JP7451874B2 - Recording method and recording device - Google Patents

Description

The present invention relates to a water-based ink composition, a recording method, and a recording device.

Inkjet recording methods are capable of recording high-definition images with relatively simple equipment, and are rapidly developing in various fields. Among these, various studies have been made regarding head maintenance methods and the like. For example, Patent Document 1 discloses a nozzle that discharges an ink composition containing a coloring material and polymer particles, and an aggregating liquid containing an aggregating agent capable of aggregating the components of the ink composition. Disclosed is a method for maintaining a recording apparatus including a recording head having a nozzle formation surface formed therein, in which the nozzle formation surface of the recording head is wiped using a cleaning liquid and an absorbing member.

Japanese Patent Application Publication No. 2017-105134

Ink ejected from an inkjet head and used for recording has a problem of poor ejection stability. Furthermore, a liquid-repellent film is formed on the nozzle surface of the inkjet head in order to prevent ink from sticking. It is known that this liquid-repellent film is easily damaged by nozzle cleaning. Even when a cleaning liquid is used as in Patent Document 1, in a recording method using an ink composition containing an inorganic pigment, there is a problem that the ink composition is more likely to stick and the liquid-repellent film is gradually damaged. There is.

The present inventors have made extensive studies to solve the above problems. As a result, the present invention was completed by discovering that the above problems can be solved by adjusting the surface tension of the ink composition and the surface tension of the organic solvent in the ink composition.

The water-based ink composition of the present invention contains an inorganic pigment, an organic solvent with a surface tension of 35 mN/m or less, and water, and the water-based ink composition has a surface tension of 20 mN/m or more. , and a wiping member for wiping the nozzle surface of the inkjet head, the inkjet head is used by being ejected onto a recording medium.

The aqueous ink composition is preferably used in a recording method that includes a step of attaching a treatment liquid containing an aggregating agent to a recording medium in an inkjet recording apparatus.

The water-based ink composition preferably has an organic solvent content of 2% by mass or more based on the total amount of the water-based ink composition.

In the aqueous ink composition, the organic solvent preferably contains either an alkanediol solvent or a glycol ether solvent.

In the aqueous ink composition, it is preferable that the standard boiling point of the solvent contained in the aqueous ink composition is 130° C. or less.

The water-based ink composition preferably has a water content of 70% by mass or less based on the total amount of the water-based ink composition.

The aqueous ink composition preferably contains a surfactant.

In the aqueous ink composition, the inorganic pigment is preferably carbon black or a white inorganic oxide.

In the aqueous ink composition, the inorganic pigment preferably has an average particle diameter of 20 to 400 μm.

In the water-based ink composition, the recording medium is preferably a low-absorption recording medium or a non-absorption recording medium.

In the water-based ink composition, the organic solvent composition contained in the water-based ink composition preferably has a surface tension of 20 to 50 mN/m.

Further, the ink set of the present invention is an ink set comprising a first water-based ink composition and a second water-based ink composition, wherein the first water-based ink composition is the above-mentioned water-based ink composition, and the first water-based ink composition is the above-mentioned water-based ink composition. The second aqueous ink composition contains an organic pigment, an organic solvent, and water, and has a surface tension of 20 mN/m or more, and the surface tension of the organic solvent composition contained in the first ink composition is , lower than the surface tension of the organic solvent composition contained in the second ink composition, in an inkjet recording apparatus including an inkjet head and a wiping member for wiping the nozzle surface of the inkjet head, with respect to the recording medium. It is used by being ejected from an inkjet head.

In the ink set, it is preferable that the first aqueous ink composition and the second aqueous ink composition each have a surface tension of 20 to 30 mN/m.

In the ink set, the second ink composition does not contain an organic solvent with a surface tension of 35 mN/m or less that is contained in the first ink composition, and contains an organic solvent with a surface tension of more than 35 mN/m; It is preferable that the first ink composition does not contain an organic solvent that has a surface tension of more than 35 mN/m and is contained in the second ink composition.

Furthermore, the recording method of the present invention is a recording method performed using an inkjet recording apparatus equipped with an inkjet head and a wiping member for wiping the nozzle surface of the inkjet head, and the recording method is a recording method in which a water-based ink composition is applied to a recording medium. The aqueous ink composition includes an ink adhesion step of ejecting and adhering from an inkjet head, and the aqueous ink composition is the aqueous ink composition described above.

Preferably, the recording method includes a step of applying a treatment liquid containing an aggregating agent to the recording medium.

The above recording method is such that an inkjet recording device is capable of recording on a low absorbency recording medium or a non-absorbing recording medium and recording on an absorbent recording medium using a water-based ink composition, It is preferable to perform recording by selecting either recording on an absorbent recording medium, a non-absorbent recording medium, or an absorbent recording medium.

Further, the recording apparatus of the present invention is a recording apparatus that performs the recording method described above, and includes an inkjet head that ejects an aqueous ink composition to adhere it to a recording medium, and a wiping member that wipes a nozzle surface of the inkjet head. has.

FIG. 1 is a perspective view showing a recording device that can be used in this embodiment. 2 is a schematic diagram showing a nozzle surface of an inkjet head included in the recording apparatus of FIG. 1. FIG. FIG. 2 is a schematic diagram showing the configuration of a wiping member included in the recording apparatus of FIG. 1. FIG.

Hereinafter, embodiments of the present invention (hereinafter referred to as "this embodiment") will be described in detail with reference to the drawings as necessary, but the present invention is not limited thereto, and the gist thereof Various modifications are possible without departing from the above. In addition, in the drawings, the same elements are given the same reference numerals, and overlapping explanations will be omitted. In addition, the positional relationships such as top, bottom, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the illustrated ratios.

1. Water-Based Ink Composition The water-based ink composition of the present embodiment is ejected from the inkjet head onto a recording medium in an inkjet recording apparatus including an inkjet head and a wiping member that wipes a nozzle surface of the inkjet head. The aqueous ink composition used includes an inorganic pigment, an organic solvent with a surface tension of 35 mN/m or less, and water, and has a surface tension of 20 mN/m or more.

Conventionally, cleaning in which the nozzle surface is wiped away using a wiping member has caused a problem in that the liquid-repellent film on the nozzle surface is peeled off. In particular, in recording methods using ink compositions containing inorganic pigments such as carbon black, the liquid-repellent film on the nozzle surface tends to peel off due to repeated cleaning.

On the other hand, in this embodiment, the inorganic pigment-containing ink composition is applied to the wiping member by adjusting the surface tension of the organic solvent contained in the ink composition containing the inorganic pigment and the surface tension of the ink composition itself. Improves the permeability of objects. This prevents the inorganic pigment remaining on the wiping member from rubbing against the liquid-repellent film during wiping. The physical properties and composition of the water-based ink composition of this embodiment will be explained in detail below.

1.1. Surface Tension The surface tension of the aqueous ink composition of this embodiment is 20 mN/m or more. It is preferably 20 to 40 mN/m, more preferably 20 to 30 mN/m, even more preferably 21 to 29 mN/m, particularly preferably 22 to 28 mN/m. When the surface tension of the aqueous ink composition is 20 mN/m or more, the ejection stability is excellent. A value of 40 mN/m or less is preferable because secondary color beading is suppressed. In this embodiment, the surface tension is a value measured by Wilhelmy method at a liquid temperature of 25° C. using a surface tension meter (manufactured by Kyowa Kaimen Kagaku Co., Ltd., surface tension meter CBVP-Z, etc.).

