Image recording method, image recording material, and ink set, as well as laminate body and method for manufacturing the same.

Abstract

Provided is an image recording method which is capable of recording an image having excellent concealing properties and having excellent lamination strength with a laminate substrate. The image recording method includes: a step for preparing a white ink containing a white pigment, a first organic solvent having a boiling point of 120℃ or more, and water; a step for preparing a coloring ink containing a coloring pigment other than the white pigment, a second organic solvent having a boiling point of 120℃ or more, and water; and a step for recording an image by applying the white ink and the coloring ink, respectively, to an impermeable substrate. Regarding the step for recording an image, the image is recorded under the conditions that, in a region where a region to which the white ink is applied and a region to which the coloring ink is applied overlap in plan view, the total applied mass of the first organic solvent and the second organic solvent per unit area is 5.5 g / m2 or less, and the total applied mass of the white pigment per unit area is at least 0.4 g / m2.

Description

[Technical Field]

[0001] This disclosure relates to an image recording method, an image recording medium, an ink set, and a laminate and a method for manufacturing the same. [Background technology]

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

[0003] For example, Patent Document 1 describes a non-white ink having a non-white colorant and thermoplastic resin particles with a volume-average particle size of 30 to 110 nm, and an ink set having a white ink having a white colorant and thermoplastic resin particles. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2018-94902 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Images recorded with white ink sometimes require low light transmittance (also known as "opacity"). For example, when recording an image on the surface of a colored substrate, high opacity of the image is thought to prevent the substrate's color from being visible through the image. Similarly, when recording an image on the surface of a transparent substrate, high opacity of the image is thought to prevent a decrease in image visibility due to light passing through the transparent substrate and the image. It is also known that images recorded with white ink are used as a base layer to be recorded beneath other colored ink images. By using an image with high opacity as a base layer, as described above, the visibility of the substrate's color or the transmission of light through the substrate and the image is suppressed, thus improving the visibility of the colored ink image. Furthermore, after recording an image on a non-permeable substrate to obtain an image recording, a laminating substrate may be laminated onto the image on the image recording. In this case, it may be necessary to improve the lamination strength between the image recording and the laminating substrate.

[0006] This disclosure has been made in view of these circumstances, and one embodiment of this disclosure aims to solve the problem of recording an image recording method and an ink set that can record an image that has excellent opacity and excellent lamination strength with a laminating substrate. Another embodiment of the present disclosure aims to solve the problem of providing an image recording material having excellent opacity and excellent lamination strength with a laminating substrate. Another embodiment of the present disclosure aims to solve the problem of providing a laminate body that has excellent lamination strength with a laminating substrate, and a method for manufacturing the laminate body that can produce the above-mentioned laminate body. [Means for solving the problem]

[0007] This disclosure includes the following aspects: <1> The process includes the steps of: preparing a white ink containing a white pigment, a first organic solvent with a boiling point of 120°C or higher, and water; preparing a colored ink containing a colored pigment other than the white pigment, a second organic solvent with a boiling point of 120°C or higher, and water; and recording an image by applying the white ink and the colored ink to a non-permeable substrate, respectively, wherein in the image recording step, the total amount of the first and second organic solvents applied per unit area is 5.5 g / m² in the area where the area to which the white ink is applied and the area to which the colored ink is applied overlap in a plan view. 2 The following applies, and the amount of white pigment applied per unit area is 0.4 g / m². 2 An image recording method that records images under the above conditions. <2> 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. <1> The image recording method described above. <3> The process further includes a step of preparing a pretreatment solution containing a coagulant and water, and in the image recording step, the pretreatment solution is applied to a non-permeable substrate, and then white ink and colored ink are applied to record the image. <1> or <2> The image recording method described above. <4> The pretreatment solution does not contain a third organic solvent with a boiling point of 120°C or higher, or, if it contains a third organic solvent with a boiling point of 120°C or higher, the content of the third organic solvent with a boiling point of 120°C or higher relative to the total volume of the pretreatment solution is 15% by mass or less. <3> The image recording method described above. <5> In the image recording process, in the area where the area to which the pretreatment solution is applied, the area to which white ink is applied, and the area to which colored ink is applied overlap in a plan view, the total mass of the first organic solvent, the second organic solvent, and the third organic solvent applied per unit area is 5.5 g / m². 2 The image will be recorded under the following conditions: <4> The image recording method described above. <6> In the image recording process, the area to which the pretreatment solution is applied, the area to which white ink is applied, and the area to which colored ink is applied overlap in a plan view, and the amount of the third organic solvent applied per unit area is 0.2 g / m². 2The image will be recorded under the following conditions: <4> or <5> The image recording method described above. <7> The white ink further contains a pigment dispersant, which is a polymer or block polymer having a cross-linked structure. <1> ~ <6> The image recording method described in one of the following. <8> Both the white and colored inks have a weighted average value of 28 MPa for the solubility parameters of the organic solvents contained in each ink. 1 / 2 The following is: <1> ~ <7> The image recording method described in one of the following. <9> The first organic solvent contains a first organic solvent A with a boiling point of 120°C to 200°C, and the proportion of the first organic solvent A in the total organic solvent contained in the white ink is 50% by mass or more. The first organic solvent A contains at least one alkylene glycol and at least one alkylene glycol alkyl ether. <1> ~ <8> The image recording method described in one of the following. <10> The first organic solvent A comprises at least one alkylene glycol and at least two alkylene glycol alkyl ethers. <9> The image recording method described above. <11> The mass ratio of alkylene glycol content to alkylene glycol ether content is 15.0 or less. <9> or <10> The image recording method described above. <12> The second organic solvent contains a second organic solvent A with a boiling point of 120°C to 200°C, and the proportion of the second organic solvent A in the total organic solvent 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. <1> ~ <11> The image recording method described in one of the following. <13> On a non-permeable substrate, <1> ~ <12> A method for manufacturing a laminate, comprising the steps of: recording an image using an image recording method described in any one of the above; and laminating a laminating substrate onto the side of a non-permeable substrate on which the image has been recorded to obtain a laminate. <14> The invention comprises an impermeable substrate and an image recorded on the impermeable substrate, wherein the image includes a white ink layer containing a white pigment in contact with the impermeable substrate and a colored ink layer containing a colored pigment other than the white pigment in contact with the white ink layer, and includes a region where the white ink layer and the colored ink layer overlap in a plan view, and in the white ink layer, the mass of the white pigment per unit area is 0.4 g / m² 2 The above is the image recording. <15> The apparatus comprises an impermeable substrate and an image recorded on the impermeable substrate, wherein the image includes a pretreatment liquid layer containing a flocculant in contact with the impermeable substrate, a white ink layer containing a white pigment in contact with the pretreatment liquid layer, and a colored ink layer containing a coloring pigment other than the white pigment in contact with the white ink layer, and includes a region where the pretreatment liquid layer, the white ink layer, and the colored ink layer overlap in a plan view, and the mass of the white pigment per unit area in the white ink layer is 0.4 g / m² 2 The above is the image recording. <16> <14> or <15> A laminate body comprising an image recording material described in [reference] and a laminating substrate laminated onto the image of the image recording material. <17> The product 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, an organic solvent, and water, wherein the pigment dispersant is a polymer or block polymer having a crosslinked structure, and both the white ink and the colored ink have a weighted average value of the solubility parameters of the organic solvent contained in each ink of 28 MPa. 1 / 2 The following is the ink set. <18> 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 colored pigment other than the white pigment and water, wherein the pigment dispersant is a polymer or block polymer having a crosslinked structure, and the organic solvent comprises 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. <19> The organic solvent comprises 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. <18> The ink set described above. [Effects of the Invention]

[0008] According to one embodiment of the present disclosure, an image recording method and an ink set are provided that can record an image with excellent opacity and excellent lamination strength with a laminating substrate. Another embodiment of the present disclosure provides an image recording material having excellent opacity and excellent lamination strength with a laminating substrate. Another embodiment of the present disclosure provides a laminate body having excellent lamination strength with a laminating substrate, and a method for manufacturing the laminate body capable of producing the above-mentioned laminate body. [Modes for carrying out the invention]

[0009] The image recording method, image recording material, ink set, laminate, and manufacturing method of the present disclosure will be described in detail below.

[0010] In this specification, a numerical range indicated using "~" means a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, within the numerical ranges described herein, any upper or lower limit values ​​within a given range may be replaced with the values ​​shown in the examples.

[0011] In this specification, the amount of each component in a composition means the total amount of multiple substances present in the composition, unless otherwise specified, if there are multiple substances corresponding to each component in the composition. In this specification, a combination of two or more preferred embodiments is a more preferred embodiment. In this specification, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps, as long as the intended purpose of the step is achieved.

[0012] In this specification, "image" means the entire film formed by applying a pretreatment liquid and ink in this order, and "image recording" means forming an image (i.e., a film). Also, the concept of "image" in this specification includes a solid image.

[0013] In this specification, "(meth)acrylate" is a concept that includes both acrylate and methacrylate. Also, "(meth)acrylic" is a concept that includes both acrylic and methacrylic.

[0014] In this specification, "alkylene glycol" is a concept that includes both monoalkylene glycol and polyalkylene glycol. Also, "alkylene glycol alkyl ether" is a concept that includes monoalkylene glycol monoalkyl ether, monoalkylene glycol polyalkyl ether, polyalkylene glycol monoalkyl ether, and polyalkylene glycol polyalkyl ether.

[0015] [Image Recording Method] The image recording method of the present disclosure 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 applying the white ink and the colored ink onto a non-permeable substrate to record an image. In the step of recording an image, in a region where the region where the white ink is applied and the region where the colored ink is applied overlap in plan view, the total applied mass of the first organic solvent and the second organic solvent per unit area is 5.5 g / m 2The following applies, and the amount of white pigment applied per unit area is 0.4 g / m². 2 The image will be recorded under the above conditions.

[0016] According to the image recording method of this disclosure, an image recording material comprising an impermeable substrate and an image recorded on the impermeable substrate can be obtained, which exhibits excellent lamination strength when a laminating substrate is laminated onto the image. Here, lamination strength refers to the peel strength when separating the laminating substrate from the image recording material in a laminated body formed by the above lamination [i.e., a laminated body having a laminated structure of "laminating substrate / image recording material" (more specifically, a laminated structure of "laminating substrate / image / impermeable substrate")]. Furthermore, the image recording method disclosed herein provides an image recording with excellent concealment properties.

[0017] The reason why the above effects are achieved by the image recording method disclosed herein is presumed to be as follows. To improve the lamination strength of a laminated material, it is first necessary to improve the adhesion between the non-permeable substrate and the image, and then to improve the adhesion between the image and the laminating substrate.

[0018] In the image recording method of this disclosure, white ink and colored ink are applied to a non-permeable substrate, respectively. The white ink and colored ink are applied under conditions that an overlapping area is created in a plan view between the area to which the white ink is applied and the area to which the colored ink is applied. The inventors focused on a first organic solvent with a boiling point of 120°C or higher contained in the white ink and a second organic solvent with a boiling point of 120°C or higher contained in the colored ink. In the image recording method of this disclosure, the total mass of the first organic solvent and the second organic solvent applied per unit area in the overlapping area is 5.5 g / m². 2 White ink and colored ink are applied under the following conditions: The total applied mass is 5.5 g / m². 2The following factors are thought to suppress the decrease in image intensity (e.g., abrasion resistance, blocking resistance, etc.) and ensure image intensity. As a result, the decrease in adhesion between the image and the laminating substrate caused by a decrease in image intensity is thought to be suppressed.

[0019] Furthermore, in the image recording method disclosed herein, the amount of white pigment applied per unit area in the overlapping region is 0.4 g / m². 2 The white ink is applied under the above conditions. The white pigment is presumed to retain the surrounding organic solvent on the non-permeable substrate. Therefore, the above application mass is 0.4 g / m². 2 As a result of the above, image strength is ensured, and excellent adhesion between the image and the laminating substrate is expected. Furthermore, the above-mentioned applied mass is 0.4 g / m². 2 As a result of the above, light transmission is suppressed, and an image recording material with excellent opacity can be obtained.

[0020] The following describes each step included in the image recording method of this disclosure.

[0021] <White ink preparation process> The image recording method disclosed herein 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").

[0022] (White pigment) The white ink prepared in the white ink preparation process contains white pigment.

[0023] White pigments can be any pigment that exhibits white color, and their type is not particularly limited. White refers to 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, silica, talc, mica, aluminum hydroxide, calcium silicate, aluminum silicate, and zinc sulfide. White pigments are preferably particles containing titanium atoms, and more preferably titanium dioxide.

[0024] 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. An average particle size of 550 nm or less results in good color reproducibility and good ejection stability when recording images using an inkjet recording method. On the other hand, an average particle size of 10 nm or more results in good lightfastness. The particle size distribution of the pigment may 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 by measuring the volume-average particle size using the dynamic light scattering method with a particle size distribution analyzer, for example, the "NanoTrack UPA-EX150" product manufactured by Nikkiso Co., Ltd. Furthermore, if the pigment is coated with a pigment dispersant, the average particle size of the pigment refers to the average particle size of the pigment coated with the pigment dispersant.

[0025] The white pigment content is 0.4 g / m², based on the amount of white pigment applied. 2 From the above viewpoint, the amount of white ink is preferably 5% to 20% by mass, and more preferably 8% to 15% by mass, relative to the total amount of white ink.

[0026] (First organic solvent with a boiling point of 120°C or higher) 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 simply referred to as the "first organic solvent."

[0027] In this disclosure, “boiling point” means the boiling point at 1 atmosphere (101325 Pa). The boiling point is measured using a boiling point meter, for example, using a boiling point measuring instrument (product name “DosaTherm300”, manufactured by Titan Technologies).

