Image recording method

Abstract

The present invention provides an image recording method and the like including a step of applying a pretreatment liquid, a first ink, and a second ink in this order on an impermeable substrate, the value (1) being 28.0-35.0, and the value (2) being-200-200. V1 represents the volume (pL) of droplets of the first ink, theta represents the contact angle (degree) of the first ink, Av1 represents the acid value (mgKOH / g) of the first ink, Av2 represents the acid value (mgKOH / g) of the second ink, S1 represents the solid content (mass%) of the first ink, S2 represents the solid content (mass%) of the second ink, and T represents the droplet ejection interval (second) of the first ink and the second ink. Value (1) = (V1) 1 / 3 * (1 + cos [theta]) * 14. Value (2) = Av1 / S1-Av2 / S2 * (Av2-Av1) / T.

Description

TECHNICAL FIELD

[0001] The present application relates to an image recording method and an image recording apparatus. BACKGROUND

[0002] Various studies have been made on an image recording method using a pretreatment liquid (also referred to as an adhesion-improving coating agent or the like) and an inkjet ink.

[0003] For example, in Japanese Patent Application Publication No. 2022-102449, there is disclosed a recording liquid set including an aqueous inkjet ink and an adhesion-improving coating agent, and having an aqueous inkjet ink including water, a pigment, a resin, an alkane diol-based solvent having 3 to 4 carbon atoms, and a surfactant having a trisiloxane skeleton, and an adhesion-improving coating agent including water and a polyvalent metal salt, the recording liquid set being capable of obtaining a printed matter having good filling and no bleeding of an image, excellent color development, and excellent stability over time, regardless of printing onto a non-absorbing substrate or high-speed printing. SUMMARY

[0004] Technical Problem to be Solved by the Invention

[0005] In an image recording method using a pretreatment liquid and an inkjet ink, sometimes a multicolor image is recorded by sequentially imparting, onto a non-permeable substrate, a pretreatment liquid containing water, a coagulant, and a resin, a first ink containing water, a first pigment, and a resin, and a second ink containing water, a second pigment, and a resin.

[0006] In the case of recording a multicolor image, sometimes at least one of bleeding between colors and hiding of dots of the second ink occurs.

[0007] The hiding of dots of the ink of the second color and subsequent colors can be a cause of reduction in a color gamut of the multicolor image.

[0008] An object of an embodiment of the present application is to provide an image recording method capable of suppressing bleeding between colors and hiding of dots of a second ink in the case where a multicolor image is recorded by sequentially imparting, onto a non-permeable substrate, a pretreatment liquid containing water, a coagulant, and a resin, a first ink containing water, a first pigment, and a resin, and a second ink containing water, a second pigment, and a resin.

[0009] An object of another embodiment of the present application is to provide an image recording apparatus for the above-described image recording method of the present application.

[0010] Means for Solving the Technical Problem

[0011] The present application includes the following modes.

[0012] <1> An image recording method comprising:

[0013] a process of imparting a pretreatment liquid containing water, a coagulant, and a resin on a non-permeable substrate;

[0014] a process of imparting a first ink containing water, a first pigment, and a resin on the region of the non-permeable substrate to which the pretreatment liquid is imparted using an inkjet recording method; and

[0015] a process of imparting a second ink containing water, a second pigment, and a resin on the region of the non-permeable substrate to which the pretreatment liquid and the first ink are imparted using an inkjet recording method,

[0016] the following value (1) is 28.0 to 35.0,

[0017] the following value (2) is -200 to 200.

[0018] value (1) = (V1) 1 / 3 × (1 + cos θ) × 14

[0019] value (2) = |Av1 / S1 - Av2 / S2| × (Av2 - Av1) / T

[0020] In value (1), V1 represents the volume of a droplet of the first ink in pL at the time of imparting the first ink, and θ represents the contact angle in ° of the first ink at the time of T seconds from when the first ink lands on the region of the non-permeable substrate to which the pretreatment liquid is imparted.

[0021] In value (2), Av1 represents the acid value of the first ink in mgKOH / g, Av2 represents the acid value of the second ink in mgKOH / g, S1 represents the solid content amount of the first ink in mass%, S2 represents the solid content amount of the second ink in mass%, and T represents the droplet ejection interval of the first ink and the second ink in seconds.

[0022] <2> The image recording method according to <1>, wherein

[0023] the following value (3) is -2000 to 2000.

[0024] value (3) = value (2) × |L2* - L1*|

[0025] In value (3), L1* represents L * a * b * L * value of the first ink in the colorimetric system, and L2* represents L * a * b * L * value of the second ink in the colorimetric system.

[0026] <3> according to <1> or <2> The image recording method, wherein,

[0027] Av1 is greater than Av2.

[0028] <4> according to <1> to <3> The image recording method described in any one of the following statements, wherein,

[0029] L * a * b * The L of the first ink in the color system * The value is L1* lower than L. * a * b * L, the second ink in the color system * The value is L2*.

[0030] <5> according to <1> to <4> The image recording method described in any one of the following methods further includes:

[0031] A process of applying a third ink containing water, a third pigment, and a resin to areas on a non-permeable substrate that have been treated with a pretreatment solution, a first ink, and a second ink using an inkjet recording method; and

[0032] The process of applying a fourth ink containing water, a fourth pigment, and a resin to areas on a non-porous substrate that have been treated with a pretreatment solution, a first ink, a second ink, and a third ink using an inkjet recording method.

[0033] When the acid value of the third ink in mgKOH / g is expressed as Av3 and the acid value of the fourth ink in mgKOH / g is expressed as Av4, the following inequality (4) is satisfied.

[0034] Inequality (4) Av1>Av2>Av3>Av4……

[0035] <6> according to <5> The image recording method further includes:

[0036] The process of applying white ink containing water, white pigment, and resin to areas on a non-porous substrate that have been treated with a pretreatment solution, a first ink, a second ink, a third ink, and a fourth ink using an inkjet recording method.

[0037] The acid value of white ink, expressed in mgKOH / g, is higher than any of Av1, Av2, Av3, and Av4.

[0038] <7> An image recording device, used for <1> to <6> The image recording method described in any one of the following statements, wherein the image recording apparatus comprises:

[0039] a pre-treatment liquid-imparting device for imparting the pre-treatment liquid on one surface of the non-penetrable substrate;

[0040] a first inkjet head for imparting the first ink; and

[0041] a second inkjet head for imparting the second ink,

[0042] the value (1) is 28.0 to 35.0,

[0043] the value (2) is -200 to 200.

[0044] Effects of the Invention

[0045] According to an embodiment of the present application, there is provided an image recording method capable of suppressing bleeding between colors and dot burying of a second ink in a case where a pre-treatment liquid containing water, a coagulant and a resin, a first ink containing water, a first pigment and a resin, and a second ink containing water, a second pigment and a resin are sequentially imparted on a non-penetrable substrate to record a multi-color image.

[0046] According to another embodiment of the present application, there is provided an image recording apparatus for the image recording method of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 is a diagram schematically showing an example of an image recording apparatus used in the image recording method of the present application.

[0048] Figure 2 is a diagram showing a character image used in the example. DETAILED DESCRIPTION

[0049] In the present application, a numerical range indicated using "~" indicates a range including the values recited before and after "~" as the minimum value and the maximum value, respectively.

[0050] In the numerical ranges recited in stages in the present specification, the upper limit value or the lower limit value recited in a certain numerical range can be replaced with the upper limit value or the lower limit value of another numerical range recited in stages. Also, in the numerical ranges recited in the present specification, the upper limit value or the lower limit value recited in a certain numerical range can be replaced with the value shown in the example.

[0051] In the present application, regarding the amount of each component in a composition, in a case where a plurality of substances corresponding to each component are present in the composition, unless otherwise specifically described, the total amount of the plurality of substances present in the composition is indicated.

[0052] In the present application, a combination of two or more of the preferable modes is a more preferable mode.

[0053] In the present application, the term "process" includes not only a process alone, but also a process even if it cannot be distinguished from other processes as long as the intended purpose of the process can be achieved.

[0054] In the present application, with respect to "image", in the case of using one kind of ink, it means the ink film itself, and in the case of using a plurality of kinds of ink in superposition, it means a laminated film of a plurality of kinds of ink films.

[0055] In the present application, "image recording" means formation of an image.

[0056] The concept of "image" in the present application also includes a solid image.

[0057] [Image recording method]

[0058] The image recording method of the present application includes a process of imparting a pretreatment liquid containing water, a coagulant, and a resin on a non-penetrable substrate; a process of imparting a first ink containing water, a first pigment, and a resin on a region on the non-penetrable substrate to which the pretreatment liquid has been imparted using an inkjet recording method; and a process of imparting a second ink containing water, a second pigment, and a resin on a region on the non-penetrable substrate to which the pretreatment liquid and the first ink have been imparted using an inkjet recording method,

[0059] The following value (1) is 28.0 to 35.0,

[0060] The following value (2) is -200 to 200.

[0061] Value (1) = (V1) 1 / 3 × (1 + cos θ) × 14

[0062] Value (2) = |Av1 / S1 - Av2 / S2| × (Av2 - Av1) / T

[0063] In value (1), V1 represents the volume of a droplet of the first ink at the time of imparting the first ink in pL, and θ represents the contact angle of the first ink at the time of passing through the time point of T seconds from the region on the non-penetrable substrate to which the pretreatment liquid has been imparted at which the first ink lands in °.

[0064] In value (2), Av1 represents the acid value of the first ink in mgKOH / g, Av2 represents the acid value of the second ink in mgKOH / g, S1 represents the solid content amount of the first ink in mass%, S2 represents the solid content amount of the second ink in mass%, and T represents the droplet ejection interval of the first ink and the second ink in seconds.

[0065] According to the image recording method of the present application, bleeding between colors and dot burying of the second ink in the case where a multicolor image is recorded by sequentially applying a pretreatment liquid containing water, a coagulant and a resin, a first ink containing water, a first pigment and a resin, and a second ink containing water, a second pigment and a resin to a non-penetrable substrate can be suppressed.

[0066] The present inventors found the following regarding suppression of bleeding of a multicolor image and dot burying of a second ink:

[0067] the volume V1 of the droplet of the first ink,

[0068] the contact angle θ of the first ink at the time (i.e., the time of landing of the second ink) that elapses T seconds from the landing of the first ink,

[0069] the acid value Av1 of the first ink,

[0070] the acid value Av2 of the second ink,

[0071] the solid content amount S1 of the first ink,

[0072] the solid content amount S2 of the second ink, and

[0073] the droplet ejection interval T of the first ink and the second ink

[0074] When the values (1) and (2) are within the above ranges, respectively, bleeding of a multicolor image and dot burying of a second ink can be suppressed.

[0075] Hereinafter, the image recording method of the present application will be described in more detail.

[0076] <value (1) [= (V1 1 / 3 × (1 + cos θ) x 14]>

[0077] In the image recording method of the present application, the value (1) [= (V1 1 / 3 × (1 + cos θ) x 14] is 28.0 to 35.0.

[0078] By the value (1) [= (V1 1 / 3 × (1 + cos θ) x 14] being 28.0 or more, dot burying of the second ink can be suppressed. Also, striping of a multicolor image is suppressed.

[0079] By the value (1) being 35.0 or less, bleeding of a multicolor image can be suppressed.

[0080] The value (1) is preferably 28.0 to 34.0, more preferably 29.0 to 34.0, further preferably 30.0 to 34.0, and particularly preferably 31.0 to 34.0.

[0081] V1 is the volume (pL) of the droplet of the first ink at the time of discharging the first ink.