Although the surface tension of the aqueous ink composition is not limited, it can be adjusted, for example, by adjusting the type and content of the surfactant contained in the ink.

1.2. Composition The water-based ink composition of the present embodiment contains an inorganic pigment, an organic solvent, and water, and may contain a surfactant and fine resin particles as necessary. Further, the organic solvent includes a solvent having a surface tension of 35 mN/m or less.

1.2.1. Inorganic pigments Examples of inorganic pigments include, but are not particularly limited to, carbon blacks (C.I. pigment black 7) such as furnace black, lamp black, acetylene black, and channel black; white inorganic oxides such as iron oxide and titanium oxide. Can be mentioned. Among these, the inorganic pigments may be used alone or in combination of two or more.

The average particle diameter of the inorganic pigment is preferably 20 to 400 μm, more preferably 50 to 350 μm, and even more preferably 75 to 350 μm. When the average particle diameter of the inorganic pigment is within the above range, the liquid-repellent film is easily peeled off, making the present invention particularly useful.

The content of the inorganic pigment is preferably 3 to 15% by weight, more preferably 5 to 12% by weight, and still more preferably 7 to 10% by weight. When the content of the inorganic pigment is within the above range, color development tends to be further improved.

1.2.2. Organic Solvent The organic solvent includes an organic solvent having a surface tension of 35 mN/m or less. This further improves the durability of the liquid-repellent film. Furthermore, if necessary, an organic solvent having a surface tension exceeding 35 mN/m may be included.

The surface tension of the organic solvent composition contained in the aqueous ink composition (organic solvent composition surface tension) is preferably 20 to 50 mN/m, more preferably 25 to 45 mN/m, and still more preferably 30 to 45 mN/m. 40 mN/m, particularly preferably 30 to 35 mN/m. This tends to further improve the durability of the liquid-repellent film. The surface tension of an organic solvent composition is the average (weighted) surface tension of each organic solvent, weighted by the ratio of the mass of each organic solvent to the total mass of all organic solvents contained in the ink composition. average).

The method for calculating the weighted average of surface tension will be explained. Let S _All be the weighted average value of surface tension, S _N be the surface tension of each organic solvent, and X _N (mass ratio) be the content mass ratio of the organic solvents. N is a number starting from 1, depending on the type of organic solvent contained in the ink composition. For example, when three types of organic solvents are used, S ₁ , S ₂ and S ₃ are produced. The weighted average S _All of the surface tension is the sum of the products of the surface tension S _N and the mass ratio X _N of each organic solvent. Therefore, the following formula (2) holds true. The mass ratio X _N is the ratio of the mass of organic solvent N to the total mass of all organic solvents contained in the ink composition, and has a value of 0 to 1. The method for measuring surface tension is the same as described above.
S _All =ΣS _N ×X _N ...(2)

Note that the weighted average of the surface tension can be adjusted by the surface tension of the organic solvent used and the content ratio of the organic solvent used.
Note that when focusing on the color bleed of the ink composition, there was a relationship with the average surface tension of the organic solvent contained in the ink composition, so the average surface tension of the organic solvent contained in the ink composition was calculated.

The organic solvent is not particularly limited, but at least one of the organic solvents contained in the ink has a surface tension of 35 mN/m or less, and the weighted average of the surface tension of the organic solvent and the ratio of water and organic solvent described below It is preferable that the weighted average standard boiling point falls within a preferable range. 1,2-pentanediol, 1,2-hexanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1 , 7-heptanediol, and alkanediol solvents such as 1,8-octanediol and 3-methyl-1,3-butanediol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol Monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol mono-t-butyl ether, triethylene glycol monobutyl ether, 1-methyl-1-methoxybutanol, propylene Glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, propylene glycol monobutyl ether, and dipropylene glycol Glycol ether solvents such as monobutyl ether or diethers thereof; glycerin; glycol solvents such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and dipropylene glycol; and the like.

Among these, glycerin; alkanediol solvents such as 1,3-butanediol, propylene glycol, 3-methyl-1,3-butanediol, and 1,2-hexanediol; and glycol ether solvents such as diethylene glycol diethyl ether. It is preferable that the solvent contains either an alkanediol solvent or a glycol ether solvent. By including such a solvent, the durability of the liquid-repellent film tends to be further improved.

The surface tension of the organic solvent is preferably 20 to 65 mN/m, more preferably 20 to 40 mN/m, even more preferably 25 to 40 mN/m, particularly preferably 25 to 35 mN/m, and more preferably 25 to 30 mN/m. Particularly preferred.

Examples of alkanediol-based solvents include alkanediols or alkanediols condensed with intermolecular hydroxyl groups. The number of carbon atoms in the alkane is preferably 3 or more, more preferably 5 or more, even more preferably 6 or more, and preferably 10 or less. The number of intermolecular condensations is preferably 1 to 4.

Among these, alkanediols having 5 or more carbon atoms are preferred. Also preferred are 1,2-alkanediols. The above case is preferable since the wiping durability is better.

Examples of glycol ether solvents include ethers of alkanediols or alkanediols condensed with intermolecular hydroxyl groups. The number of carbon atoms in the alkane is preferably 2 or more, preferably 2 to 4. The number of intermolecular condensations is preferably 1 to 4. Examples of the glycol ether include monoethers and diethers, with diethers being preferred. The glycol ether is preferably an alkyl ether. In this case, the wiping durability is better and preferred.

The average standard boiling point (solvent composition boiling point) of the solvent contained in the aqueous ink composition is preferably 210°C or lower, more preferably 200°C or lower. The temperature is more preferably 125°C or lower, even more preferably 120°C or lower. When the average standard boiling point of the organic solvent is 210° C. or less, drying properties tend to be further improved. Further, the average standard boiling point of the solvent is not particularly limited, but is preferably 105°C or higher, more preferably 110°C or higher, and still more preferably 120°C or higher.

Note that the average standard boiling point of the solvent contained in a water-based ink composition is defined as the average standard boiling point of the solvent contained in the water-based ink composition, where the weight is the ratio of the content mass of water and each organic solvent to the total mass of water and all organic solvents contained in the ink composition. or the weighted average of the standard boiling points of each organic solvent. The average standard boiling point of the solvent contained in the water-based ink composition is also referred to as the standard boiling point of the solvent composition contained in the water-based ink composition.

The method for calculating the weighted average of standard boiling points is partially similar to the method for calculating the weighted average of surface tension described above, and is calculated as follows. Let H _All be the weighted average value of standard boiling points, H _N be the standard boiling points of water and each organic solvent, and Y _N (mass %) be the mass ratio of the water or organic solvent. N is a numerical value starting from 1, depending on the type of water or organic solvent contained in the ink composition. For example, when three types of water or organic solvents are used, H ₁ , H ₂ and H ₃ are produced. The weighted average surface tension H _All is the sum of the products of the surface tension H _N and the content Y _N of water or each organic solvent. Therefore, the following formula (3) holds true. The mass ratio Y _N is the ratio of the mass of water or organic solvent N to the total mass of water and organic solvent contained in the ink composition, and has a value of 0 to 1.
H _All =ΣH _N ×Y _N ...(3)

The weighted average of the standard boiling points can be adjusted by the standard boiling point of the organic solvent used and the content mass ratio of water and organic solvent used.