[0028] Examples of organic solvents with a boiling point of 120°C or higher include alcohols such as 1,3-butanediol (207°C), 1,4-butanediol (228°C), benzyl alcohol (205°C), and terpineol (217°C); Alkylene glycols such as ethylene glycol (197°C), diethylene glycol (244°C), triethylene glycol (287°C), propylene glycol (187°C), and dipropylene glycol (230°C); Diethylene glycol monomethyl ether (194°C), diethylene glycol monoethyl ether (202°C), diethylene glycol monobutyl ether (231°C), diethylene glycol dimethyl ether (162°C), diethylene glycol ethyl methyl ether (176°C), diethylene glycol isopropyl methyl ether (179°C), triethylene glycol monomethyl ether (249°C), triethylene glycol dimethyl ether (216°C), propylene glycol monomethyl ether (121°C), propylene glycol monobutyl ether (170°C), propylene glycol monopropyl ether (150°C), 3-methyl ether Alkylene glycol alkyl ethers such as toxy-3-methyl-1-butanol (174°C), diethylene glycol monohexyl ether (above 261°C), propylene glycol monomethyl ether propionate (160°C), methyl cellosolve (ethylene glycol monomethyl ether, 125°C), ethyl cellosolve (ethylene glycol monoethyl ether, 135°C), butyl cellosolve (ethylene glycol monobutyl ether, 171°C), ethylene glycol mono-tert-butyl ether (153°C), tripropylene glycol monomethyl ether (243°C), and dipropylene glycol monomethyl ether (188°C); Examples include esters such as ethylene glycol monomethyl ether acetate (145°C), diethylene glycol monoethyl ether acetate (217°C), ethyl acetate (154°C), ethyl lactate (154°C), and 3-methoxybutyl acetate (172°C); and ketones such as diacetone alcohol (169°C), cyclohexanone (156°C), and cyclopentanone (131°C). The numbers in parentheses indicate the boiling point.

[0029] When a white ink contains a first organic solvent, it exhibits excellent ejection properties and re-ejection properties after printing pauses (hereinafter simply referred to as "re-ejection properties"). The white ink may contain an organic solvent with a boiling point of less than 120°C. From the viewpoint of ejection properties and re-ejection 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 be 100% by mass. In other words, all of the organic solvent contained in the white ink may be the first organic solvent.

[0030] The content of the first organic solvent in the 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, based on the total amount of the white ink. When the content of the first organic solvent is 30% by mass or less, image intensity is ensured even in overlapping areas, and the adhesion between the image and the laminating substrate is improved. As a result, the lamination strength is improved.

[0031] The lower limit of the content of the first organic solvent is not particularly limited as long as it is greater than 0% by mass, but from the viewpoint of dischargeability and opacity, the content of the first organic solvent is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, relative to the total amount of white ink.

[0032] From the viewpoint of further improving the lamination strength of the image recording material, the white ink preferably contains 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 be 100% by mass. In other words, all of the organic solvent contained in the white ink may be first organic solvent A.

[0033] The first organic solvent A preferably contains at least one selected from the group consisting of alkylene glycols and alkylene glycol ethers. More preferably, the first organic solvent A contains at least one alkylene glycol and at least one alkylene glycol ether. Furthermore, it is even more preferable that the first organic solvent A contains at least one alkylene glycol and at least two alkylene glycol ethers. The alkylene glycol and alkylene glycol ether 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.

[0034] If the white ink contains an organic solvent comprising 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, the drying properties of the white ink on the substrate are improved. This improves the lamination strength and adhesion.

[0035] Furthermore, if the white ink contains an organic solvent comprising 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 white ink on the substrate are further improved. This, in turn, improves the lamination strength and adhesion.

[0036] When the white ink contains alkylene glycol alkyl ether and alkylene glycol alkyl ether, 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, even more preferably 15.0 or less, even more preferably 10.0 or less, and particularly preferably 6.0 or less, from the viewpoint of further improving lamination strength and adhesion. The lower limit of the above mass ratio is not particularly limited, but from the viewpoint of re-dispensing performance, it is preferably 1.0, more preferably 2.0, even more preferably 3.0, and even more preferably 4.0.

[0037] The white ink may contain, in addition to the first organic solvent A, an organic solvent with a boiling point greater than 200°C and 240°C or less (hereinafter referred to as "first organic solvent B"), and may also contain an organic solvent with a boiling point greater than 240°C (hereinafter referred to as "first organic solvent C"). Furthermore, the white ink may contain both the first organic solvent B and the first organic solvent C in addition to the first organic solvent A.

[0038] 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 organic solvent contained 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, it is preferable that all of the organic solvent contained in the white ink is an organic solvent consisting of the first organic solvent A and the first organic solvent B, or the first organic solvent A. It is even more preferable that all of the organic solvent contained in the white ink is the first organic solvent A. Examples of the first organic solvent B include diethylene glycol monobutyl ether, dipropylene glycol, 1,2-hexanediol, and ethylene glycol monohexyl ether.

[0039] From the viewpoint of further improving the lamination strength and adhesion of image recordings, it is preferable that the proportion of the first organic solvent C in the organic solvent contained in the white ink is 10% by mass or less. The above proportion may be 0% by mass. In other words, the first organic solvent C may not be contained in the white ink. Examples of the first organic solvent C include diethylene glycol and triethylene glycol.

[0040] The weighted average value of the solubility parameter (SP value) of the organic solvent contained in the white ink is 28 MPa. 1 / 2 The following is preferable. The weighted average of the SP values ​​is calculated using the following formula. In the formula, S i This represents the SP value of the i-th organic solvent contained in the white ink, W i This represents the content (by mass) of the i-th organic solvent relative to the total amount of white ink.

[0041] Weighted average of solubility parameters = ΣS i W i / ΣW i

[0042] The weighted average SP value of the organic solvent contained in the white ink is 28 MPa. 1 / 2The following is considered to be the case, which makes the organic solvent as a whole more volatile. As a result, the lamination strength of the image recording improves. The above weighted average value is 27 MPa from the viewpoint of lamination strength. 1 / 2 The following is more preferable. The lower limit of the above weighted average value is 25.5 MPa from the viewpoint of discharge performance and re-discharge performance. 1 / 2 It is preferable that this be the case.

[0043] In this disclosure, the SP value is a value expressed as the square root of the molecular cohesive energy, calculated using the method described in RFFedors, Polymer Engineering Science, 14, pp. 147-154 (1974), and the unit of the SP value is MPa. 1 / 2 That is the case.

[0044] The following are examples of SP values ​​for organic solvents. The numbers in parentheses represent the SP values. Propylene glycol (27.6 MPa) 1 / 2 ) Ethylene glycol (30.3MPa 1 / 2 ) Diethylene glycol (30.6 MPa 1 / 2 ), triethylene glycol (27.8MPa) 1 / 2 ) Tripropylene glycol (24.7 MPa 1 / 2 )2-methyl-1,3-butanediol (28.27) 1,2-pentanediol (28.64 MPa) 1 / 2 )1,5-pentanediol (28.96MPa) 1 / 2 )1,2-Hexanediol (21.3MPa) 1 / 2 )1,6-Hexanediol (27.66MPa) 1 / 2 ) Glycerin (33.5MPa) 1 / 2 )Dimethylformamide (30.62MPa) 1 / 2 Methanol (28.17MPa) 1 / 2 Isopropyl alcohol (28.69 MPa) 1 / 2 ) Triethanolamine (32.27MPa 1 / 2 ) Dipropylene glycol (27.1 MPa 1 / 2 ) Ethylene glycol monoethyl ether (23.5MPa) 1 / 2) Ethylene glycol monopropyl ether (21.8MPa) 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 (21.7MPa) 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 (21.8MPa) 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 t-butyl ether (19.98 MPa) 1 / 2 ) Tripropylene glycol monomethyl ether (20.4MPa) 1 / 2 ) Diethylene glycol monohexyl ether (20.91 MPa) 1 / 2 ) Ethylene glycol mono-2-ethylhexyl ether (20.46MPa) 1 / 2 ) Diethylene glycol mono-2-ethylhexyl ether (20.26 MPa 1 / 2 )

[0045] (water) The white ink prepared in the white ink preparation process contains water. The water content is not particularly limited, but is, for example, 40% to 70% by mass.

[0046] (Pigment dispersant) The white ink prepared in the white ink preparation step preferably contains a pigment dispersant in order to disperse the white pigment in water. In this disclosure, the pigment dispersant has the function of dispersing the pigment. The pigment dispersant is adsorbed onto the surface of the pigment and covers at least a part of the surface of the pigment, thereby allowing the pigment to be dispersed in water. However, if a self-dispersing pigment that can be dispersed in water even without a pigment dispersant is used as the white pigment, the white ink does not need to contain a pigment dispersant.

[0047] The form of the pigment dispersant contained in the white ink is not particularly limited and may be a random polymer, a block polymer, or a graft polymer. Furthermore, the pigment dispersant contained in the white ink may be a polymer having a cross-linked structure. Among these, it is preferable that the pigment dispersant contained in the white ink be a polymer having a cross-linked structure or a block polymer. When the pigment dispersant is a polymer having a cross-linked structure or a block polymer, it is thought that the pigment dispersant is less likely to detach from the surface of the white pigment, resulting in high dispersion stability of the white pigment. As a result, when the white ink reacts with the pretreatment solution, the white pigment aggregates uniformly, resulting in a uniform image, easier evaporation of the organic solvent, and improved laminate strength. Even without using a pretreatment solution, after the white ink lands on a non-permeable substrate, the solvent ratio in the white ink increases as water evaporates, making the dispersion of the white pigment more unstable. In this case, if the pigment dispersant is a polymer having a cross-linked structure or a block polymer, uneven aggregation of the white pigment is suppressed, resulting in a uniform image, easier evaporation of the organic solvent, and improved laminate strength.

[0048] In this disclosure, "polymer" refers to a compound with a weight-average molecular weight of 1000 or more.

[0049] In this disclosure, weight-average molecular weight refers to the value measured by gel permeation chromatography (GPC). The GPC measurement is performed using an HLC®-8020GPC (manufactured by Tosoh Corporation) as the measuring instrument, with three TSKgel® Super Multipore HZ-H columns (4.6 mm ID × 15 cm, manufactured by Tosoh Corporation), and THF (tetrahydrofuran) as the eluent. The measurement is performed with a sample concentration of 0.45% by mass, a flow rate of 0.35 ml / min, a sample injection volume of 10 μl, and a measurement temperature of 40°C, using an RI detector. A calibration curve is prepared from eight samples of 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".

[0050] - A polymer with a cross-linked structure - A polymer having a cross-linked structure is not particularly limited as long as it has at least one cross-linked structure within its molecule.

[0051] Whether or not the polymers contained in the ink have a cross-linked structure can be determined, for example, by the following method. First, the polymers are separated from the ink using a separation method such as solvent extraction. The separated polymers can then be analyzed using various analytical methods such as nuclear magnetic resonance (NMR), infrared spectroscopy (IR), and thermal analysis to comprehensively determine whether or not they have a cross-linked structure.

[0052] A polymer having a crosslinked structure (hereinafter also referred to as "crosslinked polymer") is formed, for example, by crosslinking an uncrosslinked polymer (hereinafter also referred to as "uncrosslinked polymer") with a crosslinking agent. The uncrosslinked polymer is preferably a water-soluble polymer.

[0053] In this disclosure, "water-soluble" means the property of dissolving 1 g or more in 100 g of water at 25°C. Preferably, "water-soluble" means dissolving 3 g or more (more preferably 10 g or more) in 100 g of water at 25°C.

[0054] Furthermore, even if an uncrosslinked polymer is water-soluble, the crosslinked polymer is not necessarily water-soluble.

[0055] Examples of uncrosslinked polymers include vinyl resins, acrylic resins, urethane resins, and polyester resins. Among these, acrylic resin is preferred as the uncrosslinked polymer.

[0056] The uncrosslinked polymer is preferably a polymer having functional groups that can be crosslinked by a crosslinking agent. Examples of crosslinkable functional groups include carboxyl groups or their salts, isocyanate groups, and epoxy groups. Among these, from the viewpoint of improving the dispersibility of the pigment, the crosslinkable functional group is preferably a carboxyl group or its salt, and a carboxyl group is particularly preferred. In other words, the uncrosslinked polymer is preferably a polymer containing carboxyl groups.

[0057] The uncrosslinked polymer is preferably a copolymer containing structural units derived from monomers containing carboxyl groups (hereinafter referred to as "carboxyl group-containing monomers"). The copolymer may contain only one type of structural unit derived from carboxyl group-containing monomers, or two or more types. The copolymer may be a random copolymer or a block copolymer, but it is preferably a random copolymer.

[0058] Examples of monomers containing a carboxyl group include (meth)acrylic acid, β-carboxyethyl acrylate, fumaric acid, itaconic acid, maleic acid, and crotonic acid.

[0059] The carboxyl group-containing monomer is preferably (meth)acrylic acid or β-carboxyethyl acrylate, with (meth)acrylic acid being more preferred, from the viewpoint of crosslinkability and dispersibility.

[0060] The content of structural units derived from carboxyl group-containing monomers is preferably 5% to 40% by mass, more preferably 10% to 35% by mass, and even more preferably 10% to 30% by mass, based on the total amount of the uncrosslinked polymer.

[0061] The uncrosslinked polymer preferably contains structural units derived from hydrophobic monomers in addition to structural units derived from carboxyl group-containing monomers. The copolymer may contain only one type of structural unit derived from hydrophobic monomers, or two or more types.

[0062] Examples of hydrophobic monomers include (meth)acrylates having alkyl groups with 1 to 20 carbon atoms, (meth)acrylates having aromatic rings (e.g., benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, etc.), styrene, and styrene derivatives.

[0063] The content of structural units derived from hydrophobic monomers is preferably 60% to 95% by mass, more preferably 65% ​​to 90% by mass, and even more preferably 70% to 90% by mass, based on the total amount of the uncrosslinked polymer.

[0064] The uncrosslinked polymer is preferably a random copolymer comprising structural units derived from a carboxyl group-containing monomer and at least one of structural units derived from (meth)acrylate having an alkyl group with 1 to 20 carbon atoms and structural units derived from (meth)acrylate having an aromatic ring; more preferably a random copolymer comprising structural units derived from (meth)acrylic acid and structural units derived from (meth)acrylate having an aromatic ring; and even more preferably a copolymer comprising structural units derived from (meth)acrylic acid and structural units derived from benzyl (meth)acrylate.

[0065] The weight-average molecular weight (Mw) of the uncrosslinked polymer is not particularly limited, 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.

[0066] The preferred range for the weight-average molecular weight of the crosslinked polymer is the same as the preferred range for the weight-average molecular weight of the uncrosslinked polymer.

[0067] In this disclosure, the weight-average molecular weight (Mw) is measured by gel permeation chromatography (GPC). The GPC is performed using an HLC-8220GPC (manufactured by Tosoh Corporation), with three columns connected in series: TSKgeL SuperHZM-H, TSKgeL SuperHZ4000, and TSKgel SuperHZ2000 (all product names of Tosoh Corporation). THF (tetrahydrofuran) is used as the eluent. The conditions are a sample concentration of 0.45% by mass, a flow rate of 0.35 ml / min, a sample injection volume of 10 μl, and a measurement temperature of 40°C, and the measurement is performed using a differential refractive index detector. Furthermore, the calibration curve will be created using 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".

