JP7452070B2 - Recording method and inkjet recording device - Google Patents

Description

The present invention relates to a recording method and an inkjet recording apparatus.

Various types of printing are performed on colored or transparent media in industrial and commercial applications. Media include flexible packaging, labels, signs, cardboard, etc., and images with excellent visibility are required.

For example, Patent Document 1 discloses an inkjet recording method in which white ink is deposited and then color ink is deposited on top of the white ink. This document states that this makes it possible to record a color image with high visibility by turning the white image into a background image.

Japanese Patent Application Publication No. 2010-158884

However, when recording on a non-white recording medium, for example, the visibility of the color ink image was insufficient. Furthermore, the filling of the color ink image was insufficient.

One aspect of the recording method according to the present invention is
A recording method for recording on a recording medium,
The recording medium is a non-white recording medium,
a white ink adhering step of adhering a white ink containing a white coloring material to the recording medium;
a non-white ink adhering step of adhering a non-white ink containing a non-white coloring material to the recording medium,
The white ink adhesion step and the non-white ink adhesion step are performed by scanning the recording head with respect to the recording medium,
The white ink adhesion step and the non-white ink adhesion step are performed on the same area of the recording medium in the same scan,
In the area to which the white ink and the non-white ink are deposited by the white ink deposition step and the non-white ink deposition step, the amount A of the white coloring material deposited and the amount of the non-white coloring material per unit area are determined. The mass ratio (A/B) of the adhesion amount B is 0.03 or more and 0.99 or less.

One aspect of the inkjet recording device according to the present invention is
a conveyance means for conveying the recording medium;
a recording head that ejects white ink containing a white coloring material and non-white ink containing a non-white coloring material to adhere to the recording medium;
scanning means for scanning the recording head with respect to the recording medium;
a control unit that controls the conveyance means, the recording head, and the scanning means;
has
The control section,
The white ink and the non-white ink,
deposited on the same area of the recording medium by the same scanning by the scanning means,
In the same area, the mass ratio (A/B) of the adhesion amount A of the white coloring material and the adhesion amount B of the non-white coloring material per unit area is 0.03 or more and 0.99 or less. attach it to.

FIG. 1 is a schematic diagram of an example of an inkjet recording apparatus that can be used in the recording method of the embodiment. 1 is a schematic diagram of the carriage and surrounding area of an example of an inkjet recording apparatus that can be used in the recording method of the embodiment. FIG. 1 is a block diagram of an example of an inkjet printing apparatus used in the printing method of the embodiment. FIG. 3 is a schematic diagram showing the configuration of a nozzle array of a print head according to an example.

Embodiments of the present invention will be described below. The embodiments described below illustrate examples of the invention. The present invention is not limited to the following embodiments, but also includes various modifications that may be implemented within the scope of the invention. Note that not all of the configurations described below are essential configurations of the present invention.

1. Recording Method The recording method according to this embodiment performs recording on a non-white recording medium. Furthermore, the recording method according to the present embodiment includes a white ink adhesion step of adhering white ink containing a white coloring material to a recording medium, and a non-white ink adhesion step of adhering a non-white ink containing a non-white coloring material to a recording medium. , is provided.

According to this embodiment, a recording method with excellent filling and visibility can be achieved. Furthermore, printing speed, density unevenness reduction, and image quality difference reduction can also be improved, which is preferable.

Note that "excellent filling" refers to an image recorded using a non-white ink that can sufficiently fill in the background with the ink, making the background difficult to see. Furthermore, the term "excellent visibility" means that an image recorded using a non-white ink has sufficient color development and is easy to confirm.

1.1. White Ink Adhesion Process The white ink adhesion process is a process of adhering white ink to the recording medium. The white ink will be explained below. The method of adhering to the recording medium will be described later.

The white ink and the non-white ink may be any ink except that they each contain a coloring material. Examples of the ink include ink containing an evaporable solvent component. In this case, recording is performed by drying and evaporating the solvent component from the ink attached to the recording medium, leaving components such as coloring material on the recording medium. Further, in this case, the ink of this embodiment is preferable because it has better color development and filling. Examples of such inks include water-based inks that contain at least water as a solvent component, and solvent-based inks that contain an organic solvent as a solvent component and have a water content of 2% by mass or less. In such an ink, the solvent component in the ink is preferably 10% by mass or more, and preferably 99% by mass or less. Alternatively, the ink may be a photocurable ink in which recording is performed by curing components contained in the ink by irradiation with light such as ultraviolet rays.

1.1.1. White coloring material White ink contains a white coloring material. Examples of the white coloring material include metal oxides, barium sulfate, and metal compounds such as calcium carbonate. Examples of metal oxides include titanium dioxide, zinc oxide, silica, alumina, and magnesium oxide. Further, particles having a hollow structure may be used for the white coloring material, and known particles can be used as the particles having a hollow structure. The material of the white coloring material is preferably different from the inorganic fine particles described below.

Among the examples listed above, it is preferable to use titanium dioxide as the white coloring material from the viewpoint of good whiteness and abrasion resistance. The white coloring materials may be used alone or in combination of two or more.

The volume-based average particle diameter (D50) (also referred to as "volume average particle diameter") of the white coloring material is set to be larger than the volume average particle diameter of inorganic fine particles described below. The volume average particle diameter of the white coloring material is preferably 30.0 nm or more and 600.0 nm or less, more preferably 100.0 nm or more and 500.0 nm or less, and still more preferably 150.0 nm or more and 400.0 nm or less. If the volume average particle diameter of the white coloring material is within the above range, the particles will be less likely to settle, the dispersion stability will be good, and nozzle clogging will be less likely to occur when applied to an inkjet recording device. can do. Further, if the volume average particle diameter of the white coloring material is within the above range, it can sufficiently contribute to improving the visibility of images.

The volume average particle diameter of the white coloring material can be measured using a particle size distribution measuring device. Examples of the particle size distribution measuring device include a particle size distribution analyzer using a dynamic light scattering method as the measurement principle (for example, "Nanotrack series" manufactured by Microtrack Bell Co., Ltd.). The volume average particle diameter is taken as the D50 value.

Note that in this specification, the word "white" when referring to white ink, white coloring material, etc. does not refer only to complete white, but includes colored in chromatic or achromatic colors as long as it can be visually recognized as white. Including shiny colors and shiny colors. It also includes inks and pigments that are labeled and sold with names that suggest that they are white inks or white pigments.

More quantitatively, "white" refers to not only a color in which a recorded matter has L ^* of 100, but also a color in which L ^* is 60 or more and 100 or less, and a ^* and b ^* are each ±10 or less. Color is also included.

More specifically, for example, when white ink is recorded in such an amount that the surface of a recording medium made of a transparent film is sufficiently covered with the ink, the brightness (L ^* ) and chromaticity (a ^* , b ^* ) preferably fall within the above ranges when measured using a CIELAB compliant spectrophotometer. A recorded matter recorded with a sufficient coating amount is, for example, 15 mg/inch ² . More preferably, 80≦L ^* ≦100, −4.5≦a ^* ≦2, and −10≦b ^* ≦2.5. An example of a transparent film recording medium is LAG Jet E-1000ZC (manufactured by Lintec Corporation). An example of a spectrophotometer compliant with CIELAB is Spectrolino (trade name, manufactured by GretagMacbeth), and the measurement conditions are a D50 light source, an observation field of 2°, a density of DIN NB, a white reference of Abs, and a filter of No. Measurement is performed by setting the measurement mode to Reflectance.

The content (solid content) of the white coloring material in the white ink is preferably 0.5% by mass or more and 20.0% by mass or less, more preferably 1.0% by mass or more and 20.0% by mass or less, based on the total mass of the white ink. It is 0% by mass or less, even more preferably 3.0% by mass or more and 15.0% by mass or less, even more preferably 7.0% by mass or more and 10.0% by mass or less. If the content of the white coloring material is within the above range, an image with sufficient visibility can be obtained.

In the recording method of this embodiment, the white coloring material is used not for the purpose of hiding the background of the image, but rather for the purpose of increasing the visibility of the obtained image itself. Therefore, the content of the white coloring material in the white ink can be made smaller than when the purpose is to hide the background. As a result, sufficient visibility of the image can be obtained, and the dispersion stability of the white coloring material can be easily improved and sedimentation can be made difficult. Furthermore, filling and image quality difference reduction are also better and preferred. From this point of view, the upper limit of the content of the white coloring material in the white ink is preferably 10.0% by mass or less, more preferably 8.0% by mass or less, and still more preferably 7.0% by mass or less. , particularly preferably 5.0% by mass or less.

It is preferable that the white coloring material can be stably dispersed in a dispersion medium, and for this purpose, a dispersant may be used for dispersion. Examples of the dispersant include resin dispersants, and are selected from those that can improve the dispersion stability of the white coloring material in the white ink containing the above-mentioned white coloring material. White coloring materials can also be used as self-dispersing pigments by modifying the surface of pigment particles by oxidizing or sulfonating the surface of the pigment with ozone, hypochlorous acid, fuming sulfuric acid, etc. good.

As a resin dispersant, poly(meth)acrylic acid, (meth)acrylic acid-acrylonitrile copolymer, (meth)acrylic acid-(meth)acrylic ester copolymer, vinyl acetate-(meth)acrylic ester Copolymers, (meth)acrylic resins and salts thereof such as vinyl acetate-(meth)acrylic acid copolymers, vinylnaphthalene-(meth)acrylic acid copolymers; styrene-(meth)acrylic acid copolymers, Styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymer, Styrene-α-methylstyrene-(meth)acrylic acid copolymer, Styrene-α-methylstyrene-(meth)acrylic acid-(meth) Styrenic resins and their salts such as acrylic acid ester copolymers, styrene-maleic acid copolymers, styrene-maleic anhydride copolymers; polymeric compounds containing urethane bonds in which isocyanate groups and hydroxyl groups have reacted (resin ), which may be linear and/or branched, with or without a crosslinked structure, urethane resins and their salts; polyvinyl alcohols; vinylnaphthalene-maleic acid copolymers and their salts; vinyl acetate Examples include water-soluble resins such as -maleic acid ester copolymers and salts thereof; and vinyl acetate-crotonic acid copolymers and salts thereof. Among these, copolymers of monomers having a hydrophobic functional group and monomers having a hydrophilic functional group, and polymers consisting of monomers having both a hydrophobic functional group and a hydrophilic functional group are preferred. The form of the copolymer can be any of random copolymers, block copolymers, alternating copolymers, and graft copolymers.

Commercially available styrenic resin dispersants include, for example, X-200, X-1, X-205, X-220, company), Jonkryl 67, 586, 611, 678, 680, 682, 819 (manufactured by BASF), DISPERBYK-190 (manufactured by BYK Chemie Japan Co., Ltd.), N-EA137, N-EA157, N-EA167, N -EA177, N-EA197D, N-EA207D, E-EN10 (manufactured by Daiichi Kogyo Seiyaku), etc.

In addition, commercially available acrylic resin dispersants include BYK-187, BYK-190, BYK-191, BYK-194N, BYK-199 (manufactured by BYK Chemie Co., Ltd.), Aron A-210, A6114, AS-1100, AS-1800, A-30SL, A-7250, CL-2 manufactured by Toagosei Co., Ltd.), etc.

Furthermore, commercially available urethane resin dispersants include BYK-182, BYK-183, BYK-184, BYK-185 (manufactured by BYK Chemi Co., Ltd.), TEGO Disperse 710 (manufactured by Evonic Tego Chemi Co., Ltd.), and Borchi (registered trademark). Examples include Gen1350 (manufactured by OMG Borschers).

