Image recording methods, image recording materials and ink groups, and laminates and their manufacturing methods

Abstract

This invention provides an image recording method and its application capable of recording images with excellent concealment and excellent lamination strength with a laminating substrate. The image recording method includes: a step of preparing a white ink containing a white pigment, a first organic solvent with a boiling point of 120°C or higher, and water; a step of preparing a coloring ink containing a coloring pigment other than white pigment, a second organic solvent with a boiling point of 120°C or higher, and water; and a step of applying the white ink and the coloring ink separately to a non-permeable substrate to record an image. In the image recording step, in the area where the white ink and the coloring ink overlap when viewed from above, the total mass of the first and second organic solvents applied per unit area is 5.5 g / m². 2 The following applies to white pigment with a mass of 0.4 g / m² per unit area. 2 Record the image under the above conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to an image recording method, an image recorded matter, an ink set, and a laminate and a manufacturing method thereof. BACKGROUND

[0002] Conventionally, various studies have been made on image recording using a white ink and a colored ink other than white.

[0003] For example, Patent Literature 1 describes an ink set having: a non-white ink having non-white color material and thermoplastic resin particles with a volume average particle diameter of 30 to 110 nm; and a white ink having white color material and thermoplastic resin particles.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2018-94902 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] Sometimes, it is required that the light transmittance of an image recorded with a white ink be low (also referred to as "concealability"). For example, when an image is recorded on the surface of a colored substrate, it is considered that the case where the color of the substrate is visually recognized through the image is suppressed due to the high concealability of the image. Also, when an image is recorded on the surface of a transparent substrate, it is considered that the decrease in the visual recognition of the image due to the light transmission through the transparent substrate and the image is suppressed due to the high concealability of the image. Also, a technique is known in which an image recorded with a white ink is used as a base on which other colored ink images are recorded. By using an image with high concealability as a base, the case where the color of the substrate is seen as described above or the case where light is transmitted through the substrate and the image is suppressed, and thus it is considered that the visual recognition of the colored ink images is improved.

[0009] Also, sometimes, after an image is recorded on a non-permeable substrate to obtain an image recorded matter, a laminating substrate is laminated on the image in the image recorded matter, and in this case, it is sometimes required to improve the lamination strength between the image recorded matter and the laminating substrate.

[0010] The present application was made in view of such circumstances, and an embodiment of the present application aims to provide an image recording method and an ink set capable of recording an image with excellent concealability and excellent lamination strength with a laminating substrate.

[0011] Another embodiment of the present application aims to provide an image recorded matter having an image with excellent concealability and excellent lamination strength with a laminating substrate.

[0012] Another embodiment of the present application aims to provide a laminate having excellent laminate strength with a substrate for lamination, and a method for manufacturing the laminate.

[0013] Means for solving technical problems

[0014] The present application includes the following modes.

[0015] <1> An image recording method comprising: a step of preparing a white ink containing a white pigment, a first organic solvent having a boiling point of 120°C or higher, and water; a step of preparing a colored ink containing a colored pigment other than the white pigment, a second organic solvent having a boiling point of 120°C or higher, and water; and a step of recording an image by imparting the white ink and the colored ink on a non-penetrable substrate, respectively, wherein, in the step of recording an image, a total imparted mass per unit area of the first organic solvent and the second organic solvent becomes 5.5 g / m 2 or more and an imparted mass per unit area of the white pigment becomes 0.4 g / m 2 The image is recorded under the above conditions.

[0016] <2> The image recording method according to <1>, wherein a content of the first organic solvent is 30% by mass or less with respect to a total mass of the white ink, and a content of the second organic solvent is 30% by mass or less with respect to a total mass of the colored ink.

[0017] <3> The image recording method according to <1> or <2>, further comprising a step of preparing a pretreatment liquid containing a coagulant and water, wherein, in the step of recording an image, the white ink and the colored ink are imparted on the non-penetrable substrate after the pretreatment liquid is imparted.

[0018] <4> The image recording method according to <3>, wherein the pretreatment liquid does not contain a third organic solvent having a boiling point of 120°C or higher, or, in the case of containing the third organic solvent having a boiling point of 120°C or higher, a content of the third organic solvent having a boiling point of 120°C or higher is 15% by mass or less with respect to a total amount of the pretreatment liquid.

[0019] <5> The image recording method according to <4>, wherein, in the step of recording an image, a total imparted mass per unit area of the first organic solvent, the second organic solvent, and the third organic solvent becomes 5.5 g / m 2 or more in an area in which the area to which the pretreatment liquid is imparted, the area to which the white ink is imparted, and the area to which the colored ink is imparted overlap in plan view.

[0020] The image recording method according to any one of <4> or <5>, wherein in the step of recording the image, the amount of the third organic solvent applied per unit area in a region in which the region to which the pre-treatment liquid is applied, the region to which the white ink is applied, and the region to which the colored ink is applied overlap in plan view is 0.2 g / m 2 An image is recorded under the following conditions.

[0021] The image recording method according to any one of <1> to <6>, wherein the white ink further contains a pigment dispersant, and the pigment dispersant is a polymer having a crosslinked structure or a block polymer.

[0022] The image recording method according to any one of <1> to <7>, wherein, with respect to the white ink and the colored ink, the weighted average of the solubility parameters of the organic solvents contained in each of the inks is 28 MPa 1 / 2 The following.

[0023] The image recording method according to any one of <1> to <8>, wherein the first organic solvent contains a first organic solvent A having a boiling point of 120°C to 200°C, the proportion of the first organic solvent A in all the organic solvents contained in the white ink is 50% by mass or more, and the first organic solvent A contains at least one alkylene glycol and at least one alkylene glycol alkyl ether.

[0024] The image recording method according to <9>, wherein the first organic solvent A contains at least one alkylene glycol and at least two alkylene glycol alkyl ethers.

[0025] The image recording method according to <9> or <10>, wherein the mass ratio of the content of the alkylene glycol to the content of the alkylene glycol alkyl ether is 15.0 or less.

[0026] The image recording method according to any one of <1> to <11>, wherein the second organic solvent contains a second organic solvent A having a boiling point of 120°C to 200°C, the proportion of the second organic solvent A in all the organic solvents contained in the colored ink is 50% by mass or more, and the second organic solvent A contains at least one alkylene glycol and at least one alkylene glycol alkyl ether.

[0027] A method for manufacturing a laminate, comprising: a step of recording an image on a non-permeable substrate using the image recording method according to any one of <1> to <12>; and a step of laminating a laminate substrate to the side of the non-permeable substrate on which the image is recorded to obtain a laminate.

[0028] An image recorded article, comprising a non-permeable substrate and an image recorded on the non-permeable substrate, the image comprising a white ink layer in contact with the non-permeable substrate and containing a white pigment, and a colored ink layer in contact with the white ink layer and containing a coloring pigment other than the white pigment, and comprising a region in which the white ink layer and the colored ink layer overlap in plan view, the mass of the white pigment per unit area in the white ink layer being 0.4 g / m 2 or more.

[0029] An image recorded article, comprising a non-permeable substrate and an image recorded on the non-permeable substrate, the image comprising a white ink layer in contact with the non-permeable substrate and containing a white pigment, and a colored ink layer in contact with the white ink layer and containing a coloring pigment other than the white pigment, and comprising a region in which the white ink layer and the colored ink layer overlap in plan view, the mass of the white pigment per unit area in the white ink layer being 0.4 g / m 2 or more.

[0030] A laminate, comprising: the image recorded article according to <14> or <15>; and a laminating substrate laminated on the image of the image recorded article.

[0031] An ink set, comprising: a white ink containing a white pigment, a pigment dispersant, an organic solvent, and water; and a colored ink containing a coloring pigment other than the white pigment, the organic solvent, and water, the pigment dispersant being a polymer having a crosslinked structure or a block polymer, and the weighted average of the solubility parameters of the organic solvent contained in each of the white ink and the colored ink being 28 MPa 1 / 2 or more.

[0032] An ink set, comprising: a white ink containing a white pigment, a pigment dispersant, an organic solvent, and water; and a colored ink containing a coloring pigment other than the white pigment and water, the pigment dispersant being a polymer having a crosslinked structure or a block polymer, and the organic solvent containing at least one alkylene glycol having a boiling point of 120°C to 200°C and at least one alkylene glycol alkyl ether having a boiling point of 120°C to 200°C.

[0033] The ink set according to <18>, wherein the organic solvent contains at least one alkylene glycol having a boiling point of 120°C to 200°C and at least two alkylene glycol alkyl ethers having a boiling point of 120°C to 200°C.

[0034] Effects of the Invention

[0035] According to an embodiment of the present application, there is provided an image recording method and an ink set capable of recording an image having excellent concealability and excellent lamination strength with a lamination substrate.

[0036] According to another embodiment of the present application, there is provided an image recorded matter having an image with excellent concealability and excellent lamination strength with a lamination substrate.

[0037] According to another embodiment of the present application, there is provided a laminate having excellent lamination strength with a lamination substrate and a method for manufacturing the laminate. DETAILED DESCRIPTION

[0038] Hereinafter, the image recording method, the image recorded matter, the ink set, the laminate, and the method for manufacturing the laminate according to the present application will be described in detail.

[0039] In the present specification, a numerical range represented by "~" indicates a range including the numerical values recited before and after the "~" as the minimum value and the maximum value, respectively.

[0040] In the present specification, in a numerical range recited in stages, 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.

[0041] Also, 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 examples, in the numerical range recited in the present specification.

[0042] In the present specification, in the case where a plurality of substances corresponding to each component are present in a composition, unless otherwise specified, the amount of each component in the composition indicates the total amount of the plurality of substances present in the composition.

[0043] In the present specification, a combination of two or more preferred modes is a more preferred mode.

[0044] In the present specification, the term "step" includes not only a single step, but also a step that can be implemented even if it cannot be clearly distinguished from other steps, as long as the intended purpose of the step can be achieved.

[0045] In the present specification, "image" indicates the entire film formed by sequentially applying a pretreatment liquid and an ink, and "image recording" indicates the formation of the image (i.e., the film).

[0046] Also, the concept of "image" in the present specification also includes a solid image.

[0047] In the present specification, "(meth)acrylate" is a concept including both acrylate and methacrylate. Also, "(meth)acrylic acid" is a concept including both acrylic acid and methacrylic acid.

[0048] In the present specification, "alkylene glycol" is a concept including both monoalkylene glycol and polyalkylene glycol. Also, "alkylene glycol alkyl ether" is a concept including monoalkylene glycol monoalkyl ether, monoalkylene glycol polyalkyl ether, polyalkylene glycol monoalkyl ether, and polyalkylene glycol polyalkyl ether.

[0049] [Image recording method]

[0050] The image recording method of the present application includes a step of preparing a white ink containing a white pigment, a first organic solvent having a boiling point of 120°C or higher, and water; a step of preparing a colored ink containing a colored pigment other than the white pigment, a second organic solvent having a boiling point of 120°C or higher, and water; and a step of recording an image by imparting the white ink and the colored ink to a non-penetrable substrate, respectively, in the step of recording an image, the total imparted mass of the first organic solvent and the second organic solvent per unit area becomes 5.5 g / m 2 the imparted mass of the white pigment per unit area becomes 0.4 g / m 2 An image is recorded under the above conditions.

[0051] According to the image recording method of the present application, an image recorded matter having a non-penetrable substrate and an image recorded on the non-penetrable substrate, and excellent in the lamination strength when a lamination substrate is laminated on the above image, can be obtained.

[0052] Here, the lamination strength indicates the peeling strength when the lamination substrate and the image recorded matter in the lamination body formed by the above lamination, that is, the lamination body having a stacked structure of "lamination substrate / image recorded matter" (in detail, a stacked structure of "lamination substrate / image / non-penetrable substrate") are peeled.

[0053] Also, according to the image recording method of the present application, an image recorded matter excellent in the concealability can be obtained.

[0054] The reason why the above effects are exerted by the image recording method of the present application is presumed as follows.

[0055] In order to improve the lamination strength of the lamination body, it is first necessary to improve the adhesion between the non-penetrable substrate and the image, and further necessary to improve the adhesion between the image and the lamination substrate.

[0056] In the image recording method of the present invention, white ink and colored ink are applied to a non-permeable substrate, respectively. The white ink and colored ink are applied under conditions where the areas where the white ink is applied and the areas where the colored ink is applied overlap in a top view. The inventors have focused on a first organic solvent contained in the white ink with a boiling point of 120°C or higher, and a second organic solvent contained in the colored ink with a boiling point of 120°C or higher. In the image recording method of the present invention, in the aforementioned overlapping area, the total applied mass of the first organic solvent and the second organic solvent per unit area is 5.5 g / m². 2 White ink and colored ink were applied under the following conditions. It is assumed that the total applied mass is 5.5 g / m³. 2 The following can suppress the decrease in image strength (e.g., abrasion resistance, adhesion resistance, etc.), thereby ensuring image strength. As a result, it is believed that the decrease in adhesion between the image and the laminating substrate caused by the decrease in image strength can be suppressed.

[0057] Furthermore, in the image recording method of the present invention, in the aforementioned overlapping region, the amount of white pigment applied per unit area is 0.4 g / m². 2 White ink is applied under the above conditions. It is speculated that the white pigment retains the surrounding organic solvent on a non-permeable substrate. Therefore, it is believed that by applying the above-mentioned material at a mass of 0.4 g / m... 2 The above ensures image strength, resulting in excellent adhesion between the image and the laminating substrate. Furthermore, by achieving a mass of 0.4 g / m³... 2 In this way, light transmission is suppressed, thereby enabling the acquisition of image records with excellent concealment.

[0058] The following describes each step included in the image recording method of the present invention.

[0059] <White Ink Preparation Process>

[0060] The image recording method of the present invention includes a step of preparing a white ink containing a white pigment, a first organic solvent with a boiling point of 120°C or higher, and water (hereinafter referred to as the "white ink preparation step").

[0061] (White pigment)

[0062] The white ink prepared in the white ink preparation process contains white pigment.

[0063] White pigments are any pigments that are white in color, and there is no particular limitation on the type. White indicates a color that does not absorb a specific wavelength or absorbs a small amount of a specific wavelength. Examples of white pigments include inorganic pigments such as titanium dioxide, strontium titanate, barium titanate, zinc oxide, magnesium oxide, zirconium oxide, aluminum oxide, barium sulfate, silicon dioxide, talc, mica, aluminum hydroxide, calcium silicate, aluminum silicate, and zinc sulfide. White pigments are preferably particles containing titanium atoms, and more preferably titanium dioxide.

[0064] The average particle size of the white pigment is preferably 10 nm to 550 nm, more preferably 100 nm to 450 nm, and even more preferably 150 nm to 400 nm. If the average particle size is 550 nm or less, color reproduction is good, and consequently, the jetting stability is good when recording images using an inkjet recording method. On the other hand, if the average particle size is 10 nm or more, lightfastness is good. Furthermore, the pigment particle size distribution can be either a broad particle size distribution or a monodisperse particle size distribution. The average particle size and particle size distribution of the pigment are determined as follows: the volume average particle size is measured using a particle size distribution measuring device (e.g., Nikkiso Co., Ltd., product name "NANOTRACUPA-EX150") by dynamic light scattering. Furthermore, when the pigment is coated with a pigment dispersant, the average particle size of the pigment represents the average particle size of the pigment coated with the pigment dispersant.

[0065] The mass of white pigment was set to 0.4 g / m. 2 Based on the above viewpoints, the content of white pigment relative to the total amount of white ink is preferably 5% to 20% by mass, more preferably 8% to 15% by mass.

[0066] (The first organic solvent with a boiling point above 120°C)

[0067] The white ink prepared in the white ink preparation process contains a first organic solvent with a boiling point of 120°C or higher. Hereinafter, the organic solvent with a boiling point of 120°C or higher contained in the white ink will also be referred to as the "first organic solvent".

[0068] In this invention, "boiling point" refers to the boiling point at 1 atmosphere (101325 Pa). The boiling point is determined by a boiling point meter, for example using a boiling point measuring instrument (product name "DosaTherm300", manufactured by TITAN TECHNO LOGIES, KK).

[0069] Examples of organic solvents with boiling points above 120°C include 1,3-butanediol (207°C), 1,4-butanediol (228°C), benzyl alcohol (205°C), and terpineol (217°C).

