JP7218501B2 - IMAGE FORMING METHOD, IMAGE FORMING APPARATUS, AND PRINTED MATERIAL MANUFACTURING METHOD - Google Patents

Description

The present invention relates to an image forming method, an image forming apparatus, and a method for producing printed matter.

Inkjet recording has become popular because of its simpler process than other recording methods, the ease with which full-color printing can be achieved, and the ability to obtain high-resolution images even with a simple device. It is spreading from personal use to office use, commercial printing and industrial printing. In such an inkjet recording method, a water-based ink composition using a water-soluble dye as a coloring material is mainly used. The development of pigment inks using pigments from

In inkjet printing for office use, plain paper is mainly used as a recording medium, and high image density is required. In general, when pigment ink is printed on plain paper, the pigment permeates into the paper without remaining on the surface of the paper, resulting in a lower pigment density on the paper surface and a lower image density. If the pigment concentration in the ink is increased, the image density is increased, but the viscosity of the ink is increased and the ejection stability is lowered. Therefore, the choice of pigment is greatly influenced not only by the desired image properties, but also by the mechanical properties used.

Patent Documents 1 to 3 disclose ink compositions using diketopyrrolopyrrole pigments.

In general, color prints are preferred for images with a wide range of hues and high chroma, and inks are required to have the properties to achieve these. Four colors of ink, cyan, magenta, yellow, and black, are generally used.
Dispersibility is required as an important property for pigments used in inks. Pigments that can be physically dispersed by kneading, such as plastics and crayons, do not pose a problem in terms of hue and saturation. It is difficult to use pigments that are easy to remove. Among cyan, magenta, yellow, and black pigments, the magenta pigment is especially difficult to disperse.
Also, when a plurality of pigments are used for each color, the hue tends to be broadened, but the chroma and vividness tend to decrease. There are roughly two methods for selecting pigments that achieve both hue and saturation. The first is to select a single pigment with moderate hue and vividness, and the second is to combine multiple pigments with high vividness.

In the former method, quinacridone-based pigments are representative from the aspect of hue, chroma, and lightfastness, but there is a problem with dispersibility, and quinacridone-based pigments modified with functional groups are used. Not all of the many quinacridone-based pigments can be used, so the degree of freedom in designing the hue is not high.
Although the latter method has a high degree of freedom in hue, there is concern about another problem due to the use of multiple pigments. Specifically, image characteristics include uneven image formation due to separation and uneven distribution of different types of pigments.

Azo pigments are also typical magenta pigments, but they have problems such as low light resistance and discoloration of the printed matter over a long period of time depending on the intended use of the printed matter.

Diketopyrrolopyrrole pigments are magenta pigments that are characteristically high in chroma. Diketopyrrolopyrrole pigments have high lightfastness and higher chroma than quinacridone pigments. not satisfied. For example, in order to use a diketopyrrolopyrrole pigment as a magenta pigment, it is necessary to use it in combination with another pigment that imparts a bluish tint. However, when multiple organic crystal pigments are used, separation/maldistribution tends to occur due to differences in crystal structure/affinity. Especially when used in inkjet printing, pigment separation is faster than with plastic or paint because the viscosity of the ink is lower than that of plastic or paint, and the separation/uneven distribution of the pigment can be seen visually because the film thickness of the formed image is thin. Cheap. Therefore, the deterioration of the image quality due to hue variation within the same plane is remarkable, and problems such as so-called beading tend to occur. In particular, when a bluish magenta pigment and a yellowish magenta pigment are mixed, even a slight separation results in a large color difference, which is visually distinct and tends to result in an image with impaired uniformity. Therefore, it has been difficult to use diketopyrrolopyrrole-based pigments as pigments for inkjet printing.
In addition, since there are few types of inexpensive substituted/modified diketopyrrolopyrroles, the degree of freedom in hue design is low, and there are not many examples of using them in inks. In addition, similar to quinacridone pigments, they are relatively coarse organic pigment crystals, and have problems such as dispersibility and uneven distribution.

