Image recording method and inkjet recording

Abstract

Provided are: an image recording method comprising a step for preparing at least two types of ink including a first ink and a second ink, a step for heating a base material, a step for using an ink jet recording technique to provide the at least two types of ink onto the heated base material, and a step for irradiating the at least two types of ink with active energy rays, wherein in the step for providing the at least two types of ink, a mixture region in which the at least two types of ink are mixed by the provision thereof is formed on at least part of the base material, the first ink includes a first polymerizable liquid crystal compound, and the second ink includes a second chiral compound; and ink jet recorded matter.

Description

[Technical Field]

[0001] The present disclosure relates to an image recording method and an inkjet recorded matter. [Background technology]

[0002] In recent years, image recording methods using inks containing liquid crystal compounds have been proposed. Cholesteric liquid crystals, which are produced by adding chiral agents to liquid crystal compounds, have unique light reflectivity and the color tone changes depending on the viewing angle. Using inks containing liquid crystal compounds makes it possible to record unique images that cannot be seen with other image recording materials, which is expected to be useful for special decoration of products such as packaging materials, and for security printing.

[0003] For example, International Publication No. 2020 / 194831 discloses an image recording method including a base layer forming step of applying a base ink onto a substrate using an inkjet recording method to form a base layer, and an image recording step of applying an image recording ink containing a polymerizable liquid crystal compound and a chiral compound onto the base layer using an inkjet recording method to record an ink image. Summary of the Invention [Problem to be solved by the invention]

[0004] However, WO 2020 / 194831 only discloses applying a single type of image recording ink onto the underlayer, and does not mention the reproduction of a variety of colors.

[0005] The present disclosure has been made in consideration of the above circumstances, and according to one embodiment of the present invention, there are provided an image recording method and inkjet recorded matter that are capable of reproducing a variety of colors with high color development. [Means for solving the problem]

[0006] The present disclosure includes the following aspects. <1> An image recording method comprising the steps of: preparing at least two types of ink, including a first ink and a second ink; heating a substrate; applying the at least two types of ink onto the heated substrate using an inkjet recording method; and irradiating the at least two types of ink with actinic energy rays, wherein in the step of applying the at least two types of ink, a mixed region in which the at least two types of ink are mixed is formed on at least a part of the substrate by the application, and the first ink comprises a first polymerizable liquid crystal compound, and the second ink comprises a second chiral compound. <2> the first ink contains a first polymerizable liquid crystal compound, a first chiral compound, and a first organic solvent; the second ink contains a second polymerizable liquid crystal compound, a second chiral compound, and a second organic solvent; and the absolute value of the difference between the maximum reflection wavelength of an ink film formed by the first ink and the maximum reflection wavelength of an ink film formed by the second ink is 100 nm or more; <1> 1. The image recording method according to claim 1. <3> The maximum reflection wavelength of the ink film formed by the first ink is 380 nm to 490 nm, and the maximum reflection wavelength of the ink film formed by the second ink is 600 nm to 800 nm. <1> or <2> 1. The image recording method according to claim 1. <4> In the step of preparing at least two kinds of inks, a third ink containing a third polymerizable liquid crystal compound, a third chiral compound, and a third organic solvent is further prepared, and the absolute value of the difference between the maximum reflection wavelength of the ink film formed by the first ink and the maximum reflection wavelength of the ink film formed by the second ink and the maximum reflection wavelength of the ink film formed by the third ink is 40 nm or more. <1> ~ <3> 10. The image recording method according to claim 9, wherein the image is recorded in a recording medium. <5> The maximum reflection wavelength of the ink film formed by the first ink is 380 nm to 490 nm, the maximum reflection wavelength of the ink film formed by the second ink is 600 nm to 800 nm, and the maximum reflection wavelength of the ink film formed by the third ink is 500 nm to 590 nm. <4> 1. The image recording method according to claim 1. <6> In the step of applying at least two kinds of inks, the total amount of the at least two kinds of inks applied per unit area is set to 3 g / m in the mixing region. 2 ~20g / m 2The range is given as <1> ~ <5> 10. The image recording method according to claim 9, wherein the image is recorded in a recording medium. <7> In the step of applying at least two kinds of inks, the total amount of polymerizable liquid crystal compounds contained in the at least two kinds of inks applied per unit area is 1.5 g / m 2 ~8g / m 2 The range is given as <2> ~ <6> 10. The image recording method according to claim 9, wherein the image is recorded in a recording medium. <8> In the step of applying at least two kinds of inks, the total amount of organic solvents contained in the at least two kinds of inks applied per unit area is set to 2.5 g / m in the mixing region. 2 ~12.5g / m 2 The range is given as <2> ~ <7> 10. The image recording method according to claim 9, wherein the image is recorded in a recording medium. <9> At least two of the inks have a viscosity of 7 mPa·s or more. <1> ~ <8> 10. The image recording method according to claim 9, wherein the image is recorded in a recording medium. <10> At least two types of ink have a maximum absolute difference in surface tension of 1 mN / m or less. <1> ~ <9> 10. The image recording method according to claim 9, wherein the image is recorded in a recording medium. <11> In the step of heating the substrate, the substrate is heated to 40°C or higher. <1> ~ <10> 10. The image recording method according to claim 9, wherein the image is recorded in a recording medium. <12> An inkjet recorded matter comprising a substrate and an ink film containing a liquid crystal polymer provided on the substrate, wherein the ink film includes, in a planar view, a plurality of regions having mutually different maximum reflection wavelengths, and the orientation state of the liquid crystal polymer changes continuously between two adjacent regions. [Effects of the Invention]

[0007] According to one embodiment of the present invention, there are provided an image recording method and an inkjet recorded matter that are capable of reproducing a variety of colors with high color development. DETAILED DESCRIPTION OF THE INVENTION

[0008] The image recording method of the present disclosure will be described in detail below. In this specification, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this specification, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples. In this specification, the amount of each component in a composition means the total amount of the multiple substances present in the composition, unless otherwise specified, when multiple substances corresponding to each component are present in the composition. Also, in this specification, a combination of two or more preferred embodiments is a more preferred embodiment. Furthermore, in this specification, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved. As used herein, "(meth)acrylate" means acrylate or methacrylate.

[0009] [Image recording method] The image recording method of the present disclosure includes the steps of preparing at least two types of ink, including a first ink and a second ink; heating a substrate; applying the at least two types of ink onto the heated substrate using an inkjet recording method; and irradiating the at least two types of ink with actinic energy rays. In the step of applying the at least two types of ink, a mixed region in which the at least two types of ink are mixed is formed on at least a portion of the substrate by the application. The first ink contains a first polymerizable liquid crystal compound, and the second ink contains a second chiral compound, making it possible to reproduce a variety of colors with high color development.

[0010] According to the present disclosure, an ink image can be recorded by applying inks to a substrate. The ink image is a cured product of the ink. In the image recording method of the present disclosure, in the step of applying at least two types of ink, a mixed region in which the at least two types of ink are mixed is formed on at least a portion of the substrate by application. Since the first ink contains a first polymerizable liquid crystal compound and the second ink contains a second chiral compound, the first polymerizable liquid crystal compound and the second chiral compound are mixed, and the first polymerizable liquid crystal compound forms a helical structure with the second chiral compound, becoming a cholesteric liquid crystal. Cholesteric liquid crystals selectively reflect light of a wavelength corresponding to the pitch of the helical structure and exhibit structural color, so the ink image of the present disclosure exhibits structural color. Furthermore, by controlling the droplet volumes of the first ink and the second ink, it is possible to adjust the mixing ratio of the first polymerizable liquid crystal compound contained in the first ink and the second chiral compound contained in the second ink in the mixed region. Therefore, by forming a mixed region in which at least two types of ink are mixed, it is possible to reproduce a variety of colors.

[0011] In addition, in the image recording method of the present disclosure, by applying at least two inks to a heated substrate using an inkjet recording method, even if a mixed region of at least two inks is formed, the mixed region is unlikely to spread, and therefore the polymerizable liquid crystal compound can be uniformly aligned by the chiral compound, making it possible to reproduce highly color-developing colors.

[0012] Each step in the image recording method of the present disclosure will be described in detail below.

[0013] (Ink preparation process) The image recording method of the present disclosure includes a step of preparing at least two types of ink including a first ink and a second ink (hereinafter also referred to as an "ink preparation step").

