Recording method and inkjet recording apparatus

Abstract

To provide a recording method capable of suppressing light and shade unevenness, capable of imparting a recorded matter excellent in color development and abrasion resistance, and capable of intending to improve a printing speed.SOLUTION: A recording method for recording on a recording medium M comprises: a treatment liquid adhesion step for adhering a treatment liquid containing a coagulant on the recording medium; a white ink adhesion step for adhering a white ink composition containing a white colorant on the recording medium; a non-white ink adhesion step for adhering the non-white ink composition containing the non-white colorant on the recording medium, in which the adhesion of the white ink composition and the adhesion of the non-white ink composition are performed by relative scanning of a recording head 2 and the recording medium, and the adhesion of the white ink composition and the adhesion of the non-white ink composition are performed on the same relative scanning region of the recording medium by the same relative scanning.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a recording method and an inkjet recording apparatus. [Background technology]

[0002] In industrial and commercial applications, various printing processes are carried out on colored or transparent media, such as flexible packaging printing, label printing, signage printing, textile printing, and corrugated board printing, and images with excellent visibility are required.

[0003] For example, Patent Document 1 discloses an inkjet recording method in which a white ink is applied first, and then color inks are applied on the white ink. The document states that this allows the white image to become the background image, enabling recording with high visibility of color images. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-158884 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, for example, when printing on a non-white printing medium, the visibility of the color ink image is insufficient, and the filling of the color ink image is insufficient. [Means for solving the problem]

[0006] The present invention is a recording method for recording on a recording medium, comprising a treatment liquid application step of applying a treatment liquid containing a coagulant to the recording medium, a white ink application step of applying a white ink composition containing a white coloring material to the recording medium, and a non-white ink application step of applying a non-white ink composition containing a non-white coloring material to the recording medium, wherein the application of the white ink composition and the application of the non-white ink composition are performed by relative scanning of a recording head and the recording medium, and the application of the white ink composition and the application of the non-white ink composition are performed to the same scanned area of ​​the recording medium by the same relative scanning.

[0007] The present invention is a recording device that records on a recording medium, comprising a treatment liquid application mechanism that applies a treatment liquid containing a coagulant to the recording medium, a white ink head that applies a white ink composition containing a white colorant to the recording medium, a non-white ink head that applies a non-white ink composition containing a non-white colorant to the recording medium, and a scanning mechanism that performs relative scanning of the white ink head and the non-white ink head with the recording medium, and the recording device that records by the above-mentioned recording method. [Brief description of the drawings]

[0008] [Figure 1] 2 shows an example of a recording device used in this embodiment. [Diagram 2] 2 shows an example of the configuration of an inkjet head. [Diagram 3] 2 shows an example of the configuration of an inkjet head. [Figure 4] 2 shows an example of the configuration of an inkjet head. [Diagram 5] An example of the configuration of an inkjet head used in the examples and comparative examples will be shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings as necessary, but the present invention is not limited to this, and various modifications are possible without departing from the gist of the present invention. In the drawings, the same elements are given the same reference numerals, and duplicated explanations will be omitted. Furthermore, positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings, unless otherwise specified. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0010] 1. Recording method The recording method of the present embodiment is a method for recording on a recording medium, and includes a treatment liquid application step of applying a treatment liquid containing a coagulant to the recording medium, a white ink application step of applying a white ink composition containing a white coloring material to the recording medium, and a non-white ink application step of applying a non-white ink composition containing a non-white coloring material to the recording medium, in which the application of the white ink composition and the application of the non-white ink composition are performed by relative scanning of the recording head and the recording medium, and the application of the white ink composition and the application of the non-white ink composition are performed to the same scanned area of ​​the recording medium by the same relative scanning.

[0011] Conventionally, a high-quality image has been recorded by overlapping a white ink layer and a non-white ink layer and using the white ink layer as a concealing layer.

[0012] In contrast, in the present embodiment, the white ink composition and the non-white ink composition are deposited on the same scanning area of ​​the recording medium by the same relative scanning, which makes it possible to form a single ink layer containing the white ink composition and the non-white ink composition on the recording medium, and it has been found that an image with excellent color development without unevenness in shading can be formed even without forming a white ink layer and a non-white ink layer by overlapping them as in the conventional method.

[0013] In particular, when a white ink composition and a non-white ink composition are deposited on the same scanning area of ​​a recording medium by the same relative scan, the droplets of these ink compositions tend to mix on the recording medium, resulting in uneven shading. However, by using a treatment liquid, it is possible to suppress uneven shading and form an image with excellent color development.

[0014] From another viewpoint, in a conventional method of forming a white ink layer and a non-white ink layer by overlapping them using a treatment liquid, the treatment liquid is consumed by the ink composition that is applied first out of the white ink composition and the non-white ink composition, or the treatment liquid is absorbed into the recording medium, so that the treatment liquid does not act sufficiently on the ink composition that is applied later, which may result in a decrease in the color development of the ink.

[0015] In contrast, in the recording method of the present embodiment, the deposition of the white ink composition and the deposition of the non-white ink composition are performed in the same scanning area of ​​the recording medium by the same relative scanning, which makes it possible for the treatment liquid to act on both the white ink composition and the non-white ink composition, and also makes it possible to solve the conventional problems that occur before and after deposition.

[0016] Furthermore, in this embodiment, since there is no need to overlap a white ink layer and a non-white ink layer, it is possible to further improve the printing speed.

[0017] Furthermore, a head configuration can be used in which nozzles for ejecting a white ink composition and nozzles for ejecting a non-white ink composition are arranged side by side so that the deposition of the white ink composition and the deposition of the non-white ink composition are performed to the same scanning area of ​​the recording medium by the same relative scanning, which makes it possible to reduce the overall size of the inkjet head compared to a head configuration based on a conventional lamination.

[0018] 1.1. Adhesion of white ink composition and non-white ink composition Before describing each step, the deposition mode of the white ink composition and the non-white ink composition in this embodiment will be described. In the recording method of this embodiment, the deposition of the white ink composition and the non-white ink composition is performed by relative scanning of the recording head and the recording medium, and the deposition of the white ink composition and the deposition of the non-white ink composition are performed to the same scanned area of ​​the recording medium by the same relative scanning.

[0019] Here, the same relative scan means, for example, in the case of a serial type inkjet printing device, a single scan in which the printing head moves relatively in the main scanning direction intersecting the transport direction of the printing medium, and in the case of a line type inkjet printing device, a single scan in which a printing head of approximately the same length as the width of the printing medium moves relatively in the transport direction of the printing medium.

[0020] The scanning may be performed by moving the print head relative to the print medium, or the print medium may move relative to the print head. The scanning is performed while ejecting ink from the print head onto the print medium.

