JP6641668B2 - Ink, ink container, image recording method and image recording apparatus - Google Patents

Description

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

  The inkjet recording method is popular because it has the advantages that the process is simpler than other recording methods, full-color printing is easy, and a high-resolution image can be obtained even with a device having a simple configuration. Have been doing. In the ink jet recording system, a small amount of ink is caused to fly by a bubble generated by heat, a pressure generated by using piezo or electrostatic force, and the ink is attached to a recording medium such as paper and dried quickly (or recording). (Permeation into a medium) to form an image, and its use is expanding to personal and industrial printers and printing.

  In such an ink jet recording system, a water-based ink or a pigment ink using a water-soluble dye as a coloring agent is used. In recent years, however, a pigment ink is usually used from the viewpoint of weather resistance and water resistance.

  In recent years, development of water-based pigment inks for high-speed continuous printing machines has been promoted, and pigment inks that can obtain high-quality images even when printed at high speed have been demanded. In a high-speed continuous press, since the main target medium is offset coated paper, the mechanism for obtaining high image quality and high productivity differs from the case of plain paper.

  In the case of offset coated paper, drying and fixing properties often pose a problem compared to the case of plain paper. In a printed image on offset coated paper used in a high-speed continuous printing machine, the drying property is mainly discussed by an index of blocking, and the fixing property is mainly discussed by an index of spreadability. The phenomenon of blocking is a problem in that when printing is performed by a roller after printing with a high-speed continuous printing machine, pressure is applied while the prints overlap each other, and the ink is transferred. In addition, the spreadability phenomenon is a problem in that, when the printed image is completely dried and the customer uses the printed image, the portion of the printed image to which the ink is attached is rubbed with paper or the like.

  In Patent Document 1 (Japanese Patent Application Laid-Open No. 2011-153180), a white ink composition is obtained. By mixing a urethane resin and a styrene acrylic resin in a ratio of 10: 1, the drying property and the fixing property are improved. Have been reported. However, according to the study results of the present inventors, urethane resin can achieve both blocking and spreadability when the urethane resin is smaller than the styrene acrylic resin, and further, the result that the styrene resin is better than the styrene acrylic resin is better. Obtained. (The ratio of urethane resin particles / styrene resin particles is 0.3 or more and 0.6 or less).

  Patent Document 2 (Japanese Patent Application Laid-Open No. 2003-96342) reports an ink that satisfies abrasion resistance and printing characteristics by using a polyurethane resin emulsion. With this ink composition, the problem that blocking deteriorated was confirmed.

  Patent Document 3 (Japanese Patent Application Laid-Open No. 2014-172987) reports an ink obtained by adding a styrene acrylic resin and wax particles to achieve both abrasion resistance and image density. From the viewpoint of affinity for the ink, the dispersion stability was poor, and there was a problem that storage stability could not be secured if too much was added.

  It is an object of the present invention to provide an ink that achieves both blocking and spreadability while ensuring storage stability.

  As a result of the study by the present inventors, two types of soft resin (urethane resin) and hard resin (styrene resin) were mixed in the ink to prepare an ink, and the ratio of the hard resin was increased. Have found an area where both issues are compatible.

The constitution of the ink of the present invention for solving the above-mentioned problems is as described in the following (1).
(1) An ink containing an organic solvent, water, and a coloring material,
The ink includes urethane resin particles and styrene resin particles,
An image Y obtained by heating and drying the image X formed by applying the ink to the recording medium has a peak A (Y) and a peak B (Y) in the histogram of the AFM phase image, and the peak A (Y ) Is an area of 6 degrees or more and 20 degrees or less, the peak B (Y) is an area of -17 degrees or more and -10 degrees or less, and the image surface coverage of the peak A (Y) is 50-60%. And an ink having a peak B (Y) image surface coverage of 40 to 50%.

  According to the present invention, it is possible to provide an ink that achieves both blocking and spreadability while securing the storage stability of the ink.

FIG. 3 is a diagram illustrating an example of a recording apparatus using the ink of the present invention. FIG. 3 is a perspective view of a main tank that stores the ink of the present invention. FIG. 14 is a diagram illustrating a phase image before heating of a print image of the ink of Example 4; FIG. 13 is a diagram illustrating a phase image after heating of a print image of the ink of Example 4; FIG. 13 is a diagram illustrating a histogram of an AFM phase image of a print image of the ink according to the fourth embodiment.

