Ink set for thermal transfer sheet and method for producing thermal transfer sheet

Abstract

To provide a thermal transfer sheet excellent in image reproducibility.SOLUTION: Provided is an ink set for a thermal transfer sheet including: a color ink having a color other than white; at least one selected from the group consisting of a white ink and a transparent ink; and an ink aggregation liquid.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to an ink set for a thermal transfer sheet and a method for producing a thermal transfer sheet. [Background technology]

[0002] DTF printing has recently gained attention as a method for printing text, pictures, designs, and other images onto woven, knitted, nonwoven, and other fabrics. DTF stands for Direct to Film, and specifically refers to a printing method using a thermal transfer sheet. Thermal transfer sheets for DTF printing are generally produced by first printing the desired color image on a substrate sheet, then printing white ink over the image, applying hot melt powder to the white ink before it dries, and then heating to melt the hot melt powder. Printing onto fabric is achieved by placing the hot melt powder layer of the thermal transfer sheet on the fabric side and transferring the image using a heat press. Compared to direct printing on fabric, DTF printing offers advantages such as higher image clarity and a wider selection of printable fabrics and colors.

[0003] As a prior art related to DTF printing, Patent Document 1 describes an example in which the objective of the invention is to provide a transfer printing method that can print without missing images. The example uses a resin powder of a grade that is heat-meltable and adheres to the entire surface of the ink without any gaps, specifically a resin powder of a grade in which the proportion of particles of 75 μm or less is 87% or more and which does not contain powder with a particle size exceeding 150 μm, and a transfer sheet that is impermeable to ink and is sufficient to maintain the adhesion of the resin powder. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-171840 Summary of the Invention [Problem to be solved by the invention]

[0005] As described in Patent Document 1, one of the technical challenges facing DTF printing is ensuring the adhesion of hot melt powder. The method described in Patent Document 1 uses a highly impermeable substrate sheet to ensure the adhesion of hot melt powder, but when a typical thermal transfer sheet is produced using this method, there is another problem in that the color inks that form the image are likely to mix with the white ink that is applied on top of them, which can easily reduce image reproducibility.

[0006] The present disclosure addresses the problem of providing a thermal transfer sheet with excellent image reproducibility, and provides an ink set for a thermal transfer sheet to achieve this. [Means for solving the problem]

[0007] One embodiment of the present disclosure relates to an ink set for a thermal transfer sheet, including a non-white ink, at least one of a white ink and a clear ink, and an ink aggregating liquid.

[0008] Another embodiment of the present disclosure relates to a method for producing a thermal transfer sheet, including a step (Step A) of applying at least one of a non-white ink, an ink condensate, a white ink, and a transparent ink onto a substrate sheet in this order by a wet-on-wet method.

[0009] Another embodiment of the present disclosure relates to a method for producing a thermal transfer sheet, including a step (step B) of sequentially applying an ink condensate, a non-white ink, a white ink, and / or a transparent ink onto a substrate sheet by a wet-on-wet method. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a thermal transfer sheet with excellent image reproducibility, an ink set for a thermal transfer sheet for obtaining the same, and a method for producing a thermal transfer sheet. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described in detail, but the present disclosure is not limited to these embodiments and may be modified and changed in various ways.

[0012] An ink set for a thermal transfer sheet (hereinafter sometimes referred to as an "ink set") in one embodiment includes a non-white ink, at least one of a white ink and a clear ink (hereinafter sometimes referred to as a "white / clear ink"), and an ink condensate. In one embodiment, the use of an ink condensate in the production of a thermal transfer sheet stabilizes the film thickness of the white / clear ink, resulting in a thermal transfer sheet with excellent image reproducibility and suppressing image defects. Furthermore, since dripping is less likely to occur even when a relatively large amount of white / clear ink is applied, it is possible to design the application of a larger amount of white / clear ink, thereby improving transferability to the print medium and suppressing image defects. Furthermore, the effect of suppressing color mixing between the non-white ink and the white / clear ink allows for a transfer sheet with excellent image reproducibility. In particular, when inkjet printing is used for image printing, inkjet inks often contain low-volatility solvents to prevent nozzle clogging when the printer is not in use. In this case, inks containing low-volatility solvents tend to mix easily on the substrate sheet, easily causing color mixing. In the ink set of one embodiment, even when the non-white ink, white ink, and clear ink are inkjet inks, the action of the ink aggregating liquid makes it possible to obtain a thermal transfer sheet with excellent image reproducibility.

[0013] In another embodiment, by using an ink aggregating solution in the production of a thermal transfer sheet, even when a powder such as a hot-melt powder is used as an adhesive agent during transfer, the adhesion of the hot-melt powder of the white / clear ink can be ensured, and color mixing between the non-white ink and the white / clear ink can be prevented, resulting in a thermal transfer sheet with excellent image reproducibility. When a powder such as a hot-melt powder is used as an adhesive agent during transfer, the use of an ink aggregating solution in the production of a thermal transfer sheet can suppress the fluidity of the white / clear ink before the powder is applied. This allows for a thermal transfer sheet with excellent uniformity of a white solid image, particularly when using white ink. If the powder is applied when the white / clear ink is highly fluid, the powder will absorb too much of the white / clear ink. As a result, unevenness occurs in the white solid image, particularly when using white ink, reducing the uniformity of the white solid image.

[0014] An ink set according to one embodiment will now be described. The ink set according to one embodiment includes a non-white ink. The non-white ink refers to ink of a color other than white, such as cyan, magenta, yellow, or black. There are no particular limitations on the type of non-white ink, and a wide variety of inks can be used. As an example, the non-white ink may be a water-based inkjet ink. Furthermore, one type of non-white ink may be used alone, or two or more types may be used in combination.

[0015] The non-white ink contains a non-white colorant. One type of colorant may be used alone, or two or more types may be used in combination. Examples of colorants include various non-white pigments, such as organic pigments such as azo pigments, phthalocyanine pigments, polycyclic pigments, and dye lake pigments, and inorganic pigments such as carbon black and metal oxides. Examples of azo pigments include soluble azo lake pigments, insoluble azo pigments, and condensed azo pigments. Examples of phthalocyanine pigments include metal phthalocyanine pigments and metal-free phthalocyanine pigments. Examples of polycyclic pigments include quinacridone pigments, perylene pigments, perinone pigments, isoindoline pigments, isoindolinone pigments, dioxazine pigments, thioindigo pigments, anthraquinone pigments, quinophthalone pigments, metal complex pigments, and diketopyrrolopyrrole (DPP). Examples of carbon black include furnace carbon black, lamp black, acetylene black, and channel black.

[0016] When the non-white ink is an inkjet ink, the average particle size of the pigment particles may be 300 nm or less, 200 nm or less, or 150 nm or less, as the volume-based average value in the particle size distribution measured by dynamic light scattering, from the viewpoints of ejection stability and storage stability of the ink.

[0017] The non-white pigment may be a self-dispersing pigment or a microencapsulated pigment in which the pigment is coated with a resin. In addition, in the non-white ink, a pigment dispersion in which the pigment is dispersed in advance with a pigment dispersant may be used, or the pigment may be dispersed with a pigment dispersant described below.