[0068] The crosslinking agent used when crosslinking an uncrosslinked polymer is preferably a compound having two or more reaction sites with the uncrosslinked polymer (for example, a polymer having a carboxyl group). One type of crosslinking agent may be used, or two or more types may be used.

[0069] A preferred combination of a crosslinking agent and an uncrosslinked polymer is a compound having two or more epoxy groups (i.e., a bifunctional or more epoxy compound) and a polymer having a carboxyl group. In this combination, a crosslinked structure is formed by the reaction between the epoxy groups and the carboxyl groups. It is preferable that the formation of the crosslinked structure by the crosslinking agent is carried out after the pigment has been dispersed by the uncrosslinked polymer.

[0070] Examples of bifunctional or more epoxy compounds include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and trimethylolpropane triglycidyl ether.

[0071] Among these, the preferred epoxy compounds with two or more functions are polyethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, or trimethylolpropane triglycidyl ether.

[0072] The crosslinking agent can be a commercially available product. Examples of commercially available products include Denacol EX-321, EX-821, EX-830, EX-850, and EX-851 (manufactured by Nagase ChemteX).

[0073] The molar ratio of the reaction sites in the crosslinking agent (e.g., epoxy groups) to the reaction sites in the uncrosslinked polymer (e.g., carboxyl groups) 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, from the viewpoint of crosslinking reaction rate and dispersion stability after crosslinking.

[0074] -Block Polymer- A block polymer, also known as a block copolymer, is a copolymer in which at least two polymers are bonded together within the molecule.

[0075] The block polymer preferably contains structural units derived from hydrophobic monomers and structural units derived from monomers containing anionic groups (hereinafter referred to as "anionic group-containing monomers").

[0076] The structural units derived from hydrophobic monomers contained in the block polymer may be one type or two or more types. The structural units derived from anionic group-containing monomers contained in the block polymer may be one type or two or more types.

[0077] Structural units derived from hydrophobic monomers include ethylenically unsaturated compounds having an aromatic ring structure or an alicyclic structure, and (meth)acrylates having an alkyl group with 1 to 20 carbon atoms.

[0078] The content of structural units derived from hydrophobic monomers is preferably 35% to 95% by mass, more preferably 50% to 95% by mass, and even more preferably 70% to 90% by mass, relative to the total amount of the block polymer.

[0079] From the viewpoint of adsorption with pigments, the hydrophobic monomer preferably contains an ethylenically unsaturated compound having an aromatic ring structure or an alicyclic structure, more preferably contains an ethylenically unsaturated compound having an alicyclic structure, and even more preferably contains an ethylenically unsaturated compound having an alicyclic structure with 6 or more carbon atoms.

[0080] The content of structural units derived from ethylenically unsaturated compounds having an aromatic ring structure or an alicyclic structure is preferably 10% to 90% by mass, more preferably 20% to 80% by mass, even more preferably 30% to 70% by mass, and still more preferably 30% to 60% by mass, based on the total amount of the block polymer.

[0081] The structural units derived from hydrophobic monomers may also preferably include (meth)acrylates having an alkyl group with 1 to 20 carbon atoms. The alkyl group may be linear or branched.

[0082] Examples of (meth)acrylates having an alkyl group with 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.

[0083] The content of structural units derived from (meth)acrylates having an alkyl group with 1 to 20 carbon atoms is preferably 10% to 90% by mass, more preferably 20% to 80% by mass, even more preferably 30% to 70% by mass, and particularly preferably 40% to 60% by mass, based on the total amount of the block polymer.

[0084] In structural units derived from anionic group-containing monomers, examples of anionic groups include carboxyl groups, salts of carboxyl groups, sulfo groups, salts of sulfo groups, phosphate groups, salts of phosphate groups, phosphonic acid groups, and salts of phosphonic acid groups.

[0085] Counterions in salts 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.

[0086] In particular, the anionic group is preferably a carboxyl group or a salt of a carboxyl group. Examples of anionic group-containing monomers include (meth)acrylic acid, β-carboxyethyl acrylate, fumaric acid, itaconic acid, maleic acid, and crotonic acid. In particular, the anionic group-containing monomer is preferably (meth)acrylic acid.

[0087] The content of structural units derived from anionic group-containing monomers is preferably 1% to 30% by mass, more preferably 2% to 25% by mass, and even more preferably 3% to 20% by mass, based on the total amount of the block polymer.

[0088] Whether or not the polymer contained in the ink is a block polymer can be determined, for example, by the following method. First, the polymer is separated from the ink using a separation method such as solvent extraction. The separated polymer is then analyzed using various analytical methods such as nuclear magnetic resonance (NMR), infrared spectroscopy (IR), and thermal analysis, and its physical properties, such as the glass transition temperature, are measured to comprehensively determine whether or not it is a block polymer. For example, a preferred configuration in the above determination method is that the block polymer contained in the ink has two or more glass transition temperatures.

[0089] The weight-average molecular weight (Mw) of the block polymer is not particularly limited, 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.

[0090] The mixing ratio of the white pigment to the pigment dispersant is preferably 1:0.02 to 1:2 by mass, more preferably 1:0.03 to 1:1.5, and even more preferably 1:0.04 to 1:1.

[0091] Known dispersion devices can be used to disperse pigments, including, for example, ball mills, sand mills, bead mills, roll mills, jet mills, paint shakers, attritors, ultrasonic dispersers, and dispersers.

[0092] (Resin particles) The white ink prepared in the white ink preparation step preferably contains at least one type of resin particle from the viewpoint of improving the lamination strength of the image recording material. The white ink preferably contains resin particles, which are particles made of resin, in addition to the pigment dispersant.

[0093] When white ink is applied to a non-permeable substrate that has been treated with a pretreatment solution, the flocculant contained in the pretreatment solution comes into contact with the resin particles contained in the white ink, destabilizing the dispersion of the resin particles and increasing the viscosity of the white ink. As a result, the white ink adheres to the non-permeable substrate, improving the lamination strength of the image recording.

[0094] The resin constituting the resin particles is preferably a water-insoluble polymer. In the context of water-insoluble polymers, "water-insoluble" means that the amount that dissolves in 100g of distilled water at 25°C is less than 2g.

[0095] The resin particles preferably contain 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 it is preferable that they contain acrylic resin particles.

[0096] The resin particles are preferably self-dispersible resin particles. Examples of self-dispersing resin particles include those described in paragraphs 0062 to 0076 of Japanese Patent Publication No. 2016-188345 and paragraphs 0109 to 0140 of International Publication No. 2013 / 180074.

[0097] The resin in the resin particles is preferably an acrylic resin containing structural units derived from (meth)acrylate having an aromatic ring structure or an alicyclic structure, structural units derived from (meth)acrylic acid, and structural units derived from alkyl (meth)acrylate containing an alkyl group having 1 to 4 carbon atoms.

[0098] The (meth)acrylate having an alicyclic structure is preferably an alkyl (meth)acrylate having a cycloalkyl group with 3 to 10 carbon atoms, and preferably at least one selected from the group consisting of cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, and dicyclopentanyl (meth)acrylate, and more preferably at least one selected from the group consisting of isobornyl (meth)acrylate, adamantyl (meth)acrylate, and dicyclopentanyl (meth)acrylate. The (meth)acrylate having an aromatic ring structure is preferably phenoxyethyl (meth)acrylate or benzyl (meth)acrylate.

[0099] Examples of resins used in resin particles include phenoxyethyl acrylate / methyl methacrylate / acrylic acid copolymer (50 / 45 / 5), phenoxyethyl acrylate / benzyl methacrylate / isobutyl methacrylate / methacrylic acid copolymer (30 / 35 / 29 / 6), phenoxyethyl methacrylate / isobutyl methacrylate / methacrylic acid copolymer (50 / 44 / 6), phenoxyethyl acrylate / methyl methacrylate / ethyl acrylate / acrylic acid copolymer (30 / 55 / 10 / 5), and benzyl methacrylate. Benzyl acrylate / isobutyl methacrylate / methacrylic 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 Tyl methacrylate / cyclohexyl methacrylate / methacrylic acid copolymer (35 / 30 / 30 / 5), 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 Methyl methacrylate / phenoxyethyl acrylate / acrylic acid copolymer (45 / 51 / 4), methyl methacrylate / isobornyl methacrylate / methacrylic acid copolymer (20 / 72 / 8), methyl methacrylate / isobornyl methacrylate / methacrylic acid copolymer (40 / 52 / 8), methyl methacrylate / isobornyl methacrylate / methacrylic acid copolymer (48 / 42 / 10), methyl methacrylate / isobornyl methacrylate / dicyclopentanyl methacrylate / methacrylic acid copolymer (20 / 62 / 10 / 8),Examples include methyl methacrylate / dicyclopentanyl methacrylate / methacrylic acid copolymer (20 / 72 / 8) and methyl methacrylate / isobornyl methacrylate / methacrylic acid copolymer (70 / 20 / 10). The values ​​in parentheses represent the mass ratio of structural units derived from monomers. Furthermore, the (meth)acrylic acid constituting the resin may be partially or entirely a salt.

[0100] 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.

[0101] 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.

[0102] From the viewpoint of discharge 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. The average particle size of the resin particles is determined by measuring the volume-average particle size using dynamic light scattering with a particle size distribution analyzer, for example, the "NanoTrack UPA-EX150" product manufactured by Nikkiso Co., Ltd.

[0103] If the white ink contains resin particles, the resin particle content 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 still more preferably 2% to 5% by mass, relative to the total amount of the white ink. (Additives) The white ink prepared in the white ink preparation step may contain additives such as surfactants, co-sensitizers, UV absorbers, antioxidants, fade inhibitors, conductive salts, and basic compounds, as needed.

[0104] (Physical properties) The pH of the white ink is preferably 7 to 10, and more preferably 7.5 to 9.5, from the viewpoint of improving ejection stability. The pH is measured at 25°C using a pH meter, for example, using a pH meter (model number "HM-31") manufactured by Toa DKK.

[0105] 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, preferably 2 mPa·s to 15 mPa·s, and even more preferably 3 mPa·s to 10 mPa·s. The viscosity is measured at 25°C using a viscometer, for example, using a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

[0106] The surface tension of the white ink is preferably 60 mN / m or less, 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 at 25°C using a surface tensimeter, for example, by the plate method using an automatic surface tensimeter (product name "CBVP-Z") manufactured by Kyowa Interface Science Co., Ltd.

[0107] <Preparation process for colored ink> The image recording method disclosed herein includes a step of preparing a colored ink containing a colored pigment other than a white pigment, a second organic solvent with a boiling point of 120°C or higher, and water (hereinafter referred to as the "colored ink preparation step").

[0108] The colored ink prepared in the colored ink preparation step may be one type or two or more types. In order to record a multicolor image, it is preferable to prepare two or more types of colored ink in the colored ink preparation step. That is, the image recording method of this disclosure preferably includes a step of preparing at least two types of colored ink containing a colored pigment other than a white pigment, a second organic solvent with a boiling point of 120°C or higher, and water.

[0109] (Coloring pigments) The colored ink prepared in the colored ink preparation process contains colored pigments other than white pigment. Hereinafter, colored pigments other than white pigment will simply be referred to as "colored pigments."

[0110] The coloring pigments contained in the colored ink may be chromatic pigments, black pigments, or a combination of one or more chromatic pigments and one or more black pigments.

[0111] Chromatic pigments can be any pigment that exhibits a chromatic color; their type is not particularly limited. Chromatic color simply means a color that has a hue.

[0112] The chromatic pigments are not particularly limited and include, for example, cyan pigment, magenta pigment, yellow pigment, blue pigment, red pigment, green pigment, orange pigment, and violet pigment.

[0113] Examples of chromatic pigments include organic pigments such as azo pigments, disazo pigments, condensed disazo pigments, phthalocyanine pigments, quinacridone pigments, quinacridone quinone pigments, anthraquinone pigments, aminoanthraquinone pigments, anthanthrone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, perinone pigments, perylene pigments, isoindoline pigments, isoindolinone pigments, isobiolanthrone pigments, benzimidazolon pigments, indanthron pigments, triarylcarbonium pigments, and diketopyrrolopyrrole pigments.

[0114] For more details, see the following as examples of chromatic pigments: Perylene pigments such as CI Pigment Red 190, CI Pigment Red 224, and CI Pigment Violet 29; Perinon pigments such as CI Pigment Orange 43 and CI Pigment Red 194; 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; Quinacridone quinone pigments such as CI Pigment Red 206, CI Pigment Orange 48, and CI Pigment Orange 49; Anthraquinone pigments such as CI Pigment Yellow 147; Anthanthrone pigments such as CI Pigment Red 168; Benzimidazolone pigments such as CI Pigment Brown 25, CI Pigment Violet 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. Condensed disazo pigments such as 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. Disazo pigments such as CI Pigment Yellow 13, CI Pigment Yellow 83, and CI Pigment Yellow 188; Azo pigments such as 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, etc. Indanthron pigments such as CI Pigment Blue 60; 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; Triarylcarbonium pigments such as CI Pigment Blue 56 and CI Pigment Blue 61; Dioxazine pigments such as CI Pigment Violet 23 and CI Pigment Violet 37; Aminoanthraquinone pigments such as CI Pigment Red 177; Diketopyrrolopyrrole pigments such as 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. Thioindigo pigments such as CI Pigment Red 88; Isoindoline pigments such as CI Pigment Yellow 139 and Pigment Orange 66; Isoindolinone pigments such as Pigment Yellow 109 and CI Pigment Orange 61; Pyrantron pigments such as CI Pigment Orange 40 and CI Pigment Red 216; Examples include isobiolantron pigments such as CI Pigment Violet 31.

[0115] The black pigment can be any pigment that exhibits a black color, and its type is not particularly limited. Examples of black pigments include carbon black and titanium black.

[0116] 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. An average particle size of 200 nm or less results in good color reproducibility and good ejection stability when recording images using an inkjet recording method. On the other hand, an average particle size of 10 nm or more results in good lightfastness. The particle size distribution of the pigment may 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 by measuring the volume-average particle size using the dynamic light scattering method with a particle size distribution analyzer, for example, the "NanoTrack UPA-EX150" product manufactured by Nikkiso Co., Ltd. Note that if the pigment is coated with a pigment dispersant, the average particle size of the pigment refers to the average particle size of the pigment coated with the pigment dispersant.

[0117] From the viewpoint of image density, ejection performance, and re-ejection performance, the content of the coloring pigment is preferably 1% to 15% by mass, and more preferably 2% to 10% by mass, relative to the total amount of colored ink.

