JP7298314B2 - Ink, ink container, recording device, recording method, and set - Google Patents

Description

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

The inkjet recording method is a method of recording characters and images by ejecting a small amount of ink droplets from fine nozzles and adhering them to a recording medium such as paper. Therefore, it is widely used as a home printer. In recent years, the ink jet recording method has been used for commercial printing and the like because of its advantage of being able to print at high speed. In commercial printing, etc., in order to perform high-speed printing of 0.8 m/s or more, printers (line printers) are also widely used.

The inks used in these systems are required to have ejection reliability such as ejection stability and ejection accuracy. In addition, image quality such as high image density and image fastness such as scratch resistance are also required. In line printers, since the nozzles are open to the atmosphere during printing regardless of ink ejection, there is a particular demand for improvements in these functions.

Patent Document 1 discloses an inkjet ink containing a polyurethane resin and carbon black dispersed by a styrene-acrylic acid copolymer.

However, when the content of carbon black in the ink is increased in order to improve the image density in the image formed with black ink, the intermediate gradation when printing is performed by the gradation recording method (grayscale printing). There is a problem of image defect in which the image is peeled off in the area represented by , and a problem of image transferability in which the image is transferred to a contacting object. Further, when a resin is contained in the ink in order to suppress image defect and image transfer, there is a problem of ejection reliability such as non-ejection nozzles.

An ink containing carbon black, a first resin, and a second resin having a glass transition temperature Tg higher than that of the first resin, wherein the glass transition temperature Tg of the first resin is −30° C. above −10° C., the glass transition temperature Tg of the second resin is above 80° C. and below 100° C., the glass transition temperature Tg of the second resin and the glass transition temperature Tg of the first resin is 90° C. or higher and 130° C. or lower, the first resin is a urethane resin, and the mass ratio of the content of the first resin to the content of the carbon black is 0.7 or more and 1 .5 or less, and the sum of the content of the carbon black, the content of the first resin, and the content of the second resin is 8.0% by mass or more and 15% by mass of the total amount of the ink .0 mass % or less ink.

The ink of the present invention has a high image density of an image formed by the ink, suppresses image defects in an area represented by intermediate gradation, suppresses transfer of an image to a contacting object, and has high ink ejection reliability. It has excellent effect.

FIG. 1 is a schematic diagram showing an example of a recording apparatus. FIG. 2 is a schematic diagram showing an example of an image defect evaluation jig. FIG. 3 is a schematic diagram showing an example of a plate.

An embodiment of the present invention will be described below.

<<Ink>>
The ink of this embodiment preferably contains a resin and a pigment, and if necessary, other components such as an organic solvent, water, and a surfactant. Moreover, as resin, a 1st resin and a 2nd resin are contained, and other types of resin may be further contained as needed. The first resin and the second resin have different glass transition temperatures Tg, and the glass transition temperature Tg of the second resin is higher than the glass transition temperature Tg of the first resin. Moreover, as a pigment, carbon black is contained, and if necessary, other types of pigments may be further contained. It should be noted that the ink of the present application is preferably black ink.

<First resin>
The glass transition temperature Tg of the first resin is lower than the glass transition temperature Tg of the second resin. By including the first resin having a relatively low glass transition temperature Tg in the ink, even when the ink is applied to the recording medium conveyed at high speed and then heated to dry. , the fixability of the image formed by the ink to the recording medium is improved, and the image peeling (image loss) that occurs in the area represented by the intermediate gradation when printing with the gradation recording method (grayscale print) is prevented. can be suppressed. Note that the case of "high-speed transport" is, for example, a transport speed of 0.8 m/sec or more. Further, the "heating" temperature for drying the applied ink is, for example, 100° C. or higher and 140° C. or lower. In addition, "area represented by intermediate gradation when printing with gradation recording method (grayscale print)" is, for example, within the range printed with gradation recording method (grayscale print) , the ratio of the ink dot area to the print area is 60% or more and 90% or less.

The glass transition temperature Tg of the first resin is preferably -30°C or higher and -10°C or lower, more preferably -30°C or higher and -20°C or lower. When the glass transition temperature Tg is −30° C. or higher, the fixability is improved, and the transfer of an image formed by the ink to a contact object such as a recording medium is suppressed. Further, since the glass transition temperature Tg is −10° C. or lower, the first resin is suppressed from changing from a rubber state to a glass state at room temperature, thereby improving discharge reliability.

The mass ratio of the content of the first resin in the ink to the content of carbon black in the ink (content of the first resin/content of carbon black) is 0.7 or more and 1.5 or less. , and more preferably 0.85 or more and 1.5 or less. When the mass ratio is 0.7 or more, it is possible to suppress image peeling (image loss) that occurs in areas represented by intermediate gradations when printing is performed by a gradation recording method (grayscale print). . When the mass ratio is 0.85 or more, the fixability of the ink to the recording medium is further improved, and the recording medium is conveyed at a speed of 2.0 m/sec or more for high-speed printing. Image peeling (image loss) can be suppressed even when printing is completed in a state in which the ink is insufficiently dried. Moreover, it is preferable that the mass ratio is 1.5 or less because the occurrence of image defects due to blocking is suppressed.

The type of the first resin is not particularly limited as long as it satisfies the relationship with the second resin. For example, urethane resin, styrene resin, ester resin, acrylic resin, styrene acrylic resin, styrene butadiene resin , acrylic silicone resins, etc., and urethane resins are preferred. A urethane-based resin is preferable because it has high elasticity when dried and is superior in image fixability to other resins. As the urethane-based resin, an appropriately synthesized one may be used, or a commercially available product may be used. Commercially available products include, for example, Superflex 420, Superflex 420NS, Superflex 460, Superflex 460S, Superflex 470, Superflex 500M, Superflex 650, Superflex 740 (Daiichi Kogyo Seiyaku Co., Ltd.), Takelac W6110 ( Mitsui Chemicals Memcy Co., Ltd.) and the like.

The first resin is preferably a resin emulsion. A resin emulsion refers to a state in which resin particles are dispersed in an aqueous medium such as water or ink, and it does not matter whether the resin particles are solid or liquid. In addition, an aqueous medium refers to a medium containing water or a hydrophilic solvent as a component.
Methods for dispersing the resin particles containing the first resin in water or an aqueous medium such as ink include a forced emulsification method using a dispersant and a self-emulsification method using a resin having an anionic group. In the case of the forced emulsification method, the dispersant may remain in the image formed from the ink, which may reduce the strength of the image. Therefore, it is preferable to use the self-emulsification method.