[0082] V1 is preferably 0.3 to 5.0, more preferably 0.5 to 4.0, and further preferably 1.0 to 3.0.

[0083] In the present application, the method for measuring the volume of the droplet of the ink is not particularly limited, and for example, gravimetric method, camera photography method, and the like can be given.

[0084] The gravimetric method is performed, for example, by the following method.

[0085] The ink is discharged into a measuring container in a prescribed number of discharges. The total mass of the droplets discharged into the measuring container is measured. The size of the droplet is calculated according to the following equation.

[0086] Size of droplet (pL) = (total mass of discharged droplets (g) ÷ number of discharges) ÷ specific gravity of ink (g / cm3) x 10 3 ) x 10 9

[0087] The camera photography method is performed, for example, by the following method.

[0088] A jet flight droplet observation device (product name "jetXpert", manufactured by imageXpert Inc.) is provided on the inkjet head. The size of the droplet is calculated by photographing the droplet.

[0089] In addition, although not related to value (1), the preferred range of the volume (pL) of the droplet of the second ink at the time of discharging the second ink, i.e., V2, is also the same as the preferred range of the volume of the droplet of the first ink at the time of discharging the first ink, i.e., V1, which has been described.

[0090] Furthermore, the preferred range of the volume of the droplet of the ink at the time of discharging other ink (e.g., third ink, fourth ink, etc.) that can be used arbitrarily is also the same as the preferred range of the volume of the droplet of the first ink at the time of discharging the first ink, i.e., V1, which has been described.

[0091] In value (1), θ is the contact angle (°) of the first ink at the time of 1 second after the droplet ejection interval T seconds from the time of landing of the first ink, i.e., the time of landing of the second ink.

[0092] θ is measured as follows.

[0093] After the pretreatment liquid is given to the non-penetrable substrate and dried, the non-penetrable substrate to which the pretreatment liquid is given is cut, thereby obtaining a measurement sample. 2.0 μL of the first ink is dropped on the region to which the pretreatment liquid is given in the measurement sample, and the contact angle θ (°) of the first ink at the time of 1 second after the landing interval T seconds from the time of dropping is measured.

[0094] The contact angle was measured at 20°C using a contact angle meter (for example, product name "DM-501", manufactured by Kyowa Interface Science Co., Ltd.).

[0095] <value (2) [= |Av1 / S1 - Av2 / S2| x (Av2 - Av1) / T]>

[0096] In the image recording method of the present application, value (2) [= |Av1 / S1 - Av2 / S2| x (Av2 - Av1) / T] is -200 to 200.

[0097] By value (2) being -200 or more, the dot burying of the second ink can be suppressed.

[0098] By value (2) being 200 or less, the bleeding of the multi-color image can be suppressed.

[0099] Value (2) is preferably -150 to 150, more preferably -60 to 60, and further preferably -20 to 20.

[0100] Av1 is the acid value (mgKOH / g) of the first ink.

[0101] Av1 is preferably 1.0 to 6.0, and more preferably 1.0 to 5.0.

[0102] As for Av1, the diluent in which the first ink is diluted 10 times by volume with tetrahydrofuran (THF) is prepared, and the obtained diluent is completely neutralized with KOH, and then titrated with HCl.

[0103] Av2 is the acid value (mgKOH / g) of the second ink.

[0104] Av2 is also calculated in the same manner as Av1 that has been described.

[0105] Av2 is preferably 1.0 to 6.0, and more preferably 1.0 to 5.0.

[0106] That is, as for Av1 and Av2, the diluent in which the first ink and the second ink are diluted 10 times by volume with tetrahydrofuran (THF), respectively, is prepared, and the obtained diluent is completely neutralized with KOH, and then titrated with HCl.

[0107] Av1 is preferably greater than Av2 (that is, Av1 > Av2 is satisfied).

[0108] Thus, the bleeding of the multi-color image is further suppressed.

[0109] In the case where Avl is greater than Av2, the value of Avl - Av2 is preferably 0.3 or greater, more preferably 0.5 to 3.0, further preferably 0.5 to 2.0.

[0110] S1 is the amount of solid content (mass %) of the first ink, that is, the content (mass %) of the solid content with respect to the total amount of the first ink.

[0111] S1 is, for example, the total amount of the first pigment and the resin in the first ink.

[0112] With respect to S1, it can be found from the mass of the dried substance obtained by allowing the first ink to be eluted with 0.1 N hydrochloric acid, washing with 0.1 N hydrochloric acid while filtering, and drying the solid content remaining after filtration.

[0113] The solid content amount (mass %) of the second ink, that is, S2, described later, can also be found in the same manner as S1.

[0114] S1 is preferably 2.0 to 20.0, more preferably 3.0 to 20.0, further preferably 5.0 to 20.0, further preferably 7.0 to 15.0.

[0115] S2 is the amount of solid content (mass %) of the second ink, that is, the content (mass %) of the solid content with respect to the total amount of the second ink.

[0116] S2 is, for example, the total amount of the second pigment and the resin in the second ink.

[0117] T is the droplet ejection interval (seconds) of the first ink and the second ink.

[0118] In detail, T is the time from the landing of the first ink to the landing of the second ink at a certain site X on the non-penetrable substrate.

[0119] T is preferably 0.10 to 2.00, more preferably 0.20 to 1.50, further preferably 0.20 to 1.20.

[0120] <value (3) [= value (2) x |L2* - L1*|]>

[0121] In the image recording method of the present application, value (3) [= value (2) x |L2* - L1*|] is preferably -10000 to 10000, more preferably -4000 to 4000, further preferably -2000 to 2000, particularly preferably -1500 to 1500.

[0122] In value (3), L1* represents L * a * b * L1* of the first ink in the color specification system *L2* represents L * a * b * L value of the 2nd ink in the color system * value.

[0123] In the case where the value (3) is -10000 or more, bleeding of the 2nd ink can be further suppressed.

[0124] In the case where the value (3) is 10000 or less, bleeding of the multicolor image can be further suppressed.

[0125] As to L1*, the L* value of the solid image of the single color is measured by X-rite exact (manufactured by X-Rite) through the non-permeable substrate from the back of the non-permeable substrate on which the solid image of the single color is recorded, that is, the side opposite to the image recording surface.

[0126] At this time, the white surface part of the hiding power measurement test paper manufactured by Topcon Corporation is laid on the image recording surface side of the non-permeable substrate, and L1* is measured.

[0127] L2* to be described later is also measured in the same manner as L1*.

[0128] L1* is preferably 5.0 to 100.0, more preferably 5.0 to 20.0, and further preferably 5.0 to 15.0.

[0129] L2* is preferably 5.0 to 100.0, more preferably 30.0 to 100.0, and further preferably 50.0 to 100.0.

[0130] |L2*-L1*| is preferably 5.0 to 100.0, and more preferably 5.0 to 90.0.

[0131] L1* is preferably lower than L2*.

[0132] Thereby, bleeding of the multicolor image can be further suppressed.

[0133] <Non-permeable substrate>

[0134] In the image recording method of the present application, an image is recorded on a non-permeable substrate.

[0135] In the present application, the non-permeability in the non-permeable substrate refers to a property in which the water absorption rate within 24 hours measured in accordance with ASTM D570-98 (2018) is 2.5% or less. Here, "%" as a unit of the water absorption rate is on a mass basis. The above water absorption rate is preferably 1.0% or less, and more preferably 0.5% or less.

[0136] As the material of the non-permeable base material, for example, glass, metal (for example, aluminum, zinc, copper, and the like), and resin (for example, polyvinyl chloride, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, nylon, acrylic resin, and the like) can be given.

[0137] The material of the non-permeable base material is preferably resin. That is, the non-permeable base material is preferably a resin base material.

[0138] Among them, from the viewpoint of general use, the material of the non-permeable base material is preferably polypropylene, polyethylene, polyethylene terephthalate, nylon, acrylic resin, or polyvinyl chloride.

[0139] The shape of the non-permeable base material is preferably a sheet shape (film shape) or a plate shape. As the non-permeable base material having such a shape, a glass plate, a metal plate, a resin sheet (resin film), a plastic-laminated paper, a metal-laminated or vapor-deposited paper, and a metal-laminated or vapor-deposited plastic sheet (plastic film) can be given.

[0140] As the resin non-permeable base material, a resin sheet (resin film) can be given, specifically, a soft packaging material for packaging food and the like, and a floor guide panel for a mass retailer can be given.

[0141] As the non-permeable base material, in addition to the non-permeable base material of a sheet shape (film shape) or a plate shape, a textile (fabric) and a non-woven fabric formed of a fiber having non-permeability can be given.

[0142] The non-permeable base material can be subjected to a hydrophilization treatment. As the hydrophilization treatment, corona treatment, plasma treatment, flame treatment, heat treatment, abrasion treatment, light irradiation treatment (for example, UV treatment), and flame treatment can be given, but are not limited thereto. The corona treatment can be performed using, for example, Corona Master (product name "PS-10S", manufactured by Shinko Electric & Instrumentation Co., Ltd.). The conditions of the corona treatment can be appropriately selected depending on the kind of the non-permeable base material and the like.

[0143] The non-permeable base material can be a non-permeable base material having transparency.

[0144] Here, the non-permeable base material having transparency means that the transmittance of visible light having a wavelength of 400 nm to 700 nm is 80% or more. The transmittance of visible light having a wavelength of 400 nm to 700 nm of the non-permeable base material is preferably 90% or more.

[0145] In the case where the non-permeable substrate is a non-permeable substrate having transparency, it is easy to visually recognize the image from the image non-recording surface side of the non-permeable substrate through the non-permeable substrate.

[0146] For example, in the case where the non-permeable substrate is a non-permeable substrate having transparency, when an image is recorded on the non-permeable substrate by sequentially imparting a pretreatment liquid described later, a non-white ink described later, and a white ink described later on the non-permeable substrate, it is easy to visually recognize a non-white image (for example, a pattern image such as characters, figures, and the like) having a white image (for example, a solid image) as a background from the image non-recording surface side of the non-permeable substrate through the non-permeable substrate.

[0147] <Step of imparting a pretreatment liquid>

[0148] The image recording method of the present application includes a step of imparting a pretreatment liquid containing water, a coagulant, and a resin on a non-permeable substrate.

[0149] (Pretreatment liquid)

[0150] -Water-

[0151] The pretreatment liquid contains water.

[0152] The content of water is preferably 50% by mass or more, more preferably 60% by mass or more, with respect to the total amount of the pretreatment liquid.

[0153] The upper limit of the content of water also depends on the amount of other components, but is preferably 90% by mass or less, more preferably 80% by mass or less, with respect to the total amount of the pretreatment liquid.

[0154] -Coagulant-

[0155] The pretreatment liquid contains at least one coagulant.

[0156] The coagulant in the pretreatment liquid coagulates components in the ink on the non-permeable substrate. Thereby, it is possible to improve the quality of the image.

[0157] The coagulant is preferably at least one selected from the group consisting of an organic acid and a polyvalent metal compound.

[0158] As the coagulant, it is possible to preferably cite the coagulants described in paragraphs 0122 to 0130 of International Publication No. 2020 / 195360.

[0159] Hereinafter, preferred modes of each of the organic acid, the polyvalent metal compound, the metal complex, and the cationic polymer that can be used as the coagulant will be described.

[0160] --Organic acid--

[0161] As the organic acid, an organic compound having an acidic group can be cited.

[0162] As the acidic group, a phosphoric acid group, a phosphonic acid group, a phosphinic acid group, a sulfuric acid group, a sulfonic acid group, a sulfinic acid group, and a carboxyl group can be given.