[0021] For example, in a serial type inkjet recording device, when the recording head scans the same area of ​​the recording medium back and forth in the main scanning direction multiple times, one of the forward or backward passes is counted as one scan. Therefore, when the white ink application process and the non-white ink application process are performed in the same relative scan, this means that both processes are performed during one scan of the recording head.

[0022] Moreover, depositing each ink composition on the same scanning region of the recording medium means depositing a white ink composition and a non-white ink composition in a region that passes by during the scanning, thereby forming a single ink layer containing the white ink composition and the non-white ink composition on the recording medium.

[0023] A white ink recording head and a non-white ink recording head perform scanning simultaneously. In this scanning (the same scan), the white ink composition and the non-white ink composition are deposited in the same scanning area. The scanned area in a scan is the area of ​​the recording medium scanned by the recording head in that scan. In the case of a serial type inkjet recording device, it is the part on the recording medium where the recording head moves relative to the recording medium in that scan.

[0024] The deposition of white ink and non-white ink in the same scanning area of ​​the recording medium by the same relative scan means that the scanning area by the white ink recording head and the scanning area by the white ink recording head have the same area (overlapping area) in the same scan. It is sufficient that they have at least a part of the same area.

[0025] The recording method of this embodiment can be performed in either a serial or line type manner, but is preferably performed in a serial type manner in which the white ink composition and the non-white ink composition are each applied to the scanning area by two or more scans. When a white ink layer and a non-white ink layer are formed by overlapping them as in the conventional serial type manner, a scan is performed to apply one ink first, and then a scan is performed to apply the other ink. In contrast, in this embodiment, the white ink composition and the non-white ink composition are applied by the same relative scan, so that the number of scans required for image formation can be halved and the printing speed can be doubled.

[0026] In particular, it may refer to the number of scans for a scanning area. For example, two or more scans are performed for a scanning area. For example, in the example of FIG. 2, if the length of one sub-scan in the sub-scan direction is one-fourth the length of the nozzle row N1 in the sub-scan direction, four scans are performed for a rectangular scanning area that is the length of one sub-scan in the sub-scan direction and extends in the main scanning direction. The number of scans viewed in this way is called the number of scans or the number of passes. The number of scans is 1 or more, preferably 2 or more, more preferably 3 or more, even more preferably 4 or more, and particularly preferably 8 or more. There is no upper limit, but 24 or less is preferable, and 12 or less is more preferable. The more the number of scans, the more times ink can be applied to the rectangular area, and the better the image quality is, which is preferable.

[0027] The white ink composition and the non-white ink composition used in this embodiment may be solvent-based inks or water-based inks, but are preferably water-based inks. Water-based inks are highly environmentally friendly in that they do not use organic solvents or contain a small amount of organic solvent compared to solvent-based inks. In addition, water-based inks tend to be mixed with white inks and non-white inks, which tends to cause a decrease in color development and uneven shading, and in particular, the resulting image tends to be whitish. For this reason, the present invention is particularly useful. Note that when referring to "water-based" inks and treatment liquids, the term "water-based" refers to inks that contain at least water as a main solvent component. The content of water in the ink, etc. is 40% by mass or more, and preferably 50% by mass or more.

[0028] 1.2. Treatment liquid application process The treatment liquid application step is a step of applying a treatment liquid containing an aggregating agent to a recording medium, in which, from the viewpoint of aggregating the components of the ink composition, the application area of ​​the treatment liquid is at least partially overlapped with the application area of ​​the white ink composition or the non-white ink composition.

[0029] The aggregating agent in the treatment liquid interacts with the components of the white ink composition and the non-white ink composition, causing the ink composition to thicken or become insoluble. This further suppresses unevenness in shading in the image formed by the subsequently deposited white ink composition and non-white ink composition, and further improves color development. Furthermore, the recording speed can be improved, and the abrasion resistance of the resulting recorded matter can also be improved.

[0030] Methods for applying the treatment liquid to the recording medium include application methods using a bar coater, a roll coater, a sprayer, etc., in addition to an inkjet method.

[0031] 1.2.1. Processing solution The treatment liquid contains a flocculant, and may contain water, a water-soluble organic solvent, and a surfactant, as necessary.

[0032] Flocculants The flocculant is not particularly limited, but examples thereof include polyvalent metal salts, organic acids, and cationic resins.

[0033] The polyvalent metal salt is not particularly limited, but may be, for example, a polyvalent metal salt of an inorganic acid or a polyvalent metal salt of an organic acid.The polyvalent metal is not particularly limited, but may be, for example, an alkaline earth metal of the second group of the periodic table (e.g., magnesium, calcium), a transition metal of the third group of the periodic table (e.g., lanthanum), an earth metal from the thirteenth group of the periodic table (e.g., aluminum), or a lanthanide (e.g., neodymium).As the salts of these polyvalent metals, carboxylates (formic acid, acetic acid, benzoate, etc.), sulfates, nitrates, chlorides, and thiocyanates are suitable.

[0034] Among these, calcium or magnesium salts of carboxylic acids (formic acid, acetic acid, benzoate, etc.), calcium or magnesium salts of sulfate, calcium or magnesium salts of nitric acid, calcium chloride, magnesium chloride, and calcium or magnesium salts of thiocyanate can be mentioned. The polyvalent metal salts may be used alone or in combination of two or more kinds.

[0035] The organic acid is not particularly limited, but examples thereof include acids having a carboxyl group, such as succinic acid, oxalic acid, malonic acid, citric acid, and acetic acid.

[0036] The cationic resin is not particularly limited, but examples thereof include amine-based resins such as amine-epichlorohydrin condensation polymers, polyallylamine, poly(vinylpyridine) salts, polyalkylaminoethyl acrylates, polyalkylaminoethyl methacrylates, poly(vinylimidazole), poly(glucosamine), polyethyleneimine, polybiguanide, polyhexymethylene guanide, and polyguanide; cationic urethane resins; and the like.

[0037] The content of the aggregating agent is preferably 1.0 to 20% by mass, more preferably 2.5 to 15% by mass, and even more preferably 5.0 to 10% by mass, based on the total amount of the treatment liquid. By having the content of the aggregating agent within the above range, unevenness in shading of the image formed by the white ink composition and the non-white ink composition is further suppressed, and color development is further improved. Furthermore, the recording speed can be improved, and the abrasion resistance of the resulting recorded matter can also be improved.

[0038] 1.2.1.2.Water The water content is preferably 50 to 80 mass %, more preferably 55 to 75 mass %, and further preferably 60 to 70 mass %, based on the total amount of the treatment liquid.

[0039] 1.1.1.3. Water-soluble organic solvents The water-soluble organic solvent is not particularly limited, and examples thereof include glycerin; glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether. Examples of the water-soluble organic solvent include glycol monoethers such as dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monomethyl ether, and triethylene glycol monobutyl ether; nitrogen-containing solvents such as 2-pyrrolidone, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone; and alcohols such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, 2-butanol, tert-butanol, iso-butanol, n-pentanol, 2-pentanol, 3-pentanol, and tert-pentanol. The water-soluble organic solvent may be used alone or in combination of two or more.