The dispersants may be used alone or in combination of two or more. The total content of the dispersant is preferably 0.1 parts by mass or more and 30 parts by mass or less, more preferably 0.5 parts by mass or more and 25 parts by mass or less, and even more preferably The amount is 1 part by mass or more and 20 parts by mass or less, and even more preferably 1.5 parts by mass or more and 15 parts by mass or less. When the content of the dispersant is 0.1 parts by mass or more based on 50 parts by mass of the white coloring material, the dispersion stability of the white coloring material can be further improved. Further, if the content of the dispersant is 30 parts by mass or less with respect to 50 parts by mass of the white coloring material, the viscosity of the resulting dispersion can be kept low.

Among the dispersants exemplified above, at least one selected from acrylic resins, styrene resins, and urethane resins is more preferable. Further, in this case, the weight average molecular weight of the dispersant is more preferably 500 or more. By using such a resin dispersant as a dispersant, there is less odor and the dispersion stability of the white coloring material can be further improved.

Typical examples of white coloring materials include titanium dioxide, such as Taipei CR-50-2, CR-57, CR-58-2, CR-60-2, CR-60-3, CR-Super- 70, CR-90-2, CR-95, CR953, PC-3, PF-690, PF-691, PF-699, PF-711, PF-728, PF-736, PF-737, PF-739, Examples include PF-740, PF-742, R-980, and UT-771 (all manufactured by Ishihara Sangyo Co., Ltd.).

1.1.2. Other ingredients In addition to the white coloring material, white ink consists of resin particles, organic solvents, surfactants, water, wax, additives, resin dispersants, preservatives/fungicides, rust preventives, chelating agents, It may contain components such as a viscosity modifier, an antioxidant, and a fungicide. The following will be explained in order.

(resin particles)
The white ink may contain resin particles. The resin particles can further improve the adhesion of the image formed by the white ink attached to the recording medium. Examples of resin particles include urethane resins, acrylic resins (including styrene acrylic resins), fluorene resins, polyolefin resins, rosin-modified resins, terpene resins, polyester resins, polyamide resins, and epoxy resins. , vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, ethylene vinyl acetate resin, and the like. Among these, urethane resins, acrylic resins, polyolefin resins, and polyester resins are preferred. These resin particles are often handled in the form of an emulsion, but may also be in the form of a powder. Furthermore, the resin particles can be used alone or in combination of two or more.

Urethane resin is a general term for resins having urethane bonds. In addition to urethane bonds, urethane resins include polyether-type urethane resins containing ether bonds in the main chain, polyester-type urethane resins containing ester bonds in the main chain, polycarbonate-type urethane resins containing carbonate bonds in the main chain, etc. You may. Furthermore, commercially available products may be used as the urethane resin, such as Superflex 460, 460s, 840, E-4000 (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Rezamin D-1060, D-2020, D-4080, D-4200, D-6300, D-6455 (product name, manufactured by Dainichiseika Chemical Industry Co., Ltd.), Takelac WS-6021, W-512-A-6 (product name, manufactured by Mitsui Chemicals Polyurethane Co., Ltd.) ), SunCure 2710 (trade name, manufactured by LUBRIZOL), Permarin UA-150 (trade name, manufactured by Sanyo Chemical Industries, Ltd.), and other commercially available products may be used.

Acrylic resin is a general term for polymers obtained by polymerizing at least acrylic monomers such as (meth)acrylic acid and (meth)acrylic ester as one component. Examples include the resulting resins and copolymers of acrylic monomers and other monomers. Examples include acrylic-vinyl resins that are copolymers of acrylic monomers and vinyl monomers. Further, for example, examples of the vinyl monomer include styrene.

Acrylamide, acrylonitrile, etc. can also be used as the acrylic monomer. Commercially available products may be used for the resin emulsion made from acrylic resin, such as FK-854 (trade name, manufactured by Chuo Rika Kogyo Co., Ltd.), Movinyl 952B, 718A (trade name, manufactured by Nihon Gosei Kagaku Kogyo Co., Ltd.) , Nipol LX852, LX874 (trade name, manufactured by Zeon Corporation), etc. may be used.

Note that in this specification, the acrylic resin may be a styrene/acrylic resin described later. Moreover, in this specification, the notation "(meth)acrylic" means at least one of acrylic and methacryl.

Styrene-acrylic resin is a copolymer obtained from styrene monomer and (meth)acrylic monomer, and includes styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, and styrene-methacrylic acid copolymer. -acrylic acid ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer, and the like. Commercially available styrene/acrylic resins may be used, such as Joncryl 62J, 7100, 390, 711, 511, 7001, 632, 741, 450, 840, 74J, HRC-1645J, 734, 852, 7600, 775, 537J, 1535, PDX-7630A, 352J, 352D, PDX-7145, 538J, 7640, 7641, 631, 790, 780, 7610 (product name, manufactured by BASF), Movinyl 966A, 975N (product name, (manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd.), Vinibran 2586 (manufactured by Nissin Kagaku Kogyo Co., Ltd.), etc. may also be used.

The polyolefin resin has an olefin such as ethylene, propylene, butylene in its structural skeleton, and known resins can be appropriately selected and used. As the olefin resin, commercial products can be used, such as Arrowbase CB-1200 and CD-1200 (trade name, manufactured by Unitika Co., Ltd.).

Further, the resin particles may be supplied in the form of an emulsion, and examples of commercially available resin emulsions include Microgel E-1002, E-5002 (trade name manufactured by Nippon Paint Co., Ltd., styrene-acrylic Resin emulsion), Boncoat 4001 (product name manufactured by DIC Corporation, acrylic resin emulsion), Boncoat 5454 (product name manufactured by DIC Corporation, styrene-acrylic resin emulsion), Polysol AM-710, AM-920, AM-2300, AP -4735, AT-860, PSASE-4210E (acrylic resin emulsion), Polysol AP-7020 (styrene/acrylic resin emulsion), Polysol SH-502 (vinyl acetate resin emulsion), Polysol AD-13, AD-2, AD -10, AD-96, AD-17, AD-70 (ethylene/vinyl acetate resin emulsion), Polysol PSASE-6010 (ethylene/vinyl acetate resin emulsion) (product name manufactured by Showa Denko), Polysol SAE1014 (product name, Styrene-acrylic resin emulsion, manufactured by Nippon Zeon Co., Ltd.), Cybinol SK-200 (trade name, acrylic resin emulsion, manufactured by Saiden Chemical Co., Ltd.), AE-120A (trade name, acrylic resin emulsion manufactured by JSR Corporation), AE373D (Etech Seikadyne 1900W (Dainichiseika Chemical Co., Ltd. product name, ethylene/vinyl acetate resin emulsion), Viniblan 2682 (acrylic resin emulsion), Viniblan 2886 (vinyl acetate/acrylic resin) Emulsion), Viniblan 5202 (acetic acid acrylic resin emulsion) (trade name manufactured by Nissin Chemical Industry Co., Ltd.), Elitel KA-5071S, KT-8803, KT-9204, KT-8701, KT-8904, KT
-0507 (product name manufactured by Unitika Co., Ltd., polyester resin emulsion), Hitec SN-2002 (product name manufactured by Toho Chemical Co., Ltd., polyester resin emulsion), Takelac W-6020, W-635, W-6061, W-605, W- 635, W-6021 (trade name manufactured by Mitsui Chemicals Polyurethane Co., Ltd., urethane resin emulsion), Superflex 870, 800, 150, 420, 460, 470, 610, 700 (trade name manufactured by Daiichi Kogyo Seiyaku Co., Ltd., urethane resin emulsion) Emulsion), Permarin UA-150 (manufactured by Sanyo Chemical Industries, Ltd., urethane resin emulsion), SunCure 2710 (manufactured by Japan Lubrizol Co., Ltd., urethane resin emulsion), NeoRez R-9660, R-9637, R-940 ( Kusumoto Kasei Co., Ltd., urethane resin emulsion), ADEKA Bontiter HUX-380, 290K (ADEKA Co., Ltd., urethane resin emulsion), Movinyl 966A, Movinyl 7320 (Nippon Gosei Kagaku Co., Ltd.), Joncryl 7100, 390, 711, 511, 7001, 632, 741, 450, 840, 74J, HRC-1645J, 734, 852, 7600, 775, 537J, 1535, PDX-7630A, 352J, 352D, PDX-7145, 538J, 7640, 7641, 631, 790, 780, 7610 (manufactured by BASF), NK Binder R-5HN (manufactured by Shin Nakamura Chemical Co., Ltd.), Hydran WLS-210 (non-crosslinked polyurethane: manufactured by DIC Corporation), Joncryl 7610 (manufactured by BASF) and the like.

The glass transition temperature (Tg) of the resin particles is preferably -50°C or more and 200°C or less, more preferably 0°C or more and 150°C or less, and still more preferably 50°C or more and 100°C or less. Further, the temperature is particularly preferably 50°C or more and 80°C or less. When the glass transition temperature (Tg) of the resin particles is within the above range, durability and clogging resistance tend to be better. The glass transition temperature is measured, for example, using a differential scanning calorimeter "DSC7000" manufactured by Hitachi High-Tech Science Co., Ltd., in accordance with JIS K7121 (method for measuring transition temperature of plastics).

The volume average particle diameter of the resin particles is preferably 10 nm or more and 300 nm or less, more preferably 30 nm or more and 300 nm or less, even more preferably 30 nm or more and 250 nm or less, and particularly preferably 40 nm or more and 220 nm or less. The volume average particle diameter can be measured by the method described above.

When the white ink contains resin particles, the content is 0.1% by mass or more and 20% by mass or less, preferably 1% by mass or more and 15% by mass or less, based on the total mass of the white ink. Preferably it is 2% by mass or more and 10% by mass or less.

(Organic solvent)
The white ink used in the recording method according to this embodiment may contain an organic solvent. It is preferable that the organic solvent has water solubility. One of the functions of the organic solvent is to improve the wettability of the white ink to the recording medium and to improve the moisture retention property of the white ink. Organic solvents can also function as penetrants.

Examples of the organic solvent include esters, alkylene glycol ethers, cyclic esters, nitrogen-containing solvents, and polyhydric alcohols. Examples of the nitrogen-containing solvent include cyclic amides and acyclic amides. Examples of acyclic amides include alkoxyalkylamides and the like.

As esters, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate,
Glycol monoacetates such as propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, methoxybutyl acetate, ethylene glycol diacetate, diethylene glycol diacetate, propylene glycol diacetate, dipropylene glycol diacetate, ethylene glycol acetate propionate , ethylene glycol acetate butyrate, diethylene glycol acetate butyrate, diethylene glycol acetate propionate, diethylene glycol acetate butyrate, propylene glycol acetate propionate, propylene glycol acetate butyrate, dipropylene glycol acetate butyrate, dipropylene glycol acetate propionate Examples include glycol diesters such as .

The alkylene glycol ethers may be alkylene glycol monoethers or diethers, and alkyl ethers are preferred. Specific examples include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, and triethylene glycol. Monoethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, 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, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, alkylene glycol monoalkyl ethers, ethylene glycol dimethyl ether, ethylene glycol diethyl Ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl butyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, triethylene glycol methyl butyl ether, Examples include alkylene glycol dialkyl ethers such as tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, and tripropylene glycol dimethyl ether. It will be done.

Furthermore, among the above-mentioned alkylene glycols, diethers tend to dissolve or swell the resin particles in the ink more easily than monoethers, and are more preferable in terms of improving the abrasion resistance of the formed image.

