JP7428043B2 - Recording method and recording device - Google Patents

Description

The present invention relates to 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 image quality, ejection stability, and the like. For example, Patent Document 1 discloses that when a plurality of inks are overlapped and recorded on a non-absorbent or low-absorbent recording medium, the purpose of preventing bleeding or clogging between the inks is to discloses an ink set in which a reaction liquid, a first ink, and a second ink are applied in layers in this order.

Japanese Patent Application Publication No. 2015-71738

When recording using an aqueous ink composition containing water as the main solvent, an organic solvent is included in the ink in hopes of providing a moisturizing effect in order to prevent clogging of the inkjet head due to drying of the aqueous ink composition. There are cases. However, when recording is performed using a water-based ink containing an organic solvent, there are problems in that the drying properties of the ink are poor, resulting in poor image quality, and the position of landing tends to be misaligned.

The present invention is a recording method for recording on a recording medium, which includes an ink adhesion step in which an aqueous ink composition is ejected from an inkjet head to adhere to the recording medium, and an ink adhesion step in which an aqueous ink composition is applied with air by a blower mechanism to adhere to the recording medium. a primary drying step of drying the aqueous ink composition that has been applied to the recording medium; and a secondary drying step of drying the aqueous ink composition adhered to the recording medium by heating with a second heating mechanism after the primary drying step; The water-based ink composition contains a coloring material and water, does not contain an organic solvent in an amount exceeding 15.0% by mass based on the total amount of the water-based ink composition, and is dried with air in the primary drying step. This is a recording method in which the wind speed is 1.6 to 7.9 m/sec.

The present invention also provides a recording apparatus that performs recording by a recording method, which includes an inkjet head that ejects an aqueous ink composition to adhere it to a recording medium, and an inkjet head that blows air onto the aqueous ink composition that has adhered to the recording medium. The water-based ink composition includes a drying air blowing mechanism and a secondary heating mechanism that heats and dries the water-based ink composition attached to the recording medium, and the water-based ink composition contains a coloring material, water, and an organic solvent. , the recording device does not contain more than 15.0% by mass based on the total amount of the water-based ink composition, and the wind speed is 1.6 to 7.9 m/sec in the primary drying step. .

FIG. 1 is a side view illustrating an example of a recording device according to the present embodiment. FIG. 2 is a top view showing an example of the recording device of the present embodiment.

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. Recording Method The recording method of the present embodiment is a recording method for recording on a recording medium, which includes an ink adhesion step in which an aqueous ink composition is ejected from an inkjet head and adhered to the recording medium, and an ink deposition step in which a water-based ink composition is applied to the recording medium using an air blower mechanism. a primary drying step in which the aqueous ink composition adhering to the recording medium is dried, and a secondary drying step in which the aqueous ink composition adhering to the recording medium is heated by a second heating mechanism after the primary drying step to dry the aqueous ink composition adhering to the recording medium. a drying step, the water-based ink composition contains a coloring material and water, and does not contain an organic solvent in an amount exceeding 15.0% by mass based on the total amount of the water-based ink composition; In the primary drying step, the wind speed is 1.6 to 7.9 m/sec.

Water-based ink compositions containing water as a main solvent are attracting attention as ink compositions that emit less VOC (volatile organic compounds) and have a lower environmental impact. Such a water-based ink composition contains a relatively small amount of an organic solvent in order to suppress clogging due to drying and improve clogging recovery properties, with the expectation of a moisturizing effect. However, since organic solvents have a higher viscosity than water, the viscosity changes between a water-based ink composition in which water has not evaporated and a water-based ink composition in which water has evaporated. In this case, the viscosity of the aqueous ink composition varies depending on the degree of dryness of the ink, which causes differences in ejection characteristics such as ejection speed, resulting in a difference in the landing position between when the water has not evaporated and when the water has evaporated. A problem arises in that it tends to become large.

On the other hand, water-based ink compositions can be considered that can reduce the deviation in the landing position by reducing the content of the organic solvent. Such water-based ink compositions are less likely to change viscosity due to drying, and seem to solve the problem of landing errors. However, since such a water-based ink composition contains a large amount of water, it tends to dry easily, easily clog, and has a tendency for nozzles to recover easily.
When recording on a recording medium, a process is required to accelerate the drying of the ink adhered to the recording medium in order to quickly fix the aqueous ink composition adhered to the recording medium to prevent bleeding and obtain excellent image quality. be. For example, when a recording medium is heated to accelerate drying, the nozzles are indirectly affected by the heating, and as a result, the aqueous ink composition tends to dry and become clogged. Therefore, it is difficult to solve clogging by simply reducing the organic solvent content of the ink.

In particular, when recording on non-absorbent or low-absorbent recording media, it is impossible to prevent the ink from bleeding as the recording medium absorbs the solvent components of the ink. A process that accelerates the drying of the material is particularly necessary. Therefore, when a recording medium is heated, for example, in order to obtain excellent image quality, clogging tends to occur as a result, and more care must be taken in how to dry the ink.

On the other hand, in the present embodiment, the water-based ink composition adhered to the recording medium is dried by applying air to the recording medium while reducing the content of the organic solvent in the water-based ink composition. Thereby, it is possible to suppress a change in the viscosity of the water-based ink composition, and it is possible to eliminate the shift in the landing position of the water-based ink composition before and after drying. Furthermore, by drying the ink adhered to the recording medium by blowing air on it, the problem of nozzle clogging due to drying of the aqueous ink composition can be simultaneously suppressed. Excellent image quality can also be obtained by blowing air to accelerate the drying of the ink.
Furthermore, when drying is performed by heating the recording medium, water evaporated from the water-based ink composition may condense on the inkjet head, staining the head or causing damage to the water-based ink composition. By drying, the evaporated components are removed from around the inkjet head and dew condensation on the inkjet head can be reduced.

In particular, since conventional water-based ink compositions contain a considerable amount of organic solvent, the recording medium has to be heated to a considerable extent in order to dry the water-based ink composition from the viewpoint of improving image quality. However, reducing the organic solvent content of the water-based ink composition actually increases the drying speed of the water-based ink composition, so even primary drying by air blow drying does not sufficiently remove the water-based ink composition adhered to the recording medium. Can be dried. Each step will be explained in detail below.

1.1. Ink Adhesion Process The ink adhesion process is a process of ejecting a water-based ink composition from an inkjet head and making it adhere to a recording medium. Here, the inkjet head is a head that performs recording by ejecting a water-based ink composition toward a recording medium, and the head includes a cavity that ejects the contained water-based ink composition from a nozzle, and a cavity that ejects the water-based ink composition from a nozzle. The ink composition includes an ejection drive unit that applies ejection driving force to the head, and a nozzle that ejects the aqueous ink composition to the outside of the head. The ejection drive unit uses an electromechanical transducer such as a piezoelectric element that changes the volume of the cavity through mechanical deformation, and an electrothermal transducer that generates bubbles in the aqueous ink composition and ejects it by emitting heat. It can be formed by

Further, the inkjet head may be a line head or a serial head. In the line method using a line head, an inkjet head (also referred to as a "line head") having a length equal to or longer than the recording width of a recording medium is used. Then, in the ink adhesion step, while relatively moving the position of the line head and the recording medium in the scanning direction (vertical direction of the recording medium, transport direction F1) intersecting the width direction of the recording medium, the aqueous ink composition is applied. is ejected and adhered to the recording medium (see FIG. 1). Further, in a serial method using a serial head, main scanning is performed multiple times while the head is moved in a main scanning direction that intersects the sub-scanning direction of the recording medium to eject the aqueous ink composition and deposit it on the recording medium. Preferably, main scanning is performed on the same area two or more times. In this way, an image is recorded on the recording medium.

Among these, the recording method of this embodiment is preferably performed by a line method using a line head. This further improves printing speed.