[0118] (Second organic solvent with a boiling point of 120°C or higher) The colored ink prepared in the colored 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 colored ink will also be simply referred to as the "second organic solvent."

[0119] Examples of organic solvents with a boiling point of 120°C or higher include those similar to the organic solvents with a boiling point of 120°C or higher contained in the white ink mentioned above.

[0120] The presence of a second organic solvent in the colored ink results in excellent ejection and re-ejection properties. The colored ink may contain an organic solvent with a boiling point of less than 120°C. From the viewpoint of ejection and re-ejection properties, the proportion of the second organic solvent in the organic solvent contained in the colored 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 be 100% by mass. In other words, all of the organic solvent contained in the colored ink may be the second organic solvent.

[0121] The content of the second organic solvent in the colored ink is preferably 30% by mass or less, and more preferably 26% by mass or less, relative to the total amount of the colored ink. When the content of the second organic solvent is 30% by mass or less, image intensity is ensured even in overlapping areas, and the adhesion between the image and the laminating substrate is improved. As a result, the lamination strength is excellent. The lower limit of the content of the second organic solvent is not particularly limited as long as it is greater than 0% by mass, but from the viewpoint of dischargeability and opacity, the content of the second organic solvent is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, relative to the total amount of colored ink.

[0122] In particular, from the viewpoint of further improving the lamination strength, it is preferable that both the white ink and the colored ink contain 30% by mass or less of an organic solvent rated at 120°C or higher relative to the total mass of each ink. That is, it is preferable that 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, but for example, it can be 5% by mass or more.

[0123] From the viewpoint of further improving the lamination strength, the colored ink 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 colored 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 be 100% by mass. In other words, all of the organic solvent contained in the colored ink may be second organic solvent A.

[0124] The second organic solvent A preferably contains at least one selected from the group consisting of alkylene glycols and alkylene glycol ethers. More preferably, the second organic solvent A contains at least one alkylene glycol and at least one alkylene glycol ether. Furthermore, it is even more preferable that the second organic solvent A contains at least one alkylene glycol and at least two alkylene glycol ethers. The alkylene glycol and alkylene glycol ether 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.

[0125] If the colored ink contains an organic solvent comprising 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, the drying properties of the colored ink on the substrate are improved. This improves the lamination strength and adhesion.

[0126] Furthermore, if the colored ink contains an organic solvent comprising 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 colored ink on the substrate are further improved, resulting in better lamination suitability and adhesion.

[0127] When the colored ink contains alkylene glycol alkyl ether and alkylene glycol alkyl ether, 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, even more preferably 15.0 or less, even more preferably 10.0 or less, particularly preferably 8.0 or less, and especially more preferably 6.0 or less, from the viewpoint of further improving laminate strength and adhesion. The lower limit of the above mass ratio is not particularly limited, but from the viewpoint of re-dispensing properties, it is preferably 1.0, more preferably 2.0, even more preferably 3.0, and even more preferably 4.0.

[0128] The colored ink may contain, in addition to the second organic solvent A, an organic solvent with a boiling point greater than 200°C and 240°C or less (hereinafter referred to as "second organic solvent B"), and may also contain an organic solvent with a boiling point greater than 240°C (hereinafter referred to as "second organic solvent C").

[0129] 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 colored ink is preferably 90% by mass or more, and preferably 95% by mass or more. The above proportion may also be 100% by mass. That is, all of the organic solvent contained in the colored ink may be an organic solvent consisting of the second organic solvent A and the second organic solvent B, or the second organic solvent B alone. Examples of the first organic solvent B include diethylene glycol monobutyl ether, dipropylene glycol, and 1,2-hexanediol.

[0130] From the viewpoint of further improving the lamination strength and adhesion of image recordings, it is preferable that the proportion of the second organic solvent C in the organic solvent contained in the colored ink is 10% by mass or less. The above proportion may be 0% by mass. In other words, the second organic solvent C may not be contained in the colored ink. Examples of the second organic solvent C include diethylene glycol and triethylene glycol.

[0131] The weighted average SP value of the organic solvents contained in the colored ink is 28 MPa. 1 / 2 The following is preferable. In particular, both the white ink and the colored ink have a weighted average SP value of 28 MPa for the organic solvent contained in each ink. 1 / 2 The following is preferable:

[0132] The weighted average SP value of the organic solvents contained in the colored ink is calculated using the same method as the weighted average SP value of the organic solvents contained in the white ink.

[0133] The weighted average SP value of the organic solvents contained in the colored ink is 28 MPa. 1 / 2 The following conditions improve the lamination strength of the image recording. The above weighted average value is 27 MPa from the perspective of lamination strength. 1 / 2 The following is more preferable. The lower limit of the above weighted average value is 25.5 MPa from the viewpoint of discharge performance and re-discharge performance. 1 / 2 It is preferable that this be the case.

[0134] (water) The colored ink prepared in the colored ink preparation process contains water. The water content is not particularly limited, but is, for example, 40% to 70% by mass.

[0135] (Pigment dispersant) The colored ink prepared in the colored ink preparation step preferably contains a pigment dispersant in order to disperse the colored pigment in water. However, if a self-dispersing pigment that can disperse in water even without a pigment dispersant is used as the colored pigment, the colored ink does not need to contain a pigment dispersant.

[0136] The form of the pigment dispersant contained in the colored ink is not particularly limited and may be a random polymer, a block polymer, or a graft polymer. Furthermore, the pigment dispersant contained in the colored ink may be a polymer having a cross-linked structure. Among these, it is preferable that the pigment dispersant contained in the colored ink be a polymer having a cross-linked structure. When the pigment dispersant is a polymer having a cross-linked structure, it is considered less likely to detach from the surface of the colored pigment. As a result, the dispersion stability of the colored pigment is high. Since the organic solvent volatilizes easily after the colored ink lands on a non-permeable substrate, the laminate strength is further improved.

[0137] When the pigment dispersant contained in the colored ink is a polymer having a cross-linked structure, the preferred embodiment of the polymer having a cross-linked structure is the same as the preferred embodiment when the pigment dispersant contained in the white ink is a polymer having a cross-linked structure.

[0138] The mixing ratio of the coloring pigment to the pigment dispersant is preferably 1:0.06 to 1:3 by mass, more preferably 1:0.125 to 1:2, and even more preferably 1:0.125 to 1:1.5.

[0139] (Resin particles) The colored ink prepared in the colored ink preparation step preferably contains at least one type of resin particle from the viewpoint of improving the lamination strength of the image recording material. The colored ink preferably contains resin particles, which are particles made of resin, in addition to the pigment dispersant.

[0140] The preferred embodiment of the resin particles contained in the colored ink is the same as the preferred embodiment of the resin particles contained in the white ink described above.

[0141] If the colored ink contains resin particles, the resin particle content 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 still more preferably 2% to 6% by mass, based on the total amount of the colored ink.

[0142] (Additives) The colored ink prepared in the colored ink preparation step may contain additives such as surfactants, co-sensitizers, UV absorbers, antioxidants, fade inhibitors, conductive salts, and basic compounds, as needed.

[0143] (Physical properties) The pH of the colored ink is preferably 7 to 10, and more preferably 7.5 to 9.5, from the viewpoint of improving ejection stability. The pH is measured at 25°C using a pH meter, for example, using a pH meter (model number "HM-31") manufactured by Toa DKK.

[0144] The viscosity of the colored ink is preferably 0.5 mPa·s to 30 mPa·s, more preferably 2 mPa·s to 20 mPa·s, preferably 2 mPa·s to 15 mPa·s, and even more preferably 3 mPa·s to 10 mPa·s. The viscosity is measured at 25°C using a viscometer, for example, using a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

[0145] The surface tension of the colored ink is preferably 60 mN / m or less, 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 at 25°C using a surface tensimeter, for example, by the plate method using an automatic surface tensimeter (product name "CBVP-Z") manufactured by Kyowa Interface Science Co., Ltd.

[0146] <Image recording process> The image recording method disclosed herein includes a step of recording an image by applying white ink and colored ink to a non-permeable substrate (hereinafter referred to as the "image recording step"). In the image recording step, in the region where the area to which the white ink is applied and the area to which the colored ink is applied overlap in a plan view, the total mass of the first organic solvent and the second organic solvent applied per unit area is 5.5 g / m². 2 The following applies, and the amount of white pigment applied per unit area is 0.4 g / m². 2 The image will be recorded under the above conditions.

[0147] (Non-permeable base material) In this disclosure, non-permeable substrates are defined as having a 24-hour water absorption rate of 2.5% or less, as measured in accordance with ASTM D570-98 (2018). Here, the unit of water absorption rate, "%", is based on mass. The above water absorption rate is preferably 1.0% or less, and more preferably 0.5% or less.

[0148] Examples of materials for non-permeable substrates include 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 acetal, nylon, acrylic resin, etc.).

[0149] The material of the non-permeable substrate is preferably a resin. In particular, from the standpoint of versatility, the material of the non-permeable substrate is preferably polypropylene, polyethylene, polyethylene terephthalate, nylon, acrylic resin, or polyvinyl chloride.

[0150] The shape of the non-permeable substrate is preferably in the form of a sheet (film) or a plate. Examples of non-permeable substrates having such shapes 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.

[0151] Examples of non-permeable resin substrates include resin sheets (resin films), specifically, flexible packaging materials for packaging food products, and panels for floor guidance in mass retail stores.

[0152] In addition to sheet-like (film-like) or plate-like non-permeable substrates, examples of non-permeable substrates include textiles and nonwoven fabrics formed from non-permeable fibers.

[0153] 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.

[0154] Impermeable substrates may be subjected to hydrophilic treatment. Examples of hydrophilic treatments include, but are not limited to, corona treatment, plasma treatment, flame treatment, heat treatment, abrasion treatment, light irradiation treatment (e.g., UV treatment), and fire treatment. Corona treatment can be performed, for example, using a Corona Master (product name "PS-10S", manufactured by Shinko Electric Instruments Co., Ltd.). The conditions for corona treatment should be appropriately selected depending on the type of impermeable substrate.

[0155] The non-permeable substrate may be heated before applying the white ink and colored ink. The heating temperature can be set appropriately depending on the type of non-permeable substrate, but it is preferable to heat the non-permeable substrate to 30°C to 70°C, and more preferably to 30°C to 60°C.

[0156] (Order of application of white ink and colored ink) 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 colored ink may be applied to the non-permeable substrate first, followed by the white ink, or the white ink may be applied first, followed by the colored ink. If the non-permeable substrate is transparent and the application is for reverse printing, it is preferable to apply the colored ink to the non-permeable substrate first, followed by the white ink. That is, the image recording method of the present disclosure preferably includes the steps of applying colored ink to a non-permeable substrate and applying white ink to the colored ink film formed by the application of the colored ink.

[0157] (Conditions for providing white ink and colored ink) In the image recording process, an image is recorded by applying white ink and colored ink respectively, under conditions where an overlapping area (hereinafter referred to as the "overlapping area") occurs in a planar view between the area to which white ink is applied and the area to which colored ink is applied.

[0158] In the image recording process, white ink and colored ink may be applied under conditions that create overlapping areas and areas that do not overlap.

[0159] For example, a patterned colored ink film may be formed by applying colored ink in a patterned manner onto a non-permeable substrate, and then a white ink film may be formed by applying white ink (for example, in a solid color) to the area that spans the colored ink film and the area other than the colored ink film (for example, the area that covers the entire colored ink film and its surroundings). In this case, the area where the colored ink film exists corresponds to the "overlapping area" mentioned above, and the area where the colored ink film does not exist but the white ink film exists, and the area where neither the colored ink film nor the white ink film exists, correspond to the "area other than the overlapping area" mentioned above.

[0160] (Mass amount of white ink and colored ink applied) In the image recording process, the total amount of the first and second organic solvents applied per unit area in the overlapping region is 5.5 g / m². 2The following applies, and the amount of white pigment applied per unit area is 0.4 g / m². 2 The image will be recorded under the above conditions.

[0161] In the overlapping region, the total mass of the first and second organic solvents applied per unit area is 5.5 g / m². 2 The following conditions ensure image intensity and improve adhesion between the image and the laminating substrate when white and colored inks are applied to a non-permeable substrate. As a result, superior lamination strength is achieved.

[0162] In the overlapping region, the amount of white pigment applied per unit area is 0.4 g / m². 2 As a result, the white pigment retains the surrounding organic solvent, ensuring image intensity and improving adhesion between the image and the laminating substrate. Consequently, it exhibits superior lamination strength. Furthermore, in the overlapping region, the amount of white pigment applied per unit area is 0.4 g / m². 2 The above specifications result in excellent concealment.

[0163] Mass of the first organic solvent applied per unit area in the overlapping region (unit: g / m²) 2 The product of the amount of white ink applied per unit area in the overlapping region and the content (mass%) of the first organic solvent relative to the total amount of white ink is calculated. Mass of the second organic solvent applied per unit area in the overlapping region (unit: g / m²) 2 The product of the amount of colored ink applied per unit area in the overlapping region and the content (mass%) of the second organic solvent relative to the total amount of colored ink is calculated. The amount of white pigment applied per unit area in the overlapping region (unit: g / m²) 2 The product of the amount of white ink applied per unit area in the overlapping region and the amount of white pigment (mass%) relative to the total amount of white ink is calculated.

[0164] In the overlapping region, the amount of white ink applied per unit area and the amount of colored ink applied per unit area (in units of g / m²) 2This is calculated based on the resolution, image halftone dot density, and drop weight per drop, respectively.

[0165] From the perspective of further improving laminate strength, the total mass of the first and second organic solvents applied per unit area in the overlapping region should be 5.5 g / m². 2 Preferably, it is 5.0 g / m 2 It is more preferable that the following conditions apply: 4.5 g / m 2 It is even more preferable that the following conditions are met. The lower limit of the total amount of added mass is 3.0 g / m² from the viewpoint of opacity. 2 It is preferable that this be the case.

[0166] From the perspective of further improving laminate strength and opacity, the amount of white pigment applied per unit area in the overlapping region is 0.8 g / m². 2 Preferably, it is 1.0 g / m 2 It is more preferable that the above amount is achieved. The upper limit of the above-mentioned imparted mass is 1.2 g / m³ from the viewpoint of dischargeability and re-dischargeability. 2 It is preferable that this be the case.

[0167] (Method of applying white ink) The method of applying white ink is not particularly limited and includes known methods such as coating, immersion, and inkjet recording. Among these, from the viewpoint of recording high-resolution images, it is preferable to apply the white ink using an inkjet recording method.