[0040] Among these, glycol solvents such as 1,2-hexanediol and propylene glycol, and nitrogen-containing solvents such as 2-pyrrolidone are preferred. By using such water-soluble organic solvents, the image quality and abrasion resistance of the resulting recorded matter tend to be improved, and the printing speed tends to be increased.

[0041] The content of the water-soluble organic solvent is preferably 10 to 40% by mass, more preferably 15 to 35% by mass, and even more preferably 20 to 30% by mass, based on the total amount of the treatment liquid. By having the content of the water-soluble organic solvent within the above range, the image quality and abrasion resistance of the obtained recorded matter tend to be improved, and the printing speed tends to be increased.

[0042] Surfactants The surfactant is not particularly limited, but examples thereof include acetylene glycol surfactants, fluorine-based surfactants, and silicone-based surfactants. Among these, silicone-based surfactants are preferred. This tends to further improve the wettability of the treatment liquid to the recording medium.

[0043] The acetylene glycol surfactant is not particularly limited, but for example, one or more selected from 2,4,7,9-tetramethyl-5-decyne-4,7-diol, alkylene oxide adducts of 2,4,7,9-tetramethyl-5-decyne-4,7-diol, and alkylene oxide adducts of 2,4-dimethyl-5-decyne-4-ol and alkylene oxide adducts of 2,4-dimethyl-5-decyne-4-ol are preferred.

[0044] The fluorine-based surfactant is not particularly limited, but examples thereof include perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkyl phosphate, perfluoroalkyl ethylene oxide adduct, perfluoroalkyl betaine, and perfluoroalkyl amine oxide compound.

[0045] Examples of silicone surfactants include polysiloxane compounds and polyether-modified organosiloxanes.

[0046] The content of the surfactant is preferably 0.1 to 4.0% by mass, more preferably 0.3 to 3.0% by mass, and even more preferably 0.5 to 2.0% by mass, relative to the total amount of the treatment liquid, which tends to further improve the wettability of the treatment liquid to the recording medium.

[0047] In the recording area where the white ink composition and the non-white ink composition are applied, the maximum amount of the treatment liquid applied is preferably 5 mg / inch 2 More preferably, it is 0.1 to 4 mg / inch. 2 and more preferably 0.3 to 3 mg / inch 2and even more preferably 0.5 to 1 mg / inch 2 When the amount of adhesion is within the above range, the color development of the resulting recorded matter tends to be improved.

[0048] 1.3. White ink application process The white ink application step is a step of applying a white ink composition containing a white coloring material to a recording medium. The white ink application step may be performed in any manner as long as the white ink composition is applied while scanning the recording head with respect to the recording medium.

[0049] For example, it is preferable that the recording head is an inkjet head, and in the white ink depositing step and the non-white ink depositing step, the white ink composition and the non-white ink composition are ejected from the inkjet head. In this way, a small amount of printing of many different types can be efficiently performed with a small device. In this case, since the white ink composition and the non-white ink composition are deposited by the same relative scanning, the inkjet head that ejects the white ink composition and the non-white ink composition is the same.

[0050] In addition, in the recording area where the white ink composition and the non-white ink composition are applied, it is preferable that the amount of the white ink composition applied is 100% by mass or less relative to 100% by mass of the non-white ink composition applied per unit area. The amount of the white ink composition applied is preferably 10 to 100% by mass, more preferably 20 to 90% by mass, more preferably 30 to 90% by mass, and even more preferably 40 to 80% by mass relative to 100% by mass of the non-white ink composition applied. Furthermore, 40 to 50% by mass is preferable. By setting the amount of the white ink composition applied to 100% by mass or less, the proportion of the non-white ink composition increases, and the color development of the obtained recorded matter tends to be further improved. The above percentages can also be expressed as an applied amount ratio. The applied amount ratio is the amount of the white ink composition applied / the non-white ink composition. When the amount of the white ink is 100% by mass relative to 100% by mass of the non-white ink, the applied amount ratio is 1.

[0051] The unit area is an area large enough to check the amount of ink applied, for example, an area of ​​1 x 1 mm.

[0052] In the recording area where the white ink composition and the non-white ink composition are applied, the maximum amount of the white ink composition applied is preferably 15 mg / inch 2 More preferably, it is 1 to 12 mg / inch. 2 and more preferably 3 to 10 mg / inch 2 and even more preferably 5 to 9 mg / inch 2 The maximum adhesion amount of the white ink composition is 15 mg / inch. 2 By satisfying the above condition, the color development of the obtained recorded matter tends to be further improved.

[0053] 1.3.1. White ink composition The white ink composition contains a white colorant, and may contain water, a water-soluble organic solvent, a surfactant, resin particles, and wax as necessary.

[0054] When the white ink composition is mixed with a 5% by mass aqueous solution of calcium acetate monohydrate, the viscosity increase ratio after mixing relative to the viscosity of the white ink composition before mixing is preferably at least 2 times, more preferably at least 2 to 5 times, and even more preferably 3 to 5 times. When the viscosity increase ratio is within the above range, uneven shading in the obtained recorded matter is further suppressed, and it becomes possible to form an image with excellent color development.

[0055] The viscosity increase ratio can be adjusted by changing the type and content of components contained in the ink, such as coloring materials and resins, that react with the treatment liquid.

[0056] The viscosity after mixing can be obtained by mixing 10 g of the white ink composition to 1 g of a 5% by mass aqueous solution of calcium acetate monohydrate, stirring for 10 seconds, and then immediately measuring the viscosity. The viscosity measurements before and after mixing and the above mixing process are all performed at room temperature of 25°C. An E-type viscometer is used, and the shear rate is 200 s -1 Let us assume that.

[0057] 1.3.1.1.White color material The white colorant is not particularly limited, and examples thereof include white inorganic pigments such as CI Pigment White 6, 18, 21, silica, alumina, titanium dioxide, zinc oxide, antimony oxide, magnesium oxide, zirconium oxide, zinc sulfide, barium sulfate, calcium carbonate, etc. In addition to the white inorganic pigments, white organic pigments such as white hollow resin particles and polymer particles can also be used.

[0058] Among the above-listed white coloring materials, titanium dioxide is preferably used as the white coloring material from the viewpoint of good whiteness and abrasion resistance. The white coloring material may be used alone or in combination of two or more kinds.

[0059] The content of the white colorant is preferably 0.5 to 20% by mass, more preferably 1.0 to 20% by mass, even more preferably 3.0 to 20% by mass, and particularly preferably 5.0 to 20% by mass, relative to the total amount of the white ink composition. When the content of the white colorant is within the above range, unevenness in shading of images formed with the white ink composition and non-white ink composition tends to be further suppressed, and color development tends to be further improved.