The present invention relates to the ink described in the above (1), but the following (2) to (12) are also included as embodiments and will be described together.
(2) The ratio (A (Y) / B (Y)) of the image surface coverage of the peak A (Y) to the image surface coverage of the peak B (Y) is 1.0 to 1.5. The ink according to the above (1), wherein:
(3) In the image X, the histogram of the AFM phase image has a peak A and a peak B, the peak A (X) is a region of 10 degrees or more and 21 degrees or less, and the peak B (X) is -16. And the image surface coverage of the peak A (X) is 65 to 75%, and the image surface coverage of the peak B (X) is 25 to 35%. The ink according to the above (1), which is characterized in that:
(4) When the ratio (A (X) / B (X)) of the image surface coverage of the peak A (X) to the image surface coverage of the peak B (X) is 2.0 or more and 2.5 or less. The ink according to the above (3), wherein:
(5) The mass ratio (urethane resin particle / styrene resin particle) between the content (% by mass) of the urethane resin particles and the content (% by mass) of the styrene resin particles is 0.3 or more and 0.6 or less. The ink according to any one of the above (1) to (4), wherein
(6) The ink as described in any one of (1) to (5) above, wherein a minimum film forming temperature of the styrene resin particles is 45 ° C. or higher.
(7) The difference between Tg (S) of the styrene resin particles and Tg (U) of the urethane resin particles (Tg (S) −Tg (U)) is 60 ° C. or more and 80 ° C. or less. The ink according to any one of (1) to (6).
(8) The recording medium has a coating layer on at least one surface of a support, and the ink is applied to a surface having the coating layer, and is measured by a dynamic scanning liquid absorption meter. any of the above said amount of transfer of the surface having the coating layer of the recording medium of pure water at a contact time of 100ms is characterized in that it is a ^1ml / ^{m 2 ~10ml} / m 2 of (1) to (7) The ink described in Crab.
(9) An ink container, wherein the ink according to any one of (1) to (8) is stored in a container.
(10) An image recording method including a step of obtaining an image Y by heating and drying an image X formed by applying an ink to a recording medium, wherein the ink is any one of the above (1) to (8). An image recording method, comprising:
(11) The image recording method according to the above (10), wherein the heating temperature in the heating and drying is 90 ° C. or more and 110 ° C. or less.
(12) An image recording apparatus including an ink, a unit for applying an ink to a recording medium to obtain an image X, and a heating and drying unit for heating and drying the image X to obtain an image Y, wherein the ink is as described above. An image recording apparatus comprising the ink according to any one of (1) to (8).

<Ink>
Hereinafter, organic solvents, water, coloring materials, resins, additives, and the like used in the ink will be described.

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

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

  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 depending on the intended purpose; however, from the viewpoint of drying properties and ejection reliability of the ink, the content is preferably from 10% by mass to 60% by mass, The content is more preferably from 20% by mass to 60% by mass.

<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 drying properties and ejection reliability of the ink, the content is preferably from 10% by mass to 90% by mass, and more preferably from 20% by mass. % To 60% by mass is more preferable.

<Color material>
The coloring material is not particularly limited, and pigments and dyes can be used.
As the pigment, an inorganic pigment or an organic pigment can be used. These may be used alone or in combination of two or more. Further, a mixed crystal may be used.
As the pigment, for example, black pigments, yellow pigments, magenta pigments, cyan pigments, white pigments, green pigments, orange pigments, luster pigments such as gold and silver, and metallic pigments can be used.
As inorganic pigments, in addition to titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chrome yellow, carbon black produced by a known method such as a contact method, a furnace method, and a thermal method Can be used.
Examples of the organic pigment include azo pigments and polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinoflurone pigments) And dye chelates (eg, basic dye chelates and acid dye chelates), nitro pigments, nitroso pigments, aniline black, and the like. Among these pigments, those having good affinity for the solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can be used.
Specific examples of the pigment include carbon black (CI Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black, or copper or iron (CI pigment black 11) for black. And metals such as titanium oxide, and organic pigments such as aniline black (CI pigment black 1).
Further, for color, C.I. I. Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104 , 108, 109, 110, 117, 120, 138, 150, 153, 155, 180, 185, 213, C.I. I. Pigment Orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48: 2, 48: 2 (Permanent Red 2B (Ca)), 48: 3, 48: 4, 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmine 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81, 83, 88, 101 (Bengara), 104, 105, 106, 108 ( Cadmium red), 112, 114, 122 (quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, C.I. I. Pigment Violet 1 (rhodamine lake), 3, 5: 1, 16, 19, 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue), 15: 1, 15: 2, 15: 3, 15: 4 (phthalocyanine blue), 16, 17: 1, 56, 60, 63, C.I. I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, and the like.
The dye is not particularly limited, and an acidic dye, a direct dye, a reactive dye, and a basic dye can be used. One type of dye may be used alone, or two or more types may be used in combination.
Examples of the dye include C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Red 52, 80, 82, 249, 254, 289, C.I. I. Acid blue 9, 45, 249, C.I. I. Acid Black 1, 2, 24, 94, C.I. I. Food black 1, 2, C.I. I. Direct Yellow 1,12,24,33,50,55,58,86,132,142,144,173, C.I. I. Direct Red 1,4,9,80,81,225,227, C.I. I. Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, C.I. I. Directed Black 19, 38, 51, 71, 154, 168, 171, 195, C.I. I. Reactive Red 14, 32, 55, 79, 249, C.I. I. Reactive Black 3, 4, 35.

  The content of the coloring material in the ink is preferably 0.1% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 10% by mass from the viewpoints of improvement in image density, good fixability and ejection stability. It is as follows.

In order to disperse the pigment in the ink, a method of introducing a hydrophilic functional group into the pigment to form a self-dispersing pigment, a method of coating and dispersing the surface of the pigment with a resin, a method of dispersing using a dispersant, And the like.
As a method of introducing a hydrophilic functional group into a pigment to obtain a self-dispersible pigment, for example, a self-dispersible pigment which can be dispersed in water by adding a functional group such as a sulfone group or a carboxyl group to a pigment (for example, carbon). Can be used.
As a method of coating and dispersing the surface of the pigment with a resin, a method in which the pigment is included in microcapsules and can be dispersed in water can be used. This can be rephrased as a resin-coated pigment. In this case, it is not necessary that all the pigments incorporated in the ink be coated on the resin, and as long as the effects of the present invention are not impaired, uncoated pigments or partially coated pigments are dispersed in the ink. May be.
Examples of a method of dispersing using a dispersant include a method of dispersing using a known low-molecular type dispersant and a high-molecular type dispersant represented by a surfactant.
As the dispersant, for example, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, or the like can be used depending on the pigment.
RT-100 (a nonionic surfactant) manufactured by Takemoto Yushi Co., Ltd., and Na formalin condensate of naphthalenesulfonic acid can also be suitably used as the dispersant.
One type of dispersant may be used alone, or two or more types may be used in combination.