When the first resin is used as the resin particles, the volume average particle diameter of the resin particles is not particularly limited and can be appropriately selected depending on the intended purpose. , the particle size (D50) at which the volume distribution frequency is 50% is preferably 10 nm or more and 1,000 nm or less, more preferably 10 nm or more and 200 nm or less, and even more preferably 10 nm or more and 100 nm or less. The volume average particle diameter can be measured, for example, using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

The content of the first resin is not particularly limited and can be appropriately selected according to the purpose. 0% by mass or more and 20.0% by mass or less is preferable, 1.0% by mass or more and 10.0% by mass or less is more preferable, and 2.0% by mass or more and 6.0% by mass or less is even more preferable.

<Second resin>
The glass transition temperature Tg of the second resin is higher than the glass transition temperature Tg of the first resin. By including a second resin having a relatively higher glass transition temperature Tg than other resins in the ink, even when the ink is applied to a recording medium conveyed at high speed and then heated to dry. , the image density of the image formed by the ink can be increased. Note that the case of "high-speed transport" is, for example, a transport speed of 0.8 m/sec or more. Further, the "heating" temperature for drying the applied ink is, for example, 100° C. or higher and 140° C. or lower.

Moreover, specifically, the difference between the glass transition temperature Tg of the second resin and the glass transition temperature Tg of the first resin is 90° C. or more and 130° C. or less. A difference in glass transition temperature Tg of 90° C. or more is preferable because high image density can be obtained, and a difference in glass transition temperature Tg of 130° C. or less is preferable because fixability is improved and image loss can be suppressed.

The glass transition temperature Tg of the second resin is preferably 80°C or higher and 100°C or lower. When the glass transition temperature Tg is 80° C. or higher, the second resin is prevented from becoming excessively soluble, thereby improving anti-blocking properties and suppressing a decrease in image density. In addition, when the glass transition temperature Tg is 100° C. or less, the second resin is prevented from becoming excessively difficult to melt, so the surface roughness of the image formed by the ink is reduced, resulting in a decrease in image density. is suppressed, and fixability is also improved.

The mass ratio of the content of the second resin in the ink to the content of carbon black in the ink (content of the second resin/content of carbon black) is 0.6 or more and 3.4 or less. , and more preferably 0.8 or more and 2.4 or less. A mass ratio of 0.6 or more is preferable because image defects are suppressed and ejection reliability is improved. A mass ratio of 3.4 or less is preferable because the image density is improved.

The type of the second resin is not particularly limited as long as it satisfies the relationship with the first resin. It is preferably a system resin. A styrene-acrylic resin is preferable because the addition of the resin improves the image density. As the styrene-acrylic resin, an appropriately synthesized one may be used, or a commercially available product may be used. Commercially available products include, for example, KE-1062, VS-1063, YS-1274 (Seiko PMC Co., Ltd.), FS-201 (Nippon Paint Industrial Coatings Co., Ltd.), 7QX-095 (Taisei Fine Chemicals Co., Ltd.), ACRYCOTE AF. -2006, ACRYCOTE AF-7800, ACRYCOTE AF-7802, ACRYCOTE AF-362, ACRYCOTE AP-1010M, ACRYCOTE AP-2352, ACRYCOTE AP-1354 (APEC Co., Ltd.).
In addition, it is preferable to use a urethane-based resin as the first resin and a styrene acrylic-based resin as the second resin.

The second resin is preferably a resin emulsion. A resin emulsion refers to a state in which resin particles are dispersed in an aqueous medium such as water or ink, and it does not matter whether the resin particles are solid or liquid. In addition, an aqueous medium refers to a medium containing water or a hydrophilic solvent as a component.
Examples of methods for dispersing resin particles containing the second resin in water or an aqueous medium such as ink include a forced emulsification method using a dispersant and a self-emulsification method using a resin having an anionic group. In the case of the forced emulsification method, the dispersant may remain in the image formed from the ink, which may reduce the strength of the image. Therefore, it is preferable to use the self-emulsification method.

When the second resin is used as the resin particles, the volume average particle diameter of the resin particles is not particularly limited and can be appropriately selected depending on the intended purpose. , the particle size (D50) at which the volume distribution frequency is 50% is preferably 10 nm or more and 1,000 nm or less, more preferably 10 nm or more and 200 nm or less, and even more preferably 10 nm or more and 100 nm or less. The volume average particle diameter can be measured, for example, using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

The content of the second resin is not particularly limited and can be appropriately selected according to the purpose. 0% by mass or more and 20.0% by mass or less is preferable, 1.0% by mass or more and 15.0% by mass or less is more preferable, and 2.0% by mass or more and 9.0% by mass or less is even more preferable.

The mass ratio of the content of the second resin in the ink to the content of the first resin in the ink (content of the second resin/content of the first resin) is 0.7 or more5. It is preferably 4 or less. When the mass ratio is within this range, it is possible to obtain a high image density while suppressing image defects, which is preferable.

<Carbon Black>
Examples of carbon black include furnace black, lamp black, acetylene black, channel black and the like. In addition, the problem of image defects, in which the image is peeled off in the area represented by the intermediate gradation when printing by the gradation recording method (grayscale print), occurs when carbon black is used, and other pigments are used. It does not occur when used. Therefore, the ink composition of this embodiment is particularly effective when carbon black is included.

The carbon black is carbon black produced by the furnace method or the channel method, and has a primary particle size of 15 nm or more and 40 nm or less, a specific surface area by the BET method of 50 m ² /g or more and 300 m ² /g or less, and a DBP oil absorption of 40 mL/g. It preferably has 100 g or more and 150 mL/100 g or less, a volatile content of 0.5% or more and 10% or less, and a pH of 2 or more and 9 or less.

In order to disperse carbon black in ink, a method of introducing a hydrophilic functional group into carbon black to make it self-dispersible carbon black, a method of coating the surface of carbon black with a resin to disperse it, and a method of using a dispersant. and the like.
As a method of introducing a hydrophilic functional group into carbon black to self-disperse the carbon black, for example, a method of adding a functional group such as a sulfone group or a carboxyl group to the carbon black and dispersing it in water.
A method of coating the surface of carbon black with a resin and dispersing it is, for example, a method of encapsulating carbon black in microcapsules and dispersing it in water. This can be called resin-coated carbon black. In this case, all the carbon black mixed in the ink need not be coated with a resin, and uncoated carbon black or partially coated carbon black may be dispersed in the ink.
The method of dispersing using a dispersant includes, for example, a method of dispersing using a known low-molecular-weight dispersant or high-molecular-weight dispersant typified by a surfactant. As the dispersant, for example, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. can be used depending on the carbon black. RT-100 (nonionic surfactant) manufactured by Takemoto Jushi Co., Ltd. and sodium naphthalenesulfonate formalin condensate can also be used favorably as a dispersant. A dispersing agent may be used individually by 1 type, or may use 2 or more types together.