[0014] The first ink contains a first polymerizable liquid crystal compound, and the second ink contains a second chiral compound. That is, at least two types of ink contain a polymerizable liquid crystal compound and a chiral compound. By applying the inks so as to form a mixed region in which at least two types of ink are mixed, the polymerizable liquid crystal compound and the chiral compound are mixed, and the polymerizable liquid crystal compound can be aligned by the chiral compound.

[0015] The first ink may contain a component other than the first polymerizable liquid crystal compound. The second ink may contain a component other than the second chiral compound. Combinations of the first ink and the second ink in the image recording method of the present disclosure include the following embodiments. (1) An embodiment in which the first ink contains a first polymerizable liquid crystal compound, and the second ink contains a second polymerizable liquid crystal compound and a second chiral compound. (2) An embodiment in which the first ink contains a first polymerizable liquid crystal compound and a first chiral compound, and the second ink contains a second polymerizable liquid crystal compound and a second chiral compound. (3) An embodiment in which the first ink contains a first polymerizable liquid crystal compound, a first chiral compound, and a first organic solvent, and the second ink contains a second polymerizable liquid crystal compound and a second chiral compound. (4) An embodiment in which the first ink contains a first polymerizable liquid crystal compound, a first chiral compound, and a first organic solvent, and the second ink contains a second polymerizable liquid crystal compound, a second chiral compound, and a second organic solvent. (5) An embodiment in which the first ink contains a first polymerizable liquid crystal compound and a first organic solvent, and the second ink contains a second chiral compound and a second organic solvent.

[0016] Furthermore, in the image recording method of the present disclosure, it is preferable that the first ink contains a first polymerizable liquid crystal compound, a first chiral compound, and a first organic solvent, and the second ink contains a second polymerizable liquid crystal compound, a second chiral compound, and a second organic solvent, and that the absolute value of the difference between the maximum reflection wavelength of the ink film formed by the first ink and the maximum reflection wavelength of the ink film formed by the second ink is 100 nm or more. In other words, it is preferable that both the first ink and the second ink contain a polymerizable liquid crystal compound, a chiral compound, and an organic solvent, and that the ink film formed by the first ink and the ink film formed by the second ink have different hues.

[0017] The first polymerizable liquid crystal compound and the second polymerizable liquid crystal compound may be the same or different. The first chiral compound and the second chiral compound may be the same or different. The first organic solvent and the second organic solvent may be the same or different.

[0018] When the absolute value of the difference between the maximum reflection wavelength of the ink film formed by the first ink and the maximum reflection wavelength of the ink film formed by the second ink is 100 nm or more, the hue difference is large and a variety of colors can be reproduced. The absolute value of this difference is more preferably 130 nm or more, and even more preferably 150 nm or more. The upper limit of the absolute value of this difference is, for example, 400 nm.

[0019] For example, when the first polymerizable liquid crystal compound and the second polymerizable liquid crystal compound are the same and the first chiral compound and the second chiral compound are the same, the absolute value of the difference between the maximum reflection wavelength of the ink film formed by the first ink and the maximum reflection wavelength of the ink film formed by the second ink can be made 100 nm or more by adjusting the content of the polymerizable liquid crystal compound or the chiral compound.

[0020] Specifically, from the viewpoint of reproducing a variety of colors, the maximum reflection wavelength of the ink film formed by the first ink is preferably 380 nm to 490 nm, and the maximum reflection wavelength of the ink film formed by the second ink is preferably 600 nm to 800 nm. Furthermore, the maximum reflection wavelength of the ink film formed by the first ink is more preferably 390 nm to 420 nm, and the maximum reflection wavelength of the ink film formed by the second ink is more preferably 600 nm to 700 nm.

[0021] The maximum reflection wavelength of the ink film is calculated by the following method. The ink was applied to a transparent polyethylene terephthalate substrate at 100% dot coverage, dried at 50°C for 5 minutes, and then dried at 80°C for another 5 minutes to completely remove the organic solvents contained in the ink. The ink was then cured using a metal halide lamp (product name "CSOT-40" manufactured by GS Yuasa) to obtain an ink film. The maximum reflection wavelength was calculated by measuring the spectral reflectance of the ink film using a fluorescence spectrodensitometer (product name "FD-7" manufactured by Konica Minolta). During measurement, a black paper (JIS K 5600 (ISO / FDIS 6504-3:1998) manufactured by TP Giken) was placed under the substrate, with the ink film positioned as the outermost layer.

[0022] In order to reproduce a wider variety of colors, it is preferable to further prepare a third ink in the ink preparation step. The third ink contains a third polymerizable liquid crystal compound, a third chiral compound, and a third organic solvent, and the absolute value of the difference between the maximum reflection wavelength of the ink film formed by the first ink and the maximum reflection wavelength of the ink film formed by the second ink and the maximum reflection wavelength of the ink film formed by the third ink is preferably 40 nm or more. In other words, it is preferable that the absolute value of the difference between the maximum reflection wavelength of the ink film formed by the first ink and the maximum reflection wavelength of the ink film formed by the third ink, and the absolute value of the difference between the maximum reflection wavelength of the ink film formed by the second ink and the maximum reflection wavelength of the ink film formed by the third ink, are all 40 nm or more.

[0023] The third polymerizable liquid crystal compound may be the same as or different from either the first polymerizable liquid crystal compound or the second polymerizable liquid crystal compound. The third chiral compound may be the same as or different from either the first chiral compound or the second chiral compound. The third organic solvent may be the same as or different from either the first organic solvent or the second organic solvent.

[0024] When the absolute value of the difference between the maximum reflection wavelength of the ink film formed by the first ink, the maximum reflection wavelength of the ink film formed by the second ink, and the maximum reflection wavelength of the ink film formed by the third ink is 40 nm or more, a wider variety of colors can be reproduced. The absolute value of this difference is more preferably 50 nm or more, and even more preferably 70 nm or more. The upper limit of the absolute value of this difference is, for example, 150 nm.

[0025] For example, when the first polymerizable liquid crystal compound, the second polymerizable liquid crystal compound, and the third polymerizable liquid crystal compound are the same, and the first chiral compound, the second chiral compound, and the third chiral compound are the same, by adjusting the content of the polymerizable liquid crystal compound or the chiral compound, the absolute value of the difference between the maximum reflection wavelength of the ink film formed by the first ink, the maximum reflection wavelength of the ink film formed by the second ink, and the maximum reflection wavelength of the ink film formed by the third ink can be made 40 nm or more.

[0026] Specifically, from the viewpoint of reproducing a wider variety of colors, the maximum reflection wavelength of the ink film formed using the first ink is preferably 380 nm to 490 nm, the maximum reflection wavelength of the ink film formed using the second ink is preferably 600 nm to 800 nm, and the maximum reflection wavelength of the ink film formed using the third ink is preferably 500 nm to 590 nm. Furthermore, the maximum reflection wavelength of the ink film formed using the first ink is more preferably 390 nm to 470 nm, the maximum reflection wavelength of the ink film formed using the second ink is more preferably 600 nm to 700 nm, and the maximum reflection wavelength of the ink film formed using the third ink is more preferably 500 nm to 550 nm.

[0027] Each component contained in the ink will be described below. The polymerizable liquid crystal compounds (e.g., first to third polymerizable liquid crystal compounds) contained in the at least two types of ink prepared in the ink preparation step will be simply referred to as "polymerizable liquid crystal compounds." The chiral compounds (first to third chiral compounds) contained in the at least two types of ink prepared in the ink preparation step will be simply referred to as "chiral compounds." The organic solvents (e.g., first to third organic solvents) contained in the at least two types of ink prepared in the ink preparation step will be simply referred to as "organic solvents." Furthermore, the at least two types of ink prepared in the ink preparation step will be simply referred to as "ink."

[0028] <Polymerizable liquid crystal compound> In the present disclosure, a polymerizable liquid crystal compound refers to a liquid crystal compound having a polymerizable group. The liquid crystal compound may be either a rod-shaped liquid crystal compound or a discotic liquid crystal compound, but is preferably a rod-shaped liquid crystal compound.

[0029] Examples of rod-shaped liquid crystal compounds include rod-shaped nematic liquid crystal compounds. Preferred rod-shaped nematic liquid crystal compounds include azomethine compounds, azoxy compounds, cyanobiphenyl compounds, cyanophenyl ester compounds, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexane compounds, cyano-substituted phenylpyrimidine compounds, alkoxy-substituted phenylpyrimidine compounds, phenyldioxane compounds, tolan compounds, and alkenylcyclohexylbenzonitrile compounds. Not only low-molecular-weight liquid crystal compounds but also high-molecular-weight liquid crystal compounds can be used as rod-shaped liquid crystal compounds.