<Pigment dispersion>
It is possible to obtain an ink by mixing a material such as water or an organic solvent with a coloring material. Further, it is also possible to produce an ink by mixing a material such as water or an organic solvent with a pigment dispersion obtained by mixing a pigment and other water or a dispersant.
The pigment dispersion is obtained by dispersing water, a pigment, a pigment dispersant, and other components as necessary, and adjusting the particle size. For dispersion, a disperser may be used.
The particle size of the pigment in the pigment dispersion is not particularly limited, but the dispersion frequency of the pigment is good, and the image quality such as ejection stability and image density is also high. 500 nm or less is preferable, and 20 nm or more and 150 nm or less are more preferable. The particle size of the pigment can be measured using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).
The content of the pigment in the pigment dispersion is not particularly limited and can be appropriately selected depending on the intended purpose; however, from the viewpoint of obtaining good ejection stability and increasing the image density, 0.1 mass % To 50% by mass, more preferably 0.1% to 30% by mass.
The pigment dispersion is preferably degassed by filtering coarse particles with a filter, a centrifugal separator or the like, if necessary.

  Styrene resin particles and urethane resin particles are used as resin particles to be mixed in the ink. The term styrene resin includes styrene acrylic resins. It is possible to obtain an ink by mixing resin particles with a material such as a coloring material or an organic solvent in a state of a resin emulsion in which water is used as a dispersion medium. As the resin particles, appropriately synthesized ones or commercially available ones may be used.

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

  The content of the resin is not particularly limited and may be appropriately selected depending on the purpose. From the viewpoint of fixability and storage stability of the ink, the content is 1% by mass or more and 30% by mass or less based on the total amount of the ink. Is preferably 5% by mass or more and 20% by mass or less.

  The particle size of the solid content in the ink is not particularly limited and can be appropriately selected depending on the purpose.However, from the viewpoint of improving image quality such as ejection stability and image density, the maximum frequency in terms of the maximum number is Is preferably from 20 nm to 1000 nm, more preferably from 20 nm to 150 nm. The solid content includes resin particles and pigment particles. The particle size can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrac Bell Inc.).

<Additives>
If necessary, a surfactant, an antifoaming agent, an antiseptic / antifungal agent, a rust inhibitor, a pH adjuster and the like may be added to the ink.

<Surfactant>
As the surfactant, any of a silicone-based surfactant, a fluorine-based surfactant, an amphoteric surfactant, a nonionic surfactant, and an anionic surfactant can be used.
The silicone-based surfactant is not particularly limited and can be appropriately selected depending on the purpose. Among them, those which do not decompose even at a high pH are preferable, and examples thereof include side-chain-modified polydimethylsiloxane, both-end-modified polydimethylsiloxane, one-end-modified polydimethylsiloxane, and both-chain-end both-end modified polydimethylsiloxane. Those having an oxyethylene group or a polyoxyethylene polyoxypropylene group are particularly preferable because they exhibit good properties as an aqueous surfactant. In addition, a polyether-modified silicone-based surfactant can also be used as the silicone-based surfactant, 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 the fluorine-based surfactant include a perfluoroalkylsulfonic acid compound, a perfluoroalkylcarboxylic acid compound, a perfluoroalkylphosphate ester compound, a perfluoroalkylethylene oxide adduct, and a perfluoroalkylether group in a side chain. Polyoxyalkylene ether polymer compounds are particularly preferred because of their low foaming properties. Examples of the perfluoroalkylsulfonic acid compound include perfluoroalkylsulfonic acid and perfluoroalkylsulfonic acid salt. Examples of the perfluoroalkylcarboxylic acid compound include perfluoroalkylcarboxylic acid and perfluoroalkylcarboxylic acid salt. Examples of the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in a side chain include a sulfate salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in a side chain, and having a perfluoroalkyl ether group in a side chain. Salts of a polyoxyalkylene ether polymer are exemplified. The counter ions of the salts in these fluorinated surfactants include Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ , and NH (CH ₂ CH ₂ OH) _{3 and the} like.
Examples of the amphoteric surfactant include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, lauryl dihydroxyethyl betaine, and the like.
Examples of the nonionic surfactant include polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkylamine, polyoxyethylene alkyl amide, polyoxyethylene propylene block polymer, sorbitan fatty acid ester, and polyoxyethylene sorbitan. Examples include fatty acid esters and ethylene oxide adducts of acetylene alcohol.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, laurylate, and polyoxyethylene alkyl ether sulfate.
These may be used alone or in combination of two or more.