[0060] In this embodiment, the white ink composition is used not for the purpose of concealing the background of the image, but rather for the purpose of enhancing the visibility of the image obtained by using it in combination with a non-white ink composition. Therefore, the content of the white colorant in the white ink composition can be made smaller than when the purpose is to conceal the background. This makes it possible to obtain sufficient visibility of the image, and also makes it easier to improve the dispersion stability of the white colorant and make it less likely to settle. Furthermore, the filling and reduction of image quality differences are also more excellent and preferable.

[0061] The white colorant is preferably capable of being stably dispersed in the dispersion medium, and may be dispersed using a dispersant for this purpose. Examples of dispersants include resin dispersants, and are selected from those that can improve the dispersion stability of the white colorant in the white ink composition containing the white colorant. The white colorant may also be used as a self-dispersing pigment by modifying the surface of the pigment particles by oxidizing or sulfonating the pigment surface with, for example, ozone, hypochlorous acid, fuming sulfuric acid, or the like.

[0062] 1.3.1.2.Water The water content is preferably 50 to 75 mass %, more preferably 50 to 70 mass %, and even more preferably 55 to 65 mass %, relative to the total amount of the white ink composition.

[0063] 1.3.1.3. Water-soluble organic solvents Examples of the water-soluble organic solvent include the same ones as those exemplified in the above-mentioned treatment liquid. Among these, glycol-based solvents such as 1,2-hexanediol and propylene glycol, and nitrogen-containing solvents such as 2-pyrrolidone are preferred. By using such water-soluble organic solvents, the image quality and abrasion resistance of the obtained recorded matter tend to be improved, and the printing speed tends to be improved.

[0064] The content of the water-soluble organic solvent is preferably 10 to 40 mass %, more preferably 15 to 35 mass %, and even more preferably 20 to 30 mass %, relative to the total amount of the white ink composition. When the content of the water-soluble organic solvent is within the above range, the image quality and abrasion resistance of the obtained recorded matter tend to be improved, and the printing speed tends to be increased.

[0065] The water-soluble organic solvent preferably has a normal boiling point of 160 to 280° C. The content of glycol-based solvents in the ink having a normal boiling point of more than 280° C. is preferably 2% by mass or less, more preferably 1% by mass or less, and even more preferably 0.5% by mass or less, and may be 0% by mass. It is also preferable that the content of water-soluble organic solvents in the ink having a normal boiling point of more than 280° C. is within the above range.

[0066] Surfactants Examples of the surfactant include the same surfactants as those exemplified for the treatment liquid. Among these, silicone-based surfactants are preferred. This tends to further improve the wettability of the white ink composition to the recording medium.

[0067] The content of the surfactant is preferably 0.1 to 4.0% by mass, more preferably 0.3 to 3.0% by mass, and even more preferably 0.5 to 2.0% by mass, relative to the total amount of the white ink composition, which tends to further improve the wettability of the white ink composition to the recording medium.

[0068] 1.3.1.5.Resin particles By using resin particles, the adhesion of the obtained image is further improved. The resin particles are not particularly limited, but examples thereof include resin particles made of urethane resin, acrylic resin (including styrene-acrylic resin), fluorene resin, polyolefin resin, rosin-modified resin, terpene resin, polyester resin, polyamide resin, epoxy resin, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, ethylene vinyl acetate resin, etc. The resin particles may be in the form of an emulsion.

[0069] Among these, urethane resins, acrylic resins, and polyolefin 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. The resin particles may be used alone or in combination of two or more kinds.

[0070] The urethane resin is a general term for resins having a urethane bond. In addition to the urethane bond, the urethane resin may be a polyether urethane resin having an ether bond in the main chain, a polyester urethane resin having an ester bond in the main chain, or a polycarbonate urethane resin having a carbonate bond in the main chain.

[0071] Acrylic resin is a general term for polymers obtained by polymerizing at least an acrylic monomer such as (meth)acrylic acid or (meth)acrylic acid ester as one component, and examples thereof include resins obtained from acrylic monomers and copolymers of acrylic monomers and other monomers. Examples thereof include acrylic-vinyl resins, which are copolymers of acrylic monomers and vinyl monomers. Examples of vinyl monomers include styrene. Examples of acrylic monomers that can be used include acrylamide and acrylonitrile.

[0072] Among these, styrene-acrylic resins are preferred. The styrene-acrylic resins are not particularly limited, but examples thereof include styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid ester copolymers, styrene-α-methylstyrene-acrylic acid copolymers, and styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymers. By using such resins, the image quality and abrasion resistance of the resulting recorded matter tend to be further improved.

[0073] The polyolefin resin has an olefin such as ethylene, propylene, or butylene in its structural skeleton, and any known polyolefin resin can be appropriately selected and used.

[0074] The content of the resin particles is preferably 0.5 to 15 mass %, more preferably 1.0 to 10 mass %, and even more preferably 2.5 to 7.5 mass %, relative to the total amount of the white ink composition. When the content of the resin particles is within the above range, the abrasion resistance of the obtained recorded matter tends to be further improved.

[0075] Wax The wax has the function of imparting lubricity to the image formed by the white ink composition, and therefore can reduce peeling of the image formed by the white ink.

[0076] The wax is not particularly limited, but examples thereof include vegetable and animal waxes such as carnauba wax, candelilla 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; synthetic waxes such as carbon wax, Hoechst wax, polyolefin wax, and stearic acid amide; and natural and synthetic wax emulsions and blended waxes such as α-olefin-maleic anhydride copolymers. The waxes may be used alone or in combination of two or more. The waxes may be in the form of emulsions.

[0077] Among these, it is preferable to use polyolefin wax (particularly polyethylene wax and polypropylene wax) and paraffin wax. By using such wax, the abrasion resistance of the obtained recorded matter tends to be further improved.

[0078] The wax content is preferably 0.1 to 7.5 mass % relative to the total amount of the white ink composition, more preferably 0.3 to 5.0 mass %, and even more preferably 0.5 to 2.5 mass %. When the wax content is within the above range, the abrasion resistance of the resulting recorded matter tends to be further improved.

[0079] Other ingredients The white ink composition may further contain components such as preservatives, antifungals, rust inhibitors, chelating agents, viscosity adjusters, antioxidants, and antifungal agents, as necessary.

[0080] 1.4. Non-white ink application process The non-white ink applying step is a step of applying a non-white ink composition containing a non-white coloring material to a recording medium. The non-white ink applying step may be performed in any manner as long as the non-white ink composition is applied while scanning the recording head with respect to the recording medium. For example, the recording head may be an inkjet head, and the non-white ink composition may be ejected from the inkjet head.

[0081] As described above, the white ink composition and the non-white ink composition may be ejected from the same inkjet head.