Note that when we focused on the drying properties of the ink composition, we found that it was affected by the water and organic solvent contained in the ink composition, so we calculated the average standard boiling point of the solvent including the water and organic solvent contained.

The normal boiling point of the organic solvent is preferably 160 to 300°C, more preferably 170 to 240°C, even more preferably 180 to 230°C.

The content of the organic solvent is preferably 2% by mass or more, more preferably 5 to 35% by mass, and even more preferably 10 to 30% by mass, based on the total amount of the ink composition.

The content of the organic solvent having a surface tension of 35 mN/m or less is preferably 0.5% by mass or more, more preferably 1% by mass or more, and more preferably 2% by mass based on the total amount of the ink composition. % or more, more preferably 3% by mass or more, particularly preferably 5% by mass or more. Although the upper limit is not limited, it is preferably 35% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less. In this case, wiping durability is better and preferred.

1.2.3. Water A water-based ink composition is an ink composition containing at least water as a main solvent component. The content of water in the ink composition is preferably 45% by mass or more.
Furthermore, the water content is preferably 50% by mass or more, more preferably 55% by mass or more, and still more preferably 65% by mass or more. When the water content is in the above range or more, the drying properties tend to be further improved.
On the other hand, the water content is preferably 95% by mass or less, further preferably 80% by mass or less, more preferably 75% by mass or less, even more preferably 70% by mass, based on the total amount of the ink composition. % or less, even more preferably 65% by mass or less, particularly preferably 60% by mass or less. In this case, cockling reduction is better and preferred.

1.2.4. Surfactant The surfactant is not particularly limited, but preferred examples include acetylene glycol surfactants, silicone surfactants, and fluorine surfactants. In particular, silicone surfactants and fluorine surfactants are preferred since the surface tension of the ink can be easily adjusted.

Examples of the acetylene glycol surfactant include, but are not limited to, 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 2,4,7,9-tetramethyl-5- selected from alkylene oxide adducts of decyne-4,7-diol and alkylene oxide adducts of 2,4-dimethyl-5-decyn-4-ol and 2,4-dimethyl-5-decyn-4-ol One or more types are preferred. Commercially available acetylene glycol surfactants include, but are not particularly limited to, E series such as Olfine 104 series and Olfine E1010 (trade name manufactured by Air Products Japan, Inc.), Surfynol 465, and E series such as Olfine E1010. Examples include Surfynol 61 (trade name manufactured by Nissin Chemical Industry CO., Ltd.). Acetylene glycol surfactants may be used alone or in combination of two or more.

Fluorosurfactants include, but are not particularly limited to, perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl phosphates, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl betaines, and perfluoroalkyl betaines. Examples include fluoroalkylamine oxide compounds. Commercially available fluorosurfactants include, but are not limited to, Megafac F-444 (product name manufactured by DIC), S-144, S-145 (manufactured by Asahi Glass Co., Ltd.); FC-170C, FC. -430, Florado-FC4430 (manufactured by Sumitomo 3M Ltd.); FSO, FSO-100, FSN, FSN-100, FS-300 (manufactured by Dupont Corporation); FT-250, 251 (manufactured by Neos Corporation), etc. . The fluorosurfactants may be used alone or in combination of two or more.

Examples of silicone surfactants include polysiloxane compounds, polyether-modified organosiloxanes, and the like. Commercially available silicone surfactants include, but are not particularly limited to, BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-347, BYK -348, BYK-349 (all product names manufactured by BYK Chemie Japan Co., Ltd.), KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640 , KF-642, KF-643, KF-6020, X-22-4515, KF-6011, KF-6012, KF-6015, KF-6017 (all trade names, manufactured by Shin-Etsu Chemical Co., Ltd.).

The content of the surfactant is preferably 0.1 to 3% by mass, more preferably 0.2 to 2% by mass, and even more preferably 0.5 to 1% by mass, based on the total amount of the treatment liquid. It is 5% by mass. When the content of the surfactant is within the above range, the wettability of the ink composition tends to be further improved. Further, it is preferable that the surface tension of the ink composition can be easily adjusted.

1.2.5. Resin Fine Particles Dispersion, suspension, emulsion, etc. can be used as resin fine particles. Such resin particles include, but are not particularly limited to, urethane resin particles and acrylic resin particles. As a result, the fixing properties of the ink are excellent, and the abrasion resistance of the recorded material tends to be further improved.

Commercially available urethane resin fine particles include, but are not limited to, SanCure 2710 (trade name, manufactured by The Lubrizol Corporation), Permarin UA-150 (trade name, manufactured by Sanyo Chemical Industries, Ltd.). ), Superflex 460, 470, 610, 700 (product names manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), NeoRez R-9660, R-9637, R -940 (all product names manufactured by Kusumoto Chemicals, Ltd.), Adeka Bontiter HUX-380, 290K (all product names manufactured by Adeka), Takelac (registered trademark) W-605, Examples include W-635, WS-6021 (trade names of Mitsui Chemicals, Inc.), and polyether (trade names of TAISEI FINECHEMICAL CO., LTD.).

Commercial products of acrylic resin fine particles include, but are not particularly limited to, Movinyl 966A (trade name, acrylic resin emulsion manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Joncryl 7100, Joncryl 390. , Jonkrill 711, Jonkrill 511, Jonkrill 7001, Jonkrill 632, Jonkrill 741, Jonkrill 450, Jonkrill 840, Jonkrill 74J, Jonkrill HRC-1645J, Jonkrill 734, Jonkrill 852, Jonkrill 7600 , Jonkrill 775, Jonkrill 537J, Jonkrill 1535, Jonkrill PDX-7630A, Jonkrill 352J, Jonkrill 352D, Jonkrill PDX-7145, Jonkrill 538J, Jonkrill 7640, Jonkrill 7641, Jonkrill 631, Jon Examples include Kryl 790, Jonkryl 780, Jonkryl 7610 (trade names, manufactured by BASF), and NK Binder R-5HN (trade name, manufactured by Shin Nakamura Chemical Co., Ltd., acrylic resin emulsion, solid content 44%).

The content of the resin fine particles is preferably 0.5 to 20% by mass, more preferably 3 to 20% by mass, and more preferably 5 to 15% by mass, based on the total amount of the ink composition. More preferably, it is 7 to 12% by mass.

2. Ink Set The ink set of this embodiment is used by being ejected from the ink jet head onto a recording medium in an ink jet recording apparatus that includes an ink jet head and a wiping member that wipes the nozzle surface of the ink jet head. be.

The ink set includes at least the above-described aqueous ink composition containing the inorganic pigment, an organic solvent having a surface tension of 35 mN/m or less, and water. The ink set may further include other ink compositions. Examples of other ink compositions include water-based ink compositions containing organic pigments and water.

The ink composition containing an organic pigment is preferably a color ink or the like. When the composition of the solvent was adjusted so that the ink containing organic pigment had the same average surface tension of the organic solvent composition as the water-based ink composition containing the above-mentioned inorganic pigment, on the contrary, the color ink did not have the same surface tension in the image. It was found that bleed occurred.

Therefore, in the present embodiment, an ink composition of an organic pigment-containing ink composition in which the surface tension of the organic solvent composition contained is high and an inorganic pigment-containing ink composition in which the surface tension of the contained organic solvent composition is low. When used as a set, it was possible to suppress bleeding.

