Recording method and recording device

Abstract

To provide a recording method that can effectively reduce streaks that occur in the color image in the image area at the nozzle position where white ink failure occurs, when a background image made of white ink and an image made of color ink are superimposed using a reaction solution. [Solution] The method comprises the steps of: applying a processing liquid containing a coagulant to a recording medium; ejecting a white ink composition from an inkjet head and adhering it to the recording medium; ejecting a non-white ink composition from the inkjet head and adhering it to the recording medium; and ejecting a clear ink composition containing a resin from the inkjet head and adhering it to the recording medium. A white image and a non-white image are superimposed to form the image. The white ink, non-white ink, and clear ink are water-based inks, and the clear ink is applied to the area of ​​the image to be recorded by a non-ejecting nozzle among the multiple nozzles of the inkjet head that ejects the white ink.

Description

[Technical Field]

[0001] This invention relates to a recording method and a recording apparatus. [Background technology]

[0002] Inkjet recording methods, which enable the recording of high-resolution images with relatively simple equipment, are undergoing rapid development in various fields. Within this context, attempts are being made to improve image quality by preventing bleeding and color mixing by using processing solutions (hereinafter also referred to as "reaction solutions") that rapidly increase the viscosity and reduce the fluidity of ink droplets.

[0003] For example, Patent Document 1 describes a recording method comprising the steps of applying white ink to a region to which a reaction solution has been applied, and applying colored ink to the region to which the white ink has been applied. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2015-071738 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, when using a reaction solution to superimpose a background image made with white ink and an image made with color ink, there is a problem in that streaks (hereinafter also referred to as "reactivity-induced streaks") appear in the color image in the image area at the nozzle position where the white ink fails to be ejected. [Means for solving the problem]

[0006] One aspect of the recording method according to the present invention is: A processing liquid application step in which a processing liquid containing a coagulant is applied to a recording medium, A white ink adhesion step of ejecting a white ink composition containing a white coloring material from an inkjet head and attaching it to the recording medium, A non-white ink adhesion step of ejecting a non-white ink composition containing a non-white coloring material from the inkjet head and attaching it to the recording medium, A clear ink adhesion step of ejecting a clear ink composition containing a resin from the inkjet head and attaching it to the recording medium, and having, A white image formed by the adhesion of the white ink composition and a non-white image formed by the adhesion of the non-white ink composition are overlapped and formed, The white ink composition, the non-white ink composition, and the clear ink composition are aqueous inks, For an area of an image to be recorded by non-ejecting nozzles among a plurality of nozzles of the inkjet head that ejects the white ink composition, the clear ink composition is adhered.

[0007] One aspect of the recording apparatus according to the present invention is, A recording apparatus that performs recording by the recording method of the above aspect, It has the treatment liquid, the white ink composition, the non-white ink composition, the clear ink composition, an adhesion mechanism that performs the treatment liquid adhesion step, an inkjet head that performs the white ink adhesion step, an inkjet head that performs the non-white ink adhesion step, and an inkjet head that performs the white clear ink adhesion step.

Brief Description of Drawings

[0008] [Figure 1] A front view schematically showing an example of the recording apparatus according to the present embodiment. [Figure 2] A bottom view partially showing the configuration of the recording unit. [Figure 3] A perspective view schematically showing another example of the recording apparatus according to the present embodiment. [Figure 4] Table 1 showing composition examples of the treatment liquid and each ink composition. [Figure 5]Table 2 shows each example and their evaluation results. [Figure 6] Table 3 shows each example and comparative example, as well as their evaluation results. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below. The embodiments described below are examples of the present invention. The present invention is not limited in any way to the embodiments described below, and includes various modifications that can be implemented without changing the gist of the present invention. Not all of the configurations described below are necessarily essential to the present invention.

[0010] In this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively. In this specification, "(meth)acrylic" means acrylic or methacrylic, and "(meth)acrylate" means acrylate or methacrylate.

[0011] 1. Recording method A recording method according to one embodiment of the present invention comprises a processing liquid application step of applying a processing liquid containing a coagulant to a recording medium, a white ink application step of ejecting a white ink composition containing a white colorant from an inkjet head and applying it to the recording medium, a non-white ink application step of ejecting a non-white ink composition containing a non-white colorant from an inkjet head and applying it to the recording medium, and a clear ink application step of ejecting a clear ink composition containing a resin from an inkjet head and applying it to the recording medium, wherein a white image formed by the application of the white ink composition and a non-white image formed by the application of the non-white ink composition are superimposed to form the image, the white ink composition, the non-white ink composition and the clear ink composition are water-based inks, and the clear ink composition is applied to the area of ​​the image to be recorded by a non-ejecting nozzle among a plurality of nozzles of the inkjet head that ejects the white ink composition.

[0012] In this study, when a reaction solution was used to superimpose a background image using white ink and a main image using color ink, streaks appeared in the color image in the image area at the nozzle location where white ink failed to be dispensed. Conventionally, nozzle compensation processing, such as increasing the amount of ink adhering to the nozzle location adjacent to the non-dispensing nozzle, is known, but the streaks could not be eliminated even with such nozzle compensation processing.

[0013] Therefore, after diligent research by the inventors, it was discovered that by applying clear ink to the image area at the nozzle position where white ink failure occurred, streaks in the color image can be reduced (a decrease in filling can be prevented).

[0014] In the image region at the nozzle location where white ink failure occurred, no white ink was present, suggesting that a larger amount of unreacted reaction solution remained compared to other image regions where white ink was present. It is hypothesized that color ink adhering to such regions with a large amount of unreacted reaction solution reacts more readily than in other regions, leading to earlier thickening and a decrease in fluidity. This reduced ink droplet filling and the formation of streaks. In response to this, we hypothesize that by applying clear ink to the image area at the nozzle location where the white ink failed to be ejected, the unreacted reaction solution reacted with the clear ink, suppressing the progress of the color ink reaction and reducing the occurrence of streaks.

[0015] The following describes each step of the recording method according to this embodiment.

[0016] 1.1 Processing liquid application process The recording method according to this embodiment includes a processing liquid attachment step in which a processing liquid containing a coagulant is attached to a recording medium.

[0017] 1.1.1 Adhesion Pattern Methods for applying the processing solution to the recording medium include non-contact and contact methods, or combinations thereof, such as inkjet printing, coating with rollers or bars, applying the processing solution to the recording medium using various sprays, immersing the recording medium in the processing solution, and applying the processing solution to the recording medium with a brush. Among these, the inkjet printing method is preferred.

[0018] The amount of processing solution applied is not particularly limited, but it should be 0.1 to 3.0 mg / inch per unit area of ​​the recording medium. 2 Preferably, 0.2 to 2.0 mg / inch 2 More preferably, 0.2 to 1.5 mg / inch 2 More preferably, 0.3 to 1.0 mg / inch 2 This is particularly preferable. When the amount of processing liquid adhering is within the above range, the occurrence of streaks caused by reactivity tends to be further reduced. The maximum amount of processing liquid adhering in the processing liquid adhesion step may also be within the above range.

[0019] When the processing liquid application process is carried out by ejecting the processing liquid from the inkjet head and applying it to the recording medium, the maximum weight per droplet of processing liquid is preferably 30 ng or less, more preferably 20 ng or less, even more preferably 15 ng or less, even more preferably 10 ng or less, and particularly preferably 8 ng or less. The lower limit of the maximum weight per droplet of the processing solution is not particularly limited, but is preferably 1 ng or more, more preferably 3 ng or more, and even more preferably 5 ng or more.

[0020] Furthermore, when the processing liquid adhesion step is performed by ejecting the processing liquid from the inkjet head and adhering it to the recording medium, the duty cycle of the processing liquid is preferably 1 to 20, more preferably 3 to 15, even more preferably 5 to 15, and particularly preferably 8 to 12.

[0021] Furthermore, the weight per droplet can be measured from the change in liquid volume if the image resolution and duty cycle are known. For example, ink ejection rate [ng / dot] = ink adhesion per unit area [mg / inch] 2 ] / (Resolution[dot / inch 2 ] × Duty × 10 -6 It can be calculated as shown above. Note that "Duty" is the value calculated by Duty(%) = Actual number of recorded dots / (Vertical resolution × Horizontal resolution) × 100 (wherein "Actual number of recorded dots" is the actual number of recorded dots per unit area, and "Vertical resolution" and "Horizontal resolution" are the resolutions per unit area).

[0022] When the processing liquid application process is performed by the inkjet method, it is preferable that the scanning process, in which the processing liquid is ejected from the inkjet head and applied to the recording medium while moving the relative position of the inkjet head and the recording medium, and the scanning process for applying the ink in the white ink application process and / or clear ink application process described later, are performed on the same scanning area using the same scanning method.

[0023] This can be done, for example, when an inkjet head has multiple nozzle rows, each consisting of multiple nozzles arranged along the direction of the head movement (hereinafter also referred to as the "nozzle row direction"), on the nozzle surface where the nozzles are formed, by arranging the nozzle row that ejects the processing liquid so that, when projected along the head movement direction, it overlaps at least a portion with the nozzle row that ejects the white ink composition and / or the clear ink composition in the nozzle row direction.

[0024] Note that "moving the relative position of the inkjet head and the recording medium" means moving the inkjet head relative to the recording medium. In this case, the inkjet head may move relative to the recording medium, or the recording medium may move relative to the inkjet head. Also, even if both the inkjet head and the recording medium move to change the relative positional relationship between them, it is acceptable. Also, the inkjet head can be mounted on a carriage, for example. The inkjet head may be moved by moving the carriage. In this case too, it is the movement of the inkjet head.

[0025] 1.1.2 Recording Medium The recording medium used in the recording method according to this embodiment is not particularly limited, and examples include absorbent recording media, low-absorbent recording media, non-absorbent recording media, and the like.

[0026] A low-absorbent or non-absorbent recording medium refers to a recording medium that does not absorb or hardly absorbs liquid. Quantitatively, a low-absorbent or non-absorbent recording medium refers to "a recording medium with a water absorption of 10 mL / m or less from the start of contact to 30 msec in the Bristow method". This Bristow method is the most popular method for measuring the liquid absorption amount in a short time and is also adopted by the Japan Pulp and Paper Technical Association (JAPAN TAPPI). The details of the test method are described in Standard No. 51, "Paper and Paperboard - Liquid Absorbency Test Method - Bristow Method" of "JAPAN TAPPI Paper and Pulp Test Methods 2000 Edition". In contrast, an absorbent recording medium refers to a recording medium that does not fall under a low-absorbent or non-absorbent recording medium.

[0027] ​​​​Examples of low-absorption recording media include recording media with a low-absorption coating layer on their surface, known as coated paper. Examples of paper-based recording media include art paper, coated paper, matte paper, and other printing papers. Examples of plastic-based recording media include those coated with polymers on the surface of polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, etc., or those coated with silica, titanium, or other particles together with a binder.

[0028] Examples of non-absorbent recording media include those in which a plastic coating is applied to a substrate such as paper, those in which a plastic film is adhered to a substrate such as paper, and plastic films that do not have an absorbent layer (receiving layer). Examples of such plastics include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene.

[0029] Among these, it is more preferable to use a recording medium that is a polyolefin-based film substrate. "Polyolefin-based" is a general term for polymers that use alkenes (olefins) as monomers. Examples include polyethylene and polypropylene.

[0030] The recording medium used in the recording method according to this embodiment is preferably a low-absorption recording medium or a non-absorption recording medium. When recording on such recording media, streaks due to reactivity tend to occur, but this can be significantly reduced by the recording method according to this embodiment.

[0031] 1.1.3 Treatment solution The following describes the components contained in the processing solution used in the recording method according to this embodiment. The processing solution is an auxiliary liquid used together with the ink composition to quickly thicken the ink and reduce its fluidity. The processing solution may contain colorants such as pigments, but it is preferably 0.2% by mass or less, more preferably 0.1% by mass or less, even more preferably 0.05% by mass or less, and the lower limit is 0% by mass. It is preferable that the processing solution does not contain colorants.

[0032] 1.1.3.1 Flocculants The processing solution used in the recording method according to this embodiment contains a coagulant. The coagulant reacts with components such as colorants and resins to coagulate the ink components. Such coagulation can, for example, enhance the color development of the colorant, improve the fixation of the resin, and / or increase the viscosity of the ink. However, the degree of coagulation of the colorant and resin by the coagulant varies depending on the type of coagulant, colorant, and resin, and can be adjusted.

[0033] While not particularly limited, examples of flocculants include metal salts, inorganic acids, organic acids, and cationic compounds. Cationic compounds include cationic resins (cationic polymers) and cationic surfactants. Among these, polyvalent metal salts are preferred as metal salts, and cationic resins are preferred as cationic compounds. Therefore, selecting a flocculant from cationic resins, organic acids, and polyvalent metal salts is preferable in terms of obtaining particularly excellent image quality, scratch resistance, gloss, etc.

[0034] While polyvalent metal salts are preferred as the metal salts, other metal salts can also be used. Among these flocculants, it is preferable to use at least one selected from metal salts and organic acids because of its excellent reactivity with the components contained in the ink. Furthermore, among cationic compounds, it is preferable to use cationic resins because they dissolve easily in the treatment solution. It is also possible to use multiple types of flocculants in combination.

[0035] A polyvalent metal salt is a compound composed of a metal ion with two or more valencies and an anion. Examples of metal ions with two or more valencies include calcium, magnesium, copper, nickel, zinc, barium, aluminum, titanium, strontium, chromium, cobalt, and iron. Among the metal ions that make up these polyvalent metal salts, it is preferable that at least one of calcium ions and magnesium ions is present, given their excellent ability to aggregate ink components.