[0163] Among them, from the viewpoint of the coagulation speed of the ink, the acidic group is preferably a phosphoric acid group or a carboxyl group, and more preferably a carboxyl group.

[0164] It is preferable that at least a part of the acidic group dissociates in the pretreatment liquid.

[0165] As the organic compound having a carboxyl group, (meth)acrylic acid, poly(meth)acrylic acid, acetic acid, formic acid, benzoic acid, ethanediolic acid, propanedioic acid, malic acid (preferably DL-malic acid), maleic acid, succinic acid, pentanedioic acid, heptanedioic acid, hexanedioic acid, fumaric acid, citric acid, tartaric acid, phthalic acid, 4-methylphthalic acid, lactic acid, pyrrolidone carboxylic acid, pyranone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, and nicotinic acid can be given.

[0166] Among them, from the viewpoint of the coagulation speed of the ink, the organic compound having a carboxyl group is preferably a carboxylic acid of valence 2 or more (hereinafter, also referred to as a polycarboxylic acid), and more preferably a dicarboxylic acid.

[0167] Specifically, the polycarboxylic acid is preferably propanedioic acid, malic acid, maleic acid, succinic acid, pentanedioic acid, heptanedioic acid, hexanedioic acid, fumaric acid, tartaric acid, 4-methylphthalic acid, or citric acid, and more preferably propanedioic acid, malic acid, tartaric acid, succinic acid, pentanedioic acid, heptanedioic acid, hexanedioic acid, or citric acid.

[0168] It is preferable that the pKa of the organic acid is low (for example, 1.0 to 5.0). Thereby, by reducing the surface charge of the particles such as pigments, resin particles in the ink stabilized by dispersing the weakly acidic functional group such as a carboxyl group in contact with the organic acid having a lower pKa, it is possible to reduce the dispersion stability.

[0169] It is preferable that the pKa of the organic acid is low, the solubility in water is high, and the valence is 2 or more. Furthermore, it is more preferable that the organic acid has a high buffering capacity in a pH region lower than the pKa of the functional group (for example, a carboxyl group) that stabilizes the particles in the ink.

[0170] --Polyvalent Metal Compound--

[0171] As the polyvalent metal compound, a polyvalent metal salt can be given.

[0172] As the polyvalent metal salt, an organic acid polyvalent metal salt and an inorganic acid polyvalent metal salt can be given.

[0173] As the organic acid polyvalent metal salt, a polyvalent metal salt of the above-described organic acid (for example, formic acid, acetic acid, lactic acid, benzoic acid, and the like) is preferable.

[0174] As the inorganic acid polyvalent metal salt, a nitric acid polyvalent metal salt, a hydrochloric acid polyvalent metal salt, or a thiocyanic acid polyvalent metal salt is preferred.

[0175] As the polyvalent metal salt, for example, a salt of an alkaline earth metal (e.g., magnesium, calcium) of Group 2 of the periodic table, a salt of a transition metal (e.g., lanthanum) of Group 3 of the periodic table, a salt of a metal (e.g., aluminum) of Group 13 of the periodic table, and a salt of an anthanide (e.g., neodymium) can be mentioned.

[0176] As the polyvalent metal salt, a calcium salt, a magnesium salt, or an aluminum salt is preferred, and a calcium salt or a magnesium salt is more preferred.

[0177] As the polyvalent metal compound, an organic acid polyvalent metal salt is preferred, and an organic acid calcium salt or an organic acid magnesium salt is more preferred.

[0178] It is preferred that at least a part of the polyvalent metal compound dissociates into a polyvalent metal ion and a counter ion in the pretreatment liquid.

[0179] The content of the coagulant in the pretreatment liquid is preferably 0.1 to 40 mass%, more preferably 0.1 to 30 mass%, further preferably 1 to 20 mass%, and particularly preferably 1 to 10 mass%, relative to the total amount of the pretreatment liquid.

[0180] - Resin -

[0181] The pretreatment liquid contains at least one kind of resin.

[0182] The resin in the pretreatment liquid contributes to the film-forming property of the pretreatment liquid (i.e., the forming property of the pretreatment liquid film).

[0183] As the resin in the pretreatment liquid, the same resin (e.g., resin particles) as that in the ink can be used.

[0184] The content of the resin in the pretreatment liquid is not particularly limited.

[0185] The content of the resin is preferably 0.5 to 30 mass%, more preferably 1 to 20 mass%, and particularly preferably 1 to 15 mass%, relative to the total amount of the pretreatment liquid.

[0186] - Water-soluble organic solvent -

[0187] The pretreatment liquid can contain at least one kind of water-soluble organic solvent.

[0188] As the water-soluble organic solvent in the pretreatment liquid, the same solvent as that which can be contained in the ink can be used.

[0189] - Additive -

[0190] The pre-treatment liquid can contain, as necessary, additives such as a surfactant, a water-soluble resin, a co-sensitizer, a UV absorber, an antioxidant, a color fading preventive, a conductive salt, an alkaline compound, and the like.

[0191] -Physical properties-

[0192] The pH of the pre-treatment liquid (25°C) is preferably 2.0 to 7.0, more preferably 2.0 to 4.0. The pH of the pre-treatment liquid is measured by the same method as the pH of the ink.

[0193] From the viewpoint of the coatability of the pre-treatment liquid, the viscosity of the pre-treatment liquid is preferably 0.5 mPa-s to 10 mPa-s, more preferably 1 mPa-s to 5 mPa-s. The viscosity is a value measured at 25°C using a viscometer. The viscosity of the pre-treatment liquid is measured by the same method as the viscosity of the ink.

[0194] The surface tension of the pre-treatment liquid is preferably 60 mN / m or less, more preferably 20 mN / m to 50 mN / m, further preferably 30 mN / m to 45 mN / m. The surface tension is a value measured at a temperature of 25°C. The surface tension of the pre-treatment liquid is measured by the same method as the surface tension of the ink.

[0195] (Method of imparting the pre-treatment liquid)

[0196] The method of imparting the pre-treatment liquid is not particularly limited, and known methods such as a coating method, an immersion method, an inkjet recording method, and the like can be given.

[0197] As the coating method, known methods using a bar coater, an extrusion die coater, an air knife coater, a blade coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, and the like can be given.

[0198] The imparting of the pre-treatment liquid is preferably performed by a coating method.

[0199] The image recording method of the present application can include a step of drying the pre-treatment liquid imparted to the substrate after the pre-treatment liquid imparting step.

[0200] The step of imparting the pre-treatment liquid can include a step of drying the pre-treatment liquid imparted to the non-penetrable substrate.

[0201] The drying method of the pre-treatment liquid is not particularly limited, and for example, the same methods as those exemplified as the drying method of the ink described later can be applied.

[0202] The preferable range of the drying conditions (e.g., heating temperature and heating time) of the pretreatment liquid is the same as that of the drying conditions of the ink described later.

[0203] <Step of imparting the first ink>

[0204] The image recording method of the present application includes a step of imparting a first ink containing water, a first pigment, and a resin to a region to which a pretreatment liquid has been imparted on a non-permeable substrate using an inkjet recording method.

[0205] <First ink>

[0206] The first ink contains water, a first pigment, and a resin.

[0207] -Water-

[0208] The first ink contains water.

[0209] The content of water is preferably 10% by mass or more, more preferably 20% by mass or more, further preferably 30% by mass or more, and particularly preferably 50% by mass or more, relative to the total amount of the first ink.

[0210] The upper limit of the content of water relative to the total amount of the first ink is appropriately determined depending on the content of other components, but is, for example, 99% by mass, preferably 95% by mass, and more preferably 90% by mass.

[0211] -First pigment-

[0212] The first ink contains at least one first pigment.

[0213] The first pigment can be any of the commonly commercially available organic pigments and inorganic pigments.

[0214] As the first pigment, for example, pigments described in "Encyclopedia of Pigments" edited by Ito Seijiro (published in 2000), W. Herbst, K. Hunger "Industrial Organic Pigments", Japanese Patent Application Laid-Open No. 2002-12607, Japanese Patent Application Laid-Open No. 2002-188025, Japanese Patent Application Laid-Open No. 2003-26978, and Japanese Patent Application Laid-Open No. 2003-342503 can be mentioned.

[0215] Further, the first pigment can be a water-insoluble pigment that can be dispersed in water by a dispersant, or can be a self-dispersing pigment.

[0216] The self-dispersing pigment is a pigment that can be dispersed in water even without using a dispersant.

[0217] The self-dispersible pigment is, for example, a compound in which at least one of hydrophilic groups such as carbonyl, hydroxyl, carboxyl, sulfo, phosphoric acid group, and salts thereof is directly or via other groups chemically bonded to the surface of the pigment.

[0218] The first pigment can be a color (e.g., cyan, magenta, yellow, etc.) pigment, or a non-color (e.g., white and black) pigment.

[0219] From the viewpoint of image density and dischargeability, the content of the first ink with respect to the total amount of ink is preferably 1 to 25 mass%, more preferably 2 to 25 mass%, and further preferably 3 to 20 mass%.

[0220] Resin

[0221] The first ink contains at least one kind of resin.

[0222] The resin in the first ink can contribute to the film-forming property of the ink, i.e., the formability of the ink film.

[0223] The weight average molecular weight (Mw) of the resin is preferably 1,000 to 300,000, more preferably 2,000 to 200,000, and further preferably 5,000 to 100,000.

[0224] In the present application, unless otherwise specifically stated, the weight average molecular weight (Mw) indicates a value measured by gel permeation chromatography (GPC).

[0225] For the measurement by gel permeation chromatography (GPC), HLC (registered trademark) -8020 GPC (TOSOH CORPORATION) was used as the measurement device, three TSKgel (registered trademark) Super Multipore HZ-H (4.6 mm ID x 15 cm, TOSOH CORPORATION) were used as the column, and THF (tetrahydrofuran) was used as the eluent. Also, as the measurement conditions, the sample concentration was set to 0.45 mass%, the flow rate was set to 0.35 ml / min, the sample injection amount was set to 10 μl, and the measurement temperature was set to 40°C, and measurement was performed using an RI detector.

[0226] The calibration curve was prepared using eight samples of "Standard Sample TSK standard, polystyrene" of TOSOH CORPORATION: "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000", and "n-Propylbenzene".

[0227] As the resin, a pigment dispersing resin as a pigment dispersing agent can be mentioned.

[0228] As the resin, resin particles can also be cited.

[0229] The first ink can contain at least one kind of pigment dispersing resin.

[0230] The pigment dispersing resin is a resin having a function of dispersing a pigment.

[0231] The pigment dispersing resin can be a random copolymer or a block copolymer.

[0232] The pigment dispersing resin can have a crosslinked structure.

[0233] The first ink can be prepared using a pigment dispersion liquid containing a pigment and a pigment dispersing resin.

[0234] As the pigment dispersing resin, for example, a known polymer dispersant such as the polymer dispersant described in paragraphs 0029 to 0106 of International Publication No. 2021 / 221069 can be used.

[0235] In the case where the first ink contains the pigment dispersing resin, the ratio of the content of the first pigment to the content of the pigment dispersing resin in the first ink is preferably 1:0.04 to 1:3, more preferably 1:0.05 to 1:1, and further preferably 1:0.05 to 1:0.5 on a mass basis.

[0236] In the case where the first ink contains the pigment dispersing resin, the content of the pigment dispersing resin is preferably 0.1 to 10 mass%, more preferably 0.3 to 5 mass%, and further preferably 0.5 to 2.5 mass% relative to the total amount of the first ink.

[0237] The first ink can contain at least one kind of resin particle.