For this purpose, for example, an organic solvent having a relatively high surface tension is used in color ink. The ink composition containing the organic pigment was excellent in suppressing damage to the liquid-repellent film even if it did not necessarily contain an organic solvent having a surface tension of 35 mN/m or less. In this way, an ink set was obtained that was excellent in suppressing bleeding and in suppressing damage to the liquid-repellent film.

The ink set of the present embodiment includes a first water-based ink composition and a second water-based ink composition, wherein the first water-based ink composition is the above water-based ink composition containing an inorganic pigment, and the second water-based ink composition includes a first water-based ink composition and a second water-based ink composition. A water-based ink in which the water-based ink composition contains an organic pigment, an organic solvent, and water, and the first water-based ink composition and the second water-based ink composition each have a surface tension of 20 mN/m or more. Compositions are preferred. Further, in the ink set of the present embodiment, the surface tension of the organic solvent composition contained in the first ink composition is preferably lower than the surface tension of the organic solvent composition contained in the second ink composition. .

The first aqueous ink composition and the second aqueous ink composition each preferably have a surface tension within the above range, preferably from 20 to 30 mN/m.

2.1. First Water-Based Ink Composition As the first water-based ink composition, the above water-based ink composition containing an inorganic pigment can be used. In particular, the aforementioned water-based ink composition containing an inorganic pigment can be used.

2.2. Second Water-Based Ink Composition Examples of the second water-based ink composition include those containing an organic pigment. The second aqueous ink composition does not need to contain an inorganic pigment or an organic solvent having a surface tension of 35 mN/m or less, unlike the first ink composition. It is preferable that the surface tension of the organic solvent composition contained in the second aqueous ink composition is higher than the surface tension of the organic solvent composition contained in the first ink composition. The second water-based ink composition can be configured in the same manner as the first water-based ink composition except for this. Hereinafter, the differences from the first ink composition will be explained.

2.2.1. Organic Pigments Examples of organic pigments include, but are not limited to, quinacridone pigments, quinacridonequinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, anthanthrone pigments, indanthrone pigments, and flavanthrone pigments. Pigments, perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments, azo pigments, etc. can be mentioned.

The content of the organic pigment is preferably 3 to 15% by mass, more preferably 5 to 12% by mass, and even more preferably 7 to 10% by mass, based on the total amount of the ink composition. When the content of the organic pigment is within the above range, color development tends to be further improved.

The organic pigment is preferably one that allows the ink to record chromatic colors, such as cyan, yellow, magenta, orange, and green, with cyan, yellow, and magenta being preferred.

2.2.2. Organic Solvent The surface tension of the organic solvent composition contained in the second ink composition is preferably higher than the surface tension of the organic solvent composition contained in the first ink composition. The difference between the surface tension of the organic solvent composition contained in the second ink composition and the surface tension of the organic solvent composition contained in the first ink composition (second ink composition - first ink composition) is , preferably 2 mN/m or more, more preferably 5 mN/m or more, and still more preferably 10 mN/m or more. Although the upper limit is not limited, it is preferably 30 mN/m or less, more preferably 20 mN/m or less, even more preferably 15 mN/m or less, particularly preferably 12 mN/m or less.

Further, the surface tension of the organic solvent composition contained in the second ink composition is preferably 30 mN/m or more, more preferably 35 to 45 mN/m, and even more preferably 40 to 45 mN/m.

It is preferable that the second ink composition does not contain an organic solvent that is included in the first ink composition and has a surface tension of 35 mN/m or less. This tends to suppress bleeding. Further, the second ink composition contains an organic solvent having a surface tension of more than 35 mN/m, and the first ink composition contains an organic solvent having a surface tension of more than 35 mN/m contained in the second ink composition. It is preferable not to contain it. This makes it possible to suppress bleeding while suppressing damage to the liquid-repellent film.

The organic solvent contained in the second ink composition preferably has a surface tension of 20 to 65 mN/m, more preferably 35 to 65 mN/m, and even more preferably 35 to 40 mN/m.

The organic solvent contained in the second ink composition preferably has a normal boiling point of 160 to 300°C, more preferably 170 to 240°C, even more preferably 180 to 230°C.

Examples of the organic solvent contained in the second ink composition include those mentioned above, such as alkanediol solvents, polyol solvents, and glycol ether solvents. Examples of the alkanediol solvent include those mentioned above, but preferred are alkane diols having 4 or less carbon atoms, or alkane diols in which hydroxyl groups are condensed between molecules. The polyol solvent is other than the alkanediol solvent, and is, for example, a solvent having 3 or more hydroxyl groups in the molecule.

3. Recording Apparatus The recording apparatus of this embodiment includes an inkjet head that discharges the water-based ink composition, and a wiping member that wipes the nozzle surface of the inkjet head. FIG. 1 shows a perspective view of a recording device that can be used in this embodiment, FIG. 2 shows a schematic diagram of a nozzle surface of an inkjet head included in the recording device, and FIG. 3 shows the configuration of a wiping member included in the recording device. A schematic representation is shown. Printing devices are of the line type, which prints by one scan on the recording field plate using a line head with a length longer than the recording width of the print medium, the main scan type, in which an inkjet head scans the print medium, and the main type. It is possible to use either a serial type in which recording is performed by performing sub-scanning in a sub-scanning direction intersecting the scanning direction a plurality of times. FIG. 1 shows an example of a serial type recording device.

As shown in FIG. 1, the recording device 20 includes a transport section 220 and a recording section 230. The conveyance unit 220 conveys the recording medium F fed to the recording apparatus to the recording unit 230, and discharges the recording medium after recording to the outside of the recording apparatus. Specifically, the conveyance unit 220 has respective feed rollers, and conveys the fed recording medium F in the sub-scanning direction T1.

The recording unit 230 also includes an inkjet head 231 that discharges a composition onto the recording medium F sent from the conveyance unit 220, a carriage 234 on which the inkjet head 231 is mounted, and an inkjet head 234 that moves the carriage 234 in the main scanning direction S1 of the recording medium F. A carriage moving mechanism 235 for moving the carriage to S2 is provided.

As shown in FIG. 2, the inkjet head 231 has a nozzle surface 22a in which a plurality of nozzles 24 for ejecting the ink composition are opened. The plurality of nozzles 24 form a nozzle row 25 by lining up along the conveyance direction Y. Note that in this embodiment, a plurality (five) of nozzle rows 25 provided corresponding to the types of ink compositions are arranged in parallel at regular intervals in the scanning direction X.

When the inkjet head 231 is placed at the home position, the cap 27 moves relatively toward the inkjet head 231 and contacts the nozzle surface 22a, thereby performing capping to form a closed space in which the nozzle 24 opens. When the power is turned off, the inkjet head 231 is placed at the home position and capped, thereby suppressing clogging of the nozzle 24 due to dryness.

Furthermore, as a maintenance operation for the inkjet head 231, flushing can be performed in which the ink composition is ejected (thrown away) from the inkjet head 231 toward the cap 27 when the cap 27 is located away from the inkjet head 231. .

Further, by driving the suction mechanism 28 in the capped state, suction cleaning is performed to discharge foreign matter such as air bubbles from the inkjet head 231 through the nozzle 24 together with the ink composition. Note that after suction cleaning is performed, droplets discharged from the nozzle 24 may adhere to the nozzle surface 22a, so it is preferable to wipe the nozzle surface 22a by wiping.