[0168] There are no particular restrictions on the ink ejection method in the inkjet recording method, and any known method may be used, such as a charge control method that ejects ink using electrostatic attraction, a drop-on-demand method (pressure pulse method) that utilizes the vibration pressure of a piezoelectric element, an acoustic inkjet method that converts an electrical signal into an acoustic beam and irradiates the ink to eject ink using the radiation pressure, and a thermal inkjet (bubble jet®) method that heats the ink to form bubbles and utilizes the resulting pressure.

[0169] As an inkjet recording method, the method described in Japanese Patent Publication No. 54-59936 is particularly effective, as it involves the ink undergoing a rapid volume change due to the action of thermal energy, and the force resulting from this state change ejects the ink from the nozzle. As an inkjet recording method, the method described in paragraphs 0093 to 0105 of Japanese Patent Publication No. 2003-306623 can also be applied.

[0170] Ink is applied to a non-permeable substrate using an inkjet recording method by ejecting ink from the nozzles of the inkjet head.

[0171] Inkjet head systems include the shuttle system, which uses a short serial head to scan the recording medium in the width direction while recording, and the line system, which uses a line head in which recording elements are arranged to cover the entire width of one side of the recording medium.

[0172] In the line method, image recording can be performed across the entire surface of the recording medium by scanning it in a direction intersecting the arrangement direction of the recording elements. The line method eliminates the need for a transport system such as a carriage that scans the short head, which is required in the shuttle method. Furthermore, compared to the shuttle method, the line method eliminates the need for complex scanning control of the carriage movement and the recording medium, as only the recording medium moves. For this reason, the line method enables faster image recording compared to the shuttle method.

[0173] Ink application is preferably carried out using an inkjet head having 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 equal to 2.54 cm.

[0174] From the viewpoint of obtaining high-definition images, the amount of ink droplets ejected from the nozzles of the inkjet head is preferably 1 pL (picoliters) to 10 pL, and more preferably 1.5 pL to 6 pL. Furthermore, from the viewpoint of improving image uniformity and the continuity of continuous gradations, it is also effective to eject different droplet amounts in combination.

[0175] (Method of applying colored ink) The method for applying the colored ink is not particularly limited and includes known methods such as coating, immersion, and inkjet recording. Among these, it is preferable to apply the colored ink using an inkjet recording method from the viewpoint of being able to record high-resolution images. Details of the inkjet recording method are the same as those for the inkjet recording method for applying the white ink.

[0176] <Pre-treatment solution preparation process> The image recording method disclosed herein further includes a step of preparing a pretreatment solution containing a coagulant and water (hereinafter referred to as the "pretreatment solution preparation step"), and in the image recording step, it is preferable to apply the pretreatment solution to a non-permeable substrate, and then apply white ink and colored ink, respectively, to record an image.

[0177] By applying a pretreatment solution to a non-permeable substrate beforehand, the components in the white ink and colored ink are aggregated by the flocculant contained in the pretreatment solution. In particular, the flocculant effect is high when the white ink and colored ink contain pigment dispersants and resin particles. The adhesion between the non-permeable substrate and the white ink film and colored ink film is improved, and the laminate strength is further enhanced.

[0178] (Flocculant) The pretreatment solution prepared in the pretreatment solution preparation step preferably contains a flocculant. The flocculant is not particularly limited as long as it is a component that floccates the components in the white ink and the colored ink. The flocculant is preferably at least one selected from the group consisting of polyvalent metal compounds, organic acids, metal complexes, and cationic polymers, and more preferably contains an organic acid.

[0179] -Polyvalent metal compounds- Examples of polyvalent metal compounds include salts of alkaline earth metals in Group 2 of the periodic table (e.g., magnesium, calcium), transition metals in Group 3 of the periodic table (e.g., lanthanum), metals in Group 13 of the periodic table (e.g., aluminum), and lanthanides (e.g., neodymium).

[0180] These metal salts are preferably salts, nitrates, chlorides, or thiocyanates of organic acids, as described later.

[0181] In particular, 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; calcium chloride, magnesium chloride, or a calcium or magnesium salt of thiocyanate.

[0182] It is preferable that the polyvalent metal compound dissociates into polyvalent metal ions and counterions in the pretreatment solution, at least a portion of which is present.

[0183] -Organic acid- Examples of organic acids include organic compounds that have an acidic group.

[0184] Examples of acidic groups include phosphoric acid groups, phosphonic acid groups, phosphinic acid groups, sulfate groups, sulfonic acid groups, sulfinic acid groups, and carboxyl groups.

[0185] In particular, from the viewpoint of ink aggregation rate, the acidic group is preferably a phosphoric acid group or a carboxyl group, and more preferably a carboxyl group.

[0186] It is preferable that at least a portion of the acidic group is dissociated in the pretreatment solution.

[0187] Examples of organic compounds having 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, pyrrone carboxylic acid, pyrrole carboxylic acid, furanic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, and nicotinic acid.

[0188] In particular, from the viewpoint of ink aggregation rate, the organic compound having a carboxyl group is preferably a divalent or higher carboxylic acid (hereinafter also referred to as a polyvalent carboxylic acid), and more preferably a dicarboxylic acid.

[0189] 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.

[0190] Organic acids with a low pKa (e.g., 1.0 to 5.0) are preferable. This allows for a reduction in the dispersion stability of particles such as pigments and resin particles in ink, which are dispersed and stabilized by weakly acidic functional groups such as carboxyl groups, by bringing them into contact with an organic acid with an even lower pKa.

[0191] The organic acid is preferably low in pKa, highly soluble in water, and has a valency of 2 or higher. Furthermore, it is more preferable that the organic acid has high buffering capacity in a pH range lower than the pKa of the functional group (e.g., carboxyl group) that disperses and stabilizes the particles in the ink.

[0192] -Metal complex- The metal complex preferably contains at least one metal element selected from the group consisting of zirconium, aluminum, and titanium.

[0193] The metal complex is preferably a metal complex that includes at least one selected from the group consisting of acetate, acetylacetonate, methylacetoacetate, ethylacetoacetate, octylene glycolate, butoxyacetylacetonate, lactate, lactate ammonium salt, and triethanolamine as a ligand.

[0194] The metal complex may be a commercially available product. Various organic ligands, especially various polydentate ligands capable of forming metal chelate catalysts, are commercially available. Therefore, the metal complex may be a metal complex prepared by combining a commercially available organic ligand with a metal.

[0195] Examples of metal complexes include zirconium tetraacetylacetonate (e.g., "Orgatics ZC-150" manufactured by Matsumoto Fine Chemicals), zirconium monoacetylacetonate (e.g., "Orgatics ZC-540" manufactured by Matsumoto Fine Chemicals), zirconium bisacetylacetonate (e.g., "Orgatics ZC-550" manufactured by Matsumoto Fine Chemicals), zirconium monoethylacetoacetate (e.g., "Orgatics ZC-560" manufactured by Matsumoto Fine Chemicals), zirconium acetate (e.g., "Orgatics ZC-115" manufactured by Matsumoto Fine Chemicals), and titanium diisopropoxybis(acetylacetonate) (e.g., "Orgatics ZC-150" manufactured by Matsumoto Fine Chemicals). TC-100), Titanium tetraacetylacetonate (e.g., Matsumoto Fine Chemicals' "Orgatics TC-401"), Titanium dioctyloxybis(octylene glycolate) (e.g., Matsumoto Fine Chemicals' "Orgatics TC-200"), Titanium diisopropoxybis(ethylacetoacetate) (e.g., Matsumoto Fine Chemicals' "Orgatics TC-750"), Zirconium tetraacetylacetonate (e.g., Matsumoto Fine Chemicals' "Orgatics ZC-700"), Zirconium triputoxymonoacetylacetonate (e.g., Matsumoto Fine Chemicals' "Orgatics ZC-540"), Zirconium monobutoxyacetylacetonate bis(ethylacetoacetate) (e.g., Matsumoto Fine Chemicals' "Orgatics ZC-570), Zirconium dibutoxy bis(ethyl acetoacetate) (e.g., Matsumoto Fine Chemicals' "Orgatics ZC-580"), Aluminum trisacetylacetonate (e.g., Matsumoto Fine Chemicals' "Orgatics AL-80"), Titanium lactate ammonium salt (e.g., Matsumoto Fine Chemicals' "Orgatics TC-300"), Titanium lactate (e.g., Matsumoto Fine Chemicals' "Orgatics TC-310, 315"), Titanium triethanolamine (Matsumoto Fine Chemicals' "Orgatics")Examples include "TC-400") and zirconyl chloride compounds (for example, "Orgatics ZC-126" manufactured by Matsumoto Fine Chemical Co., Ltd.).

[0196] In particular, the metal complex is preferably a titanium lactate ammonium salt (e.g., "Orgatics TC-300" manufactured by Matsumoto Fine Chemical Co., Ltd.), titanium lactate (e.g., "Orgatics TC-310, 315" manufactured by Matsumoto Fine Chemical Co., Ltd.), titanium triethanolamine (e.g., "Orgatics TC-400" manufactured by Matsumoto Fine Chemical Co., Ltd.), or a zirconyl chloride compound (e.g., "Orgatics ZC-126" manufactured by Matsumoto Fine Chemical Co., Ltd.).

[0197] -Cationic polymer- Furthermore, the pretreatment solution may contain one or more cationic polymers as flocculating components. The cationic polymer is preferably a homopolymer of cationic monomers having primary to tertiary amino groups or quaternary ammonium bases, a copolymer of a cationic monomer and a non-cationic monomer, or a condensed polymer. The cationic polymer may be used in the form of a water-soluble polymer or water-dispersible latex particles. Examples of cationic polymers include polyvinylpyridine salts, polyalkylaminoethyl acrylates, polyalkylaminoethyl methacrylates, polyvinylimidazoles, polyethyleneimines, polybiguanides, polyguanides, polyallylamines, and derivatives thereof.

[0198] From the viewpoint of the viscosity of the pretreatment solution, a smaller weight-average molecular weight of the cationic polymer is preferable. When the pretreatment solution is applied to the recording medium by an inkjet recording method, a weight-average molecular weight of 1,000 to 500,000 is preferable, 1,500 to 200,000 is more preferable, and even more preferable is 2,000 to 100,000. A weight-average molecular weight of 1,000 or more is advantageous in terms of aggregation rate. A weight-average molecular weight of 500,000 or less is advantageous in terms of discharge reliability. However, this does not apply when the pretreatment solution is applied to the recording medium by a method other than an inkjet recording method.

[0199] The pretreatment solution may contain only one type of coagulant, or it may contain two or more types.

[0200] The coagulant content 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, based on the total amount of the pretreatment solution.

[0201] (water) The pretreatment solution prepared in the pretreatment solution preparation step preferably contains water. The water content is not particularly limited, but is, for example, 40% to 70% by mass.

[0202] (Organic solvents) The pretreatment solution prepared in the pretreatment solution preparation step may contain an organic solvent, and may also 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 also be simply referred to as the "third organic solvent."

[0203] 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, and more preferably 5% by mass or less. The lower limit of the content of the third organic solvent is not particularly limited and may be 0% by mass. In other words, the pretreatment solution does not have to contain the third organic solvent. When the content of the third organic solvent is 15% by mass or less, image intensity is ensured even in overlapping areas, and the adhesion between the image and the laminating substrate is improved. As a result, the lamination strength is improved. Examples of the third organic solvent include propylene glycol and propylene glycol monomethyl ether.

[0204] (Other ingredients) The pretreatment solution may contain other components besides flocculants and water, as needed. Other components that may be contained in the pretreatment solution include known additives such as resin particles, surfactants, solid wetting agents, colloidal silica, inorganic salts, anti-fading agents, emulsifying stabilizers, penetration enhancers, ultraviolet absorbers, preservatives, antifungal agents, pH adjusters, viscosity adjusters, rust inhibitors, chelating agents, and water-soluble polymer compounds (for example, water-soluble polymer compounds described in paragraphs 0026 to 0080 of Japanese Patent Application Publication No. 2013-001854).

[0205] (Physical properties) The pH of the pretreatment solution is preferably 0.1 to 4.5, and more preferably 0.2 to 4.0, from the viewpoint of the ink aggregation rate. The pH is measured at 25°C using a pH meter, for example, using a pH meter (model number "HM-31") manufactured by Toa DKK.

[0206] The viscosity of the pretreatment solution is preferably 0.5 mPa·s to 10 mPa·s, and more preferably 1 mPa·s to 5 mPa·s, from the viewpoint of the ink coagulation rate. The viscosity is measured using a viscometer at 25°C. The viscosity is measured using a viscometer at 25°C, for example, using a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

[0207] The surface tension of the pretreatment solution is preferably 60 mN / m or less, 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 at a temperature of 25°C. The surface tension is measured at 25°C using a surface tensimeter, for example, by the plate method using an automatic surface tensimeter (product name "CBVP-Z") manufactured by Kyowa Interface Science Co., Ltd.

[0208] (Order of application: pretreatment solution, white ink, and colored ink) In the image recording process, a pretreatment solution is applied to a non-permeable substrate, followed by the application of white ink and colored ink, respectively. The order in which the white ink and colored ink are applied is not particularly limited; the colored ink may be applied to the non-permeable substrate before the white ink, or the white ink may be applied before the colored ink. If the non-permeable substrate is transparent and the application is for reverse printing, it is preferable to apply the pretreatment solution, colored ink, and white ink to the non-permeable substrate in this order. That is, the image recording method of the present disclosure preferably includes the steps of applying a pretreatment solution to a non-permeable substrate, applying colored ink to the non-permeable substrate to which the pretreatment solution has been applied, and applying white ink to the colored ink film formed by the application of the colored ink.

[0209] (Conditions for applying pretreatment solution, white ink, and colored ink) In the image recording process, the image is recorded by applying white ink and colored ink under conditions where an overlapping region (hereinafter referred to as "overlapping region K") is created in a planar view, where the region to which the pretreatment solution is applied, the region to which white ink is applied, and the region to which colored ink is applied.

[0210] In the image recording process, a pretreatment solution, white ink, and colored ink may be applied under conditions that create overlapping regions and regions that do not overlap.

[0211] For example, a colored ink is applied in a pattern on a non-permeable substrate to which a pretreatment liquid has been applied to form a patterned colored ink film. Then, a white ink may be applied (e.g., in a solid manner) to a region that straddles the colored ink film and the region other than the colored ink film (e.g., a region that covers the entire colored ink film and its periphery) to form a white ink film. In this case, the region where the colored ink film exists corresponds to the above "overlap region", and the region where the colored ink film does not exist but the white ink film exists, and the region where neither the colored ink film nor the white ink film exists correspond to the above "regions other than the overlap region".