[0018] Self-dispersing pigments are pigments in which hydrophilic functional groups have been introduced onto their surfaces by chemical or physical treatment. The hydrophilic functional groups introduced into self-dispersing pigments are preferably ionic. By charging the pigment surface anionic or cationic, electrostatic repulsion can be utilized to stably disperse pigment particles in water. Examples of anionic functional groups include carboxyl groups, sulfo groups, sulfino groups, sulfate ester groups, phosphate groups, phosphate ester groups, phosphite groups, and phosphite ester groups. Examples of cationic functional groups include quaternary ammonium groups and quaternary phosphonium groups. These hydrophilic functional groups may be bonded directly to the pigment surface or via other atomic groups. Examples of other atomic groups include alkylene groups, phenylene groups, and naphthylene groups. Examples of pigment surface treatment methods include diazotization, sulfonation, hypochlorite treatment, humic acid treatment, and vacuum plasma treatment.

[0019] Preferred examples of self-dispersing pigments that can be used include the "CAB-O-JET" series manufactured by Cabot Corporation ("CAB-O-JET200," "CAB-O-JET300," "CAB-O-JET250C," "CAB-O-JET260M," "CAB-O-JET270Y," "CAB-O-JET450C," and "CAB-O-JET465M," etc.), and the "BONJET" series manufactured by Orient Chemical Industries Co., Ltd. ("BONJET BLACK CW-1," "BONJET BLACK CW-2," "BONJET BLACK CW-3," "BONJET BLACK CW-4," etc.).

[0020] Examples of commercially available pigment dispersions in which a pigment is pre-dispersed with a pigment dispersant include the HOSTAJET series manufactured by Clariant and the FUJI SP series manufactured by Fuji Pigment Co., Ltd.

[0021] The content of the non-white pigment in the non-white ink is not particularly limited, and can be in the same range as that of a general non-white ink, for example, in the range of 1 to 10% by mass of the total amount of the non-white ink.

[0022] Various pigment dispersants may be used to stably disperse the non-white pigment in the non-white ink. One type of pigment dispersant may be used alone, or two or more types may be used in combination. Examples of pigment dispersants include polymer dispersants and surfactant-type dispersants.

[0023] Examples of commercially available polymer dispersants include the TEGO Disperse series manufactured by EVONIK (such as "TEGO Disperse 740W," "TEGO Disperse 750W," "TEGO Disperse 755W," "TEGO Disperse 757W," and "TEGO Disperse 760W") and the Solsperse series manufactured by Lubrizol Japan Co., Ltd. (such as "Solsperse 20000," "Solsperse 27000," "Solsperse 41000," "Solsperse 41090," "Solsperse 43000," "Solsperse 44000," and "Solsperse 46000"). etc.), the JONCRYL series manufactured by BASF Japan Ltd. ("JONCRYL 57", "JONCRYL 60", "JONCRYL 62", "JONCRYL 63", "JONCRYL 71", "JONCRYL 501", etc.), manufactured by BYK Japan Co., Ltd., "DISPERBYK-102", "DISPERBYK-185", "DISPERBYK-190", "DISPERBYK-193", "DISPERBYK-199", etc., manufactured by BYK-Chemie Japan Co., Ltd., and "Polyvinylpyrrolidone K-30" and "Polyvinylpyrrolidone K-90" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. (all trade names).

[0024] Examples of surfactant-type dispersants include commercially available anionic surfactants such as the Demol series manufactured by Kao Corporation ("Demol P," "Demol EP," "Demol N," "Demol RN," "Demol NL," "Demol RNL," "Demol T-45," etc.), and nonionic surfactants such as the Emulgen series manufactured by Kao Corporation ("Emulgen A-60," "Emulgen A-90," "Emulgen A-500," "Emulgen B-40," "Emulgen L-40," "Emulgen 420," etc.) (all trade names).

[0025] When a pigment dispersant is used, the amount of pigment dispersant blended in the non-white ink is adjusted appropriately depending on the types of non-white pigment and pigment dispersant, but may be, for example, in the range of 0.5 to 150 parts by mass per 100 parts by mass of the non-white pigment.

[0026] The non-white ink preferably contains a resin. One type of resin may be used alone, or two or more types may be used in combination. The content of the resin in the non-white ink is adjusted appropriately depending on the desired viscosity, etc., but may be, for example, in the range of 3 to 30 mass %.

[0027] The resin type is preferably one that can form a transparent coating film, as this results in a non-white ink with better color development. Specific examples of the resin include conjugated diene resins such as styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, and vinyl chloride-vinyl acetate copolymer; acrylic resins such as polymers of acrylic acid esters and methacrylic acid esters, or copolymers of these with styrene or the like; vinyl resins such as ethylene-vinyl acetate copolymer; functional group-modified resins obtained by modifying these various resins with a monomer having a functional group such as a carboxy group; melamine resins; urea resins; polyurethane resins; polyester resins; polyolefin resins; silicone resins; polyvinyl butyral resins; and alkyd resins.

[0028] When the non-white ink is aqueous, the resin is preferably resin particles that can be dispersed in an aqueous solvent such as water or a water-soluble organic solvent. In particular, a resin that does not dissolve in water and can form an oil-in-water (O / W) emulsion is preferred. The resin may be blended as an aqueous dispersion of resin particles when producing the non-white ink.

[0029] When the resin is a resin particle dispersible in an aqueous solvent, the functional groups of the resin may be present on the surface of the resin particle, such as a self-emulsifying resin, or the resin particle may be surface-treated by attaching a dispersant to the surface. The resin particles may be anionic, cationic, nonionic, or amphoteric, but anionic or nonionic resins are preferred, and anionic resins are more preferred.

[0030] The anionic resin particles may be those in which anionic functional groups of the resin are present on the surface of the resin particles, as in the case of self-emulsifying resins, or those that have been surface-treated by attaching an anionic dispersant to the surface of the resin particles. Representative examples of the anionic functional groups include carboxyl groups, sulfo groups, sulfino groups, sulfate ester groups, phosphate groups, phosphate ester groups, phosphite groups, and phosphite ester groups. Examples of the anionic dispersant include anionic surfactants.

[0031] Commercially available aqueous dispersions of resin particles include the polyurethane dispersion "DAOTAN" series manufactured by Daicel Allnex Corporation (e.g., "DAOTAN TW6450," "DAOTAN TW6460," "DAOTAN TW6490," "DAOTAN VTW1262," etc.), and the "Implanil" series manufactured by Sumika Covestro Urethane Co., Ltd. (e.g., "Implanil DLP," "Implanil DLP-R," "Implanil DLV," "Implanil DLI," "Implanil 1016," "Implanil 1116," "Implanil DLS," "Implanil DL1537," "Implanil DL1554," "Implanil DL1380," "Implanil LP CGL 105," "Implanil DLN-SD," "Implanil LP DSB"). 1069, Impranil DLN-W50, etc.), Daiichi Kogyo Seiyaku Co., Ltd.'s "Superflex" series (e.g., "Superflex 420", "Superflex 150HS", "Superflex 460", "Superflex 470", "Superflex E2000", "Superflex 740", "Superflex 500M", "Superflex 300", etc.), Unitika Ltd.'s "Elitel" series (e.g., "Elitel KT9204", "Elitel KT8803", etc.), DSM's "NeoRez" series (e.g., "NeoRez R-966", "NeoRez R-4000, etc.), the "AQUACER" series manufactured by BYK (for example, "AQUACER507"), and the "Mowinyl" series manufactured by Japan Coating Resins Co., Ltd. (for example, "Mowinyl 6750", "Mowinyl 6751D", "Mowinyl 6763", "Mowinyl 6770", "Mowinyl 6775", etc.).