Examples of cyclic esters include β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, β-butyrolactone, β-valerolactone, γ-valerolactone, β-hexanolactone, γ-hexanolactone. , δ-hexanolactone, β-heptanolactone, γ-heptanolactone, δ-heptanolactone, ε-heptanolactone, γ-octanolactone, δ-octanolactone, ε-octanolactone, δ - List cyclic esters (lactones) such as nonalactone, ε-nonalactone, ε-decanolactone, etc., as well as compounds in which the hydrogen of the methylene group adjacent to their carbonyl group is substituted with an alkyl group having 1 to 4 carbon atoms. Can be done.

Examples of the alkoxyalkylamides include 3-methoxy-N,N-dimethylpropionamide, 3-methoxy-N,N-diethylpropionamide, 3-methoxy-N,N-methylethylpropionamide, and 3-ethoxy-N,N-dimethylpropionamide. N,N-dimethylpropionamide, 3-ethoxy-N,N-diethylpropionamide, 3-ethoxy-N,N-methylethylpropionamide, 3-n-butoxy-N,N-dimethylpropionamide, 3-n -Butoxy-N,N-diethylpropionamide, 3-n-butoxy-N,N-methylethylpropionamide, 3-n-propoxy-N,N-dimethylpropionamide, 3-n-propoxy-N,N- Diethylpropionamide, 3-n-propoxy-N,N-methylethylpropionamide, 3-iso-propoxy-N,N-dimethylpropionamide, 3-iso-propoxy-N,N-diethylpropionamide, 3-iso -Propoxy-N,N-methylethylpropionamide, 3-tert-butoxy-N,N-dimethylpropionamide, 3-tert-butoxy-N,N-diethylpropionamide, 3-tert-butoxy-N,N- Examples include methylethylpropionamide and the like.

Examples of the cyclic amides include lactams, such as 2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1-propyl-2-pyrrolidone, 1-butyl-2-pyrrolidone, Examples include pyrrolidones such as. These are preferable from the viewpoint of improving the solubility of the flocculant and promoting the formation of a film on the resin particles, which will be described later. In particular, 2-pyrrolidone is more preferable.

Moreover, it is also preferable to use a compound represented by the following general formula (1) as the alkoxyalkylamide.

R ¹ -O-CH ₂ CH ₂ -(C=O)-NR ² R ³ ...(1)

In the above formula (1), R ¹ represents an alkyl group having 1 to 4 carbon atoms, and R ² and R ³ each independently represent a methyl group or an ethyl group. "Alkyl group having 1 to 4 carbon atoms" can be a linear or branched alkyl group, for example, methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group. , sec-butyl group, iso-butyl group, and tert-butyl group. The compounds represented by the above formula (1) may be used alone or in combination of two or more.

The function of the compound represented by formula (1) includes, for example, improving the surface drying properties and fixing properties of white ink deposited on a low-absorption recording medium. In particular, the compound represented by the above formula (1) has an excellent effect of appropriately softening and dissolving vinyl chloride resin. Therefore, the compound represented by the above formula (1) can soften and dissolve the recording surface containing the vinyl chloride resin and allow the white ink to penetrate into the interior of the low-absorbency recording medium. As the white ink permeates into the low-absorbency recording medium in this way, the white ink is firmly fixed, and the surface of the white ink dries easily. Therefore, the resulting image tends to have excellent surface drying properties and fixing properties.

Further, in the above formula (1), R ¹ is more preferably a methyl group having 1 carbon number. In the above formula (1), the standard boiling point of a compound in which R ¹ is a methyl group is lower than that of a compound in which R ¹ is an alkyl group having 2 or more and 4 or less carbon atoms. Therefore, when using a compound in which R ¹ is a methyl group in the above formula (1), the surface drying property of the attached area (especially the surface drying property of the image when recorded in a high temperature and humid environment) can be further improved. There is.

When using the compound represented by the above formula (1), the content is not particularly limited to the total mass of the white ink, but is approximately 5% by mass or more and 50% by mass or less, and 8% by mass or more and 48% by mass. % or less. When the content of the compound represented by the above formula (1) is within the above range, image fixing properties and surface drying properties (particularly surface drying properties when recorded in a high temperature and high humidity environment) can be further improved. There is.

Examples of polyhydric alcohols include 1,2-alkanediol (for example, ethylene glycol, propylene glycol (also known as propane-1,2-diol), 1,2-butanediol, 1,2-pentanediol, 1,2- alkanediols such as hexanediol, 1,2-heptanediol, 1,2-octanediol), polyhydric alcohols (polyols) other than 1,2-alkanediol (e.g. diethylene glycol, dipropylene glycol, 1,3 -Propanediol, 1,3-butanediol (also known as 1,3-butylene glycol), 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2-ethyl-2-methyl- 1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl- 1,3-butanediol, 2-ethyl-1,3-hexanediol, 3-methyl-1,5-pentanediol, 2-methylpentane-2,4-diol, trimethylolpropane, glycerin, etc.). It will be done.

Polyhydric alcohols can be divided into alkanediols and polyols. Alkanediols are alkane diols having 5 or more carbon atoms. The alkane preferably has 5 to 15 carbon atoms, more preferably 6 to 10 carbon atoms, and still more preferably 6 to 8 carbon atoms. Preferably it is a 1,2-alkanediol.

The polyols are polyols of alkanes having 4 or less carbon atoms or intermolecular condensates of hydroxyl groups of polyols of alkanes having 4 or less carbon atoms. The number of carbon atoms in the alkane is preferably 2 to 3. The number of hydroxyl groups in the molecule of the polyol is 2 or more, preferably 5 or less, and more preferably 3 or less. When the polyol is the above-mentioned intermolecular condensation product, the number of intermolecular condensations is 2 or more, preferably 4 or less, and more preferably 3 or less. Polyhydric alcohols can be used alone or in combination of two or more.

Alkanediols and polyols can primarily function as penetrating and/or humectant solvents. However, alkanediols tend to have strong properties as penetrating solvents, and polyols tend to have strong properties as moisturizing solvents.

When the white ink contains an organic solvent, one type of organic solvent may be used alone, or two or more types may be used in combination. Further, the total content of the organic solvent based on the total mass of the white ink is, for example, 5% by mass or more and 50% by mass or less, preferably 10% by mass or more and 45% by mass or less, and 15% by mass or more and 40% by mass or less. More preferably, it is 20% by mass or more and 40% by mass or less. When the content of the organic solvent is within the above range, the balance between wetting and spreading properties and drying properties is better, and it is easier to form images of higher quality.

Moreover, it is more preferable that the white ink contains an organic solvent having a normal boiling point of 150.0° C. or more and 280.0° C. or less among the organic solvents listed above. In this way, it is possible to perform recording in which the formed image is dried and fixed more quickly.

Furthermore, it is more preferable that the white ink does not contain more than 1.0% by mass of an organic solvent such as a polyol having a normal boiling point of more than 280.0°C. The content of organic solvents such as polyols with a standard boiling point exceeding 280°C in the white ink is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 3% by mass or less based on the total mass of the white ink. It is 1% by mass or less, particularly preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less. The lower limit of the organic solvent content of polyols with a standard boiling point exceeding 280°C may be 0% by mass.

In this way, the formed image can be dried well, recording can be performed more quickly, and the adhesion to the recording medium can also be improved. Furthermore, it is more preferable that the white ink contains an organic solvent (not limited to polyols) having a standard boiling point of over 280.0° C. within the above range. Examples of organic solvents having a normal boiling point exceeding 280°C include glycerin, polyethylene glycol monomethyl ether, and the like.

(surfactant)
The white ink may contain a surfactant. The surfactant has the function of lowering the surface tension of the white ink and improving its wettability with the recording medium. Among the surfactants, for example, acetylene glycol surfactants, silicone surfactants, and fluorine surfactants can be preferably used.

Examples of the acetylene glycol surfactant include, but are not limited to, Surfynol 104, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 104S, 420, 440, 465, 485, SE, SE- F, 504, 61, DF37, CT111, CT121, CT131, CT136, TG, GA, DF110D (all product names, manufactured by Air Products & Chemicals), Olfin B, Y, P, A, STG, SPC, E1004 , E1010, PD-001, PD-002W, PD-003, PD-004, EXP. 4001, EXP. 4036, EXP. 4051, AF-103, AF-104, AK-02, SK-14, AE-3 (all product names, manufactured by Nissin Chemical Industry Co., Ltd.), acetylenol E00, E00P, E40, E100 (all product names, Kawa (manufactured by Ken Fine Chemical Co., Ltd.).

The silicone surfactant is not particularly limited, but polysiloxane compounds are preferred. The polysiloxane compound is not particularly limited, but includes, for example, polyether-modified organosiloxane. Commercially available polyether-modified organosiloxanes include, for example, BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348 (trade name: 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 product names, manufactured by Shin-Etsu Chemical Co., Ltd.), Silface SAG002, 005, 503A, 008 (all product names, manufactured by Nissin Chemical Co., Ltd.) (manufactured by), etc.

As the fluorine-based surfactant, it is preferable to use a fluorine-modified polymer, and specific examples include BYK-3440 (manufactured by BYK-Chemie Japan), Surflon S-241, S-242, and S-243 (product names listed above). AGC Seimi Chemical Co., Ltd.), Ftergent 215M (Neos Co., Ltd.), and the like.

When the white ink contains a surfactant, a plurality of surfactants may be contained. When the white ink contains a surfactant, the content is 0.1% by mass or more and 2% by mass or less, preferably 0.4% by mass or more and 1.5% by mass or less, based on the total mass of the white ink. More preferably, it is 0.5% by mass or more and 1.0% by mass or less.

(water)
The white ink used in the recording method according to this embodiment may contain water. The white ink is preferably a water-based white ink. Aqueous systems are compositions that contain water as one of the main solvent components. In this way, it is possible to perform recording with less odor and the like with a reduced environmental load.

Water may be included as a main solvent component of the white ink, and is a component that evaporates and scatters when dried. The water is preferably purified water such as ion-exchanged water, ultrafiltrated water, reverse osmosis water, distilled water, etc., or ultrapure water from which ionic impurities have been removed as much as possible. Furthermore, it is preferable to use water that has been sterilized by ultraviolet irradiation or hydrogen peroxide addition, since this can suppress the growth of mold and bacteria when the ink is stored for a long period of time. The water content is preferably 45% by mass or more, more preferably 50% by mass or more and 98% by mass or less, and even more preferably 55% by mass or more and 95% by mass or less based on the total amount of the white ink.

(wax)
The white ink may contain wax. Since the wax has a function of imparting lubricity to the white ink image, it is possible to reduce peeling of the white ink image.

Components that make up the wax include, for example, plant and animal waxes such as carnauba wax, candeli wax, beeswax, rice wax, and lanolin; petroleum waxes such as paraffin wax, microcrystalline wax, polyethylene wax, oxidized polyethylene wax, and petrolatum. Mineral waxes such as montan wax and ozokerite; Carbon waxes, Hoechst waxes, polyolefin waxes, synthetic waxes such as stearic acid amide, natural and synthetic waxes such as α-olefin/maleic anhydride copolymers, emulsions and blended waxes, etc. These can be used alone or in combination. Among these, it is preferable to use polyolefin waxes (especially polyethylene waxes and polypropylene waxes) and paraffin waxes from the viewpoint of their superior effect of increasing the fixability to flexible packaging films, which will be described later.

As the wax, commercially available products can be used as they are, such as Nopcote PEM-17 (trade name, manufactured by San Nopco Co., Ltd.), Chemipearl W4005 (trade name, manufactured by Mitsui Chemicals Co., Ltd.), AQUACER515, 539, 593 (products listed above). (manufactured by BIC Chemie Japan Co., Ltd.), etc.