[0030] A polymerizable liquid crystal compound can be obtained by introducing a polymerizable group into a liquid crystal compound. Examples of the polymerizable group include a polymerizable unsaturated group, an epoxy group, and an aziridinyl group. Among them, the polymerizable group is preferably a polymerizable unsaturated group, and an ethylenically unsaturated group is particularly preferred. The number of polymerizable groups contained in the polymerizable liquid crystal compound is preferably 1 to 6, and more preferably 1 to 3. From the viewpoint of durability of the obtained image, it is more preferred that the polymerizable liquid crystal compound has two polymerizable groups in the molecule.

[0031] Examples of the polymerizable liquid crystal compound include compounds described in Makromol.Chem., Vol. 190, p. 2255 (1989), Advanced Materials, Vol. 5, p. 107 (1993), U.S. Pat. No. 4,683,327, U.S. Pat. No. 5,622,648, U.S. Pat. No. 5,770,107, WO 95 / 22586, WO 95 / 24455, WO 97 / 00600, WO 98 / 23580, WO 98 / 52905, JP-A Nos. 1-272551, 6-16616, 7-110469, 11-80081, and 2001-328973.

[0032] Specific examples of the polymerizable liquid crystal compound include the following compounds (1) to (17): The polymerizable liquid crystal compound is not limited to the following examples.

[0033] [ka]

[0034] [ka]

[0035] [ka]

[0036] In compound (12), X1 each independently represents an integer of 2 to 5.

[0037] [ka]

[0038] [ka]

[0039] Examples of polymerizable liquid crystal compounds other than those exemplified above include cyclic organopolysiloxane compounds such as those disclosed in JP-A-57-165480.

[0040] The ink may contain only one type of polymerizable liquid crystal compound, or may contain two or more types.

[0041] In particular, the ink preferably contains two or more different polymerizable liquid crystal compounds, which can further improve color reproducibility.

[0042] The content of the polymerizable liquid crystal compound is preferably 1% by mass to 70% by mass, more preferably 5% by mass to 60% by mass, and particularly preferably 15% by mass to 45% by mass, relative to the total amount of the ink.

[0043] In the present disclosure, from the viewpoint of improving color reproducibility, it is preferable that the first ink and the second ink differ from each other in at least one of the type of polymerizable liquid crystal compound and the content of the polymerizable liquid crystal compound. Furthermore, when a third ink is used together with the first ink and the second ink, it is preferable that the first ink, the second ink, and the third ink differ from each other in at least one of the type of polymerizable liquid crystal compound and the content of the polymerizable liquid crystal compound. Depending on the type of polymerizable liquid crystal compound, the pitch of the helical structure when the polymerizable liquid crystal compound becomes a cholesteric liquid crystal differs, and the wavelength of light that is selectively reflected differs. By varying the type of polymerizable liquid crystal compound, ink films of different hues can be obtained. Furthermore, by varying the content of the polymerizable liquid crystal compound, the mixing ratio with the chiral compound changes, and ink films of different hues can be obtained.

[0044] (Chiral compounds) Chiral compounds are also called optically active compounds. Chiral compounds have the function of inducing a helical structure in polymerizable liquid crystal compounds. The twist direction or pitch of the induced helical structure varies depending on the type and content of the chiral compound.

[0045] The chiral compound is not particularly limited, and known compounds (for example, those described in Liquid Crystal Device Handbook, Chapter 3, Section 4-3, Chiral Agents for TN and STN, p. 199, edited by the 142nd Committee of the Japan Society for the Promotion of Science, 1989) can be used, and examples thereof include isosorbide derivatives and isomannide derivatives.

[0046] Chiral compounds generally contain an asymmetric carbon atom, but may also contain no asymmetric carbon atom as long as they have chirality. Examples of chiral compounds include axially asymmetric compounds having a binaphthyl structure, helical asymmetric compounds having a helicene structure, and planar asymmetric compounds having a cyclophane structure.

[0047] The chiral compound may have a polymerizable group. When the chiral compound has a polymerizable group, a polymer having a structural unit derived from the polymerizable liquid crystal compound and a structural unit derived from the chiral compound is formed by a polymerization reaction between the chiral compound and the polymerizable liquid crystal compound. When the chiral compound has a polymerizable group, the polymerizable group is preferably the same type of group as the polymerizable group possessed by the polymerizable liquid crystal compound. Therefore, the polymerizable group of the chiral compound is preferably a polymerizable unsaturated group, an epoxy group, or an aziridinyl group, more preferably a polymerizable unsaturated group, and particularly preferably an ethylenically unsaturated group. Alternatively, the chiral compound itself may be a liquid crystal compound.

[0048] Specific examples of chiral compounds include the following compounds: Note that chiral compounds that can be used in the ink composition are not limited to the following examples: "Me" in the compounds means a methyl group.

[0049] [ka]

[0050] [ka]

[0051] [ka]

[0052] In the above compounds, X's each independently represent an integer of 2 to 5.

[0053] The content of the chiral compound in the ink composition is preferably 1 to 15 parts by mass, and more preferably 1.5 to 5 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound.

[0054] The first ink and the second ink preferably have different chiral compound contents. Furthermore, when a third ink is used, the first ink, the second ink, and the third ink preferably have different chiral compound contents. Depending on the chiral compound content, the pitch of the helical structure when the polymerizable liquid crystal compound becomes a cholesteric liquid crystal varies, and the wavelength of light that is selectively reflected varies. By varying the chiral compound content, ink films of different hues can be obtained. Increasing the chiral compound content tends to shift the reflected wavelength toward shorter wavelengths, while decreasing the chiral compound content tends to shift the reflected wavelength toward longer wavelengths.

[0055] <Organic solvents> The type of organic solvent is not particularly limited and can be appropriately selected depending on the purpose.

[0056] Examples of organic solvents include ketone-based solvents, alkyl halide-based solvents, amide-based solvents, sulfoxide-based solvents, heterocyclic compounds, hydrocarbon-based solvents, ester-based solvents, and ether-based solvents.

[0057] The content of the organic solvent is preferably 20% to 90% by mass, more preferably 40% to 80% by mass, and even more preferably 50% to 80% by mass, relative to the total amount of the ink.

[0058] <Polymerization initiator> The ink preferably further contains a polymerization initiator. The polymerization initiator is preferably a photopolymerization initiator, and more preferably a radical polymerization initiator that has the function of generating radicals upon irradiation with ultraviolet light.

[0059] Examples of the polymerization initiator include alkylphenone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, intramolecular hydrogen abstraction photopolymerization initiators, oxime ester-based photopolymerization initiators, and cationic photopolymerization initiators. Among these, the polymerization initiator is preferably an acylphosphine oxide-based photopolymerization initiator, and specifically, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide or bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide is preferred.

[0060] The content of the polymerization initiator is preferably 0.1 to 20 parts by mass, and more preferably 0.5 to 12 parts by mass, relative to 100 parts by mass of the content of the polymerizable liquid crystal compound.

[0061] <Additives> The ink may contain additives as needed, as long as the effects of the present disclosure are not impaired.

[0062] Examples of additives include surfactants for improving the jetting properties of the ink, crosslinking agents, and non-polymerizable polymers.

[0063] When the ink contains a surfactant, the polymerizable liquid crystal compound is horizontally aligned on the air interface side when the ink is cured, and the helical axis direction is controlled to be more uniform. The surfactant is preferably a compound that can function as an alignment control agent that stably or quickly forms a cholesteric structure with planar alignment. Examples of surfactants include silicone-based surfactants and fluorine-based surfactants, with fluorine-based surfactants being preferred.

[0064] The content of the surfactant is preferably 0.01 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, and even more preferably 0.02 to 1 part by mass, per 100 parts by mass of the polymerizable liquid crystal compound.

[0065] <Physical properties> The viscosity of each of the at least two inks is preferably 7 mPa·s or more, more preferably 8 mPa·s or more, and even more preferably 10 mPa·s or more. From the viewpoint of ink ejection properties, the upper limit of the ink viscosity is, for example, 30 mPa·s.

[0066] When the viscosity of at least two inks is 7 mPa·s or higher, ink droplets that land on a substrate do not spread easily. In particular, if the chiral compounds contained in the ink flow and mix with adjacent ink droplets that land, the boundaries between areas where images are recorded in different hues tend to become unclear, and the image resolution tends to decrease. In contrast, ink droplets that do not spread easily can produce high-resolution images.

[0067] The viscosity of the ink is measured at 25° C. using a viscometer, for example, a viscometer (product name "RE-85L", manufactured by Toki Sangyo Co., Ltd.).