On the other hand, as described above, Patent Documents 1 to 3 disclose ink compositions using diketopyrrolopyrrole-based pigments. In addition to ketopyrrolopyrrole, it is essential to use a resin emulsion containing a dye and an inorganic pigment in combination, which poses a problem of image non-uniformity due to uneven distribution of materials. In addition, the compositions described in Patent Documents 2 and 3 cannot be said to have both hue and chroma, and there is also a problem of hue variation within the surface of the printed matter.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming method that achieves both hue and chroma while using highly light-resistant organic pigment crystals, and that has less hue and variation within the surface of printed matter.

The above problem is solved by the following configuration 1).
1) In an image forming method comprising an ink applying step of applying ink to a recording medium and a drying step of drying the recording medium after the ink applying step,
The ink applying step has a magenta ink applying step of applying a magenta ink containing water, a diketopyrrolopyrrole pigment, a quinacridone pigment and a resin, and the drying step includes a conveying speed of 30 to 150 m/min and a An image forming method characterized by being carried out at a temperature of 140°C .

According to the present invention, it is possible to provide an image forming method that achieves both hue and chroma while using organic pigment crystals with high light resistance, and that has little variation in hue within the surface of a printed matter.

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

As a result of extensive studies by the present inventors, even in inkjet printing, when a diketopyrrolopyrrole pigment and a quinacridone pigment are used in combination as magenta pigments, and when used in a high-speed printing machine equipped with a drying mechanism, etc., high clarity It was found that an image with a suitable hue can be obtained while maintaining the
Although the mechanism is not clear, when a high-saturation diketopyrrolopyrrole pigment and quinacridone are combined, the saturation generally decreases due to the mixture of the pigments, and beading occurs due to the progress of separation. For example, by fixing the pigment at a high speed, it is possible to prevent the occurrence of pigment aggregates, prevent the chroma from being lowered, and suppress the beading while maintaining the preferred mixed state of the hue.

Embodiments of an image forming method, an image forming apparatus, and a printed matter manufacturing method according to the present invention will be described below. In addition, the present invention is not limited to the embodiments shown below, and can be changed within the scope of those skilled in the art, such as other embodiments, additions, modifications, deletions, etc. is also included in the scope of the present invention as long as the functions and effects of the present invention are exhibited.

The image forming method and the printed matter manufacturing method of the present invention comprise an ink application step of applying ink to a recording medium to form an image, and a drying step of drying the recording medium after the ink application step, The ink applying step is characterized by having a magenta ink applying step of applying a magenta ink containing water, a diketopyrrolopyrrole pigment, a quinacridone pigment and a resin.
Further, the image forming apparatus of the present invention comprises ink applying means for applying ink to a recording medium to form an image, and drying means for drying the recording medium after the ink applying step, wherein the ink applying means , water, a diketopyrrolopyrrole pigment, a quinacridone pigment and a resin.
The ink applying step and ink applying means can include known steps and means for applying black, cyan, and yellow inks.

<Ink>
Organic solvents, water, coloring materials, resins, additives, and the like used in the ink are described below.

<Organic solvent>
The organic solvent used in the present invention is not particularly limited, and any 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, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl- Polyhydric alcohols such as 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 monoethyl Polyhydric alcohol alkyl ethers such as ethers, 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, nitrogen-containing heterocyclic compounds such as γ-butyrolactone, formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N- Amides such as 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. etc.
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. 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. % to 60% by mass is more preferred.

In the present invention, each known color ink can be used.

<Color material>
The coloring material is not particularly limited except that the magenta ink contains a diketopyrrolopyrrole pigment and a quinacridone pigment, and pigments and dyes can be used.
An inorganic pigment or an organic pigment can be used as the pigment. These may be used individually by 1 type, and may use 2 or more types together. Mixed crystals may also be used.
Examples of pigments that can be used include black pigments, yellow pigments, magenta pigments, cyan pigments, white pigments, green pigments, orange pigments, glossy color pigments such as gold and silver, and metallic pigments.

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 known methods such as contact method, furnace method, thermal method, etc. can be used.