Further, when printing is performed by jetting the ink composition toward the recording medium F from the inkjet head 231, a part of the ink composition jetted toward the recording medium F is atomized, becomes a mist, and reaches the nozzle surface. 22a and the recording medium F may float. Such mist may be carried by air currents generated by the reciprocating movement of the carriage 234 or the jetting of the ink composition, and may adhere to the nozzle surface 22a of the inkjet head 231. Note that part of the ejected ink composition becomes atomized and floats as mist because a reaction force such as air resistance is applied to the ink composition ejected toward the recording medium F in a direction opposite to the ejection direction. This is because it acts on

Then, when the ink composition adheres to the nozzle surface 22a and forms droplets, the droplets come into contact with the droplets ejected from the nozzle 24, and the flying direction of the ejected droplets changes. , printing quality may deteriorate. Therefore, when the ink composition adheres to the nozzle surface 22a due to printing operation, suction cleaning, etc., wiping is performed by the wiper unit 30, which is a wiping member, to remove the ink composition adhered to the nozzle surface 22a.

Further, when wiping is performed, the meniscus (concavely curved liquid surface) formed within the nozzle 24 may be disturbed, so it is preferable to perform flushing after performing wiping to adjust the meniscus within the nozzle 24.

A liquid-repellent film is provided on the nozzle surface 22a. The liquid-repellent film is not particularly limited as long as it has liquid-repellent properties; for example, it can be formed by forming a molecular film of a metal alkoxide having liquid-repellent properties, and then performing drying treatment, annealing treatment, etc. can do.

The metal alkoxide molecular film may be of any type as long as it has liquid repellency, but a metal alkoxide monomolecular film having a long chain polymer group containing fluorine (long chain RF group) or a liquid repellent group ( For example, a monomolecular film of a metal salt having a long chain polymer group containing fluorine is desirable. The metal alkoxide is not particularly limited, but silicon, titanium, aluminum, and zirconium are generally used as the metal species, for example. Examples of long-chain RF groups include, but are not limited to, perfluoroalkyl chains and perfluoropolyether chains. Examples of the alkoxysilane having a long-chain RF group include silane coupling agents having a long-chain RF group.

The liquid-repellent film is not particularly limited, and for example, an SCA (silane coupling agent) film or a film described in Japanese Patent No. 4424954 can be used. Note that among the liquid-repellent films, those having particularly water-repellent properties are referred to as water-repellent films.

Next, the configuration of the wiper unit 30, which is a wiping member, will be described in detail. As shown in FIG. 3, the wiper unit 30 includes a holding part 37 that holds a wiping member 40 made of an elongated ink composition absorbing member capable of wiping the nozzle surface 22a, and a holding part 37 that holds a wiping member 40 that is made of an elongated ink composition absorbing member that can wipe the nozzle surface 22a. and a moving mechanism 38 for moving.

The wiping member 40 is made of, for example, a nonwoven fabric made of synthetic resin, and when the wiping member 40 comes into contact with the nozzle surface 22a to which the ink composition has adhered, the ink composition adhering to the nozzle surface 22a is removed from the fibers constituting the wiping member 40. It is absorbed into the gaps (voids) between the fibers. Note that the wiping member 40 may be a woven fabric made of synthetic fibers, a woven fabric made of natural fibers, or a nonwoven fabric, as long as it can absorb the ink composition.

The moving mechanism 38 includes a rail portion 33 extending in the transport direction Y, a drive motor 34, and a power transmission mechanism 35 that transmits the power of the drive motor 34. The holding portion 37 is moved along the wiping direction (the direction indicated by the white arrow in FIG. 3) by the driving force. In this embodiment, the wiping direction is the moving direction of the holding part 37, and is the opposite direction to the conveyance direction Y.

The holding part 37 has a longitudinal direction in the transport direction Y, and includes a wiper holder 31 and a wiper cassette 41 that is detachably attached to the wiper holder 31. The wiper holder 31 engages with a rail portion 33 via a guide portion 32 fixed to a lower portion thereof.

A rack and pinion mechanism 36 is provided on the side wall of the wiper holder 31. The rack and pinion mechanism 36 includes a rack 36a fixed to the side surface of the wiper holder 31 and extending in the wiping direction, and a pinion 36b that meshes with the rack 36a and rotates with power transmitted via the power transmission mechanism 35. have.

When the drive motor 34 is driven in the first direction, the driving force is transmitted to the rack 36a via the power transmission mechanism 35 and the pinion 36b, so that the holding part 37 moves in the wiping direction together with the rack 36a. . Further, when the drive motor 34 is driven in a second direction opposite to the first direction, the driving force is transmitted to the rack 36a via the power transmission mechanism 35 and the pinion 36b, so that it is held together with the rack 36a. The section 37 moves in the transport direction Y.

The wiper cassette 41 rotatably holds a take-up roller 43, a pressure roller 44, and a delivery roller 42 arranged in order at a distance in the wiping direction, and also has a support shaft 44a that pivotally supports the pressure roller 44. Holds the biasing member 45 that biases. The biasing member 45 can be configured by, for example, a coil spring or a plate spring that is a compression spring, an elastic body that can be elastically deformed, or the like. Further, if the pressure roller 44 has an elastically deformable peripheral surface and can bias the support shaft 44a by the pressure roller 44, the biasing member 45 may not be provided.

The wiping member 40 is set between the pay-out roller 42 and the take-up roller 43, with the starting end in the longitudinal direction being wound around the take-up roller 43 and the end end in the longitudinal direction being wound around the pay-out roller 42. The wiping part 40a is urged toward the outside of the wiper cassette 41 by a pressure roller 44.

When the wiper cassette 41 is attached to the wiper holder 31, the wiping part 40a of the wiping member 40 is biased toward the nozzle surface 22a, and the wiper cassette 41 and the wiper holder 31 have openings (not shown) provided in the wiper cassette 41 and the wiper holder 31. It protrudes from the holding part 37 through the part.

When the holding section 37 moves in the wiping direction with the inkjet head 231 stopped at a position corresponding to the wiper unit 30 in the scanning direction X, the wiping section 40a absorbs the ink composition attached to the nozzle surface 22a. Wiping is performed by wiping the nozzle surface 22a. In this manner, in the movement region of the inkjet head 231 extending in the scanning direction X, a position where the inkjet head 231 can come into contact with the wiping member 40 is referred to as a wiping position.

When the wiping part 40a absorbs the ink composition, the wiping member 40 is removed from the winding roller 43 by performing a winding operation in which the winding roller 43 rotates in the winding direction (clockwise in FIG. 3). Wind it up. As a result, the wiping part 40a moves in the wiping direction, and at the same time, the wiping member 40 corresponding to the wound length is unwound from the feeding roller 42, so that the used portion that has absorbed the ink composition is transferred to the winding roller 43. The unused portion becomes a new wiping portion 40a.

Note that the wiper cassette 41 is configured such that when the take-up roller 43 takes up the wiping member 40, the pay-out roller 42 is allowed to rotate in the pay-out direction (clockwise in FIG. 3); It is preferable to provide a ratchet 46 that restricts rotation in the direction. This is because sagging of the wiping member 40 between the take-up roller 43 and the delivery roller 42 can be suppressed.