The content of carbon black in the ink is preferably 1.0% by mass or more and 10.0% by mass or less, more preferably 3.0% by mass or more and 6.0% by mass or less, relative to the total amount of the ink. When the content is within the above range, it is possible to improve the image density and suppress the image peeling in the area represented by the intermediate gradation when printing by the gradation recording method (grayscale print). It is possible to improve ejection reliability.

The sum of the carbon black content, the first resin content, and the second resin content in the ink is 8.0% by mass or more and 15.0% by mass or less with respect to the total amount of the ink. . When the sum of the contents is 8.0% by mass or more, it is possible to obtain a high image density while suppressing image defects, which is preferable. When the sum of the contents is 15.0% by mass or less, the viscosity of the ink rises sharply due to water evaporation from the nozzles of the inkjet head, etc., and ejection defects such as a slow ejection speed or failure to eject are suppressed. can do.

Carbon black may be mixed with water, a dispersant, or the like to form a carbon black dispersion, which may be mixed with a material such as water or an organic solvent for use in ink production.

<Organic solvent>
The organic solvent 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 water-soluble organic solvents include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and 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, triethylene glycol, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4- Polyhydric alcohols such as trimethyl-1,3-pentanediol and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol Polyhydric alcohol alkyl ethers such as monoethyl ether, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2 -pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, γ-butyrolactone and other nitrogen-containing heterocyclic compounds, 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; ethylene carbonate and the like. 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 provides good drying properties.

Polyol compounds having 8 or more carbon atoms and glycol ether compounds are also preferably used. Specific examples of polyol compounds 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.
A polyol compound having 8 or more carbon atoms and a glycol ether compound can improve ink permeability when paper is used as a recording medium.

The content of the organic solvent in the ink is not particularly limited and can be appropriately selected according to the purpose. % by mass or less is preferable, and 20% by mass or more and 60% by mass or less is more preferable.

<Water>
The content of water in the ink is not particularly limited and can be appropriately selected according to the purpose. % or less is preferable, and 20% by mass or more and 60% by mass or less is more preferable.

<Surfactant>
Any of silicone surfactants, fluorine surfactants, amphoteric surfactants, nonionic surfactants, and anionic surfactants can be used as surfactants.
The silicone-based surfactant is not particularly limited and can be appropriately selected depending on the purpose. Among them, those that do not decompose even at high pH are preferred. Examples of silicone-based surfactants include side chain-modified polydimethylsiloxane, both-end-modified polydimethylsiloxane, single-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 preferred because they exhibit good properties as water-based surfactants. As the silicone-based surfactant, a polyether-modified silicone-based surfactant can also be used, and examples thereof include compounds in which a polyalkylene oxide structure is introduced into the side chain of the Si portion of dimethylsiloxane.
Examples of fluorine-based surfactants include perfluoroalkylsulfonic acid compounds, perfluoroalkylcarboxylic acid compounds, perfluoroalkylphosphoric acid ester compounds, perfluoroalkylethylene oxide adducts, and perfluoroalkyl ether groups in side chains. Polyoxyalkylene ether polymer compounds are particularly preferred due to their low foaming properties. Examples of perfluoroalkylsulfonic acid compounds include perfluoroalkylsulfonic acids, perfluoroalkylsulfonates, and the like. Examples of perfluoroalkylcarboxylic acid compounds include perfluoroalkylcarboxylic acids and perfluoroalkylcarboxylic acid salts. Examples of polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in side chains include sulfuric acid ester salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in side chains, and polyoxyalkylene ether polymers having perfluoroalkyl ether groups in side chains. Examples thereof include salts of oxyalkylene ether polymers. Counter ions _of salts _in these fluorosurfactants include Li, Na, _K , _NH4 , _NH3CH2CH2OH , _NH2 ( _CH2CH2OH ) _{2 ,} and NH( _CH2CH2OH ). ₃ and the like.
Examples of amphoteric surfactants include laurylaminopropionate, lauryldimethylbetaine, stearyldimethylbetaine, lauryldihydroxyethylbetaine and the like.
Nonionic surfactants include, for example, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyoxyethylene propylene block polymers, sorbitan fatty acid esters, polyoxyethylene sorbitan Examples include fatty acid esters and ethylene oxide adducts of acetylene alcohol.
Examples of anionic surfactants include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, laurate, polyoxyethylene alkyl ether sulfate, and the like.
These may be used individually by 1 type, or may use 2 or more types together.

（但し、一般式（Ｓ－１）式中、ｍ、ｎ、ａ、及びｂは、それぞれ独立に、整数を表わし、Ｒは、アルキレン基を表し、Ｒ’は、アルキル基を表す。）
上記のポリエーテル変性シリコーン系界面活性剤としては、市販品を用いることができ、例えば、ＫＦ－６１８、ＫＦ－６４２、ＫＦ－６４３（信越化学工業株式会社）、ＥＭＡＬＥＸ－ＳＳ－５６０２、ＳＳ－１９０６ＥＸ（日本エマルジョン株式会社）、ＦＺ－２１０５、ＦＺ－２１１８、ＦＺ－２１５４、ＦＺ－２１６１、ＦＺ－２１６２、ＦＺ－２１６３、ＦＺ－２１６４（東レ・ダウコーニング・シリコーン株式会社）、ＢＹＫ－３３、ＢＹＫ－３８７（ビックケミー株式会社）、ＴＳＦ４４４０、ＴＳＦ４４５２、ＴＳＦ４４５３（東芝シリコン株式会社）などが挙げられる。 The silicone-based surfactant is not particularly limited and can be appropriately selected depending on the intended purpose. Examples include polydimethylsiloxane modified at both ends, and polyether-modified silicone surfactants having polyoxyethylene groups or polyoxyethylene polyoxypropylene groups as modifying groups are particularly preferred because they exhibit good properties as water-based surfactants. .
As such a surfactant, an appropriately synthesized one may be used, or a commercially available product may be used. Commercially available products are available from, for example, BYK Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Dow Corning Toray Silicone Co., Ltd., Nihon Emulsion Co., Ltd., Kyoeisha Chemical Co., Ltd., and the like.
The above polyether-modified silicone-based surfactant is not particularly limited and can be appropriately selected according to the purpose. Examples include those introduced into the side chain of the Si portion of siloxane.