[0238] The resin constituting the resin particle is preferably a water-insoluble resin. "Water-insoluble" in the water-insoluble resin means a property in which the amount of dissolution is less than 2 g with respect to 100 g of distilled water at 25°C.

[0239] The volume average particle diameter of the resin particle is preferably 1 to 300 nm, more preferably 3 to 200 nm, and further preferably 5 to 150 nm.

[0240] In the present application, the volume average particle diameter means a value measured with a laser diffraction / scattering type particle size distribution meter.

[0241] As the measuring device, for example, a particle size distribution measuring device "Microtrac MT-3300II" (manufactured by Nikkiso Co., Ltd.) can be cited.

[0242] As the resin particles, at least one selected from the group consisting of acrylic resin particles, ester resin particles, a mixture of acrylic resin particles and ester resin particles, composite particles containing an acrylic resin and an ester resin, styrene acrylic resin particles, and polyurethane resin particles is preferred.

[0243] In the present application, the acrylic resin means a polymer (homopolymer or copolymer) containing a raw material monomer selected from at least one of the group consisting of acrylic acid, a derivative of acrylic acid (for example, an acrylic ester, etc.), methacrylic acid, and a derivative of methacrylic acid (for example, a methacrylic ester, etc.).

[0244] From the viewpoint of further improving the wear resistance of the image, the glass transition temperature (Tg) of the resin particles is preferably 50°C to 250°C, and more preferably 50°C to 150°C.

[0245] Here, the glass transition temperature (Tg) of the resin particles is measured Tg obtained by measurement. As to the measurement method of the measured Tg, reference can be made to paragraph 0111 of Japanese Patent Application Publication No. 2015-25076.

[0246] As to the resin particles, reference can be made to, for example, paragraphs 0038 to 0114 of International Publication No. 2021 / 192720, paragraphs 0109 to 0120 of Japanese Patent Application Publication No. 2015-25076, etc.

[0247] In the case where the first ink contains the resin particles, the content of the resin particles in the first ink is preferably 1% by mass to 20% by mass, more preferably 2% by mass to 15% by mass, and further preferably 2% by mass to 10% by mass, with respect to the total amount of the first ink.

[0248] - Water-soluble organic solvent -

[0249] The first ink preferably contains at least one water-soluble organic solvent.

[0250] Thereby, the discharge stability from the inkjet head can be ensured.

[0251] The water-soluble organic solvent contained in the first ink can be one or two or more.

[0252] In the present application, the "water-soluble" in the "water-soluble organic solvent" means a property of dissolving 1 g or more with respect to 100 g of water at 25°C.

[0253] The kind of the water-soluble organic solvent that can be contained in the first ink is not limited, and, for example, the following can be mentioned:

[0254] A monoalcohol having 1 to 4 carbon atoms;

[0255] 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2-buten-1,4-diol, 2-ethyl-1,3-hexanediol, 2-methyl-2,4-pentanediol, 1,2-octanediol, 1,2-hexanediol, 1,2-pentanediol, 4-methyl-1,2-pentanediol, and the like diols;

[0256] glycerin, 1,2,6-hexanetriol, trimethylolpropane, and the like triols;

[0257] ethylene glycol, propylene glycol, and the like alkylene glycols;

[0258] ethylene glycol monoalkyl ether, propylene glycol monoalkyl ether, and the like alkylene glycol monoalkyl ethers;

[0259] diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, dipropylene glycol, polyoxyethylene polyoxypropylene glycol, and the like polyalkylene glycols;

[0260] diethylene glycol monoalkyl ether, triethylene glycol monoalkyl ether, tripropylene glycol monoalkyl ether, polyoxypropylene glyceryl ether, and the like polyalkylene glycol ethers; and

[0261] 2-pyrrolidone, N-methyl-2-pyrrolidone, and the like.

[0263] From the viewpoint of discharge stability, the water-soluble organic solvent in the first ink preferably contains at least one selected from the group consisting of alkylene glycols and alkylene glycol monoalkyl ethers.

[0264] The content of the water-soluble organic solvent is preferably 10 to 40% by mass, more preferably 15 to 30% by mass, with respect to the total amount of the first ink.

[0265] - Additives -

[0266] The first ink can contain, as needed, surfactants, water-soluble resins, co-sensitizers, ultraviolet absorbers, antioxidants, anti-fading agents, electrically conductive salts, basic compounds, and the like additives.

[0267] - Physical properties -

[0268] From the viewpoint of improving discharge stability, the pH (25°C) of the first ink is preferably 7 to 10, more preferably 7.5 to 9.5.

[0269] The pH of the ink is measured at 25°C using a pH meter, for example, a pH meter (product name "WM-50EG") manufactured by DKK-TOA CORPORATION.

[0270] The viscosity of the first ink (25°C) is preferably 0.5 mPa-s to 30 mPa-s, more preferably 2 mPa-s to 20 mPa-s, preferably 2 mPa-s to 15 mPa-s, and further preferably 3 mPa-s to 10 mPa-s.

[0271] The viscosity of the first ink is measured at 25°C using a viscometer, for example, a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

[0272] The surface tension of the first ink is preferably 60 mN / m or less, more preferably 20 mN / m to 50 mN / m, and further preferably 25 mN / m to 40 mN / m.

[0273] The surface tension of the first ink is measured at 25°C using a surface tension meter, for example, an automatic surface tension meter (product name "CBVP-Z") manufactured by Kyowa Interface Science Co., Ltd. and measured by a plate method.

[0274] (Method of imparting the first ink)

[0275] In the process of imparting the first ink, the first ink is imparted onto the region of the non-permeable substrate to which the pretreatment liquid is imparted using an inkjet recording method.

[0276] The discharge method of the ink in the inkjet recording method is not particularly limited and can be a publicly known method, for example, any one of a charge control method in which ink is discharged using electrostatic induction force, a drop-on-demand method (pressure pulse method) in which ink is discharged using the vibration pressure of a piezoelectric element, an acoustic inkjet method in which an electric signal is converted into an acoustic beam and irradiated onto ink and ink is discharged using the radiation pressure, and a thermal inkjet (Bubble Jet (registered trademark)) method in which ink is heated to form a bubble and ink is discharged using the pressure generated thereby.

[0277] As the inkjet recording method, in particular, the method described in Japanese Patent Application Laid-Open No. 54-59936, a method in which ink that has been subjected to thermal energy undergoes a sharp change in volume and ink is discharged from a nozzle using the force generated by the change in state can be effectively used. As the inkjet recording method, the method described in paragraphs 0093 to 0105 of Japanese Patent Application Laid-Open No. 2003-306623 can also be applied.

[0278] The process of imparting the first ink onto the non-permeable substrate by the inkjet recording method is performed by discharging the first ink from the nozzles of the inkjet head.

[0279] As a method of the inkjet head, there are a shuttle method (a multi-pass method) in which a short bar-shaped serial head is caused to scan in a width direction of a recording medium while recording is performed, and a line method (a single-pass method) in which a line head having recording elements arranged corresponding to the entire area of one side of the recording medium is used.

[0280] In the line method, by causing the recording medium to scan in a direction intersecting the arrangement direction of the recording elements, image recording can be performed on the entire surface of the recording medium. In the line method, a conveying system such as a carriage that causes the short bar-shaped head to scan in the shuttle method is not required. Also, in the line method, compared to the shuttle method, movement of the carriage and complicated scanning control of the recording medium are not required, and only the recording medium moves. Therefore, according to the line method, compared to the shuttle method, high speed of image recording can be achieved.

[0281] Regarding the application of the first ink, it is preferable to use an inkjet head having a resolution of 300 dpi or more (more preferably 600 dpi or more, and further preferably 800 dpi or more). Here, dpi is an abbreviation of dot per inch, and 1 inch is 2.54 cm.

[0282] Also, the preferable range of the volume of the droplets of the first ink (V1; pL) at the time of discharging the first ink is as described above.

[0283] The step of applying the first ink can include a step of heat-drying the first ink applied to the area of the non-penetrable substrate to which the pretreatment liquid has been applied, or can not include a step of heat-drying the first ink.

[0284] In the case where the step of heat-drying the first ink is included, the method of heat-drying is not particularly limited, and for example, infrared (IR) drying, warm air drying (for example, a dryer or the like), heat-drying using a heating device (for example, a heater, a hot plate, a heating furnace, or the like), or the like can be mentioned.

[0285] As the method of heat-drying, a method in which two or more of these are combined can also be used.

[0286] Regarding the heat-drying, it can be performed by heating the first ink from at least one of the image recording surface side and the non-image recording surface side of the substrate.

[0287] In the case where the step of heat-drying the first ink is included, the heating temperature in the heat-drying of the first ink is preferably 35°C or more, more preferably 40°C or more, further preferably 50°C or more, and particularly preferably 60°C or more.

[0288] The upper limit of the heating temperature is not particularly limited, and is preferably 100°C, more preferably 90°C.

[0289] In the case where the process of heating and drying the first ink is included, the heating time in the heating and drying of the first ink is not particularly limited, and is preferably 1 second to 180 seconds, more preferably 1 second to 120 seconds, and further preferably 1 second to 60 seconds.

[0290] <Process of applying the second ink>

[0291] The image recording method of the present application includes a process of applying a second ink containing water, a second pigment, and a resin to a region to which a pretreatment liquid and a first ink have been applied on a non-permeable substrate using an inkjet recording method.

[0292] By this process, a multicolor image having a structure in which an image derived from the second ink is superimposed on an image derived from the first ink is formed.

[0293] By having each of the processes as described above, bleeding and hiding of dots of the second ink can be suppressed in the multicolor image.

[0294] (Second ink)

[0295] The second ink contains water, a second pigment, and a resin.

[0296] Specific examples of the second pigment contained in the second ink are the same as those of the first pigment contained in the first ink.

[0297] However, the hue of the second pigment contained in the second ink is preferably different from that of the first pigment contained in the first ink.

[0298] Thus, the effects of suppressing bleeding and hiding of dots of the second ink are more easily visually recognized.

[0299] The preferable modes of the second ink are the same as those of the first ink except for the pigment.

[0300] The preferable modes of the method of applying the second ink are the same as those of the method of applying the first ink.

[0301] <Process of applying the third ink>

[0302] The image recording method of the present application can include a process of applying a third ink containing water, a third pigment, and a resin to a region to which a pretreatment liquid, a first ink, and a second ink have been applied on a non-permeable substrate using an inkjet recording method.

[0303] Specific examples of the third pigment contained in the third ink are the same as those of the first pigment contained in the first ink.

[0304] However, the hue of the third pigment contained in the third ink is preferably different from either one of the first pigment contained in the first ink and the second pigment contained in the second ink.

[0305] The preferable mode of the third ink is the same as that of the first ink except that the pigments are different.

[0306] The preferable mode of the method of applying the third ink is also the same as that of the method of applying the first ink.

[0307] In the case where the acid value (mgKOH / g) of the third ink is denoted by Av3, it is preferable to satisfy the inequality "Av1>Av2>Av3".

[0308] Thus, the graininess of the multicolor image is further improved. That is, the periodic unevenness of the multicolor image is further suppressed.

[0309] <Step of applying the fourth ink>

[0310] The image recording method of the present application can include:

[0311] a step of applying a third ink containing water, a third pigment, and a resin to a region on a non-penetrable substrate to which a pretreatment liquid, a first ink, and a second ink have been applied using an inkjet recording method; and

[0312] a step of applying a fourth ink containing water, a fourth pigment, and a resin to a region on a non-penetrable substrate to which a pretreatment liquid, a first ink, a second ink, and a third ink have been applied using an inkjet recording method.

[0313] The step of applying the third ink is as described above.