[0068] The surface tension of the at least two types of ink is preferably 20 mN / m to 40 mN / m, and more preferably 23 mN / m to 35 mN / m.

[0069] The surface tension of the ink is measured at 25° C. using a surface tensiometer, for example, a surface tensiometer (product name "DY-700", manufactured by Kyowa Interface Science Co., Ltd.).

[0070] The maximum absolute value of the difference in surface tension between the at least two inks is preferably 1 mN / m or less, more preferably 0.7 mN / m or less. When the difference in surface tension between the inks is small, with the absolute value of the difference being 1 mN / m or less, when a mixed region is formed in which at least two inks are mixed, the region in which the inks are mixed in the desired ratio is easily fixed. By appropriately controlling the region in which the inks are mixed uniformly, the polymerizable liquid crystal compound is uniformly oriented, resulting in an image with minimal color unevenness. Furthermore, when the difference in surface tension between adjacent inks is 1 mN / m or less after the inks land in adjacent regions, bleeding can be suppressed.

[0071] In the ink preparation step, from the viewpoint of ease of mixing of the inks, it is preferable to prepare at least two inks containing the same polymerizable liquid crystal compound and chiral compound, and in this case, it is preferable that the at least two inks have different contents of the chiral compound.

[0072] (Base material heating process) The image recording method of the present disclosure includes a step of heating a substrate (hereinafter also referred to as a "substrate heating step"). By heating the substrate in advance, ink can be applied onto the heated substrate.

[0073] The substrate is not particularly limited, and any substrate can be selected. The substrate may be any of an ink-absorbent substrate, a low ink-absorbent substrate, and a non-ink-absorbent substrate. Examples of the substrate include paper, leather, cloth, and resin. Among these, from the viewpoint of color development, the substrate is preferably an ink-non-absorbent substrate, and more preferably a resin substrate.

[0074] Examples of resins that can be used to form resin substrates include cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, acrylic resin, chlorinated polyolefin resin, polyethersulfone resin, polyethylene terephthalate (PET), polyethylene naphthalate, nylon, polyethylene, polystyrene, polypropylene, polycycloolefin resin, polyimide resin, polycarbonate resin, and polyvinyl acetal. The resin substrate may contain only one of these resins, or may contain a mixture of two or more of them.

[0075] The thickness of the substrate is not particularly limited, and is, for example, 1 μm to 10 mm.

[0076] In the substrate heating step, the means for heating the substrate is not particularly limited, and examples thereof include a heat drum, hot air, an infrared lamp, an oven, a heat plate, and a hot plate. The heating temperature of the substrate is preferably 40°C or higher, more preferably 50°C to 100°C, and even more preferably 55°C to 80°C.

[0077] (Ink application process) The image recording method of the present disclosure includes a step of applying at least two types of ink onto a heated substrate using an inkjet recording method (hereinafter also referred to as an "ink application step"). In the ink application step, a mixed region in which the at least two types of ink are mixed by application is formed on at least a part of the substrate.

[0078] In the ink application process, a mixed region where at least two types of ink are mixed is formed on at least a portion of the substrate, making it possible to reproduce a variety of colors with high color development. Furthermore, by applying the ink onto a heated substrate, ink droplets that land on the substrate are less likely to spread. Because the ink droplets are less likely to spread and remain at the landing position, high-resolution images can be obtained.

[0079] The mixed region in which at least two types of ink are mixed may be formed in at least a portion of the substrate. That is, the mixed region may be formed over the entire surface of the substrate. Furthermore, as long as the mixed region is formed in a portion of the substrate, the mixed region may not be formed in other portions of the substrate.

[0080] In the present disclosure, a mixed region refers to a region where at least two types of ink are mixed on a substrate. Specific embodiments in which a mixed region is formed include the following two embodiments.

[0081] When at least two types of ink are ejected consecutively, the at least two types of ink are mixed by having the subsequently ejected ink land on an ink landing area formed by the previously ejected ink. When at least two types of ink are ejected simultaneously, the at least two types of ink are mixed by having the ink landing areas formed by the at least two types of ink land so that at least a portion of the ink overlaps with one another. Note that the "mixed area" in this disclosure does not include an area where the ink landing areas partially overlap as the ink spreads on the substrate after the at least two types of ink are ejected so that the ink landing areas do not overlap with one another.

[0082] The formation of the mixed region can be confirmed by the following method. By measuring the reflected wavelength of the mixed region with a fluorescent spectrodensitometer (product name "FD-7"), etc., it can be confirmed that it is different from the reflected wavelength of the non-mixed region. In addition, because the color development of the mixed region is different from that of the non-mixed region, it can be easily confirmed by visual inspection.

[0083] In the image recording method of the present disclosure, in the ink application step, the ink film (also referred to as "ink layer") formed on the substrate by applying the ink is a single layer.

[0084] For example, one method for recording an image on a substrate is to laminate ink layers, but the image recording method of the present disclosure can reduce the number of steps by forming the ink layer as a single layer. Furthermore, the ink only needs to be designed taking into consideration the interaction between the substrate and the ink (e.g., wettability), and there is no need to consider the interaction between the ink layer and the ink, as opposed to laminating ink layers. Furthermore, the image recording method of the present disclosure applies the ink to form a single layer, so that an image with higher color development can be obtained, as compared to laminating ink layers.

[0085] The inkjet recording method can be a commonly known method, and examples thereof include a charge control method that uses electrostatic attraction to eject an ink composition, a drop-on-demand method (pressure pulse method) that uses the vibration pressure of a piezoelectric element, an acoustic inkjet method that converts an electric signal into an acoustic beam and irradiates the ink composition with it, thereby ejecting the ink composition using radiation pressure, and a thermal inkjet method that heats the ink composition to form bubbles and uses the resulting pressure.

[0086] Generally, image recording methods using inkjet recording devices include a shuttle scan method (also called a "serial head method"), which uses a short serial head to record an image, and a single-pass method (also called a "line head method"), which uses a line head in which recording elements are arranged across the entire width of the recording medium. In the shuttle scan method, an image is recorded by scanning the serial head across the width of the recording medium. In contrast, in the single-pass method, an image can be recorded across the entire surface of the recording medium by scanning the recording medium in a direction perpendicular to the direction of the recording element arrangement. Therefore, unlike the shuttle scan method, the single-pass method does not require a transport system such as a carriage for scanning the serial head. Furthermore, the single-pass method does not require complex scanning control of the carriage movement and the recording medium; only the recording medium moves, allowing for faster recording speeds compared to the shuttle scan method.

[0087] In the ink application step, the total amount of at least two types of ink applied per unit area is 3 g / m in the mixing region. 2 ~20g / m 2 It is preferable to apply it in the range of 3.5 g / m 2 ~20g / m 2 , 3.5g / m 2 ~18g / m 2 It is more preferable to apply it in the range of 3.5 g / m 2 ~16g / m 2 It is more preferable to apply it in the range of 3.5 g / m 2 ~13g / m 2It is particularly preferable to give it in the range of

[0088] In particular, in the mixed region, at least two types of ink are mixed, so the amount of ink applied is greater than in regions other than the mixed region. 2 ~20g / m 2 By applying the ink within the range of , the ink droplets that land are less likely to spread, and a high-definition image can be obtained.

[0089] In the ink application process, the amount of ink applied per unit area in one image recording was set to 3 g / m2 even in areas other than the mixed area. 2 ~20g / m 2 It is preferable to apply it in the range of 3.5 g / m 2 ~20g / m 2 , 3.5g / m 2 ~18g / m 2 It is more preferable to apply it in the range of 3.5 g / m 2 ~16g / m 2 It is more preferable to apply it in the range of 3.5 g / m 2 ~13g / m 2 It is particularly preferable to apply the ink in the range of

[0047] The region other than the mixed region means a region where only one type of ink is applied onto the substrate, and at least two types of ink are not mixed.

[0090] In the ink application step, the total amount of polymerizable liquid crystal compounds contained in at least two types of inks applied per unit area is set to 1 g / m 2 ~8g / m 2 It is preferable to apply it in the range of 1.5 g / m 2 ~8g / m 2 It is more preferable to apply it in the range of 1.5 g / m 2 ~7.5g / m 2 It is more preferable to apply it in the range of 1.5 g / m 2 ~7g / m 2 It is most preferable to give it in the range of

[0091] The total amount of the above to be applied is 1g / m 2 ~8g / m 2 When the amount is within this range, the polymerizable liquid crystal compound is more uniformly aligned, and an image with high color development can be obtained.

