Ink and thermal transfer recording sheet

Abstract

To provide: an ink having good storage stability and high light resistance; an ink having high optical density and excellent color development stability during heat pressing; and a thermal transfer recording sheet in which fading due to mixing of two different yellow colorants used in a yellow colorant layer of the thermal transfer recording sheet is suppressed.SOLUTION: An ink comprises a medium and carrier particles dyed with a compound represented by general formula (1) and a compound represented by general formula (2). An ink comprises an aqueous medium, a dispersant, a compound represented by general formula (1), and a compound represented by general formula (2). A thermal transfer recording sheet has a yellow colorant layer containing a compound represented by general formula (1) and a compound represented by general formula (2).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an ink and a thermal transfer recording sheet. [Background technology]

[0002] In the apparel industry, the large amount of industrial wastewater generated during the dyeing process of various fabrics is considered a problem from the viewpoint of environmental impact. Therefore, digital textile printing methods using inkjet printing or electrophotography have been actively developed in recent years as a method for providing printed products with low energy and low cost. For example, there are methods using ink containing pigments, methods using ink containing dye-dyed resin particles, and methods using ink containing sublimation dyes.

[0003] Aqueous inks containing pigments (aqueous pigment inks) have excellent lightfastness, but have the problem of tending to have poor color development. Furthermore, inks containing dye-dyed resin particles have difficulty achieving both lightfastness and color development. For example, Patent Document 1 reports an inkjet ink that uses resin particles colored with a coumarin dye as a colorant. However, the inventors' investigations have revealed that further improvement in lightfastness is required.

[0004] Additionally, in the field of writing instruments (especially ballpoint pens), there is growing demand for inks and functions that meet user requirements, such as writing feel, initial writing performance, and consistent, continuous writing. Ballpoint pens come in a variety of colors, including oil-based ballpoint pens, water-based ballpoint pens, and gel ink ballpoint pens, as well as black, red, blue, yellow, pink, green, and orange. Dyes, pigments, and mixtures of these are used as colorants in inks. For example, oil-based inks using pigments have excellent writing durability, but suffer from storage stability issues due to the tendency of pigments to aggregate and settle in the ink. Using oil-based inks with aggregated or settled pigments can result in poor writing results. In contrast, oil-based inks using dyes tend to be less prone to aggregation and settling than pigments due to their high solubility in solvents, resulting in less aggregation and settling and better storage stability, but they also tend to have poor lightfastness. For example, Patent Document 2 reports a ballpoint pen paste (ink for a writing instrument) using a methine dye or a coumarin dye as a colorant, but the inventors' investigations have revealed that further improvement is required in terms of light resistance. Furthermore, in image recording methods using sublimation transfer inks containing sublimation dyes, not only are images with high optical density required, but also suppression of color blur due to heat press temperatures is required to ensure color tone stability when repeatedly recording images. For example, Patent Document 3 reports an example of using inks that combine fluorescent and non-fluorescent sublimation dyes, but the inventors' investigations have revealed that the stability of image density (color development stability) due to differences in yellow image density and heat press temperature is insufficient. Furthermore, sublimation dyes can also be used in image recording methods using thermal transfer recording, which allows printing by a dry process. In thermal transfer recording, each colorant layer is typically formed by mixing two or three types of compounds. This poses the problem of discoloration due to color mixing between compounds of the same color during image recording. Therefore, studies have been conducted to prevent this discoloration in thermal transfer recording sheets. For example, Patent Document 4 proposes a solution by incorporating an anti-fading agent into the colorant layer. However, the inventors' studies have revealed that further improvement is needed to prevent discoloration due to color mixing of the same colors (hereinafter also referred to as "same-color mixing fading"). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-187337 [Patent Document 2] Japanese Patent Application Publication No. 8-20669 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-190932 [Patent Document 4] Japanese Patent Application Laid-Open No. 2001-158879 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide an ink having good storage stability and high lightfastness. Another object of the present invention is to provide an ink having high optical density and excellent color development stability during heat pressing. Still another object of the present invention is to provide a thermal transfer recording sheet in which discoloration due to mixing of the same colors is suppressed when two different yellow colorants are used in the yellow colorant layer of the thermal transfer recording sheet. [Means for solving the problem]

[0007] According to one aspect of the present invention, there is provided an ink containing a medium and carrier particles dyed with a compound represented by the following general formula (1) and a compound represented by the following general formula (2): [ka] [In general formula (1), R1 and R2 each independently represent an alkyl group; R3 represents an alkyl group, an aryl group, or an alkoxy group; R4 represents an alkyl group or an aryl group; [ka] [In general formula (2), R5 and R6 each independently represent an alkyl group; R7 and R8 each independently represent a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, or a halogen atom; X1 represents O, S, or N-R9, where R9 represents a hydrogen atom or an alkyl group.

[0008] According to another aspect of the present invention, there is provided an ink comprising an aqueous medium, a dispersant, a compound represented by the following general formula (1), and a compound represented by the following general formula (2): [ka] [In general formula (1), R1 and R2 each independently represent an alkyl group; R3 represents an alkyl group, an aryl group, or an alkoxy group; R4 represents an alkyl group or an aryl group; [ka] [In general formula (2), R5 and R6 each independently represent an alkyl group; R7 and R8 each independently represent a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, or a halogen atom; X1 represents O, S, or N-R9, where R9 represents a hydrogen atom or an alkyl group.

[0009] According to another aspect of the present invention, there is provided a thermal transfer recording sheet having a substrate and a yellow colorant layer formed on the substrate, A thermal transfer recording sheet, wherein the yellow colorant layer contains a compound represented by the following general formula (1) and a compound represented by the following general formula (2): [ka] [In general formula (1), R1 and R2 each independently represent an alkyl group; R3 represents an alkyl group, an aryl group, or an alkoxy group. R4 represents an alkyl group or an aryl group; [ka] [In general formula (2), R5 and R6 each independently represent an alkyl group; R7 and R8 each independently represent a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, or a halogen atom; X1 represents O, S, or N-R9, where R9 represents a hydrogen atom or an alkyl group. [Effects of the Invention]

[0010] According to one aspect of the present invention, an ink having good storage stability and high lightfastness can be provided. According to another aspect of the present invention, an ink having high optical density and excellent color development stability during heat pressing can be provided. According to yet another aspect of the present invention, a thermal transfer recording sheet can be provided in which two different yellow colorants used in the yellow colorant layer of the thermal transfer recording sheet are prevented from fading due to mixing of the same colors. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below. [First embodiment] As a result of intensive research conducted by the present inventors to solve the above problems, they found that by using a medium and carrier particles dyed with compounds represented by general formulas (1) and (2), it is possible to provide an ink having good storage stability and high light resistance.

[0012] Conventionally, inks using carrier particles dyed solely with a compound represented by general formula (1) have been prone to aggregation and have had problems with storage stability, while inks using carrier particles dyed solely with a compound represented by general formula (2) have had problems with poor lightfastness, although they do not aggregate.

[0013] The inventors' investigations have revealed that inks using carrier particles dyed with the compounds represented by general formulas (1) and (2) have good storage stability and high light resistance. The mechanism by which the above-mentioned effects are achieved by mixing the compounds represented by general formulas (1) and (2) is not clearly understood, but the inventors speculate as follows. This is because the compounds represented by general formulas (1) and (2) are structurally similar in size, and the two compounds overlap due to the π-π stacking interaction of the benzene rings provided by the dialkylamino groups of each compound. This overlapping stabilizes the two compounds, resulting in the aforementioned effects. In particular, in general formula (2), when X1 is NH, the hydrogen atom of NH and the oxygen atom of C=O in the coumarin skeleton form a stable six-membered ring structure through hydrogen bonding, resulting in the greatest aforementioned effects.

[0014] The composition of the ink according to this embodiment will be described in detail below. The ink according to this embodiment contains a medium and carrier particles dyed with compounds represented by general formulas (1) and (2). The ink according to this embodiment is suitable as an ink because it has good storage stability and high light resistance due to the use of carrier particles dyed with two specific types of compounds.

[0015] [Coloring agent] First, a compound represented by the following general formula (1), which is one of the colorants, will be described. [ka] [In general formula (1), R1 and R2 each independently represent an alkyl group; R3 represents an alkyl group, an aryl group, or an alkoxy group; R4 represents an alkyl group or an aryl group.

[0016] In general formula (1), the alkyl groups represented by R1 to R4 are not particularly limited, but specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. Among these, a linear or branched alkyl group having 1 to 4 carbon atoms is preferred. In particular, a methyl group or an ethyl group is more preferred, since the use of dyed resin particles makes it easier to obtain an ink with good storage stability and high lightfastness.

[0017] In general formula (1), the aryl group in R3 and R4 is not particularly limited, but both unsubstituted aryl groups and substituted aryl groups can be used. Examples of the substituent include an alkyl group, an alkoxy group, a carboxamide group, and a sulfonate salt group such as sodium sulfonate. Specific examples of the aryl group include a phenyl group, a naphthyl group, a methylphenyl group, a methoxyphenyl group, and a benzenecarboxamide group (aminocarbonylphenyl group). In particular, a phenyl group is more preferred because the use of dyed resin particles makes it easier to obtain an ink with good storage stability and high light resistance.

[0018] In general formula (1), the alkoxy group for R3 is not particularly limited, but examples thereof include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Among these, an alkoxy group having 1 to 4 carbon atoms is preferred. In particular, a methoxy group or an ethoxy group is more preferred, since the use of dyed resin particles makes it easier to obtain an ink with good storage stability and high light resistance.

[0019] The compound represented by general formula (1) has a cis-trans structural isomer represented by general formula (3), as shown in the following reaction scheme, which is within the scope of the present invention. R1 to R4 in the reaction scheme have the same meanings as described above. Note that the description of chemical formulas from this paragraph onwards will only show structures similar to general formula (1), but will include both cis-trans structural isomers. Furthermore, the compound represented by general formula (1) may also be a mixture of these structural isomers.

[0020] [ka]

[0021] Preferred examples of the compound represented by general formula (1) include compounds (1-1) to (1-5) shown below, but are not limited to these compounds. [ka]

[0022] The compound represented by the general formula (1) may be used alone, or two or more may be used in combination to adjust the color tone, etc., depending on the application. Furthermore, the compound may be used in combination with a known pigment or dye within a range that does not impair the effects of the present invention. The known pigment or dye to be combined may be one type alone or two or more types. Among these, compounds represented by general formula (1) in which R1 and R2 are each independently an alkyl group having 1 to 4 carbon atoms, and R3 is an alkoxy group having 1 to 4 carbon atoms are preferred. Compounds (1-2), (1-4), and (1-5) are particularly preferred. When resin particles dyed with any of these compounds are used, an ink having good storage stability and high lightfastness is easily obtained.

[0023] The compound represented by general formula (1) can be synthesized by a known method, but is also available as a commercially available product.

[0024] Next, another colorant, the compound represented by the following general formula (2), will be described. [ka] [In general formula (2), R5 and R6 each independently represent an alkyl group; R7 and R8 each independently represent a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, or a halogen atom; X1 represents O, S, or N-R9, where R9 represents a hydrogen atom or an alkyl group.

[0025] In general formula (2), the alkyl groups for R5 and R6 are not particularly limited, but specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. Among these, a linear or branched alkyl group having 1 to 4 carbon atoms is preferred. In particular, a methyl group or an ethyl group is more preferred, since the use of dyed resin particles makes it easier to obtain an ink with good storage stability and high lightfastness.