(However, in 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.)
Commercially available products can be used as the above polyether-modified silicone-based surfactants. 1906EX (Japan Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (Dow Corning Toray Silicone Co., Ltd.), BYK-33, BYK-387 (BYK-Chemie Corporation), TSF4440, TSF4452, TSF4453 (Toshiba Silicon Co., Ltd.) and the like.

上記一般式（Ｆ－１）で表される化合物において、水溶性を付与するためにｍは０～１０の整数が好ましく、ｎは０～４０の整数が好ましい。

上記一般式（Ｆ－２）で表される化合物において、ＹはＨ、又はＣｍＦ_２ｍ＋１でｍは１～６の整数、又はＣＨ_２ＣＨ（ＯＨ）ＣＨ_２－ＣｍＦ_２ｍ＋１でｍは４～６の整数、又はＣｐＨ_２ｐ＋１でｐは１～１９の整数である。ｎは１～６の整数である。ａは４～１４の整数である。
上記のフッ素系界面活性剤としては市販品を使用してもよい。この市販品としては、例えば、サーフロンＳ－１１１、Ｓ－１１２、Ｓ－１１３、Ｓ－１２１、Ｓ－１３１、Ｓ－１３２、Ｓ－１４１、Ｓ－１４５（いずれも、旭硝子株式会社製）；フルラードＦＣ－９３、ＦＣ－９５、ＦＣ－９８、ＦＣ－１２９、ＦＣ－１３５、ＦＣ－１７０Ｃ、ＦＣ－４３０、ＦＣ－４３１（いずれも、住友スリーエム株式会社製）；メガファックＦ－４７０、Ｆ－１４０５、Ｆ－４７４（いずれも、大日本インキ化学工業株式会社製）；ゾニール（Ｚｏｎｙｌ）ＴＢＳ、ＦＳＰ、ＦＳＡ、ＦＳＮ－１００、ＦＳＮ、ＦＳＯ－１００、ＦＳＯ、ＦＳ－３００、ＵＲ、キャプストーンＦＳ－３０、ＦＳ－３１、ＦＳ－３１００、ＦＳ－３４、ＦＳ－３５（いずれも、Ｃｈｅｍｏｕｒｓ社製）；ＦＴ－１１０、ＦＴ－２５０、ＦＴ－２５１、ＦＴ－４００Ｓ、ＦＴ－１５０、ＦＴ－４００ＳＷ（いずれも、株式会社ネオス社製）、ポリフォックスＰＦ－１３６Ａ，ＰＦ－１５６Ａ、ＰＦ－１５１Ｎ、ＰＦ－１５４、ＰＦ－１５９（オムノバ社製）、ユニダインＤＳＮ－４０３Ｎ（ダイキン工業株式会社製）などが挙げられ、これらの中でも、良好な印字品質、特に発色性、紙に対する浸透性、濡れ性、均染性が著しく向上する点から、Ｃｈｅｍｏｕｒｓ社製のＦＳ－３１００、ＦＳ－３４、ＦＳ－３００、株式会社ネオス製のＦＴ－１１０、ＦＴ－２５０、ＦＴ－２５１、ＦＴ－４００Ｓ、ＦＴ－１５０、ＦＴ－４００ＳＷ、オムノバ社製のポリフォックスＰＦ－１５１Ｎ及びダイキン工業株式会社製のユニダインＤＳＮ－４０３Ｎが特に好ましい。 As the fluorosurfactant, 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 fluorine-based surfactants include perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in side chains. Among these, a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in a side chain is preferable because of its low foamability, and in particular, fluorine-based compounds represented by general formulas (F-1) and (F-2) 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 above 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 Integer, or CpH _2p+1 where p is an integer from 1-19. n is an integer of 1-6. a is an integer from 4 to 14;
Commercially available products may be used as the fluorosurfactant. Examples of commercially available products include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by Asahi Glass Co., Ltd.); Fleurard FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (both manufactured by Sumitomo 3M); Megafac F-470, F -1405, F-474 (both manufactured by Dainippon Ink and Chemicals); 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 these, Chemours FS-3100, FS-34, FS- 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 not particularly limited and can be appropriately selected according to the purpose. % or more and 5 mass % or less is preferable, and 0.05 mass % or more and 5 mass % or less is more preferable.

<Antifoaming agent>
The antifoaming agent is not particularly limited, and examples thereof include silicone antifoaming agents, polyether antifoaming agents, and fatty acid ester antifoaming agents. These may be used individually by 1 type, or may use 2 or more types together. Among these, silicone-based antifoaming agents are preferred because of their excellent foam breaking effect.

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

<Antirust agent>
The rust inhibitor is not particularly limited, and examples thereof include acidic sulfites and sodium thiosulfate.

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

<Physical properties of ink>
The physical properties of the ink are not particularly limited and can be appropriately selected depending on the intended purpose. For example, viscosity, surface tension, pH and the like are preferably within the following ranges.
The viscosity of the ink at 25° C. is preferably 5 mPa·s or more and 30 mPa·s or less, more preferably 5 mPa·s or more and 25 mPa·s or less, from the viewpoint of improving the print density and character quality and obtaining good ejection properties. more preferred. Here, the viscosity can be measured using, for example, a rotational viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.). Measurement conditions are 25° C., standard cone rotor (1°34′×R24), sample liquid volume 1.2 mL, rotation speed 50 rpm, 3 minutes.
The surface tension of the ink is preferably 35 mN/m or less, more preferably 32 mN/m or less at 25° C., from the viewpoint that the ink is appropriately leveled on the recording medium and the drying time of the ink is shortened.
The pH of the ink is preferably from 7 to 12, more preferably from 8 to 11, from the viewpoint of preventing corrosion of metal members in contact with the liquid.
The particle size of the solid content in the ink is not particularly limited, and can be appropriately selected according to the purpose. From the viewpoint of improving image quality such as ejection stability and image density, the maximum frequency of the particle size of the solid content in the ink is preferably 20 nm or more and 1,000 nm or less, more preferably 20 nm or more and 150 nm or less, in terms of the maximum number. The solid content includes resin particles and carbon black. The particle size can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

<<Pre-treatment liquid>>
The pretreatment liquid preferably contains a polyvalent metal salt and an organic solvent, and more preferably contains water and other components such as a surfactant as necessary. The organic solvent preferably contains propylene glycol and triethylene glycol, and may contain other organic solvents as necessary. The application of the pretreatment liquid is not particularly limited, but for example, it may be a treatment liquid that is applied to the recording medium before the ink containing carbon black or the like is applied to the recording medium. preferable. Also, the pretreatment liquid may be in the form of a set in which it is combined with the ink. As for other components such as water and a surfactant, the same components as those used for the ink can be used, so description thereof will be omitted.