In the ink adhesion step, the distance between the nozzle surface of the inkjet head and the surface of the recording medium is preferably 0.5 to 3.0 mm, more preferably 0.5 to 2.5 mm, and even more preferably 0. It is .5 to 1.8 mm. By setting the distance between the nozzle surface of the inkjet head and the surface of the recording medium to be 0.5 mm or more, it becomes easier for air to pass through the primary drying process, which will be described later, and the image quality of the resulting recorded material tends to be further improved. be. In addition, even when low-temperature heating is performed in the primary drying step described below, the nozzle is less likely to be warmed and clogging tends to occur less easily. In addition, when the distance between the nozzle surface of the inkjet head and the surface of the recording medium is 0.5 mm or more, dew condensation tends to be less likely to occur on the nozzle surface. Furthermore, when the distance between the nozzle surface of the inkjet head and the surface of the recording medium is 3.0 mm or less, the flight distance of the ink droplets becomes short, so that deviations in the landing positions tend to be further suppressed.

1.1.1. Water-based ink composition The water-based ink composition contains a coloring material and water, and does not contain an organic solvent in an amount exceeding 15.0% by mass based on the total amount of the water-based ink composition. It may also contain a resin, wax, antifoaming agent, and surfactant. Note that in this embodiment, "aqueous" refers to an ink composition containing water as one of the main solvent components. Preferably, the composition contains water in an amount of 40% by mass or more based on the total mass of the composition. Each component will be explained in detail below.

1.1.1.1. Coloring Material As the coloring material, at least one of pigments and dyes can be used. It is preferable to use a pigment as the coloring material because it can improve the light resistance of the water-based ink composition. As the pigment, any pigment that is commonly used in water-based ink compositions can be used without particular limitation.

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; inorganic pigments such as iron oxide and titanium oxide; quinacridone pigments; , quinacridonequinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, anthanthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, Examples include organic pigments such as quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments, magenta pigments, cyan pigments, and azo pigments. The pigments may be used alone or in combination of two or more.

The above pigments can be obtained as a pigment dispersion obtained by dispersing them in water using a dispersant, or by dispersing in water a self-dispersing type surface-treated pigment in which a hydrophilic group is introduced into the surface of pigment particles using a chemical reaction. It is preferably added to the aqueous ink composition as a pigment dispersion obtained by dispersing the pigment coated with the polymer in water.

The above-mentioned dispersants are not particularly limited, but include, for example, polymeric dispersants (glue, gelatin, casein, proteins such as albumin, natural gums such as gum arabic and gum tragacanth, glucosides of saponin, alginic acid and propylene glycol ester, alginic acid Triethanolamine, alginate fermented product of ammonium alginate, methylcellulose, carboxymethylcellulose, cellulose derivatives of ethyl hydroxycellulose, polyvinyl alcohols, polypyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymer, potassium acrylate-acrylonitrile copolymer Polymer, vinyl acetate-acrylic ester copolymer, acrylic resin of acrylic acid-acrylic ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid Ester copolymer, styrene-acrylic resin of styrene-m-methylstyrene-acrylic acid copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, vinylnaphthalene-acrylic acid copolymer, acetic acid Vinyl-ethylene copolymer, vinyl acetate-fatty acid vinyl ethylene copolymer, vinyl acetate-maleate ester copolymer, vinyl acetate-croton copolymer, vinyl acetate-based copolymer of vinyl acetate-acrylic acid copolymer and their salts) and surfactants (various anionic surfactants, nonionic surfactants, and amphoteric surfactants). The dispersants may be used alone or in combination of two or more.

Examples of the dye include, but are not limited to, acid dyes, direct dyes, reactive dyes, and basic dyes. More specifically, as the dye, for example, C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C. I. Acid Red 52, 80, 82, 249, 254, 289, C. I. Acid Blue 9,45,249, C. I. Acid Black 1, 2, 24, 94, C. I. Food black 1, 2, C. I. Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, 173, C. I. Direct Red 1, 4, 9, 80, 81, 225, 227, C. I. Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, C. I. Directed Black 19, 38, 51, 71, 154, 168, 171, 195, C. I. Reactive Red 14, 32, 55, 79, 249, C. I. Examples include Reactive Black 3, 4, and 35. The dyes may be used alone or in combination of two or more.

The content of the coloring material is preferably 10% by mass or less based on the total amount of the water-based ink composition. Further, it is preferably 0.5% by mass or more. The content is more preferably 1.0 to 7.5% by weight, and even more preferably 1.5 to 5.0% by weight. When the content of the coloring material is 10% by mass or less, clogging during drying tends to be less likely to occur. Further, when the content of the coloring material is 1.0% by mass or more, the optical density of the resulting recorded material tends to be further improved. Note that the content of the coloring material refers to the amount of solid content, and when the coloring material is mixed into the aqueous ink composition in the form of a colorant dispersion, it means the amount of solid content thereof.

1.1.1.2. Water The content of water is preferably 40% by mass or more, more preferably 50 to 99% by mass, based on the total amount of the water-based ink composition. Furthermore, it is preferably 75 to 95% by mass, more preferably 78 to 92% by mass, and even more preferably 82 to 90% by mass. When the water content is in the above range or more, the amount of VOC (volatile organic compounds) released tends to be smaller, and the drying properties of the water-based ink composition by air blowing tend to be further improved. In addition, the impact position shift is suppressed and the image quality is better. When the water content is below the above range, clogging recovery is better.

1.1.1.3. Organic Solvent The water-based ink composition of the present embodiment does not contain an organic solvent in an amount exceeding 15.0% by mass based on the total amount of the water-based ink composition. Here, "does not contain more than 15.0% by mass" means that water-based ink compositions that do not contain organic solvents are also included in the present embodiment, and specifically, they contain no organic solvents. This means that the content is 0 to 15% by mass. When we say that a composition does not contain more than XX% by weight of a certain component, we mean the same thing.

The content of the organic solvent is 0 to 15% by mass, preferably 0.5 to 15% by mass, and more preferably 1.0 to 12% by mass, based on the total amount of the aqueous ink composition. The content is more preferably 2.0 to 9.0% by weight, even more preferably 3.0 to 7.5% by weight, particularly preferably 4.0 to 5.0% by weight. By not containing an organic solvent, that is, by having a content of 0% by mass, displacement of the landing position of the aqueous ink composition before and after drying is suppressed. Further, when the content of the organic solvent is more than 0% by mass, drying of the aqueous ink composition is suppressed, and clogging becomes less likely to occur. Further, since the content of the organic solvent is 15% by mass or less, displacement of the landing position of the water-based ink composition before and after drying is suppressed. Furthermore, since the aqueous ink composition is easily dried in the primary drying step using the blower mechanism described later, the image quality of the resulting recorded material tends to be further improved.

Examples of organic solvents include, but are not limited to, 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, and 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 glycol monoethers such as dipropylene glycol monobutyl ether and tetraethylene glycol monobutyl ether; diethylene glycol dimethyl ether , diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol ethyl methyl ether, diethylene glycol butyl methyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, tripropylene glycol dimethyl ether, etc. ; Nitrogen-containing solvents such as 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone; Glycerin; Ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol , 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol and other glycols; methanol, ethanol , n-propyl alcohol, iso-propyl alcohol, n-butanol, 2-butanol, tert-butanol, iso-butanol, n-pentanol, 2-pentanol, 3-pentanol, and tert-pentanol. Examples include: Among these, preferred are glycols, polyols such as glycerin, glycol ethers, nitrogen-containing solvents, and the like. The organic solvents may be used alone or in combination of two or more.