The silicone-based surfactant is not particularly limited and can be appropriately selected depending on the intended purpose. Examples thereof include side-chain modified polydimethylsiloxane, both-terminal-modified polydimethylsiloxane, one-terminal-modified polydimethylsiloxane, Examples include polydimethylsiloxane modified at both ends of the chain, and a polyoxyethylene group having a modifying group, and a polyether-modified silicone surfactant having a polyoxyethylene polyoxypropylene group exhibiting good properties as an aqueous surfactant. preferable.
As such a surfactant, an appropriately synthesized one 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., Dow Corning Toray Silicone Co., Ltd., Nippon Emulsion Co., Ltd., Kyoeisha Chemical Co., Ltd.
The polyether-modified silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the polyalkylene oxide structure represented by the general formula (S-1) may be a dimethylpolysiloxane. Examples include those introduced into the side chain of the siloxane in the siloxane.
General formula (S-1)
(In the general formula (S-1), m, n, a, and b represent an integer. R and R ′ represent an alkyl group or an alkylene group.)
Commercially available products can be used as the above-mentioned polyether-modified silicone-based surfactant. For example, KF-618, KF-642, KF-643 (Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5602, SS- 1906EX (Japan Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (Toray Dow Corning Silicone Co., Ltd.), BYK-33, BYK-387 (Big Chemie Co., Ltd.), TSF4440, TSF4452, and TSF4453 (Toshiba Silicon Co., Ltd.).

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 perfluoroalkyl ethylene oxide adduct, and a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in a side chain. Among these, a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain is preferable because of low foaming property, and particularly, fluorine-based compounds represented by the general formulas (F-1) and (F-2). Surfactants are preferred.
General formula (F-1)
In the compound represented by the above 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.
General formula (F-2)
_{C n F 2n + 1- CH 2} CH (OH) CH 2 -O- (CH 2 CH 2 O) a -Y
In the compound represented by the general formula (F-2), Y is H, or CnF _{2n + 1} and n is an integer of 1 to 6, or CH ₂ CH (OH) CH ₂ —CnF _{2n + 1} and n is 4 to 6. P is an integer of 1 to 19 at an integer or CpH _{2p + 1} . a is an integer of 4 to 14.
A commercially available product may be used as the above-mentioned fluorine-based surfactant. 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.); Fullard FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M Limited); Megafac F-470, F -1405, F-474 (all manufactured by Dainippon Ink and Chemicals, Inc.); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR (all FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW (all manufactured by DuPont) Males), Polyfox PF-136A, PF-156A, PF-151N, PF-154, PF-159 (manufactured by Omnova), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.), and the like. Among these, FS-300 manufactured by Du Pont, FT-110 manufactured by Neos Co., Ltd., and FT-250 manufactured by Neos Co., Ltd., from the standpoint of significantly improving good print quality, especially color development, permeability to paper, wettability, and levelness. FT-251, FT-400S, FT-150, FT-400SW, Polyfox PF-151N manufactured by Omnova and Unidyne DSN-403N manufactured by Daikin Industries, Ltd. are particularly preferred.

  The content of the surfactant in the ink is not particularly limited and may be appropriately selected depending on the purpose. However, from the viewpoint of excellent wettability and ejection stability and improved image quality, 0.001 mass % To 5% by mass, more preferably 0.05% to 5% by mass.

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

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

<Rust inhibitor>
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 the pH can be adjusted to 7 or more, and examples thereof include amines such as diethanolamine and triethanolamine.

The physical properties of the ink are not particularly limited and can be appropriately selected depending on the purpose. For example, the viscosity, surface tension, pH, and the like are preferably in the following ranges.
The viscosity of the ink at 25 ° C. is preferably 5 mPa · s or more and 30 mPa · s or less, and more preferably 5 mPa · s or more and 25 mPa · s or less, from the viewpoint of improving print density and character quality, and obtaining good ejection properties. More preferred. Here, for the viscosity, for example, a rotary viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.) can be used. As measurement conditions, measurement can be performed at 25 ° C. with a standard cone rotor (1 ° 34 ′ × R24), a sample liquid amount of 1.2 mL, a rotation speed of 50 rpm, and 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 suitably 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, and more preferably from 8 to 11, from the viewpoint of preventing corrosion of the metal member that comes into contact with the ink.

<Pretreatment liquid>
The pretreatment liquid contains a flocculant, an organic solvent, and water, and may contain a surfactant, an antifoaming agent, a pH adjuster, an antiseptic / antifungal agent, a rust inhibitor and the like as required.
As the organic solvent, surfactant, defoaming agent, pH adjuster, antiseptic / antifungal agent, and rust inhibitor, the same materials as those used for ink can be used, and other materials used for known treatment liquids can be used. .
The type of the flocculant is not particularly limited, and examples thereof include a water-soluble cationic polymer, an acid, and a polyvalent metal salt.

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

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

  The recording medium is not limited to those used as general recording media, and non-permeable base materials and permeable base materials can be used, such as building materials such as wallpaper and flooring materials, cloths for clothing, textiles, and leather. Etc. can be used as appropriate. Further, by adjusting the configuration of the path for transporting the recording medium, ceramics, glass, metal, or the like can be used.

<Recorded>
The ink record of the present invention has an image formed on a recording medium using the ink of the present invention.
A recorded matter can be obtained by recording using an inkjet recording apparatus and an inkjet recording method.