[0070] Ethylene glycol (197℃), diethylene glycol (244℃), triethylene glycol (287℃), propylene glycol (187℃), dipropylene glycol (230℃), and other alkylene glycols;

[0071] Diethylene glycol monomethyl ether (194℃), diethylene glycol monoethyl ether (202℃), diethylene glycol monobutyl ether (231℃), diethylene glycol dimethyl ether (162℃), diethylene glycol ethyl methyl ether (176℃), diethylene glycol isopropyl methyl ether (179℃), triethylene glycol monomethyl ether (249℃), triethylene glycol dimethyl ether (216℃), propylene glycol monomethyl ether (121℃), propylene glycol monobutyl ether (170℃), propylene glycol monopropyl ether (150℃), 3-methoxy Alkyl-3-methyl-1-butanol (174℃), diethylene glycol monohexyl ether (above 261℃), propylene glycol monomethyl ether propionate (160℃), methyl cellosolve (ethylene glycol monomethyl ether, 125℃), ethyl cellosolve (ethylene glycol monoethyl ether, 135℃), butyl cellosolve (ethylene glycol monobutyl ether, 171℃), ethylene glycol monotert-butyl ether (153℃), tripropylene glycol monomethyl ether (243℃), dipropylene glycol monomethyl ether (188℃), and other alkylene glycol alkyl ethers;

[0072] Esters such as ethylene glycol monomethyl ether acetate (145℃), diethylene glycol monoethyl ether acetate (217℃), ethyl acetate (154℃), ethyl lactate (154℃), and 3-methoxybutyl acetate (172℃); and ketones such as diacetone alcohol (169℃), cyclohexanone (156℃), and cyclopentanone (131℃). Additionally, the values ​​in parentheses indicate boiling points.

[0073] If the white ink contains the first organic solvent, its jetting properties and re-jetting properties after printing has stopped (hereinafter also referred to as "re-jetting properties") are excellent. The white ink may also contain an organic solvent with a boiling point below 120°C. From the viewpoint of jetting properties and re-jetting properties, the proportion of the first organic solvent in the organic solvent contained in the white ink is preferably 50% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. The above proportion may also be 100% by mass. That is, all the organic solvent contained in the white ink may be the first organic solvent.

[0074] In the white ink, the content of the first organic solvent relative to the total amount of white ink is preferably 30% by mass or less, more preferably 28% by mass or less, and even more preferably 26% by mass or less. If the content of the first organic solvent is 30% by mass or less, image strength can be ensured even in overlapping areas, thereby improving the adhesion between the image and the laminating substrate. As a result, lamination strength is improved.

[0075] The lower limit of the content of the first organic solvent is not particularly limited as long as it exceeds 0% by mass. However, from the viewpoint of sprayability and concealment, the content of the first organic solvent relative to the total amount of white ink is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more.

[0076] From the viewpoint of further improving the lamination strength of image recordings, white inks are particularly preferably containing an organic solvent with a boiling point of 120°C to 200°C (hereinafter also referred to as "first organic solvent A"). The proportion of first organic solvent A in the organic solvent contained in the white ink is preferably 50% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The above proportion may also be 100% by mass. That is, all the organic solvent contained in the white ink may be first organic solvent A.

[0077] The first organic solvent A preferably contains at least one selected from the group consisting of alkylene glycols and alkylene glycol alkyl ethers. More preferably, the first organic solvent A contains at least one alkylene glycol and at least one alkylene glycol alkyl ether. Even more preferably, the first organic solvent A contains at least one alkylene glycol and at least two alkylene glycol alkyl ethers.

[0078] The alkylene glycols and alkylene glycol alkyl ethers contained in the first organic solvent A are preferably selected from the group consisting of propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol, dipropylene glycol monomethyl ether, diethylene glycol monoethyl ether, and ethylene glycol.

[0079] If the white ink contains an organic solvent, and that organic solvent contains at least one alkylene glycol with a boiling point of 120°C to 200°C and at least one alkylene glycol alkyl ether with a boiling point of 120°C to 200°C, then the drying properties of the white ink on the substrate are improved. This, in turn, improves lamination strength and adhesion.

[0080] Furthermore, if the white ink contains an organic solvent, and that organic solvent contains at least one alkylene glycol with a boiling point of 120°C to 200°C and at least two alkylene glycol alkyl ethers with boiling points of 120°C to 200°C, the drying properties of the white ink on the substrate are further improved. Consequently, the lamination strength and adhesion are further improved.

[0081] When white inks contain alkylene glycols and alkylene glycol alkyl ethers, from the viewpoint of further improving lamination strength and adhesion, the mass ratio of the alkylene glycol content to the alkylene glycol alkyl ether content (“alkylene glycol content” / “alkylene glycol alkyl ether content”) is preferably 20.0 or less, more preferably 18.0 or less, further preferably 15.0 or less, even more preferably 10.0 or less, and particularly preferably 6.0 or less. The lower limit of the above mass ratio is not particularly limited, but from the viewpoint of re-spraying properties, it is preferably 1.0, more preferably 2.0, even more preferably 3.0, and even more preferably 4.0.

[0082] In addition to the first organic solvent A, the white ink may also contain an organic solvent with a boiling point exceeding 200°C and below 240°C (hereinafter referred to as "first organic solvent B"), and may also contain an organic solvent with a boiling point exceeding 240°C (hereinafter referred to as "first organic solvent C"). Furthermore, in addition to the first organic solvent A, the white ink may also contain both the first organic solvent B and the first organic solvent C.

[0083] From the viewpoint of further improving the lamination strength and adhesion of image recordings, the total proportion of the first organic solvent A and the first organic solvent B in the white ink is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 100% by mass. That is, the organic solvent contained in the white ink is preferably entirely composed of the first organic solvent A and the first organic solvent B, or the first organic solvent A. More preferably, the organic solvent contained in the white ink is entirely composed of the first organic solvent A.

[0084] Examples of first organic solvent B include diethylene glycol monobutyl ether, dipropylene glycol, 1,2-hexanediol, and ethylene glycol monohexyl ether.

[0085] From the viewpoint of further improving the lamination strength and adhesion of image recordings, the proportion of the first organic solvent C in the organic solvent contained in the white ink is preferably 10% by mass or less. The above proportion can also be 0% by mass. That is, the white ink can be free of the first organic solvent C.

[0086] Examples of first organic solvents C include diethylene glycol and triethylene glycol.

[0087] The weighted average of the solubility parameters (SP values) of the organic solvents contained in the white ink is preferably 28 MPa. 1 / 2 The weighted average of the SP values ​​is calculated using the following formula. Where S... i W represents the SP value of the i-th organic solvent contained in the white ink. iThis indicates the content (mass%) of the i-th organic solvent relative to the total amount of white ink.

[0088] The weighted average of solubility parameters = ΣS i W i / ΣW i

[0089] If the weighted average SP value of the organic solvents contained in white ink is 28 MPa 1 / 2 The following assumes that the organic solvent as a whole becomes more volatile. As a result, the lamination strength of the image recording increases. From the viewpoint of lamination strength, the aforementioned weighted average is more preferably 27 MPa. 1 / 2 From the viewpoint of jetting and re-jetting properties, the lower limit of the above weighted average value is preferably 25.5 MPa. 1 / 2 .

[0090] In this invention, the SP value is expressed as the square root of the intermolecular cohesive energy, and is calculated using the method described in RFFedors, Polymer Engineering Science, 14, pp. 147-154 (1974). The unit of the SP value is MPa. 1 / 2 .

[0091] The following examples illustrate the SP values ​​for organic solvents. The values ​​in parentheses represent the SP values.

[0092] Propylene glycol (27.6 MPa) 1 / 2 ), ethylene glycol (30.3 MPa) 1 / 2 ), diethylene glycol (30.6 MPa) 1 / 2 ), triethylene glycol (27.8 MPa) 1 / 2 ), tripropylene glycol (24.7 MPa) 1 / 2 ), 2-methyl-1,3-butanediol (28.27 MPa) 1 / 2 ), 1,2-pentanediol (28.64 MPa) 1 / 2 ), 1,5-pentanediol (28.96 MPa) 1 / 2 ), 1,2-hexanediol (21.3 MPa) 1 / 2 ), 1,6-hexanediol (27.66 MPa) 1 / 2 ), glycerol (33.5 MPa) 1 / 2 ), dimethylformamide (30.62 MPa) 1 / 2 Methanol (28.17 MPa) 1 / 2 Isopropanol (28.69 MPa) 1 / 2 ), triethanolamine (32.27 MPa) 1 / 2 dipropylene glycol (27.1 MPa) 1 / 2), ethylene glycol monoethyl ether (23.5 MPa) 1 / 2 ), ethylene glycol monopropyl ether (21.8 MPa) 1 / 2 ), ethylene glycol monobutyl ether (22.1 MPa) 1 / 2 ), diethylene glycol monomethyl ether (22.98 MPa) 1 / 2 ), diethylene glycol monoethyl ether (22.4 MPa) 1 / 2 ), diethylene glycol monopropyl ether (21.9 MPa) 1 / 2 ), diethylene glycol monobutyl ether (21.5 MPa) 1 / 2 ), triethylene glycol monomethyl ether (22.1 MPa) 1 / 2 ), triethylene glycol monoethyl ether (21.7 MPa) 1 / 2 ), triethylene glycol monobutyl ether (21.1 MPa) 1 / 2 ), Propylene glycol monomethyl ether (23.0 MPa) 1 / 2 ), propylene glycol monoethyl ether (22.3 MPa) 1 / 2 ), propylene glycol monopropyl ether (21.8 MPa) 1 / 2 ), Propylene glycol monobutyl ether (21.4 MPa) 1 / 2 ), dipropylene glycol monomethyl ether (21.3 MPa) 1 / 2 ), dipropylene glycol monopropyl ether (20.69 MPa) 1 / 2 ), dipropylene glycol monobutyl ether (20.45 MPa) 1 / 2 ), dipropylene glycol tert-butyl ether (19.98 MPa) 1 / 2 ), tripropylene glycol monomethyl ether (20.4 MPa) 1 / 2 ), diethylene glycol monohexyl ether (20.91 MPa) 1 / 2 ), Ethylene glycol mono-2-ethylhexyl ether (20.46 MPa) 1 / 2 ), diethylene glycol mono-2-ethylhexyl ether (20.26 MPa) 1 / 2 )

[0093] (water)

[0094] The white ink prepared in the white ink preparation process contains water. The water content is not particularly limited, for example, it can be 40% to 70% by mass.

[0095] (Pigment dispersant)

[0096] The white ink prepared in the white ink preparation process preferably contains a pigment dispersant to disperse the white pigment in water. In this invention, the pigment dispersant has the function of dispersing pigment. By adsorbing onto the surface of the pigment and coating at least a portion of the pigment surface, the pigment can be dispersed in water. Alternatively, when a self-dispersible pigment that can be dispersed in water even without a pigment dispersant is used as the white pigment, the white ink may not contain a pigment dispersant.

[0097] The form of the pigment dispersant contained in white ink is not particularly limited and can be any of random polymers, block polymers, and graft polymers. Furthermore, the pigment dispersant contained in white ink can also be a polymer with a cross-linked structure. Preferably, the pigment dispersant contained in white ink is a polymer with a cross-linked structure or a block polymer. If the pigment dispersant is a polymer with a cross-linked structure or a block polymer, it is considered that the pigment dispersant is less likely to detach from the surface of the white pigment, thus resulting in high dispersion stability of the white pigment. As a result, when the white ink reacts with the pretreatment liquid, the white pigment uniformly aggregates, thus the image becomes more uniform, the organic solvent evaporates more easily, and the lamination strength is further improved. Furthermore, even without the use of a pretreatment liquid, the solvent ratio in the white ink increases during water evaporation after the white ink drips onto a non-permeable substrate, making the dispersion of the white pigment more unstable. In this case, if the pigment dispersant is a polymer with a cross-linked structure or a block polymer, the uneven aggregation of the white pigment is suppressed, the image becomes more uniform, the organic solvent evaporates more easily, and the lamination strength is further improved.

[0098] In this invention, polymer refers to a compound with a weight-average molecular weight of 1000 or more.

[0099] In this invention, the weight-average molecular weight is expressed as the value measured by gel permeation chromatography (GPC). When performing the determination by GPC, an HLC (registered trademark)-8020GPC (manufactured by Tosoh Corporation) was used as the measuring apparatus, three TSKgel (registered trademark) Super Multipore HZ-H (4.6mm ID × 15cm, manufactured by Tosoh Corporation) eluents were used, and THF (tetrahydrofuran) was used. The determination was performed using an RI detector, with the sample concentration set to 0.45% by mass, the flow rate set to 0.35 ml / min, the sample injection volume set to 10 μl, and the measurement temperature set to 40°C. Calibration curves were prepared based on eight samples from Tosoh Corporation's "Standard Samples TSKstandard, polystyrene": "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000", and "n-propylbenzene".

[0100] -Polymers with cross-linked structures-

[0101] There are no particular limitations on polymers with cross-linked structures, as long as they have at least one cross-linked structure within the molecule.

[0102] Whether the polymer contained in the ink has a cross-linked structure can be determined, for example, by the following methods. First, the polymer in the ink is separated using separation methods such as solvent extraction. Then, by analyzing the separated polymer using various analytical methods such as nuclear magnetic resonance (NMR), infrared spectroscopy (IR), and thermal analysis, the presence or absence of a cross-linked structure can be comprehensively determined.

[0103] A cross-linked polymer (hereinafter also referred to as a "cross-linked polymer") is formed, for example, by cross-linking an uncross-linked polymer (hereinafter also referred to as a "non-cross-linked polymer") using a cross-linking agent. The non-cross-linked polymer is preferably a water-soluble polymer.

[0104] In this invention, "water solubility" refers to the property of dissolving 1g or more in 100g of water at 25°C. Preferably, "water solubility" refers to the property of dissolving 3g or more (more preferably 10g or more) in 100g of water at 25°C.

[0105] Furthermore, even if an uncrosslinked polymer is water-soluble, a crosslinked polymer is not necessarily water-soluble.

[0106] Examples of uncrosslinked polymers include vinyl resins, acrylic resins, urethane resins, and polyester resins. Among these, acrylic resins are preferred as the uncrosslinked polymer.

[0107] The uncrosslinked polymer is preferably a polymer having functional groups that can be crosslinked using a crosslinking agent. Examples of crosslinkable functional groups include carboxyl groups or their salts, isocyanate groups, and epoxy groups. From the viewpoint of improving pigment dispersibility, the crosslinkable functional group is preferably a carboxyl group or its salt, and particularly preferably a carboxyl group. That is, the uncrosslinked polymer is preferably a polymer containing a carboxyl group.

[0108] The uncrosslinked polymer is preferably a copolymer containing structural units derived from carboxyl-containing monomers (hereinafter referred to as "carboxyl-containing monomers"). The copolymer may contain only one type of structural unit derived from carboxyl-containing monomers, or it may contain two or more types. The copolymer may be a random copolymer or a block copolymer, but a random copolymer is preferred.

[0109] Examples of carboxyl-containing monomers include (meth)acrylic acid, β-carboxyethyl acrylate, fumaric acid, itaconic acid, maleic acid, and crotonic acid.

[0110] From the viewpoint of crosslinking and dispersibility, the carboxyl-containing monomer is preferably (meth)acrylic acid or β-carboxyethyl acrylate, and more preferably (meth)acrylic acid.

[0111] The content of structural units derived from carboxyl-containing monomers relative to the total amount of uncrosslinked polymer is preferably 5% to 40% by mass, more preferably 10% to 35% by mass, and even more preferably 10% to 30% by mass.

[0112] The uncrosslinked polymer preferably contains structural units derived from hydrophobic monomers in addition to structural units derived from carboxyl-containing monomers. The copolymer may contain only one type of structural unit derived from hydrophobic monomers or more than two types.

[0113] Examples of hydrophobic monomers include (meth)acrylates having alkyl groups having 1 to 20 carbon atoms, (meth)acrylates having aromatic rings (e.g., benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, etc.), styrene, and styrene derivatives.

[0114] The content of structural units derived from hydrophobic monomers relative to the total amount of uncrosslinked polymer is preferably 60% to 95% by mass, more preferably 65% ​​to 90% by mass, and even more preferably 70% to 90% by mass.

[0115] The uncrosslinked polymer is preferably a random copolymer containing at least one of structural units derived from (meth)acrylates having 1 to 20 carbon atoms and structural units derived from (meth)acrylates having an aromatic ring, and structural units derived from carboxyl monomers. More preferably, it is a random copolymer containing structural units derived from (meth)acrylates and structural units derived from (meth)acrylates having an aromatic ring. Even more preferably, it is a copolymer containing structural units derived from (meth)acrylates and structural units derived from benzyl methacrylate.

[0116] There is no particular limitation on the weight-average molecular weight (Mw) of the uncrosslinked polymer, but from the viewpoint of the dispersibility of the white pigment, it is preferably 3,000 to 300,000, more preferably 5,000 to 200,000, and even more preferably 7,000 to 100,000.

[0117] The preferred range of weight-average molecular weight for cross-linked polymers is the same as that for uncross-linked polymers.

[0118] In this invention, the weight-average molecular weight (Mw) was determined by gel permeation chromatography (GPC). An HLC-8220 GPC (manufactured by Tosoh Corporation) was used as the column, with three TSK gelL SuperHZM-H, TSK gelL SuperHZ4000, and TSK gel SuperHZ2000 (all trade names manufactured by Tosoh Corporation) connected in series as the eluent. THF (tetrahydrofuran) was used as the eluent. The conditions were set as follows: sample concentration 0.45% by mass, flow rate 0.35 ml / min, sample injection volume 10 μl, measurement temperature 40°C, and a differential refractive index detector. Calibration curves were prepared based on eight samples from Tosoh Corporation's "Standard Samples TSK standard, polystyrene": "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000", and "n-propylbenzene".