[0082] In the recording area where the white ink composition and the non-white ink composition are applied, the maximum amount of the non-white ink composition applied is preferably 20 mg / inch 2 More preferably, it is 1 to 20 mg / inch 2 More preferably, it is 3 to 15 mg / inch. 2 and more preferably 5 to 12 mg / inch 2 When the maximum adhesion amount of the white ink composition is within the above range, the color development of the obtained recorded matter tends to be further improved.

[0083] 1.4.1. Non-white ink composition The non-white ink composition contains a non-white coloring material, and may contain water, a water-soluble organic solvent, a surfactant, resin particles, and wax as necessary. The components and composition of the non-white ink may be the same as those of the white ink, except for the non-white coloring material and other matters that are specifically mentioned.

[0084] When the non-white ink composition is mixed with a 5% by mass aqueous solution of calcium acetate monohydrate, the viscosity increase ratio after mixing relative to the viscosity of the non-white ink composition before mixing is preferably at least 2 times, more preferably at least 2 to 5 times, and even more preferably 3 to 5 times. When the viscosity increase ratio is within the above range, uneven shading in the obtained recorded matter is further suppressed, and it is possible to form an image with excellent color development.

[0085] The viscosity after mixing can be obtained by mixing 10 g of the non-white ink composition with 1 g of a 5% by mass aqueous solution of calcium acetate monohydrate, stirring for 10 seconds, and then immediately measuring the viscosity. The viscosity measurements before and after mixing and the above mixing process are all performed at room temperature of 25°C. An E-type viscometer is used, and the shear rate is 200 s -1 Let us assume that.

[0086] 1.4.1.1. Non-white colorants The non-white coloring material is not particularly limited as long as it is a coloring material other than the above-mentioned white coloring materials, but examples thereof include inorganic pigments such as furnace black, lamp black, acetylene black, channel black, and other carbon blacks (CI Pigment Black 7); quinacridone pigments, quinacridonequinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, anthanthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments, and organic pigments such as azo pigments. The non-white coloring material may be used alone or in combination of two or more kinds.

[0087] The content of the non-white coloring material is preferably 0.5 to 20 mass %, more preferably 0.5 to 15 mass %, and even more preferably 0.5 to 10 mass %, relative to the total amount of the non-white ink composition. When the content of the non-white coloring material is within the above range, unevenness in shading of the image formed by the white ink composition and the non-white ink composition tends to be further suppressed, and color development tends to be further improved.

[0088] It is preferable that the non-white colorant can be stably dispersed in the dispersion medium, and therefore a dispersant may be used for dispersion. Examples of dispersants include resin dispersants, and are selected from those that can improve the dispersion stability of the non-white colorant in the non-white ink composition containing the non-white colorant. In addition, the non-white colorant may be used as a self-dispersing pigment by modifying the surface of the pigment particles by oxidizing or sulfonating the pigment surface with, for example, ozone, hypochlorous acid, fuming sulfuric acid, or the like.

[0089] 1.4.1.2.Water The water content is preferably 50 to 75 mass %, more preferably 50 to 70 mass %, and even more preferably 55 to 65 mass %, relative to the total amount of the non-white ink composition.

[0090] 1.4.1.3. Water-soluble organic solvents Examples of the water-soluble organic solvent include the same ones as those exemplified in the above-mentioned treatment liquid. Among these, glycol-based solvents such as 1,2-hexanediol and propylene glycol, and nitrogen-containing solvents such as 2-pyrrolidone are preferred. By using such water-soluble organic solvents, the image quality and abrasion resistance of the obtained recorded matter tend to be improved, and the printing speed tends to be improved.

[0091] The content of the water-soluble organic solvent is preferably 10 to 40 mass %, more preferably 15 to 35 mass %, and even more preferably 20 to 30 mass %, relative to the total amount of the non-white ink composition. When the content of the water-soluble organic solvent is within the above range, the image quality and abrasion resistance of the obtained recorded matter tend to be improved, and the printing speed tends to be increased.

[0092] Surfactants Examples of the surfactant include the same surfactants as those exemplified for the treatment liquid. Among these, silicone-based surfactants are preferred. This tends to further improve the wettability of the non-white ink composition to the recording medium.

[0093] The content of the surfactant is preferably 0.1 to 4.0% by mass, more preferably 0.3 to 3.0% by mass, and even more preferably 0.5 to 2.0% by mass, relative to the total amount of the non-white ink composition, which tends to further improve the wettability of the white ink composition to the recording medium.

[0094] 1.4.1.5.Resin particles Examples of the resin particles include those exemplified in the white ink composition. Among these, styrene-acrylic resins are preferred. By using such resins, the image quality and abrasion resistance of the resulting recorded matter tend to be improved.

[0095] The content of the resin particles is preferably 0.5 to 15 mass %, more preferably 1.0 to 10 mass %, and even more preferably 2.5 to 7.5 mass %, relative to the total amount of the non-white ink composition. When the content of the resin particles is within the above range, the abrasion resistance of the obtained recorded matter tends to be further improved.

[0096] Wax Examples of the wax include those exemplified in the white ink composition. Among these, polyethylene wax is preferred. By using such a wax, the abrasion resistance of the resulting recorded matter tends to be further improved.

[0097] The wax content is preferably 0.1 to 7.5 mass % relative to the total amount of the non-white ink composition, more preferably 0.3 to 5.0 mass %, and even more preferably 0.5 to 2.5 mass %. If the wax content is within the above range, the abrasion resistance of the resulting recorded matter tends to be further improved.

[0098] Other ingredients The non-white ink composition may further contain components such as preservatives, antifungals, rust inhibitors, chelating agents, viscosity modifiers, antioxidants, and antifungal agents, as necessary.

[0099] 1.5.Clear ink application process The recording method of the present embodiment may further include a clear ink applying step of applying a clear ink composition. The clear ink is not for coloring the recording medium, but is an ink for improving the quality of the image, such as the abrasion resistance and gloss. The content of the coloring material in the clear ink is preferably 0.1% by mass or less, more preferably 0.01% by mass or less, and may be 0% by mass or less. The clear ink is not the above-mentioned treatment liquid.

[0100] Here, the composition of the clear ink composition can be the same as that of the non-white ink composition described above, except for the coloring material.

[0101] The clear ink applying step may be performed in any manner as long as the non-white ink composition is applied while scanning the recording head with respect to the recording medium. For example, the recording head may be an inkjet head, and the clear ink composition may be ejected from the inkjet head.

[0102] Furthermore, the order in which the clear ink application steps are carried out is not particularly limited, but for example, it is preferable to apply the clear ink composition after applying the white ink composition and the non-white ink composition.

[0103] In the recording area where the white ink composition and the non-white ink composition are applied, the maximum amount of the clear ink composition applied is preferably 5 mg / inch 2 More preferably, it is 0.1 to 4 mg / inch 2 More preferably, it is 0.5 to 4 mg / inch. 2 and more preferably 1 to 4 mg / inch 2 When the maximum adhesion amount is within the above range, the abrasion resistance and other properties of the resulting recorded matter tend to be improved.