<Recording device and recording method>
The ink of the present invention can be suitably used in various recording apparatuses using an ink jet recording system, for example, a printer, a facsimile apparatus, a copying apparatus, a combined printer / fax / copier machine, and a three-dimensional printing apparatus.
In the present application, a recording device and a recording method are a device capable of discharging ink, various processing liquids, and the like to a recording medium, and a method of performing recording using the device. The recording medium means a medium to which ink and various processing liquids can be temporarily attached.
This recording apparatus can include not only a head portion for discharging ink, but also means for feeding, transporting, and discharging a recording medium, and other devices such as a pre-processing device and a post-processing device. .
The recording device and the recording method may include a heating unit used in the heating step and a drying unit used in the drying step. The heating means and the drying means include, for example, means for heating and drying the printing surface or the back surface of the recording medium. The heating means and the drying means are not particularly limited, and for example, a warm air heater or an infrared heater can be used. Heating and drying can be performed before printing, during printing, after printing, and the like.
Further, the recording apparatus and the recording method are not limited to those in which a significant image such as a character or a graphic is visualized by ink. For example, those that form a pattern such as a geometric pattern and the like that form a three-dimensional image are also included.
Further, the recording apparatus includes both a serial type apparatus that moves the ejection head and a line type apparatus that does not move the ejection head, unless otherwise limited.
Furthermore, this recording apparatus can use not only a desktop type but also a wide recording apparatus that can print on an A0 size recording medium, or a continuous paper wound in a roll shape as a recording medium. It also includes a simple continuous printer.
An example of the recording apparatus will be described with reference to FIGS. FIG. 1 is a perspective explanatory view of the device. FIG. 2 is a perspective explanatory view of the main tank. The image forming apparatus 400 as an example of the recording apparatus is a serial type image forming apparatus. A mechanism section 420 is provided inside an exterior 401 of the image forming apparatus 400. Each ink storage section 411 of the main tank 410 (410k, 410c, 410m, 410y) for each color of black (K), cyan (C), magenta (M), and yellow (Y) is packaged with, for example, an aluminum laminate film. It is formed by a member. The ink storage unit 411 is stored in a storage container case 414 made of, for example, plastics. Thus, the main tank 410 is used as an ink cartridge for each color.
On the other hand, a cartridge holder 404 is provided behind the opening when the cover 401c of the apparatus main body is opened. The main tank 410 is detachably mounted on the cartridge holder 404. Accordingly, the ink discharge ports 413 of the main tank 410 and the discharge heads 434 for the respective colors communicate with each other via the supply tubes 436 for the respective colors, and the ink can be discharged from the discharge heads 434 to the recording medium.

The recording apparatus can include not only a portion for discharging ink but also a device called a pre-processing device or a post-processing device.
As one mode of the pre-processing device and the post-processing device, the pre-processing device and the post-processing device include a pre-processing liquid and a post-processing liquid as in the case of inks such as black (K), cyan (C), magenta (M), and yellow (Y). There is a mode in which a liquid storage unit and a liquid discharge head are added, and a pretreatment liquid and a post-treatment liquid are discharged by an inkjet recording method.
As another embodiment of the pre-processing device and the post-processing device, there is a mode in which a pre-processing device and a post-processing device other than the ink jet recording method, for example, by a blade coating method, a roll coating method, and a spray coating method are provided.

  The present inventor has found an analysis technique for quantifying the surface distribution and ratio of the resin in a printed image by rough estimation. By acquiring a phase image of a printed image using an atomic force microscope (AFM), it became possible to identify a pigment, a styrene resin, and a urethane resin.

  The tapping mode in the atomic force microscope is a method described in Surface Science Letter, 290, 668 (1993), and the phase image is, for example, Polymer, 35, 5778 (1994), Macromolecules, 28, 6773 (1995). The shape of the sample surface is measured while oscillating the cantilever as described in (1) and the like. At this time, due to the viscoelastic properties of the sample surface, a phase difference occurs between the drive that causes the cantilever to vibrate and the actual vibration. What mapped this phase difference is a phase image.

The contrast of the phase image differs depending on the type of the device. Therefore, the contrast of the phase image is obtained using Dimension Icon from Bruker. When measured using this apparatus, it can be interpreted that in a phase image, the brighter the contrast, the harder the component or the smaller the adsorption. In this case, since the pigment and the styrene resin were hard and the urethane resin was soft, these components could be identified using the difference in viscoelasticity.
In addition, since the absolute value of the phase is low in quantitativeness and depends on the type of the cantilever (lever sensitivity, spring constant, radius of curvature of the tip), the cantilever used is OMCL-AC-240TS-C3 manufactured by Olympus. Shall be used.

As a parameter setting condition using Dimension Icon, it is desirable to measure under the following conditions as a condition for stably measuring a printed matter as in this case.
・ Scan Rate: 0.5Hz
・ Samples / Line: 256
・ Integral Gain: 1.9
・ Proportional Gain: 5
・ Amplitude Setpoint: 250mV
・ Scan Angle: 0 deg

This time, since the contrast of the phase image can be clearly separated, the coverage of the resin component on the surface of the printed image is quantified by binarizing the photograph using image processing software ImageJ.
In this binarization method, a phase image histogram obtained when a printed image is measured shows two distinct peaks, such as a peak A and a peak B defined in the present invention. The result is a split in two. In this case, peak A corresponds to styrene resin particles, and peak B corresponds to urethane resin particles. A threshold value is set at an intermediate portion between these two peaks, and the image is binarized by the image processing software ImageJ. From the binarized image, an area ratio of a white portion and an area ratio of a black portion are calculated by software.

  Since the ink of the present invention has a small amount of pigment and a large amount of resin, it is assumed that the effect of the pigment is negligible during binarization, and the image surface coverage is calculated by approximation. In this case, the same result can be obtained even if the size of the field of view of the AFM for quantifying the coverage is quantified in either a 5 μm square or a 1 μm square.