[0212] (Application mass of pretreatment liquid, white ink, and colored ink) In the image recording step, in the overlap region K, the total application mass of the first organic solvent, the second organic solvent, and the third organic solvent per unit area is 5.5 g / m 2 It is preferable to record an image under the following conditions. When the pretreatment liquid does not contain the third organic solvent, in the image recording step, in the overlap region K, the total application mass of the first organic solvent and the second organic solvent per unit area is 5.5 g / m 2 Record an image under the following conditions.

[0213] In the overlap region K, the total application mass of the first organic solvent, the second organic solvent, and the third organic solvent per unit area is 5.5 g / m 2 When the white ink and the colored ink are applied on the non-permeable substrate to which the pretreatment liquid has been applied, if it is as follows, the image intensity is ensured and the adhesion between the image and the laminate substrate is improved. As a result, the laminate strength is excellent.

[0214] The application mass of the third organic solvent per unit area in the overlap region K (unit: g / m 2 ) is calculated by the product of the application mass of the pretreatment liquid per unit area in the overlap region K and the content (mass%) of the third organic solvent in the total amount of the pretreatment liquid.

[0215] From the perspective of further improving the lamination strength, in the overlapping region K, the total applied mass of the first organic solvent, the second organic solvent, and the third organic solvent per unit area is 5.5 g / m 2 or less, preferably 5.0 g / m 2 or less, more preferably 4.5 g / m 2 or less. The lower limit of the total applied mass is, for example, 2.0 g / m 2 and, from the perspective of lamination strength, preferably 3.0 g / m 2 and more preferably 3.5 g / m 2 [[ID=?]]is more preferred.

[0216] In the image recording step, it is preferable to record an image under the condition that the applied mass of the third organic solvent per unit area in the overlapping region K is 0.2 g / m 2 or less. When the pretreatment liquid does not contain the third organic solvent, the applied mass of the third organic solvent per unit area in the overlapping region K is 0 g / m 2 becomes.

[0217] From the perspective of further improving the lamination strength, in the overlapping region K, the applied mass of the third organic solvent is preferably 0.08 g / m 2 or less. The lower limit of the total applied mass may be 0 g / m 2 .

[0218] (Method for applying the pretreatment liquid) The method for applying the pretreatment liquid is not particularly limited, and known methods such as a coating method, a dipping method, and an inkjet recording method can be mentioned.

[0219] Examples of the coating method include known coating methods using a bar coater, an extrusion die coater, an air doctor coater, a blade coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, etc. [[ID=?]]

[0220] [[ID=?]] It should be noted that there seems to be an error in the original text where "であることがより好ましい。 " is translated as "[[ID=?]]is more preferred. " because the original text is incomplete. I've translated it as accurately as possible based on the available content. Also, for the tags - , they are preserved as per the instruction. If there are any specific requirements or corrections regarding these tags, please let me know.After applying the pretreatment solution, the pretreatment solution applied to the non-permeable substrate may be heated and dried. Means for heating and drying the pretreatment solution include known heating means such as heaters, known blowing means such as dryers, and means combining these.

[0221] Methods for heating and drying the pretreatment solution include, for example, applying heat with a heater from the side opposite to the side of the non-permeable substrate to which the pretreatment solution has been applied; applying warm air or hot air to the side of the non-permeable substrate to which the pretreatment solution has been applied; applying heat with an infrared heater from the side of the non-permeable substrate to which the pretreatment solution has been applied or from the side opposite to the side to which the pretreatment solution has been applied; and methods combining several of these.

[0222] The heating temperature during the heat drying of the pretreatment solution is preferably 35°C or higher, and more preferably 40°C or higher. There is no particular upper limit to the heating temperature, but 100°C is preferred, 90°C is more preferred, and 70°C is even more preferred.

[0223] The heating and drying time is not particularly limited, but is preferably 0.5 to 60 seconds, more preferably 0.5 to 20 seconds, and even more preferably 0.5 to 10 seconds.

[0224] [Method for manufacturing laminated materials] According to the image recording method of this disclosure, an image recording material comprising an impermeable substrate and an image recorded on the impermeable substrate can be manufactured, which has excellent lamination strength and excellent opacity when a laminating substrate is laminated onto the image.

[0225] Therefore, the image recording method of the present disclosure is suitably used in the manufacture of a laminate body comprising the above-mentioned image recording material and a laminating substrate laminated to the side of the image recording material on which the image is recorded.

[0226] A method for manufacturing a laminate, which is one embodiment of the present disclosure, includes the steps of: recording an image on a non-permeable substrate using the image recording method of the present disclosure; and laminating a laminating substrate onto the side on which the image is recorded to obtain a laminate.

[0227] According to a method for manufacturing a laminate, which is one embodiment of the present disclosure, it is possible to manufacture a laminate that has excellent lamination strength between the image recording material and the laminating substrate, as well as excellent opacity.

[0228] For the process of recording images, refer to the image recording method of this disclosure described above. The process of obtaining a laminate is to laminate a laminating substrate onto the side on which the image is recorded.

[0229] The laminating substrate is preferably a resin substrate. The resin substrate is not particularly limited, but examples include a substrate made of a thermoplastic resin.

[0230] Examples of resin substrates include substrates made by molding thermoplastic resin into a sheet. The resin substrate preferably contains polypropylene, polyethylene terephthalate, nylon, polyethylene, or polyimide.

[0231] 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, and more preferably 10 μm to 100 μm.

[0232] In the process of obtaining a laminate, the laminating substrate may be laminated directly onto the side on which the image is recorded, or it may be laminated via another layer (e.g., an adhesive layer).

[0233] When laminating a substrate for lamination directly onto the side on which the image is recorded, lamination can be carried out by known methods such as heat bonding or heat fusion.

[0234] In addition, when laminating a base material for lamination via an adhesive layer on the side where an image is recorded, the lamination can be carried out, for example, by applying an adhesive on the side where the image is recorded, placing the base material for lamination thereon, and then bonding the image recording object and the base material for lamination together.

[0235] In addition, when laminating via an adhesive layer on the side where an image is recorded, the lamination can also be carried out by a method such as extrusion lamination (i.e., sandwich lamination).

[0236] The adhesive layer preferably contains an isocyanate compound. When the adhesive layer contains an isocyanate compound, the adhesion between this adhesive layer and the image is further improved, so that the lamination strength can be further improved.

[0237] [Image recording object] An image recording object according to one embodiment of the present disclosure includes a non-permeable base material and an image recorded on the non-permeable base material. The image includes a white ink layer containing a white pigment and contacting the non-permeable base material, and a colored ink layer containing a colored pigment other than the white pigment and contacting the white ink layer, and includes a region where the white ink layer and the colored ink layer overlap in plan view. In the white ink layer, the mass of the white pigment per unit area is 0.4 g / m 2 or more.

[0238] An image recording object according to one embodiment of the present disclosure has excellent lamination strength when a base material for lamination is laminated on the image. In addition, the image recording object of the present disclosure has excellent concealability.

[0239] An image recording object according to one embodiment of the present disclosure is preferably obtained by the image recording method of the present disclosure. Preferred embodiments of each component in the image recording object according to one embodiment of the present disclosure are the same as the preferred embodiments of each component described in the section of the image recording method of the present disclosure.

[0240] [Laminated body] One embodiment of the present disclosure is a laminate comprising the image recording material of the present disclosure described above, and a laminating substrate laminated onto the image of the image recording material. The laminate of the present disclosure has excellent opacity and lamination strength.

[0241] In a laminated body according to one embodiment of the present disclosure, the laminating substrate may be directly laminated to the side of the image recording material on which the image is recorded, or it may be laminated via another layer (adhesive layer).

[0242] A laminate body according to one embodiment of the present disclosure is preferably manufactured by a method for manufacturing a laminate body according to one embodiment of the present disclosure.

[0243] Preferred embodiments of the laminating substrate and adhesive layer are the same as those described in the section on the method for manufacturing the laminate.

[0244] [Ink Set] (Aspect 1) An ink set in one embodiment of the present disclosure 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, an organic solvent, and water, wherein the pigment dispersant is a polymer or block polymer having a crosslinked structure, and both the white ink and the colored ink have a weighted average value of the solubility parameters of the organic solvent contained in each ink of 28 or less.

[0245] (Aspect 2) An ink set in one embodiment of the present disclosure 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 crosslinked structure, and the organic solvent includes 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.

[0246] (Aspect 3) An ink set in one embodiment of the present disclosure 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 crosslinked structure, and the organic solvent includes 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.

[0247] By using an ink set, which is one form of this disclosure, an image recording material with excellent opacity and lamination strength can be obtained.

[0248] Preferred embodiments of each component in an ink set, which is one embodiment of this disclosure, are the same as preferred embodiments of each component described in the section on image recording methods of this disclosure. [Examples]

[0249] The present disclosure will be further described below with reference to examples, but the present disclosure is not limited to the following examples unless it exceeds the spirit of the disclosure.

[0250] -White pigment dispersion A (dispersion by random polymer)- 965 g of dipropylene glycol was added to a 5000 mL three-necked flask equipped with a stirrer and condenser, and heated to 85°C under a nitrogen atmosphere. Solution I was prepared 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 was prepared by dissolving 17.69 g of t-butylperoxy-2-ethylhexanoate (product name "Perbutyl O", manufactured by NOF Corporation) in 221.17 g of dipropylene glycol. Solution I was added dropwise to the three-necked flask over 4 hours, and Solution II over 5 hours. After the dropwise addition was complete, the reaction was allowed to continue for another 2 hours. The disappearance of monomers was confirmed by 1H-NMR. The resulting reaction solution was heated to 70°C, and 248.02 g of 50% potassium hydroxide aqueous solution was added. Then, 107.48 g of dipropylene glycol and 75.52 g of pure water were added and the mixture was stirred to obtain a 37% random polymer solution. This random polymer was designated as pigment dispersant P1. The structural units constituting the obtained random polymer were confirmed by 1H-NMR. The weight-average molecular weight (Mw) was also determined by GPC. The weight-average molecular weight (Mw) of the obtained pigment dispersant P1 was 8400, and the acid value was 221.7 mgKOH / g.

[0251] 150 parts by mass of pigment dispersant P1 was dissolved in water to prepare a polymer aqueous solution with a concentration of pigment dispersant P1 of approximately 25% by mass. 96 parts by mass of the polymer aqueous solution was mixed with 300 parts by mass of CI Pigment White 6 (product name "JR-405", titanium dioxide, manufactured by Teika Co., Ltd.), a white pigment, and 270 parts by mass of water to obtain a mixture. 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 Toa DKK Co., Ltd.). Next, the neutralized mixture was subjected to a dispersion treatment for 3 hours using a bead mill (bead diameter: 0.1 mmφ, zirconia beads). This yielded a white pigment dispersion A (uncrosslinked dispersion) in which the white pigment was dispersed by pigment dispersant P1. The pigment concentration of the uncrosslinked dispersion was 45% by mass, and the concentration of pigment dispersant P1 was 3.6% by mass.

[0252] -White pigment dispersion B (dispersion by crosslinked polymer)- A polymer aqueous solution with a pigment dispersant P1 concentration of approximately 25% by mass was mixed with 300 parts by mass of CI Pigment White 6 (product name "JR-405", titanium dioxide, manufactured by Teika Co., Ltd.), a white pigment, and 180 parts by mass of water to obtain a mixture. Potassium hydroxide aqueous solution was added to the obtained 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 Toa DKK Co., Ltd.). Next, the neutralized mixture was subjected to a dispersion treatment for 3 hours using a bead mill (bead diameter: 0.1 mmφ, zirconia beads). This yielded a white pigment dispersion B precursor (uncrosslinked dispersion) in which the white pigment was dispersed by the pigment dispersant P1. The pigment concentration of dispersion B precursor was 45% by mass. To 136 parts by mass of a white pigment dispersion B precursor (uncrosslinked dispersion), 2.70 parts by mass of trimethylolpropane polyglycidyl ether (product name "Denacol EX-321", manufactured by Nagase ChemteX Corporation) and 29.5 parts by mass of an aqueous boric acid solution (boric acid concentration: 4% by mass) were added as crosslinking agents. The mixture was reacted at 70°C for 6 hours and then cooled to 25°C. This resulted in a white pigment dispersion (crosslinked dispersion) in which the pigment dispersant P1 was crosslinked and the white pigment was dispersed by the pigment dispersant P1a. Pigment dispersant P1a is a polymer in which the pigment dispersant P1 has been crosslinked by the crosslinking agent. Ion-exchanged water was added to the crosslinked dispersion to achieve a pigment concentration of 15% by mass. The cross-linked dispersion was ultrafiltered through an ultrafiltration apparatus (cross-flow ultrafilter (UF), manufactured by Sartorius) equipped with a polyethersulfone (PESU) membrane (pore size: 0.1 μm) at a flow rate of 600 mL per minute. The liquid temperature was adjusted to 25°C, and ultrafiltration was performed eight times, with each ultrafiltration cycle equal to 1x the volume of the initial liquid. Ion-exchanged water was added to achieve a pigment concentration of 45% by mass. This yielded white pigment dispersion B. The acid value of the pigment dispersant P1a (cross-linked polymer) in white pigment dispersion B was 105 mg KOH / g. The concentration of pigment dispersant P1a was 3.6% by mass. The concentration of pigment dispersant P1a is calculated by subtracting the pigment concentration from the solid content concentration obtained by vacuum drying of pigment dispersion B.

[0253] -White pigment dispersion C (dispersion by block polymer)- A block polymer was synthesized as a pigment dispersant, referring to Synthesis Example 8 in Japanese Patent Publication No. 2015-83688. Details are shown below. In a 1 L separable flask equipped with a stirrer, backflow condenser, thermometer, and nitrogen inlet tube, 266 parts by mass of diethylene glycol dimethyl ether, 6.2 parts by mass of 2-iod-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 azobisdimethylisovaleronitrile, and 0.7 parts by mass of 2-t-butyl-4,6-dimethylphenol were added, and the mixture was stirred while flowing nitrogen. Next, the temperature of the mixture in the reaction apparatus (reaction temperature) was 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 polymerization solution A was sampled and its solid content was measured, which was 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 was measured by GPC and found to be 7,500. The acid value of this MMA / AA / CHMA copolymer was 101.0 mgKOH / g.