[0036] The anions constituting the polyvalent metal salt are inorganic ions or organic ions. In other words, the polyvalent metal salt in this invention consists of an inorganic ion or organic ion and a polyvalent metal. Examples of such inorganic ions include chloride ions, bromide ions, iodide ions, nitrate ions, sulfate ions, hydroxide ions, etc. Examples of organic ions include organic acid ions, such as carboxylate ions.

[0037] Furthermore, the polyvalent metal compound is preferably an ionic polyvalent metal salt, and in particular, the stability of the treatment solution is better when the polyvalent metal salt is a magnesium salt or a calcium salt. In addition, either an inorganic acid ion or an organic acid ion may be used as the counterion for the polyvalent metal.

[0038] Specific examples of the polyvalent metal salts mentioned above include calcium carbonate such as heavy calcium carbonate and light calcium carbonate, calcium nitrate, calcium chloride, calcium sulfate, magnesium sulfate, calcium hydroxide, magnesium chloride, magnesium carbonate, barium sulfate, barium chloride, zinc carbonate, zinc sulfide, aluminum silicate, calcium silicate, magnesium silicate, copper nitrate, calcium formate, calcium acetate, magnesium acetate, and aluminum acetate. These polyvalent metal salts may be used individually or in combination of two or more. Among these, at least one of calcium formate, magnesium sulfate, calcium nitrate, and calcium chloride is preferred because it ensures sufficient solubility in water and reduces residue left by the treatment solution (making the residue less noticeable), with calcium formate and calcium nitrate being more preferred. These metal salts may also contain hydration water in their raw material form.

[0039] Examples of metal salts other than polyvalent metal salts include monovalent metal salts such as sodium salts and potassium salts, such as sodium sulfate and potassium sulfate.

[0040] Suitable organic acids include, for example, poly(meth)acrylic acid, acetic acid, glycolic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid, tartaric acid, lactic acid, sulfonic acid, orthophosphate, pyrrolidone carboxylic acid, pyrrone carboxylic acid, pyrrole carboxylic acid, furanic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, or derivatives of these compounds, or salts thereof. Organic acids may be used individually or in combination of two or more. Salts of organic acids that are metal salts are included in the above-mentioned metal salts.

[0041] Examples of inorganic acids include sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid. Inorganic acids may be used individually or in combination of two or more.

[0042] Examples of cationic resins (cationic polymers) include cationic urethane resins, cationic olefin resins, cationic amine resins, and cationic surfactants. Cationic polymers are preferably water-soluble.

[0043] As cationic urethane resins, commercially available products can be used, such as Hydran CP-7010, CP-7020, CP-7030, CP-7040, CP-7050, CP-7060, CP-7610 (product names, manufactured by Dainippon Ink and Chemicals, Inc.), Superflex 600, 610, 620, 630, 640, 650 (product names, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and Urethane Emulsion WBR-2120C, WBR-2122C (product names, manufactured by Taisei Fine Chemical Co., Ltd.).

[0044] Cationic olefin resins have olefins such as ethylene and propylene as their structural framework, and known ones can be appropriately selected and used. Cationic olefin resins may also be in an emulsion state dispersed in a solvent such as water or an organic solvent. Commercially available cationic olefin resins can be used, such as Arrowbase CB-1200 and CD-1200 (trade names, manufactured by Unitika Ltd.).

[0045] As cationic amine resins (cationic polymers), any resin having an amino group in its structure is acceptable, and known resins can be appropriately selected and used. Examples include polyamine resins, polyamide resins, and polyallylamine resins. Polyamine resins are resins having an amino group in the main skeleton of the resin. Polyamide resins are resins having an amide group in the main skeleton of the resin. Polyallylamine resins are resins having a structure derived from an allyl group in the main skeleton of the resin.

[0046] Furthermore, examples of cationic polyamine resins include Unisense KHE103L (hexamethylenediamine / epichlorohydrin resin, 1% aqueous solution with a pH of approximately 5.0, viscosity of 20-50 (mPa·s), and solid content of 50% by mass) and Unisense KHE104L (dimethylamine / epichlorohydrin resin, 1% aqueous solution with a pH of approximately 7.0, viscosity of 1-10 (mPa·s), and solid content of 20% by mass) manufactured by Senka Co., Ltd. Furthermore, specific examples of commercially available cationic polyamine resins include FL-14 (manufactured by SNF), Arafix 100, 251S, 255, 255LOX (manufactured by Arakawa Chemical Co., Ltd.), DK-6810, 6853, 6885; WS-4010, 4011, 4020, 4024, 4027, 4030 (manufactured by Seikou PMC Co., Ltd.), and Papiogen P-105 (manufactured by Senka Co., Ltd.). Examples include Sumirez Resin 650(30), 675A, 6615, SLX-1 (manufactured by Taoka Chemical Industry Co., Ltd.), Kachiomaster (registered trademark) PD-1, 7, 30, A, PDT-2, PE-10, PE-30, DT-EH, EPA-SK01, TMHMDA-E (manufactured by Yokkaichi Gosei Co., Ltd.), and Jetfix 36N, 38A, 5052 (manufactured by Satoda Chemical Co., Ltd.).

[0047] Polyamine resins can also be cited as examples of polyamine-based resins. Examples of polyamine resins include polyallylamine hydrochloride, polyallylamineamide sulfate, allylamine hydrochloride / diallylamine hydrochloride copolymer, allylamine acetate / diallylamine acetate copolymer, allylamine acetate / diallylamine acetate copolymer, allylamine hydrochloride / dimethylallylamine hydrochloride copolymer, allylamine / dimethylallylamine copolymer, polydiallylamine hydrochloride, polymethyldiallylamine hydrochloride, polymethyldiallylamineamide sulfate, polymethyldiallylamine acetate, polydiallyldimethylammonium chloride, diallylamine acetate / sulfur dioxide copolymer, diallylmethylethylammonium ethyl sulfate / sulfur dioxide copolymer, methyldiallylamine hydrochloride / sulfur dioxide copolymer, diallyldimethylammonium chloride / sulfur dioxide copolymer, and diallyldimethylammonium chloride / acrylamide copolymer.

[0048] Examples of cationic surfactants include primary, secondary, and tertiary amine salt compounds, alkylamine salts, dialkylamine salts, aliphatic amine salts, benzalkonium salts, quaternary ammonium salts, quaternary alkylammonium salts, alkylpyridinium salts, sulfonium salts, phosphonium salts, onium salts, and imidazolinium salts.

[0049] Multiple types of these flocculants may be used. Furthermore, selecting at least one of these flocculants—a polyvalent metal salt, an organic acid, or a cationic resin—results in better flocculation, thus enabling the formation of higher-quality images (especially those with good color reproduction).

[0050] The total content of the flocculant in the treatment solution is preferably 1% to 20% by mass, more preferably 3% to 15% by mass, and even more preferably 5% to 10% by mass, based on the total mass of the treatment solution. Even when the flocculant is shared in a solution or dispersion, it is preferable that the solid content falls within the above range. A flocculant content of 1% by mass or more tends to provide sufficient ability for the flocculant to coagulate the components contained in the ink. Furthermore, a flocculant content of 20% by mass or less tends to improve the solubility and dispersibility of the flocculant in the treatment solution, thereby improving the storage stability of the treatment solution.

[0051] Even if the organic solvent contained in the treatment solution has high hydrophobicity, the solubility of the coagulant in the treatment solution will be good. Therefore, it is preferable to use a coagulant that has a solubility of 1 g or more in 100 g of water at 25°C, and more preferably one that is between 3 g and 80 g.

[0052] 1.1.3.2 Surfactants The processing solution used in the recording method according to this embodiment may contain a surfactant. The surfactant has the function of adjusting the surface tension of the processing solution and, for example, adjusting the wettability with the recording medium. Among surfactants, for example, acetylene glycol-based surfactants, silicone-based surfactants, and fluorine-based surfactants can be preferably used.

[0053] The acetylene glycol-based surfactant is not particularly limited, but for example, one or more selected from 2,4,7,9-tetramethyl-5-decine-4,7-diol and alkylene oxide adducts of 2,4,7,9-tetramethyl-5-decine-4,7-diol, and 2,4-dimethyl-5-decine-4-ol and alkylene oxide adducts of 2,4-dimethyl-5-decine-4-ol are preferred. Commercially available acetylene glycol-based surfactants include, but are not limited to, Surfinol 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, and DF110D (all are brand names, manufactured by Air Products Japan Co., Ltd.). Examples include Olphine 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 brand names, manufactured by Nisshin Chemical Industry Co., Ltd.), and Acetylene Nol E00, E00P, E40, E100 (all brand names, manufactured by Kawaken Fine Chemical Co., Ltd.). Acetylene glycol-based surfactants may be used individually or in combination of two or more types.

[0054] Examples of silicone-based surfactants are not particularly limited, but include polysiloxane compounds and polyether-modified organosiloxanes. Examples of commercially available silicone-based surfactants are not particularly limited, but include BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348, BYK-349 (all trade names, manufactured by BI-Chemie Japan Co., Ltd.), KF-351A, KF-352A, KF-353, KF-354L, and KF-355. Examples include A, 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 SAG503A, Silface SAG014 (all product names, manufactured by Nisshin Chemical Industry Co., Ltd.). Silicone-based surfactants may be used individually or in combination of two or more types.

[0055] Examples of fluorinated surfactants include, but are not limited to, perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl phosphate esters, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl betaines, and perfluoroalkylamine oxide compounds. Examples of commercially available fluorinated surfactants include, but are not limited to, S-144, S-145 (trade names, manufactured by Asahi Glass Co., Ltd.); FC-170C, FC-430, Florard-FC4430 (trade names, manufactured by Sumitomo 3M Limited); FSO, FSO-100, FSN, FSN-100, FS-300 (trade names, manufactured by Dupont); FT-250, 251 (trade names, manufactured by Neos Co., Ltd.). Fluorinated surfactants may be used individually or in combination of two or more types.

[0056] When surfactants are included in the treatment solution, multiple types may be included. The amount of surfactants included in the treatment solution is preferably 0.1% to 5% by mass, more preferably 0.4% to 3% by mass, and even more preferably 0.5% to 2% by mass, relative to the total mass of the treatment solution.

[0057] 1.1.3.3 Organic Solvents The processing solution used in the recording method according to this embodiment may contain an organic solvent. Preferably, the organic solvent is a water-soluble organic solvent. "Water-soluble" means that the solubility in water at 20°C is greater than 10 g / 100 g of water.

[0058] Examples of organic solvents include esters, glycol ethers, cyclic esters, amides, alcohols, and polyhydric alcohols.

[0059] Esters include glycol monoacetates such as 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, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, methoxybutyl acetate, ethylene glycol diacetate, and diethylene glycol. Examples of glycol diesters include propyl 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, and dipropylene glycol acetate propionate.

[0060] Examples of glycol ethers include monoethers or diethers of alkylene glycols. Examples of alkylene glycol monoethers include alkylene glycol monoalkyl ethers such as 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, 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 monomethyl ether, and tripropylene glycol monobutyl ether. Examples of alkylene glycol diethers include alkylene glycol dialkyl ethers such as 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, 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.

[0061] Examples of cyclic esters include cyclic esters (lactones) such as 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-nonalactone, ε-nonalactone, and ε-decanolactone, as well as compounds in which the hydrogen atoms of the methylene group adjacent to the carbonyl group are substituted with alkyl groups having 1 to 4 carbon atoms.

[0062] Examples of amides include cyclic amides and acyclic amides. Examples of acyclic amides include alkoxyalkyl amides. Examples of cyclic amides include lactams. Examples of lactams include pyrrolidones such as 2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1-propyl-2-pyrrolidone, 1-butyl-2-pyrrolidone, and 1-(2-hydroxyethyl)pyrrolidine-2-one. Examples of alkoxyalkylamides include 3-methoxy-N,N-dimethylpropionamide, 3-methoxy-N,N-diethylpropionamide, 3-methoxy-N,N-methylethylpropionamide, 3-ethoxy-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, and 3-n-propoxy-N,N-dimethylpropionamide. Examples include propionamide, 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-methylethylpropionamide, N,N-dimethylisobutyrateamide, etc.

[0063] Examples of alcohols include compounds in which one hydrogen atom of an alkane is replaced by a hydroxyl group. The alkane preferably has 10 or fewer carbon atoms, more preferably 6 or fewer, and even more preferably 3 or fewer. The alkane has 1 or more carbon atoms, preferably 2 or more. The alkane may be linear or branched. Examples of alcohols include methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, 2-butanol, tert-butanol, iso-butanol, n-pentanol, 2-pentanol, 3-pentanol, and tert-pentanol, 2-phenoxyethanol, benzyl alcohol, and phenoxypropanol.

[0064] Polyhydric alcohols are molecules that contain two or more hydroxyl groups. Polyhydric alcohols can be further classified into, for example, alkanediols and polyols.

[0065] Alkanediols include, for example, compounds in which an alkane is substituted with two hydroxyl groups. Examples of alkanediols include 1,2-alkanediols, which are a general term for compounds in which hydroxyl groups are substituted at the 1st and 2nd positions of an alkane, and other alkanediols other than 1,2-alkanediols. Alkanediols are preferably diols of alkanes having 5 or more carbon atoms. The number of carbon atoms in the alkane is preferably 5 to 15, more preferably 6 to 10, and even more preferably 6 to 8. Preferably, it is a 1,2-alkanediol.

[0066] Examples of 1,2-alkanediols include ethylene glycol, 1,2-propanediol (propylene glycol), 1,2-butanediol, 1,2-pentanediol (1,2PD), 1,2-hexanediol, 1,2-heptanediol, 1,2-octanediol, 1,2-nonanediol, 1,2-decanediol, 3-methyl-1,2-butanediol, 3-methyl-1,2-pentanediol, 4-methyl-1,2-pentanediol, 3,4-dimethyl-1,2-pentanediol, and 3 Examples include -ethyl-1,2-pentanediol, 4-ethyl-1,2-pentanediol, 3-methyl-1,2-hexanediol, 4-methyl-1,2-hexanediol, 5-methyl-1,2-hexanediol, 3,4-dimethyl-1,2-hexanediol, 3,5-dimethyl-1,2-hexanediol, 4,5-dimethyl-1,2-hexanediol, 3-ethyl-1,2-hexanediol, 4-ethyl-1,2-hexanediol, and 3-ethyl-4-methyl-1,2-hexanediol.