Organic pigments include azo pigments, polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.). , dye chelates (eg, basic dye chelates, acid dye chelates, etc.), nitro pigments, nitroso pigments, aniline black, and the like. Among these pigments, those having good affinity with the solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used.
Specific examples of pigments for black include carbon blacks (C.I. Pigment Black 7) such as furnace black, lamp black, acetylene black and channel black, or copper and iron (C.I. Pigment Black 11). , metals such as titanium oxide, and organic pigments such as aniline black (C.I. 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 (PR) 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 (red red), 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, 255, 264, C.I. I. Pigment Violet (PV) 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, etc.
As dyes, acid dyes, direct dyes, reactive dyes, and basic dyes can be used without particular limitation, and may be used singly or in combination of two or more.
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. and Reactive Black 3,4,35.

The present invention requires that the magenta ink contains a diketopyrrolopyrrole pigment and a quinacridone pigment.
The diketopyrrolopyrrole pigment is one or two or more pigments selected from CIPR254, CIPR255 and CIPR264 from the viewpoint of achieving both hue and chroma, and less variation in hue within the surface of the printed matter. is preferred.
In addition, it is one of the quinacridone pigments selected from CIPR122, CIPR202, and CIPV19 from the viewpoint of improving the lightfastness and image density of the image, achieving both hue and saturation, and reducing hue and variation within the printed surface. Alternatively, two or more pigments are preferred.

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 improving image density, good fixability, and ejection stability. It is below.

In order to disperse the pigment and obtain an ink, there are a method of introducing a hydrophilic functional group into the pigment to make it a self-dispersing pigment, a method of coating the surface of the pigment with a resin for dispersion, and a method of dispersing using a dispersant. method, etc.
As a method of making a self-dispersing pigment by introducing a hydrophilic functional group into a pigment, for example, a method of adding a functional group such as a sulfone group or a carboxyl group to a pigment (for example, carbon) to make it dispersible in water. is mentioned.
As a method of coating the surface of a pigment with a resin and dispersing it, there is a method of encapsulating the pigment in microcapsules to make it dispersible in water. This can be rephrased as a resin-coated pigment. In this case, all the pigments mixed in the ink need not be coated with a resin, and uncoated pigments or partially coated pigments may be dispersed in the ink as long as the effects of the present invention are not impaired. may be
Examples of the method of dispersing using a dispersant include a method of dispersing using a known low-molecular-weight dispersant and high-molecular-weight dispersant typified by surfactants.
As the dispersant, it is possible to use, for example, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. depending on the pigment.
RT-100 (nonionic surfactant) manufactured by Takemoto Yushi Co., Ltd. and sodium naphthalenesulfonate formalin condensate can also be suitably used as a dispersant.
A dispersing agent may be used individually by 1 type, or may use 2 or more types together.

<Pigment dispersion>
Inks can be obtained by mixing materials such as water and organic solvents with pigments. Ink can also be produced by mixing a pigment, water, a dispersant, and the like to form a pigment dispersion, and then mixing materials such as water and an organic solvent.
The pigment dispersion is obtained by mixing and dispersing water, a pigment, a pigment dispersant, and optionally other components, and adjusting the particle size. Dispersion should be carried out using a disperser.
The particle diameter of the pigment in the pigment dispersion is not particularly limited, but the dispersion stability of the pigment is improved, and the image quality such as ejection stability and image density is improved. 500 nm or less is preferable, and 20 nm or more and 150 nm or less is more preferable. The particle size of the pigment can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).
The content of the pigment in the pigment dispersion is not particularly limited and can be appropriately selected according to the purpose. % or more and 50 mass % or less is preferable, and 0.1 mass % or more and 30 mass % or less is more preferable.
The pigment dispersion is preferably degassed by filtering coarse particles with a filter, a centrifugal separator, or the like, if necessary.

<Resin>
The type of resin contained in the ink is not particularly limited and can be appropriately selected according to the purpose. resins, styrene-butadiene-based resins, vinyl chloride-based resins, acrylic-styrene-based resins, acrylic-silicone-based resins, and the like.
Resin particles made of these resins may also be used. Ink can be obtained by mixing resin particles in a resin emulsion state in which water is dispersed as a dispersion medium with a material such as a coloring material or an organic solvent. As the resin particles, appropriately synthesized ones may be used, or commercially available products may be used. Moreover, these may be used individually by 1 type, or may be used in combination of 2 or more types of resin particles.