[0092] In the ink application step, the amount of the polymerizable liquid crystal compound contained in the ink applied per unit area was set to 1 g / m2 even in areas other than the mixed area. 2 ~8g / m 2 It is preferable to apply it in the range of 1.5 g / m 2 ~8g / m 2 It is more preferable to apply it in the range of 1.5 g / m 2 ~7.5g / m 2 It is more preferable to apply it in the range of 1.5 g / m 2 ~7g / m 2 It is most preferable to give it in the range of

[0093] In the ink application step, the total amount of organic solvents contained in at least two types of ink applied per unit area is set to 1.5 g / m 2 ~12.5g / m 2 It is preferable to apply the coating in the range of 2.5 g / m 2 ~12.5g / m 2 It is more preferable to apply it in the range of 2.5 g / m 2 ~10g / m 2 It is more preferable to give it in the range of

[0094] In particular, in the mixed region, at least two types of ink are mixed, so the total amount of organic solvent contained in the ink is greater than in regions other than the mixed region. 2 ~12.5g / m 2 By applying the ink within the range of , the ink droplets that land are less likely to spread, and a high-definition image can be obtained.

[0095] In the ink application process, the amount of organic solvent contained in the ink applied per unit area was set to 1.5 g / m2 even in areas other than the mixed area. 2~12.5g / m 2 It is preferable to apply the coating in the range of 2.5 g / m 2 ~12.5g / m 2 It is more preferable to apply it in the range of 2.5 g / m 2 ~10g / m 2 It is more preferable to give it in the range of

[0096] The amount of ink applied is calculated using the following method. The desired dot ratio (the ratio of the area where the image is recorded to the total area calculated as a percentage) is applied to the substrate. 2 An image is recorded with an area of ​​. The weight of the substrate before and after image recording is measured, and the amount of ink applied is calculated from the weight difference. The amount of ink applied can be changed as desired by setting the dot ratio and adjusting the ink discharge amount of the device.

[0097] The amount of the polymerizable liquid crystal compound contained in the ink to be applied is calculated from the amount of ink to be applied and the content of the polymerizable liquid crystal compound contained in the ink.

[0098] The amount of the organic solvent contained in the ink to be applied is calculated from the amount of ink applied and the content of the organic solvent contained in the ink.

[0099] The total amount of ink applied in the mixed region is calculated as the sum of the amounts of each ink applied.

[0100] In the ink application step, the ink is applied so that the droplet volume of the ink ejected from the inkjet head is preferably 1 pL (picoliter) to 30 pL, and more preferably 2 pL to 10 pL. Note that the droplet volume refers to the volume of ink ejected from one nozzle at a time by the inkjet recording method.

[0101] In the ink application step, the ink is preferably applied so that the resolution is 100 dpi (dots per inch) × 100 dpi to 2400 dpi × 2400 dpi, and more preferably 200 dpi × 200 dpi to 1200 dpi × 1200 dpi, where "dpi" refers to the number of dots per 25.4 mm.

[0102] In the ink application step, the inks are preferably applied so that the thickness of the ink film formed by at least two types of ink in the mixed region is 1 μm to 20 μm, more preferably 1 μm to 15 μm, in one image recording. When the ink film is applied so that it is 1 μm to 20 μm thick, the applied ink dries easily, the polymerizable liquid crystal compound is more uniformly oriented, and an image with high color development is obtained.

[0103] The image recording method of the present disclosure includes a step of irradiating at least two types of ink with active energy rays (hereinafter also referred to as an "active energy ray irradiation step").

[0104] In the active energy ray irradiation step, examples of the active energy ray include ultraviolet rays, visible light, and electron beams, and among these, ultraviolet rays (hereinafter also referred to as "UV") are preferred.

[0105] The peak wavelength of the ultraviolet light is preferably 200 nm to 405 nm, more preferably 220 nm to 390 nm, and even more preferably 220 nm to 380 nm.

[0106] The UV exposure dose was 20 mJ / cm 2 ~5J / cm 2 and preferably 100 mJ / cm 2 ~1,500mJ / cm 2The irradiation conditions and basic irradiation method can be those disclosed in JP-A-60-132767. Specifically, the irradiation method is preferably a method in which light sources are provided on both sides of a head unit including an ink ejection device and the head unit and light sources are scanned using a so-called shuttle method, or a method in which irradiation is performed using a separate light source that does not involve driving.

[0107] Mercury lamps, gas lasers, and solid-state lasers are mainly used as light sources for ultraviolet irradiation, with mercury lamps, metal halide lamps, and ultraviolet fluorescent lamps being widely known. Furthermore, UV-LEDs (light-emitting diodes) and UV-LDs (laser diodes) are small, have a long life, are highly efficient, and are low-cost, and are expected to be light sources for ultraviolet irradiation. Among these, metal halide lamps, high-pressure mercury lamps, medium-pressure mercury lamps, low-pressure mercury lamps, or UV-LEDs are preferred light sources for ultraviolet irradiation.

[0108] [Inkjet recordings] The inkjet recording material of the present disclosure comprises a substrate and an ink film containing a liquid crystal polymer provided on the substrate, and the ink film includes, in a planar view, a plurality of regions having mutually different maximum reflection wavelengths, and the orientation state of the liquid crystal polymer changes continuously between two adjacent regions.

[0109] The inkjet recorded matter of the present disclosure is preferably an inkjet recorded matter obtained by the image recording method described above. For example, by applying an ink containing a polymerizable liquid crystal compound onto a substrate and then irradiating the substrate with active energy rays, the polymerizable liquid crystal compound is polymerized to form an ink film containing a liquid crystal polymer.

[0110] In the inkjet recorded matter of the present disclosure, the ink film may be provided directly on the substrate, or another layer may be provided between the substrate and the ink film.

[0111] The ink film includes, in plan view, a plurality of regions with mutually different maximum reflection wavelengths, and therefore a variety of colors can be reproduced with high color development.

[0112] The alignment state of the liquid crystal polymer between two adjacent regions can be confirmed by the following method.

[0113] First, the ink film is cut in the thickness direction to obtain a sample, so that it includes multiple regions with different maximum reflection wavelengths in a plan view. Using a scanning electron microscope (model "S-4800" manufactured by Hitachi High-Technologies Corporation, observation magnification: 10,000x, accelerating voltage: 2.0 kV), SEM images of the cross section are observed to check for the presence of stripes of varying density due to changes in the refractive index of the cholesteric liquid crystal phase. If stripes are observed, the sample is determined to be a cholesteric liquid crystal phase.

[0114] In the cross-sectional SEM image, one period of the dark and light striped regions corresponds to 180 degrees of twist in the liquid crystal. Therefore, two periods of the dark, light, dark, light striped regions correspond to 360 degrees of twist in the liquid crystal. In other words, the width of two periods of the light and dark striped regions corresponds to the length of the helical pitch in the cholesteric liquid crystal phase.

[0115] Since the ink film contains multiple regions with different maximum reflection wavelengths, the maximum reflection wavelengths of two adjacent regions are also different. Therefore, the helical pitch length of the cholesteric liquid crystal phase is different between the two adjacent regions. In this case, if the helical pitch length changes continuously between the two adjacent regions, it is determined that the orientation state of the liquid crystal polymer is changing continuously. [Example]

[0116] The present disclosure will be explained in more detail below using examples, but the present disclosure is not limited to the following examples as long as it does not deviate from the gist of the disclosure. The viscosity of the ink is measured using a viscometer (product name "RE-85L", manufactured by Toki Sangyo Co., Ltd.) while maintaining the liquid temperature at 25°C. The surface tension of the ink is measured using a surface tensiometer (product name "DY-700", manufactured by Kyowa Interface Science Co., Ltd.).