[0119] The crosslinking agent used to crosslink an uncrosslinked polymer is preferably a compound having two or more reaction sites with the uncrosslinked polymer (e.g., a polymer with carboxyl groups). Only one crosslinking agent may be used, or two or more may be used.

[0120] A preferred combination of crosslinking agent and uncrosslinked polymer is a combination of a compound having two or more epoxy groups (i.e., an epoxy compound with two or more functions) and a polymer having carboxyl groups. In this combination, the crosslinked structure is formed by the reaction of epoxy groups and carboxyl groups. The formation of the crosslinked structure using the crosslinking agent is preferably carried out after dispersing the pigment using the uncrosslinked polymer.

[0121] Examples of epoxy compounds with two or more functions include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, diethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and trimethylolpropane triglycidyl ether.

[0122] Among them, the epoxy compound with two or more functions is preferably polyethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, or trimethylolpropane triglycidyl ether.

[0123] Crosslinking agents can be commercially available products.

[0124] Commercially available products include, for example, Denacol EX-321, EX-821, EX-830, EX-850 and EX-851 (manufactured by Nagase ChemteX Corporation).

[0125] From the viewpoint of crosslinking reaction rate and dispersion stability after crosslinking, the molar ratio of the reactive site (e.g., epoxy group) in the crosslinking agent to the reactive site (e.g., carboxyl group) in the uncrosslinked polymer is preferably 1:1.1 to 1:10, more preferably 1:1.1 to 1:5, and even more preferably 1:1.1 to 1:3.

[0126] -Block polymer-

[0127] Block polymers, also known as block copolymers, are copolymers in which at least two polymers are bonded together in the molecule.

[0128] The block polymer preferably contains: structural units derived from hydrophobic monomers; and structural units derived from monomers containing anionic groups (hereinafter referred to as "monomers containing anionic groups").

[0129] Block polymers may contain only one or more structural units derived from hydrophobic monomers. Block polymers may also contain only one or more structural units derived from monomers containing anionic groups.

[0130] Examples of structural units derived from hydrophobic monomers include olefinic unsaturated compounds with aromatic or alicyclic structures and (meth)acrylates with alkyl groups having 1 to 20 carbon atoms.

[0131] The content of structural units derived from hydrophobic monomers relative to the total amount of block polymer is preferably 35% to 95% by mass, more preferably 50% to 95% by mass, and even more preferably 70% to 90% by mass.

[0132] From the viewpoint of pigment adsorption, the hydrophobic monomer preferably contains an olefinic unsaturated compound having an aromatic ring structure or an alicyclic structure, more preferably contains an olefinic unsaturated compound having an alicyclic structure, and even more preferably contains an olefinic unsaturated compound having an alicyclic structure with 6 or more carbon atoms.

[0133] The content of structural units derived from olefinic unsaturated compounds having aromatic or alicyclic structures is preferably 10% to 90% by mass relative to the total amount of the block polymer, more preferably 20% to 80% by mass, even more preferably 30% to 70% by mass, and even more preferably 30% to 60% by mass.

[0134] The structural unit derived from the hydrophobic monomer preferably contains an alkyl group having 1 to 20 carbon atoms and is a (meth)acrylate. The alkyl group can be either linear or branched.

[0135] Examples of (meth)acrylates having alkyl groups having 1 to 20 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and octyl (meth)acrylate.

[0136] The content of structural units derived from (meth)acrylates having alkyl groups having 1 to 20 carbon atoms is preferably 10% to 90% by mass relative to the total amount of the block polymer, more preferably 20% to 80% by mass, further preferably 30% to 70% by mass, and especially preferably 40% to 60% by mass.

[0137] In structural units derived from monomers containing anionic groups, anionic groups include, for example, carboxyl groups, salts of carboxyl groups, sulfonyl groups, salts of sulfonyl groups, phosphate groups, salts of phosphate groups, phosphonic acid groups, and salts of phosphonic acid groups.

[0138] As counterions in salts, examples include alkali metal ions such as sodium ions, potassium ions, and lithium ions; alkaline earth metal ions such as calcium ions and magnesium ions; and ammonium ions.

[0139] The anionic group is preferably a carboxyl group or a salt of a carboxyl group. Examples of monomers containing anionic groups include (meth)acrylic acid, β-carboxyethyl acrylate, fumaric acid, itaconic acid, maleic acid, and crotonic acid. Among these, (meth)acrylic acid is preferred.

[0140] The content of structural units derived from monomers containing anionic groups is preferably 1% to 30% by mass relative to the total amount of the block polymer, more preferably 2% to 25% by mass, and even more preferably 3% to 20% by mass.

[0141] Whether the polymer contained in the ink is a block polymer can be determined, for example, by the following methods. First, the polymer in the ink is separated using separation methods such as solvent extraction. Then, the separated polymer is analyzed using various analytical methods such as nuclear magnetic resonance (NMR), infrared spectroscopy (IR), and thermal analysis, and its physical properties, such as glass transition temperature, are measured to comprehensively determine whether it is a block polymer.

[0142] For example, the case where the block polymer contained in the ink has more than two glass transition temperatures can also be listed as a preferred form in the above-mentioned determination method.

[0143] There is no particular limitation on the weight-average molecular weight (Mw) of the block polymer, but from the viewpoint of pigment dispersibility, it is preferably 3,000 to 100,000, more preferably 5,000 to 80,000, and even more preferably 10,000 to 60,000.

[0144] The mixing ratio of white pigment to pigment dispersant, by mass, is preferably 1:0.02 to 1:2, more preferably 1:0.03 to 1:1.5, and even more preferably 1:0.04 to 1:1.

[0145] As a dispersing device for dispersing pigments, known dispersing devices can be used, such as ball mills, sand mills, bead mills, roller mills, spray mills, paint mixers, grinders, ultrasonic dispersers, and dispersers.

[0146] (Resin particles)

[0147] From the viewpoint of improving the lamination strength of image recordings, the white ink prepared in the white ink preparation process preferably contains at least one type of resin particles. The white ink preferably contains resin particles in addition to a pigment dispersant, and these resin particles are particles composed of resin.

[0148] When white ink is applied to a non-permeable substrate pretreated with a pretreatment solution, the coagulant in the pretreatment solution comes into contact with the resin particles in the white ink, causing the dispersion of the resin particles to become unstable, thereby increasing the viscosity of the white ink. As a result, the white ink fixes onto the non-permeable substrate, increasing the lamination strength of the image recorder.

[0149] The resin constituting the resin particles is preferably a water-insoluble polymer. "Water-insoluble" in water-insoluble polymer means that its solubility in 100g of distilled water at 25°C is less than 2g.

[0150] The resin particles preferably include at least one of particles made of acrylic resin (hereinafter referred to as "acrylic resin particles") and particles made of urethane resin (hereinafter also referred to as "urethane resin particles"), and preferably include acrylic resin particles.

[0151] The resin particles are preferably self-dispersible resin particles.

[0152] Examples of self-dispersible resin particles include those described in Japanese Patent Application Publication No. 2016-188345, paragraphs 0062 to 0076, and International Publication No. 2013 / 180074, paragraphs 0109 to 0140.

[0153] The resin in the resin particles is preferably an acrylic resin containing structural units derived from (meth)acrylates having an aromatic ring structure or an alicyclic structure, structural units derived from (meth)acrylic acid, and structural units derived from (meth)acrylates containing alkyl groups having 1 to 4 carbon atoms.

[0154] The (meth)acrylate having an alicyclic structure is preferably a cycloalkyl (meth)acrylate having 3 to 10 carbon atoms, preferably at least one selected from the group consisting of cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate and dicyclopentyl (meth)acrylate, more preferably at least one selected from the group consisting of isobornyl (meth)acrylate, adamantyl (meth)acrylate and dicyclopentyl (meth)acrylate.

[0155] The (meth)acrylate having an aromatic ring structure is preferably phenoxyethyl (meth)acrylate or benzyl (meth)acrylate.

[0156] Examples of resins used in resin particles include phenoxyethyl acrylate / methyl methacrylate / acrylic acid copolymer (50 / 45 / 5), phenoxyethyl acrylate / benzyl methacrylate / isobutyl methacrylate / acrylic acid copolymer (30 / 35 / 29 / 6), phenoxyethyl methacrylate / isobutyl methacrylate / acrylic acid copolymer (50 / 44 / 6), phenoxyethyl acrylate / methyl methacrylate / ethyl acrylate / acrylic acid copolymer (30 / 55 / 10 / 5), and benzyl methacrylate / isobutyl methacrylate / acrylic acid copolymer (…). 35 / 59 / 6), styrene / phenoxyethyl acrylate / methyl methacrylate / acrylic acid copolymer (10 / 50 / 35 / 5), benzyl acrylate / methyl methacrylate / acrylic acid copolymer (55 / 40 / 5), phenoxyethyl methacrylate / benzyl acrylate / methacrylic acid copolymer (45 / 47 / 8), styrene / phenoxyethyl acrylate / butyl methacrylate / acrylic acid copolymer (5 / 48 / 40 / 7), benzyl methacrylate / isobutyl methacrylate / cyclohexyl methacrylate / methacrylic acid copolymer (35 / 30 / 30 / 5), acrylic acid Phenoxyethyl acrylate / methyl methacrylate / butyl acrylate / methacrylic acid copolymer (12 / 50 / 30 / 8), benzyl acrylate / isobutyl methacrylate / acrylic acid copolymer (93 / 2 / 5), methyl methacrylate / methoxyethyl acrylate / benzyl methacrylate / acrylic acid copolymer (44 / 15 / 35 / 6), styrene / butyl acrylate / acrylic acid copolymer (62 / 35 / 3), methyl methacrylate / phenoxyethyl acrylate / acrylic acid copolymer (45 / 51 / 4), methyl methacrylate / isoborneol methacrylate / methacrylic acid copolymer (2) 0 / 72 / 8), methyl methacrylate / isoborneol methacrylate / methacrylic acid copolymer (40 / 52 / 8), methyl methacrylate / isoborneol methacrylate / methacrylic acid copolymer (48 / 42 / 10), methyl methacrylate / isoborneol methacrylate / dicyclopentyl methacrylate / methacrylic acid copolymer (20 / 62 / 10 / 8), methyl methacrylate / dicyclopentyl methacrylate / methacrylic acid copolymer (20 / 72 / 8), and methyl methacrylate / isoborneol methacrylate / methacrylic acid copolymer (70 / 20 / 10). Additionally, the numbers in parentheses indicate the mass ratio of structural units derived from monomers. Furthermore, some or all of the (meth)acrylic acid constituting the resin may be a salt.

[0157] The acid value of the resin in the resin particles is preferably 25 mg KOH / g to 100 mg KOH / g, more preferably 30 mg KOH / g to 90 mg KOH / g, and even more preferably 35 mg KOH / g to 80 mg KOH / g.

[0158] The weight-average molecular weight of the resin in the resin particles is preferably 1,000 to 300,000, more preferably 2,000 to 200,000, and even more preferably 5,000 to 100,000.

[0159] From the viewpoint of spray stability, the average particle size of the resin particles is preferably 1 nm to 200 nm, more preferably 3 nm to 200 nm, and even more preferably 5 nm to 50 nm. Furthermore, the average particle size of the resin particles is determined by measuring the volume average particle size using a particle size distribution measuring device (e.g., Nikkiso Co., Ltd., product name "NANOTRA C UPA-EX150") via dynamic light scattering.

[0160] When the white ink contains resin particles, the content of resin particles relative to the total amount of white ink is preferably 0.1% to 15% by mass, more preferably 0.5% to 10% by mass, even more preferably 1% to 8% by mass, and even more preferably 2% to 5% by mass.

[0161] (additive)

[0162] Depending on the requirements, the white ink prepared in the white ink preparation process may contain additives such as surfactants, co-sensitizers, ultraviolet absorbers, antioxidants, anti-fading agents, conductive salts, and alkaline compounds.

[0163] (physical properties)

[0164] From the viewpoint of improving spraying stability, the pH of the white ink is preferably 7 to 10, more preferably 7.5 to 9.5. The pH is measured using a pH meter at 25°C, for example using a pH meter (model "HM-31") manufactured by DKK-TOA CORPORATION.

[0165] The viscosity of the white ink is preferably 0.5 mPa·s to 30 mPa·s, more preferably 2 mPa·s to 20 mPa·s, more preferably 2 mPa·s to 15 mPa·s, and even more preferably 3 mPa·s to 10 mPa·s. The viscosity is measured using a viscometer at 25°C, for example, using a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

[0166] The surface tension of the white ink is preferably below 60 mN / m, more preferably 20 mN / m to 50 mN / m, and even more preferably 30 mN / m to 45 mN / m. The surface tension is measured using a surface tension meter at 25°C, for example, using an automatic surface tension meter (product name "CBVP-Z") manufactured by Kyowa Interface Science Co., Ltd., measured by the plate method.

[0167] <Coloring Ink Preparation Process>

[0168] The image recording method of the present invention includes a step of preparing a coloring ink containing a coloring pigment other than white pigment, a second organic solvent with a boiling point of 120°C or higher, and water (hereinafter referred to as the "coloring ink preparation step").

[0169] The coloring ink prepared in the coloring ink preparation step can be one type or two or more types of coloring ink. For recording multicolor images, the coloring ink prepared in the coloring ink preparation step preferably contains two or more types of coloring ink. That is, the image recording method of the present invention preferably includes a step of preparing at least two types of coloring ink containing a coloring pigment other than white pigment, a second organic solvent with a boiling point of 120°C or higher, and water.

[0170] (Coloring pigments)

[0171] The coloring ink prepared in the coloring ink preparation process contains coloring pigments other than white pigments. Hereinafter, coloring pigments other than white pigments will be referred to simply as "coloring pigments".

[0172] The coloring pigment contained in the coloring ink can be a colored pigment, a black pigment, or a combination of one or more colored pigments and one or more black pigments.

[0173] Colored pigments are any pigments that produce a color; there are no particular restrictions on the type. "Colored" refers to colors with a hue.

[0174] As colored pigments, there are no particular limitations; examples include cyan, magenta, yellow, blue, red, green, orange, and purple pigments.

[0175] Specifically, examples of colored pigments include azo pigments, diazo pigments, condensed diazo pigments, phthalocyanine pigments, quinacridone pigments, quinacridone quinone pigments, anthraquinone pigments, aminoanthraquinone pigments, anthraquinone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, viola cyclohexane pigments, perylene pigments, isoindoline pigments, isoindolineone pigments, isoviolanthrone pigments, benzimidazolone pigments, indanone pigments, triarylcarbium pigments, and diketopyrrole pigments, among other organic pigments.

[0176] More specifically, examples of colored pigments include:

[0177] Perylene pigments such as CI Pigment Red 190, CI Pigment Red 224, and CI Pigment Violet 29;

[0178] CI pigment orange 43, CI pigment red 194 and other violet ring ketone pigments;

[0179] Quinacridone pigments such as CI Pigment Violet 19, CI Pigment Violet 42, CI Pigment Red 122, CI Pigment Red 192, CI Pigment Red 202, CI Pigment Red 207, and Pigment Red 209;

[0180] Quinacridone quinone pigments such as CI Pigment Red 206, CI Pigment Orange 48, and CI Pigment Orange 49;

[0181] Anthraquinone pigments such as CI Pigment Yellow 147;

[0182] CI Pigment Red 168 and other anthraquinone-embedded pigments;

[0183] CI Pigment Brown 25, CI Pigment Purple 32, CI Pigment Orange 36, CI Pigment Yellow 120, CI Pigment Yellow 180, Pigment Yellow 181, CI Pigment Orange 62, CI Pigment Red 185, etc., are benzimidazole pigments.

[0184] CI Pigment Yellow 93, CI Pigment Yellow 94, CI Pigment Yellow 95, CI Pigment Yellow 128, CI Pigment Yellow 166, CI Pigment Orange 34, CI Pigment Orange 13, CI Pigment Orange 31, Pigment Red 144, Pigment Red 166, Pigment Red 220, CI Pigment Red 221, CI Pigment Red 242, Pigment Red 248, CI Pigment Red 262, CI Pigment Brown 23, etc., are condensed diazo pigments.

[0185] CI Pigment Yellow 13, CI Pigment Yellow 83, CI Pigment Yellow 188 and other diazo pigments;

[0186] CI Pigment Red 187, CI Pigment Red 170, CI Pigment Yellow 74, CI Pigment Yellow 150, CI Pigment Red 48, Pigment Red 53, CI Pigment Orange 64, CI Pigment Red 247 and other azo pigments;

[0187] CI Pigment Blue 60 and other indanone pigments;

[0188] Phthalocyanine pigments such as CI Pigment Green 7, CI Pigment Green 36, CI Pigment Green 37, CI Pigment Green 58, CI Pigment Blue 16, CI Pigment Blue 75, and Pigment Blue 15;

[0189] Triaryl carbomon pigments such as CI Pigment Blue 56 and CI Pigment Blue 61;

[0190] dioxazine pigments such as CI pigment violet 23 and CI pigment violet 37;

[0191] CI Pigment Red 177 and other aminoanthraquinone pigments;

[0192] CI Pigment Red 254, CI Pigment Red 255, CI Pigment Red 264, CI Pigment Red 272, CI Pigment Orange 71, CI Pigment Orange 73, etc., are diketopyrrolopyrrole pigments.