The recording device is a recording device capable of recording on a low-absorption recording medium or a non-absorbent recording medium, which will be described later, and recording on an absorbent recording medium. It is also possible to use a recording apparatus that performs recording by selecting whether to perform recording on an absorbent recording medium or to perform recording on an absorbent recording medium. Furthermore, a recording apparatus may be used that performs such recording using the aqueous ink composition or ink set described above. The above selection may be made, for example, by inputting selection information into the recording device or by setting the recording medium to be selected in the recording device.

The ink composition of the present embodiment described above often contains a predetermined amount of organic solvent by adjusting the surface tension of the organic solvent composition contained in the ink to a preferable value. In that case, the water content of the ink composition tends to be below a predetermined value. In this case, even when recording on an absorbent recording medium, cockling reduction is excellent and preferred.

A recording method using the above-mentioned recording device includes a step of depositing a processing liquid onto a recording medium in order to aggregate the ink composition and obtain excellent image quality. A recording method in which a reaction is performed is preferred. In such a recording method, the reaction liquid adhering to the nozzle surface 22a reacts with the ink composition, and a giant aggregate containing pigment is generated on the nozzle surface. In this case, if the wiping member sweeps the nozzle surface with the aggregates involved, there is a problem in that the peeling of the liquid-repellent film becomes particularly noticeable. Therefore, the present invention is particularly useful in a recording method in which a treatment liquid containing an aggregating agent is attached to a recording medium.

3.1 Processing liquid adhesion mechanism The recording device may include a processing liquid adhesion mechanism. The processing liquid adhesion mechanism is a mechanism that performs a process of adhering a processing liquid containing a flocculant to a recording medium. The adhesion mechanism is not particularly limited, and for example, a roller, spray, inkjet head, etc. can be used. Among these, it is preferable to adhere to the recording medium by an inkjet method using an inkjet head. This is preferable because the coating can be applied selectively only to the necessary areas, which tends to reduce printing costs and shorten drying time.

The treatment liquid contains a flocculant as a component (flocculant component) that thickens or insolubilizes the ink composition, and may also contain other components such as a solvent and a surfactant, if necessary. The treatment liquid can be similar in type and content to the above-mentioned components other than the coloring material that may be included in the ink composition, except that it contains a coagulant. It can be made independent. The content of the coloring material in the treatment liquid is preferably 0.1% by mass or less, more preferably 0.05% by mass or less, and may be 0% by mass.

Examples of the flocculant include, but are not limited to, polyvalent metal salts, organic acids, and cationic resins. The interaction of the flocculant with the ink composition causes the ink composition to thicken or become insolubilized. This makes it possible to improve image quality.

Specific examples of processing liquids that thicken or insolubilize the ink composition include processing liquids that interact with the ink composition to precipitate or insolubilize the coloring material in the ink composition; Examples include processing liquids that generate semi-solid substances (gels) containing As a method for causing interaction between the ink composition and the processing liquid, there is a method in which an anionic coloring material in the ink composition and a cationic compound in the processing liquid interact, and a method in which an ink composition having a different pH from each other is used. A method in which the pH of the ink composition is changed by mixing the ink composition with a treatment liquid to break the dispersion of the pigment in the ink composition and cause the pigment to aggregate. Examples include a method of causing dispersion destruction of the pigment in the composition and causing the pigment to aggregate.

The content of the flocculant is preferably 1 to 15 parts by weight, more preferably 2 to 10 parts by weight, and still more preferably 3 to 7 parts by weight, based on the total amount of the treatment liquid. When the content of the aggregating agent is within the above range, the resulting image quality tends to be better.

The polyvalent metal salt is not particularly limited, but for example, a polyvalent metal salt of an inorganic acid or a polyvalent metal salt of an organic acid is preferable. Such polyvalent metal salts are not particularly limited, but include, for example, alkaline earth metals in Group 2 of the periodic table (e.g., magnesium, calcium), transition metals in Group 3 of the periodic table (e.g., lanthanum). , earth metals from group 13 of the periodic table (eg aluminium), lanthanides (eg neodymium). Preferred salts of these polyvalent metals include carboxylates (formic acid, acetic acid, benzoate, etc.), sulfates, nitrates, chlorides, and thiocyanates. Among these, preferred are calcium salts or magnesium salts of carboxylic acids (such as formic acid, acetic acid, benzoate, etc.), calcium salts or magnesium salts of sulfuric acid, calcium salts or magnesium salts of nitric acid, calcium chloride, magnesium chloride, and thiocyanic acid. Mention may be made of calcium salts or magnesium salts. Note that the polyvalent metal salts may be used alone or in combination of two or more.

Examples of organic acids include, but are not limited to, phosphoric acid, oxalic acid, malonic acid, citric acid, acetic acid, propionic acid, and the like. Among these, monovalent or divalent or more carboxylic acids are preferred. Including such a carboxylic acid tends to improve image quality. In addition, one type of organic acid may be used alone or two or more types may be used in combination.

The cationic resin is not particularly limited, but for example, cationic amine resins, polyurethane resins, polyethyleneimine resins, and the like are preferred in terms of excellent image quality. Examples of the amine resin include polyallylamine resin, polyamine resin, and polyamide resin. Polyallylamine resin, polyamine resin, and polyamide resin are resins each having a polyallylamine structure, a polyamine structure, and a polyamide structure in the main skeleton of the polymer. The cationic resin is a resin particle or a water-soluble resin, preferably a water-soluble resin. Cationic resin particles are treated as a flocculant.

The weight average molecular weight of these cationic polymers is preferably 5,000 or more, more preferably about 5,000 to 100,000. The weight average molecular weight of the cationic polymer is measured by gel permeation chromatography using polystyrene as a standard substance.

The recording medium is not particularly limited, but includes, for example, an absorbent recording medium, a low absorbency recording medium, and a non-absorbent recording medium. Among these, low absorbency recording media and non-absorbent recording media are preferred, and non-absorbent recording media are more preferred. Treatment liquids are often used for non-absorbent recording media, and the present invention is particularly useful therein.

Here, "low absorbency recording medium" and "non-absorbent recording medium" refer to a recording medium in which the amount of water absorbed within 30 msec from the start of contact is 10 mL/m ² or less in the Bristow method. This Bristow method is the most popular method for measuring the amount of liquid absorbed in a short time, and is also adopted by the Japan Paper and Pulp Technology Association (JAPAN TAPPI). Details of the test method can be found in the standard No. of "JAPAN TAPPI Paper and Pulp Test Method 2000 Edition". 51 "Paper and Paperboard - Liquid Absorption Test Methods - Bristow Method".

Furthermore, non-absorbent or low-absorbent recording media can also be classified according to the wettability of the recording surface to water. For example, a 0.5 μL water droplet is dropped on the recording surface of the recording medium, and the contact angle reduction rate (comparison of the contact angle at 0.5 milliseconds and the contact angle at 5 seconds after impact) is measured. can be characterized. More specifically, as a property of the recording medium, non-absorbency refers to the above-mentioned reduction rate of less than 1%, and low absorption refers to the above-mentioned reduction rate of 1% or more and less than 5%. Absorbency refers to the above reduction rate of 5% or more. Note that the contact angle can be measured using a portable contact angle meter PCA-1 (manufactured by Kyowa Interface Science Co., Ltd.).