[0117] Example 1 [Ink preparation] (Ink Bm1) Ink Bm1 was prepared by mixing the components shown below. The viscosity of ink Bm1 (25°C) was 11 mPa·s. Diethylene glycol diethyl ether...61.27 parts by mass Polymerizable liquid crystal compound mixture A1...35 parts by mass Polymerization initiator: bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (product name "Omnirad 819") ... 1.5 parts by mass Chiral compound A: 2.2 parts by mass Fluorine-based surfactant (product name "Ftergent 208G", manufactured by Neos Co., Ltd.) ... 0.03 parts by mass The mixture of polymerizable liquid crystal compounds was prepared in the following ratio. Mixture A1 of polymerizable liquid crystal compounds: 50% by mass of compound (10), 50% by mass of compound (11) Mixture A2 of polymerizable liquid crystal compounds: 50% by mass of compound (10), 50% by mass of compound (12) Mixture A3 of polymerizable liquid crystal compounds: 33% by mass of compound (10), 34% by mass of compound (11), and 33% by mass of compound (12) Compounds (10) to (12) are rod-shaped liquid crystal compounds. Compounds (10), (11), and (12) (X 1 =2) and the structure of chiral compound A are as follows:

[0118] (Compounds (10), (11) and (12))

[0119] [ka]

[0120] (Chiral Compound A)

[0121] [ka]

[0122] The reflectance in the visible light region of the ink film formed with ink Bm1 was measured using a spectroscopic reflectometer (Konica Minolta, product name "FD-7"), and it was found that ink Bm1 formed an ink film with a maximum reflection wavelength of 440 nm. Furthermore, when the polarization characteristics were measured using a left-handed circular polarizer, no reflection spectrum was obtained. In other words, ink composition Bm1 was an ink that formed a right-handed polarized blue ink film. The surface tension of ink Bm1 was 28 mN / m. Unless otherwise noted, measurements were also performed on other inks using the same method as ink Bm1.

[0123] (Ink Rm1) Ink Rm1 was prepared in the same manner as Ink Bm1, except that the content of chiral compound A in Ink Bm1 was changed from 2.2 parts by mass to 1.6 parts by mass, and the content of diethylene glycol diethyl ether was adjusted so that the total ink content was the same as Ink Bm1. The viscosity of Ink Rm1 (25°C) was 11 mPa·s. Ink Rm1 formed a right-polarized red ink film that reflected right-handed circularly polarized light with a maximum reflection wavelength of 620 nm. The surface tension of Ink Rm1 was 27.6 mN / m.

[0124] [Image recording] A PET sheet (product name "Viewful UV TP-188" manufactured by Kimoto Co., Ltd.) was used as the substrate. The substrate was placed on a hot plate made by bonding a rubber heater to a metal plate and heated to 60°C. Ink Bm1 and Ink Rm1 were ejected onto the substrate heated to 60°C using an inkjet printer (product name "UJF3042HG" manufactured by Mimaki Engineering Co., Ltd.). Data was created with an image resolution of 600 dpi x 720 dpi. The ink Bm1 and Ink Rm1 application ratios were adjusted to 100:0, 83:17, 2:1, 50:50, 1:2, 17:83, and 0:100, respectively. The images were arranged vertically without gaps, with 7 mm square images. An inverted image of each was then placed next to it. Using the image data created, the total ink application amount in each image area was adjusted to 15 g / m. 2 After image recording was completed, the substrate was held at 60°C for 1 minute, and then heated at 80°C for 5 minutes. After that, ultraviolet A rays (UV-A, wavelength 320-390 nm) were irradiated at 350 mJ / cm using a metal halide lamp mounted in an ultraviolet irradiation device (product name "CSOT-40", manufactured by GS Yuasa Corporation). 2 Image recording 1 was obtained. Image Record 2 was also obtained in the same manner as Image Record 1, except that the 7 mm square image was changed to a 2 mm square image.

[0125] <Example 2> [Ink preparation] (Ink Gm1) Ink Gm1 was prepared in the same manner as Ink Bm1, except that the content of chiral compound A in Ink Bm1 was changed from 2.2 parts by mass to 1.9 parts by mass, and the content of diethylene glycol diethyl ether was adjusted so that the total ink content was the same as Ink Bm1. The viscosity of Ink Rm1 (25°C) was 11 mPa·s. Ink Gm1 formed a right-polarized green ink film that reflected right-handed circularly polarized light with a maximum reflection wavelength of 510 nm. The surface tension of Ink Gm1 was 28 mN / m.

[0126] [Image recording] A PET sheet (product name "Viewful UV TP-188" manufactured by KIMOTO Co., Ltd.) was used as the substrate. The substrate was placed on a rubber heater and heated to a temperature of 60°C. Ink Bm1, Ink Rm1, and Ink Gm1 were ejected onto the substrate heated to 60°C using an inkjet printer (product name "UJF3042HG" manufactured by Mimaki Engineering Co., Ltd.). Image data was prepared with an image resolution of 600 dpi x 720 dpi, with the application rate ratios of Ink Bm1, Ink Rm1, and Ink Gm1 adjusted to 1:0:0, 2:1:0, 1:2:0, 0:1:0, 0:2:1, 0:1:2, and 0:0:1, respectively. Using the prepared image data, the total application rate of ink in each image area was adjusted to 15 g / m. 2 The ink droplet volume was adjusted so that the image was recorded without gaps, as in Example 1. After image recording, the substrate was held at 60°C for 1 minute, and then heated at 80°C for 5 minutes. After that, ultraviolet A rays (UV-A, wavelength 320 to 390 nm) were irradiated at 350 mJ / cm using a metal halide lamp mounted in an ultraviolet irradiation device (product name "CSOT-40", manufactured by GS Yuasa Corporation). 2 Image recording material 1 and image recording material 2 were obtained.

[0127] Example 3 In Example 1, the total amount of ink applied in each image area was 7 g / m 2 Image Recorded Material 1 and Image Recorded Material 2 were obtained in the same manner as in Example 1, except that the ink droplet volume was adjusted so that:

[0128] Example 4 Image recorded material 1 and image recorded material 2 were obtained in the same manner as in Example 3, except that the temperature of the substrate when the ink was ejected was changed to 50°C.

[0129] <Example 5> Image Recorded Materials 1 and 2 were obtained in the same manner as in Example 3, except that the temperature of the substrate when ejecting the ink was changed to 80°C and the substrate was held at 80°C for 5 minutes after image recording was completed. In other words, in Example 5, no additional heating was applied to the substrate.

[0130] Example 6 Image Recorded Materials 1 and 2 were obtained in the same manner as in Example 3, except that in Example 5 the temperature of the substrate when ejecting the ink was changed to 90°C and the substrate was held at 90°C for 5 minutes after image recording was completed. In other words, in Example 6, no additional heating was applied to the substrate.

[0131] Example 7 In Example 2, the total amount of ink applied in each image area was 7 g / m 2 Image Recorded Material 1 and Image Recorded Material 2 were obtained in the same manner as in Example 2, except that the ink droplet volume was adjusted so that:

[0132] Example 8 Image recorded material 1 and image recorded material 2 were obtained in the same manner as in Example 7, except that the temperature of the substrate when the ink was ejected was changed to 50°C.

[0133] Example 9 Image Recorded Material 1 and Image Recorded Material 2 were obtained in the same manner as in Example 7, except that the temperature of the substrate when ejecting the ink was changed to 80°C and the substrate was held at 80°C for 5 minutes after image recording was completed. In other words, in Example 9, no additional heating was applied to the substrate.

[0134] Example 10 In Example 7, the total amount of ink applied in each image area was 3 g / m 2 Image Recorded Material 1 and Image Recorded Material 2 were obtained in the same manner as in Example 7, except that the ink droplet volume was adjusted so that:

[0135] Example 11 In Example 7, the total amount of ink applied in each image area was 1.2 g / m 2 Image Recorded Material 1 and Image Recorded Material 2 were obtained in the same manner as in Example 7, except that the ink droplet volume was adjusted so that:

[0136] Example 12 In Example 1, the total amount of ink applied in each image area was 21 g / m 2 Image Recorded Material 1 and Image Recorded Material 2 were obtained in the same manner as in Example 1, except that the ink droplet volume was adjusted so that: <Comparative Example 1> Image Recorded Material 1 and Image Recorded Material 2 were obtained in the same manner as in Example 1, except that the substrate was not heated but was kept at room temperature (25° C.).

[0137] <Comparative Example 2> Image Recorded Material 1 and Image Recorded Material 2 were obtained in the same manner as in Example 2, except that the substrate was not heated but was kept at room temperature (25° C.).

[0138] Example 13 [Ink preparation] (Ink Bm2) Ink Bm2 was prepared by mixing the components shown below. The viscosity of ink Bm2 (25°C) was 6 mPa·s. Diethylene glycol diethyl ether...68.27 parts by mass Polymerizable liquid crystal compound mixture A1: 28 parts by mass Polymerization initiator: bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Product name: “Omnirad 819, manufactured by IGM Resins BV”) …1.5 parts by mass Chiral compound A: 2.2 parts by mass Fluorine-based surfactant (product name "Ftergent 208G", manufactured by Neos Co., Ltd.) ... 0.03 parts by mass Ink Bm2 was an ink that formed a right-polarized blue ink film that reflected right-handed circularly polarized light with a selective reflection wavelength of 430 nm. The surface tension of ink Bm2 was 27 mN / m.