[0193] CI pigments, Red 88, and other sulfur-indigo pigments;

[0194] CI Pigment Yellow 139, Pigment Orange 66 and other isoindoline pigments;

[0195] Pigment Yellow 109, CI Pigment Orange 61, and other isoindolinetone pigments;

[0196] CI Pigment Orange 40, CI Pigment Red 216, and other pinantrone pigments;

[0197] And isoviolet anthrone pigments such as CI pigment violet 31.

[0198] Any black pigment is acceptable; there is no particular limitation on the type. Examples of black pigments include carbon black and titanium black.

[0199] The average particle size of the coloring pigment is preferably 10 nm to 200 nm, more preferably 10 nm to 150 nm, and even more preferably 10 nm to 110 nm. If the average particle size is 200 nm or less, color reproduction is good, and consequently, jetting stability is good when recording images using an inkjet recording method. On the other hand, if the average particle size is 10 nm or more, lightfastness is good. Furthermore, the pigment particle size distribution can be either a broad particle size distribution or a monodisperse particle size distribution. The average particle size and particle size distribution of the pigment are determined as follows: the volume average particle size is measured using a particle size distribution measuring device (e.g., Nikkiso Co., Ltd., product name "NANOTRACUPA-EX150") by dynamic light scattering. Additionally, when the pigment is coated with a pigment dispersant, the average particle size of the pigment represents the average particle size of the pigment coated with the pigment dispersant.

[0200] From the viewpoints of image density, sprayability, and resprayability, the content of coloring pigment relative to the total amount of coloring ink is preferably 1% to 15% by mass, more preferably 2% to 10% by mass.

[0201] (Second organic solvent with a boiling point above 120°C)

[0202] The coloring ink prepared in the coloring ink preparation process contains a second organic solvent with a boiling point of 120°C or higher. Hereinafter, the organic solvent with a boiling point of 120°C or higher contained in the coloring ink will also be referred to as the "second organic solvent".

[0203] As an organic solvent with a boiling point of 120°C or higher, examples of organic solvents with a boiling point of 120°C or higher that are the same as those contained in the aforementioned white ink can be cited.

[0204] If the coloring ink contains a second organic solvent, its sprayability and resprayability are excellent. The coloring ink may also contain an organic solvent with a boiling point below 120°C. From the viewpoint of sprayability and resprayability, the proportion of the second organic solvent in the organic solvent contained in the coloring ink is preferably 50% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. The above proportion may also be 100% by mass. That is, all the organic solvent contained in the coloring ink may be the second organic solvent.

[0205] In the coloring ink, the content of the second organic solvent is preferably 30% by mass or less, more preferably 26% by mass or less, relative to the total amount of the coloring ink. If the content of the second organic solvent is 30% by mass or less, image strength can be ensured even in overlapping areas, thereby improving the adhesion between the image and the laminating substrate. As a result, excellent lamination strength is achieved.

[0206] The lower limit of the content of the second organic solvent is not particularly limited as long as it exceeds 0% by mass. However, from the viewpoint of sprayability and concealment, the content of the second organic solvent relative to the total amount of the coloring ink is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more.

[0207] In particular, from the viewpoint of further improving lamination strength, the content of organic solvents with a boiling point of 120°C or higher is preferably 30% by mass or less relative to the total mass of each ink, for both white and colored inks. That is, preferably, the content of the first organic solvent is 30% by mass or less relative to the total mass of the white ink, and the content of the second organic solvent is 30% by mass or less relative to the total mass of the colored ink. The lower limit is not particularly limited; for example, 5% by mass or more can be cited.

[0208] From the viewpoint of further improving lamination strength, the coloring ink particularly preferably contains an organic solvent with a boiling point of 120°C to 200°C (hereinafter also referred to as "second organic solvent A"). The proportion of second organic solvent A in the organic solvent contained in the coloring ink is preferably 50% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The above proportion may also be 100% by mass. That is, all the organic solvent contained in the coloring ink may be second organic solvent A.

[0209] The second organic solvent A preferably contains at least one selected from the group consisting of alkylene glycols and alkylene glycol alkyl ethers. More preferably, the second organic solvent A contains at least one alkylene glycol and at least one alkylene glycol alkyl ether. Even more preferably, the second organic solvent A contains at least one alkylene glycol and at least two alkylene glycol alkyl ethers.

[0210] The alkylene glycols and alkylene glycol alkyl ethers contained in the second organic solvent A are preferably selected from the group consisting of propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol, dipropylene glycol monomethyl ether, diethylene glycol monoethyl ether, and ethylene glycol.

[0211] If the coloring ink contains an organic solvent, and that organic solvent contains at least one alkylene glycol with a boiling point of 120°C to 200°C and at least one alkylene glycol alkyl ether with a boiling point of 120°C to 200°C, then the drying properties of the coloring ink on the substrate are improved. This, in turn, improves lamination strength and adhesion.

[0212] Furthermore, if the coloring ink contains an organic solvent containing at least one alkylene glycol with a boiling point of 120°C to 200°C and at least two alkylene glycol alkyl ethers with a boiling point of 120°C to 200°C, the drying properties of the coloring ink on the substrate are further improved, and the lamination suitability and adhesion become good.

[0213] When the coloring ink contains alkylene glycols and alkylene glycol alkyl ethers, from the viewpoint of further improving lamination strength and adhesion, the mass ratio of the alkylene glycol content to the alkylene glycol alkyl ether content (“alkylene glycol content” / “alkylene glycol alkyl ether content”) is preferably 20.0 or less, more preferably 18.0 or less, further preferably 15.0 or less, even more preferably 10.0 or less, particularly preferably 8.0 or less, and even more preferably 6.0 or less. The lower limit of the above mass ratio is not particularly limited, but from the viewpoint of re-spraying properties, it is preferably 1.0, more preferably 2.0, further preferably 3.0, and even more preferably 4.0.

[0214] In addition to the second organic solvent A, the coloring ink may also contain an organic solvent with a boiling point exceeding 200°C and below 240°C (hereinafter referred to as "the second organic solvent B"), and may also contain an organic solvent with a boiling point exceeding 240°C (hereinafter referred to as "the second organic solvent C").

[0215] From the viewpoint of further improving the lamination strength and adhesion of image recordings, the total proportion of the second organic solvent A and the second organic solvent B in the organic solvent contained in the coloring ink is preferably 90% by mass or more, preferably 95% by mass or more. The above proportion may also be 100% by mass. That is, the organic solvent contained in the coloring ink may be entirely composed of the second organic solvent A and the second organic solvent B, or the second organic solvent B alone.

[0216] Examples of first organic solvents B include diethylene glycol monobutyl ether, dipropylene glycol, and 1,2-hexanediol.

[0217] From the viewpoint of further improving the lamination strength and adhesion of image recordings, the proportion of the second organic solvent C in the organic solvent contained in the coloring ink is preferably 10% by mass or less. The above proportion can also be 0% by mass. That is, the coloring ink can be free of the second organic solvent C.

[0218] Examples of second organic solvents C include diethylene glycol and triethylene glycol.

[0219] The weighted average SP value of the organic solvents contained in the coloring ink is preferably 28 MPa. 1 / 2 The following applies, particularly to white inks and colored inks, where the weighted average SP value of the organic solvents contained in each ink is preferably 28 MPa. 1 / 2 the following.

[0220] The weighted average of the SP values ​​of the organic solvents contained in the colored inks is calculated using the same method as the weighted average of the SP values ​​of the organic solvents contained in the white inks.

[0221] If the weighted average SP value of the organic solvents contained in the coloring ink is 28 MPa 1 / 2 The lamination strength of the image recording is thus increased. From the viewpoint of lamination strength, the aforementioned weighted average is more preferably 27 MPa. 1 / 2 From the viewpoint of jetting and re-jetting properties, the lower limit of the above weighted average value is preferably 25.5 MPa. 1 / 2 .

[0222] (water)

[0223] The coloring ink prepared in the coloring ink preparation process contains water. The water content is not particularly limited, for example, it can be 40% to 70% by mass.

[0224] (Pigment dispersant)

[0225] The coloring ink prepared in the coloring ink preparation process preferably contains a pigment dispersant to disperse the coloring pigment in water. Alternatively, if a self-dispersible pigment that can be dispersed in water even without a pigment dispersant is used as the coloring pigment, the coloring ink may not contain a pigment dispersant.

[0226] The form of the pigment dispersant contained in the coloring ink is not particularly limited, and it can be any of the following: random polymer, block polymer, and graft polymer. Furthermore, the pigment dispersant contained in the coloring ink can also be a polymer with a cross-linked structure. Preferably, the pigment dispersant contained in the coloring ink is a polymer with a cross-linked structure. It is believed that if the pigment dispersant is a polymer with a cross-linked structure, the pigment dispersant is less likely to detach from the surface of the coloring pigment. As a result, the dispersion stability of the coloring pigment is high. Since the organic solvent easily evaporates after the coloring ink drips onto the non-permeable substrate, the lamination strength is further improved.

[0227] When the pigment dispersant contained in the colored ink is a polymer with a cross-linked structure, the preferred method for the polymer with a cross-linked structure is the same as the preferred method when the pigment dispersant contained in the white ink is a polymer with a cross-linked structure.

[0228] The mixing ratio of coloring pigment to pigment dispersant, based on mass, is preferably 1:0.06 to 1:3, more preferably 1:0.125 to 1:2, and even more preferably 1:0.125 to 1:1.5.

[0229] (Resin particles)

[0230] From the viewpoint of improving the lamination strength of image recordings, the coloring ink prepared in the coloring ink preparation process preferably contains at least one type of resin particles. The coloring ink preferably contains resin particles in addition to a pigment dispersant, and these resin particles are particles composed of resin.

[0231] The preferred method for the resin particles contained in the colored ink is the same as the preferred method for the resin particles contained in the white ink described above.

[0232] When the coloring ink contains resin particles, the content of resin particles relative to the total amount of the coloring ink is preferably 0.1% to 15% by mass, more preferably 0.5% to 10% by mass, even more preferably 1% to 8% by mass, and even more preferably 2% to 6% by mass.

[0233] (additive)

[0234] Depending on the requirements, the coloring ink prepared in the coloring ink preparation process may contain additives such as surfactants, co-sensitizers, ultraviolet absorbers, antioxidants, anti-fading agents, conductive salts, and alkaline compounds.

[0235] (physical properties)

[0236] From the viewpoint of improving spraying stability, the pH of the coloring ink is preferably 7 to 10, more preferably 7.5 to 9.5. The pH is measured using a pH meter at 25°C, for example using a pH meter (model "HM-31") manufactured by DKK-TOA CORPORATION.

[0237] The viscosity of the coloring ink is preferably 0.5 mPa·s to 30 mPa·s, more preferably 2 mPa·s to 20 mPa·s, more preferably 2 mPa·s to 15 mPa·s, and even more preferably 3 mPa·s to 10 mPa·s. The viscosity is measured using a viscometer at 25°C, for example, using a TV-22 type viscometer manufactured by Toki Sangyo Co., Ltd.

[0238] The surface tension of the coloring ink is preferably below 60 mN / m, more preferably 20 mN / m to 50 mN / m, and even more preferably 30 mN / m to 45 mN / m. The surface tension is measured using a surface tension meter at 25°C, for example, using an automatic surface tension meter (product name "CBVP-Z") manufactured by Kyowa Interface Science Co., Ltd., measured by the plate method.

[0239] <Image Recording Process>

[0240] The image recording method of the present invention includes a step (hereinafter referred to as the "image recording step") of separately applying white ink and colored ink to a non-permeable substrate to record an image. In the image recording step, in the area where the area where white ink is applied and the area where colored ink is applied overlaps in a top view, the total applied mass of a first organic solvent and a second organic solvent per unit area is 5.5 g / m². 2 The following applies to white pigment with a mass of 0.4 g / m² per unit area. 2 Record the image under the above conditions.

[0241] (Non-permeable substrate)

[0242] In this invention, the non-permeability of the non-permeable substrate refers to the property that the water absorption rate is less than 2.5% over 24 hours as measured according to ASTM D570-98 (2018). Here, the "%" used as the unit of water absorption rate is based on mass. The aforementioned water absorption rate is preferably less than 1.0%, more preferably less than 0.5%.

[0243] Materials that can be used as non-permeable substrates include, for example, glass, metals (e.g., aluminum, zinc, copper, etc.) and resins (e.g., polyvinyl chloride, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl alcohol acetal, nylon, acrylic resin, etc.).

[0244] The preferred material for the non-permeable substrate is resin.

[0245] From a general perspective, the preferred materials for non-permeable substrates are polypropylene, polyethylene, polyethylene terephthalate, nylon, acrylic resin, or polyvinyl chloride.

[0246] The shape of the non-permeable substrate is preferably sheet (film) or plate. Examples of non-permeable substrates with this shape include glass plates, metal plates, resin sheets (resin films), paper laminated with plastic, paper laminated or vapor-deposited with metal, and plastic sheets (plastic films) laminated or vapor-deposited with metal.

[0247] As a resin-based non-permeable substrate, examples include resin sheets (resin films), and more specifically, flexible packaging materials for packaged foods and floor guide panels in large retail stores.

[0248] In addition to sheet-like (film-like) or plate-like non-permeable substrates, textiles (fabrics) and non-woven fabrics formed from non-permeable fibers can also be cited as examples of non-permeable substrates.

[0249] The thickness of the non-permeable substrate is preferably 0.1 μm to 1,000 μm, more preferably 0.1 μm to 800 μm, and even more preferably 1 μm to 500 μm.

[0250] Hydrophilic treatment can be applied to non-permeable substrates. Examples of hydrophilic treatments include corona treatment, plasma treatment, flame treatment, heat treatment, abrasion treatment, light irradiation treatment (e.g., UV treatment), but are not limited to these. Corona treatment can be performed, for example, using a corona master (product name "PS-10S", manufactured by Shinko Electric & Instrumentation Co., Ltd.). The conditions for corona treatment can be appropriately selected depending on the type of non-permeable substrate.

[0251] The non-permeable substrate can be heated before applying white ink and colored ink. The heating temperature can be appropriately set according to the type of non-permeable substrate, but it is preferable to set the temperature of the non-permeable substrate to 30°C to 70°C, and more preferably to 30°C to 60°C.

[0252] (Order of application of white ink and colored ink)

[0253] In the image recording process, white ink and colored ink are applied to a non-permeable substrate, respectively. The order in which the white ink and colored ink are applied is not particularly limited; the white ink can be applied after the colored ink is applied to the non-permeable substrate, or vice versa. When the non-permeable substrate is transparent and intended for back-side printing, it is preferable to apply the white ink after the colored ink is applied to the non-permeable substrate. That is, the image recording method of the present invention preferably includes a step of applying colored ink to a non-permeable substrate and a step of applying white ink to a colored ink film formed by applying the colored ink.

[0254] (Conditions for applying white ink and colored ink)

[0255] In the image recording process, an image is recorded by applying white ink and colored ink respectively under the condition that the areas to which white ink is applied and the areas to which colored ink is applied overlap when viewed from above (hereinafter referred to as the "overlapping area").

[0256] In the image recording process, white ink and colored ink can be applied to areas that overlap and areas outside the overlapping areas, respectively.

[0257] For example, a patterned colored ink film can be formed by applying colored ink in a patterned manner to a non-permeable substrate. Then, a white ink film can be formed by applying white ink to a region spanning the colored ink film and the area outside the colored ink film (e.g., a region covering the colored ink film and its entire surrounding area) (e.g., a solid area). In this case, the area where the colored ink film exists corresponds to the aforementioned "overlapping area," and the areas where the white ink film exists but the colored ink film does not exist, as well as the areas where neither the colored ink film nor the white ink film exists, correspond to the aforementioned "areas outside the overlapping area."

[0258] (The quality imparted by white ink and colored ink)

[0259] In the image recording process, in the overlapping area, the total mass of the first and second organic solvents per unit area is 5.5 g / m². 2 The following applies to white pigment with a mass of 0.4 g / m² per unit area. 2 Record the image under the above conditions.

[0260] In the overlapping region, if the total mass of the first and second organic solvents per unit area is 5.5 g / m² 2 Therefore, when white ink and colored ink are applied to a non-permeable substrate, image strength can be ensured, thereby improving the adhesion between the image and the laminating substrate. As a result, excellent lamination strength is achieved.

[0261] In the overlapping region, if the mass of white pigment applied per unit area is 0.4 g / m² 2 In this way, by using white pigment to retain the surrounding organic solvent, image strength can be ensured, thereby improving the adhesion between the image and the laminating substrate. As a result, excellent lamination strength is achieved. Furthermore, in the overlapping areas, if the mass of white pigment applied per unit area is 0.4 g / m²... 2 The above demonstrates excellent concealment.