[0314] Specific examples of the fourth pigment contained in the fourth ink are the same as those of the first pigment contained in the first ink.

[0315] However, the hue of the fourth pigment contained in the fourth ink is preferably different from any one of the first pigment contained in the first ink, the second pigment contained in the second ink, and the third pigment contained in the third ink.

[0316] The preferable mode of the fourth ink is the same as that of the first ink except that the pigments are different.

[0317] The preferable mode of the method of applying the fourth ink is also the same as that of the method of applying the first ink.

[0318] In the image recording method of the present application of the mode including the process of applying the third ink and the process of applying the fourth ink, in a case where the acid value (mgKOH / g) of the third ink is denoted as Av3 and the acid value (mgKOH / g) of the fourth ink is denoted as Av4, it is preferable that the following inequality (4) is satisfied.

[0319] Av1 > Av2 > Av3 > Av4... Inequality (4)

[0320] Thus, the granular property of the multicolor image is further improved. That is, the periodic unevenness of the multicolor image is further suppressed.

[0321] <Process of applying white ink>

[0322] In the image recording method of the present application, in a case where neither the first ink nor the second ink is a white ink, the image recording method of the present application can include a process of applying a white ink containing water, a white pigment, and a resin on at least a region of a non-penetrable substrate on which a pretreatment liquid, the first ink, and the second ink are applied using an inkjet recording method.

[0323] Thus, it is possible to at least conceal (that is, cover up) the multicolor image derived from the first ink and the second ink by the white image derived from the white ink.

[0324] (White pigment)

[0325] As the white pigment, for example, titanium dioxide, barium sulfate, calcium carbonate, silicon dioxide, zinc oxide, zinc sulfide, mica, talc, pearl, and the like can be given.

[0326] From the viewpoint of concealment, the average primary particle diameter of the white pigment is preferably 150 nm or more, and more preferably 200 nm or more. Also, from the viewpoint of discharge property of the ink, the average primary particle diameter of the white pigment is preferably 400 nm or less, and more preferably 350 nm or less. The average primary particle diameter of the white pigment is preferably 150 nm to 400 nm.

[0327] In the present application, the average primary particle diameter of the white pigment is a value measured using a transmission electron microscope (TEM). Specifically, it is a value obtained by selecting 50 arbitrary white pigments present in a field of view observed with the TEM, measuring the primary particle diameters of the 50, and averaging them. As the transmission electron microscope, a transmission electron microscope 1200EX manufactured by JEOL Ltd. can be used.

[0328] The white pigment can be a hollow particle. The hollow particle is a particle having a void inside. If the hollow particle is contained in the ink according to the difference in refractive index between the shell and the void of the hollow particle, an ink exhibiting white color can be obtained.

[0329] As the hollow particles, for example, hollow resin particles and inorganic hollow particles can be given.

[0330] As the resin constituting the hollow resin particles, for example, acrylic resin, styrene-acrylic resin, crosslinked styrene-acrylic resin, urethane resin, and maleic acid-based copolymer can be given.

[0331] As the inorganic material constituting the inorganic hollow particles, for example, silica, alumina, titanium oxide, and zinc oxide can be given.

[0332] Among them, the white pigment preferably contains at least one selected from the group consisting of titanium dioxide and hollow particles.

[0333] (Acid value of white ink)

[0334] The acid value of the white ink is preferably higher than the acid value of other inks (for example, at least higher than the acid value of the first ink and the second ink).

[0335] Thereby, the unevenness of the white image can be further suppressed.

[0336] For example, in the case where the image recording method of the present application includes a process of applying the first ink, a process of applying the second ink, a process of applying the third ink, and a process of applying the fourth ink, and also includes a process of applying the white ink on the region of the non-penetrable substrate to which the pretreatment liquid, the first ink, the second ink, the third ink, and the fourth ink are applied using an inkjet recording method, the acid value (mgKOH / g) of the white ink is preferably higher than any one of Av1, Av2, Av3, and Av4.

[0337] Thereby, the unevenness of the white image can be further suppressed.

[0338] [Image recording apparatus]

[0339] The image recording apparatus of the present application is used for the image recording method of the present application, and the image recording apparatus includes:

[0340] a pretreatment liquid applying device for applying the pretreatment liquid on one surface of the non-penetrable substrate;

[0341] a first inkjet head for applying the first ink; and

[0342] a second inkjet head for applying the second ink,

[0343] the value (1) is 28.0 to 35.0,

[0344] the value (2) is -200 to 200.

[0345] [Example of image recording apparatus]

[0346] Figure 1 This is a schematic diagram illustrating an example of an image recording apparatus used in the image recording method of the present invention.

[0347] like Figure 1 As shown, one embodiment of the inkjet recording apparatus is an example of an inkjet recording apparatus equipped with a transport mechanism for transporting resin substrate in a roll-to-roll manner, and is as follows: a non-permeable substrate A1, which is wound into a roll and shaped like a long strip film, is unwound by an unwinding device R1, and the unwound non-permeable substrate A1 is transported in the direction of the solid arrow under tension, so that it passes sequentially through a pretreatment liquid application device P1, a pretreatment liquid drying area DP1, a first inkjet head IJ1, a first drying area D1, a second inkjet head IJ2, and a second drying area D2, and is finally wound up by a winding device R2 containing a core under tension P.

[0348] The non-permeable substrate A1 is conveyed under tension and wound up under tension P. The tension during conveying can be the same as the tension P during winding, or it can be a different tension. Furthermore, the tension can vary depending on the position in the conveying direction, or it can be the same tension.

[0349] One embodiment of the image recording apparatus may include a tension adjustment mechanism for adjusting the tension of a non-permeable substrate.

[0350] Examples of tension adjustment mechanisms include:

[0351] A powder brake is installed in the unwinding device R1 and / or the winding device R2.

[0352] Tension adjustment rollers (dancer rollers) installed along the conveying path; and

[0353] Control devices that control tension by adjusting various conditions of the image recording device (e.g., tension controllers).

[0355] Furthermore, the image recording apparatus according to one embodiment may include a tension measuring mechanism (e.g., a tension meter) for measuring the tension of a non-permeable substrate.

[0356] in addition, Figure 1 This is a schematic diagram, thus simplifying the transport path of the non-permeable substrate A1. The diagram shows the non-permeable substrate A1 being transported in one direction, but in reality, the transport path of the non-permeable substrate A1 is sometimes tortuous, which goes without saying.

[0357] As the conveyance method of the non-penetrable substrate Al, various web conveyance methods such as a tube, a roll, and the like can be appropriately selected.

[0358] With respect to the unwinding device Rl for unwinding the non-penetrable substrate Al, a pretreatment liquid application device Pl, a pretreatment liquid drying region DP1, a first inkjet head IJl, a first drying region Dl, a second inkjet head IJ2, and a second drying region D2 are sequentially arranged on a downstream side in a conveyance direction of the non-penetrable substrate Al from an upstream side in the conveyance direction of the non-penetrable substrate Al.

[0359] The application of the pretreatment liquid, the application of the first ink, and the application of the second ink are performed by the pretreatment liquid application device Pl, the first inkjet head IJl, and the second inkjet head IJ2, respectively.

[0360] At this time, at least one of the heat drying of the pretreatment liquid in the pretreatment liquid drying region DP1, the heat drying of the first ink in the first drying region Dl, and the heat drying of the second ink in the second drying region D2 can be performed.

[0361] In the first drying region Dl, in addition to the heat drying of the first ink, the heat drying of the pretreatment liquid can also be substantially performed.

[0362] In the second drying region D2, in addition to the heat drying of the second ink, the heat drying of the pretreatment liquid and / or the heat drying of the first ink can also be substantially performed.

[0363] Furthermore, if the resin substrate is passed through each drying region in a state where the temperature of each drying region is set to room temperature, the heat drying can also be omitted.

[0364] In one embodiment, the first ink is any one of a non-white ink containing water and a colorant for recording a non-white image and a white ink containing water and a colorant for recording a white image, and the second ink is the other of the above-described non-white ink and the above-described white ink.

[0365] With respect to the pretreatment liquid application device Pl on the upstream side, a surface treatment portion (not shown) for performing surface treatment (preferably, corona treatment) on at least one of the front surface and the back surface of the non-penetrable substrate Al can be provided.

[0366] Furthermore, on the downstream side of the second drying region D2, a cooling region for cooling the recorded multicolor image (i.e., a multicolor image including a white image and a non-white image) can be provided.

[0367] The first inkjet head IJ1 and the second inkjet head IJ2 can be shuttle type heads, but from the viewpoint of increasing the speed of image recording, it is preferable that they are line type heads in which a plurality of discharge ports (nozzles) are arranged in the width direction of the long film-shaped non-penetrable substrate Al.

[0368] The first inkjet head IJ1 and the second inkjet head IJ2 can each be one or a plurality of heads.

[0369] As an example of the combination of the first inkjet head IJ1 and the second inkjet head IJ2, for example, the following combination can be given: the first inkjet head IJ1 is four inkjet heads corresponding to four colors of cyan, magenta, yellow and black (Note: the four inkjet heads are arranged in the conveyance direction of the resin substrate), and the second inkjet head IJ2 is one inkjet head corresponding to white (i.e., white).

[0370] Also, as another example of the combination of the first inkjet head IJ1 and the second inkjet head IJ2, the following combination can be given: the first inkjet head IJ1 is one inkjet head corresponding to white, and the second inkjet head IJ2 is four inkjet heads corresponding to four colors of cyan, magenta, yellow and black (Note: the four inkjet heads are arranged in the conveyance direction of the substrate).

[0371] In inkjet recording using the image recording apparatus according to an embodiment,

[0372] First, the long film-shaped non-penetrable substrate Al wound in a roll shape is unwound by the unwinding device R1,

[0373] The unwound non-penetrable substrate Al is conveyed in the direction of the solid arrow in a state in which tension is applied,

[0374] On the conveyed non-penetrable substrate Al, application of a pre-treatment liquid is performed by the pre-treatment liquid application device P1,

[0375] Next, the pre-treatment liquid is dried as necessary in the pre-treatment liquid drying region DP1,

[0376] Next, application of a first ink (i.e., either of a non-white ink and a white ink) is performed by the first inkjet head IJ1,

[0377] Next, the first ink is dried as necessary in the first drying region D1,

[0378] Next, application of a second ink (i.e., the other of a non-white ink and a white ink) is performed by the second inkjet head IJ2,

[0379] Next, the second ink is dried as necessary in the second drying region D2.

[0380] Thus, a multicolor image including a first image (i.e., either of a non-white image and a white image) derived from the first ink and a second image (i.e., the other of the non-white image and the white image) derived from the second ink can be obtained.

[0381] Next, the obtained multicolor image is cooled as necessary, and finally, the non-permeable base material Al with the multicolor image applied thereto in a state of being subjected to the tension P is wound up by the winding device R2 including the winding core.

[0382] The image recording apparatus according to an embodiment can include other inkjet heads (e.g., a third inkjet head for a third ink, a fourth inkjet head for a fourth ink, and an inkjet head for a white ink, etc.) on the downstream side of the second inkjet head IJ2 and on the more upstream side than the second drying region D2 as necessary.

[0383] Embodiments

[0384] Embodiments of the present application are shown below, but the present application is not limited to the following embodiments.

[0385] [Embodiments 1 to 18, Comparative Examples 1 to 4]

[0386] Preparation of a pretreatment liquid

[0387] The components shown below were mixed to prepare a pretreatment liquid of the following composition.