In addition, from the viewpoint of preventing the wax from melting too much and deteriorating its performance when the recording method includes a heating step, etc., the melting point of the wax is preferably 50°C or more and 200°C or less, more preferably It is preferable to use a wax having a melting point of 70°C or more and 180°C or less, more preferably 90°C or more and 150°C or less.

The wax may be supplied in the form of an emulsion or suspension. The wax content is 0.1% by mass or more and 10% by mass or less, more preferably 0.5% by mass or more and 5% by mass or less, and even more preferably 0.5% by mass based on the total mass of the white ink. It is at least 2% by mass and not more than 2% by mass. When the wax content is within the above range, the wax can perform its functions well. Note that if one or both of the white ink and the non-white ink described below contains wax, a sufficient function of imparting lubricity to the image can be obtained.

(Additive)
The white ink may contain ureas, amines, sugars, etc. as additives. Examples of ureas include urea, ethyleneurea, tetramethylurea, thiourea, 1,3-dimethyl-2-imidazolidinone, etc., and betaines (trimethylglycine, triethylglycine, tripropylglycine, triisopropylglycine, N , N,N-trimethylalanine, N,N,N-triethylalanine, N,N,N-triisopropylalanine, N,N,N-trimethylmethylalanine, carnitine, acetylcarnitine, etc.).

Examples of amines include diethanolamine, triethanolamine, triisopropanolamine, and the like. Ureas and amines may function as pH adjusters.
Examples of sugars include glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol (sorbitol), maltose, cellobiose, lactose, sucrose, trehalose, and maltotriose.

(others)
The white ink used in the recording method according to the present embodiment may further contain components such as a preservative/mold inhibitor, a rust preventive agent, a chelating agent, a viscosity modifier, an antioxidant, and a fungicide, as necessary. May be contained.

1.1.3. Physical properties of white ink and method for adhering to recording medium The white ink adhesion step may be performed in any manner as long as the white ink is applied while scanning the recording head with respect to the recording medium. For example, this can be preferably carried out by using an inkjet head as the recording head and ejecting white ink from the inkjet head. In this way, a small amount of printing of many types can be efficiently performed using a small device.

When the white ink is applied to the recording medium by an inkjet method, the viscosity of the white ink at 20°C is preferably 1.5 mPa·s or more and 15 mPa·s or less, and 1.5 mPa·s or more and 7 mPa·s or less. - It is more preferable to set it to below s, and it is more preferable to set it as 1.5 mPa*s or more and 5.5 mPa*s or less. When white ink is applied to a recording medium by an inkjet method, it is easy to efficiently form a predetermined image on the recording medium.

The white ink has a surface tension at 25° C. of 40 mN/m or less, preferably 38 mN/m or less, more preferably 35 mN/m or less, and even more preferably It is preferable that it is 30 mN/m or less. The surface tension was measured using an automatic surface tension meter CBVP-Z (manufactured by Kyowa Kaimen Kagaku Co., Ltd.) by checking the surface tension when a platinum plate was wetted with the composition in an environment of 25°C. can do.

1.2. Non-white ink adhesion process The non-white ink adhesion process is a process of adhering non-white ink to the recording medium. The non-white ink will be explained below. The method of adhering to the recording medium will be described later.

1.2.1. Non-white coloring material Non-white ink contains a white coloring material. The non-white coloring material contained in the non-white ink refers to a coloring material other than the above-mentioned white coloring material. Examples of non-white coloring materials include dyes and pigments. The non-white coloring material is preferably a coloring material such as cyan, yellow, magenta, or black.

The non-white coloring material may be either a dye or a pigment, or a mixture thereof. However, among dyes and pigments, it is more preferable to include pigments. The pigment has excellent storage stability such as light resistance, weather resistance, and gas resistance, and from this viewpoint, it is preferably an organic pigment.

Specifically, the pigments include azo pigments such as insoluble azo pigments, condensed azo pigments, azo lakes, and chelate azo pigments, phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments, Polycyclic pigments such as quinophthalone pigments, dye chelates, dye lakes, nitro pigments, nitroso pigments, aniline black, daylight fluorescent pigments, carbon black, etc. are used. The above pigments can be used alone or in combination of two or more. Furthermore, a glittering pigment may be used as the non-white coloring material.

Specific examples of pigments include, but are not limited to, the following:

As the black pigment, for example, No. 2300, No. 900, MCF88, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100, No. 2200B, etc. (all manufactured by Mitsubishi Chemical Corporation), Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Raven 700, etc. (all manufactured by Columbia Carbon) bon Columbia), Rega1 400R, Rega1 330R, Rega1 660R, Mogul L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch h 1400 etc. (manufactured by CABOT JAPAN KK), Color Black FW1 , Color Black FW2, Color Black
FW2V, Color Black FW18, Color Black FW200, Color B1ack S150, Color Black S160, Color
Black S170, Printex 35, Printex U, Printex
V, Printex 140U, Special Black 6, Special Black 5, Special Black 4A, and Special Black 4 (all manufactured by Degussa).

Examples of yellow pigments include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, 120, 124, 128, 129, 133, 138, 139, 147, 151, 153, 154, 167, 172, and 180.

Examples of magenta pigments include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48 (Ca), 48 (Mn), 57 (Ca), 57:1, 88, 112, 114, 122, 123, 144, 146, 149, 150, 166, 168 , 170, 171, 175, 176, 177, 178, 179, 184, 185, 187, 202, 209, 219, 224, 245, or C. I. Pigment Violet 19, 23, 32, 33, 36, 38, 43, and 50.

Examples of cyan pigments include C.I. I. Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:34, 15:4, 16, 18, 22, 25, 60, 65, 66, C. I. Bat Blue 4 and 60 are examples.

Pigments other than magenta, cyan, and yellow are not particularly limited, but for example, C.I. I. Pigment Green 7,10, C. I. Pigment Brown 3, 5, 25, 26, C. I. Pigment Orange 1, 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, 63.

Examples of pearl pigments include, but are not limited to, pigments having pearlescent luster or interference luster, such as titanium dioxide-coated mica, fish scale foil, and bismuth acid chloride.

Examples of metallic pigments include, but are not limited to, particles made of a single substance or an alloy of aluminum, silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, copper, or the like.

Examples of dyes include various dyes normally used in inkjet recording, such as direct dyes, acid dyes, food dyes, basic dyes, reactive dyes, disperse dyes, vat dyes, soluble vat dyes, and reactive disperse dyes. can be used.

It is preferable that the non-white coloring material can be stably dispersed or dissolved in a dispersion medium, and may be dispersed using a dispersant as necessary. Examples of the dispersant include the same dispersants used to improve the dispersibility of the white coloring material in the above-mentioned white ink.

The content of the non-white coloring material is preferably 0.3% by mass or more and 20% by mass or less, more preferably 0.5% by mass or more and 15% by mass or less, based on the total mass of the non-white ink. Furthermore, it is preferably 1 to 10% by weight, more preferably 2 to 7% by weight.

When a pigment is used as a non-white coloring material, the volume average particle diameter of the pigment particles is preferably 10 nm or more and 300 nm or less, more preferably 30 nm or more and 250 nm or less, further preferably 50 nm or more and 250 nm or less, and particularly preferably 70 nm or more and 200 nm or less. . Furthermore, 80 to 150 nm is preferable. The volume average particle size of the non-white coloring material is measured in the initial state using the method for confirming the volume average particle size described above. When the volume average particle diameter is within the above range, it is preferable because it is easy to obtain a desired coloring material and it is easy to make the characteristics of the coloring material favorable.

1.2.2. Other Ingredients In addition to the non-white coloring material, non-white ink consists of resin particles, organic solvents, surfactants, water, wax, additives, resin dispersants, preservatives/fungicides, rust preventives, and chelating agents. It may also contain components such as a disinfectant, a viscosity modifier, an antioxidant, and a fungicide.

The components of the non-white ink other than the coloring material are similar to those of the white ink, and can be made independent of the white ink. Any of these components may be the same as the above-mentioned white ink, and a detailed explanation will be omitted by replacing "white ink" with "non-white ink."

As with the white ink, the non-white ink is more preferably a water-based ink. In this way, it is possible to perform recording with less odor and the like with a reduced environmental load.

Further, like the white ink, the non-white ink preferably contains an organic solvent having a normal boiling point of 150.0° C. or more and 280.0° C. or less. Thereby, it is possible to perform recording in which the image is fixed more quickly.

Furthermore, like the white ink, it is preferable that the non-white ink does not contain more than 1.0% by mass of an organic solvent having a normal boiling point of more than 280.0. As a result, it is possible to perform recording in which the image dries more quickly, and it is also expected that the adhesion of the image will be improved.

1.2.3. Physical properties of non-white ink and method for adhering it to a recording medium The non-white ink adhesion process can be performed by any method as long as the non-white ink is applied while scanning the recording head with respect to the recording medium. However, it is more preferable to use an inkjet head as the recording head and eject non-white ink from the inkjet head. In this way, a small amount of printing of many types can be efficiently performed using a small device. The viscosity, surface tension, etc. of the non-white ink are the same as those of the white ink, so their explanation will be omitted.

1.3. Recording Medium The recording medium on which an image is formed by the recording method according to this embodiment is a non-white recording medium. The recording medium may or may not have a recording surface that absorbs ink. Therefore, there are no particular restrictions on the recording medium, and examples include non-white liquid-absorbing recording media such as paper, film, and cloth; low-liquid-absorbing recording media such as printing paper; non-white liquid absorbing recording media such as metal, glass, and Examples include liquid non-absorbent recording media such as molecules. The excellent effects of the recording method of this embodiment are more pronounced when an image is recorded on a non-white recording medium with low liquid absorption or non-liquid absorption. When the recording medium is a low-absorption or non-absorption recording medium, it is possible to more easily form an image with good filling, for example.

A low liquid absorption or non-liquid absorption recording medium refers to a recording medium that does not absorb ink at all or hardly absorbs ink. Quantitatively, a non-liquid-absorbent or low-liquid-absorbent recording medium is "a recording medium in which the amount of water absorbed in the Bristow method from the start of contact to 30 msec ^1/2 is 10 mL/m ² or less" refers to 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". On the other hand, a liquid-absorbing recording medium refers to a recording medium that does not fall under the category of non-liquid-absorbing or low-liquid-absorbing. Note that in this specification, low liquid absorption and liquid non-absorption may be simply referred to as low absorption and non-absorption.

Examples of non-liquid-absorbing recording media include those with a base material such as paper coated with plastic, those with a plastic film glued onto a base material such as paper, and those with an absorbent layer (receptive layer). Examples include plastic films that do not have Examples of the plastic here include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, and the like.

Furthermore, examples of recording media with low liquid absorption include recording media whose surfaces are provided with a coating layer with low liquid absorption. For example, it is called coated paper. For example, when the base material is paper, printing paper such as art paper, coated paper, matte paper, etc. can be mentioned, and when the base material is a plastic film, polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, Examples include those in which a polymer or the like is coated on the surface of polyurethane, polyethylene, polypropylene, etc., and those in which particles of silica, titanium, etc. are coated together with a binder.

A liquid-absorbing recording medium can also be used as the recording medium. The liquid-absorbing recording medium refers to the above-mentioned "recording medium in which the amount of water absorbed in the Bristow method from the start of contact to 30 msec ^1/2 is more than 10 mL/m ² ".