Among the organic solvents, nitrogen-containing solvents, polyols, glycol ethers, alkanediols having 5 or more carbon atoms, and the like are preferred.
The alkanediol having 5 or more carbon atoms preferably has 5 to 10 carbon atoms, more preferably 6 to 8 carbon atoms. Alkanediols having 5 or more carbon atoms are not particularly limited, but include, for example, 1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2- Heptanediol, 2-ethyl-1,3-hexanediol, 2,2-dimethyl-1,3-propanediol, 2,2-dimethyl-1,3-hexanediol, 3-methyl-1,5-pentanediol etc. Among these, 1,2-alkanediol is preferred, and 1,2-pentanediol and 1,2-hexanediol are more preferred.

Glycol ethers are etherified condensates in which alkylene glycols or hydroxyl groups of alkylene glycols are condensed intermolecularly. In the case of condensates, the number of condensations is preferably 2 to 6, more preferably 2 to 4. In alkylene glycols and condensates thereof, alkylene may be linear or branched, and preferably has 1 to 7 carbon atoms, more preferably 2 to 5 carbon atoms. The glycol ether is preferably an alkyl ether. The number of carbon atoms in the alkyl group of the alkyl ether is preferably 1 to 5, more preferably 1 to 4. The glycol ether may be a glycol monoether or a glycol diether, with glycol monoethers being preferred.

Examples of the polyols include alkane polyols having 4 or less carbon atoms, or condensates in which hydroxyl groups of alkane polyols having 4 or less carbon atoms are condensed between molecules. The number of carbon atoms mentioned above is preferably 2 to 3. In the case of condensates, the number of condensations is preferably 2 to 4. The polyols have two or more hydroxyl groups in the molecule, preferably 2 to 4.

Examples of nitrogen-containing solvents include cyclic amides and acyclic amides. Examples of the cyclic amide include the above-mentioned pyrrolidones. Examples of the non-cyclic amide include N,N-dialkyl-alkylamides. Examples of the N,N-dialkyl-alkylamides include N,N-dialkyl-alkoxyalkylamides.
Particularly preferred are propylene glycol as the polyol, 1,2-hexanediol as the alkanediol having 5 or more carbon atoms, 2-pyrrolidone as the nitrogen-containing solvent, and triethylene glycol monobutyl ether as the glycol monoether.
The content of these organic solvents in the ink may be preferably within the above range.
By using such an organic solvent, there is a tendency to further suppress the shift in the landing position of the aqueous ink composition before and after drying, and the clogging of the nozzles.

The normal boiling point of the organic solvent is preferably 160 to 280°C, more preferably 180 to 260°C, even more preferably 200 to 240°C. When the standard boiling point of the organic solvent is 160° C. or higher, the shift in the landing position of the aqueous ink composition before and after drying is further suppressed, and the nozzle composition tends to be more likely to recover from clogging. Further, since the standard boiling point of the organic solvent is 280° C. or lower, the drying properties of the aqueous ink composition by air blowing are further improved, and thus the image quality of the resulting recorded material tends to be further improved.

The content of the organic solvent whose normal boiling point is within the above range may be within the above range based on the total amount of the aqueous ink composition. When the content of such an organic solvent is within the above range, it tends to prevent a shift in the landing position of the aqueous ink composition before and after drying and to prevent clogging of the nozzle.

Further, the content of the organic solvent whose standard boiling point is outside the above range is preferably 5.0% by mass or less, more preferably 2.0% by mass or less, based on the total amount of the aqueous ink composition. It is more preferably 1.0% by mass or less, even more preferably 0.5% by mass or less, particularly preferably 0.1% by mass or less, and the lower limit of the content may be 0% by mass. When the content of such an organic solvent is within the above range, it tends to prevent a shift in the landing position of the aqueous ink composition before and after drying and to prevent clogging of the nozzle.

1.1.1.4. Resin Examples of the resin include those dissolved in the aqueous ink composition or those dispersed in the form of resin particles, emulsions, and the like. By using such a resin, recorded matter with better moisture resistance tends to be obtained. In particular, it tends to contribute to improving the binding property (abrasion resistance) between the recording medium and the water-based ink coating film.

Examples of such resins include, but are not limited to, acrylic resins, vinyl acetate resins, vinyl chloride resins, butadiene resins, styrene resins, polyester resins, crosslinked acrylic resins, crosslinked styrene resins, benzoguanamine resins, phenolic resins, and silicone resins. , epoxy resins, urethane resins, paraffin resins, fluororesins, water-soluble resins, and copolymers that are combinations of monomers constituting these resins. Examples of the copolymer include, but are not limited to, styrene-butadiene resin and styrene-acrylic resin. Further, as the resin, a polymer latex containing these resins can be used. Examples include polymer latexes containing fine particles of acrylic resin, styrene acrylic resin, styrene resin, crosslinked acrylic resin, and crosslinked styrene resin. Note that the resins may be used alone or in combination of two or more. In particular, it is preferable that the resin particles contained in the aqueous ink composition of this embodiment contain at least one of an acrylic resin, a urethane resin, or a polyester resin.
The acrylic resin is a polymer obtained by polymerizing at least an acrylic monomer, and also includes a copolymer of an acrylic monomer and other monomers. Examples of acrylic monomers include (meth)acrylate and (meth)acrylic acid. Examples of other monomers include vinyl monomers, such as styrene.
Urethane resin is a resin obtained by urethane polymerization of a polyisocyanate compound and a polyol compound.

The content of the resin is preferably 0.5% by mass or more, preferably 1.0 to 10% by mass, and more preferably 2.0 to 8.0% by mass, based on the total amount of the water-based ink composition. It is mass %, more preferably 4.0 to 8.0 mass %. When the content of the resin is 1.0% by mass or more, as described above, the abrasion resistance tends to be further improved. Furthermore, when the content of the resin is 10% by mass or less, the viscosity of the water-based ink composition decreases, and the ink composition tends to have excellent ejection stability and excellent clogging recovery properties.

1.1.1.5. Wax Examples of the wax include those that dissolve in the aqueous ink composition or those that are dispersed in the form of an emulsion. By using such a wax, recorded matter tends to be obtained with better abrasion resistance.

Such waxes include, but are not particularly limited to, ester waxes of higher fatty acids and higher monohydric alcohols or dihydric alcohols (preferably monohydric alcohols), paraffin waxes, olefin waxes, or mixtures thereof. . Among these, olefin wax is preferred, and polyethylene wax is more preferred.

The content of wax is preferably 0.1 to 3.0% by mass, preferably 0.3 to 2.0% by mass, and preferably 0.3 to 2.0% by mass, based on the total amount of the aqueous ink composition. It is 1.0% by mass. As described above, when the wax content is 0.1% by mass or more, the abrasion resistance tends to be further improved. Furthermore, when the wax content is 3.0% by mass or less, the viscosity of the aqueous ink composition decreases, and the ink composition tends to have excellent ejection stability and excellent clogging recovery properties.

1.1.1.6. Antifoaming agent The antifoaming agent is not particularly limited, and examples thereof include silicone antifoaming agents, polyether antifoaming agents, fatty acid ester antifoaming agents, and acetylene glycol antifoaming agents. Commercial antifoaming agents include BYK-011, BYK-012, BYK-017, BYK-018, BYK-019, BYK-020, BYK-021, BYK-022, BYK-023, BYK-024, BYK -025, BYK-028, BYK-038, BYK-044, BYK-080A, BYK-094, BYK-1610, BYK-1615, BYK-1650, BYK-1730, BYK-1770 (the above product names, BYK Chemie Japan) (manufactured by Nissin Chemical Industry Co., Ltd.), Surfynol DF37, DF110D, DF58, DF75, DF220, MD-20, and Envirogem AD01 (all trade names, manufactured by Nissin Chemical Industry Co., Ltd.). The antifoaming agents may be used alone or in combination of two or more.