[0067] Other examples of alkanediols include 1,3-propanediol, 1,3-butylene glycol (also known as 1,3-butanediol), 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2,4-pentanediol, 2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,3-pentanediol, 3-methyl-1,5-pentanediol, 2-methylpentane-2,4-diol, 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, and 2-methyl-2-propyl-1,3-propanediol.

[0068] Examples of polyols include condensates formed by the intermolecular condensation of two or more alkanediol molecules via hydroxyl groups, and compounds having three or more hydroxyl groups. The polyols are preferably polyols of alkanes having 4 or fewer carbon atoms, or intermolecular condensates of hydroxyl groups of polyols of alkanes having 4 or fewer carbon atoms. The number of carbon atoms in the alkane is preferably 2 to 3. The number of hydroxyl groups in the polyol molecule is 2 or more, preferably 5 or less, and more preferably 3 or less. If the polyols are the above intermolecular condensates, the number of intermolecular condensations is 2 or more, preferably 4 or less, and more preferably 3 or less.

[0069] Examples of condensates formed by the intermolecular condensation of two or more alkanediol molecules at their hydroxyl groups include dialkylene glycols such as diethylene glycol and dipropylene glycol, and trialkylene glycols such as triethylene glycol and tripropylene glycol.

[0070] Compounds having three or more hydroxyl groups are compounds with an alkane or polyether structure as their backbone and containing three or more hydroxyl groups. Examples of compounds having three or more hydroxyl groups include glycerin, trimethylolethane, trimethylolpropane, 1,2,5-hexanetriol, 1,2,6-hexanetriol, pentaerythritol, and polyoxypropylenetriol.

[0071] Organic solvents may be used individually or in combination of two or more types.

[0072] The total content of the organic solvent relative to the total mass of the processing solution is preferably, for example, 5% to 50% by mass, more preferably 10% to 45% by mass, even more preferably 15% to 40% by mass, and particularly preferably 20% to 40% by mass. Having the organic solvent content within the above range provides an even better balance between wetting spreadability and drying properties, making it easier to form higher-quality images.

[0073] It is also preferable to set the content of polyhydric alcohols (preferably alkanediols) as organic solvents within the above range.

[0074] Furthermore, it is more preferable that the processing solution contains an organic solvent among the examples of organic solvents described above, with a standard boiling point of 150.0°C to 280.0°C. This allows for faster drying and fixing of the formed image.

[0075] Furthermore, it is more preferable that the processing solution does not contain more than 1.0% by mass of organic solvents of polyols having a standard boiling point above 280.0°C. The content of organic solvents of polyols having a standard boiling point above 280°C in the processing solution is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, particularly preferably 0.5% by mass or less, and most particularly preferably 0.1% by mass or less, relative to the total mass of the processing solution. The lower limit of the content of organic solvents of polyols having a standard boiling point above 280°C may be 0% by mass. This method allows for better drying of the formed image, enables faster recording, and improves adhesion to the recording medium. Furthermore, it is even more preferable that the processing solution be an organic solvent (not limited to polyols) with a standard boiling point exceeding 280.0°C within the above range. Examples of organic solvents with a standard boiling point exceeding 280°C include glycerin and polyethylene glycol monomethyl ether.

[0076] 1.1.3.4 Water The processing solution used in the recording method according to this embodiment may contain water, and is preferably aqueous. "Aqueous" means that it contains at least water as a solvent component, and may contain water as the main solvent component.

[0077] Examples of suitable water include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, as well as ultrapure water, which has reduced ionic impurities. Furthermore, using water sterilized by ultraviolet irradiation or the addition of hydrogen peroxide can suppress the growth of bacteria and fungi when the treated solution is stored for a long period of time.

[0078] The water content is preferably 50% by mass or more, more preferably 50 to 100% by mass, in the liquid medium component. Furthermore, it is preferably 60 to 95% by mass, more preferably 70 to 90% by mass, and even more preferably 75 to 85% by mass. The liquid medium refers to a solvent component such as water or an organic solvent. Furthermore, the water content is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, relative to the total mass of the treatment liquid. There is no particular upper limit to the water content, but for example, it is preferably 99% by mass or less, and more preferably 90% by mass or less, relative to the total mass of the treatment liquid.

[0079] 1.1.3.5 Other Ingredients The processing solution used in the recording method according to this embodiment may further contain various additives as needed, such as ureas, amines, sugars, preservatives / antifungal agents, rust inhibitors, chelating agents, viscosity modifiers, antioxidants, and fungicides.

[0080] Examples of ureas include urea, ethyleneurea, tetramethylurea, thiourea, 1,3-dimethyl-2-imidazolidinone, 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.).

[0081] Examples of amines include diethanolamine, triethanolamine, and triisopropanolamine. Ureas and amines may also be used as pH adjusters.

[0082] Examples of sugars include glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol (sorbitol), maltose, cellobiose, lactose, sucrose, trehalose, and maltotriose.

[0083] 1.1.3.6 Physical Properties The processing liquid used in the recording method of this embodiment preferably has a surface tension of 40 mN / m or less, preferably 38 mN / m or less, more preferably 35 mN / m or less, and even more preferably 30 mN / m or less at 25°C, from the viewpoint of ensuring appropriate wetting spread onto the recording medium. The surface tension can be measured by using an automatic surface tension meter CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.) to check the surface tension when a platinum plate is wetted with the composition in an environment of 25°C.

[0084] When the processing solution is applied to the recording medium by an inkjet method, the viscosity at 20°C is preferably 1.5 mPa·s or more and 15 mPa·s or less, more preferably 1.5 mPa·s or more and 7 mPa·s or less, and even more preferably 1.5 mPa·s or more and 5.5 mPa·s or less.

[0085] 1.2 White ink application process The recording method according to this embodiment includes a white ink application step in which a white ink composition containing a white colorant is ejected from an inkjet head and attached to the recording medium.

[0086] 1.2.1 Adhesion Pattern The amount of white ink composition applied is not particularly limited, but should be 1 to 30 mg / inch per unit area of ​​the recording medium. 2 Preferably, 5-25 mg / inch 2 More preferably, 10-20 mg / inch 2 More preferably, 12-18 mg / inch 2 This is particularly preferable. The maximum amount of white ink composition that adheres may be within the above range.

[0087] The maximum weight per drop of the white ink composition is 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. The lower limit of the maximum weight per drop of the white ink composition is not particularly limited, but is preferably 5 ng or more, more preferably 8 ng or more, and even more preferably 10 ng or more.

[0088] Furthermore, the duty cycle in the white ink composition is preferably 50 or higher, more preferably 60 or higher, even more preferably 70 or higher, and particularly preferably 80 or higher.

[0089] In the recording method according to this embodiment, it is preferable to perform a interpolation process on the area of ​​the image to be recorded by a non-discharging nozzle among the multiple nozzles of the inkjet head that ejects the white ink composition, using a nozzle that is not a non-discharging nozzle of the white ink composition. Performing such a process tends to reduce streaks on the white image. Note that streaks on the white image tend to be less noticeable than streaks on the color image. On the other hand, even if this process is performed alone, streaks caused by reactivity cannot be reduced unless clear ink is applied to the image area at the nozzle location where the white ink failed to be ejected.

[0090] Complementation processing is a process that reduces streaks in an image by increasing the amount of ink applied around areas of the image that should have been recorded but could not be recorded due to a nozzle failure.

[0091] From the viewpoint of effectively performing the supplementation, nozzles that are not non-discharge nozzles are preferably nozzles adjacent to non-discharge nozzles.

[0092] The amount of white ink composition adhering to the nozzle position where the interpolation process is performed is not particularly limited, but is 5 to 40 mg / inch per unit area of ​​the recording medium. 2 Preferably, 10-35 mg / inch 2 More preferably, 15-30 mg / inch 2 More preferably, 17-25 mg / inch 2 This is particularly preferable. The maximum amount of white ink composition that adheres may be within the above range.

[0093] The amount of white ink composition attached to the nozzle position where the complementary treatment is performed is preferably 1.05 times or more, more preferably 1.10 times or more, even more preferably 1.15 times or more, particularly preferably 1.20 times or more, and most particularly preferably 1.25 times or more, compared to the amount of white ink composition attached to the nozzle position where the complementary treatment is not performed (the amount of white ink composition attached in the white ink attachment process).

[0094] Complementary processing can include, for example, increasing the maximum weight per ink droplet or increasing the duty cycle.

[0095] The maximum weight per drop of the white ink composition in the nozzle where the complementary treatment is performed is 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. The lower limit of the maximum weight per drop of the white ink composition in the nozzle where the complementary treatment is performed is not particularly limited, but is preferably 5 ng or more, more preferably 8 ng or more, even more preferably 10 ng or more, and particularly preferably 14 ng or more.

[0096] The duty cycle of the white ink composition at the nozzle position where the complementary processing is performed is preferably 80 or higher, more preferably 90 or higher, and even more preferably 100 or higher.

[0097] The nozzle density of the inkjet head that ejects the white ink composition and the inkjet head that ejects the non-white ink composition described later is preferably 1200 npi or more. Inkjet heads with such a nozzle density tend to have small nozzle sizes and close nozzle distances, which can easily lead to non-ejection of white ink and streaks caused by reactivity. In contrast, the recording method according to this embodiment tends to be able to effectively reduce streaks caused by reactivity, even with inkjet heads with such a nozzle density.

[0098] Note that "npi" stands for nozzles per inch, and is a unit notation that represents the number of nozzles per inch.

[0099] The method of application for the white ink application process and the non-white ink application process described later is preferably carried out by scanning (hereinafter also referred to as "scanning"), in which the inkjet head ejects ink and adheres it to the recording medium while the relative positions of the inkjet head and the recording medium move.

[0100] The number of scans performed on the same scanning area in the recording medium is not particularly limited and may be one or more scans, independently of the white ink application step and the non-white ink application step.

[0101] When the same scanning area on a recording medium is scanned multiple times, the inkjet head that ejects ink passes over the same area on the recording medium multiple times. The more times the scanning is performed, the more ink can be applied to the desired area in multiple passes, which tends to improve the image quality of the resulting recording. From the viewpoint of achieving better image quality, the number of scans is preferably 2 or more, more preferably 3 or more, even more preferably 4 or more, and particularly preferably 6 or more. There is no upper limit, but from the viewpoint of achieving better productivity, it is preferably 24 or less, more preferably 12 or less, and even more preferably 8 or less. The number of scans is set for each type of ink.

[0102] In cases where multiple passes are used, it is preferable to record by performing the scan (main scan) and sub-scan multiple times each. For example, the main scan and sub-scan can be performed alternately and repeatedly. For example, when recording in 4 passes, if the length of one sub-scan in the sub-scanning direction is one-quarter the length of the nozzle row aligned in the sub-scanning direction of the inkjet head, then four main scans will be performed on the same portion (same scanning area) of a rectangular scanning region that is the length of one sub-scan in the sub-scanning direction and extends in the main scanning direction. The number of scans in this view is called the number of scans or the number of passes. "Sub-scanning" refers to the operation of moving the relative position of the inkjet head and the recording medium in the sub-scanning direction. The "sub-scanning direction" is the direction that intersects with the main scanning direction (i.e., the direction in which the inkjet head moves relative to the recording medium). For example, by applying ink to a certain area of ​​the recording medium during a main scan, moving the recording medium slightly during a sub-scan, and then performing the next main scan, the process of applying ink adjacent to or partially overlapping the previously applied ink can be repeated to record data. Note that "sub-scan" also refers to the movement of the inkjet head relative to the recording medium; the inkjet head may move relative to the recording medium, or the recording medium may move relative to the inkjet head. The direction of such relative movement is called the sub-scan direction.

[0103] On the other hand, it is preferable that the number of scans performed on the same scanning area in the recording medium be one in the white ink application step and one in the non-white ink application step. In this case, since white ink does not adhere to the image area at the nozzle position where white ink failure occurs, streaks caused by reactivity are particularly likely to occur. However, according to the recording method of this embodiment, even in this configuration, the occurrence of streaks caused by reactivity tends to be further reduced. Furthermore, if the number of scans performed on the same scanning area in the recording medium is set to one in the white ink application process and one in the non-white ink application process, the scans may be performed using the same scan or different scans.

[0104] The recording method according to this embodiment forms a white image by superimposing a white image formed by the adhesion of a white ink composition and a non-white image formed by the adhesion of a non-white ink composition described later. By superimposing a white image and a non-white image, the problem of streaks caused by reactivity arises. Examples of the manner in which the white image and the non-white image are superimposed include the following first adhesion mode and second adhesion mode.

[0105] The first adhesion method involves adhering a white ink composition and a non-white ink composition to the same scanning area of ​​a recording medium by different scanning methods, thereby forming a white image and a non-white image on top of each other; this method is also called lamination printing.

[0106] The second adhesion method involves adhering a white ink composition and a non-white ink composition to the same scanning area of ​​the recording medium using the same scanning method, thereby superimposing a white image and a non-white image; this method is also called simultaneous printing.

[0107] The order in which the white image and the non-white image are superimposed to form the image, i.e., the order of each step, is not particularly limited, but it is preferable to perform the processing liquid application step followed by the white ink application step, and the non-white ink application step followed by the white ink application step. With such a step order, streaks caused by reactivity tend to be more noticeable, but the recording method according to this embodiment tends to reduce the occurrence of streaks caused by reactivity even with such a step order.