Examples of liquid-absorbent recording media include those that are made liquid-absorbent by providing a liquid-absorbing receptor layer on the surface of the recording medium. For example, inkjet paper (paper exclusively for inkjet) may be used. Examples of the receiving layer that absorbs liquid include a layer made of liquid-absorbing resin, liquid-absorbing inorganic fine particles, and the like.

Examples of liquid-absorbent recording media include recording media in which the base material of the recording medium itself is liquid-absorbent. Examples include cloth made of fibers and paper made of pulp. Examples of the paper include plain paper, cardboard, and liner paper. Examples of the liner paper include those made of paper such as kraft pulp and waste paper.

The recording method of this embodiment is performed on a non-white recording medium. Examples of non-white recording media include transparent recording media (transparent recording media). The transparent recording medium may be colorless and transparent or colored (colored) and transparent. Transparent also includes translucent. These are recording media that have visual transparency. It is also a recording medium that transmits visible light. In such a case, with the recording method of this embodiment, an image formed on one side of the recording medium can be clearly viewed from both sides.

And/or the non-white recording medium includes a non-white colored recording medium (non-white colored recording medium). Examples include non-white colored opaque recording media and non-white colored transparent recording media. In this case as well, by the recording method of this embodiment, it is possible to easily form an image with good image quality such as visibility, filling, and reduction of image quality differences. The non-white colored recording medium may be the above-mentioned transparent recording medium or may be a non-transparent recording medium. A recording medium that is not transparent is a recording medium that does not have visual transparency. It is also a recording medium that does not transmit visible light. Here, the non-white color is a color other than white.

1.4. Relationship between the white ink adhesion process and the non-white ink adhesion process In the recording method of this embodiment, the white ink adhesion process and the non-white ink adhesion process are performed by scanning the print head with respect to the print medium. These steps can be easily performed using an inkjet recording device described later.

Scanning is an operation in which the ink composition is deposited on the recording medium while the recording head, which deposits the ink on the recording medium, is moved to a different position relative to the recording medium. The scanning causes ink to adhere to the recording medium. Scanning may be performed while moving the print head relative to the print medium, or may be performed while moving the print medium relative to the print head. Both are scans of the print head on the print medium. Scanning is also called main scanning.

The recording head may be any type as long as it can adhere ink to the recording medium, and examples thereof include, but are not limited to, an inkjet head, a dot impact head, a thermal transfer head, and the like.

The white ink adhesion process and the non-white ink adhesion process are performed on the same area of the recording medium in the same scan. Here, in the case of a serial type inkjet printing apparatus as described later, the same scan refers to one scan of the print head in the main scanning direction. When the print head reciprocates and scans multiple times, it refers to either the forward path or the backward path (one scan). Therefore, when the white ink adhesion process and the non-white ink adhesion process are performed in the same scan, it means that both processes are performed during one scan of the recording head.

For example, when scanning is performed by ejecting white ink from nozzle row N1 and ejecting non-white ink from nozzle row N2 using an inkjet head as shown in FIG. 4, which will be described later, nozzle row N1 and nozzle row N2 are , has an overlapping portion in the sub-scanning direction SS when projected in the main-scanning direction MS. In this case, one scan of the inkjet head causes white ink and non-white ink to be deposited on the same area of the recording medium. In the above example, when the nozzle row N1 that ejects white ink and the nozzle row N2 that ejects non-white ink are projected in the main scanning direction MS, the nozzle row N1 and the nozzle row N2 are in the same area. , are mutually overlapping parts in the sub-scanning direction SS.

In the recording method of this embodiment, an area to which both white ink and non-white ink are deposited is formed on the recording medium by the white ink deposition step and the non-white ink deposition step. Then, in the area, the mass ratio (A/B) of the amount A of the white coloring material adhered to the amount B of the non-white coloring material adhered per unit area is 0.03 or more and 0.99 or less. . The amount of adhesion is the mass per unit area, and the mass ratio (A/B) is the mass ratio of the amount of adhesion.

The recording method of the present embodiment only needs to have at least an area where the mass ratio (A/B) is 0.03 or more and 0.99 or less in the area of the recording medium to which the white ink and the non-white ink are attached. .

In particular, in the area of the recording medium to which white ink and non-white ink are attached, the mass ratio is (A/B) may be 0.03 or more and 0.99 or less, which is preferable. In this case, it is preferable that an image with excellent visibility can be obtained in a region where the amount of adhesion B is large and visibility is particularly required.

In this case, for example, among the areas of the recording medium to which white ink and non-white ink are adhered, in areas where the adhesion amount B is not the maximum value in recording, the mass ratio (A/B) is not necessarily 0.03 or more. Although it does not have to be 0.99 or less, it may be 0.03 or more and 0.99 or less or more than 0.99, which is preferable. In particular, it is preferable to exceed 0.99. In this case, in areas where the adhesion amount B is not the maximum value, that is, in areas where the adhesion amount B is less than the maximum value, the mixing of the white ink and the non-white ink is better, and even in such areas, visual recognition is possible. It is possible to form an image with good properties, and since the mass ratio (A/B) is more than 0.99, filling is better in the area where the adhesion amount B is less than the maximum value, which is preferable.

Furthermore, in the area where the white ink and non-white ink are deposited, the mass ratio (A/B) is 0 over the area where the deposition amount B is 40 to 100% by mass of the maximum value of the deposition amount B. More preferably, it is .03 or more and 0.99 or less.

In addition, in the area where the white ink and non-white ink are deposited, the mass ratio (A/B) is 0.03 over the area where the deposition amount B is less than 40% by mass of the maximum value of the deposition amount B. It is preferable to set it to 0.99 or less or more than 0.99.

1.5. Adhering amount In the area of the recording medium to which the white coloring material and the non-white coloring material are adhered, the adhesion amount A of the white coloring material is preferably 0.1 mg/inch ² or less, more preferably 0.05 mg/inch ² or less. , 0.04 mg/inch ² or less is even more preferable, and 0.03 mg/inch ² or less is even more preferable. The amount of adhesion is preferably 0.005 mg/inch ² or more, more preferably 0.01 mg/inch ² or more, and even more preferably 0.02 mg/inch ² or more. In particular, in the area where the white coloring material and the non-white coloring material are deposited at a mass ratio (A/B) of 0.03 or more and 0.99 or less, it is preferable that the amount A of the deposited material is within the above range.

Further, in the area of the recording medium to which the white coloring material and the non-white coloring material are attached, the amount of white ink deposited on the recording medium is preferably 0.1 mg/inch 2 or more, and 0.1 mg/inch ² or more. More preferably, it is .3 mg/inch ² or more, and even more preferably 0.5 mg/inch ² or more. Further, the adhesion amount is preferably 15.0 mg/inch ² or less, more preferably 10.0 mg/inch ² or less. In particular, in the area where the white coloring material and the non-white coloring material are deposited at a mass ratio (A/B) of 0.03 or more and 0.99 or less, it is preferable that the amount of the deposited coloring material falls within the above range.

By forming such a region, the quality of the obtained image can be further improved. In the recording method of the present embodiment, the amount A of the white coloring material adhered and the amount of the white ink composition adhered are such that the above region has at least an area where the amount of these adhered falls within the above range. . Preferably, in the area where the amount of non-white ink adhered to is the largest and the area where the amount of non-white color material B adhered to is the largest in the above-mentioned area, it is more preferable that the amount of these adhered is within the above range.

The amount of non-white ink adhered in the region where the amount of non-white ink adhered is the maximum in the above region is preferably 3 mg/inch ² or more, and more preferably 5 mg/inch ² or more. Moreover, 20 mg/inch ² or less is preferable, 15 mg/inch ² or less is more preferable, and 12 mg/inch ² or more is still more preferable.

Furthermore, the amount B of the non-white coloring material deposited in the area where the amount of non-white coloring material deposited is the maximum in the above region is preferably 0.1 mg/inch ² or more, and more preferably 0.2 mg/inch ² or more. Moreover, 1 mg/inch ² or less is preferable, 0.5 mg/inch ² or less is more preferable, and 0.4 mg/inch ² or more is still more preferable.

Furthermore, in the area where the white coloring material and the non-white coloring material are deposited, the amount of white ink deposited on the recording medium may be constant or may vary depending on the location. In particular, the amount may be varied depending on the location depending on the amount of non-white ink attached, and the amount may be varied depending on the location depending on the amount of attached non-white ink so that the above-mentioned ratio of the amount of attached white coloring material is within the preferable range. It's okay.

Further, it is preferable that the maximum ink droplet mass of the white ink ejected from the recording head in the white ink adhesion step and the non-white ink adhesion step is twice or less than the maximum ink droplet mass of the non-white ink ejected. , more preferably 1 time or less, and even more preferably less than 1 time (making it smaller). Furthermore, it is preferably 0.8 times or less, more preferably 0.5 times or less. The lower limit is preferably 0.1 times or more, more preferably 0.3 times or more.

By doing so, the efficiency of mixing the white ink and the non-white ink can be further improved, and the difference in image quality within the plane of the obtained image can be further improved.

Here, the ink droplet mass is the mass of one ink droplet ejected from the recording head. Also called ink dot mass.

The difference between the maximum ink droplet mass of white ink and the maximum ink droplet mass of non-white ink (maximum ink droplet mass of white ink - maximum ink droplet mass of non-white ink) is preferably 10 ng or less, and 5 ng or less. It is more preferably 0 ng or less, even more preferably less than 0 ng, and particularly preferably -5 ng or less. Although not limited, the amount is preferably -30 ng or more, preferably -20 ng or more, and preferably -10 ng or more.

The maximum ink droplet mass of white ink and the maximum ink droplet mass of non-white ink in recording are each independently preferably 30 ng or less, more preferably 25 ng or less, even more preferably 20 ng or less, and even more preferably 15 ng or less. Preferably, 10 ng or less is particularly preferable. Further, the maximum ink drop mass is independently preferably 3 ng or more, more preferably 5 ng or more, even more preferably 10 ng or more, particularly preferably 15 ng or more, and may be 20 ng or more.

As mentioned above, the white ink adhesion process and the non-white ink adhesion process are performed in one scan, but the white ink and the non-white ink land on the same location in the same area during one scan. Although the timing may be different, the time difference is very small. However, the order in which the white ink and the non-white ink land on the same location in the same region during one scan is not particularly limited.

When performing the printing method of this embodiment, as in an inkjet printing apparatus described later, the scanning of the printing head (main scanning) and the relative position of the printing head and the printing medium in the direction crossing the scanning direction are performed. Recording may be performed by repeatedly performing the sub-scanning and the sub-scanning. Recording may be performed by repeating alternately. Furthermore, in the sub-scanning after the main scanning, the recording head may be moved by a length shorter than the length of the nozzle row in the sub-scanning direction, and the area scanned in the previous main scanning may be scanned in the next main scanning. . In this case, ink is further deposited in another scan to an area where ink is deposited by the nozzle array of the recording head in one scan. In other words, the area of the print medium where the nozzle array of the print head faced in one scan is further opposed by the nozzle row of the print head in another scan.

The sub-scanning may be performed by moving the print medium relative to the print head, or may be performed by moving the print head relative to the print medium.

In this way, in printing, for each scanning area of the printing medium where ink is deposited in one scan of the print head, there may be an area where the ink is deposited in another scan. In other words, there may be an area where the same area is scanned two or more times. Note that the number of times the same area is scanned is referred to as the number of scans (number of scans, number of passes).