<Polyvalent metal salt>
When the pretreatment liquid comes into contact with the ink, the polyvalent metal salt associates with the carbon black in the ink due to a charge-like action to form aggregates of the carbon black and separate the carbon black from the liquid phase. Promotes fixing to a recording medium. In addition, by including a polyvalent metal salt in the pretreatment liquid, beading can be controlled even when a recording medium with low ink absorption is used, and high-quality images can be formed. In addition, unlike a coagulant such as a cationic polymer, the polyvalent metal salt is applied to the recording medium to which the pretreatment liquid has been applied before the ink is applied after the pretreatment liquid is applied to the recording medium. Even if a member comes into contact with the region of (1), it is possible to prevent the pretreatment liquid from adhering to the member.

The polyvalent metal salt is not particularly limited and can be appropriately selected depending on the purpose. Examples include titanium compounds, chromium compounds, copper compounds, cobalt compounds, strontium compounds, barium compounds, iron compounds, aluminum compounds, calcium compounds, salts of magnesium compounds, zinc compounds, nickel compounds, and the like. These may be used individually by 1 type, and may use 2 or more types together. Among these, salts of calcium compounds, magnesium compounds, and nickel compounds are preferable, and alkaline earth metal salts of calcium compounds and magnesium compounds are more preferable, since they can effectively aggregate the pigment.

The magnesium compound is not particularly limited and can be appropriately selected depending on the intended purpose. Examples thereof include magnesium chloride, magnesium acetate, magnesium sulfate, magnesium nitrate and magnesium silicate. The calcium compound is not particularly limited and can be appropriately selected depending on the intended purpose. Examples thereof include calcium carbonate, calcium nitrate, calcium chloride, calcium acetate, calcium sulfate and calcium silicate. The barium compound is not particularly limited and can be appropriately selected depending on the intended purpose. Examples thereof include barium sulfate. The zinc compound is not particularly limited and can be appropriately selected depending on the purpose. Examples include zinc sulfide, zinc carbonate, etc. The aluminum compound is not particularly limited and can be appropriately selected depending on the purpose. It can be selected, for example, aluminum silicate, aluminum hydroxide, and the like. Among these, magnesium sulfate, magnesium nitrate, calcium nitrate, and the like, which are particularly highly soluble in a liquid composition containing triethylene glycol, are preferred.

Moreover, the polyvalent metal salt is preferably contained in an amount of 0.8 mol/L or more and 1.4 mol/L or less with respect to the total amount of the pretreatment liquid. When it is 0.8 mol/L or more, the problem of beading can be sufficiently controlled even when a low-absorbent recording medium is used, and when it is 1.4 mol/L or less, the pretreatment liquid storage stability is improved.
Further, the polyvalent metal salt is preferably contained in an amount of 3.0% by mass or more, more preferably 5.5% by mass or more, and more preferably 7.0% by mass or more relative to the total amount of the pretreatment liquid. More preferred. In addition, the polyvalent metal salt is preferably contained in an amount of 20.0% by mass or less, more preferably 15.0% by mass or less, and more preferably 14.0% by mass or less with respect to the total amount of the pretreatment liquid. More preferred. When the content of the polyvalent metal salt in the pretreatment liquid is 3.0% by mass or more, the occurrence of beading can be further controlled. Moreover, when the content is 20.0% by mass or less, it is possible to further control the precipitation and crystallization of the polyvalent metal salt in the pretreatment liquid.

<Organic solvent>
The organic solvent preferably contains propylene glycol and triethylene glycol, and may contain other organic solvents as necessary.

-Propylene glycol-
The pretreatment liquid preferably contains propylene glycol. By containing propylene glycol, it is possible to prevent the pretreatment liquid from adhering to the contact member after the pretreatment liquid is applied to the recording medium and before the ink is applied. This is because the pretreatment liquid containing propylene glycol can reduce the tackiness of the dry film formed by drying the pretreatment liquid.
In addition, when the recording medium to which the pretreatment liquid is applied has low absorbency, or the surface of the member in contact with the area of the recording medium to which the pretreatment liquid is applied is heated to 60° C. or higher and 100° C. or lower. In such a case, the adhesion of the pretreatment liquid to the member becomes conspicuous. Therefore, especially in such a case, it is preferable to include propylene glycol in the pretreatment liquid.

In addition, the propylene glycol content is preferably 3.0% by mass or more, more preferably 4.0% by mass or more, and even more preferably 4.5% by mass or more, relative to the total amount of the pretreatment liquid. . Propylene glycol is preferably contained in an amount of 15.0% by mass or less, more preferably 10.0% by mass or less, and even more preferably 9.0% by mass or less, relative to the total amount of the pretreatment liquid. . When the content of propylene glycol relative to the total amount of the pretreatment liquid is 3.0% by mass or more, the tackiness of the dry film formed by drying the pretreatment liquid can be further reduced, and the pretreatment liquid adheres to the member. can be more restrained.

The content of propylene glycol is preferably 0.50 or more and 1.10 or less, preferably 0.56 or more and 0.85 or less, based on the mass of the polyvalent metal salt. When the content of propylene glycol is 0.50 or more relative to the content of the polyvalent metal salt, the tackiness of the dry film formed by drying the pretreatment liquid can be reduced, and the pretreatment liquid can be applied to the member. adhesion can be further suppressed.

－Triethylene glycol－
The pretreatment liquid preferably contains triethylene glycol. By including triethylene glycol, the solubility of the polyvalent metal salt in the pretreatment liquid can be improved, and crystallization of the polyvalent metal salt in the pretreatment liquid can be suppressed.

In addition, triethylene glycol is preferably contained in an amount of 10.0% by mass or more, more preferably 15.0% by mass or more, and further preferably 20.0% by mass or more with respect to the total amount of the pretreatment liquid. preferable. Propylene glycol is preferably contained in an amount of 45.0% by mass or less, more preferably 40.0% by mass or less, and even more preferably 35.0% by mass or less, relative to the total amount of the pretreatment liquid. . When the content of triethylene glycol with respect to the total amount of the pretreatment liquid is 10.0% by mass or more, crystallization of the polyvalent metal salt in the pretreatment liquid can be further suppressed.

The content of triethylene glycol is 2.00 or more and 4.30 or less, preferably 3.00 or more and 4.30 or less, based on the mass of the polyvalent metal salt. When the content of triethylene glycol is 2.00 or more relative to the content of the polyvalent metal salt, crystallization of the polyvalent metal salt in the pretreatment liquid can be further suppressed.