[0108] Furthermore, it is preferable that the white image formed by the adhesion of the white ink composition be formed by superimposing it on the area to which the processing liquid has been applied in the processing liquid application step.

[0109] 1.2.2 White ink composition The following describes each component contained in the white ink composition used in the recording method according to this embodiment.

[0110] 1.2.2.1 White colorant The white ink composition used in the recording method according to this embodiment contains a white colorant.

[0111] Examples of white pigments include CI Pigment White 1, which is basic lead carbonate; CI Pigment White 4, which is made of zinc oxide; CI Pigment White 5, which is made of a mixture of zinc sulfide and barium sulfate; CI Pigment White 6, which is made of titanium dioxide; CI Pigment White 6:1, which is made of titanium dioxide containing other metal oxides; CI Pigment White 7, which is made of zinc sulfide; CI Pigment White 18, which is made of calcium carbonate; CI Pigment White 19, which is made of clay; CI Pigment White 20, which is made of titanium mica; CI Pigment White 21, which is made of barium sulfate; CI Pigment White 22, which is made of gypsum; CI Pigment White 26, which is made of magnesium oxide and silicon dioxide; CI Pigment White 27, which is made of silicon dioxide; and CI Pigment White 28, which is made of anhydrous calcium silicate. Among these, it is preferable to use CI Pigment White 6, which has excellent color development and opacity. Furthermore, the white colorant may be made from particles having a hollow structure, and known particles with a hollow structure can be used.

[0112] The volume-average particle size of the white colorant is preferably 30 nm to 500 nm, more preferably 50 nm to 450 nm, and even more preferably 200 nm to 400 nm. Setting the volume-average particle size of the white colorant within this range tends to ensure ejection stability from the inkjet head and also tends to improve opacity. In this specification, unless otherwise specified, "volume-average particle diameter" refers to the volume-based particle size distribution, which is the particle diameter at a cumulative distribution of 50 vol%. The volume-average particle diameter is measured using the dynamic light scattering method or the laser diffraction method described in JIS Z8825. Specifically, a particle size analyzer that uses the dynamic light scattering method as its measurement principle (for example, "Microtrac UPA" manufactured by Nikkiso Co., Ltd.) can be used.

[0113] In this specification, the term "white" in relation to white ink compositions, white colorants, etc., does not refer only to pure white, but also includes chromatic and achromatic colors, as well as glossy colors, as long as they are visible as white. Furthermore, it includes inks and colorants that are named and sold in a way that suggests they are white inks or white colorants.

[0114] More quantitatively, "white" refers to a recording that, for example, in CIELAB, is L * Not only colors where L is 100, * is between 60 and 100, and a * and b * This also includes colors that are within ±10 of each other. More specifically, for example, when a white ink composition is recorded in an amount sufficient to adequately cover the surface of a transparent film recording medium with the ink, the brightness (L) of the recorded portion of the recording material is reduced. * ) and chromaticity (a * , b * When the color of the material is measured using a spectrophotometer compliant with CIELAB, it is preferable that the result falls within the above range. A recording with a sufficient coating amount is, for example, 15 mg / inch 2 This is the amount of adhesion. More preferably, 80 ≤ L * ≤100, -4.5 ≤a * ≤ 2, -10 ≤ b * The value is ≤2.5. An example of a transparent film recording medium is the LAG Jet E-1000ZC (manufactured by Lintec Corporation). An example of a spectrophotometer compliant with CIELAB is the Spectrolino (product name, manufactured by GretagMacbeth Corporation), and measurements are taken with the following conditions: D50 light source, observation field of view 2°, density DIN NB, white reference Abs, filter No, and measurement mode Reflectance. Anything other than "white" will be referred to as "non-white."

[0115] To improve the dispersibility of the white colorant in the ink composition, it is preferable to either surface-treat the colorant or incorporate a dispersant.

[0116] The surface treatment of the white colorant is preferably a physical or chemical treatment that directly or indirectly bonds functional groups such as carbonyl groups, carboxyl groups, aldehyde groups, hydroxyl groups, sulfone groups, ammonium groups, and salts thereof to the surface of the colorant. In particular, the surface treatment is more preferably a treatment that modifies the surface of the colorant by oxidizing or sulfonating the surface of the colorant with, for example, ozone, hypochlorous acid, or fuming sulfuric acid.

[0117] When a dispersant is added to a white ink composition, it is preferable to use a dispersant that has both a hydrophobic portion (hydrophobic group) and a hydrophilic portion (hydrophilic group) in its molecular structure. Such a dispersant has the effect of the hydrophobic portion adsorbing to the surface of the colorant particles and the hydrophilic portion orienting towards the aqueous medium side of the ink composition. This action tends to make it possible to include the colorant in the ink composition as a dispersion more stably.

[0118] Such dispersants are not particularly limited, but examples include (meth)acrylic resins and their salts such as poly(meth)acrylic acid, (meth)acrylic acid-acrylonitrile copolymer, (meth)acrylic acid-(meth)acrylic acid ester copolymer, vinyl acetate-(meth)acrylic acid ester copolymer, vinyl acetate-(meth)acrylic acid copolymer, vinylnaphthalene-(meth)acrylic acid copolymer; styrene-(meth)acrylic acid copolymer, styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymer, styrene-α-methylstyrene-(meth)acrylic acid copolymer, styrene-α-methylstyrene Examples of styrene-based resins and their salts include styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymers, styrene-maleic acid copolymers, and styrene-maleic anhydride copolymers; urethane-based resins and their salts that contain urethane bonds formed by the reaction of isocyanate groups and hydroxyl groups, which may be linear and / or branched, and may or may not have a crosslinked structure; polyvinyl alcohols; vinylnaphthalene-maleic acid copolymers and their salts; vinyl acetate-maleic acid ester copolymers and their salts; and water-soluble resins such as vinyl acetate-crotonic acid copolymers and their salts.

[0119] Among these, copolymers of monomers having hydrophobic functional groups and monomers having hydrophilic functional groups, and polymers composed of monomers having both hydrophobic and hydrophilic functional groups are preferred. The copolymer can be in any form, such as random copolymer, block copolymer, alternating copolymer, or graft copolymer. A commercially available dispersant may also be used.

[0120] The dispersant may be used alone or in combination of two or more types. The total content of the dispersant is preferably 10 parts by mass or more and 90 parts by mass or less, more preferably 15 parts by mass or more and 70 parts by mass or less, and even more preferably 20 parts by mass or more and 50 parts by mass or less, per 100 parts by mass of the white colorant. When the content of the dispersant is within the above range per 100 parts by mass of the colorant, the reactivity with the processing solution is better, resulting in a tendency to obtain better image quality, as well as better filling and scratch resistance.

[0121] Among the dispersants exemplified above, it is even more preferable that at least one is selected from anionic dispersant resins. In this case, it is even more preferable that the weight-average molecular weight of the dispersant be 500 or more. Furthermore, it is preferable that it be between 5000 and 100000, and more preferably between 10000 and 50000.

[0122] By using such resin dispersants as dispersants, the dispersion and cohesiveness of the colorants are improved, and it tends to be possible to obtain images with even better dispersion stability and even better image quality. In addition, it is preferable that the viscosity ratio (described later) of the white ink composition can be increased.

[0123] Anionic dispersant resins are resins that exhibit anionic properties because they possess anionic functional groups. Examples of anionic functional groups include carboxyl groups, sulfo groups, and phosphate groups. Among these groups, carboxyl groups are more preferred.

[0124] The dispersant resin preferably has an acid value, preferably 5 mg KOH / g or higher, more preferably 10 to 150 mg KOH / g, and even more preferably 15 to 100 mg KOH / g. Further preferably 20 to 50 mg KOH / g, and even more preferably 25 to 35 mg KOH / g. In this case, it is preferable because it is easier to increase the viscosity ratio (described later) of the white ink composition.

[0125] The acid value can be measured by neutralization potentiometric titration in accordance with JIS K0070. For example, the "AT610" manufactured by Kyoto Electronics Manufacturing Co., Ltd. can be used as the titrator.

[0126] Alternatively, a method may be used in which the particles of the white colorant are coated with a resin or other material to impart dispersibility. Possible methods for coating the white colorant include acid precipitation, phase inversion emulsification, and miniemulsion polymerization.

[0127] The content of the white colorant is preferably 1 to 30% by mass, more preferably 2 to 25% by mass, even more preferably 4 to 20% by mass, particularly preferably 6 to 15% by mass, and most particularly preferably 8 to 12% by mass, based on the total mass of the white ink composition. When the content of the white colorant is within the above range, it tends to be possible to obtain better friction fastness and better color development (whiteness).

[0128] 1.2.2.2 Resin The white ink composition used in the recording method according to this embodiment may contain resin particles or wax. The type and content of the resin can be the same as those for the clear ink composition described later.

[0129] 1.2.2.3 Surfactants The white ink composition used in the recording method according to this embodiment may contain a surfactant. The type and amount of the surfactant can be the same as that of the processing solution described above.

[0130] 1.2.2.4 Organic Solvents The white ink composition used in the recording method according to this embodiment may contain an organic solvent. The type and content of the organic solvent can be the same as those of the processing solution described above.

[0131] 1.2.2.5 Water The white ink composition used in the recording method according to this embodiment is a water-based ink and contains water. The type and amount of water can be the same as that of the processing solution described above.

[0132] 1.2.2.6 Other Ingredients The white ink composition used in the recording method according to this embodiment may further contain various additives as needed. The various additives can be the same as those used in the processing solution described above.

[0133] 1.2.2.7 Physical Properties The surface tension and viscosity of the white ink composition used in the recording method according to this embodiment can be the same as those of the processing solution described above.

[0134] In the white ink composition, when the white ink composition and the above-mentioned processing solution are mixed in a mass ratio of 10:1, the viscosity increase ratio is preferably 5 times or more, more preferably 10 times or more, even more preferably 20 times or more, particularly preferably 30 times or more, and most particularly preferably 40 times or more. The upper limit of the viscosity increase ratio is preferably less than 80 times, more preferably less than 60 times, and even more preferably less than 50 times. When the viscosity increase ratio is within the above range, better image quality tends to be obtained.

[0135] Here, the "thickness ratio" in the white ink composition is defined as the ratio (multiplier) of the viscosity of the mixed solution to the viscosity of the white ink composition before mixing, obtained by mixing and stirring the white ink composition and processing solution used in the recording method in a mass ratio of 10:1. Viscosity is measured at 20°C. In other words, the thickness ratio is the ratio of the viscosity after mixing to the viscosity before mixing. Note that depending on the composition of the processing solution and ink, the thickness increase may be less than 1.0 times, and the viscosity may decrease, but it is still referred to as the thickness ratio. Viscosity can be measured using a rheometer.

[0136] In a white ink composition, the viscosity can be adjusted by adjusting the type and content of colorants (including resin dispersants) and resins. In particular, adjusting the viscosity by adjusting the type and content of colorants (including resin dispersants) is preferable because it is easier to adjust.

[0137] The absolute difference between the viscosity increase ratio when the white ink composition is mixed with the processing solution in a mass ratio of 10:1 and the viscosity increase ratio when the clear ink composition is mixed with the processing solution in a mass ratio of 10:1 is preferably 60 times or less, more preferably 50 times or less, even more preferably 30 times or less, particularly preferably 20 times or less, and most particularly preferably 10 times or less. When the absolute value of this difference is within the above range, streaks caused by reactivity can be reduced effectively, and blurring at the boundaries of color images tends to be reduced effectively. The lower limit of the absolute value of the difference is not particularly limited, but may be 0 times or more, or 5 times or more.

[0138] 1.3 Non-white ink application process The recording method according to this embodiment includes a non-white ink application step in which a non-white ink composition containing a non-white colorant is ejected from an inkjet head and adhered to a recording medium.

[0139] 1.3.1 Adhesion Pattern The amount of non-white ink composition applied is not particularly limited, but is generally 1 to 20 mg / inch per unit area of ​​the recording medium. 2 Preferably, 2 to 15 mg / inch 2 More preferably, 3-12 mg / inch 2 More preferably, 5-10 mg / inch 2 This is particularly preferable. The maximum amount of non-white ink composition that adheres may be within the above range.

[0140] The maximum weight per drop of the non-white ink composition is preferably 20 ng or less, more preferably 15 ng or less, even more preferably 10 ng or less, and even more preferably 8 ng or less. The lower limit of the maximum weight per droplet of the non-white ink composition is not particularly limited, but is preferably 1 ng or more, more preferably 3 ng or more, and even more preferably 5 ng or more.

[0141] Furthermore, the duty cycle in the non-white ink composition is preferably 50 or higher, more preferably 60 or higher, even more preferably 70 or higher, and particularly preferably 80 or higher.

[0142] In the recording method according to this embodiment, it is preferable to perform a interpolation process on the area of ​​the image to be recorded by a non-discharge nozzle among the plurality of nozzles of the inkjet head that discharges the non-white ink composition, using a nozzle that is not a non-discharge nozzle of the non-white ink composition. Performing such a process tends to reduce streaks on the color image. Note that streaks on color images tend to be more noticeable than streaks on white images. On the other hand, even if this process is performed alone, streaks caused by reactivity cannot be reduced unless clear ink is applied to the image area at the nozzle location where the white ink failed to be ejected.

[0143] Similar to the white ink composition described above, nozzles that are not non-discharge nozzles and are not used for complementary processing are preferably nozzles adjacent to non-discharge nozzles, from the viewpoint of effectively performing complementary processing.

[0144] The amount of non-white ink composition adhering to the nozzle position where the interpolation process is performed is not particularly limited, but is 2 to 25 mg / inch per unit area of ​​the recording medium. 2 Preferably, 3-20 mg / inch 2 More preferably, 5-15 mg / inch 2 More preferably, 7-12 mg / inch 2 This is particularly preferable. The maximum amount of non-white ink composition that adheres may be within the above range.