[0026] In general formula (2), the alkyl groups for R7 and R8 are not particularly limited, but specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. Among these, a linear or branched alkyl group having 1 to 4 carbon atoms is preferred. In particular, a methyl group or an ethyl group is more preferred, since the use of dyed resin particles makes it easier to obtain an ink with good storage stability and high lightfastness.

[0027] In the general formula (2), the aryl group in R7 and R8 is not particularly limited, but examples thereof include an unsubstituted phenyl group, a methylphenyl group, and a methoxyphenyl group. Among these, unsubstituted phenyl groups are particularly preferred, since the use of dyed resin particles makes it easier to obtain an ink with good storage stability and high light resistance.

[0028] In general formula (2), the alkoxy group in R7 and R8 is not particularly limited, but examples thereof include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, etc. Among these, a methoxy group or an ethoxy group is preferred, since the use of dyed resin particles makes it easier to obtain an ink with good storage stability and high lightfastness.

[0029] In general formula (2), the halogen atoms in R7 and R8 are not particularly limited, but examples include a chlorine atom, a bromine atom, a fluorine atom, etc. Among these, a chlorine atom is preferred because the use of dyed resin particles makes it easier to obtain an ink with good storage stability and high lightfastness.

[0030] In general formula (2), the alkyl group for R9 is not particularly limited, but examples thereof include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, 2-ethylpropyl, and 2-ethylhexyl. Among these, linear or branched alkyl groups having 1 to 8 carbon atoms are preferred. In particular, a methyl or ethyl group is preferred, since the use of dyed resin particles makes it easier to obtain an ink with good storage stability and high lightfastness.

[0031] Preferred examples of the compound having the structure represented by general formula (2) include compounds (2-1) to (2-21) shown below, but are not limited to these compounds.

[0032] [ka]

[0033] [ka]

[0034] [ka]

[0035] The compound represented by the general formula (2) may be used alone, or two or more may be used in combination to adjust the color tone, etc., depending on the application. Furthermore, the compound may be used in combination with a known pigment or dye within a range that does not impair the effects of the present invention. The known pigment or dye to be combined may be one type alone or two or more types.

[0036] Among these, compounds represented by general formula (2) in which R5 and R6 are each independently an alkyl group having 1 to 4 carbon atoms and X1 is O, NH, or N-CH3 are preferred. Compounds (2-1), (2-4), and (2-11) are particularly preferred. Using carrier particles dyed with any of these compounds makes it easy to obtain inks with good storage stability and high lightfastness.

[0037] The compound represented by formula (2) can be synthesized by a known method, but is also available as a commercially available product.

[0038] In the ink, the total amount of the compound represented by general formula (1) and the compound represented by general formula (2) is not particularly limited. Preferably, it is 0.5% by mass or more and 10.0% by mass or less, more preferably 1.0% by mass or more and 7.0% by mass or less, based on the total mass of the ink. Furthermore, the blending ratio of the compound represented by general formula (1) to the compound represented by general formula (2) is not particularly limited. Preferably, the mass ratio is in the range of 5 parts by mass or more and 90 parts by mass or less of the compound represented by general formula (2) per 10 parts by mass of the compound represented by general formula (1). More preferably, it is in the range of 10 parts by mass or more and 70 parts by mass or less, and even more preferably, it is in the range of 30 parts by mass or more and 50 parts by mass or less. By using carrier particles dyed with a colorant within this range, an ink with good storage stability and high lightfastness is likely to be obtained.

[0039] [Carrier particles] In this specification, "carrier particles" refers to carriers that can be dispersed in a medium and exist in the medium in a state of particle size. The carrier particles exist in a dispersed state in the ink. When the medium is an aqueous medium, the carrier particles exist in a dispersed state in the aqueous medium, i.e., in the state of a carrier emulsion. The carrier particles dyed with the colorant exist in a state in which the colorant is dispersed or colored in the carrier particles.

[0040] The carrier particles preferably have a cumulative 50% particle diameter (D50) of a volume-based particle size distribution of 140 nm or more and 300 nm or less. When D50 is 140 nm or more, a decrease in the lightfastness of the image can be suppressed. On the other hand, when D50 is 300 nm or less, a larger value can suppress a decrease in the ink ejection stability.

[0041] When the compounds represented by general formulas (1) and (2) are dyed onto carrier particles, the compounding ratio of the compounds represented by general formulas (1) and (2) to the carrier particles is not particularly limited. Preferably, the total amount of the compounds represented by general formulas (1) and (2) is 0.5 parts by mass or more and 20 parts by mass or less, and more preferably 1 part by mass or more and 10 parts by mass or less, per 100 parts by mass of the carrier particles. The content of dyed carrier particles is preferably 1% by mass or more and 10% by mass or less, and more preferably 3% by mass or more and 6% by mass or less, based on the total amount of ink.

[0042] Examples of carrier particles include resins and cellulose nanofibers. Examples of resin types include styrene polymers, acrylic acid polymers, methacrylic acid polymers, polyester resins, polyvinyl ether resins, polyvinyl methyl ether resins, polyvinyl alcohol resins, polyvinyl butyral resins, polyurethane resins, and polypeptide resins. These resins may be used alone or in combination of two or more types as needed. When carrier particles are made of resin, they may also be referred to as "resin particles."

[0043] The cellulose nanofibers are selected depending on the intended use. For example, they are obtained by chemically and / or mechanically defibrating plant fibers, and are ultrafine fibers with an average width of about several nm to 20 nm and an average length of about 0.5 μm to several μm. The size (fiber diameter) of these cellulose nanofibers varies depending on the type of cellulose nanofiber. Furthermore, a fiber diameter is selected within a range that does not impair the properties required for various applications, taking into account factors such as thickening effect, stability over time, and color development.

[0044] Materials containing cellulose fibers that can be used include plants such as wood, bamboo, kenaf, hemp, jute, wood pulp, waste paper, crystalline cellulose, agricultural waste, and recycled pulp, animals such as sea squirts, algae, and microorganisms.

[0045] Cellulose nanofibers are commercially available and can also be used. Examples of commercially available products include those sold under the trade names "Leocrysta I-2AX," "CNF 03," and "CNF 04" (all manufactured by Daiichi Chemical Industry Co., Ltd.), "ELLEX-S" (manufactured by Daio Paper Co., Ltd.), and "na noforest-S" (manufactured by Chuetsu Pulp Industry Co., Ltd.).

[0046] [Coloring agent] As described above, the ink contains a combination of at least one compound represented by formula (1) and at least one compound represented by formula (2) as a colorant, but may also contain a known colorant, etc., within the range that does not impair solubility or dispersibility in the medium. Examples of such colorants include, but are not limited to, condensed azo compounds, azo metal complexes, and methine compounds. The content of the colorant in the ink is not particularly limited and is set appropriately depending on the application. Preferably, the total content including any known colorant is 1.0 to 30.0 parts by mass, more preferably 2.0 to 20.0 parts by mass, and even more preferably 3.0 to 15.0 parts by mass, per 1000 parts by mass of the medium. If it is within the above range, sufficient coloring power can be obtained, and the dispersibility of the colorant will also be good.

[0047] [Method for producing dyed carrier particles] When resin particles are used as carrier particles, the resin particles can be produced by a conventionally known method, such as emulsion polymerization, mini-emulsion polymerization, seed polymerization, phase inversion emulsification, etc. Examples of methods for dyeing resin particles include a method of forming resin particles by polymerizing a monomer mixture in which compounds represented by general formulas (1) and (2) are dissolved, and a method of adding compounds represented by general formulas (1) and (2) to resin particles and heating them. When cellulose nanofibers are used as carrier particles, the cellulose nanofibers can be dyed, for example, by contacting the cellulose nanofibers with the compounds represented by general formulas (1) and (2) in an aqueous medium, followed by heating or oxidation treatment as necessary, and then distilling off the medium to obtain dyed cellulose nanofibers.

[0048] [Medium] In this embodiment, the term "medium" refers to, but is not limited to, water or an organic solvent, and is selected depending on the application and purpose of the ink. When an organic solvent is used as the medium, the type of organic solvent is selected depending on the application and purpose of the ink, and is not limited to the type of organic solvent. Examples of organic solvents include alcohols such as methanol, ethanol, isopropanol, butanol, 2-methyl-2-butanol, 3-pentanol, benzyl alcohol, and cyclohexanol; glycols such as methyl cellosolve, diethylene glycol, and diethylene glycol monobutyl ether; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters such as ethyl acetate, butyl acetate, and cellosolve acetate; aliphatic hydrocarbons such as octane, petroleum ether, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; ethers such as diethyl ether, dimethyl glycol, trioxane, and tetrahydrofuran; acetals such as diethyl acetal; organic acids such as formic acid, acetic acid, and propionic acid; and sulfur- or nitrogen-containing organic compounds such as monoethanolamine, pyridine, dimethyl sulfoxide, and dimethylformamide. Furthermore, a polymerizable monomer can also be used as the organic solvent. Examples of the polymerizable monomer include addition polymerizable monomers and condensation polymerizable monomers, and addition polymerizable monomers are preferred. Specific examples of the polymerizable monomer include styrene-based monomers such as styrene, methylstyrene, and ethylstyrene; acrylate-based monomers such as methyl acrylate, ethyl acrylate, behenyl acrylate, 2-ethylhexyl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, acrylonitrile, and acrylic acid amide; methacrylate-based monomers such as methyl methacrylate, ethyl methacrylate, diethylaminoethyl methacrylate, methacrylonitrile, and methacrylic acid amide; ethylene, propanol, and the like. Examples of the monomers include olefin monomers such as propylene, butylene, butadiene, isoprene, isobutylene, and cyclohexene; halogenated vinyl monomers such as vinyl chloride, vinylidene chloride, vinyl bromide, and vinyl iodide; vinyl ester monomers such as vinyl acetate, vinyl propionate, and vinyl benzoate; vinyl ether monomers such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether; and vinyl ketone monomers such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopropenyl ketone. These monomers may be used alone or in combination of two or more, as necessary. The content of the medium in the ink is selected depending on the purpose and use of the ink, and is not particularly limited.

[0049] In the ink, components other than the dyed resin particles are selected as appropriate depending on the application of the ink, including the medium. The following additives may also be added as appropriate, provided they do not impair the properties of the ink for various applications: polyhydric alcohols such as trimethylolpropane and trimethylolethane; urea derivatives such as urea and ethyleneurea; water-soluble resins, undyed resin particles, surfactants, pH adjusters, rust inhibitors, preservatives, antifungal agents, antioxidants, antireducing agents, evaporation accelerators, chelating agents, and cellulose nanofibers.

[0050] Examples of ultraviolet absorbers include benzophenone-based, benzotriazole-based, cyanoacrylate-based, and triazine-based ones. Commercially available ultraviolet absorbers include, for example, Tinuvin P, Tinuvin 326, Tinuvin 571, and Tinuvin 360 (all manufactured by BASF), and Adeka STAB LA-24, LA-29, LA-31RG, LA-32, LA-36, LA-46, LA-F70, and 1413 (all manufactured by ADEKA Corporation). Preferred are Adeka STAB LA-29, LA-32, LA-36, and LA-46, and particularly preferred are Adeka STAB LA-29, LA-32, and LA-36.

[0051] The antioxidant may include a phenolic compound. Commercially available antioxidants include, for example, Adeka STAB AO-20, AO-30, AO-40, AO-50, AO-50F, AO-60, AO-60G, AO-80, and AO-330 (all manufactured by ADEKA Corporation).