[0262] Mass of the first organic solvent assigned per unit area in the overlapping region (in g / m²) 2 It is calculated by multiplying the mass of white ink assigned per unit area in the overlapping region by the content (mass%) of the first organic solvent relative to the total amount of white ink.

[0263] Mass of the second organic solvent assigned per unit area in the overlapping region (in g / m²) 2 It is calculated by multiplying the mass of the colored ink per unit area in the overlapping region by the content (mass%) of the second organic solvent relative to the total amount of colored ink.

[0264] Mass of white pigment assigned per unit area in the overlapping region (in g / m²) 2 It is calculated by multiplying the mass of white ink assigned per unit area in the overlapping region by the content (mass%) of white pigment relative to the total amount of white ink.

[0265] In the overlapping areas, the mass imparted by white ink per unit area and the mass imparted by colored ink per unit area (unit: g / m²) 2 The calculations are based on the resolution, the dot ratio of the image, and the weight of each drop of ink.

[0266] From the viewpoint of further improving lamination strength, in the overlapping region, the total mass imparted by the first and second organic solvents per unit area is preferably 5.5 g / m². 2 The following is more preferably 5.0 g / m 2 The following is a further preferred value: 4.5 g / m 2 From the perspective of concealment rate, the lower limit of the total imparted mass is preferably 3.0 g / m³. 2 .

[0267] From the perspective of further improving lamination strength and concealment, the preferred mass of white pigment per unit area in the overlapping region is 0.8 g / m². 2 The above, more preferably 1.0 g / m 2That's all. From the viewpoint of jetting and re-jetting properties, the upper limit of the mass imparted is preferably 1.2 g / m³. 2 .

[0268] (Method for applying white ink)

[0269] There are no particular limitations on the method of applying white ink, and known methods such as coating, dipping, and inkjet recording can be cited. However, from the viewpoint of being able to record high-definition images, inkjet recording is the preferred method for applying white ink.

[0270] There are no particular restrictions on the ink ejection method in inkjet recording. It can be any of the known methods, such as charge control method that uses electrostatic attraction to eject ink, on-demand inkjet method (pressure pulse method) that uses the vibration pressure of piezoelectric elements, acoustic inkjet method that converts electrical signals into sound beams that irradiate the ink and uses radiation pressure to eject ink, and thermal inkjet method (Bubble Jet (registered trademark)) that heats the ink to form bubbles and uses the resulting pressure.

[0271] As an inkjet recording method, the inkjet recording method described in Japanese Patent Application Publication No. 54-59936 can be used particularly effectively. In this inkjet recording method, the ink undergoes a rapid volume change under the influence of heat energy, and the ink is ejected from the nozzle by the force generated by this change in state. The method described in paragraphs 0093 to 0105 of Japanese Patent Application Publication No. 2003-306623 can also be used as an inkjet recording method.

[0272] Applying ink to a non-permeable substrate using inkjet recording is done by ejecting ink from the nozzles of an inkjet head.

[0273] As for inkjet head types, there are reciprocating methods where short, strip-shaped serial inkjet heads scan and record simultaneously in the width direction of the recorded medium, and line methods where recording elements are arranged in a row type inkjet head corresponding to the entire area of ​​one side of the recorded medium.

[0274] In line mode, by scanning the recording medium along a direction intersecting the arrangement direction of the recording elements, images can be recorded across the entire surface of the recording medium. In line mode, the transport system, such as the carriage used in reciprocating mode for scanning short, strip-shaped inkjet heads, is unnecessary. Furthermore, compared to reciprocating mode, line mode eliminates the need for complex scanning control between the carriage movement and the recording medium; only the recording medium is moved. Therefore, line mode increases image recording speed compared to reciprocating mode.

[0275] The ink is preferably applied using an inkjet head with a resolution of 300 dpi or higher (more preferably 600 dpi or higher, and even more preferably 800 dpi or higher). Here, dpi is an abbreviation for dots per inch, and 1 inch is 2.54 cm.

[0276] From the viewpoint of obtaining high-definition images, the amount of ink droplets ejected from the nozzle of the inkjet head is preferably 1 pL (picoliter) to 10 pL, more preferably 1.5 pL to 6 pL. Furthermore, from the viewpoint of improving image uniformity and continuity, combining different droplet volumes is also effective.

[0277] (Methods for applying coloring inks)

[0278] There are no particular limitations on the method of applying coloring inks; known methods such as coating, dipping, and inkjet recording are examples. However, from the viewpoint of being able to record high-resolution images, inkjet recording is preferred for applying coloring inks. Details regarding inkjet recording are the same as those for applying white inks.

[0279] <Pretreatment Solution Preparation Process>

[0280] The image recording method of the present invention preferably further includes a step of preparing a pretreatment liquid containing a coagulant and water (hereinafter referred to as the "pretreatment liquid preparation step"). In the image recording step, after the pretreatment liquid is applied to a non-permeable substrate, white ink and colored ink are applied respectively to record the image.

[0281] By pre-treating a non-permeable substrate with a pretreatment solution, the components in white and colored inks are agglomerated by a coagulant contained in the pretreatment solution. In particular, the agglomerating effect of the coagulant is high when the white and colored inks contain pigment dispersants and resin particles. The adhesion between the non-permeable substrate and the white and colored ink films is improved, thereby further increasing the lamination strength.

[0282] (Flocculant)

[0283] The pretreatment solution prepared in the pretreatment solution preparation step preferably contains a coagulant. The coagulant is not particularly limited to any component that causes the components in white ink and colored ink to agglomerate. The coagulant is preferably selected from at least one of the group consisting of polyvalent metal compounds, organic acids, metal complexes, and cationic polymers, and more preferably includes an organic acid.

[0284] -Polyvalent metal compounds-

[0285] Examples of polyvalent metal compounds include salts of alkaline earth metals (e.g., magnesium, calcium) from Group 2 of the periodic table, transition metals (e.g., lanthanum) from Group 3 of the periodic table, metals (e.g., aluminum) from Group 13 of the periodic table, and lanthanides (e.g., neodymium).

[0286] Salts of these metals are preferably salts of organic acids, nitrates, chlorides, or thiocyanates, as described later.

[0287] The polyvalent metal compound is preferably a calcium or magnesium salt of an organic acid (e.g., formic acid, acetic acid, benzoic acid, etc.); a calcium or magnesium salt of nitric acid; or a calcium or magnesium salt of calcium chloride, magnesium chloride, or thiocyanate.

[0288] Preferably, at least a portion of the polyvalent metal compound dissociates into polyvalent metal ions and counterions in the pretreatment solution.

[0289] -Organic acids-

[0290] Organic acids can be exemplified by organic compounds having acidic groups.

[0291] Examples of acidic groups include phosphate, phosphonic acid, hypophosphonic acid, sulfate, sulfonic acid, sulfinic acid, and carboxyl groups.

[0292] From the viewpoint of ink agglomeration speed, the acidic group is preferably a phosphate group or a carboxyl group, and more preferably a carboxyl group.

[0293] Preferably, at least a portion of the acidic groups dissociate in the pretreatment solution.

[0294] Examples of organic compounds containing a carboxyl group include (meth)acrylic acid, poly(meth)acrylic acid, acetic acid, formic acid, benzoic acid, glycolic acid, malonic acid, malic acid (preferably DL-malic acid), maleic acid, succinic acid, glutaric acid, pimelic acid, adipic acid, fumaric acid, citric acid, tartaric acid, phthalic acid, 4-methylphthalic acid, lactic acid, pyrrolidone carboxylic acid, pyranone carboxylic acid, pyrrolic carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, and nicotinic acid.

[0295] From the viewpoint of ink agglomeration speed, organic compounds with carboxyl groups are preferably carboxylic acids with a valence of 2 or higher (hereinafter also referred to as polycarboxylic acids), and more preferably dicarboxylic acids.

[0296] Specifically, the polycarboxylic acid is preferably malonic acid, malic acid, maleic acid, succinic acid, glutaric acid, pimelic acid, adipic acid, fumaric acid, tartaric acid, 4-methylphthalic acid, or citric acid, and more preferably malonic acid, malic acid, tartaric acid, succinic acid, glutaric acid, pimelic acid, adipic acid, or citric acid.

[0297] The organic acid is preferably low in pKa (e.g., 1.0 to 5.0). Thus, by contacting with an organic acid with a lower pKa, the surface charge of particles such as pigments and resin particles in the ink, which are dispersed and stabilized by weakly acidic functional groups such as carboxyl groups, can be reduced, thereby reducing dispersion stability.

[0298] The organic acid preferably has a low pKa, high solubility in water, and a valence of 2 or higher. Furthermore, the organic acid is more preferably characterized by a high buffering capacity in a pH region lower than the pKa of the functional group (e.g., carboxyl group) that stabilizes the particle dispersion in the ink.

[0299] -Metal complex-

[0300] The metal complex preferably contains at least one metal element selected from the group consisting of zirconium, aluminum and titanium.

[0301] The metal complex is preferably a metal complex containing at least one ligand selected from the group consisting of acetate, acetylacetone, methyl acetoacetate, ethyl acetoacetate, octanediol, butoxyacetylacetone, lactate, ammonium lactate and triethanolamine.

[0302] Metal complexes are commercially available. Various organic ligands (especially multidentate ligands capable of forming metal chelating catalysts) are commercially available. Therefore, metal complexes can be prepared by combining commercially available organic ligands with metals.

[0303] Examples of metal complexes include zirconium tetraacetylacetone (e.g., ORGATIX ZC-150 manufactured by Matsumoto Fine Chemical Co., Ltd.), zirconium monoacetylacetone (e.g., ORGATIX ZC-540 manufactured by Matsumoto Fine Chemical Co., Ltd.), zirconium diacetylacetone (e.g., ORGATIX ZC-550 manufactured by Matsumoto Fine Chemical Co., Ltd.), zirconium monoacetylacetone (e.g., ORGATIX ZC-560 manufactured by Matsumoto Fine Chemical Co., Ltd.), zirconium acetate (e.g., ORGATIX ZC-115 manufactured by Matsumoto Fine Chemical Co., Ltd.), diisopropoxybis(acetylacetone)titanium (e.g., ORGATIX TC-100 manufactured by Matsumoto Fine Chemical Co., Ltd.), and titanium tetraacetylacetone (e.g., ORGATIX manufactured by Matsumoto Fine Chemical Co., Ltd.). TC-401”), dioctyloxybis(octyl glycol) titanium (e.g., “ORGATIX TC-200” manufactured by Matsumoto Fine Chemical Co., Ltd.), diisopropoxybis(ethyl acetoacetate) titanium (e.g., “ORGATIX TC-750” manufactured by Matsumoto Fine Chemical Co., Ltd.), zirconium tetraacetylacetonate (e.g., “ORGATIX ZC-700” manufactured by Matsumoto Fine Chemical Co., Ltd.), zirconium tributoxymonoacetylacetonate (e.g., “ORGATIX ZC-540” manufactured by Matsumoto Fine Chemical Co., Ltd.), zirconium monobutoxyacetylacetonate bis(ethyl acetoacetate) (e.g., “ORGATIX ZC-570” manufactured by Matsumoto Fine Chemical Co., Ltd.), zirconium dibutoxybis(ethyl acetoacetate) (e.g., “ORGATIX ZC-570” manufactured by Matsumoto Fine Chemical Co., Ltd.), zirconium dibutoxybis(ethyl acetoacetate) (e.g., “ORGATIX” manufactured by Matsumoto Fine Chemical Co., Ltd.). ZC-580”), aluminum triacetylacetonate (e.g., “ORGATIX AL-80” manufactured by Matsumoto Fine Chemical Co., Ltd.), ammonium titanium lactate (e.g., “ORGATIX TC-300” manufactured by Matsumoto Fine Chemical Co., Ltd.), titanium lactate (e.g., “ORGATIX TC-300” manufactured by Matsumoto Fine Chemical Co., Ltd.).Matsumoto Fine Chemical Co., Ltd. manufactures "ORGATIX TC-310, 315", triethanolamine titanium (Matsumoto Fine Chemical Co., Ltd. manufactures "ORGATIX TC-400"), and zirconium chloride compounds (e.g., Matsumoto Fine Chemical Co., Ltd. manufactures "ORGATIX ZC-126").

[0304] The metal complex is preferably titanium ammonium lactate (e.g., ORGATIX TC-300 manufactured by Matsumoto Fine Chemical Co., Ltd.), titanium lactate (e.g., ORGATIX TC-310, 315 manufactured by Matsumoto Fine Chemical Co., Ltd.), titanium triethanolamine (e.g., ORGATIX TC-400 manufactured by Matsumoto Fine Chemical Co., Ltd.), or zirconium chloride compound (e.g., ORGATIX ZC-126 manufactured by Matsumoto Fine Chemical Co., Ltd.).

[0305] -Catonic polymer-

[0306] Furthermore, the pretreatment solution can be in the form of containing one or more cationic polymers as coagulation components. The cationic polymers are preferably homopolymers, copolymers, or condensation polymers of cationic monomers having primary to tertiary amino groups or quaternary ammonium groups. As cationic polymers, they can be used in any form, either as water-soluble polymers or water-dispersible latex particles.

[0307] Examples of cationic polymers include polyvinylpyridine salts, polyalkylaminoethyl acrylates, polyalkylaminoethyl methacrylates, polyvinylimazoles, polyethyleneimine, polybiguanidines, polyguanidines, polyallylamines, and their derivatives.

[0308] From the viewpoint of the viscosity of the pretreatment solution, a lower weight-average molecular weight of the cationic polymer is preferable. When the pretreatment solution is applied to the recording medium using an inkjet printing method, a weight-average molecular weight of 1,000 to 500,000 is preferred, more preferably 1,500 to 200,000, and even more preferably 2,000 to 100,000. A weight-average molecular weight of 1,000 or higher is advantageous from the viewpoint of agglomeration rate. A weight-average molecular weight of 500,000 or lower is advantageous from the viewpoint of jetting reliability. However, this is not a limitation when the pretreatment solution is applied to the recording medium using methods other than inkjet printing.

[0309] The pretreatment solution may contain only one type of coagulant or two or more types.

[0310] The content of the coagulant relative to the total amount of the pretreatment liquid is preferably 0.1% to 40% by mass, more preferably 0.1% to 30% by mass, even more preferably 1% to 20% by mass, and particularly preferably 1% to 10% by mass.

[0311] (water)

[0312] The pretreatment solution prepared in the pretreatment solution preparation process preferably contains water. The water content is not particularly limited, for example, it can be 40% to 70% by mass.

[0313] (Organic solvents)

[0314] The pretreatment solution prepared in the pretreatment solution preparation process may contain organic solvents, or it may contain a third organic solvent with a boiling point of 120°C or higher. Hereinafter, the organic solvent with a boiling point of 120°C or higher contained in the pretreatment solution will be referred to as the "third organic solvent".

[0315] When the pretreatment solution contains a third organic solvent with a boiling point of 120°C or higher, the content of the third organic solvent relative to the total amount of the pretreatment solution is preferably 15% by mass or less, more preferably 5% by mass or less. The lower limit of the content of the third organic solvent is not particularly limited and can be 0% by mass. That is, the pretreatment solution may not contain the third organic solvent. If the content of the third organic solvent is 15% by mass or less, image strength can be ensured even in overlapping areas, thereby improving the adhesion between the image and the substrate for lamination. As a result, lamination strength is improved.

[0316] Examples of third organic solvents include propylene glycol and propylene glycol monomethyl ether.

[0317] (Other ingredients)

[0318] Depending on the requirements, the pretreatment solution may contain components other than coagulants and water. Other components that may be contained in the pretreatment solution include resin particles, surfactants, solid wetting agents, colloidal silica, inorganic salts, anti-fading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, preservatives, mildew inhibitors, pH adjusters, viscosity adjusters, rust inhibitors, chelating agents, and water-soluble polymers (e.g., the water-soluble polymers described in paragraphs 0026 to 0080 of Japanese Patent Application Publication No. 2013-001854).

[0319] (physical properties)

[0320] From the viewpoint of ink agglomeration rate, the pH of the pretreatment solution is preferably 0.1 to 4.5, more preferably 0.2 to 4.0. The pH is measured using a pH meter at 25°C, for example using a pH meter (model "HM-31") manufactured by DKK-TOA CORPORATION.

[0321] From the viewpoint of ink agglomeration rate, the viscosity of the pretreatment solution is preferably 0.5 mPa·s to 10 mPa·s, more preferably 1 mPa·s to 5 mPa·s. The viscosity is the value measured using a viscometer at 25°C. Viscosity is measured using a viscometer at 25°C, for example, using a TV-22 type viscometer manufactured by Toki Sangyo Co., Ltd.

[0322] The surface tension of the pretreatment liquid is preferably below 60 mN / m, more preferably 20 mN / m to 50 mN / m, and even more preferably 30 mN / m to 45 mN / m. The surface tension is a value measured at 25°C. The surface tension is measured using a surface tension meter at 25°C, for example, using an automatic surface tension meter (product name "CBVP-Z") manufactured by Kyowa Interface Science Co., Ltd., measured by the plate method.