The number obtained by dividing the length of the print head in the sub-scanning direction by the distance of one sub-scan of the print medium in the sub-scanning direction corresponds to the number of scans. The number of scans is per ink. The number of scans is 1 or more, preferably 2 or more, and more preferably 4 or more. Although not limited, it is preferably 20 or less, more preferably 15 or less, and even more preferably 10 or less. When the number of scans is greater than or equal to the above range, the reduction in density unevenness and the reduction in image quality difference are better, which is preferable. When the number of scans is within the above range, the printing speed is better and it is preferable.

In the printing method of this embodiment, when scanning as described above, one main scan is performed by appropriately arranging the nozzles for ejecting white ink and the nozzles for ejecting non-white ink of the print head and controlling the ejection. In the recording area of the recording medium, an area where the white ink landed first and an area where the non-white ink landed first can be formed.

In this way, the mixing of white ink and non-white ink in the image may be further improved, and the difference in visibility between the front and back sides of the image can be reduced (see the description of the embodiment for details). .

Conventionally, when recording a non-white ink layer and a white ink layer on a transparent recording medium by overlapping them at the same location by separate scanning, a white ink layer was added to improve the visibility of the non-white ink layer. In contrast, when increasing the background hiding property of the non-white ink layer, the visibility of the non-white ink image from the white ink layer side sometimes worsened. However, image visibility is excellent.

1.6. Other Steps The recording method of this embodiment includes the steps of attaching white ink and non-white ink to the recording medium, respectively. However, if necessary, the method may further include a step of attaching one or more types of other white ink and other non-white ink to the recording medium. In this case, the order and number of these steps are not limited and can be performed as appropriate. Furthermore, the recording method of this embodiment may include a step of heating the recording medium (post-heating step).

2. Inkjet Recording Apparatus The inkjet recording apparatus of this embodiment includes a conveying means for conveying a recording medium, and a recording head for ejecting white ink containing a white coloring material and non-white ink containing a non-white coloring material to adhere to the recording medium. , a scanning means for scanning the recording head with respect to the recording medium, and a control section for controlling the conveying means, the recording head, and the scanning means.

Hereinafter, an example of an inkjet recording apparatus that can carry out the recording method according to the present embodiment will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view schematically showing an inkjet recording apparatus. FIG. 2 is a perspective view showing an example of the structure around the carriage of the inkjet recording apparatus 1 shown in FIG. As shown in FIGS. 1 and 2, the inkjet recording apparatus 1 includes a recording head 2, an IR heater 3, a platen heater 4, a heating heater 5, a cooling fan 6, a preheater 7, a blower fan 8, It includes a carriage 9, a platen 11, a carriage moving mechanism 13, a conveyance means 14, and a control unit CONT. In the inkjet recording apparatus 1, the operation of the entire inkjet recording apparatus 1 is controlled by the control unit CONT shown in FIG.

The recording head 2 is configured to perform recording on the recording medium M by ejecting white ink and non-white ink from the nozzles of the recording head 2 and depositing them. In this embodiment, the recording head 2 is a serial type recording head, and scans the recording medium M multiple times in the main scanning direction relative to the recording medium M to deposit white ink and non-white ink on the recording medium M. . The recording head 2 is mounted on a carriage 9 shown in FIG. The recording head 2 is scanned multiple times in the main scanning direction relative to the recording medium M by the operation of the carriage moving mechanism 13 that moves the carriage 9 in the width direction of the recording medium M. The medium width direction is the main scanning direction of the recording head 2. Scanning in the main scanning direction is also referred to as main scanning.

Further, here, the main scanning direction is the direction in which the carriage 9 carrying the recording head 2 moves. In FIG. 1, this is a direction that intersects with the sub-scanning direction, which is the conveyance direction of the recording medium M, as indicated by an arrow SS. In FIG. 2, the width direction of the recording medium M, that is, the direction represented by S1-S2 is the main scanning direction MS, and the direction represented by T1→T2 is the sub-scanning direction SS. Note that in one scan, scanning is performed in the main scanning direction, that is, in either direction of arrow S1 or arrow S2. Then, by repeating the main scan of the print head 2 and the sub-scan, which is the conveyance of the print medium M, multiple times, the print medium M is printed.

The cartridge 12 that supplies white ink and non-white ink to the recording head 2 includes a plurality of independent cartridges. The cartridge 12 is removably attached to the carriage 9 on which the recording head 2 is mounted. Each of the plurality of cartridges is filled with non-white ink or white ink, and the white ink or non-white ink is supplied from the cartridge 12 to each nozzle. Although the present embodiment shows an example in which the cartridge 12 is mounted on the carriage 9, the cartridge 12 is not limited to this, and is provided at a location other than the carriage 9, and is connected to each nozzle by a supply pipe (not shown). It may also be in a supplied form. Furthermore, the nozzles for ejecting white ink and the nozzles for ejecting non-white ink can be appropriately designed together with the arrangement of the cartridge 12.

A conventionally known method can be used for ejection from the recording head 2. This embodiment uses a method of ejecting droplets using the vibration of a piezoelectric element, that is, an ejection method of forming ink droplets by mechanical deformation of an electrostrictive element.

The inkjet recording apparatus 1 includes an IR heater 3 and a platen heater 4 for heating the recording medium M when ink or non-white ink is ejected from the recording head 2. In this embodiment, when drying the recording medium M in the drying process, a drying mechanism such as an IR heater 3, a blower fan 8, a platen heater 4, a preheater 7, etc. can be used. The drying process performed on the ink adhered to the recording medium during ink adhesion is also referred to as a primary drying process.

Note that when the IR heater 3 is used, the recording medium M can be heated in a radiant manner by infrared radiation from the recording head 2 side. As a result, although the recording head 2 is likely to be heated at the same time, the temperature can be increased without being affected by the thickness of the recording medium M, compared to a case where the recording medium M is heated from the back side of the recording medium M using a platen heater 4 or the like. Further, various types of fans (for example, the blower fan 8) may be provided to dry the ink and non-white ink on the recording medium M by blowing warm air or air at the same temperature as the environment onto the recording medium M.

The platen heater 4 heats the recording medium M at a position facing the recording head 2 so that the non-white ink or white ink ejected by the recording head 2 can be quickly dried from the time when it is attached to the recording medium M. , and can be heated via the platen 11. The platen heater 4 is capable of heating the recording medium M in a conductive manner, and is used as necessary in the recording method of this embodiment as described above. It is preferable to control the temperature to .0°C or less.

In the ink adhesion step, the drying step of drying the ink adhering to the recording medium by the drying mechanism may not be provided, or the drying step may be performed at a relatively low temperature. In this case, the speed of drying of the ink adhering to the recording medium is suppressed, which improves filling and the like, which is preferable.

In the case where the recording medium M is dried by a drying mechanism or not dried during the ink adhesion step, the upper limit of the surface temperature of the recording medium M is preferably 45.0°C or less, and preferably 40.0°C or less. The temperature is more preferably 38.0°C or lower, even more preferably 35.0°C or lower, and particularly preferably 35.0°C or lower. Furthermore, the temperature is preferably 30°C or lower, preferably 28°C or lower, and preferably 25°C or lower. Further, the lower limit of the surface temperature of the recording medium M is preferably 20°C or higher, preferably 25.0°C or higher, more preferably 28.0°C or higher, and even more preferably 30.0°C or higher. Preferably, the temperature is particularly preferably 32.0°C or higher. Further, the temperature may be set so that the recording medium is not heated by the drying mechanism as described above, which is preferable.

When the temperature is below the above range, drying and compositional fluctuations of the white ink and non-white ink in the recording head 2 can be suppressed, and welding of resin particles and the like to the inner wall of the recording head 2 can be suppressed. It is also preferable because it has better filling, color development, image quality difference, etc. Further, when the temperature is above the above range, white ink and non-white ink can be fixed on the recording medium M at an early stage, and image quality can be improved. Note that the above temperature is the highest temperature at a location on the surface of the recording medium facing the recording head during the ink adhesion process.

The heating heater 5 is a heater for drying and solidifying the ink attached to the recording medium M, that is, for secondary heating or secondary drying. The heater 5 can be used in the post-heating process. When the heating heater 5 heats the recording medium M on which an image is recorded, water contained in the ink is more quickly evaporated and scattered, and an ink film is formed by the resin contained in the ink. In this way, the ink film is firmly fixed or adhered onto the recording medium M, resulting in excellent film-forming properties, and an excellent high-quality image can be obtained in a short time. The upper limit of the surface temperature of the recording medium M by the heating heater 5 is preferably 120.0°C or less, more preferably 100.0°C or less, and even more preferably 90.0°C or less. Further, the lower limit of the surface temperature of the recording medium M is preferably 60.0°C or higher, more preferably 70.0°C or higher, and even more preferably 80.0°C or higher. When the temperature is within the above range, high quality images can be obtained in a short time. Note that the above temperature is the maximum temperature of the portion of the recording medium that undergoes secondary heating during recording.

The inkjet recording apparatus 1 may include a cooling fan 6. After drying the ink recorded on the recording medium M, by cooling the ink on the recording medium M with the cooling fan 6, an ink coating film can be formed on the recording medium M with good adhesion.

Further, the inkjet recording apparatus 1 may include a preheater 7 that heats the recording medium M in advance before the ink is attached to the recording medium M.

Below the carriage 9 are a platen 11 that supports the recording medium M, a carriage movement mechanism 13 that moves the carriage 9 relative to the recording medium M, and a roller that conveys the recording medium M in the sub-scanning direction. A conveyance means 14 is provided. The operations of the carriage moving mechanism 13 and the conveyance means 14 are controlled by a control unit CONT.

FIG. 3 is a functional block diagram of the inkjet recording apparatus 1. The control unit CONT is a control unit for controlling the inkjet recording apparatus 1. The interface unit 101 (I/F) is for transmitting and receiving data between the computer 130 (COMP) and the inkjet recording apparatus 1. The CPU 102 is an arithmetic processing unit for controlling the entire inkjet recording apparatus 1 . The memory 103 (MEM) is for securing an area for storing programs for the CPU 102, a work area, and the like. The CPU 102 controls each unit by a unit control circuit 104 (UCTRL). Note that the detector group 121 (DS) monitors the situation inside the inkjet recording apparatus 1, and the control unit CONT controls each unit based on the detection result.

The conveyance unit 111 (CONVU) controls sub-scanning (conveyance means) of inkjet recording, and specifically controls the conveyance direction and conveyance speed of the recording medium M. Specifically, the conveyance direction and conveyance speed of the recording medium M are controlled by controlling the rotation direction and rotation speed of a conveyance roller driven by a motor.

The carriage unit 112 (CARU) controls the main scanning (pass) (scanning means) of inkjet recording, and specifically moves the recording head 2 back and forth in the main scanning direction. The carriage unit 112 includes a carriage 9 on which the recording head 2 is mounted, and a carriage movement mechanism 13 for reciprocating the carriage 9.

The head unit 113 (HU) controls the amount of white ink or non-white ink ejected from the nozzles of the recording head 2 . For example, if the nozzles of the recording head 2 are driven by piezoelectric elements, the operation of the piezoelectric elements in each nozzle is controlled. The head unit 113 controls the timing of adhesion of each ink, dot size, mass, etc. of white ink and non-white ink. Furthermore, the amount of non-white ink and white ink deposited per scan is controlled by a combination of controls of the carriage unit 112 and head unit 113.

The drying unit 114 (DU) controls the temperatures of various heaters such as the IR heater 3, preheater 7, platen heater 4, and heating heater 5.