[0052] [Ink preparation method] The ink according to this embodiment can be prepared as follows. Carrier particles dyed with the compounds represented by general formulas (1) and (2) are prepared according to the method described above. The carrier particles dyed with the compounds represented by general formulas (1) and (2) prepared above, along with other colorants, emulsifiers, resins, etc., as needed, are gradually added to a medium selected depending on the application while stirring, and thoroughly blended into the medium. Further, mechanical shear force is applied using a disperser to stably dissolve or finely disperse the carrier particles, thereby obtaining the ink of the present invention.

[0053] [Dispersion machine] The disperser for dispersing each component in the medium is not particularly limited, but media-type dispersers such as a rotary shear homogenizer, a ball mill, a sand mill, and an attritor, and a high-pressure counter-collision type disperser can be used.

[0054] The ink according to this embodiment is also suitable as an ink for oil-based writing instruments, an ink for water-based writing instruments, an ink for inkjet printing, an ink for textile printing, and an ink for paints. Among these, it is preferable to use it as an ink for oil-based writing instruments, an ink for water-based writing instruments, or an inkjet ink. Specific examples of application of the ink according to this embodiment will be described below. Note that for items not specifically described, the same description of the ink according to this embodiment applies as is.

[0055] [Oil-based writing ink] The ink for oil-based writing instruments contains resin particles dyed with the compounds represented by the general formulas (1) and (2) described above and a medium preferably containing an alcohol or glycol ether. In addition, it preferably contains a resin dissolved in the medium. The content of the carrier particles dyed with the compounds represented by the general formulas (1) and (2) is not particularly limited and can be selected appropriately depending on the application.

[0056] [Medium containing alcohol or glycol ether] Examples of alcohols include unsubstituted alkyl monoalcohols such as ethanol, isopropanol, n-butanol, isobutanol, tert-butanol, sec-butanol, 2-methyl-2-butanol, 3-pentanol, octanol, and cyclohexanol; substituted alkyl monoalcohols such as 2-phenoxyethanol and 3-methyl-3-methoxy-1-butanol; alkyl polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, 3-methyl-1,3-butanediol, and 1,3-butanediol; and aromatic alcohols such as benzyl alcohol. Examples of the substituents in substituted alkyl monoalcohols include alkoxy groups and aryloxy groups. Glycol ethers also include monoalcohol monoethers, but these are described as alcohols. Examples of diethers include ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dipropylene glycol, ethylene glycol diethyl ether, diethylene glycol diethyl ether, and diethylene glycol dipropyl ether. The medium may contain, in addition to alcohol or glycol ether, water; or an ester solvent such as 3-methyl-3-methoxybutyl acetate, butyl acetate, or methyl propionate. The amount of the medium used is not particularly limited and may be appropriately selected depending on the type of writing implement, such as a ballpoint pen, a felt-tip pen, or a marking pen.

[0057] [Resin dissolved in the medium] In order to adjust the viscosity of the ink and improve the scratch resistance, it is preferable that the ink contains a resin that exists in a dissolved state in the medium. The resin is determined depending on the purpose and application of the ink, and is not particularly limited. Examples of the resin include butyral resin, ketone resin, polyvinylpyrrolidone resin, styrene resin, styrene-acrylic resin, styrene-maleic acid resin, terpene resin, acrylic resin, polyvinyl acetal resin, polyvinyl butyral resin, terpene phenol resin, rosin-modified maleic resin, rosin phenol resin, maleic acid resin, phenol resin, xylene resin, urea resin, polyamide resin, phenoxy resin, and cellulose-based resin. Of these, butyral resin and ketone resin are preferably used to achieve a writing feel that does not cause smearing. The butyral resin and ketone resin may be commercially available products. Examples of commercially available ketone resins include low-polymerization types under the trade names "S-LEC BL-1," "BL-2," and "BL-10," and high-polymerization types under the trade names "BH-3," "BH-6," "BX-1," "BX-5," and "BH-S" (all manufactured by Sekisui Chemical Co., Ltd.). Commercially available ketone resins include, for example, "Ketone Resin K-90" (manufactured by Arakawa Chemical Industries, Ltd.), and "Hilac 901," "Hilac 110H," and "Hilac 111" (all manufactured by Hitachi Chemical Co., Ltd.). By incorporating these resins into the ink, viscosity adjustment becomes easy, wear on the pen tip can be prevented, and a stable, satisfactory writing feel can be achieved. Furthermore, because film-forming properties can be moderately suppressed, ink solidification can be suppressed even if the pen tip is left exposed for a long period of time, and the "blurring phenomenon" at the start of writing can be suppressed. The content of these resins is appropriately selected and is not particularly limited.

[0058] [Additives] If necessary, additives may be added within limits that do not adversely affect the ink, such as rust inhibitors, surfactants, lubricants, wetting agents, UV absorbers, antifoaming agents, antioxidants, pH adjusters, leveling agents, preservatives, and cellulose nanofibers.

[0059] [Water-based writing ink] The aqueous writing ink preferably contains a resin or cellulose nanofibers dyed with the compounds represented by the general formulas (1) and (2), an aqueous medium, a dispersant (hereinafter also referred to as "first dispersant"), and a water-soluble resin. The content of the carrier particles dyed with the compounds represented by the general formulas (1) and (2) is not particularly limited and can be selected appropriately depending on the application.

[0060] [Aqueous medium] The aqueous medium contains at least water and may further contain a water-soluble organic solvent. The content of water in the ink is preferably 50% by mass or more and 95% by mass or less, based on the total mass of the ink. Furthermore, the water-soluble organic solvent may be any of those commonly used in inks. Examples include alcohols, (poly)alkylene glycols, glycol ethers, nitrogen-containing compounds, and sulfur-containing compounds. The content of the water-soluble organic solvent in the ink is not particularly limited and may be selected as appropriate.

[0061] [First dispersant] When water is used as the medium, a first dispersant may be added as needed to obtain good dispersion stability of the colorant. The first dispersant is not particularly limited, but examples thereof include cationic surfactants, anionic surfactants, and nonionic surfactants. Examples of cationic surfactants include dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, dodecyl pyridinium bromide, and hexadecyl trimethyl ammonium bromide. Examples of anionic surfactants include fatty acid soaps such as sodium stearate and sodium dodecanoate, sodium dodecyl sulfate, sodium dodecylbenzene sulfate, and sodium lauryl sulfate. Examples of nonionic surfactants include dodecyl polyoxyethylene ether, hexadecyl polyoxyethylene ether, nonylphenyl polyoxyethylene ether, lauryl polyoxyethylene ether, sorbitan monooleate polyoxyethylene ether, monodecanoyl sucrose, etc. The content of the first dispersant in the ink is selected appropriately and is not particularly limited.

[0062] [Water-soluble resin] A water-soluble resin may be added to the water-based writing ink, if necessary.

[0063] [Additives] The water-based writing ink can be suitably used in water-based ballpoint pens, gel ink water-based ballpoint pen inks, felt-tip pens, marking pens, etc. Additives such as dispersants, lubricants, pH adjusters, rust inhibitors, preservatives, and antibacterial agents may be added to the water-based writing ink as appropriate, within limits that do not impair the properties for various applications.

[0064] [Inkjet ink] The inkjet ink preferably contains a resin or cellulose nanofibers dyed with the compounds represented by the general formulas (1) and (2), an aqueous medium, and a dispersant (hereinafter also referred to as a "second dispersant"). The content of the carrier particles dyed with the compounds represented by the general formulas (1) and (2) is not particularly limited and can be appropriately selected depending on the application. As the aqueous medium, the same aqueous medium as that used in the ink for the water-based writing implement can be used as is.

[0065] [Second dispersant] Examples of the second dispersant include ionic surfactants, nonionic surfactants, and polymer surfactants. Examples of ionic surfactants include aliphatic monocarboxylates, polyoxyethylene alkyl ether carboxylates; N-acylsarcosinates, N-acylglutamates, dialkyl sulfosuccinates; alkanesulfonates, alpha-olefin sulfonates, linear or branched alkylbenzene sulfonates, naphthalene sulfonate formaldehyde condensates, alkylnaphthalene sulfonates; N-methyl-N-acyltaurates; alkyl sulfates, polyoxyethylene alkyl ether sulfates, fat and oil sulfate esters; alkyl phosphates, polyoxyethylene alkyl ethers anionic surfactants such as alkyl phosphates and polyoxyethylene alkyl phenyl ether phosphates; cationic surfactants such as alkylamine salts, alkyltrimethylammonium chloride, bromide or iodide, dialkyldimethylammonium chloride, bromide or iodide, alkylbenzalkonium chloride, and alkylpyridinium chloride; and amphoteric surfactants such as alkyl betaine, fatty acid amidopropyl betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine, alkyl or dialkyldiethylenetriaminoacetic acid, and alkylamine oxide. Examples of nonionic surfactants include glycerin fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters; polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polyoxypropylene glycols; fatty acid polyethylene glycols, fatty acid polyoxyethylene sorbitan, and fatty acid alkanolamides. Examples of polymer surfactants include anionic polymers such as polyacrylates, styrene-acrylic acid copolymer salts, vinylnaphthalene-acrylic acid copolymer salts, styrene-maleic acid copolymer salts, vinylnaphthalene-maleic acid copolymer salts, and polyphosphoric acid; and nonionic polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyalkylene glycol. Examples of commercially available products include X-200, X-1, X-205, and X-220 (manufactured by Seiko PMC Co., Ltd.), Nopcosperse 6100 (manufactured by San Nopco Ltd.), BYK-190, BYK-187, BYK-191, BYK-194N, BYK-199, and BYKJET-9171 (manufactured by BYK-Chemie Co., Ltd.), Aron A-6114 (manufactured by Toagosei Co., Ltd.), BYK-184, BYK-182, BYK-183, and BYK-185 (manufactured by BYK-Chemie Co., Ltd.), and TEGO Disperse 710 (manufactured by Evonic Tego Chemi). Preferred are BYK-190, BYK-187, BYK-191, BYK-194N, BYK-199, BYKJET-9171, etc., and particularly preferred are BYK-190 and BYKJET-9171. The content of the second dispersant in the inkjet ink is not particularly limited and may be appropriately selected. The content (mass %) of the dispersant in the ink is preferably 0.1% by mass or more and 20% by mass or less, and more preferably 0.5% by mass or more and 15% by mass or less, based on the total mass of the ink. When preparing an inkjet ink, in addition to the components described above, various additives such as a pH adjuster, an anti-rust agent, an antiseptic, an anti-mold agent, an antioxidant, an anti-reducing agent, an evaporation accelerator, a chelating agent, and a water-soluble polymer may be contained as needed.

[0066] [Textile printing ink] When the ink according to this embodiment is used as a textile printing ink, the type of fabric that can be used for textile printing is not particularly limited as long as it can be dyed, and examples thereof include fabrics made of fibers containing polyester, acetate, or triacetate. The fabric may be in the form of a woven fabric, knitted fabric, nonwoven fabric, or the like. Fabrics made of cotton, silk, linen, polyurethane, acrylic, nylon, wool, or rayon fibers, or fabrics made of a combination of two or more of these fibers, can also be used. The thickness of the threads constituting the fabric is preferably in the range of 10 to 100 deniers. The thickness of the fibers constituting the threads is not particularly limited, but is preferably 1 denier or less.