Examples of absorbent recording media include, but are not limited to, plain paper such as electrophotographic paper that has high permeability to the ink composition, inkjet paper (with an ink absorbing layer composed of silica particles or alumina particles, or polyvinyl alcohol). (PVA) and polyvinylpyrrolidone (PVP), which are special inkjet papers with an ink absorbing layer made of hydrophilic polymers such as polyvinylpyrrolidone (PVA) and polyvinylpyrrolidone (PVP). Examples include coated paper and cast paper.

The low-absorbency recording medium is not particularly limited, but includes, for example, coated paper provided with a coating layer on the surface for receiving oil-based ink. Coated paper is not particularly limited, but includes, for example, printing papers such as art paper, coated paper, and matte paper.

Non-absorbent recording media are not particularly limited, but include, for example, plastic films without an ink absorption layer, those in which plastic is coated on a base material such as paper, or those in which a plastic film is adhered. can be mentioned. Examples of the plastic here include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, and the like.

4. Recording Method The recording method of the present embodiment is a recording method using the aqueous ink composition described above and the recording device described above, and includes an ink adhesion step of discharging the aqueous ink composition from an inkjet head and adhering it to the recording medium. have Further, as described in the above recording apparatus, the recording method of this embodiment may include a wiping step of wiping the nozzle surface of the inkjet head. A treatment liquid adhesion step may also be included.

Hereinafter, the present invention will be explained in more detail using Examples and Comparative Examples. The present invention is not limited in any way by the following examples.

1. Ink Composition and Treatment Liquid Each material was mixed in the composition shown in Tables 1 to 4 below and thoroughly stirred to obtain each ink composition and treatment liquid. Specifically, each ink and processing liquid were prepared by uniformly mixing each material and removing insoluble matter with a filter. In Tables 1 to 4 below, the units of numerical values are mass %, and the total is 100.0 mass %. The pigment is prepared by mixing a pigment dispersant, which is a water-soluble styrene acrylic resin, with water at a mass ratio of 3:1 (pigment:pigment dispersant) in advance, and stirring the mixture in a bead mill. An ink composition was obtained using this. The values for pigments in the table are the total values for pigments and pigment dispersants.

The surface tension of the ink composition was measured by the method described above. The surface tension of the organic solvent composition contained in the ink composition and the standard boiling point of the solvent composition contained in the ink composition were calculated.

The main materials for the ink composition and treatment liquid used in the Examples and Comparative Examples below are as follows.
[Pigment]
Carbon black C. I. pigment blue 15:3
C. I. pigment red 122
C. I. pigment yellow 74
[Resin particles]
Joncryl 537J (acrylic resin particles, manufactured by BASF Japan)
〔Organic solvent〕
Glycerin 1,3-butanediol Propylene glycol 3-methyl-1,3-butanediol 1,2-hexanediol Diethylene glycol diethyl ether [surfactant]
BYK-306 (manufactured by Big Chemie Japan)
Megafac F-444 (manufactured by DIC, fluorine-based surfactant)

2. Recording Test A modified Seiko Epson SC-P9050V machine was prepared. The modified machine includes a platen heater that can heat the recording medium at a position facing the 300 npi inkjet head during recording, an inkjet head with a liquid-repellent film formed on the nozzle surface 22a as shown in FIG. 2, and an inkjet head shown in FIG. The wiping mechanism is equipped with a cloth wiper as shown in the figure below.

The nozzle surface was made of single crystal silicon. On the nozzle forming surface, a silicon oxide film (SiO ₂ film) was formed by a CVD method by introducing SiCl ₄ and water vapor into a chemical vapor deposition (CVD) reactor. The thickness of the SiO ₂ film was 50 nm.

The liquid-repellent film (with a thickness of 10 nm) is formed by performing oxygen plasma treatment on the nozzle surface, and then performing chemical vapor deposition (CVD) using C ₈ F ₁₇ C ₂ H ₄ SiCl ₃ . ) to form a nozzle surface with a liquid-repellent film.

The surface temperature of the recording medium during recording was adjusted to 35° C. using a platen heater. Further, each ink composition and treatment liquid was filled into each nozzle row 25 in FIG. 2 one by one to enable ejection. Note that the ink resolution of the test pattern was 600 x 600 dpi.

The treatment liquid and ink composition were ejected from the inkjet head of the modified machine and deposited on OK Top Coat (manufactured by Oji Paper), which was a recording medium. Thereafter, secondary heating was performed at 90° C. for 1 minute. In the example using the treatment liquid, the amount of the treatment liquid attached was 25% by mass relative to the amount of ink attached. Further, the treatment liquid and the ink composition were ejected simultaneously.

3. Evaluation method 3.1. Color Bleed In the above recording test, a test pattern in which a black ink pattern and a color pattern were printed in contact with each other was visually observed. Note that the ink adhesion amounts for the black ink pattern and the color pattern were each 10 mg/inch ² . Further, the amount of adhesion of each of the three inks in the color pattern was made equal. The evaluation criteria for color bleed are shown below.
(Evaluation criteria)
S: The image is very clear with no blurring at the border between black and color. A: The image is clear and almost no blurring at the border between black and color. B: There is some blurring at the border between black and color. C: There is significant blurring at the boundary between black and color, and the image is not clear.

3.2. Cockling In the above recording test, double-sided high-quality plain paper A4 (manufactured by Seiko Epson) was used as the recording medium instead of OK Top Coat (manufactured by Oji Paper). The test pattern was a mixed color pattern of black, cyan, magenta, and yellow inks. Further, the total amount of ink deposited was 10 mg/inch ² , and the deposit amount of each ink was made equal. The test pattern was recorded on the entire recordable area of plain paper. The evaluation criteria for cock rings are shown below.
(Evaluation criteria)
S: There are no curls or waves in the print. A: There are some waves in the print, but almost no curls. B: There are wavy wrinkles throughout the print, and curls are seen at the edges. C: The printed matter curls and becomes round. Furthermore, wavy wrinkles appear all over the body.

3.3. Wiping Durability In the recording test described above, wiping of 5 cm with a cloth wiper was performed once every minute of recording, and recording and wiping were repeated. The evaluation criteria for wiping durability are shown below. In cases where landing deviation occurred, peeling of the liquid-repellent layer was observed, and it is assumed that peeling was the cause.
(Evaluation criteria)
S: After wiping 4000 times, the landing deviation is within ±30 μm. A: After wiping 2000 times, the landing deviation is within ±30 μm. After wiping 3000 times, the landing deviation is ±30 μm or more. B: After wiping 1000 times, the landing deviation is within ±30 μm. Within ±30μm, and after wiping 2000 times, the landing deviation is ±30μm or more C: After wiping 1000 times, the landing deviation is ±30μm or more

3.4. Beading of Secondary Colors A mixed color pattern of black, cyan, magenta, and yellow inks was used as a test pattern when performing the above recording test. Further, the total amount of ink deposited was 10 mg/inch ² , and the deposit amount of each ink was made equal. The evaluation criteria for secondary color beading are shown below.
(Evaluation criteria)
S: Very clear image with no color unevenness in the secondary color area A: Clear image with almost no color unevenness in the secondary color area B: Image with some color unevenness in the secondary color area The clarity of the image is slightly inferior. C: There is significant color unevenness in the secondary color area and the image is not clear.