[0388] Composition of the pretreatment liquid

[0389] Calcium acetate [coagulant]

[0390] ... 0.2 mass%

[0391] Calcium formate [coagulant]

[0392] ... 1.7 mass%

[0393] Calcium lactate [coagulant]

[0394] ... 2.2 mass%

[0395] Propylene glycol [solvent]

[0396] ... 2.0 mass%

[0397] OLFINE E1010 (manufactured by Nissin Chemical co., ltd.) [surfactant]

[0398] ... 0.5 mass%

[0399] SUPER FLEX M500 (manufactured by DKS Co. Ltd.) [water dispersion of urethane resin particles]

[0400] ... 9.3 mass %

[0401] • ultra-pure water

[0402] ... the balance of the pretreatment liquid becomes 100 mass %

[0403] <Preparation of black ink K1>

[0404] The components shown below were mixed to prepare black ink K1.

[0405] Black ink K1 was used as the first ink or the second ink.

[0406] Details of which of the first ink and the second ink to use black ink K1 and each of the following inks are shown in Tables 1 and 2 below.

[0407] - Composition of black ink K1 -

[0408] • APD4000 Black (manufactured by Fujifilm Imaging Colorants Ltd.)

[0409] ... 3.2 mass % as the content of the pigment

[0410] • propylene glycol monomethyl ether (PGmME) [water-soluble organic solvent]

[0411] ... 3 mass %

[0412] • propylene glycol (PG) [water-soluble organic solvent]

[0413] ... 20 mass %

[0414] • Neocryl A-1091 (manufactured by DSM) [styrene acrylic resin particle dispersion liquid]

[0415] ... 5.0 mass % as the content of the styrene acrylic resin particle

[0416] • OLFINE E1010 (manufactured by Nissin Chemical co., ltd.) [acetylene glycol-based surfactant]

[0417] ... 2.2 mass %

[0418] • BYK345 (manufactured by BYK) [silicone-based surfactant]

[0419] ... 0.2 mass %

[0420] • PVP K15 (manufactured by Tokyo Chemical Industry Co., Ltd.) (polyvinylpyrrolidone K15)

[0421] ... 0.15% by mass

[0422] • ST-XS (manufactured by Nissan Chemical Corporation) [colloidal silica dispersion liquid]

[0423] ... 0.05% by mass in terms of colloidal silica particle content

[0424] • Water

[0425] ... the balance to 100% by mass of the entire ink

[0426] Preparation of Black Ink K2

[0427] In the preparation of Black Ink K1,

[0428] "Neocryl A-1091 (manufactured by DSM) [styrene acrylic resin particle dispersion liquid]

[0429] ... 5.0% by mass in terms of styrene acrylic resin particle content" was changed to

[0430] "NeoRez R940 (manufactured by Kusumoto Chemicals, Ltd.) [urethane resin particle dispersion liquid]

[0431] ... 8.4% by mass in terms of urethane resin particle content",

[0432] Other than this, Black Ink K2 was prepared in the same manner as the preparation of Black Ink K1.

[0433] Black Ink K1 was used as the first ink or the second ink (see Tables 1 and 2 for details).

[0434] Preparation of Black Inks K3 to K5 (comparative examples)

[0435] In the preparation of Black Ink K1, the amount of OLFINE E1010 and the amount of BYK345 were changed so as to make the cosθ described later the values shown in Table 1, and other than this, Black Inks K3 to K5 used in the comparative examples were each prepared in the same manner as the preparation of Black Ink K1.

[0436] In K3, the amount of OLFINE E1010 was set to 1.9% by mass, and the amount of BYK345 was set to 0.3% by mass.

[0437] In K4, the amount of OLFINE E1010 was set to 0.1 mass%, and BYK 345 was not used.

[0438] In K5, the amount of OLFINE E1010 was set to 1.5 mass%, and the amount of BYK 345 was set to 0.7 mass%.

[0439] Black inks K3 to K5 were used as the first ink. Details are described in Table 2.

[0440] <Preparation of cyan ink C1>

[0441] The components shown below were mixed to prepare the cyan ink C1.

[0442] The cyan ink C1 was used as the first ink or the second ink (details are described in Tables 1 and 2).

[0443] -Composition of cyan ink C1-

[0444] • APD4000 Cyan (manufactured by Fujifilm Imaging Colorants Ltd.) [cyan pigment dispersion liquid]

[0445] ... 3.1 mass% as the content of the cyan pigment

[0446] • Propylene glycol monomethyl ether (PGmME) [water-soluble organic solvent]

[0447] ... 3 mass%

[0448] • Propylene glycol (PG) [water-soluble organic solvent]

[0449] ... 20 mass%

[0450] • Neocryl A-1091 (manufactured by DSM) [styrene acrylic resin particle dispersion liquid]

[0451] ... 5.5 mass% as the content of the resin particles

[0452] • OLFINE E1010 (manufactured by Nissin Chemical co., ltd.) [acetylene glycol-based surfactant]

[0453] ... 1.7 mass%

[0454] • BYK 345 (manufactured by BYK) [silicone-based surfactant]

[0455] ... 0.2 mass%

[0456] • PVP K15 (manufactured by Tokyo Chemical Industry Co., Ltd.) [polyvinylpyrrolidone K15]

[0457] ... 0.15% by mass

[0458] • ST-XS (manufactured by Nissan Chemical Corporation) [colloidal silica dispersion liquid]

[0459] ... 0.05% by mass in terms of the content of colloidal silica particles

[0460] • Water

[0461] ... the balance to 100% by mass of the entire ink

[0462] Preparation of Blue Ink C2

[0463] In the preparation of Blue Ink C1, the acid value was changed by changing the following point, and otherwise Blue Ink C2 was prepared in the same manner as in the preparation of Blue Ink C1.

[0464] Blue Ink C1 was used as the 2nd ink (see Tables 1 and 2 for details).

[0465] - Change points compared to Blue Ink C1 -

[0466] "Neocryl A-1091 (manufactured by DSM) [styrene acrylic resin particle dispersion liquid] 5.5% by mass" was changed to "Neocryl A-1120 (manufactured by DSM) [styrene acrylic resin particle dispersion liquid] 5.5% by mass".

[0467] Preparation of Magenta Ink M1

[0468] The ingredients shown below were mixed to prepare Magenta Ink M1.

[0469] Magenta Ink M1 was used as the 2nd ink or the 3rd ink (see Tables 1 and 2 for details).

[0470] - Composition of Magenta Ink M1 -

[0471] • APD4000 Magenta (manufactured by Fujifilm Imaging Colorants Ltd.)

[0472] ... 5.7% by mass in terms of the content of pigments

[0473] • Propylene glycol monomethyl ether (PGmME) [water-soluble organic solvent]

[0474] ... 3% by mass

[0475] • Propylene glycol (PG) [water-soluble organic solvent]

[0476] ... 20% by mass

[0477] • Neocryl A-1091 (manufactured by DSM) [styrene acrylic resin particle dispersion liquid]

[0478] ... 3.4% by mass based on the content of the resin particles

[0479] • OLFINE E1010 (manufactured by Nissin Chemical co., ltd.) [acetylene glycol-based surfactant]

[0480] ... 2.1% by mass

[0481] • BYK345 (manufactured by BYK) [silicone-based surfactant]

[0482] ... 0.2% by mass

[0483] • PVP K15 (manufactured by Tokyo Chemical Industry Co., Ltd.) [polyvinylpyrrolidone K15]

[0484] ... 0.15% by mass

[0485] • ST-XS (manufactured by Nissan Chemical Corporation) [colloidal silica dispersion liquid]

[0486] ... 0.05% by mass based on the content of the colloidal silica particles

[0487] • Water

[0488] ... the balance to 100% by mass of the entire ink

[0489] Preparation of Yellow Ink Y1

[0490] The components shown below were mixed, thereby preparing the yellow ink Y1.

[0491] The yellow ink Y1 was used as the 2nd ink or the 4th ink (see Tables 1 and 2 for details).

[0492] - Composition of Yellow Ink Y1 -

[0493] • APD4000 Yellow (manufactured by Fujifilm Imaging Colorants Ltd.)

[0494] ... 3.9% by mass based on the content of the pigment

[0495] • Propylene glycol monomethyl ether (PGmME) [water-soluble organic solvent]

[0496] ... 3 mass%

[0497] • Propylene glycol (PG) [water-soluble organic solvent]

[0498] ... 20 mass%

[0499] • Neocryl A-1091 (manufactured by DSM) [styrene acrylic resin particle dispersion liquid]

[0500] ... 6.0 mass% as content of resin particles

[0501] • OLFINE E1010 (manufactured by Nissin Chemical co., ltd.) [acetylene glycol-based surfactant]

[0502] ... 1.9 mass%

[0503] • BYK349 (manufactured by BYK) [silicone-based surfactant]

[0504] ... 0.2 mass%

[0505] • PVP K15 (manufactured by Tokyo Chemical Industry Co., Ltd.) [polyvinylpyrrolidone K15]

[0506] ... 0.15 mass%

[0507] • ST-XS (manufactured by Nissan Chemical Corporation) [colloidal silica dispersion liquid]

[0508] ... 0.05 mass% as content of colloidal silica particles

[0509] • Water

[0510] ... the balance to 100 mass% of the entire ink

[0511] Preparation of Yellow Ink Y2

[0512] In the preparation of Yellow Ink Y2, the acid value was changed by changing the following points, and otherwise, Yellow Ink Y2 was prepared in the same manner as in the preparation of Yellow Ink Yl.

[0513] Yellow Ink Y2 was used as the 2nd ink (see Tables 1 and 2 for details).

[0514] - Points of Change Compared to Yellow Ink Yl -

[0515] The content “Neocryl A-1091 (manufactured by DSM) [Styrene-Acrylic Resin Particle Dispersion] 6.0% by mass” is changed to “Neocryl A-6075 (manufactured by DSM) [Styrene-Acrylic Resin Particle Dispersion] 6.0% by mass”.

[0516] <Preparation of Yellow Ink Y3>

[0517] In the preparation of yellow ink Y1, the acid value was changed by altering the following points. Otherwise, yellow ink Y3 was prepared in the same manner as yellow ink Y1.

[0518] Yellow ink Y3 is used as the fourth ink.

[0519] -Changes compared to yellow ink Y1-

[0520] The content “Neocryl A-1091 (manufactured by DSM) [Styrene-Acrylic Resin Particle Dispersion] 6.0% by mass” is changed to “Neocryl A-6075 (manufactured by DSM) [Styrene-Acrylic Resin Particle Dispersion] 5.0% by mass”.

[0521] <Preparation of White Ink W1>

[0522] White ink W1 was prepared as follows.

[0523] (Synthesis of pigment dispersant (block polymer) for white pigment dispersion)

[0524] Referring to Synthesis Example 8 of Japanese Patent Application Publication No. 2015-83688, block polymer 1 was synthesized as a pigment dispersant for low-acid-value white pigment dispersions. Details are shown below.

[0525] Add to a reaction apparatus consisting of a 1L split-flask equipped with a stirrer, reflux condenser, thermometer, and nitrogen inlet pipe.

[0526] Diethylene glycol dimethyl ether (266 parts by weight; polymerization solvent)

[0527] 2-Iodo-2-cyanopropane (6.2 parts by mass; polymerization initiator compound),

[0528] Methyl methacrylate (MMA) (120 parts by weight; monomer),

[0529] Acrylic acid (AA) (28.8 parts by weight; monomer),

[0530] Cyclohexyl methacrylate (CHMA) (67.2 parts by weight; monomer),

[0531] Azobisdimethylvaleronitrile (7.9 parts by mass) and

[0532] 2-tert-butyl-4, 6-dimethylphenol (0.7 parts by mass; catalyst),

[0533] The mixture was stirred while passing nitrogen therethrough.