[0145] The amount of non-white ink composition attached to the nozzle position where the complementary treatment is performed is preferably 1.05 times or more, more preferably 1.10 times or more, even more preferably 1.15 times or more, particularly preferably 1.20 times or more, and most particularly preferably 1.25 times or more, compared to the amount of non-white ink composition attached to the nozzle position where the complementary treatment is not performed (the amount of non-white ink composition attached in the non-white ink attachment process).

[0146] The maximum weight per drop of the non-white ink composition in the nozzle where the complementary treatment is performed is preferably 20 ng or less, more preferably 15 ng or less, even more preferably 12 ng or less, and even more preferably 10 ng or less. The lower limit of the maximum weight per drop of the non-white ink composition in the nozzle where the complementary treatment is performed is not particularly limited, but is preferably 1 ng or more, more preferably 3 ng or more, even more preferably 5 ng or more, and particularly preferably 7 ng or more.

[0147] The duty cycle of the non-white ink composition at the nozzle position where the complementary processing is performed is preferably 80 or higher, more preferably 90 or higher, and even more preferably 100 or higher.

[0148] 1.3.2 Non-white ink compositions The following describes each component contained in the non-white ink composition used in the recording method according to this embodiment.

[0149] 1.3.2.1 Non-white colorants The non-white ink composition used in the recording method according to this embodiment contains a non-white colorant. The non-white colorant is a colorant other than the white colorant, and examples include non-white pigments and dyes. As pigments, for example, inorganic pigments and organic pigments can be used.

[0150] While there are no particular limitations on the inorganic pigments, examples include carbon blacks such as CI Pigment Black 6 (Lamp Black, Vegetable Black), CI Pigment Black 7 (Furnace Black, Channel Black, Thermal Black, Acetylene Black), CI Pigment Black 8 (Charcoal Black), and CI Pigment Black 10 (Graphite).

[0151] Commercially available carbon black products include Mitsubishi Chemical Corporation's No. 2300, 900, MCF88, No. 20B, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100, No. 2200B, etc.; and Degussa's Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Pritex 35, U, V, 140U, etc. Examples include Shallblack 6, 5, 4A, 4, 250, etc.; Columbia Carbon's Conductex SC, Raven 1255, 5750, 5250, 5000, 3500, 1255, 700, etc.; and Cabot's Regal 400R, 330R, 660R, Mogul L, Monarch 700, 800, 880, 900, 1000, 1100, 1300, 1400, Elftex 12, etc.

[0152] Examples of organic pigments include quinacridone pigments, quinacridone quinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, ancenthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimimidazolone pigments, isoindolinone pigments, azomethine pigments, or azo pigments.

[0153] Specific examples of organic pigments include the following:

[0154] Examples of cyan pigments include CI Pigment Blue 1, 2, 3, 15:3, 15:4, 15:34, 16, 22, 60, etc.; CI Bat Blue 4, 60, etc. Preferably, one or more mixtures selected from the group consisting of CI Pigment Blue 15:3, 15:4, and 60 can be exemplified.

[0155] Examples of magenta pigments include CI Pigment Red 5, 7, 12, 48(Ca), 48(Mn), 57(Ca), 57:1, 112, 122, 123, 168, 184, 202, and CI Pigment Violet 19. Preferably, one or more mixtures selected from the group consisting of CI Pigment Red 122, 202, and 209, and CI Pigment Violet 19 can be exemplified.

[0156] Examples of yellow pigments include CI Pigment Yellow 1, 2, 3, 12, 13, 14C, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 119, 110, 114, 128, 129, 138, 150, 151, 154, 155, 180, 185, etc. Preferably, one or more mixtures selected from the group consisting of CI Pigment Yellow 74, 109, 110, 128, 138, 150, and 180 can be exemplified.

[0157] Other colored pigments can also be used. For example, orange pigment and green pigment can be used.

[0158] Pigments may be used individually or in combination of two or more types.

[0159] For pigments used as non-white colorants, it is preferable to either surface-treat the colorant or incorporate a dispersant to improve dispersibility in the ink composition, similar to the white colorants described above. The type and amount of dispersant can be the same as for the white ink composition described above. The total content of the dispersant is preferably 30 parts by mass or more and 90 parts by mass or less, more preferably 40 parts by mass or more and 80 parts by mass or less, and even more preferably 50 parts by mass or more and 70 parts by mass or less, per 100 parts by mass of the non-white colorant.

[0160] The dyes used are not particularly limited and include acid dyes, direct dyes, reactive dyes, and basic dyes. Dyes may be used individually or in combination of two or more.

[0161] There are no particular restrictions on the dyes used, but for example, CI Acid Yellow 17, 23, 42, 44, 79, 142; CI Acid Red 52, 80, 82, 249, 254, 289; CI Acid Blue 9, 45, 249; CI Acid Black 1, 2, 24, 94; CI Food Black 1, 2; CI Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 14 Examples include 2, 144, 173, CI Direct Red 1, 4, 9, 80, 81, 225, 227, CI Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, CI Direct Black 19, 38, 51, 71, 154, 168, 171, 195, CI Reactive Red 14, 32, 55, 79, 249, and CI Reactive Black 3, 4, 35.

[0162] The content of the non-white colorant is preferably 0.1% to 15% by mass, more preferably 1% to 10% by mass, and even more preferably 2% to 6% by mass, based on the total mass of the non-white ink composition.

[0163] 1.3.2.2 Resin The non-white ink composition used in the recording method according to this embodiment may contain resins such as resin particles or wax. The type and content of the resin can be the same as those for the clear ink composition described later.

[0164] 1.3.2.3 Surfactants The non-white ink composition used in the recording method according to this embodiment may contain a surfactant. The type and amount of the surfactant can be the same as that of the processing solution described above.

[0165] 1.3.2.4 Organic Solvents The non-white ink composition used in the recording method according to this embodiment may contain an organic solvent. The type and content of the organic solvent can be the same as those of the processing solution described above.

[0166] 1.3.2.5 Water The non-white ink composition used in the recording method according to this embodiment is a water-based ink and contains water. The type and amount of water can be the same as that of the processing solution described above.

[0167] 1.3.2.6 Other Ingredients The non-white ink composition used in the recording method according to this embodiment may further contain various additives as needed. The various additives can be the same as those used in the processing solution described above.

[0168] 1.3.2.7 Physical Properties The surface tension and viscosity of the non-white ink composition used in the recording method according to this embodiment can be the same as those of the processing solution described above.

[0169] In the case of a non-white ink composition, the viscosity increase ratio when the non-white ink composition and the above-mentioned processing solution are mixed in a mass ratio of 10:1 can be the same as that when the white ink composition and the above-mentioned processing solution are mixed in a mass ratio of 10:1.

[0170] The absolute difference between the viscosity increase ratio when a non-white ink composition is mixed with processing solution in a mass ratio of 10:1 and the viscosity increase ratio when a clear ink composition is mixed with processing solution in a mass ratio of 10:1 can be the same as the absolute difference between the viscosity increase ratio when a white ink composition is mixed with processing solution in a mass ratio of 10:1 and the viscosity increase ratio when a clear ink composition is mixed with processing solution in a mass ratio of 10:1.

[0171] 1.4 Clear ink application process The recording method according to this embodiment includes a clear ink application step in which a clear ink composition containing resin is ejected from an inkjet head and attached to a recording medium.

[0172] 1.4.1 Adhesion Pattern The recording method according to this embodiment involves applying a clear ink composition to the area of ​​the image to be recorded by a non-ejecting nozzle among the multiple nozzles of an inkjet head that ejects the above-mentioned white ink composition (hereinafter also referred to as the "white ink non-ejecting area"). By applying clear ink to the image area at the nozzle position where the white ink was not ejected, the unreacted reaction solution reacts with the clear ink, suppressing the progress of the color ink reaction and reducing the occurrence of streaks caused by the reactivity.

[0173] The amount of clear ink composition applied is not particularly limited, but is generally 1 to 20 mg / inch per unit area of ​​the recording medium. 2 Preferably, 2 to 16 mg / inch 2 More preferably, 3-12 mg / inch 2 More preferably, 4-10 mg / inch 2 This is particularly preferable. The maximum amount of clear ink composition that adheres may be within the above range.

[0174] The maximum weight per drop of the clear ink composition is preferably 20 ng or less, more preferably 15 ng or less, even more preferably 10 ng or less, and even more preferably 8 ng or less. The lower limit is not particularly limited, but is preferably 1 ng or more, more preferably 3 ng or more, and even more preferably 5 ng or more. On the other hand, the maximum weight per drop of the clear ink composition is 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. The lower limit is not particularly limited, but is preferably 5 ng or more, more preferably 8 ng or more, and even more preferably 10 ng or more.

[0175] The duty cycle in the clear ink composition is preferably 20 or higher, more preferably 30 or higher, and even more preferably 40 or higher. Furthermore, the duty cycle in the clear ink composition is preferably 80 or lower, more preferably 60 or lower, and even more preferably 50 or lower.

[0176] Furthermore, the adhesion of the clear ink composition is not limited to the areas where white ink is not ejected; it may also be applied to areas other than those where white ink is not ejected.

[0177] In this case, it is preferable that the amount of clear ink composition adhering to the area of ​​the image to be recorded by the non-ejecting nozzle among the multiple nozzles of the inkjet head that ejects the white ink composition (the area where the white ink is not ejected) is greater than the amount of clear ink composition adhering to areas other than that area. This allows for appropriate adjustment of the amount of unreacted reaction liquid in the area where the white ink is not ejected, reducing the occurrence of streaks caused by reactivity and tending to further improve abrasion resistance.

[0178] The order in which the clear ink composition is applied to the areas where the white ink does not discharge, i.e., the order of each step, is not particularly limited, and the clear ink application step may be performed after the white ink application step and before or after the non-white ink application step. Even with such an order, the rate of reaction of the color ink can be suppressed, and streaks caused by the reactivity can be effectively reduced. Preferably, the clear ink application step is performed after the white ink application step and before the non-white ink application step. With this sequence, the unreacted reaction solution and the clear ink can react before the color ink reaction progresses, which tends to further suppress the progress of the color ink reaction and better reduce streaks caused by the reactivity.

[0179] 1.4.2 Clear Ink Composition The following describes each component contained in the clear ink composition used in the recording method according to this embodiment. Note that the clear ink composition is not an ink composition used to color the recording medium, but a coating liquid used together with the coloring ink composition. The clear ink composition may contain colorants such as pigments, but it is preferably 0.2% by mass or less, more preferably 0.1% by mass or less, even more preferably 0.05% by mass or less, and the lower limit is 0% by mass, based on the total mass of the clear ink composition. It is preferable that the clear ink composition does not contain colorants.

[0180] 1.4.2.1 Resin The clear ink composition used in the recording method according to this embodiment contains a resin. Examples of the resin include resin particles that improve the adhesion and abrasion resistance of the ink components and function as a so-called fixing resin, and waxes that have the function of improving abrasion resistance, etc., by imparting smoothness to the formed image. Preferably, the resin is a resin that reacts with the processing liquid composition described above.

[0181] (Resin particles) 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, epoxy resins, vinyl chloride resins, vinyl chloride-vinyl acetate copolymers, and ethylene vinyl acetate resins. Among these, urethane resins, acrylic resins, polyolefin resins, and polyester resins are preferred. These resin particles are often handled in emulsion form, but they may also be in powder form. Furthermore, the resin particles can be used individually or in combination of two or more types.

[0182] Urethane resins are a general term for resins that have urethane bonds. In addition to urethane bonds, urethane resins may also include polyether-type urethane resins containing ether bonds in the main chain, polyester-type urethane resins containing ester bonds in the main chain, and polycarbonate-type urethane resins containing carbonate bonds in the main chain. Furthermore, commercially available urethane resins may be used, such as Superflex 460, 460s, 840, E-4000 (product names, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Rezamin D-1060, D-2020, D-4080, D-4200, D-6300, D-6455 (product names, manufactured by Dainichi Seika Kogyo Co., Ltd.), Takelac WS-6021, W-512-A-6 (product names, manufactured by Mitsui Chemicals Polyurethane Co., Ltd.), Sankyuar 2710 (product name, manufactured by LUBRIZOL), and Permarin UA-150 (product name, manufactured by Sanyo Chemical Industries, Ltd.).

[0183] Acrylic resins are a general term for polymers obtained by polymerizing at least one acrylic monomer, such as (meth)acrylic acid or (meth)acrylic acid ester. Examples include resins obtained from acrylic monomers and copolymers of acrylic monomers with other monomers. For example, acrylic-vinyl resins, which are copolymers of acrylic monomers and vinyl monomers, are examples. Examples of vinyl monomers include styrene.

[0184] Acrylic monomers such as acrylamide and acrylonitrile can also be used. For resin emulsions made from acrylic resins, commercially available products may be used, for example, selected from FK-854 (trade name, manufactured by Chuo Rika Kogyo Co., Ltd.), Movinyl 952B, 718A (trade name, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Nipol LX852, LX874 (trade name, manufactured by Nippon Zeon Co., Ltd.).

[0185] In this specification, the acrylic resin may be a styrene-acrylic resin as described later. Also, in this specification, (meth)acrylic means acrylic or methacrylic.

[0186] Styrene-acrylic resins are copolymers obtained from styrene monomers and (meth)acrylic monomers, and examples 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. For the styrene-acrylic resin, commercially available products 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 names, manufactured by BASF), Movinyl 966A, 975N (product names, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Vinibran 2586 (manufactured by Nisshin Chemical Industry Co., Ltd.), etc.