The content of the antifoaming agent is preferably 0.03 to 0.7% by mass, more preferably 0.05 to 0.5% by mass, and even more preferably It is 0.08 to 0.3% by mass.

1.1.1.7. Surfactant Surfactants include, but are not particularly limited to, acetylene glycol surfactants, fluorine surfactants, and silicone surfactants.

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 limited to, E series such as Olfine 104 series and Olfine E1010, Surfynol 465 and Surfynol 61 (all trade names are Nissin Chemical Co., Ltd.). Industry CO., Ltd. (trade name), etc. 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, S-144, S-145 (product names manufactured by Asahi Glass Co., Ltd.); FC-170C, FC-430, Florado-FC4430 (product names listed above); FT-250, 251 (all product names, manufactured by Neos Corporation), etc. can be mentioned. 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 silicone surfactants may be used alone or in combination of two or more.

The content of the surfactant is preferably 0.3 to 3.0% by mass, more preferably 0.5 to 2.0% by mass, and even more preferably It is 0.8 to 1.5% by mass.

1.1.1.8. Dynamic surface tension The dynamic surface tension of the aqueous ink composition at an average life of 10 ms measured by the maximum bubble pressure method is preferably 30 to 40 mN/m, more preferably 30 to 38 mN/m, and even more preferably 30 mN/m. ~36 mN/m. When the dynamic surface tension of the aqueous ink composition is within the above range, the shift in the landing position of the aqueous ink composition before and after drying tends to be more suppressed. The above dynamic surface tension can be measured using a bubble pressure dynamic surface tension meter by the maximum bubble pressure method within a surface life of 10 msec to 100 msec.

1.1.1.9. Static Surface Tension The static surface tension of the aqueous ink composition is preferably 20 to 28 mN/m, more preferably 22 to 28 mN/m, and even more preferably 24 to 28 mN/m. When the static surface tension of the water-based ink composition is within the above range, the shift in the landing position of the water-based ink composition before and after drying tends to be more suppressed. The static surface tension can be measured by the Wilhelmy method using an automatic surface tension meter. Specifically, the static surface tension can be obtained by measuring the force that attempts to draw the platinum plate into the ink when the platinum plate is wetted with ink in an environment of 25°C.

The ratio of the dynamic surface tension to the static surface tension is preferably 1.0 to 1.4, preferably 1.1 to 1.35, preferably 1.1 to 1.3. . When the ratio of the dynamic surface tension to the static surface tension is within the above range, the shift in the landing position of the aqueous ink composition before and after drying tends to be more suppressed.

1.1.1.10. Viscosity The viscosity of the aqueous ink composition at 20° C. is preferably 0.5 to 10.00 mPa·s, more preferably 1.0 to 5.0 mPa·s, and even more preferably 1.5 to 4.0 mPa·s. 5 mPa·s, more preferably 2.0 to 4.0 mPa·s. When the viscosity of the water-based ink composition is within the above range, the shift in the landing position of the water-based ink composition before and after drying tends to be more suppressed. Viscosity can be measured with a rheometer.

1.1.1.11. Recording Medium The recording medium targeted by the recording method of the present embodiment is not particularly limited, but includes, for example, an absorbent recording medium, a low absorbency recording medium, or a non-absorbent recording medium. Preferably, it is a low-absorption recording medium or a non-absorption recording medium.

Examples of the non-absorbent recording medium include, but are not limited to, sheets, films, textile products, etc. containing non-absorbable materials. Non-absorbent recording media also include a layer containing a non-absorbent material (hereinafter referred to as a "low-absorbent layer") on the surface of a base material (e.g., paper, fiber, leather, plastic, glass, ceramics, metal, etc.). ). Non-absorbent materials include, but are not particularly limited to, olefin resins, ester resins, urethane resins, acrylic resins, vinyl chloride resins, and the like.

Among these, as the non-absorptive recording medium, one having a recording surface containing vinyl chloride resin can be preferably used. Specific examples of vinyl chloride resins include polyvinyl chloride, vinyl chloride-ethylene copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl ether copolymer, vinyl chloride-vinylidene chloride copolymer, and vinyl chloride. -maleic acid ester copolymer, vinyl chloride-(meth)acrylic acid copolymer, vinyl chloride-(meth)acrylic acid ester copolymer, vinyl chloride-urethane copolymer, and the like. Note that there are no particular restrictions on the characteristics of the low-absorption recording medium, such as the thickness, shape, color, softening temperature, hardness, etc.

Examples of non-absorbent recording media include, but are not limited to, plastic films and plates such as polyvinyl chloride, polyethylene, polypropylene, and polyethylene terephthalate (PET), and metals such as iron, silver, copper, and aluminum. Examples include plates, metal plates manufactured by vapor deposition of these various metals, plastic films, plates made of alloys such as stainless steel and brass, and the like. In addition, as a non-absorbent recording medium, a water-based ink absorption layer made of silica particles or alumina particles, or a water-based ink absorption layer made of a hydrophilic polymer such as polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP) is used. It is preferable that no .

Absorbent recording media are not particularly limited, but include, for example, plain paper such as electrophotographic paper with high ink permeability, inkjet paper (with an ink absorbing layer composed of silica particles or alumina particles, or polyvinyl alcohol (PVA)). ) and inkjet paper with an ink absorbing layer made of a hydrophilic polymer such as polyvinylpyrrolidone (PVP). Alternatively, cloth may also be used.

Examples of the low-absorbency recording medium include art paper, coated paper, and cast paper used in general offset printing, which have relatively low ink permeability. These are made by providing a coating layer with relatively low ink permeability on a base material such as paper, and are also called coated paper. The coating layer is a layer made of a resin, an inorganic compound, etc. that has low water absorption, and is a layer that has low ink absorption.

1.2. First Drying Process The first drying process of this embodiment includes a process (air blowing process) of drying the aqueous ink composition adhered to the recording medium by applying wind using a blowing mechanism. In addition, in the first drying step, in addition to the above blower, a first heating mechanism may be used in combination.

1.2.1. Air blowing mechanism The air blowing mechanism is used to dry the water-based ink composition attached to the recording medium, and is used in place of the heating mechanism such as a platen heater that was previously installed facing the nozzle surface. It is. Therefore, the aqueous ink composition that the air blowing mechanism dries is the one that has just been applied to the recording medium, and at least the air blowing mechanism is configured to send air to the aqueous ink composition that has just been applied to the recording medium. The purpose of the primary drying process is to prevent the water-based ink composition from bleeding, etc., and is a drying process in which the solvent component of the water-based ink composition does not completely evaporate. When resin is included, the resin is not completely flattened during drying.

Such an air blowing mechanism may be one that accelerates the drying of the aqueous ink composition attached to the recording medium by blowing air onto the surface of the recording medium or flowing air over the surface of the recording medium. There is no particular restriction, and a blower fan provided in the recording device can be used. The blower mechanism is preferably installed from the viewpoint of drying the aqueous ink composition immediately after it has been deposited on the recording medium.
In the case of the line method, it is possible to blow air to the recording medium at a position immediately downstream of the inkjet head when viewed from the conveyance direction F1 of the recording medium, where air can be blown onto the recording medium without getting in the way of the inkjet head, etc. It is preferable to install a ventilation mechanism at the location.
In the case of the serial method, air can be blown onto the recording medium at a position where the inkjet head, carriage, etc. do not get in the way in the direction in which the inkjet head equipped with the carriage moves during main scanning. It is preferable to install a ventilation mechanism at the location.
In the case of the line method, for example, it is preferable to blow air at a position within 30 cm from the most downstream nozzle. Alternatively, it is preferable to start blowing air within one second after ink droplets from the most downstream nozzle land on the recording medium.
In the case of the serial method, it is preferable to blow air at a position where the inkjet head and carriage do not get in the way in the main scanning direction of the inkjet head. Alternatively, in the main scanning, it is preferable to start blowing air within one second after the ink droplets from the most downstream nozzle in the main scanning direction land.