[0104] 1.6.Drying process The recording method of the present embodiment may include a drying step of heating the recording medium before each step, after the treatment liquid application step, after the white ink application step and the non-white ink application step, and after the clear ink application step. The heating temperature is not particularly limited, but can be, for example, 50 to 100°C.

[0105] The heating method is not particularly limited, but examples thereof include a platen heater, a preheater, an IR heater, and a blower fan.

[0106] 1.7. Recording medium The recording medium used in this embodiment is not particularly limited, and examples thereof include absorbent recording media such as paper, film, and cloth, low absorbent recording media such as printed paper, and non-absorbent recording media such as metal, glass, and polymer. Among these, low absorbent recording media or non-absorbent recording media are preferred from the viewpoint of ink absorbency. Also, non-white recording media are preferred from the viewpoint of color. In the past, such recording media were formed by stacking a white ink layer and a non-white ink layer, and the white ink layer was used as a concealing layer to record high-quality images. Therefore, by using the present invention, the effect of the present invention, that an image with excellent color development without unevenness in shading, can be particularly effectively exhibited.

[0107] In this embodiment, the non-absorbent or low-absorbent recording medium is a recording medium that is absorbent within 30 msec from the start of contact in the Bristow method. 1 / 2 Water absorption up to 10mL / m 2 This refers to a recording medium that is the following: The Bristow method is the most widely used method for measuring the amount of liquid absorbed in a short period of time, and is also adopted by the Japan Pulp and Paper Technical Association (JAPAN TAPPI). Details of the test method are described in Standard No. 51 "Paper and paperboard - Liquid absorbency test method - Bristow method" of the "JAPAN TAPPI Paper and Pulp Test Method 2000 Edition."

[0108] Examples of non-absorbent recording media include those in which a plastic is coated on a substrate such as paper, those in which a plastic film is adhered to a substrate such as paper, plastic films that do not have an absorption layer (receptive layer), etc. Examples of plastics include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, etc.

[0109] In addition, the low-absorbency recording medium may be, for example, a recording medium having a low-absorbency coating layer on the surface. For example, it may be called coated paper. For example, the substrate may be paper, such as printing paper, coated paper, matte paper, etc., and the substrate may be a plastic film, such as polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, etc., coated with a polymer or the like, or coated with particles of silica, titanium, etc. together with a binder.

[0110] As the recording medium, an absorbent recording medium can also be used. The absorbent recording medium is a recording medium that is absorbed within 30 msec from the start of contact in the above-mentioned "Bristow method." 1 / 2 Water absorption up to 10mL / m 2 It refers to a "super recording medium."

[0111] The absorbent recording medium is not particularly limited, but examples thereof include plain paper, cardboard, liner paper, etc. Liner paper includes those made of paper such as kraft pulp and recycled paper.

[0112] Examples of non-white recording media include transparent recording media (transparent recording media). Transparent recording media may be colorless and transparent, or colored (colored) transparent. Transparent also includes semi-transparent. These are recording media that are visually translucent. They are also recording media that are visible light transmissive. In such cases, an image formed on one side of the recording medium by the recording method of this embodiment can be clearly viewed from both sides.

[0113] Further, examples of non-white recording media include non-white colored recording media (non-white colored recording media). Examples include non-white colored opaque recording media and non-white colored transparent recording media. In this case, too, the recording method of this embodiment can easily form an image with good image quality such as visibility, filling, and reduced image quality difference. The non-white colored recording media may be the transparent recording media described above, or may not be transparent recording media. Recording media that are not transparent are recording media that do not have translucency when viewed from the naked eye. Recording media that are not translucent to visible light are also recording media. Here, non-white colored recording media are colors other than white.

[0114] 2. Recording device The recording apparatus of the present embodiment is a recording apparatus that records on a recording medium, and is equipped with a treatment liquid application mechanism that applies a treatment liquid containing a coagulant to the recording medium, a white ink head that applies a white ink composition containing a white colorant to the recording medium, a non-white ink head that applies a non-white ink composition containing a non-white colorant to the recording medium, and a scanning mechanism that performs relative scanning of the white ink head and the non-white ink head with the recording medium, and performs recording by the above-mentioned recording method.

[0115] An example of a recording apparatus used in the present embodiment will be described below with reference to the drawings, but the recording apparatus used in the present embodiment is not limited to the following aspect.

[0116] An example of a recording device used in this embodiment is shown in Fig. 1. In Fig. 1, an on-carriage type printer in which an ink cartridge is mounted on a carriage is taken as an example for explanation, but the recording device is not limited to an on-carriage type printer, and may be an off-carriage type printer in which the ink cartridge is fixed externally.

[0117] The printer used in the following description is a serial printer in which an inkjet head for recording is mounted on a carriage that moves in a predetermined direction, and the inkjet head moves with the movement of the carriage to eject droplets onto the recording medium. The recording device is not limited to a serial printer, and may be a line printer. A line printer is a printer in which the inkjet head is formed wider than the width of the recording medium, and ejects droplets onto the recording medium without moving the inkjet head.

[0118] As shown in FIG. 1, the printer 1 includes a recording head 2, an ink cartridge 3, a carriage 4, a platen 5, a heating mechanism 6, a carriage movement mechanism 7, a medium feed mechanism 8, a guide rod 9, a linear encoder 10, and a control unit CONT.

[0119] The control unit CONT controls the operation of the entire printer 1. The carriage 4 mounts the recording head 2, which will be described later, and removably mounts ink cartridges 3 that supply each ink composition and treatment liquid to the recording head 2. The platen 5 is disposed below the recording head 2, and transports the recording medium M, which is a recording medium. The heating mechanism 6 heats the recording medium M. The carriage movement mechanism 7 moves the carriage 4 in the medium width direction of the recording medium M. The medium feed mechanism 8 transports the recording medium M in the medium feed direction. Here, the medium width direction is the main scanning direction MS, which is the operation direction of the recording head 2. The medium feed direction is the sub-scanning direction SS, which is a direction perpendicular to the main scanning direction MS and in which the recording medium M moves.

[0120] The recording head 2 is a means for depositing each ink composition and treatment liquid onto the recording medium M, and is provided with a first nozzle for ejecting a white ink composition and a second nozzle for ejecting a non-white ink composition on the surface facing the recording medium M to which each ink composition is deposited. These multiple nozzles are arranged in a row, thereby forming a nozzle surface on the surface of the nozzle plate. In FIG. 1, the recording head 2 serves as both a white ink head and a non-white ink head.

[0121] Examples of the method for ejecting the white ink composition or the non-white ink composition from the nozzle include a piezoelectric method in which pressure and a recording information signal are simultaneously applied to the white ink composition or the non-white ink composition by a piezoelectric element, thereby ejecting and recording droplets of the ink or the non-white ink composition. In addition to an inkjet head, a dot impact head, a thermal transfer head, or the like may also be used as the recording head 2.