[0187] Polyolefin resins have olefins such as ethylene, propylene, and butylene as their structural framework, and known types can be appropriately selected and used. Commercially available olefin resins can be used, for example, Arrowbase CB-1200, CD-1200 (trade names, manufactured by Unitika Ltd.).

[0188] Furthermore, the resin particles may be supplied in the form of an emulsion. Examples of commercially available resin emulsions include Microgel E-1002, E-5002 (product names of Nippon Paint Co., Ltd., styrene-acrylic resin emulsion), Boncoat 4001 (product name of DIC Corporation, acrylic resin emulsion), Boncoat 5454 (product name of DIC Corporation, styrene-acrylic resin emulsion), Polysol AM-710, AM-920, AM-2300, AP-4735, AT-860, PSASE-4210E (acrylic resin emulsion), and Poly 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.), Saibinol SK-200 (product name, acrylic resin emulsion, manufactured by Saiden Chemical Co., Ltd.) AE-120A (JSR product name, acrylic resin emulsion), AE373D (E-Tech product name, carboxy-modified styrene-acrylic resin emulsion), Seikadine 1900W (Dainichi Seika Kogyo product name, ethylene-vinyl acetate resin emulsion), Vinibran 2682 (acrylic resin emulsion), Vinibran 2886 (vinyl acetate-acrylic resin emulsion), Vinibran 5202 (acrylic acetate resin emulsion) (Nisshin Chemical Industry product name), Elitel KA-5071S, KT-8803, KT-9204, KT-870 1. KT-8904, KT-0507 (Unitika Corporation product names, polyester resin emulsion), Hi-Tec SN-2002 (Toho Chemical Co., Ltd. product name, polyester resin emulsion), Takelac W-6020, W-635, W-6061, W-605, W-635, W-6021 (Mitsui Chemicals Polyurethane Co., Ltd. product names, urethane resin emulsion), Superflex 870, 800, 150, 420, 460, 470, 610, 700 (Daiichi Kogyo Seiyaku Co., Ltd. product names, urethane resin emulsion), Permarin UA-150 (Sanyo Chemical Industries, Ltd.Urethane resin emulsion), SunCure 2710 (manufactured by Lubrizol Japan, urethane resin emulsion), NeoRez R-9660, R-9637, R-940 (manufactured by Kusumoto Kasei Co., Ltd., urethane resin emulsion), Adekabon Titer HUX-380, 290K (manufactured by ADEKA Corporation, urethane resin emulsion), Movinyl 966A, Movinyl 7320 (manufactured by Nippon Synthetic Chemical Co., Ltd.), Joncryl 7100, 390, 711, 511, 7001, 632, 741, 450, 840, 74J, HRC-1645J, 734, 852, 7600, 775, 537J, 1535, PDX-7 You may also select and use from among 630A, 352J, 352D, PDX-7145, 538J, 7640, 7641, 631, 790, 780, 7610 (all manufactured by BASF), NK Binder R-5HN (manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), Hydran WLS-210 (non-crosslinked polyurethane: manufactured by DIC Corporation), Joncryl 7610 (manufactured by BASF), etc.

[0189] The glass transition temperature (Tg) of the resin particles is preferably between -50°C and 200°C, more preferably between 0°C and 150°C, and even more preferably between 50°C and 100°C. A temperature between 50°C and 80°C is particularly preferred. When the glass transition temperature (Tg) of the resin particles is within the above range, the abrasion resistance tends to be superior. The glass transition temperature is measured, for example, using a differential scanning calorimeter "DSC7000" manufactured by Hitachi High-Tech Science Corporation, in accordance with JIS K7121 (Method for measuring the transition temperature of plastics).

[0190] The volume-average particle diameter of the resin particles is preferably 10 nm to 300 nm, more preferably 30 nm to 300 nm, even more preferably 30 nm to 250 nm, and particularly preferably 40 nm to 220 nm. The volume-average particle diameter can be measured by the method described above.

[0191] The resin of the resin particles preferably has an acid value of 70 mgKOH / g or less, more preferably 60 mgKOH / g or less, even more preferably 50 mgKOH / g or less, and particularly preferably 40 mgKOH / g or less. The lower limit of the acid value is 0 mgKOH / g or more, preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, even more preferably 20 mgKOH / g or more, and particularly preferably 30 mgKOH / g or more. The acid value can be measured by the method described above.

[0192] When resin particles are included in the clear ink composition, the content is 1% by mass or more and 20% by mass or less, preferably 3% by mass or more and 15% by mass or less, and more preferably 5% by mass or more and 10% by mass or less, as solid content, relative to the total mass of the clear ink composition.

[0193] (wax) The components of the wax can be, for example, plant 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, which can be used individually or in combination of multiple types. Among these, polyolefin waxes (especially polyethylene wax and polypropylene wax) and paraffin wax are preferred from the viewpoint of superior abrasion resistance.

[0194] Commercially available waxes can also be used, such as Nopcoat PEM-17 (product name, manufactured by Sunnopco Co., Ltd.), Chemipearl W4005 (product name, manufactured by Mitsui Chemicals, Inc.), and AQUACER 515, 539, and 593 (all product names, manufactured by Big Chemie Japan Co., Ltd.).

[0195] Furthermore, when the recording method includes a heating process, it is preferable to use a wax with a melting point of 50°C to 200°C, more preferably 70°C to 180°C, and even more preferably 90°C to 150°C, in order to prevent the wax from melting too much and degrading its performance.

[0196] The wax may be supplied in the form of an emulsion or suspension. The wax content is 0.1% to 10% by mass, more preferably 0.5% to 5% by mass, and even more preferably 0.5% to 2% by mass, based on solid content relative to the total mass of the clear ink composition. When the wax content is within the above range, the wax tends to exhibit its functions well.

[0197] 1.4.2.2 Surfactants The clear ink composition used in the recording method according to this embodiment may contain a surfactant. The type and amount of the surfactant can be the same as that of the processing solution described above.

[0198] 1.4.2.3 Organic Solvents The clear ink composition used in the recording method according to this embodiment may contain an organic solvent. The type and content of the organic solvent can be the same as those of the processing solution described above.

[0199] 1.4.2.4 Water The clear ink composition used in the recording method according to this embodiment is a water-based ink and contains water. The type and amount of water can be the same as that of the processing solution described above.

[0200] 1.4.2.5 Other ingredients The clear ink composition used in the recording method according to this embodiment may further contain various additives as needed. The various additives can be the same as those used in the processing solution described above.

[0201] 1.4.2.6 Physical Properties The surface tension and viscosity of the clear ink composition used in the recording method according to this embodiment can be the same as those of the processing solution described above.

[0202] The clear ink composition is preferably a clear ink composition that thickens when mixed with the processing liquid described above. With such a clear ink composition, the amount of unreacted reaction liquid in the white ink non-discharge region can be appropriately adjusted, and the occurrence of streaks caused by reactivity tends to be further reduced. As a clear ink composition that thickens when mixed with the processing liquid described above, it is preferable, for example, to contain a resin that reacts with the processing liquid composition described above.

[0203] In the clear ink composition, when the clear ink composition is mixed with the above-mentioned processing liquid in a mass ratio of 10:1, the viscosity increase ratio is preferably 3 times or more, more preferably 10 times or more, even more preferably 20 times or more, particularly preferably 30 times or more, and most preferably 50 times or more. The upper limit of the viscosity increase ratio is preferably less than 150 times, more preferably less than 120 times, even more preferably less than 100 times, and particularly preferably less than 80 times. When the viscosity increase ratio is within the above range, the occurrence of streaks caused by reactivity tends to be further reduced.

[0204] 1.5 Primary drying process The recording method according to this embodiment may include a drying step (primary drying step) for drying the recording medium. Having such a drying step allows the ink (hereinafter, when these ink compositions are not particularly distinguished, they will also simply be referred to as "ink") to dry earlier, which tends to improve scratch resistance and image quality.

[0205] The primary drying process involves heating or blowing air onto the recording medium to quickly dry the ink. The primary drying process dries at least a portion of the solvent component of the ink that has adhered to the recording medium, to the extent that it reduces the flow of the ink. The primary drying process may be carried out so that the ink adheres to the heated recording medium, or it may be carried out early after adhesion to accelerate drying.

[0206] In the primary drying process, it is preferable that the ink droplets that have landed on the recording medium begin to dry no later than 0.5 seconds after landing. The drying unit (drying mechanism) for drying the ink on the recording medium is not particularly limited, but examples include platen heaters, hot air heaters, IR heaters, etc., which have a heating function, and blowers, etc., which do not have a heating function.

[0207] Types of drying mechanisms include conduction type, which heats the recording medium by transferring heat from a component in contact with the recording medium to the recording medium; radiation type, which heats the recording medium by radiating radiation such as IR to the recording medium; and airflow type, which blows air towards the recording medium.

[0208] The blower method (blowing process) includes methods that heat the recording medium while applying hot air, and methods that promote ink drying with room temperature air without heating. The method without heating is preferable because it suppresses the drying of ink in the inkjet head nozzles and the resulting decrease in ejection stability. It is also preferable to use the blower method in combination with either the conduction method or the radiation method. When used in combination, the blower method may also be a method without heating, which is preferable.

[0209] In the primary drying process, the surface temperature of the recording medium portion facing the inkjet head is preferably 60°C or lower, more preferably 55°C or lower. Furthermore, it is preferably 50°C or lower, even more preferably 45°C or lower. On the other hand, it is preferably 20°C or higher, more preferably 25°C or higher, even more preferably 30°C or higher, particularly preferably 35°C or higher, and even more particularly preferably 40°C or higher. Furthermore, it is preferably 30 to 60°C, even more preferably 35 to 55°C. Even more preferably 40 to 50°C.

[0210] When the surface temperature of the recording medium is within the above range, drying properties are improved, and the abrasion resistance of the resulting recorded material tends to be improved. Furthermore, clogging recovery, ejection stability, and color development are also better, which is preferable.

[0211] Furthermore, the primary drying process may be omitted, or the primary drying process may not involve heating. In this case, the surface temperature of the recording medium on the platen should remain below the above range.

[0212] Furthermore, when using a fan-type system, the wind speed near the recording medium is preferably 0.2 m / s or more, more preferably 0.5 m / s or more, even more preferably 1.0 m / s or more, particularly preferably 1.5 m / s or more, and most particularly preferably 2.0 m / s or more. On the other hand, it is preferably 20 m / s or less, more preferably 15 m / s or less, even more preferably 10 m / s or less, and particularly preferably 5 m / s or less. Furthermore, a speed of 0.5 to 10 m / s is preferred, 1 to 4 m / s is more preferred, and 2 to 3 m / s is even more preferred. The air temperature is preferably 45°C or lower, more preferably 40°C or lower, even more preferably 32°C or lower, and particularly preferably 20-27°C.

[0213] 1.6 Secondary drying process The recording method according to this embodiment may include a heating step (secondary heating step) for heating a recording medium to which an ink composition has been attached. The secondary heating step is a step of heating the recording medium sufficiently to complete the recording and allow the recorded material to be used. The secondary heating step is also a step of heating the solvent components of the ink and the fixing resin contained in the ink to flatten the ink coating film.

[0214] The secondary heating step is preferably started more than 0.5 seconds after the ink adheres to the recording medium. For example, it is preferable to start heating a recording area of ​​the recording medium more than 0.5 seconds after the ink has completely adhered to that area.

[0215] The surface temperature of the recording medium in the secondary heating step is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 70°C or higher. In the secondary heating step, heating the surface temperature of the recording medium to 60°C or higher tends to result in excellent drying properties and better moisture resistance and friction resistance. The upper limit is preferably 100°C or lower, and more preferably 90°C or lower.

[0216] Furthermore, the secondary heating mechanism can be a conduction type, a radiation type, a forced-air type, or the like.

[0217] 2. Recording device A recording device according to one embodiment of the present invention is a recording device that performs recording by the recording method described above, and comprises the above-described processing liquid, a white ink composition, a non-white ink composition, a clear ink composition, an adhesion mechanism that performs a processing liquid adhesion step, an inkjet head that performs a white ink adhesion step, an inkjet head that performs a non-white ink adhesion step, and an inkjet head that performs a white clear ink adhesion step.

[0218] According to the recording device of this embodiment, recording is performed by the recording method described above, and streaks caused by reactivity can be effectively reduced.

[0219] Figure 1 is a schematic front view showing an example of a recording device according to this embodiment. In Figures 1 and 2, XYZ Cartesian coordinates with the Z-axis as the vertical axis are shown to clarify the arrangement of the various parts of the device. In the following explanation, the direction in which each coordinate axis (arrow) points will be treated as the positive direction, and the opposite direction will be treated as the negative direction. The recording device shown in Figure 1 is a serial recording device, but since the transport of the recording medium is performed in a direction along the scanning axis, it is also called a lateral recording device.

[0220] The recording device 100 includes a host device 200 that generates print data from image data (bitmap data) received from an external device such as a personal computer, and a printer unit 300 that prints an image based on the print data received from the host device 200. The printer unit 300 transports a long sheet S roll-to-roll and prints an image on the surface of the sheet S using an inkjet method.

[0221] As shown in Figure 1, the printer unit 300 includes a main body case 1 having a roughly rectangular parallelepiped shape. Inside the main body case 1 are a feeding unit 2 that feeds out the sheet S from a roll R1 on which the sheet S is wound, a printing chamber 3 that prints by ejecting ink onto the surface of the fed-out sheet S, a drying unit 4 that dries the sheet S to which the ink has adhered, and a winding unit 5 that winds the dried sheet S into a roll R2.

[0222] More specifically, the inside of the main case 1 is divided vertically in the Z-axis direction by a flat base plate 6 arranged parallel to the XY plane (i.e., horizontally), with the upper part of the base plate 6 being the printing chamber 3. Approximately in the center of the printing chamber 3, a platen 30 is fixed to the upper surface of the base plate 6. The platen 30 has a rectangular shape, and its upper surface, which is parallel to the XY plane, supports the sheet S from below. The recording unit 31 then prints on the surface of the sheet S supported on the platen 30.