Additionally, by using such an air blowing mechanism, drying of the aqueous ink composition in the nozzle can be suppressed, compared to a primary drying process that relies only on a heating process without performing an air blowing process, thereby reducing clogging. They tend to be more restrained. Further, as described above, if the aqueous ink composition has a relatively low content of organic solvent, it is possible to dry the aqueous ink composition on the recording medium by blow drying. Furthermore, with the blower mechanism, it is possible to suppress dew condensation on the inkjet head, contamination of the head, and damage caused by water, which are problems with the heating mechanism, because the evaporated components can be removed from the vicinity of the head.

The wind speed in the primary drying step is 1.6 to 7.9 m/sec, preferably 2.0 to 7.0 m/sec, and more preferably 2.2 to 6.0 m/sec. , more preferably 2.5 to 5.0 m/sec, particularly preferably 2.5 to 4.5 m/sec. When the wind speed in the primary drying step is 1.6 m/sec or more, drying of the water-based ink composition is further accelerated, and the image quality of the resulting recorded matter is further improved. Further, by setting the wind speed in the primary drying step to 7.9 m/sec or less, landing deviation due to the influence of the wind is further suppressed, and the image quality of the obtained recorded material is further improved.

In addition, as an example of the method for measuring the wind speed, as shown in FIG. 2, in the case of a line printer, wind speed is measured at five or more positions equally in the width direction F3 of the recording medium and the average value is determined. Thereby, even if there is variation in wind speed in the width direction of the recording medium, it is possible to evaluate the wind speed. Further, the wind speed can be measured at a position on the recording medium at the same height as the nozzle.

Further, in the case of a serial printer, the installation position of the air blowing mechanism can be within the same distance range as described above in the main scanning direction of the inkjet head. For example, the range can be set to a range where air is blown within one second after ink droplets from the most downstream nozzle land on the recording medium. In addition, in the case of a serial printer, since the inkjet head moves in the main scanning direction (the width direction of the recording medium), a blower mechanism can be installed next to the inkjet head in one direction in the main scanning direction or in the other direction. .

In the primary drying step, the temperature of the air is preferably 40°C or lower, more preferably 30°C or lower, and even more preferably 25°C or lower. On the other hand, the temperature is preferably 5°C or higher, more preferably 10°C or higher, and even more preferably 15°C or higher.
Furthermore, the temperature is more preferably 5 to 25°C, and even more preferably 10 to 20°C or lower. When the temperature of the air is within the above range, drying of the aqueous ink composition within the nozzle is further suppressed, and clogging tends to be further suppressed. When the wind temperature is within the above range, the image quality is better.

Further, the conveyance speed of the recording medium is preferably 10 m/min or more, more preferably 10 to 70 m/min, and even more preferably 10 to 40 m/min. When the conveyance speed of the recording medium is 10 m/min or more, that is, when the printing speed is relatively high, it is required to perform drying in a shorter time in the primary drying step in order to obtain an excellent image. This makes the present invention particularly useful. Further, by setting the conveyance speed of the recording medium to 70 m/min or less, drying time can be ensured, so that the image of the resulting recorded material tends to be further improved.

The wind speed is preferably 1.5 to 15.0 times, more preferably 1.5 to 10.0 times, even more preferably 1.5 to 5.0 times the conveyance speed of the recording medium. It is. When the ratio of the wind speed to the transport speed of the recording medium is within the above range, drying of the water-based ink composition can be accelerated, and the image quality of the resulting recorded matter tends to be further improved.

Note that in the primary drying step, the surface temperature of the recording medium in the portion facing the inkjet head is preferably 45° C. or lower, more preferably 40° C. or lower, still more preferably 38° C. or lower, and even more preferably is 35°C or lower, more preferably 30°C or lower, and even more preferably 28°C or lower. On the other hand, the temperature is preferably 15°C or higher, preferably 20°C or higher, more preferably 25°C or higher, still more preferably 30°C or higher, and even more preferably 35°C or higher.
Furthermore, the temperature is more preferably 15 to 40°C, and even more preferably 20 to 35°C. When the surface temperature of the recording medium is 45° C. or lower, drying of the aqueous ink composition in the nozzle is further suppressed, and clogging recovery tends to be further improved. It is preferable that the surface temperature of the recording medium is equal to or higher than the above range because the image quality is better.
The surface temperature of the recording medium in the primary drying process is a temperature that takes into account the heating in the first heating process when the primary drying process has a first heating process, and the surface temperature of the recording medium in the primary drying process is a temperature that takes into account the heating in the first heating process. If not, the temperature takes into account the air blowing process and environmental temperature.

Further, in the first drying step, in addition to the above-mentioned air blowing step, a heating step (first heating step) performed by a heating mechanism (first heating mechanism) may be used in combination, and the first heating mechanism The surface temperature may be adjusted. Examples of the first heating mechanism include a platen heater and the like.

When the primary drying process includes a heating process in addition to the blowing process, the image quality is better and preferable. Therefore, it is preferable that the number of heating steps is small, and it is preferable that the surface temperature of the recording medium in the primary drying step is relatively low, since this is more effective in suppressing landing position deviation and clogging recovery. It is also preferable that the primary drying step does not include a heating step.

Note that the first drying step may be performed at the same time as the ink adhesion step or before the ink adhesion step. Further, it may be carried out continuously from before the ink adhesion step or at the same time as the ink adhesion step to after the ink adhesion step.

1.3. 2nd drying process The 2nd drying process of this embodiment is a drying process performed after the 1st drying process. This is a step of further drying the aqueous ink composition adhered to the recording medium by heating with a heating mechanism (second heating mechanism). For example, the first drying step is a step for suppressing the aqueous ink composition attached to the recording medium from bleeding and deteriorating image quality, such as spreading more than necessary, and the second drying step It can also be called a process for further heating the aqueous ink composition fixed on the recording medium in the drying process to form an ink coating. It is affirmative that the recorded matter has been dried to the extent that it can be used.
The secondary heating process is performed after the ventilation in the primary heating process is finished. Furthermore, if the primary heating step includes a heating step, it is performed after the heating mechanism finishes applying heat to the recording medium.

In this way, by performing the first drying step and the second drying step separately, the first drying step performs drying to a degree that can suppress the drying of the nozzles of the inkjet head, and improves the image quality of the resulting recorded material. By sufficiently drying the aqueous ink composition in the second drying step, the abrasion resistance of the resulting recorded matter can be improved.
In the recording method of this embodiment, since the content of the organic solvent in the ink composition is 15% by mass or less, the ink can be easily dried, and the secondary drying process can easily dry the solvent component of the ink. This is preferable because the temperature and time required for the subsequent drying can be reduced. This is preferable in that thermal deformation of the recorded material can be reduced.

The second heating mechanism is not particularly limited, but includes, for example, a platen heater, a warm air heater, an IR heater, etc., which have a heating function.

Note that the surface temperature of the recording medium in the second drying step is preferably 60 to 100°C, preferably 65 to 90°C, and more preferably 70 to 85°C. When the surface temperature of the recording medium in the second drying step is within the above range, the image quality and abrasion resistance of the resulting recorded material tend to be further improved.
The second drying step is preferably started more than 1 second after the ink droplets are attached to the recording medium.

1.4. Treatment Liquid Adhesion Step The recording method of the present embodiment may further include a treatment liquid attachment step of applying a treatment liquid containing an aggregating agent to the recording medium. By including such a treatment liquid application step, the components of the aqueous ink composition tend to aggregate on the surface of the recording medium, and as a result, the image quality of the resulting recorded product tends to improve. As for the method of applying the treatment liquid, in addition to the method of applying it using the inkjet method as described above, it may also be applied using a bar coater, a roll coater, a spray, or the like. Note that, as the inkjet method, a method similar to the method for discharging the water-based ink composition described above can be exemplified.