[0323] (The order in which the pretreatment solution, white ink, and coloring ink are applied)

[0324] In the image recording process, after applying a pretreatment liquid to a non-permeable substrate, white ink and coloring ink are applied respectively. The order in which the white ink and coloring ink are applied is not particularly limited; the white ink can be applied after the coloring ink is applied to the non-permeable substrate, or vice versa. When the non-permeable substrate is transparent and is used for back-side printing, it is preferable to apply the pretreatment liquid, coloring ink, and white ink sequentially to the non-permeable substrate. That is, the image recording method of the present invention preferably includes: a step of applying a pretreatment liquid to a non-permeable substrate, followed by applying coloring ink to the non-permeable substrate to which the pretreatment liquid has been applied; and a step of applying white ink to the coloring ink film formed by applying the coloring ink.

[0325] (Conditions for applying pretreatment solution, white ink, and coloring ink)

[0326] In the image recording process, an image is recorded by applying white ink and colored ink under the condition that the area where the pretreatment liquid is applied, the area where white ink is applied, and the area where colored ink is applied overlap in a top view (hereinafter referred to as "overlapping area K").

[0327] In the image recording process, pretreatment liquid, white ink, and coloring ink can be applied to areas that overlap and areas outside the overlapping area, respectively.

[0328] For example, a patterned colored ink film can be formed by patterning colored ink onto a non-permeable substrate to which a pretreatment liquid has been applied. Then, a white ink film is formed by applying white ink to an area spanning the colored ink film and areas outside the colored ink film (e.g., an area covering the colored ink film and its entire periphery) (e.g., a solid area). In this case, the area where the colored ink film exists corresponds to the aforementioned "overlapping area," and the areas where the white ink film exists but the colored ink film is absent, as well as the areas where neither the colored ink film nor the white ink film exists, correspond to the aforementioned "areas outside the overlapping area."

[0329] (The quality imparted by the pretreatment solution, white ink, and coloring ink)

[0330] In the image recording process, it is preferable that the total mass of the first, second, and third organic solvents per unit area in the overlapping region K is 5.5 g / m². 2 Images are recorded under the following conditions. Furthermore, if the pretreatment solution does not contain the third organic solvent, during the image recording process, the total mass of the first and second organic solvents per unit area in the overlapping region K is 5.5 g / m². 2 Record images under the following conditions.

[0331] In the overlapping region K, if the total mass of the first, second, and third organic solvents per unit area is 5.5 g / m² 2 Therefore, when white ink and colored ink are applied to a non-permeable substrate to which a pretreatment solution has been applied, image strength can be ensured, thereby improving the adhesion between the image and the laminating substrate. As a result, excellent lamination strength is achieved.

[0332] Mass of the third organic solvent assigned per unit area in the overlapping region K (in g / m²) 2 It is calculated by multiplying the mass of the pretreatment liquid per unit area in the overlapping region K by the content (mass%) of the third organic solvent relative to the total amount of the pretreatment liquid.

[0333] From the viewpoint of further improving lamination strength, in the overlapping region K, the total mass imparted by the first, second, and third organic solvents per unit area is preferably 5.5 g / m². 2 The following is more preferably 5.0 g / m 2 The following is a further preferred value: 4.5 g / m 2 The following is an example of the lower limit for the total assigned mass: 2.0 g / m³. 2 From the perspective of lamination strength, 3.0 g / m is preferred. 2More preferably 3.5g / m 2 .

[0334] Furthermore, in the image recording process, it is preferable that the mass of the third organic solvent applied per unit area in the overlapping region K is 0.2 g / m². 2 Images were recorded under the following conditions. Additionally, in the case that the pretreatment solution does not contain the third organic solvent, the mass of the third organic solvent imparted per unit area in the overlapping region K is 0 g / m². 2 .

[0335] From the viewpoint of further improving lamination strength, the preferred mass of the third organic solvent in the overlapping region K is 0.08 g / m³. 2 The lower limit of the total assigned mass mentioned above can be 0 g / m³. 2 .

[0336] (Method for applying pretreatment solution)

[0337] There are no particular limitations on the method of applying the pretreatment solution; known methods such as coating, immersion, and inkjet recording can be cited.

[0338] As a coating method, known coating methods include rod coating machines, extrusion coating machines, air knife coating machines, scraper coating machines, bar coating machines, doctor blade coating machines, extrusion coating machines, and reverse roller coating machines.

[0339] The pretreatment liquid can be heated and dried after being applied to a non-permeable substrate. Examples of components for heating and drying the pretreatment liquid include known heating components such as heaters, known air supply components such as dryers, and components combining these.

[0340] Examples of methods for heating and drying pretreatment liquids include heating the non-permeable substrate from the side opposite to the surface to which the pretreatment liquid is applied using a heater, blowing warm air or hot air onto the surface of the non-permeable substrate to which the pretreatment liquid is applied, heating the non-permeable substrate from the surface to which the pretreatment liquid is applied or from the side opposite to the surface to which the pretreatment liquid is applied using an infrared heater, and combining these methods together.

[0341] The heating temperature for heating and drying the pretreatment liquid is preferably 35°C or higher, more preferably 40°C or higher. There is no particular upper limit to the heating temperature, but it is preferably 100°C, more preferably 90°C, and even more preferably 70°C.

[0342] There is no particular limitation on the heating and drying time, but it is preferably 0.5 seconds to 60 seconds, more preferably 0.5 seconds to 20 seconds, and even more preferably 0.5 seconds to 10 seconds.

[0343] [Manufacturing method of laminate]

[0344] According to the image recording method of the present invention, it is possible to manufacture an image recorder having excellent lamination strength and excellent concealment when a laminating substrate is laminated onto the image, having a non-permeable substrate and an image recorded on the non-permeable substrate.

[0345] Therefore, the image recording method of the present invention is suitable for manufacturing a laminate having the above-described image recording object and a laminating substrate laminated on the image recording side of the image recording object.

[0346] A method for manufacturing a laminate according to one aspect of the present invention includes: a step of recording an image on a non-permeable substrate using the image recording method of the present invention; and a step of laminating a laminating substrate onto the side on which the image is recorded to obtain a laminate.

[0347] According to the method for manufacturing a laminate as an aspect of the present invention, it is possible to manufacture a laminate with excellent lamination strength and excellent concealment between an image recorder and a substrate for lamination.

[0348] For the process of recording images, please refer to the image recording method of the present invention described above.

[0349] The process of obtaining a laminate is to laminate a laminating substrate onto the side on which the image is recorded to obtain a laminate.

[0350] The substrate for lamination is preferably a resin substrate. There are no particular limitations on the type of resin substrate; for example, a substrate made of thermoplastic resin can be cited.

[0351] Examples of resin substrates include substrates formed from thermoplastic resin in sheet form.

[0352] The resin substrate preferably contains polypropylene, polyethylene terephthalate, nylon, polyethylene or polyimide.

[0353] The shape of the resin substrate is not particularly limited, but a sheet-like resin substrate is preferred. The thickness of the resin substrate is preferably 10 μm to 200 μm, more preferably 10 μm to 100 μm.

[0354] In the process of obtaining the laminate, the laminating substrate can be directly laminated onto the side on which the image is recorded, or it can be laminated onto the side on which the image is recorded via other layers (e.g., adhesive layers).

[0355] When a laminating substrate is directly laminated onto the side on which the image is recorded, lamination can be performed using known methods such as hot pressing or hot fusion.

[0356] Furthermore, the lamination of the laminating substrate onto the side where the image is recorded via an adhesive layer can be carried out, for example, by applying an adhesive to the side where the image is recorded, placing the laminating substrate, and then bonding the image recorder and the laminating substrate together.

[0357] Furthermore, lamination via adhesive layer on the side where the image is recorded can also be implemented by methods such as extrusion lamination (i.e., sandwich lamination).

[0358] The adhesive layer preferably contains an isocyanate compound. When the adhesive layer contains an isocyanate compound, the adhesion between the adhesive layer and the image is further improved, thus further increasing the lamination strength.

[0359] [Image Records]

[0360] As one aspect of the present invention, the image recording object comprises a non-permeable substrate and an image recorded on the non-permeable substrate. The image includes a white ink layer containing white pigment in contact with the non-permeable substrate and a colored ink layer containing color pigment other than white pigment in contact with the white ink layer. The image also includes an area where the white ink layer and the colored ink layer overlap in a top view. In the white ink layer, the mass of white pigment per unit area is 0.4 g / m². 2 above.

[0361] As an embodiment of the present invention, the image recorder exhibits excellent lamination strength when a laminating substrate is laminated onto an image. Furthermore, the image recorder of the present invention offers excellent concealment.

[0362] The image recording object, as an embodiment of the present invention, is preferably obtained by the image recording method of the present invention. The preferred embodiments of each component in the image recording object, as an embodiment of the present invention, are the same as the preferred embodiments of each component described in the image recording method section of the present invention.

[0363] [Laminate]

[0364] One aspect of the laminate of the present invention comprises: the image recording object of the present invention described above; and a laminating substrate, laminated on the image of the image recording object. The laminate of the present invention exhibits excellent concealment and lamination strength.

[0365] In a laminate as an embodiment of the present invention, the laminating substrate can be directly laminated to the side of the image recorder on which the image is recorded, or it can be laminated to the side of the image recorder on which the image is recorded via other layers (adhesive layers).

[0366] The laminate as an aspect of the present invention is preferably manufactured by a laminate manufacturing method as an aspect of the present invention.

[0367] The preferred methods for the substrate and adhesive layer used in lamination are the same as those described in the section on the manufacturing method of the laminate.

[0368] [Ink Set]

[0369] (Method 1)

[0370] The ink assembly according to one aspect of the present invention comprises: a white ink containing a white pigment, a pigment dispersant, an organic solvent, and water; and a colored ink containing a coloring pigment other than the white pigment, an organic solvent, and water. The pigment dispersant is a polymer or a block polymer having a cross-linked structure. Regarding the white ink and the colored ink, the weighted average solubility parameter of the organic solvent contained in each ink is 28 MPa. 1 / 2 the following.

[0371] (Method 2)

[0372] The ink assembly according to one aspect of the present invention comprises: a white ink containing a white pigment, a pigment dispersant, an organic solvent, and water; and a colored ink containing a colored pigment other than the white pigment and water, wherein the pigment dispersant is a polymer or block polymer having a cross-linked structure, and the organic solvent contains at least one alkylene glycol with a boiling point of 120°C to 200°C and at least one alkylene glycol alkyl ether with a boiling point of 120°C to 200°C.

[0373] (Method 3)

[0374] The ink assembly according to one aspect of the present invention comprises: a white ink containing a white pigment, a pigment dispersant, an organic solvent, and water; and a colored ink containing a colored pigment other than the white pigment and water, wherein the pigment dispersant is a polymer or block polymer having a cross-linked structure, and the organic solvent contains at least one alkylene glycol with a boiling point of 120°C to 200°C and at least two alkylene glycol alkyl ethers with a boiling point of 120°C to 200°C.

[0375] By using the ink group as an aspect of the present invention, image recordings with excellent concealment and lamination strength can be obtained.

[0376] The preferred embodiment of each component in the ink group, as one aspect of the present invention, is the same as the preferred embodiment of each component described in the image recording method section of the present invention.

[0377] Example

[0378] The present invention will be described in more detail below through embodiments, but the present invention is not limited to the following embodiments as long as it does not depart from its spirit.

[0379] -White pigment dispersion A (dispersion using random polymers)-

[0380] 965 g of dipropylene glycol was added to a 5000 mL three-necked flask equipped with a stirrer and a cooling tube, and the mixture was heated to 85 °C under a nitrogen atmosphere. Solution I, obtained by dissolving 640 g of benzyl methacrylate, 340 g of methacrylic acid, and 19.94 g of 2-mercaptopropionic acid in 370.28 g of dipropylene glycol, and Solution II, obtained by dissolving 17.69 g of tert-butyl peroxy-2-ethylhexanoate (product name "PERBUTYL O", manufactured by NOF CORPORATION) in 221.17 g of dipropylene glycol, were prepared. Solution I was added dropwise to the above three-necked flask over 4 hours, and Solution II was added dropwise over 5 hours. After the addition was completed, the mixture was allowed to react for an additional 2 hours. 1 ¹H-NMR confirmed the disappearance of the monomer. The resulting reaction solution was heated to 70°C, and 248.02 g of 50% (w / w) potassium hydroxide aqueous solution was added, followed by the addition of 107.48 g of dipropylene glycol and 75.52 g of pure water. The mixture was stirred to obtain a 37% (w / w) solution of the random polymer. This random polymer was used as pigment dispersant P1. 1 ¹H-NMR confirmed the structural units constituting the obtained random polymer. Furthermore, the weight-average molecular weight (Mw) was determined by GPC. The obtained pigment dispersant P1 had a weight-average molecular weight (Mw) of 8400 and an acid value of 221.7 mg KOH / g.

[0381] 150 parts by mass of pigment dispersant P1 were dissolved in water to prepare a polymer aqueous solution with a pigment dispersant P1 concentration of approximately 25% by mass. 96 parts by mass of the polymer aqueous solution, 300 parts by mass of CI pigment white 6 (trade name "JR-405", titanium dioxide, manufactured by TAYCA Co., Ltd.), and 270 parts by mass of water were mixed to obtain a mixture. Potassium hydroxide aqueous solution was added to the obtained mixture to adjust the neutralized pH to 8.7. The pH value was measured at 25°C using a pH meter (model: WM-50EG, manufactured by DKK-TOA CORPORATION). The neutralized mixture was then dispersed for 3 hours using a bead mill (bead diameter: 0.1 mm φ, zirconia beads). This yielded a white pigment dispersion A (uncrosslinked dispersion) with white pigment dispersed by pigment dispersant P1. The pigment concentration of the uncrosslinked dispersion was 45% by mass, and the pigment dispersant P1 concentration was 3.6% by mass.

[0382] -White pigment dispersion B (dispersion using cross-linked polymers)-

[0383] A mixture was prepared by mixing 180 parts by mass of a polymer aqueous solution containing approximately 25% by mass of pigment dispersant P1, 300 parts by mass of CI pigment white 6 (trade name "JR-405", titanium dioxide, manufactured by TAYCA Co., Ltd.) as a white pigment, and 180 parts by mass of water. A potassium hydroxide aqueous solution was added to the resulting mixture to adjust the pH to 8.7 after neutralization. The pH was measured at 25°C using a pH meter (model: WM-50EG, manufactured by DKK-TOA CORPORATION). The neutralized mixture was then dispersed for 3 hours using a bead mill (bead diameter: 0.1 mm φ, zirconia beads). This yielded a white pigment dispersion precursor B (uncrosslinked dispersion) dispersed in pigment dispersant P1. The pigment concentration of dispersion precursor B was 45% by mass.

[0384] 136 parts by mass of the white pigment dispersion precursor B (uncrosslinked dispersion) were reacted with 2.70 parts by mass of trimethylolpropane polyglycidyl ether (product name "Denacol EX-321", manufactured by Nagase ChemteX Corporation) as a crosslinking agent and 29.5 parts by mass of an aqueous boric acid solution (boric acid concentration: 4% by mass) at 70°C for 6 hours, followed by cooling to 25°C. This yielded a white pigment dispersion (crosslinked dispersion) in which pigment dispersant P1 was crosslinked and the white pigment was dispersed by pigment dispersant P1a. Pigment dispersant P1a is a polymer crosslinked by pigment dispersant P1 through a crosslinking agent. Deionized water was added to the crosslinked dispersion to bring the pigment concentration to 15% by mass. The crosslinked dispersion was then subjected to ultrafiltration at a flow rate of 600 mL per minute through an ultrafiltration apparatus (cross-flow ultrafiltration (UF), manufactured by Sartorius Corporation) equipped with a polyethersulfone (PESU) membrane (micropore size: 0.1 μm). At this point, the liquid temperature was adjusted to 25°C, and ultrafiltration was performed eight times, with each cycle consisting of one times the volume ratio of the added liquid. Deionized water was added to bring the pigment concentration to 45% by mass. This yielded white pigment dispersion B. The acid value of the pigment dispersant P1a (crosslinked polymer) contained in white pigment dispersion B was 105 mg KOH / g. Furthermore, the concentration of pigment dispersant P1a was 3.6% by mass. The concentration of pigment dispersant P1a was obtained by subtracting the pigment concentration from the solid component concentration obtained from vacuum drying of pigment dispersion B.

[0385] -White pigment dispersion C (dispersion using block polymers)-

[0386] Referring to Synthesis Example 8 of Japanese Patent Application Publication No. 2015-83688, a block polymer was synthesized as a pigment dispersant. Details are shown below.

