0 parts of styrene were used.

<Preparation of resin emulsion: EM-3>
A resin emulsion EM-3 was obtained in the same manner as in the synthesis of the resin emulsion EM-1, except that 40.0 parts of 2-ethylhexyl acrylate and 40.0 parts of styrene were used.

<Preparation of resin emulsion: EM-4>
A mixture of 50.0 parts of T-5650E (polycarbonate-based polymer polyol, manufactured by Asahi Kasei Chemicals Corporation), 3.1 parts of 2,2-bis(hydroxymethyl)propionic acid, 2.3 parts of triethylamine, and 53.0 parts of acetone was added. A 0.5 L separable flask equipped with a stirring blade, a thermometer, and a reflux tube was charged, stirred, and heated to 40° C. while introducing nitrogen to dissolve the raw materials. Then, 23.2 parts of dicyclohexylmethane 4,4′-diisocyanate and 1 drop of tin (II) 2-ethylhexanoate were added, and the temperature was raised to 80° C. to react for 2 hours. Thereafter, the temperature was lowered to 40° C., 142.0 parts of ion-exchanged water was added to form fine particles, the mixture was stirred for 1 hour, 0.9 part of diethylenetriamine was added, and the reaction was further performed for 2 hours. When the pH was less than 8, the resin emulsion EM-4 was obtained by appropriately neutralizing with triethylamine and removing acetone.

<Preparation of resin emulsion: EM-5>
200 parts of a resin solution (solid content concentration: 15% by mass) of Teflon AF1600 (Mitsui DuPont Fluorochemical Co., Ltd.) dissolved in perfluoro(2-butyltetrahydrofuran) was charged into a jacketed glass container (content volume: 2 L). Then, cold water was passed through the jacket to keep the system temperature at 13° C., and the mixture was stirred with a stirrer (MAZELA1000, manufactured by Tokyo Rika Co., Ltd.) (rotation speed: 600 rpm). Then, while stirring, 10 parts of a 10 mass% aqueous solution of a surfactant (trade name: Unidyne DSN-403N, manufactured by Daikin Industries, Ltd.) previously dissolved in water was added, followed by a speed of 100 g/min. Then, 190 parts of distilled water at 13° C. was added. The temperature in the system was always 15° C. or lower during the entire addition of distilled water. After the addition of distilled water was completed, the mixture was stirred for 30 minutes to obtain a fluororesin emulsion having a solid content concentration of 8 mass %. Further, 400 parts of this aqueous dispersion was placed in a 1 L flask, heated in an oil bath heated to about 50° C., and concentrated under reduced pressure. The concentration was once stopped when the mass of the “flask+aqueous dispersion” was reduced by 260 parts, and after cooling to room temperature, 200 parts of distilled water was added. 340 parts of this aqueous dispersion was put into a 1 L flask again, heated in an oil bath heated to 50° C., and concentrated under reduced pressure. The concentration was completed when the mass of the “flask+aqueous dispersion” was reduced by 240 parts, and the mixture was cooled to room temperature. By the above operation, a resin emulsion EM-5 having a solid content concentration of 30 mass% was obtained.

<Preparation of resin emulsion: EM-6>
A resin emulsion EM-6 was obtained in the same manner as in the synthesis of the resin emulsion EM-1, except that 60.0 parts of 2-ethylhexyl acrylate and 20.0 parts of styrene were used.

<Preparation of ink>
[Example 1]
Pigment Dispersion DP-1 28.0 parts, propane-1,2-diol 18.0 parts, 3-methoxy-3-methyl-1-butanol 2.0 parts, TEGO Wet270 (manufactured by EVONIK INDUSTRIES) 1.0 Parts, resin emulsion: EM-1 (solid content 30.0%) 17.0 parts, Proxel LV (manufactured by Abyssia) 0.1 part, 1,2,3-benzotriazole 0.1 part, and ion-exchanged water 33. 0.8 parts were mixed, stirred for 1 hour, and then filtered with a membrane filter having a pore size of 1.2 μm to obtain the ink of Example 1.

[Examples 2 to 10]
Inks of Examples 2 to 10 were produced in the same manner as in the formulation of Example 1, except that the material was a combination of the pigment dispersion and the resin described in Table 1.

[Comparative Examples 1 to 5]
Inks of Comparative Examples 1 to 5 were prepared in the same manner as in the formulation of Example 1 except that the material was a combination of the pigment dispersion and the resin described in Table 1.