The treatment liquid adhesion step may be performed before or after the ink adhesion step. Furthermore, when performing the treatment liquid adhesion step before the ink adhesion step, the ink adhesion step may be performed before the treatment liquid dries, or the ink adhesion step may be performed after the treatment liquid dries. Furthermore, when performing the treatment liquid application step after the ink deposition step, it is preferable to perform the treatment liquid application step before the aqueous ink composition dries. Among these, it is preferable to perform the treatment liquid adhesion process before the ink adhesion process.

The amount of treatment liquid deposited is preferably less than the maximum amount of ink deposited, preferably 50% by mass or less of the maximum deposited amount of ink, and more preferably 5 to 30% by mass.
By making the treatment liquid adhered in a smaller amount than the ink, it is also possible to increase the organic solvent content compared to the ink. Alternatively, the ink adhesion step may be performed after the treatment liquid is sufficiently dried.

1.3.1. Treatment liquid The treatment liquid is not particularly limited as long as it contains a coagulant that coagulates the components of the water-based ink composition, and may contain water, an organic solvent, an antifoaming agent, and a surfactant as necessary. Good too.

1.3.1.1. Coagulant The coagulant is not particularly limited as long as it coagulates the components of the aqueous ink composition, and examples thereof include polyvalent metal salts, organic acids or salts thereof, and cationic resins. The flocculants may be used alone or in combination of two or more.

The polyvalent metal salt is not particularly limited, but includes, for example, a polyvalent metal salt of an inorganic acid or a polyvalent metal salt of an organic acid. Examples of polyvalent metals include, but are not particularly limited to, typical metals in Group 2 of the periodic table (e.g., magnesium, calcium), transition metals in Group 3 of the periodic table (e.g., lanthanum), and metals in group 13 of the periodic table. Examples include typical metals from the genus (e.g. aluminum), lanthanides (e.g. 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 (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, acetic acid, phosphoric acid, oxalic acid, malonic acid, and citric acid. Among these, monovalent or divalent or more carboxylic acids are preferred. Further, the organic acid may be in the form of a salt. In addition, one type of organic acid or its salt may be used alone or two or more types may be used in combination. Organic acids or their salts that are also polyvalent metal salts are included in polyvalent metal salts.

Examples of the cationic resin include, but are not limited to, amine resins such as amine/epichlorohydrin condensation polymers, polyallylamine, and polyallylamine derivatives. The cationic resin is preferably a resin that is soluble in the processing liquid or one that is dispersed in the processing liquid in the form of a resin emulsion or the like, and the former is more preferable.

The content of the flocculant is preferably 1 to 10% by mass, more preferably 3 to 10% by mass, and still more preferably 3 to 7% by mass, based on the total amount of the treatment liquid. When the content of the aggregating agent is within the above range, not only the image quality of the obtained recorded material is further improved, but also the bleeding resistance and embedding property of the obtained recorded material tend to be further improved.

1.3.1.2. Water The content of water contained in the treatment liquid is preferably 65 to 90% by mass, more preferably 70 to 85% by mass, even more preferably 75 to 80% by mass, based on the total amount of the treatment solution. be. Aqueous treatment liquids are preferred.

1.3.1.3. Organic Solvent As the organic solvent contained in the treatment liquid, the same ones as those exemplified for the aqueous ink composition can be exemplified.

The content of the organic solvent is preferably 15% by mass or less, more preferably 1.0 to 10.0% by mass, and more preferably 1.0 to 8.0% by mass based on the total amount of the treatment liquid. It is mass %, more preferably 2.0 to 6.0 mass %. The content of the organic solvent in the above-mentioned ink may be in the same range.

1.3.1.4. Antifoaming Agent As the antifoaming agent contained in the treatment liquid, the same ones as those exemplified for the aqueous ink composition can be exemplified. The content of the antifoaming agent is preferably 0.03 to 0.7% by mass, more preferably 0.05 to 0.5% by mass, and even more preferably 0.05% by mass, based on the total amount of the treatment liquid. 08 to 0.3% by mass.

1.3.1.5. Surfactant As the surfactant contained in the treatment liquid, the same surfactants as those exemplified for the aqueous ink composition can be exemplified. The content of the surfactant is preferably 0.5 to 7.0% by mass, more preferably 0.7 to 5.0% by mass, and still more preferably 1.0% by mass, based on the total amount of the treatment liquid. It is 0 to 4.0% by mass. When the content of the surfactant is within the above range, the wettability of the treatment liquid tends to be further improved.

2. Recording Apparatus The recording apparatus of the present embodiment is a recording apparatus that performs recording by the above-described recording method, and includes an inkjet head that ejects the above-described aqueous ink composition to adhere it to a recording medium, and an inkjet head that ejects the above-described aqueous ink composition to adhere it to a recording medium, and A blowing mechanism that blows air onto the ink composition to dry it, and a heating mechanism that heats and dries the aqueous ink composition attached to the recording medium, and the wind speed of the blowing mechanism is 1.6 to 7. .9m/sec.

As an example of the printing apparatus of this embodiment, FIGS. 1 and 2 show a side view and a top view of a line type printing apparatus. As shown in FIG. 1, the recording apparatus 100 includes a recording medium conveying section 20, a recording section 30, a primary drying section 40, and a secondary drying section 50.

The conveyance unit 20 is provided so as to be able to convey the recording medium in the conveyance direction F1. Specifically, the conveyance unit 20 includes one or more feed rollers, and the feed rollers are driven alone or in conjunction with each other to convey the recording medium.

The recording unit 30 also includes an inkjet head 31 that discharges a water-based ink composition onto a recording medium, and an inkjet head 32 that discharges a treatment liquid. Further, a platen 60 that supports the recording medium F from the back side is provided at a position facing the recording section 30.

As shown in FIG. 2, a line printer, which is a line type recording device, includes a line head having a length equal to or longer than the recording width of a recording medium. The water-based ink composition is ejected from the line head toward the recording medium while the line head and the recording medium move relative to each other in a scanning direction that intersects the width direction. That is, a water-based ink composition is ejected from a line head toward a recording medium that is scanned relative to the line head. In a line printer, the head is (almost) fixed without moving, and printing is performed in one pass (single pass). Line printers have an advantage over serial printers in that they have faster recording speeds. The pass is also called scanning (main scanning).

Here, the above-mentioned "line head with a length corresponding to the recording width of the recording medium" does not mean that the width of the recording medium and the length (width) of the line head are completely the same, but are different from each other. You can leave it there. For example, the length (width) of the line head corresponds to the width (recording width) of the recording medium onto which the aqueous ink composition is to be ejected (an image is to be recorded). An example of this is when the length is

Furthermore, the first drying section 40 includes an air blowing mechanism 41 and, if necessary, a first heating means 42. The air blowing mechanism 41 is provided so as to be able to send air to the surface of the recording medium to which the aqueous ink composition is attached. FIG. 1 shows a blower mechanism 41 that sends air downstream of the recording unit 30 in a blowing direction F2. The position of the blower mechanism 41 is not limited to the position shown in the example of FIG. 1, and for example, the air sent from a blower mechanism located at another position may be blown to the recording medium through a blower route partitioned by a board or the like. Good too.
Further, in FIG. 1, the first heating means 42 is shown as a platen heater. Heat from the platen heater heats the recording medium via the platen.

Note that the first heating means 42 functions to promote drying of the water-based ink composition on the recording medium by the air blowing mechanism 41, and is not a device that attempts to dry the water-based ink composition by itself like a conventional platen heater. isn't it.