The volume average particle diameter of the resin particles is not particularly limited and can be appropriately selected according to the intended purpose. 200 nm or less is more preferable, and 10 nm or more and 100 nm or less is particularly preferable.
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 resin is not particularly limited and can be appropriately selected according to the purpose. However, 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 preferable, and 5% by mass or more and 20% by mass or less is more preferable.

The particle size of the solid content in the ink is not particularly limited and can be appropriately selected according to the purpose. is preferably 20 nm or more and 1000 nm or less, more preferably 20 nm or more and 150 nm or less. The solid content includes resin particles, pigment particles, and the like. The particle size can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

<Additive>
Surfactants, antifoaming agents, antiseptic antifungal agents, anticorrosive agents, pH adjusters, etc. may be added to the ink as necessary.

<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 preferable. Those having an oxyethylene group or a polyoxyethylene polyoxypropylene 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 the perfluoroalkylsulfonic acid compound include perfluoroalkylsulfonic acid and perfluoroalkylsulfonate. Examples of the perfluoroalkylcarboxylic acid compounds include perfluoroalkylcarboxylic acids and perfluoroalkylcarboxylic acid salts. As the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in a side chain, a sulfate ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in a side chain, and a perfluoroalkyl ether group in a side chain Examples thereof include salts of polyoxyalkylene 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 acetates, dodecylbenzene sulfonates, laurates, and salts of polyoxyethylene alkyl ether sulfates.
These may be used individually by 1 type, or may use 2 or more types together.

The silicone-based surfactant is not particularly limited and can be appropriately selected depending on the intended purpose. Examples include polydimethylsiloxane modified at both chain ends, and polyether-modified silicone-based surfactants having polyoxyethylene groups or polyoxyethylene-polyoxypropylene groups as modifying groups exhibit excellent properties as water-based surfactants. preferable.
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 the general formula (S-1), m, n, a, and b each independently represent an integer, R represents an alkylene group, and R' represents an alkyl group.)
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.

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, polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain are preferable because of their 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.

General formula (F-2)
_{CnF2n +1-} CH2CH(OH) _{CH2 -} O-( _CH2CH2O ) _{a -} Y

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.

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.

<Pretreatment liquid>
The pretreatment liquid contains a flocculant, an organic solvent, and water, and may optionally contain a surfactant, an antifoaming agent, a pH adjuster, an antiseptic agent, an antirust agent, and the like.
Organic solvents, surfactants, antifoaming agents, pH adjusters, antiseptic antifungal agents, and antirust agents can be the same materials as those used for inks, and other materials used for known treatment liquids can be used. .
The type of flocculant is not particularly limited, and examples thereof include water-soluble cationic polymers, acids, polyvalent metal salts, and the like.

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

<Recording medium>
The recording medium used for recording is not particularly limited, but includes plain paper, glossy paper, special paper, cloth, film, OHP sheet, general-purpose printing paper, and the like.

The recording medium is not limited to those used as general recording media, and wallpaper, floor materials, building materials such as tiles, cloth for clothing such as T-shirts, textiles, leather, and the like can be used as appropriate. Ceramics, glass, metal, etc. can also be used by adjusting the configuration of the path for conveying the recording medium.

<Records>
The ink recorded matter 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 with an inkjet recording apparatus and an inkjet recording method.

<Recording device, recording method>
The ink of the present invention can be suitably used for various inkjet recording apparatuses, such as printers, facsimile machines, copiers, printer/facsimile/copier complex machines, stereolithography machines, and the like.
In the present invention, a recording apparatus and a recording method refer to an apparatus capable of ejecting ink, various treatment liquids, and the like onto a recording medium, and a method of performing recording using the apparatus. A recording medium means a medium to which ink or various processing liquids can adhere even temporarily.
This recording apparatus can include not only a head portion for ejecting ink, but also means for feeding, conveying, and discharging a recording medium, and other devices called pre-processing devices and post-processing devices. .
As for the recording apparatus and the recording method, it is preferable to use heating means used in the heating process and drying means used in the drying process. 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, an infrared drying device, a microwave drying device, hot air, a heat roller, a heat drum, or the like can be used. Heating and drying can be performed before, during, or after printing.