-Other organic solvents-
The pretreatment liquid can contain other organic solvents in addition to propylene glycol and triethylene glycol. Other organic solvents include, for example, polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds. mentioned.
Specific examples of water-soluble organic solvents include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and 1,4-butane. diol, 2,3-butanediol, 3-methyl-1,3-butanediol, 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, 1,2,6-hexanetriol, 2 -Ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3-pentanediol, petriol, etc. Polyhydric alcohols, ethylene glycol monoethyl 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 and other polyhydric alcohol alkyl ethers, ethylene glycol polyhydric alcohol aryl ethers such as monophenyl ether; 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, γ-butyrolactone Nitrogen-containing heterocyclic compounds, amides such as formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, monoethanol Examples include amines such as amine, diethanolamine and triethylamine, sulfur-containing compounds such as dimethylsulfoxide and thiodiethanol, propylene carbonate and ethylene carbonate.

The content of the organic solvent in the pretreatment liquid is not particularly limited and can be appropriately selected according to the purpose. 60% by mass or less is preferable, and 20% by mass or more and 60% by mass or less is more preferable.

<Physical properties of pretreatment liquid>
The physical properties of the pretreatment liquid are not particularly limited and can be appropriately selected according to the intended purpose. For example, the viscosity, surface tension, pH and the like are preferably within the following ranges.
The viscosity of the pretreatment liquid at 25° C. is preferably from 5 mPa·s to 30 mPa·s, more preferably from 5 mPa·s to 25 mPa·s. Here, the viscosity can be measured using, for example, a rotational viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.). Measurement conditions are 25° C., standard cone rotor (1°34′×R24), sample liquid volume 1.2 mL, rotation speed 50 rpm, 3 minutes.
The surface tension of the pretreatment liquid is preferably 35 mN/m or less, more preferably 32 mN/m or less at 25°C.
The pH of the pretreatment liquid is preferably from 7 to 12, more preferably from 8 to 11, from the viewpoint of preventing corrosion of metal members in contact with the liquid.

<<Recording medium>>
The recording medium to which the ink is applied is not particularly limited, but includes plain paper, glossy paper, special paper, cloth, film, OHP sheet, general-purpose printing paper, and the like. Note that the recording medium means a medium to which ink can adhere even temporarily.

<<Recordings>>
A recorded matter has a recording medium and a print layer formed with the ink of the present embodiment applied on the recording medium. The printed layer is a layer formed by applying the ink of the present embodiment and drying it.

<<Ink container>>
The ink storage container includes an ink storage portion that stores the ink of the present embodiment, and may have other members appropriately selected as necessary.
The shape, structure, size, material, etc. of the ink storage container can be appropriately selected according to the purpose. A large-capacity ink tank or the like is suitable.

<<Recording Method>>
The recording method preferably has an ink application step of applying ink and, if necessary, a drying step of drying the applied ink. In addition, in the ink application step, the ink is preferably applied to the recording medium. Further, in order to suppress the occurrence of beading, it is more preferable to have a pretreatment liquid applying step of applying a pretreatment liquid to the recording medium before the ink applying step.

<Ink application process>
Examples of methods for applying ink include an inkjet method, 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, and a spray coating method. , the inkjet method is preferred.

<Drying process>
The drying process for drying the applied ink includes, for example, a hot air device that directly blows high-temperature air to the surface of the recording medium or the like to which the ink is applied, and a heat device that applies heat to the opposite surface of the recording medium to which the ink is applied. and a heating device that provides. It is preferable that the hot air device applies air of 100° C. or more and 140° C. or less at 20 m/sec, and the heating device preferably applies heat of 100° C. or more and 140° C. or less. It is more preferable to have both the hot air device and the heating device at the same time.

<Pretreatment liquid application step>
If desired, a pretreatment liquid can be applied prior to the ink application step. Methods for applying the pretreatment liquid to the recording medium or the like include, for example, a liquid ejection method and a coating method.

The liquid ejection method is not particularly limited and can be appropriately selected according to the purpose. For example, a method using an injection type charge control type head may be used.

Examples of coating methods include blade coating, gravure coating, gravure offset coating, wire bar coating, bar coating, roll coating, knife coating, air knife coating, comma coating, U comma coating, AKKU coating method, smoothing coating method, micro gravure coating method, reverse roll coating method, four or five roll coating method, dip coating method, curtain coating method, slide coating method, die coating method and the like. Among these, the wire bar coating method and the roller coating method are particularly preferred.

The amount of the pretreatment liquid applied to the recording medium in the pretreatment liquid application step is preferably 0.1 g/m ² or more and 30.0 g/m 2 or less, and 0.2 g/m ^{2 or} more and 10.0 g/m ² or less. is more preferred. When the applied amount is 0.1 g/m ² or more, the image quality can be improved, and when it is 30.0 g/m ² or less, pretreatment can be performed particularly in the case of a recording medium with low ink absorption. The dryness of the liquid can be improved, and curling can be prevented.

The recording medium to which the pretreatment liquid has been applied in the pretreatment liquid application step may be heated to dry the pretreatment liquid after the pretreatment liquid application step and before the ink application step, if necessary. A step may be performed, but the heating step may not be performed.
The heating step is a step of drying the pretreatment liquid applied to the recording medium by heating the recording medium with a known heating means such as a roll heater, a drum heater, and hot air. , preferably 60° C. or higher, and preferably 100° C. or lower.

<<Recording Device>>
The ink of the present embodiment can be suitably used for various recording apparatuses using an inkjet recording method, such as printers, facsimile machines, copiers, printer/fax/copier complex machines, stereolithography machines, and the like. Note that the printing apparatus is an apparatus capable of ejecting various treatment liquids such as ink and pretreatment liquid onto a printing medium.
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 called pre-processing devices and post-processing devices. .
The recording device may have heating means and/or drying means. The heating means and drying means include, for example, means for heating and drying the printing surface and the back surface of the recording medium. The heating means and drying means are not particularly limited, but for example, hot air heaters and infrared heaters can be used. Heating and drying can be performed before, during, or after printing.
Also, the recording apparatus is not limited to one that visualizes significant images such as characters and graphics with ink. For example, it includes those that form patterns such as geometric patterns, and those that form three-dimensional images.
In addition, unless otherwise specified, the recording apparatus includes both a serial type apparatus in which the ejection head is moved and a line type apparatus in which the ejection head is not moved.
Furthermore, this recording device can be used not only as a desktop type, but also as a wide recording device that can print on A0 size recording media, and for example, can use continuous paper wound into a roll as a recording medium. A continuous feed printer is also included.