The inkjet recording apparatus 1 described above alternately repeats an operation of moving the carriage 9 on which the recording head 2 is mounted in the main scanning direction (main scanning) and a conveying operation (sub-scanning). At this time, when performing each pass, the control unit CONT controls the carriage unit 112 to move the print head 2 in the main scanning direction, and also controls the head unit 113 to move a predetermined nozzle of the print head 2. Droplets of white ink or non-white ink are ejected from the holes, and the droplets of white ink or non-white ink are attached to the recording medium M. Further, the control unit CONT controls the transport unit 111 to transport the recording medium M in the transport direction by a predetermined transport amount (feed amount) during the transport operation.

In the recording method of this embodiment, the control unit CONT causes white ink and non-white ink to adhere to the same area of the recording medium M by the same scanning by the scanning means, and to apply the white ink and the non-white ink to the same area of the recording medium , control the deposition so that the mass ratio (A/B) of the amount A of white coloring material deposited and the amount B of non-white coloring material deposited per unit area is 0.03 or more and 0.99 or less. .

In the inkjet recording apparatus 1, a recording area to which a plurality of droplets (dots) are attached is gradually conveyed by repeating main scanning (pass) and sub-scanning (conveyance operation). Then, the droplets attached to the recording medium M are dried by the heater 5, and an image is completed. Thereafter, the completed recorded matter may be wound into a roll by a winding mechanism (not shown) or transported by a flatbed mechanism (not shown).

According to such an inkjet recording apparatus, an image can be recorded on a recording medium while mixing white ink and non-white ink. Thereby, an image with good visibility can be obtained. In addition, the visibility of the obtained image is good on both the front and back sides. For example, when recording is performed on the front side of a transparent recording medium, the visibility from the back side of the recording medium can also be good. . Furthermore, since white ink and non-white ink can be deposited in the same scan, the recording speed can be improved.

The printing device can be a serial printing device that performs main scanning and sub-scanning, as in the above example. On the other hand, as shown in FIG. 1, the printing apparatus is a line-type printing apparatus in which the printing head 2 has a length longer than the printing width of the printing medium, and prints by one scan while transporting the printing medium. Also good.

3. Examples Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples. Hereinafter, "parts" and "%" are based on mass unless otherwise specified. Note that unless otherwise specified, the evaluation was performed under an environment of a temperature of 25.0° C. and a relative humidity of 40.0%.

3.1. Preparation of ink Put each component into a container so that it has the composition shown in Table 1, mix and stir with a magnetic stirrer for 2 hours, and then perform a dispersion treatment using a bead mill filled with zirconia beads with a diameter of 0.3 mm. Thoroughly mixed. After stirring for 1 hour, the mixture was filtered using a 5.0 μm PTFE membrane filter to obtain non-white ink Bk1, non-white ink C1, white ink W1, and white ink W2. The numerical values in Table 1 indicate mass %. Ion-exchanged water was used as water, and added so that the mass of each ink was 100% by mass.

Among the components shown in Table 1, carbon black is No. 33 (manufactured by Mitsubishi Chemical Corporation) was used. "P.B.15:3" means C.B.15:3. I. Pigment Blue 15:3 is shown. As titanium dioxide, Taipei CR-50-2 (manufactured by Ishihara Sangyo Co., Ltd.) was used. "Joncryl (registered trademark) 537J" is a resin particle (acrylic resin) obtained from BASF Japan Co., Ltd. "SAG503A" is a silicone surfactant obtained from Nissin Chemical Industry Co., Ltd.

The pigment is prepared by mixing a pigment dispersant, which is a styrene-acrylic water-soluble resin not listed in the table, and the pigment in water in advance at a mass ratio of pigment:pigment dispersant = 2:1 and stirring. A pigment dispersion was prepared, which was used to prepare an ink.

3.2. Recording Test The inkjet recording device used was a modified SC-S80650 manufactured by Seiko Epson Corporation. The recording head had a nozzle array arrangement as shown in FIG. The nozzle density per nozzle row was 600 npi, and the number of nozzles was 600. The recording device was configured as shown in FIGS. 1 and 2.

The number of passes (number of scans) per ink was set to the values shown in Tables 2 and 3. In other words, the length of one sub-scan is approximately the length of the nozzle row/number of passes. This is the number of passes required to record on a certain portion of the recording medium. For example, in the case of two-pass printing, the length of one sub-scanning was set to about half the length of the nozzle row, and printing was performed on a certain portion of the printing medium in two passes. In the ink adhesion process, no drying mechanism was used, and the recording medium surface temperature in the ink adhesion process was set at 25°C.

Lumirror S10 (manufactured by TOREY, PET sheet) was used as the recording medium.

The final adhesion amount of white ink and non-white ink per unit area in the recording pattern is set to the values shown in the table, and the dots are evenly thinned out for each pass so that the adhesion amount for each pass is approximately equal. was recorded. The recording resolution per ink was 600 x 600 dpi. Tables 2 and 3 list the ink mass per dot (ink droplet). After recording, it was discharged from the inkjet recording apparatus and left at room temperature for one day.

In addition, the table shows the types of white ink and non-white ink used in each example, the amount of adhesion of white ink and non-white ink, the amount of adhesion of white coloring material and non-white coloring material, and the mass ratio of the amount of adhesion of coloring material. (A/B) (white/non-white), the mass of ink droplets (dot mass), and the number of passes when recording was performed per specific recording area were listed.

As shown in FIG. 4, the five nozzle rows of the recording head are numbered N1 to N5. In the table, "simultaneously" in the "white ink deposition method" column indicates that white ink and non-white ink were deposited on the recording medium in one pass (scanning).

In the table, in the column "White ink row arrangement", "left end" indicates that N1 is filled with white ink, N2 is filled with non-white (Bk) ink, and N3 is filled with non-white (C) ink. show. In this case, the recording head reciprocated in the main scanning direction to perform bidirectional printing, and the landing order of white ink and non-white ink was alternately changed for each pass (scan).

In the table, in the column "White ink row arrangement", "center" means that N3 is filled with white ink, N2 and N4 are filled with non-white (Bk) ink, and N1 and N5 are filled with non-white (C) ink. Show that. In this case, the recording head reciprocates in the main scanning direction to perform bidirectional printing, and for non-white ink, N1 and N2 or N4 and N5 are used alternately for each pass. The landing order of ink and non-white ink was made to be the same between passes.

In the table, in the "White ink row arrangement" column, "Both ends" indicates that N2 is filled with non-white (Bk) ink, N3 is filled with non-white (C) ink, and N1 and N4 are filled with white ink. show. In this case, the recording head reciprocates in the main scanning direction to perform bidirectional printing, and for white ink, N1 or N4 is used alternately in each pass, and in every pass, white ink and non-white ink are The order of impact is now the same between passes.

In addition, in the table, in the column of "White ink deposition method", "Pre-dosing" means that the nozzle row is filled with ink in the same way as in the "leftmost" example, but only white ink is used. After the pattern was recorded, the recording medium was rewound and a non-white pattern was recorded over the white pattern. That is, the case is shown in which white ink and non-white ink are not deposited in the same scan.

3.3. Evaluation method 3.3.1. Printing speed The table shows the results of evaluation based on the following criteria based on the number of passes required to record on a certain part of the recording medium.
S: Within 2 passes A: Within 4 passes B: Within 6 passes C: More than 6 passes

3.3.2. Evaluation of filling (image quality)
A pattern in which Bk1 and W1 or W2 were mixed was recorded on a recording medium. The degree of color fading in the color pattern of the printed matter (shielding property since it is a transparent recording medium) was visually confirmed. For color loss, we focused on whether or not the image could be seen through. The results of evaluation based on the following criteria are listed in the table. In addition,
In the pre-printing example, color loss occurs when the non-white image recorded with non-white ink shows through when viewed from the side of the non-white image recorded with non-white ink, and the white image underneath the non-white image is visible. We focused on whether or not
S: The ink spreads sufficiently, and color loss cannot be confirmed visually or with a magnifying glass. A: The ink spreads well, and color loss cannot be confirmed visually. B: The ink spreads insufficiently, and the color is slightly visible. C: Ink spread is insufficient, and color loss is visible and noticeable.

3.3.3. Color development evaluation (visibility)
On the recording medium, print a pattern in which a solid printed area of C1 and W1 or W2 and a solid printed area of Bk1 and W1 or W2 are brought into contact at the edge boundary of the area, and paste it on black paper. After that, the ease of identifying the boundaries was visually confirmed. The results of evaluation based on the following criteria are listed in the table. This is an evaluation of visibility.
S: No whitishness is seen and the border can be easily identified. A: No whitishness is seen and the border can be identified. B: No whitishness is seen and the border can be easily identified. The boundary can be identified by observation. C: It is difficult to identify the boundary, or the boundary can be identified but the image is whitish.
Z: The boundary can be easily identified when viewed from the non-white image side. However, if a printed record is pasted onto black paper with the back side (white image side) facing up, the boundaries cannot be identified.

3.3.4. Evaluation of density unevenness (image quality)
A pattern in which Bk1 and W1 or W2 were attached was recorded on the media. The density uniformity (density unevenness) of the printed matter was visually confirmed. The results of evaluation based on the following criteria are listed in the table.
S: A uniform image with no density unevenness A: A good image with no density unevenness B: An image with no density unevenness C: Nonuniform density unevenness was visually confirmed

3.3.5. Evaluation of in-plane image quality difference (image quality)
A pattern in which Bk1 and W1 or W2 were deposited was recorded on a recording medium. Visual evaluation was performed when observing from a distance of 30 cm from the recording surface and when observing from a distance of 1 m. It was evaluated whether parts of different colors were visible depending on the location within the pattern (in-plane) on the recording surface side. The results of evaluation based on the following criteria are listed in the table.
S: Cannot distinguish between different parts at a distance of 30 cm A: There are different parts at a distance of 30 cm but cannot distinguish between them at a distance of 1 m B: Different parts can be distinguished at a distance of 1 m C: Different parts can be distinguished at a distance of 1 m The area appears streaky.

3.3.6. Evaluation of front and back image quality differences (image quality)
A pattern in which Bk1 and W1 or W2 were deposited was recorded on a recording medium. Visual evaluation was performed when observed from a distance of 30 cm from the surface of the recorded portion or from the recording medium side, and when observed from a distance of 1 m. I looked at it from both the front and back to see if it looked different between the front and back. The results of evaluation based on the following criteria are listed in the table.
S: You cannot tell the difference between the front and back sides at a distance of 30cm. A: You can tell the difference between the front and back sides at a distance of 30cm, but you cannot tell the difference at a distance of 1m. B: You can tell the difference between the front and back sides at a distance of 1m. C: You can tell the difference between the front and back sides at a distance of 1m. The difference between the front and back is obvious depending on the distance, and one side is white.

3.4. Evaluation results A white ink adhesion process and a non-white ink adhesion process were performed, and these processes were performed on the same area of the non-white recording medium with the same scan, and the white ink and non-white ink were applied. In the example in which the mass ratio (A/B) of the amount A of the white coloring material adhered to the amount B of the non-white coloring material adhered per unit area is 0.03 or more and 0.99 or less, Excellent filling and color development.

On the other hand, all of the other comparative examples were inferior in either filling or color development.

From Examples 1 to 3, the smaller the white/non-white coloring material deposition amount ratio, the better the density unevenness and image quality difference, and the larger the ratio, the better filling.

From Examples 1, 4, and 5, the smaller the mass of the white ink droplets, the better the filling, the reduction of density unevenness, and the reduction of image quality differences.

From Examples 1, 6, and 7, it is better to prevent the landing order of white ink and non-white ink from changing between passes, since it is better to reduce the in-plane image quality difference. It was better to reduce the difference in image quality between the front and back sides.