In the present invention, the drying process is preferably carried out at a conveying speed of 30-150 meters/minute, more preferably at a conveying speed of 50-120 meters/minute. The drying speed can be controlled by the conveying speed of the recording medium.
In this specification, the term "conveyance speed" refers to the speed at which blocking does not occur when the printing speed is changed from high to low at a constant drying temperature.
Here, the occurrence of blocking is defined as the occurrence of image destruction or color shift when the contact portion between the printed portion on the front side of the paper and the back side of the paper as a recording medium is peeled off 10 minutes after printing. .
However, although it is possible to apply an excessive drying temperature at low speed printing in terms of operation settings, the paper will turn yellow if it is dried at low speed and high temperature. do.
The drying temperature is, for example, 80-140°C, preferably 100-120°C.

Also, the recording apparatus and recording method are not limited to those that visualize 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 FIGS. 1 and 2. FIG. FIG. 1 is a perspective explanatory view of the device. FIG. 2 is a perspective explanatory view of the main tank. An image forming apparatus 400 as an example of a recording apparatus is a serial image forming apparatus. A mechanical unit 420 is provided inside the exterior 401 of the image forming apparatus 400 . Each ink container 411 of the main tank 410 (410k, 410c, 410m, 410y) for each color of black (K), cyan (C), magenta (M), and yellow (Y) is packed with, for example, an aluminum laminated film. It is made up of members. The ink containing portion 411 is housed, for example, in a container case 414 made of plastic. Thus, the main tank 410 is used as an ink cartridge for each color.
On the other hand, a cartridge holder 404 is provided on the far side of the opening when the cover 401c of the apparatus main body is opened. A main tank 410 is detachably attached to the cartridge holder 404 . As a result, each ink discharge port 413 of the main tank 410 communicates with the ejection head 434 for each color via the supply tube 436 for each color, and ink can be ejected from the ejection head 434 onto the printing medium.

This recording apparatus can include not only a portion that ejects ink, but also devices called pre-processing devices and post-processing devices.
As an aspect of the pre-treatment device and the post-treatment device, it has a pre-treatment liquid and a post-treatment liquid in the same manner 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 container and a liquid ejection head are added, and the pretreatment liquid and the posttreatment liquid are ejected by an inkjet recording method.
As another aspect of the pre-treatment device and the post-treatment device, there is an aspect in which a pre-treatment device and a post-treatment device using a method other than the inkjet recording method, such as a blade coating method, a roll coating method, and a spray coating method, are provided.

The use of the ink of the present invention is not particularly limited and can be appropriately selected according to the intended purpose. Furthermore, it can be used not only as an ink to form two-dimensional characters and images, but also as a three-dimensional modeling material for forming a three-dimensional three-dimensional image (three-dimensional object).
A known three-dimensional modeling apparatus for forming three-dimensional objects can be used, and is not particularly limited. be able to. The three-dimensional object includes a three-dimensional object obtained by applying ink repeatedly. It also includes a molded product obtained by processing a structure obtained by applying ink onto a base material such as a recording medium. The molded product is, for example, a sheet-shaped or film-shaped recorded matter or structure that has been subjected to molding such as heat stretching or punching.・Suitably used for applications where molding is performed after the surface is decorated, such as electronic equipment, meters for cameras, and operation panels.

In the present invention, the terms image formation, recording, printing, and printing are all synonymous.

The terms recording medium, medium, and printed material are all synonymous.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. "Parts" and "%" in the examples are "mass parts" and "mass%" unless otherwise specified. Further, Examples 17 to 19 refer to Reference Examples 17 to 19 which are not included in the present invention.

-Preparation of pigment-dispersed polymer solution-
After sufficiently replacing the inside of a 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube, and dropping funnel with nitrogen gas, 11.2 g of styrene, 2.8 g of acrylic acid, and 12.0 g of lauryl methacrylate were added. , 4.0 g of polyethylene glycol methacrylate, 4.0 g of styrene macromer, and 0.4 g of mercaptoethanol were mixed and heated to 65°C.
Next, styrene 100.8 g, acrylic acid 25.2 g, lauryl methacrylate 108.0 g, polyethylene glycol methacrylate 36.0 g, hydroxylethyl methacrylate 60.0 g, styrene macromer 36.0 g, mercaptoethanol 3.6 g, azobismethyl valero. A mixed solution of 2.4 g of nitrile and 18.0 g of methyl ethyl ketone was dropped into the flask over 2.5 hours. After dropping, a mixed solution of 0.8 g of azobismethylvaleronitrile and 18 g of methyl ethyl ketone was dropped into the flask over 0.5 hours. After aging at 65° C. for 1 hour, 0.8 g of azobismethylvaleronitrile was added and further aged for 1 hour. After completion of the reaction, 364.0 g of methyl ethyl ketone was added into the flask to obtain 800 g of a polymer solution having a concentration of 50% by mass.