[0534] Next, the temperature of the mixture in the reaction device (reaction temperature) was raised to 70°C, and polymerization was performed for 3 hours, thereby obtaining a polymerization solution A containing a MMA / AA / CHMA copolymer.

[0535] After 3 hours, a portion of the above polymerization solution A was sampled and the solid content was measured, and as a result, the solid content was confirmed to be 42.0 mass%, and most of the monomers were polymerized.

[0536] Further, the molecular weight of the MMA / AA / CHMA copolymer was measured by GPC, and as a result, the weight average molecular weight (Mn) was 7,500.

[0537] The acid value of the MMA / AA / CHMA copolymer was 101.0 mgKOH / g.

[0538] Next, a mixture of benzyl methacrylate (BzMA) (35.2 parts by mass; monomer) and V-65 (0.3 parts by mass; radical generator) was added to the above polymerization solution A, and polymerization was performed at 70°C for 3 hours, thereby obtaining a polymerization solution B containing a block polymer 1 as a pigment dispersant for a low-acid-value white pigment dispersion liquid.

[0539] Here, the block polymer 1 is a block polymer containing an A block as a MMA / AA / CHMA copolymer and a B block as a BzMA homopolymer.

[0540] The solid content of the obtained polymerization solution B was measured, and as a result, the solid content was confirmed to be 43.2 mass%, and most of the monomers were polymerized.

[0541] Further, the Mw of the block polymer 1 was 8,500, and the acid value was 89.3 mgKOH / g.

[0542] (Preparation of a white pigment dispersion liquid)

[0543] The block polymer 1 (136.4 parts by mass), butylcarbitol (163.6 parts by mass), and CI pigment white 6 (product name "JR-405", (manufactured by TAYCA Co., Ltd.) [titanium dioxide particles]) (450 parts by mass) as a white pigment were blended and stirred using a disperser. Then, the white pigment was fully dispersed using a horizontal media disperser to obtain an oily pigment dispersion. The average particle size of the white pigment dispersed in the oily pigment dispersion was 290 nm. The viscosity of the oily pigment dispersion was 86.3 m³ Pa·s.

[0544] Next, while stirring the above-mentioned oily pigment dispersion (700 parts by weight) using a disperser, a mixture of potassium hydroxide (4.0 parts by weight) and water (341 parts by weight) was slowly added to it and neutralized. Then, the white pigment was fully dispersed using a horizontal media disperser to obtain a pigment dispersion.

[0545] Next, ultrafiltration was performed using an ultrafiltration apparatus (cross-flow ultrafiltration (UF), manufactured by Sartorius) by adding ion-exchanged water at a flow rate of 600 mL per minute to the obtained pigment dispersion. The filtrate temperature was maintained at 25°C, and ultrafiltration was performed 10 times, with each cycle consisting of one volume of the produced liquid. Ion-exchanged water was then added to obtain a low-acid-value white pigment dispersion with a white pigment concentration of 45% by mass and a block polymer concentration of 3.7% by mass.

[0546] (Preparation of white ink W1)

[0547] The following ingredients were mixed to prepare white ink W1.

[0548] -Composition of white ink W1-

[0549] The above-mentioned low-acid-value white pigment dispersion

[0550] ...12.5% ​​by mass based on pigment content.

[0551] Water-soluble organic solvents

[0552] Propylene glycol monomethyl ether (PGmME) [water-soluble organic solvent]

[0553] ...3% by mass

[0554] Propylene glycol (PG) [water-soluble organic solvent]

[0555] ...20% by mass

[0556] Neocryl A-1091 (manufactured by DSM) [Styrene-acrylic resin particle dispersion]

[0557] … 7 mass% as the content of the resin particles

[0558] • OLFINE E1010 (manufactured by Nissin Chemical co., ltd.) [acetylene glycol-based surfactant]

[0559] … 1.0 mass%

[0560] • BYK345 (manufactured by BYK) [silicone-based surfactant]

[0561] … 0.7 mass%

[0562] • PVP K15 (manufactured by Tokyo Chemical Industry Co., Ltd.) [polyvinylpyrrolidone K15]

[0563] … 0.15 mass%

[0564] • ST-XS (manufactured by Nissan Chemical Corporation) [colloidal silica dispersion liquid]

[0565] … 0.05 mass% as the content of the colloidal silica particles

[0566] • Water

[0567] … the balance to make 100 mass% of the entire ink

[0568] Preparation of White Ink W2

[0569] In the preparation of White Ink W1, the acid value was changed by changing the following points, and otherwise, White Ink W2 was prepared in the same manner as in the preparation of White Ink W1.

[0570] - Points of Change Compared to White Ink W1 -

[0571] The amount of "Neocryl A-1091 (manufactured by DSM) [styrene acrylic resin particle dispersion liquid]" was changed from "7.0 mass%" to "6.0 mass%".

[0572] Preparation of Image Recording Device

[0573] As an image recording device for evaluation, an image recording device shown in Fig. 1 was prepared. Figure 1

[0574] As a pre-treatment liquid application device P1, a gravure coater was used.

[0575] The drying method in the pre-treatment liquid drying area DP1 was set to warm air drying.​

[0576] An inkjet head for ejecting the first ink shown in Table 1 (for example, black ink Kl in Example 1) was configured as the first inkjet head IJl, and an inkjet head for ejecting the second ink shown in Table 1 (for example, cyan ink Cl in Example 1) was configured as the second inkjet head IJ2.

[0577] It was made to pass directly through the first drying area Dl.

[0578] The drying method in the second drying area D2 was set to warm air drying.

[0579] An air cooling area (not shown) was provided between the second drying area D2 and the take-up device R2.

[0580] As the first inkjet head IJl and the second inkjet head IJ2, a 1200 dpi (dot per inch, inch is 2.54 cm) / 20 inch width piezoelectric line head (2048 of all nozzle number) was used.

[0581] The drive frequency of the first inkjet head IJl and the second inkjet head IJ2 was set to 30 kHz.

[0582] <IMAGE RECORDING>

[0583] Image recording was performed using the above-described image recording device.

[0584] The above-described pretreatment liquid, the first ink, and the second ink were mounted in the image recording device.

[0585] As the non-penetrable substrate, an OPP film (product name "pylenct film-OT", manufactured by Toyobo Co., Ltd., thickness 25 μm) was used.

[0586] First, the non-penetrable substrate was unwound by the unwinding device Rl, and the unwound non-penetrable substrate was transported in a state where tension was applied. The non-penetrable substrate being transported was subjected to the application of the pretreatment liquid by the gravure coater as the pretreatment liquid application device P 1.

[0587] Next, the pretreatment liquid applied to the non-penetrable substrate was dried in the pretreatment liquid drying area DP 1.

[0588] Next, the first ink shown in Table 1 was applied to the area of the non-penetrable substrate to which the pretreatment liquid was applied in a solid image by the first inkjet head IJl, and it was made to pass directly through the first drying area Dl.

[0589] Next, the second ink is applied to the region of the non-penetrable substrate to which the pretreatment liquid and the first ink have been applied in a solid image shape by the second inkjet head IJ2.

[0590] Next, the second ink is dried in the second drying region D2.

[0591] By the above operation, a multicolor image (solid image) having a structure in which a solid image derived from the second ink is superimposed on a solid image derived from the first ink is recorded on the non-penetrable substrate of 1000 m in length, and thus an image recorded matter is obtained.

[0592] Next, after the obtained image recorded matter is subjected to air cooling, winding is performed by the winding device R2 including a winding core, and thus a wound material of the image recorded matter is obtained.

[0593] The amount of application of the pretreatment liquid is set to 1.7 g / m 2 .

[0594] The drying condition of the pretreatment liquid is set to 40°C for 3 seconds.

[0595] The drying condition of the second ink is set to 70°C for 20 seconds.

[0596] The distance between the first inkjet head IJ1 and the second inkjet head IJ2 (hereinafter, also referred to as the Bar-to-Bar distance),

[0597] The conveyance speed of the non-penetrable substrate,

[0598] The droplet ejection interval (T seconds) of the first ink and the second ink,

[0599] The volume of the droplet of the first ink at the time of ejection (V1; pL) and

[0600] The volume of the droplet of the second ink at the time of ejection (V2; pL)

[0601] Each is set to the value shown in Table 1 and Table 2.

[0602] <The contact angle Θ (°) of the first ink on the non-penetrable substrate to which the pretreatment liquid has been applied>

[0603] After the pretreatment liquid is applied to and dried on the non-penetrable substrate, the non-penetrable substrate to which the pretreatment liquid has been applied is cut, and thus a measurement sample is obtained. 2.0 μL of the first ink is dropped on the region to which the pretreatment liquid has been applied in the measurement sample, and the contact angle Θ (°) of the first ink at the time when T seconds have elapsed from the dropping is measured.

[0604] As for the contact angle, measurement was performed at 20°C using a contact angle meter (product name "DM-501", manufactured by Kyowa Interface Science Co., Ltd.).

[0605] The results obtained are shown in Tables 1 and 2.

[0606] <L*1 and L*2>

[0607] Under the same conditions as in the aforementioned image recording, a solid image of a single color was recorded for each of the first ink and the second ink.

[0608] From the back of the non-permeable substrate on which the solid image of a single color was recorded (i.e., the side opposite to the image recording surface), the L* value of the solid image of a single color was measured through the non-permeable substrate using an X-rite exact (manufactured by X-Rite Inc.). At this time, the white surface portion of a hiding rate measurement test paper manufactured by Toyo Gosei Co., Ltd. was laid on the image recording surface side of the non-permeable substrate, and the L* was measured.

[0609] The L* value of the solid image of a single color of the first ink was set as L*1, and the L* value of the solid image of a single color of the second ink was set as L*2.

[0610] The results obtained are shown in Tables 1 and 2.

[0611] <Av1 and Av2>

[0612] As for each of the first ink and the second ink, the acid value (mgKOH / g) was measured by the following method, and the value obtained was set as Av1 (mgKOH / g) and Av2 (mgKOH / g), respectively.

[0613] The results obtained are shown in Tables 1 and 2.

[0614] As for the acid value of each ink, a diluent in which each ink was diluted four times by volume with tetrahydrofuran (THF) was prepared, and after the diluent obtained was completely neutralized with KOH, titration was performed with HCl.

[0615] <Solid content S1 (mass%) in the first ink and solid content S2 (mass%) in the second ink>

[0616] The solid content S1 (mass%) in the first ink and the solid content S2 (mass%) in the second ink are shown in Tables 1 and 2.

[0617] S1 and S2 are each the content (mass%) of the solid content (i.e., pigments, pigment-dispersed resins, and resin particles) with respect to the total amount of the ink.

[0618] In the present examples and comparative examples, S1 and S2 were each calculated from the mass of the dried substance obtained by washing with 0.1 N hydrochloric acid after the ink was precipitated, filtering while washing with 0.1 N hydrochloric acid, and drying the residual solid component after filtration.

[0619] <Calculation of Value (1)>

[0620] Value (1) was calculated by the following equation.

[0621] The results are shown in Tables 1 and 2.

[0622] Value (1) = (V1) 1 / 3 x (1 + cos θ) x 14

[0623] <Calculation of Value (2)>

[0624] Value (2) was calculated by the following equation.

[0625] The results are shown in Tables 1 and 2.

[0626] In Tables 1 and 2, the value of |Av1 / S1 - Av2 / S2| is also shown.

[0627] Value (2) = |Av1 / S1 - Av2 / S2| x (Av2 - Av1) / T

[0628] <Calculation of Value (3)>

[0629] Value (3) was calculated by the following equation.