[0032] The non-white ink may contain other components in addition to the non-white pigment and resin, such as organic solvents, water, surfactants, pH adjusters, dispersants, fixing agents, and preservatives.

[0033] The type of organic solvent is not particularly limited, and a wide variety of organic solvents commonly used in the ink field can be used. The content of the organic solvent in the non-white ink may be, for example, 1% by mass or more, 5% by mass or more, or 10% by mass or more. It may also be 60% by mass or less, 50% by mass or less, or 40% by mass or less. The content of the organic solvent in the non-white ink may be, for example, in the range of 1 to 60% by mass.

[0034] Among organic solvents, it is preferable to include an organic solvent with a boiling point of 260°C or higher (hereinafter, this may be referred to as a "high-boiling organic solvent"). When at least one of the inks included in the ink set includes a high-boiling organic solvent, the adhesion of the powder is improved. Furthermore, when the non-white ink is an inkjet ink, including a high-boiling organic solvent makes it even less likely for the nozzles to clog when the printer is not in use. In one embodiment of the ink set for thermal transfer sheets, even when the non-white ink includes a high-boiling organic solvent, the fluidity of the white / clear ink is reduced by the action of the ink aggregating liquid before the powder is applied. This prevents the powder from absorbing too much ink, thereby preventing a decrease in the uniformity of the white solid image, and allows for a thermal transfer sheet with excellent image reproducibility.

[0035] The boiling point of the high-boiling organic solvent may be 270° C. or higher, or 280° C. or higher, or 350° C. or lower, or 320° C. or lower, or 300° C. or lower. The boiling point of the high-boiling organic solvent may be, for example, in the range of 260 to 350° C.

[0036] The content of the high-boiling organic solvent in the non-white ink may be, for example, 1% by mass or more, 3% by mass or more, or 5% by mass or more. It may also be 40% by mass or less, 30% by mass or less, or 20% by mass or less. The content of the high-boiling organic solvent in the non-white ink may be, for example, in the range of 1 to 40% by mass.

[0037] The proportion of high-boiling-point organic solvents in all organic solvents in the non-white ink may be, for example, 5% by mass or more, 10% by mass or more, or 20% by mass or more. It may also be 60% by mass or less, 50% by mass or less, or 40% by mass or less. The proportion of high-boiling-point organic solvents in all organic solvents in the non-white ink may be, for example, in the range of 5 to 60% by mass.

[0038] In one embodiment, when the non-white ink is aqueous, a water-soluble organic solvent can be preferably used as the organic solvent. The water-soluble organic solvent can be any solvent commonly used in the field of aqueous inks, and is not particularly limited. A single water-soluble organic solvent can be used alone, or two or more water-soluble organic solvents can be used in combination. Among these, water-soluble organic solvents that are liquid at room temperature and can be uniformly mixed with an equal volume of water at 20°C under 1 atmosphere are preferred. Examples of such water-soluble organic solvents include lower alcohol compounds such as methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, and 2-methyl-2-propanol; glycol compounds such as ethylene glycol, diethylene glycol, trimethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol; glycerin compounds such as glycerin, diglycerin, and triglycerin; acetin compounds such as monoacetin, diacetin, and triacetin; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, and ethylene glycol monobutyl ether. glycol ether compounds such as tetraethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol dimethyl ether, and tetraethylene glycol diethyl ether; triethanolamine, 1-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, β-thiodiglycol, and sulfolane.

[0039] Among these water-soluble organic solvents, examples of the water-soluble high-boiling organic solvents that fall under the above-mentioned high-boiling organic solvents include, for example, glycol solvents such as triethylene glycol, tetraethylene glycol, and tripropylene glycol; and glycerin-based solvents such as glycerin, diglycerin, and triglycerin.

[0040] When the non-white ink is aqueous, it preferably contains a water-soluble organic solvent. The content of the water-soluble organic solvent in the non-white ink may be, for example, 1% by mass or more, 5% by mass or more, or 10% by mass or more. It may also be 60% by mass or less, 50% by mass or less, or 40% by mass or less. The content of the water-soluble organic solvent in the non-white ink may be, for example, in the range of 1 to 60% by mass.

[0041] The content of the water-soluble high-boiling organic solvent in the non-white ink may be, for example, 1% by mass or more, 3% by mass or more, or 5% by mass or more. It may also be 40% by mass or less, 30% by mass or less, or 20% by mass or less. The content of the water-soluble high-boiling organic solvent in the non-white ink may be, for example, in the range of 1 to 40% by mass.

[0042] The proportion of the water-soluble high-boiling point organic solvent in the total water-soluble organic solvents in the non-white ink may be, for example, 5% by mass or more, 10% by mass or more, or 20% by mass or more. It may also be 100% by mass, 60% by mass or less, 50% by mass or less, or 40% by mass or less. The proportion of the water-soluble high-boiling point organic solvent in the total water-soluble organic solvents in the non-white ink may be, for example, in the range of 5 to 100% by mass.

[0043] The non-white ink may be aqueous. When the ink is aqueous, the water contained in the non-white ink may be, for example, ion-exchanged water, distilled water, or ultrapure water. The proportion of water relative to the total amount of the non-white ink is adjusted appropriately depending on the desired viscosity, etc., but may be, for example, in the range of 30 to 90% by mass.

[0044] Examples of surfactants include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. The surfactant may be either a low molecular weight surfactant or a high molecular weight surfactant. One type of surfactant may be used alone, or two or more types may be used in combination. Of these, nonionic surfactants are preferred. The HLB value of the surfactant is preferably 5 to 20, and more preferably 10 to 18.

[0045] Examples of nonionic surfactants include ester surfactants such as glycerin fatty acid esters and fatty acid sorbitan esters; ether surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers and polyoxypropylene alkyl ethers; ether ester surfactants such as polyoxyethylene sorbitan fatty acid esters; acetylene surfactants; silicone surfactants; fluorine-based surfactants; etc. Among these, acetylene surfactants are preferably used.

[0046] Examples of the acetylene surfactant include an acetylene glycol surfactant, an acetylene alcohol surfactant, and a surfactant having an acetylene group. The acetylene glycol surfactant is a glycol having an acetylene group, preferably a glycol having a symmetrical structure with the acetylene group located in the center, and may have a structure in which ethylene oxide is added to acetylene glycol. Examples of commercially available acetylene surfactants include the Surfynol series manufactured by Evonik Industries ("Surfynol 104E," "Surfynol 104H," "Surfynol 420," "Surfynol 440," "Surfynol 465," "Surfynol 485," etc.) and the Olfin series manufactured by Nissin Chemical Industry Co., Ltd. ("Olfin E1004," "Olfin E1010," "Olfin E1020," etc.).

[0047] Examples of silicone surfactants include polyether-modified silicone surfactants, alkyl-aralkyl co-modified silicone surfactants, acrylic silicone surfactants, etc. Commercially available silicone surfactants include "Silface SAG002" and "Silface SAG503A" manufactured by Nissin Chemical Industry Co., Ltd. (both are trade names).

[0048] Other nonionic surfactants include polyoxyethylene alkyl ether surfactants such as the Emulgen series manufactured by Kao Corporation (Emulgen 102KG, Emulgen 103, Emulgen 104P, Emulgen 105, Emulgen 106, Emulgen 108, Emulgen 120, Emulgen 147, Emulgen 150, Emulgen 220, Emulgen 350, Emulgen 404, Emulgen 420, Emulgen 705, Emulgen 707, Emulgen 709, Emulgen 1108, Emulgen 4085, Emulgen 2025G, etc.) (all trade names).