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

(Preparation Example 1)
-Preparation of Cyan Pigment Surfactant Dispersion A-
-Phthalocyanine pigment: 30.0 parts (CI Pigment Blue 15: 3, manufactured by Dainichi Seika Kogyo Co., Ltd.)
-Polyoxyethylene styrene phenyl ether: 10.0 parts (Nonionic surfactant, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Neugen EA-177, HLB
(Value = 15.7)
・ Ion-exchanged water: 60.0 parts First, the surfactant was dissolved in ion-exchanged water, and the pigment was mixed and sufficiently wetted. Then, a wet disperser (Dynomill KDL A type, manufactured by WAB) was used. Was filled with zirconia beads having a diameter of 0.5 mm and dispersed at 2,000 rpm for 2 hours to obtain a primary pigment dispersion.

-Preparation of aqueous solution A 'of water-soluble polymer compound-
-Α-olefin-maleic anhydride copolymer represented by the following general formula (I) (manufactured by Seiko PMC Co., Ltd., T-YP112, olefin chain (R): having 20 to 24 carbon atoms (in general formula (I) (A copolymer in which R1 corresponds to an alkyl group having 18 to 22 carbon atoms), an acid value of 190 mgKOH / g, and a weight average molecular weight of 10,000) ... 10.0 parts
1N aqueous LiOH solution (1.2 times the acid value of the α-olefin-maleic anhydride copolymer represented by formula (I)) 17.34 parts 72.66 parts

  Next, the mixture is heated and stirred by a stirrer to dissolve the α-olefin-maleic anhydride copolymer represented by the general formula (I), and a trace amount of insoluble matter is filtered through a filter having an average pore diameter of 5 μm. Then, a water-soluble polymer compound aqueous solution A ′ was prepared.

  Next, 7.51 parts of the water-soluble polymer compound aqueous solution A ′ was added to the primary pigment dispersion, and a water-soluble polyester resin (Nichigo Polyester W-0030, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., 29.9% of active ingredient, 2.51 parts of an acid value of 100 mg KOH / g and a weight average molecular weight of 7,000) were added thereto, and sufficiently stirred to obtain a cyan pigment surfactant dispersion A. When the volume-based particle diameter (D50) of the pigment dispersion in the obtained cyan pigment surfactant dispersion A was measured, it was 78 nm. The volume-based particle diameter (D50) was measured using a particle size distribution analyzer (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.).

(Preparation Example 2)
-Preparation of styrene resin A-
St monomer, KH ₂ PO ₄ , methanol, and ethanol used were reagent grades manufactured by Wako Pure Chemical Industries, Ltd. For KOH, a first-class reagent manufactured by Wako Pure Chemical Industries, Ltd. was used, and for NaPSS, a reagent manufactured by Wako Pure Chemical Industries, Ltd. was used. As the water, pure water distilled after an ion exchange treatment was used.
The synthesis was carried out in a four-neck separable flask in a 1 L container equipped with an N ₂ gas inlet tube, a thermometer, a reflux condenser, and a stirrer. Water / methanol mixed solvent (adjusted to be 800 g in total reaction solution, methanol concentration is 0 to 40% of solvent), monomer 2 mol / L (St monomer is 166.64 g), 1 mol / L, KOH aqueous solution 3.19 g (4 × 10 ⁻³ mol / L) and 0.44 g (4 × 10 ⁻³ mol / L) of KH ₂ PO ₄ were mixed. The mixture was stirred at a rotation speed of 300 rpm for about 40 minutes while raising the reaction temperature to 65 ° C. in a water bath and purging with N ₂ gas. _K 2 _S 2 _O 8 0.65g dissolved thereto of water ^{20g (3 × 10 -3 mol /} L) and NaPSS, was added ^{1.65g (10 × 10 -3 mol /} L), subsequently 65 The reaction was carried out at 300 ° C. for 24 hours. The synthesis was completed when the mass of the polymer in the reaction solution with respect to the charged amount of the monomers became 90% or more. The Tg of the synthesized styrene resin A was 50.0 ° C.

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

  In a separable flask equipped with a stirrer, a reflux condenser and a thermometer, 203.4 g of deionized water and 14.8 g of the aqueous dispersion (1) were charged and stirred until the whole became uniform. Under stirring, 0.65 g of 25% aqueous ammonia was added to obtain a colorless and transparent aqueous resin aqueous solution. 25 g of Chemipearl W400 (low molecular weight polyolefin emulsion, solid content: 40%, manufactured by Mitsui Chemicals, Inc.) was added thereto, and the mixture was stirred until the whole became uniform. Further, 22.5 g of styrene was added with stirring, and nitrogen stirring was carried out for 1 hour and 30 minutes to remove dissolved oxygen in the system while stirring. After the completion of bubbling, the temperature was raised to 70 ° C. When the internal temperature reached 70 ° C., 0.32 g of a 10% aqueous solution of 4,4′-azobis (4-cyanopentanoic acid) was added as a water-soluble radical initiator, and after 6 hours, the polymerization was completed. The Tg of the obtained water-dispersible styrene acrylic resin B was 45.0 ° C.