[0254] 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-dimethylvaleronitrile), manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (0.3 parts by mass) was added to polymerization solution A, and polymerization was carried out at 70°C for 3 hours to obtain polymerization solution B containing a block polymer. The obtained block polymer is a block polymer containing block A, which is an MMA / AA / CHMA copolymer, and block B, which is a BzMA homopolymer. The solid content of polymerization solution B was measured 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 mgKOH / g. 136.4 parts by mass of the obtained block polymer, 163.6 parts by mass of butyl carbitol, and 450 parts by mass of CI Pigment White 6 (trade name "JR-405", titanium dioxide, manufactured by Teika Co., Ltd.) as a white pigment were blended and stirred with a disperser. Next, the white pigment was thoroughly dispersed using a horizontal media disperser to obtain an oil-based pigment dispersion. The average particle size of the white pigment dispersed in the oil-based pigment dispersion was 290 nm. The viscosity of the oil-based pigment dispersion was 86.3 m3 Pa·s. Next, 700 parts by mass of the above oil-based pigment dispersion was stirred with a disperser, and a mixture consisting of 4.0 parts by mass of potassium hydroxide and 341 parts by mass of water was gradually added to neutralize and undergo phase change. After that, the white pigment was thoroughly dispersed using a horizontal media disperser to obtain a pigment dispersion. Next, the obtained pigment dispersion was subjected to ultrafiltration using an ultrafiltration apparatus (cross-flow type ultrafilter (UF), manufactured by Sartorius) by flowing deionized water 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 pass representing 1x the volume of the initially charged liquid. Deionized water was added to obtain a white pigment dispersion C with a pigment concentration of 45% by mass and a pigment dispersant (block polymer) concentration of 3.6% by mass. The concentration of the block polymer is the value obtained by subtracting the pigment concentration from the solid content concentration obtained by vacuum drying of pigment dispersion C.

[0255] -White pigment dispersion D (self-dispersion)- 100 g of titanium dioxide (number mean primary particle size: 130 nm to 350 nm, median: 240 nm) was added to 3,000 mL of 2.5 N sodium hypochlorite solution and stirred at 60°C and 300 rpm for 10 hours. The reaction solution obtained was a white pigment in which carboxyl groups were attached to the surface of the titanium dioxide by oxidation treatment. The obtained reaction solution was filtered, and the filtered white pigment was neutralized with sodium hydroxide solution and ultrafiltration was performed. Next, ultrafiltration was performed using ion-exchanged water with a dialysis membrane, and then ultrasonic dispersion was performed using an ultrasonic disperser to obtain a white pigment dispersion D with a pigment concentration of 45% by mass.

[0256] -Preparation of white inks W1~W31- For white inks W1-W29 and W31, a white pigment dispersion (one of the white pigment dispersions A-C) was mixed with an organic solvent, resin particles, and water to prepare the white ink so that the content of each component was as shown in Tables 1-3 (mass %). In Tables 1-3, white pigment dispersion A was used when the dispersant was a random polymer, white pigment dispersion B was used when the dispersant was a crosslinked polymer, and white pigment dispersion C was used when the dispersant was a block polymer. For white ink W30, a white pigment dispersion D, an organic solvent, resin particles, and water were mixed to prepare the white ink so that the content of each component was as shown in Table 3. The water content is calculated as the remaining amount when the total amount of white ink reaches 100% by mass.

[0257] In the table, the abbreviations for each organic solvent are as follows: PGmME: Propylene glycol monomethyl ether PGmEE: Propylene glycol monoethyl ether PGmPE: Propylene glycol monopropyl ether PGmBE: Propylene glycol monobutyl ether EGmPE: Ethylene glycol monopropyl ether EGmBE: Ethylene glycol monobutyl ether PG: Propylene glycol DPGmME: Dipropylene glycol monomethyl ether DEGmEE: Diethylene glycol monoethyl ether EG: Ethylene glycol DEGmBE: Diethylene glycol monobutyl ether DPG: Dipropylene glycol 1,2-HD:1,2-Hexanediol DEG: Diethylene glycol TEG: Triethylene glycol

[0258] The resin particles were prepared using the following method. 560.0 g of methyl ethyl ketone was placed in a 2-liter three-necked flask (reaction vessel) equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, and the temperature was raised to 87°C. Then, while maintaining reflux 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-methylpropionate) (product name "V-601", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), a polymerization initiator, was added dropwise at a constant rate so that the addition would be completed in 2 hours. Reflux was maintained until the end of the reaction. After the addition was complete, the mixture was stirred for 1 hour, and then the following procedure (1) was performed on the reaction solution. Step (1) ... A solution consisting of 1.16 g of "V-601" and 6.4 g of methyl ethyl ketone was added and stirred for 2 hours. Next, the above procedure (1) was repeated four times, and then a solution consisting of 1.16 g of "V-601" and 6.4 g of methyl ethyl ketone was added and stirring was continued for 3 hours. After the reaction was complete, the temperature of the solution was lowered to 65°C, and 163.0 g of isopropanol was added and allowed to cool, thereby obtaining a polymerization solution containing the copolymer (solid content concentration 41.0% by mass). Next, 317.3 g of the obtained polymerization solution was weighed, and 46.4 g of isopropanol, 1.65 g of 20% by mass maleic anhydride aqueous solution (equivalent to 0.3% by mass of maleic acid relative to the copolymer), and 40.77 g of 2 mol / L sodium hydroxide aqueous solution were added to it, and the temperature of the liquid in the reaction vessel was raised to 70°C. Next, 380 g of distilled water was added dropwise to the liquid, which had been heated to 70°C, at a rate of 10 mL / min. Subsequently, 287.0 g of isopropanol, methyl ethyl ketone, and distilled water were removed by distillation under reduced pressure, maintaining the temperature of the liquid in the reaction vessel at 70°C for 1.5 hours. To the resulting liquid, 0.278 g of Proxel GXL(S) (manufactured by Arch Chemicals Japan) (440 ppm as benzoisothiazolin-3-one relative to the polymer solids) was added. The obtained liquid was filtered through a 1 μm filter, and the filtrate was collected to obtain an aqueous dispersion of resin particles A (solid content concentration 23.2% by mass), which is a copolymer of methyl methacrylate / isobornyl methacrylate / methacrylic acid (=70 / 20 / 10 [mass ratio]). Of the structural units derived from methacrylic acid that constitute the resin, 50% by mass was sodium methacrylate salt. The volume-average particle size of resin particles A was 5.0 nm, and the weight-average molecular weight (Mw) was 60,000.

[0259] In Tables 1 to 3, the first organic solvent A refers to an organic solvent contained in the white ink with a boiling point of 120°C to 200°C, the first organic solvent B refers to an organic solvent with a boiling point greater than 200°C and 240°C or less, and the first organic solvent C refers to an organic solvent with a boiling point greater than 240°C.

[0260] [Table 1]

[0261] [Table 2]

[0262] [Table 3]

[0263] <Preparation of colored ink> The following pigment dispersions were prepared as cyan, magenta, yellow, and black pigment dispersions. In each of these dispersions, the pigments of each color are dispersed by a cross-linked polymer. • Cyan pigment dispersion (Product name: "APD3000Cyan (pigment concentration 14.0% by mass), manufactured by FUJIFILM Imaging Colorants) • Magenta pigment dispersion (Product name: "APD3000Magenta (Pigment concentration 14.0% by mass)", manufactured by FUJIFILM Imaging Colorants) • Yellow pigment dispersion (Product name: "APD3000Yellow (Pigment concentration 10.0% by mass)", manufactured by FUJIFILM Imaging Colorants) • Black pigment dispersion… (Product name "APD3000Black (pigment concentration 10.0% by mass)", manufactured by FUJIFILM Imaging Colorants)

[0264] -Preparation of cyan inks C1-C6- For cyan inks C1 to C6, the cyan pigment dispersion described above was mixed with an organic solvent, resin particles, and water to prepare the cyan ink so that the content of each component was as shown in Table 4 (mass %). The concentration of the crosslinked polymer used as a pigment dispersant is the value obtained by subtracting the pigment concentration from the solid content concentration obtained by drying each pigment dispersion under reduced pressure.

[0265] -Preparation of magenta ink M1, yellow ink Y1, and black ink Bk1- For magenta ink M1, the magenta pigment dispersion described above was mixed with an organic solvent, resin particles, and water to prepare the magenta ink so that the content of each component was as shown in Table 5 (mass %). For yellow ink Y1, the above-mentioned yellow pigment dispersion was mixed with an organic solvent, resin particles, and water to prepare the yellow ink so that the content of each component was as shown in Table 5 (mass %). For black ink Bk1, the black pigment dispersion described above was mixed with an organic solvent, resin particles, and water to prepare the black ink so that the content of each component was as shown in Table 5 (mass %). The water content is calculated as the remaining amount that makes up 100% by mass of all colored inks combined.

[0266] In Tables 4 and 5, the second organic solvent A refers to the organic solvent contained in the colored ink, with a boiling point of 120°C to 200°C.

[0267] [Table 4]

[0268] [Table 5]

[0269] <Preparation of pretreatment solution> Pretreatment solutions T1 and T2 were prepared by mixing the following components in the following quantities. -Pretreatment solution T1- • Flocculant: Malonic acid…5% by mass • Surfactant: Sodium dodecylbenzenesulfonate (hard type), manufactured by Tokyo Chemical Industry Co., Ltd. ... 1% by mass • Water…the remaining amount that makes up 100% by mass of the entire pretreatment solution.

[0270] -Pretreatment solution T2- • Flocculant: Malonic acid…5% by mass • Third organic solvent: Propylene glycol (boiling point 188°C) ... 5% by mass • Surfactant: Sodium dodecylbenzenesulfonate (hard type), manufactured by Tokyo Chemical Industry Co., Ltd. ... 1% by mass • Water…the remaining amount that makes up 100% by mass of the entire pretreatment solution.

[0271] [Image Recording] As a non-permeable substrate (hereinafter also simply referred to as "substrate"), a polyethylene terephthalate (PET) substrate (product name "FE2001", manufactured by Futamura Chemical Co., Ltd., thickness 12 μm, width 100 mm, length 200 mm) was prepared.

[0272] An image recording device was prepared, comprising a transport mechanism for transporting the substrate, and, in the order of upstream of the substrate transport direction, a wire bar coater for applying pretreatment liquid, a first inkjet head for applying colored ink, and a second inkjet head for applying white ink. When applying two or more types of colored ink, the number of inkjet heads was increased according to the number of colored inks to be applied.

[0273] Both the first and second inkjet heads were 1200 dpi / 20-inch wide piezo full-line heads. Here, dpi stands for dots per inch.

[0274] The arrangement of both the first and second inkjet heads is a line head configuration, where the heads are aligned in a direction perpendicular to the substrate transport direction (i.e., the width direction of the substrate). For each of the above inkjet heads, we used the Samba G3L (manufactured by FUJIFILM DIMATIX).

[0275] In the image recording device described above, the substrate, the pretreatment liquid, the white ink, and the colored ink were set, and the pretreatment liquid, white ink, and colored ink were applied to the substrate under conditions that overlapped in a plan view between the areas to which the pretreatment liquid was applied and the areas to which the white ink was applied. An image was then recorded. This resulted in obtaining an image recording. In Example 33, the pretreatment liquid was not used, and the substrate, white ink, and colored ink were set in the image recording device described above. The white ink and colored ink were applied to the substrate under conditions that overlapped in a plan view between the areas to which the white ink was applied and the areas to which the colored ink was applied. An image was then recorded. The following details the image recording method when applying the pretreatment solution. Note that Example 34 is the same as the image recording method when applying the pretreatment solution, except that it does not include the step of applying the pretreatment solution.

[0276] The substrate was moved at a constant speed of 500 mm / second while the pretreatment solution was applied to the substrate using a wire bar coater. The amount of pretreatment solution applied was as shown in Tables 6 to 9 (unit: g / m²). 2 )

[0277] The mass of pretreatment solution applied is the mass of the applied pretreatment solution divided by the area of ​​the region to which the pretreatment solution was applied. The amount of the third organic solvent applied is equal to the amount of the pretreatment solution applied (unit: g / m³). 2This value is calculated based on the content (mass%) of the third organic solvent relative to the total amount of the pretreatment solution.

[0278] At the point where the pretreatment solution had been applied, drying of the pretreatment solution was started using a dryer at 50°C 1.5 seconds after the completion of the pretreatment solution application, and drying was completed 3.5 seconds after the completion of the pretreatment solution application. The drying time at this point was 2 seconds.

[0279] After the pretreatment solution had dried, the substrate was moved at a constant stage speed of 50 mm / second, and colored ink was ejected from the first inkjet head onto the dried pretreatment solution to create a solid image. Then, white ink was ejected from the second inkjet head onto the applied colored ink. In this process, the white ink was applied to the entire surface of the colored ink on the substrate. The overlapping areas in the examples and comparative examples correspond to the areas where colored ink is applied and the areas where white ink is applied, respectively.

[0280] Next, the colored ink and white ink were dried at 70°C for 10 seconds.

[0281] This resulted in obtaining a solid image having a laminated structure in which a white ink film is laminated on a colored ink film. That is, an image recording material was obtained comprising a substrate and the solid image provided on the substrate.

[0282] Here, the ejection conditions for both the colored and white inks were set to an ejection frequency of 24 kHz and a resolution of 1200 dpi × 1200 dpi (dots per inch). The amount of colored ink and white ink dispensed was adjusted according to the respective amounts of colored and white ink dispensed. The results are shown in Tables 6-9. For example, in Example 1, the amount of colored ink droplets was 4.0 nanograms (colored ink application mass 8.94 g / m²). 2 (Compatible with) and the amount of white ink droplets is 3.4 nanograms (white ink application mass 7.59 g / m²). 2 (This corresponds to)

[0283] Both the colored and white inks used were degassed through a degassing filter and heated to 30°C.

[0284] The mass of colored ink applied is the mass of colored ink applied to the overlapping region divided by the area of ​​the overlapping region. The amount of the second organic solvent added is equal to the amount of the colored ink added (unit: g / m²). 2 This value is calculated based on the content (mass%) of the second organic solvent relative to the total amount of colored ink.

[0285] The amount of white ink applied is the mass of white ink applied to the overlapping region divided by the area of ​​the overlapping region. The amount of the first organic solvent applied is equal to the amount of white ink applied (unit: g / m²). 2 This value is calculated based on the content (mass%) of the first organic solvent relative to the total amount of white ink. The amount of white pigment applied is equal to the amount of white ink applied (unit: g / m²). 2 This value is calculated based on the amount of white pigment (mass %) relative to the total amount of white ink. As mentioned above, each value obtained by calculation was calculated using a value with one more significant digit than the value listed in the table, and then rounded according to the number of significant digits.