[0067] [Second embodiment] As a result of extensive research to solve the above problems, the present inventors have found that the following ink can provide an ink that has high optical density and excellent color development stability during heat pressing. The ink according to this embodiment is characterized by containing an aqueous medium, a dispersant, a compound represented by general formula (1), and a compound represented by general formula (2). When the compounds represented by the general formulas (1) and (2) are used, inks having high optical density and excellent color stability during heat pressing can be obtained. The mechanism contributing to the color stability is not clearly understood, but the present inventors speculate as follows. This is thought to be due to the fact that the compounds represented by general formulas (1) and (2) are structurally similar in size, and the overlapping occurs due to the π-π stacking interaction of the benzene rings provided by each dialkylamino group, resulting in stabilization. In particular, in general formula (2), when X1 is NH, the hydrogen of NH and the oxygen atom of C=O in the coumarin skeleton form a stable six-membered ring structure through hydrogen bonding, resulting in the greatest effect. The ink according to this embodiment can be used in textile applications that have been expanding in recent years, such as dyeing polyester fibers, sports apparel in which polyester is woven with polyurethane or the like, and high-quality one-piece dresses in which the shape of the fibers is processed. Each component of the ink according to this embodiment will be described in detail below. Note that the compounds represented by general formulas (1) and (2) and the disperser for dispersing each component in the medium can be the same as those described in the first embodiment, and therefore further description will be omitted.

[0068] (dispersant) The dispersant is not particularly limited, but examples thereof include anionic dispersants, nonionic dispersants, and polymer dispersants. The anionic dispersant is not particularly limited, but examples thereof include formalin condensates of aromatic sulfonic acids, formalin condensates of β-naphthalenesulfonic acids, formalin condensates of alkylnaphthalenesulfonic acids, and formalin condensates of creosote oil sulfonic acids. The aromatic sulfonic acid is not particularly limited, but examples thereof include creosote oil sulfonic acid, cresol sulfonic acid, phenol sulfonic acid, alkylnaphthalene sulfonic acids such as β-naphthol sulfonic acid, methylnaphthalene sulfonic acid, and butylnaphthalene sulfonic acid, a mixture of β-naphthalene sulfonic acid and β-naphthol sulfonic acid, a mixture of cresol sulfonic acid and 2-naphthol-6-sulfonic acid, and lignin sulfonic acid. Examples of nonionic dispersants include, but are not limited to, alkylene oxide adducts of phytosterols, alkylene oxide adducts of cholestanols, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkylamines, glycerin fatty acid esters, EO-PO block polymers mainly composed of a copolymer of ethylene oxide (EO) and propylene oxide (PO), and substituted derivatives thereof. The polymer dispersant is not particularly limited, but examples thereof include polyacrylic acid partial alkyl esters, polyalkylene polyamines, polyacrylates, styrene-acrylic acid copolymers, vinylnaphthalene-maleic acid copolymers, and the like. Among the above dispersants, EO-PO block polymers, which are primarily copolymers of ethylene oxide (EO) and propylene oxide (PO), are particularly preferred because they are highly concentrated and can easily produce inks that exhibit excellent color stability during heat pressing. Commercially available EO-PO block polymers may be used, including, for example, those under the trade names "DisperBYK 183," "DisperBYK185," and "DisperBYK190" (all manufactured by BYK-Chemie). The content (mass %) of the dispersant in the ink is preferably 0.1 mass % or more and 20 mass % or less, and more preferably 0.5 mass % or more and 15 mass % or less, based on the total mass of the ink.

[0069] (aqueous medium) The ink is preferably an aqueous ink containing at least water as an aqueous medium, and may further contain a water-soluble organic solvent as an aqueous medium. The water content (% by mass) in the ink is preferably 50% to 95% by mass, and more preferably 55% to 90% by mass, based on the total mass of the ink. Furthermore, the water-soluble organic solvent may be one that is commonly used in inks. Examples include alcohols, (poly)alkylene glycols, glycol ethers, nitrogen-containing compounds, and sulfur-containing compounds. The water-soluble organic solvent content (% by mass) in the ink is preferably 3% to 50% by mass, and more preferably 5% to 40% by mass, based on the total mass of the ink.

[0070] (Other additives) In addition to the components described above, the ink may contain the following additives as needed: polyhydric alcohols such as trimethylolpropane and trimethylolethane; urea and urea derivatives such as ethyleneurea; water-soluble resins, undyed resin particles, surfactants, pH adjusters, rust inhibitors, preservatives, antifungal agents, antioxidants, reduction inhibitors, evaporation accelerators, chelating agents, etc.

[0071] (Ink properties) It is preferable to use ink whose surface tension and viscosity are appropriately controlled in accordance with the characteristics of the inkjet recording head to be used. Specifically, the surface tension of the ink at 25°C is preferably 10 mN / m or more and 60 mN / m or less, more preferably 20 mN / m or more and 60 mN / m or less, and particularly preferably 30 mN / m or more and 50 mN / m or less. The viscosity of the ink at 25° C. is preferably 1.0 mPa·s or more and 10 mPa·s or less, and more preferably 1.0 mPa·s or more and 5 mPa·s or less.

[0072] (Recording method) The ink according to this embodiment can be applied to printers of the sublimation transfer method or direct printing method. Below, a sublimation transfer method will be described as an example of a recording method using the ink according to this embodiment, but the method is not limited to this method. The dye sublimation transfer recording method consists of two steps: (1) printing onto transfer paper, and (2) transferring onto fabric.

[0073] (Printing process onto transfer paper) In the printing process onto the transfer paper, the ink according to the present embodiment is applied to the transfer paper by an inkjet method. The transfer paper is not particularly limited, but it is preferable to use sublimation transfer printing paper. The heads that can be used in the inkjet system include those that use a piezo system or a system that ejects ink by bubbles generated by heating the ink.

[0074] (Transfer process to fabric) The transfer paper to which ink has been applied in the printing process is placed on a fabric, and then the fabric is heated and pressurized using a heat press or other heat press. This transfers the image to the fabric, allowing the image to be recorded on the fabric. The heat pressurization time is preferably 30 seconds or more and 180 seconds or less. The lower limit of the heating temperature in this process is not particularly limited, but is preferably 180°C or more and 220°C or less, more preferably 185°C or more and 205°C or less, and particularly preferably 190°C or more and 200°C or less. The heat pressing pressure in this step is not particularly limited, but is preferably 30 PSI or more and 120 PSI or less, and particularly preferably 40 PSI or more and 90 PSI or less. Instead of a heat press, a sublimation transfer machine (for example, trade name: PSH-4230, manufactured by Europort Co., Ltd.) that transfers at low temperatures under vacuum can also be used. On the other hand, when the recording method using the ink according to this embodiment is a direct printing method, unlike the sublimation transfer method, an image is recorded on the fabric by applying the ink directly to the fabric using an inkjet method without going through a printing process on transfer paper. The image is then fixed to the fabric by heating and pressurizing the ink-applied fabric using a heating and pressurizing device such as a heat press. The heating and pressurizing time is preferably 30 seconds or more and 180 seconds or less. The heating temperature in this process is not particularly limited, but is preferably 180°C or more and 220°C or less, more preferably 185°C or more and 205°C or less, and particularly preferably 190°C or more and 200°C or less.

[0075] (Recording medium) The recording medium is not particularly limited as long as it can be dyed with the ink according to this embodiment, but examples include fabrics made of fibers containing polyester, acetate, or triacetate. The fabric may be in any form, such as woven fabric, knitted fabric, or nonwoven fabric. Fabrics made of cotton, silk, linen, polyurethane, acrylic, nylon, wool, or rayon fibers, or fabrics made of a combination of two or more of these fibers, can also be used. In particular, with conventional sublimation dyes, the color development tends to vary depending on the heat press temperature when dyeing polyester and polyurethane mixed materials, which are often used in sportswear and the like in recent years. However, with the ink according to this embodiment, it is possible to obtain dyed products with excellent color development stability during heat press. The thickness of the yarns constituting the fabric is preferably in the range of 10 denier to 100 denier, and the thickness of the fibers constituting the yarns is not particularly limited, but is preferably 1 denier or less. In addition, objects having a three-dimensional shape such as a sheet, sphere, or rectangular parallelepiped shape, such as a polyester-coated mug, may also be used.

[0076] [Third embodiment] The thermal transfer recording sheet according to this embodiment is characterized in that, in the thermal transfer recording sheet having a substrate and a yellow colorant layer formed on the substrate, the yellow colorant layer contains a compound represented by general formula (1) and a compound represented by general formula (2).

[0077] Conventionally, inks using a single compound represented by general formula (1) as a yellow colorant have been prone to aggregation and have had problems with storage stability, while inks using a single compound represented by general formula (2) as a yellow colorant have had problems with poor lightfastness, although they do not aggregate. As a result of extensive research, the present inventors have found that the same-color mixed color fading can be suppressed by using a combination of a compound represented by general formula (1) and a compound represented by general formula (2), each of which has problems when used alone as a yellow colorant. The mechanism by which the yellow coloring material exhibits the effect of suppressing color mixing and fading caused by mixing compounds of the same color but different structures is not clearly understood, but the present inventors speculate as follows.

[0078] In this embodiment, when compounds having structures represented by general formulas (1) and (2) are used, the ink exhibits good storage stability, and image recording (printed) samples exhibit suppressed color mixing and fading of the same colors. This is because the compounds represented by general formulas (1) and (2) are structurally similar in size, and the dialkylamino groups in each compound provide π-π stacking interactions between the benzene rings, resulting in overlapping of the compounds. It is believed that this overlapping provides stabilization, resulting in the aforementioned effects. In particular, in the compound represented by general formula (2), when X1 is NH, the most stable structure is formed when the hydrogen atom of NH and the oxygen atom of C═O in the coumarin skeleton form a six-membered ring through hydrogen bonding, thereby achieving the greatest effects. The structure of the thermal transfer recording sheet will be described in detail below. Note that the compounds represented by the general formulas (1) and (2) used in the thermal transfer recording sheet are the same as those described in the first embodiment, and therefore further description will be omitted.

[0079] The thermal transfer recording sheet according to this embodiment is a thermal transfer recording sheet having a substrate and a yellow colorant layer formed on the substrate, wherein the yellow colorant layer contains the compound represented by the general formula (1) and the compound represented by the general formula (2). The thermal transfer recording sheet preferably further comprises a magenta coloring material layer and a cyan coloring material layer, and it is preferable that the yellow coloring material layer, the magenta coloring material layer and the cyan coloring material layer are formed in face order on the base material.

[0080] (I-1) Base material The substrate of the thermal transfer recording sheet is preferably one that supports at least the three colorant layers described above. The substrate is not particularly limited, and any substrate that has been conventionally known in the field of thermal transfer recording sheets and has appropriate heat resistance and strength can be used. ·Material of the base material Examples of the substrate include polyethylene terephthalate film, polyethylene naphthalate film, polycarbonate film, polyimide film, polyamide film, aramid film, polystyrene film, 1,4-polycyclohexylene dimethylene terephthalate film, polysulfone film, polypropylene film, polyphenylene sulfide film, polyvinyl alcohol film, cellophane film, cellulose derivative film, polyethylene film, polyvinyl chloride film, nylon film, condenser paper, and paraffin paper. Among these, polyethylene terephthalate film is preferred as the substrate from the viewpoints of mechanical strength, solvent resistance, and economy. ·Base material thickness The thickness of the substrate can be set to 0.5 μm or more and 50 μm or less, and from the viewpoint of transferability, it is preferably set to 3 μm or more and 10 μm or less. Adhesion treatment When a dye-containing composition (ink) is applied to a substrate to form each colorant layer, the coating liquid (dye composition) may lack wettability, adhesiveness, etc. Therefore, it is preferable to subject the substrate to an adhesive treatment on the coated surface as needed. The adhesive treatment is not particularly limited, and any method known in the field of thermal transfer recording sheets can be used. Examples of adhesive treatments include ozone treatment, corona discharge treatment, ultraviolet treatment, plasma treatment, low-temperature plasma treatment, primer treatment, and chemical treatment. Two or more of these treatments may also be combined. The adhesive treatment of the substrate may also be carried out by coating an adhesive layer on the substrate. The adhesive layer is not particularly limited, and any adhesive layer known in the field of thermal transfer recording sheets may be used. Examples of materials used for the adhesive layer include organic materials such as polyester resin, polystyrene resin, polyacrylic ester resin, polyamide resin, polyether resin, polyvinyl acetate resin, polyethylene resin, polypropylene resin, polyvinyl chloride resin, polyvinyl alcohol resin, and polyvinyl butyral resin, and inorganic fine particles such as silica, alumina, magnesium carbonate, magnesium oxide, and titanium oxide.