[0387] A reaction apparatus equipped with a 1L separable flask containing a stirrer, reflux condenser, thermometer, and nitrogen inlet pipe was added with 266 parts by mass of diethylene glycol dimethyl ether, 6.2 parts by mass of 2-iodo-2-cyanopropane, 120 parts by mass of methyl methacrylate (MMA), 28.8 parts by mass of acrylic acid (AA), 67.2 parts by mass of cyclohexyl methacrylate (CHMA), 7.9 parts by mass of azobis(dimethyl)isovalerate, and 0.7 parts by mass of 2-tert-butyl-4,6-dimethylphenol. The mixture was stirred while nitrogen was flowing through it. The temperature of the mixture in the reaction apparatus (reaction temperature) was then raised to 70°C, and polymerization was carried out for 3 hours to obtain polymerization solution A containing the MMA / AA / CHMA copolymer. After 3 hours, a portion of the polymerization solution A was sampled, and the solid content was determined to be 42.0% by mass, confirming that most of the monomers had polymerized. Furthermore, the weight-average molecular weight (Mw) of the MMA / AA / CHMA copolymer, determined by GPC, was 7,500. The acid value of this MMA / AA / CHMA copolymer was 101.0 mg KOH / g.

[0388] Next, a mixture of benzyl methacrylate (BzMA) (35.2 parts by mass) and V-65 (oil-soluble azo polymerization initiator, 2,2'-azobis(2,4-dimethylpentanonitrile), manufactured by FUJIFI LM Wako Pure Chemical Corporation) (0.3 parts by mass) was added to the above polymerization solution A, and they were polymerized at 70°C for 3 hours to obtain polymerization solution B containing block polymers. The obtained block polymers were block polymers containing block A (MMA / AA / CHMA copolymer) and block B (BzMA homopolymer). The solids content of polymerization solution B was determined to be 43.2% by mass, confirming that most of the monomers had polymerized. The Mw of the block polymer was 8,500, and the acid value was 89.3 mg KOH / g.

[0389] 136.4 parts by weight of the resulting block polymer, 163.6 parts by weight of butylcarbitol, and 450 parts by weight of CI Pigment White 6 (trade name "JR-405", titanium dioxide, manufactured by TAYCA Co., Ltd.) as a white pigment were mixed and stirred using a disperser. Next, 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 mPa·s. Then, while stirring 700 parts by weight of the above oily pigment dispersion using a disperser, a mixture consisting of 4.0 parts by weight of potassium hydroxide and 341 parts by weight of water was slowly added to neutralize and induce phase transfer. Finally, the white pigment was fully dispersed using a horizontal media disperser to obtain a pigment dispersion.

[0390] Next, the obtained pigment dispersion was ultrafiltered using an ultrafiltration apparatus (cross-flow ultrafiltration (UF), manufactured by Sartorius) with deionized water flowing through it at a flow rate of 600 mL per minute. The liquid temperature was maintained at 25°C, and ultrafiltration was performed eight times, with each ultrafiltration cycle consisting of one volume of liquid added. After adding deionized water, a white pigment dispersion C was obtained with a pigment concentration of 45% by mass and a pigment dispersant (block polymer) concentration of 3.6% by mass. The block polymer concentration was calculated by subtracting the pigment concentration from the solids concentration obtained from vacuum drying of pigment dispersion C.

[0391] -White pigment dispersion D (self-dispersible)-

[0392] 100 g of titanium dioxide (number-average primary particle size: ≥130 nm and ≤350 nm, median: 240 nm) was added to 3000 mL of sodium hypochlorite solution with a specified concentration of 2.5, and the mixture was stirred at 300 rpm for 10 hours at 60 °C. This oxidation treatment yielded a reaction solution containing a white pigment with carboxyl groups on the surface of the titanium dioxide. The filtered reaction solution was neutralized with sodium hydroxide solution, followed by ultrafiltration. Then, ultrafiltration using deionized water via a dialysis membrane was performed, followed by ultrasonic dispersion using an ultrasonic disperser to obtain a white pigment dispersion D with a pigment concentration of 45% by mass.

[0393] -Preparation of white inks W1 to W31-

[0394] In white inks W1 to W29 and W31, any one of the white pigment dispersions A to C mentioned above, along with an organic solvent, resin particles, and water, are mixed to prepare white inks in the manner described in Tables 1 to 3 (mass %). In Tables 1 to 3, white pigment dispersion A was used in the example where the dispersant was a random polymer, white pigment dispersion B was used in the example where the dispersant was a crosslinking polymer, and white pigment dispersion C was used in the example where the dispersant was a block polymer.

[0395] In white ink W30, white pigment dispersion D, organic solvent, resin particles, and water are mixed to prepare the white ink in the manner described in Table 3.

[0396] In addition, the water content is such that the white ink as a whole is 100% by mass.

[0397] The abbreviations for each organic solvent in the table are as follows.

[0398] PGmME: Propylene Glycol Monomethyl Ether

[0399] PGmEE: Propylene Glycol Monoethyl Ether

[0400] PGmPE: Propylene Glycol Monopropyl Ether

[0401] PGmBE: Propylene Glycol Monobutyl Ether

[0402] EGmPE: Ethylene glycol monopropyl ether

[0403] EGmBE: Ethylene glycol monobutyl ether

[0404] PG: Propylene Glycol

[0405] DPGmME: Dipropylene glycol monomethyl ether

[0406] DEGmEE: Diethylene glycol monoethyl ether

[0407] EG: Ethylene glycol

[0408] DEGmBE: Diethylene glycol monobutyl ether

[0409] DPG: Dipropylene glycol

[0410] 1,2-HD: 1,2-Hexanediol

[0411] DEG: Diethylene glycol

[0412] TEG: Triethylene Glycol

[0413] The resin particles are produced by the following method.

[0414] 560.0 g of methyl ethyl ketone was charged into a 2-liter three-necked flask (reaction vessel) equipped with a stirrer, thermometer, reflux cooling tube, and nitrogen inlet tube, and the temperature was raised to 87°C. Then, while maintaining the reflux state in the reaction vessel, a mixed solution consisting of 220.4 g of methyl methacrylate, 301.6 g of isobornyl methacrylate, 58.0 g of methacrylic acid, 108 g of methyl ethyl ketone, and 2.32 g of dimethyl 2,2'-azobis(2-methylpropionic acid) (product name "V-601", manufactured by FUJIFILM Wako Pure Chemical Corporation) as a polymerization initiator was added dropwise over 2 hours. The reflux state was maintained until the reaction was completed. After the addition was completed, the mixture was stirred for 1 hour, and then the reaction solution was subjected to the following procedure (1).

[0415] Step (1)... A solution consisting of 1.16g of "V-601" and 6.4g of methyl ethyl ketone was added and stirred for 2 hours.

[0416] Next, the above process (1) was repeated 4 times. Then, a solution consisting of 1.16g of “V-601” and 6.4g of methyl ethyl ketone was added and stirred for 3 hours.

[0417] After the reaction was completed, the temperature of the solution was lowered to 65°C, 163.0 g of isopropanol was added, and the solution was allowed to cool naturally to obtain a polymerization solution containing the copolymer (solid component concentration 41.0% by mass).

[0418] Next, 317.3 g of the obtained polymerization solution was weighed, and 46.4 g of isopropanol, 1.65 g of 20% maleic anhydride aqueous solution (equivalent to 0.3% by mass relative to the copolymer as maleic acid) and 40.77 g of 2 mol / L sodium hydroxide aqueous solution were added to raise the temperature of the liquid in the reaction vessel to 70°C.

[0419] Next, 380 g of distilled water was added dropwise to the liquid heated to 70 °C at a rate of 10 mL / min. Then, under reduced pressure, the temperature of the liquid in the reaction vessel was maintained at 70 °C for 1.5 hours, thereby distilling away a total of 287.0 g of isopropanol, methyl ethyl ketone, and distilled water. 0.278 g of PROXEL GX L(S) (manufactured by Arch Chemicals Japan, Inc.) (440 ppm relative to the polymer solids content as benzisothiazolin-3-one) was added to the resulting liquid.

[0420] The obtained liquid was filtered through a 1 μm filter, and the filtrate was recovered, thereby obtaining an aqueous dispersion (solids concentration 23.2% by mass) of resin particles A, which is a copolymer of methyl methacrylate / isoborneol methacrylate / methacrylic acid (=70 / 20 / 10 [mass ratio]). 50% by mass of the methacrylic acid-derived structural units constituting the resin are sodium methacrylate. The volume average particle size of resin particles A is 5.0 nm, and the weight average molecular weight (Mw) is 60,000.

[0421] In Tables 1 to 3, Organic Solvent A represents organic solvents with boiling points of 120°C to 200°C contained in white ink, Organic Solvent B represents organic solvents with boiling points exceeding 200°C but below 240°C, and Organic Solvent C represents organic solvents with boiling points exceeding 240°C.

[0422] [Table 1]

[0423]

[0424] [Table 2]

[0425]

[0426] [Table 3]

[0427]

[0428] <Preparation of Coloring Inks>

[0429] The following pigment dispersions were prepared as cyan, magenta, yellow, and black pigment dispersions. These pigment dispersions are dispersions of pigments of each color dispersed by cross-linked polymers.

[0430] • Cyan pigment dispersion…Product name: “APD3000Cyan (pigment concentration 14.0% by mass)”, manufactured by FUJIFILMImaging Colorants, Inc.

[0431] • Magenta pigment dispersion…Product name: “APD3000Magenta (pigment concentration 14.0% by mass)”, manufactured by FUJIFILM Imaging Colorants, Inc.

[0432] • Yellow pigment dispersion…Product name: “APD3000 Yellow (pigment concentration 10.0% by mass)”, manufactured by FUJIFILMImaging Colorants, Inc.

[0433] • Black pigment dispersion… (Product name “APD3000Black (pigment concentration 10.0% by mass)”, manufactured by FUJIFILMImaging Colorants, Inc.)

[0434] -Preparation of Cyan Ink C1~C6-

[0435] Cyan inks C1 to C6 are prepared by mixing the above-mentioned cyan pigment dispersion with organic solvent, resin particles and water, so that the content of each component is as shown in Table 4 (mass %).

[0436] In addition, the concentration of the crosslinked polymer used as a pigment dispersant is the value obtained by subtracting the pigment concentration from the concentration of the solid components obtained from drying each pigment dispersion under reduced pressure.

[0437] Preparation of magenta ink M1, yellow ink Y1 and black ink Bk1-

[0438] Magenta ink M1 is prepared by mixing the above-mentioned magenta pigment dispersion with organic solvent, resin particles and water, so that the content of each component is as recorded in Table 5 (mass %).

[0439] In yellow ink Y1, the above-mentioned yellow pigment dispersion, organic solvent, resin particles and water are mixed to prepare the yellow ink in such a way that the content of each component is as recorded in Table 5 (mass %).

[0440] In black ink Bk1, the above-mentioned black pigment dispersion, organic solvent, resin particles and water are mixed to prepare the black ink in such a way that the content of each component is as recorded in Table 5 (mass %).

[0441] In addition, the water content is such that the total amount of each coloring ink is 100% by mass.

[0442] In Tables 4 and 5, the second organic solvent A represents the organic solvent with a boiling point of 120℃ to 200℃ contained in the coloring ink.

[0443] [Table 4]

[0444]

[0445] [Table 5]

[0446]

[0447] <Preparation of Pretreatment Solution>

[0448] The following components are mixed to the following concentrations to prepare pretreatment solutions T1 and T2.

[0449] -Pretreatment solution T1-

[0450] • Flocculant: malonic acid…5% by mass

[0451] Surfactant: Sodium dodecylbenzenesulfonate (hard type), manufactured by Tokyo Chemical Industry Co., Ltd… 1% by mass

[0452] Water… makes the pretreatment solution a total of 100% by mass.

[0453] -Pretreatment solution T2-

[0454] • Flocculant: malonic acid…5% by mass

[0455] • Third organic solvent: Propylene glycol (boiling point 188℃)…5% by mass

[0456] Surfactant: Sodium dodecylbenzenesulfonate (hard type), manufactured by Tokyo Chemical Industry Co., Ltd… 1% by mass

[0457] Water… makes the pretreatment solution a total of 100% by mass.

[0458] [Image Recording]

[0459] As a non-permeable substrate (hereinafter, also referred to as the "substrate"), a polyethylene terephthalate (PET) substrate (product name "FE2001", manufactured by FUTAMURA CHEMICAL CO.,LTD., thickness 12μm, width 100mm, length 200mm) was prepared.

[0460] An image recording apparatus is provided, which includes a transport mechanism for transporting a substrate, and, upstream of the substrate transport direction, a bar coater for applying pretreatment liquid, a first inkjet head for applying coloring ink, and a second inkjet head for applying white ink. Furthermore, when applying two or more coloring inks, the number of inkjet heads is increased according to the amount of coloring ink applied.

[0461] Both the first and second inkjet heads are piezoelectric full-line inkjet heads with a width of 1200 dpi / 20 inch. Here, dpi is an abbreviation for dots per inch.

[0462] Both the first and second inkjet heads are arranged in a row inkjet head configuration with the inkjet heads arranged in a direction orthogonal to the transport direction of the substrate (i.e., the width direction of the substrate).

[0463] The Samba G3L (manufactured by FUJIFILM Dimatix, Inc.) was used for each of the above inkjet heads.

[0464] The aforementioned substrate, pretreatment liquid, white ink, and coloring ink were disposed on the aforementioned image recording apparatus. Under conditions where the areas where the pretreatment liquid, white ink, and coloring ink were applied overlapped in a top view, the pretreatment liquid, white ink, and coloring ink were respectively applied to the substrate, and an image was recorded. Thus, an image recording object was obtained. Furthermore, in Example 33, without using a pretreatment liquid, the aforementioned substrate, white ink, and coloring ink were disposed on the aforementioned image recording apparatus. Under conditions where the areas where the white ink and coloring ink were applied overlapped in a top view, white ink and coloring ink were respectively applied to the substrate, and an image was recorded.

[0465] The following details the image recording method when applying the pretreatment solution. Additionally, Example 34 does not include the step of applying the pretreatment solution; otherwise, it is the same as the image recording method when applying the pretreatment solution.

[0466] While the substrate was moved at a constant speed of 500 mm / s, a pretreatment solution was applied to the substrate using a wire bar coater. The amount of pretreatment solution applied was set as shown in Tables 6 to 9 (unit: g / m³). 2 ).

[0467] The mass of the pretreatment solution is the value obtained by dividing the mass of the pretreatment solution by the area of ​​the region to which the pretreatment solution is applied.

[0468] The mass of the third organic solvent is determined based on the mass of the pretreatment solution (unit: g / m³). 2 The value is calculated from the content (mass%) of the third organic solvent relative to the total amount of the pretreatment liquid.

[0469] At the point where the pretreatment solution application is completed, drying of the pretreatment solution begins using a dryer at 50°C 1.5 seconds after the application is finished, and ends 3.5 seconds after the application is finished. The total drying time is 2 seconds.

[0470] While the substrate, having finished drying the pretreatment solution, is moved at a constant stage speed of 50 mm / s, colored ink is sprayed from the first inkjet head onto the dried pretreatment solution to create a solid image, and white ink is sprayed from the second inkjet head onto the applied colored ink. At this time, the entire colored ink applied to the substrate is coated with white ink. The overlapping areas in the embodiments and comparative examples correspond to the areas coated with colored ink and the areas coated with white ink, respectively.

[0471] Next, the colored ink and white ink were dried at 70°C for 10 seconds.

[0472] Thus, a solid image is obtained having a laminated structure in which a white ink film is stacked on top of a colored ink film. That is, an image recorder having a substrate and the aforementioned solid image disposed on the substrate is obtained.

[0473] Here, the spraying conditions for both colored and white inks are set to a spraying frequency of 24kHz and a resolution of 1200dpi×1200dpi (dots per inch).

[0474] The droplet amounts of the colored ink and white ink were adjusted according to the respective amounts of colored ink and white ink applied. The results are shown in Tables 6-9.

[0475] For example, in Example 1, the droplet size of the coloring ink was set to 4.0 nanograms (corresponding to a given mass of 8.94 g / m³ for the coloring ink). 2 The droplet size of the white ink was set to 3.4 nanograms (corresponding to a given mass of 7.59 g / m³ of white ink). 2 ).

[0476] Both the coloring ink and the white ink were degassed by a degassing filter and the temperature was adjusted to 30°C.

[0477] The quality of the coloring ink is the value obtained by dividing the mass of the coloring ink applied to the overlapping area by the area of ​​the overlapping area.

[0478] The mass of the second organic solvent is determined based on the mass of the coloring ink (unit: g / m³). 2 The value is calculated from the content (mass%) of the second organic solvent relative to the total amount of the coloring ink.

[0479] The quality of the white ink is the value obtained by dividing the mass of the white ink applied to the overlapping area by the area of ​​the overlapping area.

[0480] The mass of the first organic solvent is based on the mass of the white ink (unit: g / m). 2 The value is calculated from the content (mass%) of the first organic solvent relative to the total amount of white ink.

[0481] The applied mass of white pigment is based on the applied mass of white ink (unit: g / m). 2 The value is calculated from the content (mass%) of white pigment relative to the total amount of white ink.

[0482] In addition, the values ​​calculated as described above are calculated as follows: the values ​​are calculated using a value that is one place larger than the value recorded in the table, and the significant digits are rounded.