[0049] The non-white ink preferably contains a surfactant, and the content of the surfactant in the non-white ink may be, for example, in the range of 0.01 to 10% by mass relative to the total amount of the non-white ink.

[0050] The method for producing the non-white ink is not particularly limited, and the ink can be produced by a general method for producing non-white ink. For example, all components are added to a mixer such as a Three-One Motor all at once or in portions, and dispersed, and if desired, the mixture is passed through a filter such as a membrane filter to obtain an ink.

[0051] The pH of the non-white ink may be, for example, in the range of 7.0 to 10.0 from the viewpoint of storage stability of the ink. Furthermore, when the non-white ink is an inkjet ink, the viscosity thereof may be, for example, in the range of 1 to 30 mPa s at 23°C from the viewpoint of inkjet ejection properties.

[0052] In one embodiment, the ink set includes at least one of a white ink and a clear ink. The type of white ink that can be included in the ink set is not particularly limited, and a wide variety of inks can be used. For example, the white ink may be a water-based inkjet ink.

[0053] The white ink contains a white colorant. One type of colorant may be used alone, or two or more types may be used in combination. Examples of the colorant include various white pigments, such as white inorganic pigments such as titanium oxide, zinc oxide, zinc sulfide, antimony oxide, and zirconium oxide. Among these, titanium oxide is preferably used from the viewpoint of hiding power. The average particle diameter of the titanium oxide is not particularly limited, but may be, for example, in the range of 100 to 600 nm. For the white ink, a pigment dispersion in which the pigment is dispersed in advance with a pigment dispersant, or a pigment dispersion dispersed with a pigment dispersant described below, may be used.

[0054] The content of the white pigment in the white ink is not particularly limited, and can be in the same range as that of a general white ink. For example, it may be 1% by mass or more, 3% by mass or more, or 5% by mass or more, based on the total amount of the white ink. It may also be 30% by mass or less, 20% by mass or less, or 15% by mass or less. The content of the white pigment relative to the total amount of the white ink may be, for example, in the range of 1 to 30% by mass.

[0055] Various pigment dispersants may be used to stably disperse the white pigment in the white ink. One type of pigment dispersant may be used alone, or two or more types may be used in combination. Examples of pigment dispersants include those exemplified as pigment dispersants that may be contained in non-white inks.

[0056] When a pigment dispersant is used, the amount of pigment dispersant added in the white ink is adjusted appropriately depending on the type of white pigment and pigment dispersant, but may be, for example, in the range of 0.5 to 50 parts by mass per 100 parts by mass of pigment.

[0057] The white ink preferably contains a resin. One type of resin may be used alone, or two or more types may be used in combination. The content of the resin in the white ink is adjusted appropriately depending on the desired viscosity, etc., but may be, for example, in the range of 3 to 30 mass %.

[0058] The type of resin is preferably one that can form a transparent coating film, as this results in a white ink with better color development. Specific examples of the resin include those exemplified as resins that can be contained in non-white inks.

[0059] The white ink may contain other components in addition to the white pigment and resin, such as organic solvents, water, surfactants, pH adjusters, dispersants, fixing agents, and preservatives.

[0060] The type of organic solvent is not particularly limited, and a wide variety of organic solvents commonly used in the ink field can be used. The content of the organic solvent in the white ink may be, for example, 1% by mass or more, 5% by mass or more, or 10% by mass or more. It may also be 50% by mass or less, 40% by mass or less, or 30% by mass or less. The content of the water-soluble organic solvent in the white ink may be, for example, in the range of 1 to 50% by mass.

[0061] Among organic solvents, it is preferable to include an organic solvent with a boiling point of 260°C or higher (high-boiling organic solvent). When at least one of the inks included in the ink set includes a high-boiling organic solvent, the adhesion of the powder is improved. Furthermore, when the white ink is an inkjet ink, including a high-boiling organic solvent makes it even less likely for the nozzles to clog when the printer is not in use. In one embodiment of the ink set for thermal transfer sheets, even when the white ink includes a high-boiling organic solvent, a thermal transfer sheet with excellent image reproducibility can be obtained by the action of the ink coagulation liquid.

[0062] The content of the high-boiling point organic solvent in the white ink may be, for example, 1% by mass or more, 5% by mass or more, or 10% by mass or more. It may also be 50% by mass or less, 40% by mass or less, or 30% by mass or less. The content of the high-boiling point organic solvent in the white ink may be, for example, in the range of 1 to 40% by mass.

[0063] The proportion of the high-boiling-point organic solvent in the total organic solvents in the white ink may be, for example, 10% by mass or more, 50% by mass or more, 70% by mass or more, 90% by mass or more, or even 100% by mass. The proportion of the high-boiling-point organic solvent in the total organic solvents in the white ink may be, for example, in the range of 10 to 100% by mass.

[0064] In one embodiment, when the white ink is aqueous, a water-soluble organic solvent can be preferably used as the organic solvent. Specific examples of the water-soluble organic solvent contained in the white ink include those exemplified as the water-soluble organic solvents that can be contained in the non-white ink. One type of water-soluble organic solvent may be used alone, or two or more types may be used in combination.

[0065] When the white ink is aqueous, it preferably contains a water-soluble organic solvent. The content of the water-soluble organic solvent in the white ink may be, for example, 1% by mass or more, 5% by mass or more, or 10% by mass or more. It may also be 50% by mass or less, 40% by mass or less, or 30% by mass or less. The content of the water-soluble organic solvent in the non-white ink may be, for example, in the range of 1 to 50% by mass.

[0066] The content of the water-soluble high-boiling-point organic solvent in the white ink may be, for example, 1% by mass or more, 5% by mass or more, or 10% by mass or more. It may also be 50% by mass or less, 40% by mass or less, or 30% by mass or less. The content of the water-soluble high-boiling-point organic solvent in the white ink may be, for example, in the range of 1 to 40% by mass.

[0067] The proportion of the water-soluble high-boiling-point organic solvent in the total water-soluble organic solvents in the white ink may be, for example, 30% by mass or more, 50% by mass or more, 70% by mass or more, or even 100% by mass. The proportion of the water-soluble high-boiling-point organic solvent in the total water-soluble organic solvents in the white ink may be, for example, in the range of 30 to 100% by mass.

[0068] The white ink may be aqueous. When the white ink is aqueous, the water contained therein may be, for example, ion-exchanged water, distilled water, or ultrapure water. The proportion of water relative to the total amount of the white ink is adjusted appropriately depending on the desired viscosity, etc., but may be, for example, in the range of 30 to 90% by mass.

[0069] The white ink preferably contains a surfactant. Specific examples of surfactants contained in the white ink include those exemplified as surfactants that may be contained in the non-white ink. The content of the surfactant in the white ink may be, for example, in the range of 0.01 to 10% by mass relative to the total amount of the non-white ink.

[0070] The method for producing the white ink is not particularly limited, and the white ink can be produced by a general method for producing a white ink. For example, all of the components are added together or in portions to a mixer such as a Three-One Motor, dispersed, and, if desired, passed through a filter such as a membrane filter to obtain an ink.