[0081] (I-2) Heat-resistant slipping layer In order to improve heat resistance and the running property of a thermal head, the thermal transfer recording sheet preferably has a heat-resistant slip layer on the surface of the substrate opposite to the surface on which the coloring material layer is formed. The heat-resistant slip layer is composed of a layer containing a heat-resistant resin. The heat-resistant resin is not particularly limited, and the following resins can be used, for example: polyvinyl butyral resin, polyvinyl acetal resin, polyester resin, polyether resin, polybutadiene resin, vinyl chloride-vinyl acetate copolymer resin, styrene-butadiene copolymer resin, polyurethane acrylate, polyester acrylate, polyimide resin, polycarbonate resin, etc. The heat-resistant slip layer may also contain additives such as a crosslinking agent, a release agent, a lubricant, and a slip-imparting agent. Examples of the lubricant include amino-modified silicone compounds and carboxy-modified silicone compounds. Examples of the slip-imparting agent include heat-resistant fine particles such as silica. The heat-resistant slipping layer can be formed by applying a heat-resistant slipping layer coating liquid, which is prepared by adding the above-mentioned heat-resistant resin and additives to a solvent, dissolving or dispersing the heat-resistant resin and additives, to a substrate, and then drying the liquid. The method for applying the heat-resistant slipping layer coating liquid is not particularly limited, and for example, methods using a bar coater, gravure coater, reverse roll coater, rod coater, or air doctor coater can be used. Among these, the coating method using a gravure coater is preferred, as it is easy to adjust the film thickness. The amount of the heat-resistant slip layer coating solution applied to the substrate is preferably such that the thickness of the heat-resistant slip layer after drying is in the range of 0.1 μm to 5 μm, from the viewpoint of transferability.

[0082] (I-3) Protective layer The thermal transfer recording sheet may have one or two transferable protective layers on a substrate to protect the image surface after image formation, in face order with the colorant layer described below. This protective layer may also be formed on a sheet (substrate) different from the colorant layer. In this case, the thermal transfer recording sheet according to this embodiment includes a sheet having a substrate and a colorant layer (colorant layer sheet) and a sheet having a substrate and a protective layer (protective layer sheet). The protective layer can be formed by applying the composition for each layer to the substrate and drying it. The method for applying the composition for each layer to the substrate is not particularly limited, and examples thereof include methods using a bar coater, gravure coater, reverse roll coater, rod coater, air doctor coater, etc. Among these, the application method using a gravure coater is preferred because it is easy to adjust the film thickness. Furthermore, the drying conditions after coating the composition for each layer are not particularly limited as long as sufficient drying is achieved. For example, drying can be performed at a temperature range of 50°C or higher and 120°C or lower for 1 second or longer and 5 minutes or shorter. The binder resin used in the protective layer is not particularly limited, but suitable examples include acrylic resins such as polystyrene, polymethyl methacrylate, and polyethyl acrylate; styrene resins such as poly-α-methylstyrene; vinyl resins such as polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, and polyvinyl acetal; and synthetic resins such as polyamide resin, epoxy resin, polyurethane resin, petroleum resin, ionomer, ethylene-acrylic acid copolymer, and ethylene-acrylic acid ester copolymer. The thickness of the protective layer is preferably in the range of 0.1 μm to 5 μm. It is also preferable that a release layer having a thickness of 0.1 μm to 1.5 μm be provided under the yellow colorant layer containing the above-mentioned compound to facilitate peeling from the sheet, the release layer containing an acrylic resin such as polymethyl methacrylate or polyethyl acrylate. The release layer is formed on the substrate.

[0083] (I-4) Color material layer In the thermal transfer recording sheet, the yellow colorant layer contains the compounds represented by the above general formulas (1) and (2) as yellow colorants. The above-mentioned two compounds can be used in combination with other yellow colorants as long as the effects of the present invention are not impaired. The other yellow colorants are not particularly limited and can be used as long as they are used in the field of thermal transfer recording sheets and are thermally transferable. From the viewpoint of transferability and storage stability, the melting point of the compounds represented by general formulas (1) and (2) is preferably 40° C. or higher and 200° C. or lower, more preferably 50° C. or higher and 180° C. or lower, and particularly preferably 60° C. or higher and 150° C. or lower. The compounding ratio of the compound represented by general formula (1) to the compound represented by general formula (2) is not particularly limited. Preferably, the compound represented by general formula (2) is present in a range of 5 to 90 parts by mass relative to 10 parts by mass of the compound represented by general formula (1). A range of 10 to 70 parts by mass is more preferable, and a range of 30 to 50 parts by mass is even more preferable. Within this range, a thermal transfer recording sheet can be easily obtained in which the same-color fading of the two different yellow colorants used in the yellow colorant layer is suppressed.

[0084] (I-4-1) Components contained in the colorant layer The components contained in the colorant layer other than the two compounds described above will be described below. (i) Other coloring compounds The magenta colorant used in the magenta colorant layer and the cyan colorant used in the cyan colorant layer are not particularly limited as long as they are used in the field of thermal transfer recording sheets and are thermally transferable. In addition, each colorant compound can be used alone or in combination of two or more types.

[0085] (ii) Binder resin The binder resin that can be used in each colorant layer of the thermal transfer recording sheet is not particularly limited, and various resins can be used. Among them, the following water-soluble resins and organic solvent-soluble resins are preferably used. Water-soluble resins: cellulose resins, polyacrylic resins, starch resins, and epoxy resins. Organic solvent-soluble resins: polyacrylate resin, polymethacrylate resin, polystyrene resin, polycarbonate resin, polyethersulfone resin, polyvinyl butyral resin, ethyl cellulose resin, acetyl cellulose resin, polyester resin, AS resin, and phenoxy resin. These binder resins may be used alone or in combination of two or more types as required.

[0086] (iii) surfactants A surfactant may be added to each colorant layer of the thermal transfer recording sheet to provide sufficient lubricity during heating with a thermal head (during image recording). Examples of surfactants that can be added to each colorant layer include cationic surfactants, anionic surfactants, and nonionic surfactants. Examples of the cationic surfactant include dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, dodecyl pyridinium bromide, and hexadecyl trimethyl ammonium bromide. Examples of the anionic surfactant include fatty acid soaps such as sodium stearate and sodium dodecanoate, sodium dodecyl sulfate, sodium dodecylbenzene sulfate, and sodium lauryl sulfate. Examples of the nonionic surfactant include dodecyl polyoxyethylene ether, hexadecyl polyoxyethylene ether, nonylphenyl polyoxyethylene ether, lauryl polyoxyethylene ether, sorbitan monooleate polyoxyethylene ether, and monodecanoyl sucrose.

[0087] (iv) Wax Wax may be added to each color material layer of the thermal transfer recording sheet to provide sufficient lubricity when the thermal head is not heated. Examples of wax that can be added to each color material layer include, but are not limited to, polyethylene wax, paraffin wax, and fatty acid ester wax.

[0088] (v) Other additives In addition to the above-mentioned additives, ultraviolet absorbers, preservatives, antioxidants, antistatic agents, viscosity adjusters, etc. may be added to each colorant layer of the thermal transfer recording sheet, if necessary. Examples of ultraviolet absorbers include benzophenone-based, benzotriazole-based, cyanoacrylate-based, and triazine-based ones. Commercially available ultraviolet absorbers include, for example, Tinuvin P, Tinuvin 326, Tinuvin 571, and Tinuvin 360 (all manufactured by BASF), and Adeka STAB LA-24, LA-29, LA-31RG, LA-32, LA-36, LA-46, LA-F70, and 1413 (all manufactured by ADEKA Corporation). Preferred are ADK STAB LA-29, LA-32, LA-36, and LA-46, and particularly preferred are ADK STAB LA-29, LA-32, and LA-36. The antioxidant may include a phenolic compound. Commercially available antioxidants include, for example, ADK STAB AO-20, AO-30, AO-40, AO-50, AO-50F, AO-60, AO-60G, AO-80, and AO-330 (all manufactured by ADEKA Corporation).

[0089] (vi) Medium The medium that can be used to prepare each colorant composition for the thermal transfer recording sheet is not particularly limited, but examples include water and organic solvents. The following organic solvents are preferred: alcohols such as methanol, ethanol, isopropanol, and isobutanol; cellosolves such as methyl cellosolve and ethyl cellosolve; aromatic hydrocarbons such as toluene, xylene, and chlorobenzene; esters such as ethyl acetate and butyl acetate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; halogenated hydrocarbons such as methylene chloride, chloroform, and trichloroethylene; ethers such as tetrahydrofuran and dioxane; N,N-dimethylformamide, N-methylpyrrolidone, and the like. These organic solvents may be used alone or in combination of two or more types as needed. Water and organic solvents may also be used in combination.

[0090] (I-4-2) Composition of colorant composition for forming colorant layer Colorant content (amount used) From the viewpoint of sheet storage stability, the amount of each colorant (yellow colorant, magenta colorant, or cyan colorant) used in each colorant composition is preferably 1 part by mass or more and 200 parts by mass or less relative to 100 parts by mass of binder resin. From the viewpoint of colorant dispersion, it is more preferably 50 parts by mass or more and 180 parts by mass or less relative to 100 parts by mass of binder resin. Note that when two or more types of colorant are used in combination, the amount of the colorant used refers to the total amount of parts by mass of each colorant. For example, even when the compounds of the general formulas (1) and (2) above are used in combination with an existing colorant as a yellow colorant, the amount of the colorant used refers to the total number of parts by mass of these colorants. Other ingredient content (amount used) The amounts of other components (additives) used can be set appropriately and are not particularly limited.

[0091] (I-5) Other layers (i) Black colorant layer The thermal transfer recording sheet preferably has three colorant layers including a yellow colorant layer, a magenta colorant layer, and a cyan colorant layer, and may further have a conventionally known black colorant layer as a colorant layer. The black colorant layer can be formed using a black colorant or a composition containing a known yellow colorant, a magenta colorant, and a cyan colorant, and this black colorant layer can also contain the compounds of the general formulas (1) and (2) described above.