[0139] (Ink Rm2) Ink Rm2 was prepared in the same manner as Ink Bm2, except that the content of chiral compound A in Ink Bm2 was changed from 2.2 parts by mass to 1.6 parts by mass, and the content of diethylene glycol diethyl ether was adjusted so that the total ink content was the same as Ink Bm2. The viscosity of Ink Rm1 (25°C) was 6 mPa·s. Ink Rm2 formed a right-polarized red ink film that reflected right-handed circularly polarized light with a maximum reflection wavelength of 620 nm. The surface tension of Ink Rm2 was 27 mN / m.

[0140] [Image recording] An image recording was obtained in the same manner as in Example 5, except that ink Bm2 was used instead of ink Bm1 and ink Rm2 was used instead of ink Rm1.

[0141] Example 14 [Ink preparation] (Ink Rm3) Ink Rm3 was prepared in the same manner as Ink Rm1, except that the fluorosurfactant content in Ink Rm1 was changed from 0.03 parts by mass to 0.2 parts by mass, and the diethylene glycol diethyl ether content was adjusted so that the total ink content was the same as Ink Rm1. The viscosity of Ink Rm3 (at 25°C) was 11 mPa·s. Ink Rm2 was an ink that formed a right-polarized red ink film that reflected right-handed circularly polarized light with a maximum reflection wavelength of 620 nm. The surface tension of Ink Rm3 was 25 mN / m. [Image recording] An image recorded matter was obtained in the same manner as in Example 5, except that ink Rm3 was used instead of ink Rm1.

[0142] Table 1 lists the types of ink used in the examples and comparative examples; the amounts of ink, organic solvent, and polymerizable liquid crystal compound applied; the maximum absolute value of the difference in surface tension; and the temperature of the substrate when the ink was ejected.

[0143] The maximum absolute value of the difference in surface tension was determined by calculating the absolute value of the difference in surface tension between the inks, and taking the largest of the calculated absolute values.

[0144] <Evaluation> (1) Color development in multiple wavelength ranges The prepared image recording 1 was placed on the black side of a hiding power measurement paper (JIS K 5600), and the spectral reflectance spectrum was measured in multiple wavelength regions using a spectral reflectance meter (product name "FD-7" manufactured by Konica Minolta, Inc.) to evaluate color development in multiple color gamuts. The measurements were performed under the following conditions: reflection measurement, observation field of view 2°, observation illuminant D50, and no polarizing filter. Specifically, the spectral reflectance spectrum was measured in seven wavelength regions: 420 nm to 460 nm, 465 nm to 475 nm, 480 nm to 520 nm, 525 nm to 550 nm, 555 nm to 565 nm, 570 nm to 605 nm, and 610 nm to 730 nm, and it was confirmed whether or not a reflection wavelength peak was present in each wavelength region. In addition, it was confirmed whether or not the same color as image recording 1 was visible for image recording 2. The evaluation criteria were as follows. The evaluation results are shown in Table 1. <Evaluation criteria> 7: Image recording 1 has a reflection wavelength peak with a reflectance of 1% or more in all wavelength ranges, and it is visually confirmed that image recording 2 reproduces the same colors as image recording 1 in all wavelength ranges. 6: In image recording 1, there are 4 to 6 regions in which the reflection wavelength peak has a reflectance of 1% or more in all wavelength regions, and in image recording 2, the same color as in image recording 1 can be reproduced. 5: In image recording 1, there are six wavelength regions with reflection wavelength peaks with reflectance of 1% or more, and in image recording 2, it is visually confirmed that the same colors as in image recording 1 are reproduced in all wavelength regions. 4: In image recording 1, there are six wavelength regions with reflection wavelength peaks with reflectance of 1% or more, and in image recording 2, there are four or five regions in which the same color as in image recording 1 can be reproduced. 3: In image recording 1, there are five wavelength regions with reflection wavelength peaks with reflectance of 1% or more, and in image recording 2, it is visually confirmed that the same colors as in image recording 1 are reproduced in all wavelength regions. 2: In image recording 1, there are five wavelength regions with reflection wavelength peaks with reflectance of 1% or more, and in image recording 2, there are four regions where the same color as in image recording 1 can be reproduced. 1: In image recording 1, there are four or fewer wavelength regions with reflection wavelength peaks with reflectance of 1% or more, or in image recording 2, there are three or fewer regions in which the same color as in image recording 1 can be reproduced.

[0145] (2) Glossiness The prepared image recording 1 was placed on the black side of a hiding power measurement paper (standard: JIS K 5600, manufactured by TP Giken). The image was visually observed and the glossiness was evaluated. The evaluation criteria are as follows: 2 or higher is a practically acceptable level. The evaluation results are shown in Table 1. <Evaluation criteria> 4: Excellent gloss. 3: It has a glossy finish. 2: It has a slight sheen. 1: No gloss and the color appears dull.

[0146] (3) Uniformity The prepared image recording 1 was placed on the black side of a hiding power measurement paper (JIS K 5600), and the target observation area was visually inspected for cloudiness or unevenness. The target observation area was a mixed area where at least two types of ink were mixed. If the image was free of cloudiness or unevenness, it can be said that the image had high uniformity. The evaluation criteria were as follows: 2 or above is a practically acceptable level. The evaluation results are shown in Table 1. <Evaluation criteria> 4: No cloudiness or unevenness. 3: There is very little cloudiness or unevenness. 2: There is slight cloudiness or unevenness that can be seen with the naked eye. 1: There is clear cloudiness or unevenness, and it is problematic for practical use.

[0147] (4) Image quality (resolution) The prepared image recording was placed on the black side of a hiding power measurement paper (JIS K 5600), and visual observation was made to see whether or not there was any color mixing between adjacent image areas. The evaluation criteria were as follows: 2 or higher is a practically acceptable level. The evaluation results are shown in Table 1. <Evaluation criteria> 5: No or very little color mixing is observed. 4: Very slight color mixing is observed. 3: There is a slight mixture of colors, but the mixed areas are not noticeable. 2: There is some color mixing, and the mixed color areas are somewhat noticeable. 1: Large, noticeable areas where the colors are completely mixed.

[0148] [Table 1]

[0149] As shown in Table 1, Examples 1 to 13 include the steps of preparing at least two inks, including a first ink and a second ink, heating a substrate, applying the at least two inks to the heated substrate using an inkjet recording method, and irradiating the at least two inks with actinic energy rays. In the step of applying the at least two inks, the inks were applied so as to form a mixed region in which the at least two inks were mixed on at least a portion of the substrate. This demonstrated excellent color development in multiple wavelength ranges. In other words, Examples 1 to 13 demonstrated that a wide variety of colors could be reproduced with high color development.

[0150] On the other hand, Comparative Examples 1 and 2 did not include a step of heating the substrate, and at least two types of ink were not applied onto the heated substrate, so it was not possible to reproduce a variety of colors with high color development.

[0151] In Example 1, the total amount of at least two types of ink applied per unit area in the mixed region was 3 g / m 2 ~20g / m 2 As a result, compared to Example 12, a wider variety of colors could be reproduced with high color development, cloudiness and unevenness in the image were suppressed, and a glossier image was obtained.

[0152] In Example 2, the inks were applied so that a mixed area where the three inks were mixed was formed on a part of the substrate, so that a wider variety of colors could be reproduced with high color development compared to Example 1.

[0153] In Example 3, the total amount of at least two inks applied per unit area in the mixed region was 3.5 g / m 2 ~13g / m 2 As a result, compared to Example 1, a wider variety of colors could be reproduced with high color development, cloudiness and unevenness in the image were suppressed, and a higher-resolution, glossy image was obtained.

[0154] In Example 3, the temperature of the substrate when the ink was ejected was 55°C or higher, so compared to Example 4, a wider variety of colors could be reproduced with high color development, cloudiness and unevenness in the image were suppressed, and a higher-resolution, glossy image was obtained.

[0155] In Example 5, the temperature of the substrate when the ink was ejected was 80° C. or less, and therefore, compared to Example 6, cloudiness and unevenness in the image were further suppressed.

[0156] In Example 7, the total amount of at least two inks applied per unit area in the mixed region was 13 g / m 2 In Example 10, a wider variety of colors could be reproduced with high color development, cloudiness and unevenness of the image were suppressed, and a more precise and glossy image was obtained compared to Example 2. Furthermore, since three types of ink were used, the color development was superior to that of Example 3. Furthermore, in Example 10, in the mixed region, the total application amount per unit area of ​​at least two types of ink was 3 g / m 2 ~20g / m 2As a result, compared to Example 11, a wider variety of colors could be reproduced with high color development.