[0071] The pH of the white ink may be, for example, in the range of 7.0 to 10.0 from the viewpoint of storage stability of the ink. Furthermore, when the white ink is an inkjet ink, the viscosity thereof may be, for example, in the range of 1 to 30 mPa·s at 23°C from the viewpoint of inkjet ejection properties.

[0072] The type of clear ink that may be included in the ink set of an embodiment is not particularly limited, and a wide variety of inks may be used. As an example, the clear ink may be a water-based inkjet ink.

[0073] The transparent ink may be an ink that does not contain a colorant, or may contain a colorant to the extent that image reproducibility is not impaired. For example, the colorant may be contained in an amount of 0.1% by mass or less. The transparent ink preferably contains a resin that can form a transparent coating film. Specific examples of the resin include those exemplified as resins that can be contained in non-white ink.

[0074] The transparent ink may contain components other than the resin, such as organic solvents, water, surfactants, pH adjusters, dispersants, fixing agents, and preservatives.

[0075] The type of organic solvent is not particularly limited, and a wide range of organic solvents commonly used in the ink field can be used. When at least one of the inks included in the ink set contains a high-boiling-point organic solvent, powder adhesion is improved. Furthermore, when the clear ink is an inkjet ink, the inclusion of a high-boiling-point organic solvent further reduces nozzle clogging during periods when the printer is not in use. In one embodiment of the ink set for thermal transfer sheets, even when the clear ink contains a high-boiling-point solvent, the action of the ink aggregating liquid allows a thermal transfer sheet with excellent image reproducibility to be obtained.

[0076] In one embodiment, when the transparent ink is aqueous, a water-soluble organic solvent can be preferably used as the organic solvent. Specific examples of the water-soluble organic solvent contained in the transparent ink include those exemplified as the water-soluble organic solvents that can be contained in the non-white ink. One type of water-soluble organic solvent may be used alone, or two or more types may be used in combination.

[0077] The transparent ink may be aqueous. When the transparent ink is aqueous, the water contained therein may be, for example, ion-exchanged water, distilled water, or ultrapure water. The proportion of water relative to the total amount of the transparent ink is adjusted appropriately depending on the desired viscosity, etc., but may be, for example, in the range of 30 to 90% by mass.

[0078] In one embodiment, the ink set includes at least one of a white ink and a clear ink. The ink set may include both a white ink and a clear ink. For example, when the print medium is a low-lightness color such as black or navy blue, it is preferable that the ink set includes at least a white ink, as this enables image formation with better color reproducibility. On the other hand, when the print medium is a high-lightness color such as white, and it is desired to print part of the image transparently so that the color of the print medium shows through, the ink set may include either a white ink or a clear ink, or may include both.

[0079] The ink set of one embodiment includes an ink aggregating liquid. Specifically, the ink aggregating liquid includes an ink aggregating agent, and examples of the ink aggregating agent include metal salts, cationic polymers, and organic acids.

[0080] Examples of metal salts include metal salts composed of a metal ion and an anion. Examples of metal ions include Na + , K. + Monovalent metal ions such as Ca 2+ , Mg 2+ , Cu 2+ , Ni 2+ , Zn 2+ , Ba 2+ Examples of the anion include polyvalent metal ions such as Cl - , NO3 - , CH3COO - , I - , Br - , ClO3 - The metal salts may be used alone or in combination of two or more.

[0081] Examples of cationic polymers include polyallylamine, polyallylamine sulfate, polyallylamine hydrochloride, allylamine diallylamine copolymer, allylamine diallylamine copolymer sulfate, allylamine diallylamine copolymer hydrochloride, allylamine dimethylallylamine copolymer, allylamine dimethylallylamine copolymer sulfate, allylamine dimethylallylamine copolymer hydrochloride, diallylamine, diallylamine sulfate, diallylamine hydrochloride, methyl diallylamine amide, methyl diallylamine amide sulfate, methyl diallylamine amide hydrochloride, diallylamine sulfur dioxide copolymer, diallylamine sulfur dioxide copolymer sulfate, diallylamine sulfur dioxide copolymer hydrochloride, methyl diallylamine sulfur dioxide copolymer, methyl diallylamine sulfur dioxide copolymer sulfate, methyl diallylamine sulfur dioxide copolymer hydrochloride, polydimethyl diallyl ammonium chloride, etc. One type of cationic polymer may be used alone, or two or more types may be used in combination.

[0082] Examples of organic acids include formic acid, acetic acid, lactic acid, oxalic acid, citric acid, malic acid, ascorbic acid, etc. One type of organic acid may be used alone, or two or more types may be used in combination.

[0083] In particular, the ink condensate preferably contains a metal salt, and more preferably a polyvalent metal salt formed from a polyvalent metal ion and an anion, because this allows the production of a thermal transfer sheet with excellent image reproducibility. Examples of polyvalent metal salts include divalent metal salts such as calcium salts and magnesium salts.

[0084] The proportion of metal salt in the ink aggregating agent contained in the ink aggregating liquid is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. Alternatively, 100% by mass of the ink aggregating agent may be metal salt. Furthermore, the proportion of polyvalent metal salt in the ink aggregating agent is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. Alternatively, 100% by mass of the ink aggregating agent may be polyvalent metal salt.

[0085] The content of the ink aggregating agent in the ink aggregating liquid is adjusted appropriately depending on the type of ink aggregating agent, etc. For example, the content of the ink aggregating agent in the ink aggregating liquid may be 1% by mass or more, 10% by mass or more, or 20% by mass or more. It may also be 50% by mass or less, 45% by mass or less, or 40% by mass or less. The content of the ink aggregating agent in the ink aggregating liquid may be, for example, in the range of 1 to 50% by mass.

[0086] Furthermore, when the ink condensate contains a metal salt, the metal salt concentration in the ink condensate may be 0.1 mol / kg or more, 0.3 mol / kg or more, or 0.5 mol / kg or more. It may also be 10 mol / kg or less, 5 mol / kg or less, or 2 mol / kg or less. The metal salt concentration in the ink condensate may be, for example, in the range of 0.1 to 10 mol / kg.

[0087] The ink aggregating liquid may contain other components in addition to the ink aggregating agent, such as organic solvents, water, surfactants, pH adjusters, dispersants, fixing agents, and preservatives.

[0088] In one embodiment, when the inks contained in the ink set are aqueous, a water-soluble organic solvent can be preferably used as the organic solvent. Specific examples of the water-soluble organic solvent contained in the ink condensation liquid include those exemplified as the water-soluble organic solvents that can be contained in the non-white ink. One type of water-soluble organic solvent may be used alone, or two or more types may be used in combination.

[0089] The content of the water-soluble organic solvent in the ink condensate may be, for example, 1% by mass or more, 5% by mass or more, or 10% by mass or more. It may also be 50% by mass or less, 40% by mass or less, or 30% by mass or less. The content of the water-soluble organic solvent in the non-white ink may be, for example, in the range of 1 to 50% by mass.

[0090] The ink condensate may contain water. Examples of water include ion-exchanged water, distilled water, and ultrapure water. The water content of the ink condensate may be in the range of 10 to 90% by mass, for example.

[0091] The ink condensate preferably contains a surfactant. Specific examples of surfactants contained in the ink condensate include those exemplified as surfactants that may be contained in non-white inks. The content of surfactant in the white ink may be, for example, in the range of 0.01 to 10% by mass relative to the total amount of the ink condensate.