[0092] (I-6) Method for producing a thermal transfer recording sheet The method for producing the thermal transfer recording sheet is not particularly limited, but it can be produced, for example, as follows: As an example, the yellow colorant layer will be described. First, the compounds (colorants) represented by general formulas (1) and (2), and, if necessary, a binder resin, a surfactant, and a wax are gradually added to a medium (e.g., an organic solvent) while stirring, and are thoroughly mixed into the medium. In this process, mechanical shear force is applied using a disperser to stably dissolve or disperse these components in the medium into fine particles to prepare a colorant composition (ink).The colorant composition is applied to a base film, which is a substrate, and then dried to produce the desired colorant layer. The dispersing machine used in preparing the colorant composition is not particularly limited, but for example, a media type dispersing machine such as a rotary shear type homogenizer, a ball mill, a sand mill, or an attritor, as well as a high-pressure counter-collision type dispersing machine, etc. can be used. In a thermal transfer recording sheet, each color material layer is formed in face order on a substrate. For example, a yellow color material layer, a magenta color material layer, a cyan color material layer, and a protective layer can be repeatedly formed on a substrate (substrate sheet) along the direction of movement of the substrate. When a thermal transfer sheet having color material layers in this order is used, a yellow image is formed first, followed by a magenta image and then a cyan image, forming a series of images in this order to form a full-color image. Finally, a protective layer is formed, and this series of image formation is repeated. Note that color material layers other than these color material layers can also be added as appropriate; for example, a black color material layer (thermally fusible black layer) can also be added to the substrate. The colorant layer can be formed by applying a colorant composition for each layer to the substrate and drying it. The method for applying the composition for each layer to the substrate is not particularly limited, and examples thereof include methods using a bar coater, gravure coater, reverse roll coater, rod coater, air doctor coater, etc. Among these, the application method using a gravure coater is preferred because it is easy to adjust the film thickness. Furthermore, the drying conditions after applying the colorant composition for each layer are not particularly limited as long as sufficient drying is possible. For example, drying can be performed at a temperature range of 50°C or higher and 120°C or lower for 1 second or longer and 5 minutes or shorter. By thoroughly drying each dye composition, it is easy to prevent background scumming and transfer of dye ink to the back surface during winding, and further it is easy to prevent retransfer of the transferred dye ink to a colorant layer of a different hue during rewinding. The amount of the colorant composition to be applied is preferably such that the thickness of the colorant layer after drying is in the range of 0.1 μm to 5 μm, from the viewpoint of transferability.

[0093] (I-7) How to use the thermal transfer recording sheet A thermal transfer recording sheet is superimposed on a transferee, for example, an image receiving sheet having a colorant-receiving layer on its surface, and the thermal transfer recording sheet is heated using a heating method such as a thermal head, thereby transferring the colorant in the sheet to the image receiving sheet, thereby forming an image. If the thermal transfer recording sheet has the above-mentioned transferable protective layer, the sheet with this protective layer portion is superimposed on the image formed on the image receiving sheet. Then, by heating using a heating method such as a thermal head, the protective layer can be transferred (formed) on the image. The means for heating the thermal transfer recording sheet for image recording is not particularly limited, and not only the usual method using a thermal head but also infrared rays or laser light can be used. Also, the sheet can be used as an electrically conductive dye transfer sheet by using an electrically conductive heat-generating film that generates heat by passing electricity through the base film itself of the substrate. [Example]

[0094] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the text, "parts" are by mass unless otherwise specified.

[0095] <Example of the first embodiment> [Compounds represented by general formulas (1) and (2)] The compounds represented by the general formulas (1) and (2) were synthesized by known methods. The compounds represented by the general formulas (1) and (2) used in this example are listed in Table 1-1. The identification of the obtained compound was carried out as follows: 1 H nuclear magnetic resonance spectroscopy ( 1 H-NMR (trade name: AVANCE-600 NMR spectrometer, manufactured by BRUKER) and MALDI-TOF / MS (trade name: MALDI-TOF / MS ultraFleXtreme, manufactured by BRUKER) were used.

[0096] [Comparative compounds] The following comparative compounds (1) to (5) were used as comparative compounds. [ka]

[0097] [Examples 1-1 to 1-11 and Comparative Examples 1-1 to 1-12] [Preparation of aqueous dispersion of resin particles (A)] A reaction vessel was charged with 1,178 parts of water at 70°C, and 466 parts of monomer (50% styrene, 47% acrylonitrile, 3% methacrylic acid) was mixed, followed by dropwise addition of a polymerization initiator (aqueous solution of 1.9 parts potassium persulfate in 659 parts water) over 60 minutes. The mixture was stirred at 70°C for an additional 30 minutes to obtain an aqueous solution of core resin particles. Next, the temperature of the aqueous solution of core resin particles was raised to 80°C, and 80 parts of a mixed monomer solution (85% styrene, 15% methacrylic acid) and a polymerization initiator (aqueous solution prepared by adding 0.1 parts of potassium persulfate to 133 parts of water) were added dropwise over 10 minutes. The mixture was stirred for a further 120 minutes to synthesize resin particles (A) that would form a shell film (core-shell structure) on the core resin. Next, an appropriate amount of 8 mol / L potassium hydroxide aqueous solution was added to the reaction vessel, and the pH of the liquid was adjusted to 8.5. Furthermore, a total of 29 parts (5% of the resin particles) of powder of the compounds shown in Table 1-1 (the compounding ratio of each compound is as shown in Table 1-1) and 29 parts of ethanol / butanol (8 / 2) were added, and the temperature was raised to 80°C. Thereafter, the mixture was stirred for 2 hours. After the solvent was distilled off under reduced pressure, an appropriate amount of 8 mol / L potassium hydroxide aqueous solution was added to the reaction vessel, and the pH of the liquid was adjusted to 8.5. Water was added so that the resin particle content was 20%, and an aqueous dispersion of resin particles (A) was obtained.

[0098] [Preparation of aqueous dispersion of resin particles (B)] Under a nitrogen atmosphere, 100 parts of monomer (30% styrene, 30% n-butyl acrylate, 40% methacrylic acid) was added to 100 parts of methyl ethyl ketone at 78°C in a reaction vessel and mixed, and a polymerization initiator (a mixed solution of 1 part azobisisobutyronitrile and 20 parts methyl ethyl ketone) was added dropwise over 2 hours. After reacting for another 2 hours, the mixture was cooled to 30°C, and 100 parts of dimethylethanolamine and 100 parts of water were added. The solvent was then removed by vacuum concentration to obtain resin particle solution (B). Meanwhile, under a nitrogen atmosphere, an aqueous solution prepared by adding 1 part sodium bicarbonate and 1 part sodium lauryl sulfate to 178 parts water was heated to 80°C, and 1 part potassium persulfate was added. To this solution, a solution containing 200 parts methyl methacrylate, 140 parts butyl acrylate, 5 parts glycidyl methacrylate, and 5 parts of the compounds shown in Table 1-1 (the compounding ratios of each compound are shown in Table 1-1), 6 parts sodium lauryl sulfate, and 178 parts water was added dropwise over 2 hours. Then, 119 parts of the resin particle solution (B) obtained above was added dropwise over 30 minutes, followed by 35 parts of a 1% aqueous ammonium persulfate solution over 30 minutes. The mixture was allowed to react at 80°C for 2 hours to obtain an aqueous dispersion (B) of resin particles with a solids concentration of 40%.

[0099] [Ink preparation] 50 parts of aqueous dispersion of resin particles (A) or (B), 10 parts of glycerin, 10 parts of triethylene glycol, 1 part of Acetylenol E100 (Kawaken Fine Chemicals), and 35 parts of water were mixed and stirred, and then pressure filtered through a microfilter (Fujifilm) with a pore size of 3.0 μm to prepare each of the inks listed in Table 1-1. The pH of each of the prepared inks was in the range of 8.5 to 9.0.

[0100] [Evaluation of storage stability of aqueous dispersion of resin particles] The aqueous dispersion of resin particles (A) or (B) was sealed and stored at 10° C. for one month, and the presence or absence of aggregates and precipitates after storage was visually confirmed. The results are shown in Table 1-1. The evaluation criteria were as follows: In the evaluation, the storage stability was judged to be good if "almost no aggregates and precipitates of the compound were observed" or "a small amount of aggregates and precipitates of the compound were observed." A: Almost no compound aggregates or precipitates were observed. B: A small amount of compound aggregates and precipitates are observed. C: Significant aggregation and precipitation of the compound is observed.

[0101] [Evaluation of lightfastness of printed matter (image recording matter)] [Creating image samples] Each of the prepared inks was filled into an ink cartridge, and an image was recorded using an inkjet recording apparatus (trade name "PIXUS Pro-10", manufactured by Canon) to obtain a monochrome image sample.

[0102] [Lightfastness evaluation method] Each obtained monochromatic image sample was placed in a xenon test device (product name: AtlasCi4000, manufactured by Suga Test Instruments Co., Ltd.) and irradiance was set at 0.28 W / m at 340 nm. 2 The samples were exposed to the conditions of a temperature of 40°C and a relative humidity of 50% for 24 hours. The reflection density of the monochrome image sample was measured before and after exposure using a reflection densitometer FD-7 (trade name, manufactured by Konica Minolta, Inc.). The initial chromaticity before exposure is a0 * , b0 * , L0 * and the chromaticity after exposure is a * , b * , L * Then, the color difference ΔE was defined and calculated as follows:

[0103]

number

[0104] The evaluation criteria were as follows: In the evaluation, if ΔE after 20 hours was less than 7, it was determined that the light resistance was good. [Evaluation criteria] A: ΔE<5 B: 5≦ΔE<7 C:7≦ΔE

[0105] [Table 1-1]

[0106] As is clear from Table 1-1 above, inks using resin particles dyed with a combination of compounds of general formulas (1) and (2) described in the examples had good storage stability and improved lightfastness of the printed matter. In contrast, comparative inks using resin particles dyed with a compound of general formula (1) or (2) alone or with a comparative compound whose structure is different from that of general formulas (1) and (2) had poor storage stability or lightfastness.

[0107] [Examples 1-12] [Preparation of aqueous dispersion of resin particles (C)] In preparing the aqueous dispersion (B) of resin particles in Example 1-1, a total of 5 parts of the compounds shown in Table 1-1 (the compounding ratio of each compound is as shown in Table 1-1) were added to 10 parts of Adekastab LA-36 (manufactured by ADEKA CORPORATION), and an aqueous dispersion (C) of resin particles with a solids concentration of 40% was obtained in the same manner as in Example 1-1. The storage stability of this aqueous dispersion of resin particles was evaluated as A, and an image sample was prepared and the lightfastness of the printed matter was evaluated. As a result, ΔE after 24 hours was 2.21, indicating an improvement in lightfastness.

[0108] <Preparation of Ink for Oil-Based Writing Instruments> [Examples 1-13] To a mixed solution of 78 parts 1-phenoxy-2-propanol and 22 parts benzyl alcohol, 9 parts of Elec BL-1 (manufactured by Sekisui Chemical Co., Ltd.) as a resin and 1 part of polyvinylpyrrolidone resin K-90 (manufactured by Nippon Shokubai Co., Ltd.) were added and heated to 70°C to dissolve. The mixture was then cooled to room temperature, and 3 parts of Compound 1-2, a compound represented by general formula (1), 12 parts of Compound 2-1, a compound represented by general formula (2), and 3 parts of Plysurf A208N were added as colorants. The mixed solution was dispersed for 3 hours using an Attritor (manufactured by Mitsui Mining Co., Ltd.) to prepare ink (1) for an oil-based writing instrument.

[0109] [Comparative Example 1-13-1] Comparative oil-based ink for writing instruments (1) was prepared in the same manner as in Example 1-13, except that in Example 1-13, the colorant was changed to only 15 parts of Compound 1-2, which is a compound represented by general formula (1).

[0110] [Comparative Example 1-13-2] Comparative oil-based ink for writing instruments (2) was prepared in the same manner as in Example 1-13, except that in Example 1-13, the colorant was changed to only 15 parts of compound 2-1, which is a compound represented by general formula (2).

[0111] <Evaluation of storage stability of ink for oil-based writing instruments> 20 mL of each of the oil-based writing inks obtained above was added to a 50 mL sample bottle, sealed, and left at 60°C for one month. After leaving the bottle, the surface condition was observed at 20x magnification using a phase-contrast microscope (trade name: BX53, manufactured by OLYMPUS Corporation). The observation revealed that when the compounds of general formulas (1) and (2) were used alone, particle aggregation was observed, but when both compounds of general formulas (1) and (2) were used, no aggregation was observed. This confirmed the improvement in storage stability due to the use of both compounds of general formulas (1) and (2).