[0223] On the other hand, the dispensing section 2, drying section 4, and winding section 5 are located on the lower side of the base 6. The dispensing section 2 is located on the lower side of the platen 30 in the negative X-axis direction (down to the left in Figure 1) and is equipped with a rotatable dispensing shaft 21. The sheet S is wound around this dispensing shaft 21 and supports the roll R1. The winding section 5 is located on the lower side of the platen 30 in the positive X-axis direction (down to the right in Figure 1) and is equipped with a rotatable winding shaft 51. The sheet S is wound around this winding shaft 51 and supports the roll R2. The drying section 4 is located directly below the platen 30, between the dispensing section 2 and the winding section 5 in the X-axis direction.

[0224] The sheet S, fed from the feeding shaft 21 of the feeding unit 2, is guided by rollers 71-77 and passes sequentially through the printing chamber 3 and the drying unit 4 before being wound onto the winding shaft 51 of the winding unit 5. The rollers 72 and 73 are arranged in a straight line in the X-axis direction (i.e., horizontally) on either side of the platen 30, and their tops are positioned so that they are at the same height as the top surface of the platen 30 (the surface that supports the sheet S). Therefore, the sheet S wound onto roller 72 moves horizontally (in the X-axis direction) while sliding against the top surface of the platen 30 until it reaches roller 73.

[0225] In the printing chamber 3, the printing process onto the sheet S is performed by a recording unit 31 located above the platen 30. This recording unit 31 prints an image onto the surface of the sheet S by ejecting the aforementioned processing liquid, as well as the white ink composition, non-white ink composition, and clear ink composition onto the surface of the sheet S. Here, a cartridge mounting section 8 is provided at the negative X-axis end (left end in Figure 1) of the printing chamber 3, and a processing liquid cartridge 81 for storing the aforementioned processing liquid and a plurality of ink cartridges 82 for storing the aforementioned white ink composition, non-white ink composition, and clear ink composition are detachably mounted in the cartridge mounting section 8. The recording unit 31 is capable of ejecting the processing liquid supplied from the processing liquid cartridge 81 and each ink composition supplied from the ink cartridges 82 onto the surface of the sheet S using an inkjet method.

[0226] Figure 2 is a bottom view partially showing the configuration of the recording unit. Here, the details of the recording unit 31 will be explained using Figures 1 and 2. The recording unit 31 has a carriage 32, a flat support plate 33 attached to the lower surface of the carriage 32, and inkjet heads 34 and 35 attached to the lower surface of the support plate 33. On the lower surface of the support plate 33, four inkjet heads 35 and one inkjet head 34 are arranged at equal pitches in the X-axis direction, and multiple nozzles N are arranged parallel to each other in the Y-axis direction in each inkjet head 34 and 35. The inkjet head 34 ejects processing liquid from the nozzles N, and each of the four inkjet heads 35 ejects different inks from the nozzles N, namely a white ink composition, a non-white ink composition, and a clear ink composition.

[0227] An inkjet head that ejects the processing liquid is an adhesion mechanism that performs the processing liquid adhesion step described above, an inkjet head that ejects the white ink composition is an inkjet head that performs the white ink adhesion step described above, an inkjet head that ejects the non-white ink composition is an inkjet head that performs the non-white ink adhesion step described above, and an inkjet head that ejects the clear ink composition is an inkjet head that performs the clear ink adhesion step described above. The adhesion mechanism that performs the processing liquid adhesion step is not limited to an inkjet head, but may be a roller, bar, various sprays, etc., which are not shown.

[0228] In Figures 1 and 2, multiple inkjet heads, each having a row of nozzles N, are shown. However, a single inkjet head with multiple nozzles N may also be used. In this case, each nozzle N that ejects ink or processing liquid is considered to be a separate inkjet head.

[0229] Returning to Figure 1, let's continue the explanation. The carriage 32 of the recording unit 31, configured as described above, is movable integrally with the support plate 33 and the inkjet heads 34 and 35. In other words, an X-axis guide rail 37 is provided inside the printing chamber 3, extending parallel to the X-axis direction, and when the carriage 32 receives the driving force from the X-axis motor, it moves in the X-axis direction along the X-axis guide rail 37.

[0230] The recording unit 31 then prints an image onto the surface of the sheet S, which stops on the upper surface of the platen 30, by ejecting processing liquid and ink from the recording heads 34 and 35 while moving the carriage 32 back and forth above the platen 30 in the X-axis direction (main scanning direction). The recording unit 31 performs a scan in which it ejects processing liquid from the nozzle N of the recording head 34 onto the surface of the sheet S while moving the carriage 32 in a forward direction parallel to the X-axis. Preferably, in the same scan as this, a scan is performed in which a white ink composition and / or a clear ink composition are ejected from the nozzle N of each recording head 35 onto the surface of the sheet S in the same scanning area. Subsequently, the recording unit 31 ejects ink such as a non-white ink composition from the nozzle N of each recording head 35 onto the surface of the sheet S while moving the carriage 32 in a return direction parallel to the X-axis. As a result, on the surface of sheet S, multiple lines of image extending parallel to the X-axis are arranged in the Y-axis direction, creating a two-dimensional image that makes up one frame. In addition, the colorants and resin components of the ink that make up the two-dimensional image aggregate due to the action of the processing solution and are fixed to the surface of sheet S.

[0231] The printing of one frame as described above is repeatedly performed while intermittently moving the sheet S in the X-axis direction. Specifically, a predetermined area covering almost the entire upper surface of the platen 30 is the printing area. The sheet S is then intermittently transported in the X-axis direction using a distance corresponding to the length of this printing area in the X-axis direction (intermittent transport distance) as the unit, and one frame is printed on the sheet S that stops on the upper surface of the platen 30 during the intermittent transport. In other words, once one frame of printing is completed on the sheet S stopped on the platen 30, the sheet S is transported in the X-axis direction by the intermittent transport distance, and the unprinted side of the sheet S stops on the platen 30. Subsequently, one frame of printing is performed on this unprinted side, and once this is completed, the sheet S is transported again in the X-axis direction by the intermittent transport distance. This series of operations is then repeated.

[0232] Furthermore, in order to keep the sheet S, which is stopped on the upper surface of the platen 30, flat during intermittent transport, the platen 30 is equipped with a mechanism to suck the sheet S that is stopped on its upper surface. Specifically, numerous suction holes (not shown) are opened on the upper surface of the platen 30, and a suction unit 38 is attached to the lower surface of the platen 30. When the suction unit 38 operates, negative pressure is generated at the suction holes on the upper surface of the platen 30, and the sheet S is sucked onto the upper surface of the platen 30. While the sheet S is stopped on the platen 30 for printing, the suction unit 38 sucks the sheet S to keep it flat. On the other hand, when printing is finished, the suction unit 38 stops sucking the sheet S, enabling smooth transport of the sheet S.

[0233] A heater 39 may be attached to the underside of the platen 30. This heater 39 can heat the platen 30 to a predetermined temperature (e.g., 30°C) as needed. This allows the sheet S to be subjected to printing by the inkjet heads 34 and 35 while being pre-dried by the heat of the platen 30.

[0234] However, in the recording apparatus according to this embodiment, the recording medium may be heated in the area where the ink composition adheres, such as on the platen 30, by a heating mechanism (e.g., heater 39) provided on the member supporting the recording medium, or by a heating mechanism (not shown) for heating the recording medium from above. Examples of heating mechanisms for heating the recording medium from above include a blower fan and an IR heater.

[0235] The heating temperature is preferably the same as that of the primary drying step described above, as it is the surface temperature of the recording medium facing the inkjet head.

[0236] In this way, the sheet S, which has received one frame of printing, moves from the platen 30 to the drying section 4 as the sheet S is intermittently transported. This drying section 4 (secondary heating mechanism) can perform a secondary heating process that completely dries the processing liquid and ink composition that have landed on the sheet S using air heated for drying.

[0237] In the drying section 4, it is preferable to heat the sheet S so that its surface temperature reaches 30.0°C to 120.0°C, preferably 40.0°C to 100.0°C, more preferably 50.0°C to 95°C, and even more preferably 70°C to 90°C. It is also preferable that the surface temperature reached by the sheet S be the same as that of the secondary drying step described above.

[0238] The dried sheet S then reaches the winding section 5 as the sheet S is intermittently transported and is wound up as a roll R2.

[0239] Figure 3 is a schematic perspective view showing another example of a recording device according to this embodiment. The recording device in Figure 3 is also an example of a serial-type recording device. The recording device 500 includes an inkjet head 510, a carriage housing 9, a carriage body 12, a platen 11, a carriage movement mechanism 13, a transport means 14, and a control unit CONT. The operation of the inkjet recording device 500 is controlled by the control unit CONT.

[0240] The inkjet head 510 is an inkjet head having nozzles for ejecting the processing liquid or ink described above, and can record onto the recording medium M by ejecting the processing liquid or ink from the nozzles of the inkjet head and applying it. The configuration of the inkjet head 510 can be the same as that of the inkjet heads 34 and 35 described above.

[0241] The inkjet head 510 is a serial inkjet head that scans the recording medium M one or more times in the main scanning direction relative to the recording medium M to deposit the aforementioned processing liquid and ink onto the recording medium M. The inkjet head 510 is mounted on the carriage 9 shown in Figure 3. The inkjet head 510 is scanned one or more times in the main scanning direction relative to the recording medium M by the operation of the carriage movement mechanism 13, which moves the carriage 9 in the media width direction of the recording medium M. The media width direction is the main scanning direction of the inkjet head 2. Scanning in the main scanning direction is also called main scanning.

[0242] Here, the main scanning direction is the direction in which the carriage 9, on which the inkjet head 510 is mounted, moves. In Figure 3, the width direction of the recording medium M, i.e., 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, i.e., in either the direction of arrow S1 or arrow S2.

[0243] The inkjet recording device 500 may have a primary drying mechanism and a secondary heating mechanism, and can have the same configuration as the recording device 100 described above.

[0244] Another example of the recording apparatus according to this embodiment is a line-type inkjet recording apparatus in which the inkjet head is a line head. As a line-type inkjet recording device, for example, in Figure 1, the inkjet heads 34 and 35 are fixed line heads with a length greater than or equal to the recording width in the width direction (Y-axis direction) of the sheet S. Processing liquid or ink is ejected from the inkjet heads 34 and 35 onto the conveyed sheet S and adheres to the sheet S. In this case, recording is performed in one main scan. When the inkjet heads 34 and 35 are line heads, the other configurations may be the same as those of the lateral-type recording device described above.

[0245] 3. Examples Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to these examples. Hereinafter, “%” is based on mass unless otherwise specified.

[0246] 3.1 Preparation of treatment liquid and each ink composition Put each component into a container so as to have the composition shown in Table 1 (Figure 4), mix and stir with a magnetic stirrer for 2 hours, and then perform a dispersion treatment with a bead mill filled with zirconia beads having a diameter of 0.3 mm to mix sufficiently. After stirring for 1 hour, filter using a 5.0 μm PTFE membrane filter to obtain a treatment liquid (R1), clear ink compositions (CL1 to CL3), a white ink composition (W1), and a non-white ink composition (C1). The numerical values related to each component in Table 1 indicate mass %. Pure water is used for water, and it is added so that the total mass of each composition is 100 mass % respectively.

[0247] For the pigment and the dispersion resin, a colorant dispersion liquid is prepared as follows and used. First, 12 parts by mass of resin A or resin B as a resin dispersant is added and dissolved in 155 parts by mass of ion-exchanged water in which 0.1 part by mass of a 30% aqueous ammonia solution (neutralizing agent) is dissolved. Then, 18 parts by mass of titanium dioxide as a white colorant or carbon black as a non-white colorant is added, and a dispersion treatment is performed with a ball mill using zirconia beads for 10 hours. Thereafter, centrifugal filtration is performed with a centrifuge to remove impurities such as coarse particles and dust, and adjusted so that the concentration of the pigment becomes 20 mass % to obtain a colorant dispersion liquid. The volume average particle diameter of carbon black is 6 nm. The volume average particle diameter of titanium dioxide is 350 nm.

[0248] Supplementary explanations for the description in Table 1 are given. 〔Dispersion resin〕 · Resin A (anionic): acrylic acid-acrylic acid ester copolymer (weight average molecular weight: 25,000, acid value: 30) · Resin B (anionic): acrylic acid-acrylic acid ester copolymer (weight average molecular weight: 25,000, acid value: 50) 〔Resin particles〕 • Styrene-acrylic type A: See below (highly cohesive type) • Styrene-acrylic type B: See below (low cohesiveness type) • Styrene-acrylic compound C: See below (those with higher cohesiveness) 〔wax〕 • Polyethylene-based: "Nopcoat PEM-17" (product name, manufactured by Sunopco Co., Ltd.) [Surfactants] • "BYK348": Product name of BYK Corporation, silicone-based surfactant.

[0249] <Preparation of Styrene Acrylic B> Resin emulsion B (acid value 10 mg KOH / g) is obtained by emulsifying copolymerizing 75 parts by mass of styrene, 0.8 parts by mass of acrylic acid, 14.2 parts by mass of methyl methacrylate, and 10 parts by mass of cyclohexyl methacrylate. Newcol NT-30 (manufactured by Nippon Emulsifier Co., Ltd.) is used as the surfactant for emulsion polymerization, in an amount of 2 parts by mass per 100 parts by mass of the total amount of monomer.

[0250] <Preparation of Styrene Acrylic A> Resin emulsion A (acid value 40 mg KOH / g) is obtained in the same manner as above, except that the monomer composition is changed. The surfactant for emulsion polymerization is added in an amount of 1 part by mass per 100 parts by mass of the total amount of monomer.