(Preparation Example 4)
-Preparation of styrene acrylic resin C-
As the olefin polymer (1), 1000 g of a propylene-butene-ethylene terpolymer (Bestplast 750, manufactured by Degussa Japan), 100 g of maleic anhydride-modified polypropylene wax (High Wax NP0555A, manufactured by Mitsui Chemicals, Inc.) and olein 40 g of potassium acid (KS Soap, manufactured by Kao Corporation), and supplied from a hopper of a twin screw extruder (PCM-300, L / D = 40, manufactured by Ikegai Iron Works) at a speed of 3000 g / hour. A 17% aqueous solution of potassium hydroxide was continuously supplied at a rate of 120 g / hour (4% based on the whole) from a supply port provided in a vent portion of the extruder, and was continuously extruded at a superheating temperature of 200 ° C. The extruded resin mixture was cooled to 90 ° C. by a jacketed static mixer installed in the extruder, and further poured into hot water at 80 ° C. to obtain an olefin-based heavy fluid having a yield of 99%, a solid concentration of 40%, and a pH of 12. A combined aqueous dispersion (2) was obtained.
In a separable flask equipped with a stirrer, a reflux condenser and a thermometer, 217.3 g of deionized water and 2.3 g of sodium dodecylsulfonate as an anionic dispersant were charged and stirred until the whole became uniform. Under stirring, 0.65 g of 25% aqueous ammonia was added, and 25 g of an aqueous dispersion (2) of an olefin polymer was added, followed by stirring until the whole became uniform. Further, a mixed solution of 10.2 g of styrene and 12.4 g of butyl acrylate was added with stirring, and nitrogen stirring was performed for 1 hour and 30 minutes to remove dissolved oxygen in the system with stirring. After the completion of bubbling, the temperature was raised to 70 ° C. When the internal temperature reached 70 ° C., 0.32 g of a 10% aqueous solution of 4,4′-azobis (4-cyanopentanoic acid) was added as a water-soluble radical initiator, and after 6 hours, the polymerization was completed. The Tg of the water-dispersible styrene acrylic resin C was 30.0 ° C.

(Preparation Example 5)
-Procurement of urethane resin D-
This time, Takerack W6110 (polyurethane resin) manufactured by Mitsui Chemicals, Inc. was obtained and used for ink preparation. The Tg of the obtained urethane resin D was -20.0 ° C.

[Examples 1 to 4, Comparative Examples 1 to 5]
Ink jet inks of Examples 1 to 4 and Comparative Examples 1 to 5 were produced using the respective components as shown in Table 1. The pigment dispersion liquid used in Preparation Example 1, the styrene resin used in Preparation Example 2, the styrene acrylic resin used in Preparation Examples 3 and 4, and the urethane resin used in Preparation Example 5 were used.

The components shown in Table 1 by abbreviated names are as described below.
-Zonyl FS-300: polyoxyethylene perfluoroalkyl ether (manufactured by Dupont, component 40%).
-Proxel GXL: a fungicide containing, as a main component, 1,2-benzisothiazolin-3-one (Avisia Co., component 20%, containing dipropylene glycol).
-KM-72F: Self-emulsifying type silicone antifoaming agent (Shin-Etsu Silicone Co., Ltd., component 100%).

Next, each of the inkjet inks of Examples 1 to 4 and Comparative Examples 1 to 5 was evaluated by the evaluation method described below.
-Preparation for print evaluation-
Driving of the piezo element using an inkjet printer (IPSiO GXe-5500, manufactured by Ricoh Co., Ltd.) under the environmental conditions adjusted to 23 ± 0.5 ° C. and 50 ± 5% RH so that the ink ejection amount becomes uniform. The voltage was changed so that the same amount of ink was applied to the recording medium. Two types of print images were prepared: an image to be left at room temperature and an image to be put into a thermostat at 100 ° C. for 1 minute.

<Blocking>
Immediately after printing and discharging, the back surface of the same medium was pressed against the “シ ア ン” portion of the chart cyan solid printing surface with the 64-point character “■” prepared by Microsoft Word 2000, and the presence or absence of transfer was determined.
〔Evaluation criteria〕
○: No transfer dirt △: Slight transfer dirt x: Transfer dirt

<Extensibility>
The degree of transfer contamination due to rubbing 20 times from the obtained solid cyan portion to the background portion was visually evaluated. The ranking was evaluated according to the following criteria. At this time, a printed image after heating was used.
；: Invisible △: faintly visible ×: clearly visible

<Storage stability of ink>
Using the viscometer, the storage stability was determined from the viscosity before storage and the viscosity measured after storage in a sealed container at 70 ° C. for 7 days according to the following formula, and evaluated based on the following evaluation criteria. Ink storage stability (%) = [(viscosity after storage) / (viscosity before storage)] × 100
〔Evaluation criteria〕
：: within 100 ± 10%.
Δ: More than 100 ± 10 to less than 20%.
X: 100 ± 20% or more.
<Image observation with an atomic force microscope>
Using a Dimension Icon manufactured by Bruker, the cantilever was observed using an OMCL-AC240-TS-C3 cantilever in a 1-μm square visual field using an atomic force microscope (AFM) to observe a printed image by tapping mode measurement. The obtained photograph was binarized by ImageJ software, the bright part was discriminated as styrene resin, and the dark part was discriminated as urethane resin. The influence of pigment was ignored, and the coverage on each image was quantified by approximation. did.
3 to 5 are diagrams showing the results of observing the printed image of the ink of Example 4 with an atomic force microscope (AFM).
FIG. 3 shows a phase image before heating, and FIG. 4 shows a phase image after heating. FIG. 5 is a diagram showing a histogram of an AFM phase image of a print image.