An example of a recording apparatus will be described with reference to FIG. FIG. 1 is a schematic diagram showing an example of a recording apparatus. The recording apparatus includes an inkjet head 2 for applying ink 3 to a recording medium 1, a hot air device 4 and a heating device 7 for drying the ink 3 on the recording medium 1, a pretreatment liquid container 14 and a pretreatment liquid container. a coating device 9 comprising coating rollers 10, 11 and 12 for coating the recording medium 1 with the pretreatment liquid 13 in 14; 16 and 17.

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

<Preparation example of pretreatment liquid>
Triethylene glycol (manufactured by Sankyo Chemical Co., Ltd.) 30.0 mass%, propylene glycol (manufactured by ADEKA Co., Ltd.) 4.0 mass%, magnesium sulfate heptahydrate (manufactured by Showa Chemical Industry Co., Ltd.) 25.0 mass %, 2-ethyl-1,3-hexanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.2% by mass, polyoxyalkylene alkyl ether (trade name: Emulgen 103, manufactured by Kao Corporation) 0.1% by mass, 2 -Amino-2-ethyl-1,3-propanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.3% by mass, Proxel LV (manufactured by Avecia Co., Ltd.) 0.1% by mass, benzotriazole (manufactured by Johoku Kasei Kogyo Co., Ltd.) ) 0.1% by mass and ion-exchanged water were added to make the total 100% by mass, and the mixture was uniformly mixed by stirring for 1 hour to obtain a pretreatment liquid. The static surface tension of the obtained pretreatment liquid was measured using a Wilhelmy type surface tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.) in an environment of 25° C. and 55% RH, and was 32.27 mN/m. rice field.

<Adjustment of carbon black dispersion>
62.0 g (525 mmol) of 1,6-hexanediol (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was dissolved in 700 mL of methylene chloride, and 20.7 g (262 mmol) of pyridine was added. To this solution, a solution obtained by dissolving 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 over 2 hours while stirring, and then at room temperature for 6 hours. Stirred. After washing the resulting reaction solution with water, the organic phase is isolated, dried over magnesium sulfate and evaporated. The residue was purified by silica gel column chromatography using a mixed solvent of methylene chloride/methanol (98/2 by volume) as an eluent to obtain 52.5 g of 2-naphthoic acid-2-hydroxyethyl ester. 42.1 g (155 mmol) of 2-naphthoic acid-2-hydroxyethyl ester was then dissolved in dry methyl ethyl ketone and heated to 60.degree. A solution of 24.0 g (155 mmol) of 2-methacryoyloxyethyl isocyanate (manufactured by Showa Denko Co., Ltd., Karenz MOI) dissolved in 20 mL of dry methyl ethyl ketone was added dropwise to the solution with stirring over 1 hour. Stirred at 70° C. for 12 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, and 57.0 g of the structure represented by the following structural formula (1) was obtained. Monomer M-1 was obtained.

Next, a monomer solution was prepared by dissolving 1.20 g (16.7 mmol) of acrylic acid (manufactured by Sigma-Aldrich Japan G.K.) and 7.12 g (16.7 mmol) of monomer M-1 in 40 ml of dry methyl ethyl ketone. After heating 10% of the monomer solution to 75° C. under an argon stream, 0.273 g (1.67 mmol) of 2,2′-azoin (butyronitrile) (manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in the remaining monomer solution. The resulting solution was added dropwise over 1.5 hours and stirred at 75° C. for 6 hours. After cooling to room temperature, the resulting reaction solution was dropped into hexane. The precipitated copolymer was separated by filtration and dried under reduced pressure to obtain 8.13 g of copolymer (weight average molecular weight (Mw): 9200, number average molecular weight (Mn): 3100).

Next, 2.00 g of the obtained copolymer was dissolved in an aqueous tetraethylammonium hydroxide solution so that the concentration of the copolymer was 2.38% by mass and the pH was 8.0, and then carbon black was added. was added to prepare a carbon black dispersion.

<Examples 1 to 11, Comparative Examples 1 to 9>
After mixing and stirring the materials of the following formulation, the mixture was filtered through a 1.5 μm polypropylene filter to prepare inks of Examples 1 to 11 and Comparative Examples 1 to 9. The types and mixing ratios of carbon black, organic solvent, resin, etc. used in each ink are as shown in Tables 1 and 2 for Examples and Comparative Examples. In addition, the numerical value of the addition amount described in Tables 1 and 2 is "% by mass". Further, the numerical values of the added amounts of the carbon black dispersion, the first resin, and the second resin shown in Tables 1 and 2 represent the solid content.

In addition, in Tables 1 and 2, the product names and manufacturer names of the components are as follows.
・Aliphatic dialcohol (trade name: Simdiol 68, manufacturer: Iwase Cosfa Co., Ltd.)
・Polyoxyethylene alkyl ether (trade name: TRITON HW-1000, manufacturer: Dow Chemical Japan Co., Ltd.)
・2,4,7,9-tetramethyldecane-4,7-diol (manufacturer: Avecia Co., Ltd.)
・Super Flex 420 (urethane resin, manufacturer: Daiichi Kogyo Seiyaku Co., Ltd.)
・Super Flex 460S (urethane resin, manufacturer: Daiichi Kogyo Seiyaku Co., Ltd.)
・Super Flex 740 (urethane resin, manufacturer: Daiichi Kogyo Seiyaku Co., Ltd.)
・Super Flex 126 (urethane resin, manufacturer: Daiichi Kogyo Seiyaku Co., Ltd.)
・Super Flex 126 (urethane resin, manufacturer: Daiichi Kogyo Seiyaku Co., Ltd.)
・ ACRYCOTE AF-7800 (styrene acrylic resin, manufacturer: Agilis Chemical Inc.)
・KE-1062 (styrene acrylic resin, manufacturer: Seiko PMC Co., Ltd.)
・BE-7650 (styrene acrylic resin, manufacturer: Seiko PMC Co., Ltd.)
・TE-1048 (styrene acrylic resin, manufacturer: Seiko PMC Co., Ltd.)