[0122] 2 shows a nozzle formation surface when an inkjet head is used as the recording head 2. When scanning is performed by ejecting a white ink composition from nozzle row N1 and ejecting a non-white ink composition from nozzle row N2, the nozzle rows N1 and N2 have an overlapping portion in the sub-scanning direction SS when projected in the main scanning direction MS. In this case, the white ink composition and the non-white ink composition are deposited in the same region of the recording medium by one scan of the inkjet head.

[0123] In the above example, the identical area is the part where nozzle row N1, which ejects white ink, and nozzle row N2, which ejects non-white ink, overlap each other in the sub-scanning direction SS when projected in the main scanning direction MS.

[0124] 3 to 4 show another embodiment of the inkjet head. In the inkjet head shown in FIGS. 3 to 4, the region is further divided into blocks B1 to B3 in the sub-scanning direction SS. In this inkjet head, the type of droplets ejected can be changed for each block and nozzle row. For example, in FIG. 3, the inkjet head may be configured so that white ink is ejected in block B1 of nozzle row N1, non-white ink is ejected in blocks B1 to 2 of nozzle row N2, and treatment liquid is ejected in blocks B1 to 3 of nozzle row N3. In this way, by further dividing the inkjet head into blocks in the sub-scanning direction SS, a more flexible ejection mode can be realized.

[0125] In FIG. 1, the ink cartridge 3 that supplies a white ink composition and the like to the recording head 2 is composed of four independent cartridges. For example, three of the four cartridges are filled with different types of ink compositions, and one of them is filled with a treatment liquid. The ink cartridge 3 is detachably mounted on the recording head 2. In the example of FIG. 1, the number of cartridges is four, but this is not limited thereto, and any desired number of cartridges can be mounted.

[0126] The carriage 4 is attached in a state supported by a guide rod 9, which is a support member installed in the main scanning direction, and moves in the main scanning direction along the guide rod 9 by a carriage moving mechanism 7. In the example of Fig. 1, the carriage 4 moves in the main scanning direction, but is not limited to this, and may move in the sub-scanning direction in addition to the movement in the main scanning direction.

[0127] The installation position of the heating mechanism 6 is not particularly limited as long as it is provided in a position where it can heat the recording medium M. In the example of Fig. 1, the heating mechanism 6 is installed on the platen 5 at a position facing the recording head 2. When the heating mechanism 6 is installed at a position facing the recording head 2, the position on the recording medium M where the ink or non-white ink composition is attached can be reliably heated, and the white ink composition or non-white ink composition attached to the recording medium M can be efficiently dried.

[0128] Examples of the heating mechanism 6 include a print heater mechanism that heats the recording medium M by contacting it with a heat source, a mechanism that irradiates infrared rays or microwaves, which are electromagnetic waves with a maximum wavelength at around 2450 MHz, and a dryer mechanism that blows hot air.

[0129] The heating mechanism 6 heats the recording medium M before or when the droplets ejected from the nozzles of the recording head 2 adhere to the recording medium M. The control unit CONT controls various heating conditions, such as the timing of heating, the heating temperature, and the heating time.

[0130] The linear encoder 10 detects the position of the carriage 4 in the main scanning direction with a signal. The signal detected by the linear encoder 10 is sent to the control unit CONT as position information. The control unit CONT recognizes the scanning position of the recording head 2 based on the position information from the linear encoder 10, and controls the recording operation, i.e., the ejection operation, of the recording head 2. The control unit CONT is configured to be able to variably control the moving speed of the carriage 4. EXAMPLES

[0131] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0132] 1. Method for preparing ink composition and treatment liquid 1.1. Resin 1: Styrene-acrylic resin emulsion Styrene / acrylic acid / methyl methacrylate / cyclohexyl methacrylate were copolymerized by emulsion polymerization in a mass ratio of 75 / 0.8 / 14.2 / 10 to obtain a styrene-acrylic resin emulsion (Resin 1). At this time, 2 parts by mass of Newcol NT-30 (manufactured by Nippon Nyukazai Co., Ltd.) was used as the emulsion polymerization surfactant, based on 100 parts by mass of the total amount of monomers.

[0133] 1.2. Resin 2: Styrene-acrylic resin emulsion A styrene-acrylic resin emulsion (resin 2) was obtained in the same manner as in the preparation of resin 1, except that the amount of acrylic acid relative to the total amount of monomers was increased.

[0134] 1.3. Preparation Each material was mixed in the composition shown in Table 1 below and thoroughly stirred to obtain each ink composition and treatment liquid. Specifically, each material was mixed uniformly and insoluble matter was removed using a filter to prepare the ink composition and treatment liquid. In Table 1 below, the units of values ​​are mass %, and the total is 100.0 mass %. Also, unless otherwise specified, the solid content is shown.

[0135] [Table 1] BYK348: BYK Japan, silicone surfactant Hi-Tec E6500: Toho Chemical Industry Co., Ltd., polyethylene wax emulsion Catiomaster PD-7: Yokkaichi Chemical Co., Ltd., amine-epichlorohydrin condensation polymer

[0136] 1.4. Viscosity increase ratio The viscosity of the white ink composition and the non-white ink composition was measured using an E-type viscometer (MCR302 manufactured by Anton Paar) at room temperature and a shear rate of 200 s -1 The white ink composition or non-white ink composition was mixed at a mass ratio of 10 g to 1 g of a 5% by mass aqueous solution of calcium acetate monohydrate, and stirred for 10 seconds. The viscosity of the mixture was then immediately measured at room temperature and a shear rate of 200 s using an E-type viscometer (MCR302 manufactured by Anton Paar). -1 The viscosity increase ratio was calculated from the ratio of the viscosity before mixing to the viscosity after mixing.

[0137] 2. Evaluation 2.1. Uneven Shading A modified serial inkjet printer (product name SC-S40650) was prepared. Each nozzle row had 360 nozzles at a nozzle density of 360 dpi. As shown in FIG. 5, an inkjet head capable of ejecting any of the droplets listed in Tables 2 and 3 was provided in an area defined by nozzle rows N1 to N4 and block numbers.

[0138] The ink jet printer was filled with the ink composition and treatment liquid, and each ink composition and treatment liquid was made ejectable from the nozzle rows and blocks specified in Tables 2 to 3, and a solid image was recorded with the deposition amount and number of passes listed in Tables 2 to 3. The number of passes listed in Tables 2 to 3 refers to the number of passes per ink in which a main scan is performed on a band region of the distance of one sub-scan, and for example, 4 passes means that the distance of one sub-scan is ¼ of the length of the nozzle row used for recording.