The second drying section 50 has a second heating means 51 that further dries the processing liquid adhering to the recording medium F and the aqueous ink composition adhering to the recording medium. In FIG. 1, the second heating means 51 is shown as a heater that heats the aqueous ink composition attached to the recording medium from the recording surface side, but the second heating means 51 is not limited to this, and may be a platen heater or a hot air heater. A heater, an IR heater, etc., or a combination of two or more of these can be used.

The thickness of the platen 60 is preferably 20 mm or less, preferably 15 mm or less, and more preferably 10 mm or less. Further, the thickness is preferably 1 mm or more, and preferably 5 mm or more. The thickness of the platen is the thickness of the member that constitutes the surface of the platen that supports the recording medium. The platen can be made of metal, resin, or the like.

The recording apparatus of this embodiment is not limited to the above-mentioned line type recording apparatus, but may be the above-mentioned serial type recording apparatus.

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. Preparation of water-based ink composition 1.1. Preparation of cyan dispersion St-Ac acid copolymer (copolymerized at a mass ratio of methacrylic acid/butyl acrylate/styrene/hydroxyethyl acrylate = 25/50/15/10. Weight average molecular weight 7000, acid value 150 mgKOH/ g) 40 parts by mass was added to a mixture of 7 parts by mass of potassium hydroxide and 53 parts by mass of water, and heated at 80°C with stirring to prepare an aqueous resin solution of the water-soluble resin. 20 parts by mass of a pigment (C.I. Pigment Blue 15:3), 10 parts by mass of an aqueous resin solution, and 70 parts by mass of ion-exchanged water were mixed and dispersed using a zirconia bead mill to obtain a pigment dispersion.

Each component was put into a mixture tank so as to have the composition shown in Table 1, mixed and stirred, and further filtered through a 5 μm membrane filter to obtain a water-based ink composition of each example. In addition, the numerical value of each component shown in each example in a table|surface represents mass % unless otherwise stated. Moreover, in the table, the numerical value of the pigment dispersion liquid represents the mass % of solid content.

The abbreviations and product components used in Table 1 are as follows.
〔Organic solvent〕
・Propylene glycol (boiling point 188℃)
・2-pyrrolidone (boiling point 245℃)
・1,2-hexanediol (boiling point 223°C)
・Triethylene glycol monobutyl ether (boiling point 278°C)
[Pigment dispersion]
・C. I. PigmentBlue15:3
〔resin〕
・Takelac W-6061 (urethane resin, Mitsui Chemicals, Inc.)
〔wax〕
・AQUACER539 (polyethylene wax, BIC Chemie Japan Co., Ltd.)
[Defoaming agent]
・Surfynol DF110D (acetylene diol surfactant, Nissin Chemical Industry Co., Ltd.)
[Surfactant]
・BYK348 (silicone surfactant, BYK Chemie Japan Co., Ltd.)

1.2. Surface tension measurement 1.2.1. Dynamic Surface Tension The dynamic surface tension at an average life of 10 ms in the maximum bubble pressure method was measured by the maximum bubble pressure method (bubble pressure method) using a bubble pressure dynamic surface tensimeter BP100 (trade name, manufactured by Cruz Co., Ltd.). At this time, the measurement was performed in the range of surface life from 10 msec to 100 msec.
1.2.2. Static Surface Tension Static surface tension was measured by the Wilhelmy method using an automatic surface tension meter CBVP-Z (trade name, manufactured by Kyowa Interface Science Co., Ltd.). Specifically, when a platinum plate was wetted with a water-based ink composition in an environment of 25° C., the force with which the platinum plate was drawn into the water-based ink composition was measured.

1.3. Viscosity Measurement The viscosity was measured using a rheometer MCR302 (trade name, manufactured by Anton Paar Japan) under the conditions of a shear rate of 200 s ⁻¹ in a temperature environment of 20° C.

2. Preparation of Treatment Liquid Each component was put into a mixture tank so as to have the composition shown in Table 2, mixed and stirred, and further filtered through a 5 μm membrane filter to obtain a treatment liquid for each example.

The abbreviations and product components used in Table 2 are as follows.
〔Organic solvent〕
・1,2-hexanediol [flocculant]
- Calcium acetate monohydrate - Malonic acid - Cation Master PD-7 (cationic resin, Yokkaichi Gosei Co., Ltd.)
[Defoaming agent]
・Surfynol DF110D (acetylene diol surfactant, Nissin Chemical Industry Co., Ltd.)
[Surfactant]
・BYK348 (silicone surfactant, BYK Chemie Japan Co., Ltd.)

3. Recording Device As the recording device, a modified L-6034VW (manufactured by Seiko Epson Corporation) that had been modified to a line system was used. Note that, as shown in FIG. 1, an air blowing mechanism was provided downstream of the first heating mechanism and the inkjet head, and a drying heater (second heating mechanism) was further installed downstream of the blowing mechanism. Note that the air blowing mechanism was installed in a range where air was blown within 1 second after the aqueous ink composition of the most downstream nozzle landed on the recording medium.

3.1. Wind Speed Measurement Wind speed and wind temperature were measured at a distance from the inkjet head of the recording device on the downstream side in the conveyance direction of the recording medium, where the wind from the fan is most likely to hit. In the measurement, measurements were taken at five positions equally in the width direction F3 of the recording medium, and the average value was taken.
3.2. Recording test Fill the above recording device with a water-based ink composition and processing liquid, and print a solid image on a recording medium (Pyren (registered trademark) film-OT (model number: P2111, thickness 20 μm, Toyobo Co., Ltd.)) did.
Note that the recording conditions for solid image quality were: resolution: 1200 x 1200 dpi, print pattern: solid image, and number of scans: 1 time. Furthermore, other conditions such as wind speed, wind temperature, surface temperature of the recording medium, and amount of ink etc. adhered were as shown in Tables 3 and 4. Note that the temperature in the primary drying step and the temperature in the secondary drying step were determined by measuring the temperature of the recording medium with a thermocouple. The environmental conditions for recording were a temperature of 25° C. and a humidity of 35%.

4. Evaluation method 4.1. Solid image quality The solid image obtained in the recording test was dried, and its image quality was visually confirmed, and the solid image quality was determined according to the following evaluation criteria.

(Evaluation judgment)
AA: No uneven bleed spots are observed in the image.
A: Some areas with uneven bleeding are observed in the image.
B: Areas with uneven bleed are observed in the image.
C: There are considerable areas of uneven bleeding in the image.

4.2. Shift in impact position Recording was performed under the conditions of the recording test described above. During recording, all nozzles ejected continuously for 10 seconds, and immediately after that, a nozzle check pattern was recorded. Further, during recording, there was a period of one minute during which no ink was ejected from all nozzles (idle running), and immediately after that, a nozzle check pattern was recorded.
The ink in the nozzles in the nozzles immediately after continuous ejection has not progressed to dryness, and the ink in the nozzles in the nozzles immediately after idle running has progressed in drying. The two check patterns were compared to confirm the difference in their landing positions. The average value of the landing position deviation of the check pattern of all the nozzles was determined, and this value was taken as the result of the landing position deviation of the water-based ink composition. However, if there was a nozzle pattern with no ejection, it was excluded from the calculation of the average value. Based on the obtained average value, the deviation of the landing position was determined according to the following evaluation criteria.
(Evaluation criteria)
A: There is no difference in the difference in the landing position.
B: There is a deviation in the landing position within the distance between the nozzles.
C: There is a deviation in the landing position exceeding the distance between nozzles.