[Evaluation of image defect in intermediate gradation area]
Image loss in areas represented by intermediate gradations when printing is performed by a gradation recording method (grayscale printing) using inks 1 to 20 prepared in Examples 1 to 11 and Comparative Examples 1 to 9. was evaluated.
Using ^an inkjet printer (model name: VC60000, manufactured by Ricoh Co., Ltd.) as shown in FIG. print. The application amount of the pretreatment liquid was set to 0.06±0.03 mg/cm ² . The recording medium was set to be conveyed at 0.8 m/sec. Printing with ink was performed by a gradation recording method (grayscale printing), and specifically, the ratio of the ink dot area to the printing area was set to 75%. The printed recording medium was dried using hot air at 100°C and a hot plate at 100°C.
By bringing a dedicated jig into contact with the ink-applied surface of the dried recording medium, evaluation of image loss in the intermediate gradation region is performed. First, a jig for image defect evaluation, which is a dedicated jig, will be described with reference to FIGS. 2 and 3. FIG. FIG. 2 is a schematic diagram showing an example of an image defect evaluation jig. FIG. 3 is a schematic diagram showing an example of a plate, which is a partial configuration of the image defect evaluation jig.
As shown in FIG. 2, the image defect evaluation jig 20 includes a plate 21 in contact with a recording medium, a mounting mechanism 24 having a fixing portion 25 attached to a translation device, and a fixing plate 22 for fixing the plate 21 to the mounting mechanism 24. The contact angle α between the plate 21 and the recording medium is preferably adjusted to 20° to 25°, more preferably 23°.
As shown in FIG. 3, the plate 21 has a length b of 25 mm in the Y1-Y2 direction, a width c of 15 mm on the Y2 side in the Z1-Z2 direction, and a radius of 150 mm on the Y1 side in the Z1-Z2 direction. has a curved portion of Although not shown in FIG. 3, the thickness of the plate is 0.5 mm. Also, the material of the plate 21 is SUS420J2.
In order to evaluate the above jig at a constant moving speed and a constant load, it was attached to a variable load type friction and wear test system (device name: HHS2000, manufactured by Shinto Kagaku Co., Ltd.), and the moving speed was 1.0 m / s. Image defect evaluation is performed under the condition of a load of 300 g.
Evaluation of image defects was performed based on the following evaluation criteria. Tables 3 and 4 show the results. The case where the evaluation was B or higher was evaluated as being practically preferable.
〔Evaluation criteria〕
A: No image defect occurred in the evaluation trace B: The evaluation trace was black (the ink forming the image in the intermediate gradation region spread to the non-image forming portion, and the friction and abrasion test was performed on the portion where the image was not formed). The state where it looks black compared to the part without it)
C: Evaluation marks are white (state in which the ink forming the image in the intermediate gradation area is worn away and the color of the recording medium is visible)

[Evaluation of Ejection Reliability]
Inks 1 to 20 prepared in Examples 1 to 11 and Comparative Examples 1 to 9 were used to evaluate ink ejection reliability. An inkjet head (device name: MH5220, manufactured by Ricoh Co., Ltd.) was filled with the ink prepared above, and the ink was adjusted so that the ejection speed was 7 m/sec, the driving frequency was 40 kHz, and the volume per droplet was 2.5 pL. , was discharged continuously for 30 minutes. In addition, the presence or absence of ink ejection was observed using a droplet observation device (device name: EV1000, manufactured by Ricoh Co., Ltd.), and evaluation was made based on the following evaluation criteria. Tables 3 and 4 show the results. The case where the evaluation was A or higher was evaluated as being practically preferable.
〔Evaluation criteria〕
A: Less than 10 non-ejection nozzles B: 10 or more non-ejection nozzles

[Image density evaluation]
The image densities of the images formed on the recording medium using the inks 1 to 20 prepared in Examples 1 to 11 and Comparative Examples 1 to 9 were measured with a reflective color spectroscopic densitometer (manufactured by X-Rite). , was evaluated based on the following evaluation criteria. Tables 3 and 4 show the results. The case where the evaluation was B or higher was evaluated as being practically preferable.
〔Evaluation criteria〕
A: 1.90 or more B: 1.80 or more and less than 1.90 C: less than 1.80

<Evaluation of Image Transferability>
Using the inks 1 to 20 prepared in Examples 1 to 11 and Comparative Examples 1 to 9 above, a 6 cm square solid image was printed on Lumi Art Gross 130 g/m ² with a printer (model name: VC60000, manufactured by Ricoh Co., Ltd.). Printed at 100 duty. After 24 hours or more after printing, the Lumi Art Gloss attached to a crockmeter (manufactured by Toyo Seiki Co., Ltd.) is reciprocated 10 times in the printed solid image area, and the transfer optical density (transfer Image density) was measured by X-rite and evaluated according to the following evaluation criteria. Tables 3 and 4 show the results. The case where the evaluation was B or higher was evaluated as being practically preferable.
〔Evaluation criteria〕
A: Transfer image density is less than 0.05 B: Transfer image density is 0.05 or more and less than 0.15 C: Transfer image density is 0.15 or more and less than 0.20 D: Transfer image density is 0.20 or more

REFERENCE SIGNS LIST 1 recording medium 2 inkjet head 3 ink 4 hot air device 5, 6, 8, 15, 16, 17 transport roller 7 heating device 9 pretreatment liquid application device 10, 11, 12 application roller 13 pretreatment liquid 14 pretreatment liquid container 20 image defect evaluation jig 21 plate 22 fixing plate 23 fixing screw 24 mounting mechanism 25 fixing part α contact angle a, b, c plate dimensions

JP 2012-214712 A

Claims (8)

An ink containing carbon black, a first resin, and a second resin having a glass transition temperature Tg higher than that of the first resin,
The glass transition temperature Tg of the first resin is -30°C or higher and -10°C or lower,
The glass transition temperature Tg of the second resin is 80° C. or higher and 100° C. or lower,
The difference between the glass transition temperature Tg of the second resin and the glass transition temperature Tg of the first resin is 90° C. or higher and 130° C. or lower,
The first resin is a urethane resin,
The mass ratio of the content of the first resin to the content of the carbon black is 0.7 or more and 1.5 or less,
The sum of the content of the carbon black, the content of the first resin, and the content of the second resin is 8.0% by mass or more and 15.0% by mass or less with respect to the total amount of the ink. some ink. 2. The ink according to claim 1, wherein the mass ratio of the content of the second resin to the content of the first resin is 0.7 or more and 5.4 or less. 3. The ink according to claim 1 , wherein said second resin is a styrene acrylic resin. The ink according to any one of claims 1 to 3 , wherein a mass ratio of the content of the second resin to the content of the carbon black is 0.6 or more and 3.4 or less. An ink container containing the ink according to any one of claims 1 to 4 . 6. A recording apparatus comprising: the ink container according to claim 5 ; and ink applying means for applying the contained ink. A recording method comprising an ink application step of applying the ink according to claim 1 . A set comprising the ink according to any one of claims 1 to 4 and a pretreatment liquid applied to a recording medium before the ink is applied.

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