[0139] In Tables 2-3, M1 means that K-liner (manufactured by Oji Paper) was used as the recording medium, and M2 means that transparent PVC media E1000ZC (manufactured by Lintec Corporation) was used as the recording medium. In the example using recording medium M1, primary heating and secondary heating were not performed. On the other hand, in the example using recording medium M2, primary heating was performed with a platen heater so that the surface temperature of the recording medium became 35°C, and secondary heating was performed with a secondary heater so that the surface temperature of the recording medium became 70°C.

[0140] The recorded matter obtained as described above was visually inspected, and the unevenness of shading in the solid pattern was evaluated according to the following evaluation criteria. (Evaluation Criteria) A: The color does not appear to be unevenly shaded in the pattern. B: There are slight variations in the color shading in the pattern. C: There is a noticeable amount of subtle unevenness in the color shading in the pattern. D: Large color variations are visible in the pattern.

[0141] 2.2.Color development The recorded matter obtained as described above was visually inspected and the color development was evaluated according to the following evaluation criteria. The visual inspection was performed from the recorded side. (Evaluation Criteria) A: It looks like a beautiful cyan color. B: Slightly whitish but looks cyan C: Clearly a whitish cyan color D: It is whitish and does not look cyan.

[0142] 2.3.Abrasion resistance A load was applied to the solid pattern portion of the recorded matter obtained as described above using a Gakushin-type abrasion resistance tester ("AB-301" manufactured by Tester Sangyo Co., Ltd.), and the image portion was rubbed with a friction element attached with white cotton cloth (compliant with JIS L 0803). The degree of peeling of the image was then visually observed, and the abrasion resistance was evaluated according to the following evaluation criteria. Note that recording medium M1 was rubbed 20 times with a load of 100 g, and recording medium M2 was rubbed 50 times with a load of 200 g. (Evaluation Criteria) AA: No visible scratches A: If you look closely you can see some scratches. B: Clear scratches are visible C: Severe chafing

[0143] 2.4.Recording speed The recording speed was evaluated according to the number of printing passes. Note that, in the following evaluation criteria, the recording speed is evaluated according to the number of passes, but the actual recording speed can be determined by comparing and considering the case where the white ink composition and the non-white ink composition are applied to the same scanning area by the same relative scanning and the case where they are applied by separate operations. (Evaluation Criteria) A: Number of printing passes is 4 or less B: Number of printing passes: 5 to 8 C: Number of printing passes is 9 or more

[0144] [Table 2]

[0145] [Table 3]

[0146] 3. Evaluation results As described above, the recording method of the present invention allows the deposition of a white ink composition and a non-white ink composition to the same scanning area by the same relative scanning, thereby suppressing uneven shading and providing a recorded product with excellent color development and abrasion resistance, and also making it possible to improve the printing speed.

[0147] In particular, in Comparative Example 1, which did not use a white ink composition, the color development was poor, and in Comparative Example 2, which did not use a treatment liquid, the unevenness in shading was poor. Also, in Comparative Examples 3 and 4, in which the white ink composition and the non-white ink composition were not applied simultaneously, it was found that both the color development and the unevenness in shading were poor, and also that the printing speed was poor because the number of passes was increased by not applying them simultaneously. [Explanation of symbols]

[0148] REFERENCE SIGNS LIST 1... printer, 2... recording head, 3... ink cartridge, 4... carriage, 5... platen, 6... heating mechanism, 7... carriage movement mechanism, 8... medium feed mechanism, 9... guide rod, 10... linear encoder, M... recording medium, CONT... control unit

Claims

1. A recording method for recording on a recording medium, comprising the steps of: a treatment liquid applying step of applying a treatment liquid containing a flocculant to the recording medium; a white ink applying step of applying a white ink composition containing a white color material to the recording medium; a non-white ink applying step of applying a non-white ink composition containing a non-white colorant to the recording medium; , The deposition of the white ink composition and the deposition of the non-white ink composition are performed by a recording head and a recording By scanning relative to the medium, The recording head includes a nozzle array for ejecting droplets of the white ink composition and a nozzle array for ejecting droplets of the non-white ink composition. The ink jet head has a nozzle row for ejecting droplets of the ink composition, and is mounted on a carriage. The carriage moves relative to the recording medium while depositing droplets of the white ink composition and the relative scanning is performed by ejecting droplets of the non-white ink composition; a nozzle row for ejecting droplets of the white ink composition; The nozzle array that outputs the ink jet head is aligned in the direction of the relative scanning when projected in the direction of the relative scanning. have overlapping portions in perpendicular directions, The overlapping portion prevents the white ink composition from being applied and the non-white ink composition from being applied. and performing the same scanning area of ​​the recording medium by the same relative scanning. In the recording medium, an area to which the treatment liquid is applied and an area to which the white ink composition is applied are , and the non-white ink composition is applied to the area overlapping the area, Recording method.

2. In the recording area to which the white ink composition and the non-white ink composition are applied, The amount of the non-white ink composition attached per area is 100% by mass. The amount of the composition attached is 100% by mass or less. The recording method according to claim 1 .

3. the recording head is an inkjet head, In the white ink application step and the non-white ink application step, the white ink composition and the non-white ink composition are ejected from the nozzle; The recording method according to claim 1 or 2.

4. The white ink composition and the non-white ink composition are respectively applied to the scanning area. The adhesive is applied by two or more scans. The recording method according to any one of claims 1 to 3.

5. In the recording area to which the white ink composition and the non-white ink composition are applied, Maximum adhesion amount of color ink composition is 15 mg / inch 2 Below is the The recording method according to any one of claims 1 to 4.

6. The white ink composition and the non-white ink composition each contain 5% by weight calcium acetate monohydrate. When mixed with a 0.05% aqueous solution, the viscosity increase ratio after mixing is 2 times or more compared to before mixing. The recording method according to any one of claims 1 to 5.

7. The content of the white coloring material is 5 to 20% by mass with respect to the total amount of the white ink composition. the law of nature, The content of the non-white coloring material is 0.5 to 10% by mass with respect to the total amount of the non-white ink composition. %. The recording method according to any one of claims 1 to 6.

8. the white ink composition and the non-white ink composition are each a water-based ink; The recording method according to any one of claims 1 to 7.

9. The recording medium is a low-absorbency recording medium or a non-absorbency recording medium. The recording method according to any one of claims 1 to 8.

10. The recording medium is a non-white recording medium. The recording method according to any one of claims 1 to 9.

11. A recording device for recording on a recording medium by the recording method according to any one of claims 1 to 10. So, a treatment liquid applying mechanism that applies a treatment liquid containing a flocculant to a recording medium; The nozzle array ejects droplets of a white ink composition containing a white coloring material and deposits the droplets on the recording medium. and ejecting droplets of a non-white ink composition containing a non-white coloring material onto the recording medium. the recording head having a nozzle array; the carriage on which the recording head is mounted; a scanning mechanism for performing the relative scanning of the recording head and the recording medium, Recording device.

Images