3.5. Drying property In the above recording test, a pattern was formed for each ink with a total adhesion amount of 10 mg/inch ² , and instead of performing secondary heating at 90° C. for 1 minute, drying was performed at 40° C. for 1 minute. Thereafter, the ink-applied surface of the recorded material was brought into contact with plain paper to check whether the ink composition was transferred to the surface of the plain paper. How to show the evaluation criteria for dryness.
(Evaluation criteria)
S: No transfer is observed A: Transfer area is 5% or less B: Transfer area is over 5% and 10% or less C: Transfer area is over 10%

3.6. Ejection Stability In the above recording test, printing was continuously performed on 200 recording media. Afterwards, we checked for discharge bends and non-discharge nozzles. The evaluation results of discharge stability are shown below.
(Evaluation criteria)
S: No ejection disturbance or non-discharge is observed. A: Ejection disturbance or non-discharge occurs in 5 nozzles or less. B: Discharge disturbance or non-discharge occurs in 10 nozzles or less. C: Discharge disturbance or non-discharge occurs in 11 or more nozzles. be

4. Evaluation Results Table 6 shows the evaluation results for each example. From Table 6, all examples in which the water-based ink composition contains an inorganic pigment, an organic solvent with a surface tension of 35 mN/m or less, and water, and the surface tension of the water-based ink composition is 20 mN/m or more, have excellent wiping durability and ejection. Stability was also excellent.

On the other hand, all of the other comparative examples were inferior in wiping durability or ejection stability. Write down the details.

From Examples 1, 4, and 7, the wiping durability was better when the ink containing the inorganic pigment contained an organic solvent having a lower surface tension.

From Examples 1, 6, and 11, the wiping durability was better when the ink containing the inorganic pigment contained more of the organic solvent with low surface tension.

From Examples 1, 3, and 8, the lower the surface tension of the ink in the ink set, the better the reduction of secondary color beading.

From Examples 1, 9, 10, 12, etc., ink containing inorganic pigments has better color bleed than ink containing organic pigments when the surface tension of the organic solvent composition contained in the ink is lower. The larger the value, the better.

From Examples 6 and 7, it was found that less water contained in the ink was better in reducing cockling. It has been found that the ink of this embodiment can perform recording with excellent cockling reduction even when recording on an absorbent recording medium in addition to recording on a non-absorbing or low-absorbing recording medium.

In Comparative Example 1, the surface tension of the ink composition was too low and the ejection stability was poor.
Comparative Examples 2 and 3 did not contain an organic solvent with a surface tension of 35 mN/m or less and had poor wiping durability.

In Reference Examples 1 and 2, no treatment liquid was used, and there was a tendency for beading and color bleeding of secondary colors to decrease. Note that in Reference Example 2, the wiping durability was not inferior even though the ink did not contain an organic solvent with a surface tension of 35 mN/m or less.

20... Recording device, 22a... Nozzle surface, 24... Nozzle, 25... Liquid temperature, 25... Nozzle row, 27... Cap, 28... Suction mechanism, 30... Wiper unit, 31... Wiper holder, 32... Guide portion, 33 ...Rail part, 34... Drive motor, 35... Power transmission mechanism, 36... Rack and pinion mechanism, 36a... Rack, 36b... Pinion, 37... Holding part, 38... Moving mechanism, 40... Wiping member, 40a... Wiping Part, 41... Wiper cassette, 42... Feeding roller, 43... Winding roller, 44... Pressing roller, 44... Solid content, 44a... Support shaft, 45... Biasing member, 46... Ratchet, 220... Conveying section, 230... Recording unit, 231... Inkjet head, 234... Carriage, 235... Carriage movement mechanism

Claims (15)

A recording device that records on a recording medium,
a first aqueous ink composition, a second aqueous ink composition, and a treatment liquid containing an aggregating agent;
an inkjet head that ejects the first water-based ink composition and the second water-based ink composition to adhere to a recording medium;
a processing liquid adhesion mechanism for adhering the processing liquid to a recording medium;
a wiping member that wipes a nozzle surface of the inkjet head,
a step of adhering the treatment liquid to the recording medium by the treatment liquid attachment mechanism; and an ink adhesion step of ejecting the first aqueous ink composition and the second aqueous ink composition from the inkjet head and adhering them to the recording medium. and a recording method in which the recording medium is a low-absorption recording medium or a non-absorption recording medium ,
The first water-based ink composition contains an inorganic pigment, an organic solvent with a surface tension of 35 mN/m or less, and water, and the water-based ink composition has a surface tension of 20 mN/m or more,
The second aqueous ink composition contains an organic pigment, an organic solvent, and water, and has a surface tension of 20 mN/m or more,
the surface tension of the organic solvent composition contained in the first water-based ink composition is lower than the surface tension of the organic solvent composition contained in the second water-based ink composition;
The second aqueous ink composition has a surface tension of more than 35 mN/m and contains an organic solvent that the first aqueous ink composition does not contain;
The first water-based ink composition is either an alkanediol-based solvent or a glycol ether-based solvent, has a standard boiling point of 160 to 240°C, has a surface tension of 35 mN/m or less , and has a surface tension of 35 mN/m or less. Contains an organic solvent that the ink composition does not contain,
The wiping member is capable of absorbing the ink composition.
Recording device. The flocculant is any one of a polyvalent metal salt, an organic acid, and a cationic resin.
The recording device according to claim 1. The content of the organic solvent having a surface tension of 35 mN/m or less is 2% by mass or more based on the total amount of the first aqueous ink composition.
The recording device according to claim 1 or 2. The organic solvent having a surface tension of 35 mN/m or less contained in the first aqueous ink composition is an alkanediol solvent.
The recording device according to any one of claims 1 to 3. The first aqueous ink composition has a solvent composition that has a standard boiling point of 130°C or less;
The recording device according to any one of claims 1 to 4. The water content is 70% by mass or less based on the total amount of the first aqueous ink composition.
The recording device according to any one of claims 1 to 5. The first aqueous ink composition includes a surfactant.
The recording device according to any one of claims 1 to 6. the inorganic pigment is carbon black or a white inorganic oxide,
The recording device according to any one of claims 1 to 7. The organic pigment is one of cyan, yellow, magenta, orange, and green.
The recording device according to any one of claims 1 to 8. The recording medium is a low-absorption recording medium that is coated paper , or a non-absorption recording medium,
The non-absorbent recording medium is a plastic film, or a base material coated with plastic or a plastic film adhered to the base material.
The recording device according to any one of claims 1 to 9. The organic solvent composition contained in the first aqueous ink composition has a surface tension of 20 to 50 mN/m.
The recording device according to any one of claims 1 to 10. The first water-based ink composition and the second water-based ink composition each have a surface tension of 20 to 30 mN/m.
The recording device according to any one of claims 1 to 11. The inkjet recording device uses the first water-based ink composition and the second water-based ink composition to record on a low-absorbency recording medium or a non-absorptive recording medium, and to record on an absorbent recording medium, is possible, and recording is performed by selecting either recording on the low absorbency recording medium or non-absorbent recording medium or recording on the absorbent recording medium.
The recording device according to any one of claims 1 to 12. The wiping member is made of nonwoven fabric.
The recording device according to any one of claims 1 to 13. A recording method performed using the recording device according to any one of claims 1 to 14,
adhering the processing liquid to the recording medium by the processing liquid adhesion mechanism;
an ink adhering step of ejecting the first aqueous ink composition and the second aqueous ink composition from the inkjet head and adhering them to the recording medium ,
The recording medium is a low-absorption recording medium or a non-absorption recording medium,
Recording method.