[0251] <Preparation of Styrene-Acrylic C> Resin emulsion C (acid value 60 mg KOH / g) is obtained in the same manner as above, except that the monomer composition is changed. The surfactant for emulsion polymerization is added in an amount of 1 part by mass per 100 parts by mass of the total amount of monomer.

[0252] The "thickness ratio when mixed with R1" listed in Table 1 is calculated by mixing each clear ink composition (CL1-CL3), white ink composition (W1), or non-white ink composition (C1) with a test solution under the same conditions as the processing solution (R1) in a mass ratio of 10:1, stirring for 1 minute, and then measuring the viscosity using a rheometer (MCR302 / Anton Paar) at 25°C and a shear rate of 200 s. -1This is the ratio of the viscosity of the mixed solution to the viscosity of the ink before mixing, measured under the specified conditions.

[0253] 3.2 Record Test The records used in the recording test shall be under the conditions described in Table 2 (Figure 5), Table 3 (Figure 6), and below. Printing machine: SurePress L-4733AW (manufactured by Seiko Epson Corporation), modified version. Nozzle density: 1200 npi Recording resolution: 1200 x 1200 dpi Recording medium: "PET50A" (product name manufactured by Lintec Corporation, PET transparent film) Printing order: The order listed in Tables 2 and 3. Nozzle condition: If there are no non-discharging nozzles, it is considered "good"; if there are non-discharging nozzles, it is considered "missing". Dot size: Weight per droplet (ng / dot) Duty: Ink droplet density on the grid at the above recording resolution

[0254] The printing order is as follows: the contents of the left parentheses in Tables 2 and 3 are printed simultaneously in this nozzle order, then the carriage returns, and in the second pass, the contents of the right parentheses are printed simultaneously in this nozzle order. For example, in Example 1, it is written as "(reaction solution → white → clear) → (colored)". First, in the first pass, simultaneous printing is performed in the nozzle order of "(reaction solution → white → clear)". That is, scanning to eject the processing solution from the inkjet head and adhere it to the recording medium, scanning to eject the white ink composition from the inkjet head and adhere it to the recording medium, and scanning to eject the clear ink composition from the inkjet head and adhere it to the recording medium are performed on the same scanning area with the same scan, and the order in which the droplets land on the recording medium is processing solution → white → clear. After that, in the second pass, simultaneous printing is performed in the nozzle order of "(colored)". That is, scanning to eject the non-white ink composition and adhere it to the recording medium is performed on the same scanning area.

[0255] Record a solid pattern of 10×20 cm in the first pass. Overlap and record the next solid pattern on a 10×10 cm portion, which is half of the solid pattern recorded in the second pass.

[0256] The recording test is carried out separately for the recording when the nozzles are in good condition and the recording when the nozzles are in poor condition to obtain respective recordings. For the recording when the nozzles are in good condition, printing is performed according to Table 2, Table 3 and the above conditions. On the other hand, in the recording when the nozzles are in poor condition, 3% of each of the nozzles that discharge the white ink composition and the non-white ink composition are regarded as non-discharging nozzles and not discharged. For the two adjacent nozzles (2 nozzles) of the non-discharging nozzles, the dot size or Duty is set to the values described in Table 2 and Table 3. For the clear ink composition, one nozzle at the same position as the non-discharging nozzle of the white ink composition is discharged with the described value. The nozzles other than the nozzles adjacent to the non-discharging nozzles are printed in the same manner as when the nozzles are in good condition.

[0257] 3.3 Evaluation Test 3.3.1 Streaks in the solid white part For the recordings obtained in the above recording test, a white image without a laminated color image was visually confirmed, and the occurrence of streaks in the image area at the nozzle position where non-discharge of the white ink occurred was confirmed. Evaluation was performed according to the following criteria. (Evaluation Criteria) A: Streaks cannot be seen even at a short distance. B: Streaks can be seen at a short distance but cannot be seen at a distance of 30 cm. C: Streaks can be seen even at a distance of 30 cm.

[0258] 3.3.2 Streaks in the solid color part on white For the recordings obtained in the above recording test, an image with a color image laminated on the white image was visually confirmed, and the occurrence of streaks in the color image on the image area at the nozzle position where non-discharge of the white ink occurred was confirmed. Evaluation was performed according to the following criteria. (Evaluation Criteria) A: Streaks cannot be seen even at a short distance. B: It's visible at close range, but not at a distance of 30cm. C: Visible even at a distance of 30cm.

[0259] 3.3.3 Blurring at color boundaries The recordings obtained in the above recording test will be visually observed up close at the boundary between the color image formed by layering on a white image and the white image on which no color image is layered, and evaluated according to the following criteria. (Judgment criteria) A: The boundary looks like a clean straight line. B: There is some slight ink bleeding at the border. C: There is considerable ink bleeding at the border.

[0260] 3.4 Evaluation Results The evaluation results are shown in Tables 2 and 3. As shown in the results in Tables 2 and 3, the recording method according to each embodiment includes a processing liquid application step of applying a processing liquid containing a coagulant to a recording medium, a white ink application step of ejecting a white ink composition containing a white colorant from an inkjet head and applying it to the recording medium, a non-white ink application step of ejecting a non-white ink composition containing a non-white colorant from an inkjet head and applying it to the recording medium, and a clear ink application step of ejecting a clear ink composition containing a resin from an inkjet head and applying it to the recording medium, and a white image formed by the application of the white ink composition and a non-white image formed by the application of the non-white ink composition are superimposed to form the image, the white ink composition, the non-white ink composition and the clear ink composition are water-based inks, and the clear ink composition is applied to the image area to be recorded by a non-ejecting nozzle among the multiple nozzles of the inkjet head that ejects the white ink composition, and all of the recording methods according to each embodiment are able to effectively reduce streaks in the color image (streaks in solid color areas on white) on the image area at the nozzle position where the white ink was not ejected.

[0261] In contrast, Comparative Examples 1 to 3, which do not satisfy the above configuration, are unable to reduce streaks in the color image (streaks in solid color areas on white backgrounds) in the image area at the nozzle position where white ink failure occurred.

[0262] The following conclusions can be drawn from the embodiments described above.

[0263] One method of recording is: A processing liquid application step in which a processing liquid containing a coagulant is applied to a recording medium, A white ink application step involves ejecting a white ink composition containing a white colorant from an inkjet head and adhering it to the recording medium. A non-white ink application step involves ejecting a non-white ink composition containing a non-white colorant from the inkjet head and adhering it to the recording medium, The process includes a clear ink application step in which a clear ink composition containing resin is ejected from the inkjet head and adhered to the recording medium, A white image formed by the adhesion of the white ink composition and a non-white image formed by the adhesion of the non-white ink composition are superimposed to form a complete image. The white ink composition, the non-white ink composition, and the clear ink composition are water-based inks. The clear ink composition is applied to the area of ​​the image to be recorded by a non-discharging nozzle among the multiple nozzles of the inkjet head that discharges the white ink composition.

[0264] In one embodiment of the above recording method, The clear ink composition may be a clear ink composition that thickens when mixed with the processing liquid.

[0265] In any embodiment of the above recording method, The amount of the clear ink composition adhering to the area of ​​the image to be recorded by the non-discharging nozzle among the plurality of nozzles of the inkjet head that ejects the white ink composition may be greater than the amount of the clear ink composition adhering to areas other than that area.

[0266] In any embodiment of the above recording method, In the region of the image to be recorded by the non-discharging nozzle among the plurality of nozzles of the inkjet head that ejects the white ink composition, a interpolation process may be performed using a nozzle other than the non-discharging nozzle of the white ink composition.

[0267] In any embodiment of the above recording method, In the area of ​​the image to be recorded by the non-discharge nozzle among the plurality of nozzles of the inkjet head that discharges the non-white ink composition, a interpolation process may be performed using a nozzle other than the non-discharge nozzle of the non-white ink composition.

[0268] In any embodiment of the above recording method, The clear ink application step may be performed after the white ink application step, or before or after the non-white ink application step.

[0269] In any embodiment of the above recording method, After the processing liquid application step, the white ink application step is performed. The non-white ink application step may be performed after the white ink application step.

[0270] In any embodiment of the above recording method, The nozzle densities of the inkjet head that ejects the white ink composition and the inkjet head that ejects the non-white ink composition may each be 1200 npi or more.

[0271] In any embodiment of the above recording method, The absolute difference between the viscosity increase ratio when the white ink composition is mixed with the processing solution in a mass ratio of 10:1 and the viscosity increase ratio when the clear ink composition is mixed with the processing solution in a mass ratio of 10:1 may be 60 times or less.

[0272] In any embodiment of the above recording method, The white ink application step and the non-white ink application step are performed by scanning, in which the inkjet head and the recording medium move relative to each other while ink is ejected from the inkjet head and applied to the recording medium. The number of scans performed on the same scanning area in the recording medium may be one for the white ink application step and one for the non-white ink application step.

[0273] In any embodiment of the above recording method, The recording medium may be a low-absorption recording medium or a non-absorption recording medium.

[0274] One embodiment of a recording device is: A recording device that performs recording by any of the above-described recording methods, The device comprises the processing liquid, the white ink composition, the non-white ink composition, the clear ink composition, an adhesion mechanism for performing the processing liquid adhesion step, an inkjet head for performing the white ink adhesion step, an inkjet head for performing the non-white ink adhesion step, and an inkjet head for performing the white clear ink adhesion step.

[0275] The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the present invention includes configurations that are substantially identical to the configurations described in the embodiments, for example, configurations that have the same function, method and result, or configurations that have the same purpose and effect. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as the configurations described in the embodiments. Furthermore, the present invention includes configurations that add known technology to the configurations described in the embodiments. [Explanation of Symbols]

[0276] 100, 500... Recording device, 200... Host device, 210... Printer driver, 230... Communication control unit, 240... Monitor, 300... Printer unit, 400... Printer control unit, 1... Main case, 2... Feeding unit, 9... Carriage housing, 12... Carriage body, 13... Carriage movement mechanism, 14... Conveying means, 21... Feeding shaft, 3... Printing chamber, 30, 11... Platen, 31... Recording unit, 32... Carriage, 33... Support plate, 34, 35, 510... Inkjet head, 37... X-axis guide rail, 38... Suction unit, 39... Heater, 4... Drying unit, 5... Winding unit, 51... Winding shaft, 6... Base, 71~77... Roller, 8... Cartridge mounting unit, 81... Processing liquid cartridge, 82... Ink cartridge, R1, R2... Roll, S... Sheet.

Claims

1. A processing liquid application step in which a processing liquid containing a coagulant is applied to a recording medium, A white ink application step involves ejecting a white ink composition containing a white colorant from an inkjet head and adhering it to the recording medium. A non-white ink application step involves ejecting a non-white ink composition containing a non-white colorant from the inkjet head and adhering it to the recording medium, The process includes a clear ink application step in which a clear ink composition containing resin is ejected from the inkjet head and adhered to the recording medium, A white image formed by the adhesion of the white ink composition and a non-white image formed by the adhesion of the non-white ink composition are superimposed to form a complete image. The white ink composition, the non-white ink composition, and the clear ink composition are water-based inks. A recording method comprising applying the clear ink composition to an area of ​​an image to be recorded by a non-discharging nozzle among a plurality of nozzles of an inkjet head that discharges the white ink composition.

2. The recording method according to claim 1, wherein the clear ink composition is a clear ink composition that thickens when mixed with the processing liquid.

3. The recording method according to claim 1 or claim 2, wherein the amount of the clear ink composition adhering to an area of ​​an image to be recorded by a non-discharging nozzle among a plurality of nozzles of the inkjet head that discharges the white ink composition is greater than the amount of the clear ink composition adhering to areas other than that area.

4. The recording method according to claim 1 or claim 2, wherein a region of an image to be recorded by a non-discharging nozzle among a plurality of nozzles of the inkjet head that discharges the white ink composition is interpolated using a nozzle other than the non-discharging nozzle of the white ink composition.

5. The recording method according to claim 1 or claim 2, wherein a region of an image to be recorded by a non-discharge nozzle among a plurality of nozzles of the inkjet head that discharges the non-white ink composition is interpolated with a nozzle other than the non-discharge nozzle of the non-white ink composition.

6. The recording method according to claim 1 or claim 2, wherein the clear ink application step is performed after the white ink application step and before or after the non-white ink application step.

7. After the processing liquid application step, the white ink application step is performed. The recording method according to claim 1 or claim 2, wherein the non-white ink application step is performed after the white ink application step.

8. The recording method according to claim 1 or claim 2, wherein the nozzle density of the inkjet head that ejects the white ink composition and the inkjet head that ejects the non-white ink composition are each 1200 npi or more.

9. The recording method according to claim 1 or claim 2, wherein the absolute difference between the viscosity increase ratio when the white ink composition is mixed with the processing liquid in a mass ratio of 10:1 and the viscosity increase ratio when the clear ink composition is mixed with the processing liquid in a mass ratio of 10:1 is 60 times or less.

10. The white ink application step and the non-white ink application step are performed by scanning, in which the inkjet head and the recording medium move relative to each other while ink is ejected from the inkjet head and applied to the recording medium. The recording method according to claim 1 or claim 2, wherein the number of scans performed on the same scanning area in the recording medium is one for the white ink application step and one for the non-white ink application step.

11. The recording method according to claim 1 or claim 2, wherein the recording medium is a low-absorption recording medium or a non-absorption recording medium.

12. A recording device that performs recording by the recording method described in claim 1, A recording device comprising the processing liquid, the white ink composition, the non-white ink composition, the clear ink composition, an adhesion mechanism for performing the processing liquid adhesion step, an inkjet head for performing the white ink adhesion step, an inkjet head for performing the non-white ink adhesion step, and an inkjet head for performing the white clear ink adhesion step.

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