[0092] The method for producing the ink condensate is not particularly limited. For example, all components are added to a stirrer such as a Three-One Motor all at once or in portions, and dispersed, and if desired, the ink condensate can be obtained by passing the mixture through a filter such as a membrane filter.

[0093] A thermal transfer sheet using an ink set according to one embodiment can be produced, for example, by applying the inks and ink aggregating liquid contained in the ink set onto a substrate sheet.

[0094] The type of substrate sheet is not particularly limited, and may be any sheet that can be printed using the ink set of one embodiment, is resistant to the pressure and temperature conditions during thermal transfer, and is peelable after transfer. An ink-receiving layer, an easily peelable layer, or the like may be provided on the printing surface of the substrate sheet. Specific examples of the substrate sheet include those that are commonly used as substrate sheets for DTF printing.

[0095] Examples of the order in which the inks and ink condensate contained in the ink set are applied include non-white ink, ink condensate, and white or clear ink, ink condensate, non-white ink, and white or clear ink, and non-white ink, white ink, and ink condensate. Among these, the order of non-white ink, ink condensate, and white or clear ink, or ink condensate, non-white ink, and white or clear ink is preferred, as this allows for the production of a thermal transfer sheet with superior image reproducibility.

[0096] When the order is non-white ink, ink condensate, and white or transparent ink, the dot size of the non-white ink tends to be large, resulting in good solid coverage and high image density even when printed at low resolution.On the other hand, when the order is ink condensate, non-white ink, and white or transparent ink, the dot size of the non-white ink tends to be small, resulting in less distortion of fine characters and thin lines and easier production of sharp images even when printed at high resolution.

[0097] When applying each ink and ink condensate onto the substrate sheet, a drying step may be performed after each application of the ink and ink condensate, or the inks may be applied successively using a so-called wet-on-wet method without performing a drying step. In one embodiment, even when the inks and ink condensate are applied using a wet-on-wet method, the ink set provides a thermal transfer sheet that is less likely to cause color mixing and has excellent image reproducibility.

[0098] When the inks and ink condensate are applied by a wet-on-wet method, the amount of volatile matter remaining in the previously applied ink or ink condensate when the subsequently applied ink or ink condensate is applied may be, for example, 50% by mass or more, 75% by mass or more, or 90% by mass or more. The time interval between application of the inks and ink condensate is preferably 0.1 to 200 seconds.

[0099] One embodiment of a method for producing a thermal transfer sheet (hereinafter sometimes referred to as "production method 1") includes a step (step A) of sequentially applying a non-white ink, an ink condensate, a white ink, and / or a transparent ink onto a substrate sheet using a wet-on-wet method.

[0100] Another embodiment of a method for producing a thermal transfer sheet (hereinafter sometimes referred to as "production method 2") is a method for producing a thermal transfer sheet, which includes a step (step B) of sequentially applying an ink condensate, a non-white ink, a white ink, and / or a transparent ink onto a substrate sheet using a wet-on-wet method.

[0101] The method for applying the inks and ink condensate onto the substrate sheet is not particularly limited, and various printing methods such as screen printing, roller printing, and inkjet printing can be used. In one embodiment, the inks and ink condensate may be applied by inkjet printing, from the viewpoints of enabling efficient production of the thermal transfer sheet and facilitating control of the amount of each component applied. The type of inkjet method is not particularly limited, and may be any method such as a piezoelectric method, an electrostatic method, or a thermal method. The application of the inks and ink condensate by the inkjet method can be carried out, for example, by using a general inkjet printer, ejecting droplets from an inkjet head based on a digital signal, and allowing the ejected droplets to adhere to a cloth.

[0102] The amounts of each ink and ink condensate applied can be adjusted as appropriate depending on the type of base sheet, the design of the printed image, etc. The amounts of each ink and ink condensate applied are basically not affected by the order in which the inks and ink condensate are applied, and for example, the amounts of each ink and ink condensate applied in Production Method 1 and Production Method 2 may be the same.

[0103] The amount of non-white ink applied can be adjusted appropriately depending on the type of substrate sheet, the design of the printed image, etc. The amount of non-white ink applied is, for example, 5 to 50 g / m 2 may be in the range of

[0104] The amount of ink aggregating liquid applied can be adjusted appropriately depending on the type of substrate sheet, the design of the printed image, etc. The amount of ink aggregating liquid applied is, for example, 0.5 to 30 g / m 2 In one embodiment of the method for producing a thermal transfer sheet, the amount of ink aggregating liquid applied is set to 20 g / m because the stickiness of the thermal transfer sheet is reduced and handling is easy. 2 Preferably, it is 15 g / m or less. 2 Furthermore, the amount of ink condensation liquid applied is preferably 10 g / m or less, since cracking of the image on the thermal transfer sheet is less likely to occur.2 It is particularly preferred that:

[0105] The amount of white / transparent ink applied can be adjusted as appropriate depending on the type of substrate sheet, the design of the printed image, etc. The amount of white / transparent ink applied is, for example, 5 to 300 g / m in total. 2 Furthermore, since the thermal transfer sheet has high transferability regardless of the type of print medium, and is less likely to become stiff even when the print medium is fabric, when applying powder, it is preferable to apply the powder in an amount of 5 to 200 g / m 2 The range is preferably 10 to 150 g / m 2 is more preferred. If no powder is applied, the recommended dose is 50-300g / m 2 The range is preferably 75 to 250 g / m 2 is more preferred.

[0106] The ratio of the amount of ink condensate applied per unit area to the total amount of white ink and clear ink applied per unit area (hereinafter, this value may be referred to as the "X value") may be 0.6 or less. In one embodiment of the method for producing a thermal transfer sheet, the X value is preferably 0.3 or less, since this reduces stickiness of the thermal transfer sheet and makes it easier to handle. The X value may be, for example, in the range of 0.01 to 0.3.

[0107] Production method 1 and production method 2 may include a step of applying powder (step P) in addition to step A or step B. Step P is preferably performed after the application of each ink and ink aggregating liquid, i.e., after step A or step B. In a more preferred embodiment, when at least one of the inks and ink aggregating liquid contains a high-boiling point solvent, the adhesion of the powder is further enhanced. Even in this case, the fluidity of the white ink or clear ink is reduced by the ink aggregating liquid contained in the ink set of one embodiment, so the powder does not absorb too much ink.

[0108] The type of powder is not particularly limited, and examples thereof include hot melt powder and foam powder. The powder may be hot melt powder, and the use of hot melt powder further improves the fastness of the transferred product. The type of hot melt powder is not particularly limited, and for example, various resin powders that are solid (powder) at room temperature and can be melted by heating at about 90 to 160°C can be used. The particle size of the hot melt powder is not particularly limited, and for example, the average particle size may be in the range of 100 to 300 μm. Specific examples of hot melt powder include those that are commonly used as hot melt powders for DTF printing.

[0109] The application of the powder is preferably carried out before the areas where the inks and ink condensate have been applied dry. For example, the amount of volatile matter remaining in the areas where the inks and ink condensate have been applied at the time of powder application may be 50% by mass or more, 75% by mass or more, or even 90% by mass or more. The time interval between the completion of application of all the inks and ink condensate and the application of the hot melt powder is preferably 0.1 to 200 seconds.

[0110] The amount of powder applied is not particularly limited, but may be, for example, 10 to 200 g / m 2 and may be in the range of 20 to 100 g / m 2 The powder may be in the range of 0.01 to 0.05. It is preferable to apply the powder uniformly and evenly to the areas where the inks and ink condensate are applied so that no image omissions occur during transfer. The powder can be applied, for example, by scattering an excess amount of powder on the areas where the inks and ink condensate are applied, applying the required amount, and then removing the excess.