[0286] In Tables 6 to 9, "G / A" in the colored ink column refers to the mass ratio of alkylene glycol content to alkylene glycol ether content in the colored ink. Similarly, "G / A" in the white ink column refers to the mass ratio of alkylene glycol content to alkylene glycol ether content in the white ink. In addition, "Type of alkylene glycol alkyl ether" in the white ink column refers to the number of different types of alkylene glycol alkyl ether contained in the white ink.

[0287] [evaluation] For each example and comparative example, the lamination strength, opacity, and adhesion of the image recording material, as well as the re-ejectability and ejection performance of the white ink, were evaluated. The evaluation method is as follows. The evaluation results are shown in Tables 6 to 9.

[0288] -Laminate strength- Images were recorded using the method described in the image recording section above, and image recordings were obtained. The obtained image recordings were used as samples for evaluating laminate strength. Within 60 minutes after image recording, a dry laminating adhesive (main component TM-320 (isocyanate compound) / curing agent CAT-13B (alcohol compound), manufactured by Toyo Morton Co., Ltd.) was applied using a bar coater and dried at 70°C for 10 seconds. An unoriented polypropylene film (CPP) film (product name: Pyrene P1128, manufactured by Toyobo Co., Ltd., thickness 25 μm) was placed on top of the dried adhesive as a laminating substrate. In this state, the laminating substrate and the laminate strength evaluation sample were bonded together to obtain a laminate. The obtained laminate was aged at 40°C for 48 hours. A sample piece measuring 100 mm in length and 15 mm in width was cut from the aged laminate. Next, the laminating substrate and the laminate strength evaluation sample were manually separated in a region of 30 mm from one end of the sample piece in the longitudinal direction. The remaining 70 mm region was left with the laminating substrate and the laminate strength evaluation sample bonded together. Next, a tensile test was performed on the delaminated portion of the sample piece, pulling the laminate substrate and the delaminated portion of the laminate strength evaluation sample in opposite directions. The pulling direction was perpendicular to the remaining 70 mm length region (the region where the laminate substrate and the laminate strength evaluation sample remained bonded together). This tensile test determined the peel strength required to separate the laminating substrate from the laminate strength evaluation sample in the remaining 70 mm length region, and the obtained peel strength was defined as the laminate strength. The evaluation criteria are as follows. AA: The lamination strength between the image recording and the laminating substrate is 1.5 N / 15 mm or higher. A: The lamination strength between the image recording and the laminating substrate is 1 N / 15 mm or more and less than 1.5 N / mm. B: The lamination strength between the image recording and the laminating substrate is 0.5 N / 15 mm or more and less than 1 N / 15 mm. C: The lamination strength between the image recording and the laminating substrate is less than 0.5 N / 15 mm.

[0289] -Concealment- Images were recorded using the method described in the image recording section above, and image recordings were obtained. The obtained recordings were placed on measurement paper with the substrate side facing down. As the measurement paper, the white area of ​​opacity measurement paper (standard: JIS K-5600, manufactured by TP Giken Co., Ltd.) was used. Using a spectrophotometer (product name "X-Rite eXact (measurement diameter: 2 mm, light source: D50, observer field of view: 2° field of view, density status: Status T)", manufactured by X-Rite Corporation), the optical density (OD value) of the overlapping region between the colored ink film and the white ink film was measured from the white solid image side of the obtained image recording. The opacity was evaluated based on the optical density (OD value). The evaluation criteria are as follows. AA:OD value is less than 0.70 A: The OD value is 0.70 or higher and less than 0.85. B: The OD value is 0.85 or higher and less than 1.00. The C:OD value is 1.00 or higher.

[0290] -Adhesion- Images were recorded using the method described in the image recording section above, and an image recording was obtained. Within 30 minutes ± 1 minute after image recording, a piece of cellophane tape (registered trademark, No. 405, manufactured by Nichiban Co., Ltd., 12 mm wide, hereinafter also simply referred to as "tape") was attached to the solid image of the obtained image recording, and then the adhesion of the image was evaluated by peeling off the tape piece. The tape was applied and removed using the following method. The tape was removed at a constant speed, cut to a length of approximately 75 mm, and obtained tape pieces. The obtained tape piece was placed over the solid image, and a 12mm wide and 25mm long area in the center of the tape piece was stuck to it with a finger and rubbed firmly with the fingertip. Within 5 minutes of applying the tape piece, grasp the end of the tape piece and peel it off in 0.5 to 1.0 seconds at an angle as close to 60° as possible. The presence or absence of adhering substances on the detached tape fragments and the presence or absence of image peeling were visually observed. The evaluation criteria were as follows: AA: There is no residue on the tape piece, and the image is not peeling off. A: There is some colored residue on the tape, but the image is not peeling off. B: There is some colored residue on the tape piece, and there is some peeling of the image, but the peeled area is less than 30% of the image area. C: The tape piece has colored deposits, there is peeling of the image, and the peeled area is 30% or more of the image area.

[0291] -Re-ejectability of white ink after printing pause- After recording the image using the image recording method described above, the inkjet head was left idle for 1 minute under conditions of 25°C and 50% humidity. After 1 minute, a single pass was used on the substrate with a mass applied per unit area of ​​4.47 g / m². 2 White ink was ejected under the specified conditions, and a solid image was recorded. In the obtained solid image, the portion of the image recorded immediately after the start of ejection was observed using a microscope, and the deviation of the impact position was measured. The evaluation criteria are as follows. AA: There is no deviation in the point of impact. A: The deviation in the point of impact is 0.5 mm or less. B: The deviation of the point of impact is greater than 0.5 mm and less than or equal to 1.0 mm. C: The deviation in the point of impact is greater than 1.0 mm.

[0292] -White ink payoff properties- On the substrate, a single pass applied a mass of 4.47 g / m² per unit area. 2 White ink was ejected under the specified conditions, and a solid image was recorded. The state of the resulting solid image was visually inspected. The evaluation criteria are as follows: AA: No tendons A: There is a thin line. B: There are 2 to 4 thin lines. C: There are five or more thin streaks, or there are thick streaks.

[0293] [Table 6]

[0294] [Table 7]

[0295] [Table 8]

[0296] [Table 9]

[0297] As shown in Tables 6 to 9, Examples 1 to 39 include the steps of: preparing a white ink containing a white pigment, a first organic solvent, and water; preparing a colored ink containing a colored pigment other than the white pigment, a second organic solvent, and water; and applying the 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 to which the white ink is applied and the area to which the colored ink is applied overlap in a plan view, the total amount of the first organic solvent and the second organic solvent applied per unit area is 5.5 g / m². 2 The following applies, and the amount of white pigment applied per unit area is 0.4 g / m². 2 Under the above conditions, it was found that an image recording material with excellent lamination strength and opacity could be obtained by imprinting the image.

[0298] On the other hand, in Comparative Example 1, in the region where the area to which white ink is applied and the area to which colored ink is applied overlap in a plan view, the total mass of the first organic solvent and the second organic solvent applied per unit area was 5.5 g / m².2 It was found that the resulting image recordings had inferior lamination strength.

[0299] In Comparative Example 2, in the region where the area to which white ink is applied and the area to which colored ink is applied overlap in a plan view, the amount of white pigment applied per unit area was 0.4 g / m². 2 The result was less than [a certain value], and the resulting image recordings were found to have poor opacity.

[0300] In Example 6, the content of the first organic solvent was 30% by mass or less relative to the total mass of the white ink, and the content of the second organic solvent was 30% by mass or less relative to the total mass of the colored ink. As a result, it was found that an image recording material with superior lamination strength could be obtained compared to Example 5.

[0301] In Example 13, a pretreatment solution was applied to a non-permeable substrate, and then white ink and colored ink were applied to record the image. As a result, it was found that an image recording material with superior lamination strength, opacity, and adhesion was obtained compared to Example 34.

[0302] In Examples 13 and 15, the pigment dispersant contained in the white ink was a crosslinked polymer or a block polymer, respectively. As a result, compared to Example 30, image recordings with superior lamination strength, opacity, and adhesion were obtained, and the white ink discharge was also superior. Compared to Example 31, image recordings with superior lamination strength were obtained.

[0303] In Example 14, both the white ink and the pre-colored ink had a weighted average value of 28 MPa for the solubility parameters of the organic solvents contained in each ink. 1 / 2 Therefore, it was found that an image recording material with superior lamination strength and adhesion was obtained compared to Example 23.

[0304] In Example 8, the proportion of the first organic solvent A in the organic solvent contained in the white ink was 50% by mass or more, and the first organic solvent A contained at least one alkylene glycol and at least one alkylene glycol alkyl ether. As a result, it was found that an image recording material with superior lamination strength and adhesion could be obtained compared to Example 9.

[0305] Furthermore, in Example 12, since the first organic solvent A contains at least one alkylene glycol and at least two alkylene glycol alkyl ethers, it was found that an image recording material with superior lamination strength could be obtained compared to Example 8.

[0306] Furthermore, in Example 8, the mass ratio of alkylene glycol content to alkylene glycol ether content was 15.0 or less, so it was found that an image recording material with superior lamination strength and adhesion could be obtained compared to Example 10.

[0307] In Example 4, the proportion of the second organic solvent A in the organic solvent contained in the colored ink was 50% by mass or more. Since the second organic solvent A contains at least one alkylene glycol and at least one alkylene glycol alkyl ether, it was found that an image recording material with superior lamination strength could be obtained compared to Example 38.

[0308] <Examples 101 and 102> Image recordings were obtained using the same method as in Example 1, with the four inks listed in Table 10 used as coloring inks. Details of the magenta ink, yellow ink, and black ink are shown in Table 5.

[0309] The amount of pretreatment solution to be applied is as shown in Table 10 (unit: g / m²). 2 )

[0310] After applying a pretreatment solution to the substrate, cyan ink, magenta ink, yellow ink, black ink, and white ink were dispensed in that order. During this process, the white ink was applied to the entire surface of the colored inks already on the substrate.

[0311] The amount of each colored ink and white ink applied is shown in Table 10 (unit: g / m²). 2 )

[0312] Examples 101 and 102 were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 10.

[0313] [Table 10]

[0314] As shown in Table 10, in Examples 101 and 102, which used four types of colored inks, it was found that image recordings with excellent lamination strength and opacity could be obtained, similar to the case where one type of colored ink was used.

Claims

1. 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 colored ink containing a colored pigment other than the aforementioned white pigment, a second organic solvent with a boiling point of 120°C or higher, and water, The process includes the step of applying the white ink and the colored ink to a non-permeable substrate and recording an image, 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. The process of recording the aforementioned image involves applying a total mass of the first organic solvent and the second organic solvent per unit area of ​​5.0 g / m² in the region where the area to which the white ink is applied and the area to which the colored ink is applied overlap in a plan view. ２ The following applies, and The amount of the white pigment applied per unit area is 0.4 g / m². ２ An image recording method for recording the aforementioned image under the above conditions.

2. The process further includes a step of preparing a pretreatment solution containing a coagulant and water, The image recording method according to claim 1, wherein in the step of recording the image, the pretreatment liquid is applied to the non-permeable substrate, and then the white ink and the colored ink are applied, respectively, to record the image.

3. The image recording method according to claim 2, wherein the pretreatment liquid does not contain a third organic solvent having a boiling point of 120°C or higher, or, if it contains 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 relative to the total mass of the pretreatment liquid is 15% by mass or less.

4. The process of recording the image involves applying the first organic solvent, the second organic solvent, and the third organic solvent in a region where the area to which the pretreatment liquid is applied, the area to which the white ink is applied, and the area to which the colored ink is applied overlap in a plan view, with a total applied mass of 5.5 g / m² per unit area. ２ The image recording method according to claim 3, wherein the image is recorded under the following conditions.

5. The process of recording the aforementioned image involves applying the third organic solvent in a region where the area to which the pretreatment solution is applied, the area to which the white ink is applied, and the area to which the colored ink is applied overlap in a plan view, with a mass of the third organic solvent applied per unit area of ​​0.2 g / m². ２ The image recording method according to claim 3 or claim 4, wherein the image is recorded under the following conditions.

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

7. Both the white ink and the colored ink have a weighted average value of 28 MPa for the solubility parameter of the organic solvent contained in each ink. 1 / 2 The image recording method according to any one of claims 1 to 6, as follows:

8. The image recording method according to any one of claims 1 to 7, wherein the first organic solvent comprises a first organic solvent A having a boiling point of 120°C to 200°C, the proportion of the first organic solvent A in the total organic solvent contained in the white ink is 50% by mass or more, and the first organic solvent A comprises at least one alkylene glycol and at least one alkylene glycol alkyl ether.

9. The image recording method according to claim 8, wherein the first organic solvent A comprises at least one alkylene glycol and at least two alkylene glycol alkyl ethers.

10. The image recording method according to claim 8 or claim 9, wherein the mass ratio of the alkylene glycol content to the alkylene glycol ether content is 15.0 or less.

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

12. A step of recording the image on a non-permeable substrate using the image recording method described in any one of claims 1 to 11, A method for manufacturing a laminate, comprising the step of laminating a laminating substrate onto the side of the non-permeable substrate on which the image is recorded to obtain a laminate.

13. An image recording material comprising a non-permeable substrate and an image recorded on the non-permeable substrate by an image recording method according to any one of claims 1 to 11, wherein the image includes a white ink layer in contact with the non-permeable substrate and containing a white pigment and an organic solvent, and a colored ink layer in contact with the white ink layer and containing a colored pigment other than the white pigment, and includes a region in which the white ink layer and the colored ink layer overlap in a plan view, and in the white ink layer, the mass of the white pigment per unit area is 1.0 g / m². ２ The above is the image recording.

14. An image recording material comprising a non-permeable substrate and an image recorded on the non-permeable substrate by an image recording method according to any one of claims 1 to 11, wherein the image includes a pre-treatment liquid layer containing a flocculant in contact with the non-permeable substrate, a white ink layer containing a white pigment and an organic solvent in contact with the pre-treatment liquid layer, and a colored ink layer containing a coloring pigment other than the white pigment in contact with the white ink layer, and includes a region in which the pre-treatment liquid layer, the white ink layer and the colored ink layer overlap in a plan view, and in the white ink layer, the mass of the white pigment per unit area is 1.0 g / m² ２ The above is the image recording.

15. A laminate body comprising an image recording material according to claim 13 or claim 14, and a laminating substrate laminated onto the image of the image recording material.

Images