-Preparation of Magenta Pigment Dispersion-
28 g of the polymer solution, 42 g of CIPR254, 13.6 g of a 1 mol/L potassium hydroxide aqueous solution, 20.0 g of methyl ethyl ketone, and 13.6 g of deionized water were sufficiently stirred and kneaded using a roll mill.
The obtained paste was poured into 200 g of pure water and stirred thoroughly. Methyl ethyl ketone and water were distilled off using an evaporator. A magenta pigment dispersion of CIPR254 having a pigment content of 15% by mass and a solid content of 20% by mass was obtained by pressure filtration.
Dispersions of CIPR255, PR264, PR122, PR202, PV19 and PR53:1 were obtained in the same manner.

―Creation of magenta ink 1 to 19―
After mixing and stirring the formulation (parts by mass) shown in Table 1, the pH was adjusted to 9 with a 10% aqueous solution of lithium hydroxide. After that, filtration was performed using a membrane filter having an average pore size of 0.1 μm to obtain magenta inks 1 to 19.

[Image formation]
Using the obtained inks 1 to 19, the resolution/ Magenta solid images of Examples 1 to 19 and Comparative Examples 1 to 9 were recorded at the conveying speed. For color reproducibility evaluation, a cyan solid image and a yellow solid image were prepared using commercially available cyan ink and yellow ink (ink for RICOH Pro VC60000 manufactured by Ricoh).

<Saturation>
Select 20 points from the magenta solid image of each image obtained in Examples 1 to 19 and Comparative Examples 1 to 9, and measure the brightness using a colorimeter (Handy type image evaluation system PIAS-II manufactured by Trek Japan). Then, from the obtained a* and b* values, chroma C ^* =[(a ^* ) ² +(b ^* ) ² ] ^1/2 was calculated, and the average value of 20 points was calculated. The ratio k=C ^* /C ^* ₀ to the saturation value C ^* ₀ of the standard color (Japan color ver.2) was calculated and evaluated according to the following evaluation criteria. C or higher is practical.
(Evaluation criteria)
A: 1.00 > k > 0.975
B: 0.975>k≧0.95
C: 0.95>k≧0.90
D: 0.90>k

<Saturation distribution>
Among the 20 k values measured in the above chroma evaluation, the maximum k was kmax, the minimum k was kmin, and kr=kmin/kmax was used as the chroma distribution and evaluated according to the following evaluation criteria. C or higher is practical.
(Evaluation criteria)
A: 1.00>kr≧0.975
B: 0.975>kr≧0.95
C: 0.95>kr≧0.90
D: 0.90>kr

<Color reproducibility>
Using a colorimeter (handy type image evaluation system PIAS-II manufactured by Trek Japan Co., Ltd.), measure the color reproduction area on the CIE-a* and b* sides of the standard printed matter of Japan Color-2001, and measure the area (1). asked.
Select 20 points from the magenta solid images of each image obtained in Examples and Comparative Examples, and use commercially available cyan ink and yellow ink (ink for RICOH Pro VC60000 manufactured by Ricoh) for Examples 1 to 19 and Comparative Examples. Using a solid cyan image and a solid yellow image under the same conditions as 1 to 9, using a colorimeter (handy type image evaluation system PIAS-II manufactured by Trek Japan) on the CIE-a* and b* planes. The color reproduction area (2) at L*=50 was obtained as an average value of 20 points.
The color reproduction rate was evaluated as (area (2)/area (1))×100 according to the following evaluation criteria. C or higher is practical.
A: 95% or more B: 90% or more and less than 95% C: 80% or more and less than 90% D: less than 80%