[0483] In Tables 6-9, the "G / A" in the coloring ink column indicates the mass ratio of the alkylene glycol content to the alkylene glycol alkyl ether content in the coloring ink. Similarly, the "G / A" in the white ink column indicates the mass ratio of the alkylene glycol content to the alkylene glycol alkyl ether content in the white ink. Furthermore, the "Type of Alkylene Glycol Alkyl Ether" in the white ink column indicates the quantity of each type of alkylene glycol alkyl ether contained in the white ink.

[0484] [evaluate]

[0485] The lamination strength, concealment, and adhesion of the image recordings, as well as the re-spraying and spraying properties of the white ink, were evaluated for each embodiment and comparative example. The evaluation methods are as follows. The evaluation results are shown in Tables 6 to 9.

[0486] -Lamination strength-

[0487] Images were recorded using the method described in the image recording section above, resulting in image recordings. These image recordings were used as samples for evaluating lamination strength. After image recording, within 60 minutes, a dry lamination adhesive (main agent TM-320 (isocyanate compound) / curing agent CAT-13B (alcohol compound), manufactured by Toyo-Morton, Ltd.) was applied using a bar coater and dried at 70°C for 10 seconds. An unstretched polypropylene (CPP) film (trade name: PYLEN P1128, manufactured by TOYO BO CO.,LTD., thickness 25 μm) was overlapped on the dried adhesive as a lamination substrate. In this state, the lamination substrate and the lamination strength evaluation sample were bonded together to obtain a laminate. The resulting laminate was aged at 40°C for 48 hours.

[0488] A sample sheet measuring 100 mm in length and 15 mm in width was cut from the aged laminate. Then, the laminating substrate and the lamination strength evaluation sample were manually peeled off from one end of the sample sheet to a length of 30 mm. For the remaining 70 mm length, the laminating substrate and the lamination strength evaluation sample were kept bonded together.

[0489] Next, a tensile test was performed on the laminate substrate and the laminate strength evaluation sample of the peeled portion of the sample sheet, which were stretched in opposite directions. The direction of stretching was set perpendicular to the remaining 70 mm length of the area (the area where the laminate substrate and the laminate strength evaluation sample were bonded together).

[0490] This tensile test is used to determine the peel strength of the substrate and the laminate used to peel the remaining 70mm length of the aforementioned region, and the peel strength is taken as the laminate strength. The evaluation criteria are as follows.

[0491] AA: The lamination strength between the image recording material and the laminating substrate is 1.5 N / 15 mm or more.

[0492] A: The lamination strength between the image recording material and the laminating substrate is greater than 1 N / 15 mm and less than 1.5 N / 15 mm.

[0493] B: The lamination strength between the image recording material and the laminating substrate is 0.5 N / 15 mm or more and less than 1 N / 15 mm.

[0494] C: The lamination strength between the image recording material and the substrate for lamination is less than 0.5 N / 15 mm.

[0495] -Concealment-

[0496] Images were recorded using the method described in the image recording section above, resulting in image recordings. The resulting recordings were then stacked on test paper with the substrate side down. The white background of the masking rate test paper (standard: JIS K-5600, manufactured by TP Giken Co., Ltd.) was used as the test paper. The optical density (OD value) of the overlapping area of ​​the colored ink film and the white ink film was measured from the white solid image side of the obtained image recordings using a spectrophotometer (product name "X-Rite eXact (measurement diameter: 2mm, light source: D50, observer field of view: 2° field of view, density status: StatusT)", manufactured by Videojet X-Rite KK). Masking performance was evaluated based on the optical density (OD value). The evaluation criteria are as follows.

[0497] AA: OD value less than 0.70

[0498] A: OD value is above 0.70 and below 0.85

[0499] B: OD value greater than 0.85 and less than 1.00

[0500] C: OD value is 1.00 or higher.

[0501] -Adhesion-

[0502] An image record was obtained by recording an image using the method described in the image recording section above. After recording an image on a solid image in the obtained image record, a sheet of transparent tape (registered trademark, No. 405, manufactured by NICHIBAN Co., Ltd., 12 mm wide, hereinafter referred to as "tape") was applied within 30 minutes ± 1 minute, and then the tape was peeled off, thereby evaluating the adhesion of the image.

[0503] Specifically, the application and removal of the tape are carried out using the following methods.

[0504] Remove the tape at a constant speed and cut it into pieces approximately 75mm in length to obtain tape sheets.

[0505] Overlay the obtained tape sheet onto the solid image, and use your finger to stick the tape sheet to the central area, which is 12mm wide and 25mm long, and rub it vigorously with your fingertip.

[0506] Within 5 minutes of applying the tape, grasp the end of the tape and peel it off at an angle as close to 60° as possible for 0.5 to 1.0 seconds.

[0507] The peeled-off tape was visually inspected for any adhering substances and image peeling. The evaluation criteria are as follows.

[0508] AA: There is no residue on the tape and no image peeling.

[0509] A: There are some colored residues on the tape, but no image has been peeled off.

[0510] B: There are some colored residues on the tape and some image peeling, but the peeled area is less than 30% of the image area.

[0511] C: The tape has colored residue and image peeling, with the peeled area exceeding 30% of the image area.

[0512] -Re-spraying properties of white ink after printing has stopped-

[0513] After recording the image using the above image recording method, the inkjet head was stopped for 1 minute under conditions of 25°C and 50% humidity. After 1 minute, the mass assigned per unit area per single pass was 4.47 g / m². 2 Under certain conditions, white ink was sprayed onto a substrate, and solid images were recorded. Within the obtained solid images, the portion recorded immediately after the start of spraying was observed using a microscope, and the deviation width of the droplet position was measured. The evaluation criteria are as follows.

[0514] AA: The dripping position was not deviated.

[0515] A: The deviation width of the dripping position is less than 0.5mm.

[0516] B: The deviation of the drop position from the width of the droplet exceeds 0.5mm but is less than 1.0mm.

[0517] C: The deviation of the drop position from the width exceeds 1.0 mm.

[0518] -Sprayability of white ink-

[0519] The mass assigned per unit area per single pass is 4.47 g / m². 2 Under the specified conditions, white ink was sprayed onto the substrate to record a solid image. The condition of the obtained solid image was visually verified. The evaluation criteria are as follows.

[0520] AA: No stripes

[0521] A: There is one light-colored stripe.

[0522] B: There are 2 to 4 light-colored stripes.

[0523] C: There are 5 or more light-colored stripes or dark-colored stripes.

[0524] [Table 6]

[0525]

[0526] [Table 7]

[0527]

[0528] [Table 8]

[0529]

[0530] [Table 9]

[0531]

[0532] As shown in Tables 6 to 9, in Examples 1 to 39, the process includes a step of preparing a white ink containing a white pigment, a first organic solvent, and water; a step of preparing a colored ink containing a coloring pigment other than white pigment, a second organic solvent, and water; and a step of applying the white ink and the colored ink to a non-permeable substrate to record an image. In the image recording step, in the area where the white ink and the colored ink are applied, which overlap in a top view, the total mass of the first and second organic solvents applied per unit area is 5.5 g / m². 2 The following applies to white pigment with a mass of 0.4 g / m² per unit area. 2 Under the above conditions, images can be recorded with excellent lamination strength and concealment.

[0533] On the other hand, it can be seen that in Comparative Example 1, in the area where the white ink and the colored ink overlap when viewed from above, the total mass of the first and second organic solvents applied per unit area exceeds 5.5 g / m². 2 The resulting image recordings have poor lamination strength.

[0534] It can be seen that, in Comparative Example 2, in the area where the white ink and the colored ink overlap when viewed from above, the mass of white pigment applied per unit area is less than 0.4 g / m². 2 The resulting image records are poorly concealed.

[0535] It is known that in Example 6, the content of the first organic solvent is less than 30% by mass relative to the total mass of the white ink, and the content of the second organic solvent is less than 30% by mass relative to the total mass of the coloring ink, thus an image recorder with superior lamination strength compared to Example 5 can be obtained.

[0536] As can be seen, in Example 13, after applying a pretreatment liquid to a non-permeable substrate, white ink and colored ink are applied to record images, thus obtaining image recordings with superior lamination strength, concealment, and adhesion compared to Example 34.

[0537] It is known that in Examples 13 and 15, the pigment dispersants contained in the white ink are crosslinked polymers or block polymers, respectively. Therefore, image recordings with superior lamination strength, concealment and adhesion compared to Example 30 can be obtained, and image recordings with superior jetting properties and lamination strength compared to Example 31 can also be obtained.

[0538] As can be seen, in Example 14, the weighted average solubility parameter of the organic solvent contained in the white ink and the colored ink is 28 MPa. 1 / 2 Therefore, an image recorder with superior lamination strength and adhesion compared to Example 23 can be obtained.

[0539] It is known that in Example 8, the proportion of the first organic solvent A in the organic solvent contained in the white ink is more than 50% by mass, and the first organic solvent A contains at least one alkylene glycol and at least one alkylene glycol alkyl ether. Therefore, an image recorder with superior lamination strength and adhesion compared to Example 9 can be obtained.

[0540] Furthermore, it is known that in Example 12, the first organic solvent A contains at least one alkylene glycol and at least two alkylene glycol alkyl ethers, thus obtaining an image recorder with superior lamination strength compared to Example 8.

[0541] Furthermore, it is known that in Example 8, the mass ratio of the content of alkylene glycol to the content of alkylene glycol alkyl ether is 15.0 or less, thus an image recorder with superior lamination strength and adhesion compared to Example 10 can be obtained.

[0542] It is known that in Example 4, the proportion of the second organic solvent A in the organic solvent contained in the coloring ink is more than 50% by mass, and the second organic solvent A contains at least one alkylene glycol and at least one alkylene glycol alkyl ether. Therefore, an image recorder with superior lamination strength compared to Example 38 can be obtained.

[0543] <Example 101, Example 102>

[0544] The four colors of ink listed in Table 10 were used as coloring inks, and image recordings were obtained using the same method as in Example 1. Details of the magenta, yellow, and black inks are described in Table 5.

[0545] The mass of the pretreatment solution is set as shown in Table 10 (unit: g / m³). 2 ).

[0546] After applying the pretreatment liquid to the substrate, cyan ink, magenta ink, yellow ink, black ink, and white ink were sequentially sprayed. At this point, the entire coloring ink applied to the substrate was coated with white ink.

[0547] The mass of each coloring ink and white ink is set as shown in Table 10 (unit: g / m). 2 ).

[0548] Examples 101 and 102 were evaluated in the same way as in Example 1. The evaluation results are shown in Table 10.

[0549] [Table 10]

[0550]

[0551] As shown in Table 10, it can be seen that in Examples 101 and 102, which use four different colored inks, image recordings with excellent lamination strength and concealment can be obtained in the same way as when using one colored ink.

Claims

1. An image recording method comprising: a step of preparing a white ink containing a white pigment, a first organic solvent having a boiling point of 120°C or higher, and water; a step of preparing a colored ink containing a coloring pigment other than the white pigment, a second organic solvent having a boiling point of 120°C or higher, and water; and a step of recording an image by imparting the white ink and the colored ink on a non-penetrable substrate, respectively, In the process of recording the image, the total amount of the first organic solvent and the second organic solvent per unit area in a region in which the region to which the white ink is applied and the region to which the colored ink is applied overlap in plan view is 5.5 g / m 2 The amount of the white pigment applied per unit area is 0.4 g / m 2 The image is recorded under the above conditions, the first organic solvent contains a first organic solvent A having a boiling point of 120°C to 200°C, and the proportion of the first organic solvent A in all the organic solvents contained in the white ink is 95% by mass or more, the first organic solvent A contains at least one alkylene glycol and at least one alkylene glycol alkyl ether, the mass ratio of the content of the alkylene glycol to the content of the alkylene glycol alkyl ether is 15.0 or less.

2. The image recording method according to claim 1, wherein the content of the first organic solvent is 30% by mass or less with respect to the total mass of the white ink, and the content of the second organic solvent is 30% by mass or less with respect to the total mass of the colored ink.

3. The image recording method according to claim 1, wherein, further comprising a step of preparing a pretreatment liquid containing a coagulant and water, in the step of recording an image, after imparting the pretreatment liquid on the non-penetrable substrate, the white ink and the colored ink are imparted to record the image, respectively.

4. The image recording method according to claim 3, wherein the pretreatment liquid does not contain a third organic solvent having a boiling point of 120°C or higher, or in the case of containing a third organic solvent having a boiling point of 120°C or higher, the content of the third organic solvent having a boiling point of 120°C or higher is 15% by mass or less with respect to the total amount of the pretreatment liquid.

5. The image recording method according to claim 4, wherein In the process of recording the image, the total amount of the first organic solvent, the second organic solvent, and the third organic solvent applied per unit area in a region in which the region to which the pretreatment liquid is applied, the region to which the white ink is applied, and the region to which the colored ink is applied overlap in plan view is 5.5 g / m2or more. 2 The image was recorded under the following conditions.

6. The image recording method according to claim 4 or 5, wherein In the process of recording the image, the imparted mass of the third organic solvent per unit area in a region in which the region to which the pretreatment liquid is imparted, the region to which the white ink is imparted, and the region to which the colored ink is imparted overlap in plan view becomes 0.2 g / m 2 The image was recorded under the following conditions.

7. The image recording method according to any one of claims 1 to 5, wherein the white ink further contains a pigment dispersant, the pigment dispersant is a polymer or a block polymer having a crosslinked structure.

8. The image recording method according to any one of claims 1 to 5, wherein The weighted average of the solubility parameters of the organic solvents contained in each of the white ink and the colored ink is 28 MPa 1 / 2 The following.

9. The image recording method according to any one of claims 1 to 5, wherein the first organic solvent A contains at least one alkylene glycol and at least two alkylene glycol alkyl ethers.

10. The image recording method according to any one of claims 1 to 5, wherein the second organic solvent contains a second organic solvent A having a boiling point of 120°C to 200°C, and the proportion of the second organic solvent A in all the organic solvents contained in the colored ink is 50% by mass or more, the second organic solvent A contains at least one alkylene glycol and at least one alkylene glycol alkyl ether.

11. A method for manufacturing a laminate comprising: a step of recording an image on a non-penetrable substrate using the image recording method according to any one of claims 1 to 10; and a step of laminating a lamination substrate on the side of the non-penetrable substrate on which the image is recorded to obtain a laminate.

12. An image recorded matter formed using the image recording method according to any one of claims 1 to 10, comprising a non-penetrable substrate and an image recorded on the non-penetrable substrate, the image comprising a white ink layer in contact with the non-penetrable substrate and containing a white pigment, and a colored ink layer in contact with the white ink layer and containing a coloring pigment other than the white pigment, and comprising a region in which the white ink layer and the colored ink layer overlap in plan view, The mass of the white pigment per unit area in the white ink layer is 0.4 g / m2or more. 2 The above.

13. An image recorded matter formed using the image recording method according to any one of claims 1 to 10, comprising a non-penetrable substrate and an image recorded on the non-penetrable substrate, the image comprising a pretreatment liquid layer in contact with the non-penetrable substrate and containing a coagulant, a white ink layer in contact with the pretreatment liquid layer and containing a white pigment, and a colored ink layer in contact with the white ink layer and containing a coloring pigment other than the white pigment, and comprising a region in which the pretreatment liquid layer, the white ink layer, and the colored ink layer overlap in plan view, The mass of the white pigment per unit area in the white ink layer is 0.4 g / m2or more and 1.0 g / m2or less. 2 The above.

14. A laminate comprising: the image recorded matter according to claim 12 or 13; and a laminating substrate laminated on the image of the image recorded matter.

15. An ink set comprising: a white ink containing a white pigment, a pigment dispersant, a first organic solvent, and water; and a colored ink containing a coloring pigment other than the white pigment, a second organic solvent, and water, the pigment dispersant being a polymer or a block polymer having a crosslinked structure, The weighted average of the solubility parameters of the organic solvents contained in each of the white ink and the colored ink is 28 MPa 1 / 2 Hereinafter, the first organic solvent includes a first organic solvent A having a boiling point of 120°C to 200°C, and the proportion of the first organic solvent A in all the organic solvents contained in the white ink is 95% by mass or more, the first organic solvent A contains at least one alkylene glycol and at least one alkylene glycol alkyl ether, the mass ratio of the content of the alkylene glycol to the content of the alkylene glycol alkyl ether is 15.0 or less.

16. An ink set comprising: a white ink containing a white pigment, a pigment dispersant, an organic solvent, and water; and a colored ink containing a coloring pigment other than the white pigment and water, the pigment dispersant being a polymer or a block polymer having a crosslinked structure, the organic solvent contains at least one alkylene glycol having a boiling point of 120°C to 200°C and at least one alkylene glycol alkyl ether having a boiling point of 120°C to 200°C, and the total proportion of the alkylene glycol and the alkylene glycol alkyl ether in the organic solvent is 95% by mass or more, the mass ratio of the content of the alkylene glycol to the content of the alkylene glycol alkyl ether is 15.0 or less.

17. The ink set according to claim 16, wherein the organic solvent contains at least one alkylene glycol having a boiling point of 120°C to 200°C and at least two alkylene glycol alkyl ethers having a boiling point of 120°C to 200°C.

Images