  In FIG. 3, the styrene resin particles are observed as a bright particle with the styrene resin particles remaining as the resin particles due to the high influence of the Tg of the styrene resin particles. Since the Tg of the urethane resin particles is lower than room temperature, a dark contrast portion between the styrene resin particles corresponds to the urethane resin. As can be seen from FIG. 4, the styrene resin particles are formed by the heating step. The styrene resin particles are formed into a film and become flat, and the urethane resin particles are distributed in a state where the film is formed. When the ratio of the styrene resin occupied on the image and the ratio of the urethane resin particles at this time were quantified by the image processing software ImageJ, the results are as shown in Table 2, and the styrene resin sank by heating and the urethane resin You can see that it is exposed to The vertical axis of the phase histogram in FIG. 5 is the frequency of the phase value in the image.

<Measurement of amount of pure water transferred by dynamic scanning absorptiometer>
With respect to the recording paper Lumi Art Gloss 90 gsm used this time, the absorption curve of pure water was measured using a dynamic scanning liquid absorption meter (model: KS350D, manufactured by Kyowa Seiko Co., Ltd.). The absorption curve was plotted with the transfer amount (mL / m ² ) and the square root of the contact time √ (ms) to form a straight line having a certain slope, and the value of the transfer amount after a certain time was measured by interpolation. The transfer amount of Lumi Art Gloss 90 gsm was 5 ml / m ² .
However, it is known that media such as offset coated paper such as Lumi Art Gloss 90 gsm has pores on the surface, and it is conceivable that the transfer amount may vary depending on the location in the recording paper. Therefore, it the amount of transfer of the surface having the coating layer of the recording medium of pure water at a contact time of 100ms measured by a dynamic scanning absorptometer is 1ml / m ² ~10ml / m ² preferable.
In this ink evaluation, all recording paper used Lumi Art Gloss 90 gsm.
Table 2 shows the results of the print image.

It was confirmed that inks having a slightly higher ratio of the styrene resin, with a mixture of styrene particles and urethane resin, could satisfy all the qualities relatively. It was confirmed that the quality was satisfactory if the combination of styrene acrylic resin and urethane resin was styrene rich.
Before heating the printed image, the resin surface cover ratio is almost the same as the ink preparation amount. However, it can be seen that the ratio of styrene resin, which is a high-phase component, on the surface decreases by heating and drying. The change in the coverage of the resin exposed on the surface due to heating and drying is because the surface of the coated paper, which is the media, is hydrophobic, so the hydrophobic styrene resin sinks inside during heating and drying, and It is presumed that the urethane resin may remain on the surface of the image area.

400 Image forming apparatus 401 Exterior 401c Cover 404 Cartridge holder 410, 410k, 410c, 410m, 410y Main tank 411 Ink storage unit 413 Ink discharge port 414 Storage container case 420 Mechanism unit 434 Discharge head 436 Supply tube L Ink storage container

JP 2011-153180 A JP 2003-96342 A JP 2014-172987 A

Claims (12)

An organic solvent, water, and ink containing a coloring material,
The ink includes urethane resin particles and styrene resin particles,
An image Y obtained by heating and drying the image X formed by applying the ink to the recording medium has a peak A (Y) and a peak B (Y) in the histogram of the AFM phase image, and the peak A (Y ) Is an area of 6 degrees or more and 20 degrees or less, the peak B (Y) is an area of -17 degrees or more and -10 degrees or less, and the image surface coverage of the peak A (Y) is 50-60%. And an ink having a peak B (Y) image surface coverage of 40 to 50%.   The ratio (A (Y) / B (Y)) of the image surface coverage of the peak A (Y) to the image surface coverage of the peak B (Y) is 1.0 to 1.5. The ink according to claim 1, wherein:   In the image X, the histogram of the AFM phase image has a peak A and a peak B, the peak A (X) is a region of 10 degrees or more and 21 degrees or less, and the peak B (X) is -16 degrees or more. A region of 8 degrees or less, wherein the peak A (X) has an image surface coverage of 65 to 75%, and the peak B (X) has an image surface coverage of 25 to 35%. The ink according to claim 1.   The ratio (A (X) / B (X)) of the image surface coverage of the peak A (X) to the image surface coverage of the peak B (X) is 2.0 or more and 2.5 or less. The ink according to claim 3, characterized in that:   The mass ratio (urethane resin particle / styrene resin particle) between the content (% by mass) of the urethane resin particles and the content (% by mass) of the styrene resin particles is 0.3 or more and 0.6 or less. The ink according to any one of claims 1 to 4, wherein:   The ink according to claim 1, wherein a minimum film forming temperature of the styrene resin particles is 45 ° C. or higher.   The difference (Tg (S) -Tg (U)) between Tg (S) of the styrene resin particles and Tg (U) of the urethane resin particles is not less than 60 ° C and not more than 80 ° C. 6. The ink according to any one of 6. The recording medium has a coating layer on at least one surface of the support, the ink is applied to the surface having the coating layer, and a contact time of 100 ms measured by a dynamic scanning liquid absorption meter. the ink according to claim 1, the transfer amount of the surface having the coating layer of the recording medium of the pure water is characterized by a 1ml / m ² ~10ml / m ² in.   An ink container, wherein the ink according to claim 1 is stored in a container.   An image recording method comprising a step of obtaining an image Y by heating and drying an image X formed by applying ink to a recording medium, wherein the ink is the ink according to any one of claims 1 to 8. Characteristic image recording method. The image recording method according to claim 10, wherein a heating temperature in the heating and drying is 90C or more and 110C or less.   An image recording apparatus comprising: an ink; a unit for applying the ink to a recording medium to obtain an image X; and a heating and drying unit for heating and drying the image X to obtain an image Y. 8. An image recording apparatus comprising the ink according to any one of 8.