<Hue distribution>
Using the a* value and b* value obtained by measurement using a colorimeter (handy type image evaluation system PIAS-II manufactured by Trek Japan Co., Ltd.) in the 20 points of the magenta solid portion measured in the saturation evaluation, Hue angle (h) is calculated from h=tan ⁻¹ (b*/a*).
The maximum h of the 20 points was defined as hmax, the minimum h was defined as hmin, and hr=hmin/hmax was defined as the hue distribution and evaluated according to the following evaluation criteria. C or higher is practical.
(Evaluation criteria)
A: 1.00>hr≧0.975
B: 0.975>hr≧0.95
D: 0.95>hr≧0.90
C: 0.90>hr

Table 2 shows the results.

As in Examples 1 to 19, a magenta ink containing water, a diketopyrrolopyrrole pigment, a quinacridone pigment, and a resin, and having a drying process to form an image, showed poor chroma and color reproducibility. A good uniform image was obtained with not only good quality but also a suppressed in-plane distribution. When the conveying speed is slow, the saturation and hue start to vary within the plane of the paper, resulting in a slightly worse distribution, but within a practical range. When the drying process is not performed as in Comparative Examples 7, 8, and 9, the distribution is significantly deteriorated, making it unpractical.
When only the diketopyrrolopyrrole pigment was used as in Comparative Examples 1 and 2, the color reproducibility was insufficient due to its characteristic hue. As in Comparative Examples 3 and 4, quinacridone-based pigments have insufficient chroma. Even when a diketopyrrolopyrrole pigment and other pigments are used in combination as in Comparative Examples 5 and 6, when they are used in combination with an azo pigment, the chroma and hue distribution within the paper surface is observed, resulting in an uneven image due to uneven distribution of the pigment. was gotten.

400 Image forming apparatus 401 Exterior of image forming apparatus 401c Cover of apparatus main body 404 Cartridge holder 410 Main tank 410k, 410c, 410m, 410y For black (K), cyan (C), magenta (M), and yellow (Y) main tank 411 ink storage unit 413 ink discharge port 414 storage container case 420 mechanism unit 434 ejection head 436 supply tube

JP 2008-255241 A Japanese Patent No. 5448735 Japanese Patent No. 5641929

Claims (7)

In an image forming method comprising an ink application step of applying ink to a recording medium and a drying step of drying the recording medium after the ink application step,
The ink application step includes a magenta ink application step of applying a magenta ink containing water, a diketopyrrolopyrrole pigment, a quinacridone pigment and a resin,
An image forming method, wherein the drying step is carried out at a conveying speed of 30 to 150 m/min and a temperature of 80 to 140°C . 2. The image forming method according to claim 1, wherein said diketopyrrolopyrrole pigment is one or more pigments selected from C.I.PR254, C.I.PR255 and C.I.PR264. 3. The image forming method of claim 1, wherein the quinacridone pigment is one or more pigments selected from C.I.PR122, C.I.PR202 and C.I.PV19. 4. The image forming method according to any one of claims 1 to 3, wherein the drying step is carried out at a conveying speed of 50 to 120 meters/minute. wherein the diketopyrrolopyrrole pigment is a pigment selected from CIPR254, CIPR255 and CIPR264;
The quinacridone pigment is one or more pigments selected from CIPR122, CIPR202 and CIPV19,
2. The image forming method according to claim 1, wherein the diketopyrrolopyrrole pigment is of two or more kinds. ink applying means for applying ink to a recording medium;
drying means for drying the recording medium after applying the ink;
The ink applying means has a magenta ink applying means for applying a magenta ink containing water, a diketopyrrolopyrrole pigment, a quinacridone pigment and a resin,
The image forming apparatus, wherein the drying means performs drying at a conveying speed of 30 to 150 meters/minute and a temperature of 80 to 140.degree . In a method for producing a printed matter, which includes an ink application step of applying ink to a recording medium, and a drying step of drying the recording medium after the ink application step,
The ink application step includes a magenta ink application step of applying a magenta ink containing water, a diketopyrrolopyrrole pigment, a quinacridone pigment and a resin,
A method for producing printed matter, wherein the drying step is performed at a conveying speed of 30 to 150 meters/minute and a temperature of 80 to 140°C .

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