[0112] <Production of oil-based writing implements and evaluation of lightfastness> Each of the oil-based inks for writing instruments obtained above was filled into a polypropylene ink reservoir tube with an inner diameter of 1.2 mm and a length of 140 mm. A ballpoint pen for evaluation test was prepared using this ink reservoir tube and a phosphor bronze tip (ball diameter 0.7 mm), and a 2 cm square image sample was created using a constant writing pressure. The obtained image sample was placed in a xenon test device (Atlas Weather-O-Meter Ci4000, manufactured by Toyo Seiki Seisakusho Co., Ltd.). After placement, the illuminance was 0.28 W / m at 340 nm. 2 The sample was exposed for 10 hours under conditions of a black panel temperature of 40°C and a relative humidity of 50%. Compared to the case where the compounds represented by general formulas (1) and (2) were used alone, the case where both the compounds represented by general formulas (1) and (2) were used showed a 10% higher residual optical density (OD) rate (%), confirming improved lightfastness. The OD remaining rate (%) was measured using an image sample reflection densitometer (product name "FD-7", manufactured by Konica Minolta), and was the rate of change in yellow OD between the initial time and after 10 hours.

[0113] <Preparation of Water-Based Writing Ink> [Examples 1-14] As colorants, 3 parts of Compound 1-2, a compound represented by general formula (1), 12 parts of Compound 2-1, a compound represented by general formula (2), 0.6 parts of Plysurf A208N (Dai-ichi Kogyo Seiyaku Co., Ltd.), 1 part of methanol, and 0.5 parts of cellulose nanofiber Leocrysta I-2AX (Dai-ichi Kogyo Seiyaku Co., Ltd.) were added, followed by the addition of 99 parts of ion-exchanged water. The mixture was heated to an internal temperature of 80°C and stirred for 2 hours while removing the methanol. After allowing to cool to room temperature, the mixture was dispersed in a homogenizer for 5 minutes to prepare aqueous ink for writing instruments (1).

[0114] [Comparative Example 1-14-1] Comparative oil-based ink for writing instruments (1) was prepared in the same manner as in Example 9, except that in Example 1-14, the colorant was changed to only 15 parts of Compound 1-2, which is a compound represented by general formula (1).

[0115] [Comparative Example 1-14-2] Comparative oil-based ink for writing instruments (2) was prepared in the same manner as in Example 1-14, except that in Example 9, the colorant was changed to only 15 parts of compound 2-1, which is a compound represented by general formula (2).

[0116] <Evaluation of storage stability of ink for water-based writing instruments> 20 mL of each of the obtained aqueous writing inks was added to a 50 mL sample bottle, sealed, and left at 60°C for one month. After leaving the bottle, the surface condition was observed at 20x magnification using a phase-contrast microscope (trade name: BX53, manufactured by OLYMPUS Corporation). The observation revealed that when the compounds of general formulas (1) and (2) were used alone, particle aggregation was observed, but when both compounds of general formulas (1) and (2) were used, no aggregation was observed. This confirmed the improvement in storage stability due to the use of both compounds of general formulas (1) and (2).

[0117] <Production of water-based writing implements and evaluation of lightfastness> The resulting water-based writing ink was filled into a polypropylene ink reservoir tube with an inner diameter of 1.2 mm and a length of 140 mm. A ballpoint pen for evaluation test was prepared using this ink reservoir tube and a phosphor bronze tip (ball diameter 0.7 mm), and a 2 cm square image sample was created using a constant writing pressure. The obtained image sample was placed in a xenon test device (product name: Atlas Weather-O-Meter Ci4000, manufactured by Toyo Seiki Seisakusho Co., Ltd.). After placement, the illuminance was 0.28 W / m at 340 nm. 2 The samples were exposed for 10 hours under conditions of a black panel temperature of 40°C and a relative humidity of 50%. After exposure, the OD residual rate (%) was 8.5% higher when both the compounds of general formulas (1) and (2) were used, compared to when a single compound was used, demonstrating improved lightfastness. The OD residual rate (%) was determined in the same manner as in Example 1-13.

[0118] <Example of the second embodiment> [Compounds represented by general formulas (1) and (2)] The compounds represented by the general formulas (1) and (2) were synthesized by known methods. The compounds represented by the general formulas (1) and (2) used in this example are listed in Table 2-1. The identification of the obtained compound was carried out as follows: 1 H nuclear magnetic resonance spectroscopy ( 1 H-NMR (trade name: AVANCE-600 NMR spectrometer, manufactured by BRUKER) and MALDI-TOF / MS (trade name: MALDI-TOF / MS ultraFleXtreme, manufactured by BRUKER) were used.

[0119] [Comparative compounds] The following comparative compounds were used: [ka]

[0120] (Examples 2-1 to 2-11 and Comparative Examples 2-1 to 2-6) [Ink manufacturing] A total of 2 parts of the compounds shown in Table 2-1 (the compounding ratio of each compound is as shown in Table 2-1), 16 parts of water, 0.8 parts of a dispersant (trade name: DisperBYK190, manufactured by BYK-Chemie), and 80 parts of 0.2 mmφ zirconia beads were placed in a zirconia container and dispersed at 300 rpm for 4 hours in a planetary ball mill. The dispersion was diluted with a 15% aqueous glycerin solution to a solids concentration of 5%, and then filtered through a 0.5 μm filter to obtain an ink.

[0121] [Printing process onto transfer paper] The ink was filled into a modified Canon printer equipped with a piezo-type recording head, and a solid image with 100% duty was printed on dye-sublimation transfer paper (trade name LUCY, manufactured by Dairyoku Co., Ltd.).

[0122] [Transfer process to fabric] The obtained solid image was dried and then transferred to a polyester fabric (Polyester Amunzen, manufactured by Tajimaya Co., Ltd.) using a heat press machine (product name: AIR FUSION, manufactured by STAHLS) at a heat press pressure of 60 SPI and a heat press temperature shown in Table 2-1.

[0123] <Evaluation> (Yellow optical density evaluation) For the polyester fabrics produced in the Examples and Comparative Examples at a heat press temperature of 200°C, the yellow optical density (OD) of the images obtained at each press temperature was measured using a reflection densitometer (product name: FD-7, manufactured by Konica Minolta, Inc.). The measurement results were evaluated for density according to the following evaluation criteria. The evaluation results are shown in the "Y density" column in Table 2-1. In the evaluation, a yellow OD of 1.50 or higher was considered to have a high optical density.

[0124] [Evaluation criteria] A: The yellow OD is 1.70 or higher. B: Yellow OD is 1.50 or more and less than 1.70. C: Yellow OD is less than 1.50.

[0125] (Heat press color stability evaluation) The color stability during heat pressing was calculated using the following formula: The method for measuring the yellow optical density (OD) of the image at each heat pressing temperature was the same as the method for evaluating the yellow optical density described above, except that the heat pressing temperature was different. Color stability (%) when heat pressed at 180℃~210℃= |OD of yellow when heat pressed at 210°C -OD of yellow when heat pressed at 180°C| (absolute value) Color stability (%) when heat pressed at 190℃~200℃= |OD of yellow when heat pressed at 200°C -OD of yellow when heat pressed at 190°C| (absolute value)

[0126] The obtained results were evaluated according to the following criteria: In the evaluation, if the OD difference (absolute value) of yellow was less than 0.50, it was determined that the color development stability was good. [Evaluation criteria] A: The OD difference (absolute value) of yellow is less than 0.30. B: The OD difference (absolute value) of yellow is 0.30 or more and less than 0.50. C: The OD difference (absolute value) of yellow is 0.50 or more.

[0127] [Table 2-1]

[0128] As is clear from Table 2-1 above, by using inks containing the compounds represented by general formulas (1) and (2), it was possible to obtain image recordings with high optical density and high thermal stability.

[0129] [Example 2-12] Two parts of the compound of Example 2-8, one part of ADK STAB LA-36 (ADEKA CORPORATION), 15 parts of water, 0.8 parts of a dispersant (trade name: DisperBYK190, BYK-Chemie), and 80 parts of 0.2 mm diameter zirconia beads were mixed and dispersed in a planetary ball mill at 300 rpm for four hours. The dispersion was diluted with a 15% aqueous glycerin solution to a solids concentration of 5%, and then filtered through a 0.5 μm filter to obtain an ink. The yellow optical density and heat press color stability of this ink were evaluated in the same manner as in Example 2-8. The evaluation results are shown in Table 2-2 below. As shown in Table 2-2, Example 2-12 showed even greater improvement in color stability during heat press than Example 2-8.

[0130] [Table 2-2]

[0131] <Example of the third embodiment> [Compounds represented by general formulas (1) and (2)] The compounds represented by the general formulas (1) and (2) were synthesized by known methods. The compounds represented by the general formulas (1) and (2) used in this example are listed in Table 3-1. The identification of the obtained compound was carried out as follows: 1 H nuclear magnetic resonance spectroscopy ( 1 H-NMR (trade name: AVANCE-600 NMR spectrometer, manufactured by BRUKER) and MALDI-TOF / MS (trade name: MALDI-TOF / MS ultraFleXtreme, manufactured by BRUKER) were used.

[0132] [Comparative compounds] The following comparative compounds (1) to (5) were used as comparative compounds. [ka]

[0133] Examples 3-1 to 3-15 and Comparative Examples 3-1 to 3-13 (I) Thermal transfer recording sheet [Preparation of each colorant composition] <Preparation of Colorant Composition> Five parts of polyvinyl butyral resin (product name "KS-3", manufactured by Sekisui Chemical Co., Ltd.) was gradually added and dissolved in a mixed solution of 45 parts of methyl ethyl ketone and 45 parts of toluene. Five parts of a compound shown in Table 3-1 below was added and dissolved in this solution to obtain a colorant composition.

[0134] [Preparation of thermal transfer recording sheet] A 4.5 μm thick polyethylene terephthalate film (trade name "Lumirror", manufactured by Toray Industries, Inc.) was used as the substrate, and the above colorant composition was applied onto this substrate and then dried to produce a thermal transfer recording sheet having a yellow colorant layer with a thickness of 1 μm after drying. [Creating image samples] Using the thermal transfer recording sheet having the prepared yellow colorant layer, a monochrome image was transferred onto recording paper using a modified machine (trade name "Selphy" manufactured by Canon) (the amount of heat supplied for thermal transfer was reduced to about 80%) to prepare image samples (1) to (15) using colorant compositions (1) to (15) and comparative image samples (1) to (13) using comparative colorant compositions (1) to (13). The color of the image sample was measured using a reflection densitometer (product name "FD-7", manufactured by Konica Minolta, Inc.).

[0135] [evaluation] [Evaluation of storage stability of ink (colorant composition)] The colorant compositions used in Examples 3-1 to 3-15 and Comparative Examples 3-1 to 3-13 were placed in 100 mL mayonnaise bottles, sealed, and stored at 10° C. for one month, and the presence or absence of aggregates after storage was visually confirmed. The results are shown in Table 3-1. The evaluation criteria were as follows: In the evaluation, if "almost no aggregates of the compound were observed" or "a small amount of aggregates of the compound were observed," it was determined that the storage stability was good. [Evaluation criteria] A: Almost no compound aggregates were observed. B: A small amount of compound aggregates is observed. C: Significant aggregation of the compound is observed.