[0630] The results are shown in Tables 1 and 2.

[0631] In Tables 1 and 2, the value of |L2* - L1*| is also shown.

[0632] <Evaluation>

[0633] Using the obtained image recorded matter, evaluation of each of streaks, bleeding, and hiding of dots of the second ink was performed as follows.

[0634] The results are shown in Tables 1 and 2.

[0635] (Streaks)

[0636] The web of the obtained image recorded matter was unwound, and the amount of one head was visually observed, and in the multicolor image (solid image) of the image recorded matter, the number of streaks generated in the transport direction of the non-penetrable substrate was confirmed.

[0637] According to the confirmed results, evaluation of the streaks in the image was performed according to the following evaluation criteria.

[0638] -Evaluation Criteria for Streaks-

[0639] A: 0 or more and less than 4 streaks.

[0640] B: 4 or more and less than 8 streaks.

[0641] C: 8 or more streaks.

[0642] (bleeding)

[0643] The second ink was discharged in a character image, and otherwise, under the same conditions as the above image recording, a multicolor image having a structure in which a character image based on the second ink was recorded on a solid image based on the first ink was recorded. The character image based on the second ink was set to a character image shown in Fig. 1. The character image was recorded in sizes of 5pt, 6pt, 7pt, and 8pt. Figure 2

[0644] The character image in the obtained multicolor image was visually observed, and the bleeding of the image was evaluated in accordance with the following evaluation criteria.

[0645] - Evaluation Criteria for Bleeding -

[0646] AA: No deformation of the character image in all sizes of 5pt, 6pt, 7pt, and 8pt.

[0647] A: No deformation of the character image in sizes of 6pt, 7pt, and 8pt, but deformation was observed in the 5pt size.

[0648] B: No deformation of the character image in sizes of 7pt and 8pt, but deformation was observed in the 5pt and 6pt sizes.

[0649] C: No deformation of the character image in the 8pt size, but deformation was observed in the 5pt, 6pt, and 7pt sizes.

[0650] D: Deformation of the character image was observed in all sizes of 5pt, 6pt, 7pt, and 8pt.

[0651] (Point burial of the second color)

[0652] The second ink was discharged in a dot image, and otherwise, under the same conditions as the above image recording, a multicolor image having a structure in which a dot image based on the second ink was recorded on a solid image based on the first ink was recorded. The multicolor image was recorded as follows: in a 2 cm x 2 cm region in the solid image based on the first ink, the second ink was droplet ejected in a droplet amount of 2.1 pL to form 200 dots.

[0653] ​The proportion of the number of "buried dots" of the 200 dots based on the second ink buried in the solid image based on the first ink was confirmed, and the evaluation of the dot burying of the second color was performed according to the following evaluation criteria.

[0654] Evaluation criteria of dot burying of the second color

[0655] A: The proportion of buried dots is less than 1%.

[0656] B: The proportion of buried dots is 1% or more and less than 15%.

[0657] C: The proportion of buried dots is 15% or more and less than 30%.

[0658] D: The proportion of buried dots is 30% or more.

[0659]

[0660]

[0661] As shown in Table 1 and Table 2, in Example 1 to Example 18 in which the value (1) is 28.0 to 35.0 and the value (2) is -200 to 200, bleeding of the multi-color image and dot burying of the second ink were suppressed.

[0662] The results of the comparative examples with respect to the examples are as follows.

[0663] In Comparative Example 1 in which the value (2) exceeds 200, bleeding of the multi-color image occurred.

[0664] In Comparative Example 2 in which the value (1) is 28.0 or less, dot burying of the second ink occurred.

[0665] In Comparative Example 3 in which the value (1) exceeds 35.0, bleeding of the multi-color image occurred.

[0666] In Comparative Example 4 in which the value (2) is less than -200, dot burying of the second ink occurred.

[0667] From the results of Example 5, Example 13, and Example 15, it was found that in the case where the value (3) is -2000 to 2000 (Example 15), bleeding of the multi-color image was further suppressed.

[0668] From the comparison results of Example 3 and Example 4, it was found that in the case where Avl is greater than Av2 (Example 4), bleeding of the multi-color image was further suppressed.

[0669] From the comparison results of Example 4 and Example 5, it was found that in the case where the L* value of the first ink, Ll*, is lower than the L* value of the second ink, L2* (Example 4), bleeding of the multi-color image was further suppressed.

[0670] [Example 101 and Example 102]

[0671] [Example of 4 colors]

[0672] In the image recording device used in the image recording of Example 1, a 3rd inkjet head for 3rd ink and a 4th inkjet head for 4th ink were added on the downstream side of the 2nd inkjet head IJ2 and on the more upstream side than the 2nd drying region D2, and image recording was performed in which 4 colors of ink were sequentially superimposed and applied on the region to which a pre-treatment liquid was applied.

[0673] As the 1st ink of the 1st color, the 2nd ink of the 2nd color, the 3rd ink of the 3rd color, and the 4th ink of the 4th color, the inks shown in Table 3 were used.

[0674] As for the ink droplet amount at the time of ejection, all the inks were set to 0.5 pL, and a multi-color image of a dot gain of 25% was recorded with a total droplet amount of 2.0 pL of the 4 colors.

[0675] The multi-color image obtained was observed from the image recording surface side, and the graininess (whether or not periodic unevenness was present) was evaluated in accordance with the following evaluation criteria.

[0676] A: When observed from a position 30 cm from the image recording surface, periodic unevenness was not visually recognized.

[0677] B: When observed from a position 30 cm from the image recording surface, periodic unevenness was visually recognized, but when observed from a position 50 cm therefrom, periodic unevenness was not visually recognized.

[0678] C: When observed from a position 50 cm from the image recording surface, periodic unevenness was visually recognized.

[0679] [Table 3]

[0680]

[0681] As shown in Table 3, it was found that in the case where 4 colors of ink were used, from the viewpoint of the graininess of the multi-color image, it was more preferable to satisfy the relationship of Av1 > Av2 > Av3 > Av4 (inequality (4)) (i.e., Example 102).

[0682] [Example 201 and Example 202]

[0683] [Example of 4 colors + white]

[0684] A third inkjet head for third ink, a fourth inkjet head for fourth ink, and an inkjet head for white ink were added to the downstream side of the second inkjet head IJ2 in the image recording apparatus used in the image recording of Example 1 and to the upstream side of the second drying region D2, and image recording was performed in which the four colors of ink and the white ink were sequentially superimposed and applied onto the region to which the pre-treatment liquid was applied.

[0685] As the first ink of the first color, the second ink of the second color, the third ink of the third color, and the fourth ink of the fourth color, and the white ink applied last, the inks shown in Table 4 were used.

[0686] As to the ink drop amount at the time of ejection, the drop amount was set to 0.5 pL for each of the first ink to the fourth ink, and a multi-color image of a dot gain of 25% was recorded with a total drop amount of 2.0 pL for the four colors. A white solid image based on white ink was recorded in a manner so as to cover the upper portion of the multi-color image. The drop amount of the white ink was set to 2.7 pL.

[0687] The multi-color image covered by the white solid image was observed from the image recording surface side, and the white solid unevenness was evaluated in accordance with the following evaluation criteria.

[0688] A: The white solid unevenness was not visually recognized when observed from a position 30 cm from the image recording surface.

[0689] B: The white solid unevenness was visually recognized when observed from a position 30 cm from the image recording surface, but the white solid unevenness was not visually recognized when observed from a position 50 cm from the image recording surface.

[0690] C: The white solid unevenness was visually recognized when observed from a position 50 cm from the image recording surface.

[0691] [Table 4]

[0692]

[0693] As shown in Table 4, it was found that in the case where four colors of ink and white ink were used, it was more preferable that the acid value of the white ink be higher than any one of Av1, Av2, Av3, and Av4 (i.e., Example 202).

[0694] Explanation of Symbols

[0695] A1 - non-permeable substrate, R1 - unwinding device, P1 - pre-treatment liquid application device, IJ1 - first inkjet head, IJ2 - second inkjet head, DP1 - pre-treatment liquid drying region, D1 - first drying region, D2 - second drying region, R2 - winding device.

[0696] The invention of Japanese Patent Application No. 2023-047328 filed on March 23, 2023 is incorporated by reference in the present invention.

[0697] All of the literature, patent applications and technical standards cited in the present invention are incorporated by reference to the same extent as if each individual literature, patent application and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. An image recording method, comprising: A process of applying a pretreatment solution containing water, coagulant and resin to a non-permeable substrate; The process of applying a first ink containing water, a first pigment, and a resin to an area on the non-permeable substrate that has been treated with the pretreatment liquid using an inkjet recording method; and The process of applying a second ink containing water, a second pigment, and a resin to an area on the non-permeable substrate that has been treated with the pretreatment liquid and the first ink using an inkjet recording method. The following value (1) is 28.0 to 35.

0. The following value (2) is -200 to 200. Value(1) = (V1) 1 / 3 ×(1+cosθ)×14, Value (2) = |Av1 / S1 - Av2 / S2| × (Av2 - Av1) / T, In value (1), V1 represents the volume of the first ink droplet when it is applied to the first ink, in pL. θ represents the contact angle of the first ink, expressed in degrees, at a time T seconds after the first ink has landed on the non-permeable substrate in the area treated with the pretreatment liquid. In value (2), Av1 represents the acid value of the first ink, expressed in mgKOH / g. Av2 represents the acid value of the second ink, expressed in mgKOH / g. S1 indicates the solid content of the first ink, expressed as a percentage by mass. S2 indicates the solid content of the second ink, expressed as a percentage by mass. T represents the droplet ejection interval between the first and second inks, in seconds.

2. The image recording method according to claim 1, wherein, The following value (3) is -2000 to 2000. Value (3) = Value (2) × |L2*-L1*|, In value (3), L1* represents L * a * b * L, the first ink in the color system * Value, L2* represents L * a * b * L, the second ink in the color system * value.

3. The image recording method according to claim 1, wherein, Av1 is greater than Av2.

4. The image recording method according to claim 1, wherein, L * a * b * L of the first ink in the color system * The value is L1* lower than L. * a * b * L of the second ink in the color system * The value is L2*.

5. The image recording method according to claim 1, wherein, Also includes: The process of applying a third ink containing water, a third pigment, and a resin to an area on the non-permeable substrate that has been treated with the pretreatment liquid, the first ink, and the second ink using an inkjet recording method; and The process of applying a fourth ink containing water, a fourth pigment, and a resin to areas on the non-permeable substrate that have been treated with the pretreatment liquid, the first ink, the second ink, and the third ink using an inkjet recording method. When the acid value of the third ink in mgKOH / g is expressed as Av3 and the acid value of the fourth ink in mgKOH / g is expressed as Av4, the following inequality (4) is satisfied. Av1>Av2>Av3>Av4……Inequality (4).

6. The image recording method according to claim 5, wherein, Also includes: The process of applying a white ink containing water, white pigment, and resin to areas on the non-permeable substrate that have been treated with the pretreatment liquid, the first ink, the second ink, the third ink, and the fourth ink using an inkjet printing method. The white ink, expressed in mgKOH / g, has an acid value higher than any of Av1, Av2, Av3, and Av4.

7. An image recording apparatus for use in the image recording method according to any one of claims 1 to 6, the image recording apparatus comprising: A pretreatment liquid application device for applying the pretreatment liquid to one surface of the non-permeable substrate; The first inkjet head is used to apply the first ink; and a second inkjet head, used to apply the second ink, The value (1) is 28.0–35.

0. The value (2) is -200 to 200.

Images