From Examples 1, 8, and 10, the larger the number of passes, the better the reduction of density unevenness and the reduction of image quality difference, and the smaller the number of passes, the better the printing speed.

From Examples 1 and 9, the smaller the content of the coloring material in the white ink, the better the reduction in filling and image quality difference, and the larger the content, the better in reducing density unevenness.

In Comparative Example 1, recording was performed using only non-white ink without using white ink, with the same ink row arrangement as at the left end. From Comparative Examples 1 and 3, when no white ink was used or when the ratio of the amount of white coloring material deposited was too small, filling and visibility were poor.

From Comparative Example 2, when the ratio of the amount of white coloring material deposited was too large, visibility was poor.

In Reference Examples 1 and 2, when viewing the non-white image, the white image below the non-white image was visible, and the filling of the non-white image was poor. The visibility when viewed from the non-white image side was not inferior. Note that when compared with simultaneous printing where the number of scans per ink is the same, twice the number of scans is required.

Although not listed in the table, when the same procedure was performed as in Example 1 with the surface temperature of the recording medium set to 40°C by operating the platen heater in the ink adhesion process, the filling and image quality differences were slightly inferior. Ta. From this, it was found that it is preferable that the surface temperature of the recording medium in the ink adhesion step is lower.

In addition, when recording was carried out in the same manner as in Example 1 using the above-mentioned PET sheet that had been colored brown in advance to make it opaque, the same excellent filling and visibility were obtained. Ta.

The embodiments and modifications described above are just examples, and the present invention is not limited thereto. For example, it is also possible to combine each embodiment and each modification as appropriate.

The present invention includes a configuration that is substantially the same as the configuration described in the embodiments, for example, a configuration that has the same function, method, and result, or a configuration that has the same purpose and effect. Further, the present invention includes a configuration in which non-essential parts of the configuration described in the embodiments are replaced. Further, the present invention includes a configuration that has the same effects or a configuration that can achieve the same objective as the configuration described in the embodiment. Further, the present invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

The following contents are derived from the above-described embodiment and modification.

One aspect of the recording method is
A recording method for recording on a recording medium,
The recording medium is a non-white recording medium,
a white ink adhering step of adhering a white ink containing a white coloring material to the recording medium;
a non-white ink adhering step of adhering a non-white ink containing a non-white coloring material to the recording medium,
The white ink adhesion step and the non-white ink adhesion step are performed by scanning the recording head with respect to the recording medium,
The white ink adhesion step and the non-white ink adhesion step are performed on the same area of the recording medium in the same scan,
In the area to which the white ink and the non-white ink are deposited by the white ink deposition step and the non-white ink deposition step, the amount A of the white coloring material deposited and the amount of the non-white coloring material per unit area are determined. The mass ratio (A/B) of the adhesion amount B is 0.03 or more and 0.99 or less.

According to this recording method, an image can be recorded on a recording medium while mixing white ink and non-white ink. As a result, an image with good visibility and high quality can be obtained. Excellent filling. Furthermore, the image quality of the obtained image is good on both the front and back sides, and for example, when recording is performed on the front side of a transparent recording medium, visibility from the back side of the recording medium can also be good. Furthermore, since white ink and non-white ink can be deposited in the same scan, the recording speed can be improved.

In the aspect of the recording method,
The recording head may be an inkjet head, and the white ink adhesion step and the non-white ink adhesion step may be performed by ejecting the white ink and the non-white ink from the inkjet head.

According to this recording method, it is possible to efficiently perform printing in small quantities and in many types using a small device.

In the aspect of the recording method,
A maximum ink drop mass of the white ink ejected from the inkjet head may be smaller than a maximum ink drop mass of the non-white ink ejected.

According to this recording method, the efficiency of mixing white ink and non-white ink is further improved, and the difference in in-plane image quality of the obtained image can be further improved.

In the aspect of the recording method,
Printing may be performed by repeatedly performing the scanning and a sub-scanning that changes the relative position of the printing head and the printing medium in a direction intersecting the scanning direction.

According to this recording method, white ink and non-white ink can be mixed more efficiently.

In the aspect of the recording method,
In the area to which the white ink and the non-white ink are attached, the mass ratio (A/B) is 0.03 or more and 0. It may be .99 or less.

According to this recording method, white ink and non-white ink can be mixed more efficiently, and an image with better visibility can be formed.

In the aspect of the recording method,
The white ink and the non-white ink may each be applied to a scanning area of the recording medium that is scanned by one scan of the recording head by two or more scans.

According to this recording method, the landing order of the white ink and the non-white ink can be made different, and the mixing of the white ink and the non-white ink in the image may be further improved, and the visibility on the front and back sides of the image may be improved. The difference can be made smaller.

In the aspect of the recording method,
The content of the white coloring material in the white ink may be 1.0% by mass or more and 20.0% by mass or less.

According to this recording method, since the content of the white coloring material in the white ink can be suppressed, the sedimentation recovery property of the white ink can be improved. Furthermore, since the white ink has a low white coloring material concentration, mixing with non-white ink proceeds more efficiently.

In the aspect of the recording method,
The white ink and the non-white ink may each be water-based inks.

According to this recording method, it is possible to perform recording with less odor and the like with a reduced environmental load.

In the aspect of the recording method,
The white ink and the non-white ink may each contain an organic solvent having a standard boiling point of 150.0°C or more and 280.0°C or less.

According to this recording method, it is possible to perform recording in which images are fixed more quickly.

In the aspect of the recording method,
The white ink and the non-white ink each do not need to contain more than 1.0% by mass of an organic solvent having a standard boiling point of more than 280.0.

According to this recording method, it is possible to perform recording in which the image dries more quickly.

In the aspect of the recording method,
The non-white recording medium may be a low-absorption or non-absorption recording medium.

According to this recording method, an image with good filling can be formed more easily.

In the aspect of the recording method,
The non-white recording medium may be either a transparent recording medium or a non-white colored recording medium.

According to this recording method, images with good image quality can be formed more easily.

One aspect of the inkjet recording device is
a conveyance means for conveying the recording medium;
a recording head that ejects white ink containing a white coloring material and non-white ink containing a non-white coloring material to adhere to the recording medium;
scanning means for scanning the recording head with respect to the recording medium;
a control unit that controls the conveyance means, the recording head, and the scanning means;
has
The control section,
The white ink and the non-white ink,
deposited on the same area of the recording medium by the same scanning by the scanning means,
In the same area, the mass ratio (A/B) of the adhesion amount A of the white coloring material and the adhesion amount B of the non-white coloring material per unit area is 0.03 or more and 0.99 or less. Attach to.

According to this inkjet recording apparatus, an image can be recorded on a recording medium while mixing white ink and non-white ink. Thereby, an image with good visibility can be obtained. In addition, the visibility of the obtained image is good on both the front and back sides. For example, when recording is performed on the front side of a transparent recording medium, visibility from the back side of the recording medium can also be good. . Furthermore, since white ink and non-white ink can be deposited in the same scan, the recording speed can be improved.

DESCRIPTION OF SYMBOLS 1... Inkjet recording device, 2... Recording head, 2a... Nozzle surface, 3... IR heater, 4... Platen heater, 5... Heating heater, 6... Cooling fan, 7... Preheater, 8... Ventilation fan, 9... Carriage, DESCRIPTION OF SYMBOLS 11...Platen, 12...Cartridge, 13...Carriage moving mechanism, 14...Transportation means, 101...Interface part, 102...CPU, 103...Memory, 104...Unit control circuit, 111...Transportation unit, 112...Carriage unit, 113... Head unit, 114...Drying unit, 121...Detector group, 130...Computer, CONT...Control unit, MS...Main scanning direction, SS...Sub-scanning direction, M...Recording medium

Claims (15)

A recording method for recording on a recording medium,
The recording medium is a non-white recording medium,
a white ink adhesion step of adhering white ink containing a white coloring material to the recording medium;
a non-white ink adhering step of adhering a non-white ink containing a non-white coloring material to the recording medium,
The white ink and the non-white ink are each water-based ink,
The white ink adhesion step and the non-white ink adhesion step are performed by scanning the recording head with respect to the recording medium,
The white ink adhesion step and the non-white ink adhesion step are performed on the same area of the recording medium in the same scan,
In the area to which the white ink and the non-white ink are deposited by the white ink deposition step and the non-white ink deposition step, the amount A of the white coloring material deposited and the amount of the non-white coloring material per unit area are determined. The mass ratio (A/B) of the adhesion amount B is 0.03 or more and 0.03 or more over the area where the adhesion amount B of the non-white coloring material is maximum to 40% by mass of the maximum adhesion amount. A recording method that is .99 or less. In claim 1,
A recording method, wherein the recording head is an inkjet head, and the white ink attaching step and the non-white ink attaching step are performed by ejecting the white ink and the non-white ink from the inkjet head. In claim 2,
A recording method, wherein a maximum ink drop mass of the white ink ejected from the inkjet head is smaller than a maximum ink drop mass of the non-white ink ejected. In any one of claims 1 to 3,
A printing method in which printing is performed by repeatedly performing the scanning and a sub-scanning that changes the relative position of the printing head and the printing medium in a direction intersecting the scanning direction. In any one of claims 1 to 4,
In the area to which the white ink and the non-white ink are attached, the mass ratio (A/B) is 0.03 or more and 0. A recording method that is .99 or less. In any one of claims 1 to 5,
A recording method, wherein the white ink and the non-white ink are applied to a scanning area of the recording medium that is scanned in one scan of the recording head by two or more scans. In any one of claims 1 to 6,
A recording method, wherein the content of the white coloring material in the white ink is 1.0% by mass or more and 20.0% by mass or less. In any one of claims 1 to 7,
A recording method, wherein the white ink and the non-white ink each have a water content of 45% by mass or more based on the total amount of ink . In any one of claims 1 to 8,
A recording method, wherein the white ink and the non-white ink each contain an organic solvent having a standard boiling point of 150.0°C or more and 280.0°C or less. In any one of claims 1 to 9,
A recording method, wherein the white ink and the non-white ink each do not contain more than 1.0% by mass of an organic solvent having a standard boiling point of more than 280.0°C. In any one of claims 1 to 10,
A recording method, wherein the non-white recording medium is a low-absorption or non-absorption recording medium. In any one of claims 1 to 11,
The recording method, wherein the non-white recording medium is either a transparent recording medium or a non-white colored recording medium. In any one of claims 1 to 12,
The recording head has a portion where the nozzle array for ejecting the white ink and the nozzle array for ejecting the non-white ink overlap in a direction intersecting the scanning direction when projected in the scanning direction. ,Recording method. a conveyance means for conveying the recording medium;
a recording head that ejects white ink containing a white coloring material and non-white ink containing a non-white coloring material to adhere to the recording medium;
scanning means for scanning the recording head with respect to the recording medium;
a control unit that controls the conveyance means, the recording head, and the scanning means;
has
The white ink and the non-white ink are each water-based ink,
The control section,
The white ink and the non-white ink,
deposited on the same area of the recording medium by the same scanning by the scanning means,
In the same area, the mass ratio (A/B) of the adhesion amount A of the white coloring material and the adhesion amount B of the non-white coloring material per unit area is such that the adhesion amount B of the non-white coloring material is maximum. An inkjet recording device that deposits an amount of 0.03 or more and 0.99 or less over an area where the amount of adhesion is 40% by mass of the maximum amount of adhesion . In claim 14,
The recording head has a portion where the nozzle array for ejecting the white ink and the nozzle array for ejecting the non-white ink overlap in a direction intersecting the scanning direction when projected in the scanning direction. , inkjet recording device.

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