[0136] [Evaluation of lightfastness of printed matter (image recording matter)] Each of the monochromatic image samples obtained in Examples 3-1 to 3-15 and Comparative Examples 3-1 to 3-13 was placed in a xenon test device (trade name "AtlasCi4000", manufactured by Suga Test Instruments Co., Ltd.) and subjected to illuminance of 0.28 W / m at 340 nm. 2 The sample was exposed to the temperature of 40°C and relative humidity of 50% for 20 hours. The reflection density of the printed matter was measured before and after the test. The initial chromaticity is a0 * , b0 * , L0 * and the chromaticity after exposure is a * , b * , L* Then, the color difference ΔE was defined and calculated as follows:

[0137]

number

[0138] The evaluation criteria were as follows: In the evaluation, if ΔE after 20 hours was less than 7, it was determined that the light resistance was good. [Evaluation criteria] A: ΔE<5 B: 5≦ΔE<7 C:7≦ΔE

[0139] [Table 3-1]

[0140] As is clear from Table 3-1 above, the image samples formed using the thermal transfer recording sheets described in the examples showed that the same-color fading of the yellow dye was suppressed in the yellow colorant layer, and a thermal transfer recording sheet could be obtained.

[0141] The present disclosure includes the following configurations. [Configuration 1] The medium and An ink containing a compound represented by the following general formula (1) and carrier particles dyed with a compound represented by the following general formula (2): [ka] [In general formula (1), R1 and R2 each independently represent an alkyl group; R3 represents an alkyl group, an aryl group, or an alkoxy group; R4 represents an alkyl group or an aryl group; [ka] [In general formula (2), R5 and R6 each independently represent an alkyl group; R7 and R8 each independently represent a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, or a halogen atom; X1 represents O, S, or N-R9, where R9 represents a hydrogen atom or an alkyl group. [Configuration 2] The ink according to [Configuration 1], which contains a dispersant. [Configuration 3] The ink according to [Configuration 1] or [Configuration 2], further comprising a resin present in a dissolved state in the medium. [Configuration 4] The ink according to any one of [Configuration 1] to [Configuration 3], which is for use with an oil-based writing instrument, a water-based writing instrument, or an inkjet printer. [Configuration 5] an aqueous medium; a dispersant; and A compound represented by the following general formula (1), A compound represented by the following general formula (2), An ink characterized in that it comprises: [ka] [In general formula (1), R1 and R2 each independently represent an alkyl group; R3 represents an alkyl group, an aryl group, or an alkoxy group; R4 represents an alkyl group or an aryl group; [ka] [In general formula (2), R5 and R6 each independently represent an alkyl group; R7 and R8 each independently represent a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, or a halogen atom; X1 represents O, S, or N-R9, where R9 represents a hydrogen atom or an alkyl group. [Configuration 6] The ink according to [Configuration 5], which is water-based. [Configuration 7] The ink according to [Configuration 5] or [Configuration 6], which is for inkjet use. [Configuration 8] The ink according to any one of [Structure 1] to [Structure 7], wherein in the general formula (1), R1 and R2 are each independently an alkyl group having 1 to 4 carbon atoms, and R3 is an alkoxy group having 1 to 4 carbon atoms. [Configuration 9] The ink according to any one of [Configuration 1] to [Configuration 8], wherein in the general formula (2), R5 and R6 are each independently an alkyl group having 1 to 4 carbon atoms, and X1 is O, NH, or N—CH3. [Configuration 10] The ink according to any one of [Configuration 1] to [Configuration 9], wherein the mass ratio of the compound represented by general formula (1) to the compound represented by general formula (2) is 5 parts by mass or more and 90 parts by mass or less of the compound represented by general formula (2) per 10 parts by mass of the compound represented by general formula (1). [Configuration 11] The ink according to any one of [Configuration 1] to [Configuration 9], wherein the mass ratio of the compound represented by general formula (1) to the compound represented by general formula (2) is 10 parts by mass or more and 70 parts by mass or less of the compound represented by general formula (2) per 10 parts by mass of the compound represented by general formula (1). [Configuration 12] The ink according to any one of [Configuration 1] to [Configuration 9], wherein the mass ratio of the compound represented by general formula (1) to the compound represented by general formula (2) is 30 parts by mass or more and 50 parts by mass or less of the compound represented by general formula (2) per 10 parts by mass of the compound represented by general formula (1). [Configuration 13] A thermal transfer recording sheet having a substrate and a yellow colorant layer formed on the substrate, A thermal transfer recording sheet, wherein the yellow colorant layer contains a compound represented by the following general formula (1) and a compound represented by the following general formula (2): [ka] [In general formula (1), R1 and R2 each independently represent an alkyl group; R3 represents an alkyl group, an aryl group, or an alkoxy group. R4 represents an alkyl group or an aryl group; [ka] [In general formula (2), R5 and R6 each independently represent an alkyl group; R7 and R8 each independently represent a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, or a halogen atom; X1 represents O, S, or N-R9, where R9 represents a hydrogen atom or an alkyl group. [Configuration 14] The thermal transfer recording sheet according to [Structure 13] further comprises a magenta colorant layer and a cyan colorant layer, and the yellow colorant layer, the magenta colorant layer, and the cyan colorant layer are formed in face order on the base material. [Configuration 15] A thermal transfer recording sheet according to [Structure 13] or [Structure 14], wherein in the general formula (1), R1 and R2 are each independently an alkyl group having 1 to 4 carbon atoms, and R3 is an alkoxy group having 1 to 4 carbon atoms. [Configuration 16] A thermal transfer recording sheet according to any one of [Structure 13] to [Structure 15], wherein in the general formula (2), R5 and R6 are each independently an alkyl group having 1 to 4 carbon atoms, and X1 is O, NH, or N-CH3. [Configuration 17] A thermal transfer recording sheet according to any one of [Configuration 13] to [Configuration 16], wherein the mass ratio of the compound represented by the general formula (1) to the compound represented by the general formula (2) is 5 parts by mass or more and 90 parts by mass or less of the compound represented by the general formula (2) per 10 parts by mass of the compound represented by the general formula (1). [Configuration 18] The thermal transfer recording sheet according to any one of [Configuration 13] to [Configuration 16], wherein the mass ratio of the compound represented by the general formula (1) to the compound represented by the general formula (2) is 10 parts by mass or more and 70 parts by mass or less of the compound represented by the general formula (2) relative to 10 parts by mass of the compound represented by the general formula (1). [Configuration 19] The thermal transfer recording sheet according to any one of [Configuration 13] to [Configuration 16], wherein the mass ratio of the compound represented by the general formula (1) to the compound represented by the general formula (2) is 30 parts by mass or more and 50 parts by mass or less of the compound represented by the general formula (2) per 10 parts by mass of the compound represented by the general formula (1).

Claims

1. The medium and An ink containing a compound represented by the following general formula (1) and carrier particles dyed with a compound represented by the following general formula (2): 【Chemical 1】 [In general formula (1), R １ and R ２ each independently represents an alkyl group, R ３ represents an alkyl group, an aryl group, or an alkoxy group; R ４ represents an alkyl group or an aryl group. 【Chemistry 2】 [In general formula (2), R ５ and R ６ each independently represents an alkyl group, R ７ and R ８ each independently represents a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, or a halogen atom; X １ is O, S, or N-R ９ represents R ９ represents a hydrogen atom or an alkyl group.

2. 10. The ink of claim 1, further comprising a dispersant.

3. 10. The ink of claim 1, further comprising a resin present in a dissolved state in said medium.

4. 2. The ink according to claim 1, which is for use in an oil-based writing instrument, a water-based writing instrument, or an ink-jet writing instrument.

5. an aqueous medium; a dispersant; and A compound represented by the following general formula (1), A compound represented by the following general formula (2), An ink characterized in that it comprises: 【Chemistry 3】 [In general formula (1), R １ and R ２ each independently represents an alkyl group, R ３ represents an alkyl group, an aryl group, or an alkoxy group; R ４ represents an alkyl group or an aryl group. 【Chemistry 4】 [In general formula (2), R ５ and R ６ each independently represents an alkyl group, R ７ and R ８ each independently represents a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, or a halogen atom; X １ is O, S, or N-R ９ represents R ９ represents a hydrogen atom or an alkyl group.

6. 6. The ink of claim 5 which is water-based.

7. 6. The ink according to claim 5, which is for ink-jet printing.

8. In the general formula (1), R １ and R ２ are each independently an alkyl group having 1 to 4 carbon atoms, and R ３ The ink according to any one of claims 1 to 7, wherein is an alkoxy group having 1 to 4 carbon atoms.

9. In the general formula (2), R ５ and R ６ are each independently an alkyl group having 1 to 4 carbon atoms, and X １ is O, N—H, or N—CH ３ The ink according to any one of claims 1 to 7, wherein

10. The ink according to any one of claims 1 to 7, wherein a mass ratio of the compound represented by general formula (1) to the compound represented by general formula (2) is 5 parts by mass or more and 90 parts by mass or less of the compound represented by general formula (2) relative to 10 parts by mass of the compound represented by general formula (1).

11. The ink according to any one of claims 1 to 7, wherein a mass ratio of the compound represented by general formula (1) to the compound represented by general formula (2) is 10 parts by mass or more and 70 parts by mass or less of the compound represented by general formula (2) relative to 10 parts by mass of the compound represented by general formula (1).

12. The ink according to any one of claims 1 to 7, wherein a mass ratio of the compound represented by the general formula (1) to the compound represented by the general formula (2) is 30 parts by mass or more and 50 parts by mass or less of the compound represented by the general formula (2) relative to 10 parts by mass of the compound represented by the general formula (1).

13. A thermal transfer recording sheet having a substrate and a yellow colorant layer formed on the substrate, A thermal transfer recording sheet, wherein the yellow colorant layer contains a compound represented by the following general formula (1) and a compound represented by the following general formula (2): 【Chemistry 5】 [In general formula (1), R １ and R ２ each independently represents an alkyl group, R ３ represents an alkyl group, an aryl group, or an alkoxy group. R ４ represents an alkyl group or an aryl group. 【Chemistry 6】 [In general formula (2), R ５ and R ６ each independently represents an alkyl group, R ７ and R ８ each independently represents a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, or a halogen atom, X １ is O, S, or N-R ９ represents R ９ represents a hydrogen atom or an alkyl group.

14. 14. The thermal transfer recording sheet according to claim 13, further comprising a magenta coloring material layer and a cyan coloring material layer, wherein the yellow coloring material layer, the magenta coloring material layer, and the cyan coloring material layer are formed in face order on the substrate.

15. In the general formula (1), R １ and R ２ are each independently an alkyl group having 1 to 4 carbon atoms, and R ３ 14. The thermal transfer recording sheet according to claim 13, wherein is an alkoxy group having 1 to 4 carbon atoms.

16. In the general formula (2), R ５ and R ６ are each independently an alkyl group having 1 to 4 carbon atoms, and X １ is O, N—H, or N—CH ３ 14. The thermal transfer recording sheet according to claim 13, wherein

17. 14. The thermal transfer recording sheet according to claim 13, wherein the mass ratio of the compound represented by the general formula (1) to the compound represented by the general formula (2) is 5 parts by mass or more and 90 parts by mass or less for 10 parts by mass of the compound represented by the general formula (1).

18. 14. The thermal transfer recording sheet according to claim 13, wherein the mass ratio of the compound represented by the general formula (1) to the compound represented by the general formula (2) is 10 parts by mass or more and 70 parts by mass or less of the compound represented by the general formula (2) relative to 10 parts by mass of the compound represented by the general formula (1).

19. 14. The thermal transfer recording sheet according to claim 13, wherein the mass ratio of the compound represented by the general formula (1) to the compound represented by the general formula (2) is 30 parts by mass or more and 50 parts by mass or less for 10 parts by mass of the compound represented by the general formula (1).

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