[0111] The method for removing excess powder is not particularly limited, and examples thereof include a method of shaking it off, and a method of scattering it by generating an air current using an airbrush or the like.

[0112] When a hot melt powder is used as the powder, the hot melt powder may be melted by heating after application, or the powder may be left as is to obtain a thermal transfer sheet without being melted. When melting the powder, the heating temperature and heating time are appropriately adjusted depending on the melting point of the hot melt powder, but for example, heating may be performed at a temperature range of about 90 to 160°C for about 0.5 to 10 minutes. After heating, a cooling step may be performed. Cooling methods include, for example, air cooling and cooling with a cooler.

[0113] One embodiment of the method for producing a transfer printed material involves overlaying a thermal transfer sheet obtained by one embodiment of the method for producing a transfer printed material on a printing medium, heating it to transfer an image, and then peeling off the base sheet.

[0114] The printing medium is not particularly limited as long as it is a medium that can be thermally transferred using a press or the like, and examples thereof include cloth, vinyl sheet, etc. The cloth is not particularly limited, and a wide variety of materials can be used. Examples of fibers that make up the cloth include natural fibers such as cotton, silk, wool, and linen; chemical fibers such as polyester, acrylic, polyurethane, nylon, rayon, cupra, and acetate; and blends of these fibers. Examples of types of fabric include woven fabrics, knitted fabrics, and nonwoven fabrics.

[0115] The conditions during transfer, such as pressure, temperature, and pressing time, are adjusted as appropriate depending on the type of printing medium, the type of hot melt powder, etc. For example, when using a FUSION heat press, the pressure condition may be in the range of 3 to 9 pr, the temperature condition may be in the range of 90 to 160°C, and the pressing time may be in the range of 5 to 30 seconds.

[0116] After the image is transferred, it is preferable to cool the transfer print to room temperature before peeling off the substrate sheet.

[0117] Some embodiments of the present disclosure are set forth below. <1> An ink set for a thermal transfer sheet, comprising a non-white ink, at least one of a white ink and a transparent ink, and an ink aggregating liquid.

[0118] <2> At least one of the non-white ink, the white ink, and the transparent ink contains an organic solvent having a boiling point of 260° C. or higher. <1> An ink set for a thermal transfer sheet according to the present invention.

[0119] <3> A method for producing a thermal transfer sheet, comprising a step (step A) of applying a non-white ink, an ink condensate, a white ink, and / or a transparent ink to the surface of a substrate sheet in this order by a wet-on-wet method.

[0120] <4> A method for producing a thermal transfer sheet, comprising a step (step B) of applying an ink condensate, a non-white ink, a white ink, and / or a transparent ink to the surface of a substrate sheet in this order by a wet-on-wet method.

[0121] <5> At least one of the non-white ink, the white ink, and the transparent ink contains an organic solvent having a boiling point of 260° C. or higher. <3> or <4> A method for producing the thermal transfer sheet according to claim 1.

[0122] <6> the ratio of the amount of the ink condensation liquid applied per unit area to the total amount of the white ink and the transparent ink applied per unit area is 0.3 or less; <3> ~ <5> 10. A method for producing a thermal transfer sheet according to any one of the preceding claims.

[0123] <7> The amount of the ink condensation liquid applied per unit area is 10 g / m 2 The above-mentioned <3> ~ <6> 10. A method for producing a thermal transfer sheet according to any one of the preceding claims.

[0124] <8> In addition to the step (A), the method includes a step (step P) of applying powder. <3> , <5> ~ <7> A method for producing the thermal transfer sheet according to claim 1.

[0125] <9> In addition to the step (B), the method includes a step (step P) of applying powder. <4> ~ <7> A method for producing the thermal transfer sheet according to claim 1.

[0126] <10> The powder is a hot melt powder. <8> or <9> A method for producing the thermal transfer sheet according to claim 1.

[0127] <11> The aforementioned <3> ~ <10> 1. A method for producing a transfer print, comprising: superposing a thermal transfer sheet produced by the method according to any one of 1 to 3 on a print medium; heating the sheet to transfer an image; and then peeling off the base sheet. [Example]

[0128] Hereinafter, embodiments of the present disclosure will be described in detail using examples. The present disclosure is not limited to the following examples. In the following description, "%" indicates "% by mass" unless otherwise specified. The content shown in each table indicates the total amount of raw materials blended as a solution, dispersion, etc.

[0129] [Manufacturing ink sets for thermal transfer sheets] Non-white inks 1 to 4, white ink 1, and ink condensate 1 were produced in the following manner, and used as an ink set for thermal transfer sheets.

[0130] [Production of non-white ink] The raw materials were mixed in the blending ratios shown in Table 1 and filtered through a cellulose acetate membrane filter with a pore size of 3 μm to obtain non-white inks 1 to 4.

[0131] [Table 1]

[0132] The details of the raw materials listed in Table 1 are as follows: Non-white pigment dispersion 1: Cabot Corporation "CAB-O-JET 300", black pigment dispersion, solid content 15% by mass Non-white pigment dispersion 2: Cabot Corporation "CAB-O-JET 250C", cyan pigment dispersion, solid content 10% by mass Non-white pigment dispersion 3: Cabot Corporation "CAB-O-JET 260M", magenta pigment dispersion, solid content 10% by mass Non-white pigment dispersion 4: Cabot Corporation "CAB-O-JET 270Y", yellow pigment dispersion, solid content 10% by mass Resin emulsion 1: "Movinyl 6775" manufactured by Japan Coating Resin Co., Ltd., urethane resin, solid content 38% by mass Glycerin: Water-soluble organic solvent with a boiling point of 290°C, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Diethylene glycol: Water-soluble organic solvent with a boiling point of 246°C, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Surfactant: Nissin Chemical Industry Co., Ltd.'s "Olfine E1010", an acetylene-based surfactant

[0133] [White ink manufacturing] The raw materials were mixed in the blending ratios shown in Table 2 and filtered through a cellulose acetate membrane filter with a pore size of 3 μm to obtain White Ink 1.

[0134] [Table 2]

[0135] Details of the raw materials listed in Table 2 are as follows: White pigment dispersion 1: 350 g of titanium dioxide ("R62N" manufactured by Sakai Chemical Industry Co., Ltd.) as a white pigment and 14 g (3.5 g of active ingredient) of pigment dispersant ("Demol EP" manufactured by Kao Corporation) were mixed with 636 g of ion-exchanged water, and the mixture was dispersed with 0.5 mm diameter zirconia beads using a bead mill ("DYNO-MILL KDL A" manufactured by Shinmaru Enterprises Co., Ltd.) at a filling rate of 80% and a residence time of 2 minutes to obtain a white pigment dispersion (pigment content 35% by mass). Resin emulsion 2: "Superflex 740" manufactured by Daiichi Kogyo Seiyaku Co., Ltd., urethane resin, resin content 40% by mass Resin emulsion 3: "Superflex 420" manufactured by Daiichi Kogyo Seiyaku Co., Ltd., urethane resin, resin content 32% by mass Glycerin: Water-soluble organic solvent with a boiling point of 290°C, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Surfactant: Nissin Chemical Industry Co., Ltd.'s "Olfine E1010", an acetylene-based surfactant

[0136] [Production of ink agglomerate] The raw materials were mixed in the blending ratios shown in Table 2 and filtered through a cellulose acetate membrane filter with a pore size of 3 μm to obtain ink condensation liquid 1.