<Measurement of average primary particle size of carbon black>
The average primary particle diameter of carbon black was measured by processing an image photographed using a transmission electron microscope TEM (JEM-2100, manufactured by JEOL). Specifically, the ink was diluted with tetrahydrofuran to a solid content of 0.1%, and subjected to a dispersion treatment of 3 sets for 5 minutes with an ultrasonic disperser. The dispersion was dropped onto a collodion film-attached mesh (manufactured by Nissin EM) using a Pasteur pipette, the solvent was evaporated with a dryer, and a transmission electron microscope was used to observe conditions under a magnification of 40,000 and an acceleration voltage of 200 kV. I took an image with. The particle size distribution was calculated using image analysis software (Image-Pro Plus, manufactured by Media Cybernetics). The diameter of a circle (equivalent circle diameter) equal to the projected area of the carbon black particles obtained from the observed image is defined as the particle size, and 100 or more carbon blacks dispersed up to the primary particles are randomly selected, The equivalent circle diameter was calculated as the average primary particle size. The results are shown in Table 1.

<Measurement of glass transition temperature Tg of dry solid>
The glass transition temperature Tg of the dry solid of the ink was measured using a differential scanning calorimeter (DSC system Q-2000, manufactured by TA Instruments). Specifically, the ink was placed in an aluminum cup, dried in an oven at 80° C. for 12 hours, and then dried in a vacuum oven at 80° C. for 6 hours to obtain a dried solid product of the ink. 5.0 mg of the dried solid product of the obtained ink was placed in a sample container made of aluminum, and the measurement was performed in a nitrogen atmosphere. Tg was determined by the midpoint method by selecting the DSC curve at the time of the second temperature increase from (1) to (4) below. The results are shown in Table 1.
(1) Hold for 5 minutes after cooling to −80 (2) Raise to 160° C. at 10° C./min (3) Hold for 5 minutes after cooling to −80 (4) Raise to 160° C. at 10° C./min

Next, the characteristics of each ink prepared in Examples 1 to 10 and Comparative Examples 1 to 5 were evaluated according to the following methods and evaluation criteria. The results are shown in Table 1.

<Evaluation of storage stability>
Each ink was filled in an ink container and stored at 70° C. for 1 week, and the change rate of the viscosity (Q) after storage with respect to the viscosity (P) before storage was obtained from the following formula, and evaluated according to the following criteria.
Formula: Change rate of viscosity (%)={(Q-P)/P}×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.
〔Evaluation criteria〕
A: Viscosity change rate within ±5% B: Viscosity change rate over ±5%, within ±10% C: Viscosity change rate over ±10%, within ±30% D: Viscosity change Rate exceeds ±30%, or gelation is impossible and evaluation is not possible

<Image density>
An ink jet printer (IPSiO GXe5500, manufactured by Ricoh) was filled with each ink, and a solid image of 20 mm square at a resolution of 600 dpi was formed on a coated paper (Lumi Art Gloss 130 gsm paper, manufactured by Stora Enso). Immediately after printing, it was dried by heating in an oven at 80° C. for 60 seconds.
Next, with respect to the solid image printed on the recording medium, the image density was measured using a handy colorimeter (X-Rite eXact, manufactured by X-Rite), and the image density was evaluated according to the following criteria.
〔Evaluation criteria〕
A: Image density is 1.90 or more B: Image density is 1.70 or more and less than 1.90 C: Image density is 1.50 or more and less than 1.70 D: Image density is less than 1.50

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 Ejection head 436 Supply tube

JP, 2008-127525, A

Claims (12)

An ink containing a resin having a structural unit represented by the following general formula (1) and carbon black,
The average primary particle size of the carbon black is 15 nm or less,
An ink having a glass transition temperature Tg of 50° C. or higher and 100° C. or lower, which is a dried solid of the ink.
(In the structural unit represented by the general formula (1), R is a hydrogen atom or a methyl group, and L is an alkylene group having 2 to 18 carbon atoms.) The ink according to claim 1, further comprising a resin other than the resin having the structural unit represented by the general formula (1). The ink according to claim 1 or 2, wherein the glass transition temperature Tg of the dried solid is 60°C or higher and 90°C or lower. The ink according to any one of claims 1 to 3, wherein the resin having a structural unit represented by the general formula (1) further has a structural unit represented by the following general formula (2).
(In the structural unit represented by the general formula (2), R ₁ is a hydrogen atom or a methyl group, and X is a hydrogen atom or a cation.) The ink according to any one of claims 1 to 4, wherein the content of the carbon black is 1.0% by mass or more and 8.0% by mass or less with respect to the ink. An ink container for containing the ink according to claim 1. A recording apparatus comprising: the ink container according to claim 6; and an ejection unit that ejects the contained ink. The recording apparatus according to claim 7, further comprising a heating unit that heats the ejected ink. The recording apparatus according to claim 7 or 8, wherein a difference between the glass transition temperature Tg of the dried solid and the heating temperature of the heating means (glass transition temperature Tg-heating temperature) is -30°C or higher and 30°C or lower. A recording method comprising an ejection step of ejecting the ink according to claim 1. The recording method according to claim 10, further comprising a heating step of heating the ejected ink. The recording method according to claim 10 or 11, wherein a difference between the glass transition temperature Tg of the dried solid and the heating temperature in the heating step (glass transition temperature Tg-heating temperature) is -30°C or higher and 30°C or lower.