4.3. Head condensation In the above recording test, printing was continued for 30 minutes. However, the environment during recording was 25° C. and 15% RH. The relatively low humidity created an environment where the water contained in the ink easily evaporated and condensation was likely to occur. Thereafter, the head was removed and the state of dew condensation on the nozzle surface was visually observed. In addition, the influence on solid images due to ejection failure of each nozzle was visually observed to confirm image defects due to ejection failure. Evaluation was made according to the following criteria.
(Evaluation criteria)
A: No dew condensation was observed and no image defects occurred.
B: Some dew condensation was observed, and slight image defects occurred due to ink ejection failure caused by the dew condensation.
C: Significant dew condensation was observed, and strong image defects occurred due to ink ejection failure caused by dew condensation.

4.4. Thermal deformation of printed matter The shape of the printed matter recorded in the above recording test was visually confirmed, and the thermal deformation of the printed matter was determined according to the following evaluation criteria.
(Evaluation criteria)
A: No deformation such as expansion or contraction can be observed in the printed matter.
B: Slight expansion and contraction etc. can be observed in the printed matter, but no effect on the printed matter is observed.
C: Significant expansion and contraction etc. can be confirmed in the printed matter, and the influence on the printed matter is recognized.

4.5. Recovery from nozzle clogging Recording was performed in the above recording test. However, the ink composition was intentionally caused to fail to eject from the nozzle, and a simulated recording was performed in a state where the nozzle failed to eject the ink composition. Non-discharge from the nozzle was caused by hitting the nozzle surface with a bemcotton moistened with water. Recording was performed in that state. A simulated recording was performed for 3 hours. After that, the nozzle was cleaned. Next, the nozzle was inspected to determine the recovery from clogging. Note that for cleaning the nozzles, 1 g of the water-based ink composition was discharged from the nozzle row.
(Evaluation criteria)
AA: No non-discharging nozzles.
A: Less than 3% of the total number of nozzles were found to be non-ejecting nozzles.
B: The number of non-ejecting nozzles was confirmed to be 3% or more and less than 5% of the total number of nozzles.
C: 5% or more of the total number of nozzles were found to be non-ejecting nozzles.

4. Evaluation Results Tables 3 and 4 show the configuration of the recording device, the water-based ink composition, the treatment liquid, each recording condition, and the evaluation results used in each example.
In all of the examples in which the content of the organic solvent is 15% by mass or less of the ink, and the blow drying process is performed at a wind speed of 1.6 to 7.9 m/s, it is possible to suppress the displacement of the landing position and improve the nozzle position. Both clogging recovery and image quality were excellent.
On the other hand, all of the other comparative examples were inferior in any of the following: suppression of landing position deviation, ability to recover from clogged nozzles, and image quality.
Furthermore, according to the present embodiment, it has been found that dew condensation on the head and thermal deformation of printed matter can be suppressed by not performing high-temperature heating in the primary drying step.

According to Examples 11 and 12, it can be seen that even by blowing air alone, the deviation of the landing position is suppressed, the recovery from nozzle clogging is excellent, and recorded matter of excellent image quality can be obtained. Since the organic solvent content of the ink is 15% by mass or less, the ink has good drying properties, and even by using only the air blowing process as the drying process, it is possible to suppress the misalignment of the landing position and recover from nozzle clogging. Both image quality and image quality were obtained.
From Examples 7 to 10 and 13, it was possible to obtain excellent image quality and improve clogging recovery even when the temperature of the heating step was relatively low.

According to Examples 19 to 24, it can be seen that by using the processing liquid, the image quality of the obtained recorded matter is further improved.

According to Comparative Examples 1 to 5 and 10, when the organic solvent content exceeds 15% by mass, the drying properties of the ink are poor and excellent image quality cannot be obtained with only the air blowing process. Excellent image quality could only be obtained by using a heating process at significantly higher temperatures. Furthermore, when the ink was dried using a heating process as in Comparative Examples 1, 4, and 5, the displacement of the landing position became large.

According to Comparative Examples 6 and 7, when the wind speed was too high, the landing position deviation increased and clogging worsened. It can be seen that if the wind speed is too slow, the image quality deteriorates and dew condensation also occurs.
According to Comparative Examples 8 and 9, even if the organic solvent content is within a predetermined range, if drying by air blowing is not used, image quality may deteriorate, clogging may occur, or dew condensation may occur. I understand.

DESCRIPTION OF SYMBOLS 100...Recording apparatus, 20...Transportation part, 30...Recording part, 31, 32...Inkjet head, 40...Primary drying part, 41...Air blowing mechanism, 42...First heating means, 50...Secondary drying part, 51... Second heating means

Claims (14)

A recording method for recording on a recording medium,
an ink adhesion step of ejecting a water-based ink composition from an inkjet head and adhering it to the recording medium;
a primary drying step comprising drying the aqueous ink composition adhered to the recording medium by applying air with an air blowing mechanism;
after the primary drying step, a secondary drying step of heating with a heating mechanism to dry the aqueous ink composition adhered to the recording medium;
The aqueous ink composition contains a coloring material, water, and an organic solvent, and does not contain more than 15.0% by mass of the organic solvent based on the total amount of the aqueous ink composition;
In the primary drying step, the wind speed is 1.6 to 7.9 m/sec,
The inkjet head is a line head having a length equal to or longer than the recording width of the recording medium,
Recording is performed on the conveyed recording medium using a line method in which scanning is performed once by the line head,
The conveyance speed of the recording medium is 10 m/min or more,
In the primary drying step, the surface temperature of the recording medium in the portion facing the inkjet head is 30° C. or less;
Recording method. The content of the organic solvent is 1.0 to 9.0% by mass based on the total amount of the aqueous ink composition.
The recording method according to claim 1. In the primary drying step, the surface temperature of the recording medium in the portion facing the inkjet head is 28 ° C. or less;
The recording method according to claim 1 or 2. In the primary drying step, the temperature of the air is 25°C or less,
The recording method according to any one of claims 1 to 3. The primary drying step does not include a heating step of heating with a heating mechanism to dry the aqueous ink composition attached to the recording medium.
The recording method according to any one of claims 1 to 4. In the primary drying step, the aqueous ink composition adhering to the recording medium is further heated by a first heating mechanism to dry the water-based ink composition.
The recording method according to any one of claims 1 to 4 . The conveyance speed of the recording medium is 10 to 70 m/min,
The recording method according to any one of claims 1 to 6 . The wind speed is 1.5 to 15.0 times the conveyance speed of the recording medium.
The recording method according to any one of claims 1 to 7 . a treatment liquid adhesion step of adhering a treatment liquid containing a flocculant to the recording medium;
The recording method according to any one of claims 1 to 8. The organic solvent contains at least one of polyols, glycol ethers, nitrogen-containing solvents, and alkanediols having 5 or more carbon atoms.
The recording method according to any one of claims 1 to 9. In the water-based ink adhesion step, the distance between the nozzle surface of the inkjet head and the surface of the recording medium is 0.5 to 3.0 mm.
The recording method according to any one of claims 1 to 10. In the secondary drying step, the surface temperature of the portion of the recording medium that is heated by the heating mechanism is 60 to 100°C.
The recording method according to any one of claims 1 to 11. The aqueous ink composition has a dynamic surface tension of 30 to 40 mN/m at an average life of 10 ms according to the maximum bubble pressure method,
The aqueous ink composition has a static surface tension of 20 to 28 mN/m.
The recording method according to any one of claims 1 to 12. A recording device that performs recording by the recording method according to any one of claims 1 to 13,
the inkjet head for ejecting a water-based ink composition to adhere it to the recording medium;
the blowing mechanism that blows air onto the aqueous ink composition attached to the recording medium to dry it;
the heating mechanism that heats and dries the aqueous ink composition attached to the recording medium;
The aqueous ink composition contains a coloring material, water, and an organic solvent, and does not contain more than 15.0% by mass of the organic solvent based on the total amount of the aqueous ink composition;
The wind speed of the wind by the blowing mechanism is 1.6 to 7.9 m/sec,
Recording device.