[0137] [Table 3]

[0138] The details of the raw materials listed in Table 3 are as follows: Calcium chloride: Fujifilm Wako Pure Chemical Industries, Ltd. Diethylene glycol: Water-soluble organic solvent with a boiling point of 246°C, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Glycerin: Water-soluble organic solvent with a boiling point of 290°C, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Surfactant: Nissin Chemical Industry Co., Ltd.'s "Olfine E1010", an acetylene-based surfactant

[0139] [Examples 1 to 14 and Comparative Example 1] The non-white inks 1 to 4, white ink 1, and ink condensate 1 obtained above were used as an ink set for thermal transfer sheets to produce thermal transfer sheets and transfer printed matter in the following manner. The obtained thermal transfer sheets and transfer printed matter were subjected to various evaluations in the following manner. The results are shown in Tables 4 to 6.

[0140] [Thermal transfer sheet manufacturing] According to steps 1 to 3 in Tables 4 to 6, non-white inks 1 to 4, white ink 1, and ink condensate 1 were applied to a substrate sheet (*1) by a wet-on-wet method. The inks and ink condensate were applied by inkjet printing using an inkjet printer manufactured by Mastermind. Non-white inks 1 to 4 were applied as full-color image printing, and white ink 1 and ink condensate 1 were applied as solid image printing. The printed image used had a portion of the image where none of the non-white inks 1 to 4 was applied, and had a solid image portion of white ink 1 (hereinafter, this may be referred to as a "white solid image"). In Examples 1 to 12 and Comparative Example 1, after applying the ink and ink condensate, hot melt powder (*2) was applied and the excess was brushed off. Then, the sheet was left in a thermostatic bath at 130°C for 5 minutes to melt the hot melt powder and obtain a thermal transfer sheet. In Examples 13 and 14, after the ink and ink condensation liquid were applied, the sheet was left in a thermostatic chamber at 130° C. for 5 minutes to obtain a thermal transfer sheet.

[0141] Base sheet (*1): Premium film for DTF printing manufactured by Toyo Corporation Hot melt powder (*2): "ARTJET POWDER" manufactured by Matsui Pigment Chemical Industry Co., Ltd.

[0142] [Manufacturing transfer prints] The thermal transfer sheet obtained above was placed on a black cotton T-shirt (*3) so that the ink- or hot-melt powder-coated side of the transfer sheet was in contact with the T-shirt, and then heat-pressed using a FUSION heat press machine at a pressure setting of 9 pr, 140°C, and 20 seconds. After cooling to room temperature, the base sheet was peeled off to obtain a transfer print. Black cotton T-shirt (*3): "Printstar" manufactured by TMS Co., Ltd.

[0143] [Evaluation of color mixing on thermal transfer sheets] The thermal transfer sheet was visually inspected from the ink-attached side or the hot-melt powder-attached side, and evaluated according to the following criteria. A: There is no color mixing between the non-white inks 1 to 4 and the white ink 1, and image reproducibility is excellent. B: Mixture of non-white inks 1 to 4 with white ink 1 is observed in some parts of the image, but there is no significant deterioration in image reproducibility. C: Mixture of non-white inks 1 to 4 with white ink 1 is observed in part or the entire image, and image reproducibility is poor.

[0144] [Evaluation of cracks on thermal transfer sheets] The thermal transfer sheet was visually inspected from the ink-attached side or the hot-melt powder-attached side, and evaluated according to the following criteria. A: No cracks in the image, excellent image reproducibility B: There are cracks in some parts of the image, but there is no significant deterioration in image reproducibility. C: The image is partially or entirely cracked, and image reproducibility is poor.

[0145] [Evaluation of stickiness of thermal transfer sheets] The ink- or hot-melt powder-adhered surface of the thermal transfer sheet was palpated with a finger and evaluated according to the following criteria. A: There is no or very little residue on the fingers. B: There is some residue on the finger, but the amount is small. C: There is a lot of adhesion on the finger.

[0146] [Evaluation of uniformity of solid white images on transfer prints] The white solid image on the transfer print was visually inspected and evaluated according to the following criteria. A: The solid white image is uniform and consistent B: There is unevenness in the white solid image, but the color of the fabric does not show through. C: The solid white image is uneven and some of the fabric color shows through.

[0147] [Evaluation of image defects in transfer prints] The image on the transfer print was visually inspected to check for image defects.

[0148] [Table 4]

[0149] [Table 5]

[0150] [Table 6]

[0151] The X value (*4) in Tables 4 to 6 is (amount of ink aggregating liquid applied per unit area) / (total amount of white ink and clear ink applied per unit area).

[0152] In Examples 1 to 14, which used an ink set for thermal transfer sheets containing non-white inks 1 to 4, white ink 1, and ink condensate 1, both the thermal transfer sheet and the transfer prints exhibited excellent image reproducibility. Furthermore, there were no image defects in the transfer prints in Examples 1 to 14. In particular, Examples 1 to 8 and 10 to 14, in which the X value was 0.2 or less, exhibited high image reproducibility without the occurrence of cracks in the transfer sheet. In Comparative Example 1, which did not use ink aggregating liquid 1, color mixing was observed on the thermal transfer sheet, and the uniformity of the white solid image on the transfer print was low due to unevenness caused by the hot melt powder absorbing the white ink.

Claims

1. An ink set for a thermal transfer sheet, comprising a non-white ink, at least one of a white ink and a transparent ink, and an ink aggregating liquid.

2. 2. The ink set for a thermal transfer sheet according to claim 1, wherein at least one of the non-white ink, the white ink, and the clear ink contains an organic solvent having a boiling point of 260°C or higher.

3. A method for producing a thermal transfer sheet, comprising: a step (step A) of applying a non-white ink, an ink condensate, a white ink, and / or a transparent ink onto a substrate sheet in this order by a wet-on-wet method.

4. A method for producing a thermal transfer sheet, comprising: a step (step B) of applying an ink condensate, a non-white ink, a white ink, and / or a transparent ink onto a substrate sheet in this order by a wet-on-wet method.

5. The method for producing a thermal transfer sheet according to claim 3 or 4, wherein at least one of the non-white ink, the white ink, and the transparent ink contains an organic solvent having a boiling point of 260°C or higher.

6. 5. The method for producing a thermal transfer sheet according to claim 3, wherein a ratio of the amount of the ink aggregating liquid applied per unit area to the total amount of the white ink and the transparent ink applied per unit area is 0.3 or less.

7. The amount of the ink condensation liquid applied per unit area is 10 g / m ２ The method for producing a thermal transfer sheet according to claim 3 or 4, wherein the method is as follows:

8. The method for producing a thermal transfer sheet according to claim 3 , further comprising, in addition to the step (A), a step (step P) of applying a powder.

9. The method for producing a thermal transfer sheet according to claim 4 , further comprising, in addition to step (B), a step (step P) of applying a powder.

10. The method for producing a thermal transfer sheet according to claim 8 or 9, wherein the powder is a hot melt powder.

11. A method for producing a transfer printed matter, comprising: producing a thermal transfer sheet by the method described in claim 3, 4, 8 or 9; overlaying the thermal transfer sheet on a printing medium and heating it to transfer an image; and peeling off the base sheet.

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