[0157] In Example 7, the temperature of the substrate when the ink was ejected was 55°C or higher, so compared to Example 8, a wider variety of colors could be reproduced with high color development, cloudiness and unevenness in the image were suppressed, and a higher-resolution, glossy image was obtained.

[0158] In Example 5, at least two types of ink each had a viscosity of 7 mPa·s or more, so compared to Example 13, a wider variety of colors could be reproduced with high color development, and cloudiness and unevenness in the image were suppressed.

[0159] In Example 5, the maximum absolute value of the difference in surface tension between the inks was 1 mN / m or less, so compared to Example 14, a wider variety of colors could be reproduced with high color development, cloudiness and unevenness in the image were suppressed, and a higher-resolution image was obtained.

[0160] <Examples 101 to 103> [Image recording] Image recording material 1 and image recording material 2 were obtained in the same manner as in Examples 1, 3, and 7, except that the inkjet recording device was changed to an inkjet printer (product name "SUJV-160", manufactured by Mimaki Engineering Co., Ltd.), the heater temperature was set to 70°C, and exposure was performed using an exposure device built into the inkjet printer.

[0161] When the same evaluations as in Examples 1, 3, and 7 were carried out, it was found that Examples 101 to 103 were also able to reproduce a variety of colors with high color development.

[0162] <Example 200> [Ink preparation] (Ink Nm1) Ink Nm1 was prepared by mixing the components shown below. The viscosity of ink Nm1 (at 25°C) was 9 mPa·s. Diethylene glycol diethyl ether...63.43 parts by mass Polymerizable liquid crystal compound mixture: 35 parts by weight Polymerization initiator: bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Product name: “Omnirad 819, manufactured by IGM Resins BV”) …1.5 parts by mass Fluorine-based surfactant (product name "Ftergent 208G", manufactured by Neos Co., Ltd.) ... 0.03 parts by mass The mixture of polymerizable liquid crystal compounds contained 33.4% by mass of compound (10), 33.3% by mass of compound (11), and compound (12) (X 1 =2) 33.3% by mass Compounds (10) to (12) are rod-shaped liquid crystal compounds.

[0163] (ink Nm2) Ink Nm2 was prepared by mixing the components shown below. The viscosity of ink Nm2 (at 25°C) was 1.7 mPa·s. Diethylene glycol diethyl ether...94.7 parts by mass Polymerization initiator: bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Product name: “Omnirad 819, manufactured by IGM Resins BV”) …1.5 parts by mass Chiral compound A...4 parts by mass Fluorine-based surfactant (product name "Ftergent 208G", manufactured by Neos Co., Ltd.) ... 0.03 parts by mass

[0164] [Image recording] A PET sheet (product name "Viewful UV TP-188" manufactured by KIMOTO Co., Ltd.) was used as the substrate. The substrate was placed on a rubber heater and heated to 60°C. Ink Nm1 and Ink Nm2 were ejected onto the substrate heated to 60°C using an inkjet printer (product name "UJF3042HG" manufactured by Mimaki Engineering Co., Ltd.). An ink image was recorded at an image resolution of 600 dpi x 720 dpi by varying the amount of Ink Nm2 applied so that a mixed region where Ink Nm1 and Ink Nm2 were mixed was formed. After image recording was completed, the substrate was held at 60°C for 1 minute and then further heated at 80°C for 5 minutes. After that, ultraviolet A rays (UV-A, wavelength 320-390 nm) were irradiated at 350 mJ / cm using a metal halide lamp mounted on an ultraviolet irradiation device (product name "CSOT-40" manufactured by GS Yuasa Corporation). 2 Image recording 1 was obtained. Image Record 2 was also obtained in the same manner as Image Record 1, except that the 7 mm square image was changed to a 2 mm square image.

[0165] It was found that the hue of the resulting image recording differed depending on the amount of ink applied (Nm2). That is, in Example 200 as well, a variety of colors could be reproduced with high color development.

[0166] <Examples 15 to 28> Image recorded materials 1 and 2 were obtained in the same manner as in Examples 1 to 14, except that the mixture A1 of polymerizable liquid crystal compounds in Examples 1 to 14 was changed to the mixture A2 of polymerizable liquid crystal compounds. When the same evaluations as in Examples 1 to 14 were carried out, similar results were obtained in Examples 15 to 28.

[0167] <Examples 104 to 106> In Examples 101 to 103, the inks used were the same as in Examples 15, 17, and 21, and evaluations were carried out in the same manner as in Examples 15, 17, and 21. As a result, in Examples 104 to 106, a variety of colors could also be reproduced with high color development.

[0168] <Examples 29 to 42> Image recorded materials 1 and 2 were obtained in the same manner as in Examples 1 to 14, except that the mixture A1 of polymerizable liquid crystal compounds in Examples 1 to 14 was changed to the mixture A3 of polymerizable liquid crystal compounds. When the same evaluations as in Examples 1 to 14 were carried out, similar results were obtained in Examples 29 to 42.

[0169] <Examples 107 to 109> In Examples 101 to 103, the inks used were the same as in Examples 29, 31, and 35, and evaluations were carried out in the same manner as in Examples 29, 31, and 35. As a result, in Examples 107 to 109, a variety of colors could also be reproduced with high color development.

[0170] The disclosure of Japanese Patent Application No. 2020-217654, filed on December 25, 2020, is incorporated herein by reference in its entirety. In addition, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated to be incorporated by reference.

Claims

1. providing at least two inks including a first ink and a second ink; heating the substrate; applying the at least two inks onto a heated substrate using an inkjet recording method; and irradiating the at least two types of ink with actinic energy rays, In the step of applying the at least two types of ink, a mixed region in which the at least two types of ink are mixed with each other is formed on at least a part of the substrate by the application, The image recording method, wherein the first ink contains a first polymerizable liquid crystal compound, and the second ink contains a second chiral compound.

2. the first ink contains the first polymerizable liquid crystal compound, a first chiral compound, and a first organic solvent; the second ink contains a second polymerizable liquid crystal compound, the second chiral compound, and a second organic solvent; 2. The image recording method according to claim 1, wherein an absolute value of a difference between a maximum reflection wavelength of the ink film formed by the first ink and a maximum reflection wavelength of the ink film formed by the second ink is 100 nm or more.

3. 3. The image recording method according to claim 1, wherein the ink film formed by the first ink has a maximum reflection wavelength of 380 nm to 490 nm, and the ink film formed by the second ink has a maximum reflection wavelength of 600 nm to 800 nm.

4. In the step of preparing at least two kinds of inks, a third ink containing a third polymerizable liquid crystal compound, a third chiral compound, and a third organic solvent is further prepared; 4. The image recording method according to claim 1, wherein an absolute value of a difference between a maximum reflection wavelength of an ink film formed by the first ink, a maximum reflection wavelength of an ink film formed by the second ink, and a maximum reflection wavelength of an ink film formed by the third ink is 40 nm or more.

5. 5. The image recording method according to claim 4, wherein the ink film formed by the first ink has a maximum reflection wavelength of 380 nm to 490 nm, the ink film formed by the second ink has a maximum reflection wavelength of 600 nm to 800 nm, and the ink film formed by the third ink has a maximum reflection wavelength of 500 nm to 590 nm.

6. In the step of applying the at least two types of ink, a total application amount of the at least two types of ink per unit area is set to 3 g / m in the mixed region. ２ ~20g / m ２ The image recording method according to any one of claims 1 to 5, wherein the range is given as:

7. In the step of applying the at least two kinds of inks, the total amount of polymerizable liquid crystal compounds contained in the at least two kinds of inks applied per unit area in the mixed region is 1.5 g / m ２ ~8g / m ２ The image recording method according to any one of claims 2 to 6, wherein the range is given as:

8. In the step of applying the at least two kinds of inks, the total amount of the organic solvents contained in the at least two kinds of inks applied per unit area in the mixing region is 2.5 g / m ２ ~12.5g / m ２ The image according to any one of claims 2 to 7, Image recording method.

9. 9. The image recording method according to claim 1, wherein each of the at least two types of ink has a viscosity of 7 mPa·s or more.

10. 10. The image recording method according to claim 1, wherein the at least two types of ink have a maximum absolute value of the difference in surface tension between the inks of 1 mN / m or less.

11. The image recording method according to any one of claims 1 to 10, wherein in the step of heating the substrate, the substrate is heated to 40°C or higher.

Images